外文翻譯--機(jī)床

1、<p>　　畢業(yè)設(shè)計(jì)(論文)外文資料翻譯</p><p>　　系　　部： 機(jī)械工程系 </p><p>　　專 業(yè)： 機(jī)械工程及自動(dòng)化 </p><p>　　姓 名： </p

2、><p>　　學(xué) 號(hào)： </p><p>　　外文出處： English For Electromechanical</p><p>　　Engineering </p><p>　　附 件： 1.外文資料翻譯譯文；2.外文原文。 </p&

3、gt;<p>　　注：請(qǐng)將該封面與附件裝訂成冊(cè)。</p><p>　　附件1：外文資料翻譯譯文 </p><p><b>　　機(jī) 床</b></p><p>　　機(jī)床是用于切削金屬的機(jī)器。工業(yè)上使用的機(jī)床要數(shù)車床、鉆床和銑床最為重要。其它類型的金屬切削機(jī)床在金屬切削加工方面不及這三種機(jī)床應(yīng)用廣泛。</p><p

4、>　　車床通常被稱為所有類型機(jī)床的始祖。為了進(jìn)行車削，當(dāng)工件旋轉(zhuǎn)經(jīng)過刀具時(shí)，車床用一把單刃刀具切除金屬。用車削可以加工各種圓柱型的工件，如：軸、齒輪坯、皮帶輪和絲杠軸。鏜削加工可以用來擴(kuò)大和精加工定位精度很高的孔。</p><p>　　鉆削是由旋轉(zhuǎn)的鉆頭完成的。大多數(shù)金屬的鉆削由麻花鉆來完成。用來進(jìn)行鉆削加工的機(jī)床稱為鉆床。鉸孔和攻螺紋也歸類為鉆削過程。鉸孔是從已經(jīng)鉆好的孔上再切除少量的金屬。</p&

5、gt;<p>　　攻螺紋是在內(nèi)孔上加工出螺紋，以使螺釘或螺栓旋進(jìn)孔內(nèi)。</p><p>　　銑削由旋轉(zhuǎn)的、多切削刃的銑刀來完成。銑刀有多種類型和尺寸。有些銑刀只有兩個(gè)切削刃，而有些則有多達(dá)三十或更多的切削刃。銑刀根據(jù)使用的刀具不同能加工平面、斜面、溝槽、齒輪輪齒和其它外形輪廓。</p><p>　　牛頭刨床和龍門刨床用單刃刀具來加工平面。用牛頭刨床進(jìn)行加工時(shí)，刀具在機(jī)床上往復(fù)

6、運(yùn)動(dòng)，而工件朝向刀具自動(dòng)進(jìn)給。在用龍門刨床進(jìn)行加工時(shí)，工件安裝在工作臺(tái)上，工作臺(tái)往復(fù)經(jīng)過刀具而切除金屬。工作臺(tái)每完成一個(gè)行程刀具自動(dòng)向工件進(jìn)給一個(gè)小的進(jìn)給量。</p><p>　　磨削利用磨粒來完成切削工作。根據(jù)加工要求，磨削可分為精密磨削和非精密磨削。精密磨削用于公差小和非常光潔的表面，非精密磨削用于在精度要求不高的地方切除多余的金屬。</p><p><b>　　車 床<

7、;/b></p><p>　　車床是用來從圓形工件表面切除金屬的機(jī)床，工件安裝在車床的兩個(gè)頂尖之間，并繞頂尖軸線旋轉(zhuǎn)。車削工件時(shí)，車刀沿著工件的旋轉(zhuǎn)軸線平行移動(dòng)或與工件的旋轉(zhuǎn)軸線成一斜角移動(dòng)，將工件表面的金屬切除。車刀的這種位移稱為進(jìn)給。車刀裝夾在刀架上，刀架則固定在溜板上。溜板是使刀具沿所需方向進(jìn)行進(jìn)給的機(jī)構(gòu)。用于操縱車床手柄可使車刀實(shí)現(xiàn)進(jìn)給，也可以借助專門的傳動(dòng)裝置實(shí)現(xiàn)自動(dòng)進(jìn)給。</p>

