考虑热变形影响的主轴轴承动态特性

针对角接触球轴承高速工况下内部易产生大量的热量、温升过高而引起轴承零件热变形,导致轴承内部沟道曲率中心与球中心几何位置关系发生变化，进而影响动力学状态的问题,基于轴承分析的拟静力学理论,考虑了轴承内部摩擦功耗生热和轴承零件的热变形。利用热网络法划分主轴单元热网络节点,定义节点之间的热阻抗,建立了稳态热网络模型。分析了不同工作转速和载荷下各节点温升导致的轴承零件的热变形,得出了轴承动态特性和热特性之间的耦合关系模型,并分析研究了轴承内部的动力学特性。结果表明:随着轴承工作转速和载荷的变化,考虑热变形和不考虑热变形时的轴承接触载荷和接触角有显著不同,高速条件下轴承内部的热变形对轴承的动态特性影响巨大,是轴承在正常使用期间出现故障的主要原因之一。 

Dynamic property of spindle bearing considering the effect of thermal deformation

A lot of heat will be produced inside an angular-contact ball bearing under high speed conditions, and high temperature rise will cause thermal deformation, leading to the changes of geometric position relationship of bearing internal channel curvature center and ball bearing center. Finally, the bearing dynamic state, in turn, will be affected. On the basis of the analysis of the bearing quasi-statics theory, the heat production caused by the bearing internal friction and the thermal deformation of bearing components were considered. Using thermal network, the spindle unit was divided into network nodes, and the node hot impedance was defined, thereafter, the steady state thermal network model was established. The thermal deformation of bearing components, caused by each node temperature rising under different working speeds and loads, was analyzed. The coupling relationship model between the bearing dynamic properties and thermal properties was established, and the bearing internal dynamic properties were analyzed. The results showed that considering the thermal deformation or not, the bearing contact load and contact angle with the change of bearing working speed and the load were significantly different. Under the condition of high speed, the bearing internal thermal deformation has a significant impact on bearing dynamic properties, becoming one of the main causes of bearing faults during normal use.