外文翻譯--軸

1、<p><b>　　附錄：</b></p><p><b>　　外文資料與中文翻譯</b></p><p><b>　　外文資料：</b></p><p><b>　　Shaft</b></p><p>　　Solid shafts. As a

2、 machine component a shaft is commonly a cylindrical bar that supports and rotates with devices for receiving and delivering rotary motion and torque .The crankshaft of a reciprocating engine receive its rotary motion fr

3、om each of the cranks, via the pistons and connecting roads (the slider-crank mechanisms), and delivers it by means of couplings, gears, chains or belts to the transmission, camshaft, pumps, and other devices. The camsha

4、fts, driven by a gear or chain from the </p><p>　　An axle is usually defined as a stationary cylindrical member on which wheels and pulleys can rotate, but the rotating shafts that drive the rear wheels of

5、an automobile are also called axles, no doubt a carryover from horse-and-buggy days. It is common practice to speak short shafts on machines as spindles, especially tool-carrying or work-carrying shafts on machine tools.

6、</p><p>　　In the days when all machines in a shop were driven by one large electric motor or prime mover, it was necessary to have long line shafts running length of the shop and supplying power, by belt, to

7、 shorter couter shafts, jack shafts, or head shafts. These line </p><p>　　shafts were assembled form separate lengths of shafting clampled together by rigid couplings. Although it is usually more convenient

8、to drive each machine with a separate electric motor, and the present-day trend is in this direction, there are still some oil engine receives its rotary motion from each of the cranks, via the pistons and connecting roa

9、ds (the slider-crank mechanisms) , and delivers it by means of couplings, gears, chains or belts to the transmission, camshaft, pumps, and other de</p><p>　　An axle is usually defined as a stationary cylindr

10、ical member on which wheels and pulleys can rotate, but the rotating shafts that drive the rear wheels of an automobile are also called axles, no doubt a carryover from horse-and-buggy days. It is common practice to spea

11、k short shafts on machines as spindles, especially tool-carrying or work-carrying shafts on machine tools.</p><p>　　In the days when all machines in a shop were driven by one large electric motor or prime mo

12、ver, it was necessary to have long line shafts running length of the shop and supplying power, by belt, to shorter coutershafts, jackshafts, or headshafts. These line shafts were assembled form separate lengths of shafti

13、ng clampled together by rigid couplings. Although it is usually more convenient to drive each machine with a separate electric motor, and the present-day trend is in this direction, there a</p><p>　　A single

14、-throw crankshaft that could be used in a single-cylinder reciprocating engine or pump is shown in Figure 21. The journals A and B rotate in the main bearings, C is the crankpin that fits in a bearing on the end of the c

15、onnecting rod and moves on a circle of radius R about the main bearings, while D and E are the cheeks or webs. </p><p>　　The throw R is one half the stroks of the piston, which is connected, by the wrist pin

16、, to the other end of the connecting rod and guided so as to move on a straight path passing throw the axis XX. On a multiple-cylinder engine the crankshaft has multiple throws---eight for a straight eight and for a V-8-

17、--arranged in a suitable angular relationship.</p><p>　　Stress and strains. In operation, shafts are subjected to a shearing stress, whose magnitude depends on the torque and the dimensions of the cross sect

18、ion. This stress is a measure of resistance that the shaft material offers to the applied torque. All shafts that transmit a torque are subjected to torsional shearing stresses.</p><p>　　In addition to the s

19、hearing stresses, twisted shafts are also subjected to shearing distortions. The distorted state is usually defined by the angle of twist per unit length; i.e., the retation of one cross section of a shaft relative to an

20、other cross section at a unit distance from it.</p><p>　　Shafts that carry gears and pulleys are bent as well as twisted, and the magniude of the bending stresses, which are tensile on the convex side of the

21、 bend and compressive on the concave side, will depend on the load, the distance between the bearings of the shaft cross section.</p><p>　　The combination of bending and twisting produces a state of stress i

22、n the shaft that is more complex than the state of pure shears produced by torsion alone or the state of tension-compression produced by bending alone.</p><p>　　To the designer of shaft it is important to kn

23、ow if the shaft is likely to fail because of an excessive normal stress. If a piece of chalk is twisted, it will invariably rupture on a plane at about 45 degrees to the axis. This is because the maximum tensile stresses

24、 act on this plane, and chalk is weak in tension. Steel shafting is usually designed so that the maximum shearing stress produced by bending and torsion is less than a specified maximum.</p><p>　　Shafts with

25、 circular cross sections are easier to produce in the steel mill, easier to machine, and easier to support in bearings than shafts with other cross section; there is seldom any need for using noncircular shapes. In addit

26、ion, the strength and stiffness, both in bending and torsion, are more easily calculated for circular shafts. Lastly, for a given amount of materials the circular shafts has the smallest maximum shearing stress for a giv

27、en torque, and the highest torsional rigidity.</p><p>　　The shearing in a circular shaft is highest at the surface and drops off to zero at the axis. This means that most of the torque is carried by the mate

