利用有限元素法模擬金屬薄板之深抽軸成形分析

The Simulation Analysis on Sheet Metal Deep Drawing Process by Finite Element Method

謝承佑(Cheng-Yu Hsieh)

指導教授 ： 許源泉

國立虎尾科技大學/工程學院/創意工程與精密科技研究所在職專班/碩士(2014年)

https://doi.org/10.6827/NFU.2014.00245

摘要

金屬薄板成形技術廣泛應用於汽車、鋼鐵、電器、船舶、航空航太、武器等各種產品中。本研究結合有限元素模擬軟體分析與沖壓模技術開發實體模具方式，探討薄板引伸成型技術可行性以及有效提高未來設計方式。引伸成形是薄板成形中極為重要的塑性加工方法，是製造業工藝中重要組成部分。薄板成形過程的數值模擬分析是一個很複雜的系統工程。傳統的板材成形方法，模具設計製造週期較為攏長，需要長時間的反覆試模驗證，導致技術無法延續長久也進而增加模具產品開發成本與週期。深抽模具成形方法目前於業界一般認知其開發不確定因素尚有許多，倘若僅能利用職場上老師傅經驗值而無法累積建立可數據化的資料庫，即無法有效掌握開發進度，如此便很難滿足應用於業界要求。

隨著電腦和電腦輔助技術不斷的發展突破，此項技術在金屬塑性成形的領域裡漸漸得到了廣泛的應用。本研究透過有限元素數值模擬軟體（PAM-STAMP）整合板金成形過程與有限元素電腦模擬技術以求解的模擬軟體。利用有限元素模擬技術對薄板成形問題進行研究，實現對起皺和拉裂等問題的預測與消除，甚至減少或取消試模，達成縮短產品開發週期、降低產品開發成本的目的。

本文利用有限元素模擬軟體(PAM-STAMP)對金屬薄板成形問題進行分析與研究。經研究結果顯示，在薄板材引伸方面，可利用過度抽拉、推擠材料及成形R角設定做為材料流動的介質，補償必須適宜，若過多可能造成材料流動太快，過少則會發生肉厚不均現象；在深抽材料推擠方面，影響尺寸精度及深抽擠料順暢之參數為模具摩擦力與模具精度。在模具設計方面，必須注意到每個到次之間的關聯性與連續性，尚須考慮到帶料、拉料、力量平衡、回彈等問題，利用有效的工程配置來完成模具的總體設計，建構出各工程之脫料行程、浮昇高度、成形沖頭高度等資訊，創建一個實體的模具。

完成簡易有限元素模擬試驗，將取得相關之數據套入各工程所需之技術參數，進行實例與模擬比對設計可行性，模擬分析與實際數據相互比對後，其結果顯示模擬與實際趨勢上相符合，更加驗證有限元素分析軟體應用於板材之抽引成形之可行性與可靠性。

關鍵字

金屬薄板 ； 成形技術 ； 有限元素法

並列摘要

Sheet metal forming technologies have been widely applied in various industries such as automobiles, steel, electronics, shipbuilding, aerospace, and weaponry industries. In this study, finite element method (FEM) and a physical model of stamping die technology were employed to investigate the feasibility of using sheet metal drawing technology and to effectively improve design methods. Drawing is a plastic processing method crucial to sheet forming and a vital component of manufacturing industries. The numerical simulation of sheet forming processes involves an extremely complex system. In traditional sheet forming approaches, the manufacturing cycle time for designing dies is excessively lengthy because substantial time is required to repeatedly undergo die tests. Consequently, the use of sheet forming technologies cannot be sustained, thus increasing the costs and duration of die development. Currently, experts from various industries believe that numerous uncertainties remain in the process of using the deep drawing die forming method. Thus, if development procedures are performed based on only experts’ experiences and no database is established for such procedures, development progresses cannot be determined effectively, which renders satisfying the requirements of industrial operators difficult.

With the continual development of computers and computer-aided technologies, deep drawing is gradually applied in the fields of metal plastic forming. In this study, FEM numerical simulation software (PAM-STAMP) was adopted; this software solves relevant problems by integrating sheet metal forming process with a FEM computer simulation technology. This FEM simulation technology was used to study the problems involved in sheet forming, predict and eliminate problems concerning sheet wrinkling and tearing, and reduce or cancel the use of test dies, thereby shortening the durations and lowering the costs of product developments.

This study employed PAM-STAMP to analyze and investigate the problems related to sheet metal forming. The results indicated that during sheet drawing, the materials used can be strongly pulled and pushed, and adjusting corner radius R can serve as the medium for controlling material flow. However, R must be appropriately adjusted, where overly high and low R results in rapid material flow and uneven thickness, respectively. Regarding the pushing of deep drawing material, parameters that influence dimensional precision and the smoothness of pushing processes include die friction and die precision. During the process of die design, attention must be paid to the relation and continuity between strip designs, in addition to considering problems related to strip, strip feeding, balance of force, and spring back. Furthermore, effective configuration was applied to complete the overall die design, determine the stripper travel distance, blank lifting height, and punch length, and devise a physical die.

After the simple FEM simulation test was performed, the acquired data were integrated with technology parameters required in various processes to perform simulations and actual tests for verifying the feasibility of the developed design. Comparing the simulation findings and actual data showed that the simulation and actual tests yielded consistent result, which further verified the feasibility and reliability of using FEM software in the simulation of sheet drawing.

並列關鍵字

Sheet Metal ； Forming Technology ； Finite Element

參考文獻

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