Study On Effect Of Precision Milling Process Parameters On Surface Integrity

Surface integrity is one of the key factors affecting the fatigue life of parts,mainly including residual stress,surface roughness and hardness.but the surface integrity index of the workpieces is directly related to the final processing method of the surface.In recent years,with the continuous development of precision milling technology,milling is a final surface processing method.Its function is getting more and more attention.The thesis is based on the evaluation criterion of the surface integrity of anti-fatigue manufacturing.Launch on the basic theory and experimental research on the influence of milling process parameters on the surface residual stress and surface quality of parts.The following research is carried out.Firstly,the cause of the residual stress in milling workpiece is analyzed at the theoretical level.The simulation analysis model of workpiece milling based on elastoplastic deformation is established,and the trend of the influence of different process parameters for the residual stress on the surface of the workpiece is analyzed.It provides a theoretical basis for subsequent processing experiment and process parameter setting.Then,On the basis of theoretical analysis,the experimental research on residual stress distribution of A16061 is carried out.The effects of spindle speed,feed per tooth,milling depth and milling width on the surface integrity of A16061 workpiece were studied.According to the test results,the optimum process parameters are summarized in the experiment.As follows:when the spindle speed 10000 r/min,the feed per tooth 0.015 mm,the milling depth 0.5 mm,the milling width 11.8 mm,the maximum influence on the surface residual stress,the depth about 245?m,the maximum residual compressive stress of 147.67 MPa,and the peak depth of about 80?m.In this thesis,the surface roughness of the workpiece obtained by A16061's milling parameters with large spindle speed and small feed is relatively low,which is in the range of 0.1-0.3 ?m.Through the study of the milling of A16061,it is proved that the residual stress can be introduced into the milling process and the residual stress distribution can be effectively controlled,and under the better process parameters,the residual stress of the aluminum alloy surface can be rationally introduced and regulated,and the better surface quality can be achieved.Finally,On this basis,the study of precision milling about gear steel 18CrNiMo7-6 for the post mixed water jet shot blasting is carried out.Through the study and discovery,after milling,the residual compressive stress depth layer introduced by the back mixing water jet shot is moved deeper into the deeper layer,and the maximum value change is not large.The precision milling along the surface to the workpiece after the hard milling.To a certain depth,the residual stress curve before and after milling is basically parallel or overlapped.After this depth,the effect of precision milling on residual stress is smaller.Through the analysis of the surface roughness data of precision milling,the surface roughness of the workpiece is between 0.05 ?m and 0.25 ?m.when the process parameters are the spindle speed of 6000 r/min,the feed per tooth 0.02 mm,and the milling depth 0.05 mm,the optimal surface quality Ra is 0.0823 ?m.After the precision milling,the hardened layer still exists on the workpiece surface,and the hardness value is between the original sample and the post mixed water jet peening hardness value.Through the analysis of the orthogonal test data,the optimum technology for the surface integrity index of the workpiece is obtained:the spindle speed 4000 r/min,the feed 0.02 mm per tooth,the milling depth 0.06 mm.And the optimum process parameters are verified by the single factor experiment respectively.