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이현종(H. J. Lee),주병돈(B. D. Joo),박성필(S. P. Park),문영훈(Y. H. Moon) 한국소성가공학회 2010 한국소성가공학회 학술대회 논문집 Vol.2010 No.5
Hot stamping is possible to combine forming and quenching in one process step. This affords the opportunity to manufacture components with complex geometric shapes and high strength. In this study, characteristics of boron steel which is usually using hot stamping process were analyzed. To estimate high temperature properties, hardening test was performed at 900℃ of heating temperature and held for 10minutes, respectively. And then, specimens were given pressure at 700℃. Martensite was observed and Vickers hardness is approximately 450~470HV. The tensile test of press hardened specimens was performed. The tensile strength is more than l500㎫ and elongation is approximately 8%. And also high cycle fatigue test was performed to prove reliability of hot stamping steel and 60 ㎏/㎟ grade hot rolled steel. Experiment were performed until 10? cycles at stress ratio, R=0. High cycle fatigue test was measured from 80% of tensile strength. Fatigue limit of hot stamping steel and hot rolled steel was approximately 460㎫, 370㎫ at peak stress.
냉각채널에 따른 Nozzle 제품의 휨 변형 특성 연구
이현종(H. J. Lee),주병돈(B. D. Joo),김상윤(S. Y. Kim),박성필(S. P. Park),문영배(Y. B. Moon),문영훈(Y. H. Moon) 한국소성가공학회 2011 한국소성가공학회 학술대회 논문집 Vol.2011 No.5
Plastic injection processes comprise injection, packing, cooling, ejection and process/part quality control applications. Plastic injection provides a number of advantages over the weight reduction, assembly simplification and high productivity. In this study FE analysis was performed with MoldFlow2009 to optimize flow characteristic. With optimized conditions, cooling channel was designed and cool analysis was performed. Warpage characteristic at various cooling conditions was analyzed. The results show that warpage can be successfully reduced by appropriate control of cooling channel and cooling temperature.