Mechanical Analysis And Simulation Of Ultrasonic Rolling Strengthening Of Bearing Rings

As an important basic part of the rotating body in the supporting mechanical equipment,the surface properties of the ferrule are the key factors affecting the bearing reliability and fatigue life.As an emerging surface strengthening technology,ultrasonic rolling strengthening technology can effectively reduce the surface roughness of the material and preset the residual compressive stress at a certain depth from the surface layer,which has good applicability to the surface performance strengthening of the bearing ring.Through theoretical analysis,simulation and orthogonal test method,this paper studies the series of mechanics and interaction problems of ultrasonic rolling strengthening applied to bearing rings.Taking the bearing ring material 42 CrMo steel as the research object and based on the theory of elastoplastic mechanics and the principle of contact mechanics,the strengthening process is regarded as the elastoplastic contact deformation behavior under the impact load.The mechanical properties of the contact area between the rolling ball and the material surface are analyzed.Based on the three-dimensional Hertz contact theory,the stress distribution state of the elastic deformation zone during the single impact of the rolling ball is given.According to the plastic yield criterion of the material,the equivalent shaping strain at any moment into the shaping yield stage is given.The motion relationship during the ultrasonic rolling process is analyzed.The results show that the spatial motion trajectory of the rolling ball is the coupling curve between the spiral and the sinusoid,moreover the equation of motion trajectory is derived.The rolling density is given according to the workpiece rotation speed and feed.The area of the single impact crater of the rolling ball is mainly related to the amplitude and static pressure.The relative rolling of the rolling ball to the surface of the material reduces the contact friction and helps to improve the quality of the surface after strengthening.The constitutive model of the material suitable for ultrasonic rolling is established.The finite element simulation software ABAQUS is used to simulate the ultrasonic rolling strengthening process.The results show that the compressive stress along the impact direction reaches a peak at a shallow depth,then gradually decreases to zero and evolves into a tensile stress in the material matrix.The static pressure has the greatest influence on the surface plastic deformation after impact.The effect of the amplitude on the deformation rate makes the degree of plastic deformation more severe.The ultrasonic rolling test under different intensification parameters is designed,and the surface residual stress data is collected by XRD equipment.The regression model is established to analyze the influence of each strengthening parameter on the surface residual stress.The results are basically consistent with the simulation analysis,the static pressure has the greatest influence on the surface residual stress after strengthening and the amplitude increases the residual stress value by dynamic impact.The workpiece rotation speed and feed rate affect the residual stress by affecting the processing density.