The Process And Mechanism Of Electrical Discharge Grinding Of Polycrystalline Diamond

Polycrystalline diamond is widely used in cutting tool because of its many excellent mechanical and physical properties,and a typical super hard material.However,the super-hard and wear-resisting featurs make it very difficult to form and process,it seriously hinders the popularization and application of it.The electrical discharge grinding technology is one of the effective processing method of polycrystalline diamond,and has a high research value and broad application prospect because of its unique advantages.The mechanism of electro-discharge machining and the process of electrical discharge grinding of Polycrystalline Diamond have been studied.This paper has drawn some valuable conclusions in the discharge characteristics of electro-discharge machining,material removal of polycrystalline diamond and characteristic analysis of electric discharge grinding process.These would be helpful to solve the problem of the hard forming and play an important role in promoting the application of polycrystalline diamond.Firstly,the discharge characteristics and mechanism of electro-discharge machining of polycrystalline diamond have been studied by single pulse discharge machining experiment.Studies have shown that the breakdown voltage and discharge maintaining voltage of polycrystalline diamond in electro-discharge machining were higher than the ordinary materials;The micro geometric morphology of the workpiece materials after processing has been observed by SEM,the heat generated by the electric spark discharge made metal binder be melted and evaporated,and caused the shedding of diamond grains was the main form of discharge erosion of polycrystalline diamond have been found.Furthermore,polycrystalline diamond was one of brittle materials,which caused local temperature rising rapidly and the temperature made polycrystalline diamond been split in the discharge process,also found that the bigger diamond particles were,the more obvious of the splitting traces were left.Secondly,the characteristics of electrical discharge grinding has been analyzed.It was found that the installation error and roundness error of disk electrode had an important impact on the size of discharge gap,this is not conducive to the stability of the discharge process,while the online turning function of electrical discharge grinding could effectively reduce the impact;In addition,the rotating electrode not only made the discharge point shifted rapidly,which was conducive to improve the surface quality of the workpiece material,but also accelerated the flow of working fluid,so it was helpful to dislodge debris particles from discharge gap.Finally,electrode rotation speed,peak current,pulse duration,inter-pulse interval and polarity have been studied by uniform design.The results have showed that in the material removal rate of polycrystalline diamond,the peak current effect was most obvious,followed by the electrode rotation speed and machining polarity,the inter-pulse interval and pulse duration were the last;and in the surface roughness of polycrystalline diamond,influence levels in turn were peak current,pulse duration,inter-pulse interval,polarity and electrode rotation speed.In addition,the five factors were studied by single factor test and this would be able to provide reference for the selection and optimization of process parameters in electrical discharge machining.