Research On Bubble Pulsation And Motion In Gap Flow Field During EDM

In the process of EDM,the volume fraction of bubbles and the concentration of etching products in the machining gap flow field have important effects on machining efficiency,machining stability and electrode loss.In the process of EDM,the erosion products are easy to accumulate in the bottom machining gap,and failure to discharge them in time and effectively will cause discharge short circuit,secondary discharge,arc pulling and other phenomena,which affect the machining efficiency of the EDM process.A lot of research shows that the pulsation process of bubbles in the discharge process affects the movement state of the gap flow field and the distribution of erosion products in the gap between electrodes,and then affects the machining efficiency of the edm process.From the point of view of numerical simulation and experimental research,the pulsating process of a single bubble near the workpiece surface and the moving process of a continuous discharge bubble are numerically simulated to study the influence of the pulsating process of a bubble on the movement and distribution of erosion products in the interpole gap flow field.It is of great significance to improve the distribution of erosion products and machining efficiency in EDM gap flow field.First of all,based on Rayleigh spherical bubble theory,a simulation model of single bubble pulsation process in near workpiece surface electric spark discharge was established,and the single bubble pulsation process near the rigid wall was numerically simulated.The pressure field and velocity field changes during the expansion,contraction,collapse and rebound stages of single bubble were analyzed,and the change rules of single bubble pulsation process in near workpiece surface electric spark discharge were studied.Secondly,on the basis of numerical simulation of single bubble pulsation process in near workpiece surface EDM,a simulation model of bubble movement process in gap flow field of continuous discharge EDM process is established to numerically simulate the interaction and fusion process between bubbles,analyze the movement law of bubbles in the flow field and its influence on the distribution of corrosion products,and study the movement law of bubbles in bottom gap flow field of continuous discharge EDM process.Finally,on the basis of EDM experiments,the simulation results of bubble pulsation process are verified;Then,the experiments of EDM hole machining are carried out to prove the influence of the bubble movement process in the machining gap on the distribution of erosion products.