28、rial on and near the surface.</p><p>　　Critical speeds. In the same way that a violin string vibrates when stroked with a bow, a cylindrical shaft suspended between two bearings has a natural frequency of la

29、teral vibration. If the speed of revolution of the shaft coincides with the natural frequency, the shaft experience a whirling critical speed and become noisy. These speeds are more likely to occur with long, flexible sh

30、afts than with short, stiff ones. The natural frequency of a shaft can be raised by increasing its stiffness.</p><p>　　If a slender rod is fixed to the ceiling ta one end and supports a heavy disk at the oth

31、er end, the disk will oscillate back and forth around the rod axis like a torsion pendulum if given an initial twist and let go. The frequency of the oscillations will depend on the torsional stiffness of the rod and the

32、 weight of the disk; the stiffer the rod and the lighter the disk the higher the frequency. Similar torsional oscillations can occur in the crankshafts of reciprocating engines, particularly t</p><p>　　When

33、the engine is operating the torques delivered to the crankshaft by the connecting rods fluctuate, and if the crankshaft speed is such that these fluctuating impulses are delivered at a speed corresponding to one of the n

34、atural torsional frequencies of the shaft, torsional oscillations will be superimposed on the rotary motion of the shafts. Such speed are known as torsional critical speeds, and they can cause shaft failures. A number of

35、 devices to control the oscillations of crankshafts hav</p><p>　　Flexible shafts. A flexible shaft consists of a number of superimposed tightly wound right-and left-hand layers of helically wound wires wrap

36、ped about a single center wire or mandrel. The shaft is connected to source of power and the driven member by special fittings attached to the end of the shaft. Flexible easings of metallic or nonmetallic materials, whic

37、h guide and protect the shaft and retain the lubricant, are also available. Compared with solid shafts, flexible shafts can be bent to muc</p><p>　　For transmitting power around corners and for considerable

38、distances flexible shafts are usually cheaper and more convenient than belts, chains, or gears. Most speedometers on automobiles are driven by flexible shafts running from the transmission to the dashboard. When a valve,

39、 a switch, or other control devices is in a hard-to-reach location, it can be operated by a flexible shaft from a more convenient position. For portable tools such as sanders, grinders, and drilling machines, flexible sh

40、a</p><p>　　出處：輸送機(jī)械相關(guān)英語 http://bbs.cmiw.cn/forum.php?mod=viewthread&tid=212652</p><p><b>　　中文翻譯：</b></p><p><b>　　軸</b></p><p>　　實(shí)心軸 軸作為機(jī)械零件

41、通常是一根圓柱形桿，用來支撐部件并隨部件一起轉(zhuǎn)動以接受和傳遞轉(zhuǎn)動和扭矩。往復(fù)式發(fā)動機(jī)的曲軸接受每一根曲軸通過活塞和連桿（滑塊-曲柄機(jī)構(gòu)）傳來的轉(zhuǎn)動，并通過聯(lián)軸器、齒輪、鏈條或皮帶把轉(zhuǎn)動傳遞到變速箱、凸輪軸、泵和其它裝置。由曲軸通過齒輪或鏈條驅(qū)動的凸輪軸只有一根受力軸即輸入軸，但軸上的每一個凸輪都能把轉(zhuǎn)動傳遞給氣門的傳動機(jī)構(gòu)溝。</p><p>　　輪軸通常的定義是車輪和皮帶輪能在其上旋轉(zhuǎn)的一根固定的圓柱形構(gòu)件，但

42、驅(qū)動汽車后輪的旋轉(zhuǎn)軸也叫輪軸，這可能是從過去馬車時代傳下來的。通常習(xí)慣上把機(jī)器上的短軸叫做主軸（或心軸），特別是指機(jī)床上安裝刀具和工件的軸。</p><p>　　在以前一個車間里所有的機(jī)器都由一個大電動機(jī)或原動機(jī)的，這樣就必須有一根同車間一樣長的主傳動軸（即天軸）通過皮帶把動力供給較短的副軸、中間軸或頂軸。這種主傳動軸是用一節(jié)節(jié)的軸裝配起來的，用剛性聯(lián)軸器固定在一起。盡管一般說來用單獨(dú)的電動機(jī)來驅(qū)動每一臺機(jī)器更為

43、方便，并且現(xiàn)代的趨勢也是按照這個方向發(fā)展的，但現(xiàn)在仍有某些場合采用分組傳動更為經(jīng)濟(jì)。</p><p>　　應(yīng)力和變力 軸在轉(zhuǎn)動時承受剪應(yīng)力，其大小取決于扭矩和斷面的尺寸。這個剪應(yīng)力是軸的材料對作用扭矩所產(chǎn)生的抗力的一種量度。所有傳遞扭矩的軸都承受扭轉(zhuǎn)剪應(yīng)力。</p><p>　　除剪應(yīng)力之外，傳遞扭矩的軸還會產(chǎn)生剪切變形。扭轉(zhuǎn)的狀態(tài)通常用每單位長度的扭轉(zhuǎn)角來表示，即用軸的某一截面所轉(zhuǎn)過的

