Design And Performance Study Of Reduce-Collision Raceway For Cageless Ball Bearing

Cageless ball bearings are used as backup bearings for active magnetic bearings in aerospace engines,wind turbines and other applications.Although the stiffness and load bearing performance of cageless ball bearings are higher than conventional bearings,but the rolling element without cage restraint will occur inevitable collision,accelerating the wear of the rolling element and reducing the performance of the bearing,in response to this problem,this paper designed a kind of local reduced-collision raceway in the bearing outer raceway that can the motion track of the rolling mass center coincides with the bearing pitch circle,so as to realize the discrete state of the rolling element without contacting each other.This paper carries out the structural design and dynamics study of cageless ball bearings with reduced collision raceways.First of all,the design of cageless ball bearing with reduced-collision raceway is carried out.In order to ensure that the motion trajectory of the mass center of the rolling element always coincides with the bearing pitch circle,according to the principle of automatic discrete of the rolling element,the cross-sectional shape of the reduced-collision raceway is determined to be composed of two circular arcs,and the velocity change equation of the rolling element is established to determine the structure of the reduced-collision raceway.For the designed reduced-collision raceway structure,analyze the change law of contact point between rolling element and reduced-collision raceway,establish the equation of contact trajectory curve between reduced-collision raceway and rolling element,and the equation of groove curvature center curve which can characterize the shape of reduced-collision raceway structure.Combine the equation of contact trajectory with bearing geometry,establish the constraints of design parameters of reduced-collision raceway structure,and establish the relationship between design parameters of reduced-collision raceway structure and discrete spacing of rolling element,so as to provide the basis for the subsequent dynamic analysis.Secondly,analyze the influence of the local reduced-collision raceway on the speed of rolling element and the discrete spacing.According to the theory of bearing dynamics,the geometric interaction between the rolling element and the conventional raceway,the reduced-collision raceway and the adjacent rolling element as well as the calculation model of friction force are analyzed;through the force analysis of the bearing components and ignoring the axial motion of the bearing system,the set of dynamic differential equations of the rolling element and the inner ring is established.The system of kinetic differential equations is solved by the fourth-order ADAMS prediction correction algorithm programmed in Matlab software to obtain the rotational velocity and displacement of the rolling element and the adjacent rolling element ball spacing for different structural design parameters,analyze the velocity-displacement phase diagram of the rolling element,and determine the optimal range of the structural design parameters of the rolling element.Finally,the simulation model of the cageless ball bearing with reduced-collision raceway is established in Solidworks software,and the dynamics simulation is carried out by Adams software to verify the discrete performance of the reduced-collision raceway on the rolling element,and to determine the influence law of the reduced-collision raceway on the discrete effect of the rolling element under different working conditions.In order to compare and analyze the theoretical model and simulation analysis,high-speed photographic image acquisition and vibration test analysis are carried out for cageless ball bearing with reduced-collision raceway to further verify the effect of reduced-collision raceway on rolling element variable speed,to give the vibration acceleration values for cageless bearings with or without reduced-collision raceway,and to determine the effect of reduced-collision raceway position on bearing performance and its reduce collision effect.In this papers,through the research of cageless ball bearing with reduced-collision raceway,the collision between rolling elements in cageless ball bearing is reduced,which provides technical support to improve the performance of cageless ball bearing and expand its application.