Increasing the dimensional accuracy of U-bend product of high strength steel sheets by controlling the pressure pad

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Prasan Saengkhiao
Komgrit Lawanwong


To reduce springback in U-shape of high strength steel sheet, the present paperproposes a new process parameter in U-bending technique. This paper aims to present the effect of clearance between die and counterpunch on springback behavior. The process in this work consists of four steps; (1) clamping of a sheet between a punch and a pressure pad, (2) bending with constant clamping force, (3) pushing-up at bottom of the part by using the pressure pad , and (4) final release tool. From the experimental results, decreasing of bending moment by bottom pushing-up resulted in the springback reduction. An appropriate of the clearance between die and pressure pad combined with bottom pushing-up force can be reduced springback. Our results suggested that the Y-U model, an advanced kinematic hardening, is essential for accurate numerical simulation of springback behavior.

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[1] Nagai Y.Accurate U-bending of sheets, J. JPN. Soc. Technol 1988; 234:69-74.

[2] M. Sunseri, J. Cao, A. P. Karafillis and M. C. Boyce. Accommodation of Springback Error in Channel Forming Using Active Binder Force Control: Numerical Simulations and Experiments. J. Eng. Mater. Technol 1996; 118:426-35.

[3] F. Yoshida, T. Uemori, K. Fujiwara. Elastic–plastic behaviour of steel sheets under in-plane cyclic tension-compression at large strain. International Journal of Plasticity 2002; 8:633–59.

[4] F. Yoshida, T. Uemori. A model of large-strain cyclic plasticity describing the Bauschinger effect and workhardening stagnation. International Journal of Plasticity 2002; 18:661–86.

[5] Y.E. Ling, H.P. Lee, B.T. Cheok. Finite element analysis of springback in L-bending of sheet metal. J. Mater. Process. Tech 2005; 168:296-302.

[6] Takeshi Uemori, Satoshi Sumikawa, Shohei Tamura, Hiroyuki Akagi, Tetsuo Naka, and Fusahito Yoshida. Spring back Simulation of High Strength Steel Sheets Calculated by Yoshida-Uemori Model. Steel research special edition 10 international conferences metal forming 2010; 825-8.

[7] T.Ogawa, F. Yoshida. Springback analysis on U-bending with bottoming. Steel research special edition 10 international conferences metal forming 2011; 845-9.

[8] Hiroshi Hamasaki, Kelim Yilamu, Ryutaro Hino and Fusahito Yoshida. Spring back predivtion for 430ss Stainless Clad aluminium alloy sheet by using accurate cyclic stress-strain response of individual layer. Steel research International special edition of 14 the international conferences metal forming 2012; 343-6.

[9] Joonhang Lee, Kwangmin Lee, Dongok Kim, Hongseok Choi and Byungmin Kim. Spring-back and spring-go behaviors in bending of thick plates of high-strength steel at elevated temperature. Computational Materials Science 2015; 100:76-9.

[10] L. Komgrit, H. Hamasaki, R. Hino and F. Yoshida. Elimination of Spring back of High-Strength Steel Sheet by using Additional Bending with Pressure pad Punch. J. Mater. Process. Tech 2016; 16:199–206.

[11] Xiaohui Cui, Jianhua Mo, Jianjun Li, Hailiang Yu, Qingshan Wang. Reduction of springback in V-shaped parts using electromagnetic impulse calibration. Procedia Engineering 2017; 207: 801-6.

[12] Naoko Saito, Mitsugi Fukahori, Toru Minote, Yoshimasa Funakawa, Daisuke Hisano, Hiroshi Hamasaki, Fusahito Yoshida. Elasto-viscoplastic behavior of 980 MPa nano-precipitation strengthened steel sheet at elevated temperatures and springback in warm bending, International Journal of Mechanical Sciences 2017, Corrected Proof.

[13] Xiaoli Liu, Jianguo Cao, Xueting Chai, Jiang Liu, Rongguo Zhao, Ning Kong. Investigation of forming parameters on springback for ultra high strength steel considering Young’s modulus variation in cold roll forming, Journal of Manufacturing Processes 2017; 209:289-97.

[14] Christian Löbbe, A. Erman Tekkaya. Mechanisms for controlling springback and strength in heat-assisted sheet forming. CIRP Annals 2018; In Press: Corrected Proof.

[15] Hong-Liang Dai, Hao-Jie Jiang, Ting Dai, Wei-Li Xu, Ai-Hui Luo, Investigation on the influence of damage to springback of U-shape HSLA steel plates, Journal of Alloys and Compounds 2017; 708:575-86.