管件液壓預成形製程之研究

A Study of Preforming Design in the Tube-Hydroforming Process

江彥輝(Yen-Hui Chiang)

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(2011年)

https://doi.org/10.6342/NTU.2011.01716

摘要

在當前成形技術，管件液壓成形技術漸漸崛起，在汽車產業中已廣泛使用此技術來加強車身強度與減輕結構重量。管件液壓製程包括：彎管、預成形與液壓成形，而本論文係針對汽車後懸吊系統之扭力樑管件液壓製程，使用不同之預成形設計進行成形性分析與缺陷之探討。
本論文首先利用一實際載具採用預成形與否進行分析，並探討後續產生之問題，包括製程的順利程度與實際開發之可行性。接著以該載具於液壓成形階段，設計不同負載曲線以進行較佳化分析，提供可行之負載曲線類型並建議較佳之一階與二階負載路徑。
為了節省後續加工，在模具上可以設計沖孔機構使管材在成形後可以接續模內沖孔道次。本論文針對實際載具液壓模內沖孔進行探討，首先以不同沖頭進行板件沖孔以觀察各沖頭之留料情況，經模擬分析與實際沖孔驗證後，提供合適沖頭套入模內沖孔製程進行模擬，並依模擬結果給予模內沖孔並留住廢料之設計條件。
本論文最後研究後懸吊系統扭力樑之預成形設計，探討其成形之可行性，以及對後續液壓成形之影響。由於該扭力樑具有雙軸向之彎曲曲率，造型較為複雜，經模擬分析結果建議以多道次進行該扭力樑之實際開發。本研究成果可提供扭力樑管件液壓成形製程之設計參考。

關鍵字

管件液壓成形 ； 後懸吊系統扭力樑 ； 預成形 ； 液壓模內沖孔 ； 負載路徑

並列摘要

Nowadays, Tube hydroforming (THF) technique has been popularly applied to the car body structural components. The advantages of employing THF process over the conventional stamping and welding process have been lightweight and high strength for the car body structure. There are three operations in a complete THF process, which are tube bending, preforming, and hydro-forming. In the present study, the preforming die design and the loading path adopted in the hydroforming operation for manufacturing a twist beam used in a real axle were examined. In addition, the punch shape for hydro-piercing a scrap-attached hole was also investigated. Both the finite element simulations and the experimental approaches were employed to complete the analysis and die design.
Since the twist beam bears a relatively small curvature in one plane, it is difficult to bend the tube by a bending machine and needs to produce the bend in a preforming die. Also due to the deep V-shaped cavity along the curved axis of the twist beam, one or two more preforming operations are required to provide an appropriate preformed tube to the subsequent hydroforming operation. In the present study, the number of preforming operations and the geometry of each prefoming die are determined by the finite element analysis. It is found that three preforming operations are required for hydroforming this curved twist beam if a cam mechanism is not involved in the preforming operation. In addition, different loading paths are designed for the hydroforming operation to investigate the formability of this twist beam using the finite element simulations. Based on the finite element analysis, an optimum single-step loading path was established. However, a two-step loading path that would improve the maximum thinning a little bit was also developed.
As for the hydro-piercing operation, different punch shapes were designed to investigate the hole-piercing performance. The hole-piercing experiments were conducted first in a stamping process without hydraulic pressure acting on the opposite side of the sheet. The appropriate geometry of the punch shape was then applied to the hydro-piercing operation. The finite element simulation results indicate that the proposed punch shape could pierce the hole with the scrap remained in the tube that is required by the part design. The developed preforming die design concept, the loading path used in the hydroforming operation, and the punch shape for the hydro-piercing process could provide a valuable reference to the future study in the tube-hydroforming research field.

並列關鍵字

tube-hydroforming ； twist beam ； rear axle ； preforming die design ； hydro-piercing ； loading path

參考文獻

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