静压支承摩擦副变形流热力耦合求解与实验

FLUID-THERMAL-MECHANICAL COUPLED SOLUTION AND EXPERIMENT ON DEFORMATION OF BEARING FRICTION PAIRS IN HYDROSTATIC BEARING

摩擦副变形对静压支承摩擦学性能有显著影响,不均匀变形会引起润滑油膜破裂和干摩擦,严重时导致静压支承摩擦失效。针对环形缝隙节流静压支承,运用计算流体动力学、弹性理论和有限元法对静压支承摩擦副变形进行流热力耦合求解,得到了旋转速度和工作台自重对支承摩擦副变形的影响规律和摩擦失效机理。并进行了实验验证,数值模拟结果和实验值吻合较好,验证了数值模拟方法的正确性。研究结果表明:随着旋转工作台转速增加,间隙油膜温度升高,热变形增大。工作台自重产生摩擦副的弹性变形对热变形有均匀化作用,但其挤压效应会加大热变形,造成工作台和底座的变形为内边靠近外部开口的喇叭状。工况继续恶劣,润滑油黏度急剧下降,局部油膜迅速变薄,出现干摩擦润滑,导致静压支承摩擦失效。

The deformation of friction pairs has a significant influence on friction performance of hydrostatic bearing, and the non-uniform deformation will result in oil film rupture, dry friction, and even friction failure. The fluid-thermal-mechanical interaction model of oil hydrostatic bearing with annular slit restrictors is established. The deformation of hydrostatic bearing friction pairs has been solved through fluid-thermal-mechanical coupled method based on computational fluid dynamics, elastic theory and finite element method. The relationship among the deformation of hydrostatic thrust bearing and rotational speed and workbench weight is established, and its deformation distribution law is revealed. A test rig is established for testing deformation. The results show that the experimental data are basically identical with the simulation results, and demonstrate the validity of the proposed numerical simulation method. The results prove that the clearance oil film temperature of hydrostatic bearing rise sharply and the thermal deformation is also increasing with the increase of rotational speed. The thermal deformation are homogenized by the elastic deformation caused by the workbench weight, but the squeeze effect will increase the thermal deformation. The deformation of the rotating workbench and the base is like a trumpet. The inner edge is closing and outer edge is opening. By further increasing the rotational speed and load weight, the lubricating oil viscosity declines sharply, the oil film grows thin quickly, the bearing friction pair exhibits uneven deformation, and the local bearing friction pairs sustain boundary lubrication or dry friction which may cause the friction failure.