Study On The Dynamics Of Rolling Bearings In High-speed Spindles

With the advancement of technology,CNC machine tool spindles performance has been greatly improved.Rolling bearings as support structures as the rotor system are widely used in spindles,and its dynamics significantly different from the static mechanical properties,especially in the high-speed operation.Besides bearing supports have a significant impact on the overall dynamic behavior of the rotor system.Therefore,in order to fully study the dynamic performance spindle system and meet the needs of a new generation of high-speed spindles,a comprehensive study of high-speed rolling bearings is necessary.This paper focuses on the mechanical properties of high-speed rolling bearing spindle,carrying out the following tasks:(1)By using the quasi-static method and based on Jones&Harris high speed bearing parameters computing model.it studies the dynamic load distribution characteristics of rolling bearings.The impact of differrnt structural parameters and operation conditions on the actual contact angles,contact loads and deformations as well as deflections of the rings have been well studied.By analyzing the results of the calculations,an optimization bearing load distribution calculation model of easier calculation process and less coupling parameters has been proposed.The optimization model is verified with comparison shows that the model is well suited to solve the high-speed spindle rolling bearing load distribution.(2)When bearings run at high speeds,the dynamic stiffness will change greatly.,The relationship between external loads and the deflection of the bearing rings are analyzed according to the results of dynamic load distribution and bearing rings deflections.Load and deflection are further established through implicit functions.Using the implicit function derivation method,according to the definition of stiffness,the five DOF stiffness matrix can be built by the partial derivation of external loads with respect to five degrees of freedom deflections.Comparison with other literature or experiments have been studied to verify the feasibility of this computing model.(3)The clearances generated by manufacturing errors of rolling elements,bearing rings and race-ways have been considered and its impact on the dynamic load distributions or dynamic stiffness of the bearing has been studied.The study shows that:the manufacturing error of the rolling elements and the clearances it generated have less influence on dynamic performance while the manufacturing error of bearing ring or the radius of curvature of raceways have a relatively greater impact.From the study of the case it can be found the dynamic contact deformation and contact angles variations due to the bearing manufacturing error are relative larger with the increase of speed while the influence of speed on the stiffness variations due to the errors are smaller.(4)The principles and form of vibration of rolling bearings in high-speed vibration machine have been studied.Studies on the ball pass vibrations generated by geometry defects of the rolling bearing,manufacturing errors and the vibration due to time-varying stiffness have been studied.A CNC machine tool as a test rig has been investigated and shows verification of the presence of these vibrations forms.The results obtained have been used to analyze of the amplitude of the vibration and the magnitude of these effects on the overall system conditions.In summary,this paper studies the calculation of dynamic load distribution of rolling bearings,further optimization of its calculation process,the analysis and calculation of dynamic stiffness and bearing vibration etc..The research results for improving the spindle bearing design,manufacture,use and maintenance are of important theoretical significance and application value.