第一篇：機械工程英語葉邦彥漢語翻譯第二部分
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PART 2 Unit 2 生產設備的數字控制
（1）數控是程序控制的自動化，在數字控制系統中，設備通過數字，字母和符號來編碼，以一種合適的格式為每一個特定的零件或工件定義一個程序指令集。當工件變化時，程序也變化，改變程序的能力也就是適合中小批量生產。寫一個新程序比改變大量生產設備要容易的多。
（2）基本結構：數控系統由下面三部分組成：1.控制程序；2.機器控制單元；3.加工設備。
三部分的基本關系，由圖2.1所示。程序輸入到控制單元由送入的程序來引導加工設備控制。
（3）指導程序是一步步詳細的指導加工設備的指令。通常指令把主軸上刀具相對于安裝工具的工作臺定位。更多先進的說明包括主軸的轉速，加工工具的選擇及其功能。程序刻在合適的介質中，提交到機器控制單元中，在過去幾十年中，最常用的介質是一英寸寬的打孔紙帶。由于打孔紙帶的廣泛使用，NC有時也叫紙帶控制，然而這是現代數控使用的誤稱。現在進入使用更多的是磁帶和軟盤。
（4）機器控制單元（MUC）由電子和控制硬件組成，機器控制單元可以讀出和執行指令程序，可以自動改變加工工具和其他加工設備。
（5）執行單元是數控系統的第三基礎部分，執行原件是有效執行工作的原件，最常見的數控例子其中的一個加工操作，加工設備由工作臺和主軸組成，就像用電動機來驅動一樣。加工設備由控制單元來驅動控制系統的類型。控制系統的類型
（6）數控有2種基本類型，點對點式和輪廓式控制，點對點式控制也稱定位控制，每個軸都是通過絲杠單獨驅動，根據加工類型不同，加工速度也不一樣。機器開始以最大速度運行來減少非加工時間，但當他達到數據定義的位置時，機器開始減速。因此在一個操作中，如鉆或沖孔操作先定位在加工。在鉆或沖孔之后，迅速收起工具移動到另一個位置重復此操作。從一個位置移到另一個位置是非常重要的，要遵循一個原則，從效率上考慮只要時間最短即可。點對點系統主要用于鉆，沖孔，直銑操作中。
（7）輪廓式也就是連續路徑式系統，定位和切削同時按不同速度來控制，由于刀具在指定路線運動同時切削，因此速度和運動的同步控制是非常重要的。輪廓式系統常用于車床銑床磨床焊接設備和加工中心。
（8）沿著路徑的運動或以增量差補是幾個基本方式的一個，在所有的差補中，要控制刀具的回轉中心定位，補償可以以不同直徑及刀具磨損，在數控程序中進行改寫。
（9）有一些已形成差補方案來處理數控系統中連續路徑和加工系統產生的問題包括：
1.線性差補；2.圓弧差補；3.螺旋線差補；4.拋物線差補；5.立體差補
（10）每一種差補程序都允許程序源產生加工指令，適用于相對少的輸入參數的直線或曲線路徑。儲存在數控單元中的模塊預算指引工具沿計算出的路徑運動。
（11）線性差補是最基本的差補方法，用于連續路徑的數控系統中。兩軸和三軸線性差補路線在實際中有時會分辨出的，但在概念上他們是一樣的，程序源要明確指定直線的起點和缺點及沿直線的進給率。差補需計算兩軸或三軸的進給速率以達到設定的進給速度。
（12）線性差補用來差補圓是不合適的因為程序源需要明確指定線段部分（線段數量）和各自的終點來大約模擬圓弧。圓弧差補法已形成他允許程序編程的路徑，使用圓弧只要給定以下參數，圓弧終點坐標，圓心坐標，半徑和刀具沿圓弧路徑的走刀方向。圓弧差補也是由許多小的直線段來實現的，但這些小線段的參數由差補模塊來計算出來的，而不是程序員設定的。切削是沿著每一小線段一個一個的進行以產生光滑曲線路徑。圓弧差補的局限性是圓弧路徑所在平面是由數控系統中兩軸所決定的平面。（13）螺旋線差補結合了環形差補兩軸在第三軸上做線性運動這樣來定義空間三維螺旋路徑。
（14）拋物線差補和立方差補法通過高次高程來實現自由曲線。這通常需要有強的計算能力，正因如此，他不如直線差補和環形差補常見。他們主要用于汽車工業中具有自由風格的車身面，而這是線性差補和圓弧差補不能精確容易得到的。
（15）數控技術運用于數控機床，這是數控的主要應用。現在主要用于商業。我們仍討論數控系統特別是金屬數控車床。數控車床技術
（16）種加工過程都可以在設計的專門車床上來實現加工。在車床上車削，在鉆床上鉆，在銑床上加工。有幾種類型的磨削方法也要有相應種類的磨床。被設計的數控磨床可以進行下列加工包括：1.鉆加工；2.銑床立式和臥式主軸；3.車床臥式主軸和立式主軸；4.臥式和立式鏜床；5.仿形銑床；6.平面磨和圓柱磨
（17）除了上述幾種機械加工方法，數控機床可用于其他金屬加工過程包括：用于薄片板的金屬板上沖孔的沖壓機，用于薄片金屬
彎曲的折彎機。
（18）數控技術的介入到機加工對機床的設計和運用有著顯著的影響。數控影響之一在程序控制下切削金屬的時間與傳統手動機床大得多。所以對于一些零件如主軸驅動主軸絲杠磨損更快，這些零件要設計成持續時間長的。第二，增加電子控制單元后設備成本也隨之增加，因此需要更高的利用率。取代傳統手工操作的一班制，數控機床通常采用兩班或三班制來獲得更多的回報。數控機床的設計中減少了非操作過程的時間如裝卸工件和換刀時間。第三，增加的勞動成本由人工成本變為設備成本。考慮到人工操作的角色，角色由技術熟練的工人控制，工件生產的每一個過程變為只控制裝卸換刀和清除碎屑和類似的操作，這樣一個工人可以同時操作兩臺或三臺車床，機床的角色和功能也改變了。數控需要設計成高度自動化具有需要在不同車床加工幾種操作聯合在一起一定加工的能力，這些變化是通過一種新型車床在數控技術存在之前是不存在的，他豐富了數控加工中心
（19）加工中心是在20世紀50年代發展起來的具有在程序控制下在一個工件上一次裝夾完成幾種不同的加工能力的機床。加工中心能完成銑，鉆，鉸屑，攻絲，鏜，車端面及一些類似機加工工作。另外數控加工中心的典型特征包括以下方面：
（20）(1)自動換刀能力: 多種機加工工作一位著需要多種刀具。刀具貝安裝在刀庫或多刀刀庫中。當一把刀需要被調換時，多刀刀座自動旋轉到相應的位置上。自動化的換刀機構。在程序控制下進行，把主軸上需換下的刀和多刀刀座上的刀調換。（21）(2)工件的自動定位: 大多數加工中心都可以使工件沿著主軸旋轉因此允許刀具達到工件的四個表面。
（22）(3)托架滑動裝置（平板架）: 加工中心另一個特點是有兩個或多個獨立拖板每個拖板都可以調整在刀具上。在加工過程中，一個拖板在刀具的前部，另一個拖板在遠離主軸的安全位置。這樣當機床正在加工當前的零件時。操作人員就可以從上一個工作循環中卸下最終加工好的零件，同時加緊毛坯用于下一個工作循環。
（23）加工中心可以分為立式和臥式。這是參照機床主軸方向來劃分的。立式加工中心具有軸線相對工作臺垂直的主軸，臥式車床的主軸軸線是水平方向的。這種區別通常會導致在這些加工中心加工的零件類型不同。立式加工中心用于以上進刀的平面工作。臥式加工中心用于立體形狀，刀具在立體側面可以進刀。一臺數控臥式加工中心，例子如圖2.2所示，具有上面提到的一些特征。（24）加工中心的成功應用導致了其他類似金屬加工機床的發展。例如：在車削中心，把車削加工設計成一個高度自動化萬能機床可以完成車削，刨，鉆，螺紋加工和類似的操作 DNC AND CNC（25）數控的發展在分批生產和小批量生產中有著重要意義，從技術和商業角度來說都有著重要意義。數控有兩方面的提高和擴展，包括：1.直接數據控制；2.計算機數字控制（26）直接數據控制
直接數據控制定義為一個制造系統，一定數量的機床有一臺計算機通過直接硬件連線實時控制。相應的磁帶播放機忽略在直接數控中，這樣就消除系統中最不可靠的環節。不用磁帶播放機而用電腦信息傳給車床。原則上說一臺計算機可以控制100臺獨立機器（DNC系統在1970年稱為可控制26臺機床）直接數控（DNC）電腦設計成在需要的時候提供指令給每一臺機床，當機床需要控制指令時，計算機立即發送指令給機床。
（27）圖2.3說明了DNC的基本配置。這個系統包括4部分：
1.中央計算機；2.大量內存，用于存放數控程序；3.通信線；4.機床刀具
（28）計算機從海量內存中取出部分程序指令送入到需要的獨立機床中。相應的計算機也接受機床反饋信息。這種雙工的信息流在實時控制加工系統中出現意味著每臺機床需要指令的請求能立即得到回應。類似的，計算機必須總是要準備要接受信息和進行回應。DNC系統顯著特點是：可以實時控制大量機床。更具機器數量和所需的計算機程度化。有時需要使用衛星計算機如圖2.4所示。衛星計算機是更小的計算機，可以分擔中央計算任務，減輕其負擔。每臺衛星控制幾臺機床。零件加工指令程序由計算機接受，儲存在內存中。當需要時衛星計算機發送指令程序到每個獨立機床中。來自機床的反饋數據在電腦中央存儲接受之前存儲在衛星內存中。（29）計算機數字控制
由于DNC技術的介入，在計算機技術上得到了很大的發展。計算機在尺寸和成本顯著減少的同時，計算機的能力卻有很大的提高。在數控中，這些發展使得由硬件布置的MCU（）變為數字電腦控制的控制單元。最早，小型機在1970年使用。隨著計算機進一步小型化，小型機被當今的微型機取代。
（30）計算機控制也是一種數字控制，它采用微型計算機作為控制單元。由于數字電腦用于CNC 和DNC中，只近似區分兩種類型。有三個區分原則：
1）.DNC電腦接受和發送指令數據都是來自許多機器，CNC電腦控制只是一個機器或多個機器。2）.DNC電腦占有一個位置通過控制來實現機器的旋轉。CNC電腦要非常靠近車床。
3）.DNC軟件的發展不經可以控制生產設備的每個單獨零件，還可以在生產堅固性方面提供主要控制信息。CNC的提高可以提高特殊車床的能力。
（31）電腦數控系統的大體配置如圖2.5所示。如圖中所示，最初進入控制器的是磁帶播放機。這樣，CNC的外部系統與傳統的NC機相似。然而CNC中的程序使用方法是不同的。
PART 2 Unit 4 機加工與切削加工中心
（1）這篇文章介紹了計算機控制的機械刀具設計的能力和較大的發展，就想我們知道的機加工和切削加工中心，這些機器有其他機器工具沒有的柔性和多功能性，應此他們作為加工工具第一選擇。機加工與切削加工中心
（2）需要注意的是每臺機器他的自動化程度有多高，都要設計一種基本的加工樣式就像所展示的那樣，在制造過程中不同的表面是用不同的加工方法加工的，（3）例如，如圖4.3所示，銑、端面車削、鏜、鉆、鉸孔、切絲來獲得額定的公差要求及最終表面精度。
（4）習慣性的加工過程的執行，始于工件的移動從一把加工刀具到另一把加工刀具直至所有的加工完成，這是一種切實可行的制造方法，并具有高度的自動化。這就是生產流水線的原理。最常見的是應用于高容量或大批量的生產，生產流水線是由幾種加工刀具按一定的次序排列組成的，諸如自動發動機模塊這樣的工件從一個加工地點到另一個加工地點，并且在每一個加工中心都運用特有的加工方式進行加工，工件會被輸送到下一個機器進行下一個加工。
（5）有這樣一些產品或加工方法，他們的生產路線是不可行或不經濟的，特別是當這些種類的產品在加工時需要迅速轉換加工方法。一個重要的概念，在20世紀50年代末期得到發展，那就是機加工中心。一個機加工中心就是運用計算機控制的刀具在工件的不同表面和不同的方向上進行切削操作的能力，通常說工件是不動的，而切削工具進行旋轉，比如銑和鉆操作。
（6）機加工中心的發展暗示著計算機控制的機器刀具之間關系的進步。如數字控制的車床加工中心擁有兩個轉臺帶動幾把切削刀具進行車削，端面車削，鏜孔和切螺紋。
（7）工件在加工中心里是被安放在托盤上或模塊上，那樣可以被移動并且可以進行不同方向的旋轉和定位，在進行特殊的切削過程完成后，工件不需要移動到另一臺機器進行鉆孔，鉸孔，攻絲之類的附加加工。換句話說，工件和機器是被置于工件上的。（8）當所有的加工工作完成后，托盤會自動離開已加工工件，并且另一個托盤運用自動托盤變速器將工件進行定位和加工。所有的傳動機構都有計算機控制，并且托盤定位器有10-30秒的循環時間，托盤臺能夠使得多級托盤更好的服務于加工中心，工具同樣能夠被裝備到不同的自動化部件中，諸如上料與下料機構。
（9）加工中心裝備了可變程序的自動刀具變換器，依賴于這樣的設計多達200把切削刀具能夠被貯存在刀庫，刀鼓，刀鏈（工具庫），輔助工具庫能夠更好的為一些特殊加工中心提供更好的切削道具，這些刀具可以自動的任意選擇到達機械主軸的最短路線，刀具交換臂是一個普通的設計機構，他可以旋轉來拾取特殊的工具（每一個工具有他自己的刀桿）和他在主軸上的位置。（10）刀具通過直接連接在刀具夾持口上的編碼標簽、條形碼或記憶芯片來標識。一次換刀時間在5-10秒鐘，對于小的刀具可以少于1-2秒，對于重達110公斤的刀具可以達到30秒，刀具變換器的設計趨勢趨向于運用簡單的原理提高換刀的時間。
（11）加工中心同時裝備有工具的檢驗臺，他可以給計算機數字控制提供信息對于在換刀和刀具磨損時的誤差提供補償。接觸試探針可以自動裝入工具夾持口中以確定工件的參考平面，以便對刀具設置進行選擇并對加工的工件在線檢測。
（12）圖4.6所示的一些表面可以被聯系起來，他們的相對位置可以被確立并儲存在計算機軟件的數據庫中，這些數據稍后可被用于編寫刀具工作路徑的程序同時對刀具的長度和直徑進行補償，又可以為預先加工刀具的磨損提供補償。機加工與切削加工中心的種類
（13）盡管這里有不同種類的刀具設計在加工中心中，兩種最基本的種類垂直主軸和水平主軸；大部分的機器擁有上述兩種軸線的能力，在加工中心中最大的切削刀具的尺寸可以繞工具一周，就像我們知道的工具包絡，這個術語第一次應用在與工業機器人的聯系上。
（14）垂直主軸加工中心或是水平主軸加工中心都是為了適用在工件具有深腔的平面上執行加工工藝，如鑄型和模具制造。一個垂直主軸的加工中心類似于一個垂直主軸銑床。刀庫在圖示的左側并且所有的加工方法和傳動機構通過位于右側的計算機控制托盤進行定位和修改。
（15）因為在加工中心中由于推力的作用方向是向下的，機器具有高的剛度，并在對于加工部分有較好的精確補償，這些機器通常比水平主軸的機器便宜些。
（16）水平主軸的加工中心或水平機加工中心是為了適用于高大工件的表面加工的需求。托盤可以在不同的軸線（如圖4.3所示）上旋轉來進行不同種類的有角定位。
（17）水平主軸加工的另一個范疇是車削加工，是用特殊機床進行計算機控制的車削加工。一個三轉動架的計算機數字控制的車削加工如圖4.8所示，這個機器是由兩個水平主軸和三個轉動架以及不同的切削刀具設計而成的來執行一些旋轉工件的加工。
（18）萬能加工中心同時裝備了垂直主軸和水平主軸的機器，他們具有不同種類的特色，并且具有加工所有表面的能力（垂直的、水平的、斜的）。機加工中心的特征和能力
（19）下面是加工中心的大部分特征：
a．他們有能力有效的，經濟的并且擁有重復的高精度的尺寸的能力來處理不同型號的磨具的能力。公差的范圍在正負0.0025mm。b．這些機器是萬能的，擁有多達6條線性的有角傳動的軸線并且有能力快速的從一種加工方式向另一種加工方式轉變來滿足不同種類的加工刀具和有效的減小地板空間。
c．裝載工作和卸載工作，轉換刀具，矯正，故障尋找所需的時間正在減少，應此生產能力提高，減少實驗的需求尤其是對于熟練實驗的要求并且生產成本降到最低。
d．他們可以高速的自動化并相對地緊湊，應此一個工作人員可以在同一時間照顧到兩臺或更多的機器。e．加工機器裝備了刀具調節監測裝置為了檢測出工具的磨損與破裂，又可以探測工具磨損的補償和工具調位。f．前處理和后處理的矯正和工件加工監測在加工中心的功能。
（20）加工中心可應用于更廣闊范圍的不同種類型號和特征，并且他們的成本范圍從5萬到100萬甚至更高。典型容量范圍可達75KW，并且最小軸轉速通常在4000-8000rpm范圍里，一些可以達到75000rpm，還用于小補償切削的特殊應用。一些托盤具有支撐重達7000kg工件的能力，通常高的容量用于特殊的應用當中。
（21）現在大部分機器有一個標準組件的基準構造，應此不同種類的外圍裝備和附件可以被安裝并且和修改不同種類產品的修改要求。
（22）因為加工中心的高生產能力，大量的切削會產生并且必須被收集起來應此一些需要一些可用于切削收集處理的設計，就像圖示所舉例那樣，兩個在橫軸加工中心截面圖底部的切削傳送帶這些特殊的加工傳送帶是螺旋形或螺桿型，他們沿著導槽收集切削并且將他們輸送到收集點，另一條系統會選用鏈式傳送帶。刀具的選擇
（23）加工中心能夠有能力需求有效的花費可以說進行有效的成本控制，他們通常不得不每天做至少兩次移動，所以他們必須有效并且可以連續調整在加工中心中產品的購買需求，因為他們固定的多功能性，但是加工中心可用于及時的制造大范圍的特殊產品。（24）種類的選擇和加工中心的尺寸依賴于以下幾種因素。
a．產品的種類，尺寸和模具的復雜性。
b．加工方法的種類及執行方式和切削工具的需求次數。c．精確補償的需求。d．生產速率的需求。
（25）盡管多功能性是選取加工中心的一個關鍵因素，我們必須考慮到權衡高成本高精度需求和比較在運用傳統加工工具制造相同產品時的成本。
UINIT 4鑄造工藝
引言
1鍛造是一種重要的成型加工工藝。可以用來生產各種形狀和尺寸的零部件，這些零部件從非常小的到重達幾噸的。2鍛造是把金屬加熱并且在合適的壓力下使其塑性變形而成型的一種加工。通常這個壓力是通過電錘或壓力機的錘頭打擊面形成，如圖4.1所示。
3手工鍛造工具包括各種形狀的錘子。在鑄造過程中用來支撐工件的支座是砧座。
4對于半機械化鑄造的小型和中型的零件，鑄造錘所使用的各種動力都用共同的特點，例如手工鑄造錘，他們利用它下落時的重力來提供金屬成型時所需要的壓力。大型零件的鑄造是通過蒸汽或被壓縮空氣或液壓或電力來提供鑄造壓力的。大型自動化鍛造設備是用來生產大批量的工程部件。
5開模鍛比如通常使用錘鍛及閉模之間的差別。在錘鍛中，組件是通過錘子的撞擊和輔助的簡單工具成型的。他們包括開式模具，即不會完全把金屬封閉起來的成型。錘鍛一種最基本的操作拔長是通過錘子的撞擊金屬拉伸片狀金屬，從而使金屬變得又薄又長。在手工鍛造中，工件在撞擊下要旋轉90°，從而可以完全鍛造并阻止其側面的進一步變形。與拔長相反的是鐓鍛，它能使壓縮方向縮短。例如，將棒料加熱并進行軸向捶打，其直徑即可增大。
6閉模鍛造廣泛應用于大量的工業生產中，金屬的成型是被壓入一對鍛造模中而完成的。上模通常與鍛造壓力機的撞擊工具或鍛錘相連接，下模是固定的。把他們結合在一起就形成了閉模。閉模鍛造可以生產非常復雜和精度很高的組建，他們與傳統的加工方法相比可得到更好的加工表面。磨具通常是由耐熱和耐磨材料制作而成的。將一塊大小足以填充模腔并能稍溢出的金屬放入底模，并將頂模加壓合攏。這塊金屬便獲得該模腔的形狀。閉模鍛造通常用來加工連續加工的小工件或非常大的工件。對于后者的加工，例如噴氣式飛機的組件，要使用很大的能產生5000噸或更多壓力的水壓機來提供壓力。
7一種特殊貴重的鍛造可以通過完善結構，均勻工件來改善金屬的強度；因此對于重型鍛造，；例如螺旋槳，有時要用10000噸的水壓來擠壓金屬件。盡管水壓鍛機的比落錘鍛造設備要貴的多，但它們可以給大型部件提供更大的壓力和更均勻的組織。對于高壓和擠壓操作還要注意，它的操作場合比落錘鍛造要低噪音少震動。對于重達30噸或更多的鑄塊須用機械鍛造來完成加工，手工加工是無法完成的。
8鍛造細化晶粒結構，提高金屬的物理性能。合適的設計可以使晶粒流動方向與實際使用時的主應力方向一致。如圖4.2所示，在塑性變形時晶粒沿木模方向流動。物理性能如強度韌性在鍛造中要比未鍛造要好的多。在未鍛造時，晶粒是任意方向的。
9鍛件每一部分都是一致的，沒有孔，空缺，夾雜物質及其他缺點。因此，最終加工如機器加工不存在孔，因為里面不存在空隙。操作的薄層如盤狀或直的，使工件有光滑表面。
10已鍛部件小重量就有一個很高的強度，因此用于飛機支架設計。
11鍛造金屬可導致下面幾方面：1）長度增加，橫截面減小，稱為拔長。2)長度減小。。12上述鍛造使晶粒流動，形成高強度零件。13金屬可以熱鍛也可以冷鍛。14
第二篇：機械工程英語翻譯機械工程英語第二部分翻譯[范文模版]
Unit 1 1中央控制單元（CPU）的功能是控制所有系統部件的運行和對數據進行數字的或是邏輯的操作。為了完成上述功能，CPU由以下兩個單元組成
2． 控制單元 ． 數字邏輯單元
3控制單元通過程序指令來協調大量的特種操作，這些操作包括接受輸入計算機的數據，并決定和是以何種方法來處理這些數據。控制單元能指揮數字邏輯單元的操作，他把數據發送給ALU來告訴ALU根據這些數據該運行什么功能，并且在哪里把結果存儲下來。控制單元完成上述操作的能力基于其安裝了一個具有儲存與記憶功能的總控程序機構。
4數字邏輯單元運行諸如加減比較之類的操作。這些操作是根據數據以二進制的形式表現出來的。在指示了確定的條件下，邏輯部也可以用來改變命令執行的次序。此外，邏輯部分還具有編輯或清除數據等功能。
5控制單元和數字邏輯單元都是得用寄存器來完成他們的功能的，計算機寄存器是一個可以接收短暫存儲，轉移數據的小記憶裝置。根據計算機能力的不同，寄存器能建立出相應的字節數的字長。每個詞的字節數從4到64不等！
Unit 2 生產設備的數字控制（1）數控是程序控制的自動化，在數字控制系統中，設備通過數字，字母和符號來編碼，以一種合適的格式為每一個特定的零件 或工件定義一個程序指令集。當工件變化時，程序也變化，改變程序的能力也就是適合中小批量生產。寫一個新程序比改變大量生 產設備要容易的多。
（2）基本結構：數控系統由下面三部分組成：1.控制程序；2.機器控制單元；3.加工設備。
三部分的基本關系，由圖2.1 所示。程序輸入到控制單元由送入的程序來引導加工設備控制。
（3）指導程序是一步步詳細的指導加工設備的指令。通常指令把主軸上刀具相對于安裝工具的工作臺定位。更多先進的說明包括 主軸的轉速，加工工具的選擇及其功能。程序刻在合適的介質中，提交到機器控制單元中，在過去幾十年中，最常用的介質是一英 寸寬的打孔紙帶。由于打孔紙帶的廣泛使用，NC 有時也叫紙帶控制，然而這是現代數控使用的誤稱。現在進入使用更多的是磁帶 和軟盤。
（4）機器控制單元（MUC）由電子和控制硬件組成，機器控制單元可以讀出和執行指令程序，可以自動改變加工工具和其他加工 設備。
（5）執行單元是數控系統的第三基礎部分，執行原件是有效執行工作的原件，最常見的數控例子其中的一個加工操作，加工設備 由工作臺和主軸組成，就像用電動機來驅動一樣。加工設備由控制單元來驅動控制系統的類型。控制系統的類型
（6）數控有2 種基本類型，點對點式和輪廓式控制，點對點式控制也稱定位控制，每個軸都是通過絲杠單獨驅動，根據加工類型 不同，加工速度也不一樣。機器開始以最大速度運行來減少非加工時間，但當他達到數據定義的位置時，機器開始減速。因此在一 個操作中，如鉆或沖孔操作先定位在加工。在鉆或沖孔之后，迅速收起工具移動到另一個位置重復此操作。從一個位置移到另一個 位置是非常重要的，要遵循一個原則，從效率上考慮只要時間最短即可。點對點系統主要用于鉆，沖孔，直銑操作中。
（7）輪廓式也就是連續路徑式系統，定位和切削同時按不同速度來控制，由于刀具在指定路線運動同時切削，因此速度和運動的 同步控制是非常重要的。輪廓式系統常用于車床銑床磨床焊接設備和加工中心。
（8）沿著路徑的運動或以增量差補是幾個基本方式的一個，在所有的差補中，要控制刀具的回轉中心定位，補償可以以不同直徑 及刀具磨損，在數控程序中進行改寫。
（9）有一些已形成差補方案來處理數控系統中連續路徑和加工系統產生的問題包括：
1.線性差補；2.圓弧差補；3.螺旋線差補；4.拋物線差補；5.立體差補
（10）每一種差補程序都允許程序源產生加工指令，適用于相對少的輸入參數的直線或曲線路徑。儲存在數控單元中的模塊預算指 引工具沿計算出的路徑運動。
（11）線性差補是最基本的差補方法，用于連續路徑的數控系統中。兩軸和三軸線性差補路線在實際中有時會分辨出的，但在概念 上他們是一樣的，程序源要明確指定直線的起點和缺點及沿直線的進給率。差補需計算兩軸或三軸的進給速率以達到設定的進給速 度。
（12）線性差補用來差補圓是不合適的因為程序源需要明確指定線段部分（線段數量）和各自的終點來大約模擬圓弧。圓弧差補法 已形成他允許程序編程的路徑，使用圓弧只要給定以下參數，圓弧終點坐標，圓心坐標，半徑和刀具沿圓弧路徑的走刀方向。圓弧 差補也是由許多小的直線段來實現的，但這些小線段的參數由差補模塊來計算出來的，而不是程序員設定的。切削是沿著每一小線 段一個一個的進行以產生光滑曲線路徑。圓弧差補的局限性是圓弧路徑所在平面是由數控系統中兩軸所決定的平面。
（13）螺旋線差補結合了環形差補兩軸在第三軸上做線性運動這樣來定義空間三維螺旋路徑。
（14）拋物線差補和立方差補法通過高次高程來實現自由曲線。這通常需要有強的計算能力，正因如此，他不如直線差補和環形差 補常見。他們主要用于汽車工業中具有自由風格的車身面，而這是線性差補和圓弧差補不能精確容易得到的。
（15）數控技術運用于數控機床，這是數控的主要應用。現在主要用于商業。我們仍討論數控系統特別是金屬數控車床。數控車床技術
（16）種加工過程都可以在設計的專門車床上來實現加工。在車床上車削，在鉆床上鉆，在銑床上加工。有幾種類型的磨削方法也 要有相應種類的磨床。被設計的數控磨床可以進行下列加工包括：1.鉆加工；2.銑床立式和臥式主軸；3.車床臥式主軸和立式主軸； 4.臥式和立式鏜床；5.仿形銑床；6.平面磨和圓柱磨
（17）除了上述幾種機械加工方法，數控機床可用于其他金屬加工過程包括：用于薄片板的金屬板上沖孔的沖壓機，用于薄片金屬 彎曲的折彎機。
（18）數控技術的介入到機加工對機床的設計和運用有著顯著的影響。數控影響之一在程序控制下切削金屬的時間與傳統手動機床__ 大得多。所以對于一些零件如主軸驅動主軸絲杠磨損更快，這些零件要設計成持續時間長的。第二，增加電子控制單元后設備成本 也隨之增加，因此需要更高的利用率。取代傳統手工操作的一班制，數控機床通常采用兩班或三班制來獲得更多的回報。數控機床 的設計中減少了非操作過程的時間如裝卸工件和換刀時間。第三，增加的勞動成本由人工成本變為設備成本。考慮到人工操作的角 色，角色由技術熟練的工人控制，工件生產的每一個過程變為只控制裝卸換刀和清除碎屑和類似的操作，這樣一個工人可以同時操 作兩臺或三臺車床，機床的角色和功能也改變了。數控需要設計成高度自動化具有需要在不同車床加工幾種操作聯合在一起一定加 工的能力，這些變化是通過一種新型車床在數控技術存在之前是不存在的，他豐富了數控加工中心
（19）加工中心是在20 世紀50 年代發展起來的具有在程序控制下在一個工件上一次裝夾完成幾種不同的加工能力的機床。加工中 心能完成銑，鉆，鉸屑，攻絲，鏜，車端面及一些類似機加工工作。另外數控加工中心的典型特征包括以下方面：
（20）(1)自動換刀能力: 多種機加工工作一位著需要多種刀具。刀具貝安裝在刀庫或多刀刀庫中。當一把刀需要被調換時，多刀 刀座自動旋轉到相應的位置上。自動化的換刀機構。在程序控制下進行，把主軸上需換下的刀和多刀刀座上的刀調換。
（21）(2)工件的自動定位: 大多數加工中心都可以使工件沿著主軸旋轉因此允許刀具達到工件的四個表面。
（22）(3)托架滑動裝置（平板架）: 加工中心另一個特點是有兩個或多個獨立拖板每個拖板都可以調整在刀具上。在加工過程中，一個拖板在刀具的前部，另一個拖板在遠離主軸的安全位置。這樣當機床正在加工當前的零件時。操作人員就可以從上一個工作循 環中卸下最終加工好的零件，同時加緊毛坯用于下一個工作循環。（23）加工中心可以分為立式和臥式。這是參照機床主軸方向來劃分的。立式加工中心具有軸線相對工作臺垂直的主軸，臥式車床 的主軸軸線是水平方向的。這種區別通常會導致在這些加工中心加工的零件類型不同。立式加工中心用于以上進刀的平面工作。臥 式加工中心用于立體形狀，刀具在立體側面可以進刀。一臺數控臥式加工中心，例子如圖2.2 所示，具有上面提到的一些特征。（24）加工中心的成功應用導致了其他類似金屬加工機床的發展。例如：在車削中心，把車削加工設計成一個高度自動化萬能機床 可以完成車削，刨，鉆，螺紋加工和類似的操作 DNC AND CNC（25）數控的發展在分批生產和小批量生產中有著重要意義，從技術和商業角度來說都有著重要意義。數控有兩方面的提高和擴展，包括：1.直接數據控制；2.計算機數字控制（26）直接數據控制
直接數據控制定義為一個制造系統，一定數量的機床有一臺計算機通過直接硬件連線實時控制。相應的磁帶播放機忽略在直接數控 中，這樣就消除系統中最不可靠的環節。不用磁帶播放機而用電腦信息傳給車床。原則上說一臺計算機可以控制100 臺獨立機器（DNC 系統在1970 年稱為可控制26 臺機床）直接數控（DNC）電腦設計成在需要的時候提供指令給每一臺機床，當機床需要控 制指令時，計算機立即發送指令給機床。
（27）圖2.3 說明了DNC 的基本配置。這個系統包括4 部分： 1.中央計算機；2.大量內存，用于存放數控程序；3.通信線；4.機床刀具
（28）計算機從海量內存中取出部分程序指令送入到需要的獨立機床中。相應的計算機也接受機床反饋信息。這種雙工的信息流在 實時控制加工系統中出現意味著每臺機床需要指令的請求能立即得到回應。類似的，計算機必須總是要準備要接受信息和進行回應。DNC 系統顯著特點是：可以實時控制大量機床。更具機器數量和所需的計算機程度化。有時需要使用衛星計算機如圖2.4 所示。衛 星計算機是更小的計算機，可以分擔中央計算任務，減輕其負擔。每臺衛星控制幾臺機床。零件加工指令程序由計算機接受，儲存 在內存中。當需要時衛星計算機發送指令程序到每個獨立機床中。來自機床的反饋數據在電腦中央存儲接受之前存儲在衛星內存中。（29）計算機數字控制
由于DNC 技術的介入，在計算機技術上得到了很大的發展。計算機在尺寸和成本顯著減少的同時，計算機的能力卻有很大的提高。在數控中，這些發展使得由硬件布置的MCU（）變為數字電腦控制的控制單元。最早，小型機在1970 年使用。隨著計算機進一步 小型化，小型機被當今的微型機取代。
（30）計算機控制也是一種數字控制，它采用微型計算機作為控制單元。由于數字電腦用于CNC 和DNC 中，只近似區分兩種類 型。有三個區分原則：
1）.DNC 電腦接受和發送指令數據都是來自許多機器，CNC 電腦控制只是一個機器或多個機器。
2）.DNC 電腦占有一個位置通過控制來實現機器的旋轉。CNC 電腦要非常靠近車床。
3）.DNC 軟件的發展不經可以控制生產設備的每個單獨零件，還可以在生產堅固性方面提供主要控制信息。CNC 的提高可以提 高特殊車床的能力。
（31）電腦數控系統的大體配置如圖2.5 所示。如圖中所示，最初進入控制器的是磁帶播放機。這樣，CNC 的外部系統與傳統的NC機相似。然而CNC 中的程序使用方法是不同的。
Unit 3數控編程
數控編程由一系列方向構成，這些方向導致數控車床執行某種操作，加工是最常用的進程。數控車床編程由內部編程部門來完成，在車間里，或者從外部源購買。編程還可以手動或者在計算機輔助下來完成。程序包括指令和命令。幾何指令涉及刀具和工件間的相對移動。進程指令涉及主軸速度，進給以及道具等。行動指令涉及插值的類型以及刀具或者工作臺的緩慢和快速移動。切換命令涉及到開/關冷卻液供給狀況，主軸旋轉，主軸方向，換刀，工件進給，夾具固定等等。（1）手工編程。手工編程包括根據部分工程圖紙首先算出刀具，工件以及工作臺的尺寸關系，繼而決定執行的操作和工序。那么一個包括執行特定操作所需必要信息的程序表就準備好了，例如刀具切削，主軸轉速，進給，切削深度，切削液，以及刀具或者工件間的相對位置或者移動。根據這些信息，部分程序就準備好了。通常一個紙帶首先被準備好用于試用和調試程序。根據紙帶被使用多久，紙袋通常用更耐用的聚酯薄膜制成。
手工編程可以由那些具有特定制造工藝知識和能夠理解，閱讀以及更改部分程序的人來完成。因為他們熟悉機床刀具和工藝流程，熟練的機械師可以做一些手工編程的編程培訓。然而，所涉及的工作是乏味的，費時的，因此不合算。手工編程大多數用于簡單的點對點應用上。（2）計算機輔助編程。計算機輔助編程是一種涉及到特殊符號的編程語言，這種語言可以決定角點的坐標，刀口以及工件的表面。編程語言是與計算機通信的方式并且涉及到符號字符。編程員用這種語言描述加工零件，而由計算機將零件程序轉換為數控機床的執行指令。許多種商業應用上的語言有多種多樣的特點和應用。第一種被使用的是類似于英語語句的語言，它在十九世紀五十年代末被開發出來并被稱為APT語言。這種語言，由于它多種多樣的擴展形式，一直是最廣泛的用于點對點和連續路徑編程的語言。
復雜的工件現在使用基本的繪圖進行制造，計算機輔助制造程序。刀具的路徑是在類似于一個CAD程序的大量的繪圖環境下制造出來的。這種機器代碼由程序自動生成。
在生產開始之前，程序應該被校驗，還有就是通過一個顯示器觀看工藝流程的模仿或者使用廉價的材料（例如鋁，木頭，石蠟，或者是塑料）制作工件，而不是使用指定用于已加工零件的真實材料。
計算機輔助編程有以下幾個優于人工方式的重要優點。
比較容易使用的符號語言
縮短了編程時間。編程是一種容納了大量關于機械特點和工藝變量數據的一種能力，例如動力，速度，進給，刀具形狀，刀具形狀改變的補給量，刀具磨損，偏轉，以及冷卻液的使用。
減少了在人工編程中出現人為錯誤的可能性。
因為編程時所需更少的時間，降低了成本。編程語言的使用不僅導致更高的工件質量而且考慮到了機械指令的更加快速發展。另外，模擬可以在遠程計算機的終端設備上運行，這就確保了程序按照既定來運行。這種方法可以防止昂貴的機器由于調試程序產生不必要的占用。
選擇某一種數控機床編程語言主要取決于以下幾個因素：
生產設施人員的專業水平級別
工件的復雜程度
設備的外形以及計算機的應用
涉及編程的時間及費用
因為數控涉及有關工件材料和加工參數的數據插入，編程必須由有制造業的相關方面知識的操作工和程序員來完成。在生產開始之前，程序應該被校驗，還有通過一個CRT屏幕來觀察工藝流程的模擬或者用廉價的材料制造工件，例如鋁，木頭或者塑料，而不是使用指定用于已加工零件的真實材料。數控編程語言
自從1956念麻省理工學院的初步研究數控編程系統以來大概有超過100種的數控編程語言已經被開發出來了。大多數語言開發用于特殊的需求和機械并且它們沒有經受住時間的考驗。然而，相當多的語言在今天一直被使用。在本小節，我們回顧一下那些被普遍認為是重要的語言。
APT(自動編程工具)，APT語言是麻省理工學院研發的關于數控機床控制編程系統的成果。它的研發開始于1956年六月，它第一次用于生產是在1959年左右。幾天它是在美國應用最廣泛的語言。雖然第一次打算作為一種輪廓語言。APT現在的版本可用于定位和持續路徑的編程而且可用于多達五個基準軸的持續路徑編程。
AUTOSPOT(用于定位工具的自動系統)。這個程序有IBM研發，在1962年第一次被引進用于PTP編程。AUTOSPOT現在的版本也可應被用于修證輪廓。
COMPACT II。這種語言是來自于制造數據系統的封裝。（MDSI公司），在安阿伯，密歇根州的一家公司。數控機床控制編程的許多特點于SPLIT相似。MDSI公司將COMPACT II系統租賃給以分時為依據的用戶。這種程序通過使用遠程終端把程序傳送給MDSI公司的計算機，有計算機轉向產生數控的紙帶。
ADAPT（APT的改編版本）。多種編程語言直接依據于APT程序。這些語言之一便是ADAPT，它是在空軍合同下由IBM公司研發的。這種語言意圖提供許多APT的特點但是用于小型計算機。ADAPT不如APT一樣強大，但是能夠被用于定位和修改輪廓工作的程序。
EXAPT(APT的擴展子集)。這種語言是由德國研發的。，開始于1964年之間，以APT語言為依據。有三個版本：EXAPT I ——被設計應用于定位（鉆削和直切銑）。EXAPT II——被設計用于車削，還有EXAPT III—被設計用于限制輪廓的操作。EXAPT最重要的一個特點是嘗試自動地計算最佳進給量和進給速度。
APT不僅僅是一種數控語言；它也是一種以APT聲明為依據執行計算來。生成切割位置的計算機程序。在APT語言中聲明有四種類型：
幾何聲明。這些定義好的幾何元素包括了工作組。它們有時也叫做定義聲明。
后處理程序聲明。這些聲明用于特殊的機械工具和控制系統。它們用于指定進給量和進給速度而且精確了機械的其他特點。
輔助聲明。這些不同種類的聲明常用作定義工件，刀具，以及公差等等。
銑床和車床的CNC編程于其他機械編程工藝是相似的；它需要對編程語言有一個透徹的理解。這種用作銑床和車床NC的語言通常被稱為G代碼。這些工序通常用于銑床機械和機加工中心，提供了一些G代碼使用的經典例子，因為它包括大約了NC操作中的75%。下面編程和工藝的五類用于銑床NC編程。（下轉P114）自動化編程的人工指南
NC機械編程采用兩種形式：人工編程以及在CAM軟件支持下的代碼生成。例3-1是一個人工編程的例子。它以銑削零件圖為開始，編程者設計一些能夠驅動切削刀具沿著預期路徑運行的G代碼工序。CAM生成的NC代碼為了使目標機械工具能夠直接轉換為零件圖送給G代碼程序運行在已選擇的機械上，從而使用一個后處理程序。CAM軟件和后處理程序分成兩類。類型之一，專業CAM和簡潔CAM，它是獨立的，并且吸收了所有主要CAM供應商的繪圖文件。第二種類型，是被CAD供應商研發的，它集成了CAD程序和運行，作為集成CAD / CAM設計軟件的一部分
Unit 4 機加工與切削加工中心
（1）這篇文章介紹了計算機控制的機械刀具設計的能力和較大的發展，就想我們知道的機加工和切削加工中心，這些機器有其他 機器工具沒有的柔性和多功能性，應此他們作為加工工具第一選擇。機加工與切削加工中心
（2）需要注意的是每臺機器他的自動化程度有多高，都要設計一種基本的加工樣式就像所展示的那樣，在制造過程中不同的表面 是用不同的加工方法加工的，（3）例如，如圖4.3 所示，銑、端面車削、鏜、鉆、鉸孔、切絲來獲得額定的公差要求及最終表面精度。
（4）習慣性的加工過程的執行，始于工件的移動從一把加工刀具到另一把加工刀具直至所有的加工完成，這是一種切實可行的制 造方法，并具有高度的自動化。這就是生產流水線的原理。最常見的是應用于高容量或大批量的生產，生產流水線是由幾種加工刀 具按一定的次序排列組成的，諸如自動發動機模塊這樣的工件從一個加工地點到另一個加工地點，并且在每一個加工中心都運用特 有的加工方式進行加工，工件會被輸送到下一個機器進行下一個加工。
（5）有這樣一些產品或加工方法，他們的生產路線是不可行或不經濟的，特別是當這些種類的產品在加工時需要迅速轉換加工方 法。一個重要的概念，在20 世紀50 年代末期得到發展，那就是機加工中心。一個機加工中心就是運用計算機控制的刀具在工件的 不同表面和不同的方向上進行切削操作的能力，通常說工件是不動的，而切削工具進行旋轉，比如銑和鉆操作。
（6）機加工中心的發展暗示著計算機控制的機器刀具之間關系的進步。如數字控制的車床加工中心擁有兩個轉臺帶動幾把切削刀 具進行車削，端面車削，鏜孔和切螺紋。
（7）工件在加工中心里是被安放在托盤上或模塊上，那樣可以被移動并且可以進行不同方向的旋轉和定位，在進行特殊的切削過 程完成后，工件不需要移動到另一臺機器進行鉆孔，鉸孔，攻絲之類的附加加工。換句話說，工件和機器是被置于工件上的。（8）當所有的加工工作完成后，托盤會自動離開已加工工件，并且另一個托盤運用自動托盤變速器將工件進行定位和加工。所有 的傳動機構都有計算機控制，并且托盤定位器有10-30 秒的循環時間，托盤臺能夠使得多級托盤更好的服務于加工中心，工具同樣 能夠被裝備到不同的自動化部件中，諸如上料與下料機構。（9）加工中心裝備了可變程序的自動刀具變換器，依賴于這樣的設計多達200 把切削刀具能夠被貯存在刀庫，刀鼓，刀鏈（工具 庫），輔助工具庫能夠更好的為一些特殊加工中心提供更好的切削道具，這些刀具可以自動的任意選擇到達機械主軸的最短路線，刀具交換臂是一個普通的設計機構，他可以旋轉來拾取特殊的工具（每一個工具有他自己的刀桿）和他在主軸上的位置。
（10）刀具通過直接連接在刀具夾持口上的編碼標簽、條形碼或記憶芯片來標識。一次換刀時間在5-10 秒鐘，對于小的刀具可以 少于1-2 秒，對于重達110 公斤的刀具可以達到30 秒，刀具變換器的設計趨勢趨向于運用簡單的原理提高換刀的時間。
（11）加工中心同時裝備有工具的檢驗臺，他可以給計算機數字控制提供信息對于在換刀和刀具磨損時的誤差提供補償。接觸試探 針可以自動裝入工具夾持口中以確定工件的參考平面，以便對刀具設置進行選擇并對加工的工件在線檢測。
（12）圖4.6 所示的一些表面可以被聯系起來，他們的相對位置可以被確立并儲存在計算機軟件的數據庫中，這些數據稍后可被用 于編寫刀具工作路徑的程序同時對刀具的長度和直徑進行補償，又可以為預先加工刀具的磨損提供補償。機加工與切削加工中心的種類
（13）盡管這里有不同種類的刀具設計在加工中心中，兩種最基本的種類垂直主軸和水平主軸；大部分的機器擁有上述兩種軸線的 能力，在加工中心中最大的切削刀具的尺寸可以繞工具一周，就像我們知道的工具包絡，這個術語第一次應用在與工業機器人的聯 系上。
（14）垂直主軸加工中心或是水平主軸加工中心都是為了適用在工件具有深腔的平面上執行加工工藝，如鑄型和模具制造。一個垂 直主軸的加工中心類似于一個垂直主軸銑床。刀庫在圖示的左側并且所有的加工方法和傳動機構通過位于右側的計算機控制托盤進 行定位和修改。（15）因為在加工中心中由于推力的作用方向是向下的，機器具有高的剛度，并在對于加工部分有較好的精確補償，這些機器通常 比水平主軸的機器便宜些。
（16）水平主軸的加工中心或水平機加工中心是為了適用于高大工件的表面加工的需求。托盤可以在不同的軸線（如圖4.3 所示）上旋轉來進行不同種類的有角定位。
（17）水平主軸加工的另一個范疇是車削加工，是用特殊機床進行計算機控制的車削加工。一個三轉動架的計算機數字控制的車削 加工如圖4.8 所示，這個機器是由兩個水平主軸和三個轉動架以及不同的切削刀具設計而成的來執行一些旋轉工件的加工。
（18）萬能加工中心同時裝備了垂直主軸和水平主軸的機器，他們具有不同種類的特色，并且具有加工所有表面的能力（垂直的、水平的、斜的）。
機加工中心的特征和能力
（19）下面是加工中心的大部分特征：
a．他們有能力有效的，經濟的并且擁有重復的高精度的尺寸的能力來處理不同型號的磨具的能力。公差的范圍在正負0.0025mm。b．這些機器是萬能的，擁有多達6 條線性的有角傳動的軸線并且有能力快速的從一種加工方式向另一種加工方式轉變來滿足不同 種類的加工刀具和有效的減小地板空間。
c．裝載工作和卸載工作，轉換刀具，矯正，故障尋找所需的時間正在減少，應此生產能力提高，減少實驗的需求尤其是對于熟練 實驗的要求并且生產成本降到最低。
d．他們可以高速的自動化并相對地緊湊，應此一個工作人員可以在同一時間照顧到兩臺或更多的機器。
e．加工機器裝備了刀具調節監測裝置為了檢測出工具的磨損與破裂，又可以探測工具磨損的補償和工具調位。
f．前處理和后處理的矯正和工件加工監測在加工中心的功能。（20）加工中心可應用于更廣闊范圍的不同種類型號和特征，并且他們的成本范圍從5 萬到100 萬甚至更高。典型容量范圍可達 75KW，并且最小軸轉速通常在4000-8000rpm 范圍里，一些可以達到75000rpm，還用于小補償切削的特殊應用。一些托盤具有支 撐重達7000kg 工件的能力，通常高的容量用于特殊的應用當中。（21）現在大部分機器有一個標準組件的基準構造，應此不同種類的外圍裝備和附件可以被安裝并且和修改不同種類產品的修改要 求。
（22）因為加工中心的高生產能力，大量的切削會產生并且必須被收集起來應此一些需要一些可用于切削收集處理的設計，就像圖 示所舉例那樣，兩個在橫軸加工中心截面圖底部的切削傳送帶這些特殊的加工傳送帶是螺旋形或螺桿型，他們沿著導槽收集切削并 且將他們輸送到收集點，另一條系統會選用鏈式傳送帶。刀具的選擇
（23）加工中心能夠有能力需求有效的花費可以說進行有效的成本控制，他們通常不得不每天做至少兩次移動，所以他們必須有效 并且可以連續調整在加工中心中產品的購買需求，因為他們固定的多功能性，但是加工中心可用于及時的制造大范圍的特殊產品。（24）種類的選擇和加工中心的尺寸依賴于以下幾種因素。a．產品的種類，尺寸和模具的復雜性。
b．加工方法的種類及執行方式和切削工具的需求次數。c．精確補償的需求。d．生產速率的需求。
（25）盡管多功能性是選取加工中心的一個關鍵因素，我們必須考慮到權衡高成本高精度需求和比較在運用傳統加工工具制造相同 產品時的成本。
Unit5 工業機器人
介紹
工業機器人是相對來說較新的機電設備，它已經開始改變現代工業的面貌。工業機器人不像科幻小說中的那個模樣具有人一樣的能力并且能與其它移動物建立友誼。機器人能夠看見聽到觸覺聽的研究已經進行了20多年，現在開始開花結果了。然而，通常所說的工業機器人技術是是大多數機器人只包含了一條臂而不是擁有人解剖學上的全部結構。通常的控制只允許這些機器人在空間上從點到點的移動，完成相對簡單的工作。美國機器人學會定義機器人為“一個可再編程序，多功能的機器手，它通過各種可編程的運行來完成不同的任務，用于搬用原料、零件、刀具、以及專用裝置。如果認為不同類型的加工有不同的作用。那么一個數控加工中心也可以被認為是機器人。大部分制造工程師認為數控加工中心不是機器人，盡管他們有很多相似之處。數控機構和機器人的動力驅動和控制十分相似。想數控機構一樣機器人能夠由發動機、液壓系統、氣壓系統提供動力。兩種設備都能由開環控制或閉環控制。實際上，許多應用于機器人發展技術由數控工業演變過來并且許多機器人制造商也制造數控機床和數控控制器。實際的機器人由帶有腕（或稱為臂）的主機身和機器端部的工具（通常是某些的支撐器）組成。機器人也可能有一個輔助動力系統。機器人系統還包括一個有一些控制環模、操作桿、鍵的控制器。一種典型的機器人系統如圖5、1 機器人特點通常由機械系統的設計表現，一個主要框架包括三條移動軸的機器人稱為笛卡爾機器人。笛卡爾機器人它的名字來源于笛卡爾坐標系沿三維空間的直線移動。一些笛卡爾機器人由龍門結構構成以便使沿每個軸的偏差最小。這些機器人稱為龍門機器人。圖5.2展示了笛卡爾機器人，這些機器人的動作控制都相似于傳統的三坐標機床。龍門結構一般來說是最正確的機器人實際結構。龍門機器人通常用于公差較小和位置度要求較高的裝配中。
圓柱機器人由兩個移動軸和一個旋轉軸組成，這種機器人的名稱來源自包圍軌跡（它的功作范圍），它由軸移動的極限位置構成。圖5.3展示了典型的圓柱機器人。圓柱機器人有許多應用，最常見的是材料的搬運操作。給機器人編程。
為了是設備具有資格作為機器人，它必須是容易可再編程的。不可編程的機構，無論其通過重新裝配或再接線可實現的潛在柔性有多大，也不能算坐機器人。許多這類設備是固定的或可變的序列機器人。很多這樣的機器人是由氣壓驅動的。這種機器人借助某種梯形邏輯圖被驅動至一些固定的擋塊活行程開關處，而不是控制它的軌跡。雖然梯形圖編程可滿足機器人的運動要求，但行程開關和擋塊必須正常的被整體移動，以改變所需執行的工作任務。動力開動或發動機打開到“開”或“關”依據工序的要求和轉換狀態。機器人對這類系統操作通常局限于相當簡單應用。
傳統機器人的程序通常采用以下三個形式之一：（1）操作器編程（2）導入式程序（3）脫機程序。每個機器人通常具有一個或更多這種程序類型的系統。每種形式的優缺點依不同的應用而不同。
操作器編程最常用的機器人編程方式，這種類型編程，A pendant 通常包括幾個用于使機器人在它工作范圍移動的操作桿。在每個工序的終點，機器人的位置被保存。像數控機床一樣，一些機器人允許編程人員選擇定義兩點間路線。另外，這些機器人被稱為連續路徑系統。不允許用戶指定路徑系統稱為點到點系統。許多連續路徑機器人允許用戶定義在兩個主要點之間連線的路徑。那么，用戶可以定義直線、圓弧的、指定某一位置的路徑。在直線路徑中，機器人在笛卡爾空間中，以直線兩兩端點移動。顧名思義，圓弧運動就是在某一主平面上沿圓弧運動。機器人以插入某處方案執行路線很不容易確定。在接點插補中，機器人的每一關節都以一恒定速度移動以保證所有的軸同時啟動和停止。對于笛卡爾機器人，直線和結點插補方案產生相同的路徑。對于其他類型機器人系統，這不成立。
操作器編程系統通常提供允許編程人完成輔助操作的命令，如關閉終端，等待，暫停，檢查一種或幾種轉換狀態，返回全部狀況給機床，等等。編程人員使機器人走過要求完成一項工作的必要步驟，保存每一中間步驟和輔助的信息。用于給fanuc M1機器人編程的操作器，如圖5.4所示。
導入式程序是最簡單的機器人程序設計過程之一。顧名思義，編程人簡單實際的是機器人沿著路線輪廓移動。機器人控制器反饋它的位置并且像編程人一樣引導機器人完成操作。當編程人員負責引導機器人完成必要動作時，動力降低以便機器人不產生傷害操作人員。盡管導入式編程是最容易學的程序語言，但它也反映了一些機器人應用的限制，例如，當機器人正在進行操作時，操作人員搬運機器人。齒輪，電動機和絲杠會引入錯誤的運算讀數值，這樣當機器人的重量，也許是工件的重量必須由系統承擔時，端部執行器的 實際位置可能與機器人的訓練位置有很大差異。這種方式的另一個問題是由于在機器人的位置和速度被記錄指引通過期望的路徑是，大量的數據信號產生，這些數據不需存儲后調用，存儲和從新調用的空間和時間可能會引起匯編器問題，也許與導入方程式協調的主要問題是引導機器人完成工藝過程的人能夠做有限的準確可能引起工藝過程的不協調，人為錯誤和不準確性削弱了使用機器人的優點。
脫機程序對機器人來說是 相對較新的技術，它能夠提供導入式和控制板編程的一些優點。脫機程序的規律與對數控技術應用脫機語言類似。幾種脫機語言已經在美國的主要大學和工業種發展。這些語言主要有unimation的VAL,美國機器人協會的ar-basic,microbot,lnc的arm-basic和ibm的ami，以ar-basic為例解釋說明脫機語言，ar-bisic允許用戶 定義機器人的位置 控制機器人的運動 輸入輸出控制數據
ar-basis系統的細化，他采用的許多相同的功能采用了我們熟悉的basic程序語言，在ar-basic中，點和刀具定義為初始化數據點由以下協議定義 x,y,z,r,y X，y,z表示由端部執行器占據笛卡爾空間，r p y表示刀具旋轉進給和yaw.每個點的定義既可以是絕對的夜可以是相對的（也和數控機床有相似的規則）
刀具定義命令常用于定義操作要求的所有刀具的位置，刀具定義指定機器人面板的中心，包括等定義點相同的六個數據
機器人通過運動控制命令執行運動，運動命令允許編程人定義采取的路徑類型（直線，圓弧，結點插補）定義刀具的最終速度 定義參考柜架 定義刀尖的類別
AR-Basic也允許程序編譯人員輸入，輸出數據到與機器人連接的設備，模擬的數字信號可以傳送到模—數轉換轉換器并行的或串行的I/O口。表5—1是點和刀具定義的舉例。表5—2舉例說明了AR-Basic的運動控制。
Unit6 成組技術
成組技術是一個制造業的哲學概念，它涉及到具有相似或相關屬性零件的標識和分組，這樣我們可利用產品的相似性這種特點把這種技術應用于產品的生產的設計制造生產過程中。歷史上，這項新奇的技術首先出現在1920年的美國，當時Frederick Taylor也認同成組部件需要特殊工藝的觀點緊隨其后的是瓊斯和拉姆森機械公司在20世紀20年代初，這個公司使用的是一種簡陋的成組加工方式來生產機床，他們使用這一原理的方法就是以產品來劃分部門而不是以工藝或縮短路徑來劃分部門。現如今，成組技術通過良好的結構分類和編碼系統和應用支持軟件采取的相似組成部分取得優勢。
現代制造技術正投許多日益增長的國際化競爭與快速變更的市場需求所引起的挑戰進行著比拼。下列的這些挑戰已在成組技術中遇到過。
第一段 略。
作為第一個因素的結果，傳統的銷售組織變得非常低效和浪費，這都是因為產品在不同的加工部門之間奢侈的路徑（直接翻譯的不很對）。為了縮短準備時間有必要使設計與生產環節緊湊起來，從而獲得在國際市場中相對有利的位置。
1.產品設計中的益處。涉及到產品的設計，組成技術的原理益處就是它能夠是產品設計者避免”重新設計車輪”(即重復改造)，或者加大設計的影響，換句話說，它排除設計一個已經被設計過的產品的可能性，因為他使儲存變得容易并且使工程設計的檢索相對容易些。（下句書中有）如果精確部件的設計不包括在公司的電腦檔案中，一個設計將足夠接近那種被需要的能夠被檢索并且調整調整到為了滿足需求的程度。成組技術的進一步優勢是它促進了設計特征的標準化，諸如角半徑，倒角這一類的，從而導致了生產工具和生產設備的標準化。
2.模具和安裝的標準化。自從部件被分門別類處理后，一個柔性的生產設備的設計能夠使得其適應用同一種方式加工的同種類別內的各種加工，從而通過減少夾具來減少其所需的費用。同樣的，一個機器的安裝也可以適應整個類別而不是獨立部件。3.已有
4．提高問題式生產的經濟體系。通常，間歇式生產涉及了許多非標準部件。似乎毫無共同之處。因此，不同類別的分組部件使得經濟效益的 獲得只存在于大批量生產中。
5．更容易調度。將部件分組方便了任務的調度，使得工作時是完成一類的加工而不是只加工單個部件。6． 減少工作進程和準備時間。7 更快更合理的工藝設計。成組技術為自動化流程規劃鋪平了道路，這可以通過適當的零件分類和編碼系統來實現，在每個部分的詳細過程圖中儲存代碼，從而方便檢索。
Unit7 1 CAD/CAM(計算機輔助設計)是一個以電腦為輔助設計或用電腦輔助設計的一個術語。它是一種在設計和生產過程中運用數字電腦來完成特定功能的一種技術。這一技術正朝著設計和制造，這兩個曾被傳統的認為在生產過程中有名自獨立分工職能的兩個過程相結合的過程發展。總之，CAD/CAM將會為今后的計算機結合產業提供技術基礎。
2、由硬件和軟件組成的電腦系統將執行由特定用戶所提出的特殊的設計功能基礎的CAP硬件包括：電腦。一個或多個終端器圖像顯示、鍵盤、及其他的一些外部設備。CAD的軟件包括能在其系統內運行計算機圖表的計算機程序及能為公司用戶的設計工作提供便利的應用程序。例如：分力壓力分析（程序）機器的動力回應（程序）熱交換計算程序、及各種控制程序等。由于生產線、制造工序及顧客市場的不同，各種應用程序也會隨不同用戶的需求的轉變，因而這些工廠也帶來了對CAD系統需要的差異
3計算機輔助制造（CAM）可以被定義為通過擁有車間生產信息的直接或間接的電腦界面利用計算機系統來計劃、管理和控制制造工廠的運作。其定義表明，計算機輔助制造的應用可分為兩大類：一 計算機監控和管理，這是計算機為了監控和管理生產過程最直接的應用且于生產過程直接相聯系
二、以制造為支撐的應用、這是計算機被直接用于工廠的生產運作，但其中并沒有計算機與制造過程直接聯系的界面
CAD/CAM系統具有一套全新的制圖基本原理，其中的任何一個都能提高制圖效率。例如：目前市場上大多系統都是具有能將新興的實用的制圖技術制動化固有功能。如分層技術使得制圖能按邏輯結構制圖，立刻組成一個整體，并被分開保存以便識別，但這些部件并演示整個制作過程。這一過程與我們在生物中所見到的解剖圖樣類似。骨骼，神經，內臟，血管和肌肉分別由具有不同顏色的塑料所替代。他們被看做個體，或者把他們疊加在一起，來顯示各個部件之間是如何相匹配的。通過圖象系統來分層設色，采用相同的原則，除非覆蓋物是邏輯的而不是非物理的。諸如此類的應用有很多。分層也可用于區分英文和數字維度信息，數據信息。文本信息，電子需要鋸錘測探、機械部件路徑等。結果是清晰、明了的圖樣 其它分析的好處：
CAD/CAM也可以通過其它方式影響一個公司的工程系統，它能把所有的物理過程流線化，并且允許對現代化的工程技術方法和工藝過程進行重新評估。CAD/CAM提高了確保質量的技術，自然而然的適合于保持精度完善文件材料，并且保存了零件的數量與材料清單的精確記錄。一個完全集成CAD/CAM系統的正確安裝，促進了一個公司對設計及生產方法的評估，并且開創了那些方法所適合的標準。通常這個評估證明是有效的，但也能給那些沒做好準備的人帶來意外傷害。對這兩方面的問題都考慮到的管理者是很聰明的，CAD/CAM的應用始終都是一件復雜的事。缺點是什么呢？
CAD/CAM的缺點或許并不明顯，但即使對于最好的設計也是‘具有破壞性的。其中最大 的缺點是來自于從手工草圖和保存的記錄到CAD/CAM系統徑直移動所必須的跳躍。這就好像是把噴氣式飛機的引擎安裝在大眾汽車上，汽車開始可能在很短的時間內行駛的很快，但是，如果底盤不夠堅固來處理作用力，那么所有的設計將震動分離。換句話說，CAD/CAM將突出工作最脆弱的區域的不完全性，這對于人和不能保持的規則來說是殘忍的，就像一個對它的描述：“如果一個公司內部對繪圖材料清單和部分數字系統不能很好的使用，CAD/CAM系統將使問題惡化。”
當這種令人不滿的結果發生時，通常會把矛頭指向CAD/CAM系統---雖幾乎是不能譴責的是，但通常比將矛頭指向人或組織更好。任何一臺計算機將只能在輸入數據時工作，這是最基本的數據處理規則：廢物進，廢物出。如果一個公司正在使用一個不完全的目錄控制系統，僅僅是因為它是自動的。這個系統將得不到改善。事實上，自動化將會使這個不完全更加明顯。并且可能更混亂。因此當實施CAD/CAM系統是不僅評估技術的需要很重要，而且對于期望提高的現存的規則也是很重要的。
如果管理者不愿對現存的操作條件，標準，工藝過程進行評估，那對CAD/CAM的使用將很可能會失敗----因為一系列的原因。原因之一，管理政策將因為CAD/CAM系統與標準操作過程的分離而不能被很好的組織。在低水平的管理者中將產生一種這個系統永遠不會被人們有效使用的感覺。另一個原因，不同的部門之間的信息通道還沒有建立起來，這也導致產生CAD/CAM系統不能被長期使用的感覺。還有一個原因，就是操作員對系統實施的方面沒有輸入，這就導致了繪圖標準的缺點，系統管理的貧乏，系統使用者的無知，這種循環是不可原諒的。特別是對于標準操作條件的評價將直接給提高這些工藝過程提供意見，即使是CAD/CAM系統從來沒被使用過。CAD/CAM的應用
CAD/CAM技術從畫圖板發展到如今已經經過了一個很長的歷程，它已經廣泛的應用在各種工業生產，涉及范圍從航天飛機控制到武器研究。從繪圖到動態診斷，從電路分析到結構鋼分析。CAD/CAM廣泛應用于繪圖和制造的各個環節，從繪制影視音像設備草圖到控制大量的機器人組裝線，它的用途在不斷的發展。
CAD/CAM首先應用于電子制作業。這是因為CAD/CAM并不是一項公認的超越計算機產業的技術。人們才覺察到CAD/CAM在航空民用工業等領域的市場需求。新的復雜的設計已經無法由借助查圖手冊的手工繪圖所滿足。CAD/CAM成了必然的解決方法。如今這項技術已經具備了強大的技術和資金基礎。因此，潛在的CAD/CAM的用戶能夠滿足最終所采用的挑剔要求，他們再也不用購買低劣的或不會使用的設備了。當今的CAD/CAM市場：
現在，市場上有4種CAD/CAM的提供商。第一種是大型公司的附屬機構或部門。IBM的CAD/CAM分部就是一個例子。這些分公司和他的總公司喲著大宗的商業買賣，他們不僅銷售鑰匙系統，還稱作售后服務處。因為這些公司有著強大的后盾，所以他們的運作良好。但是他們同樣受束縛作風的影響，使得他們的不能對市場變化作出快速反應，也不能把先進的技術用于生產線來提高設備的性能。
第二種是專門的交鑰匙系統銷售商。這些公司提供各種各樣的作用于不同工業環境的CAD/CAM系統。這些公司已經從事CAD/CAM行業幾年或幾十年。他們已經在不斷的技術發展中建立了良好的 聲譽，這類公司有。。，這些企業由于規格較小，有時不能提供很好的售后服務，但他們對市場反靈敏，能很好的滿足客戶的要求，能夠提供各種可以使用的CAD/CAM系統。
第一種是新興的CAD/CAM銷售企業。這些公司比較小，年輕，富有創新精神，但他們的市場占有率僅為5%,但是每個公司都擅長為部分市場單人獨特的高品質的系統。通常，這些企業銷售的微型監控系統對需要小型化專業化 的CAD/CAM系統的客戶非常有用。事實上，這些客戶在購買設備前都是經過深思熟慮的。
第二種是服務機構，這些企業專門從事CAD/CAM服務。來滿足很小的或協調性的需求。服務機構越來越普遍并成為那些不能承擔購買CAD/CAM系統費用或不具備購買條件的公司的首選。這些機構不僅參與CAD/CAM的相關商業行為，他們還能為那些將要考慮購買他們設備的企業進行相關培訓和研討。
和任意一種銷售商做生意都有利有弊，大公司不容易討價還價，而且他們技術革新緩慢，但他們大多能提供良好的服務和可靠的產品，專門的銷售企業對客戶的需求都加靈活，并且產品升級周期較短。
1、CAD/CAM是指一個以計算機為輔助設計或輔助制造的術語。它是一種在設計和生產過程中運用數字計算機來完成特定功能的一項技術，這一技術正朝著與設計和制造兩個一直被認為在生產過程中各自獨立、分工明確的兩個過程相結合的過程發展。總之，CAD/CAM將會為今后的計算機融合產業提供技術基礎。
2、這一計算機系統由硬件和軟件兩部分組成，執行由特定用戶所提供的特殊的設計功能。基本的CAD硬件包括計算機、一個或多個終端圖樣顯示器、鍵盤及其他的一些外部設備。CAD的軟件包括能在計算機系統內部運行的圖標和程序。例如，分力壓力分析程序動力回應程序，熱交換計算程序及各種控制程序等。由于生產線、制造工序及顧客市場的不同，應用程序會隨用戶的不同需求而轉變。這也導致了CAD系統需求的差異。
3、計算機輔助制造CAM可被定義為通過擁有車間生產信息的直接或間接的計算機界面，利用計算機系統來規劃、管理和控制制造車間的運作。其定義表明，計算機輔助制造的應用分為兩大類： <1> 計算機監控和管理，這是計算機為了監控和管理 提高制圖效率1、2、3、它的潛能確實是無限的，生產率的提高只受管理原則性的限制。比如，可以把制圖中心看做是一個專門設計貨倉的建筑方。他們的多數工作都是重復的，可以在一項項工作中被反復使用。
例如，一個標準的地板或樓梯；亦或是一個標準的門或門框，系統可以再幾秒內完成這項工作，同時制圖者可以不必每次都重新設計必須插入到圖中的部分。
4、此外還有許多使用的宏程序。一組放在一起的按鈕可以自動的將圖樣的規格用英文自動轉化為數字單元，或自動調節整個繪圖，并使之旋轉到理想的方位，或生成一張關于復雜工程繪圖的材料清單。
5、更進一步的講，整個設計過程都能被儲存到系統中。當制圖者接到一個與所儲存的繪圖規格相似的工作時，他只需重新調用它，把它引入工作存儲庫，再重新修改新工作中與原圖的不匹配的部分的規格。這樣效率就被提高了，原始工序被提高了效率，而反過來，下一步的工序也被提高了效率，這說明需保持和對用戶易于操作的有完善與分進的數據庫。
Unit8 柔性制造系統
關于柔性制造系統，有很多不同的定義，多數情況下，如何對其定義依賴于其使用者對其組成部分和使用方法的個人看法。
然而，接下來的描述是對FMS定義的概括，那就是有源可尋和無源可尋的資源。
美國政府：一系列的自動機床和生產加工設備項目與自動物料處理系統聯系在一起普通級別的數據事先編程計算機控制，為任意生產加工的零件或組合列入預先給定的零件組中做準備。
Kvearney和Tvrecker：FMS是數控機床的組成。它能任意地執行零件組，自動化物料的處理和中央計算機控制動態平衡資源的利用。因此，系統能自動的適應在零件生產，產品的品種組成和輸出方面的變化。FMS是一種可隨意的指定任務的自動化系統，這種系統基于承租制造技術，結合了計算機集成控制和一組可連續進行零件的自動處理和加工的機床。
FMS結合了微電子技術和機械工程能夠使批量生產更具有經濟性，中央在線計算機控制的機床，其他工作站，能完成零部件的傳輸和加工。計算機也能提高監控和信息控制，這種結合了靈活性和全局控制的方式使小批量大范圍的產品的生產成為可能。
在已有的能力和預先定義的規劃范圍內，在控制中執行零部件和產品的多樣化生產。
一種將幫助精良工廠獲得較快的加工時間的技術，是在一個較高水平的管理和中心控制下，實現較低的單元成本，較高的質量的生產。
基本上FMS是有軟件和硬件組成的。硬件部分是可見的，可觸摸的。例如：計算機數控化機床，旋轉式托盤，物料傳輸設備（機器人和自動引導小車），集中是排屑系統，刀庫，坐標測量機，工件清洗站和計算機硬件設備。軟件部分是不可見的無形的，例如：數控程序，交通管理軟件，刀具信息，坐標測量儀的工作順序文件和復雜的FMS軟件。圖8.1是典型的FMS布局和它的主要動態性組成和可確認的組成部件。
Unit9
為了理解提高自動化綜合生產力的限制因素，進行下面的類比，假設一輛汽車的多種輔助系統都已經自動化了，司機的工作會變得更加輕松，自動加速、減速、轉向、剎車
將會比人工操作更有效。然而，考慮一下將會發生的事，如果這些自動化的輔助系統在一定程度上沒有聯系在一起，即不能即時的連續的交流與分享精確的最新的信息，一個系統試圖加速，而另一個系統試圖剎車。在自動化制造設備上有同樣的制約，這些制約導致了如今制造技術發展的另一個階段：集成。
Unit15 滑尺的平移運動是通過使用空氣軸實現的，為了盡量減少摩擦，也為了減少因滑道缺陷引起的后果，一個合適的空氣源是必需的。基軸的運動完全依靠于廉價的手動三坐標測量儀，大多數手動機器都配有一個精確地手輪裝置，盡管許多用戶更喜歡直接用手來移動滑尺。
更昂貴的機器采用馬達驅動的軸驅動裝置，采用直流伺服電機通過特殊的機制運作，各軸均有即斷開關來控制并允許手動控制運動。
第三篇：機械工程英語第二版翻譯
第一單元
? Types of Materials
材料的類型
Materials may be grouped in several ways.Scientists often classify materials by their state: solid, liquid, or gas.They also separate them into organic(once living)and inorganic(never living)materials.材料可以按多種方法分類。科學家常根據狀態將材料分為：固體、液體或氣體。他們也把材料分為有機材料(曾經有生命的)和無機材料(從未有生命的)。
For industrial purposes, materials are divided into engineering materials or nonengineering materials.Engineering materials are those used in manufacture and become parts of products.就工業效用而言，材料被分為工程材料和非工程材料。那些用于加工制造并成為產品組成部分的就是工程材料。Nonengineering materials are the chemicals, fuels, lubricants, and other materials used in the manufacturing process, which do not become part of the product.非工程材料則是化學品、燃料、潤滑劑以及其它用于加工制造過程但不成為產品組成部分的材料。Engineering materials may be further subdivided into: ①Metal ②Ceramics ③Composite ④Polymers, etc.工程材料還能進一步細分為：①金屬材料②陶瓷材料③復合材料 ④聚合材料，等等。
? Metals and Metal Alloys 金屬和金屬合金
Metals are elements that generally have good electrical and thermal conductivity.Many metals have high strength, high stiffness, and have good ductility.金屬就是通常具有良好導電性和導熱性的元素。許多金屬具有高強度、高硬度以及良好的延展性。Some metals, such as iron, cobalt and nickel, are magnetic.At low temperatures, some metals and intermetallic compounds become superconductors.某些金屬能被磁化，例如鐵、鈷和鎳。在極低的溫度下，某些金屬和金屬化合物能轉變成超導體。
What is the difference between an alloy and a pure metal? Pure metals are elements which come from a particular area of the periodic table.Examples of pure metals include copper in electrical wires and aluminum in cooking foil and beverage cans.合金與純金屬的區別是什么？純金屬是在元素周期表中占據特定位置的元素。例如電線中的銅和制造烹飪箔及飲料罐的鋁。
Alloys contain more than one metallic element.Their properties can be changed by changing the elements present in the alloy.Examples of metal alloys include stainless steel which is an alloy of iron, nickel, and chromium;and gold jewelry which usually contains an alloy of gold and nickel.合金包含不止一種金屬元素。合金的性質能通過改變其中存在的元素而改變。金屬合金的例子有：不銹鋼是一
種鐵、鎳、鉻的合金，以及金飾品通常含有金鎳合金。
Why are metals and alloys used? Many metals and alloys have high densities and are used in applications which require a high mass-to-volume ratio.為什么要使用金屬和合金？許多金屬和合金具有高密度，因此被用在需要較高質量體積比的場合。Some metal alloys, such as those based on aluminum, have low densities and are used in aerospace applications for fuel economy.Many alloys also have high fracture toughness, which means they can withstand impact and are durable.某些金屬合金，例如鋁基合金，其密度低，可用于航空航天以節約燃料。許多合金還具有高斷裂韌性，這意味著它們能經得起沖擊并且是耐用的。
What are some important properties of metals? Density is defined as a material’s mass divided by its volume.Most metals have relatively high densities, especially compared to polymers.金屬有哪些重要特性？
密度定義為材料的質量與其體積之比。大多數金屬密度相對較高，尤其是和聚合物相比較而言。Materials with high densities often contain atoms with high atomic numbers, such as gold or lead.However, some metals such as aluminum or magnesium have low densities, and are used in applications that require other metallic properties but also require low weight.高密度材料通常由較大原子序數原子構成，例如金和鉛。然而，諸如鋁和鎂之類的一些金屬則具有低密度，并被用于既需要金屬特性又要求重量輕的場合。
Fracture toughness can be described as a material’s ability to avoid fracture, especially when a flaw is introduced.Metals can generally contain nicks and dents without weakening very much, and are impact resistant.A football player counts on this when he trusts that his facemask won’t shatter.斷裂韌性可以描述為材料防止斷裂特別是出現缺陷時不斷裂的能力。金屬一般能在有缺口和凹痕的情況下不顯著削弱，并且能抵抗沖擊。橄欖球運動員據此相信他的面罩不會裂成碎片。
Plastic deformation is the ability of bend or deform before breaking.As engineers, we usually design materials so that they don’t deform under normal conditions.You don’t want your car to lean to the east after a strong west wind.塑性變形就是在斷裂前彎曲或變形的能力。作為工程師，設計時通常要使材料在正常條件下不變形。沒有人愿意一陣強烈的西風過后自己的汽車向東傾斜。
However, sometimes we can take advantage of plastic deformation.The crumple zones in a car absorb energy by undergoing plastic deformation before they break.然而，有時我們也能利用塑性變形。汽車上壓皺的區域在它們斷裂前通過經歷塑性變形來吸收能量。The atomic bonding of metals also affects their properties.In metals, the outer valence electrons are shared among all atoms, and are free to travel everywhere.Since electrons conduct heat and electricity, metals make good cooking pans and
electrical wires.金屬的原子連結對它們的特性也有影響。在金屬內部，原子的外層階電子由所有原子共享并能到處自由移動。由于電子能導熱和導電，所以用金屬可以制造好的烹飪鍋和電線。
It is impossible to see through metals, since these valence electrons absorb any photons of light which reach the metal.No photons pass through.因為這些階電子吸收到達金屬的光子，所以透過金屬不可能看得見。沒有光子能通過金屬。
Alloys are compounds consisting of more than one metal.Adding other metals can affect the density, strength, fracture toughness, plastic deformation, electrical conductivity and environmental degradation.合金是由一種以上金屬組成的混合物。加一些其它金屬能影響密度、強度、斷裂韌性、塑性變形、導電性以及環境侵蝕。
For example, adding a small amount of iron to aluminum will make it stronger.Also, adding some chromium to steel will slow the rusting process, but will make it more brittle.例如，往鋁里加少量鐵可使其更強。同樣，在鋼里加一些鉻能減緩它的生銹過程，但也將使它更脆。
? Ceramics and Glasses 陶瓷和玻璃
