Fig. 1 Configuration 2-axis bending equipment for blow motor case
Fig. 2 Comparison of mechanical properties, HGI vs. DP780
Fig. 3 True stress – true strain curves for HGI and DP 780
Fig. 4 Diagram for optimization of bending tool geometry
Fig. 5 Secant method for optimization of bending tool geometry(x-axis: diameter of bending tool, y-axis: error in diameter of formed part
Fig. 6 Finite element model for bending analysis
Fig. 8 Error in diameter of formed part for each optimization steps
Fig. 9 Forming test((a) equipment for forming test, (b) formed part)
Fig. 10 Error in diameter and out of roundness (mandrel with elliptical section)
Fig. 11 Error in diameter of formed part (mandrel with circular section vs. with elliptical section)
Fig. 12 Error in out of roundness of formed part (mandrel with circular section vs. with elliptical section)
Fig. 7 Major stress of upper fiber((a) after forming, (b) after springback)
Table 1. Diameters of mandrel(bending tool) for each optimization step(Unit:mm)
Table 2. Error in diameter and out of roundness of formed parts(DP780, 2.0mm thickness, unit:mm)
Table 3. Error in diameter and out of roundness of formed parts(HGI, 2.6mmt, unit:mm)
Table 4. Vertical and horizontal length of mandrel(bending tool) and formed part for each optimization steps(Unit:mm)
참고문헌
- C. H. Cha, S. K. Lee, D. C. Ko, B. M. Kim, "A study on the forming of automotive front side member part with ultra high strength steel of DP980", Transactions of Materials Processing 18(1), pp.39-44 (2009). https://doi.org/10.5228/KSPP.2009.18.1.039
- C. H. Suh, H. D. Shin, Y-C. Jung, C. D. Park, Y. H. Lim, Y. S. Kim, "A study on the forming process of stair type side sill for automobile using DP780", Transactions of Materials Processing 18(8), pp.601-606 (2009). https://doi.org/10.5228/KSPP.2009.18.8.601
- D. C. Ko, J. H. An, M. J. Jang, J. H. Bae, C. H. Kim, B. M. Kim, "Process design of seat rail in automobile by the advanced high strength steel of DP780", Transactions of Materials Processing, 17(3), pp.197-202 (2008). https://doi.org/10.5228/KSPP.2008.17.3.197
- M. K. Choi, H. Huh, "Investigation of springback behavior of DP780 steel sheets after the U-bending process ", Transactions of Materials Processing, 21(6), pp.384-388 (2012). https://doi.org/10.5228/KSTP.2012.21.6.384
- K. H. Kang, S. H. Kim, H. C. Ro, "Change in springback tendency during forming of a hat-type product with high strength steel using a digital servo press", Transactions of Materials Processing, 25(1), pp.21-28 (2016). https://doi.org/10.5228/KSTP.25.1.21
- Gug-Yong Kim, Il-Keun Kwon, Jun-Woo Park, "Study on prediction of mechanical joining strength of blow motor case joint", Journal of The Korean Society of Industry Convergence 20(1), pp.81-87 (2017). https://doi.org/10.21289/KSIC.2017.20.1.081
- Jin-Woo Lee, "Advanced method for an initial pole position estimation of a PMLSM", the transactions of korean institute of power electronics, 10(2), pp.124-129 (2005).