Research On Ultrasonic Rolling Device And Its Processing Experiment

Ultrasonic surface rolling technology can significantly improve the surface quality of materials.It is a new type of surface strengthening technology,which widely used in aerospace,shipbuilding and automobile manufacturing and other fields.In this paper,the ultrasonic rolling device is designed at first,and the ultrasonic generator and transducer are selected,then the whole structure of amplitude transformer,rolling head and overall structure of the device are designed.Firstly,in the structural design of ultrasonic rolling tool head,the structure of 3 small cemented carbide balls supporting 1 large cemented carbide ball is adopted.The structure of the rolling head can rotate freely to avoid severe local wear and affect the processing quality;Secondly,the mode analysis of the transducer,the amplitude transformer and the rolling head device is carried out by using the finite element method,and its natural frequency and various vibration modes are obtained.At the same time,the harmonic response of the device is analyzed,and its harmonic response analysis curve is obtained to analyze whether the amplitude of the whole device meets the work requirements.Thirdly,according to the structural characteristics of the lathe and the whole rolling device,the fixed fixture of the rolling device on the lathe is designed.The clamping device takes the zero amplitude position of the amplitude of the transformer as the fixed connection point of the clamping device,and at the same time,a pressure sensor is installed inside the device.It not only can ensure the normal operation of the device,but also can realize the accurate measurement of static pressure.Secondly,based on the analysis and testing of the dynamic impact force in the process of ultrasonic rolling,the finite element software ABAQUS is adopted to establish the 3D finite element model of ultrasonic surface rolling processing.The single-point impact analysis of 18CrNiMo7-6 material is carried out,and the results,which include the compression depth,the compression radius and the maximum compressive stress,are consistent with the results calculated by Hertz theory,so as the effectiveness of the finite element model is verified.Then the model is used to analyze the motion state of the tool head,and the residual stress is given.Finally,the device was used for ultrasonic rolling test on the lathe,using NPFLEX type three-dimensional surface topography measurement system,HV-1000 micro hardness tester,VHX-2000 E super depth of field three-dimensional microscope system and Proto high-speed high power X-ray residual stress analyzer was used to observe and analyze the surface roughness,surface microhardness,surface 2D morphology and surface residual stress of the samples before and after processing.The influence of process parameters(spindle speed,feed rate,static pressure,rolling times,amplitude)on surface quality was studied.Then,the test data of surface roughness,surface microhardness and residual stress of the samples after ultrasonic rolling were analyzed by range analysis and variance analysis.The results show that the surface roughness of the sample is reduced from the original 3.003?m to 0.468?m after ultrasonic rolling.Ultrasonic rolling produces different degrees of work hardening on the surface of the workpiece.The surface microhardness is increased from 360.9Hv to 442.9HV.The microhardness increased by 22.7%;the surface of the surface after processing was more flat and formed a continuous flat surface;the maximum residual compressive stress appeared at 80 ?m from the surface about-672.04 MPa,and the high hardened layer reached 300 ?m.The order of significance of surface roughness is: feed amount > spindle speed > number > amplitude > static pressure;the order of influence on surface hardness is: static pressure > number > amplitude > spindle speed > feed;the order of the degree of significance of the residual stress is: static pressure > amplitude > number > feed > spindle speed;the integrity of the sample after ultrasonic rolling is significantly improved.