A ceramic is often broadly defined as any inorganic nonmetallic material． By this definition, ceramic materials would also include glasses;however, many materials scientists add the stipulation that “ceramic” must also be crystalline.陶瓷通常被概括地定義為無機的非金屬材料。照此定義，陶瓷材料也應包括玻璃；然而許多材料科學家添加了“陶瓷”必須同時是晶體物組成的約定。
A glass is an inorganic nonmetallic material that does not have a crystalline structure.Such materials are said to be amorphous.玻璃是沒有晶體狀結構的無機非金屬材料。這種材料被稱為非結晶質材料。Properties of Ceramics and Glasses Some of the useful properties of ceramics and glasses include high melting temperature, low density, high strength, stiffness, hardness, wear resistance, and corrosion resistance.陶瓷和玻璃的特性
高熔點、低密度、高強度、高剛度、高硬度、高耐磨性和抗腐蝕性是陶瓷和玻璃的一些有用特性。
Many ceramics are good electrical and thermal insulators.Some ceramics have special properties: some ceramics are magnetic materials;some are piezoelectric materials;and a few special ceramics are superconductors at very low temperatures.Ceramics and glasses have one major drawback: they are brittle.許多陶瓷都是電和熱的良絕緣體。某些陶瓷還具有一些特殊性能：有些是磁性材料，有些是壓電材料，還有些特殊陶瓷在極低溫度下是超導體。陶瓷和玻璃都有一個主要的缺點：它們容易破碎。
Ceramics are not typically formed from the melt.This is because most ceramics will crack extensively(i.e.form a powder)upon cooling from the liquid state.陶瓷一般不是由熔化形成的。因為大多數陶瓷在從液態冷卻時將會完全破碎(即形成粉末)。
Hence, all the simple and efficient manufacturing techniques used for glass production such as casting and blowing, which involve the molten state, cannot be used for the production of crystalline ceramics.Instead, “sintering” or “firing” is the process typically used.因此，所有用于玻璃生產的簡單有效的—諸如澆鑄和吹制這些涉及熔化的技術都不能用于由晶體物組成的陶瓷的生產。作為替代，一般采用“燒結”或“焙燒”工藝。
In sintering, ceramic powders are processed into compacted shapes and then heated to temperatures just below the melting point.At such temperatures, the powders react internally to remove porosity and fully dense articles can be obtained.在燒結過程中，陶瓷粉末先擠壓成型然后加熱到略低于熔點溫度。在這樣的溫度下，粉末內部起反應去除孔隙并得到十分致密的物品。
An optical fiber contains three layers: a core made of highly pure glass with a high refractive index for the light to travel, a middle layer of glass with a lower refractive index known as the cladding which protects the core glass from scratches and other surface imperfections, and an out polymer jacket to protect the fiber from damage.光導纖維有三層：核心由高折射指數高純光傳輸玻璃制成，中間層為低折射指數玻璃，是保護核心玻璃表面不被擦傷和完整性不被破壞的所謂覆層，外層是聚合物護套，用于保護光導纖維不受損。
In order for the core glass to have a higher refractive index than the cladding, the core glass is doped with a small, controlled amount of an impurity, or dopant, which causes light to travel slower, but does not absorb the light.為了使核心玻璃有比覆層大的折射指數，在其中摻入微小的、可控數量的能減緩光速而不會吸收光線的雜質或攙雜劑。
Because the refractive index of the core glass is greater than that of the cladding, light traveling in the core glass will remain in the core glass due to total internal reflection as long as the light strikes the core/cladding interface at an angle greater than the critical angle.由于核心玻璃的折射指數比覆層大，只要在全內反射過程中光線照射核心/覆層分界面的角度比臨界角大，在核心玻璃中傳送的光線將仍保留在核心玻璃中。
The total internal reflection phenomenon, as well as the high purity of the core glass, enables light to travel long distances with little loss of intensity.全內反射現象與核心玻璃的高純度一樣，使光線幾乎無強度損耗傳遞長距離成為可能。
? Composites
復合材料
Composites are formed from two or more types of materials.Examples include polymer/ceramic and metal/ceramic
composites.Composites are used because overall properties of the composites are superior to those of the individual components.復合材料由兩種或更多材料構成。例子有聚合物/陶瓷和金屬/陶瓷復合材料。之所以使用復合材料是因為其全面性能優于組成部分單獨的性能。
For example: polymer/ceramic composites have a greater modulus than the polymer component, but aren’t as brittle as ceramics.Two types of composites are: fiber-reinforced composites and particle-reinforced composites.例如：聚合物/陶瓷復合材料具有比聚合物成分更大的模量，但又不像陶瓷那樣易碎。復合材料有兩種：纖維加強型復合材料和微粒加強型復合材料。Fiber-reinforced Composites Reinforcing fibers can be made of metals, ceramics, glasses, or polymers that have been turned into graphite and known as carbon fibers.Fibers increase the modulus of the matrix material.纖維加強型復合材料
加強纖維可以是金屬、陶瓷、玻璃或是已變成石墨的被稱為碳纖維的聚合物。纖維能加強基材的模量。The strong covalent bonds along the fiber’s length give them a very high modulus in this direction because to break or extend the fiber the bonds must also be broken or moved.沿著纖維長度有很強結合力的共價結合在這個方向上給予復合材料很高的模量，因為要損壞或拉伸纖維就必須破壞或移除這種結合。
Fibers are difficult to process into composites, making fiber-reinforced composites relatively expensive.把纖維放入復合材料較困難，這使得制造纖維加強型復合材料相對昂貴。
Fiber-reinforced composites are used in some of the most advanced, and therefore most expensive sports equipment, such as a time-trial racing bicycle frame which consists of carbon fibers in a thermoset polymer matrix.纖維加強型復合材料用于某些最先進也是最昂貴的運動設備，例如計時賽競賽用自行車骨架就是用含碳纖維的熱固塑料基材制成的。
Body parts of race cars and some automobiles are composites made of glass fibers(or fiberglass)in a thermoset matrix.競賽用汽車和某些機動車的車體部件是由含玻璃纖維(或玻璃絲)的熱固塑料基材制成的。
Fibers have a very high modulus along their axis, but have a low modulus perpendicular to their axis.Fiber composite manufacturers often rotate layers of fibers to avoid directional variations in the modulus.纖維在沿著其軸向有很高的模量，但垂直于其軸向的模量卻較低。纖維復合材料的制造者往往旋轉纖維層以防模量產生方向變化。
Particle-reinforced composites Particles used for reinforcing include ceramics and glasses such as small mineral particles, metal particles such as
aluminum, and amorphous materials，including polymers and carbon black.微粒加強型復合材料
用于加強的微粒包含了陶瓷和玻璃之類的礦物微粒，鋁之類的金屬微粒以及包括聚合物和碳黑的非結晶質微粒。
Particles are used to increase the modulus of the matrix, to decrease the permeability of the matrix, to decrease the ductility of the matrix.An example of particle-reinforced composites is an automobile tire which has carbon black particles in a matrix of polyisobutylene elastomeric polymer.微粒用于增加基材的模量、減少基材的滲透性和延展性。微粒加強型復合材料的一個例子是機動車胎，它就是在聚異丁烯人造橡膠聚合物基材中加入了碳黑微粒。
? Polymers
聚合材料
A polymer has a repeating structure, usually based on a carbon backbone.The repeating structure results in large chainlike molecules.Polymers are useful because they are lightweight, corrosion resistant, easy to process at low temperatures and generally inexpensive.聚合物具有一般是基于碳鏈的重復結構。這種重復結構產生鏈狀大分子。由于重量輕、耐腐蝕、容易在較低溫度下加工并且通常較便宜，聚合物是很有用的。
Some important characteristics of polymers include their size(or molecular weight), softening and melting points, crystallinity, and structure.The mechanical properties of polymers generally include low strength and high toughness.Their strength is often improved using reinforced composite structures.聚合材料具有一些重要特性，包括尺寸(或分子量)、軟化及熔化點、結晶度和結構。聚合材料的機械性能一般表現為低強度和高韌性。它們的強度通常可采用加強復合結構來改善。
Important Characteristics of Polymers Size.Single polymer molecules typically have molecular weights between 10,000 and 1,000,000g/mol—that can be more than 2,000 repeating units depending on the polymer structure!聚合材料的重要特性
尺寸：單個聚合物分子一般分子量為10,000到1,000,000g/mol之間，具體取決于聚合物的結構—這可以比2,000個重復單元還多。
The mechanical properties of a polymer are significantly affected by the molecular weight, with better engineering properties at higher molecular weights.聚合物的分子量極大地影響其機械性能，分子量越大，工程性能也越好。
Thermal transitions.The softening point(glass transition temperature)and the melting point of a polymer will determine which it will be suitable for applications.These temperatures usually determine the upper limit for which a polymer can be used.熱轉換性：聚合物的軟化點(玻璃狀轉化溫度)和熔化點決定了它是否適合應用。這些溫度通常決定聚合物能否使用的上限。
For example, many industrially important polymers have glass transition temperatures near the boiling point of water(100℃, 212℉), and they are most useful for room temperature applications.Some specially engineered polymers can withstand temperatures as high as 300℃(572℉).例如，許多工業上的重要聚合物其玻璃狀轉化溫度接近水的沸點(100℃, 212℉)，它們被廣泛用于室溫下。而某些特別制造的聚合物能經受住高達300℃(572℉)的溫度。
Crystallinity.Polymers can be crystalline or amorphous, but they usually have a combination of crystalline and amorphous structures(semi-crystalline).結晶度：聚合物可以是晶體狀的或非結晶質的，但它們通常是晶體狀和非結晶質結構的結合物(半晶體)。Interchain interactions.The polymer chains can be free to slide past one another(thermo-plastic)or they can be connected to each other with crosslinks(thermoset or elastomer).Thermo-plastics can be reformed and recycled, while thermosets and elastomers are not reworkable.原子鏈間的相互作用：聚合物的原子鏈可以自由地彼此滑動(熱可塑性)或通過交鍵互相連接(熱固性或彈性)。熱可塑性材料可以重新形成和循環使用，而熱固性與彈性材料則是不能再使用的。
Intrachain structure.The chemical structure of the chains also has a tremendous effect on the properties.Depending on the structure the polymer may be hydrophilic or hydrophobic(likes or hates water), stiff or flexible, crystalline or amorphous, reactive or unreactive.鏈內結構：原子鏈的化學結構對性能也有很大影響。根據各自的結構不同，聚合物可以是親水的或憎水的(喜歡或討厭水)、硬的或軟的、晶體狀的或非結晶質的、易起反應的或不易起反應的。
第二單元
The understanding of heat treatment is embraced by the broader study of metallurgy.Metallurgy is the physics, chemistry, and engineering related to metals from ore extraction to the final product.對熱處理的理解包含于對冶金學較廣泛的研究。冶金學是物理學、化學和涉及金屬從礦石提煉到最后產物的工程學。
Heat treatment is the operation of heating and cooling a metal in its solid state to change its physical properties.According to the procedure used, steel can be hardened to resist cutting action and abrasion, or it can be softened to permit machining.熱處理是將金屬在固態加熱和冷卻以改變其物理性能的操作。按所采用的步驟，鋼可以通過硬化來抵抗切削和磨損，也可以通過軟化來允許機加工。
With the proper heat treatment internal stresses may be removed, grain size reduced, toughness increased, or a hard surface produced on a ductile interior.The analysis of the steel must be known because small percentages of certain elements, notably carbon, greatly affect the physical properties.使用合適的熱處理可以去除內應力、細化晶粒、增加韌性或在柔軟材料上覆蓋堅硬的表面。因為某些元素(尤其是碳)的微小百分比極大地影響物理性能，所以必須知道對鋼的分析。
Alloy steel owe their properties to the presence of one or more elements other than carbon, namely nickel, chromium, manganese, molybdenum, tungsten, silicon, vanadium, and copper.Because of their improved physical properties they are used commercially in many ways not possible with carbon steels.合金鋼的性質取決于其所含有的除碳以外的一種或多種元素，如鎳、鉻、錳、鉬、鎢、硅、釩和銅。由于合金鋼改善的物理性能，它們被大量使用在許多碳鋼不適用的地方。
The following discussion applies principally to the heat treatment of ordinary commercial steels known as plain carbon steels.With this process the rate of cooling is the controlling factor, rapid cooling from above the critical range results in hard structure, whereas very slow cooling produces the opposite effect.下列討論主要針對被稱為普通碳鋼的工業用鋼而言。熱處理時冷卻速率是控制要素，從高于臨界溫度快速冷卻導致堅硬的組織結構，而緩慢冷卻則產生相反效果。
? A Simplified Iron-carbon Diagram 簡化鐵碳狀態圖
If we focus only on the materials normally known as steels, a simplified diagram is often used.如果只把注意力集中于一般所說的鋼上，經常要用到簡化鐵碳狀態圖。
Those portions of the iron-carbon diagram near the delta region and those above 2% carbon content are of little importance to the engineer and are deleted.A simplified diagram, such as the one in Fig.2.1, focuses on the eutectoid region and is quite useful in understanding the properties and processing of steel.鐵碳狀態圖中靠近三角區和含碳量高于2%的那些部分對工程師而言不重要，因此將它們刪除。如圖2.1所示的簡化鐵碳狀態圖將焦點集中在共析區，這對理解鋼的性能和處理是十分有用的。
The key transition described in this diagram is the decomposition of single-phase austenite(γ)to the two-phase ferrite plus carbide structure as temperature drops.在此圖中描述的關鍵轉變是單相奧氏體(γ)隨著溫度下降分解成兩相鐵素體加滲碳體組織結構。
Control of this reaction, which arises due to the drastically different carbon solubility of austenite and ferrite, enables a wide range of properties to be achieved through heat treatment.控制這一由于奧氏體和鐵素體的碳溶解性完全不同而產生的反應，使得通過熱處理能獲得很大范圍的特性。To begin to understand these processes, consider a steel of the eutectoid composition, 0.77% carbon, being slow cooled along line x-x’ in Fig.2.1.At the upper temperatures, only austenite is present, the 0.77% carbon being dissolved in solid solution with the iron.When the steel cools to 727℃(1341℉), several changes occur simultaneously.為了理解這些過程，考慮含碳量為0.77%的共析鋼，沿著圖2.1的x-x’線慢慢冷卻。在較高溫度時，只存在奧氏體，0.77%的碳溶解在鐵里形成固溶體。當鋼冷卻到727℃(1341℉)時，將同時發生若干變化。
The iron wants to change from the FCC austenite structure to the BCC ferrite structure, but the ferrite can only contain 0.02% carbon in solid solution.鐵需要從面心立方體奧氏體結構轉變為體心立方體鐵素體結構，但是鐵素體只能容納固溶體狀態的0.02%的碳。The rejected carbon forms the carbon-rich cementite intermetallic with composition Fe3C.In essence, the net reaction at the eutectoid is austenite 0.77%C→ferrite 0.02%C+cementite 6.67%C.被析出的碳與金屬化合物Fe3C形成富碳的滲碳體。本質上，共析體的基本反應是奧氏體0.77%的碳→鐵素體0.02%的碳+滲碳體6.67%的碳。
Since this chemical separation of the carbon component occurs entirely in the solid state, the resulting structure is a fine mechanical mixture of ferrite and cementite.Specimens prepared by polishing and etching in a weak solution of nitric acid and alcohol reveal the lamellar structure of alternating plates that forms on slow cooling.由于這種碳成分的化學分離完全發生在固態中，產生的組織結構是一種細致的鐵素體與滲碳體的機械混合物。通過打磨并在弱硝酸酒精溶液中蝕刻制備的樣本顯示出由緩慢冷卻形成的交互層狀的薄片結構。
This structure is composed of two distinct phases, but has its own set of characteristic properties and goes by the name pearlite, because of its resemblance to mother-of-pearl at low magnification.這種結構由兩種截然不同的狀態組成，但它本身具有一系列特性，且因與低倍數放大時的珠母層有類同之處而被稱為珠光體。
Steels having less than the eutectoid amount of carbon(less than 0.77%)are known as hypo-eutectoid steels.Consider now the transformation of such a material represented by cooling along line y-y’ in Fig.2.1.含碳量少于共析體(低于0.77%)的鋼稱為亞共析鋼。現在來看這種材料沿著圖2.1中y-y’ 線冷卻的轉變情況。At high temperatures, the material is entirely austenite, but upon cooling enters a region where the stable phases are ferrite and austenite.Tie-line and level-law calculations show that low-carbon ferrite nucleates and grows, leaving the remaining austenite richer in carbon.在較高溫度時，這種材料全部是奧氏體，但隨著冷卻就進入到鐵素體和奧氏體穩定狀態的區域。由截線及杠桿定律分析可知，低碳鐵素體成核并長大，剩下含碳量高的奧氏體。
At 727℃(1341℉), the austenite is of eutectoid composition(0.77% carbon)and further cooling transforms the remaining austenite to pearlite.The resulting structure is a mixture of primary or pro-eutectoid ferrite(ferrite that formed above the eutectoid reaction)and regions of pearlite.在727℃(1341℉)時，奧氏體為共析組成(含碳量0.77%)，再冷卻剩余的奧氏體就轉化為珠光體。作為結果的組織結構是初步的共析鐵素體(在共析反應前的鐵素體)和部分珠光體的混合物。
Hypereutectoid steels are steels that contain greater than the eutectoid amount of carbon.When such steel cools, as shown in z-z’ of Fig.2.1 the process is similar to the hypo-eutectoid case, except that the primary or pro-eutectoid phase is now cementite instead of ferrite.過共析鋼是含碳量大于共析量的鋼。當這種鋼冷卻時，就像圖2.1的z-z’線所示，除了初步的共析狀態用滲碳體取代鐵素體外，其余類似亞共析鋼的情況。
As the carbon-rich phase forms, the remaining austenite decreases in carbon content, reaching the eutectoid composition at 727℃(1341℉).As before, any remaining austenite transforms to pearlite upon slow cooling through this temperature.隨著富碳部分的形成，剩余奧氏體含碳量減少，在727℃(1341℉)時達到共析組織。就像以前說的一樣，當緩慢冷卻到這溫度時所有剩余奧氏體轉化為珠光體。
It should be remembered that the transitions that have been described by the phase diagrams are for equilibrium conditions, which can be approximated by slow cooling.With slow heating, these transitions occur in the reverse manner.應該記住由狀態圖描述的這種轉化只適合于通過緩慢冷卻的近似平衡條件。如果緩慢加熱，則以相反的方式發生這種轉化。
However, when alloys are cooled rapidly, entirely different results may be obtained, because sufficient time is not provided for the normal phase reactions to occur, in such cases, the phase diagram is no longer a useful tool for engineering analysis.然而，當快速冷卻合金時，可能得到完全不同的結果。因為沒有足夠的時間讓正常的狀態反應發生，在這種情況下對工程分析而言狀態圖不再是有用的工具。
? Hardening
淬火
Hardening is the process of heating a piece of steel to a temperature within or above its critical range and then cooling it rapidly.淬火就是把鋼件加熱到或超過它的臨界溫度范圍，然后使其快速冷卻的過程。
If the carbon content of the steel is known, the proper temperature to which the steel should be heated may be obtained by reference to the iron-iron carbide phase diagram.However, if the composition of the steel is unknown, a little preliminary experimentation may be necessary to determine the range.如果鋼的含碳量已知，鋼件合適的加熱溫度可參考鐵碳合金狀態圖得到。然而當鋼的成分不知道時，則需做一些預備試驗來確定其溫度范圍。
A good procedure to follow is to heat-quench a number of small specimens of the steel at various temperatures and observe the result, either by hardness testing or by microscopic examination.When the correct temperature is obtained, there will be a marked change in hardness and other properties.要遵循的合適步驟是將這種鋼的一些小試件加熱到不同的溫度后淬火，再通過硬度試驗或顯微鏡檢查觀測結果。一旦獲得正確的溫度，硬度和其它性能都將有明顯的變化。
In any heat-treating operation the rate of heating is important.Heat flows from the exterior to the interior of steel at a definite rate.If the steel is heated too fast, the outside becomes hotter than the interior and uniform structure cannot be obtained.在任何熱處理作業中，加熱的速率都是重要的。熱量以一定的速率從鋼的外部傳導到內部。如果鋼被加熱得太快，其外部比內部熱就不能得到均勻的組織結構。
If a piece is irregular in shape, a slow rate is all the more essential to eliminate warping and cracking.The heavier the section, the longer must be the heating time to achieve uniform results.如果工件形狀不規則，為了消除翹曲和開裂最根本的是加熱速率要緩慢。截面越厚，加熱的時間就要越長才能達到均勻的結果。
Even after the correct temperature has been reached, the piece should be held at that temperature for a sufficient period of time to permit its thickest section to attain a uniform temperature.即使加熱到正確的溫度后，工件也應在此溫度下保持足夠時間以讓其最厚截面達到相同溫度。
The hardness obtained from a given treatment depends on the quenching rate, the carbon content, and the work size.In alloy steels the kind and amount of alloying element influences only the hardenability(the ability of the workpiece to be hardened to depths)of the steel and does not affect the hardness except in unhardened or partially hardened steels.通過給定的熱處理所得到的硬度取決于淬火速率、含碳量和工件尺寸。除了非淬硬鋼或部分淬硬鋼外，合金鋼中合金元素的種類及含量僅影響鋼的淬透性(工件被硬化到深層的能力)而不影響硬度。
Steel with low carbon content will not respond appreciably to hardening treatment.As the carbon content in steel increases up to around 0.60%, the possible hardness obtainable also increases.含碳量低的鋼對淬火處理沒有明顯的反應。隨著鋼的含碳量增加到大約0.60%，可能得到的硬度也增加。Above this point the hardness can be increased only slightly, because steels above the eutectoid point are made up entirely of pearlite and cementite in the annealed state.Pearlite responds best to heat-treating operations;and steel composed mostly of pearlite can be transformed into a hard steel.高于此點，由于超過共析點鋼完全由珠光體和退火狀態的滲碳體組成，硬度增加并不多。珠光體對熱處理作業響應最好；基本由珠光體組成的鋼能轉化成硬質鋼。
As the size of parts to be hardened increases, the surface hardness decreases somewhat even though all other conditions have remained the same.There is a limit to the rate of heat flow through steel.即使所有其它條件保持不變，隨著要淬火的零件尺寸的增加其表面硬度也會有所下降。熱量在鋼中的傳導速率是有限的。
No matter how cool the quenching medium may be, if the heat inside a large piece cannot escape faster than a certain critical rate, there is a definite limit to the inside hardness.However, brine or water quenching is capable of rapidly bringing the surface of the quenched part to its own temperature and maintaining it at or close to this temperature.無論淬火介質怎么冷，如果在大工件中的熱量不能比特定的臨界速率更快散發，那它內部硬度就會受到明確限制。然而鹽水或水淬火能夠將被淬零件的表面迅速冷卻至本身溫度并將其保持或接近此溫度。
Under these circumstances there would always be some finite depth of surface hardening regardless of size.This is not true in oil quenching, when the surface temperature may be high during the critical stages of quenching.在這種情況下不管零件尺寸如何，其表面總歸有一定深度被硬化。但油淬情況就不是如此，因為油淬時在淬火臨界階段零件表面的溫度可能仍然很高。
? Tempering
回火
Steel that has been hardened by rapid quenching is brittle and not suitable for most uses.By tempering or drawing, the hardness and brittleness may be reduced to the desired point for service conditions．
快速淬火硬化的鋼是硬而易碎的，不適合大多數場合使用。通過回火，硬度和脆性可以降低到使用條件所需要的程度。
As these properties are reduced there is also a decrease in tensile strength and an increase in the ductility and toughness of the steel.The operation consists of reheating quench-hardened steel to some temperature below the critical range followed by any rate of cooling.隨著這些性能的降低，拉伸強度也降低而鋼的延展性和韌性則會提高。回火作業包括將淬硬鋼重新加熱到低于臨界范圍的某一溫度然后以任意速率冷卻。
Although this process softens steel, it differs considerably from annealing in that the process lends itself to close control of the physical properties and in most cases does not soften the steel to the extent that annealing would.The final structure obtained from tempering a fully hardened steel is called tempered martensite.雖然這過程使鋼軟化，但它與退火是大不相同的，因為回火適合于嚴格控制物理性能并在大多數情況下不會把鋼軟化到退火那種程度。回火完全淬硬鋼得到的最終組織結構被稱為回火馬氏體。
Tempering is possible because of the instability of the martensite, the principal constituent of hardened steel.Low-temperature draws, from 300℉ to 400℉(150℃~205℃), do not cause much decrease in hardness and are used principally to relieve internal strains.由于馬氏體這一淬硬鋼主要成分的不穩定性，使得回火成為可能。低溫回火，300℉到400℉(150℃~205℃)，不會引起硬度下降很多，主要用于減少內部應變。
As the tempering temperatures are increased, the breakdown of the martensite takes place at a faster rate, and at about 600℉(315℃)the change to a structure called tempered martensite is very rapid.The tempering operation may be described as one of precipitation and agglomeration or coalescence of cementite.隨著回火溫度的提高，馬氏體以較快的速率分解，并在大約600℉(315℃)迅速轉變為被稱為回火馬氏體的結構。回火作業可以描述為滲碳體析出和凝聚或聚結的過程。
A substantial precipitation of cementite begins at 600℉(315℃), which produces a decrease in hardness.Increasing the temperature causes coalescence of the carbides with continued decrease in hardness.滲碳體的大量析出開始于600℉(315℃)，這使硬度下降。溫度的上升會使碳化物聚結而硬度繼續降低。In the process of tempering, some consideration should be given to time as well as to temperature.Although most of the softening action occurs in the first few minutes after the temperature is reached, there is some additional reduction in hardness if the temperature is maintained for a prolonged time.在回火過程中，不但要考慮溫度而且要考慮時間。雖然大多數軟化作用發生在達到所需溫度后的最初幾分鐘，但如果此溫度維持一段延長時間，仍會有些額外的硬度下降。
Usual practice is to heat the steel to the desired temperature and hold it there only long enough to have it uniformly heated.通常的做法是將鋼加熱到所需溫度并且僅保溫到正好使其均勻受熱。
Two special processes using interrupted quenching are a form of tempering.In both, the hardened steel is quenched in a salt bath held at a selected lower temperature before being allowed to cool.These processes, known as austempering and martempering, result in products having certain desirable physical properties.兩種采用中斷淬火的特殊工藝也是回火的形式。這兩種工藝中，淬硬鋼在其被允許冷卻前先在一選定的較低溫度鹽浴淬火。這兩種分別被稱為奧氏體回火和馬氏體回火的工藝，能使產品具有特定所需的物理性能。
? Annealing
退火
The primary purpose of annealing is to soften hard steel so that it may be machined or cold worked.退火的主要目的是使堅硬的鋼軟化以便機加工或冷作。
This is usually accomplished by heating the steel too slightly above the critical temperature, holding it there until the temperature of the piece is uniform throughout, and then cooling at a slowly controlled rate so that the temperature of the surface and that of the center of the piece are approximately the same.通常是非常緩慢地將鋼加熱到臨界溫度以上，并將其在此溫度下保持到工件全部均勻受熱，然后以受控的速率慢慢地冷卻，這樣使得工件表面和內部的溫度近似相同。
This process is known as full annealing because it wipes out all trace of previous structure, refines the crystalline structure, and softens the metal.Annealing also relieves internal stresses previously set up in the metal.這過程被稱為完全退火，因為它去除了以前組織結構的所有痕跡、細化晶粒并軟化金屬。退火也釋放了先前在金屬中的內應力。
The temperature to which a given steel should be heated in annealing depends on its composition;for carbon steels it can be obtained readily from the partial iron-iron carbide equilibrium diagram.When the annealing temperature has been reached, the steel should be held there until it is uniform throughout.給定的鋼其退火溫度取決于它的成分；對碳鋼而言可容易地從局部的鐵碳合金平衡圖得到。達到退火溫度后，鋼應當保持在此溫度等到全部均勻受熱。
This usually takes about 45min for each inch(25mm)of thickness of the largest section.For maximum softness and ductility the cooling rate should be very slow, such as allowing the parts to cool down with the furnace.The higher the carbon content, the slower this rate must be.加熱時間一般以工件的最大截面厚度計每英寸(25mm)大約需45min。為了得到最大柔軟性和延展性冷卻速率應該很慢，比如讓零件與爐子一起冷下來。含碳量越高，冷卻的速率必須越慢。
The heating rate should be consistent with the size and uniformity of sections, so that the entire part is brought up to temperature as uniformly as possible.加熱的速率也應與截面的尺寸及均勻程度相協調，這樣才能使整個零件盡可能均勻地加熱。
? Normalizing and Spheroidizing 正火和球化
The process of normalizing consists of heating the steel about 50℉ to 100℉
(10℃~40℃)above the upper critical range and cooling in still air to room temperature.正火處理包括先將鋼加熱到高于上臨界區50℉到100℉(10℃~40℃)然后在靜止的空氣中冷卻到室溫。This process is principally used with low-and medium-carbon steels as well as alloy steels to make the grain structure more uniform, to relieve internal stresses, or to achieve desired results in physical properties.Most commercial steels are normalized after being rolled or cast.退火主要用于低碳鋼、中碳鋼及合金鋼，使晶粒結構更均勻、釋放內應力或獲得所需的物理特性。大多數商業鋼材在軋制或鑄造后都要退火。
Spheroidizing is the process of producing a structure in which the cementite is in a spheroidal distribution.If steel is heated slowly to a temperature just below the critical range and held there for a prolonged period of time, this structure will be obtained.球化是使滲碳體產生成類似球狀分布結構的工藝。如果把鋼緩慢加熱到恰好低于臨界溫度并且保持較長一段時間，就能得到這種組織結構。
The globular structure obtained gives improved machinability to the steel.This treatment is particularly useful for hypereutectoid steels that must be machined.所獲得的球狀結構改善了鋼的可切削性。此處理方法對必須機加工的過共析鋼特別有用。
? Surface Hardening 表面硬化 Carburizing The oldest known method of producing a hard surface on steel is case hardening or carburizing.Iron at temperatures close to and above its critical temperature has an affinity for carbon.滲碳
最早的硬化鋼表面的方法是表面淬火或滲碳。鐵在靠近并高于其臨界溫度時對碳具有親合力。
The carbon is absorbed into the metal to form a solid solution with iron and converts the outer surface into high-carbon steel.The carbon is gradually diffused to the interior of the part.The depth of the case depends on the time and temperature of the treatment.碳被吸收進金屬與鐵形成固溶體使外表面轉變成高碳鋼。碳逐漸擴散到零件內部。滲碳層的深度取決于熱處理的時間和溫度。
Pack carburizing consists of placing the parts to be treated in a closed container with some carbonaceous material such as charcoal or coke.It is a long process and used to produce fairly thick cases of from 0.03 to 0.16 in.(0.76~4.06mm)in depth.固體滲碳的方法是將要處理的零件與木炭或焦炭這些含碳的材料一起放入密閉容器。這是一個較長的過程，用于產生深度為0.03到0.16 英寸(0.76~4.06mm)這么厚的硬化層。
Steel for carburizing is usually a low-carbon steel of about 0.15% carbon that would not in itself responds appreciably to heat treatment.In the course of the process the outer layer is converted into high-carbon steel with a content ranging from 0.9% to 1.2% carbon.用于滲碳的一般是含碳量約為0.15%、本身不太適合熱處理的低碳鋼。在處理過程中外層轉化為含碳量從0.9%到1.2%的高碳鋼。
A steel with varying carbon content and, consequently, different critical temperatures requires a special heat treatment.含碳量變化的鋼具有不同的臨界溫度，因此需要特殊的熱處理。
Because there is some grain growth in the steel during the prolonged carburizing treatment, the work should be heated to the critical temperature of the core and then cooled, thus refining the core structure.The steel should then be reheated to a point above the transformation range of the case and quenched to produce a hard, fine structure.由于在較長的滲碳過程中鋼內部會有些晶粒生長，所以工件應該加熱到核心部分的臨界溫度再冷卻以細化核心部分的組織結構。然后重新加熱到高于外層轉變溫度再淬火以生成堅硬、細致的組織結構。
The lower heat-treating temperature of the case results from the fact that hypereutectoid steels are normally austenitized for hardening just above the lower critical point.A third tempering treatment may be used to reduce strains.由于恰好高于低臨界溫度通常使過共析鋼奧氏體化而硬化，所以對外層采用較低的熱處理溫度。第三次回火處理可用于減少應變。
Carbonitriding Carbonitriding, sometimes known as dry cyaniding or nicarbing, is a case-hardening process in which the steel is held at a temperature above the critical range in a gaseous atmosphere from which it absorbs carbon and nitrogen.碳氮共滲
碳氮共滲，有時也稱為干法氰化或滲碳氮化，是一種表面硬化工藝。通過把鋼放在高于臨界溫度的氣體中，讓它吸收碳和氮。
Any carbon-rich gas with ammonia can be used.The wear-resistant case produced ranges from 0.003 to 0.030 inch(0.08~ 0.76mm)in thickness.An advantage of carbonitriding is that the hardenability of the case is significantly increased when nitrogen is added, permitting the use of low-cost steels.可以使用任何富碳氣體加氨氣，能生成厚度從0.003到0.030英寸(0.08~ 0.76mm)的耐磨外層。碳氮共滲的優點之一是加入氮后外層的淬透性極大增加，為使用低價鋼提供條件。
Cyaniding Cyaniding, or liquid carbonitriding as it is sometimes called, is also a process that combines the absorption of carbon and nitrogen to obtain surface hardness in low-carbon steels that do not respond to ordinary heat treatment.氰化
氰化，有時稱為液體碳氮共滲，也是一種結合了吸收碳和氮來獲得表面硬度的工藝，它主要用于不適合通常熱處理的低碳鋼。
The part to be case hardened is immersed in a bath of fused sodium cyanide salts at a temperature slightly above the Ac1 range, the duration of soaking depending on the depth of the case.The part is then quenched in water or oil to obtain a hard surface.需表面硬化的零件浸沒在略高于Ac1溫度熔化的氰化鈉鹽溶液中，浸泡的持續時間取決于硬化層的深度。然后將零件在水或油中淬火。
Case depths of 0.005 to 0.015in.(0.13~0.38mm)may be readily obtained by this process.Cyaniding is used principally for the treatment of small parts.通過這樣處理可以容易地獲得0.005到0.015英寸(0.13~0.38mm)的硬化深度。氰化主要用于處理小零件。Nitriding Nitriding is somewhat similar to ordinary case hardening, but it uses a different material and treatment to create the hard surface constituents.滲氮
滲氮有些類似普通表面硬化，但它采用不同的材料和處理方法來產生堅硬表面成分。
In this process the metal is heated to a temperature of around 950℉(510℃)and held there for a period of time in contact with ammonia gas.Nitrogen from the gas is introduced into the steel, forming very hard nitrides that are finely dispersed through the surface metal.這種工藝中金屬加熱到約950℉(510℃)，然后與氨氣接觸一段時間。氨氣中的氮進入鋼內，形成細微分布于金屬表面又十分堅固的氮化物。
Nitrogen has greater hardening ability with certain elements than with others, hence, special nitriding alloy steels have been developed.氮與某些元素的硬化能力比其它元素大，因此開發了專用的滲氮合金鋼。
Aluminum in the range of 1% to 1.5% has proved to be especially suitable in steel, in that it combines with the gas to form a very stable and hard constituent.The temperature of heating ranges from 925℉ to 1,050℉(495℃~565℃).在鋼中含鋁1%到1.5%被證明特別合適，它能與氨氣結合形成很穩定堅固的成分。其加熱溫度范圍為925℉到1,050℉(495℃~565℃)。
Liquid nitriding utilizes molten cyanide salts and, as in gas nitriding, the temperature is held below the transformation range.Liquid nitriding adds more nitrogen and less carbon than either cyaniding or carburizing in cyanide baths.液體滲氮利用熔化的氰化物鹽，就像氣體滲氮，溫度保持在低于轉化范圍內。液體滲氮時在氰化物溶液中加入比氰化及滲碳都較多的氮和較少的碳。
Case thickness of 0.001 to 0.012in.(0.03~0.30mm)is obtained, whereas for gas nitriding the case may be as thick as 0.025 in.(0.64mm).In general the uses of the two-nitriding processes are similar.液體滲氮可以獲得厚度為0.001到0.012英寸(0.03~0.30mm)的硬化層，然而氣體滲氮則能獲得厚0.025英寸(0.64mm)的硬化層。一般而言兩種滲氮方法的用途是類似的。
Nitriding develops extreme hardness in the surface of steel.This hardness ranges from 900 to 1,100 Brinell, which is considerably higher than that obtained by ordinary case hardening.滲氮在鋼表面獲得遠遠超出正常標準的硬度。其硬度范圍為900到1,100布氏硬度，這遠高于普通表面硬化所獲得的硬度。
Nitriding steels, by virtue of their alloying content, are stronger than ordinary steels and respond readily to heat treatment.It is recommended that these steels be machined and heat-treated before nitriding, because there is no scale or further work necessary after this process.由于滲氮鋼的合金比例，它們比普通鋼更強，也容易熱處理。建議對這種鋼在滲氮前先機加工和熱處理，因為滲氮后沒有剝落并不需要更多的加工。
Fortunately, the interior structure and properties are not affected appreciably by the nitriding treatment and, because no quenching is necessary, there is little tendency to warp, develop cracks, or change condition in any way.The surface
effectively resists corrosive action of water, saltwater spray, alkalies, crude oil, and natural gas.值得慶幸的是由于滲氮處理一點都不影響內部結構和性能，也無需淬火，所以幾乎沒有任何產生翹曲、裂縫及變化條件的趨勢。這種表面能有效地抵御水、鹽霧、堿、原油和天然氣的腐蝕反應。
第三單元
Casting is a manufacturing process in which molten metal is poured or injected and allowed to solidify in a suitably shaped mold cavity.During or after cooling, the cast part is removed from the mold and then processed for delivery.鑄造是一種將熔化的金屬倒入或注入合適的鑄模腔并且在其中固化的制造工藝。在冷卻期間或冷卻后，把鑄件從鑄模中取出，然后進行交付。
Casting processes and cast-material technologies vary from simple to highly complex.Material and process selection depends on the part’s complexity and function, the product’s quality specifications, and the projected cost level.鑄造工藝和鑄造材料技術從簡單到高度復雜變化很大。材料和工藝的選擇取決于零件的復雜性和功能、產品的質量要求以及成本預算水平。
Castings are parts that are made close to their final dimensions by a casting process.With a history dating back 6,000 years, the various casting processes are in a state of continuous refinement and evolution as technological advances are being made.通過鑄造加工，鑄件可以做成很接近它們的最終尺寸。回溯6,000年歷史，各種各樣的鑄造工藝就如同科技進步一樣處于一個不斷改進和發展的狀態。
? Sand Casting
砂型鑄造
Sand casting is used to make large parts(typically iron, but also bronze, brass, aluminum).Molten metal is poured into a mold cavity formed out of sand(natural or synthetic).砂型鑄造用于制造大型零件(具有代表性是鐵，除此之外還有青銅、黃銅和鋁)。將熔化的金屬倒入由型砂(天然的或人造的)做成鑄模腔。
The processes of sand casting are discussed in this section, including patterns, sprues and runners, design considerations, and casting allowance.本節討論砂型鑄造工藝，包括型模、澆注口、澆道、設計考慮因素及鑄造余量。
The cavity in the sand is formed by using a pattern(an approximate duplicate of the real part), which are typically made out of wood, sometimes metal.The cavity is contained in an aggregate housed in a box called the flask.砂型里的型腔是采用型模(真實零件的近似復制品)構成的，型模一般為木制，有時也用金屬制造。型腔整個包含在一個被放入稱為砂箱的箱子里的組合體內。
