液態電漿拋光 6000系列鋁合金參數最佳化設計

Optimum Design of Parameters for Plasma Electrolytic Polishing 6000 Series Aluminum Alloy

黃鈺軒(Huang Yu-Shuan)

指導教授 ： 陳晧隆

國立屏東科技大學/工學院/機械工程系所/碩士(2021年)

https://doi.org/10.6346/NPUST202100427

摘要

6000系列鋁合金具備質輕、易加工、耐蝕性與抗氧化性佳等優點，已經廣泛被應用於機械、電機及電子產業製作機台框架或精密元件，由於應用性廣泛對此材料表面性質的要求也較高。鋁合金表面處理方法很多，隨環境保護條件升高，表面處理方法也必須符合環保條件。本研究使用液態電漿拋光方法，採用較環保的電解液，並搭配田口穩健設計L9(34)直交表及實驗分三階段進行，尋找最佳化參數組合。
第一階段實驗以L9(34)直交表探索三種電解液於三種控制因子中找出最佳的拋光電解液。控制因子為直流電壓、拋光時間、電解液莫耳濃度、電解液種類。處理後碳酸氫鈉與檸檬酸電解液的表面粗糙度降低，在草酸電解液中，為了達到設定電壓，需要更大的電流，在電壓與電流都很大的情況並不屬於拋光，結果表面粗糙度值變大。
第二階段實驗中，保留第一階段實驗的碳酸氫鈉與檸檬酸電解液將會產生較大電流的草酸替換成冰醋酸，並且把貢獻度最小的拋光時間替換成電解液溫度，實驗在低溫、常溫與高溫環境中電解液對拋光的影響。控制因子為直流電壓、電解液莫耳濃度、電解液種類、電解液的溫度。結果顯示冰醋酸跟草酸一樣伴隨著較大電流造成侵蝕現象，表面粗糙度值變大，而在碳酸氫鈉與檸檬酸電解液的工件表面粗糙度降低。
第三階段實驗中，前二階段結果顯示電流會造成表面粗糙度增加，選用不會有電流產生的檸檬酸當作電解液，控制因子為直流電壓、拋光時間、電解液莫耳濃度、電解液的溫度。結果顯示NO 8，參數組合A3 B2 C1 D3之表面粗糙度改善率為17.42 %，A因子(直流電壓)之貢獻度68.83 %為最大，其後為C因子(電解液莫耳濃度)19.54 %、B因子(拋光時間)11.47 %、最後D因子(電解液溫度)貢獻度最小。經優化後參數組合A3 B2 C2 D1之表面粗糙度改善率為23.86 %與原直交表最佳組別相比，增加27 %。

關鍵字

液態電漿拋光 ； 鋁合金 6000系列 ； 表面粗糙度 ； 田口穩健製程設計法

並列摘要

The aluminum alloy 6000 series have been widely used in machinery, electrical and electronic industries to make machine frames or precision components, that there are advantages light weight, easy processing, good corrosion resistivity and resistance to oxidation. Due to its wide range of applications, the requirement of surface property on this material is strict. There are many ways of surface treatment methods for aluminum alloys. As environmental protection conditions increase, the surface treatment methods must also comply with environmental protection conditions.
This research uses a plasma electrolytic polishing method, apply a more environmentally friendly electrolyte, and uses Taguchi's robust design of the L9 (34) orthogonal table. The experiment is carried out in three stages to find the optimization parameter combination.
In the first stage of the experiment, the L9 (34) orthogonal table was used to explore the three different electrolytes and find the best polishing electrolyte among the three control factors. The control factors are DC voltage, polishing time, electrolyte concentration, and electrolytic solution type. After treatment of sodium hydrogen carbonate and citric acid electrolyte solution, surface roughness is reduced. In oxalic acid electrolyte solution, to achieve the set voltage, a larger current is required. When the voltage and current are both large, it does not in the scope of polishing, and the surface roughness becomes larger.
In the second stage of the experiment, the sodium hydrogen carbonate and citric acid electrolyte were still be used. Oxalic acid solution was be replace to glacial acetic acid that owing to it easy generates a larger current. The polishing time was be replace to electrolyte temperature. To experiment at low temperature, room temperature and high temperature environment and observe influence of electrolyte on polishing. The control factors are the DC voltage, electrolyte concentration, the type of electrolyte, and the temperature of the electrolyte. The results show that glacial acetic acid and oxalic acid with larger current will cause erosion, and the surface roughness value becomes larger, while the surface roughness of the component with sodium bicarbonate and citric acid electrolyte reduce.
In the third stage of the experiment, above the results of two stages shown that current will increase the surface roughness. The citric acid solution does not generate current in plasma electrolytic polishing process, so it was used as main electrolyte. The control factors are DC voltage, polishing time, electrolyte concentration, and electrolyte temperature. The results shown that NO 8, the parameter combination A3 B2 C1 D3 has a surface roughness improvement 17.42%, the A factor (DC voltage) contribution rate of 68.83% is the largest, followed by the C factor (electrolytic solution concentration) 19.54%, The B factor (polishing time) is 11.47%, and the final D factor (electrolyte temperature) contributes the least. After combination of parameters optimized A3 B2 C2 D1 the surface roughness improvement rate is 23.86%, with the best group of the original orthogonal table increase of 27%.

並列關鍵字

Plasma Electrolytic Polishing ； Aluminum Alloy 6000 Series ； Surface Roughness ； Taguchi Method

參考文獻

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