Proceedings of the
9th International Conference of Asian Society for Precision Engineering and Nanotechnology (ASPEN2022)
15 – 18 November 2022, Singapore

Experimental and numerical study on High Speed Impact Trimming(HSIT) process for UHSS sheets

Jae-Hyuk Lim1, Jae-Wook Lee2, Kun-Woo Kim2, Da-Hye Kim2, Soon-Deok Kwon3, Ji-Won Park4,Ho-Jung Lee4 and Eun-Ho Lee1,5,a

1Department of Mechanical Engineering, Sungkyunkwan University, 2066, Seoburo, Jangan-gu, Suwon-si, Gyeonggi-do, Republic of Korea

2Smart Manufacturing Technology R&D Group, Korea Institute of Industrial Technology, Daegu 42994, Republic of Korea

3Gyeongbuk Hybrid Technology Institute, 24-24, Goeyeon 1-gil, Yeongcheon-si, Gyeongsangbuk-do, Republic of Korea

4Mechanical Engineering Department, Samyeon technology, 103, Dalseong2cha 2-ro, Guji-myeon, Dalseong-gun, Daegu, Republic of Korea

5Department of Smart Fab. Technology, Sungkyunkwan University, 2066, Seobu-ro, Jangan-gu, Suwon-si, Gyeonggi-do, Republic of Korea


Ultra-High Strength Steel (UHSS) sheets have been widely used for lightweight structure design because of their high specific strength characteristic in the automobile industry. However, the final stages of the manufacturing process, such as trimming and hole piercing of formed parts, lead to tool damage issues due to a subsequent increase in high yield stress. Conventional mechanical trimming techniques have some problems with UHSS because punch and die wear out and work hardened parts often cannot be trimmed. High-Speed Impact Trimming (HSIT) can be an alternative in this case. The basic principle of the HSIT process is that the high-speed trimming punch can cut off the scrap within a few microseconds leading to adiabatic conditions within the narrow shear band. In this study, the sheared edge quality using the HSIT under large clearance is investigated for CP1180-1.2t steel sheet with numerical and experimental methods. In order to consider the physical effects in numerical condition, Johnson-Cook hardening and damage models were employed so that the strain hardening, rate hardening, and thermal softening is reflected in simulation results. The experimental results show that high punch speed makes straight trimmed edge compared to conventional trimming under the same large clearance. The numerical simulation results also show that the faster punch speed of HSIT causes a deformation mode close to pure shear in the shear band, enabling more effective trimming with a good sheared edge quality.

Keywords: High Speed Impact Trimming(HSIT), Ultra High Strength Steel(UHSS), Adiabatic condition, Shear band, Finite element method, Fracture strain

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