Core is a sand shape inserted into the mold to produce the internal features of the part such as holes or internal passages.Cores are placed in the cavity to form holes of the desired shapes.Core print is the region added to the pattern, core, or mold that is used to locate and support the core within the mold.砂芯是插入鑄模的砂型，用于生成諸如孔或內通道之類的內部特征。砂芯安放在型腔里形成所需形狀的孔洞。砂芯座是加在型模、砂芯或鑄模上的特定區域，用來在鑄模內部定位和支撐砂芯。
A riser is an extra void created in the mold to contain excessive molten material.The purpose of this is to feed the molten metal to the mold cavity as the molten metal solidifies and shrinks, and thereby prevents voids in the main casting.冒口是在鑄模內部增加的額外空間，用于容納過多的熔化金屬。其目的是當熔化金屬凝固和收縮時往型腔里補充熔化金屬，從而防止在主鑄件中產生孔隙。
In a two-part mold, which is typical of sand castings, the upper half, including the top half of the pattern, flask, and core is called cope and the lower half is called drag, as shown in Fig.3.1.The parting line or the parting surface is line or surface that separates the cope and drag.在典型砂型鑄造的兩箱鑄模中，上半部分(包括型模頂半部、砂箱和砂芯)稱為上型箱，下半部分稱為下型箱，見圖3.1所示。分型線或分型面是分離上下型箱的線或面。
The drag is first filled partially with sand, and the core print, the cores, and the gating system are placed near the parting line.The cope is then assembled to the drag, and the sand is poured on the cope half, covering the pattern, core and the gating system.首先往下型箱里部分地填入型砂和砂芯座、砂芯，并在靠近分型線處放置澆注系統。然后將上型箱與下型箱裝配在一起，再把型砂倒入上型箱蓋住型模、砂芯和澆注系統。
The sand is compacted by vibration and mechanical means.Next, the cope is removed from the drag, and the pattern is carefully removed.The object is to remove the pattern without breaking the mold cavity.型砂通過振動和機械方法壓實。然后從下型箱上撤掉上型箱，小心翼翼地取出型模。其目的是取出型模而不破壞型腔。
This is facilitated by designing a draft, a slight angular offset from the vertical to the vertical surfaces of the pattern.This is usually a minimum of 1.5mm(0.060in.), whichever is greater.The rougher the surface of the pattern, the more the draft to be provided.通過設計拔模斜度—型模垂直相交表面的微小角度偏移量—來使取出型模變得容易。拔模斜度最小一般為1.5mm(0.060in.)，只能比此大。型模表面越粗糙，則拔模斜度應越大。
The molten material is poured into the pouring cup, which is part of the gating system that supplies the molten material to the mold cavity.熔化的金屬從澆注杯注入型腔，澆注杯是澆注系統向型腔提供熔化金屬的部分。
The vertical part of the gating system connected to the pouring cup is the sprue, and the horizontal portion is called the runners and finally to the multiple points where it is introduced to the mold cavity called the gates.將澆注系統的垂直部分與澆注杯連接的是澆注口，澆注系統的水平部分稱為澆道，最后到多點把熔化金屬導入型腔的稱為閘道。
Additionally there are extensions to the gating system called vents that provide the path for the built-up gases and the displaced air to vent to the atmosphere.除此之外，還有稱為排放口的澆注系統延長段，它為合成氣體和置換空氣排放到大氣提供通道。
The cavity is usually made oversize to allow for the metal contraction as it cools down to room temperature.This is achieved by making the pattern oversize.To account for shrinking, the pattern must be made oversize by these factors on the average.These are linear factors and apply in each direction.型腔通常大于所需尺寸以允許在金屬冷卻到室溫時收縮。這通過把型模做得大于所需尺寸來達到。為解決收縮效應，一般而言型模做得比所需尺寸大，必須考慮線性因素并作用于各個方向。
These shrinkage allowances are only approximate, because the exact allowance is determined by the shape and size of the casting.In addition, different parts of the casting might require different shrinkage allowances.收縮余量僅僅是近似的，因為準確的余量是由鑄件的形狀和尺寸決定的。另外，鑄件的不同部分也可能需要不同的收縮余量。
Sand castings generally have a rough surface sometimes with surface impurities, and surface variations.A machining(finish)allowance is made for this type of defect.砂型鑄件一般表面粗糙，有時還帶有表面雜質和表面變異。對這類缺陷采用機加工(最后一道工序)的余量。In general, typical stages of sand casting operation include(as shown in Fig.3.2): 1.Patterns are made.These will be the shape used to form the cavity in the sand.一般而言，砂型鑄造作業的典型階段包括(如圖3.2所示)： 1.制作型模。做成用于在型砂中形成型腔的形狀。
2.Cores may also be made at this time.These cores are made of bonded sand that will be broken out of the cast part after it is complete.3.Sand is mulled(mixed)thoroughly with additives such as bentonite to increase bonding and overall strength.2.同時還要制作砂芯。這些砂芯用粘結砂做成，等鑄件完成后將被打碎取出。3.型砂與膨潤土之類的添加劑充分地混合以增強連接及整體強度。
4.Sand is formed about the patterns, and gates, runners, risers, vents and pouring cups are added as needed.A
compaction stage is typically used to ensure good coverage and solid molds.4.型砂在型模周圍成形，并根據需要安放閘道、澆道、冒口、排放口和澆注杯等。通常要采取壓緊步驟來保證良好的覆蓋和堅固的鑄型。
Cores may also be added to make concave or internal features for the cast part.Alignment pins may also be used for mating the molds later.Chills may be added to cool large masses faster.安放砂芯來制成鑄件的凹形結構或內部特征。為了以后鑄模匹配還要用到定位銷。對大質量鑄件可能需要加入冷卻物來使其較快冷卻。
5.The patterns are removed, and the molds may be put through a baking stage to increase strength.6.Mold halves are mated and prepared for pouring metal.5.取走型模，將鑄模烘焙以增加強度。6.匹配上下鑄模，做好澆鑄金屬的準備。
7.Metal is preheated in a furnace or crucible until is above the liquidus temperature in a suitable range(we don’t want the metal solidifying before the pour is complete).The exact temperature may be closely controlled depending upon the application.7.金屬在熔爐或坩堝中預熱到高于液化溫度的一個合適范圍內(不希望金屬在澆鑄完成前凝固)。確切的溫度要根據應用場合嚴格控制。
Degassing, and other treatment processes may be done at this time, such as removal of impurities(i.e.slag).Some portion of this metal may be remelted scrap from previously cast parts—10% is reasonable.在此期間還要進行排氣和其它處理步驟，例如去除雜質(即熔渣)。可以加入一定量原先是這種金屬鑄件的廢料再融化—10%是適當的。
8.The metal is poured slowly, but continuously into the mold until the mold is full.9.As the molten metal cools(minutes to days), the metal will shrink and the volume will decrease.During this time molten metal may backflow from the molten risers to feed the part and maintain the same shape.8.將金屬緩慢而連續地注滿型模。
9.隨著熔化金屬的冷卻(幾分鐘到幾天)，金屬收縮體積減小。在此期間熔化金屬可能從冒口回流供給零件以保持其形狀不變。
10.Once the part starts to solidify small dendrites of solid material form in the part.During this time metal properties are being determined, and internal stresses are being generated.If a part is allowed to cool slowly enough at a constant rate then the final part will be relatively homogenous and stress free.10.在零件開始凝固其內部形成固態金屬的小型樹枝狀結晶期間金屬性能被確定，同時也產生了內應力。如果零件以恒定速率冷卻得足夠緩慢，最終零件將相對均質并釋放內應力。
11.Once the part has completely solidified below the eutectic point it may be removed with no concern for final metal
properties.At this point the sand is simply broken up, and the part removed.At this point the surface will have a quantity of sand adhering to the surface, and solid cores inside.11.一旦零件在共析點以下完全凝固，可以不考慮金屬的最后性能而將其取出。這時可以簡單地打碎砂型并取出零件，但零件表面會有大量型砂粘附著，內部還有實心的砂芯。
12.A bulk of the remaining sand and cores can be removed by mechanically striking the part.Other options are to use a vibrating table, sand/shot blaster, hand labor, etc.12.大量的剩余型砂和砂芯要通過機械敲擊零件來去除。其它的選擇還有采用振動臺、噴砂/噴丸機、手工作業等等。
13.The final part is cut off the runner gate system, and is near final shape using cutters, torches, etc.Grinding operations are used to remove any remaining bulk.14.The part is taken down to final shape using machining operations.And cleaning operations may be used to remove oxides, etc.13.最后零件要用刀具、噴槍等切掉澆道閘道系統，這樣就接近最終形狀了。再用磨削作業去除多余的部分。14.通過機加工將零件切削到最終形狀。可能還要用清洗作業去除氧化物等。
? Investment casting 熔模鑄造
Investment casting is also known as the lost wax process.This process is one of the oldest manufacturing processes.The Egyptians used it in the time of the Pharaohs to make gold jewelry(hence the name Investment)some 5,000 years ago.熔模鑄造也稱為失蠟加工。這是最古老的制造工藝之一。大約在5,000年前的法老王時代，埃及人就用它制造黃金飾品(因此而得名投資)。
Intricate shapes can be made with high accuracy.In addition, metals that are hard to machine or fabricate are good candidates for this process.It can be used to make parts that cannot be produced by normal manufacturing techniques, such as turbine blades that have complex shapes, or airplane parts that have to withstand high temperatures.復雜的形狀能被高精度地制造。另外較難機加工或制作的金屬都能用此工藝。它還能用于生產一般制造技術無法生產的零件，例如有復雜形狀的渦輪葉片或必須耐得住高溫的飛機零件。
The mold is made by making a pattern using wax or some other material that can be melted away.This wax pattern is dipped in refractory slurry, which coats the wax pattern and forms a skin.This is dried and the process of dipping in the slurry and drying is repeated until a robust thickness is achieved.制作鑄型的型模采用石蠟或其它一些能被融化掉的材料做成。石蠟型模浸泡在耐熱漿里，讓它覆蓋型模并形成外殼，然后使其變干。重復這個浸泡、變干的過程直至獲得足夠的厚度。
After this, the entire pattern is placed in an oven and the wax is melted away.This leads to a mold that can be filled with the molten metal.Because the mold is formed around a one-piece pattern(which does not have to be pulled out from
the mold as in a traditional sand casting process), very intricate parts and undercuts can be made.完成后把整個型模放在烤箱里融化石蠟。這樣就做成了能填充熔化金屬的鑄型。由于這種鑄型是環繞整塊型模形成的(無需像傳統的砂型鑄造工藝那樣拔模)，能制作十分復雜的零件和浮雕。
The wax pattern itself is made by duplicating using a stereo lithography or similar model—which has been fabricated using a computer solid model master.石蠟型模本身能用立體制版或類似的模型復制—這可以采用計算機立體模型原版制作。
The materials used for the slurry are a mixture of plaster, a binder and powdered silica, a refractory, for low temperature melts.For higher temperature melts, sillimanite or alumina-silicate is used as a refractory, and silica is used as a binder.對較低熔化溫度而言，用于耐熱漿的材料是石膏作粘合劑和用粉末狀硅石作耐溫材料的混合物。對較高熔化溫度而言，則采用硅線石或氧化鋁硅酸鹽作耐溫材料、無水硅酸作粘合劑。
Depending on the fineness of the finish desired additional coatings of sillimanite and ethyl silicate may be applied.The mold thus produced can be used directly for light castings, or be reinforced by placing it in a larger container and reinforcing it more slurry.根據最后所需光潔度也可采用硅線石和乙烷基硅酸鹽。這樣生成的鑄模可直接用于薄壁鑄件或通過將其放在較大容器內用更多耐熱漿加強。
Just before the pour, the mold is pre-heated to about 1,000℃(1,832℉)to remove any residues of wax, harden the binder.The pour in the pre-heated mold also ensures that the mold will fill completely.在正要澆鑄之前，將型模預熱到約1,000℃(1,832℉)以去除剩余石蠟、硬化粘合劑。在預熱的型模中澆鑄也能保證型模完全充滿。
Pouring can be done using gravity, pressure or vacuum conditions.Attention must be paid to mold permeability when using pressure, to allow the air to escape as the pour is done.澆鑄可采用重力、壓力或真空條件來實現。當使用壓力時必須注意滲透性，以便在澆鑄的同時讓空氣逸出。Tolerances of 0.5% of length are routinely possible, and as low as 0.15% is possible for small dimensions.Castings can weigh from a few grams to 35kg(0.1oz to 80lb), although the normal size ranges from 200g to about 8kg(7oz to 15 lb).Normal minimum wall thicknesses are about 1mm to about 0.5mm(0.040~ 0.020 in.)for alloys that can be cast easily.一般公差可能為長度的0.5%，小尺寸可能低到0.15%。雖然通常尺寸的鑄件重量范圍為200g到約8kg(7oz到15lb)，但實際可從幾克到35kg(0.1oz to 80lb)。對容易鑄造的合金而言，通常壁厚約為1mm到0.5mm(0.040~ 0.020 in.)。
The types of materials that can be cast are aluminum alloys, bronzes, tool steels, stainless steels, stellite, hastelloys, and precious metals.Parts made with investment castings often do not require any further machining, because of the close tolerances that can be achieved.可以用于鑄造的材料類型有：鋁合金、青銅、工具鋼、不銹鋼、鎢鉻鈷合金、鎳基合金和貴金屬。采用熔模鑄造的零件常常不需要進一步加工，因為熔模鑄造能達到精密的公差。
? Centrifugal Casting 離心鑄造
Centrifugal casting(Fig.3.3)as a category includes centrifugal casting, semi-centrifugal casting and centrifuging.In centrifugal casting, a permanent mold is rotated about its axis at high speeds(300 to 3,000rpm)as the molten metal is poured.離心鑄造(圖3.3)作為一個種類包括了離心鑄造、半離心鑄造和離心法鑄造。離心鑄造中，永久性的型模在熔化金屬澆鑄時以較高速度(300到3,000rpm)繞其軸線旋轉。
The molten metal is centrifugally thrown towards the inside mold wall, where it solidifies after cooling.The casting is usually a fine grain casting with a very fine-grained outer diameter, which is resistant to atmospheric corrosion, a typical situation with pipes.The inside diameter has more impurities and inclusions, which can be machined away.受離心力作用熔化金屬被拋向型模的內壁，在那里冷卻后固化。這種鑄件通常為外徑處晶粒非常細小的細晶粒鑄件，能耐大氣腐蝕，典型的情況是管子。內徑處則有較多的雜質和內含物，但可用機加工去除。
Only cylindrical shapes can be produced with this process.Size limits are up to 3m(10feet)diameter and 15m(50 feet)length.Wall thickness can be 2.5mm to 125mm(0.1~5.0in.).The tolerances that can be held on the OD can be as good as 2.5mm(0.1in.)and on the ID can be 3.8mm(0.15in.).The surface finish ranges from 2.5mm to 12.5mm(0.1~0.5in.)rms(root-mean-square).只有圓柱形才能用此工藝生產。尺寸限制為直徑大到3m(10feet)、長度大到15m(50feet)。壁厚為2.5mm到125mm(0.1~5.0in.)。外徑公差保持在2.5mm(0.1in.)以內，內徑公差保持在3.8mm(0.15in.)以內。表面粗糙度的有效值(均方根)范圍為2.5mm到12.5mm(0.1~0.5in.)。
Typical materials that can be cast with this process are iron, steel, stainless steels, and alloys of aluminum, copper and nickel.Two materials can be cast by introducing a second material during the process.Typical parts made by this process are pipes, boilers, pressure vessels, flywheels, cylinder liners and other parts that are axis-symmetric.可用此工藝鑄造的典型材料有：鐵、鋼、不銹鋼以及鋁、銅和鎳的合金。通過在生產過程中加入第二種材料能進行兩種材料鑄造。采用這種工藝制造的典型零件有：管子、鍋爐、壓力容器、飛輪、汽缸襯墊和其它軸對稱零件。
Semi-centrifugal casting.The molds used can be permanent or expendable, can be stacked as necessary.The rotational speeds are lower than those used in centrifugal casting.半離心鑄造：型模可以是永久性的或是消耗性的，可根據需要疊加。它的旋轉速度比離心鑄造低。
The center axis of the part has inclusion defects as well as porosity and thus is suitable only for parts where this can be machined away.This process is used for making wheels, nozzles and similar parts where the axis of the part is removed by subsequent machining.零件的中心軸附近存在缺陷和孔隙，因此僅適用于能將這些機加工去除的零件。這種工藝被用于制造車輪、管嘴及類似的隨后可用機加工去除中心軸部分的零件。
Centrifuging.Centrifuging is used for forcing metal from a central axis of the equipment into individual mold cavities that are placed on the circumference.This provides a means of increasing the filling pressure within each mold and allows for reproduction of intricate details.This method is often used for the pouring of investment casting pattern.離心法鑄造：離心法鑄造用于迫使金屬從設備的中心軸進入分布在圓周上的單獨型腔。它為每個型腔提供了一種增加填充壓力方法并允許再現復雜細節。這種方法常用于澆鑄熔模鑄型。
Full-mold casting is a technique similar to investment casting, but instead of wax as the expendable material, polystyrene foam is used as the pattern.The foam pattern is coated with a refractory material.The pattern is encased in a one-piece sand mold.As the metal is poured, the foam vaporizes, and the metal takes its place.實型鑄造是與熔模鑄造類似的技術，但它用做型模的消耗材料是聚苯乙烯泡沫而不是石蠟。泡沫型模用難熔材料覆蓋。型模裝入整體砂模中。當金屬澆入時，泡沫材料蒸發，金屬取代其位置。
This can make complex shaped castings without any draft or flash.However, the pattern cost can be high due to the expendable nature of the pattern.Minimum wall thicknesses are 2.5mm, tolerances can be held to 0.3% on dimensions.Surface finish can be held from 2.5μm to 25μm(0.1μin.to 1.0μin.)rms(root-mean-square).它能制造沒有拔模斜度和縫脊的復雜形狀鑄件。然而由于型模的消耗特性，型模成本可能較高。最小壁厚為2.5mm，公差能保持在尺寸的0.3% 之內。表面粗糙度的有效值(均方根)能保持在2.5μm至25μm(0.1μin.至1.0μin.)之間。
Size limits are from 400g(1lb)to several tons.No draft allowance is required.Typical materials that can be cast with this process are aluminum, iron, steel, nickel alloys, copper alloys.Types of parts that can be made using these processes are pump housings, manifolds, and auto brake components.重量限制從400g(1lb)到數噸。無需留拔模余量。這種工藝所用的典型材料有：鋁、鐵、鋼、鎳合金、銅合金。可以采用這些工藝制造的零件類型有泵殼、復式接頭和自動剎車部件。
第四單元
? Introduction
引言
Forging is an important hot-forming process.It is used in producing components of all shapes and sizes, from quite small items to large units weighing several tons.鍛造是一種重要的熱成型工藝。它能用于生產各種形狀和尺寸、從很小到重量數噸的零件。
Forging is the process by which metal is heated and is shaped by plastic deformation by suitably applying compressive force.Usually the compressive force is in the form of hammer blows using a power hammer or a press, as shown in Fig.4.1.在鍛造過程中先將金屬加熱，然后施加合適的壓力使其塑性變形。通常壓力都是以由如圖4.1所示的動力錘或壓力機提供的錘擊形式出現。
Hand forging tools comprise variously shaped hammers.The base on which the work is supported during forging is the anvil.手工鍛造工具包括各種不同形狀的錘子。在鍛造中用于支撐工件的基礎是鐵砧。
For the semimechanized forging of small to medium-sized components, forging hammers powered by various means are employed.The feature common to all of them is that, like the hand forging hammer, they utilize the energy of a falling weight to develop the pressure needed for shaping the metal.對小到中等尺寸零件的半機械化鍛造而言，鍛錘可采用多種動力。就其一般特性而言，都象手工鍛錘一樣，它們均利用落重能量來產生金屬成型所需的壓力。
Larger components are forged by means of forging presses operated by steam or compressed air or by hydraulic or electric power.Largely automatic forging machines are used for the quantity production of engineering parts.鍛造大零件則要用到蒸汽、壓縮空氣、液力或電力驅動的鍛壓機。大型的自動化鍛機用于工程零件的批量生產。A distinction may be made between open-die forging, usually in the form of hammer forging, and closed-die forging.In hammer forging, the component is shaped by hammer blows aided by relatively simple tools.These may include open dies i.e., dies that do not completely enclose the metal to be shaped.錘鍛中常用的開式模鍛與閉式模鍛是有區別的。在錘鍛中零件通過錘擊輔之以相對簡單的工具成型。其中包括開式鍛模，就是不完全封閉被成型金屬的模具。
One of the basic operations of hammer forging is the elongation of a piece of metal by stretching with hammer blows, causing it to become thinner and longer.In hand forging the work-piece is usually turned 90°after each blow, in order to forge it thoroughly and prevent its lateral expansion.錘鍛的基本操作之一就是通過錘擊使金屬伸長，促成其變細變長。手工鍛造時一般在每次錘擊后都轉過90°以充分鍛打工件并防止橫向膨脹。
The opposite of elongation is upsetting, which produces compressive shortening.For example, the diameter of a bar can be increased by heating and hammering axially.與伸長相反的是鐓粗，即產生壓縮性縮短。例如，棒料的直徑可以通過加熱和軸向錘擊而增大。
More important is closed-die forging, very widely used for mass production in industry, in which the metal is shaped
by pressing between a pair of forging dies.The upper die is usually attached to the ram of a forging press or a forging hammer, while the lower die is stationary.更重要的是閉式模鍛，在工業上廣泛用于規模生產。閉式模鍛中金屬在一對鍛模之間擠壓成型。頂模通常放在鍛壓機的撞頭或鍛錘上，而底模則是固定的。
Together they form a closed die.Closed-die forging can produce components of greater complexity and accuracy, with a better surface finish than the more traditional methods not using closed dies.The dies are made of special heat-resistant and wear-resistant tool steels.兩者合在一起形成閉式鍛模。閉式模鍛能生產高度復雜和精確的零件，而且表面光潔度要比不用閉式鍛模的更傳統方法好。閉式鍛模采用特殊的耐熱、耐磨工具鋼制成。
A piece of hot metal sufficient to slightly overfill the die shape is placed in the bottom die, and the top die is forced against it, so that the metal takes the internal shape of the die.將一塊大小足以充填模腔并能稍有溢出的加熱金屬放入底模，并將頂模加壓合攏，這塊金屬便獲得該模腔的形狀。
Closed-die forging is used for the rapid production of large numbers of fairly small parts and also for very large components.For the latter, e.g., modern jet-aircraft components, giant hydraulically operated presses are used, which can develop forces of 50,000 tons and more.閉式模鍛用于相當小的零件大批量快速生產，也可用于很大的零件。對后者而言，例如現代噴氣飛機零件，使用能產生50,000噸以上壓力的巨型液力鍛壓機。
One valuable feature of forging is that it improves the strength of the metal by refining the structure and making it uniform;so for heavy forgings, such as marine propeller shafts, an immensely powerful hydraulic press squeezes the metal with a force sometimes as great as 10,000 tonnes.鍛造有價值的特性之一是它通過使金屬組織均勻而改善強度，因此對諸如船舶螺旋槳軸之類的重型鍛件，要用能達10,000噸壓力的龐大而有力的液壓機來擠壓金屬。
Although the hydraulic forging press is a more expensive piece of equipment than a drop-forge, it has advantages beside those of giving greater strength and more uniform structure to large components.On account of the high pressure and squeezing action, it operates with less noise and vibration than a drop-forge.雖然這種液壓鍛機比落錘鍛造要昂貴得多，但它除了能給予大零件較高的強度和更均勻的組織外還有其它優點。由于較高的壓力和擠壓作用，它比落錘鍛造噪聲及振動都小得多。
As ingots of steel weighing 30 tonnes or more are forged in this way, manual operation is impossible and it is essential that all the manipulation of the ingot is done mechanically.由于這種情況下被鍛鋼坯重量大于30噸，人工操作是不可能的，鋼坯的所有操作都必須是機械化的。Forging refines the grain structure and improves physical properties of the metal.With proper design, the grain flow
can be oriented in the direction of principal stresses encountered in actual use.鑄造細化金屬的晶粒組織、改善其物理性能。通過適當的設計，可以使晶粒流動方向與實際使用時的主應力方向一致。
As shown in Fig.4.2, grain flow is the direction of the pattern that the crystals take during plastic deformation.Physical properties(such as strength, ductility and toughness)are much better in a forging than in the base metal, which has crystals randomly oriented.如圖4.2所示，晶粒流動的方向就是在塑性變形期間結晶排列的方向。鍛件的物理性能(如強度、延展性和韌性)遠好于基礎金屬，因為基礎金屬的晶粒是無序排列的。
Forgings are consistent from piece to piece, without any of the porosity, voids, inclusions and other defects.Thus, finishing operations such as machining
do not expose voids, because there aren’t any.Also coating operations such as plating or painting are straightforward due to a good surface, which needs very little preparation.鍛件各部分是連貫一致的，沒有孔隙、空洞、雜質及其它缺陷。因此像機加工之類的精加工工序不會受空洞的影響，因為根本就不存在。另外由于鍛件良好的表面，像電鍍或油漆之類的涂裝工序就很簡單，幾乎不需要做準備工作。
Forgings yield parts that have high strength to weight ratio, thus are often used in the design of aircraft frame members.A forged metal can result in the following: 鍛造生產的零件具有較高的強度重量比，所以常被用在飛機結構零件的設計中。鍛造金屬可以導致下列結果：
? Increase length, decrease cross-section, called drawing out the metal.? Decrease length, increase cross-section, called upsetting the metal.? Change length, change cross-section, by squeezing in closed impression dies.This results in favorable grain flow for strong parts.●增加長度、減小橫截面，稱為延伸金屬。●減小長度、增加橫截面，稱為鐓粗金屬。●通過用封閉鍛模擠壓，改變長度和橫截面。這導致有利的晶粒流使零件堅固。
? Common Forging Processes 常用的鍛造工藝
The metal can be forged hot(above recrystallization temperatures)or cold.金屬既可熱鍛(高于再結晶溫度)也可冷鍛。
Open die forgings/Hand forgings.Open die forgings or hand forgings are made with repeated blows in an open die, where the operator manipulates the workpiece in the die.The finished product is a rough approximation of the die.This is
what a traditional blacksmith does, and is an old manufacturing process.開式模鍛/手工鍛：開式模鍛或手工鍛就是操作者操縱工件在開式鍛模中反復擊打。完成的產品是鍛模的粗糙近似物。這就是傳統鐵匠干的活，是較古老的制造工藝。
Impression die forgings/Precision forgings.Impression die forgings and precision forgings are further refinements of the blocker forgings.The finished part more closely resembles the die impression.壓模鍛/精密鍛：壓模鍛和精密鍛是雛形模鍛的進一步改進。完成的零件與模膛更相似。
Press forgings.Press forgings use a slow squeezing action of a press, to transfer a great amount of compressive force to the workpiece.Unlike an open-die forging where multiple blows transfer the compressive energy to the outside of the product, press forging transfers the force uniformly to the bulk of the material.壓鍛：壓鍛通過壓力機緩慢的擠壓動作將巨大的壓力傳遞給工件。不像開式模鍛那樣需要多次擊打把壓縮能量傳遞到零件外表面，壓鍛能將力均勻地傳遞給材料的主體。
This results in uniform material properties and is necessary for large weight forgings.Parts made with this process can be quite large as much as 125kg(260lb)and 3m(10 feet)long.這使材料性能一致，對大重量鍛件而言是十分必要的。采用此工藝生產的零件重量可達125kg(260lb)而長度可達3m(10 feet)。
Upset forgings.Upset forging increases cross-section by compressing the length, this is used in making heads on bolts and fasteners, valves and other similar parts.頂鍛：頂鍛通過壓縮長度增加橫截面，用于在螺栓等緊固件、柱塞及類似零件上制造頭部。
Roll forgings.In roll forging, a bar stock, round or flat is placed between die rollers which reduces the cross-section and increases the length to form parts such as axles, leaf springs etc.This is an essential form of draw forging.滾鍛：在滾鍛時，圓的或是扁平的棒料放在模輥之間縮小橫截面增加長度制成諸如輪軸、板簧之類的零件。這是軋鍛的基本形式。
Swaging.Swaging—a tube or rod is forced inside a die and the diameter is reduced as the cylindrical object is fed.The die hammers the diameter and causes the metal to flow inward causing the outer diameter of the tube or the rod to take the shape of the die.型鍛：型鍛—將圓管或圓棒強制壓入鍛模，隨著圓柱形物體的被壓入其直徑減小。鍛模錘擊橫斷面使金屬向內流動導致圓管或圓棒的外徑變為鍛模的形狀。
Net shape/Near-net shape forging.In net shape or near-net shape forging, forging results in wastage of material in the form of material flash and subsequent machining operations, as shown in Fig.4.3.This wastage can be as high as 70% for gear blanks, and even 90% in the case of aircraft structural parts.純型/近似純型鍛 ：采用純型鍛或近似純型鍛，產生材料損耗的主要形式是飛邊以及隨后的機加工，如圖4.3所示。齒輪毛坯材料損耗為70%，而飛機結構零件的材料損耗甚至達90%。
Net-shape and near-net-shape processes minimize the waste by making precision dies, producing parts with very little draft angle(less than 1°).These types of processes often eliminate or reduce machining.純型鍛和近似純型鍛工藝通過制作精密模具并生產鍛模斜角很小(小于1°)的零件能使材料損耗最小化。此類工藝通常可以省去或減少機加工。
The processes are quite expensive in terms of tooling and the capital expenditure required.Thus, these processes can be only justified for current processes that are very wasteful where the material savings will pay for the significant increase in tooling costs.從模具的角度而言這些工藝是相當昂貴的，需要資金投入。因此這些工藝只有對目前很浪費的生產過程，在材料節約足以補償模具成本的大量增加時才是合理的。
? Die Design Consideration 鍛模設計的考慮因素
? Parting surface should be along a single plane if possible, else following the contour of the part.The parting surface should be through the center of the part, not near the upper or lower edges.? 如果可能分模面應沿著單一平面，否則就順著零件輪廓方向。分模面應經過零件中心，而不要靠近上下邊緣。
If the parting line cannot be on a single plane, then it is good practice to use symmetry of the design to minimize the side thrust forces.Any point on the parting surface should be less than 75°from the principal parting plane.如果分模面不能在單一平面，利用設計的對稱性來減小側向推力不失為一種好方法。分模面上任意點與主分模面的夾角應小于75°。
? As in most forming processes, use of undercuts should be avoided as these will make the removal of the part difficult, if not impossible.? 如同大多數成型工藝，如果不是非用不可，盡量避免采用凹槽，因為凹槽會使零件難以取出。? Generous fillets and radius should be provided to aid in material flow during the forging process.Sharp corners are stress-risers in the forgings, as well as make the dies weak in service.? Ribs should not be high or narrow;this makes it difficult for the material to flow.? 應提供盡可能大的倒角和半徑以幫助材料在鍛造過程中流動。銳角會增加鍛件中的應力，同時在使用時削弱鍛模。
? 加勁肋不要過高、過窄，因為這會造成材料流動困難。? Tolerances
公差
? Dimension tolerances are usually positive and are approximately 0.3% of the dimension, rounded off to the next higher 0.5mm(0.020in.).? 尺寸公差通常為正，大約取為該尺寸的0.3%，并圓整到較大的0.5mm(0.020in.)。
? Die wear tolerances are lateral tolerances(parallel to the parting plane)and are roughly +0.2% for copper alloys to +0.5% for aluminum and steel.? 鍛模磨損公差為側向公差(平行于分模面)，對銅合金大約為+0.2%，對鋁和鋼大約為+0.5%。? Die closure tolerances are in the direction of opening and closing, and range from 1mm(0.040in.)for small forgings, die projection area＜150cm2(23in.2), to 6.25mm(0.25in.)for large forgings, die projection area＞6,500cm2(100in.2).? 鍛模的閉合公差處于開閉的方向上，范圍從對較小鍛件[其投影面積＜150cm2(23in.2)]取為1mm(0.040in.)，到較大鍛件[其投影面積＞6,500cm2(100in.2)]取為6.25mm(0.25in.)。
? Die match tolerances are to allow for shift in the upper die with respect to the lower die.? 鍛模的配合公差是為了允許上模能根據下模替換。
A proper lubricant is necessary for making good forgings.The lubricant is useful in preventing sticking of the workpiece to the die, and also acts as a thermal insulator to help reduce die wear.制造良好的鍛件必須有合適的滑潤劑。滑潤劑對防止工件粘住鍛模很有用，還可以作為絕熱體幫助減少鍛模磨損。
第五單元
Powder metallurgy(Fig.5.1)uses sintering process for making various parts out of metal powder.The metal powder is compacted by placing in a closed metal cavity(the die)under pressure.粉末冶金(圖5.1)采用燒結工藝將金屬粉末制成各種各樣的零件。金屬粉末放在封閉的金屬腔(模具)中在壓力下被壓實。
This compacted material is placed in an oven and sintered in a controlled atmosphere at high temperatures and the metal powders coalesce and form a solid.A Second pressing operation, repressing, can be done prior to sintering to improve the compaction and the material properties.被壓實的材料置于爐內燒結，在高溫下爐內環境可控，金屬粉末熔合形成固體。在燒結前可以進行二次擠壓作
業(再擠壓)以改善壓實狀態和材料性能。
Powder metallurgy is a highly developed method of manufacturing reliable ferrous and nonferrous parts.Made by mixing elemental or alloy powders and compacting the mixture in a die, the resultant shapes are then sintered or heated in a controlled atmosphere furnace.粉末冶金是一種高度發達的制造可靠鐵或非鐵零件的方法。通過混合元素或合金粉末并在模具中壓實混合物，再燒結或在環境可控爐內加熱制成最終形狀。
? Material
材料
The majority of the structural components produced by fixed die pressing are iron-based.The powders are elemental, pre-alloyed, or partially alloyed.大多數用固定模壓制的結構件都是鐵基的。粉末可以是單一元素、預先合金或部分合金。
Elemental powders, such as iron and copper, are easy to compress to relatively high densities, produce pressed compacts with adequate strength for handling during sintering, but do not produce very high strength sintered parts.諸如鐵、銅之類的單一元素粉末較容易被壓得相對密度較高、生產具備足夠強度的壓制物供燒結處理，但是無法制造出很高強度的燒結零件。
Pre-alloyed powders are harder, less
compressible and hence require higher pressing loads to produce high density compacts.However, they are capable of producing high strength sintered materials.預先合金粉末比較硬、不容易壓實，因此需要較高的擠壓力來產生高密度的壓制物。然而它們能生成高強度燒結材料。
Pre-alloying is also used when the production of a homogeneous material from elemental powders requires very high temperatures and long sintering times.The best examples are the stainless steels, whose chromium and nickel contents have to be pre-alloyed to allow economic production by powder metallurgy.如果用單一元素粉末生產均勻材料需要很高溫度和較長燒結時間，也可用預先合金。最好的例子是不銹鋼，因含有鉻和鎳成分，所以粉末冶金必須用預先合金才經濟。
Partially alloyed powders are a compromise approach.Elemental powders, e.g.iron with 2wt.% copper, are mixed to produce an homogeneous blend which is then partially sintered to attach the copper particles to the iron particles without producing a fully diffused powder but retaining the powder form.部分合金粉末是一種折衷的方法。單一元素粉末，例如鐵與2%的銅(重量百分比)混合均勻，經部分燒結后銅微粒粘附到鐵微粒上而沒有產生充分擴散的粉末卻保留了粉末的形態。
In this way the compressibilities of the separate powders in the blend are maintained and the blend will not segregate during transportation and use.用這種方法混合物中單獨粉末的可壓縮性得以維持，在運送和使用期間結合將不會分離。
A similar technique is to “glue” the small percentage of alloying element onto the iron powder.This “glueing”
technique is successfully used to introduce carbon into the blends, a technique which prevents carbon segregation and dusting, producing so-called “clean” powders.另一種類似的技術是把小百分比的合金元素“粘合”到鐵微粒上。這種“粘合”技術已成功用于將碳引入結合物，一種防止碳分離并起塵的技術，生產所謂的“清潔”粉末。
? Powder Consolidation 粉末合成
Components or articles are produced by forming a mass of powder into a shape, then consolidating to form inter-particle metallurgical bonds.通過將大量的粉末放入模具成型為零件或物品，然后合成為內有微粒的冶金結合物。
An elevated temperature diffusion process referred to as sintering, sometimes assisted by external pressure, accomplishes this.The material is never fully molten, although there might be a small volume fraction of liquid present during the sintering process.Sintering can be regarded as welding the particles present in the initial useful shape.提升溫度擴散工藝被稱為燒結，有時還輔之以外界的壓力來達到目的。雖然在燒結過程中可能會有少量液態出現，但材料決不是全熔化。燒結可以被看作是把微粒焊接成初始的有用形狀。
As a general rule both mechanical and physical properties improve with increasing density.Therefore the method selected for the fabrication of a component by powder metallurgy will depend on the level of performance required from the part.Many components are adequate when produced at 85~90% of theoretical full density whist others require full density for satisfactory performance.作為普遍規律，隨著密度的增加機械和物理性能均改善。因此選擇何種粉末冶金方法來制作零件取決于其所需的性能級別。許多零件只需理論全密度的85~90%而其它的則需全密度才能滿足要求。
Some components, in particular bush type bearings often made from copper and its alloys, are produced with significant and controlled levels of porosity, the porosity being subsequently filled with a lubricant.Fortunately there is a wide choice of consolidation techniques available.有些零件，尤其是襯套式軸承常用銅及其合金制作，控制多孔性程度的意義重大，因為這些孔隨后要填充潤滑劑。
還好有多種合成技術可供選擇。Cold Uniaxial Pressing Elemental metal, or an atomized pre-alloyed powder is mixed with a lubricant, typically lithium stearate(0.75 wt.%), and pressed at pressures of say, 600MPa(87,000lb/in.2)in metal dies.冷單向擠壓
單一元素金屬，或極小顆粒的預先合金粉末與潤滑劑(一般是鋰硬脂酸鹽，重量百分比0.75%)混合，然后在金屬模具中施加壓力[比如600MPa(87,000lb/in.2)]擠壓。
Cold compaction ensures that the as-compacted, or “green”, component is dimensionally very accurate, as it is moulded precisely to the size and shape of the die.冷擠壓能保證被壓制或“未加工”的零件尺寸十分精確，因為它被精確地按模具的尺寸和形狀成型。One disadvantage of this technique is the differences in pressed density that can occur in different parts of the component due to particle/particle and die wall/particle frictional effects.Typical as-pressed densities for soft iron components would be 7.0g/cc, i.e.about 90% of theoretical density.這種技術的缺點之一是由于微粒/微粒和模壁/微粒間的摩擦效應，零件不同部位的壓實密度存在差異。典型的軟鐵零件壓制密度為7.0g/cc，即大約是理論密度的90%。
Compaction pressure rises significantly if higher as-pressed densities are required, and this practice becomes uneconomic due to higher costs for the larger presses and stronger tools to withstand the higher pressures.如果需要較高的壓實密度則壓實壓力要顯著提高，因為大型壓力機成本較高并且在較高壓力下模具強度要更高這樣就不合算。
Cold Isostatic Pressing Metal powders are contained in an enclosure e.g.a rubber membrane or a metallic can that is subjected to isostatic, which is uniform in all directions, external pressure.As the pressure is isostatic the as-pressed component is of uniform density.冷均衡擠壓
金屬粉末裝入均衡受壓的橡膠膜或金屬罐內，其所受外壓力在各個方向都是均勻的。由于壓力是均衡的，所以壓制零件密度是均勻的。
Irregularly shaped powder particles must be used to provide adequate green strength in the as-pressed component.This will then be sintered in a suitable atmosphere to yield the required product.必須采用不規則形狀粉末微粒為壓制零件提供足夠的未加工強度。然后放入合適的環境中燒結成所需產品。Normally this technique is only used for semi-fabricated products such as bars, billets, sheet, and roughly shaped components, all of which require considerable secondary operations to produce the final, accurately dimensioned component.通常這種技術只用于制作諸如棒料、坯段、薄板及粗糙成型零件之類的半成品，所有這些都需要大量進一步加工才能生產出最終尺寸精確的零件。
