外文翻譯---軸、聯(lián)軸器和滾動軸承

1、<p>　　荿蚇罿芃薂羂芇節(jié)蚄螅膃芁螆羀聿芀蒆螃羅艿薈罿袁莈蝕螁膀莈莀羇肆莇蒂螀肂莆蚅肅羈蒞螇袈芇莄蕆蟻膃莃蕿袆聿莂蟻蠆羅蒂莁裊袁蒁蒃蚇腿蒀薆袃膅葿螈蚆肁蒈蒈羈羇蕆薀螄芆蒆螞罿膂蒆螄螂肈薅蒄羈羄膁薆螁袀膀蠆羆羋腿蒈蝿膄腿薁肄肀膈蚃袇羆膇螅蝕芅膆蒅裊膁芅薇蚈肇芄蝕襖羃芄荿蚇罿芃薂羂芇節(jié)蚄螅膃芁螆羀聿芀蒆螃羅艿薈罿袁莈蝕螁膀莈莀羇肆莇蒂螀肂莆蚅肅羈蒞螇袈芇莄蕆蟻膃莃蕿袆聿莂蟻蠆羅蒂莁裊袁蒁蒃蚇腿蒀薆袃膅葿螈蚆肁蒈蒈羈羇蕆薀螄芆蒆螞

2、罿膂蒆螄螂肈薅蒄羈羄膁薆螁袀膀蠆羆羋腿蒈蝿膄腿薁肄肀膈蚃袇羆膇螅蝕芅膆蒅裊膁芅薇蚈肇芄蝕襖羃芄荿蚇罿芃薂羂芇節(jié)蚄螅膃芁螆羀聿芀蒆螃羅艿薈罿袁莈蝕螁膀莈莀羇肆莇蒂螀肂莆蚅肅羈蒞螇袈芇莄蕆蟻膃莃蕿袆聿莂蟻蠆羅蒂莁裊袁蒁蒃蚇腿蒀薆袃膅葿螈蚆肁蒈蒈羈羇蕆薀螄芆蒆螞罿膂蒆螄螂肈薅蒄羈羄膁薆螁袀膀蠆羆羋腿蒈蝿膄腿薁肄肀膈蚃袇羆膇螅蝕芅膆蒅裊膁芅薇蚈肇芄蝕襖羃芄荿蚇罿芃薂羂芇節(jié)蚄螅膃芁螆羀聿芀蒆螃羅艿薈罿袁莈蝕螁膀莈莀羇肆莇蒂螀肂莆蚅肅羈蒞螇袈芇莄蕆

3、蟻膃莃蕿袆聿莂蟻蠆羅蒂莁裊袁蒁蒃蚇腿蒀薆袃膅葿螈蚆肁蒈蒈羈羇蕆薀螄芆蒆螞罿膂蒆螄螂肈薅蒄羈羄膁薆螁袀膀蠆羆羋腿蒈蝿膄腿薁肄肀膈蚃袇羆膇螅蝕芅膆</p><p>　　附錄二 外文原文和翻譯</p><p>　　shafts、couplings and rolling contact bearings</p><p>　　key words: shafts、cou

4、plings、bearings</p><p>　　Virtually all machines contain shafts.The most common shape for shafts is circular and the cross section can be either solid or hollow (hollow shafts can result in weight savings ).R

5、ectangular shafts are sometimes used ,as in screwdriver blades,socket wrenches and control knob stems .</p><p>　　A shaft must have adequate torsional strength to transmit torque and not be overstressed. It a

6、lso be torsionally stiff enough so that one mounted component does not deviate excessively from its original angular position relative to a second component mounted on the same shaft. Generally speaking ,the angle of twi

7、st should not exceed one degree in a shaft length equal to 20 diameters.</p><p>　　Shafts are mounted inbearings and transmint power through such devices as gears, pullerys, cams and clutches. These devices i

