提高纯钨微小孔电火花加工深径比的方法

A Method to Improve High Aspect Ratio of Micro Hole Machined by EDM

在航空、航天等一些尖端行业的核心零件中,微小孔的应用日趋广泛。电火花加工技术是微小孔加工的主要工艺之一,但对于大深径比微孔加工,现有的电火花加工工艺能力仍无法满足加工需求。针对纯钨材料微小孔电火花加工中的深径比难以提升的问题,分析了电蚀产物在孔底累积对放电过程造成的不利影响,找到了制约微孔电火花加工深径比提升的关键因素,即需有效排出孔底电蚀产物,确保放电过程处于“干净”环境。在此基础上,提出了在电火花加工中引入电化学作用,利用电化学作用产生的气泡驱动电蚀产物排出,确保大深径比孔底放电过程不受电蚀产物积聚的影响进而提高加工深径比的方法。通过实验对该方法的可行性和加工特征进行了验证,获得了直径约为0.2mm,深度48mm的加工结果。

In the core parts of aviation,aerospace and other advanced industries,the application of micro holes is becoming increasingly widespread.Electrical discharge machining(EDM)is one of the main processes of micro holes machining.However,the existing EDM process capability can not meet the requirement of machining micro hole with high aspect ratio.In order to improve the high aspect ratio of micro hole machined by electrical discharge machining on pure tungsten,the adverse influence on the electrical erosion caused by debris accumulation in the bottom of the hole was analyzed.The key factors that constraint the machining of deep micro holes was found.Based on this,a new method to improve the high aspect ratio of micro hole was proposed.The bubbles produced by electrochemical action was utilized to drive the debris out of electrode gap in EDM,which avoiding the adverse influence of debris accumulation on deep micro holes machining.The experiments shows that the method is feasibility to improve the high aspect ratio of micro holes,and micro hole with diameter 0.2mm and depth 48mm are machined on pure tungsten.