Study On The Effects Of High Frequency Pulse On Discharge Process Of Micro EDM

With the development of science and technology,miniaturization,refinement and complication has been becoming an important developing trend of electromechanical products.In the process of micro-hole machining,micro EDM technology is widely used without considering the factors such as hardness and strength of materials.The traditional method of micro EDM is to use short-pulse duration and high frequency of EDM pulse power supply for processing,which can both improve the machining accuracy as well as efficiency.Micro EDM process,however,also could be affected by various mechanism under the condition of high frequency pulse.The effect of high frequency pulse on the discharge process of micro EDM mainly reflects two aspects:the electrode skin effect and the magnetic pinch effect of discharge channel under the high frequency pulse.The studies of this paper are as follows:(1)The skin effect principle with high frequency pulse of micro EDM electrode was analyzed.Based on the electrode skin effect of electromagnetic field theory and the induction current and electromotive force theory of the workpiece under the condition of electrode electromagnetic field,the coupling model of the electric field and magnetic field of micro EDM electrode under high frequency pulse were established.The single factor simulation method was used to simulate the skin effect under different pulse frequency,current and magnetic conductivity.Under the influence of pulse frequency,current and electrode magnetic conductivity,the current density and the electric field intensity distribution of the electrode face were obtained.Furthermore,under the influence of the skin effect,the current density distribution of the surface of the hole under different depth is obtained.The electric field intensity was calculated by current density on the surface of the electrode and the surface of the hole,and the discharge probability of the electrode face and bottom surface was calculated from the electric field strength.Finally,the total discharge probability of high frequency pulsed EDM was calculated and the discharge probability equation was obtained.(2)The effect of high frequency pulse on discharge channel was analyzed.Based on the electronic movement characteristics in the discharge channel of electromagnetic field,the coupling model of electric field and magnetic field as well as charged particle tracking under the influence of the strong magnetic pinch effect of high frequency pulse were established.The influence law of high frequency pulsed electromagnetic field on particle motion of discharge channel was studied and the effect of magnetic pinch on discharge channel energy transmission and distribution were analyzed.The influence of main machining parameters such as pulse frequency,peak current and dielectric conductivity on the magnetic pinch effect of discharge channel was verified and the contraction rule of electron beam in discharge channel was obtained.According to the law of electron beam movement in the discharge channel,the distribution of heat flux density with high frequency pulse was summarized,and the influence of heat flux density distribution on material erosion was analyzed.In this paper,the effect of high-frequency pulse frequency on electrode loss and material erosion in micro EDM is verified by combining the theory with simulations.The basic theory of high frequency micro EDM technology is developed,which is of important academic value.