为了深入研究望远镜的负载扭矩随着温度降低而增大的机理, 提高低温下伺服系统的跟踪精度。首先分析了轴承摩擦扭矩的各种影响因素和低温对负载扭矩的影响, 研究了润滑剂黏度随温度的变化规律, 试验对比了有无添加润滑脂情况下负载扭矩的变化, 结果表明在低温下无润滑脂时负载扭矩的波动减少并且线性度提高。其次分析了轴承摩擦扭矩和间隙的关系, 采用电阻应变片法测量不同材料在不同温度下的热膨胀系数, 建立起材料膨胀系数和扭矩的相关特性, 结果表明低温下负载扭矩是常温下的6.67倍, 而材料尺寸的最大缩短量达到960 με。通过对低温负载扭矩机理的研究, 可为低温环境下望远镜的精确控制提供理论和试验数据。

In order to improve the accuracy of the servo system at low temperature, the mechanism that the load torque of the telescope increase along with the temperature decrease must be deeply understood. Firstly, the influence factors of friction torque of bearing and the influence of low temperature on load torque were analyzed. The lubricant viscosity with temperature variation was studied. The relationship between load torque and grease was tested and discussed. The results indicate that the fluctuation of load torque without the grease at low temperature is decreased and the linearity of load torque is increased. The influence of clearance on bearing friction torque was also analyzed. The expansion coefficient of different materials at different temperatures was measured by resistance strain gauge method. The correlation coefficient between torque and material expansion was established. The result indicates that the load torque at low temperature is 6.67 times load torque at normal temperature, and the maximum of shortening of material reaches 960 με. The research on the mechanism of cryogenic load torque in this paper can provide theoretical and experimental data for the precise control of the telescope under extreme environment.