Study On Mechanism And Residual Stress Control Of Ultrasonic Rolling Finishing

Ultrasonic rolling finishing strengthening technology is a new surface treatment technology,the traditional rolling and ultrasonic technology are organically combined,so that the workpiece surface organization produced strong plastic deformation,surface finishing strengthening effect,and a certain thickness is formed in the surface residual compressive stress,can significantly reduce the surface roughness and improve the hardness of the workpiece to improve the wear resistance,etc..In this paper,the typical aluminum alloy material is taken as the research object,and the key process parameters are taken as experimental factors.To Aluminum Alloy 7050 as the research object,select the static pressure parameters as influencing factors,ultrasonic polishing experiments,microscope observation and microstructure of 3D surface topography of the workpiece processed by that ultrasonic rolling "peak",the surface of different process conditions to obtain the(including surface roughness,surface topography)analysis of macro and micro experimental study found that roughness is due to the increase in the initiation of surface micro cracks cause analysis,the formation and evolution law of 3D surface processing,the rough surface of large workpiece surface topography was observed,analysis of the causes of variation of the surface roughness.Hertz contact theory and elastoplastic model analysis based on the change of microhardness were measured using a microhardness tester,hardening of the surface before and after the processing layer of the hardening layer depth are analyzed,based on the hardness distribution trend under different pressure and hardened layer depth and the surface hardness of the regression calculation using origin fitting the empirical formula of 7050 surface hardness and depth of hardened layer of ultrasonic rolling Aluminum Alloy to instruct the actual processing,the research has deep processing micro parts surface layer hardness value distribution,workpiece surface exploration has mechanical properties and its distribution along depth direction.With the help of the blind hole method to measure residual stress instrument on residual stress after different processing parameters of ultrasonic detection,residual rolling technology can form a certain depth of compressive stress,using three to force measuring instrument,detection in the actual process of three forces,and the surface residual stress of mutual contact force change between the Z confirmed to stress is an important factor affecting the change of the residual force,in the protection of macro surface integrity(roughness,hardness,residual stress)at the same time,in order to obtain high amplitude and depth stability of compressive stress and strengthening layer as the optimization index,search process find reasonable parameters.