Again, at economical working pressures, products are not fully dense and usually need additional working such as hot extrusion, hot rolling or forging to fully density the material.此外使用經濟工作壓力的產品不是充分致密的，一般需要增加諸如熱擠壓、熱軋或鍛之類的額外工序來使材料達到全密度。
Sintering
Sintering is the process whereby powder compacts are heated so that adjacent particles fuse together, thus resulting in a solid article with improved mechanical strength compared to the powder compact.燒結
燒結就是通過把粉末壓制物加熱使鄰近的微粒熔合在一起的工藝，它能生成比粉末壓制物機械強度更好的固體物。
This “fusing” of particles results in an increase in the density of the part and hence the process is sometimes called densification.There are some processes such as hot isostatic pressing which combine the compaction and sintering processes into a single step.微粒的“熔合”導致零件密度增加，因此該工藝有時被稱為致密化。還有一些工藝如熱均衡擠壓，將壓實和燒結工藝合并為單一步驟。
After compaction the components pass through a sintering furnace.This typically has two heating zones, the first removes the lubricant, and the second higher temperature zone allows diffusion and bonding between powder particles.零件壓實后通過燒結爐。一般有兩個加熱區，第一個去除潤滑劑，第二個溫度更高的區域讓粉末微粒之間擴散并結合。
A range of atmospheres, including vacuum, are used to sinter different materials depending on their chemical compositions.As an example, precise atmosphere control allows iron/carbon materials to be produced with specific carbon compositions and mechanical properties.根據不同材料的化學成分，燒結的環境包括真空狀態也各不相同。例如精確的環境控制可使鐵/碳材料生成特殊碳化物和機械性能。
The density of the component can also change during sintering, depending on the materials and the sintering temperature.These dimensional changes can be controlled by an understanding and control of the pressing and sintering parameters, 根據材料和燒結溫度的不同，零件的密度在燒結過程中也會改變。因為尺寸的變化可以通過了解并調節擠壓及燒結參數進行控制，and components can be produced with dimensions that need little or no rectification to meet the dimensional tolerances.Note that in many cases all of the powder used is present in the finished product, scrap losses will only occur when secondary machining operations are necessary.所以零件尺寸幾乎無需校正就能滿足尺寸公差。可以看到在很多情況下所有使用的粉末都包含在制成品中，廢料損失僅產生于需要輔助機加工時。
Hot Isostatic Pressing Powders are usually encapsulated in a metallic container but sometimes in glass.The container is evacuated, the powder out-gassed to avoid contamination of the materials by any residual gas during the consolidation stage and
sealed-off.熱均衡擠壓
粉末通常封裝在金屬容器內有時也裝在玻璃容器內。把容器抽真空，粉末抽氣是為了防止材料在合成階段和密封時被殘留氣體污染。
It is then heated and subjected to isostatic pressure sufficient to plastically deform both the container and the powder.再加熱并施加均衡壓力足以使容器和粉末都塑性變形。
The rate of densification of the powder depends upon the yield strength of the powder at the temperatures and pressures chosen.At moderate temperature the yield strength of the powder can still be high and require high pressure to produce densification in an economic time.粉末致密率取決于該粉末在選定溫度和壓力下的屈服強度。中等溫度下粉末的屈服強度仍然較高，因此需要較高壓力使其在經濟時間內致密化。
Typical values might be 1120℃ and 100MPa for ferrous alloys.By pressing at very much higher temperatures lower pressures are required as the yield strength of the material is lower.Using a glass enclosure atmospheric pressure(15psi)is used to consolidate bars and larger billets.對鐵合金典型的數值為1120℃和100MPa。由于很高溫度下材料的屈服強度較低，因此只需較低壓力就能擠壓。采用玻璃容器時可用大氣壓力(15psi)合成棒料和較大坯段。
The technique requires considerable financial investment as the pressure vessel has to withstand the internal gas pressure and allow the powder to be heated to high temperatures.因為壓力容器必須經受住內氣壓并允許粉末加熱到較高溫度，所以這種技術需要相當可觀的資金投入。As with cold isostatic pressing only semi-finished products are produced, either for subsequent working to smaller sizes, or for machining to finished dimensions.此工藝與采用冷均衡擠壓一樣只能生產半成品，可以通過后續加工至較小尺寸，也能用機加工到最終尺寸。Hot Forging(Powder Forging)Cold pressed and sintered components have the great advantage of being close to final shape(near-net shape), but are not fully dense.Where densification is essential to provide adequate mechanical properties, the technique of hot forging, or powder forging, can be used.熱鍛(粉末鍛造)冷擠壓和燒結零件主要優點是接近最終形狀(近似純形)，但不是充分致密的。當為了提供足夠的機械性能而致密化是必須時，可以采用熱鍛或粉末鍛造技術。
In powder forging an as-pressed component is usually heated to a forging temperature significantly below the usual sintering temperature of the material and then forged in a closed die.This produces a fully dense component with the shape of the forging die and appropriate mechanical properties.在粉末鍛造中，壓制零件一般加熱到遠低于該材料通常燒結溫度的鍛造溫度，然后在閉模中鍛造。這能生產具有鍛模形狀和合適機械性能的充分致密零件。
Powder forged parts generally are not as close to final size or shape as cold pressed and sintered parts.These results from the allowances made for thermal expansion effects and the need for draft angles on the forging tools.Further, minimal machining is required but when all things are considered this route is often very cost-effective.粉末鍛造零件通常不像冷擠壓和燒結零件那樣接近最終尺寸或形狀。這是由于為熱膨脹效應而設置允差以及在鍛模上需要拔模斜角所致。此外還需少量機加工，但全面考慮這種方法通常還是很劃算的。
Metal Injection Moulding(MIM)Injection moulding is very widely used to produce precisely shaped plastic components in complex dies.As injection pressures are low it is possible to manufacture complex components, even some with internal screw threads, by the use of side cores and split tools.金屬注塑成型(MIM)注塑成型被很廣泛地用于在復雜模具中生產形狀精確的塑料零件。注塑壓力較低使得制作復雜零件成為可能，通過采用側面型芯和分離工具甚至可以帶有內螺紋。
By mixing fine, typically less than 20 μm diameter, spherical metal powders with thermoplastic binders, metal filled plastic components can be produced with many of the features available in injection moulded plastics.After injection moulding, the plastic binder material is removed to leave a metal skeleton which is then sintered at high temperature.將細小(直徑一般小于20μm)球形金屬粉末與熱塑性粘合劑混合，能生產具有多數注塑成型塑料特征的金屬充滿塑料零件。注塑成型后，去除塑料粘合材料剩下金屬骨架，然后在高溫下燒結。
Dimensional control can be exercised on the as-sintered component as the injected density is sensibly uniform so shrinkage on sintering is also uniform.燒結零件可以實現尺寸控制，因為注塑密度明顯均勻，所以燒結收縮也是均勻的。
Shrinkage can be large, due to both the fine particle size of the powders and the substantial proportion of polymer binder used.由于所用粉末細小微粒的尺寸和聚合物粘合劑的真實比例，收縮可以比較大。
? Features
特征
? For high tolerance parts, a sintering part is put back into a die and repressed.In genera this makes the part more accurate with a better surface finish.? 對較大公差的零件，燒結后可放回模具重新擠壓。一般而言這會使零件更精確同時具有更好的表面光潔度。
? A part has many voids that can be impregnated.One method is to use an oil bath.Another method uses vacuum first, then impregnation.? 零件有許多可供填充的空間。一種方法是采用油浴。另一種方法是先抽真空然后再充滿。? A part surface can be infiltrated with a low melting point metal to increase density, strength, hardness, ductility and impact resistance.? Plating, heat treating and machining operations can also be used.? 零件表面能被低熔點金屬滲透以增大密度、強度、硬度、延展性和抗沖擊能力。? 仍然可以進行電鍍、熱處理和機加工作業。? Advantages
優點
? Good tolerances and surface finish ? Highly complex shapes made quickly ? Can produce porous parts and hard to manufacture materials(e.g.cemented oxides)? 良好的公差和表面光潔度 ? 高度復雜的形狀能快速制作
? 能制作多孔零件和難以加工材料(如粘結氧化物)? Pores in the metal can be filled with other materials/metals ? Surfaces can have high wear resistance ? Porosity can be controlled ? Low waste ? Automation is easy ? 金屬中的氣孔可用其它材料/金屬填充 ? 表面能具有較高的耐磨性 ? 孔隙率可以控制 ? 較低損耗 ? 容易自動化
? Physical properties can be controlled ? Variation from part to part is low ? Hard to machine metals can be used easily ? No molten metals ? 物理性能可以控制 ? 零件之間的變化較小
? 難以機加工的金屬能被容易使用 ? 無需熔化金屬
? No need for many/any finishing operations
? Permits high volume production of complex shapes ? Allows non-traditional alloy combinations ? Good control of final density ? 不需要很多/任何修整作業 ? 允許加工復雜形狀的大體積產品 ? 允許非傳統合金結合 ? 對最終密度能很好地控制 ? Disadvantages
缺點
? Metal powders deteriorate quickly when stored improperly ? Fixed and setup costs are high ? Part size is limited by the press and compression of the powder used ? 如果存放不當金屬粉末質量很快降低 ? 安裝和調整的成本較高
? 零件尺寸受壓力機和所用粉末壓縮的限制
? Sharp corners and varying thickness can be hard to produce ? Non-moldable features are impossible to produce ? 銳角和變厚度較難加工 ? 不適合模壓的東西不可能生產
第六單元
Injection molding(Fig.6.1)is the predominant process for fabrication of thermoplastics into finished forms, and is increasingly being used for thermosetting plastics, fiber-filled composites, and elastomers.注塑成型(圖6.1)是將熱塑性塑料制成最終形狀的主要工藝，并且越來越多地用于熱硬化性塑料、纖維填充合成物和人造橡膠。
It is the process of choice for tremendous variety of parts ranging in weight from 5g to 85kg.It is estimated that 25% of all thermoplastics are injection molded.它是重量范圍為5g到85kg極大一類零件可選用的工藝。估計所有熱塑性塑料中有25%是采用注塑成型的。If newer modifications, such as reaction injection molding, and the greatly increased rate of adoption of plastics as substitutes for metals are considered, it is likely that the worldwide industrial importance of injection molding will continue to increase.如果考慮到新近的改進(例如反作用注塑成型)和采用塑料替代金屬的高增長率，注塑成型在世界范圍的工業重
要性很可能將繼續增加。
Currently, probably close to half of all major processing units is injection molding machines.In 1988, a dollar sale of new injection molding machinery in the U.S.was approximately 65% of total major polymer machinery sales volume;this included 4,600 injection molding units.當前，大概所有主要處理設備的近一半是注塑成型機。1988年，美國新的注塑成型機械銷售約占全部主要聚合物機械銷售量的65%，其中包括4,600臺注塑成型設備。
The machines and their products are ubiquitous and are synonymous with plastics for many people.這類機械和它們的產品普遍存在，對許多人來說與塑料是同義的。
A reciprocating screw injection molding machine combines the functions of an extruder and a compressive molding press.往復螺旋注射成型機把壓出機和成型壓力機的功能結合起來。
It takes solid granules of thermoplastic resin, melts and pressurizes them in the extruder section, forces the melt at high velocity and pressure through carefully designed flow channels into a cooled mold, then ejects the finished part(s), and automatically recycles.把熱塑性塑料樹脂的固體顆粒在壓出部分融化并增壓，迫使其高速融化并通過仔細設計的流動通道進入冷卻模具，噴射成最終零件，然后自動再循環。
This machine is a descendant of the plunger type “stuffing machine” patented by the Hyatt brothers in 1872 to mold celluloid.In 1878, the Hyatts developed the first multicavity mold, but it was not until 1938 that Quillery(France)patented a machine incorporating a screw to plasticize the elastomer being molded.這種機械是1872年Hyatt兄弟獲得專利權的融化賽璐珞的活塞型“填充機”的派生物。1878年Hyatt兄弟開發了第一個多槽模具，但直到1938年Quillery(法國)才發明了用螺旋增塑人造橡膠并使其成型的一體化機械。
In 1956, Ankerwerk Nuremberg commercialized the modern reciprocating screw injection molding machine for thermoplastics.Today, over 50 machine manufacturers are listed in Modern Plastics Encyclopedia, offering machines to the U.S.market ranging from 2 to 6,000 tons clamping capacity.1956年，Ankerwerk Nuremberg使用于熱塑性塑料的現代往復螺旋注塑成型機商業化。今天，已有超過50家制造商列入現代塑料制品百科全書，能為美國市場提供壓制能力從2到6,000噸的機械。
(A machine with a 10,000-ton capacity has been built to mold 264-gallon HDPE trash containers.)A host of suppliers of auxiliary equipment, molds, instruments, and controls service this major segment of the polymer industry.(一臺能力為10,000噸用于成型264加侖高密度聚乙烯垃圾箱的機械也已制成)。許多輔助設備、模具、儀器和控制系統供應商在為聚合物工業的這一主要部分服務。
Injection molding is particularly worthy of intensive study because it combines many areas of interest extrusion, mold design, rheology, sophisticated hydraulic and electronic controls, robotic accessories, design of complex products, and, of
course, the integration of materials science and process engineering.注塑成型對深入研究很有價值，因為它結合了許多重要領域，如擠壓、模具設計、流變學、完備的液壓和電子控制、機器人配件、復雜產品的設計，當然還有材料科學與加工工程的綜合。
The objectives of injection molding engineers are simple enough: to obtain minimum cycle time with minimum scrap, to attain specified product performance with assurance, to minimize production costs due to downtime or any other reasons, and to steadily increase in expertise and competitiveness.注塑成型工程師的目標很簡單：在最少廢料的情況下取得最小循環時間，在有保證的情況下獲得指定產品性能，將由停工或其它原因產生的生產成本最小化，還有穩定地增加專門知識和競爭力。
Profit margins for custom injection molders are said to be generally skimpy;an established way to improve profits is to be selected for more demanding, higher margin jobs that demand the highest level of efficiency and competence.傳統的注塑成型機利潤盈余據說一般是不足的；為了更多需求及更高盈余工作需要選擇一種改善利潤的確定方法，它要求最高水平的效率和能力。
This text will concentrate on the reciprocating screw machine for thermoplastics, which has largely replaced the older reciprocating plunger types except for very small-capacity machines.本文將集中論述熱塑性塑料用的往復螺旋機，除了小容量機械外它已在很大程度上取代了較老的往復活塞式機械。
? Injection Molding Materials 注塑成型材料
It is not possible to injection-mold all polymers.Some polymers like PTFE(Poly-tetra-fluoro-ethylene), cannot be made to flow freely enough to make them suitable for injection molding.要注塑成型所有聚合物是不可能的。像聚四氟乙烯之類的聚合物就不能自由流動得足以適合注塑成型。Other polymers, such as a mixture of resin and glass fiber in woven or mat form, are unsuitable by their physical nature for use in the process.In general, polymers which are capable of being brought to a state of fluidity can be injection-molded.其它聚合物，例如樹脂和編織的或墊子形的玻璃纖維的混合物，由于它們的物理性質不適合使用此工藝。一般而言，能進入流動狀態的聚合物都可以注塑成型。
The vast majority of injection molding is applied to thermoplastic polymers.This class of materials consists of polymers which always remain capable of being softened by heat and of hardening on cooling, even after repeated cycling.注塑成型的絕大多數都用于熱塑性聚合物。這類材料由具有加熱軟化、冷卻硬化甚至可重復循環能力的聚合物組成。
This is because the long-chain molecules of the material always remain as separate entities and do not form chemical bonds to one another.An analogy car, be made to a block of ice that can be softened(i.e.turned back to liquid), poured
into any shape cavity, and then cooled to become a solid again.這是由于這類材料的長鏈分子總是保持分離的實體并不相互形成化學連結。一輛由冰塊制成的模擬汽車，可以融化(即轉化為液態)，倒入任何形狀的空腔，然后冷卻重新變成固體。
This property differentiates thermoplastic materials from thermosetting ones.In the latter type of polymer, chemical bonds are formed between the separate molecule chains during processing.In this case the chemical bonding referred to as cross linking is the hardening mechanism.這個特性將熱塑性材料與熱硬化性材料區分開。后者在加工過程中分離的分子鏈之間形成化學連結。在此情況下作為交聯的化學連結是硬化機制。
In general, most of the thermoplastic materials offer high impact strength, corrosion resistance, and easy processing with good flow characteristics for molding complex designs.Thermoplastics are generally divided into two classes: namely crystalline and amorphous.一般而言，大多數熱塑性材料具有較高的抗沖擊強度、耐腐蝕性以及良好流動性使其容易加工而適于復雜成型設計。熱塑性塑料通常分為兩類：即結晶質的和非結晶質的。
Crystalline polymers have an ordered molecular arrangement, with a sharp melting point.Due to the ordered arrangement at molecules, the crystalline polymers reflect most incidents light and generally appear opaque.結晶質聚合物具有規則的分子排列及明顯的熔點。由于規則的分子排列，結晶質聚合物能反射大多數特定光線并一般表現為不透明的。
They also undergo a high shrinkage or reduction in volume during solidification.Crystalline polymers usually are more resistant to organic solvents and have good fatigue and wear-resistant properties.Crystalline polymers also generally are denser and have better mechanical properties than amorphous polymers.它們在固化過程中收縮較大或體積減少較多。結晶質聚合物通常多能抵御有機溶劑并具有良好的抗疲勞和磨損特性。結晶質聚合物通常也比非結晶質聚合物更致密并且具有更好的機械性能。
The main exception to this rule is polycarbonate, which is the amorphous polymer of choice for high quality transparent moldings, and has excellent mechanical properties.其中主要例外是聚碳酸酯，它是可選用做高質量透明注塑件的非結晶質聚合物，并具有卓越的機械性能。The mechanical properties of thermoplastics, while substantially lower than those of metals, can be enhanced for some applications through the addition of glass fiber reinforcement.This takes the form of short-chopped fibers, a few millimeters in length, which are randomly mixed with the thermoplastic resin.就本質而言，熱塑性塑料的機械性能低于金屬，但可以通過加入玻璃纖維強化予以增強來適應某些運用。常用幾毫米長的短碎纖維隨機地與熱塑性樹脂混合。
The fibers can occupy up to one third of the material volume to considerably improve the material strength and stiffness.The negative effect of this reinforcement is usually a decrease in impact strength and an increase in abrasiveness.纖維可占材料體積的三分之一以極大改善材料的強度和硬度。這種加強的負作用通常是抗沖擊強度降低及磨損性增加。
The latter also has an effect on processing since the life of the mold cavity is typically reduced from about 1,000,000 parts for plain resin parts to about 300,000 for glass-filled parts.后者對加工過程也有影響，因為模具腔的壽命從典型的普通樹脂零件大約1,000,000件減少到玻璃纖維填充樹脂零件的約300,000件。
Perhaps the main weakness of injection-molded parts is the relatively low service temperatures to which they can be subjected.Thermoplastic components can only rarely be operated continuously above 250℃, with an absolute upper service temperature of about 400℃.注塑成型零件的主要缺點或許是它們能承受的工作溫度相對較低。熱塑性塑料零件只有很少能連續運行在250℃以上，其絕對最高工作溫度約為400℃。
The temperature at which a thermoplastic can be operated under load can be defined qualitatively by the heat deflection temperature.This is the temperature at which a simply supported beam specimen of the material, with a centrally applied load, reaches a predefined deflection.熱塑性塑料帶載運行溫度可從質量上定義為熱偏差溫度。這是中心承載的該材料簡支梁達到預定偏差的溫度。The temperature value obviously depends upon the conditions of the test and the allowed deflection and for this reason, the test values are only really useful for comparing different polymers.其溫度值明顯取決于試驗條件和允許偏差，因此對比較不同的聚合物而言只有試驗數據是真正有用的。
? Cycle of Operation 作業循環
The reciprocating screw injection molding machine is considered as consisting of two halves: a fixed injection side, and a movable clamp side.往復螺旋注塑成型機被認為由兩部分組成：一個固定注塑端和一個活動夾具端。
The injection side contains the extruder that receives solid resin in pellet or granular form and converts it into a viscous liquid or melt that can be forced through the connecting nozzle, spine, and runners to the gates that lead into the mold cavities.注塑端包含壓出機，它接受小球或粒狀的固體樹脂，然后將其轉化為粘性液體或稱為融化，再強迫其通過連接噴嘴、中心和澆道到閘道進入模具腔。
The mold is tightly clamped against injection pressure and is cooled well below the melt temperature of the thermoplastic.When the parts in the cavities have cooled sufficiently the mold halves are opened at the mold parting plane and the parts ejected by a knockout system drop into a receiving bin below.模具被緊緊地夾住以抵抗注塑壓力，并在熱塑性塑料的融化溫度以下很好地冷卻。當模腔內的零件充分冷卻，剖分模在模具分模面處打開，推出系統將零件推出落入下面的接收容器內。
This summarizes the overall cycle, but leaves out much vital detail that is necessary for understanding the process.However, with this introduction, it is possible to understand the advantages and disadvantages of the process.這概述了整個循環，但省略了許多對理解此工藝所必需的很重要細節。然而通過本介紹，了解這種工藝的優缺點仍是可能的。
? Effects of Process Variables on Orientation
加工變量對方向性的影響
In injection molding, any variation in processing that keeps the molding resin hot throughout filling allows increased relaxation and, therefore, decreased orientation.Some of the steps that can be taken to reduce orientation are as follows.在注塑成型時，整個填料過程始終保持成型樹脂高溫的任何加工變化都會增加松弛作用而減少方向性。下面是可以用于減少方向性的若干措施。
? Faster injection(up to a point): less cooling during filling, hence a thinner initial frozen layer, lower viscosity due to shear thinning;better flow to corners;and less
crystallinity all favor lower subsurface orientation.The primary effect is that the gate will freeze more quickly.At that point, orientation stops and relaxation starts.? 較快注塑(到點)：在填料過程中冷卻較少，因此初始固化層較薄，由于剪應變稀少而粘性較低；能較好地流到角落；結晶度較小；所有這些促成表面下的方向性也較低。主要效果是閘道將較快固化。這樣使得方向性停止產生而松弛作用開始增加。
? Higher melt and mold temperatures: lower melt viscosity, easier filling, and greater relaxation favor reduced orientation.? Reduced packing time and pressure: overpacking inhibits relaxation processes.? 較高的融化和成型溫度：融化粘性較低，更容易填充，較大松弛作用促成方向性減少。? 減少擠壓時間和壓力：過度擠壓會抑制松弛過程。
? Reduced gate size: larger gates take longer to freeze off and permit increased orientation.? 減小閘道尺寸：閘道越大則固化時間越長并會使方向性增加。
Excessively high injection speed can cause high surface orientation and increase susceptibility to stress cracking.For example, moldings that are to be electroplated, and will be subject to acid solutions during plating, must be made using very slow injection speeds to minimize surface orientation.過高的注塑速度會引起較高的表面方向性及增加應力破裂的敏感性。例如，要電鍍的注塑件在電鍍時會經受酸溶液，必須采用很低的注塑速度制造以使表面方向性最小化。
On the other hand, the transverse motion component of the melt front in most moldings can cause transverse subsurface orientation superimposed on the primary orientation, giving a desirable biaxial orientation effect.另一方面，大多數注塑件的融化前部橫向運動部分能導致在主要方向性上有層理的表面下橫向方向性，產生需要的雙軸方向性效應。
Orientation can be seriously increased by obstructions to flow during filling of the cavity.Flow around an obstruction causes a decrease in melt front speed and leads to high local viscosity and reduced relaxation.This is also likely to occur near the end of the filling phase if gating is inadequate.在填充模腔時流動受到阻礙會極大地增加方向性。圍繞障礙物流動使融化前部的速度下降并產生較高的局部粘性而減少松弛作用。如果閘道不適當，這也很可能發生在接近填充結束階段。
The molder must recognize the dangers of excessive fill speed, insufficient injection pressure, excessive melt temperature, and inadequate packing.These dangers are weighed against the opposing effects on orientation discussed above.注塑工必須認識過快填充速度、不足注塑壓力、過高融化溫度和不充分擠壓的危害性。這些危害性要與上述方向性的反向效應相權衡。
Thicker parts delay cooling and increase relaxation time and tend to result in lower orientation.Thicker parts also tend to warp less.Therefore, a minimum wall thickness can be established by experience for various shapes, materials, and process combinations.較厚零件會延遲冷卻并且增加松弛時間，趨向于導致較低的方向性。較厚零件也有助于減少翹曲。因此，對各種形狀、材料和工藝組合能通過經驗來確定最小壁厚。
Lower molecular weight and broader molecular weight distribution in thermoplastics favor lower orientation and reduced internal stress in moldings.在熱塑性塑料中較小的分子量以及較寬泛的分子量分布促成方向性減少同時降低注塑件中的內應力。The skin thickness ratio is affected by process variables in the same way as one would predict for the orientation;that is, it decreases as the melt or mold temperatures and cavity pressure increases.Tensile strength and stiffness increase as skin thickness ratio increases.Microscopic examination thus provides another way of studying the process efficiently.外殼厚度比受加工變量影響的方式與方向性預測一樣；也就是它能隨融化或成型溫度及模腔壓力的增加而減少。拉伸強度和硬度隨外殼厚度比增加而增加。因而顯微鏡檢查提供了有效研究該工藝的另一方法。
? Advantages
優點
1.High production rates.For example, a CD disk can be produced with a 10~12s cycle in high melt flow index PC.1.高生產率：例如，一張CD盤在高融體流動指數生產控制中只需10~12s一個循環就能生產出來。2.Relatively low labor content.One operator can frequently take care of two or more machines, particularly the moldings are unloaded automatically onto conveyors.2.相對較少的工作內容：一個操作者經常可以照看兩臺以上機械，尤其是當成品能自動卸到輸送機上時。3.Parts require little or no finishing.For example, flash can be minimized and molds can be arranged to automatically
separate runners and gates from the part itself.4.Very complex shapes can be formed.Advances in mold tooling are largely responsible.3.零件幾乎不需要修整：例如，飛邊可以最小化并且模具能被設計成自動將澆道和閘道從零件本身分離。4.非常復雜的形狀也能成型：模具的進步很大程度上是可靠的。
5.Flexibility of design(finishes, colors, inserts, materials).More than one material can be molded through co-injection.Foam core materials with solid skins are efficiently produced.Thermosetting plastics and fiber-reinforced shapes are injection molded.5.設計的靈活性(光潔度、顏色、插入物、材料)：通過復合注塑可以成型多于一種材料。可以高效地生產帶有固體外殼的泡沫型芯材料。熱硬化性塑料和纖維加強形狀都可以注塑成型。
6.Minimum scrap loss.Runners, gates, and scrap can usually be reground.Recycled thermoplastics can be injection molded.6.廢料損失最小化：澆道、閘道和廢料通常可以重新研磨。循環熱塑性塑料可以注塑成型。
7.Close tolerances are obtainable.Modern microprocessor controls, fitted to precision molds, and elaborate hydraulics, facilitate tolerances in the 0.1% range on dimensions and weights(but not without a high level of operational skills in constant attendance).7.能得到接近的公差：現代微處理器控制、合適的精密模具和精心制作的液壓設備使得尺寸和重量的公差保持在0.1% 的范圍內(但不是沒有在持續照看時的高水平操作技能)。
8.Makes best use of the unique attributes of polymers, such as flow ability, light weight, transparency, and corrosion resistance.This is evident from the number and variety of molded plastic products in everyday use.8.充分利用聚合物諸如流動能力、重量輕、透明和耐腐蝕等獨特屬性：從日常使用成型塑料產品的數量和種類就能明顯看到。
? Disadvantages and Problems 缺點和問題
1.High investment in equipment and tools requires high production volumes.2.Lack of expertise and good preventive maintenance can cause high startup and running costs.1.較高的設備和模具投資需要較高生產量才合算。
2.缺少專門技術和良好的預防性維修會導致較高的啟動和運行成本。
3.Quality is sometimes difficult to determine immediately.For example, post-mold warpage may render parts unusable because of dimensional changes that are not completed for weeks or months after molding.3.質量有時難以馬上確定。例如，成型后的翹曲會導致零件不能用，因為在成型后幾星期甚至幾個月尺寸變化都不能完成。
4.Attention is required on many details requiring a wide variety of skills and cross-disciplinary knowledge.5.Part design sometimes is not well suited to efficient molding.4.對許多需要廣泛多樣性技能和交叉學科知識的細節必須加以注意。5.零件設計有時不能很好地適應有效率的成型。
6.Lead time for mold design, mold manufacture and debugging trials is sometimes very long.6.模具設計、模具制造和調試試驗這些先導工作有時要花費很長時間。
第七單元
The importance of machining processes can be emphasised by the fact that every product we use in our daily life has undergone this process either directly or indirectly.(1)In USA, more than $100 billions are spent annually on machining and related operations.機加工過程的重要性可通過日常生活使用的每件產品都直接或間接經歷這一過程的事實來強調。(1)在美國，每年花在機加工及其相關作業上的費用都多于千億美元。
(2)A large majority(above 80%)of all the machine tools used in the manufacturing industry have undergone metal cutting.(3)An estimate showed that about 10 to 15% of all the metal produced in USA was converted into chips.(2)用于制造業的全部機床中的大多數(多于80%)都經歷過金屬切削。(3)有估計顯示美國生產的所有金屬中約10到15%轉變成了切屑。
These facts show the importance of metal cutting in general manufacturing.It is therefore important to understand the metal cutting process in order to make the best use of it.這些事實說明了金屬切削在常規制造中的重要性。因此了解金屬切削過程以充分利用它是重要的。A number of attempts have been made in understanding the metal cutting process and using this knowledge to help improve manufacturing operations which involved metal cutting.在了解金屬切削過程并運用這些知識幫助改善與金屬切削有關的制造作業方面已經做了許多努力。A typical cutting tool in simplified form is shown in Fig.7.1.The important features to be observed are follows.典型切削刀具的簡化形式如圖7.1所示。要注意的重要特征如下。
1.Rake angle.It is the angle between the face of the tool called the rake face and the normal to the machining
direction.Higher the rake angle, better is the cutting and less are the cutting forces, increasing the rake angle reduces the metal backup available at the tool rake face.1.前角：它是被稱為前傾面的刀具面與垂直機加工方向的夾角。前角越大，則切削越好且切削力越小，增加前角可以減少刀具前傾面上產生的金屬阻塞。
This reduces the strength of the tool tip as well as the heat dissipation through the tool.Thus, there is a maximum limit to the rake angle and this is generally of the order of 15°for high speed steel tools cutting mild steel.It is possible to have rake angles at zero or negative.但這會和減少通過刀具散發的熱量一樣減少刀尖強度。因此前角有一最大限制，用高速鋼刀具切削低碳鋼通常為15°。前角取零度或負值也是可能的。
2.Clearance angle.This is the angle between the machined surface and the underside of the tool called the flank face.The clearance angle is provided such that the tool will not rub the machined surface thus spoiling the surface and increasing the cutting forces.A very large clearance angle reduces the strength of the tool tip, and hence normally an angle of the order of 5~6°is used.2.后角：這是機加工面與被稱為后側面的刀具底面夾角。后角使刀具不產生會損壞機加工面的摩擦和增加切削力。很大的后角會削弱刀尖的強度，因此一般采用5~6°的后角。
The conditions which have an important influence on metal cutting are work material, cutting tool material, cutting tool geometry, cutting speed, feed rate, depth of cut and cutting fluid used.對金屬切削有重要影響的條件有工件材料、刀具材料、刀具幾何形狀、切削速度、進給率、切削深度和所用的切削液。
The cutting speed, v, is the speed with which the cutting tool moves through the work material.This is generally expressed in metres per second(ms-1).切削速度v指切削刀具經過工件材料的移動速度。通常用米每秒(ms-1)表示。
Feed rate, f, may be defined as the small relative movement per cycle(per revolution or per stroke)of the cutting tool in a direction usually normal to the cutting speed direction.Depth of cut, d, is the normal distance between the unmachined surface and the machined surface.進給率f可定義為每循環(每轉或每行程)切削刀具在通常為垂直于切削速度方向的次要相對運動。切削深度d是未加工面與已加工面之間的垂直距離。
? Chip Formation 切屑的形成
Metal cutting process is a very complex process.Fig.7.2 shows the basic material removal operation schematically.金屬切削過程是一個很復雜的過程。圖7.2用圖的形式顯示了基本材料去除作業。
The metal in front of the tool rake face gets immediately compressed, first elastically and then plastically.This zone is traditionally called shear zone in view of fact that the material in the final form would be removed by shear from the parent
metal.在刀具前傾面前的金屬直接受到壓縮，首先彈性變形然后塑性變形。考慮到最終形狀中的材料是通過剪切從母體金屬去除的，此區域傳統上稱為剪切區。
The actual separation of the metal starts as a yielding or fracture, depending upon the cutting conditions, starting from the cutting tool tip.Then the deformed metal(called chip)flows over the tool(rake)face.金屬的實際分離始于屈服或斷裂(視切削條件而定)，從切削刀尖開始。然后變形金屬(稱為切屑)流過刀具(前傾)面。
If the friction between the tool rake face and the underside of the chip(deformed material)is considerable, then the chip gets further deformed, which is termed as secondary deformation.The chip after sliding over the tool rake face is lifted away from the tool, and the resultant curvature of the chip is termed as chip curl.如果刀具前傾面與切屑(變形金屬)底面之間的摩擦相當大，那么切屑進一步變形，這也叫做二次變形。滑過刀具前傾面的切屑被提升離開刀具，切屑彎曲的結果被稱為切屑卷。
Plastic deformation can be caused by yielding, in which case strained layers of material would get displaced over other layers along the slip-planes which coincide with the direction of maximum shear stress.屈服能導致塑性變形，在這種情況下材料變形層沿著與最大剪應力方向一致的滑移面被其它層所取代。A chip is variable both in size and shape in actual manufacturing practice.Study of chips is one of the most important things in metal cutting.As would be seen later, the mechanics of metal cutting are greatly dependent on the shape and size of the chips produced.在實際加工過程中切屑的尺寸和形狀都是變化的。對切屑的研究是金屬切削最重要的事情之一。如同后面將要看到的那樣，金屬切削力學極大地依賴于所產生切屑的形狀和尺寸。
Chip formation in metal cutting could be broadly categorised into three types:(Fig.7.3)(1)Discontinuous chip(2)Continuous chip(3)Continuous chip with BUE(Built up edge)金屬切削中的切屑形成可以寬泛地分成三個類型(圖7.3)：(1)間斷切屑(2)連續切屑
(3)帶切屑瘤的連續切屑
Discontinuous Chip.The segmented chip separates into short pieces, which may or may not adhere to each other.Severe distortion of the metal occurs adjacent to the face, resulting in a crack that runs ahead of the tool.間斷切屑：分段的切屑分散成小碎片，既可能相互附著也可能不相互附著。在靠近切削面處發生金屬的劇烈變形，導致在運動刀具前方金屬層產生裂縫。
Eventually, the shear stress across the chip becomes equal to the shear strength of the material, resulting in fracture and separation.With this type of chip, there is little relative movement of the chip along the tool face, Fig.7.3a.最后，橫過切屑的剪切應力與材料的剪切強度相等，造成斷裂和分離。生成這類切屑時，切屑沿刀具面幾乎沒有相對運動，見圖7.3a。
Continuous chip.The continuous chip is characterized by a general flow of the separated metal along the tool face.There may be some cracking of the chip, but in this case it usually does not extend far enough to cause fracture.連續切屑：連續的切屑一般具有分離金屬沿刀具面流動的特征。切屑可能有一些破裂，但在這種情況下切屑通常不會延長到足以引起斷裂。
This chip is formed at the higher cutting speeds when machining ductile materials.There is little tendency for the material to adhere to the tool.The continuous chip usually shows a good cutting ratio and tends to produce the optimum surface finish, but it may become an operating hazard, Fig.7.3b.這種切屑形成于用較高切削速度機加工有延展性的材料時。材料幾乎沒有粘附刀具的傾向。連續切屑通常具有良好的切削率和趨向于產生最適宜的表面光潔度，但可能成為操作的危險之源，見圖7.3b。
Continuous with a built-up edge.This chip shows the existence of a localized, highly deformed zone of material attached or “welded” on the tool face.帶切屑瘤的連續切屑：這種切屑顯示了粘合或“焊接”在刀具面上材料局部高度變形區的存在。
Actually, analysis of photomicrographs shows that this built-up edge is held in place by the static friction force until it becomes so large that the external forces acting on it cause it to dislodge, with some of it remaining on the machined surface and the rest passing off on the back side of the chip, Fig.7.3c.實際上，對顯微照片的分析顯示這種切屑瘤受到靜摩擦力抑制直至它變得大到作用在它上面的外力使其移動，一些留在機加工表面上而另一些延伸到切屑的背面，見圖7.3c。
? Shear Zone
剪切區
There are basically two schools of thought in the analysis of the metal removal process.One school of thought is that the deformation zone is very thin and planar as shown in Fig.7.4a.The other school thinks that the actual deformation zone is a thick one with a fan shape as shown in Fig.7.4b.在對金屬去除過程的分析中主要存在兩種思想學派。一種思想學派認為變形區如圖7.4a所示那樣非常薄而平坦。另一學派則認為真實變形區象圖7.4b所示那樣為一厚的帶有扇形的區域。
Though the first model(Fig.7.4a)is convenient from the point of analysis, physically it is impossible to exist.This is because for the transition from undeformed material to deform to take place along a thin plane, the acceleration across the plane has to be infinity.雖然第一種模型(圖7.4a)從分析的角度看是方便的，但實際上是不可能存在的。這是由于未變形的材料沿著剪切面發生變形，而且越過剪切面的加速度無窮大。
第四篇：機械工程英語第二版翻譯HT-12-14（范文）
第十二單元 鉆削和鉆頭
Drillingsurfaces.空心鉆用于擴大已有的孔而不是打孔。這類鉆頭具有較大生產率、高加工精度和優良鉆削表面質量的特性。
Gun drills.-to the tip of the drill.鉆削作業既能采用手鉆也能采用鉆床來實現。鉆床在尺寸和結構上雖有差別，然而始終都是切削刀具圍繞自身軸線旋轉、工件穩固定位的形式。這正好與在車床上鉆孔相反。Cutting-, which can be straight or helical.用于鉆削作業的切削刀具
在鉆削作業中，要用到被稱為鉆頭的圓柱形回轉端切削刀具。鉆頭可以有一條或多條直的或是螺旋狀的切削刃以及相應的出屑槽。
The functionfor transmitting rotation.錐形鉆柄通過楔入動作安裝在主軸的錐形軸孔中，鉆柄上還有柄舌插入主軸軸孔中的插槽，從而作為傳遞轉動的可靠方法。
On the other hand, straight-shank-shank drills.另一方面，直柄鉆頭用鉆頭卡盤夾住，接下來鉆頭卡盤則象錐形鉆柄鉆頭一樣安裝在主軸軸孔內。
