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Enhancement of Dimple Formability in Sheet Metals by 2-Step Forming

2중 성형에 의한 금속판재 딤플의 성형성 향상

  • Kim, Hasung (Dept. of Mechanical Engineering, Sogang Univ.) ;
  • Kim, Minsoo (Dept. of Mechanical Engineering, Sogang Univ.) ;
  • Lee, Hyungyil (Dept. of Mechanical Engineering, Sogang Univ.) ;
  • Kim, Naksoo (Dept. of Mechanical Engineering, Sogang Univ.) ;
  • Kim, Dongchoul (Dept. of Mechanical Engineering, Sogang Univ.)
  • Received : 2012.11.12
  • Accepted : 2013.05.29
  • Published : 2013.07.01

Abstract

In this study, a 2-step stamping model with an additional 1st stamping tool is proposed to reduce stamping flaws in the curved parts of a dimple in a nuclear fuel spacer grid. First, the strains of curved part of dimple are characterized via a comparison with strain solutions in pure bending. A reference 2D finite element (FE) model of 1-step stamping is then established, and the corresponding maximum strain is obtained. By varying the values of design variables of the 1st stamping tool in the 2-step stamping model, FE solutions are obtained to express the strain as a function of process variables, which provides the optimum values of process variables. Finally, applying these optimum values to a 3D FE model, we demonstrate the enhanced formability of the proposed 2-step stamping model.

Keywords

Forming Process Design;2-Step Forming;Finite Element Analysis;Response Surface Method;Formability;Forming Limit Diagram

