In the cutting test of the vertical lathe, great attention is paid to the end face and outer circle roughness of the workpiece, and one of the keys to determine its quality is the rigidity of the system. The system rigidity includes the rigidity of the frame structure, the rigidity of the support bearing, etc., during which the rigidity of the bearing often depends on its axial preload. Therefore, it is particularly important to reasonably set the axial preload of the bearing to fully consider the influence of temperature and load.