极间介质模式对放电诱导烧蚀铣削影响

Effects of different gap dielectric mode on EDM ablation milling

为探究一种更有利于提高放电诱导烧蚀铣削工艺指标的极间介质模式,设计了内喷雾、液中喷雾、液中喷气这3种极间介质模式的对比试验,对材料去除率、相对电极损耗率、表面粗糙度等指标进行了对比。试验发现,液中喷气模式的材料去除率最高,达到131.86mm^(3)/min,相比于内喷雾、液中喷雾分别提高了7.10%、27.42%;相对电极损耗率最低,为1.81%,相比于内喷雾、液中喷雾降低了72.11%、74.64%;其氧气利用率同样是三者中最高的,达0.81%,相比于内喷雾、液中喷雾提高了44.64%、65.31%。分析表明,液中喷气放电诱导烧蚀铣削加工是在气液分层介质中击穿放电,其排屑状态优于内喷雾和液中喷雾,因此短路拉弧现象减少,电极损耗因而大幅降低,同时该模式具有聚集氧气的优势,有利于提高放电诱导烧蚀铣削加工的工艺指标。

Comparison experiments of near-dry EDM ablation milling,submerged mist-jetting mode and submerged gas-jetting mode are conducted to investigate an optimal gap dielectric mode which benefits improving the process index of EDM ablation milling.Material Removal Rate(MRR),Relative Electrode Wear Rate(REWR)and surface roughness are compared.The experimental results show that the submerged gas-jetting mode gets the highest MRR of 131.86 mm^(3)/min,increased by 7.10%and 27.42%compared to near-dry mode and submerged mist-jetting mode;this mode remains the lowest REWR of 1.81%,reducing by 72.11%and 74.64%compared to near-dry mode and submerged mist-jetting mode;the mode also achieved the largest oxygen utilization rate of 0.81%,increasing by 44.64%and 65.31%in comparison with near-dry mode and submerged mist-jetting mode.The analysis indicates submerged gas-jetting EDM ablation milling sparks in the gas-liquid stratified medium,which shows better debris removal capability than others,and therefore reduced short circuit;thus,REWR of submerged gas-jetting mode reduces sharply.The submerged gas-jetting mode also has the advantage of gathering oxygen,and consequently,is able to improve the performance of EDM ablation milling.