冰层辅助对电火花-电解复合穿孔的影响

电火花-电解复合穿孔(ECDD)加工方法有望实现难加工材料涡轮叶片气膜冷却孔无重铸层高效加工,为了进一步提升小孔孔壁的加工质量,提出了在工件底部填充冰层的电火花-电解复合穿孔加工新方法。分析了冰层辅助对复合加工过程中两极之间电流电压的波形、复合穿孔的加工效率、小孔的出入口孔径、孔壁重铸层去除等的影响,进行了冰层辅助与无冰层辅助电火花-电解复合穿孔对比试验。试验表明:冰层辅助加工可以在小孔穿透之后形成充分的反向冲液,有效地解决小孔穿透之后的漏液问题。在增加底部停顿时间的基础上,即小孔穿透后管电极到达预设深度继续停留一段时间,延长管电极对孔壁的电解作用时间,可以显著提高重铸层的去除效果,有望实现小孔整个孔壁重铸层的完全去除。

Effects of aided ice layer on electrochemical discharge drilling

The processing method of electrochemical discharge drilling (ECDD) is expected to achieve high efficiency machining of the difficult-to-machine material of film cooling holes without recast layer on turbine blade.In order to further improve the machining quality of hole walls,a new processing method of ECDD with ice layer filled at the bottom of the workpiece is proposed.The effects of ice layer on current and voltage waveform between tool electrode and workpiece electrode,machining efficiency,the diameter of the entrance and exit,and removal of recast layer on hole walls are analyzed.Contrast experiments between ECDD with aided ice layer and ECDD without aided ice layer are conducted.Experiment resuits show that the aided ice layer can help to form sufficient reverse flushing of working fluid and effectively solve the problem of working fluid leakage after penetration.After penetration of small holes,the tube electrode stays for a few seconds at the predetermined depth to increase the electrochemical dissolution time,so that the ECDD with aided ice layer can enhance the removal effect of recast layer,and is expected to achieve complete removal of entire recast layer of the wall of small holes.