关键词: 主轴轴承, 振动, 摩擦力矩, 灰关联度, 演化

Abstract: The dynamic performance of spindle bearing for precision machine tool is directly related to it’s comprehensive operation state. Accelerated life test and friction torque detection were conducted on the spindle bearing 7208B, and dynamic performance time series of vibration and friction torque were obtained at each time node of 80 hours, 160 hours, 240 hours, 320 hours, and 400 hours. Using the vibration and friction torque data of the first 80 hours as the reference sequence, the initial value grey correlation degree, mean value grey correlation degree, interval value grey correlation degree, relative correlation degree, and absolute correlation degree between the dynamic performance signals of other time nodes and the reference sequence were calculated to characterize the similarity between the bearing at each service stage and the initial state, and evaluate the degree of degradation of its dynamic performance. Then, multiple grey relational degree models were effectively integrated using the mean method, stepwise mean accumulation method, and membership function method to comprehensively quantify the evolution process of the dynamic performance of high-speed precision machine tool spindle bearings. The results indicated that the dynamic performance of the bearing would show significant degradation at the initial stage of operation, but the degradation behavior was relatively gentle between 160 and 320 hours, and after 320 hours when the degree of evolution was more severe. The overall evolution behavior shows a nonlinear degradation trend, showing the characteristics of significant degradation in the early stage, gentle in the middle stage, and accelerated in the late stage, and it is in good agreement with the change of the micro morphology of the same batch of test bearings.

Key words: spindle bearings, vibration, friction torque, grey correlation degree, evolution