整合電腦輔助分析與數控銑床應用於金屬板材單點增量成形之研究

The Study of the Integrating of CAE and CNC Milling Machine for the Single Point Incremental Forming of Sheet Metal

倪永寬(Yung-Kuan Ni)

指導教授 ： 李經綸

淡江大學/工學院/機械與機電工程學系博士班/博士(2020年)

https://doi.org/10.6846/TKU.2020.00799

摘要

本文將電腦輔助製造軟體所轉出之刀具路徑資料，再與電腦輔助分析前處理軟體之工具設定與料片邊界條件做結合。採用動顯函有限元素法進行單點增量成形數值分析，以瞭解工件在成形歷程中所發生的厚度分佈、應力與應變分佈，及成形負荷變化。並設計一組含拉伸扣緣之圓柱形壓料板與夾具，經由數控銑床進行單點增量成形實驗，用以驗證本文有限元素數值分析程式之可靠性。
經由數值模擬與實驗結果比較得知，當設定不同工具轉速與工件進給速率進行45度圓錐杯成形時，於工具轉軸靜止，且工件進給速率為800 mm/min時，成形效果最佳。當工件進給速率遞增時，於錐杯底部圓弧角處的厚度有明顯薄化現象。橢圓錐杯的長軸與短軸分別與拉伸扣緣之距離不同，導致長軸傾斜壁所得的厚度分佈優於短軸。若提高工件進給速率，將可改善短軸傾斜壁之厚度分佈。當圓錐杯與橢圓錐杯隨著傾斜角增加，將導致板材厚度引薄，並使等效應力、等效應變，及成形負荷隨之遞增。成形後工件的最佳表面粗糙度分別為0.30 μm與0.34 μm，隨著傾斜角與加工深度增加，成形工件之表面粗糙度值就愈大。
本文採用的加工條件分別為螺旋線漸進式刀具路徑、工具轉軸靜止、提高工件進給速率，與注入冷卻潤滑液等，可提升圓錐杯與橢圓錐杯之成形性，並顯著改善工件之表面粗糙度，而數值分析結果皆可合理的模擬實驗結果，故本文之電腦輔助分析程式，皆可合理的預測單點增量成形製程。

關鍵字

刀具路徑 ； 動顯函有限元素法 ； 單點增量成形 ； 表面粗糙度

並列摘要

In this study, the toolpath data exported from a computer aided manufacturing software are combined with the tool settings and material sheet boundary conditions of a computer aided analysis pre-processing software. A dynamic explicit finite element method is adopted for numerical analysis of single point incremental forming to predict the thickness distribution, stress and strain distribution, and changes in forming load during the forming process of workpieces. A set of cylindrical blankholder and binder with drawbead is designed, and a single point incremental forming experiment is conducted using a CNC milling machine to verify the reliability of the finite element numerical analysis program adopted in this study.
By comparing the results from numerical simulation and experiments, it is evident that when different tool spindle speeds and workpiece feed rates are set to 45˚ circular cone cup forming, the forming effect is optimal if the tool spindle is stationary and workpiece feed rate is 800 mm/min. When the feed rate of the workpiece increases, the thickness at the arc corner at the bottom of the circular cone cup is significantly decreased. The distances from the long axis and short axis of the elliptical cone cup to the draw beads are different. Thus, the thickness distribution of inclined wall along the long axis is better than that along the short axis. If the workpiece feeding rate is increased, then the thickness distribution of the inclined wall along the short axis can be improved. As the inclination angles of the circular cone cup and elliptical cone cup increase, the thickness of the sheet material and the equivalent stress, equivalent strain, and forming load simultaneously increase. The optimal surface roughness of the formed workpieces is 0.30 μm and 0.34 μm. As the inclination angle and processing depth increase, the surface roughness of the formed workpieces increases.
The processing conditions adopted in this study involve spiral progressive tool path, stationary tool spindle, increasing workpiece feed rate, and injecting cooling lubricant. These processing conditions can improve the formability of a circular cone cup and elliptical cone cup and significantly improve the surface roughness of workpieces. The numerical analysis results can reasonably simulate the experiment results. Therefore, the computer aided analysis program adopted in this study can reasonably predict single point incremental forming processes.

並列關鍵字

Tool Path ； Dynamic Explicit Finite Element Method ； Single Point Incremental Forming ； Surface Roughness

參考文獻

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