Investigation On The Mechanism And Control Method Of The Residual Stress Superposition For Aerospace Complex Thin-Walled Parts

In the high-speed milling process of the aerospace complex thin-walled parts,due to its thin-wall?complex structure?complex surface and deformation,it has been an important bottleneck restricting the development that how to control the superposition of residual stress and deformation caused by multi process machining and achieve its higher precision requirements.Therefore,in this paper,there will be carrying out deep-going study for the residual stress superposition distribution and the deformation caused by the curved surface machining,the plane machining,and single/multi process machining of complex thin-walled parts.The main research contents are as follows:?1?According to the study of ball-end cutter machining the complex surface of aerospace thin-walled parts,to establish the geometric model and the volume?Vuct?mathematical model of the undeformed chip of ball end milling.In order to achieve the optimal control of material removal rate,to compare and analyze the parameters of the undeformed chip volume.And based on the Third Wave AdvantEdge-3D model,carrying out the simulation machining of the single machining and double machining of ball-end cutter,to explore the influence of the coupling effect of the cutting force and heat on the distribution of residual stress on the surface and subsurface of the thin wall parts.On the premise of controlling the residual stress of workpiece curved surface,to carry out the optimization and analysis of different processing parameters.?2?To carry out the cutting simulation of aerospace thin-walled parts after three kinds of heat treatment,according to the residual stress distribution on the surface and sub-surface of the workpiece,the first heat treatment plan is optimized to process the blank by heat treatment.Secondly,to carry out the single process simulation cutting of thin-wall parts based on the Third Wave AdvantEdge-2D model,thus the distribution superposition of residual stress is revealed,and the single process parameters are optimized for the residual stress distribution of single process superposed.The plane cutting process of thin-walled parts is divided into the cutting in stage,stable cutting and cutting out stage,when the tool cuts into and cuts out the surface of the workpiece,there will be a certain residual stress impact on the surface of the workpiece.Through simulation and experimental verification,and the simulation parameters of single process residual stress impact are optimized,to analyze the superposition distribution regularity of residual stress impact in multiple cutting processes.?3?In multi process machining simulation,to carry out semi finishing and finishing simulation in the Third Wave AdvantEdge-2D model,and to carry out the heat treatment simulation for destressing in the heat treatment module of ABAQUS,to reveal the superposition distribution regularity of residual stress in multi process machining:after the destressing aging treatment,the residual stress?_xx on the surface of thin-walled parts is decreased by 36.5⁵4.2%,the residual stress?_xx on the subsurface of thin-walled parts is decreased by 20%³0%;the residual stress?_yy on the surface of thin-walled parts is decreased by 56.7%,the effect on subsurface is much smaller.Therefore,after machining and destressing stress aging treatment,the compressive stress on the surface of the thin-walled parts is greatly reduced,and the residual stress on the subsurface of thin-walled parts will enter a stable state quickly,the internal metal structure is more reliable,and the strength is more stable.The above researches also provides a theoretical basis for controlling residual stresses and deformation of thin-walled parts in multi process machining.In the end,taking the space complex thin-walled specimen as the research object,according to the previous chapters,the methods to control the residual stress are obtained,the optimization of cutting path and cutting parameters is carried out by classifying the plane and curved surface of complex thin-walled parts,to analyze the effect of the cutting path on cutting time and cutting force.The machining efficiency and residual stress distribution are verified by machining thin-walled parts.