管件液壓成形製程之有限元素法分析

The Finite Element Analysis of Tube Hydroforming Processes

詹惟嶸(Way-Rome Zhan)

指導教授 ： 陳復國

國立臺灣大學/工學院/機械工程學研究所/碩士(2004年)

https://doi.org/10.6342/NTU.2004.01390

摘要

管件液壓成形（Tube Hydroforming）即是藉著高壓液體去完成金屬管材之膨脹變形的加工方式。管件液壓成形具有強度高、質量輕、節省材料、減少產品組裝道次、降低成本等優點，因此管件液壓成形此項技術遂成為國際各大車廠積極投入開發研究的項目之一。

由於材料之機械性質為CAE模擬所不可或缺的參數，因此建立正確的材料性質曲線是必須的，由於管件之材料性質不易取得，因此本論文利用簡易之CAE模擬模型，希望能利用原板材的材料性質預測管件的材料性質，並利用實驗與模擬結果做相關的比對，實驗結果發現實際製管過程所造成的加工硬化值要比模擬結果來得大，模擬所預測的加工硬化值為理想的製管過程，是不考慮摩擦等因素所造成的最小的加工硬化值。此外實驗發現管件的拉伸曲線在經過一個offset值之後確實可以與原板材的拉伸曲線重合，這表示材料的最大伸長量是固定的，隨著應變的累積，所剩餘的伸長量將會越來越少。

在液壓壓力與製程參數之關係驗證上，是藉由CAE的模擬結果與理論模型做相關的驗證，驗證結果發現理論模型在高壓時會些釭滌爬蘁犍顝珨搌漲豆怹ㄓO，但在實務上在應用公式來評估液壓時，雖然會使公式計算結果正確性略降，但是卻不用擔心”未填滿”的問題，此項公式在工程的應用上算是最大所需的成形壓力（upper bound），因此即使正確性略降，但是在工業上的應用是沒有問題的。

製程規劃方面，由於已經驗證成形性公式的正確性，因此可利用成形性公式進行製程規劃，計算所需的成形壓力以及所需的壓模力為何，在產品開發初期之時便能初步的規劃各項所需的設備。

本論文已根據實際的液壓成形製程建立完整的CAE模擬模式，提供設計者一套完整的液壓成形的模擬模式，並針對各製程可能發生的各種缺陷有初步的研究，此外也初步的建立管件液壓成形製程所需的設計流程。

關鍵字

壓模力 ； 板件液壓成形 ； 成形壓力 ； 液壓成形 ； 未填滿 ； 加工硬化值 ； 管件液壓成形

並列摘要

Tube hydroforming is a manufacturing process to form desired component shapes by fluid pressure which is applied ductile metallic tube blanks. This takes low cost, low mass and can retrench materials, even improve structural performance. Hence, tube hydroforming is one of the technologies that car companies investigate aggressive.

Because the material properties are required in computer simulations, tube material properties are investigated in the present study. Tensile tests from the tube are not easy to obtain. However, in order to predict the tube material properties, the simple model is established. The experimental results reveal that strain hardening during the tube-rolling process is higher than the computer simulation. Nevertheless, the computer simulation is the least strain hardening during the tube-rolling process. Besides, after the offset of tube materials, the stress curve can overlap tube materials and original materials. It reveals that the failure point is the same. As the material strain hardens, it gets nearer to its failure point.

Computer simulation is used to prove the formability formula. The results of the formability formula show higher forming pressure than exact forming pressure. According to the above results, the phenomenon of under-fill will not happen in the application because the calculated value is higher than the right value. The formula can be used in application.

The formability formula can estimate the forming pressure and the holding force since it is proved the precision. The designer can decide the hydraulic system and hydraulic press from the calculation in the initial stage.

The overall requirements for the simulation of tube hydroforming are fully discussed in the present study. From the simulation, the defects are also investigated.
Furthermore we also create some design guidelines for the designers who want to investigate the technology of tube hydroforming.

並列關鍵字

strain hardening ； hydroforming ； sheet metal hydroforming ； holding force ； under fill ； forming pressure

參考文獻

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