As can-while it is in operation.如圖12.1所示，兩條切削刃就是鉆唇，通過鑿子狀邊緣的楔形體連在一起。麻花鉆還有兩條導向邊，用于作業中鉆頭的正確導向和定位。
The toolin.(i.e., 0.25 up to 80 mm).雖然也有硬質合金刀尖的鉆頭，麻花鉆一般用高速鋼制成。工業實際中使用的麻花鉆尺寸范圍為0.01到3.25英寸(即0.25到80毫米)。
Core drills.A core-the accuracy.空心鉆：空心鉆包括斜面、鉆頭體、鉆頸和鉆柄，如圖12.2所示。這類鉆頭可以有三條或四條出屑槽及相同數量的保證良好導向的導向邊，這樣使得加工有高精 深孔鉆：深孔鉆用于鉆深孔。所有深孔鉆都是直出屑槽的，并且均為單切削刃。鉆頭體中有個孔作為導管在相當大的壓力下將冷卻液傳送到鉆頭頂端。There are t-drilling operation.深孔鉆有兩種類型，即用于鉆盲孔的中心切削深孔鉆和套孔鉆。后者在其中心有一圓柱形溝槽，這樣能生成整體芯在鉆孔作業過程中引導鉆頭。
Spade drills.-easy to grind.扁平鉆：扁平鉆用于鉆削3.5英寸(90毫米)或更大的大孔。其設計使得鉆頭成本明顯節省、重量切實減輕，重量輕又使操作更方便。此外這種鉆頭容易磨利。
? Milling and Milling Cutter
銑削和銑刀
Milling-milling cutter.銑削是采用被稱為銑刀的多刃旋轉刀具完成的機加工作業。
In this process,-gear-cutting operation.在此工藝中，金屬去除是通過銑刀的旋轉運動和工件的直線運動的組合實現的。銑削作業既可用于生成平面、輪廓面和螺旋面，也可用于切削螺紋和齒輪。Each of-rake and relief angles.在銑刀切削工件金屬時，銑刀的每條切削刃都象一單獨的單刃刀具一樣作用。所以每條切削刃都適當的前后角。
Since only-than those for turning or drilling.由于同一時間只有部分切削刃切削工件，因此可以在對刀具壽命沒有不利影響的情況下承擔重型切削。事實上，銑削允許的切削速度和進給比車削或鉆削高三到四倍。Moreover,-by turning, shaping, or drilling.此外，由銑削加工的表面質量通常優于車削、刨削或鉆削加工的表面質量。
A wide variety-of a machining workshop.工業上可采用的銑刀類型眾多。連同銑床是極通用機床的事實，使得銑床成為機加工車間的支柱。As far as-he following two methods.至于涉及到銑刀轉動的方向和工件的進給，銑削可以通過下列兩種方法之一進行。
Up milling--cutting edges.逆銑(傳統銑削)：在逆銑中，工件逆著銑刀轉動的方向進給，如圖12.3a所示。就像在此圖中能看到的那樣，切削深度(及作為結果的載荷)隨著切削刃持續進入切削而逐漸增加。
Therefore,forces act downward.這會導致一種沖擊，或突然加載。因此，這種方法只有當銑床在進給螺栓上配備間隙消除器時才采用。這種方法的優點包括機加工表面質量較高和工件由于切削力向下作用而較容易夾緊。
Types ofsurfaces.平面銑刀：平面銑刀是一種盤狀切削刀具，它可以具有直齒或螺旋齒，如圖12.4a所示。這類銑刀總是安裝在臥式銑床上，用于機加工平面。
Face-cutter of this type.端面銑刀：端面銑刀也可用于機加工平面。它用螺栓固定在短刀桿的端部，而短刀桿則依次安裝于立式銑床上。圖12.4b顯示了這類銑刀。
Plain-a very thin plain milling cutter.平面金屬開槽鋸刃銑刀：圖12.4c顯示了一種平面金屬開槽鋸刃銑刀。可以看到它其實是一種很薄的平面銑刀。
Side milling-can be straight or helical.側銑刀：側銑刀用于切削狹槽、凹槽和花鍵槽。正如圖12.4d所示，它與平面銑刀十分相似，差別在于此類銑刀齒在側面。象平面銑刀的情況一樣，切削齒既可以是直的也可以是螺旋的。
Angle milling-this type.傾斜銑刀：傾斜銑刀用于切削燕尾槽、棘輪之類的。圖12.4e顯示了這類銑刀。
T-slot cutter.-milling T-slots.T型槽銑刀：如圖12.4f所示，T型槽銑刀包括了一個平面銑刀和一根垂直于它的整體軸。正像其名字所表明的，這類銑刀用于銑削T型槽。
End mill--straight or helical.端面銑刀：端面銑刀在切削狹槽、凹槽、長凹槽、花鍵槽、凹狀工件之類時均能發現其普遍應用。圖12.4g為端面銑刀。它總是安裝在立式銑床上，并具有兩到四條既可是直的也可是螺旋的長凹槽。
Form millingspeeds are required.對大規模生產而言，因為其需要重型切削和/或高切削速度，銑刀頂端常裝有燒結碳化物或有色金屬碳合金作為切削齒。
第十四單元
Dimensioning 標注尺寸
The design-proper materials.機械設計除了計算載荷和應力、選擇合適的材料外，還包括許多其它因素。
Before-all phases of production drawings.在建造或制造開始前，完成裝配圖和零件圖以把必要信息傳達給車間工人是必須的。在送往車間前設計者常常被召集來檢查圖紙。而在精通生產圖紙的所有情況之前，需要有許多經驗并熟悉制造工藝。
Drawings should-ne interpretation.圖紙必須仔細檢查其尺寸是否按生產部門最方便易懂的方式標注。很明顯圖紙應該只有唯一的解釋。In particular,-for its mastery.尤其是不能要求車間工人在生產機械安排前進行三角或其它復雜的計算。
尺寸標注是一項復雜的工作，要掌握它需要有豐富的經驗。
Tolerances-given dimension.由于要把零件加工到正好為給定尺寸是不可能的，因此圖紙的尺寸必須加上公差以限制其可允許的變化。Although-or functional considerations permit.雖然較小公差能得到較高加工質量和較好操作機構，但隨著公差的減小制造成本會迅速增加，如圖14.1的典型曲線所示。因此公差被定為從操作或功能考慮允許的最大值是重要的。
Tolerances-each way from this dimension.公差既可以是單向的也可以是雙向的。單向標注有一公差為零，所有變化都由另一公差給定。而雙向標注則采用一平均尺寸，它將公差帶中點從該尺寸雙向擴展為相等的正負變化范圍。
The development-ssembly with the mating parts.大規模低成本制造生產工藝的發展很大程度取決于組成零件的互換性。因此設計者必須確定單個零件的合適公差以及配合零件裝配允許的正確間隙或過盈量。The manner of placing--such dimensions.在圖紙上標注公差的方法相當程度上依賴于產品的性質或制造工藝的類型。如果尺寸公差沒有特別注明，圖紙應該包含一個給出這些尺寸公差值的普遍適用注釋。However, some-single interpretation.然而有些公司不采用普遍適用注釋，假定每個尺寸是單獨被考慮的，可能會規定出比注釋中要求的更寬的公差。在任何情況下圖紙不模棱兩可并只服從于單一的解釋是十分重要的。
? Dimension and Tolerance 尺寸和公差
In dimensioninggeneral tolerances.偶爾也可能為了檢查而必須給出供參考的輔助尺寸。在這種情況下，尺寸應該用括號括起來，以便參考。這樣的尺寸不受通用公差控制。
Dimensions-other dimensions.影響零件功能的尺寸總是應該標注的而不要留作其它尺寸的和或差。
一根軸可能的名義尺寸為2.5in.(63.5mm)，但由于實際原因不用大成本是不能在制造中保持這個數字的，因此要增加確定的公差。如果允許有±0.003in.(±0.08mm)的變化，則此尺寸可表達為2.500±0.003(63.5±0.08mm)。Dimensions given closeconvenient to manufacture.圖紙必須按方便制造零件的方式將設計者的要求真實和完整地表達出來。
Every dimension-possible, appear on the same view.對每一描述產品所需的尺寸都只須標注一次而不必在不同的視圖中重復。有關同一特性的尺寸，諸如孔的位置和If thisinterchangeability.除非另行說明，所有尺寸都必須受圖上的通用公差控制。一般這樣的公差受到尺寸量值的控制。在影響功能或互換性的尺寸上必須標注專門的公差。A systemtolerance grade.公差是基本尺寸的函數 并通過一個被稱為等級的數字符號標明—即公差等級。
The position-of 45 mm might be 45H8/g7.公差相對于零線的位置同樣為基本尺寸的函數通過一個或兩個字母符號表達，大寫字母表示孔而小寫字母表示軸。這樣基本尺寸為45毫米的一個孔和軸配合規格可能是45H8/g7。
Twenty standard grades-400~500 mm).ISO規定了二十種標準的公差等級，稱之為IT01，IT0，IT1~18，給在直至500毫米強行分段(例如0~3，3~6，6~10,......, 400~500毫米)中的公稱直徑提供具體數值。
The value of-microns and D in millimeters.對5～16級而言，公差單位i的值可用下式計算這里i的單位是微米，而D的單位是毫米。
Standard shaft--of rather complex tables.標準的軸和孔偏差同樣都由若干公式提供；然而對實際應用，公差和偏差都在三張相當復雜的表格中規定了。
Additional tables-and Horology”.對基本尺寸大于500毫米和在“一般用途”和“精密機械和鐘表”兩個類別中的“常用的軸和孔”而言，由附加的表格給出數值。
第五篇：機械工程英語第二版翻譯
Unit1 Types of Materials
材料的類型
Materials may be grouped in several ways.Scientists often classify materials by their state: solid, liquid, or gas.They also separate them into organic(once living)and inorganic(never living)materials.材料可以按多種方法分類。科學家常根據狀態將材料分為：固體、液體或氣體。他們也把材料分為有機材料(曾經有生命的)和無機材料(從未有生命的)。
For industrial purposes, materials are divided into engineering materials or nonengineering materials.Engineering materials are those used in manufacture and become parts of products.就工業效用而言，材料被分為工程材料和非工程材料。那些用于加工制造并成為產品組成部分的就是工程材料。
Nonengineering materials are the chemicals, fuels, lubricants, and other materials used in the manufacturing process, which do not become part of the product.非工程材料則是化學品、燃料、潤滑劑以及其它用于加工制造過程但不成為產品組成部分的材料。
Engineering materials may be further subdivided into: ①Metal ②Ceramics ③Composite ④Polymers, etc.工程材料還能進一步細分為：①金屬材料②陶瓷材料③復合材料 ④聚合材料，等等。Metals and Metal Alloys 金屬和金屬合金
Metals are elements that generally have good electrical and thermal conductivity.Many metals have high strength, high stiffness, and have good ductility.金屬就是通常具有良好導電性和導熱性的元素。許多金屬具有高強度、高硬度以及良好的延展性。Some metals, such as iron, cobalt and nickel, are magnetic.At low temperatures, some metals and intermetallic compounds become superconductors.某些金屬能被磁化，例如鐵、鈷和鎳。在極低的溫度下，某些金屬和金屬化合物能轉變成超導體。
What is the difference between an alloy and a pure metal? Pure metals are elements which come from a particular area of the periodic table.Examples of pure metals include copper in electrical wires and aluminum in cooking foil and beverage cans.合金與純金屬的區別是什么？純金屬是在元素周期表中占據特定位置的元素。例如電線中的銅和制造烹飪箔及飲料罐的鋁。
Alloys contain more than one metallic element.Their properties can be changed by changing the elements present in the alloy.Examples of metal alloys include stainless steel which is an alloy of iron, nickel, and chromium;and gold jewelry which usually contains an alloy of gold and nickel.合金包含不止一種金屬元素。合金的性質能通過改變其中存在的元素而改變。金屬合金的例子有：不銹鋼是一種鐵、鎳、鉻的合金，以及金飾品通常含有金鎳合金。
Why are metals and alloys used? Many metals and alloys have high densities and are used in applications which require a high mass-to-volume ratio.為什么要使用金屬和合金？許多金屬和合金具有高密度，因此被用在需要較高質量體積比的場合。Some metal alloys, such as those based on aluminum, have low densities and are used in aerospace applications for fuel economy.Many alloys also have high fracture toughness, which means they can withstand impact and are durable.某些金屬合金，例如鋁基合金，其密度低，可用于航空航天以節約燃料。許多合金還具有高斷裂韌性，這意味著它們能經得起沖擊并且是耐用的。
What are some important properties of metals?
Density is defined as a material’s mass divided by its volume.Most metals have relatively high densities, especially compared to polymers.金屬有哪些重要特性？
密度定義為材料的質量與其體積之比。大多數金屬密度相對較高，尤其是和聚合物相比較而言。Materials with high densities often contain atoms with high atomic numbers, such as gold or lead.However, some metals such as aluminum or magnesium have low densities, and are used in applications that require other metallic properties but also require low weight.高密度材料通常由較大原子序數原子構成，例如金和鉛。然而，諸如鋁和鎂之類的一些金屬則具有低密度，并被用于既需要金屬特性又要求重量輕的場合。
Fracture toughness can be described as a material’s ability to avoid fracture, especially when a flaw is introduced.Metals can generally contain nicks and dents without weakening very much, and are impact resistant.A football player counts on this when he trusts that his facemask won’t shatter.斷裂韌性可以描述為材料防止斷裂特別是出現缺陷時不斷裂的能力。金屬一般能在有缺口和凹痕的情況下不顯著削弱，并且能抵抗沖擊。橄欖球運動員據此相信他的面罩不會裂成碎片。
Plastic deformation is the ability of bend or deform before breaking.As engineers, we usually design materials so that they don’t deform under normal conditions.You don’t want your car to lean to the east after a strong west wind.塑性變形就是在斷裂前彎曲或變形的能力。作為工程師，設計時通常要使材料在正常條件下不變形。沒有人愿意一陣強烈的西風過后自己的汽車向東傾斜。
However, sometimes we can take advantage of plastic deformation.The crumple zones in a car absorb energy by undergoing plastic deformation before they break.然而，有時我們也能利用塑性變形。汽車上壓皺的區域在它們斷裂前通過經歷塑性變形來吸收能量。
The atomic bonding of metals also affects their properties.In metals, the outer valence electrons are shared among all atoms, and are free to travel everywhere.Since electrons conduct heat and electricity, metals make good cooking pans and electrical wires.金屬的原子連結對它們的特性也有影響。在金屬內部，原子的外層階電子由所有原子共享并能到處自由移動。由于電子能導熱和導電，所以用金屬可以制造好的烹飪鍋和電線。
It is impossible to see through metals, since these valence electrons absorb any photons of light which reach the metal.No photons pass through.因為這些階電子吸收到達金屬的光子，所以透過金屬不可能看得見。沒有光子能通過金屬。
Alloys are compounds consisting of more than one metal.Adding other metals can affect the density, strength, fracture toughness, plastic deformation, electrical conductivity and environmental degradation.合金是由一種以上金屬組成的混合物。加一些其它金屬能影響密度、強度、斷裂韌性、塑性變形、導電性以及環境侵蝕。
For example, adding a small amount of iron to aluminum will make it stronger.Also, adding some chromium to steel will slow the rusting process, but will make it more brittle.例如，往鋁里加少量鐵可使其更強。同樣，在鋼里加一些鉻能減緩它的生銹過程，但也將使它更脆。Ceramics and Glasses陶瓷和玻璃
A ceramic is often broadly defined as any inorganic nonmetallic material． By this definition, ceramic materials would also include glasses;however, many materials scientists add the stipulation that “ceramic” must also be crystalline.陶瓷通常被概括地定義為無機的非金屬材料。照此定義，陶瓷材料也應包括玻璃；然而許多材料科學家添加了“陶瓷”必須同時是晶體物組成的約定。
A glass is an inorganic nonmetallic material that does not have a crystalline structure.Such materials are said to be amorphous.玻璃是沒有晶體狀結構的無機非金屬材料。這種材料被稱為非結晶質材料。Properties of Ceramics and Glasses
Some of the useful properties of ceramics and glasses include high melting temperature, low density, high strength, stiffness, hardness, wear resistance, and corrosion resistance.陶瓷和玻璃的特性
高熔點、低密度、高強度、高剛度、高硬度、高耐磨性和抗腐蝕性是陶瓷和玻璃的一些有用特性。Many ceramics are good electrical and thermal insulators.Some ceramics have special properties: some ceramics are magnetic materials;some are piezoelectric materials;and a few special ceramics are superconductors at very low temperatures.Ceramics and glasses have one major drawback: they are brittle.許多陶瓷都是電和熱的良絕緣體。某些陶瓷還具有一些特殊性能：有些是磁性材料，有些是壓電材料，還有些特殊陶瓷在極低溫度下是超導體。陶瓷和玻璃都有一個主要的缺點：它們容易破碎。
Ceramics are not typically formed from the melt.This is because most ceramics will crack extensively(i.e.form a powder)upon cooling from the liquid state.陶瓷一般不是由熔化形成的。因為大多數陶瓷在從液態冷卻時將會完全破碎(即形成粉末)。Hence, all the simple and efficient manufacturing techniques used for glass production such as casting and blowing, which involve the molten state, cannot be used for the production of crystalline ceramics.Instead, “sintering” or “firing” is the process typically used.因此，所有用于玻璃生產的簡單有效的—諸如澆鑄和吹制這些涉及熔化的技術都不能用于由晶體物組成的陶瓷的生產。作為替代，一般采用“燒結”或“焙燒”工藝。
In sintering, ceramic powders are processed into compacted shapes and then heated to temperatures just below the melting point.At such temperatures, the powders react internally to remove porosity and fully dense articles can be obtained.在燒結過程中，陶瓷粉末先擠壓成型然后加熱到略低于熔點溫度。在這樣的溫度下，粉末內部起反應去除孔隙并得到十分致密的物品。
An optical fiber contains three layers: a core made of highly pure glass with a high refractive index for the light to travel, a middle layer of glass with a lower refractive index known as the cladding which protects the core glass from scratches and other surface imperfections, and an out polymer jacket to protect the fiber from damage.光導纖維有三層：核心由高折射指數高純光傳輸玻璃制成，中間層為低折射指數玻璃，是保護核心玻璃表面不被擦傷和完整性不被破壞的所謂覆層，外層是聚合物護套，用于保護光導纖維不受損。In order for the core glass to have a higher refractive index than the cladding, the core glass is doped with a small, controlled amount of an impurity, or dopant, which causes light to travel slower, but does not absorb the light.為了使核心玻璃有比覆層大的折射指數，在其中摻入微小的、可控數量的能減緩光速而不會吸收光線的雜質或攙雜劑。
Because the refractive index of the core glass is greater than that of the cladding, light traveling in the core glass will remain in the core glass due to total internal reflection as long as the light strikes the core/cladding interface at an angle greater than the critical angle.由于核心玻璃的折射指數比覆層大，只要在全內反射過程中光線照射核心/覆層分界面的角度比臨界角大，在核心玻璃中傳送的光線將仍保留在核心玻璃中。The total internal reflection phenomenon, as well as the high purity of the core glass, enables light to travel long distances with little loss of intensity.全內反射現象與核心玻璃的高純度一樣，使光線幾乎無強度損耗傳遞長距離成為可能。Composites
復合材料
Composites are formed from two or more types of materials.Examples include polymer/ceramic and metal/ceramic composites.Composites are used because overall properties of the composites are superior to those of the individual components.復合材料由兩種或更多材料構成。例子有聚合物/陶瓷和金屬/陶瓷復合材料。之所以使用復合材料是因為其全面性能優于組成部分單獨的性能。
For example: polymer/ceramic composites have a greater modulus than the polymer component, but aren’t as brittle as ceramics.Two types of composites are: fiber-reinforced composites and particle-reinforced composites.例如：聚合物/陶瓷復合材料具有比聚合物成分更大的模量，但又不像陶瓷那樣易碎。
復合材料有兩種：纖維加強型復合材料和微粒加強型復合材料。Fiber-reinforced Composites
Reinforcing fibers can be made of metals, ceramics, glasses, or polymers that have been turned into graphite and known as carbon fibers.Fibers increase the modulus of the matrix material.纖維加強型復合材料
加強纖維可以是金屬、陶瓷、玻璃或是已變成石墨的被稱為碳纖維的聚合物。纖維能加強基材的模量。
The strong covalent bonds along the fiber’s length give them a very high modulus in this direction because to break or extend the fiber the bonds must also be broken or moved.沿著纖維長度有很強結合力的共價結合在這個方向上給予復合材料很高的模量，因為要損壞或拉伸纖維就必須破壞或移除這種結合。
Fibers are difficult to process into composites, making fiber-reinforced composites relatively expensive.把纖維放入復合材料較困難，這使得制造纖維加強型復合材料相對昂貴。
Fiber-reinforced composites are used in some of the most advanced, and therefore most expensive sports equipment, such as a time-trial racing bicycle frame which consists of carbon fibers in a thermoset polymer matrix.纖維加強型復合材料用于某些最先進也是最昂貴的運動設備，例如計時賽競賽用自行車骨架就是用含碳纖維的熱固塑料基材制成的。
Body parts of race cars and some automobiles are composites made of glass fibers(or fiberglass)in a thermoset matrix.競賽用汽車和某些機動車的車體部件是由含玻璃纖維(或玻璃絲)的熱固塑料基材制成的。
Fibers have a very high modulus along their axis, but have a low modulus perpendicular to their axis.Fiber composite manufacturers often rotate layers of fibers to avoid directional variations in the modulus.纖維在沿著其軸向有很高的模量，但垂直于其軸向的模量卻較低。纖維復合材料的制造者往往旋轉纖維層以防模量產生方向變化。Particle-reinforced composites
Particles used for reinforcing include ceramics and glasses such as small mineral particles, metal particles such as
aluminum, and amorphous materials，including polymers and carbon black.微粒加強型復合材料
用于加強的微粒包含了陶瓷和玻璃之類的礦物微粒，鋁之類的金屬微粒以及包括聚合物和碳黑的非結晶質微粒。
Particles are used to increase the modulus of the matrix, to decrease the permeability of the matrix, to decrease the ductility of the matrix.An example of particle-reinforced composites is an automobile tire which has carbon black particles in a matrix of polyisobutylene elastomeric polymer.微粒用于增加基材的模量、減少基材的滲透性和延展性。微粒加強型復合材料的一個例子是機動車胎，它就是在聚異丁烯人造橡膠聚合物基材中加入了碳黑微粒。Polymers
聚合材料
A polymer has a repeating structure, usually based on a carbon backbone.The repeating structure results in large chainlike molecules.Polymers are useful because they are lightweight, corrosion resistant, easy to process at low temperatures and generally inexpensive.聚合物具有一般是基于碳鏈的重復結構。這種重復結構產生鏈狀大分子。由于重量輕、耐腐蝕、容易在較低溫度下加工并且通常較便宜，聚合物是很有用的。
Some important characteristics of polymers include their size(or molecular weight), softening and melting points, crystallinity, and structure.The mechanical properties of polymers generally include low strength and high toughness.Their strength is often improved using reinforced composite structures.聚合材料具有一些重要特性，包括尺寸(或分子量)、軟化及熔化點、結晶度和結構。聚合材料的機械性能一般表現為低強度和高韌性。它們的強度通常可采用加強復合結構來改善。Important Characteristics of Polymers
Size.Single polymer molecules typically have molecular weights between 10,000 and 1,000,000g/mol—that can be more than 2,000 repeating units depending on the polymer structure!聚合材料的重要特性
尺寸：單個聚合物分子一般分子量為10,000到1,000,000g/mol之間，具體取決于聚合物的結構—這可以比2,000個重復單元還多。
The mechanical properties of a polymer are significantly affected by the molecular weight, with better engineering properties at higher molecular weights.聚合物的分子量極大地影響其機械性能，分子量越大，工程性能也越好。
Thermal transitions.The softening point(glass transition temperature)and the melting point of a polymer will determine which it will be suitable for applications.These temperatures usually determine the upper limit for which a polymer can be used.熱轉換性：聚合物的軟化點(玻璃狀轉化溫度)和熔化點決定了它是否適合應用。這些溫度通常決定聚合物能否使用的上限。
For example, many industrially important polymers have glass transition temperatures near the boiling point of water(100℃, 212℉), and they are most useful for room temperature applications.Some specially engineered polymers can withstand temperatures as high as 300℃(572℉).例如，許多工業上的重要聚合物其玻璃狀轉化溫度接近水的沸點(100℃, 212℉)，它們被廣泛用于室溫下。而某些特別制造的聚合物能經受住高達300℃(572℉)的溫度。
Crystallinity.Polymers can be crystalline or amorphous, but they usually have a combination of crystalline and amorphous structures(semi-crystalline).結晶度：聚合物可以是晶體狀的或非結晶質的，但它們通常是晶體狀和非結晶質結構的結合物(半晶體)。
Interchain interactions.The polymer chains can be free to slide past one another(thermo-plastic)or they can be connected to each other with crosslinks(thermoset or elastomer).Thermo-plastics can be reformed and recycled, while thermosets and elastomers are not reworkable.原子鏈間的相互作用：聚合物的原子鏈可以自由地彼此滑動(熱可塑性)或通過交鍵互相連接(熱固性或彈性)。熱可塑性材料可以重新形成和循環使用，而熱固性與彈性材料則是不能再使用的。
Intrachain structure.The chemical structure of the chains also has a tremendous effect on the properties.Depending on the structure the polymer may be hydrophilic or hydrophobic(likes or hates water), stiff or flexible, crystalline or amorphous, reactive or unreactive.鏈內結構：原子鏈的化學結構對性能也有很大影響。根據各自的結構不同，聚合物可以是親水的或憎水的(喜歡或討厭水)、硬的或軟的、晶體狀的或非結晶質的、易起反應的或不易起反應的。
Unit2
The understanding of heat treatment is embraced by the broader study of metallurgy.Metallurgy is the physics, chemistry, and engineering related to metals from ore extraction to the final product.對熱處理的理解包含于對冶金學較廣泛的研究。冶金學是物理學、化學和涉及金屬從礦石提煉到最后產物的工程學。
Heat treatment is the operation of heating and cooling a metal in its solid state to change its physical properties.According to the procedure used, steel can be hardened to resist cutting action and abrasion, or it can be softened to permit machining.熱處理是將金屬在固態加熱和冷卻以改變其物理性能的操作。按所采用的步驟，鋼可以通過硬化來抵抗切削和磨損，也可以通過軟化來允許機加工。
With the proper heat treatment internal stresses may be removed, grain size reduced, toughness increased, or a hard surface produced on a ductile interior.The analysis of the steel must be known because small percentages of certain elements, notably carbon, greatly affect the physical properties.使用合適的熱處理可以去除內應力、細化晶粒、增加韌性或在柔軟材料上覆蓋堅硬的表面。因為某些元素(尤其是碳)的微小百分比極大地影響物理性能，所以必須知道對鋼的分析。
Alloy steel owe their properties to the presence of one or more elements other than carbon, namely nickel, chromium, manganese, molybdenum, tungsten, silicon, vanadium, and copper.Because of their improved physical properties they are used commercially in many ways not possible with carbon steels.合金鋼的性質取決于其所含有的除碳以外的一種或多種元素，如鎳、鉻、錳、鉬、鎢、硅、釩和銅。由于合金鋼改善的物理性能，它們被大量使用在許多碳鋼不適用的地方。
The following discussion applies principally to the heat treatment of ordinary commercial steels known as plain carbon steels.With this process the rate of cooling is the controlling factor, rapid cooling from above the critical range results in hard structure, whereas very slow cooling produces the opposite effect.下列討論主要針對被稱為普通碳鋼的工業用鋼而言。熱處理時冷卻速率是控制要素，從高于臨界溫度快速冷卻導致堅硬的組織結構，而緩慢冷卻則產生相反效果。A Simplified Iron-carbon Diagram簡化鐵碳狀態圖
If we focus only on the materials normally known as steels, a simplified diagram is often used.如果只把注意力集中于一般所說的鋼上，經常要用到簡化鐵碳狀態圖。
Those portions of the iron-carbon diagram near the delta region and those above 2% carbon content are of little importance to the engineer and are deleted.A simplified diagram, such as the one in Fig.2.1, focuses on the eutectoid region and is quite useful in understanding the properties and processing of steel.鐵碳狀態圖中靠近三角區和含碳量高于2%的那些部分對工程師而言不重要，因此將它們刪除。如圖2.1所示的簡化鐵碳狀態圖將焦點集中在共析區，這對理解鋼的性能和處理是十分有用的。
The key transition described in this diagram is the decomposition of single-phase austenite(γ)to the two-phase ferrite plus carbide structure as temperature drops.在此圖中描述的關鍵轉變是單相奧氏體(γ)隨著溫度下降分解成兩相鐵素體加滲碳體組織結構。Control of this reaction, which arises due to the drastically different carbon solubility of austenite and ferrite, enables a wide range of properties to be achieved through heat treatment.控制這一由于奧氏體和鐵素體的碳溶解性完全不同而產生的反應，使得通過熱處理能獲得很大范圍的特性。
To begin to understand these processes, consider a steel of the eutectoid composition, 0.77% carbon, being slow cooled along line x-x’ in Fig.2.1.At the upper temperatures, only austenite is present, the 0.77% carbon being dissolved in solid solution with the iron.When the steel cools to 727℃(1341℉), several changes occur simultaneously.為了理解這些過程，考慮含碳量為0.77%的共析鋼，沿著圖2.1的x-x’線慢慢冷卻。在較高溫度時，只存在奧氏體，0.77%的碳溶解在鐵里形成固溶體。當鋼冷卻到727℃(1341℉)時，將同時發生若干變化。
The iron wants to change from the FCC austenite structure to the BCC ferrite structure, but the ferrite can only contain 0.02% carbon in solid solution.鐵需要從面心立方體奧氏體結構轉變為體心立方體鐵素體結構，但是鐵素體只能容納固溶體狀態的0.02%的碳。
The rejected carbon forms the carbon-rich cementite intermetallic with composition Fe3C.In essence, the net reaction at the eutectoid is austenite 0.77%C→ferrite 0.02%C+cementite 6.67%C.被析出的碳與金屬化合物Fe3C形成富碳的滲碳體。本質上，共析體的基本反應是奧氏體0.77%的碳→鐵素體0.02%的碳+滲碳體6.67%的碳。
Since this chemical separation of the carbon component occurs entirely in the solid state, the resulting structure is a fine mechanical mixture of ferrite and cementite.Specimens prepared by polishing and etching in a weak solution of nitric acid and alcohol reveal the lamellar structure of alternating plates that forms on slow cooling.由于這種碳成分的化學分離完全發生在固態中，產生的組織結構是一種細致的鐵素體與滲碳體的機械混合物。通過打磨并在弱硝酸酒精溶液中蝕刻制備的樣本顯示出由緩慢冷卻形成的交互層狀的薄片結構。
This structure is composed of two distinct phases, but has its own set of characteristic properties and goes by the name pearlite, because of its resemblance to mother-of-pearl at low magnification.這種結構由兩種截然不同的狀態組成，但它本身具有一系列特性，且因與低倍數放大時的珠母層有類同之處而被稱為珠光體。
Steels having less than the eutectoid amount of carbon(less than 0.77%)are known as hypo-eutectoid steels.Consider now the transformation of such a material represented by cooling along line y-y’ in Fig.2.1.含碳量少于共析體(低于0.77%)的鋼稱為亞共析鋼。現在來看這種材料沿著圖2.1中y-y’ 線冷卻的轉變情況。
At high temperatures, the material is entirely austenite, but upon cooling enters a region where the stable phases are ferrite and austenite.Tie-line and level-law calculations show that low-carbon ferrite nucleates and grows, leaving the remaining austenite richer in carbon.在較高溫度時，這種材料全部是奧氏體，但隨著冷卻就進入到鐵素體和奧氏體穩定狀態的區域。由截線及杠桿定律分析可知，低碳鐵素體成核并長大，剩下含碳量高的奧氏體。
At 727℃(1341℉), the austenite is of eutectoid composition(0.77% carbon)and further cooling transforms the remaining austenite to pearlite.The resulting structure is a mixture of primary or pro-eutectoid ferrite(ferrite that formed above the eutectoid reaction)and regions of pearlite.在727℃(1341℉)時，奧氏體為共析組成(含碳量0.77%)，再冷卻剩余的奧氏體就轉化為珠光體。作為結果的組織結構是初步的共析鐵素體(在共析反應前的鐵素體)和部分珠光體的混合物。
Hypereutectoid steels are steels that contain greater than the eutectoid amount of carbon.When such steel cools, as shown in z-z’ of Fig.2.1 the process is similar to the hypo-eutectoid case, except that the primary or pro-eutectoid phase is now cementite instead of ferrite.過共析鋼是含碳量大于共析量的鋼。當這種鋼冷卻時，就像圖2.1的z-z’線所示，除了初步的共析狀態用滲碳體取代鐵素體外，其余類似亞共析鋼的情況。
As the carbon-rich phase forms, the remaining austenite decreases in carbon content, reaching the eutectoid composition at 727℃(1341℉).As before, any remaining austenite transforms to pearlite upon slow cooling through this temperature.隨著富碳部分的形成，剩余奧氏體含碳量減少，在727℃(1341℉)時達到共析組織。就像以前說的一樣，當緩慢冷卻到這溫度時所有剩余奧氏體轉化為珠光體。
It should be remembered that the transitions that have been described by the phase diagrams are for equilibrium conditions, which can be approximated by slow cooling.With slow heating, these transitions occur in the reverse manner.應該記住由狀態圖描述的這種轉化只適合于通過緩慢冷卻的近似平衡條件。如果緩慢加熱，則以相反的方式發生這種轉化。
However, when alloys are cooled rapidly, entirely different results may be obtained, because sufficient time is not provided for the normal phase reactions to occur, in such cases, the phase diagram is no longer a useful tool for engineering analysis.然而，當快速冷卻合金時，可能得到完全不同的結果。因為沒有足夠的時間讓正常的狀態反應發生，在這種情況下對工程分析而言狀態圖不再是有用的工具。Hardening
淬火
Hardening is the process of heating a piece of steel to a temperature within or above its critical range and then cooling it rapidly.淬火就是把鋼件加熱到或超過它的臨界溫度范圍，然后使其快速冷卻的過程。
If the carbon content of the steel is known, the proper temperature to which the steel should be heated may be obtained by reference to the iron-iron carbide phase diagram.However, if the composition of the steel is unknown, a little preliminary experimentation may be necessary to determine the range.如果鋼的含碳量已知，鋼件合適的加熱溫度可參考鐵碳合金狀態圖得到。然而當鋼的成分不知道時，則需做一些預備試驗來確定其溫度范圍。
A good procedure to follow is to heat-quench a number of small specimens of the steel at various temperatures and observe the result, either by hardness testing or by microscopic examination.When the correct temperature is obtained, there will be a marked change in hardness and other properties.要遵循的合適步驟是將這種鋼的一些小試件加熱到不同的溫度后淬火，再通過硬度試驗或顯微鏡檢查觀測結果。一旦獲得正確的溫度，硬度和其它性能都將有明顯的變化。
In any heat-treating operation the rate of heating is important.Heat flows from the exterior to the interior of steel at a definite rate.If the steel is heated too fast, the outside becomes hotter than the interior and uniform structure cannot be obtained.在任何熱處理作業中，加熱的速率都是重要的。熱量以一定的速率從鋼的外部傳導到內部。如果鋼被加熱得太快，其外部比內部熱就不能得到均勻的組織結構。
If a piece is irregular in shape, a slow rate is all the more essential to eliminate warping and cracking.The heavier the section, the longer must be the heating time to achieve uniform results.如果工件形狀不規則，為了消除翹曲和開裂最根本的是加熱速率要緩慢。截面越厚，加熱的時間就要越長才能達到均勻的結果。
Even after the correct temperature has been reached, the piece should be held at that temperature for a sufficient period of time to permit its thickest section to attain a uniform temperature.即使加熱到正確的溫度后，工件也應在此溫度下保持足夠時間以讓其最厚截面達到相同溫度。
The hardness obtained from a given treatment depends on the quenching rate, the carbon content, and the work size.In alloy steels the kind and amount of alloying element influences only the hardenability(the ability of the workpiece to be hardened to depths)of the steel and does not affect the hardness except in unhardened or partially hardened steels.通過給定的熱處理所得到的硬度取決于淬火速率、含碳量和工件尺寸。除了非淬硬鋼或部分淬硬鋼外，合金鋼中合金元素的種類及含量僅影響鋼的淬透性(工件被硬化到深層的能力)而不影響硬度。
Steel with low carbon content will not respond appreciably to hardening treatment.As the carbon content in steel increases up to around 0.60%, the possible hardness obtainable also increases.含碳量低的鋼對淬火處理沒有明顯的反應。隨著鋼的含碳量增加到大約0.60%，可能得到的硬度也增加。
Above this point the hardness can be increased only slightly, because steels above the eutectoid point are made up entirely of pearlite and cementite in the annealed state.Pearlite responds best to heat-treating operations;and steel composed mostly of pearlite can be transformed into a hard steel.高于此點，由于超過共析點鋼完全由珠光體和退火狀態的滲碳體組成，硬度增加并不多。珠光體對熱處理作業響應最好；基本由珠光體組成的鋼能轉化成硬質鋼。
As the size of parts to be hardened increases, the surface hardness decreases somewhat even though all other conditions have remained the same.There is a limit to the rate of heat flow through steel.即使所有其它條件保持不變，隨著要淬火的零件尺寸的增加其表面硬度也會有所下降。熱量在鋼中的傳導速率是有限的。
No matter how cool the quenching medium may be, if the heat inside a large piece cannot escape faster than a certain critical rate, there is a definite limit to the inside hardness.However, brine or water quenching is capable of rapidly bringing the surface of the quenched part to its own temperature and maintaining it at or close to this temperature.無論淬火介質怎么冷，如果在大工件中的熱量不能比特定的臨界速率更快散發，那它內部硬度就會受到明確限制。然而鹽水或水淬火能夠將被淬零件的表面迅速冷卻至本身溫度并將其保持或接近此溫度。Under these circumstances there would always be some finite depth of surface hardening regardless of size.This is not true in oil quenching, when the surface temperature may be high during the critical stages of quenching.在這種情況下不管零件尺寸如何，其表面總歸有一定深度被硬化。但油淬情況就不是如此，因為油淬時在淬火臨界階段零件表面的溫度可能仍然很高。Tempering
回火
Steel that has been hardened by rapid quenching is brittle and not suitable for most uses.By tempering or drawing, the hardness and brittleness may be reduced to the desired point for service conditions．
快速淬火硬化的鋼是硬而易碎的，不適合大多數場合使用。通過回火，硬度和脆性可以降低到使用條件所需要的程度。
As these properties are reduced there is also a decrease in tensile strength and an increase in the ductility and toughness of the steel.The operation consists of reheating quench-hardened steel to some temperature below the critical range followed by any rate of cooling.隨著這些性能的降低，拉伸強度也降低而鋼的延展性和韌性則會提高。回火作業包括將淬硬鋼重新加熱到低于臨界范圍的某一溫度然后以任意速率冷卻。
Although this process softens steel, it differs considerably from annealing in that the process lends itself to close control of the physical properties and in most cases does not soften the steel to the extent that annealing would.The final structure obtained from tempering a fully hardened steel is called tempered martensite.雖然這過程使鋼軟化，但它與退火是大不相同的，因為回火適合于嚴格控制物理性能并在大多數情況下不會把鋼軟化到退火那種程度。回火完全淬硬鋼得到的最終組織結構被稱為回火馬氏體。
Tempering is possible because of the instability of the martensite, the principal constituent of hardened steel.Low-temperature draws, from 300℉ to 400℉(150℃~205℃), do not cause much decrease in hardness and are used principally to relieve internal strains.由于馬氏體這一淬硬鋼主要成分的不穩定性，使得回火成為可能。低溫回火，300℉到400℉(150℃~205℃)，不會引起硬度下降很多，主要用于減少內部應變。
As the tempering temperatures are increased, the breakdown of the martensite takes place at a faster rate, and at about 600℉(315℃)the change to a structure called tempered martensite is very rapid.The tempering operation may be described as one of precipitation and agglomeration or coalescence of cementite.隨著回火溫度的提高，馬氏體以較快的速率分解，并在大約600℉(315℃)迅速轉變為被稱為回火馬氏體的結構。回火作業可以描述為滲碳體析出和凝聚或聚結的過程。
A substantial precipitation of cementite begins at 600℉(315℃), which produces a decrease in hardness.Increasing the temperature causes coalescence of the carbides with continued decrease in hardness.滲碳體的大量析出開始于600℉(315℃)，這使硬度下降。溫度的上升會使碳化物聚結而硬度繼續降低。
In the process of tempering, some consideration should be given to time as well as to temperature.Although most of the softening action occurs in the first few minutes after the temperature is reached, there is some additional reduction in hardness if the temperature is maintained for a prolonged time.在回火過程中，不但要考慮溫度而且要考慮時間。雖然大多數軟化作用發生在達到所需溫度后的最初幾分鐘，但如果此溫度維持一段延長時間，仍會有些額外的硬度下降。
Usual practice is to heat the steel to the desired temperature and hold it there only long enough to have it uniformly heated.通常的做法是將鋼加熱到所需溫度并且僅保溫到正好使其均勻受熱。
Two special processes using interrupted quenching are a form of tempering.In both, the hardened steel is quenched in a salt bath held at a selected lower temperature before being allowed to cool.These processes, known as austempering and martempering, result in products having certain desirable physical properties.兩種采用中斷淬火的特殊工藝也是回火的形式。這兩種工藝中，淬硬鋼在其被允許冷卻前先在一選定的較低溫度鹽浴淬火。這兩種分別被稱為奧氏體回火和馬氏體回火的工藝，能使產品具有特定所需的物理性能。
Annealing
退火
The primary purpose of annealing is to soften hard steel so that it may be machined or cold worked.退火的主要目的是使堅硬的鋼軟化以便機加工或冷作。
This is usually accomplished by heating the steel too slightly above the critical temperature, holding it there until the temperature of the piece is uniform throughout, and then cooling at a slowly controlled rate so that the temperature of the surface and that of the center of the piece are approximately the same.通常是非常緩慢地將鋼加熱到臨界溫度以上，并將其在此溫度下保持到工件全部均勻受熱，然后以受控的速率慢慢地冷卻，這樣使得工件表面和內部的溫度近似相同。
This process is known as full annealing because it wipes out all trace of previous structure, refines the crystalline structure, and softens the metal.Annealing also relieves internal stresses previously set up in the metal.這過程被稱為完全退火，因為它去除了以前組織結構的所有痕跡、細化晶粒并軟化金屬。退火也釋放了先前在金屬中的內應力。
The temperature to which a given steel should be heated in annealing depends on its composition;for carbon steels it can be obtained readily from the partial iron-iron carbide equilibrium diagram.When the annealing temperature has been reached, the steel should be held there until it is uniform throughout.給定的鋼其退火溫度取決于它的成分；對碳鋼而言可容易地從局部的鐵碳合金平衡圖得到。達到退火溫度后，鋼應當保持在此溫度等到全部均勻受熱。
This usually takes about 45min for each inch(25mm)of thickness of the largest section.For maximum softness and ductility the cooling rate should be very slow, such as allowing the parts to cool down with the furnace.The higher the carbon content, the slower this rate must be.加熱時間一般以工件的最大截面厚度計每英寸(25mm)大約需45min。為了得到最大柔軟性和延展性冷卻速率應該很慢，比如讓零件與爐子一起冷下來。含碳量越高，冷卻的速率必須越慢。