8、<p>　　車床的最大部件稱為床身，它的兩端分別裝有床頭箱和尾座。床身表面有專門的導(dǎo)軌，溜板和尾座可以在導(dǎo)軌上滑行。</p><p>　　車床的兩個(gè)頂尖分別裝在兩根主軸中：活頂尖裝在床頭箱主軸中，另一個(gè)死頂尖則裝在尾座的主軸中。</p><p>　　車床卡盤用于夾緊工件，其目的在于使工件在車削時(shí)不搖晃。通常，安裝在床頭箱主軸上的卡盤可具有不同的尺寸和結(jié)構(gòu)。如果工件是一完整的圓，可

9、將其夾緊在所謂的三爪通用卡盤中，卡盤的三個(gè)爪靠轉(zhuǎn)動(dòng)螺旋機(jī)構(gòu)能同時(shí)向中間移動(dòng)。但是如果工件系非完整的圓，則應(yīng)使用四爪相互獨(dú)立的四爪卡盤。</p><p>　　車床在車削不同材料和不同直徑的工件時(shí)，必須以不同的速度運(yùn)轉(zhuǎn)。裝在床頭箱內(nèi)的齒輪系統(tǒng)能使車床以不同的速度運(yùn)轉(zhuǎn)。</p><p>　　車床在車削工件前，它的頂尖要對(duì)準(zhǔn)，即兩個(gè)頂尖的軸線必須在同一直線上。</p><p&g

10、t;　　為檢驗(yàn)車床頂尖的同軸度，可進(jìn)行一次車削，然后用千分尺測(cè)量車削物的兩端。</p><p>　　并非所有的工件都必須裝夾在車床的兩個(gè)頂尖之間。短工件的車削可不使用死頂尖，而是簡(jiǎn)單的將其適當(dāng)夾緊在床頭箱的主軸上。 </p><p><b>　　鉆 頭 和 鉆 床</b></p><p>　　麻花鉆頭是一種高效率的刀具，它通常由扁鋼鍛造后扭轉(zhuǎn)出

11、凹槽，或由圓柱</p><p>　　棒料銑削而成，一般用高速鋼制作。高速鋼的成本雖然較高，但用它制作的刀具在耐熱性方面要比用普通工具鋼制作的刀具好得多。</p><p>　　麻花鉆可分做三個(gè)主要部分：鉆體、鉆柄和鉆尖。螺旋槽是位于鉆頭側(cè)面的螺旋形凹槽，鉆頭制成兩條、三條或四條螺旋槽。帶有三條或四條螺旋槽的鉆頭用于較小鉆頭鉆孔后繼續(xù)鉆孔的場(chǎng)合，或?qū)σ雁@好的孔進(jìn)行擴(kuò)孔，而不宜在實(shí)體坯料上鉆孔。

12、</p><p>　　螺旋槽主要有四個(gè)好處：</p><p>　?。?）螺旋槽使鉆頭的切削刃有正確的前角；</p><p>　?。?）螺旋槽可以卷緊切屑，使其占有最小的空間；</p><p>　?。?）螺旋槽可以構(gòu)成若干通道，切屑能借助這些通道從孔內(nèi)排出；</p><p>　　（4）螺旋槽可以使?jié)櫥瑒╉樌亓飨蚯邢魅小?/p>

13、</p><p>　　刃帶（棱邊）是螺旋槽切削刃上的狹帶。刃帶部分實(shí)際上是鉆頭的最大直徑處，它伸展到螺旋槽的全長(zhǎng)，它的表面是圓柱體的一部分。緊靠刃帶的鉆體部分其直徑略小于刃帶的直徑，減小的直徑稱做鉆體間隙。鉆體間隙用來減少鉆頭和孔壁間的摩檫，而刃帶則用來保證孔的準(zhǔn)確尺寸。</p><p>　　鉆頭的一端是鉆柄，它被安裝在鉆套、鉆床的主軸或鉆夾頭中。通常只有錐柄鉆頭才帶柄舌。</p&g

