近年來,隨著製造技術的加工水準日漸升高,所設計的產品造型多為複雜曲面。故本研究探討五軸加工機銑削NAK80模具鋼複雜曲面的最佳化切削參數,以提升工件表面品質與精度,以減少在研磨、拋光等後續處理上的加工成本及時間。 本次研究之實驗機台為實驗室之床台傾斜旋轉型態之五軸加工機,實驗對象為NAK80模具鋼材料半球形曲面之複雜輪廓,研究步驟為CAD/CAM軟體Unigraphcis進行路徑規劃,使用不同的刀具路徑以多軸同動方式進行切削加工程序,實驗的因子有主軸轉速、進給速度、刀具路徑規劃和刀具步進數等四個相關因子,同時每因子都設定為三個水準,量測各個工件切削後表面粗糙度,並使用田口法以求得最佳加工參數組合。本研究的品質特性為望小特性,亦即取得較小的表面粗糙度值為佳。實驗結果顯示利用12,000rpm的主軸轉速、600mm/min的進給速度、跟隨周邊的路徑規劃與600刀具步進數可以達到較佳的表面粗糙度,表面粗糙度為0.2361μm。同時也利用ANOVA分析表驗證了與田口法的實驗結果是一致的,分析結果以路徑規劃貢獻度最大,有82.99%的影響力。
Many designers of industrial products tend to design product featured with complex surface. In order to improve the surface quality and accuracy of work piece and thus reduce time, cost, and error in further bench working, we design an experiment to optimize the cutting parameters for minimizing the roughness of a complex surface machined on NAK80. The table rotating-tilting type five-axis machine is used to perform the experimental cutting in this study. Unigraphcis CAD/CAM software is used to plan the tool path for milling process. The four parameters studied are spindle speed, feed rate, tool paths, and stepover, and each of these factors has three levels. Use the Taguchi method to find the optimal machining parameters. The target of this study is the feature of lower-the-better that is minimization of the surface roughness. The final results of this study showed that the optimal parameters are 12,000 rpm spindle speed, 600 mm/min feed rate, follow periphery, and 600 stepover, and the best surface roughness produced are 0.2361μm. The results of ANOVA analysis is correspondent with this result. The factor contributed most to the surface roughness is tool path and is 82.99%.