黃銅線及鍍鋅線應用於線切割之性能研究

線切割加工能使用的線電極種類繁多，但線電極對加工性能的影響過去未見討論。本研究欲探討線電極對加工特性之影響，以提供未來線電極設計之參考。文中使用鍍鋅線與黃銅線，進行不同加工道次切割數種厚度的SKD-11材料。結果顯示鍍鋅線不僅在面切割速度上優於黃銅線，在工件上也呈現更好的形狀精度以及更優異的表面粗糙度。導致此差異的原因可歸納為三大基本因素，分別為熱、電與汽化的性質。研究中針對鍍鋅線與黃銅線在熱、電與汽化相關等特性設計實驗，整合實驗結果可發現使用鍍鋅線做為線電極材料，其表面的多孔結構可增加線電極與加工液接觸的面積，協助熱量的排除，並因為鍍鋅線有較低的熔點與沸點，因此較容易發生汽化帶走熱量，而具有較佳的熱量排除機制；另外由於鍍鋅線有較低的電子親合能，在放電加工過程中會產生較大的放電間隙，配合上鍍鋅線的低沸點與高飽和蒸氣壓，於加工中產生大量氣體，使放電渣較容易排除，而達到較佳的清洗性。最後本研究歸納了各種在放電加工上影響線電極效果之因素，建議如欲改善黃銅線之加工效能，可將黃銅線的表面改成多孔結構，以協助熱量排除；如欲發展新線種，可設計多層不同材質的線電極，例如最內層選用鉬或鎢等高剛性、高熔點材料，中間層則選用導電性良好的黃銅或純銅，最外層則鍍上一層鋅，此種新型電極應可滿足線電極的所有需求。預期有極佳的剛性、優異的導電率、優良的熱量排除機制以及良好的清洗性。

關鍵字

線切割放電；黃銅線；鍍鋅線

並列摘要

Many kinds of wire electrodes were used on wire electric discharge machining (WEDM), but the research of the wire electrode has few been discussed. In this study, the impact of wire electrode will be discussed, in order to be the reference of design the wire electrode in the future. In the article, brass wire and zinc-coated brass wire were used as electrodes in WEDM. Experiments were conducted with different workpiece thicknesses and different cutting processes. And material SKD-11 was used as the workpiece. According to the experimental result, zinc-coated brass wire is not only good at machining speed but also can form good shape accuracy and good surface roughness. It could be concluded that the three basic elements like heat, electric and evaporation were the main factors. This study focused on these three basic physical properties of zinc-coated brass wire and brass wire, and also designed and conducted the experiments with the characteristics of heat, electric and evaporation. It is discovered that there are some micro holes on the surface of zinc-coated brass wire while it is used as an electrode. Hence, the contact area between the fluid and the wire electrode will increase and that will lead to a better heat removal, being easy to evaporate and a better cooling mechanism because of the lower melting point and boiling point of zinc-coated brass wire. Moreover, the lower electron affinity of zinc-coated brass wire would lead to the larger gap distance during WEDM process. And with the characteristics of lower boiling point and induced higher saturated vapor pressure, zinc-coated brass wire can produce much more vapor resulting that the discharge debris could be easily eliminated to achieve the better flush-ability. At last, this study has figured out all the factors which can influence the efficiency of wire electrode and machine efficiency. A design with multi layers of electrode composed of different materials like the most inner layer with molybdenum or tungsten material with high boiling point and stiffness, the median layer with brass or copper which is good at conductivity and the outer layer with zinc-coated was proposed as an innovative electrode design. Multi-layer wire electrode would be the optimum choice to obtain a good stiffness, conductivity, heat removal rate and debris eliminating.

並列關鍵字

WEDM ； brass wire ； zinc-coated brass wire

參考文獻

[16] 伍國瑋, “線切割放電加工機放電延遲時間之序列分析,” 台灣大學機械工程學研究所碩士論文, 2009年.

[4] T. Tani, Y. Fukuzawa, N. Mohri, N. Satio and M. Okada, “Machining phenomena in WEDM of insulating ceramics,” Journal of Materials Processing Technology, Vol. 149, 2004, pp. 124-128.

[5] K. T. Chiang and F. P. Chang, “Optimization of the WEDM process of particle-reinforced material with multiple performance characteristics using grey relational analysis,” Journal of Materials Processing Technology, Vol. 180, 2006, pp. 96-101.

[6] A.B. Puri and B. Bhattacharyya, “An analysis and optimization of the geometrical inaccuracy due to wire lag phenomenon,” International Journal of Machine Tools and Manufacture, Vol. 43, 2003, pp. 151-159.

[7] O. Dodun, L. Slâtineanu, G. Nagît and A. M. Goncalves-Coelho, “Using wire electrical discharge machining for improved corner cutting accuracy of thin parts,” International Journal of Advanced Manufacturing Technology, Vol. 41, 2003, pp. 858-864.

國際替代計量

黃銅線及鍍鋅線應用於線切割之性能研究

全文下載

主題瀏覽