Low Frequency Vibration Assisted EDM Milling Process Simulation

In electro-discharge milling(ED-Milling), short circuit and arc discharge often occurs frequently. Applying vibration to the workpiece can effectively reduce the probability of short circuit and arc discharge, improve the probability of normal discharge, so as to improve the efficiency of ED-Milling. By using reasonable way of flushing in EDM, the molten particles can be removed out of the machining gap more easily and the machining efficiency of EDM can be improved. Making research on the flow field of the low frequency vibration assisted inner jetted dielectric ED-Milling machining gap and EDM workpiece surface temperature field is very improtant for understanding the basic rules of ED-Milling and revealing the mechanism of EDM.In this paper, through theoretical analysis, simulation analysis and experimental validation, researches on low frequency vibration assisted inner jetted dielectric ED-Milling machining gap and low frequency vbration assisted EDM temperature field have been made. The main research contents are as follows:Theoretical analysis on the flow field of the low frequency vibration assisted inner jetted dielectric ED-Milling machining gap has been carried out.2D-axisymmetric gap flow field mathematical model and molten particles distribution model have been established. The gap flow field simulation model has been established by using the finite element software Fluent. The simulation analysis on the gap flow field pressure, velocity, distribution of molten particles has been made.The impact of flushing pressure and rotation speed of the electrode on the gap flow field have been researched through simulation analysis and experiment verification. Results show that:The speed and pressure of the gap flow field increase with the flushing pressure. The improvement of the flushing pressure can make the molten particles be removed out of the bottom machining gap more easily, thereby improving the efficiency of ED-Milling. The gap flow field velocity increases with the rotation speed of the electrode. The rotation of the electrode can promote the molten particles move out of the bottom machining gap, thereby improving ED-Milling efficiency.The impact of the amplitude and frequency of vibration on the gap flow field have been researched through simulation analysis and experiment verification. Results show that:The vibration make the X direction velocity, Y direction velocity and general velocity of the fluid in the gap flow field faster and change periodically. The periodic change of the fluid velocity can make the molten particles be removed out of the gap flow field more easily; The X direction velocity and Y direction velocity of the fluid in the gap flow field increases with the increase of the amplitude. The particle average escape time decreases with the increase of the amplitude. The increase of the amplitude can reduce the accumulation of the molten particles on the surface of the workpiece and make the molten particles move out of the gap flow field more easily, so as to reduce the workpiece surface roughness and improve ED-Milling efficiency. The Y direction average velocity of the fluid in the gap flow field increases with the increase of the frequency. The particle average escape time decreases with the increase of the frequency. The increase of the vibration frequency can make the distribution of the molten particles in the gap flow fluid more uniform and reduce the accumulation of the molten particles on the surface of the workpiece.Theoretical analysis on the vibration assisted EDM temperature field of single pulse discharge has been carried out.3D-axisymmetric simulation model has been established with the finite element software Abaqus. The variation of the processed workpiece area with the single pulse discharge time and the changes of the width and depth of the single pulse discharge pit with discharge voltage are verified by simulation and experiment. Results show that:The width and depth of the single pulse discharge pit increase with the discharge voltage.increase.The low frequency vibration assisted ED-Milling temperature field has been researched by simulation and experiment. The width and depth of the workpiece groove and the temperature of the ED-Milling center area increase with the increase of the discharge voltage. The width and depth of the workpiece groove and the temperature of the ED-Milling center area decrease with the increase of the tool electrode speed. We can improve the discharge voltage and reduce the speed of the electrode to obtain higher machining efficiency or reduce the discharge voltage and improve the speed of the electrode to obtain better workpiece surface roughness.