高強度鋼板沖壓成形之材料模型探討

RESEARCH ON MATERIAL MODEL OF HIGH STRENGTH STEEL FOR STAMPING PROCESS

張家源(Chia-Yuan Chang)

指導教授 ： 李碩仁

元智大學/工程學院/機械工程學系/碩士(2012年)

https://doi.org/10.6838/YZU.2012.00002

摘要

本論文以U形模具進行沖壓成形回彈現象之研究，為了解傳統鋼板與高強度鋼板兩者回彈現象的差異，選用抗拉強度270級軟鋼與590級、980級高強度鋼板，使用三種沖頭圓角半徑R3、R6與R9進行沖壓實驗，搭配套裝軟體AutoForm模擬U形模具沖壓回彈。在模擬過程使用抗拉強度270級軟鋼與590級、980級的高強度鋼板三種材料外，並採用AutoFrom材料模型不同硬化準則與動態硬化模型模擬，探討使用不同材料模型時，高強度鋼板回彈模擬的準確性。
經由模擬與實驗結果比對，實驗部分可得：在相同的沖頭圓角半徑下，材料強度越大時，沖壓回彈量會隨之增加；而在不同的沖壓圓角半徑時，隨著沖頭圓角半徑的增加，回彈量明顯提升。
於模擬部分可得：(1)不考慮動態硬化模型：在270級軟鋼時，選用Hockeet-Sheby硬化準則，其模擬結果趨勢較為接近實驗值；而於590級高強度鋼，選用Combined S-H硬化準則之模擬結果趨勢接近實驗值；在980級高強度鋼時，以Ghosh與Hockeet-Sheby硬化準則之模擬結果趨勢與實驗值較為一致。(2)考慮動態硬化模型：對於270級軟鋼之模擬值與實驗值兩者差異不大；在590級高強度鋼時，選用Combined S-H硬化準則搭配動態硬化模型，其模擬結果誤差較小。而980級高強度鋼板，在Hockeet-Sheby與Combined S-H硬化準則搭配動態硬化模型時，會有較佳的預測值。
由U形模具沖壓模擬與實驗比對結果可知，高強度鋼板材料在模擬時使用動態硬化模型後，相較於未使用動態硬化模型之模擬結果，可獲得較準確的預測值。

關鍵字

高強度鋼板 ； 回彈現象 ； AutoForm ； 沖壓成形 ； CAE模擬 ； 材料模型 ； 硬化曲線

並列摘要

This paper study the springback phenomenon of the U-shaped sheet of the stamping process. In order to understand the differences in springback phenomenon between different traditional high strength steel sheets, 270 mild steel sheet, 590 and 980 high strength steel sheets with punch radius 3, 6 and 9 mm are used to conduct actual experiments and perform numerical simulation with commercial software AutoForm. In the numerical simulation, the four hardening laws and one kinematic hardening model are used.
The results of the simulation and the experiment are compared. The optimal material model and certain phenomenon of springback for steel sheets 270, 590, 980 are obtained as follows: (1) If kinematic hardening model is not considered, the simulation results of the 270 mild steel sheet with Hockeet-Sheby hardening law is most close to the experimental value than the other hardening law models. The simulation results of 590 high strength steel with Combined S-H hardening law is most close to the experiment results than the other hardening laws. 980 high strength steels with Ghosh and Hockeet-Sheby hardening law is most close to the experimental value than the other hardening laws. (2) If the kinematic hardening model is considered, the simulation results of the 270 mild steel match the experimental results. The 590 high strength steel with the Combined S-H is more close to the experimental results than the others. But, the 980 high strength steel with Hockeet-Sheby and Combined S-H hardening laws have a better predictive value with experiments than the other hardening laws. (3) The springback angle increases with the punch radius. (4) The springback angle increases with the strength of steel sheet.
By comparison of the results between the simulation and the experiments of stamping the U-shaped high strength steel, the simulation results with kinematic hardening model is more accurate than the ones without kinematic hardening model.

並列關鍵字

AutoForm ； Stamping ； CAE simulation ； Material model ； Hardening curve ； High strength steel ； Springback

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