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

研究了真空条件下齿轮的摩擦磨损特性。利用齿轮试验机对S45C、SUS440C和MoS_2包覆SUS440C齿轮在空气和真空环境下进行了运行试验，测量了接触齿面间的摩擦系数、齿轮齿的磨损以及齿轮齿、轴的温度变化等。在这些结果的基础上，确定了齿轮在真空中的摩擦和磨损特性。研究了不同壳体深度淬火齿轮在低温（-60℃）下的冲击强度和弯曲疲劳强度。C)也被调查了。确定了壳体淬硬齿轮在室温和低温下的冲击和弯曲疲劳强度，以及壳体深度对这些强度的影响以及冲击载荷对弯曲疲劳强度的影响。本研究的主要结果总结如下：1。真空条件下S45C齿轮的摩擦系数大于空气条件下SUS440C齿轮的摩擦系数，而真空条件下SUS440C齿轮的摩擦系数小于空气条件下SUS440C齿轮的摩擦系数，其中MoS_2包覆SUS440C齿轮在真空条件下的摩擦系数与空气条件下的摩擦系数基本相等。淬火齿轮在低温（-60℃）下的弯曲疲劳强度。C)比常温时大，但低温时冲击强度小。在低温和室温条件下，淬火齿轮的弯曲疲劳强度存在最优壳体深度。冲击强度随壳体深度的增加而降低。当冲击载荷小于冲击断裂极限载荷时，低温冲击载荷对弯曲疲劳强度没有影响，而室温冲击载荷对弯曲疲劳强度有影响。从而确定了齿轮在低温和真空条件下的承载能力，为空间应用齿轮的设计提供了有益的数据。

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.