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氧气在电火花(EDM)诱导烧蚀加工过程中起到参与氧化放热、蚀除金属和冷却的作用。以气体压力为研究对象,通过理论推导,证明增加气体压力可提高气体流速、减小气体分子平均自由程、提高氧化扩散速度和气体蚀除力以及加速能量散失。通过测得不同气体压力下的击穿电压、击穿延时和工作电压,试验证实了气体压力对击穿电压和击穿延时有较大影响;通过建立EDM诱导烧蚀加工放电等效模型,表明工作电压变化是由电极和工件表面氧化引起的。研究了气体压力对EDM诱导烧蚀加工材料蚀除率(MRR)、相对电极损耗(REWR)和表面粗糙度的影响。结果表明:随着气体压力增大,材料蚀除率先增加后降低,电极相对损耗缓慢减小,表面粗糙度显著降低。
Oxygen plays a role in oxidation, exotherm, metal removal and cooling in EDM induced ablation processes. Taking the gas pressure as the research object, the theoretical derivation shows that increasing the gas pressure can increase the gas flow rate, decrease the mean free path of the gas molecules, increase the oxidation diffusion rate and the gas erosion force, and accelerate the energy dissipation. By measuring the breakdown voltage, breakdown delay and operating voltage under different gas pressures, the experiment confirmed that the gas pressure has a great influence on the breakdown voltage and the breakdown delay. By establishing the EDM-induced ablation process discharge equivalent model , Indicating that the change of working voltage is caused by the oxidation of the electrode and the workpiece surface. The effects of gas pressure on the material removal rate (MRR), relative electrode loss (REWR) and surface roughness of EDM-induced ablation material were investigated. The results show that with the increase of gas pressure, the material erosion rate firstly increases and then decreases, while the relative loss of electrode decreases slowly, and the surface roughness decreases significantly.