Study On Simulation And Experimental Of Electrical Discharge-assisted Milling Of Titanium Alloy

Ti6Al4V titanium alloy has excellent properties of high specific strength,good corrosion resistance and high heat resistance,and is widely used in important fields such as aerospace and nuclear energy industry.However,Ti6Al4 V titanium alloy is a typical difficult-to-machine material.It is easy to form heat accumulation in the conventional machining process,and it is difficult to dissipate the cutting heat.Aiming at the above problems,a new method of Electrical discharge-assisted milling(EDAM)is proposed in this paper,and its cutting mechanism and cutting performance are deeply studied.A three-dimensional finite element model of EDM temperature field was established to simulate the change law of material temperature field after Electrical discharge-assisted cutting,and a finite element model of Electrical discharge-assisted cutting was established to simulate its thermal coupling cutting process.The specific research contents are as follows:(1)Based on the theory of heat transfer,a three-dimensional finite element model of the temperature field of EDM preheating Ti6Al4 V titanium alloy was established,and the temperature variation law of single-pulse and continuous multi-pulse discharge was simulated and studied according to multiple sets of processing parameters.The EDM experiment of titanium alloy was carried out with the parameters of single-pulse simulation to verify the authenticity of the simulation under different energies.The results show that the correlation between the experiment and the simulation is good.And the larger the capacitance,the higher the EDM preheating temperature.(2)Based on the multi-pulse temperature field simulation of EDM and the Johnson-Cook material constitutive model and failure criterion of Ti6Al4 V titanium alloy,a thermal coupling finite element model of 3D orthogonal cutting of titanium alloy was established,and the finite element simulation of conventional cutting and Electrical discharge-assisted cutting was carried out.The simulation results of stress,cutting temperature and cutting force under the two cutting methods were analyzed,and the mechanism of Electrical discharge-assisted cutting was revealed.The simulation and experimental results show that compared with traditional cutting,Electrical discharge-assisted cutting performs better in reducing cutting force and stress in the cutting area,the cutting force and stress were reduced by 43.98% and17.27% respectively(C = 100000 p F).(3)In this paper,special tools and special machine tools for EDAM are designed and manufactured.Based on the thermal-mechanical coupling simulation analysis,several groups of conventional milling and EDAM experiments with different machining parameters are designed.The microstructure and composition of the denatured layer after EDM machining of titanium alloys were studied,and the microhardness of the denatured layer at different high temperatures and the cutting force during the cutting process were measured.The influence of EDM on the machinability of titanium alloys was analyzed by observing the surface quality,tool wear and chip morphology of the two machining processes.The results show that compared with conventional milling,EDAM can significantly reduce the cutting force by17.47% ～ 41.85%,and can effectively improve the surface quality and prolong the tool life.