Research On The Residual Stress And Deformation Of Pure Iron Thin-walled Parts In Turning

Pure iron material has excellent electromagnetic properties,so it is widely used in the fields of electrical and electronic,national defense,aerospace industry and other fields.For thin-walled parts made of pure iron material,on the one hand,due to the high plasticity of pure iron material,the cutting performance is poor,which affects the surface quality and performance of the part.On the other hand,due to its weak rigidity,it is easily deformed during processing,and the redistribution of residual stress is one of the important reasons for the deformation of parts.Therefore,this paper takes pure iron thin-walled parts as the research object.Through theoretical analysis,finite element simulation and experimental test,the residual stress induced by turning of pure iron is studied,and the influence of the redistribution of machining residual stress on the deformation of thin-walled parts is analyzed.These studies provide a reference for improving the processing technology of pure iron thin-walled parts.The specific research contents are as follows:(1)Using the finite element software AdvantEdge,the orthogonal cutting simulation model of pure iron is established to analyze the thermal-force load affecting the machining residual stress of pure iron.Based on the cutting mechanism,an analytical model of the equivalent thermal-force load in orthogonal cutting is established.On this basis,considering the influence of the radius of the tool tip in the turning process,the functional relationship between the equivalent thermal-force load and the cutting parameters in the turning process is established.(2)Based on the equivalent thermal-force load,a simulation model of residual stress induced by turning of pure iron is established.In order to quantify the equivalent thermal-force load,the actual cutting experiment is carried out,and the cutting force coefficient,chip deformation coefficient,tool-work contact length and heat distribution coefficient in the third deformation zone are determined to provide basic data for the simulation model.Through the simulation model,the three-dimensional distribution of the residual stress along the depth direction and the feed direction is obtained.(3)The test experiment of residual stress in pure iron turning is carried out,and the test results are compared with the simulation results to verify the accuracy of the simulation model of machining residual stress.In addition,the influence of cutting parameters,tool tip fillet and tool coating on machining residual stress is studied experimentally.(4)Based on the mapping method,a simulation model of thin-walled spherical shell deformation caused by machining residual stress is established.Aiming at the turning process of thin-walled spherical shell,the velocity-dependent machining residual stress field on the spherical shell surface is constructed considering the influence of cutting speed on machining residual stress,and then the machining deformation of spherical shell caused by machining residual stress is predicted.On this basis,the influence of machining residual stress on the machining deformation of spherical shell under different cutting parameters is investigated.