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30 m口径望远镜(TMT)的三镜跟踪系统(M3PA)的运动性能和指向精度指标均高于已建成的各大望远镜,且工况复杂多变,给设计人员带来了巨大的挑战。三镜跟踪系统包括Rotator轴和Tilt轴两部分。重点研究了Tilt轴轴承布置方案以及相应分析。提出了两种轴承方案,经过分析,使用一对双列角接触转盘轴承的方案更适合于Tilt轴的工作需要,此时结构第一阶谐振频率可达到15.1Hz,满足Tilt轴的设计要求。选定方案后,针对所选择的轴承,使用ANSYS进行了仿真。仿真结果显示,所选轴承中滚动体的最大承载达到5 000 N,最大应力大约为2 300 MPa,承载曲线满足经典余弦分布,从而证明仿真数据可靠,模拟方法可信;另外四列滚动体上都有明显的承载,从而说明所选择的轴系能够很好地将载荷分散到两侧结构架上。分析结果表明,这种结构形式能够满足TMT三镜系统对刚度要求。
The movement and pointing accuracy of the three-mirror tracking system (M3PA) of the 30 m telescope (TMT) are both higher than those of the existing large telescopes. The complicated and changeable working conditions pose a great challenge to designers. Three mirror tracking system includes Rotator axis and Tilt axis of two parts. Focus on the Tilt shaft bearing arrangement and the corresponding analysis. Two kinds of bearing schemes are proposed. After analysis, the scheme of using a pair of double row angular contact turntable bearings is more suitable for the work of Tilt shaft. At this moment, the first resonance frequency of the structure can reach 15.1Hz, which meets the design requirements of Tilt shaft. After selecting the solution, the selected bearing was simulated using ANSYS. The simulation results show that the maximum load of the rolling elements in the selected bearing reaches 5 000 N and the maximum stress is about 2 300 MPa. The load curve satisfies the classical cosine distribution, which proves that the simulation data is reliable and the simulation method is credible. On the other four rolling elements Have obvious bearing, which shows that the selected shaft system can well distribute the load to both sides of the structure frame. The analysis results show that this structure can meet the TMT three mirror system stiffness requirements.