Study On Dynamics Of Angular Contact Ball Bearing For Ultra-high Speed Grinding Electric Spindle

Bearing is one of the key factors affecting the performance of high speed motorized spindle.The reasonable bearing support form,configuration mode,bearing structure parameter and initial preload force have obvious influence on the static and dynamic characteristics of the spindle system.This topic is aimed at the angular contact ball bearings used in the super high speed grinding of high power electric spindle.The influence of bearing structure parameters and preload on bearing stiffness is studied.A set of bearing-rotor system is designed with laboratory equipment,then the static and dynamic characteristics are experimentally studied and the simulation results of FEM simulation are validated,which indirectly verifies the correctness of the bearing stiffness.The main contents and research results of the thesis are as follows:1.The quasi statics model of angular contact ball bearing is studied,and the matrix model of calculating the five-DOF stiffness of angular contact ball bearing is deduced by analyzing the bearing ball movement,force and force balance equation;2.For angular contact ball bearing dynamic characteristics problem,firstly,the influence of the axial preload on the correlation characteristics of diagonal contact ball bearings is studied,including the bearing stiffness,the contact load inside the bearing,the working contact angle and the lubrication characteristics of the bearing,and the relation graph is given.Secondly,the influence of radial load on bearing internal contact load,bearing working contact angle and bearing inner and outer ring displacement are analyzed,and the relation graph is given;Then,the influence of bearing structure parameters on the stiffness of diagonal contact ball bearing is studied,and the relation curve diagram is plotted,then some concrete measures to improve the stiffness of angular contact ball bearing are given which provide parameter support and help for the bearing selection and arrangement of high speed motorized spindle.The research of this part can provide data support for dynamic and static analysis of bearing-rotor system.3.Aiming at the bearing-rotor system of high speed grinding,firstly,the three-dimensional solid finite element model and beam element model of the bearing-rotor system are established by FEM simulation.And the beam element model can not only reduce the simulation time greatly,but also ensure the accuracy of simulation results.Secondly,the static characteristics of the bearing-rotor system are analyzed,and the influence of bearing type and bearing material on the static stiffness of the spindle is mainly studied which provides a reference for the bearing selection of the spindle system.Then,by analyzing the dynamic characteristics of four different bearing-rotor systems,some measures to improve the dynamic stiffness of high speed motorized spindle are proposed which provides data reference and theoretical support for the structure design of high speed motorized spindle;4.Based on the existing equipment of the laboratory,a set of bearing-rotor system is designed and processed for the practical needs of the subject.Firstly,the natural frequencies of the spindle are analyzed by the finite element simulation method which is compared with the natural frequency of the spindle measured by the experiment,which verifies the correctness of the FEM simulation results.And then the static experiment of the bearing-rotor system designed for the subject is carried out.By comparing the experimental results with the simulation results,the accuracy of the stiffness matrix of the bearing and the reliability of the simulation results are verified.And the experiment is helpful to reduce the experimental cost and improve the experimental efficiency.