Research On Vibration Performance Of Motorized Spindle And Calculating Method Of Bearing Life

Motorized spindle is widely used in industrial field.It has the advantages of simple and compact structure,high efficiency,low noise,small vibration and high accuracy.In the manufacturing of bearing,the rolling elements always have dimension errors,and such dimension error will affect the stress of bearing and the vibration performance of motorized spindle,it also affect the life of bearing.This thesis take supporting bearings of the motorized spindle as the research object,quasi-static model of bearing with and without considering dimension errors of the rolling elements is established through using Hertz theory and Ferrule control theory,and the force of each rolling element is calculated by MATLAB programming.With a concrete example,the author studies the influences of external load and dimension errors of the rolling element on bearing force.Also,this thesis take the rotor of motorized spindle as the research object,the dynamic model of the rotor with and without considering the dimension errors of the rolling elements is established by use of transfer matrix method.Through numerical iteration,the natural frequencies and mode shapes of the rotor are calculated with ideal precision and different machining precision and calculated results are compared.The author also study the track of the bearing axis,the unbalanced response of the rotor,the influences of axial load on the vibration of the rotor under ideal precision and different precision of the rolling element.Using L-P theory,the fatigue life model of supporting bearings of the motorized spindle which can calculate the fatigue life of bearings is established.The influences of rolling element machining precision on the life of bearings are studied and the curves of fatigue life are obtained.The influences of axial load,radial load,speed of rotor on the life of bearing are also studied.The research results obtained in this thesis will be beneficial for further research of the vibration performance of motorized spindle and life of supporting bearings in the motorized spindle.