Experimental Study On Electrical Discharge Drilling Of Particle Reinforced Aluminum Matrix Composites By Polygonal Hollow Electrode

It is a promising machining method of Particulate Reinforced Aluminum Matrix Composites(PRAMCs)machined by Electrical Discharge Machining(EDM),which can avoid the traditional tool breakage and reduce processing costs.However,EDM machining PRAMCs has its own defects caused by the reinforced particles in PRAMCs.The reinforced particles are usually electrical insulating materials,and their physical properties such as melting point and steam is several times higher than alloy,when PRAMCs machined by EDM,particles does not melt.So in the process,these particles plays a role to prevent the metal around from being melted.And the processing efficiency is inversely proportional to the fraction of particles in the PRAMCs.With the increase of the depth of processing,the discharge erosion efficiency will become worse,and the removal of particles will lead to the emergence of the secondary discharge phenomenon,making the process of instability.With the increase of the ratio of depth to diameter of the hole,the influence of these phenomena on the machining will be larger.This paper explores the special-shaped electrode machining PRAMCs material,and study the effect of Al2O3 PRAMCs drilled by polygon hollow electrode to verify whether the polygon hollow electrode can improve the machining environment and improve the EDM drilling efficiency to particulate reinforced aluminum matrix composites.Firstly,this paper introduces EDM erosion mechanism process and influence factors of machining PRAMCs.Secondly,this paper models and simulates the flow of machining gap between the polygon hollow electrode and the PRAMCs workpiece,and analyses the flow distribution and erosion particle concentration in the machining gap.Finally,through the single factor experiment,orthogonal experiment and response surface method,this paper survey the factor of peak current,pulse width,total factor ratio,spindle speed,flushing pressure impact on removal rate,tool wear rate,the tool relative wear of the polygon hollow electrode machining PRAMCs,compared with the circular hollow the electrode.The results show that under the same processing conditions,the material removal rate of the polygon hollow electrode is better than the circle hollow electrode and the loss rate is higher,but the tool relative loss is lower.In this paper,the machining effect of circular hollow electrode and polygonal hollow electrode on the deep hole machining is compared.The experiment results show that the material removal rate of the polygonal hollow electrode is better,but the surface roughness is larger.Through scanning electron microscopy images of the hole surface machined by the the polygon hollow electrode and the circular hollow electrode,the paper analyses the electrical discharge erosion situation by the polygon hollow electrode.It showes that the electrical discharge is more severe and single pulse energy has greater efficiency,and it indirectly verify that the improvement of chip removal of the polygon hollow electrode.