Analysis And Simulation On Material Removal Process Of Powder Mixed Near Dry Electrical Discharge Machining

In recent years, EDM, which is an important part in modern manufacturing industry, has achieved a rapid development. It’s playing a more and more important role in micro and nano fabrication, mirror face processing and material removal process for semiconductor material and superhard material. Using gas-liquid-solid three phase flow mixtures as its dielectric medium, powder mixed near dry electrical discharge machining (PMND-EDM) technology, has a broad application prospect. It can overcome the disadvantages of EDM in fluid and EDM in gas and improve the machining efficiency and surface quality and has a broad application prospect. Because of its properties of high temperature, short time, small gap and difficult to measure, this paper researches on material removal of PMND-EDM using computer simulation technology. The main work is as follows:The basic principles, features, applications and limitations of EDM is demostrated and the current research status at home and abroad of simulation research on EDM has been discussed. On this basis, the research scheme of material removal and simulation during PMND-EDM was established based on this.The experimental setup was designed and manufactured. Its working process was introduced and then the function of three phase flow dielectric was studied based on the breakdown mechanism of gas medium. Then, by means of the streamer theory, the micro gap break down procedure of PMND-EDM was discussed.During PEDEDM process, the single pulse discharge can be divided into four period:ionization, medium breakdown, debris ejection and deionization.Using finite element method (FEM), the single pulse discharge process of PMND-EDM was simulated. Based on the principle of the EDM thermal erosion, the heat flux formulas with discharge channel radius and boundary conditions were derived and heat transfer model of single pulse discharge during PEDEDM was established. The model was calculated through FEM package ABAQUS and the temperature field was obtained. The results of simulation have verified the feasibility of the established model.The theoretical model of gap flow field during PMND-EDM has been established. Use the simulation software FLUENT to simulate the flow field in the discharge gap.Researches on the pressure distribution, the velocity distribution and silica powders distribution in the discharge gap was done, Influences of different factors on the flow field, material remove rate (MRR) and tool wear rate (TWR) of PMND-EDM were discussesed. Experiments were carried to verify the results of simulation.This paper researches on the machining mechanism of PMND-EDM.Simulations on the single pulse discharge and gap flow field are done. It further defines the material removal mechanism and provides the theory basis for PMND-EDM. The conclusions that obtained are helpful to guide practical application.