High Precision Draw Bending of Asymmetric Channel Section with Restriction Dies and Axial Tension

In recent years asymmetric cross section aluminum alloy stock has been finding increasing use in various industrial manufacturing areas such as general structures and automotive components. In these areas, components are generally required to have complex curved configuration and, as such, a bending process is required during manufacture. Undesirable deformation in bending processes such as flattening or wrinkling can easily occur when thin-walled sections are bent. Hence, a thorough understanding of the bending behavior of such sections is needed to prevent these undesirable deformations. In this study, the bending behavior of asymmetric channel section was examined using finite element analysis (FEA). Typical methods of preventing undesirable deformation, such as asymmetric laminated elastic mandrels were included in FEA model of draw bending. Additionally, axial tension was applied to prevent wrinkling. By utilizing the FE simulations effect of restriction dies and axial tension on undesirable deformation during the process was clarified.

Authors:

• Y. Okude
• S. Sakaki
• S. Yoshihara
• B. J. MacDonald

Keywords:

• bending
• draw bending
• asymmetric channel section
• restriction dies
• axial tension
• FEA

References:

[1] N. Utsumi, "Countermeasures against undesirable phenomena in the draw-bending process for extruded square tubes," J. Mater. Process. Technol., vol. 123, pp. 264-269, Apr. 2002.
[2] H. Li, "A new method to accurately obtain wrinkling limit diagram in NC
bending process of thin-walled tube with large diameter under different
loading paths," J. Mater. Process. Technol., vol. 177, pp. 192-196, July 2006.
[3] K. Trana, "Finite element simulation of the tube hydroforming processÔÇöbending, preforming and hydroforming," J. Mater. Process. Technol., vol. 127, pp. 401-408, Oct. 2002.
[4] M. Murata, "Effect of hardening exponent on tube bending," J. Mater.
Process. Technol., vol. 201, pp. 189-192, May 2008.
[5] O. Sonobe, "Deformation mechanism of thin-walled tubes in bending
method with slight reduction in diameter," J. of the JSTP, vol. 52, pp. 720-725, June 2011 (in Japanese).
[6] O. Sonobe, "Deformation behavior of thin-walled ERW tubes in bending
method with slight reduction in diameter and FEM simulation," J. of the
JSTP, vol. 52, pp. 715-719, June 2011(in Japanese).
[7] H. Suzuki, "Bending of circular tube with a drawing die," The Japan
society of mechanical engineering, vol. 54, pp. 1933-1937, Aug. 1988(in
Japanese).
[8] S. Maki. Addition of pulling force to pipe bending method using a
floating expanding plug," J. of the JSTP, vol. 42, pp.129-133, Apr. 2000
(in Japanese).
[9] M.M. Pastor, "Open cross-section beams under pure bending. I. Experimental investigations," Thin-Walled Structures, vol. 46, pp.
476-478, May 2008.
[10] M.M. Pastor, "Open cross-section beams under pure bending II. Finite
element simulation," Thin-Walled Structures, vol. 47, pp. 514-521, May
2009.
[11] A.A. EL-DOMIATY, "Open cross-section beams under pure bending II.
Finite element simulation," Int. J. Math. Tools Manufact, vol. 38, pp. 75-95, Feb. 1998.
[12] Y. Liu, "Bending collapse of thin-walled circular tubes and computational
application," Thin-Walled Structures, vol. 46, pp. 442-450, Apr. 2008.
[13] Z. YU, " Numerical analysis of dimension precision of U-shaped
aluminium profile rotary stretch bending," Transactions of Nonferrous
Metals Society of China, vol. 17, pp. 581-585, June 2007.
[14] I. Ochiai, "A study of V-bending of thin channels," J. of the JSTP, vol. 10,
pp.591-597, Aug. 1969 (in Japanese).
[15] I. Ochiai, "Improvement of bending accuracy on draw bending of channel
section," 2002 Jpn. Spring conf. for the Technol. of plasticity, pp.363-364, (in Japanese).