Evaluation of Performance and Development of Surface Treatment Method of Gears for Space Application

点击翻译按钮获取中文摘要

The friction and wear characteristics of gears in vacuum were investigated. The running tests for S45C, SUS440C and MoS_2 coated SUS440C gears were carried out in air and vacuum environment by using the gear testing machine, and the coefficient of friction between the contacting tooth surfaces, the wear of the gear teeth and temperature changes of the gear teeth, the shaft, etc. were measured. One the basis of these results, the friction and wear characteristics of gears in vacuum were determined to a considerable extent.The impact and bending fatigue strengths of case-hardened gears with various case depths at low temperature (-60 。C) were also investigated. The impact and bending fatigue strength of case-hardened gears at room and low temperature, and the effects of case depths on these strengths and the effect of impact load on the bending fatigue strength were determined considerably.The main results obtained from this investigation are summarized as follows.1. The coefficient of friction of S45C gears in vaccum is larger than that in air, but that of SUS440C gears in vacuum is smaller, and that of MoS_2 coated SUS440C gears in vacuum is almost equal to that in air.2. The bending fatigue strength of case-hardened gears at low temperature (-60 。C) is larger than that at room temperature, but the impact strength at low temperature is smaller.3. The optimum case depth exists for the bending fatigue strength of case-hardened gears at low and room temperatures. The impact strength decreases with an increasing case depth.4. An impact load at low temperature has no effect on the bending fatigue strength when the impact load is smaller than the impact breaking limit load, while that at room temperature has an effect on the bending fatigue strength.Thus the load bearing capacity of gears at low temperature and in vacuum was determined, and the useful data for the design of gears for space application were obtained from this investigation.