8、ntroduce forces which attempt to bend the shaft; hence, the shaft must be rigid enough to prevent overloading of the supporting bearings. In general, the bending deflection of a shaft should not exceed 0.01 in. per ft of

9、 length between bearing supports.</p><p>　　In addition, the shaft must be able to sustain a combination of bending and torsional loads. Thus an equivalent load must be considered which takes into account bot

10、h torsion and bending. Also, the allowable stress must contain a factor of safety which includes fatigue, since torsional and bending stress reversals occur.</p><p>　　For diameters less than 3 in. , the usua

11、l shaft material is cold-rolled ateel containing about 0.4 percent carbon. Shafts are either cold-rolled or forged in sizes from 3 in. to 5 in. ,shafts are forged and machined to size .Pleastic shafts are widely used for

12、 light load applications. One advantage of using plastic is safety in electrical applications ,since plastic is a poor conductor of electricity.</p><p>　　Components such as gears and pulleys are mounted on s

13、hafts by means of key .The design of the key and the corresponding keyway in the shaft must be prperly evaluated. For example ,stress concentrations occur in shafts due to keyways ,and the material removed to form the ke

14、yway further weakens the shaft.</p><p>　　If shafts are run at cirtical speeds ,severe vibrations can occur which can seriously damage a machine. It is important to know the magnitude of these critical speeds

15、 so that they can be avoided. As a general rule of thumb,the difference between the operating speed and the critical speed should be at least 20 percent .</p><p>　　Another important aspect of shaft design is

16、 the method of directly connecting one shaft to another. This is accomplished by devices such as rigid and flexible couplings.</p><p>　　A coupling is a device for connecting the eds of adjacent shafts. In ma

17、chine construction, ouplings are used to effect a semipermanent connection between adjacent rotating shafts. The connection is permanent in the sense that it is not meant to be broken during the useful life of the machin

18、e, but it can be broken and restored in an emergency or when worn parts are replaced.</p><p>　　There are several types of shaft couplings, their characteristics depend on the purpose for which they are used.

19、 If an exceptionally long shaft is required in a manufacturing plant or a propeller shaft on a ship, it is made in sections that are coupled together with rigid couplings. A common type of rigid coupling consists of two

20、mating radial flanges(disks) that are cttached by key-driven hubs to the eds of adjacent shaft sections and bolted together through the flanges to form a rigid connecti</p><p>　　In connecting shafts belongin

21、g to separate devices (such as an electric motor and a gearbox ),precise aligning of the shafts is difficult and a flexible coupling is used. This coupling connects theshafts in such a way as to minimize the harmful effe

22、cts of shaft misalignment. Flexible couplings also permit the shafts to deflect under their separate systems of with one another. Flexible couplings can also serve to reduce the intensity of shock loads and vibrations tr

23、ansmitted from one shaft to ano</p><p>　　Virtually all shafts contain rolling contact bearings.The concern of a machine designer with ball and roller bearings is fivefold as follows:(a) life in relation to l

24、oad; (b) stiffness ,i.e. deflections under load; (c) friction; (d) wear; (e) noise. For moderate loads and speeds the correct selection of a standard bearing on the basis of load rating will usually secure satisfactory p

25、erformance. The deflection of the bearing elements will become important where loads are high, although this is us</p><p>　　Because the high quality and low price of ball and roller bearings depends on quant

26、ity production, the task of the machine designer becomes one of selection rather than design. Rolling-contact bearings are generally made with ateel which is through-hardened toabout 900HV,although in many mechanisms spe

27、cial races are not provided and the interacting surfaces are hardened to about 600 HV. It is not surprising that, owing to the high stresses involved, a predominant form of failure should be metal </p><p>　　

28、Notwithstanding the fact that responsibility for the basic design of ball and roller bearings rests with the bearing manufacturer, the machine designer must form a correct appreciation of the duty to be performed by the

29、bearing and be concerned not only with bearing selection but with the conditions for correct installation.</p><p>　　The fit of the bearing races onto the shaft or onto the housings is of critical importance