The heating rate should be consistent with the size and uniformity of sections, so that the entire part is brought up to temperature as uniformly as possible.加熱的速率也應與截面的尺寸及均勻程度相協調，這樣才能使整個零件盡可能均勻地加熱。Normalizing and Spheroidizing正火和球化
The process of normalizing consists of heating the steel about 50℉ to 100℉
(10℃~40℃)above the upper critical range and cooling in still air to room temperature.正火處理包括先將鋼加熱到高于上臨界區50℉到100℉(10℃~40℃)然后在靜止的空氣中冷卻到室溫。
This process is principally used with low-and medium-carbon steels as well as alloy steels to make the grain structure more uniform, to relieve internal stresses, or to achieve desired results in physical properties.Most commercial steels are normalized after being rolled or cast.退火主要用于低碳鋼、中碳鋼及合金鋼，使晶粒結構更均勻、釋放內應力或獲得所需的物理特性。大多數商業鋼材在軋制或鑄造后都要退火。
Spheroidizing is the process of producing a structure in which the cementite is in a spheroidal distribution.If steel is heated slowly to a temperature just below the critical range and held there for a prolonged period of time, this structure will be obtained.球化是使滲碳體產生成類似球狀分布結構的工藝。如果把鋼緩慢加熱到恰好低于臨界溫度并且保持較長一段時間，就能得到這種組織結構。
The globular structure obtained gives improved machinability to the steel.This treatment is particularly useful for hypereutectoid steels that must be machined.所獲得的球狀結構改善了鋼的可切削性。此處理方法對必須機加工的過共析鋼特別有用。Surface Hardening表面硬化 Carburizing
The oldest known method of producing a hard surface on steel is case hardening or carburizing.Iron at temperatures close to and above its critical temperature has an affinity for carbon.滲碳
最早的硬化鋼表面的方法是表面淬火或滲碳。鐵在靠近并高于其臨界溫度時對碳具有親合力。The carbon is absorbed into the metal to form a solid solution with iron and converts the outer surface into high-carbon steel.The carbon is gradually diffused to the interior of the part.The depth of the case depends on the time and temperature of the treatment.碳被吸收進金屬與鐵形成固溶體使外表面轉變成高碳鋼。碳逐漸擴散到零件內部。滲碳層的深度取決于熱處理的時間和溫度。
Pack carburizing consists of placing the parts to be treated in a closed container with some carbonaceous material such as charcoal or coke.It is a long process and used to produce fairly thick cases of from 0.03 to 0.16 in.(0.76~4.06mm)in depth.固體滲碳的方法是將要處理的零件與木炭或焦炭這些含碳的材料一起放入密閉容器。這是一個較長的過程，用于產生深度為0.03到0.16 英寸(0.76~4.06mm)這么厚的硬化層。
Steel for carburizing is usually a low-carbon steel of about 0.15% carbon that would not in itself responds appreciably to heat treatment.In the course of the process the outer layer is converted into high-carbon steel with a content ranging from 0.9% to 1.2% carbon.用于滲碳的一般是含碳量約為0.15%、本身不太適合熱處理的低碳鋼。在處理過程中外層轉化為含碳量從0.9%到1.2%的高碳鋼。
A steel with varying carbon content and, consequently, different critical temperatures requires a special heat treatment.含碳量變化的鋼具有不同的臨界溫度，因此需要特殊的熱處理。
Because there is some grain growth in the steel during the prolonged carburizing treatment, the work should be heated to the critical temperature of the core and then cooled, thus refining the core structure.The steel should then be reheated to a point above the transformation range of the case and quenched to produce a hard, fine structure.由于在較長的滲碳過程中鋼內部會有些晶粒生長，所以工件應該加熱到核心部分的臨界溫度再冷卻以細化核心部分的組織結構。然后重新加熱到高于外層轉變溫度再淬火以生成堅硬、細致的組織結構。
The lower heat-treating temperature of the case results from the fact that hypereutectoid steels are normally austenitized for hardening just above the lower critical point.A third tempering treatment may be used to reduce strains.由于恰好高于低臨界溫度通常使過共析鋼奧氏體化而硬化，所以對外層采用較低的熱處理溫度。第三次回火處理可用于減少應變。Carbonitriding
Carbonitriding, sometimes known as dry cyaniding or nicarbing, is a case-hardening process in which the steel is held at a temperature above the critical range in a gaseous atmosphere from which it absorbs carbon and nitrogen.碳氮共滲
碳氮共滲，有時也稱為干法氰化或滲碳氮化，是一種表面硬化工藝。通過把鋼放在高于臨界溫度的氣體中，讓它吸收碳和氮。
Any carbon-rich gas with ammonia can be used.The wear-resistant case produced ranges from 0.003 to 0.030 inch(0.08~ 0.76mm)in thickness.An advantage of carbonitriding is that the hardenability of the case is significantly increased when nitrogen is added, permitting the use of low-cost steels.可以使用任何富碳氣體加氨氣，能生成厚度從0.003到0.030英寸(0.08~ 0.76mm)的耐磨外層。碳氮共滲的優點之一是加入氮后外層的淬透性極大增加，為使用低價鋼提供條件。Cyaniding
Cyaniding, or liquid carbonitriding as it is sometimes called, is also a process that combines the absorption of carbon and nitrogen to obtain surface hardness in low-carbon steels that do not respond to ordinary heat treatment.氰化
氰化，有時稱為液體碳氮共滲，也是一種結合了吸收碳和氮來獲得表面硬度的工藝，它主要用于不適合通常熱處理的低碳鋼。
The part to be case hardened is immersed in a bath of fused sodium cyanide salts at a temperature slightly above the Ac1 range, the duration of soaking depending on the depth of the case.The part is then quenched in water or oil to obtain a hard surface.需表面硬化的零件浸沒在略高于Ac1溫度熔化的氰化鈉鹽溶液中，浸泡的持續時間取決于硬化層的深度。然后將零件在水或油中淬火。
Case depths of 0.005 to 0.015in.(0.13~0.38mm)may be readily obtained by this process.Cyaniding is used principally for the treatment of small parts.通過這樣處理可以容易地獲得0.005到0.015英寸(0.13~0.38mm)的硬化深度。氰化主要用于處理小零件。Nitriding
Nitriding is somewhat similar to ordinary case hardening, but it uses a different material and treatment to create the hard surface constituents.滲氮
滲氮有些類似普通表面硬化，但它采用不同的材料和處理方法來產生堅硬表面成分。
In this process the metal is heated to a temperature of around 950℉(510℃)and held there for a period of time in contact with ammonia gas.Nitrogen from the gas is introduced into the steel, forming very hard nitrides that are finely dispersed through the surface metal.這種工藝中金屬加熱到約950℉(510℃)，然后與氨氣接觸一段時間。氨氣中的氮進入鋼內，形成細微分布于金屬表面又十分堅固的氮化物。
Nitrogen has greater hardening ability with certain elements than with others, hence, special nitriding alloy steels have been developed.氮與某些元素的硬化能力比其它元素大，因此開發了專用的滲氮合金鋼。
Aluminum in the range of 1% to 1.5% has proved to be especially suitable in steel, in that it combines with the gas to form a very stable and hard constituent.The temperature of heating ranges from 925℉ to 1,050℉(495℃~565℃).在鋼中含鋁1%到1.5%被證明特別合適，它能與氨氣結合形成很穩定堅固的成分。其加熱溫度范圍為925℉到1,050℉(495℃~565℃)。
Liquid nitriding utilizes molten cyanide salts and, as in gas nitriding, the temperature is held below the transformation range.Liquid nitriding adds more nitrogen and less carbon than either cyaniding or carburizing in cyanide baths.液體滲氮利用熔化的氰化物鹽，就像氣體滲氮，溫度保持在低于轉化范圍內。液體滲氮時在氰化物溶液中加入比氰化及滲碳都較多的氮和較少的碳。
Case thickness of 0.001 to 0.012in.(0.03~0.30mm)is obtained, whereas for gas nitriding the case may be as thick as 0.025 in.(0.64mm).In general the uses of the two-nitriding processes are similar.液體滲氮可以獲得厚度為0.001到0.012英寸(0.03~0.30mm)的硬化層，然而氣體滲氮則能獲得厚0.025英寸(0.64mm)的硬化層。一般而言兩種滲氮方法的用途是類似的。
Nitriding develops extreme hardness in the surface of steel.This hardness ranges from 900 to 1,100 Brinell, which is considerably higher than that obtained by ordinary case hardening.滲氮在鋼表面獲得遠遠超出正常標準的硬度。其硬度范圍為900到1,100布氏硬度，這遠高于普通表面硬化所獲得的硬度。
Nitriding steels, by virtue of their alloying content, are stronger than ordinary steels and respond readily to heat treatment.It is recommended that these steels be machined and heat-treated before nitriding, because there is no scale or further work necessary after this process.由于滲氮鋼的合金比例，它們比普通鋼更強，也容易熱處理。建議對這種鋼在滲氮前先機加工和熱處理，因為滲氮后沒有剝落并不需要更多的加工。
Fortunately, the interior structure and properties are not affected appreciably by the nitriding treatment and, because no quenching is necessary, there is little tendency to warp, develop cracks, or change condition in any way.The surface effectively resists corrosive action of water, saltwater spray, alkalies, crude oil, and natural gas.值得慶幸的是由于滲氮處理一點都不影響內部結構和性能，也無需淬火，所以幾乎沒有任何產生翹曲、裂縫及變化條件的趨勢。這種表面能有效地抵御水、鹽霧、堿、原油和天然氣的腐蝕反應。
Unit3
Casting is a manufacturing process in which molten metal is poured or injected and allowed to solidify in a suitably shaped mold cavity.During or after cooling, the cast part is removed from the mold and then processed for delivery.鑄造是一種將熔化的金屬倒入或注入合適的鑄模腔并且在其中固化的制造工藝。在冷卻期間或冷卻后，把鑄件從鑄模中取出，然后進行交付。
Casting processes and cast-material technologies vary from simple to highly complex.Material and process selection depends on the part’s complexity and function, the product’s quality specifications, and the projected cost level.鑄造工藝和鑄造材料技術從簡單到高度復雜變化很大。材料和工藝的選擇取決于零件的復雜性和功能、產品的質量要求以及成本預算水平。
Castings are parts that are made close to their final dimensions by a casting process.With a history dating back 6,000 years, the various casting processes are in a state of continuous refinement and evolution as technological advances are being made.通過鑄造加工，鑄件可以做成很接近它們的最終尺寸。回溯6,000年歷史，各種各樣的鑄造工藝就如同科技進步一樣處于一個不斷改進和發展的狀態。Sand Casting
砂型鑄造
Sand casting is used to make large parts(typically iron, but also bronze, brass, aluminum).Molten metal is poured into a mold cavity formed out of sand(natural or synthetic).砂型鑄造用于制造大型零件(具有代表性是鐵，除此之外還有青銅、黃銅和鋁)。將熔化的金屬倒入由型砂(天然的或人造的)做成鑄模腔。
The processes of sand casting are discussed in this section, including patterns, sprues and runners, design considerations, and casting allowance.本節討論砂型鑄造工藝，包括型模、澆注口、澆道、設計考慮因素及鑄造余量。
The cavity in the sand is formed by using a pattern(an approximate duplicate of the real part), which are typically made out of wood, sometimes metal.The cavity is contained in an aggregate housed in a box called the flask.砂型里的型腔是采用型模(真實零件的近似復制品)構成的，型模一般為木制，有時也用金屬制造。型腔整個包含在一個被放入稱為砂箱的箱子里的組合體內。
Core is a sand shape inserted into the mold to produce the internal features of the part such as holes or internal passages.Cores are placed in the cavity to form holes of the desired shapes.Core print is the region added to the pattern, core, or mold that is used to locate and support the core within the mold.砂芯是插入鑄模的砂型，用于生成諸如孔或內通道之類的內部特征。砂芯安放在型腔里形成所需形狀的孔洞。砂芯座是加在型模、砂芯或鑄模上的特定區域，用來在鑄模內部定位和支撐砂芯。
A riser is an extra void created in the mold to contain excessive molten material.The purpose of this is to feed the molten metal to the mold cavity as the molten metal solidifies and shrinks, and thereby prevents voids in the main casting.冒口是在鑄模內部增加的額外空間，用于容納過多的熔化金屬。其目的是當熔化金屬凝固和收縮時往型腔里補充熔化金屬，從而防止在主鑄件中產生孔隙。
In a two-part mold, which is typical of sand castings, the upper half, including the top half of the pattern, flask, and core is called cope and the lower half is called drag, as shown in Fig.3.1.The parting line or the parting surface is line or surface that separates the cope and drag.在典型砂型鑄造的兩箱鑄模中，上半部分(包括型模頂半部、砂箱和砂芯)稱為上型箱，下半部分稱為下型箱，見圖3.1所示。分型線或分型面是分離上下型箱的線或面。
The drag is first filled partially with sand, and the core print, the cores, and the gating system are placed near the parting line.The cope is then assembled to the drag, and the sand is poured on the cope half, covering the pattern, core and the gating system.首先往下型箱里部分地填入型砂和砂芯座、砂芯，并在靠近分型線處放置澆注系統。然后將上型箱與下型箱裝配在一起，再把型砂倒入上型箱蓋住型模、砂芯和澆注系統。
The sand is compacted by vibration and mechanical means.Next, the cope is removed from the drag, and the pattern is carefully removed.The object is to remove the pattern without breaking the mold cavity.型砂通過振動和機械方法壓實。然后從下型箱上撤掉上型箱，小心翼翼地取出型模。其目的是取出型模而不破壞型腔。
This is facilitated by designing a draft, a slight angular offset from the vertical to the vertical surfaces of the pattern.This is usually a minimum of 1.5mm(0.060in.), whichever is greater.The rougher the surface of the pattern, the more the draft to be provided.通過設計拔模斜度—型模垂直相交表面的微小角度偏移量—來使取出型模變得容易。拔模斜度最小一般為1.5mm(0.060in.)，只能比此大。型模表面越粗糙，則拔模斜度應越大。
The molten material is poured into the pouring cup, which is part of the gating system that supplies the molten material to the mold cavity.熔化的金屬從澆注杯注入型腔，澆注杯是澆注系統向型腔提供熔化金屬的部分。
The vertical part of the gating system connected to the pouring cup is the sprue, and the horizontal portion is called the runners and finally to the multiple points where it is introduced to the mold cavity called the gates.將澆注系統的垂直部分與澆注杯連接的是澆注口，澆注系統的水平部分稱為澆道，最后到多點把熔化金屬導入型腔的稱為閘道。
Additionally there are extensions to the gating system called vents that provide the path for the built-up gases and the displaced air to vent to the atmosphere.除此之外，還有稱為排放口的澆注系統延長段，它為合成氣體和置換空氣排放到大氣提供通道。
The cavity is usually made oversize to allow for the metal contraction as it cools down to room temperature.This is achieved by making the pattern oversize.To account for shrinking, the pattern must be made oversize by these factors on the average.These are linear factors and apply in each direction.型腔通常大于所需尺寸以允許在金屬冷卻到室溫時收縮。這通過把型模做得大于所需尺寸來達到。為解決收縮效應，一般而言型模做得比所需尺寸大，必須考慮線性因素并作用于各個方向。
These shrinkage allowances are only approximate, because the exact allowance is determined by the shape and size of the casting.In addition, different parts of the casting might require different shrinkage allowances.收縮余量僅僅是近似的，因為準確的余量是由鑄件的形狀和尺寸決定的。另外，鑄件的不同部分也可能需要不同的收縮余量。
Sand castings generally have a rough surface sometimes with surface impurities, and surface variations.A machining(finish)allowance is made for this type of defect.砂型鑄件一般表面粗糙，有時還帶有表面雜質和表面變異。對這類缺陷采用機加工(最后一道工序)的余量。
In general, typical stages of sand casting operation include(as shown in Fig.3.2): 1.Patterns are made.These will be the shape used to form the cavity in the sand.一般而言，砂型鑄造作業的典型階段包括(如圖3.2所示)： 1.制作型模。做成用于在型砂中形成型腔的形狀。
2.Cores may also be made at this time.These cores are made of bonded sand that will be broken out of the cast part after it is complete.3.Sand is mulled(mixed)thoroughly with additives such as bentonite to increase bonding and overall strength.2.同時還要制作砂芯。這些砂芯用粘結砂做成，等鑄件完成后將被打碎取出。3.型砂與膨潤土之類的添加劑充分地混合以增強連接及整體強度。
4.Sand is formed about the patterns, and gates, runners, risers, vents and pouring cups are added as needed.A compaction stage is typically used to ensure good coverage and solid molds.4.型砂在型模周圍成形，并根據需要安放閘道、澆道、冒口、排放口和澆注杯等。通常要采取壓緊步驟來保證良好的覆蓋和堅固的鑄型。
Cores may also be added to make concave or internal features for the cast part.Alignment pins may also be used for mating the molds later.Chills may be added to cool large masses faster.安放砂芯來制成鑄件的凹形結構或內部特征。為了以后鑄模匹配還要用到定位銷。對大質量鑄件可能需要加入冷卻物來使其較快冷卻。
5.The patterns are removed, and the molds may be put through a baking stage to increase strength.6.Mold halves are mated and prepared for pouring metal.5.取走型模，將鑄模烘焙以增加強度。6.匹配上下鑄模，做好澆鑄金屬的準備。
7.Metal is preheated in a furnace or crucible until is above the liquidus temperature in a suitable range(we don’t want the metal solidifying before the pour is complete).The exact temperature may be closely controlled depending upon the application.7.金屬在熔爐或坩堝中預熱到高于液化溫度的一個合適范圍內(不希望金屬在澆鑄完成前凝固)。確切的溫度要根據應用場合嚴格控制。
Degassing, and other treatment processes may be done at this time, such as removal of impurities(i.e.slag).Some portion of this metal may be remelted scrap from previously cast parts—10% is reasonable.在此期間還要進行排氣和其它處理步驟，例如去除雜質(即熔渣)。可以加入一定量原先是這種金屬鑄件的廢料再融化—10%是適當的。
8.The metal is poured slowly, but continuously into the mold until the mold is full.9.As the molten metal cools(minutes to days), the metal will shrink and the volume will decrease.During this time molten metal may backflow from the molten risers to feed the part and maintain the same shape.8.將金屬緩慢而連續地注滿型模。
9.隨著熔化金屬的冷卻(幾分鐘到幾天)，金屬收縮體積減小。在此期間熔化金屬可能從冒口回流供給零件以保持其形狀不變。
10.Once the part starts to solidify small dendrites of solid material form in the part.During this time metal properties are being determined, and internal stresses are being generated.If a part is allowed to cool slowly enough at a constant rate then the final part will be relatively homogenous and stress free.10.在零件開始凝固其內部形成固態金屬的小型樹枝狀結晶期間金屬性能被確定，同時也產生了內應力。如果零件以恒定速率冷卻得足夠緩慢，最終零件將相對均質并釋放內應力。
11.Once the part has completely solidified below the eutectic point it may be removed with no concern for final metal properties.At this point the sand is simply broken up, and the part removed.At this point the surface will have a quantity of sand adhering to the surface, and solid cores inside.11.一旦零件在共析點以下完全凝固，可以不考慮金屬的最后性能而將其取出。這時可以簡單地打碎砂型并取出零件，但零件表面會有大量型砂粘附著，內部還有實心的砂芯。
12.A bulk of the remaining sand and cores can be removed by mechanically striking the part.Other options are to use a vibrating table, sand/shot blaster, hand labor, etc.12.大量的剩余型砂和砂芯要通過機械敲擊零件來去除。其它的選擇還有采用振動臺、噴砂/噴丸機、手工作業等等。
13.The final part is cut off the runner gate system, and is near final shape using cutters, torches, etc.Grinding operations are used to remove any remaining bulk.14.The part is taken down to final shape using machining operations.And cleaning operations may be used to remove oxides, etc.13.最后零件要用刀具、噴槍等切掉澆道閘道系統，這樣就接近最終形狀了。再用磨削作業去除多余的部分。
14.通過機加工將零件切削到最終形狀。可能還要用清洗作業去除氧化物等。Investment casting熔模鑄造
Investment casting is also known as the lost wax process.This process is one of the oldest manufacturing processes.The Egyptians used it in the time of the Pharaohs to make gold jewelry(hence the name Investment)some 5,000 years ago.熔模鑄造也稱為失蠟加工。這是最古老的制造工藝之一。大約在5,000年前的法老王時代，埃及人就用它制造黃金飾品(因此而得名投資)。
Intricate shapes can be made with high accuracy.In addition, metals that are hard to machine or fabricate are good candidates for this process.It can be used to make parts that cannot be produced by normal manufacturing techniques, such as turbine blades that have complex shapes, or airplane parts that have to withstand high temperatures.復雜的形狀能被高精度地制造。另外較難機加工或制作的金屬都能用此工藝。它還能用于生產一般制造技術無法生產的零件，例如有復雜形狀的渦輪葉片或必須耐得住高溫的飛機零件。
The mold is made by making a pattern using wax or some other material that can be melted away.This wax pattern is dipped in refractory slurry, which coats the wax pattern and forms a skin.This is dried and the process of dipping in the slurry and drying is repeated until a robust thickness is achieved.制作鑄型的型模采用石蠟或其它一些能被融化掉的材料做成。石蠟型模浸泡在耐熱漿里，讓它覆蓋型模并形成外殼，然后使其變干。重復這個浸泡、變干的過程直至獲得足夠的厚度。
After this, the entire pattern is placed in an oven and the wax is melted away.This leads to a mold that can be filled with the molten metal.Because the mold is formed around a one-piece pattern(which does not have to be pulled out from the mold as in a traditional sand casting process), very intricate parts and undercuts can be made.完成后把整個型模放在烤箱里融化石蠟。這樣就做成了能填充熔化金屬的鑄型。由于這種鑄型是環繞整塊型模形成的(無需像傳統的砂型鑄造工藝那樣拔模)，能制作十分復雜的零件和浮雕。
The wax pattern itself is made by duplicating using a stereo lithography or similar model—which has been fabricated using a computer solid model master.石蠟型模本身能用立體制版或類似的模型復制—這可以采用計算機立體模型原版制作。
The materials used for the slurry are a mixture of plaster, a binder and powdered silica, a refractory, for low temperature melts.For higher temperature melts, sillimanite or alumina-silicate is used as a refractory, and silica is used as a binder.對較低熔化溫度而言，用于耐熱漿的材料是石膏作粘合劑和用粉末狀硅石作耐溫材料的混合物。對較高熔化溫度而言，則采用硅線石或氧化鋁硅酸鹽作耐溫材料、無水硅酸作粘合劑。
Depending on the fineness of the finish desired additional coatings of sillimanite and ethyl silicate may be applied.The mold thus produced can be used directly for light castings, or be reinforced by placing it in a larger container and reinforcing it more slurry.根據最后所需光潔度也可采用硅線石和乙烷基硅酸鹽。這樣生成的鑄模可直接用于薄壁鑄件或通過將其放在較大容器內用更多耐熱漿加強。
Just before the pour, the mold is pre-heated to about 1,000℃(1,832℉)to remove any residues of wax, harden the binder.The pour in the pre-heated mold also ensures that the mold will fill completely.在正要澆鑄之前，將型模預熱到約1,000℃(1,832℉)以去除剩余石蠟、硬化粘合劑。在預熱的型模中澆鑄也能保證型模完全充滿。
Pouring can be done using gravity, pressure or vacuum conditions.Attention must be paid to mold permeability when using pressure, to allow the air to escape as the pour is done.澆鑄可采用重力、壓力或真空條件來實現。當使用壓力時必須注意滲透性，以便在澆鑄的同時讓空氣逸出。
Tolerances of 0.5% of length are routinely possible, and as low as 0.15% is possible for small dimensions.Castings can weigh from a few grams to 35kg(0.1oz to 80lb), although the normal size ranges from 200g to about 8kg(7oz to 15 lb).Normal minimum wall thicknesses are about 1mm to about 0.5mm(0.040~ 0.020 in.)for alloys that can be cast easily.一般公差可能為長度的0.5%，小尺寸可能低到0.15%。雖然通常尺寸的鑄件重量范圍為200g到約8kg(7oz到15lb)，但實際可從幾克到35kg(0.1oz to 80lb)。對容易鑄造的合金而言，通常壁厚約為1mm到0.5mm(0.040~ 0.020 in.)。
The types of materials that can be cast are aluminum alloys, bronzes, tool steels, stainless steels, stellite, hastelloys, and precious metals.Parts made with investment castings often do not require any further machining, because of the close tolerances that can be achieved.可以用于鑄造的材料類型有：鋁合金、青銅、工具鋼、不銹鋼、鎢鉻鈷合金、鎳基合金和貴金屬。采用熔模鑄造的零件常常不需要進一步加工，因為熔模鑄造能達到精密的公差。Centrifugal Casting離心鑄造
Centrifugal casting(Fig.3.3)as a category includes centrifugal casting, semi-centrifugal casting and centrifuging.In centrifugal casting, a permanent mold is rotated about its axis at high speeds(300 to 3,000rpm)as the molten metal is poured.離心鑄造(圖3.3)作為一個種類包括了離心鑄造、半離心鑄造和離心法鑄造。離心鑄造中，永久性的型模在熔化金屬澆鑄時以較高速度(300到3,000rpm)繞其軸線旋轉。
The molten metal is centrifugally thrown towards the inside mold wall, where it solidifies after cooling.The casting is usually a fine grain casting with a very fine-grained outer diameter, which is resistant to atmospheric corrosion, a typical situation with pipes.The inside diameter has more impurities and inclusions, which can be machined away.受離心力作用熔化金屬被拋向型模的內壁，在那里冷卻后固化。這種鑄件通常為外徑處晶粒非常細小的細晶粒鑄件，能耐大氣腐蝕，典型的情況是管子。內徑處則有較多的雜質和內含物，但可用機加工去除。
Only cylindrical shapes can be produced with this process.Size limits are up to 3m(10feet)diameter and 15m(50 feet)length.Wall thickness can be 2.5mm to 125mm(0.1~5.0in.).The tolerances that can be held on the OD can be as good as 2.5mm(0.1in.)and on the ID can be 3.8mm(0.15in.).The surface finish ranges from 2.5mm to 12.5mm(0.1~0.5in.)rms(root-mean-square).只有圓柱形才能用此工藝生產。尺寸限制為直徑大到3m(10feet)、長度大到15m(50feet)。壁厚為2.5mm到125mm(0.1~5.0in.)。外徑公差保持在2.5mm(0.1in.)以內，內徑公差保持在3.8mm(0.15in.)以內。表面粗糙度的有效值(均方根)范圍為2.5mm到12.5mm(0.1~0.5in.)。
Typical materials that can be cast with this process are iron, steel, stainless steels, and alloys of aluminum, copper and nickel.Two materials can be cast by introducing a second material during the process.Typical parts made by this process are pipes, boilers, pressure vessels, flywheels, cylinder liners and other parts that are axis-symmetric.可用此工藝鑄造的典型材料有：鐵、鋼、不銹鋼以及鋁、銅和鎳的合金。通過在生產過程中加入第二種材料能進行兩種材料鑄造。采用這種工藝制造的典型零件有：管子、鍋爐、壓力容器、飛輪、汽缸襯墊和其它軸對稱零件。
Semi-centrifugal casting.The molds used can be permanent or expendable, can be stacked as necessary.The rotational speeds are lower than those used in centrifugal casting.半離心鑄造：型模可以是永久性的或是消耗性的，可根據需要疊加。它的旋轉速度比離心鑄造低。The center axis of the part has inclusion defects as well as porosity and thus is suitable only for parts where this can be machined away.This process is used for making wheels, nozzles and similar parts where the axis of the part is removed by subsequent machining.零件的中心軸附近存在缺陷和孔隙，因此僅適用于能將這些機加工去除的零件。這種工藝被用于制造車輪、管嘴及類似的隨后可用機加工去除中心軸部分的零件。
Centrifuging.Centrifuging is used for forcing metal from a central axis of the equipment into individual mold cavities that are placed on the circumference.This provides a means of increasing the filling pressure within each mold and allows for reproduction of intricate details.This method is often used for the pouring of investment casting pattern.離心法鑄造：離心法鑄造用于迫使金屬從設備的中心軸進入分布在圓周上的單獨型腔。它為每個型腔提供了一種增加填充壓力方法并允許再現復雜細節。這種方法常用于澆鑄熔模鑄型。
Full-mold casting is a technique similar to investment casting, but instead of wax as the expendable material, polystyrene foam is used as the pattern.The foam pattern is coated with a refractory material.The pattern is encased in a one-piece sand mold.As the metal is poured, the foam vaporizes, and the metal takes its place.實型鑄造是與熔模鑄造類似的技術，但它用做型模的消耗材料是聚苯乙烯泡沫而不是石蠟。泡沫型模用難熔材料覆蓋。型模裝入整體砂模中。當金屬澆入時，泡沫材料蒸發，金屬取代其位置。This can make complex shaped castings without any draft or flash.However, the pattern cost can be high due to the expendable nature of the pattern.Minimum wall thicknesses are 2.5mm, tolerances can be held to 0.3% on dimensions.Surface finish can be held from 2.5μm to 25μm(0.1μin.to 1.0μin.)rms(root-mean-square).它能制造沒有拔模斜度和縫脊的復雜形狀鑄件。然而由于型模的消耗特性，型模成本可能較高。最小壁厚為2.5mm，公差能保持在尺寸的0.3% 之內。表面粗糙度的有效值(均方根)能保持在2.5μm至25μm(0.1μin.至1.0μin.)之間。
Size limits are from 400g(1lb)to several tons.No draft allowance is required.Typical materials that can be cast with this process are aluminum, iron, steel, nickel alloys, copper alloys.Types of parts that can be made using these processes are pump housings, manifolds, and auto brake components.重量限制從400g(1lb)到數噸。無需留拔模余量。這種工藝所用的典型材料有：鋁、鐵、鋼、鎳合金、銅合金。可以采用這些工藝制造的零件類型有泵殼、復式接頭和自動剎車部件。
Unit4 Introduction
引言
Forging is an important hot-forming process.It is used in producing components of all shapes and sizes, from quite small items to large units weighing several tons.鍛造是一種重要的熱成型工藝。它能用于生產各種形狀和尺寸、從很小到重量數噸的零件。
Forging is the process by which metal is heated and is shaped by plastic deformation by suitably applying compressive force.Usually the compressive force is in the form of hammer blows using a power hammer or a press, as shown in Fig.4.1.在鍛造過程中先將金屬加熱，然后施加合適的壓力使其塑性變形。通常壓力都是以由如圖4.1所示的動力錘或壓力機提供的錘擊形式出現。
Hand forging tools comprise variously shaped hammers.The base on which the work is supported during forging is the anvil.手工鍛造工具包括各種不同形狀的錘子。在鍛造中用于支撐工件的基礎是鐵砧。
For the semimechanized forging of small to medium-sized components, forging hammers powered by various means are employed.The feature common to all of them is that, like the hand forging hammer, they utilize the energy of a falling weight to develop the pressure needed for shaping the metal.對小到中等尺寸零件的半機械化鍛造而言，鍛錘可采用多種動力。就其一般特性而言，都象手工鍛錘一樣，它們均利用落重能量來產生金屬成型所需的壓力。
Larger components are forged by means of forging presses operated by steam or compressed air or by hydraulic or electric power.Largely automatic forging machines are used for the quantity production of engineering parts.鍛造大零件則要用到蒸汽、壓縮空氣、液力或電力驅動的鍛壓機。大型的自動化鍛機用于工程零件的批量生產。
A distinction may be made between open-die forging, usually in the form of hammer forging, and closed-die forging.In hammer forging, the component is shaped by hammer blows aided by relatively simple tools.These may include open dies i.e., dies that do not completely enclose the metal to be shaped.錘鍛中常用的開式模鍛與閉式模鍛是有區別的。在錘鍛中零件通過錘擊輔之以相對簡單的工具成型。其中包括開式鍛模，就是不完全封閉被成型金屬的模具。
One of the basic operations of hammer forging is the elongation of a piece of metal by stretching with hammer blows, causing it to become thinner and longer.In hand forging the work-piece is usually turned 90°after each blow, in order to forge it thoroughly and prevent its lateral expansion.錘鍛的基本操作之一就是通過錘擊使金屬伸長，促成其變細變長。手工鍛造時一般在每次錘擊后都轉過90°以充分鍛打工件并防止橫向膨脹。
The opposite of elongation is upsetting, which produces compressive shortening.For example, the diameter of a bar can be increased by heating and hammering axially.與伸長相反的是鐓粗，即產生壓縮性縮短。例如，棒料的直徑可以通過加熱和軸向錘擊而增大。
More important is closed-die forging, very widely used for mass production in industry, in which the metal is shaped by pressing between a pair of forging dies.The upper die is usually attached to the ram of a forging press or a forging hammer, while the lower die is stationary.更重要的是閉式模鍛，在工業上廣泛用于規模生產。閉式模鍛中金屬在一對鍛模之間擠壓成型。頂模通常放在鍛壓機的撞頭或鍛錘上，而底模則是固定的。
Together they form a closed die.Closed-die forging can produce components of greater complexity and accuracy, with a better surface finish than the more traditional methods not using closed dies.The dies are made of special heat-resistant and wear-resistant tool steels.兩者合在一起形成閉式鍛模。閉式模鍛能生產高度復雜和精確的零件，而且表面光潔度要比不用閉式鍛模的更傳統方法好。閉式鍛模采用特殊的耐熱、耐磨工具鋼制成。
A piece of hot metal sufficient to slightly overfill the die shape is placed in the bottom die, and the top die is forced against it, so that the metal takes the internal shape of the die.將一塊大小足以充填模腔并能稍有溢出的加熱金屬放入底模，并將頂模加壓合攏，這塊金屬便獲得該模腔的形狀。Closed-die forging is used for the rapid production of large numbers of fairly small parts and also for very large components.For the latter, e.g., modern jet-aircraft components, giant hydraulically operated presses are used, which can develop forces of 50,000 tons and more.閉式模鍛用于相當小的零件大批量快速生產，也可用于很大的零件。對后者而言，例如現代噴氣飛機零件，使用能產生50,000噸以上壓力的巨型液力鍛壓機。
One valuable feature of forging is that it improves the strength of the metal by refining the structure and making it uniform;so for heavy forgings, such as marine propeller shafts, an immensely powerful hydraulic press squeezes the metal with a force sometimes as great as 10,000 tonnes.鍛造有價值的特性之一是它通過使金屬組織均勻而改善強度，因此對諸如船舶螺旋槳軸之類的重型鍛件，要用能達10,000噸壓力的龐大而有力的液壓機來擠壓金屬。
Although the hydraulic forging press is a more expensive piece of equipment than a drop-forge, it has advantages beside those of giving greater strength and more uniform structure to large components.On account of the high pressure and squeezing action, it operates with less noise and vibration than a drop-forge.雖然這種液壓鍛機比落錘鍛造要昂貴得多，但它除了能給予大零件較高的強度和更均勻的組織外還有其它優點。由于較高的壓力和擠壓作用，它比落錘鍛造噪聲及振動都小得多。
As ingots of steel weighing 30 tonnes or more are forged in this way, manual operation is impossible and it is essential that all the manipulation of the ingot is done mechanically.由于這種情況下被鍛鋼坯重量大于30噸，人工操作是不可能的，鋼坯的所有操作都必須是機械化的。
Forging refines the grain structure and improves physical properties of the metal.With proper design, the grain flow can be oriented in the direction of principal stresses encountered in actual use.鑄造細化金屬的晶粒組織、改善其物理性能。通過適當的設計，可以使晶粒流動方向與實際使用時的主應力方向一致。
As shown in Fig.4.2, grain flow is the direction of the pattern that the crystals take during plastic deformation.Physical properties(such as strength, ductility and toughness)are much better in a forging than in the base metal, which has crystals randomly oriented.如圖4.2所示，晶粒流動的方向就是在塑性變形期間結晶排列的方向。鍛件的物理性能(如強度、延展性和韌性)遠好于基礎金屬，因為基礎金屬的晶粒是無序排列的。
Forgings are consistent from piece to piece, without any of the porosity, voids, inclusions and other defects.Thus, finishing operations such as machining
do not expose voids, because there aren’t any.Also coating operations such as plating or painting are straightforward due to a good surface, which needs very little preparation.鍛件各部分是連貫一致的，沒有孔隙、空洞、雜質及其它缺陷。因此像機加工之類的精加工工序不會受空洞的影響，因為根本就不存在。另外由于鍛件良好的表面，像電鍍或油漆之類的涂裝工序就很簡單，幾乎不需要做準備工作。
Forgings yield parts that have high strength to weight ratio, thus are often used in the design of aircraft frame members.A forged metal can result in the following:
鍛造生產的零件具有較高的強度重量比，所以常被用在飛機結構零件的設計中。
鍛造金屬可以導致下列結果：
Increase length, decrease cross-section, called drawing out the metal.Decrease length, increase cross-section, called upsetting the metal.Change length, change cross-section, by squeezing in closed impression dies.This results in favorable grain flow for strong parts.●增加長度、減小橫截面，稱為延伸金屬。●減小長度、增加橫截面，稱為鐓粗金屬。●通過用封閉鍛模擠壓，改變長度和橫截面。
這導致有利的晶粒流使零件堅固。Common Forging Processes常用的鍛造工藝
The metal can be forged hot(above recrystallization temperatures)or cold.金屬既可熱鍛(高于再結晶溫度)也可冷鍛。
Open die forgings/Hand forgings.Open die forgings or hand forgings are made with repeated blows in an open die, where the operator manipulates the workpiece in the die.The finished product is a rough approximation of the die.This is what a traditional blacksmith does, and is an old manufacturing process.開式模鍛/手工鍛：開式模鍛或手工鍛就是操作者操縱工件在開式鍛模中反復擊打。完成的產品是鍛模的粗糙近似物。這就是傳統鐵匠干的活，是較古老的制造工藝。
Impression die forgings/Precision forgings.Impression die forgings and precision forgings are further refinements of the blocker forgings.The finished part more closely resembles the die impression.壓模鍛/精密鍛：壓模鍛和精密鍛是雛形模鍛的進一步改進。完成的零件與模膛更相似。
Press forgings.Press forgings use a slow squeezing action of a press, to transfer a great amount of compressive force to the workpiece.Unlike an open-die forging where multiple blows transfer the compressive energy to the outside of the product, press forging transfers the force uniformly to the bulk of the material.壓鍛：壓鍛通過壓力機緩慢的擠壓動作將巨大的壓力傳遞給工件。不像開式模鍛那樣需要多次擊打把壓縮能量傳遞到零件外表面，壓鍛能將力均勻地傳遞給材料的主體。
This results in uniform material properties and is necessary for large weight forgings.Parts made with this process can be quite large as much as 125kg(260lb)and 3m(10 feet)long.這使材料性能一致，對大重量鍛件而言是十分必要的。采用此工藝生產的零件重量可達125kg(260lb)而長度可達3m(10 feet)。
Upset forgings.Upset forging increases cross-section by compressing the length, this is used in making heads on bolts and fasteners, valves and other similar parts.頂鍛：頂鍛通過壓縮長度增加橫截面，用于在螺栓等緊固件、柱塞及類似零件上制造頭部。
Roll forgings.In roll forging, a bar stock, round or flat is placed between die rollers which reduces the cross-section and increases the length to form parts such as axles, leaf springs etc.This is an essential form of draw forging.滾鍛：在滾鍛時，圓的或是扁平的棒料放在模輥之間縮小橫截面增加長度制成諸如輪軸、板簧之類的零件。這是軋鍛的基本形式。
Swaging.Swaging—a tube or rod is forced inside a die and the diameter is reduced as the cylindrical object is fed.The die hammers the diameter and causes the metal to flow inward causing the outer diameter of the tube or the rod to take the shape of the die.型鍛：型鍛—將圓管或圓棒強制壓入鍛模，隨著圓柱形物體的被壓入其直徑減小。鍛模錘擊橫斷面使金屬向內流動導致圓管或圓棒的外徑變為鍛模的形狀。
Net shape/Near-net shape forging.In net shape or near-net shape forging, forging results in wastage of material in the form of material flash and subsequent machining operations, as shown in Fig.4.3.This wastage can be as high as 70% for gear blanks, and even 90% in the case of aircraft structural parts.純型/近似純型鍛 ：采用純型鍛或近似純型鍛，產生材料損耗的主要形式是飛邊以及隨后的機加工，如圖4.3所示。齒輪毛坯材料損耗為70%，而飛機結構零件的材料損耗甚至達90%。
