汽車前副車架管件液壓成形回彈現象之研究

A Study of Springback Phenomenon Occurred in a Tube-Hydroformed Automotive Front Sub-Frame

古宇鈞(Yu-Jyun Gu)

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(2019年)

https://doi.org/10.6342/NTU202000784

摘要

隨著節能減碳等綠能環保議題日益被重視，低油耗及車體輕量化為汽車產業之一大發展趨勢，管件液壓成形技術已被大量應用於汽車零組件及結構件上，而液壓件式前副車架也已廣泛用在各級車種上。本論文首先針對管件液壓成形製程中之前副車架回彈問題進行研究與分析，並也對前副車架之成形性進行探討與驗證。
本論文利用有限元素法軟體對於前副車架回彈現象進行模擬建立與分析，也說明模擬分析時回彈現象之計算求解方式及量值記錄方式，並觀察其應力分佈情形，找出其回彈發生機制，而另一面也對製程參數及材料性質參數進行探討，了解其影響程度。
本論文先針對前副車架之管件液壓成形道次進行分析探討，主要包含：直管下料、彎管成形、預成形、液壓成形。首先對載具進行截面分析及初步可成形性分析以判斷下料管材尺寸，接著在彎管成形道次中，透過與實際彎管成品逆向掃描結果進行比對修正模擬，使模擬結果更具有真實性，並貼近實際製程中之現象；在預成形道次中，利用側向CAM模之作動來成形管材，以提高模具設計之靈活度；在液壓成形道次中，則透過蒐集之文獻資料及模擬分析，得出一較佳之壓力側推負載路徑以滿足載具之成形性需求，並應用到實際製程中。
前副車架回彈現象改善方面，由於為開模生產後所發生之問題，因此將透過製程中影響因素及相關參數之探討，其中包含彎管成形道次、預成形道次、液壓成形道次及低壓成形等，以找出對回彈現象改善之可能性。而本論文最後也透過成品實際尺寸與有限元素法軟體之模擬結果進行比較，以驗證有限元素法之準確性。本論文研究成果可輔助實際製程之設計與優化，提供前副車架管件液壓成形相關之模具開發人員參考，以及前副車架回彈現象分析使用。

關鍵字

前副車架 ； 管件液壓成形 ； 有限元素法 ； 回彈分析 ； 預成形 ； 低壓成形

並列摘要

As carbon reduction and some green energy environmental issues are increasingly considered an important issue, low fuel consumption and lightweight of car body are the major development trends in the automotive industry. Due to the fact that the tube-hydroforming technology has been widely used in the manufacture of automotive parts. Further, the tube-hydroformed parts of front sub-frame have also been applied to various types of cars. This thesis began with the research about the springback phenomenon of hydroformed front sub-frame. Then, this thesis also analyzed and validated the formability of the hydroformed front sub-frame.
The simulation model and analysis for the springback phenomenon of front sub-frame were established by finite element method in this thesis. The solution method and recording mode for the amount of springback during simulation analysis were also illustrated in detail. Then, based on these, the mechanism of springback was searched out by observing the distribution of stress. In order to understand the influence of the springback phenomenon, the present study also discussed the process parameters and material parameters by simulation analysis.
The analysis and exploration of front sub-frame tube hydroforming process which includes tube bending, pre-forming, and hydroforming was performed in this thesis for the first. First, the initial feasibility analysis is determined by combining sectional analysis and component shape for predicting the size of tube. Then, in order to conform the to the real production condition, the simulation was modified by comparing tube bending simulation results to reverse scanning results of real tubes. As for preforming process, side cam action was used in preforming die to increase flexibility of tool design. In the hydroforming process, this thesis modified the loading path referring to the published literatures and simulation analysis results that provided a better formability for the tube tube-hydroformed part, and applied that to the real process.
As for ameliorating the springback phenomenon of front sub-frame, due to that the problem was occurred after molding and producing product, some influencing factors and process parameters which includes tube bending, pre-forming, hydroforming and low-pressure hydroforming were discussed for searching out the probability of ameliorating the springback phenomenon. Lastly, the hydroforming product dimensions of an actual front sub-frame were performed to validate the results of simulation analysis conducted in this thesis for ensuring the accuracy of the finite element method. The research results of this thesis could be valuable reference in developing the tube hydroforming process for manufacturing the front sub-frame and aid of the design and optimization in real process.

並列關鍵字

front sub-frame ； tube-hydroforming ； finite element method ； springback analysis ； pre-forming ； low-pressure hydroforming

參考文獻

[1] http://www.inoxveneta.it/en/tube-hydroforming/

[2] 鄭炳國，「管件液壓成形」，科學發展，400期，12-17頁，2006。

[3] https://www.totalmateria.com/page.aspx?ID=CheckArticle&site=kts&NM=344

[4] H. Yoshida, “Front sub-frame structure”, U.S. Patent, Appl. No. 6390224, 2002.

[5] K. J. Kim, J. S. Kim, B. I. Choi, K. H. Kim, H. H. Choi, C. W. Kim, K. W. Kang, J. H. Song and C. W. Sung, “Development of automotive engine cradle by hydroforming process”, Journal of Mechanical Science and Technology, Vol. 21, pp. 1523-1527, 2007.