機械設(shè)計外文翻譯--車床和銑床

1、<p><b>　　附錄1</b></p><p>　　LATHES & MILLING</p><p>　　A shop that is equipped with a milling machine and an engine lathe can machine almost any type of product of suitable

2、 size.</p><p>　　The basic machines that are designed primarily to do turning，facing and boring are called lathes. Very little turning is done on other types of machine tools，and none can do it with equal fac

3、ility. Because lathe can do boring，facing，drilling，and reaming in addition to turning，their versatility permits several operations to be performed with a single setup of the workpiece. This accounts for the fact that lat

4、hes of various types are more widely used in manufacturing than any other machine tool. </p><p>　　Lathes in various forms have existed for more than two thousand years. Modern lathes date from about 1797，whe

5、n Henry Maudsley developed one with a leads crew. It provided controlled，mechanical feed of the tool. This ingenious Englishman also developed a change gear system that could connect the motions of the spindle and leads

6、crew and thus enable threads to be cut. </p><p>　　Lathe Construction. The essential components of a lathe are depicted in the block diagram of picture. These are the bed，headstock assembly，tailstock assembly

7、，carriage assembly，quick-change gearbox，and the leadscrew and feed rod. </p><p>　　The bed is the back bone of a lathe. It usually is made of well-normalized or aged gray or nodular cast iron and provides a h

8、eavy，rigid frame on which all the other basic components are mounted. Two sets of parallel，longitudinal ways，inner and outer，are contained on the bed，usually on the upper side. Some makers use an inverted V-shape for all

9、 four ways，whereas others utilize one inverted V and one flat way in one or both sets. Because several other components are mounted and/or move on the ways</p><p>　　The headstock is mounted in a fixed positi

10、on on the inner ways at one end of the lathe bed. It provides a powered means of rotating the work at various speeds. It consists，essentially，of a hollow spindle，mounted in accurate bearings，and a set of transmission gea

11、rs——similar to a truck transmission——through which the spindle can be rotated at a number of speeds. Most lathes provide from eight to eighteen speeds，usually in a geometric ratio，and on modern lathes all the speeds can

12、be obtained merely</p><p>　　Because the accuracy of a lathe is greatly dependent on the spindle，it is of heavy construction and mounted in heavy bearings，usually preloaded tapered roller or ball types. A <

13、;/p><p>　　long- itudinal hole extends through the spindle so that long bar stock can be fed through it. The size of this hole is an important size dimension of a lathe because it determines the maximum size of

14、bar stock that can be machined when the material must be fed through the spindle. </p><p>　　The inner end of the spindle protrudes from the gear box and contains a means for mounting various types of chucks，

15、face plates，and dog plates on it. Whereas small lathes often employ a threaded section to which the chucks are screwed，most large lathes utilize either cam-lock or key-drive taper noses. These provide a large-diameter ta

16、per that assures the accurate alignment of the chuck，and a mechanism that permits the chuck or face plate to be locked or unlocked in position without the necessity </p><p>　　Power is supplied to the spindle

17、 by means of an electric motor through a V-belt or silent-chain drive. Most modern lathes have motors of from 5 to15 horsepower to provide adequate power for carbide and ceramic tools at their high cutting speeds.</p&

18、gt;<p>　　The tailstock assembly consists，essentially，of three parts. A lower casting fits on the inner ways of the bed and can slide longitudinally thereon，with a means for clamping the entire assembly in any desi

19、red location. An upper casting fits on the lower one and can be moved transversely upon it on some type of keyed ways. This transverse motion permits aligning the tailstock and headstock spindles and provides a method of

20、 turning tapers. The third major component of the assembly is the tailstock </p><p>　　The carriage assembly provides the means for mounting and moving cutting tools. The carriage is a relatively flat H-shape

21、d casting that rests and moves on the outer set of ways on the bed. The transverse bar of the carriage contains ways on which the cross slide is mounted and can be moved by means of a feed screw that is controlled by a s

22、mall hand wheel and a graduated dial. Through the cross slide a means is provided for moving the lathe tool in the direction normal to the axis of rotation of </p><p>　　On most lathes the tool post actually