14、t;<p>　　鉆床是僅次于車床的最古老的機(jī)床，它的發(fā)明略遲于車床，它是一種最普通和最有用的機(jī)床。鉆床可分為三大類：立式鉆床、多軸鉆床和搖臂鉆床。立式鉆床有三種類型：重型鉆床、普通鉆床和高速手壓臺(tái)鉆。</p><p>　　鉆床除了鉆孔外，還可完成下列工作：如攻螺紋（加工內(nèi)螺紋）、鉸孔（用絞刀精加工孔）、尖底锪鉆、平底锪鉆、鏜孔和锪端面等。</p><p><b>　

15、　銑 床</b></p><p>　　銑床是一種當(dāng)工件向銑刀進(jìn)給時(shí)，銑刀旋轉(zhuǎn)著從工件表面切除金屬的機(jī)床。銑刀安裝在刀桿上并由襯套或軸套定位。刀桿的一端安裝在主軸上，而另一端則可在安裝在刀桿支架的軸承里旋轉(zhuǎn)。</p><p>　　銑刀通常有高速鋼制成，有不同的尺寸和形狀。銑刀可分為圓柱銑刀、立銑刀（銑端面）、成形銑刀、角度銑刀、三面刃銑刀、鋸片銑刀等。這些銑刀的銑削方向可能不同，

16、例如，在切削時(shí)，它們可以順時(shí)針轉(zhuǎn)動(dòng)，也可以逆時(shí)針轉(zhuǎn)動(dòng)。</p><p>　　在銑床可以加工規(guī)則的或不規(guī)則的工件，銑床結(jié)構(gòu)的不同取決于要加工工件的類型特點(diǎn)。根據(jù)主軸的位置，銑床可分為立式銑床和臥式銑床兩大類。銑床可分為許多種。</p><p>　　根據(jù)總體結(jié)構(gòu)的不同，銑床可分為升降臺(tái)式銑床、專用銑床、龍門銑床；根據(jù)工作臺(tái)的結(jié)構(gòu)，銑床可分為萬能銑床和普通銑床。</p><p

17、>　　銑床主要的零部件有啟動(dòng)手柄、主軸、立柱、升降臺(tái)、升降螺桿、工作臺(tái)、分度臺(tái)、調(diào)速手柄、進(jìn)給手柄、工作臺(tái)移動(dòng)手柄、床身和刀桿支架。</p><p>　　銑床主軸由電動(dòng)機(jī)通過安裝在立柱里的一系列齒輪驅(qū)動(dòng)。普通銑床的工作臺(tái)只能沿垂直于主軸的方向運(yùn)動(dòng)，而萬能銑床在銑削輪齒、螺紋等時(shí)，工作臺(tái)可以在橫向滑板上轉(zhuǎn)動(dòng)。</p><p>　　銑床上所用的各種附件增加了銑床的加工范圍。</p&

18、gt;<p>　　分度頭是一種在工件圓周方向上進(jìn)行等分，以及切削時(shí)把工件夾持在所需位置的裝置。</p><p>　　銑床用各種虎鉗來夾持工件，最常見的是平口鉗及旋轉(zhuǎn)座虎鉗。</p><p><b>　　龍 門 刨 床</b></p><p>　　龍門刨床是用于往復(fù)切削運(yùn)動(dòng)的最大的機(jī)床之一。它在一連竄的直線切削過程中加工平面或成形面

19、。龍門刨床的加工效率高于牛頭刨床。</p><p>　　龍門刨床上的工件裝在工作臺(tái)上，并在刨刀下面做往復(fù)運(yùn)動(dòng)，刨刀裝在橫軌上。龍門刨床的床身一定要比工作臺(tái)長(zhǎng)一倍左右，以便工作臺(tái)在行程中的每一個(gè)位置都得到支承。雙立柱龍門刨床有兩根立柱，用來支承橫軌的兩端。單立柱龍門刨床只在一邊有立柱。單立柱龍門刨床適用于那些寬度超過兩立柱間距離的工件。然而，雙立柱龍門刨床剛性較高。</p><p>　　有一

