机电技术专业英语 教学课件 作者 徐起贺 张庆良pata b lesson Nine.pptVIP

* 机电技术专业英语 Lesson Nine Text The concern of a machine designer with ball and roller bearings is fivefold as follows: ①life in relation to load. ②stiffness，i.e. deflections under load. ③friction. ④wear. ⑤noise. For moderate loads and speeds the correct selection of a standard bearing on the basis of load rating will usually secure satisfactory performance. The deflection of the bearing elements will become important where loads are high, although this is usually of less magnitude than that of the shafts or other components associated with the bearing. Where speeds are high special cooling arrangements become necessary which may increase frictional drag. Wear is primarily associated with the introduction of contaminants, and sealing arrangements must be chosen with regard to the hostility of the environment. Rolling Contact Bearings Lesson Nine New Words and Expressions Lesson Nine Lesson Nine Notes 1. throughhardened 意为“经过透硬淬火的，整体淬火的”。 2. fretting corrosion 意为“微动腐蚀(即由腐蚀和两固体接触面有微小振幅的振动而引起的磨损的联合作用所产生的材料破坏)”。 3. static loadcarrying capacity意为“静态承载能力”。 Lesson Nine Lesson Nine 参考译文 对于球轴承和滚子轴承，一个机器设计人员应该考虑下面五个方面：①寿命与载荷的关系；②刚度，也就是在载荷作用下的变形；③摩擦；④磨损；⑤噪声。对于中等载荷和转速，根据额定负荷选择一个标准轴承，通常都可以保证其具有令人满意的工作性能。当载荷较大时，尽管轴承零件的变形通常小于轴和其他与轴承一起工作的零部件的变形，但是这种变形也应当引起足够的重视。在转速高的场合需要有专门的冷却装置，而这可能会增大摩擦阻力。磨损主要是由于污染物的进入引起的，必须选用密封装置以防止周围环境的不良影响。 滚 动 轴 承 谢谢观赏 相关词汇表。 *