高速主轴离心膨胀及对轴承动态特性的影响

以高速主轴系统为对象，将主轴转子和轴承内圈分别等效为等截面梁和空心圆盘，计算离心力作用下主轴转子和轴承内圈的径向弹性变形，并分析主轴转子与轴承连接状态随转速升高的变化趋势。考虑旋转部件的离心膨胀变形，建立高速主轴轴承动力学模型并进行试验验证。在此基础上，研究离心效应对主轴轴承径向预紧状态的影响，揭示高速主轴轴承动态特性随转速的变化规律。研究结果表明，离心力引起的径向膨胀变形使滚动体与轴承内、外圈之间的接触角减小，接触力增加。主轴轴承的轴向刚度和径向刚度均随转速的升高而降低。轴承内圈的离心膨胀变形对轴承轴向刚度的影响可以忽略不计，而能在一定程度上提高轴承的径向刚度。

Centrifugal Expansion of High-speed Spindle and Its Influences on Bearing Dynamic Characteristics

Focusing on a high-speed spindle system, the shaft and the bearing inner ring are modelled as a beam with the same cross-section and a hollow disk, respectively. The radial elastic deformations of the spindle shaft and the bearing inner ring under centrifugal forces are investigated. The changes of the connected state between the shaft and the bearing with speed are analyzed as well. Considering the centrifugal expansion of rotating components, a dynamic model for the high-speed spindle bearing is given with experimental verification. On this basis, the centrifugal influence on the radial preload state of spindle bearings are studied, and then the rules that how dynamic properties of the high-speed rolling bearing change with the speed are revealed. The results show that, the contact angles decrease, while the contact loads increase with the radial expansion deformation. Both the axial stiffness and the radial stiffness of spindle bearings decrease when the rotating speed increases. The radial expansion deformation of bearing inner rings due to the centrifugal force has an ignorable influence on the axial stiffness of bearings, while it can increase the radial stiffness of bearings to a certain extent.