Study On The Mechanism Of Ultrasonic Vibration Aided Electrical Discharge Machining In Gas And Its Simulation

Ultrasonic vibration electrical discharge machining (UEDM) in gas is a new technology that has been developed in recent years, with a view to the protection of the environment. During the machining process, the tool electrode is formed into a thin-walled pipe, and high pressure gas medium is supplied through it. Ultrasonic vibration of workpiece could improve the machining process. And this method could machine any electric materials. Study on the method would impulse the development of electrical discharge machining.In this dissertation, based on abundant literatures, discharging process of UEDM was analyzed systemically. Firstly, the charge forming and moving process in the gas media was analyzed. Then the heat conduction process was analyzed. The mathematic model and expression of the heat conduction process with the changing of parameters and phase changes were constructed. And material-removal-rate mathematic model was also established, in which the effect of gas pressure was considered. The results of theoretical analysis and experiment showed that ultrasonic vibration could enhance the material removal rate (MRR). And the ultrasonic vibration could improve the quality of the workpiece surface.Temperature fields of one pulse machining in gas were simulated. Changes of the temperature fields and shapes of the dents with the change of the discharging current were simulated. The results showed that the ratio of the depth to the diameter of the dent became larger with the augment of the discharge current. Also, the effect of discharge current on material removal rate and surface roughness was studied experimentally. Experimental results showed that the material removal rate and the surface roughness increased with the current. The experimental results were similar with the theoretical formula and the simulation results. Observed from SEM pictures, the crater in gas was found less than that in traditional liquid.Ultimately, thermal stress and strain field was simulated by the method of indirect...