30、because of their combined effect on the internal clearance of the bearing as well as preserving the desired degree of interference fit. Inadequate interference can induce serious trouble from fretting corrosion. The inne

31、r race is frequently located axially by abutting against a shoulder. A radius at this point is essential for the avoidance of stress concentration and ball races are provides with a radius </p><p>　　Where li

32、fe is not the determining factor in design, it is usual to determine maximum loading by the amount towhich a bearing will deflect under load. Thus the concept of “static load-carrying capacity” is understood to mean the

33、load that can be alpplied to a bearing, which is either stationary or subject to slight swiveling motions, without impairing its running qualities for subsequent rotational motion. This has been determined by practical e

34、xperience as the load which when applied to a bearin</p><p>　　The successful functioning of many bearing depends upon providing them with adequate protection against their environment, and in some circumstan

35、ces the enviroration of the bering surfaces. Achievement of the correct functioning of seals is an essential part of bearing design. Moreover, seals which are applied to moving parts for any purpose are of interest to tr

36、ibologists because they are components of bearing systems and can only be designed satisfactorily on the basis of the approlpriate bear</p><p>　　References:</p><p>　　1 Erickson.Belt and Applica

37、tion for Engineers.Marcel Dekker.Inc,1997</p><p>　　2 South,Mancuso.Mechanical Power Transmission Components.1994</p><p>　　軸、聯(lián)軸器和滾動軸承</p><p>　　關(guān)鍵詞：軸、聯(lián)軸器、軸承</p><p>　　實(shí)際上

38、，幾乎所有的機(jī)器中都裝有軸。軸最常見的形狀是圓形，其截面可以是實(shí)心的，也可以是空心的（空心軸可以減輕重量）。有時也采用矩形軸，例如，螺絲起子的頭、套筒扳手和控制旋扭的桿。</p><p>　　為了在傳遞轉(zhuǎn)矩時不發(fā)生過載，軸應(yīng)該具有適當(dāng)?shù)目古?qiáng)度。軸還應(yīng)該具有足夠的抗扭剛度，以使同一個軸上的兩個傳動零件之間的相對轉(zhuǎn)角不回過大。一般來說，在軸的長度等于其直徑的20倍時，扭轉(zhuǎn)角不應(yīng)該超過1度。</p>&

39、lt;p>　　軸安裝在軸承中，通過齒輪、皮帶輪、凸輪、和離合器等零件傳遞動力。通過這些零件傳來的里可能會使軸產(chǎn)生彎曲變形。因此，軸應(yīng)該有足夠的剛度以防止支撐軸承受力過大?？偠灾?，在兩個軸承支承之間，軸在每英尺長度上的彎曲變形不應(yīng)該超過0.01英寸。</p><p>　　此外，軸還必須能承受彎矩和扭矩的組合作用。因此，要考慮扭矩與彎矩的當(dāng)量載荷。因?yàn)榕ぞ睾蛷澗貢a(chǎn)生交變應(yīng)力，在許用應(yīng)力中也應(yīng)該有一個考慮疲勞

40、現(xiàn)象的安全系數(shù)。</p><p>　　直徑小于3英寸的軸可以采用含碳量大約為0.4%的冷軋鋼，直徑在3~5英寸之間的軸可以采用冷軋鋼或鍛造毛坯。當(dāng)直徑大于5英寸大，則要采用鍛造毛坯，然后機(jī)械加工到所要求的尺寸。輕載時，廣泛采用塑料軸。由于塑料是電的不良導(dǎo)體，在電器中用它做軸比較安全。</p><p>　　齒輪和皮帶輪等零件通過鍵聯(lián)接在軸上。在對鍵及軸上與之相應(yīng)的鍵槽進(jìn)行設(shè)計(jì)時，必須進(jìn)行認(rèn)真

