Shafts and Couplings

Terminology Text tour

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《机械工程专业英语教程》

Terminology

Coupling

A coupling is a device for connecting the ends of adjacent shafts.

联轴器：联轴器是用来把相邻的两个轴 的轴端联接起来的装置

Socket wrench

A wrench with a usually

interchangeable socket to fit over a nut or bolt

套筒扳手：通常带有可替换套筒以 适于螺帽或螺栓的扳手

Keyway

A slot for a key in the hub or shaft of a wheel

键槽：轮毂里或轴上装键的沟槽

Bolt 螺栓, 螺杆

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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).

Rectangular shafts are sometimes used, as in screw driver blades,

socket wrenches and control knob stems.

Text tour

66

A shaft must have adequate torsional strength to transmit torque and not be over stressed. It must also 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 twist should not exceed one degree in a

shaft length equal to 20 diameters.

为了在传递扭矩时不发生过载，轴应该具 有适当的抗扭强度。轴还应该具有足够的 抗扭刚度，以使在同一个轴上的两个传动 零件之间的相对转角不会过大。一般来 说，在长度等于轴的直径的20倍时，轴的 扭转角不应该超过1°。

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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 0.01 in. per ft of length between bearing supports.

轴安装在轴承中，通过齿轮、皮带轮、凸 轮和离合器等零件传递动力。通过这些零 件传来的力可能会使轴产生弯曲变形。因 此，轴应该有足够的刚度以防止支撑轴承 受力过大。总而言之，在两个轴承支撑之 间，轴在每英尺长度上的弯曲变形不应该 超过0.01英寸。

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 both torsion and bending.

Also, the allowable stress must contain a factor of safety which includes fatigue, since torsional and bending stress reversals occur.

此外，轴还必须能够承受弯矩和扭 矩的组合作用。因此，要考虑扭矩 与弯矩的当量载荷。因为扭矩和弯 矩会产生交变应力，在许用应力中 也应该有一个考虑疲劳现象的安全 系数。

For diameters less than 3 in. , the usual shaft material is cold-rolled steel containing about 0.4 percent carbon. Shafts are either cold-rolled or forged in sizes from 3 in. to 5 in..

For sizes above 5 in. , shafts are forged and machined to size.^[1]

Plastic shafts are widely used for light load applications. One

advantage of using plastic is safety in electrical applications, since

plastic is a poor conductor of electricity.

直径小于3英寸的轴可以采用含碳量大约为

Components such as gears and pulleys are mounted on shafts by means of key. The design of the

key and the corresponding keyway in the shaft must be properly

evaluated. For example, stress

concentrations occur in shafts due to keyways, and the material

removed to form the keyway further weakens the shaft.

齿轮和带轮等零件通过键联接在轴 上。在对键及轴上与之相对应的键

槽的设计中，必须进行认真的计算。

例如，轴上的键槽会引起应力集

中，由于键槽的存在会使轴的横截

面积减小，会进一步减弱轴的强度。

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