本研究針對車銑複合加工中心之中大型床面，提出一結構設計最佳化流程，以期讓工具機開發人員在產品研發初期即可導入，透過此最佳化設計流程搭配田口實驗分析方法，先訂定主要之品質目標，再依產品性質決定因子與適當之水準，之後使用有限元素分析軟體輸入各項邊界條件後執行分析，將分析完成之結果代回田口實驗分析方法求取S / N比及最佳化之因子水準組合，並使用最佳化之因子水準組合預測S / N值與品質特性結果，最後依據此最佳化之因子水準組合建立分析模型並執行分析，比較最佳化組合之分析結果與田口實驗方法預測之品質特性是否相一致。 本研究選擇床面上方軌道面與前方軌面之垂直方向變形量為品質目標，品質特性為使垂直方向變形量最小之望小特性。將田口實驗方法得到之最佳化因子水準組合與分析模擬結果比對後顯示，最佳化之組合為 A1B3C1D3，即肋間距365 mm、肋厚25 mm、正主軸台鎖固面70 mm與地腳數量為12時，與原始床面模型相比，可使床面之上軌道面垂直方向變形量減少16.49 %及18 %，床面前方軌道面之垂直方向變形量可減少16.59 %及58.62 %，正主軸台鎖固面之垂直方向變形量可減少55.33 %，在重量方面，最佳化因子水準組合之床面較原始設計之床面重量增加756.84 kg，約為11.52 %。 ;This study presents an optimal design process for the base in medium-to-large-size turn-mill machining centers. Such a computer-aided design process can be applied at the initial stage in development of a new turn-mill machining center. In this proposed design process, a Taguchi method is employed in combination with a finite element analysis (FEA) technique. The Taguchi method is applied to determining the quality characteristic of the product, the control factors, and the control factor levels for a turn-mill machining center. The FEA technique is applied to calculating the stress and deformation of the developing turn-mill center under various combinations of design parameters, as planned by the Taguchi method. According to the “Smaller-the-Better” quality characteristic in the Taguchi method, the minimum deformation of the base in the vertical direction (Y axis) is selected to be the objective function to be optimized. Analysis results indicate the optimal combination of the control factors is determined to be a rib spacing of 365 mm, a rib thickness of 25 mm, a spindle fixture width of 70 mm, and 12 bottom supports. Compared to the original design, the optimized design can reduce the Y-axis deformation about 16.49% and 18% on the upper guide-way, about 16.59% and 58.62% on the front guide-way, and about 55.33% in the main spindle fixture. The weight of the base in the optimal design slightly increases by 756.84 kg, which is about 11.52% of the original one.
