Abstract
With increasing diameters of aluminum alloy thin-walled tubes (AATTs), the tube forming limits, i.e. the minimum bending factors, and their predictions under multi-index constraints including wrinkling, thinning and flattening have been being a key problem to be urgently solved for improving tube forming potential in numerical control (NC) bending processes of AATTs with large diameters. Thus in this paper, a search algorithm of the forming limits is put forward based on a 3D elastic-plastic finite element (FE) model and a wrinkling energy prediction model for the bending processes under axial compression loading (ACL) or not. This algorithm enables to be considered the effects of process parameter combinations including die, friction parameters on the multi-indices. Based on this algorithm, the forming limits of the different size tubes are obtained, and the roles of the process parameter combinations in enabling the limit bending processes are also revealed. The followings are found: the first, within the appropriate ranges of friction and clearances between the different dies and the tubes enabling the bending processes with smaller bending factors, the ACL enables the tube limit bending processes after a decrease of the mandrel ball thickness and diameters; then, without considering the effects of the tube geometry sizes on the tube constitutive equations, the forming limits will be decided by the limit thinning values for the tubes with diameters smaller than 80 mm, while the wrinkling for the tubes with diameters no less than 80 mm. The forming limits obtained from this algorithm are smaller than the analytical results, and reduced by 57.39%; the last, the roles of the process parameter combinations in enabling the limit bending processes are verified by experimental results.
Article PDF
Similar content being viewed by others
Avoid common mistakes on your manuscript.
References
Yang H, Sun Z C, Lin Y, et al. Advanced plastic processing technology and research progress on tube forming (in Chinese). J Plast Eng, 2001, 8(2): 86–88
Gillanders J. Pipe and Tube Bending Mannual. Houston: Gulf Publishing Company, 1984. 102
Butuca M C, Gracioa J J, Barata da R A. An experimental and theoretical analysis on the application of stress-based forming limit criterion. Int J Mech Sci, 2006, 48(4): 414–429
Ozturk F, Lee D. Analysis of forming limits using ductile fracture criteria. J Mater Process Technol, 2004, 147(3): 397–404
Koc M, Altan T. Prediction of forming limits and parameters in the tube hydroforming process. Int J Mach Tools Manuf, 2002, 42(1): 123–138
Wang X, Cao J. Wrinkling limit in tube bending. Trans ASME, 2001, 123(4): 430–435
Yang H, Lin Y. Wrinkling analysis for forming limit of tube bending processes. J Mater Process Technol, 2004, 152(3): 363–369
Li H, Yang H, Zhan M, et al. 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, 2006, 177(1–3): 192–196
Narayanasamy R, Loganathan C. Study on wrinkling limit of commercially pure aluminum sheet metals of different grades when drawn through conical and tractrix dies. Mater Sci Eng A, 2006, 419(1–2): 249–261
Palumbo G, Tricarico L. Numerical and experimental investigations on the warm deep drawing process of circular aluminum alloy specimens. J Mater Process Technol, 2007, 184(1–3): 115–123
Yang T S. The strain path and forming limit analysis of the lubricated sheet metal forming process. Int J Mach Tools Manuf, 2007, 47(7–8): 1311–1321
Kima J, Kimb S W, Songa W J, et al. Analytical and numerical approach to prediction of forming limit in tube hydroforming. Int J Mech Sci, 2005, 47(7): 1023–1037
Lee J W, Kwon H C, Rhee M H, et al. Determination of forming limit of a structural aluminum tube in rubber pad bending. J Mater Process Technol, 2003, 140(1–3): 487–493
Li H, Yang H, Zhan M, et al. Wrinkling limit based on FEM virtual experiment during NC bending process of thin-walled tube. Mater Sci Forum, 2004, 471–472: 498–502
Gu R J, Yang H, Zhan M, et al. Effect of mandrel on cross section quality of thin-walled tube NC bending. Trans Nonferrous Met Soc China, 2005, 15(6): 1264–1274
Li H, Yang H, Zhan M, et al. Forming characteristics of thin-walled tube bending process with small bending radius. Trans Nonferrous Met Soc China, 2006, 16(Suppl): 613–623
Li H. Study on wrinkling behaviors under multi-die constraints in thin-walled tube NC bending (in Chinese). Dissertation of Doctoral Degree. Xi’an: Northwestern Polytechnical University, 2007. 76
Yang H, Yan J, Zhan M, et al. 3D numerical study on wrinkling characteristics in NC bending of aluminum alloy thin-walled tubes with large diameters under multi-die constraints. Comput Mater Sci, 2009, 45(4): 1052–1067
ABAQUS. Version 6.5. Washington (FL): Hibbit Karlson and Sorensen Inc. 2005
Sun W Y, Xu C X, Zhu D T, et al. Optimization Method (in Chinese). Beijing: Higher Education Press, 2004. 89
Author information
Authors and Affiliations
Corresponding author
Rights and permissions
About this article
Cite this article
Yan, J., Yang, H., Zhan, M. et al. Forming limits under multi-index constraints in NC bending of aluminum alloy thin-walled tubes with large diameters. Sci. China Technol. Sci. 53, 326–342 (2010). https://doi.org/10.1007/s11431-009-0331-x
Received:
Accepted:
Published:
Issue Date:
DOI: https://doi.org/10.1007/s11431-009-0331-x