Acknowledgement

Supported by : 한국연구재단

References

  1. Shin, M. K., Lee, H. A., Lee, J. J., Song, K. N. and Park, G. J., 2008, Optimization of a Nuclear Fuel Spacer Grid Spring Using Homology Constraints, Nuclear Engineering and Design, Vol. 238, pp. 2624-2634. https://doi.org/10.1016/j.nucengdes.2008.04.003
  2. Kim, K. S., Yoon, K. H. and Song, K. N., 2006, FEM Analysis of Optimized H Type Grid Spring by using the Gap Elements, Trans. Korean Soc. Mech. Eng. A, pp.1-6.
  3. Kim, S.-H., Kim, S.-H. and Huh, H., 2002, Tool Design in a Multi-Stage Drawing and Ironing Process of a Rectangular Cup with a Large Aspect Ratio using Finite Element Analysis., International Journal of Machine Tools & Manufacture, Vol. 42, pp. 863-875. https://doi.org/10.1016/S0890-6955(02)00003-2
  4. Kim, Y., Kim, J. and Kang, B.-S., 2005, Analysis of Multi-Stage Deep Drawing Process for Rectangular Container Using Finite Element Method, Trans. Korean Soc. Mech. Eng. A, pp.1453-1456.
  5. Kim, H.-K. and Hong, S.K., 2007, FEM-Based Optimum Design of Multi-stage Deep Drawing Process of Molybdenum Sheet, Journal of Materials Processing Technology, Vol. 184, pp. 354-362. https://doi.org/10.1016/j.jmatprotec.2006.12.001
  6. Abe, Y., Mori, K. and Ebihara, O., 2002, Optimization of the Distribution of Wall Thickness in the Multistage Sheet Metal Forming of Wheel Disks, Journal of Materials Processing Technology, Vol. 125-126, pp. 792-797. https://doi.org/10.1016/S0924-0136(02)00394-1
  7. Ku, T.W., Ha, B.K., Song, W. J., Kang, B.S. and Hwang, S.M., 2002, Finite Element Analysis of Multi-Stage Deep Drawing Process for High-Precision Rectangular Case with Extreme Aspect Ratio, Journal of Materials Processing Technology, Vol. 130-131, pp. 128-134. https://doi.org/10.1016/S0924-0136(02)00737-9
  8. Huang, Y., Lo, Z. Y. and Du, R., 2006, Minimization of the Thickness Variation in Multi-step Sheet Metal Stamping, Journal of Materials Processing Technology, Vol. 177, pp. 84-86. https://doi.org/10.1016/j.jmatprotec.2006.03.225
  9. Azaouzi, M., Lebaal, N., Rauchs, G. and Belouettar, S., 2012, Optimal Design of Multi-step Stamping Tools Based on Response Surface Method, Simulation Modeling Practice and Theory, Vol. 24, pp. 1-14. https://doi.org/10.1016/j.simpat.2012.01.006
  10. Chen, W., Liu, Z. J., Hou, B. and Du, R. X., 2007, Study on Multi-stage Sheet Metal Forming for Automobile Structure-pieces, Journal of Materials Processing Technology, Vol. 187-188, pp. 113-117. https://doi.org/10.1016/j.jmatprotec.2006.11.163
  11. Tsai, H.-K., Liao, C.-C. and Chen, F.-K., 2008, Die Design for Stamping a Notebook Case with Magnesium Alloy Sheets, Journal of Materials Processing Technology, Vol. 201, pp. 247-251. https://doi.org/10.1016/j.jmatprotec.2007.11.288
  12. Chen, W., Lin, G. S. and Hu, S. J., 2008, A Comparison Study on the Effectiveness of Stepped Binder and Weld Line Clamping Pins on Formability Improvement for Tailor-Welded Blanks, Journal of Materials Processing Technology, Vol. 207, pp. 204-210. https://doi.org/10.1016/j.jmatprotec.2007.12.100
  13. Wang, W.-R., Chen, G.-L. and Lin, Z.-Q., 2010, The Effect of Binder Layouts on the Sheet Metal Formability in the Stamping with Variable Blank Holder Force, Journal of Materials Processing Technology, Vol. 210, pp. 1378-1385. https://doi.org/10.1016/j.jmatprotec.2010.03.027
  14. Hill, R., 1950, The Mathematical Theory of Plasticity, Oxford, pp. 287-289.
  15. Leu, D.-K., 1997, A Simplified Approach for Evaluating Bendability and Springback in Plastic Bending of Anisotropic Sheet Metals, Journal of Materials Processing Technology, Vol. 66, pp. 9-17. https://doi.org/10.1016/S0924-0136(96)02453-3
  16. Wang, C., Kinzel, G. and Altan, T., 1993, Mathematical Modeling of Plane-Strain Bending of Sheet and Plate, Journal of Materials Processing Technology, Vol. 39, pp. 279-304. https://doi.org/10.1016/0924-0136(93)90164-2
  17. ABAQUS Version 6.10 User's Manual, 2010, Dassault Systems Simulia Corp., Providence, RI, USA.
  18. Seo, Y., Hyun, H.C., Lee, H. and Kim, N., 2011, Forming Limit Diagrams of Zircaloy-4 and Zirlo Sheets for Stamping of Spacer Grids of Nuclear Fuel Rods, Trans. Korean Soc. Mech. Eng. A , Vol. 35, pp. 889-897. https://doi.org/10.3795/KSME-A.2011.35.8.889
  19. Seo, Y., 2011, Sectional Fe Forming Limit Model of Zircaloy-4 and Zirlo Sheet, M.S. Thesis, Sogang University, pp. 66-82.
  20. Wang, J., Kim, N., Lee, H., 2012, Ductile Fracture Model in the Shearing Process of Zircaloy Sheet for Nuclear Fuel Spacer Grids, Metals Materials International, Vol. 18, pp. 303-316. https://doi.org/10.1007/s12540-012-2014-6
  21. Ramazani, A., Abbasi, M., Prahl, U., Bleck, W., 2012, Failure Analysis of DP600 Steel During the Cross-Die Test, Computational Materials Science, Vol. 64, pp. 101-105. https://doi.org/10.1016/j.commatsci.2012.01.031