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최병근(Byungkeun Choi),손현성(Hyunsung Son),김홍기(Honggee Kim) 한국자동차공학회 2009 한국자동차공학회 학술대회 및 전시회 Vol.2009 No.11
Hot Press Forming (HPF) process with which automotive product is formed at elevated temperature and cooled down in the tool to get the ultra-high strength has been applied to improve weight reduction and crash performance. AlSi coated material for HPF process is widely used to prevent oxidation of substrate during heating in the furnace and transport to the press in the air. This study observed surface color of the AlSi coated sheet with heating condition and analyzed the characteristics of AlSi coated layer. As heating time gets longer, surface color after cooling was changed from gray to blue. The coated layer has a thickness over 35㎛ after heating and reaction between coated material and substrate results in a specific alloy composition along with coated layer. Finally, pick-up of AlSi coated layer on the tool was observed and elimination of pick-up is one of the factors that stop the process and increase maintenance costs for the serial process.
유한요소해석을 이용한 열간프레스성형 적용 로어 컨트롤 암의 성형품질 조건 최적설계
손현성(Hyunsung Son),김홍기(Honggee Kim),최병근(Byungkeun Choi) 한국자동차공학회 2009 한국자동차공학회 학술대회 및 전시회 Vol.2009 No.11
Hot-Press-Forming (HPF), an advanced sheet forming method in which a high strength part can be produced by forming at high temperature and rapid cooling in dies, is one of the most successful forming process in producing components with complex geometric shape, high strength and a minimum of springback. The thermo-mechanical coupled analysis for a hot-press-formed lower arm is performed by using the commercial program, LS-Dyna. To optimize conditions of forming quality in HPF process and secure a safe product without any failures, such as fractures and wrinkling, the simulations are coupled with Taguchi’s orthogonal array experiment. Three design and process variables―the friction coefficient, blank shape, and hole location for burring―are selected to be optimized. The most effective condition of forming quality for a hot-press-formed lower arm is suggested. The simulation results are confirmed with experimental ones.