20、些以前用龍門刨床加工的工件，現(xiàn)在可用龍門銑床加工，因?yàn)榍罢叩男什蝗绾笳吒摺２贿^，還是有許多工件在龍門刨床上加工比在其它機(jī)床上加工更為有利和經(jīng)濟(jì)。例如，斜面通常在龍門銑床上加工較為容易。狹長(zhǎng)表面的加工用龍門刨床也最為有效。此外，龍門刨床常用來在表面粗糙的鍛件和鑄件上進(jìn)行重要的初切，以便為后面的加工建立一個(gè)基準(zhǔn)面。</p><p><b>　　磨 床</b></p><p&

21、gt;　　磨削，或研磨加工，是制造業(yè)發(fā)展最快的金屬切削方法。很多以前由傳統(tǒng)銑床，車床和刨床作的機(jī)械加工作業(yè)，現(xiàn)在由各種磨床來完成。</p><p>　　磨床的總類很多。常見的有刀具磨床、普通磨床、無心磨床、外圓磨床、內(nèi)圓磨床及工具磨床。</p><p>　　在磨床上可進(jìn)行五種類型的磨削：</p><p>　?。?）平面磨削。平面磨削是用于加工平面，角平面和不規(guī)則的表

22、面。在平面磨削過程中，砂輪在軸上旋轉(zhuǎn)，工件安裝在一個(gè)往復(fù)移動(dòng)或轉(zhuǎn)動(dòng)的工作臺(tái)上，工件被帶動(dòng)與砂輪互相接觸。</p><p>　?。?）外圓磨削。外圓磨削是磨削圓柱體的外表面的過程。這些表面可以是圓柱面的，圓錐形的和外輪廓曲面。外圓磨削操作類似車床車削的操作。當(dāng)工件是很硬或當(dāng)需要極高精度和較高光潔度時(shí)，外圓磨削可代替車床。工件旋轉(zhuǎn)，砂輪與工件旋轉(zhuǎn)方向相反且轉(zhuǎn)速更快，被帶到與工件接觸的部件。工件與工作臺(tái)往復(fù)運(yùn)動(dòng)，當(dāng)與砂

23、輪接觸就對(duì)材料進(jìn)行磨削。</p><p>　?。?）無心外圓磨削。無心外圓磨床運(yùn)行不需要中心孔或夾緊裝置。在無心外圓磨床上，工件停在靜止的刀形托板上，且被另一個(gè)稱為導(dǎo)輪的輪子支撐著。在刀形支撐上，砂輪推動(dòng)工件向下，且靠在調(diào)節(jié)輪上。調(diào)節(jié)輪經(jīng)常用橡膠結(jié)合耐磨材料做成，旋轉(zhuǎn)的方向與主動(dòng)輪相同，同時(shí)當(dāng)實(shí)質(zhì)一個(gè)微小的傾斜角度時(shí)，能控制工件的縱向進(jìn)給。改變這個(gè)角度和砂輪的速度，工件的進(jìn)給速度也能改變。</p>

24、<p>　?。?）內(nèi)圓磨床。內(nèi)圓磨床是被用于完成精準(zhǔn)的圓柱形的，圓錐形的和成形孔的加工。大多數(shù)通用的內(nèi)圓磨床的操作與車床上的鏜孔操作非常相似。工件是被工件夾具所夾持，工件夾具通常是卡盤或套爪卡盤夾緊由主軸箱驅(qū)動(dòng)旋轉(zhuǎn)。一臺(tái)單獨(dú)的電動(dòng)機(jī)與工件同一個(gè)方向驅(qū)動(dòng)砂輪旋轉(zhuǎn)。它能進(jìn)退工件也能調(diào)整切削深度。</p><p>　?。?）特種磨削加工。特種磨床是加工特殊類型的工件及具有特殊操作功能的磨削設(shè)備。比較常見的特殊

25、種類概括如下：</p><p>　　工具和刀具磨床：人們?cè)O(shè)計(jì)這些磨削機(jī)床以鋒利銑刀，絞床，絲攻和其他的機(jī)械切割刀具。</p><p>　　一般的刀具磨床是最通用萬能的刀具磨削機(jī)床。其各種配件能使絕大多數(shù)的切割刀具變得鋒利。</p><p>　　坐標(biāo)磨床：坐標(biāo)磨床機(jī)開發(fā)是用來定位和精確磨削錐形和圓柱形的孔。坐標(biāo)磨床機(jī)有一個(gè)能安裝和驅(qū)動(dòng)砂輪的高速立軸。和坐標(biāo)鏜床一樣，它

