Research On Method And Technology Of Debris Removal In EDM Micro-small Hole

When machining micro-small holes by EDM,as the machining depth increases,the debris and bubbles in the machining gap will be difficult to remove the machining gap.Which will accumulate in the machining gap and affect the machining efficiency.Therefore,in the process of EDM micro-small hole,it is necessary to add an effective method to change the flow state of the fluid in the gap flow field.Thereby promoting the discharge of debris and bubble.In this paper,the finite element simulation method was used to simulate and analyze the process of EDM micro-small hole under the action of the flushing and electrode rotation.Analyze the impact of the flushing speed and electrode speed on the gap flow field.Obtain the technological law that are beneficial to debris and bubbles removal.The main research contents and results are as follows:(1)Through the EDM hole test,the initial state of the bubbles and the number of debris generated by pulse discharge were obtained.The debris and bubbles random generation model was established by using the VOF,DPM model and secondary development(UDF)function in Fluent.Thus,the gas-liquid-solid three-phase flow simulation model of the gap field of the EDM micro-small hole was established.Wrote particle statistics program,which can show the removal effect of debris.(2)Based on the simulation model,the distribution of bubbles and debris in machining gap under single pulse and continuous discharge were simulated and analyzed.The results show that the expansion of multiple bubbles can only remove less debris.By adding the flushing method,the process of EDM hole under the action of unilateral flushing and internal flushing were simulated and analyzed.The results show that when the side flushing speed is doubled,the fluid velocity in the side gap is about five times the original,and the debris removal ability is enhanced.With the increase of machining depth,when the flushing speed is constant,the flow velocity of the fluid in the bottom gap is almost 0m/s.The debris and bubbles will accumulate on one side and cannot remove debris.When the internal flushing speed is doubled,the fluid flow rate in the side gap will also double.The processing depth has little effect on the fluid flow rate and debris removal.(3)The process of EDM hole under the action of cylinder,edge and spiral electrode rotation were simulated and analyzed.Obtained that the cylindrical electrode can promote the debris and bubbles to rise slowly along the side gap and evenly distributed around the electrode.The edge electrode can make the fluid produce upward speed at the edge of the bottom.The debris and bubbles rise faster in the side gap,and distribute more at the edge.The spiral electrode can make the fluid produce a spiral upward flow field,the upward flow velocity is about ten times the edge electrode,the debris and bubbles can rise rapidly along the spiral groove.It was found by changing the electrode speed,when the speed increases to 5000r/min,the number of particles in the bottom gap between the cylindrical electrode and the edge electrode will increase,and spiral electrodes will decrease.The results show that the cylindrical electrode and the edge electrode have a good debris removal effect at a specific speed,and the spiral electrode increases the debris removal ability with increasing speed.(4)Experiments of EDM holes under different debris removal conditions were carried out,observing the position of the burned wall on the inner wall of the hole.The results show that the location of the particles in the simulation is basically consistent with the location of the burn.Record the processing time when processing the hole in specified depth,got the change trend of the processing speed,the change trend of the particles number in the bottom gap is basically consistent with the simulation.,the simulation results are verified laterally.