23、is mounted on a compound rest. This consists of abase，which is mounted on the cross slide so that it can be pivoted about a vertical axis，and an upper casting. The upper casting is mounted on ways on this base so that it

24、 can be moved back and forth and controlled by means of a short lead screw operated by a hand wheel and a calibrated dial. </p><p>　　Manual and powered motion for the carriage，and powered motion for the cr

25、oss slide，is provided by mechanisms within the apron，attached to the front of the carriage. Manual movement of the carriage along the bed is effected by turning a hand wheel on the front of the apron，which is geared to a

26、 pinion on the back side. This pinion engages a rack that is attached beneath the upper front edge of the bed in an inverted position.</p><p>　　To impart powered movement to the carriage and cross slide，a ro

27、tating feed rod is provided. The feed rod，which contains a keyway through out most of its length，passes through the two reversing bevel pinions and is keyed to them . Either pinion cam be brought into mesh with a </p&

28、gt;<p>　　mating bevel gear by means of the reversing lever on the front of the apron and thus provide “forward” or “reverse” power to the carriage. Suitable clutches connect either the rack pinion or </p>&

29、lt;p>　　the cross-slide screw to provide longitudinal motion of the carriage or transverse motion of cross slide.</p><p>　　For cutting threads，a second means of longitudinal drive is provided by a lead scr

30、ew. Whereas motion of the carriage when driven by the feed-rod mechanism takes place through a friction clutch in which slippage is possible，motion through the lead screw is by a direct，mechanical connection between the

31、apron and the lead screw. This is achieved by a split nut. By means of a clamping lever on the front of the apron，the split nut can be closed around the lead screw. With the split nut closed，the car</p><p>　

32、　Modern lathes have a quick-change gear box. The input end of this gearbox is driven from the lathe spindle by means of suitable gearing. The out put end of the gear box is connected to the feed rod and lead screw. Thus，

33、through this gear train，leading from the spindle to the quick-change gearbox，thence to the lead screw and feed rod，and then to the carriage，the cutting tool can be made to move a specific distance，either longitudinally o

34、r transversely，for each revolution of the spindle. A typical </p><p>　　Milling is a basic machining process in which the surface is generated by the progressive formation and removal of chips of material fro

35、m the workpiece as it is fed to a rotating cutter in a direction perpendicular to the axis of the cutter. .In some cases the workpiece is stationary and the cutter is fed to the work. In most instances a multiple-tooth c

36、utter is used so that the metal removal rate is high，and frequently the desired surface is obtained in a single pass of the work.</p><p>　　The tool used in milling is known as a milling cutter. It usually co

37、nsists of a cylindrical body which rotates on its axis and contains equally spaced peripheral teeth that intermittently engage and cut the workpiece. In some cases the teeth extend part way across one or both ends of the

38、 cylinder. </p><p>　　Because the milling principle provides rapid metal removal and can produce good surface finish，it is particularly well-suited for mass-production work，and excellent milling machines have

39、 been developed for this purpose. However，very accurate and versatile milling machines of a general-purpose nature also have been developed that are widely used in job-shop and tool and die work. A shop that is equipped

40、with a milling machine and an engine lathe can machine almost any type of product of suitable </p><p>　　Types of Milling Operations. Milling operations can be classified into two broad categories，each of whi

41、ch has several variations：</p><p>　　1.In peripheral milling a surface is generated by teeth located in the periphery of the cutter body；the surface is parallel with the axis of rotation of the cutter. Both f

42、lat and formed surfaces can be produced by this method. The cross section of the resulting surface corresponds to the axial contour of the cutter. This procedure often is called slab milling.</p><p>　　In fac

43、e milling the generated flat surface is at right angles to the cutter axis and is the </p><p>　　combined result of the actions of the portions of the teeth located on both the periphery and the </p>&

44、lt;p>　　with the face portions providing a finishing action.</p><p>　　The basic concepts of peripheral and face milling are illustrated in Fig. Peripheral milling operations usually are performed on machin

45、es having horizontal spindles，whereas face milling is done on both horizontal-and vertical-spindle machines.</p><p>　　Surface Generation in Milling. Surfaces can be generated in milling by two distinctly dif

