利用電化學加工製作微電極和微孔之研究與分析; The Analysis and Investigation on the Micro-electrode and Micro-hole Fabrication by Electrochemical Machining

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題名:	利用電化學加工製作微電極和微孔之研究與分析;The Analysis and Investigation on the Micro-electrode and Micro-hole Fabrication by Electrochemical Machining
作者:	范智文;Zhi-wen Fan
貢獻者:	機械工程研究所
關鍵詞:	電雙層;微孔;脈衝電壓;微電化學加工;微電極;Electrochemical micromachining;Micro electrode
日期:	2010-05-04
上傳時間:	2010-12-08 13:41:57 (UTC+8)
出版者:	國立中央大學
摘要:	摘要在眾多傳統加工中，電化學微細加工(EMM)又稱微電解加工，屬於特種加工的一種。其優點是可以加工任何金屬材料，並不受其硬度與強度的影響;且刀具電極不損耗，工件表面不含殘留應力，加工重複性較放電加工高，但其缺點在於微加工精度不高故本文針對以電化學加工法製作微電極和孔加工精度進行探討。微電極在非傳統加工中應用層面廣，但微電極的製作多半是由線放電研磨和雷射加工所製作，其成本花費很高且製作效率低，加上二者皆是採熱加工容易殘留應力，故本研究利用電拋光方式分別探討在直流和脈衝電源供應器下，其加工參數對於微電極製作之外型和尺寸的影響並搭配旋轉系統增加質傳效應。經由實驗發現到低電壓、高電解液濃度、加上合適的轉速，可製作出小於100 μm之微電極，且發現到加工之微電極轉速對於電極外型有很大的影響性。在搭配脈衝電源供應下製作微電極其以線性遞減操作電壓和加工能率的方式，可成功的製作出刃長為2 mm、3 mm、4 mm，電極直徑為100 μm的圓柱狀微電極，也利用此微電極進行深孔加工。在微電化學深孔加工中因為電極細小，不易使用中空管刀具進行排屑，故本研究採用旋轉刀具，改善電解液流動問題，且配合脈衝式直流電源，提供有規律的間歇供電進行間歇加工，以改善成品精度和增加孔深寬比。經由實驗可發現，在刀具轉速越高其加工深度可越深但高於某一轉速後其影響性降低，在使用50 μm的陰極刀具，且配合1000 RPM下其加工深度可達1000 μm(深寬比約1 : 9)，過切量為33.35 μm。而在極短脈衝電化學加工經由實驗發現脈衝頻率和過切關係不為線性以及氫氣泡對於加工的影響很高，在單一脈衝放電時間為30 ns下其可製作出深度為300 μm，孔過切量為13.75 μm的微孔。 In numerous micromachining, electrochemical micro-machining (EMM) also called the electrolytic micro-machining that belong to the non conventional machining. It has more advantages such as any metal material regardless of its hardness can be machined, the cathode tool would not break in the machining process, the work piece after machining will not have any residual stress remained on its surface, the machining reproducibility was high than electro discharge machining. Due to the EMM that disadvantage was the low machining precision. In this paper we discussion the working parameters of EMM that how to effect the machining precision on the manufacture the micro-electrode and hole drilling. The mircro-electrode has high potential application in non-conventional machining, because the micro-electrode is very thin, generally they are fabricated by micro-electro discharge and laser machining. However, the corresponding equipments are very expensive and their machining efficient is very low. In this reseaech, we applied in the form of electrochemical polish to manufacture the micro-electrode. Under using the DC and pulsed voltage power supply we disscuss the working parameters that how to efeect the micro-electrode’s size and form. For increasing the mass diffusion effect, it added the rotational system in the experimet. Experimental results show that low applied voltage, high concentration electrolyte and an appropriate rotation of electrode are preferred to fabricate micro electrodes with diameter less than 100 μm. From the experiment, it found the rotational speed had critical affect in the form of micro-electrode. When processing the microelectrode by the pulsed voltage power supply, it could fabricate the 100 μm cylindrical tungsten microelectrode and length of 2 mm, 3 mm and 4 mm by linear decay of applied voltage or duty at different length, and we used the micro-electrode to process the electrochemical micro drilling. In the electrochemical machining of deep holes, especially for small holes, driving out the sludge is always difficult. The hollow tool electrode or lateral flow of the electrolyte cannot be applied to improve the machining precision anymore. In this paper, a rotational tool electrode and a high-frequency pulsed generator were applied herein to drive out the sludge, increase the machining precision and achieve the high aspect ratio hole. By the experiment, a high quality micro hole with a 33.35 μm overcut is drilled by a WC pin of diameter 50 μm on a 304 stainless steel plate of thickness 1000 μm(The hole aspect ratio reaches around 1 : 9.).It shows that a rotational tool can be utilized in the deep hole, electrochemical micro-drilling. In the electrochemical micro drilling with ultral short pulse voltage, by the experiment, it found the relationship between pulsed frequency and overcut was not linear and an excess amount of hydrogen gas bubbles would hinder hole machining, and reduce machining efficiency and precision. Under 30 ns pulsed on-time, a high-quality micro hole with a 13.75 μm overcut is drilled on a nickel plate of 300 μm thick.
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