Research On Wear Evolution Of Ball Bearing Raceway Under Starved Lubrication

Raceway wear is one of the main failure modes of ball bearing.The wear of the raceway will change the surface topography of the contact between the rolling body and the raceway,thus further affecting the service life of the ball bearing.The formation of bearing raceway wear has a certain process and is affected by many factors such as relative motion of friction surface and contact mechanics.Complex motion forms such as sliding,spin and gyro will occur when ball bearing rolling body moves relative to the raceway.These complex movements produce different contact conditions,which affect the wear morphology of the raceway.At the same time,the lubricant will form a layer of oil film between the rolling body and the raceway.The wear of the raceway will be significantly aggravated when the lubrication is not sufficient.When the wear intensifies,the friction torque between the ball and the raceway increases.As a result,friction heat generation and thermal failure of the bearing are caused.Therefore,it is of great significance to make clear the wear evolution process and influencing factors of ball bearing raceway for bearing life prediction.Firstly,taking the ball bearing as an example,the elastic ball-curved raceway is equivalent to the rigid ball-straight raceway based on the Hertz point contact theory for subsequent studies.The size and distribution of contact stress before and after the ballraceway contact model are consistent with the real model.The three-dimensional equivalent contact model of ball-raceway was established by using the finite element tool Abaqus.Based on this model,the subroutine UMESHMOTION was redeveloped coupled with Archard wear theory.The redevelopment program can effectively simulate the wear condition of bearing raceway surface.Secondly,based on the boundary lubrication state,and considering the complexity of rolling bearing operating conditions,the multi-factor wear of bearing raceway was studied,such as radial load,wear times and complex movement form of bearing.The results show that the wear depth of bearing raceway increases with the increase of radial load and wear times,and shows a linear increase.The spin motion,gyro motion and sliding of the rolling body have a serious influence on the wear evolution and appearance of the raceway.The main reason for the change is that the complex motions change the relative sliding between the rolling body and the contact area of the raceway.The wear of the raceway is greatly affected by the sliding and gyro motion of the rolling body and the combined motion.Then,the paper studies on the influence of mixed lubrication on the contact and wear of rolling body and raceway.In fact,ball bearings need fluid lubrication to run smoothly and permanently.Lubricants will form a layer of oil film in the contact area to bear the contact pressure and improve the contact condition.When the bearing is in mixed lubrication,the ball-raceway contact area cannot form a complete oil film,so the contact situation becomes bad,and the wear also intensifies.Therefore,this paper studies the friction parameters of the bearing contact area with the change of oil deficiency,and carries out finite element study on the wear of the bearing raceway under different oil deficiency degrees.It is showed that lubricant can greatly improve the wear of the bearing raceway.Finally,the paper studies the friction heat generation and wear of the ball and the bearing raceway when the bearing raceway is in starved lubrication.The results show that the main heat source of the ball bearing is the friction heat generated by the contact between the steel ball and the raceway,and the tangential friction properties of the ballraceway determine the distribution of the raceway temperature field under the influence of complicated motion.The bearing friction heat generation caused by ball rolling is small,while gyro motion and sliding have the greatest influence on the bearing friction heat generation.When the friction heat generation phenomenon of ball-raceway becomes serious,the bearing temperature will continue to increase due to heat conduction.When the temperature rises,the thermal properties of the material lead to the expansion of the ball-raceway contact ellipse area,the decrease of the contact stress,but the wear rate of the bearing raceway does not change significantly.