Net-shape and near-net-shape processes minimize the waste by making precision dies, producing parts with very little draft angle(less than 1°).These types of processes often eliminate or reduce machining.純型鍛和近似純型鍛工藝通過制作精密模具并生產鍛模斜角很小(小于1°)的零件能使材料損耗最小化。此類工藝通常可以省去或減少機加工。
The processes are quite expensive in terms of tooling and the capital expenditure required.Thus, these processes can be only justified for current processes that are very wasteful where the material savings will pay for the significant increase in tooling costs.從模具的角度而言這些工藝是相當昂貴的，需要資金投入。因此這些工藝只有對目前很浪費的生產過程，在材料節約足以補償模具成本的大量增加時才是合理的。Die Design Consideration鍛模設計的考慮因素
Parting surface should be along a single plane if possible, else following the contour of the part.The parting surface should be through the center of the part, not near the upper or lower edges.如果可能分模面應沿著單一平面，否則就順著零件輪廓方向。分模面應經過零件中心，而不要靠近上下邊緣。
If the parting line cannot be on a single plane, then it is good practice to use symmetry of the design to minimize the side thrust forces.Any point on the parting surface should be less than 75°from the principal parting plane.如果分模面不能在單一平面，利用設計的對稱性來減小側向推力不失為一種好方法。分模面上任意點與主分模面的夾角應小于75°。
As in most forming processes, use of undercuts should be avoided as these will make the removal of the part difficult, if not impossible.如同大多數成型工藝，如果不是非用不可，盡量避免采用凹槽，因為凹槽會使零件難以取出。
Generous fillets and radius should be provided to aid in material flow during the forging process.Sharp corners are stress-risers in the forgings, as well as make the dies weak in service.Ribs should not be high or narrow;this makes it difficult for the material to flow.應提供盡可能大的倒角和半徑以幫助材料在鍛造過程中流動。銳角會增加鍛件中的應力，同時在使用時削弱鍛模。
加勁肋不要過高、過窄，因為這會造成材料流動困難。Tolerances
公差
Dimension tolerances are usually positive and are approximately 0.3% of the dimension, rounded off to the next higher 0.5mm(0.020in.).尺寸公差通常為正，大約取為該尺寸的0.3%，并圓整到較大的0.5mm(0.020in.)。
Die wear tolerances are lateral tolerances(parallel to the parting plane)and are roughly +0.2% for copper alloys to +0.5% for aluminum and steel.鍛模磨損公差為側向公差(平行于分模面)，對銅合金大約為+0.2%，對鋁和鋼大約為+0.5%。
Die closure tolerances are in the direction of opening and closing, and range from 1mm(0.040in.)for small forgings, die projection area＜150cm2(23in.2), to 6.25mm(0.25in.)for large forgings, die projection area＞6,500cm2(100in.2).鍛模的閉合公差處于開閉的方向上，范圍從對較小鍛件[其投影面積＜150cm2(23in.2)]取為1mm(0.040in.)，到較大鍛件[其投影面積＞6,500cm2(100in.2)]取為6.25mm(0.25in.)。
Die match tolerances are to allow for shift in the upper die with respect to the lower die.鍛模的配合公差是為了允許上模能根據下模替換。
A proper lubricant is necessary for making good forgings.The lubricant is useful in preventing sticking of the workpiece to the die, and also acts as a thermal insulator to help reduce die wear.制造良好的鍛件必須有合適的滑潤劑。滑潤劑對防止工件粘住鍛模很有用，還可以作為絕熱體幫助減少鍛模磨損。
Unit5
Powder metallurgy(Fig.5.1)uses sintering process for making various parts out of metal powder.The metal powder is compacted by placing in a closed metal cavity(the die)under pressure.粉末冶金(圖5.1)采用燒結工藝將金屬粉末制成各種各樣的零件。金屬粉末放在封閉的金屬腔(模具)中在壓力下被壓實。
This compacted material is placed in an oven and sintered in a controlled atmosphere at high temperatures and the metal powders coalesce and form a solid.A Second pressing operation, repressing, can be done prior to sintering to improve the compaction and the material properties.被壓實的材料置于爐內燒結，在高溫下爐內環境可控，金屬粉末熔合形成固體。在燒結前可以進行二次擠壓作業(再擠壓)以改善壓實狀態和材料性能。
Powder metallurgy is a highly developed method of manufacturing reliable ferrous and nonferrous parts.Made by mixing elemental or alloy powders and compacting the mixture in a die, the resultant shapes are then sintered or heated in a controlled atmosphere furnace.粉末冶金是一種高度發達的制造可靠鐵或非鐵零件的方法。通過混合元素或合金粉末并在模具中壓實混合物，再燒結或在環境可控爐內加熱制成最終形狀。Material
材料
The majority of the structural components produced by fixed die pressing are iron-based.The powders are elemental, pre-alloyed, or partially alloyed.大多數用固定模壓制的結構件都是鐵基的。粉末可以是單一元素、預先合金或部分合金。Elemental powders, such as iron and copper, are easy to compress to relatively high densities, produce pressed compacts with adequate strength for handling during sintering, but do not produce very high strength sintered parts.諸如鐵、銅之類的單一元素粉末較容易被壓得相對密度較高、生產具備足夠強度的壓制物供燒結處理，但是無法制造出很高強度的燒結零件。
Pre-alloyed powders are harder, less
compressible and hence require higher pressing loads to produce high density compacts.However, they are capable of producing high strength sintered materials.預先合金粉末比較硬、不容易壓實，因此需要較高的擠壓力來產生高密度的壓制物。然而它們能生成高強度燒結材料。
Pre-alloying is also used when the production of a homogeneous material from elemental powders requires very high temperatures and long sintering times.The best examples are the stainless steels, whose chromium and nickel contents have to be pre-alloyed to allow economic production by powder metallurgy.如果用單一元素粉末生產均勻材料需要很高溫度和較長燒結時間，也可用預先合金。最好的例子是不銹鋼，因含有鉻和鎳成分，所以粉末冶金必須用預先合金才經濟。
Partially alloyed powders are a compromise approach.Elemental powders, e.g.iron with 2wt.% copper, are mixed to produce an homogeneous blend which is then partially sintered to attach the copper particles to the iron particles without producing a fully diffused powder but retaining the powder form.部分合金粉末是一種折衷的方法。單一元素粉末，例如鐵與2%的銅(重量百分比)混合均勻，經部分燒結后銅微粒粘附到鐵微粒上而沒有產生充分擴散的粉末卻保留了粉末的形態。
In this way the compressibilities of the separate powders in the blend are maintained and the blend will not segregate during transportation and use.用這種方法混合物中單獨粉末的可壓縮性得以維持，在運送和使用期間結合將不會分離。
A similar technique is to “glue” the small percentage of alloying element onto the iron powder.This “glueing” technique is successfully used to introduce carbon into the blends, a technique which prevents carbon segregation and dusting, producing so-called “clean” powders.另一種類似的技術是把小百分比的合金元素“粘合”到鐵微粒上。這種“粘合”技術已成功用于將碳引入結合物，一種防止碳分離并起塵的技術，生產所謂的“清潔”粉末。Powder Consolidation粉末合成
Components or articles are produced by forming a mass of powder into a shape, then consolidating to form inter-particle metallurgical bonds.通過將大量的粉末放入模具成型為零件或物品，然后合成為內有微粒的冶金結合物。
An elevated temperature diffusion process referred to as sintering, sometimes assisted by external pressure, accomplishes this.The material is never fully molten, although there might be a small volume fraction of liquid present during the sintering process.Sintering can be regarded as welding the particles present in the initial useful shape.提升溫度擴散工藝被稱為燒結，有時還輔之以外界的壓力來達到目的。雖然在燒結過程中可能會有少量液態出現，但材料決不是全熔化。燒結可以被看作是把微粒焊接成初始的有用形狀。
As a general rule both mechanical and physical properties improve with increasing density.Therefore the method selected for the fabrication of a component by powder metallurgy will depend on the level of performance required from the part.Many components are adequate when produced at 85~90% of theoretical full density whist others require full density for satisfactory performance.作為普遍規律，隨著密度的增加機械和物理性能均改善。因此選擇何種粉末冶金方法來制作零件取決于其所需的性能級別。許多零件只需理論全密度的85~90%而其它的則需全密度才能滿足要求。
Some components, in particular bush type bearings often made from copper and its alloys, are produced with significant and controlled levels of porosity, the porosity being subsequently filled with a lubricant.Fortunately there is a wide choice of consolidation techniques available.有些零件，尤其是襯套式軸承常用銅及其合金制作，控制多孔性程度的意義重大，因為這些孔隨后要填充潤滑劑。
還好有多種合成技術可供選擇。Cold Uniaxial Pressing
Elemental metal, or an atomized pre-alloyed powder is mixed with a lubricant, typically lithium stearate(0.75 wt.%), and pressed at pressures of say, 600MPa(87,000lb/in.2)in metal dies.冷單向擠壓
單一元素金屬，或極小顆粒的預先合金粉末與潤滑劑(一般是鋰硬脂酸鹽，重量百分比0.75%)混合，然后在金屬模具中施加壓力[比如600MPa(87,000lb/in.2)]擠壓。
Cold compaction ensures that the as-compacted, or “green”, component is dimensionally very accurate, as it is moulded precisely to the size and shape of the die.冷擠壓能保證被壓制或“未加工”的零件尺寸十分精確，因為它被精確地按模具的尺寸和形狀成型。
One disadvantage of this technique is the differences in pressed density that can occur in different parts of the component due to particle/particle and die wall/particle frictional effects.Typical as-pressed densities for soft iron components would be 7.0g/cc, i.e.about 90% of theoretical density.這種技術的缺點之一是由于微粒/微粒和模壁/微粒間的摩擦效應，零件不同部位的壓實密度存在差異。典型的軟鐵零件壓制密度為7.0g/cc，即大約是理論密度的90%。
Compaction pressure rises significantly if higher as-pressed densities are required, and this practice becomes uneconomic due to higher costs for the larger presses and stronger tools to withstand the higher pressures.如果需要較高的壓實密度則壓實壓力要顯著提高，因為大型壓力機成本較高并且在較高壓力下模具強度要更高這樣就不合算。Cold Isostatic Pressing
Metal powders are contained in an enclosure e.g.a rubber membrane or a metallic can that is subjected to isostatic, which is uniform in all directions, external pressure.As the pressure is isostatic the as-pressed component is of uniform density.冷均衡擠壓
金屬粉末裝入均衡受壓的橡膠膜或金屬罐內，其所受外壓力在各個方向都是均勻的。由于壓力是均衡的，所以壓制零件密度是均勻的。
Irregularly shaped powder particles must be used to provide adequate green strength in the as-pressed component.This will then be sintered in a suitable atmosphere to yield the required product.必須采用不規則形狀粉末微粒為壓制零件提供足夠的未加工強度。然后放入合適的環境中燒結成所需產品。
Normally this technique is only used for semi-fabricated products such as bars, billets, sheet, and roughly shaped components, all of which require considerable secondary operations to produce the final, accurately dimensioned component.通常這種技術只用于制作諸如棒料、坯段、薄板及粗糙成型零件之類的半成品，所有這些都需要大量進一步加工才能生產出最終尺寸精確的零件。
Again, at economical working pressures, products are not fully dense and usually need additional working such as hot extrusion, hot rolling or forging to fully density the material.此外使用經濟工作壓力的產品不是充分致密的，一般需要增加諸如熱擠壓、熱軋或鍛之類的額外工序來使材料達到全密度。Sintering
Sintering is the process whereby powder compacts are heated so that adjacent particles fuse together, thus resulting in a solid article with improved mechanical strength compared to the powder compact.燒結
燒結就是通過把粉末壓制物加熱使鄰近的微粒熔合在一起的工藝，它能生成比粉末壓制物機械強度更好的固體物。
This “fusing” of particles results in an increase in the density of the part and hence the process is sometimes called densification.There are some processes such as hot isostatic pressing which combine the compaction and sintering processes into a single step.微粒的“熔合”導致零件密度增加，因此該工藝有時被稱為致密化。還有一些工藝如熱均衡擠壓，將壓實和燒結工藝合并為單一步驟。
After compaction the components pass through a sintering furnace.This typically has two heating zones, the first removes the lubricant, and the second higher temperature zone allows diffusion and bonding between powder particles.零件壓實后通過燒結爐。一般有兩個加熱區，第一個去除潤滑劑，第二個溫度更高的區域讓粉末微粒之間擴散并結合。
A range of atmospheres, including vacuum, are used to sinter different materials depending on their chemical compositions.As an example, precise atmosphere control allows iron/carbon materials to be produced with specific carbon compositions and mechanical properties.根據不同材料的化學成分，燒結的環境包括真空狀態也各不相同。例如精確的環境控制可使鐵/碳材料生成特殊碳化物和機械性能。
The density of the component can also change during sintering, depending on the materials and the sintering temperature.These dimensional changes can be controlled by an understanding and control of the pressing and sintering parameters，根據材料和燒結溫度的不同，零件的密度在燒結過程中也會改變。因為尺寸的變化可以通過了解并調節擠壓及燒結參數進行控制，and components can be produced with dimensions that need little or no rectification to meet the dimensional tolerances.Note that in many cases all of the powder used is present in the finished product, scrap losses will only occur when secondary machining operations are necessary.所以零件尺寸幾乎無需校正就能滿足尺寸公差。可以看到在很多情況下所有使用的粉末都包含在制成品中，廢料損失僅產生于需要輔助機加工時。Hot Isostatic Pressing
Powders are usually encapsulated in a metallic container but sometimes in glass.The container is evacuated, the powder out-gassed to avoid contamination of the materials by any residual gas during the consolidation stage and sealed-off.熱均衡擠壓
粉末通常封裝在金屬容器內有時也裝在玻璃容器內。把容器抽真空，粉末抽氣是為了防止材料在合成階段和密封時被殘留氣體污染。
It is then heated and subjected to isostatic pressure sufficient to plastically deform both the container and the powder.再加熱并施加均衡壓力足以使容器和粉末都塑性變形。
The rate of densification of the powder depends upon the yield strength of the powder at the temperatures and pressures chosen.At moderate temperature the yield strength of the powder can still be high and require high pressure to produce densification in an economic time.粉末致密率取決于該粉末在選定溫度和壓力下的屈服強度。中等溫度下粉末的屈服強度仍然較高，因此需要較高壓力使其在經濟時間內致密化。
Typical values might be 1120℃ and 100MPa for ferrous alloys.By pressing at very much higher temperatures lower pressures are required as the yield strength of the material is lower.Using a glass enclosure atmospheric pressure(15psi)is used to consolidate bars and larger billets.對鐵合金典型的數值為1120℃和100MPa。由于很高溫度下材料的屈服強度較低，因此只需較低壓力就能擠壓。采用玻璃容器時可用大氣壓力(15psi)合成棒料和較大坯段。
The technique requires considerable financial investment as the pressure vessel has to withstand the internal gas pressure and allow the powder to be heated to high temperatures.因為壓力容器必須經受住內氣壓并允許粉末加熱到較高溫度，所以這種技術需要相當可觀的資金投入。
As with cold isostatic pressing only semi-finished products are produced, either for subsequent working to smaller sizes, or for machining to finished dimensions.此工藝與采用冷均衡擠壓一樣只能生產半成品，可以通過后續加工至較小尺寸，也能用機加工到最終尺寸。
Hot Forging(Powder Forging)
Cold pressed and sintered components have the great advantage of being close to final shape(near-net shape), but are not fully dense.Where densification is essential to provide adequate mechanical properties, the technique of hot forging, or powder forging, can be used.熱鍛(粉末鍛造)
冷擠壓和燒結零件主要優點是接近最終形狀(近似純形)，但不是充分致密的。當為了提供足夠的機械性能而致密化是必須時，可以采用熱鍛或粉末鍛造技術。
In powder forging an as-pressed component is usually heated to a forging temperature significantly below the usual sintering temperature of the material and then forged in a closed die.This produces a fully dense component with the shape of the forging die and appropriate mechanical properties.在粉末鍛造中，壓制零件一般加熱到遠低于該材料通常燒結溫度的鍛造溫度，然后在閉模中鍛造。這能生產具有鍛模形狀和合適機械性能的充分致密零件。
Powder forged parts generally are not as close to final size or shape as cold pressed and sintered parts.These results from the allowances made for thermal expansion effects and the need for draft angles on the forging tools.Further, minimal machining is required but when all things are considered this route is often very cost-effective.粉末鍛造零件通常不像冷擠壓和燒結零件那樣接近最終尺寸或形狀。這是由于為熱膨脹效應而設置允差以及在鍛模上需要拔模斜角所致。此外還需少量機加工，但全面考慮這種方法通常還是很劃算的。Metal Injection Moulding(MIM)
Injection moulding is very widely used to produce precisely shaped plastic components in complex dies.As injection pressures are low it is possible to manufacture complex components, even some with internal screw threads, by the use of side cores and split tools.金屬注塑成型(MIM)
注塑成型被很廣泛地用于在復雜模具中生產形狀精確的塑料零件。注塑壓力較低使得制作復雜零件成為可能，通過采用側面型芯和分離工具甚至可以帶有內螺紋。
By mixing fine, typically less than 20 μm diameter, spherical metal powders with thermoplastic binders, metal filled plastic components can be produced with many of the features available in injection moulded plastics.After injection moulding, the plastic binder material is removed to leave a metal skeleton which is then sintered at high temperature.將細小(直徑一般小于20μm)球形金屬粉末與熱塑性粘合劑混合，能生產具有多數注塑成型塑料特征的金屬充滿塑料零件。注塑成型后，去除塑料粘合材料剩下金屬骨架，然后在高溫下燒結。
Dimensional control can be exercised on the as-sintered component as the injected density is sensibly uniform so shrinkage on sintering is also uniform.燒結零件可以實現尺寸控制，因為注塑密度明顯均勻，所以燒結收縮也是均勻的。
Shrinkage can be large, due to both the fine particle size of the powders and the substantial proportion of polymer binder used.由于所用粉末細小微粒的尺寸和聚合物粘合劑的真實比例，收縮可以比較大。Features
特征
For high tolerance parts, a sintering part is put back into a die and repressed.In genera this makes the part more accurate with a better surface finish.對較大公差的零件，燒結后可放回模具重新擠壓。一般而言這會使零件更精確同時具有更好的表面光潔度。A part has many voids that can be impregnated.One method is to use an oil bath.Another method uses vacuum first, then impregnation.零件有許多可供填充的空間。一種方法是采用油浴。另一種方法是先抽真空然后再充滿。
A part surface can be infiltrated with a low melting point metal to increase density, strength, hardness, ductility and impact resistance.Plating, heat treating and machining operations can also be used.零件表面能被低熔點金屬滲透以增大密度、強度、硬度、延展性和抗沖擊能力。仍然可以進行電鍍、熱處理和機加工作業。Advantages
優點
Good tolerances and surface finish Highly complex shapes made quickly Can produce porous parts and hard to manufacture materials(e.g.cemented oxides)良好的公差和表面光潔度 高度復雜的形狀能快速制作
能制作多孔零件和難以加工材料(如粘結氧化物)Pores in the metal can be filled with other materials/metals Surfaces can have high wear resistance Porosity can be controlled Low waste Automation is easy 金屬中的氣孔可用其它材料/金屬填充 表面能具有較高的耐磨性 孔隙率可以控制 較低損耗 容易自動化
Physical properties can be controlled Variation from part to part is low Hard to machine metals can be used easily No molten metals 物理性能可以控制 零件之間的變化較小 難以機加工的金屬能被容易使用 無需熔化金屬
No need for many/any finishing operations Permits high volume production of complex shapes Allows non-traditional alloy combinations Good control of final density 不需要很多/任何修整作業 允許加工復雜形狀的大體積產品 允許非傳統合金結合 對最終密度能很好地控制 Disadvantages
缺點
Metal powders deteriorate quickly when stored improperly Fixed and setup costs are high Part size is limited by the press and compression of the powder used 如果存放不當金屬粉末質量很快降低 安裝和調整的成本較高
零件尺寸受壓力機和所用粉末壓縮的限制
Sharp corners and varying thickness can be hard to produce Non-moldable features are impossible to produce 銳角和變厚度較難加工 不適合模壓的東西不可能生產
Unit6
Injection molding(Fig.6.1)is the predominant process for fabrication of thermoplastics into finished forms, and is increasingly being used for thermosetting plastics, fiber-filled composites, and elastomers.注塑成型(圖6.1)是將熱塑性塑料制成最終形狀的主要工藝，并且越來越多地用于熱硬化性塑料、纖維填充合成物和人造橡膠。
It is the process of choice for tremendous variety of parts ranging in weight from 5g to 85kg.It is estimated that 25% of all thermoplastics are injection molded.它是重量范圍為5g到85kg極大一類零件可選用的工藝。估計所有熱塑性塑料中有25%是采用注塑成型的。
If newer modifications, such as reaction injection molding, and the greatly increased rate of adoption of plastics as substitutes for metals are considered, it is likely that the worldwide industrial importance of injection molding will continue to increase.如果考慮到新近的改進(例如反作用注塑成型)和采用塑料替代金屬的高增長率，注塑成型在世界范圍的工業重要性很可能將繼續增加。
Currently, probably close to half of all major processing units is injection molding machines.In 1988, a dollar sale of new injection molding machinery in the U.S.was approximately 65% of total major polymer machinery sales volume;this included 4,600 injection molding units.當前，大概所有主要處理設備的近一半是注塑成型機。1988年，美國新的注塑成型機械銷售約占全部主要聚合物機械銷售量的65%，其中包括4,600臺注塑成型設備。
The machines and their products are ubiquitous and are synonymous with plastics for many people.這類機械和它們的產品普遍存在，對許多人來說與塑料是同義的。
A reciprocating screw injection molding machine combines the functions of an extruder and a compressive molding press.往復螺旋注射成型機把壓出機和成型壓力機的功能結合起來。
It takes solid granules of thermoplastic resin, melts and pressurizes them in the extruder section, forces the melt at high velocity and pressure through carefully designed flow channels into a cooled mold, then ejects the finished part(s), and automatically recycles.把熱塑性塑料樹脂的固體顆粒在壓出部分融化并增壓，迫使其高速融化并通過仔細設計的流動通道進入冷卻模具，噴射成最終零件，然后自動再循環。
This machine is a descendant of the plunger type “stuffing machine” patented by the Hyatt brothers in 1872 to mold celluloid.In 1878, the Hyatts developed the first multicavity mold, but it was not until 1938 that Quillery(France)patented a machine incorporating a screw to plasticize the elastomer being molded.這種機械是1872年Hyatt兄弟獲得專利權的融化賽璐珞的活塞型“填充機”的派生物。1878年Hyatt兄弟開發了第一個多槽模具，但直到1938年Quillery(法國)才發明了用螺旋增塑人造橡膠并使其成型的一體化機械。
In 1956, Ankerwerk Nuremberg commercialized the modern reciprocating screw injection molding machine for thermoplastics.Today, over 50 machine manufacturers are listed in Modern Plastics Encyclopedia, offering machines to the U.S.market ranging from 2 to 6,000 tons clamping capacity.1956年，Ankerwerk Nuremberg使用于熱塑性塑料的現代往復螺旋注塑成型機商業化。今天，已有超過50家制造商列入現代塑料制品百科全書，能為美國市場提供壓制能力從2到6,000噸的機械。
(A machine with a 10,000-ton capacity has been built to mold 264-gallon HDPE trash containers.)A host of suppliers of auxiliary equipment, molds, instruments, and controls service this major segment of the polymer industry.(一臺能力為10,000噸用于成型264加侖高密度聚乙烯垃圾箱的機械也已制成)。許多輔助設備、模具、儀器和控制系統供應商在為聚合物工業的這一主要部分服務。
Injection molding is particularly worthy of intensive study because it combines many areas of interest extrusion, mold design, rheology, sophisticated hydraulic and electronic controls, robotic accessories, design of complex products, and, of course, the integration of materials science and process engineering.注塑成型對深入研究很有價值，因為它結合了許多重要領域，如擠壓、模具設計、流變學、完備的液壓和電子控制、機器人配件、復雜產品的設計，當然還有材料科學與加工工程的綜合。
The objectives of injection molding engineers are simple enough: to obtain minimum cycle time with minimum scrap, to attain specified product performance with assurance, to minimize production costs due to downtime or any other reasons, and to steadily increase in expertise and competitiveness.注塑成型工程師的目標很簡單：在最少廢料的情況下取得最小循環時間，在有保證的情況下獲得指定產品性能，將由停工或其它原因產生的生產成本最小化，還有穩定地增加專門知識和競爭力。
Profit margins for custom injection molders are said to be generally skimpy;an established way to improve profits is to be selected for more demanding, higher margin jobs that demand the highest level of efficiency and competence.傳統的注塑成型機利潤盈余據說一般是不足的；為了更多需求及更高盈余工作需要選擇一種改善利潤的確定方法，它要求最高水平的效率和能力。
This text will concentrate on the reciprocating screw machine for thermoplastics, which has largely replaced the older reciprocating plunger types except for very small-capacity machines.本文將集中論述熱塑性塑料用的往復螺旋機，除了小容量機械外它已在很大程度上取代了較老的往復活塞式機械。
Injection Molding Materials注塑成型材料
It is not possible to injection-mold all polymers.Some polymers like PTFE(Poly-tetra-fluoro-ethylene), cannot be made to flow freely enough to make them suitable for injection molding.要注塑成型所有聚合物是不可能的。像聚四氟乙烯之類的聚合物就不能自由流動得足以適合注塑成型。
Other polymers, such as a mixture of resin and glass fiber in woven or mat form, are unsuitable by their physical nature for use in the process.In general, polymers which are capable of being brought to a state of fluidity can be injection-molded.其它聚合物，例如樹脂和編織的或墊子形的玻璃纖維的混合物，由于它們的物理性質不適合使用此工藝。一般而言，能進入流動狀態的聚合物都可以注塑成型。
The vast majority of injection molding is applied to thermoplastic polymers.This class of materials consists of polymers which always remain capable of being softened by heat and of hardening on cooling, even after repeated cycling.注塑成型的絕大多數都用于熱塑性聚合物。這類材料由具有加熱軟化、冷卻硬化甚至可重復循環能力的聚合物組成。
This is because the long-chain molecules of the material always remain as separate entities and do not form chemical bonds to one another.An analogy car, be made to a block of ice that can be softened(i.e.turned back to liquid), poured into any shape cavity, and then cooled to become a solid again.這是由于這類材料的長鏈分子總是保持分離的實體并不相互形成化學連結。一輛由冰塊制成的模擬汽車，可以融化(即轉化為液態)，倒入任何形狀的空腔，然后冷卻重新變成固體。
This property differentiates thermoplastic materials from thermosetting ones.In the latter type of polymer, chemical bonds are formed between the separate molecule chains during processing.In this case the chemical bonding referred to as cross linking is the hardening mechanism.這個特性將熱塑性材料與熱硬化性材料區分開。后者在加工過程中分離的分子鏈之間形成化學連結。在此情況下作為交聯的化學連結是硬化機制。
In general, most of the thermoplastic materials offer high impact strength, corrosion resistance, and easy processing with good flow characteristics for molding complex designs.Thermoplastics are generally divided into two classes: namely crystalline and amorphous.一般而言，大多數熱塑性材料具有較高的抗沖擊強度、耐腐蝕性以及良好流動性使其容易加工而適于復雜成型設計。熱塑性塑料通常分為兩類：即結晶質的和非結晶質的。Crystalline polymers have an ordered molecular arrangement, with a sharp melting point.Due to the ordered arrangement at molecules, the crystalline polymers reflect most incidents light and generally appear opaque.結晶質聚合物具有規則的分子排列及明顯的熔點。由于規則的分子排列，結晶質聚合物能反射大多數特定光線并一般表現為不透明的。
They also undergo a high shrinkage or reduction in volume during solidification.Crystalline polymers usually are more resistant to organic solvents and have good fatigue and wear-resistant properties.Crystalline polymers also generally are denser and have better mechanical properties than amorphous polymers.它們在固化過程中收縮較大或體積減少較多。結晶質聚合物通常多能抵御有機溶劑并具有良好的抗疲勞和磨損特性。結晶質聚合物通常也比非結晶質聚合物更致密并且具有更好的機械性能。
The main exception to this rule is polycarbonate, which is the amorphous polymer of choice for high quality transparent moldings, and has excellent mechanical properties.其中主要例外是聚碳酸酯，它是可選用做高質量透明注塑件的非結晶質聚合物，并具有卓越的機械性能。
The mechanical properties of thermoplastics, while substantially lower than those of metals, can be enhanced for some applications through the addition of glass fiber reinforcement.This takes the form of short-chopped fibers, a few millimeters in length, which are randomly mixed with the thermoplastic resin.就本質而言，熱塑性塑料的機械性能低于金屬，但可以通過加入玻璃纖維強化予以增強來適應某些運用。常用幾毫米長的短碎纖維隨機地與熱塑性樹脂混合。
The fibers can occupy up to one third of the material volume to considerably improve the material strength and stiffness.The negative effect of this reinforcement is usually a decrease in impact strength and an increase in abrasiveness.纖維可占材料體積的三分之一以極大改善材料的強度和硬度。這種加強的負作用通常是抗沖擊強度降低及磨損性增加。
The latter also has an effect on processing since the life of the mold cavity is typically reduced from about 1,000,000 parts for plain resin parts to about 300,000 for glass-filled parts.后者對加工過程也有影響，因為模具腔的壽命從典型的普通樹脂零件大約1,000,000件減少到玻璃纖維填充樹脂零件的約300,000件。
Perhaps the main weakness of injection-molded parts is the relatively low service temperatures to which they can be subjected.Thermoplastic components can only rarely be operated continuously above 250℃, with an absolute upper service temperature of about 400℃.注塑成型零件的主要缺點或許是它們能承受的工作溫度相對較低。熱塑性塑料零件只有很少能連續運行在250℃以上，其絕對最高工作溫度約為400℃。
The temperature at which a thermoplastic can be operated under load can be defined qualitatively by the heat deflection temperature.This is the temperature at which a simply supported beam specimen of the material, with a centrally applied load, reaches a predefined deflection.熱塑性塑料帶載運行溫度可從質量上定義為熱偏差溫度。這是中心承載的該材料簡支梁達到預定偏差的溫度。
The temperature value obviously depends upon the conditions of the test and the allowed deflection and for this reason, the test values are only really useful for comparing different polymers.其溫度值明顯取決于試驗條件和允許偏差，因此對比較不同的聚合物而言只有試驗數據是真正有用的。Cycle of Operation作業循環
The reciprocating screw injection molding machine is considered as consisting of two halves: a fixed injection side, and a movable clamp side.往復螺旋注塑成型機被認為由兩部分組成：一個固定注塑端和一個活動夾具端。
The injection side contains the extruder that receives solid resin in pellet or granular form and converts it into a viscous liquid or melt that can be forced through the connecting nozzle, spine, and runners to the gates that lead into the mold cavities.注塑端包含壓出機，它接受小球或粒狀的固體樹脂，然后將其轉化為粘性液體或稱為融化，再強迫其通過連接噴嘴、中心和澆道到閘道進入模具腔。
The mold is tightly clamped against injection pressure and is cooled well below the melt temperature of the thermoplastic.When the parts in the cavities have cooled sufficiently the mold halves are opened at the mold parting plane and the parts ejected by a knockout system drop into a receiving bin below.模具被緊緊地夾住以抵抗注塑壓力，并在熱塑性塑料的融化溫度以下很好地冷卻。當模腔內的零件充分冷卻，剖分模在模具分模面處打開，推出系統將零件推出落入下面的接收容器內。
This summarizes the overall cycle, but leaves out much vital detail that is necessary for understanding the process.However, with this introduction, it is possible to understand the advantages and disadvantages of the process.這概述了整個循環，但省略了許多對理解此工藝所必需的很重要細節。然而通過本介紹，了解這種工藝的優缺點仍是可能的。
Effects of Process Variables on Orientation
加工變量對方向性的影響
In injection molding, any variation in processing that keeps the molding resin hot throughout filling allows increased relaxation and, therefore, decreased orientation.Some of the steps that can be taken to reduce orientation are as follows.在注塑成型時，整個填料過程始終保持成型樹脂高溫的任何加工變化都會增加松弛作用而減少方向性。下面是可以用于減少方向性的若干措施。
Faster injection(up to a point): less cooling during filling, hence a thinner initial frozen layer, lower viscosity due to shear thinning;better flow to corners;and less
crystallinity all favor lower subsurface orientation.The primary effect is that the gate will freeze more quickly.At that point, orientation stops and relaxation starts.較快注塑(到點)：在填料過程中冷卻較少，因此初始固化層較薄，由于剪應變稀少而粘性較低；能較好地流到角落；結晶度較小；所有這些促成表面下的方向性也較低。主要效果是閘道將較快固化。這樣使得方向性停止產生而松弛作用開始增加。
Higher melt and mold temperatures: lower melt viscosity, easier filling, and greater relaxation favor reduced orientation.Reduced packing time and pressure: overpacking inhibits relaxation processes.較高的融化和成型溫度：融化粘性較低，更容易填充，較大松弛作用促成方向性減少。減少擠壓時間和壓力：過度擠壓會抑制松弛過程。
Reduced gate size: larger gates take longer to freeze off and permit increased orientation.減小閘道尺寸：閘道越大則固化時間越長并會使方向性增加。
Excessively high injection speed can cause high surface orientation and increase susceptibility to stress cracking.For example, moldings that are to be electroplated, and will be subject to acid solutions during plating, must be made using very slow injection speeds to minimize surface orientation.過高的注塑速度會引起較高的表面方向性及增加應力破裂的敏感性。例如，要電鍍的注塑件在電鍍時會經受酸溶液，必須采用很低的注塑速度制造以使表面方向性最小化。
On the other hand, the transverse motion component of the melt front in most moldings can cause transverse subsurface orientation superimposed on the primary orientation, giving a desirable biaxial orientation effect.另一方面，大多數注塑件的融化前部橫向運動部分能導致在主要方向性上有層理的表面下橫向方向性，產生需要的雙軸方向性效應。
Orientation can be seriously increased by obstructions to flow during filling of the cavity.Flow around an obstruction causes a decrease in melt front speed and leads to high local viscosity and reduced relaxation.This is also likely to occur near the end of the filling phase if gating is inadequate.在填充模腔時流動受到阻礙會極大地增加方向性。圍繞障礙物流動使融化前部的速度下降并產生較高的局部粘性而減少松弛作用。如果閘道不適當，這也很可能發生在接近填充結束階段。
The molder must recognize the dangers of excessive fill speed, insufficient injection pressure, excessive melt temperature, and inadequate packing.These dangers are weighed against the opposing effects on orientation discussed above.注塑工必須認識過快填充速度、不足注塑壓力、過高融化溫度和不充分擠壓的危害性。這些危害性要與上述方向性的反向效應相權衡。
Thicker parts delay cooling and increase relaxation time and tend to result in lower orientation.Thicker parts also tend to warp less.Therefore, a minimum wall thickness can be established by experience for various shapes, materials, and process combinations.較厚零件會延遲冷卻并且增加松弛時間，趨向于導致較低的方向性。較厚零件也有助于減少翹曲。因此，對各種形狀、材料和工藝組合能通過經驗來確定最小壁厚。
Lower molecular weight and broader molecular weight distribution in thermoplastics favor lower orientation and reduced internal stress in moldings.在熱塑性塑料中較小的分子量以及較寬泛的分子量分布促成方向性減少同時降低注塑件中的內應力。
The skin thickness ratio is affected by process variables in the same way as one would predict for the orientation;that is, it decreases as the melt or mold temperatures and cavity pressure increases.Tensile strength and stiffness increase as skin thickness ratio increases.Microscopic examination thus provides another way of studying the process efficiently.外殼厚度比受加工變量影響的方式與方向性預測一樣；也就是它能隨融化或成型溫度及模腔壓力的增加而減少。拉伸強度和硬度隨外殼厚度比增加而增加。因而顯微鏡檢查提供了有效研究該工藝的另一方法。
Advantages
優點
1.High production rates.For example, a CD disk can be produced with a 10~12s cycle in high melt flow index PC.1.高生產率：例如，一張CD盤在高融體流動指數生產控制中只需10~12s一個循環就能生產出來。
2.Relatively low labor content.One operator can frequently take care of two or more machines, particularly the moldings are unloaded automatically onto conveyors.2.相對較少的工作內容：一個操作者經常可以照看兩臺以上機械，尤其是當成品能自動卸到輸送機上時。
3.Parts require little or no finishing.For example, flash can be minimized and molds can be arranged to automatically separate runners and gates from the part itself.4.Very complex shapes can be formed.Advances in mold tooling are largely responsible.3.零件幾乎不需要修整：例如，飛邊可以最小化并且模具能被設計成自動將澆道和閘道從零件本身分離。
4.非常復雜的形狀也能成型：模具的進步很大程度上是可靠的。
5.Flexibility of design(finishes, colors, inserts, materials).More than one material can be molded through co-injection.Foam core materials with solid skins are efficiently produced.Thermosetting plastics and fiber-reinforced shapes are injection molded.5.設計的靈活性(光潔度、顏色、插入物、材料)：通過復合注塑可以成型多于一種材料。可以高效地生產帶有固體外殼的泡沫型芯材料。熱硬化性塑料和纖維加強形狀都可以注塑成型。
6.Minimum scrap loss.Runners, gates, and scrap can usually be reground.Recycled thermoplastics can be injection molded.6.廢料損失最小化：澆道、閘道和廢料通常可以重新研磨。循環熱塑性塑料可以注塑成型。
7.Close tolerances are obtainable.Modern microprocessor controls, fitted to precision molds, and elaborate hydraulics, facilitate tolerances in the 0.1% range on dimensions and weights(but not without a high level of operational skills in constant attendance).7.能得到接近的公差：現代微處理器控制、合適的精密模具和精心制作的液壓設備使得尺寸和重量的公差保持在0.1% 的范圍內(但不是沒有在持續照看時的高水平操作技能)。
8.Makes best use of the unique attributes of polymers, such as flow ability, light weight, transparency, and corrosion resistance.This is evident from the number and variety of molded plastic products in everyday use.8.充分利用聚合物諸如流動能力、重量輕、透明和耐腐蝕等獨特屬性：從日常使用成型塑料產品的數量和種類就能明顯看到。
Disadvantages and Problems缺點和問題
