Simulation And Experimental Study On High Efficiency And Low Wear Rate Of Electrical Discharge Machining With Graphite Electrode

As an important part of non-traditional machining,electrical discharge machining(EDM)has been widely used in aerospace,energy power and mold manufacturing etc.,which has many advantages such as without macroscopic cutting force,machining ability for special shaped cavity,suitability for various materials.In EDM process,tool electrode is the key factor for machining performance.The electrode of different material has a great influence on material removal rate(MRR),electrode wear rate(EWR)and surface roughness(SR)of workpiece.Graphite electrode has been widely used in the field of EDM because of its high discharge efficiency,low wear rate,small deformation,high thermal stability,low density and other advantages.Exploring the EDM mechanism and improving the machining performance are extremely important to achieve high machining efficiency and machining quality.Using graphite electrode to explore the EDM mechanism and optimizing processing parameters for high MRR and low EWR,a large number of experiments and relevant analysis are carried out in this paper.Firstly,in order to investigate the micro process and EDM mechanism,the temperature field simulation of EDM based on single pulse discharge experiment is carried out.According to the experimental results of single pulse discharge,the energy distribution in the discharge process is analyzed,and the discharge plasma radius is fitted.Based on the Gauss heat source model,the thermal conduction model of single pulse discharge of graphite electrode is established.On the basis of this model,the finite element simulation of temperature field is carried out,and the temperature simulation model is obtained and verified by experiments.The MRR and EWR were predicted and verified by the simulation model.In order to explore the effect of processing parameters on the EDM,single factor experiments are carried out.The experiment scheme design and experiment error elimination are carried out.The influences of electrode polarity,pulse duty cycle,pulse width,peak current and servo reference voltage on MRR,EWR and SR are studied respectively.Based on the temperature field simulation model,the experimental phenomena and causes are analyzed theoretically,and some suggestions on parameter selection in actual machining are given.The response surface experiment of EDM with graphite electrode is designed referring to the above experimental results.The regression equation of MRR and EWR are obtained and verified by experiments.The processing parameters for high MRR and low EWR are found.What?s more,the phenomenon of negative tool wear during the experiments is explored.The surface microstructure,composition and functional characteristics of the carbon layer of graphite electrode are explored and analyzed.