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금형 재질과 표면 처리 조건이 1.2GPa급 강판의 전단 가공에서 전단면 특성에 미치는 영향
차승훈(S. H. Cha),서판기(P. K. Seo),남재두(J. D. Nam),안민수(M. S. Ahn),원광우(K. W. Won) 한국소성가공학회 2013 한국소성가공학회 학술대회 논문집 Vol.2013 No.10
In order to reduce the weight and improve the crash performance of the vehicle, advanced high strength steel of DP980 and CP1180 have widely used in the automotive industry. However, the high strength steel in the press parts causes severe tool wear or failures, such as adhesion, chipping and fracture at the tool cutting area during the shearing process. These result in the excess burr which deteriorates the tool life and causes serious problem in the product quality. The objective of this study is to evaluate the effect of the characteristic of sheared surface on the die material and surface treatment conditions at the shearing process with 1.2GPa steel grade. The characteristics of sheared surface were evaluated after shearing experiment of 60,000 strokes. A burr height was measured using the illuminance meter. Also, tool wear or failures was analyzed through observing microstructure.
남재두(J. D. Nam),안민수(M. S. Ahn),차승훈(S. H. Cha),서판기(P. K. Seo),원광우(K. W. Won),이영민(Y. M. Lee),박광수(K. S. Park),배충수(C. S. Bae) 한국소성가공학회 2013 한국소성가공학회 학술대회 논문집 Vol.2013 No.10
According to current development trends for automotive body parts, light weight is a key issue in improving fuel efficiency and CO₂ reduction. Compared to steel and aluminum, magnesium has a relatively low specific gravity. However, it is challenging to use magnesium to produce a product at room temperature because magnesium has a Hexagonal Close-Packed (HCP) crystal structure. Therefore, the structure is not suitable for plastic deformation without using a heating system. So, we suggest the use of a Diamond-Like Carbon (DLC) coating when developing a magnesium sheet forming process. This coating can improve formability and the work environment by increasing the surface roughness. This study compared dies and product before and after DLC coating at same tryout conditions.
금형 소재별 열전도도에 따른 루프사이드 금형의 냉각 성능 평가
차승훈(S. H. Cha),서판기(P. K. Seo),남재두(J. D. Nam),안민수(M. S. Ahn),원광우(K. W. Won) 한국소성가공학회 2014 한국소성가공학회 학술대회 논문집 Vol.2014 No.5
In order to reduce the weight and improve safety performance of automotive, AHSS (advanced high strength steel) has widely used in automotive industry. But AHSS is difficult to manufacture the press die due to low formability and excessive spring-back. Hot stamping process is strong point to be excellent formability and reduce spring-back due to hot forming. However this is required to be cooling channel into press die. So this is weakness to be poor productivity. Therefore this is needed to improve the cooling performance which is to be proper design of cooling channel and to develop the tool steel of a high thermal conductivity. This study introduced the developed tool steel of a high thermal conductivity. The cooling performance of roof side die was evaluated according to the thermal conductivity of tool steels. The cooling analysis used the FloEFD of CFD (Computational Fluid Dynamics) software.