Numerical Simulation And Experimental Study Of The Surface Properties Of Ultrasound Rolling Mechanism

Ultrasonic surface rolling processing is a newly developed surface nanocrystallization technology,which can greatly improve the comprehensive performance of metal surface.First,the dynamic response of AISI304 stainless steel suffered by ultrasonic surface rolling is investigated.In this connection,dynamic monitoring system based on the principle of piezoelectric effect if established and the frequency and amplitude of dynamic impact force which varies according to sine function are obtained.It is found that the impact force increase.Compared with static pressure.the influence of vibration amplitude is more significant.The motion state of processing tip is obtained by finite element simulation,and further sued for solving the elasticplastic spherical stress wave problem generated in dynamic impact process.The stress-strain state and velocity of any mass point at any time are provided through characteristic method.Second,energy distribution during ultrasonic surface rolling process is studied using finite element analysis,as well as definition and calculation of ultrasonic surface rolling process efficiency and power.Also,effects of ultrasonic surface rolling process parameters on surface characteristics are discussed.Simulation results show that residual stress distribution in surface layer is evener after ultrasonic surface rolling process treatment and the surface residual stress is compressive.Compressive stress first increases and then decreases with the increase of depth.The magnitude and depth of maximum residual stress and residual stress range increase as spindle speed and feed rate decrease and static pressure,Vibration amplitude,processing times increase.Surface roughness rises as spindle speed and feed rate increase and first decrease and thee increase with the increase of static pressure and vibration amplitude.Work hardening is characterized through the equivalent plastic strain.Third,Static pressure is one of the most important parameters in ultrasonic rolling.In this paper,the ultrasonic rolling process of AISI304 stainless steel was carried out,the influences of the different static pressure in ultrasonic rolling process on the sample surface topography,roughness,grain level of detail,with the depth varying surface micro-hardness and residual stress distribution were investigated using a comprehensive scanning electron microscopy,contact pin type roughness meter,metallographic microscope,micro-hardness tester and X ray diffraction analyzer.The results show that: The static pressure in the range of 300 N to 800 N can obtain better surface quality,but over 800 N will cause damage to the surface,the appearance of fine lines;Through XRD analysis,the higher the static pressure,the higher the degree of grain refinement,the width of the X diffraction peak is also small.;The depth and the hardness of the surface hardened layer increased with the increase of the static pressure,the hardened layer of 600 N increased 150 μm and the hardness increased by 35% compared with 200 N;The surface residual stress is compressive stress,and increases with the increase of static pressure increases,when the static pressure increases to 600 N,the maximum residual stress from the surface to the internal transfer of materials...