微振動輔助主動式氣膜電化學放電鑽孔加工之研究

電化學放電加工常用於對玻璃、陶瓷這類非導體硬脆材料進行加工，但是電化學放電鑽孔加工法仍然有許多需要克服的地方，例如鑽孔深度、加工速度、擴孔現象、孔錐度等等。主動式氣膜電化學放電鑽孔加工為使用中空管狀電極，鑽孔加工時在中空管內施打空氣。結果顯示，由於施打的空氣氣泡向上漂浮，改變電極側面局部絕緣層厚度，而無法產生較穩定的絕緣氣膜，降低電極側面放電火花發生的機率，故能獲得較小的擴孔量與較佳的孔錐度。但因電極側面放電不均勻的關係，使得孔壁粗糙度不佳。本文的研究目的在於改善主動式氣膜電化學放電鑽孔加工，主要是在施打空氣的中空管狀電極加上微振動，且於電極側壁使用線切割放電加工機加工出多道環狀溝槽，並觀察微振動與電極側面的溝槽對電化學放電鑽孔加工所造成的影響。實驗結果顯示，由於電極的振動擾動了電極側壁的絕緣層，使得絕緣層變的不穩定，因而減少了電極側壁的放電機率；而振動與電極側壁的環狀溝槽搭配之下，能將電極側壁與孔壁之間中空管狀電極所施打的空氣氣泡撞擊而分解為較小氣泡，使其難以結合為絕緣氣膜，因此電極側壁放電的機率變的更低，故能得到更小的擴孔率與更佳的孔錐度，並且由於振動能將電極與孔壁間的氣泡平均分散，改善電極側壁放電不均勻的現象，因此能改善孔壁表面粗糙度不佳的問題。

關鍵字

電化學放電加工；鑽孔；擴孔現象；孔錐度；微振動；孔壁粗糙度

並列摘要

Electrochemical discharge machining (ECDM) is widely used to machine the non-conductive brittle materials such as glasses and ceramics. However a lot of significant problems are still remained unsolved, eg., the machining depth, the machining rate, the enlarging hole condition and the tapering hole phenomenon etc. Self-acting gas film electrochemical discharge drilling process injected air through a hollow tube electrode during the drilling process to reduce the enlarging and tapering hole phenomenon. But the experimental results showed that the surface roughness of the workpiece was worse comparing to that machined without the air injecting process because the local thickness of the gas film around the electrode became unstable and there was only few sparks taking place non-uniformly around the tube electrode. Hence, the purpose of this study is to improve the self-acting gas film electrochemical discharge drilling process with a micro vibration assisted on the hollow tube electrode which has been already repaired with several grooves on its side by wire electrical discharge machining (WEDM) while injecting air. This study also figured out the effect of the micro vibration assisted and the produced groove. Experimental results showed that the thickness of the gas film around the electrode became unstable because of the micro vibration, so that the chance of sparks which can take place around the electrode is reduced, ie., the bubbles from the air injected turned into the smaller bubbles and then this condition is hard to integrate into gas film. As a result, this developed process can improve the enlarging hole condition and the tapering hole phenomenon. In addition, because of the micro vibration, the bubbles can disperse averagely between the electrode and the hole. Thus the problem of the worse surface roughness of the performed hole also could be improved.

並列關鍵字

ECDM ； oversize ； taping angle ； surface roughness ； micro vibration

參考文獻

12.吳倫靜，電化學放電鑽孔加工品質提升之研究，碩士論文，國立台灣大學機械工程學研究所，民國九十五年七月

14.莊博淵，主動式氣膜輔助電化學放電鑽孔加工之研究，碩士論文，國立台灣大學機械工程學研究所，民國九十六年七月

16.彭文陽，電化學放電現象與製程應用之研究，博士論文，國立台灣大學機械工程學研究所，民國九十四年九月

1.H. Kurafuji and K. Suda, “Electrical discharge drilling of glass,” Annals of the CIRP, Vol. 16, 1968, pp.415-419

2.Y. Liu, Z. Jia and J. Liu, “Study on hole machining of non-conducting ceramics by gas-filled electrodischarge and electrochemical compound machining,” Journal of Materials Processing Technology, Vol. 69, 1996, pp.198-202

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微振動輔助主動式氣膜電化學放電鑽孔加工之研究

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