| Stainless steel has good corrosion resistance,high-temperature resistance and mechanical properties,and is widely used in medicine,nuclear power,aviation,ships and other fields.However,in the process of processing,the plasticity of stainless steel is large and the phenomenon of work hardening is serious,which easily leads to poor surface quality and low service life of the processed parts.As one of the important indicators of surface quality,the residual stress on the workpiece surface will affect the stress state and fatigue life of parts.Therefore,the research on the residual stress of stainless steel machining has important theoretical significance and application value for actual machining.In this paper,AISI 304 stainless steel is taken as the research object,and the milling residual stress prediction model is established by analytical method to analyze the influence of processing parameters on the surface residual stress of stainless steel.The main research contents are as follows:Theoretical study of residual stress in the orthogonal cutting state.Using the non-equal shear zone theory,the orthogonal cutting force model is constructed,and the mechanical stress in the orthogonal cutting process is studied through the Hertzian contact theory.Based on the mirror heat source method,the temperature model of orthogonal cutting is established,and the research on the thermal stress of orthogonal cutting is carried out in this way.Combining the total stress characteristics of mechanical stress and thermal stress,combined with the stress evolution process such as elastoplastic loading,unloading and stress release,the orthogonal cutting residual stress is further scientifically evaluated.Residual stresses in orthogonal cutting are systematically investigated by means of mechanical stresses,thermal stresses and residual stresses.Theoretical research on milling force and milling temperature.Through the discretization research of the milling process,combined with the orthogonal cutting theory,the bevel cutting force model is constructed.Analyze the micro-element cutting state of the existing milling cutter helix angle,and accurately evaluate the milling force characteristics.A simplified model of milling temperature is established by using the superposition method of moving line heat source temperature.According to the various rules of milling force and temperature under different process parameters,the influence of processing parameters on milling force and temperature characteristics is analyzed.Theoretical study of milling residual stress.Based on the milling force model and the orthogonal cutting theory,the mechanical stress behavior and characteristics in the milling state are studied.Combining the image heat source method and the moving line heat source temperature superposition method,the thermal stress change caused by milling behavior is analyzed.For the existing mechanical stress and thermal stress,the elastic-plastic incremental accumulation theory is used to solve the analytical model of the milling residual stress,and the influence of processing parameters on the milling surface residual stress is deeply explored.In this paper,the milling characteristics of 304 stainless steel are systematically studied by combining theory,simulation and experiment,and the influence of processing parameters on milling characteristics is explored.The research results provide a theoretical basis for improving the milling quality of stainless steel and provide a certain reference for the reasonable selection of milling parameters. |
