混粉准干式电火花加工试验研究

提出一种混粉准干式电火花加工技术，其加工介质是气液固三相流混合物。试验结果表明，材料去除率与表面粗糙度随脉冲宽度、峰值电流及分层厚度的增大而增大，脉冲间隙作用则相反，提高空气压力既有助于提高材料去除率又可降低表面粗糙度，电极损耗随脉冲宽度增大而减小，当脉冲宽度较大时电极损耗接近于零，随峰值电流增大而增加。由于液滴、粉末的介入，气体介质的绝缘强度降低，放电间隙会增加，有利于电蚀产物的排除，可减少短路、电弧放电的发生率，加工稳定性得到提高，从而材料去除率得到提高；由于粉末会产生放电分散效果，电蚀凹坑深度减小，工件表面粗糙度降低。

Experimental Study of Powder-mixed Near Dry Electrical Discharge Machining

The powder-mixed near dry electrical discharge machining (EDM) technology is presented; its dielectric medium is gas-liquid-solid three phase mixtures. Experiment result shows that the material removal rate (MRR) and surface roughness increases with the increase of pulse duration, peak current and layer thickness, while pulse interval has the opposite effect. Raising air pressure can increase MRR and improve surface quality. Electrode consumption decreases with the increase of pulse duration. When pulse duration is large, electrode consumption is near zero. Due to the presence of droplet and powder, dielectric strength of gas medium reduces, thus discharging gap increases, the eroded particles are easily removed, and the probability of short circuit and arc discharge is reduced, working stability is improved, thus MRR is improved. Due to discharge disperse effect of powder, electric erosion pit depth is reduced, thus surface roughness is reduced.