Research On Micro-Milling/Micro-EDM Combined Process Of Graphite Electrode

With the continuous development of disciplines such as aerospace,biomedical,electronics and communications engineering,intelligent micro devices with low energy consumption,versatility,high accuracy,and high reliability have been more widely used,micro parts and micro parts.Structural processing has become the focus of domestic and foreign scholars.Single methods such as silicon-based MEMS technology,LIGA technology,micro-milling processing technology and micro-special processing technology are affected by the processing materials,processing costs,and the adaptability of complex microstructures,which greatly limits their application.Therefore,in order to expand the applicability of a single process,micro-milling/micro-EDM combined machining processes for graphite electrode has been studied.The JC constitutive equations of oxygen-free copper and the JH2 constitutive equations of graphite materials were obtained according to the intrinsic properties of the materials.The finite element simulation model of the micro-milling process of graphite and copper materials was established through finite element simulation software.L₁₆?4³?orthogonal table was used for orthogonal experimental simulation of the influence of spindle speed,feed per tooth,and axial depth of cut on micro-milling forces and machining surface quality.The simulation results show that the higher speed,lower feed per tooth and the depth of milling can effectively reduce the size of micro-milling force and the height of burrs;The average micro-milling force of graphite is much smaller than that of copper,and the edge of the micro-surface structure is basically free of burrs in the micro-milling process simulation of graphite material.The comparison between the simulation results of micro-milling force and the results of the theoretical formula shows that the coincidence between the simulation results and the theoretical calculation formula is relatively high,and the maximum relative errors of micro-milling force simulation results for oxygen-free copper and graphite are 8.451%and 11.603%,respectively.The single-factor experiment of micro-milling grooves considering the feed speed,spindle speed and axial depth of cut was designed and carried out.The experimental results show that:in larger spindle speed,appropriate feed rate and smaller axial depth of cut conditions,the slot width of the groove has good consistency,and the surface roughness Ra is low,resulting in the machining accuracy and machining surface quality are relatively high.Selecting graphite materials which has better micro-milling processing performance as forming electrode materials,then parametric modeling and micro-milling machining trajectory planning of electrodes which has square columns and quadrangular prisms micro-structure.The single formed electrode has better processing precision and processing quality,and the surface roughness value can reach 0.3134?m.The micro-three-dimensional structure of the shaped electrode with high precision was processed on the graphite material by micro-milling process.The dimensional error was less than 10?m,the maximum relative dimension error was 0.91%,and the surface roughness value was 0.3112?m.Using this shaped electrode to conduct micro-EDM experiments,Finally,the micro-EDM machining experiment was carried out with using this forming electrode,and a process which contains a rough,semi-finishing and finishing process for improving the precision of micro-EDM machining was proposed.The results show that the multi shaped electrode can effectively improve the micro-EDM machining in processing quality,processing accuracy and processing efficiency.The surface quality of the three-grouped electrode is 258.21%higher than that of the single electrode,and the machining efficiency has increased by 12.91%,it is proved that the micro-milling/micro-EDM forming process of graphite electrode is feasible.