46、ferent methods depicted in Fig. Note that in up milling the cutter rotates against the direction of feed the workpiece，whereas in down milling the rotation is in the same direction as the feed .As shown in Fig., the meth

47、od of chip formation is quite different in the two cases. In up milling the c hip is very thin at the beginning, where the tooth first contacts the work，and increases in thickness, be-coming </p><p>　　In dow

48、n milling，maximum chip thickness occurs close to the point at which the tooth contacts the work. Because the relative motion tends to pull the workpiece into the cutter，all possibility of looseness in the table feed scre

49、w must be eliminated if down milling is to be used. It should never be attempted on machines that are not designed for this type of milling. In as mush as the material yields in approximately a tangential direction at th

50、e end of the tooth engagement，there is much less tende</p><p>　　Sometimes a disadvantage of down milling is that the cutter teeth strike against the surface of the work at the beginning of each chip. When th

51、e workpiece has a hard surface，such as castings do，this may cause the teeth to dull rapidly.</p><p>　　Milling Cutters. Milling cutters can be classified several ways. One method is to group them into two bro

52、ad classes，based on tooth relief，as follows：</p><p>　　1. Profile-cutters have relief provided on each tooth by grinding a small land back of the cutting edge. The cutting edge may be straight or curved.</

53、p><p>　　2.In form or cam-relieved cutters the cross section of each tooth is an eccentric curve behind the cutting edge，thus providing relief. All sections of the eccentric relief，parallel with the cutting edge

54、，must have the same contour as the cutting edge. Cutters of this type are sharpened by grinding only the face of the teeth，with the contour of the cutting edge thus remaining unchanged. </p><p>　　

55、Another useful method of classification is according to the method of mounting the cutter. Arbor cutters are those that have a center hole so they can be mounted on an arbor. Shank cutters have either tapered or straight

56、 integral shank. Those with tapered shanks can be mounted directly in the milling machine spindle，whereas straight-shank cutters are held in a chuck. Facing cutters </p><p>　　usually are bolted to the end of

57、 a stub arbor.Types of Milling Cutters. Plain milling cutters are cylindrical or disk-shaped，having straight or helical teeth on the periphery. They are used for milling flat surfaces. This type of operation is called pl

58、ain or slab milling. Each tooth in a helical cutter engages the work gradually，and usually more than one tooth cuts at a given time. This reduces shock and chattering tendencies and promotes a smoother surface. Consequen

59、tly，this type of cutter usua</p><p>　　Interlocking slotting cutters consist of two cutters similar to side mills，but made to operate as a unit for milling slots. The two cutters are adjusted to the desired w

60、idth by inserting shims between them. </p><p>　　Staggered-tooth milling cutters are narrow cylindrical cutters having staggered teeth，and with alternate teeth having opposite helix angles. They are ground to

61、 cut only on the periphery，but each tooth also has chip clearance ground on the protruding side. These cutters have a free cutting action that makes them particularly effective in milling deep slots. Metal-slitting saws

62、are thin，plain milling cutters，usually from 1/32 to 3/16 inch thick，which have their sides slightly“dished”to provide cle</p><p><b>　　附錄2</b></p><p><b>　　車床和銑床</b></p&

63、gt;<p>　　車間里擁有一臺車床和一臺普通銑床就能加工出具有適合尺寸的各種產(chǎn)品。</p><p>　　用于車外圓、端面和鏜孔等加工的機床稱作車床。車削很少在其他種類的機床上進行，因為其他機床都不能像車床那樣方便地進行車削加工。由于車床除了用于車外圓外還能用于鏜孔、車端面、鉆孔和鉸孔，車床的多功能性可以使工件在一次定位安裝中完成多種加工。這就是在生產(chǎn)中普遍使用各種車床比其他種類的機床都要多的原因。

64、兩千多年前就已經(jīng)有了車床?，F(xiàn)代車床可以追溯到大約 1797年，那時亨利·莫德斯利發(fā)明了一種具有絲杠的車床。這種車床可以控制工具的機械進給。這位聰明的英國人還發(fā)明了一種把主軸和絲杠相連接的變速裝置，這樣就可以切削螺紋。圖中標(biāo)出了車床的主要部件：床身、主軸箱組件、尾架組件、拖板組件、變速齒輪箱、絲杠和光杠。床身是車床的基礎(chǔ)件。它通常是由經(jīng)過充分正火或時效處理的灰鑄鐵或者球墨鑄鐵制成，它是一個堅固的剛性框架，所有其他主要部件都安裝在

