Study On Micro-topography Of Ultrasonic Rolling Extrusion Process Of Precision Bearing Inner Ring

Precision rolling bearings are the key of aerospace,high-speed transport and military equipment and other high-tech areas,the improvement in the performance of the ring surface can maximize the avoidance of mechanical failure caused by early failure,which is the key to the performance and reliability of its installed equipment.Ring surface performance refers to the surface micro-morphology and surface layer of physical and mechanical properties of factors such as a comprehensive manifestation.Compared with the traditional roll extrusion,the ultrasonic roll extrusion process has a series of advantages,such as low rolling friction force and low surface roughness.At the same time,the residual compressive stress can be formed on the surface of the ring.In this paper,the precision bearing inner ring is taken as the research object,using the ultrasonic roll extrusion technology,the formation mechanism of the surface microtopography of ultrasonic rolling extrusion is studied,and the influence of the processing parameters on the surface micro-topography of the bearing ring is discussed.Based on the theory of metal elastic-plastic deformation,the relationship between the tool head and the inner ring of the precision bearing during the process of ultrasonic roll extrusion is analyzed.The contact mechanics model and kinematic model of the tool head and the precision bearing inner ring is established.The mechanical properties of the small deformation of the tool head and the inner ring is studied.The forming principle of surface micro-topography of ultrasonic roll extrusion is analyzed,and the theoretical model of micro-profile height of ultrasonic roll extrusion is established.The influence of different processing parameters on the surface micromorphology is also discussed by using MATLAB simulation software.The dynamic simulation model of the inner ring ultrasonic roll extrusion is established by using ABAQUS simulation software,and the influence of different processing parameters on the surface metal flow and surface roughness of the inner ring is analyzed.The formation mechanism of surface micro-topography of ultrasonic roll extrusion process is revealed.The experimental scheme of ultrasonic roll extrusion under different processing parameters is developed.The influence of three processing parameters on the surface roughness of the ring is analyzed by measuring the surface roughness of the ring by the white light interference microscope.At the same time,the theoretical simulation analysis is carried out to reveal the formation mechanism of the surface micromorphology of ultrasonic roll extrusion.The surface roughness prediction model of the inner ring of ultrasonic rolling and extrusion is established by using the second order response surface method considering the interaction of ultrasonic roll extrusion parameters,and the processing parameters is optimized to determine the optimal combination of processing parameters.The experimental results show that the parameters of ultrasonic rolling process has significant influence on the surface roughness of the parts.In the range of 150 N ~ 300 N,the surface roughness of the parts decreases with the increase of pre-extrusion pressure,the minimum value can reach Ra 0.268.When the force exceeds 300 N,the surface roughness increases with the increase of pre-extrusion pressure.With parts speed and tool head feed increase,the surface roughness showed increase trend.The prediction model of surface roughness,which can effectively predict the surface roughness of the inner ring of precision bearing under different ultrasonic roll extrusion processing parameters.