機(jī)械專(zhuān)業(yè)畢業(yè)設(shè)計(jì)外文翻譯5-其他專(zhuān)業(yè)-文庫(kù)吧
2025-12-16 12:29 本頁(yè)面
【正文】 素的場(chǎng)合，通常根據(jù)軸承受載荷時(shí)產(chǎn)生的變形量來(lái)確定其最大載荷。因此， “靜態(tài)承載能力 ”這個(gè)概念可以理解為對(duì)處于靜止?fàn)顟B(tài)的或者進(jìn)行緩慢轉(zhuǎn)動(dòng)的質(zhì)量沒(méi)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(gè)載荷，當(dāng)它作用在軸承上時(shí)，滾動(dòng)體與滾道在任何一個(gè)接觸點(diǎn)處的總變形量不超過(guò)滾動(dòng)體直徑的 %。這相當(dāng)于直徑位 25mm 的球產(chǎn)生 的永久變形。 只有將軸承與周?chē)h(huán)境適當(dāng)?shù)馗綦x開(kāi)，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(rùn)滑劑和軸承表面磨損生成物的污染。軸承設(shè)計(jì)的一 個(gè)重要組成部分是使密封裝置起到應(yīng)有作用。此外，對(duì)摩擦學(xué)研究人員來(lái)說(shuō)，為了任何目的而應(yīng)用于運(yùn)動(dòng)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(mǎn)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。 Virtually all machines contain shafts. The most mon shape for shafts is circular and the cross section can be either solid or hollow (hollow shafts can result in weight savings).Rectangular shafts are sometimes used, as in screwdriver blades, socket wrenches and control knob stems . A shaft must have adequate torsion strength to transmit torque and not be overstressed. It also be torsion ally stiff enough so that one mounted ponent does not deviate excessively from its original angular position relative to a second ponent mounted on the same shaft. Generally speaking, the angle of twist should not exceed one degree in a shaft length equal to 20 diameters. Shafts are mounted in bearings and transmit power through such devices as gears, pulleys, cams and clutches. These devices introduce 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 in. per ft of length between bearing supports. In addition, the shaft must be able to sustain a bination of bending and tensional loads. Thus an equivalent load must be considered 2 which take into account both torsion and bending. Also, the allowable stress must contain a factor of safety which includes fatigue, since tensional and bending stress reversals occur. For diameters less than 3 in., the usual shaft material is coldrolled steel containing about percent carbon. Shafts are either coldrolled or fed in sizes from 3 in. to 5 in., shafts are fed and machined to size. Plastic shafts are widely used for light load applications. One advantage of using plastic is safety in electrical applications, since plasti
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