| The cageless ball bearing has higher stiffness due to the increase of the number of rolling elements.As a spare bearing,it is used to support the rotor falling when the magnetic bearing fails to avoid contact between the rotor and the stator.Some scholars have designed reduce collision grooves on the outer raceway of cageless ball bearings to realize that the rolling bodies do not contact each other,and once the reduce collision grooves are worn,the rolling bodies will be collided.Therefore,this thesis studies the characterization of the outer raceway wear of cageless ball bearing with anti collision groove by the discrete element method,establishes the discrete element wear model of cageless ball bearing,and conducts research through theoretical analysis,simulation analysis and experimental verification.Firstly,the wear principle of the outer raceway of the cageless ball bearing is analyzed,based on which the bond fracture of the discrete element method is determined as the characterization of the wear of outer raceway of the bearing,and the outer raceway of the bearing is discretized into a particle system connected by the bond,respectively establishing the aggregate units of the contact between the rolling body and the particle system at the conventional outer raceway and the reduce collision groove,which provides a basic model for the establishment of the contact force equation of the subsequent particle system;The contact form between particles in the outer raceway is analyzed,the contact model between particles in the outer raceway is established,the energy conservation equation is established based on the arrangement of particles,and the normal and tangential elastic coefficients and damping coefficients of the contact between particles are determined;Finally,according to the discrete element bond theory,the bond model between the particles of outer raceway is established,and the fracture conditions of the bond between the particles of the outer raceway are determined to complete the bond fracture characterization of bearing outer raceway wear.Secondly,the bond fracture that characterizes the wear of the outer raceway is studied.According to the set element of the outer raceway particle system proposed above,the contact model between the rolling body and the set element of the outer raceway particle system is established.On this basis,the contact force equations between the rolling body and the set element at the conventional outer raceway and the reduce collision groove are established respectively,and the change law of the external force on the rolling body and the set element at different positions is determined;According to the arrangement mode of the particle system,the internal force change law of particles at different positions and different layers is analyzed,and the internal force transfer equation of the outer raceway particle system is established.The external force on the contact surface of the rolling body and the set element is substituted into the transfer equation as the initial value of the internal force of the particle system,and the internal force transfer equation is solved with MATLAB programming;By comparing the calculated internal force with the bond fracture condition,the bond fracture between particles in the outer raceway is analyzed,and the fitting equation between the number of particles falling off and the number of layers falling off due to the bond fracture is established to predict the wear amount and wear depth of the outer raceway.Finally,in order to verify the correctness of the bond fracture of the discrete element of the outer raceway of the bearing to represent the wear,this thesis uses the cageless ball bearing with reduce collision groove as the simulation and test object,and uses the simulation software EDEM to carry out simulation research on the bearing wear,to obtain the change law of the contact force between the rolling body and the outer raceway and the wear amount of the outer raceway of the bearing;The 12 groups of wear tests of cageless ball bearing with reduce collision groove at variable speed and load were carried out.The wear amount of outer raceway and the wear depth of reduce collision groove were measured by balance and super depth of field.The theoretical research,simulation analysis and test results were compared to verify the correctness of the wear characterization of cageless ball bearing outer raceway discrete element.In this thesis,through the research on the wear of the outer raceway of cageless ball bearing with reduce collision groove,it is proposed that the wear of the outer raceway is characterized by the fracture of the bond in the discrete element method,and the wear degree of the outer raceway and the reduce collision groove is determined.This research provides a theoretical guide for the design of cageless ball bearing. |
