管材機械性質與液壓成形製程分析

An Analysis of Tube Material properties and Tube-Hydroforming Processes

邱黃正凱(Jheng-Kai Ciou Huang)

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(2005年)

https://doi.org/10.6342/NTU.2005.00319

摘要

管件液壓成形技術應用在汽車輕量化的零組件方面有越來越多的趨勢，但其原始素材與製造方式皆與傳統的沖壓有所差異，因此本論文將探討管件材料性質以及模具設計方式。
本論文先藉由製管模擬來探討板材與管材材料性質之差異性，預期能夠藉由管件的幾何尺寸由板材預測管件的材料性質，在實驗驗證方面，選擇了不同尺寸之管材(四組熱軋鋼管、一組冷軋鋼管、三組不繡鋼管)比較板材與管件材料性質之差異性，並針對熱軋鋼管及不繡鋼管的部份建立了預測公式。本論文並對管材圓周方向的材料進行拉伸試驗，探討Bauschinger Effect對實驗結果之影響。最後建立一套管件材料性質的試驗流程，進行CAE模擬時可利用此方法快速的得到管件的材料性質。
在液壓成形製程中，成品常會有無法脹出的凹陷產生。本論文針對此現象分析管件在預成形時所允許之最大凹陷量，並進一步分析模具形狀對管件凹陷量的影響。管件下料尺寸亦是影響凹陷產生與否的因素之一。因此，當決定好管件下料尺寸之後，必須特別注意管件膨脹率在5﹪以下的截面，此處的成形結果很可能會有凹陷產生，最後藉由不同的模具設計方式改善管件成形後的凹陷情形。
在管件液壓成形製程規劃方面，本論文選取了一具有代表性的汽車結構件進行分析，由原始的彎管、預成形、到液壓成形皆建立了CAE模擬模式，並探討不同的預成形設計方式以及彎管半徑對管件最終成形之影響。本研究並實際配合廠商所生產之液壓成形結構件驗證模擬之正確性，由成品得知有限元素法軟體預測管件成形後的外形準確性相當高，成品產生凹陷的地方其趨勢和模擬結果是一致的。本論文所獲得之研究成果可提供管件液壓成形業者進行製程規劃以及模具設計時的參考。

關鍵字

液壓成形 ； 最大凹陷量 ； 預成形

並列摘要

The application of tube-hydroforming technology to the parts of lightweight automobile is becoming more and more popular, but its original blank and manufacture processes are different from those in the conventional stamping. So, this paper will discuss the material properties of tubes and the methods of die design.
This paper first discusses the differences of material properties between the plate and the tube by the simulation of tube-making, in order to predict the tube material properties by the dimensions of the tube. In terms of the experimental verification, this paper compares the material properties between the plate and the tube by experimenting on the tubes of different dimensions, including four hot-rolled tubes, one cold-rolled tube, and three stainless tubes. The results of the experiments can be used to establish the predictive formulas of the hot-rolled and stainless tubes. In addition, this paper discusses the Bauschinger Effect on the experimental results. Finally, this paper establishes a process for material tests.
This paper also analyzes the maximum allowable wrinkle of the tube in the preform process and discusses the effect of die shape on the wrinkle of the tube. Another factor that influences the wrinkle is the tube size. When the tube size is determined, special attention should be paid to the section of the die at the tube expansion rate under 5%, where unexpanded hollowness happens easily. The last step is to improve the hollowness of the tube by different die designs.
In the planning of the hydroforming process, the paper analyzes a representative automobile part to build up the CAE simulation model of tube bending, preforming, and hydroforming, and discusses the influence of different preform designs and bending radii on the final shape of the tube. In this paper, we also compare the simulation results with the actually hydroformed parts. The results show that there is a considerable accuracy of simulation by using the finite element method. The results of this study can be a reference for related academic research and can also be used to develop related products for industry production.

並列關鍵字

hydroforming ； Bauschinger Effect ； maximum wrinkle ； preform

參考文獻

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