Research On Discharge Ablation Machining Based On Rotating Multi-channel Electrode

With the advancement of technology and the development of industry,new materials and new structures are widely used,and the processing requirements of difficult-to-process materials such as high-temperature alloys,high-strength steels and composite materials with high strength and high hardness are increasing.Electrical Discharge Machining(EDM)ablation is a kind of high-efficiency EDM technology,which utilizes the huge chemical energy generated by the combustion of metal and oxygen to remove the workpiece.It has the advantage of high processing efficiency and is suitable for processing difficult-to-process materials.However,the ablation reaction releases a large amount of energy,which makes the processed surface quality relatively poor.In order to improve the surface quality of the workpiece after EDM ablation,this paper combines multi-channel discharge with EDM ablation,and proposes a method of multi-channel discharge ablation based on rotating multi-channel electrode.This method achieves multi-point ablation in one pulse discharge cycle,breaking the limitation of one channel in traditional electric discharge machining,and significantly improving the EDM ablation efficiency.At the same time,the multi-channel discharge disperses the discharge energy,which effectively improves the surface quality of the workpiece after EDM ablation.This discharge mode could highly solve the contradictions between the machining efficiency and quality.The main research work of this paper lists as follows:(1)This paper combines multi-channel discharge with EDM ablation,and proposes a method of multi-channel discharge ablation based on rotating multi-channel electrode.Besides,a multi-channel discharge ablation milling system is constructed according to the technical principle,including machining experiment platform,gas-liquid atomization system and rotating multi-channel electrode.(2)The multi-channel discharge ablation processing mechanism was studied and the equivalent circuit model of multi-channel discharge was established.And it was found that the micro-etching process of multi-channel discharge ablation processing can be divided into four stages: multi-point discharge,multi-point activation,multi-point ablation and chip removal.In addition,the multi-channel discharge ablation and single-channel discharge ablation comparison experiments were carried out,and the comparative analysis of the electric erosion pits and the discharge waveform verified that the multi-channel discharge can disperse the discharge energy and improve the surface quality of the workpiece.(3)The relationship between the size of the electric erosion pits and the number of discharge channels was analyzed by temperature field finite element simulation and verified by single-pulse discharge experiments.In addition,the relationships between the number of discharge channels and the open circuit voltage,the interelectrode distance,the pulse width,the number of electrodes were studied respectively.(4)Explore the processing characteristics and technological Law of multi-channel discharge ablation.In this paper,a comparative experiment of multi-channel discharge ablation and EDM ablation with GH4169 was performed.The results show that compared with EDM ablation,the material removal rate(MRR)of GH4169 with multi-channel discharge ablation increased by 73.7%.In addition,as the multi-channel discharge dispersed the discharge energy,the surface roughness of the workpiece decreased by 14.6%,surface micro-cracks decreased,the crack widths and crack lengths decreased.Moreover,the process experiments on oxygen concentration,low-voltage current,duty cycle,pulse width and electrode material were carried out,and the influence of relevant parameters on multi-channel discharge ablation was studied.