臺灣博碩士論文加值系統

近年板金的生產趨向於客製化及少量生產，且由設計到製造的週期縮短。傳統沖壓在模具的開發上需耗費大量的資金與時間，因此市場開始尋求更靈活的工藝。增量成形不需要模具，並具有高度的自由度，使用CNC設備或機械手臂皆能進行成形，在客製化方面有高度的競爭力。但最大成形角度卻限制了增量成形的應用，因此突破最大成形角度成為最重要的研究項目之一。而在眾多研究成果中，多階段單點增量成形能有效地提升板材厚度並突破最大成形角度，然而多階段單點增量成形存在著板厚分布不均的問題，仍有造成板材破裂的疑慮。因此本研究探討其變形機制並提出控制厚度分配的策略。
本研究使用有限元素分析軟體Abaqus模擬軸對稱圓錐造型之多階段單點增量成形過程，由模擬結果中發現，多階段成形中材料的應變與位移量有關。藉由此關係能具體的說明多階段成形中板材厚度分布的狀態，且能透過位移量推算出板材厚度。
傳統多階段單點增量成形之第一階段輪廓皆使用等角度直線輪廓，本研究則使用Bezier curve建立曲線輪廓。曲線輪廓之成形角度會隨位置而改變，因此厚度也會隨著改變，藉由控制第一階段的厚度分布，達到調整最終厚度之目的。而在建立曲線輪廓時也根據應變與位移量的關係定義曲線的參數，使最終厚度得以增加且分布更平均。本研究將上述策略應用於成形垂直圓杯，與傳統方法相比，不論是厚度或是成形性皆有顯著的提升。

In recent years, sheet metals tend to be customized and produced in small quantities. Traditional stamping requires a lot of cost and time in the production of dies. Incremental forming is highly competitive in customization because it does not require dies. However, the maximum draw angle limits the application of incremental forming. Multi-stage single-point incremental forming can effectively increase the formability of the sheet, i.e., the limitation of maximum forming angle. Nevertheless, tool paths in multi-stage single-point incremental forming are simple. Therefore the thickness distribution is not homogeneous, leading to possible material failure. This research investigated the deformation mechanism of multi-stage single-point incremental forming and proposed a strategy to optimize the thickness distribution with Bezier curves.
In this research, finite element analysis was used to simulate the forming process of axisymmetric cone in multi-stage single-point incremental forming. In the traditional multi-stage single-point incremental forming, the first-stage profile is equal-angle linear profile. In this research, the Bezier curve was used to establish the curve profile. The curved profile are designed according to simulation results. By adjusting the thickness distribution in the first stage, the purpose of adjusting the final thickness distribution was achieved. The parameters of the curve profile were defined according to the relationship between strain and displacement, so that the thickness distribution was more homogeneous. This research applied the above strategy to form vertical round cups, which had a significant improvement in both thickness and formability compared to conventional methods.

口試委員會審定書 i
誌謝 ii
摘要 iii
Abstract iv
目錄 v
圖目錄 viii
表目錄 xii
第一章 緒論 1
1.1 前言 1
1.2 研究動機與目的 3
1.3 文獻回顧 5
1.4 研究方法與步驟 9
1.5 論文總覽 10
第二章 增量成形機制探討 11
2.1 單點增量成形機制探討 11
2.1.1 垂直進給量與工具尺寸 11
2.1.2 單點增量成形厚度分布 13
2.1.3 單點增量成形的成形性 15
2.1.4 Membrane analysis 18
2.2 多階段單點增量成形機制探討 21
2.2.1 多階段單點增量成形相關策略 21
2.2.2 多階段單點增量成形之應變 24
第三章 實驗與模擬模型建立 27
3.1 實驗架設 27
3.1.1 單點增量成形夾具 27
3.1.2 實驗設備及儀器 30
3.1.3 成形工具 31
3.1.4 實驗用板材 32
3.1.5 工具路徑生成 33
3.1.6 實驗流程 34
3.2 材料模型建立 35
3.2.1 拉伸試驗 35
3.2.2 成形極限圖 38
3.3 有限元素分析模型建立 38
3.3.1 Abaqus/Explicit 39
3.3.2 模型建立 39
3.3.3 收斂性測試 41
3.3.4 模型驗證 46
第四章 多階段增量成形加工策略 48
4.1 多階段增量成形厚度變化 50
4.2 厚度分布改善方法 54
4.2.1 Bezier curve 54
4.2.2 建立第一階段輪廓 57
4.3 厚度分布改善結果 64
4.3.1 深度30mm圓杯 64
4.3.2 深度35mm圓杯 67
4.3.3 深度40mm圓杯 69
4.4 實驗結果 73
第五章 結論與未來展望 74
5.1 結論 74
5.2 未來展望 75
參考文獻 76

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