非對稱鋁合金型材擠製之有限元素分析

Finite Element Analysis of Asymmetric Extrusion of Aluminum-Alloy

洪俊銘(Chun-Ming Hong)

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(2007年)

https://doi.org/10.6342/NTU.2007.03054

摘要

鋁合金由於具有密度低、強度強之特點，目前因輕量化方面之運用而快速成長，而一般在生產非對稱中空產品時，常常是運用窗口模做生產，而擠製出的產品，常常會有彎曲、扭曲的情形，因此本論文利用有限元素模擬進行非對稱鋁合金型材擠製變形研究。
針對DEFORM模擬方面，由於軟體無法進行焊接室之模擬情形，本論文探討了剛性面及預成形擠錠兩種方法，順利解決了模擬問題，接著探討型材變形情形，發現型材變形主要是由於材料出口速度不一，導致型材會有彎曲、截面凹陷之情形發生。接著引用另一套有限元素軟體:HyperXtrude對模擬結果做一比較，兩者變形情形相當接近。
經由各製程參數分析之結果，得到擠錠溫度、推桿速度、及增加型材厚度並無法相當有效地改善缺陷情形，而在修改下模R角時，可確實改變材料流動情形，接著經由修改下模R角，去探討在材料不同流動情形下，型材變形情形，更確定了型材變形主要是由材料流動速度不均所造成。
最後運用田口式直交表法，對下模R角作一最佳參數化設計，經最佳化設計後，原設計下型材彎曲、凹陷的情形可獲得改善，而本論文之研究成果可供鋁合金擠製成形業者進行製程規劃以及模具設計時的參考。

關鍵字

A7075鋁合金 ； 窗口模 ； 電腦模擬分析 ； DEFORM ； 擠壓成形 ； 模具設計

並列摘要

The superior properties of aluminum-alloy draw attentions from the light-trend industry recently. The principal manufacturing process of the asymmetric hollow products of A7075 aluminum-alloy has been extruded by using porthole dies. However, there are usually bending and torsion defects on the hollow products. Therefore the extrusion process of asymmetric aluminum-alloy products is studied in the present study by the finite element analysis and experiments.
The finite element software DEFORM is employed to simulate the extrusion processes of asymmetric products. Due to the software DEFORM is not able to simulate welding directly, the problem is solved at first. Following the deformation of asymmetric products is studied. It shows the defects which are bending and torsion are caused by uneven material flow. In addition, another software HYPERXTRUDE is employed to compare simulation results with DEFORM.
The experiment of asymmetric extrusion was practiced to verify the analyzed results. The experimental results obtained in the present study show good agreement with simulations. It shows the finite element software DEFORM is suitable to process asymmetric extrusion.
The influence of important process parameters such as the temperature, extrusion speed, product thickness, m value, corner radius of bottom die are analyzed by simulations. According to the results of analysis, it shows the serious effect could be caused by corner radius of bottom die. Modifying the corner radius of bottom die indeed alters the material flow. Therefore, we can observe how the defect of profile changes under different material flow by changing the corner radius.
In the end, Taguchi method is applied to make the optimum design of corner radius of bottom die. After optimized the corner radius design, the bending and torsion of original design is improved. The results of this study can be reference resources for related academic research and can also be used to develop related products for industry production.

並列關鍵字

A7075 ； Porthole dies ； CAE ； DEFORM ； Extrusion ； Die design

參考文獻

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