65、床身上。通常在床身上面有內(nèi)外兩組平行的導(dǎo)軌。一些制造廠生產(chǎn)的四個條導(dǎo)軌都采用倒“V ”形，而另一些制造廠則將倒“ V ”形導(dǎo)軌和平面導(dǎo)軌相結(jié)合。由于其他的部件要安裝在導(dǎo)軌上并（或）在導(dǎo)軌上移動，導(dǎo)軌要經(jīng)過精密加工，以保證其裝配精度。同樣地，在操作中應(yīng)該小心，以避免損傷導(dǎo)軌。</p><p>　　主軸的內(nèi)端從主軸箱中凸出，其上可以安裝多種卡盤、花盤和擋塊。而小型的車床常帶有螺紋截面供安裝卡盤之用。很多大車床使用偏心

66、夾或鍵動圓錐軸頭。這些附件組成了一個大直徑的圓錐體，以保證對卡盤進行精確地裝配，并且不用旋轉(zhuǎn)這些笨重的附件就可以鎖定或松開卡盤或花盤。主軸由電動機經(jīng) V 帶或無聲鏈裝置提供動力。大多數(shù)現(xiàn)代車床都裝有 5--15馬力的電動機，為硬質(zhì)合金和金屬陶瓷合金刀具提供足夠的動力，進行高速切削。尾座組件主要由三部分組成。底座與床身的內(nèi)側(cè)導(dǎo)軌配合，并可以在導(dǎo)軌上做縱向移動，底座上有一個可以使整個尾座組件夾緊在任意位置上的裝置。尾座安裝在底座上，可以沿鍵

67、槽在底座上橫向移動，使尾座與主軸箱中的主軸對中并為切削圓錐體提供方便。尾座組件的第三部分是尾座套筒，它是一個直徑通常在2--3英寸之間的鋼制空心圓柱軸。通過手輪和螺桿，尾座套筒可以在尾座體中縱向移入和移出幾英寸?；顒犹淄驳拈_口一端具有莫氏錐度，可以用于安裝頂尖或諸如鉆頭之類的各種刀具。通常在活動套筒的外表面刻有幾英寸長的刻度，以控制尾座的前后移動。鎖定裝置可以使套筒在所需要的位置上夾緊。拖板組件用于安裝和移動切削工具。拖板是一個相對平滑

68、</p><p>　　現(xiàn)代車床有一個變速齒輪箱，齒輪箱的輸入端由車床主軸通過合適的齒輪傳動來驅(qū)動。齒輪箱的輸出端與光杠和絲杠連接。主軸就是這樣通過齒輪傳動鏈驅(qū)動變速齒輪箱，再帶動絲杠和光杠，然后帶動拖板，刀具就可以按主軸的轉(zhuǎn)數(shù)縱向地或橫向地精確移動。一臺典型的車床的主軸每旋轉(zhuǎn)一圈，通過光杠可以獲得從 0.002到 0.118英寸尺寸范圍內(nèi)的 48種進給量；而使用絲杠可以車削從 1.5到92牙 /英寸范圍內(nèi)的 48

69、 種不同螺紋。一些老式的或價廉的車床為了能夠得到所有的進給量和加工出所有螺紋，必須更換主軸和變速齒輪箱之間的齒輪系中的一個或兩個齒輪。</p><p>　　銑削是機械加工的一個基礎(chǔ)方法。在這一加工過程中，當(dāng)工件沿垂直于旋轉(zhuǎn)刀具軸線方向進給時，在工件上形成并去除切屑從而逐漸地銑出表面。有時候，工件是固定的，而刀具處于進給狀態(tài)。在大多數(shù)情況下，使用多齒刀具，金屬切削量大，只需一次銑削就可以獲得所期望的表面。在銑削加工

