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Overheat failure mechanism and improvement scheme of ball bearing for aero electromotor

Published:2024-05-24 author:LI Shili, ZHANG Wenhu, LI Xinqing, et al. Browse: 644 Check PDF documents

Overheat failure mechanism and improvement scheme of ball bearing

for aero electromotor

LI Shili1, ZHANG Wenhu1, LI Xinqing2, ZHAO Lei2, DENG Bo2

(1.School of Mechatronics Engineering, Henan University of Science and Technology, Luoyang 471003, China;

2.Xinxiang Aviation Industry Group Co.,Ltd., Xinxiang 453000, China)

Abstract: During the aero electromotor's test operation, abnormal noise was detected. Upon disassembly, it was discovered that the ball bearings at both ends of the electromotor shaft system had suffered from overheating failure, grease carbonization, cage fracture, as well as wear on the inner and outer rings, among other issues. To address the overheating failure problem in the ball bearings of an aero electromotor, a failure analysis of the bearings at both ends of the electromotor shaft system was conducted, and an improvement plan was formulated. Firstly, a failure analysis of the ball bearings at both ends of the electromotor shaft system was carried out based on experience, and several structural improvement options were proposed. Subsequently, a thermalstress coupled aero electromotor bearing-rotor simulation analysis model was established using COBRA AHS software, and contact stress and temperature field analyses were performed for different improvement schemes. Finally, the results of the simulation analyses under various conditions were compared to derive the overheating failure mechanism of the bearings. A corresponding improvement plan was developed and validated through experiments. The results show that the heat deformation of the rotating shaft is the main cause of overheating failure of the ball bearing of the aero electromotor. The heat deformation of the rotating shaft compresses the bearings at both ends, making the maximum contact stress between the rolling element and the raceway up to 2 512.0 MPa. Under overload conditions, the bearing friction heat generation is intensified, resulting in a sharp rise in temperature up to 219.1 ℃, grease carbonization failure due to high temperature, poor lubrication conditions make the bearing early failure. By replacing the supporting bearings at both ends of the electromotor with angular contact ball bearings, the maximum temperature of both ends of the bearing is 96.6 ℃, and the maximum contact stress is 1 866.1 MPa, which reduces the operating temperature of the bearing, improves the axial bearing capacity of the bearing, and makes the operating life of the electromotor more than 1 200 h.

Key words: running life of motor; ball bearing; bearing overheating failure principle; thermal deformation of rotating shaft; angular contact ball bearing; analysis of contact stress and temperature field; grease carbonization

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