Research On Surface Finishing Strengthening Technology Based On Ultrasonic Vibration Extrusion

This paper proposes an ultrasonic vibration surface finishing and strengthening technology,which mainly strengthens the surface of the part to improve the comprehensive performance of the surface of the part(such as surface roughness,surface hardness,surface residual compressive stress,etc.).Ultrasonic vibration surface finishing and strengthening technology superimposes ultrasonic vibration on the basis of traditional extrusion processing methods,and uses the physical and mechanical effects of ultrasonic to make the ultrasonic extrusion tool head produce great instantaneous acceleration and energy concentration effects in a small local area.This mode of action can use a small static extrusion force to cause plastic strain on the surface of the part to improve the surface quality of the part.Compared with the traditional surface strengthening process,this new processing method has significant advantages.This thesis first studied the mechanism of ultrasonic vibration in the surface finishing and strengthening process of ultrasonic vibration,and then analyzed the motion trajectory and separation characteristics of the ultrasonic extrusion tool head,and used the dislocation theory in elastoplastic mechanics to analyze the surface layer after ultrasonic impact from a microscopic point of view.The plastic deformation process of metals.Then optimize the design of the ultrasonic vibration surface finishing and strengthening system,design the structure of the sandwich composite horn piezoelectric ultrasonic transducer(also called the integrated transducer horn structure),and assemble the ultrasonic vibration system.Design the size of key components,analyze the factors that affect the stability of the ultrasonic vibration surface finishing and strengthening processing system,and make improvements.Then,a finite element simulation model was established for the ultrasonic vibration surface smoothing and strengthening process,and the influence of static extrusion force,feed speed and ultrasonic amplitude on the residual stress distribution on the surface of the impacted workpiece was analyzed and compared.Finally,the actual ultrasonic vibration surface smoothing and strengthening processing experiment is carried out for the bar made of 45# steel,and the processing parameters(such as spindle speed,feed rate,static extrusion amount,extrusion times,ultrasonic amplitude)are controlled,and the comparison is analyzed and compared.The influence of surface quality(such as surface roughness,surface hardness,surface residual compressive stress and metallographic structure),and finally draw conclusions.The conclusion shows that the superimposed ultrasonic surface finishing and strengthening process has a strong advantage in improving the surface quality of parts.It can effectively reduce the surface roughness,increase the surface hardness,preset higher residual compressive stress,and refine the surface layer of the metal.It can improve the mechanical properties of the surface of the parts and comprehensively improve the quality of the processed surface.