一、前言我们在设计,制造一部机器时,总是力图做到使它的效能高,使用寿命长。而且,除了少数有特殊要求者以外,还希望这部机器的体积小,重量轻。要达到这四个方面的要求,既要有良好的结构设计,又要合理地 First, the foreword We are in the design, manufacture a machine, always trying to make it high efficiency, long service life. Moreover, except for a few who have special requirements, but also hope that this machine is small and light weight. To achieve these four requirements, we must have a good structural design, but also reasonable