Research On Analytical Prediction Of Residual Stress In Grinding

Residual stress has a significant impact on the performance and life of parts,and is one of the important indicators to evaluate the quality of the workpiece.With the development of modern computer technology,people hope to predict the residual stress of the workpiece through trial cutting of parts before large-scale processing of products.The formation of the residual stress of the workpiece in the grinding process is a complicated process,and the established residual stress analysis model and the experimental value still have certain errors.Under different grinding conditions and grinding parameters,mechanical stress,thermal stress and phase change stress have different effects on the final residual stress.Therefore,it is necessary to research the prediction model of residual stress according to different grinding stages.This paper mainly analyzes the theoretical model of residual stress in grinding.Through orthogonal test design,the grinding force,residual stress on the surface of the workpiece and mechanical stress in the process of small depth of cut grinding are researched.The main research contents and conclusions are as follows:(1)By analyzing the characteristics of the grinding process,based on the triangular distribution of grinding force on the grinding arc,a theoretical model of mechanical stress is established.According to the basic theory of heat transfer and the triangular heat source,the thermal stress of the workpiece due to the temperature increase during the grinding process is analyzed.Based on the established theoretical model of mechanical stress and thermal stress of grinding,through the elastoplastic loading and unloading theory and stress-strain release program,the theoretical analysis model of grinding residual stress is established.(2)The grinding parameters are selected to design orthogonal test,and the grinding force in the grinding process is analyzed by mathematical statistics.The research shows that: Grinding depth has the largest influence on grinding force,followed by grinding wheel speed,and workpiece feed speed has the smallest influence.At the same time,the influence of selected grinding parameters on grinding force is highly significant.Through the relationship between grinding force and grinding parameters,a linear regression method is used to establish the grinding force prediction model.And verified that the regression equation is highly significant At the same time,through the comparison of the experimental value and the predicted value of the grinding force,it is found that the established model is feasible..(3)The residual stress on the surface of the workpiece after grinding is analyzed.The research shows that: Under the selected parameter level,the grinding depth has the largest impact on the residual stress on the workpiece surface,followed by the workpiece feed speed,and the smallest impact on the grinding wheel speed.When the grinding depth is small,the residual stress on the surface of the workpiece after grinding is the result of the combined action of the original stress and the grinding stress.Based on the relationship between the residual stress and the original stress of the workpiece and the grinding parameters,a linear regression method is used to establish a residual stress prediction model.It is verified that the linear regression equation is highly significant,and the error between the predicted value and the experimental value is analyzed.(4)Based on the theoretical model of grinding force and mechanical stress in the grinding process,the mechanical stress distribution on the grinding arc is analyzed.And the relationship between the maximum mechanical stress of the workpiece during grinding and the amount of surface stress change after grinding is researched The research shows that: On the grinding arc,the mechanical stress is the tensile stress at the cutting position of the grinding wheel,and firstly increases and then decreases as the grinding arc increases.When the grinding wheel is close to the cutting position,it changes rapidly into compressive stress,and reaches the maximum at the cutting position value.The depth of mechanical stress on the grinding arc is limited,and it is only distributed on the surface.The mechanical stress during grinding is in the same trend as the amount of stress change on the workpiece surface after grinding.When the grinding depth is small and the cutting performance of the grinding wheel is good,the residual stress on the surface of the workpiece after grinding is mainly affected by the mechanical stress.