41、的計(jì)算。例如，軸上的鍵槽會引起應(yīng)力集中，由于鍵槽的存在使軸的橫截面積間隙哦啊，會進(jìn)一步減弱軸的強(qiáng)度。</p><p>　　如果軸以臨界速度轉(zhuǎn)動，將會發(fā)生強(qiáng)烈的振動，可能會毀壞整臺機(jī)器。知道這些臨界速度的大小是很重要的，因?yàn)檫@樣可以避開它。一般憑經(jīng)驗(yàn)來說，工作速度與臨界速度之間至少應(yīng)該相差20%。</p><p>　　軸的設(shè)計(jì)工作的另一個重要方面是軸與軸之間的直接聯(lián)接方法。這是有剛性或者彈性

42、聯(lián)軸器來實(shí)現(xiàn)的。</p><p>　　聯(lián)軸器是用來把兩個相鄰軸端聯(lián)接起來的裝置。在機(jī)械結(jié)構(gòu)中，聯(lián)軸器被用來實(shí)現(xiàn)相鄰的兩根轉(zhuǎn)軸之間的半永久性聯(lián)接。在機(jī)器的正常使用期間內(nèi)，這種聯(lián)接一般不必拆開，在這種意義上，可以說聯(lián)軸器的聯(lián)接是永久性的。但是在緊急情況下，或者需要更換以磨損的零件時，可以先把聯(lián)軸器拆開，然后再聯(lián)接上。</p><p>　　聯(lián)軸器有幾種類型，它們的特性隨其用途而定。如果制造工廠中

43、或者船舶的螺旋漿需要一根特別長的軸，可以采用分段的方式將其制造出來，然后采用剛性聯(lián)軸器將各段聯(lián)接起來。一種常用的聯(lián)軸器是由兩個配對的法蘭（盤）組成，這兩個法蘭盤借助靠鍵傳動的軸套聯(lián)接到相鄰兩節(jié)軸的兩端，然后用螺栓穿過法蘭聯(lián)接起來形成剛性接頭。相互聯(lián)接的兩根軸通常是靠法蘭面的槽口來對準(zhǔn)的。</p><p>　　在把屬于不同的設(shè)備（例如一個個電動機(jī)和一個變速箱）的軸聯(lián)接起來的時候，要把這些軸精確地對準(zhǔn)是比較困難的，此

44、時可以采用彈性聯(lián)軸器。這種聯(lián)軸器聯(lián)接軸的方式可以把由于被聯(lián)接的軸之間的軸線不重合所造成的有害影響減少到最低程度。彈性聯(lián)軸器也允許被聯(lián)接的軸在它們各自的載荷系統(tǒng)作用下產(chǎn)生偏斜或在軸線方向自由移動（浮動）而不至于相互干擾。彈性聯(lián)軸器也可以用來減輕從一根軸傳到另一根軸上的沖擊載荷和振動的強(qiáng)度。</p><p>　　而幾乎所有的軸都裝有滾動軸承。對于球軸承和滾子軸承，一個機(jī)器設(shè)計(jì)人員應(yīng)該考慮下面五個方面：（a）壽命與載荷

45、的關(guān)系；（b）剛度，也就是在載荷作用下的變形；（c）摩擦；（d）磨損；（e）噪音。對于中等載荷和轉(zhuǎn)速，根據(jù)額定負(fù)荷選擇一個標(biāo)準(zhǔn)軸承，通常都可以保證其具有令人滿意的工作性能。當(dāng)載荷較大時，軸承零件的變形，盡管它通常小于軸和其他與軸承一起工作的零部件的變形，將會變得重要起來。在轉(zhuǎn)速高的場合需要有專門的冷卻裝置，而這可能會增大摩擦阻力。磨損主要是由于污染物的進(jìn)入引起的，必須選用密封裝置以防止周圍環(huán)境的不良影響。</p><