70、中使用的刀具稱做銑刀。它通常是一個繞其軸線旋轉(zhuǎn)并且周邊帶有同間距齒的圓柱體，銑刀齒間歇性接觸并切削工件。在某些情況下，銑刀上的刀齒會高出圓柱體的一端或兩端。由于銑削切削金屬速度很快，并且能產(chǎn)生良好的表面光潔度，故特別適合大規(guī)模生產(chǎn)加工。為了實現(xiàn)這一目的，已經(jīng)制造出了質(zhì)量一流的銑床。然而在機修車間和工具模具加工中也已經(jīng)廣泛地使用了非常精確的多功能通用的銑床。車間里擁有一臺銑床和一臺普通車床就能加工出具有適合尺寸的各種產(chǎn)品。</p&g

71、t;<p>　　銑削操作類型：銑削操作可以分成兩大種類，每一類又有多種類型。1.圓周銑削在圓周銑削中，使用的銑刀刀齒固定在刀體的圓周面上，工件銑削表面與旋轉(zhuǎn)刀具軸線平行，從而加工表面。使用這種方法可以加工出平面和成型表面，加工中表面橫截面與刀具的軸向外輪廓相一致。這種加工過程常被稱為平面銑削。2.端面銑削銑削平面與刀具的軸線垂直，被加工平面是刀具位于周邊和端面的齒綜合作用形成的。刀具周邊齒完成銑削的主要任務(wù)，而端面齒用于精

72、銑。</p><p>　　圓周銑削和端面銑削的基本概念，圓周銑削通常使用臥式銑床，而端銑削則既可在臥式銑床又可以在立式銑床上進行。銑削面的形成：銑削時可以采用兩種完全不同的方法。應(yīng)注意，在逆銑時，銑刀旋轉(zhuǎn)方向與工件進給方向相反，而在順銑時銑刀旋轉(zhuǎn)與工件進給方向相同。在逆銑過程中，當(dāng)銑刀齒剛切入工件時，切屑是非常薄的，然后漸漸增厚，在刀齒離開工件的地方，切屑最厚。在兩種銑削方法中，切屑的形成是不同的，逆銑過程中，刀

73、具有推動工件并使工件從工作臺上提升的趨勢，這種作用有助于消除銑床工作臺進給螺桿和螺母間的間隙，從而形成平穩(wěn)的切削。然而，這種作用也有造成工件與夾緊裝置之間的松動的趨勢，這時應(yīng)施加更大的夾緊力。此外，銑削表面的平整度主要取決于切削刃的鋒利程度。順銑時，最大切屑厚度產(chǎn)生于靠近刀具與工件接觸點處。由于相對運動趨于把工件拉向銑刀，如果采用順銑法，要消除工作臺進給螺桿可能產(chǎn)生的松動。因此，對于不能用于順銑的銑床，不要采用順銑方法。因為在銑刀結(jié)束切

74、削時，處于切線方向的被切材料發(fā)生屈服，所以與逆銑相比，順銑的被加工表面沒有什么切痕。順銑的另一個優(yōu)勢是切削力趨于將工件壓緊在工作臺上，因此對工件的夾緊力可以小于逆銑。這一</p><p>　　銑刀分類有多種方法，一種方法是根據(jù)刀具后角將銑刀分為兩大類：1.仿形銑刀 每個刀齒在切削刃的背面磨了一個很小的棱面形成后角，切削刃可以是直線或曲線的。2.成形或凸輪形后角銑刀 每個齒的橫截面在切削刃的背面呈偏心曲線狀，以產(chǎn)生

75、后角。偏心后角的各面與切削刃平行，具有切削刃的相同形狀。這種類型的銑刀僅需磨削齒的前刀面就可以變得鋒利，只要切削刃的外形保持不變。銑刀的另一種分類方法是根據(jù)銑刀安裝的方法進行分類。心軸銑刀帶有一個中心孔以使銑刀安裝在心軸上。帶柄銑刀有一錐柄或直柄軸，含錐形軸柄的銑刀可以直接安裝在銑床的主軸上，而直柄軸的銑刀則是夾持在卡盤里。平面銑刀通常用螺栓固定在刀軸的末端上。根據(jù)這種分類方法，通用型的銑刀可分類如下：心軸銑刀：圓柱形銑刀，角度銑刀，側(cè)