Abstract: For the national key R&D program “high-speed precision suspension bearing”, the requirements for the drop capacity of TDBs were: rotor mass ≥3000 kg, drop speed ≥3000 r/min, and successful drops ≥10 times. Based on this, the research and development of TDBs drop failure mechanism were carried out. Two hybrid TDBs with ceramic balls suitable for drop conditions were proposed: full complement ball without cage scheme and non-full complement ball with cage scheme. A rotor drop simulation model was built including dynamics and thermal. The force and heating processes of the drop processes were simulated. The effectiveness of the simulation model was verified by mounting the TDBs in the test bench for experiments. TDBs without cage are found to have failed severely. The damages of the failed bearing are detected, and it is observed that due to the large friction coefficient between the rolling elements, the rolling elements are seized up, resulting in continuous dry friction between the rolling elements and the raceways, and between the inner ring and the rotor, and serious burns and wear of the inner rings.

Key words: active magnetic bearing, touchdown bearing(TDB), rotor drop, bearing damage, failure mechanism

摘要： 国家重点研发计划《高速精密悬浮轴承》对保护轴承跌落承载能力的要求是：转子质量不小于3000 kg，跌落转速不小于3000 r/min，抗跌落次数不小于10。基于此开展了对保护轴承设计研发及跌落失效机理的研究。提出了两种适用于跌落工况的陶瓷球混合保护轴承方案：满装球无保持架方案和非满装球带保持架方案。搭建了包含动力学、热学在内的转子跌落仿真模型，对不同方案跌落过程的受力和发热过程进行了仿真。将保护轴承安装到试验台架中进行测试，验证了仿真模型的有效性。在测试中发现无保持架保护轴承发生严重失效。对失效轴承的损伤情况进行观察和检测，发现由于滚动体间摩擦因数大，滚动体发生卡死现象，使滚动体与滚道、内圈与转子间发生持续干摩擦，造成内圈严重烧伤与磨损。

关键词: 磁悬浮轴承, 保护轴承, 转子跌落, 轴承损伤, 失效机理