26、們使用相同的精確定位系統(tǒng)。</p><p>　　螺紋磨床：這種特殊磨削機(jī)與外圓磨削機(jī)相似。它們有一個(gè)精確的引導(dǎo)絲桿以便在工件上加工出正確的螺距或?qū)С?。螺紋磨床還可加工及精修砂輪的切削面，以便在工件上加工出精確的螺旋線。</p><p><b>　　鏜 床</b></p><p>　　鏜孔也可以稱為內(nèi)車削，是增大圓孔內(nèi)徑的方法。鏜削之前的孔是鉆孔

27、或在鑄件上的一個(gè)孔。</p><p>　　鏜孔有以下三個(gè)目的：</p><p>　?。?）達(dá)到尺寸：鉆孔可以得到合適精度的孔。</p><p>　?。?）直線度：鏜孔能提高原有鑿的孔和鑄件的直線度。</p><p>　　（3）同心度：受卡盤和夾具的精度影響鏜削會(huì)使孔和外圓柱偏心。</p><p>　　鏜削工序一般分兩步

28、完成，即粗鏜和精鏜。粗鏜工序的目的是快速、高效地去除多余的金屬；而精鏜工序的目的是獲得所需的尺寸、光潔表面度和孔的位置?？椎某叽缤ㄟ^使用試切割程序而獲得。孔的直徑可以用內(nèi)卡尺和千分尺測(cè)量。測(cè)量?jī)x表或內(nèi)千分尺可用于直接測(cè)量直徑。</p><p>　　肩、溝槽、輪廓、錐度和螺紋也應(yīng)該在孔內(nèi)鏜出。內(nèi)槽是用與外部開槽工具相似的工具切削。鏜削內(nèi)槽的步驟非常類似于車削肩部的步驟。大的肩部使用前導(dǎo)裝置定位的鏜孔工具進(jìn)行刮削，使

29、用橫向滑板進(jìn)給刀具。內(nèi)部輪廓使用車床上的描摹附件加工。仿形板附件安裝在橫向滑板上，靠模指跟隨標(biāo)準(zhǔn)剖面樣板的輪廓線運(yùn)動(dòng)。這種刀具以對(duì)應(yīng)于標(biāo)準(zhǔn)剖面樣板的輪廓線的路徑進(jìn)行移動(dòng)。這樣標(biāo)準(zhǔn)剖面樣板的輪廓就在孔內(nèi)得到復(fù)制。標(biāo)準(zhǔn)剖面樣板精確安裝在一個(gè)專用的滑板上，滑板可以在兩個(gè)方向上進(jìn)行精確調(diào)整以使刀具與工件以正確的關(guān)系對(duì)正。正常的車削是在主軸逆時(shí)針轉(zhuǎn)動(dòng)時(shí)進(jìn)行的；鏜削是在主軸順時(shí)針方向或“向后”轉(zhuǎn)動(dòng)時(shí)進(jìn)行的。</p><p>

30、　　附件2：外文原文（復(fù)印件）</p><p>　　Machine Tools</p><p>　　Machine Tools are machines for cutting metals.The most important of machine tools used in industry are lathes,drilling machines and milling machin

31、es.Other kinds of metal working machines are not so widely used in machining metals as these three.</p><p>　　The lathe is commonly called the father of the entire machine tool family.For turning operations,t

32、he lathe uses a single point cutting tool,which removes metal as it travels past the revolving work-piece.Turning operations are required to make many different cylindrical shapes,such as axes,gear blanks,pulleys,and thr

33、eaded shafts.Boring operations are performed to enlarge,finish,and accurately locate holes.</p><p>　　Drilling is performed with a rotating tool called a drill.Most drilling in metal is done with a twist dril

34、l.The machine used for drilling is called a drill press.Operations,such as reaming and tapping,are also classified as drilling.Reaming consists of removing a small amount of metal form a hole already drilled.</p>

