外文翻譯--齒輪和齒輪傳動-其他專業(yè)(編輯修改稿)
2025-02-24 00:34 本頁面
【文章內(nèi)容簡介】 tedly engage if both gear and pinion are hardened steel. (If the gear is made of a soft material, an integral ratio allows the gear to coldwork and conform to the pinion, thereby promoting quiet operation.) Make sure critical are at least 20% apart from operating speeding or speed multiples and from frequency of tooth mesh. Multiple mesh gear Multiple mesh refers to move than one pair of gear operating in a train. Can be on parallel or nonparallel axes and on intersection or nonintersecting shafts. They permit higer speed ratios than are feasible with a single pair of gears . Series trains:Overall ratio is input shaft speed divided by output speed ,also the product of individual ratios at each mesh ,except in plaary gears .Ratio is most easily found by dividing the product of numbers of teeth of driven gears by the product of numbers of teeth of driving gears. Speed increasers (with stepup rather than stepdown ratios) may require special care in manufacturing and design. They often involve high speeds and may creste problems in gear dynamics. Also, frictional and drag forces are magnified which, in extreme cases , may lead to operational problems. Epicyclic Gearing:Normally, a gear axis remains fixed and only the gears rotates. But in an epicyclic gear train, various gears axes rotate about one anther to provide specialized output motions. With suitable clutchse and brakes, an epicyclic train serves as the plaary 蘭州交通大學(xué)畢業(yè)設(shè)計（論文） 4 gear monly found in automatic transmissions. Epicyclic trains may use spur or helical gears, external or internal, or bevel gears. In transmissions, the epicyclic (or plaary) gears usually have multiple plas to increase load capacity. In most cases, improved kinematic accuracy in a gearset decreases gear mesh excitation and results in lower drive noise. Gearset accuracy can be increased by modifying the tooth involute profile, by substituting higher quality gearing with tighter manufacturing tolerances, and by improving tooth surface finish. However, if gear mesh excitation generaters resonance somewhere in the drive system, nothing short of a “perfect” gearset will substantially reduce vibration and noise. Tooth profiles are modified to avoid interferences which can result from deflections in the gears, shafts, and housing as teeth engage and disendgage. If these tooth interferences are not pensated for by profile modifications, gears load capacity can be seriously reduced. In addition, the drive will be noisier because tooth interferences generate high dynamic loads. Interferences typically are eliminated by reliving the tooth tip, the tooth flank, or both. Such profile modifications are especially important for highload , highspeed drives. The graph of sound pressure
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