基于权重法的机床主轴可变预紧力确定方法

Optimal Preload in Variable Preloading of Machine Tool Spindles

目的研究不同转速、载荷条件下机床主轴轴承的最佳预紧力,满足高速机床主轴全速段性能要求.方法建立基于拟静力学的轴承分析模型,计算不同转速、负荷条件下满足轴承使用寿命的最大轴向预紧力,和能够限制轴承陀螺旋转的最小轴向预紧力,得出预紧力取值的上下限.通过试验分析轴向预紧力对电主轴轴承温升和振动的影响.结果在低速范围内,轴向预紧力的变化对主轴振动和轴承温度无明显影响.在中速范围内,随着轴向预紧力增加,主轴振动有较明显减弱,轴承温度有较明显增加.在高速范围内,随着轴向预紧力增加,主轴振动大幅度减弱,轴承温度大幅度增加.结论在每个转速范围内分别引入不同的预紧力上下限权重值,得出满足高速机床主轴全速段性能要求的轴承最佳预紧力.

The optimal pretightening force of the main shaft bearing of the machine tool under different working conditions is studied to meet the performance requirements of the full-speed section of the high-speed machine tool spindle,so as to realize a high-efficiency spindle system. Based on the quasi-static,a bearing analysis model is established. By calculating the maximum bearing preload that satisfies the bearing life under different speed and load conditions,and the minimum bearing preload that can limit the rotation of the bearing’s gyroscope,the upper and lower limits of the preload value can be obtained. The effect of axial preload on the temperature rise and vibration ofthe electric spindle bearing is analyzed by the test method. At lowspeeds,the change in axial preload has no significant effect on the vibration of the spindle and the temperature of the bearing. In the medium speed range,as the axial preload force increases,the vibration of the main shaft is significantly weakened,and the temperature of the bearing increases significantly. In the high speed range,as the axial preload force increases,the vibration of the main shaft is significantly weakened,and the temperature of the bearing is significantly increased. In each speed range,the weight values of the upper and lower limits of different preloading forces are introduced respectively,and the optimal preload of the bearing that meets the performance requirements of the full speed section of the high speed machine tool spindle is obtained. The speed range is segmented,considering the requirements of different working conditions on the spindle stiffness and temperature rise,different weight values of upper and lower limits of preloading force are introduced in each range of speed.