35、<p>　　Tapping is the process of cutting a thread inside a hole so that a cap screw or bolt may be threaded into it.</p><p>　　Milling removes metal with a revolving,multiple cutting edge tools called mil

36、ling cutter.Milling cutters are made in many styles and size.Some have as few as two cutting edges and others have 30 or more.Milling can produce flat,angled surfaces,groves,slots,gear teeth,and other profiles,depending

37、on the shape of the cutters being used.</p><p>　　Shaping and planing produce flat surfaces with a single point cutting tool.In shaping,the cutting tool on a shaper reciprocates or moves back and forth while

38、the work is fed automatically towards the tool.In planing,the work-piece is attached to a worktable that reciprocates past the cutting tool.The cutting tool is automatically fed into the work-piece a small amount on each

39、 stroke.</p><p>　　Grinding makes use of abrasive particles to do the cutting.Grinding operations may be classified as precision or non-precision,depending on the purpose.Precision grinding is concerned with

40、grinding to close tolerances and very smooth finish.Non-precision grinding involves the removals of metal where accuracy is not important.</p><p><b>　　Lathe </b></p><p>　　A lathe is

41、a machine tool for cutting metal form the surface of a round work fastened between the two lathe centers and turning around its axis.In turning the work a cutter moves in the direction parallel to the axis of rotation of

42、 the work or at an angle to this axis,cutting off the metal from the surface of the work.This movement of the cutter is called the feed.The cutter is clamped in the tool post which is mounted on the carriage.The carriage

43、 is the mechanism feeding the cutter in the neede</p><p>　　The largest part of the lathe is called the bed on which the headstock and the tailstock are fastened at opposite ends.On the upper part of the bed

44、there are special ways upon which the carriage and the tailstock silde.</p><p>　　The two lathe centers are mounted in two spindles:one(the live center)is held in the headstock spindle,while the other (the de

45、ad center)in the tailstock spindle.</p><p>　　The lathe chuck is used for chucking the work,which is for clamping it so that it will rotate without wobbling while turning.The chuck,usually,mounted on the head

46、stock spindle,may have different sizes and construction.If the work is perfectly round,it may be chucked in the so-called three-jaw universal chuck,all the jaws of which are moved to the center by turning the screw.But i

47、f the work is not perfectly round,the four-jaw independent chuck should be used.</p><p>　　In turning different materials and works of different diameters,lathes must be run at different speeds.The gearbox co

48、ntained in the headstock makes it possible to run the lathe at various speeds.</p><p>　　Before turning a work in the lathe,the lathe centers are to be aligned;that means that the axes of both centers must be

49、 on one line.</p><p>　　The alignment of the lathe center may be tested by taking a cut and then measuring both ends of the cut with a micrometer,</p><p>　　Not all works should be fastened betwee

50、n the two centers of the lathe.A short work may be turned without using the dead center,by simply chucking it properly at the spindle of the headstock.</p><p>　　Drills and Drilling Machines</p><p&

51、gt;　　The twist drill is a very efficient tool.It is generally formed by forging and twisting grooves in a flat strip of steel or by milling a cylindrical piece of steel,high-speed steel being commonly used.High-speed ste

52、el costs more but tools made of it withstand heat much better than those made of ordinary tool steel.</p><p>　　The twist drill may be divided into three principal parts:body,shank,and point.The flutes are th

53、e spiral grooves that are formed on the side of a drill,drills being made with two,three,or four flutes.Those having three or four flutes are used for following smaller drills or for enlarging holes already drilled,and a

54、re not suited for drilling into solid stock.</p><p>　　Spiral flutes have four main advantages:</p><p>　　(1) They give the correct rake to the lip of a drill.</p><p>　　(2) They cause

55、 the chip to curl so tightly that it occupies the minimum amount of space.</p><p>　　(3) They form channels through which chips escape from the hole.</p><p>　　(4) They allow the lubricant to flow

56、 easily down to the cutting edge.</p><p>　　The margin is the narrow strip on the cutting edge of the flute.It is practically the full diameter of the drill and extends the entire length of the flute,its surf

