Research On The Combination Machining Technology Of Micro Edm And Micro Milling For Ti-6Al-4V Titanium Alloy

With the progress of science and technology,the development of micro intelligent devices with multi-function,low power consumption,high precision and high reliability has become a new trend of science and technology development.Titanium alloy has been widely used as a metal material due to its excellent physical properties and biocompatibility in aerospace,biological medical,petrochemical industry,shipbuilding and automotive fields.With the development of micro devices,how to efficiently fabricate micro structures with certain precision and surface quality on titanium alloy materials has become the focus of scholars at home and abroad.Therefore,in order to expand the machining technology of titanium alloy materials in the field of micro machining,this paper carried out the research on the micro EDM and micro milling combined machining technology direction of titanium alloy materials.In this paper,according to the physical properties of Ti-6Al-4V material,the JC constitutive model of Ti-6Al-4V material was used to describe the deformation and failure behavior of the material in the process of machining,and the three-dimensional milling model of Ti-6Al-4V material was established by using the finite element simulation software.The residual stress on the surface after EDM was simulated by cooling method.The influence of EDM surface on the micro-milling process was compared by comparing experiments with different cutting depths.It is found that the residual stress layer generated by EDM increases the cutting force and inhibits the formation of inlet burr.The simulation results are compared with the theoretical results and the actual average burr height.The maximum relative errors of the micro-milling force and the average burr height are 6.14% and 8.56%,respectively.In order to explore the technological rules of EDM,a single factor experiment of micro-EDM was designed considering the factors of machining polarity,peak current,charging capacitance,pulse width and so on.The experimental results show that higher machining efficiency and lower electrode loss can be obtained under the conditions of negative polarity,long pulse width and large current.Under the condition of low capacitance,more uniform recasting layer and better machining surface precision can be obtained.The electrode loss can be controlled at 3.59%,and the material removal rate can reach 17.09×10-3mm3/min.Based on the low electrode loss and high removal rate achieved by micro-discharge milling(EDM),the machining quality of workpiece surface was improved by micromilling.The process experiment of micro-milling EDM surface is designed.It is determined that the key to obtain better surface quality is the high spindle speed,the appropriate feed speed and the appropriate cutting depth.When the machining allowance is 30 ?m,the recasting layer formed by EDM can be completely removed by micromilling.In order to verify the feasibility of combined machining in production,the combined machining experiment of T groove was designed.After micro-EDM machining,the relative dimension error of slot width is 6.59%,and the surface roughness Ra is1.3657?m.After micro-milling finishing,the relative dimension error is 1.24%,and the surface roughness Ra is 0.3697?m.The combination machining process of high efficiency and high precision of T groove is realized in the same machine tool at the same station.