44、角度來表示。</p><p>　　安裝齒輪和皮帶輪的軸不但會產(chǎn)生扭矩，而且還會產(chǎn)生彎矩，彎曲應(yīng)力（在凸面是拉應(yīng)力，在凹面是壓應(yīng)力）的大小取決于兩軸承間的距離及軸的截面尺寸，</p><p>　　彎曲和扭轉(zhuǎn)綜合起來使軸內(nèi)所產(chǎn)生的受力狀態(tài)比單純扭轉(zhuǎn)所產(chǎn)生的純剪切狀態(tài)或單純彎曲所產(chǎn)生的拉伸─壓縮狀態(tài)更為復(fù)雜。</p><p>　　對軸的設(shè)計(jì)工作者來說，重要的是要知道軸是否

45、可能產(chǎn)生過大的發(fā)向應(yīng)力或過大的剪應(yīng)力以致?lián)p壞。如果扭轉(zhuǎn)一支粉筆，它必定在同軸線成45°角的平面上而不是在與軸線垂直的平面上斷裂。這是因?yàn)樽畲蟮膽?yīng)力就作用在這個平面上，而粉筆的抗拉強(qiáng)度是很差的。通常在設(shè)計(jì)鋼軸時要使彎曲和扭轉(zhuǎn)產(chǎn)生的最大剪應(yīng)力小于規(guī)定的最大設(shè)計(jì)應(yīng)力。</p><p>　　圓形截面的軸與其它截面的軸相比，在扎鋼上更易于扎制，且更易于加工，同時也易于支撐在軸承上。因此，在實(shí)際應(yīng)用中很少使用非遠(yuǎn)行

46、截面的軸。此外，圓軸的強(qiáng)度和剛度，無論是在彎曲或是扭轉(zhuǎn)時，都較易與計(jì)算。最后，對一定量的材料來說，圓軸對一定的扭矩所產(chǎn)生的最大剪應(yīng)力最小，而抗扭剛度則最大。</p><p>　　圓軸內(nèi)的剪應(yīng)力在表面最大，而在軸線部分則降到零。這就是說大部分扭矩是由表面和靠近表面的材料來承受的。</p><p>　　臨界轉(zhuǎn)速 用弓拉小提琴時琴弦會發(fā)生振動，同樣，支撐在兩軸承之間的圓軸也有一個自然的橫向振動

47、頻率。如果軸的轉(zhuǎn)速與自然頻率重合，軸就處于臨界轉(zhuǎn)速并發(fā)出噪音。多半長的撓性軸比短的剛性軸更容易出現(xiàn)臨界轉(zhuǎn)速。軸的自然頻率可隨其剛度的增加而提高。</p><p>　　如果把一根細(xì)長桿的一端固定在天花板上，另一端支撐一個很重的圓盤，如果給圓盤一個起始的扭矩就把手松開，圓盤就會像扭擺一樣繞桿軸來回振動。振動的頻率取決于桿的抗扭剛度和圓盤的重量；桿的剛度越大且圓盤越輕則頻率越高。往復(fù)式發(fā)動機(jī)的曲軸也會產(chǎn)生類似的扭轉(zhuǎn)振動

48、。特別是多拐曲軸和帶有很重飛輪的曲軸更是如此。每一個曲拐和與之相聯(lián)的連桿部分的作用就像一個小飛輪，并且對作為一個整體的曲軸來說，這些小飛輪能按很多種方式彼此安相反的方向與主飛輪反反方向地繞軸線來回振動。</p><p>　　當(dāng)發(fā)動機(jī)運(yùn)轉(zhuǎn)時，由連桿傳遞給曲軸的扭矩是波動的，如果曲軸的轉(zhuǎn)速使連桿的起伏推力以與軸的自然扭轉(zhuǎn)頻率之一相符合的速度傳遞，則扭轉(zhuǎn)擺動就將同軸的轉(zhuǎn)動疊加起來。這樣的轉(zhuǎn)速稱之為扭轉(zhuǎn)臨界轉(zhuǎn)速，它能導(dǎo)致

49、軸的損壞。因此，已經(jīng)設(shè)計(jì)了許多裝置來控制軸的振動。</p><p>　　撓性軸 撓性軸是把單根的心線或新心軸上繞成螺旋形金屬絲左向和右向重疊地緊緊繞許多層而制成的。這種軸借助裝在軸的兩端的專用配件連接到動力源和從動件上。也可以采用金屬或非金屬材料的撓性套來引導(dǎo)和保護(hù)撓性軸，但要封裝一定的潤滑劑。與實(shí)心軸相比，撓性軸可以彎成半徑小得多的弧形而不至產(chǎn)生超限應(yīng)力。</p><p>　　對于把傳