57、ace being a part of a cylinder.The portion of the body next to the margin is of less diameter than the margin.This lessened diameter,called body clearance,reduces the friction between the drill and the walls of the hole,

58、while the margin insures the hole being of accurate size.</p><p>　　The shank is the end of the drill which fits into the socket,spindle,or chuck of the drill press.The tang is usually found only on tapered s

59、hank tools.</p><p>　　The drilling machine is the second oldest machine tools,having been invented shortly after the lathe,and is one of the most common and useful machines.The drilling machines may be classi

60、fied into three general types:vertical spindle,multiple spindle,and radial spindle machine.The vertical spindle drilling machine comes in three types:heavy duty,plain,and sensitive.</p><p>　　Besides the dril

61、ling of holes,such operations may be performed on the drilling machine:drilling,tapping(internal threading),reaming(finishing the hole with a reamer),countersinking,counterboring,boring and spot-facing.</p><p&

62、gt;　　Milling Machines</p><p>　　The milling machine is a machine that removes metal from the work with a revolving milling cutter as the work is fed against it.The milling cutter is mounted on an arbor where

63、it is held in place by spacers or bushing.The arbor is fixed in the spindle with one end,while the other end of the arbor rotates in the bearing mounted on the arbor yoke.</p><p>　　The milling cutter are gen

64、erally made from high speed steel and are available in different sizes and shapes.There are such kinds of milling cutters as cylindrical cutters,end milling cutters(for face milling),from milling cutters,angular,side and

65、 face cutter,slitting saw,ect.These cutters may differ in the direction of their operation,i.e.they may cut revolving either clockwise or counter-clockwise.</p><p>　　Regular or irregular shaped work may be p

66、roduced on a milling machine,designs varying according to the particular class of work wanted.According to the position of the spindle,the milling machines may be divided into two groups of vertical spindle milling machi

67、nes and horizontal spindle milling machines.Milling machines may be grouped into various classes.</p><p>　　According to the variation in general design as the"column and knee type",the manufacturin

68、g types,and the planner type of milling machine.According to the table design,the milling machines may be classified as universal and plain milling machines.</p><p>　　The most important parts of the milling

69、machine are starting levers,spindle,column,knee,elevating screw,table,index head,speed levers,feed movement,table movement levers,foot stock,arbor yoke.</p><p>　　The spindle of the milling machine is driven

70、by an electric motor through a train of gears mounted in the column.The table of the plain milling machine may travel only at right angles to the spindle,while the universal milling machine is provided with a table that

71、may be swiveled on the transverse slide for milling gear teeth,threads,ect.</p><p>　　Various attachments are used for increasing the range of work that can be performed on a milling machine.</p><p

72、>　　The dividing head(also called an index head)is a device used to divide the periphery of a piece of work into any number of equal parts,and to hold the work in the required position while the cuts are being made.<

73、;/p><p>　　Various kinds of vises may be used for holding the work in a milling machine,the most common being the plain vise,and the swivel vise.</p><p>　　The Planer</p><p>　　The plane

74、r is one of the biggest machine tools that employ a reciprocating cutting action.It generates flat or contoured surfaces in a series of straight cuts.Its efficiency is higher than that of the shaper.</p><p>

75、　　The work on the planer is held on the machine table and moves under the tool which is carried on the rail.The bed must be approximately twice as long as the table to support it at all positions during the stroke.The do

76、uble-housing on one side only.Open-side planers are designed for work-pieces which are so wide that they can pass between the housings of double-housing planers.The double-housing machine,however,offers greater rigidity.

77、</p><p>　　Some of the work that was formerly done on the planer is now done on the planer-type milling machine since the former is not so efficient as the latter.However,there are still many jobs that can be

78、 carried out better and more economically on the planer than on any other machines.For example,angular surfaces are often easier to machine on a planer.Planning is also most effective in the machining of long and narrow

79、surfaces.In addition,the planer usually takes the important first cut on the rough </p><p>　　Grinding Machines</p><p>　　Grinding,or abrasive machine,is one of the most rapidly growing metal rem

80、oval processes in manufacturing.Many machining operations,previously done on conventional milling machines,lathes and shapers,are now performed on various types of grinding machines.</p><p>　　There is a grea

