Analysis of discharge channel characteristics based on three-phase flow dielectric characteristics in USV-MF assisted WEDM-LS

In this paper, considering the effects of the characteristics of the three-phase flow dielectric in the discharge gap flow field on the discharge channels in the ultrasonic vibration and magnetic field assisted low speed WEDM (USV-MF assisted WEDM-LS), the model of discharge channel including discharge position and size of discharge channel is established. Firstly, a mechanism of bubble-particle bridging breakdown was proposed under working condition of cutting workpieces with large thickness. Then a prediction model of the discharge point position in USV-MF assisted WEDM-LS under three-phase flow dielectric characteristics based on the breakdown mechanism was performed, and FEM software COMSOL was used to simulate and analyze this model. By comparing with the experimental results of discharge point position captured by high-speed camera, the accuracy of the prediction results of discharge point position in USV-MF assisted WEDM-LS was verified, it showed that the model can explain the dielectric breakdown more accurately. Next, the model of radius of discharge channel including magnetic field intensity, electric field intensity, medium pressure, and surface tension of discharge channel was established, and the influence of USV and MF on the size of discharge channel was analyzed theoretically. The radius of discharge channel in USV-MF assisted WEDM-LS was obtained by solving the partial differential equation in MATLAB. According to discharge point position and radius of the plasma discharge channel, surface morphology of workpiece was simulated by COMSOL. Finally, the experiment of photographing the discharge channel in USV-MF assisted WEDM-LS was carried out to verify the above model. It showed that the trend of the simulated results of discharge channel position is the same as that of the experimental results, and the error of peak height value between simulated and experimental results is within 6%.