机械制造专业英语-technical+english.doc

TECHNICAL ENGLISH FOR MECHANICAL ENGINEERING 机械制造专业英语 2009．7 Capacity of a machine component is related to the most severe service condition it can sustain without a change which will prevent the component from continuing its intended function. Micro-cracks exist in the structure of this material which give rise to high stress concentration during tensile loading while in compressive loading, for geometrical reasons, these micro-cracks are ineffective. A hollow shaft weighs considerably less than a solid shaft of comparable strength, but is somewhat more expensive. Careful location of bearings can do much to control the size of shafts, as the loading is affected by the position of mountings. Often, the bore of such other components has to be chamfered to clear radii at the point where a shaft changes diameter. The diameters of shafts made compatible with metric-sized bores of mechanical components (such as antifriction bearings) are specified in millimeters. When two gears are meshing, the two pitch circles must be exactly tangent if the gears are to function properly. 压力角是不计算摩擦力的情况下，受力方向和运动方向所夹的锐角。 Pressure angle: the angle between the line of action and a line perpendicular to the centerlines of the two gears in mesh. The metric system for spur-gear直尺圆柱齿轮 calculations involves more than changing inches to millimeters. The pouring process must be carefully controlled, since the temperature of the melt greatly affects the degree of liquid contraction before solidification, the rate of solidification, which in turn affects the amount of columnar growth present at the mold wall, the extent and nature of the dendritic growth, the degree of alloy burnout, and the feeding characteristics of the risering system. Productivity and quality depend to a large degree on the skill of the hammer operator and the tooling. Tolerances vary with materials and design, but production runs calling for 0.002 to 0.005-in. tolerance are regularly made. Basically, arc welding is a proces