81、t variety of grinding machines.The machines that are generally used are cutter grinder,surface grinder,centerless grinder,external grinder,internal grinder,and tool grinder.</p><p>　　Five types of grinding o

82、perations are performed on grinding machines:</p><p>　　（1）Surface grinding.Surface grinding are used to produce flat,angular and irregular surfaces.In the surface grinding process,the grinding wheel revolves

83、 on a spindle;and the workpiece,mounted on either a reciprocating or a rotary table,is brought into contact with the grinding wheel.</p><p>　　（2）Cylindrical grinding.Cylindrical grinding is the process of gr

84、inding the outside surface of a cylinder.These surfaces may be straight,tapered or contoured.Cylindrical grinding operations resemble lathe turning operations.They replace the lathe when the workpiece is hardened or when

85、 extreme accuracy and superior finish are required.As the workpiece revolves,the grinding wheel,rotating much faster in the opposite direction,is brought into contact with the part.The workpiece and table reciprocat</

86、p><p>　?。?）Centerless grinding.Centerless grinding machines eliminate the need to have center holes for the work or to use workholding devices.In centerless grinding,the workpiece rests on a workrest blade and

87、is backed up by a second wheel,called the regulating wheel.The rotation of the grinding wheel pushes the workpiece down on the workrest blade and against the regulating wheel.The regulating wheel,usually made of a rubber

88、 bonded abrasive,rotates in the same direction as the grinding wheel and contr</p><p>　?。?）Internal grinding.Internal grinders are used to accurately finish straight,tapered or formed holes.The most popular

89、internal grinder is similar in operation to a boring operation in a lathe.The work-piece is held by a workholding device,usually a chuck or collet,and revolved by a motorized headstock.A separate motor head in the same d

90、irection as the workpiece revolves the grinding wheel.It can be fed in and out of the work and also adjusted for depth of cut.</p><p>　?。?）Special grinding processes.Special types of grinders are grinding ma

91、chines made for specific types of work and operations.A brief description of the more commonly used special types follows:</p><p>　　Tool and cutter grinders:There grinding machines are designed to sharpen mi

92、lling cutters,reamers,taps and other machine tool cutters.</p><p>　　The general purpose cutter grinder is the most popular and versatile tool grinding machine.Various attachments are available for sharpening

93、 most types of cutting tools.</p><p>　　Jig grinding machines:Jig grinders were developed to locate and accurately grind tapered or straight holes.Jig grinders are equipped with a high speed vertical spindle

94、for holding and driving the grinding wheel.They utilize the same precision locating system as do jig borers.</p><p>　　Thread grinding machines:These are special grinders that resemble the cylindrical grinder

95、.They must have a precision lead screw to produce the correct pitch,or lead,on a threaded part.Thread grinding machines also have a means of dressing or truing the cutting periphery of the grinding wheel so that it will

96、produce a precise thread form on the part.</p><p>　　Boring Machine</p><p>　　Boring,also called internal turning,is used to increase the inside diameter of a hole.The original hole is made with a

97、 drill,or it may be a cored hole in a casting.Boring achieves three things:</p><p>　　Sizing:Boring brings the hole to the proper size and finish.</p><p>　　Straightness:Boring will straighten the

98、 original drilled or cast hole.</p><p>　　Concentricity:Boring will make the hole concentric with the outside diameter within the limits of the accuracy of the chuck or holding device.</p><p>　　T

99、he boring operation is generally performed in two steps;namely,rough boring and finish boring.The objective of the rough-boring operation is to remove the excess metal rapidly and efficiently,and the objective of the fin

100、ish boring operation is to obtain the desired size,surface finish,and location of the hole .The size of the hole is obtained by using the trial-cut procedure.The diameter of the hole can be measured with inside calipers

101、and outside micrometer calipers.Basic Measuring Instruments</p><p>　　Shoulders,grooves,contours,taper,and threads are also bored inside of holes.Internal grooves are cut using a tool that is similar to an ex

102、ternal grooving tool.The procedure for boring internal shoulders is very similar to the procedure for turning shoulders.Large shoulders are faced with the boring tool positioned with the nose leading,and using the cross