Study On Surface Integrity Of Titanium Alloy Under Tool Mesoscopic Characteristics

Titanium alloy is widely used in aerospace field because of its excellent strength,heat resistance and light weight.However,due to the low thermal conductivity of titanium alloy,the heat accumulated in the cutting area is easy to accelerate the tool wear,which has adverse effects on the machined surface quality,and has become one of the factors limiting the application of titanium alloy materials.The results show that the microtexture can improve the cutting performance,reduce the cutting temperature and prolong the service life of the tool,so that better machined surface can be obtained.Therefore,in this paper,two mesoscopic characteristics of blunt circular edge and micro texture are introduced into ball end milling cutter,and as a starting point,the surface integrity of titanium alloy milling workpiece is studied,and the influence of micro texture mode and tool edge passivation parameters on the surface integrity of workpiece is analyzed,The research contents are as follows:Firstly,based on the two-dimensional cutting model of tool contact area,the influence of tool edge and flank on the machined surface is analyzed,and the tool contact area in the machining process is deduced;The finite element simulation model was established,and the mesoscopic characteristic parameter range of the tool was designed.The influence of the micro texture on the workpiece surface temperature was analyzed by orthogonal simulation experiment;Based on the laser marking machine,the micro texture of the tool flank is prepared,and different parameters of the blunt edge radius are processed by the grinder,which provides a reference for the subsequent research on the surface integrity of mesoscopic geometric features milling titanium alloy workpiece.Secondly,the evaluation index of workpiece surface integrity is studied,and the surface roughness,residual stress microhardness and metamorphic layer are selected as the evaluation indexes to build the titanium alloy milling experimental platform and detect the milling workpiece surface;The influence of tool mesoscopic characteristics on the surface residual height of titanium alloy was analyzed,the mechanism of residual stress was revealed,the variation of surface microhardness was analyzed,and the formation factors of surface metamorphic layer were explored based on dislocation theory,which laid the foundation for the subsequent optimization of workpiece surface integrity.Finally,taking the surface integrity of the workpiece as the evaluation index,the multiple regression model of the mesoscopic geometric feature parameters is established;the multi-objective optimization of the model is carried out with the help of particle swarm optimization algorithm,and the optimization results of the mesoscopic characteristics are obtained.The research content of this paper provides a new direction for improving titanium alloy processing technology and realizing high efficiency and high quality processing.