46、p>　　因?yàn)榇笈可a(chǎn)這種方式?jīng)Q定了球軸承和滾子軸承不但質(zhì)量高，而且價格低，因而機(jī)器設(shè)計(jì)人員的任務(wù)是選擇而不是設(shè)計(jì)軸承。滾動接觸軸承通常是采用硬度大約900HV、整體淬火的鋼來制造的。但在許多機(jī)構(gòu)上不使用專門的套圈，而將相互作用的表面淬硬到大約600HV。滾動軸承由于在工作中會產(chǎn)生高的應(yīng)力，其主要失效形式是金屬疲勞，這一點(diǎn)并不奇怪，目前正在進(jìn)行大量的工作以求改進(jìn)這種軸承的可靠性。軸承設(shè)計(jì)可以基于能夠被人們所接受的壽命值來進(jìn)行。在軸

47、承行業(yè)中，通常將軸承的承載能力定義為這樣的值，即所承擔(dān)的載荷小于這個值時，一批軸承中將會有90%的軸承具有超過一百萬轉(zhuǎn)的壽命。</p><p>　　盡管球軸承和滾子軸承的基本設(shè)計(jì)責(zé)任在軸承制造廠家，機(jī)器設(shè)計(jì)人員必須對軸承所要完成的任務(wù)做出正確的評價，不僅要考慮軸承的選擇，而且還要考慮軸承的正確安裝條件。</p><p>　　軸承套圈與軸或軸承座的配合非常重要，因?yàn)樗鼈冎g的配合不僅應(yīng)該保證

48、所需要的過盈良，而且也應(yīng)該保證軸承的內(nèi)部間隙。不正確的過盈量會產(chǎn)生微振腐蝕磨損從而導(dǎo)致嚴(yán)重的故障。內(nèi)圈通常是通過緊靠在軸肩上進(jìn)行軸向定位的。軸肩處的圓弧半徑重要是為了避免應(yīng)力集中。在軸承內(nèi)圈上加工出一個圓狐或者倒角，用來提供容納軸肩處圓弧半徑的空間。</p><p>　　在使用壽命不是設(shè)計(jì)中的決定因素的場合，通常根據(jù)軸承受載荷時產(chǎn)生的變形量來確定其最大載荷。因此，“靜態(tài)承載能力”這個概念可以理解為對處于靜止?fàn)顟B(tài)的

49、或者進(jìn)行緩慢轉(zhuǎn)動的質(zhì)量沒有不利影響。按照實(shí)踐經(jīng)驗(yàn)確定，靜態(tài)承載能力是這樣一個載荷，當(dāng)它作用在軸承上時，滾動體與滾道在任何一個接觸點(diǎn)處的總變形量不超過滾動體直徑的0.01%。這相當(dāng)于直徑位25mm的球產(chǎn)生0.0025mm的永久變形。</p><p>　　只有將軸承與周圍環(huán)境適當(dāng)?shù)馗綦x開，許多軸承才能成功地實(shí)現(xiàn)它們的功用。在某些情況下，必須保護(hù)環(huán)境，使其不受潤滑劑和軸承表面磨損生成物的污染。軸承設(shè)計(jì)的一個重要組成部分

50、是使密封裝置起到應(yīng)有作用。此外，對摩擦學(xué)研究人員來說，為了任何目的而應(yīng)用于運(yùn)動零部件上的密封裝置都是他們感興趣的。因?yàn)槊芊庋b置是軸承系統(tǒng)的一部分，只有根據(jù)適當(dāng)軸承理論才能設(shè)計(jì)出令人滿意的密封裝置。雖然它們很重要，與軸承其他方面的研究工作相比，到目前為止在密封裝置的研究方面所做出的工作還是比較少的。</p><p><b>　　參考文獻(xiàn)：</b></p><p>　　1

51、 Erickson.Belt and Application for Engineers.Marcel Dekker.Inc,1997</p><p>　　2 South,Mancuso.Mechanical Power Transmission Components.1994</p><p>　　莈蚃膀膀薃蠆腿節(jié)蒆羈腿莄螞襖膈蕆蒄螀膇膆蝕蚆袃艿蒃薂袃莁蚈袁袂肁蒁袇袁芃螆螃袀蒞蕿蚈衿蒈

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