1.High investment in equipment and tools requires high production volumes.2.Lack of expertise and good preventive maintenance can cause high startup and running costs.1.較高的設備和模具投資需要較高生產量才合算。
2.缺少專門技術和良好的預防性維修會導致較高的啟動和運行成本。
3.Quality is sometimes difficult to determine immediately.For example, post-mold warpage may render parts unusable because of dimensional changes that are not completed for weeks or months after molding.3.質量有時難以馬上確定。例如，成型后的翹曲會導致零件不能用，因為在成型后幾星期甚至幾個月尺寸變化都不能完成。
4.Attention is required on many details requiring a wide variety of skills and cross-disciplinary knowledge.5.Part design sometimes is not well suited to efficient molding.4.對許多需要廣泛多樣性技能和交叉學科知識的細節必須加以注意。
5.零件設計有時不能很好地適應有效率的成型。
6.Lead time for mold design, mold manufacture and debugging trials is sometimes very long.6.模具設計、模具制造和調試試驗這些先導工作有時要花費很長時間。
Unit7
The importance of machining processes can be emphasised by the fact that every product we use in our daily life has undergone this process either directly or indirectly.(1)In USA, more than $100 billions are spent annually on machining and related operations.機加工過程的重要性可通過日常生活使用的每件產品都直接或間接經歷這一過程的事實來強調。
(1)在美國，每年花在機加工及其相關作業上的費用都多于千億美元。
(2)A large majority(above 80%)of all the machine tools used in the manufacturing industry have undergone metal cutting.(3)An estimate showed that about 10 to 15% of all the metal produced in USA was converted into chips.(2)用于制造業的全部機床中的大多數(多于80%)都經歷過金屬切削。
(3)有估計顯示美國生產的所有金屬中約10到15%轉變成了切屑。
These facts show the importance of metal cutting in general manufacturing.It is therefore important to understand the metal cutting process in order to make the best use of it.這些事實說明了金屬切削在常規制造中的重要性。因此了解金屬切削過程以充分利用它是重要的。A number of attempts have been made in understanding the metal cutting process and using this knowledge to help improve manufacturing operations which involved metal cutting.在了解金屬切削過程并運用這些知識幫助改善與金屬切削有關的制造作業方面已經做了許多努力。
A typical cutting tool in simplified form is shown in Fig.7.1.The important features to be observed are follows.典型切削刀具的簡化形式如圖7.1所示。要注意的重要特征如下。
1.Rake angle.It is the angle between the face of the tool called the rake face and the normal to the machining direction.Higher the rake angle, better is the cutting and less are the cutting forces, increasing the rake angle reduces the metal backup available at the tool rake face.1.前角：它是被稱為前傾面的刀具面與垂直機加工方向的夾角。前角越大，則切削越好且切削力越小，增加前角可以減少刀具前傾面上產生的金屬阻塞。
This reduces the strength of the tool tip as well as the heat dissipation through the tool.Thus, there is a maximum limit to the rake angle and this is generally of the order of 15°for high speed steel tools cutting mild steel.It is possible to have rake angles at zero or negative.但這會和減少通過刀具散發的熱量一樣減少刀尖強度。因此前角有一最大限制，用高速鋼刀具切削低碳鋼通常為15°。前角取零度或負值也是可能的。
2.Clearance angle.This is the angle between the machined surface and the underside of the tool called the flank face.The clearance angle is provided such that the tool will not rub the machined surface thus spoiling the surface and increasing the cutting forces.A very large clearance angle reduces the strength of the tool tip, and hence normally an angle of the order of 5~6°is used.2.后角：這是機加工面與被稱為后側面的刀具底面夾角。后角使刀具不產生會損壞機加工面的摩擦和增加切削力。很大的后角會削弱刀尖的強度，因此一般采用5~6°的后角。
The conditions which have an important influence on metal cutting are work material, cutting tool material, cutting tool geometry, cutting speed, feed rate, depth of cut and cutting fluid used.對金屬切削有重要影響的條件有工件材料、刀具材料、刀具幾何形狀、切削速度、進給率、切削深度和所用的切削液。
The cutting speed, v, is the speed with which the cutting tool moves through the work material.This is generally expressed in metres per second(ms-1).切削速度v指切削刀具經過工件材料的移動速度。通常用米每秒(ms-1)表示。
Feed rate, f, may be defined as the small relative movement per cycle(per revolution or per stroke)of the cutting tool in a direction usually normal to the cutting speed direction.Depth of cut, d, is the normal distance between the unmachined surface and the machined surface.進給率f可定義為每循環(每轉或每行程)切削刀具在通常為垂直于切削速度方向的次要相對運動。
切削深度d是未加工面與已加工面之間的垂直距離。Chip Formation 切屑的形成
Metal cutting process is a very complex process.Fig.7.2 shows the basic material removal operation schematically.金屬切削過程是一個很復雜的過程。圖7.2用圖的形式顯示了基本材料去除作業。
The metal in front of the tool rake face gets immediately compressed, first elastically and then plastically.This zone is traditionally called shear zone in view of fact that the material in the final form would be removed by shear from the parent metal.在刀具前傾面前的金屬直接受到壓縮，首先彈性變形然后塑性變形。考慮到最終形狀中的材料是通過剪切從母體金屬去除的，此區域傳統上稱為剪切區。
The actual separation of the metal starts as a yielding or fracture, depending upon the cutting conditions, starting from the cutting tool tip.Then the deformed metal(called chip)flows over the tool(rake)face.金屬的實際分離始于屈服或斷裂(視切削條件而定)，從切削刀尖開始。然后變形金屬(稱為切屑)流過刀具(前傾)面。
If the friction between the tool rake face and the underside of the chip(deformed material)is considerable, then the chip gets further deformed, which is termed as secondary deformation.The chip after sliding over the tool rake face is lifted away from the tool, and the resultant curvature of the chip is termed as chip curl.如果刀具前傾面與切屑(變形金屬)底面之間的摩擦相當大，那么切屑進一步變形，這也叫做二次變形。滑過刀具前傾面的切屑被提升離開刀具，切屑彎曲的結果被稱為切屑卷。
Plastic deformation can be caused by yielding, in which case strained layers of material would get displaced over other layers along the slip-planes which coincide with the direction of maximum shear stress.屈服能導致塑性變形，在這種情況下材料變形層沿著與最大剪應力方向一致的滑移面被其它層所取代。
A chip is variable both in size and shape in actual manufacturing practice.Study of chips is one of the most important things in metal cutting.As would be seen later, the mechanics of metal cutting are greatly dependent on the shape and size of the chips produced.在實際加工過程中切屑的尺寸和形狀都是變化的。對切屑的研究是金屬切削最重要的事情之一。如同后面將要看到的那樣，金屬切削力學極大地依賴于所產生切屑的形狀和尺寸。
Chip formation in metal cutting could be broadly categorised into three types:(Fig.7.3)
(1)Discontinuous chip
(2)Continuous chip
(3)Continuous chip with BUE(Built up edge)
金屬切削中的切屑形成可以寬泛地分成三個類型(圖7.3)：
(1)間斷切屑
(2)連續切屑
(3)帶切屑瘤的連續切屑
Discontinuous Chip.The segmented chip separates into short pieces, which may or may not adhere to each other.Severe distortion of the metal occurs adjacent to the face, resulting in a crack that runs ahead of the tool.間斷切屑：分段的切屑分散成小碎片，既可能相互附著也可能不相互附著。在靠近切削面處發生金屬的劇烈變形，導致在運動刀具前方金屬層產生裂縫。
Eventually, the shear stress across the chip becomes equal to the shear strength of the material, resulting in fracture and separation.With this type of chip, there is little relative movement of the chip along the tool face, Fig.7.3a.最后，橫過切屑的剪切應力與材料的剪切強度相等，造成斷裂和分離。生成這類切屑時，切屑沿刀具面幾乎沒有相對運動，見圖7.3a。
Continuous chip.The continuous chip is characterized by a general flow of the separated metal along the tool face.There may be some cracking of the chip, but in this case it usually does not extend far enough to cause fracture.連續切屑：連續的切屑一般具有分離金屬沿刀具面流動的特征。切屑可能有一些破裂，但在這種情況下切屑通常不會延長到足以引起斷裂。
This chip is formed at the higher cutting speeds when machining ductile materials.There is little tendency for the material to adhere to the tool.The continuous chip usually shows a good cutting ratio and tends to produce the optimum surface finish, but it may become an operating hazard, Fig.7.3b.這種切屑形成于用較高切削速度機加工有延展性的材料時。材料幾乎沒有粘附刀具的傾向。連續切屑通常具有良好的切削率和趨向于產生最適宜的表面光潔度，但可能成為操作的危險之源，見圖7.3b。
Continuous with a built-up edge.This chip shows the existence of a localized, highly deformed zone of material attached or “welded” on the tool face.帶切屑瘤的連續切屑：這種切屑顯示了粘合或“焊接”在刀具面上材料局部高度變形區的存在。Actually, analysis of photomicrographs shows that this built-up edge is held in place by the static friction force until it becomes so large that the external forces acting on it cause it to dislodge, with some of it remaining on the machined surface and the rest passing off on the back side of the chip, Fig.7.3c.實際上，對顯微照片的分析顯示這種切屑瘤受到靜摩擦力抑制直至它變得大到作用在它上面的外力使其移動，一些留在機加工表面上而另一些延伸到切屑的背面，見圖7.3c。Shear Zone
剪切區
There are basically two schools of thought in the analysis of the metal removal process.One school of thought is that the deformation zone is very thin and planar as shown in Fig.7.4a.The other school thinks that the actual deformation zone is a thick one with a fan shape as shown in Fig.7.4b.在對金屬去除過程的分析中主要存在兩種思想學派。一種思想學派認為變形區如圖7.4a所示那樣非常薄而平坦。另一學派則認為真實變形區象圖7.4b所示那樣為一厚的帶有扇形的區域。
Though the first model(Fig.7.4a)is convenient from the point of analysis, physically it is impossible to exist.This is because for the transition from undeformed material to deform to take place along a thin plane, the acceleration across the plane has to be infinity.雖然第一種模型(圖7.4a)從分析的角度看是方便的，但實際上是不可能存在的。這是由于未變形的材料沿著剪切面發生變形，而且越過剪切面的加速度無窮大。
Similarly the stress gradient across the shear plane has to be very large to be practical.同樣在實際運用中越過剪切面的應力梯度必須很大才行。
In the second model(Fig.7.4b)by making the shear zone over a region, the transitions in velocities and shear stresses could be realistically accounted for.在第二種模型(圖7.4b)中讓剪力區分布于一個范圍，速度和剪應力的轉變能說明得更符合實際。
The angle made by the shear plane with the cutting speed vector, Φ is a very important parameter in metal cutting.Higher the shear angle better is the cutting performance.From a view of the Fig.7.4a, it can be observed that a higher rake angles give rise to higher shear angles.由剪切面和切削速度矢量形成的角度Φ在金屬切削中是一個十分重要的參數。剪切角越大，切削作業越好。從圖7.4a觀察，可以看到較大的前角能增大剪切角。Cutting Tool Materials切削刀具材料
Various cutting tool materials have been used in the industry for different applications.A number of developments have occurred in the current century.在工業中為了不同的應用可以使用各種各樣的切削刀具材料。在最近的百年里產生了許多進展。A large variety of cutting tool materials has been developed to cater to the variety of materials used in these programmes.Before we discuss the properties of these materials, let us look at the important characteristics expected of a cutting tool material.多種切削刀具材料被開發出來以滿足這些方案中使用材料的多樣性。討論這些材料性能之前，先看一下作為切削刀具材料應具備哪些重要特性。
1.Higher hardness than that of the workpiece material being machined, so that it can penetrate into the work material.2.Hot hardness, which is the ability of the material to retain its hardness at elevated temperatures in view of the high temperatures existing in the cutting zone.1.硬度要比被切削工件材料高，這樣它才能進入工件材料。
2.熱硬度，即材料由于存在于切削區的高溫而升溫時仍能保持其硬度的能力。
3.Wear resistance—The chip-tool and chip-work interfaces are exposed to such severe conditions that adhesive and abrasion wear is very common.The cutting tool material should therefore have high abrasion resistance to improve the effective life of the tool.3.耐磨性—切屑-刀具與切屑-工件的接觸界面處于如此嚴酷的狀態，粘附和磨損是很普遍的。因此切削刀具材料應具有高耐磨性以提高刀具的有效壽命。
4.Toughness—Even though the tool is hard, it should have enough toughness to withstand the impact loads that come in the beginning of cut or force fluctuations due to imperfections in the work material.This requirement is going to be more useful for the interrupted cutting, e.g.milling.4.韌性—雖然刀具是堅硬的，但也應有足夠的韌性以經受住沖擊載荷，這些載荷來自于切削的開始或由于工件材料的缺陷而產生的作用力波動。這個要求對如銑削之類的間斷切削更有用。
5.Low friction—The coefficient of friction between the chip and tool should be low.This would allow for lower wear rates and better chip flow.5.低摩擦系數—切屑與刀具間的摩擦系數應當較低。這會使磨損率較小及切屑流動更好。
6.Thermal characteristics—Since a lot of heat is generated at the cutting zone, the tool material should have higher thermal conductivity to dissipate this heat in the shortest time, otherwise the tool temperature would become high, reducing its life.6.熱特性—因為大量的熱產生在切削區，刀具材料應當具有較高的熱傳導性以在最短的時間內散發熱量，否則刀具溫度會升高，壽命會減少。
All these characteristics may not be found in a single tool material.Improved tool materials have been giving a better cutting performance.所有這些特性不可能存在于單一刀具材料中。改進的刀具材料已經被賦予較好的切削性能。Surface Finish
表面光潔度
Machining operations are utilized in view of the better surface finish that could be achieved by it compared to other manufacturing operations.由于機加工能獲得比其它制造作業更好的表面光潔度，所以機加工作業具有實用價值。
Thus it is important to know what would be the effective surface finish that can be achieved in a machining operation.The surface finish in a given machining operation is a result of two factors: 因而了解能在機加工作業中獲得怎樣的實際表面光潔度是重要的。給定機加工作業中的表面光潔度是兩個因素共同作用的結果：
(1)the ideal surface finish, which is a result of the geometry of the manufacturing process which can be determined by considering the geometry of the machining operation, and(2)the natural component, which is a result of a number of uncontrollable factors in machining, which is difficult to predict.理想的表面光潔度，是通過考慮機加工作業的幾何體系所決定的制造工藝幾何學的結果，和 自然要素，即在機加工中一些難以預測的不可控因素作用的結果。Ideal Surface Finish in Turning
The actual turning tool used would have a nose radius in place of the sharp tool point, which modifies the surface geometry as shown in Fig.7.5a.If the feed rate is very small, as is normal in finish turning, the surface is produced purely by the nose radius alone as shown in Fig.7.5.車削中的理想表面光潔度
實際使用的車削刀具有一個刀尖半徑取代鋒利刀尖，它將表面幾何形狀加工為如圖7.5a所示。如果進給率很小，象精車中很正常的那樣，工件表面則完全是由刀尖半徑單獨產生的，如圖7.5所示。
For the case in Fig.7.5, the surface roughness value is to be
Ra=8f2/(18R√3)Where: Ra is the surface roughness value
R is the nose radius
f is the feed rate
對圖7.5這種情況，表面粗糙度值為
Ra=8f2/(18R√3)式中：Ra是表面粗糙度值
R是刀尖半徑
f是進給率
The above are essentially geometric factors and the values represent an ideal situation.The actual surface finish obtained depends to a great extent upon a number of factors such as:
上述基本為幾何要素，其值代表了理想情況。而實際獲得的表面光潔度很大程度上還取決于下列一些因素：
(1)the cutting process parameter, speed, feed and depth of cut(2)the geometry of the cutting tool(3)application of cutting fluid(4)work and tool material characteristics(5)rigidity of the machine tool and the consequent vibrations.(1)切削工藝參數、速度、進給和切削深度(2)切削刀具的幾何形狀(3)切削液的運用
(4)工件和刀具的材料特性
(5)機床的剛度及其伴隨發生的振動
The major influence on surface finish is exerted by the feed rate and cutting speed.As the feed decreases, from the above equations, we can see that the roughness index decreases.對表面光潔度產生主要影響的是進給率和切削速度。從上述公式可以看到，隨著進給的減少，粗糙度指標會降低。
Similarly as the cutting speed increases, we have better surface finish.Thus while making a choice of cutting process parameters for finish, it is desirable to have high cutting speed and small feed rates.同樣隨著切削速度的增大，能得到較好表面光潔度。因此在為光潔度而選擇切削工藝參數時，采用較高的切削速度和較小的進給率是適當的。Cutting Fluids
切削液
The functions of cutting fluids(which are often erroneously called coolants)are: To cool the tool and workpiece To reduce the friction
切削液(經常誤稱為冷卻液)的功能如下： 冷卻刀具和工件 減少摩擦
To protect the work against rusting To improve the surface finish To prevent the formation of built-up edge To wash away the chips from the cutting zone 保護工件不生銹 改善表面光潔度 防止切屑瘤的形成 從切削區沖掉切屑
However, the prime function of a cutting fluid in a metal cutting operation is to control the total heat.This can be done by dissipating the heat generated as well as reducing it.The mechanisms by which a cutting fluid performs these functions are: cooling action and lubricating action.然而，在金屬切削作業中切削液的主要功能是控制總熱量。這可通過既散發又減少所產生的熱量來達到。切削液實現這些功能的機理是：冷卻作用和潤滑作用。
Cooling action.Originally it was assumed that cutting fluid improves the cutting performance by its cooling properties alone.That is why the name coolant was given to it.冷卻作用：最初設想切削液僅僅是通過冷卻特性來改善切削作業。這也是它曾被稱為冷卻液的原因。
Since most of the tool wear mechanisms are thermally activated, cooling the chip tool interface helps in retaining the original properties of the tool and hence prolongs its life.由于大多數刀具的磨損機理都是由熱引起的，冷卻切屑刀具接觸界面有助于保持刀具的原有特性，從而延長其使用壽命。
However, a reduction in the temperature of the workpiece may under certain conditions increase the shear flow stress of the workpiece, thereby decreasing tool life.It has been shown through a number of investigations that cooling in fact is one of the major factors in improving the cutting performance.可是工件溫度的降低在特定條件下會增加工件的剪切流動應力，從而降低刀具壽命。通過一些研究已經表明實際上冷卻只是改善切削作業的主要因素之一。
Lubricating action.The best improvement in cutting performance can be achieved by the lubricating action since this reduces the heat generated, thus reducing the energy input to the metal cutting operation.潤滑作用：切削作業的最大改善可通過潤滑作用來達到，由于它減少了熱量的產生因而減少了金屬切削作業的能量輸入。
However, if the cutting fluid is to be effective, it must reach the chip tool interface.But it is not easy to visualize how it is accomplished in the case of a continuous turning with a single point turning tool, specially when the chip-tool contact pressure is as high as 70 MPa.可是，如果要使切削液起作用就必須讓它到達切屑刀具接觸界面。但如何在采用單尖刀具連續車削的場合尤其是切屑-刀具接觸壓力高達70MPa時實現并非易事。
Merchant thought that minute asperities existed at the chip-tool interface and the fluid was drawn into the interface by the capillary action of the interlocking network of these surface asperities.Merchant認為：在切屑與刀具接觸界面上存在微小的粗粒，切削液通過這些表面的微小粗粒組成連鎖的網絡的毛細管被吸入到切屑與刀具的接觸界面上。
Unit8
Grinding is a manufacturing process that involves the removal of metal by employing a rotating abrasive wheel.The latter simulates a milling cutter with an extremely large number of miniature cutting edges.磨削是通過采用旋轉磨輪去除金屬的制造工藝。磨輪用非常大量的微型切削刃模仿銑刀進行切削。Generally, grinding is considered to be a finishing process that is usually used for obtaining high-dimensional accuracy and better surface finish.Grinding can be performed on flat, cylindrical, or even internal surfaces by employing specialized machine tools, which are referred to as grinding machines.一般而言，磨削被認為是一種通常用于獲得高尺寸精度和較好表面光潔度的精加工作業。磨削通過采用被稱為磨床的特殊機床能在平面、圓柱面甚至內表面上進行。
Obviously, grinding machines differ in construction as well as capabilities, and the type to be employed is determined mainly by the geometrical shape and nature of the surface to be ground, e.g., cylindrical surfaces are ground on cylindrical grinding machines.顯然，磨床根據結構和功能的不同有所區別，使用何種形式的磨床主要取決于被磨削表面的幾何形狀和物理性質。例如，圓柱面在外圓磨床上磨削。Type of Grinding Operations磨削作業的類型
1.Surface grinding.As the name surface grinding suggests, this operation involves grinding of flat or plane surfaces.Fig.8.1 indicates the two possible variations, either a horizontal or vertical machine spindle.1.表面磨削：就像其名稱暗示的那樣，表面磨削和平面磨削直接有關。圖8.1表示了兩種可能的變化：臥式磨床主軸或立式磨床主軸。
In the first case(horizontal spindle), the machine usually has a planer-type reciprocating table on which the workpiece is held.However, grinding machines with vertical spindles can have either a planer type table like that of the horizontal-spindle machine or a rotating worktable.在第一種情況(臥式主軸)，臥式磨床通常具有安裝工件的刨床式往復工作臺。而立式主軸磨床既可以像臥式主軸磨床那樣具有刨床式工作臺也可以具有旋轉工作臺。
Also, the grinding action in this case is achieved by the end face of the grinding wheel(Fig.8.1b), contrary to the case of horizontal-spindle machines, where the workpieces ground by the periphery of the grinding wheel.而且在這種情況下，磨削動作是通過砂輪端面完成的(圖8.1b)，這與通過砂輪周邊磨削工件的臥式主軸磨床正好相反。
Fig.8.1a and b also indicate the equations to be used for estimating the different parameters of the grinding operation, such as the machining time and the rate of metal removal.圖8.1a和b同時簡述了用于估計諸如加工時間和金屬去除率之類的磨削作業不同參數的方程式。During the surface-grinding operations, heavy workpieces are either held in fixtures or clamped on the machine table by strap clamps and the like, whereas smaller workpieces are usually held by magnetic chucks.在平面磨削時，重的工件用夾具固定或用壓板等夾緊在磨床工作臺上，而小的工件則通常是用電磁卡盤固定的。
2.Cylindrical grinding.In cylindrical grinding, the workpiece is held between centers during the grinding operation, and the wheel rotation is the source and cause for the rotary cutting motion, as shown in Fig.8.2.In fact, cylindrical grinding can be carried out by employing any of the following methods: 2.圓柱面磨削：在圓柱面磨削中，作業時工件支撐在兩頂尖之間，砂輪轉動是導致回轉切削運動的動力源，如圖8.2所示。實際上，圓柱面磨削能通過采用下列任意方法來實現：
(1)The transverse method, in which both the grinding wheel and the workpiece rotate and longitudinal linear feed is applied to enable grinding of the whole length.The depth of cut is adjusted by the cross feed of the grinding wheel into the workpiece.(1)橫向方法：這種方法中砂輪與工件均旋轉且采用線性縱向進給以保證能磨削整個長度。切削深度通過改變砂輪對工件的橫向進給來進行調整。
(2)The plunge-cut method, in which grinding is achieved through the cross feed of the grinding wheel and no axial feed is applied.As you can see, this method can be applied only when the surface to be ground is shorter than the width of the grinding wheel used.(2)插入-切削方法：這種方法通過砂輪的橫向進給完成磨削而不采用軸向進給。正如料想的那樣，這種方法只在要磨削表面比所用砂輪寬度短時才使用。
(3)The full-depth method, which is similar to the transverse method except that the grinding allowance is removed in a single pass.This method is usually recommended when grinding short rigid shafts.(3)全深度方法：這種方法除了一次加工就能去除磨削余量外其它與橫向方法相同。這種方法通常在磨削較短剛性軸時推薦使用。
Internal grinding.Internal grinding is employed for grinding relatively short holes, as shown in Fig.8.3.The workpiece is held in a chuck or a special fixture.Both the grinding wheel and the workpiece rotate during the operation and feed is applied in the longitudinal direction.內表面磨削：內表面磨削用于相對較短的孔，如圖8.3所示。工件安裝在卡盤或特殊夾具上。作業時砂輪和工件都回轉并且采用縱向進給。Any desired depth of cut can be obtained by the cross feed of the grinding wheel.A variation from this type is planetary internal grinding, which is recommended for heavy workpieces that cannot be held in chucks.通過砂輪的橫向進給能得到任意所需的切削深度。這種方法的一個變體是行星式內表面磨削，當工件較重不能用卡盤固定時推薦使用。
In that case, the grinding wheel not only spins around its own axis but also rotates around the centerline of the hole that is being ground.在這種情況下，砂輪不但繞自身軸線回轉，同時還繞被磨削孔的中心線旋轉。
Centerless grinding.Centerless grinding involves passing a cylindrical workpiece, which is supported by a rest blade, between two wheels, i.e., the grinding wheel and the regulating or feed wheel.無心磨削：無心磨削用于加工圓柱形工件，工件由托板支撐，在兩輪即砂輪和調節或進給輪之間通過去。
The grinding wheel does the actual grinding, while the regulating wheel is responsible for rotating the workpiece as well as generating the longitudinal feed.This is possible because of the frictional characteristics of that wheel, which is usually made of rubber-bonded abrasive.砂輪完成實際磨削，而調節輪負責旋轉工件和產生縱向進給。由于調節輪通常用橡膠粘結的磨料制成，其摩擦特性使這成為可能。
As can be seen in Fig.8.4, the axis of the regulating wheel is tilted at a slight angle with the axis of the grinding wheel.Consequently, the peripheral velocity of the regulating wheel can be resolved into two components, namely, workpiece rotational speed and longitudinal feed.正如在圖8.4中所看到的那樣，調節輪的軸與砂輪軸傾斜一個微小角度。因此調節輪的圓周速度可以分解為兩個分量，即工件回轉速度和縱向進給。These can be given by the following equations:
Vworkpiece＝Vregulating wheel×cosα
Axial feed＝Vregulating wheel×c×sinα
Where c is a constant coefficient to account for the slip between the workpiece and the regulating wheel(c=0.94~0.98).其值可由下列公式給出：
V工件＝V調節輪×cosα
軸向進給＝V調節輪×c×sinα
式中c是考慮工件和調節輪之間滑動的恒定系數(c=0.94~0.98)。
The velocity of the regulating wheel is controllable and is used to achieve any desired rotational speed of the workpiece.The angleαis usually taken from 1°to 5°and the larger the angle, the larger the longitudinal feed would be.調節輪的速度是可控的并被用于實現工件任意所需的轉動速度。α角通常取1到 5°，這角度越大則縱向進給也將越大。
Whenαis taken as 0°, i.e., the two axes of the grinding and regulating wheels are parallel, there is no longitudinal feed of the workpiece.當α取0°時，即砂輪和調節輪軸線平行時，則工件沒有縱向進給。Grinding Wheels 砂輪
Grinding wheels are composed of abrasive grains having similar size and a binder.The actual grinding process is performed by the abrasive grains.Pores between the grains within the binder enable the grains to act as separate single-point cutting tools.砂輪由具有相近尺寸的磨料顆粒和粘合劑組成。實際磨削作業由磨粒完成。在粘合劑中磨粒之間的孔隙使磨粒能象獨立的單刃切削刀具一樣工作。
These pores also provide space for the generated chips, thus preventing the wheel from clogging.In addition, pores assist the easy flow of coolants to enable efficient and prompt removal of the heat generated during the grinding process.這些孔隙同時還為產生的切屑提供空間以防砂輪堵塞。另外孔隙幫助冷卻液容易流動，從而使在磨削作業中產生的熱量能有效而迅速地散發。
Grinding wheels are identified based on their shape and size, kind of abrasive, grain size, binder, grade(hardness), and structure.砂輪根據它們的形狀和尺寸、磨料的類型、磨粒的大小、粘合劑、等級(硬度)和結構組織來分類。
Shape and size of grinding wheels.Grinding wheels differ in shape and size, depending upon the purpose for which they are to be used.Various shapes are shown in Fig.8.5 and include the following types:
砂輪的形狀和尺寸：根據砂輪的用途，它們的形狀和尺寸是不同的。各種形狀如圖8.5所示，其中包括：
1)Straight wheels used for surface, cylindrical, internal, and centerless grinding.2)Bevelled-face or tapered wheels used for grinding threads, gear teeth, and the like.3)Straight recessed wheels for cylindrical grinding and facing.1)用于表面、圓柱面、內部和無心磨削的直輪。2)用于磨削螺紋、齒輪輪齒之類的斜面或錐形輪。3)用于圓柱面和端面磨削的直凹輪。
4)Abrasive disks for cutoff and slotting operations.(thickness 0.02 up to 0.2in.(0.5 to 5mm)).5)Cylinders, straight cups, and flaring cups are used for surface grinding with the end face of the wheel.4)用于切斷和開槽作業的砂輪片(其厚度從0.02到0.2英寸(0.5到5毫米))。5)用其端面進行表面磨削的圓柱、直杯及外展杯狀砂輪。
The main dimensions of a grinding wheel are the outside diameter D, the bore diameter d, and the height H.These dimensions vary widely, depending upon the grinding process for which the wheel is to be used.砂輪的主要尺寸有外徑D、孔徑d和厚度H。根據采用砂輪的磨削工藝，這些尺寸變化很大。
Kind of abrasive.Grinding wheels can be made of natural abrasives such as quartz, emery, and corundum or of industrially prepared chemical compounds such as aluminum oxide or silicon carbide(known as carborundum).磨料的類型：砂輪可以由象石英、金剛砂、剛玉之類的自然磨料制成，或者由象氧化鋁或碳化硅(也稱人造金剛砂)之類的工業制備的化學化合物制成。
Generally, silicon carbide grinding wheels are used when grinding low-tensile-strength materials like cast iron, whereas aluminum oxide wheels are employed for grinding high-strength metals such as alloy steel, hardened steel, and the like.當磨削象鑄鐵類低拉伸強度材料時，一般采用碳化硅砂輪，而磨削合金鋼、淬火鋼等高強度金屬則要用氧化鋁砂輪。
Grain size of abrasive used.As you may expect, the grain size of the abrasive particles of the wheel plays a fundamental role in determining the quality of ground surface obtained.所用磨粒的尺寸：正如料想的那樣，砂輪磨粒的尺寸對決定所得磨削表面的質量起著根本的作用。The finer the grains, the smoother the ground surface is.Therefore, coarse-grained grinding wheels are used for roughing operations, whereas fine-grained wheels are employed in final finishing operations.磨粒越細，磨削表面越光滑。所以，粗粒砂輪用于粗加工，而細粒砂輪則用于最后精加工。
The grade of the bond.The grade of the bond is actually an indication of the resistance of the bond to pulling off the abrasive grains from the grinding wheel.Generally, wheels having hard grades are used for grinding soft materials and vice versa.粘結體的等級：粘結體的等級實際上是其抵抗將磨粒從砂輪上拉脫的指標。一般而言，具有較硬等級的砂輪用于磨削較軟材料，反之亦然。
If a hard-grade wheel were to be used for grinding a hard material, the dull grains would not be pulled off from the bond quickly enough, thus impeding the self-dressing process of the surface of the wheel and finally resulting in clogging of the wheel and burns on the ground surface.如果較硬等級的砂輪用于磨削較硬材料，磨鈍的磨粒將不能足夠快地脫離粘結體，這會妨礙砂輪表面的自修復，最終導致砂輪的堵塞并在被磨表面留下灼斑。
In fact, the cutting properties of all grinding wheels must be restored periodically by dressing with a cemented carbide roller or a diamond tool to give the wheel the exact desired shape and remove all worn abrasive grains.實際上，所有砂輪的磨削性能都必須定期地通過使用硬質合金滾輪或金剛石修整器修整而被恢復，以求很準確地把砂輪加工成要求的形狀，并去除已磨鈍的磨粒。
Structure.Structure refers to the amount of void space between the abrasive grains.When grinding softer metals, larger void space are needed to facilitate the flow of the removed chips.結構組織：結構組織與磨粒間的空隙量有關。當磨削較軟金屬時，需要較大的空隙以便去除切屑的流動。
The binder.Abrasive particles are bonded together in many different ways.These include bond, silicate, rubber, resinoid, shellac, and oxychloride.Nevertheless, the bond is the most commonly used one.粘合劑：磨粒可用多種不同方法粘結在一起。其中包括粘合劑、硅酸鹽、橡膠、樹脂、蟲膠和氯氧化物。然而，粘合劑是最常用的。
In fact, the standard marking system is employed for distinguishing grinding wheels, by providing all the preceding parameters in a specific sequence.在實際生產中，為了區分砂輪采用標準標注系統，通過用一特定順序將所有上述參數都表示出來。
Unit9 Lapping 研磨
Lapping is a finishing operation used on flat and cylindrical surfaces.The lap, shown in Fig.9.1a, is usually made of cast iron, copper, leather, or cloth.研磨是一種用于平面和圓柱面的精加工作業。研具，如圖9.1a所示，通常用鑄鐵、銅、皮革或布制成。
The abrasive particles are embedded in the lap, or they may be carried through slurry.Depending on the hardness of the workpiece, lapping pressures range from 7kPa to 140kPa(1 to 20 psi).研磨微粒嵌入研具內，或者可以通過液體攜帶。根據工件硬度，研磨壓力可在7kPa到140kPa(1到20psi)范圍中取。
Lapping has two main functions.Firstly, it produces a superior surface finish with all machining marks being removed from the surface.Secondly, it is used as a method of obtaining very close fits between mating parts such as pistons and cylinders.研磨有兩個主要作用。首先，它通過去除所有機加工痕跡能產生較好的表面光潔度。其次，它能用作獲得像活塞與氣缸之類配件間過盈配合的方法。
The lapped workpiece surface may look smooth but it is actually filled with microscopic peaks, valleys, scratches and pits.Few surfaces are perfectly flat.Lapping minimizes the surface irregularities, thereby increasing the available contact area.研磨后的工件表面可能看似平滑，其實布滿著微觀峰、谷、劃痕和凹陷。幾乎沒有表面是完全平整的。研磨使表面不規則最小化，因而增加了有效接觸面積。
The drawing in Fig.9.1a shows two surfaces.The upper one is how a surface might look before lapping and the lower one after lapping.Lapping removes the microscopic mountain tops and produces relatively flat plateaus.Entire microscopic mountain ranges may need to be ground down in order to increase the available contact area.圖9.1a上顯示了兩個表面。上面是研磨前表面可能的外觀模樣而下面則是研磨后的模樣。研磨去除了微觀峰頂從而產生相對平坦的平臺。整個微觀山脈范圍都需要磨去以增加有效接觸面積。
Production lapping on flat or cylindrical pieces is done on machines such as those shown in Fig.9.1b and 9.1c.Lapping is also done on curved surfaces, such as spherical objects and lenses, using specially shaped laps.研磨平面或圓柱面工件的生產過程是在如圖9.1b和9.1c那樣的機器上完成的。研磨也可采用特殊成型研具在諸如球形物體和透鏡之類的曲面上進行。Polishing
拋光
Polishing is a process that produces a smooth, lustrous surface finish.Two basic mechanisms are involved in the polishing process:(a)fine-scale abrasive removal, and(b)softening and smearing of surface layers by frictional heating during polishing.拋光是生成平滑、有光澤表面光潔度的工藝。拋光工藝涉及兩種基本機理：(a)精細等級磨粒去除，和(b)在拋光中通過摩擦生熱軟化并抹光表面層。Electropolishing
Electropolishing is an electrochemical process similar to, but the reverse of, electroplating.The electropolishing process smoothes and streamlines the microscopic surface of a metal object.Mirror-like finishes can be obtained on metal surfaces by electropolishing.電解拋光
電解拋光是一種與電鍍相似的電化學工藝，但過程與電鍍正好相反。電解拋光工藝使金屬物體的微觀表面平滑和簡單化。通過電解拋光能在金屬表面得到鏡面光潔度。
In electropolishing, the metal is removed ion by ion from the surface of the metal object being polished.Electrochemistry and the fundamental principles of electrolysis(Faraday’s Law)replace traditional mechanical finishing techniques.在電解拋光中，金屬是逐個離子地從被拋光金屬物體表面去除的。電化學和電解基本原理(Faraday定理)取代了傳統的機械精加工技術。
In basic terms, the object to be electropolished is immersed in an electrolyte and subjected to a direct electrical current.The object is maintained anodic, with the cathodic connection being made to a nearby metal conductor.用基本術語說，要電解拋光的物體被浸沒在電解液中并且通上直流電。該物體為陽極，陰極連接到附近的金屬導體上。
Smoothness of the metal surface is one of the primary and most advantageous effects of electropolishing.During the process, a film of varying thickness covers the surface of the metal.This film is thickest over micro depressions and thinnest over micro projections.金屬表面的平滑是電解拋光主要的和最有優勢的效應之一。在此過程中，一變化著厚度的膜覆蓋在金屬表面上。該膜在微觀凹陷處最厚而在微觀凸出處最薄。
Electrical resistance is at a minimum wherever the film is thinnest, resulting in the greatest rate of metallic dissolution.Electropolishing selectively removes microscopic high points or “peaks” faster than the rate of attack on the corresponding micro-depressions or “valleys”.電阻在膜最薄處最小，導致最大金屬分解率。電解拋光選擇性地去除微觀高點或“峰” 快于對相應微觀凹陷處或“谷”的侵蝕速率。
Stock is removed as metallic salt.Metal removal under certain circumstances is controllable and can be held to 0.0001 to 0.0025 mm.原材料以金屬鹽的形式被去除。在特定環境下金屬的去除是可控的并且保持在0.0001 到0.0025mm范圍內。
Chemical Mechanical Polishing
Chemical mechanical polishing is becoming an increasingly important step in the fabrication of multi-level integrated circuits.Chemical mechanical polishing refers to polishing by abundant slurry that interacts both chemically and mechanically with the surface being polished.化學機械拋光
化學機械拋光正在多層集成電路制造領域成為日益重要的步驟。化學機械拋光是指大量拋光液與被拋光表面產生化學和機械作用的拋光。
During the chemical mechanical polishing process, a rotating wafer is pressed face down onto a rotating, resilient polishing pad while polishing slurry containing abrasive particles and chemical reagents flows in between the wafer and the pad.在化學機械拋光過程中，旋轉晶片面向下壓在旋轉、有回彈力的拋光襯墊上，而同時含有研磨微粒和化學反應物的拋光液流過晶片與襯墊之間。
The combined action of polishing pad, abrasive particles and chemical reagents results in material removal and polishing of the wafer surface.Chemical mechanical polishing creates flat, damage-free on a variety of brittle materials and it is used extensively on silicon wafers in the manufacture of integrated circuits.拋光襯墊、研磨微粒和化學反應物的共同作用導致晶片表面的材料去除并拋光。化學機械拋光可使多種易碎材料平整且不受損害，因此在集成電路制造中被廣泛地用在硅晶片上。
Chemical mechanical polishing is a complicated multiphase process.It mainly includes the following two dynamics.First, the active component in polishing slurry reacts with the atoms of the wafer, and the process is chemical reaction step with oxidation-reductive reaction.化學機械拋光是一種復雜的多相工藝。它主要包括下列兩個動態過程：第一，拋光液中活性成分與晶片的原子發生反應，這是帶有氧化-還原反應的化學反應步驟。
The second step is the process of desorption, that is to say, the resultants gradually separate from the wafer
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