Research On Ultrasonic Rolling Preparation Technology Of Surface Microtexture

Ultrasonic rolling is a new surface equal material processing technology,which combines two processing forms of static pressure rolling and ultrasonic impact.Combined with the motion control system,it can form controllable plastic deformation on the surface and improve the surface performance.At present,the common surface micro texture preparation technologies include laser processing,micro EDM,abrasive jet processing,ion etching,photolithography and so on.In this paper,a new technology of micro texture preparation by ultrasonic rolling is proposed.The effects of rolling process parameters on texture surface morphology and properties are studied by finite element analysis and experiment.The finite element simulation model of surface micro texture prepared by ultrasonic rolling is established,the distribution law of surface displacement and residual stress is studied,and its variation law with rolling process parameters is analyzed.The results show that obvious groove morphology and material accumulation are formed on the ultrasonic rolling surface,and the residual stress layer dominated by compressive stress is formed.Among the rolling process parameters,the static pressure has the greatest influence on the surface residual stress and displacement,and the amplitude has little influence.The optimal parameters are obtained as follows:static pressure 600N,amplitude 7 μm.The feed speed is 1000mm/min.The micro textures of straight line,concentric circle and sine were designed.The micro textures were prepared on the surfaces of 304 stainless steel and 45#steel by ultrasonic rolling equipment.The effects of rolling process parameters on the surface morphology of the materials were studied.The results showed that the surface of ultrasonic rolling samples formed a stable and regular micro texture morphology,and the texture depth increased with the increase of step distance.The texture morphology of 45#steel surface is very clear,the degree of deformation is small,and the texture depth is weakly affected by step.304 stainless steel has a large degree of deformation.At the same time,due to the phenomenon of "sticking knife",a certain degree of surface damage is formed.This damage can be reduced by changing the step distance and texture morphology.Affected by the processing path and whether the reciprocating processing method is adopted,the variation law of the surface morphology of the three textures with step length is obviously different.The surface hardness,crystal phase and wettability of ultrasonic rolling samples are tested,and the influence of rolling process parameters on the textured surface properties of ultrasonic rolling is analyzed.The results show that the hardness of samples after ultrasonic rolling is significantly increased,the grain on the surface of 45#steel is significantly refined,and the surface of 304 stainless steel is significantly transformed from austenite to martensite.The surface hardness and crystal phase of the two materials also have obvious differences with the rolling process parameters,which is due to the different deformation strengthening mechanism of the two materials during ultrasonic rolling.Compared with the substrate,the contact angle of textured surface by ultrasonic rolling tends to increase.The contact angle of 304 stainless steel is larger than 45#steel as a whole.The contact angle of the two materials is consistent with the change of rolling process parameters,and the texture morphology has a significant impact on the change law of contact angle.