Research On Mechanical Characteristics Of High-speed Electric Spindle Rolling Bearings

Rolling bearings are supporting and transmitting components widely used in high-speed electric spindles.Its mechanical characteristics have a significant impact on the dynamic characteristics of electric spindle systems.The key to the research on the mechanical characteristics of rolling bearings is how to accurately calculate the stiffness and damping.Therefore,this paper takes ball bearings and tapered roller bearings as research objects,the theoretical research,finite element analysis and experimental verification of stiffness and damping are carried out.The research contents include:(1)Based on Hertz contact theory and elastohydrodynamic lubrication theory,a comprehensive stiffness theoretical model of rolling bearings considering external load,centrifugal force,gyroscopic moment,preload,rotation speed and oil film thickness was established.The load distribution characteristic of bearings was analyzed,and the influence of structure,load and lubrication parameters on the comprehensive stiffness of rolling bearing was also analyzed.The stiffness characteristic of the lubricant film was studied and the influence of different parameters on it was analyzed.(2)The finite element model of rolling bearings was built by ANSYS and the contact characteristics were analyzed,the best constraint application method for the rolling bearing simulation analysis was discussed.The stiffness was calculated by fitting the relative displacements of the inner and outer rings under different loads.Through the finite element analysis under the actual bearing simulation conditions and comparison with the calculation results of the theoretical model,the correctness of the theoretical model was verified.(3)The multigrid method was used to establish a point or line contact comprehensive damping calculation model for rolling bearings,and a comprehensive damping calculation formula considering the bearing external load,centrifugal force,spin,thermal effects,and lubricant film was derived,the oil film pressure distribution and oil film thickness distribution in the contact area were obtained.The change tendency of the comprehensive damping with external load,speed,film thickness and viscosity was analyzed.(4)The test bench for mechanical properties of rolling bearings was designed,the influence factors of comprehensive stiffness and damping were experimentally verified based on theoretical research and simulation analysis,and the influence rules of various influencing factors on the comprehensive stiffness and damping of rolling bearings were obtained.It verifies the correctness of the theoretical model and the reliability of the finite element model.