| 摘要: | 電化學加工（Electrochemical Machining，ECM），屬於非傳統加工方法的一種，以電解現象達成加工成形之目的，其優點為加工不受材料硬度與強度限制、工件無表面應力殘留，加工速度快且刀具無耗損，具有相當高的發展潛力與附加價值。
本研究目的為採用PCB板，結合刀具及遮罩進行遮罩式電化學雙面加工，用不銹鋼304板(0.5mm)作為工件。以灰色關聯分析探討實驗參數(電解液濃度、操作電壓、遮罩孔洞直徑、電解液流速)對加工品質之影響度，並找出加工範圍內之最佳參數組合，其優點還可以同時進行多重特性評估，有別於田口分析只能望一品質。並分析6×6陣列孔洞其孔洞錐度分布。
實驗結果發現，對於加工成品之特性影響較大的實驗參數為電解液流速與電解液濃度，而實驗之最佳參數組合(A_1 B_3 C_2 D_3)為電解液濃度10wt%、操作電壓22V、遮罩孔徑直徑0.6mm、電解液流速3.74m/s。加工結果如下:平均過切為0.263mm、平均圓度誤差為0.03mm、平均錐度為37.85º與初始條件相比，其灰色關聯度從0.6提升到0.79。孔洞分布中，以橫向排列分布呈現靠近電極端錐度較小、過切量較大，形成波浪狀，得知此區域加工速率較為中間孔洞快速，原因於電極棒兩端放熱及流場邊界層影響，造成兩端電解液溫度較高，電導率上升，加工速率增快。以縱向排列分布時，下游端過切量較大、錐度較小，判斷出下游端加工速率較上游端加工速率快，原因為電解液流動帶離上游的焦耳熱到下游端，與下游流速較慢於上游，造成電解液溫度上升和電導率上升，使加工速率增快。
;Electrochemical machining (ECM), which is one of the non-traditional manufacturing processes, shapes workpieces by electrolysis. The advantages of ECM include not being affected by the hardness and strength of the material, no surface residual stress, fast processing speed, and no consumption of the tool. It is considered the enormous potentialities and highly added values.
The purpose of this study is to use a PCB board, combined with a tool and a mask, to process through-mask double-side electrochemical machining. Stainless steel 304 plate (0.5mm) is used as the workpiece. Grey relational analysis(GRA) is used to investigate the effect of experimental parameters, such as electrolyte concentration, applied voltage, diameter of the mask hole, and electrolyte flow rate, on the machining quality, and estimate the best combination of parameters. Compared with Taguchi method, GRA could have multi-objective optimization, while Taguchi has only single-objective optimization. Furtherance analysis of the distribution of taper angle and overcut on 6×6 array holes is also performed.
Through the experimental results, it can be found that the most important factors for the characteristics of finished product are electrolyte flow rate and electrolyte concentration. The best parameter combination is A_1 B_3 C_2 D_3 (electrolyte concentration 10wt%, applied voltage 22V, diameter of the mask hole 0.6mm, and electrolyte flow rate 3.74m/s.) The processing results were as follows: the average overcut was 0.263 mm, the average roundness error was 0.03mm and the average taper angle was 37.85 º. Compared with the original working condition(A_1 B_1 C_1 D_1 ), the GRA is increased from 0.6 to 0.79. In the distribution of the holes, the taper angle distribution in the horizontal arrangement shows that the taper angle is smaller near the electrode rod. In the overcut distribution, the overcut is larger near the electrode end. I will know the machining rate is faster than the part of middle. A wavy distribution on the overcut and taper angle are formed. Because the heat is from both ends of the electrode rods and the boundary layer effect, it cause the electrolyte temperature at both ends to be higher, the conductivity to rise, and the machining rate to increase. When the taper distribution and the overcut distribution are vertical arrangement, the downstream has a large overcut and a small taper. I determine that the downstream machining rate is faster than the upstream. Because the Joule heat accumulate on the downstream by the electrolyte flow from upstream. And the flow rate on the downstream is slower than the upstream. It cause the electrolyte temperature and the conductivity to rise. The machining rate increases. |
