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블랭크 홀딩력 조절을 통한 성형성 향상에 관한 수치적 연구
최현석,정완진,Choi, Hyun-Seok,Chung, Wan-jin 한국금형공학회 2016 한국금형공학회지 Vol.10 No.1
In sheet metal forming process, drawing is typical process. And the key factor of drawing is blank holding force (BHF) A low BHF can cause wrinkling, whereas a high BHF can cause fracture during a deep drawing process. Thus, formability can be influenced by application appropriate BHF. In this study, a variable blank holding force (VBHF) is applied to extend the forming limit by avoiding both wrinkling and fracture. To determine VBHF in drawing process, numerical simulations and statistical analysis are carried out using commercial FEM software.
피라미드 코어를 가진 샌드위치 판재의 L형 굽힘 성형해석
임성진 ( Sung Jin Lim ),김종호 ( Jong Ho Kim ),정완진 ( Wan Jin Chung ) 한국고무학회 2009 엘라스토머 및 콤포지트 Vol.44 No.4
본 연구에서는 피라미드 형상의 코어재를 갖는 복합판재의 성형해석을 위한 축약모델의 사용이 제안되었다. L형 굽힘성형에 대하여 유한요소해석에 의한 해석을 수행하여 제안된 축약모델의 정확성과 유효성이 검증되었다. 성형해석의 정확성을 향상하기 위하여 코어의 보다 상세한 모델링과 코어성형에 의한 가공경화의 고려가 수행되었다. 변형형상과 성형하중곡선에 대하여 비교하였으며 실험과 좋은 일치를 보였다. 힘-하중 곡선의 비교에서 본 해석이 좌굴후변형거동을 잘 예측할 수 있음을 보였다. In this study, the use of a condensed model is proposed for the simulation of forming of sandwich sheet with pyramid core. A corresponding finite element analysis for L-type bending is carried out to prove the accuracy and the effectiveness. In order to improve the accuracy of forming analysis, more precise modeling of core shape and consideration of work-hardening of previous core forming are carried out. Simulation results are compared with those of experiment. Deformation shape and post-buckling behavior by simulation are in good agreement with those of experiment for the considerable range of deformation. From the comparison of force-displacement curve, it is shown that the proposed model shows good prediction of post-buckling behavior.
국내개발 Lagrangian, Eulerian 및 ALE Hydrocode 기법 비교
이민형(Minhyung Lee),정완진(Wan-Jin Chung) 대한기계학회 2006 대한기계학회 춘추학술대회 Vol.2006 No.3
A new hydrocode which is still under development using Lagrangian, Eulerian and arbitrary Lagrangian-Eulerian operators, has been described. The three operators are implemented into a single framework by incorporating the sequential three stages of Lagrangian, remesh and remap stages. Several numerical schemes used for each operator are discussed briefly in this paper. In order to evaluate the characteristics of each operator, the Taylor Impact Test has been simulated using each operator and the results are compared. Currently the code is 1st order accuracy in the material interface tracking algorithm and can not handle multimaterial in the mixed cell. The areas of possible enhancement of the code are also provided.
박춘달(Chun Dal Park),정완진(Wan Jin Chung),김병민(Byung Min Kim) Korean Society for Precision Engineering 2006 한국정밀공학회지 Vol.23 No.9
Surface deflections have a great effect on the external appearance of automobiles. Usually, they are occurred on large flat panels containing sudden shape changes and of very small size about ±30-300㎛. Since the current numerical method is not sufficient for predicting these defects, the correction of these defects still depends on trial and error, which requires a great deal of time and expense. Consequently, developing the numerical method to predict and prevent these defects is very important for improving cosmetic surface qualities. In this study, an evaluation system that can analyze surface deflections using numerical simulation and a visualization system are reported. To calculate the surface deflections numerically, robust algorithms and simulation methodologies are suggested and to visualize them quantitatively, the curvature variation algorithm is proposed. To verify the developed systems, the experimental die of the handle portion of exterior door is analyzed. The results showed that the experimental and simulational visualization are in good agreement. Compensation methods to correct the surface deflections are also tested. The evaluation system proposed in this paper could be used to predict and minimize the occurrence of surface deflections in die manufacturing.
김영천,심응철,이현상,홍용수,정완진,Kim, Young-Cheon,Sim, Eung-Chul,Lee, Hyun-Sang,Hong, Yong-Soo,Chung, Wan-Jin 한국금형공학회 2012 한국금형공학회지 Vol.6 No.2
In April 2010, the die and mould grand prix for university student was held in Osaka as a special event of Inter Mold Japan. The students from Korea, China, and Japan participated to demonstrate the design and manufacturing skill of die and mould. Based on the given product drawing of Test Work, progressive die should be designed and manufactured. Also, production of Test Work should be carried out. This study had been conducted to participate in the grand prix and to learn practical knowledge and experience from real die design and making. Test Work is made of SPCC and includes piercing, blanking, deep drawing and burring. From the analysis of product drawing, process planning and die design was carried out. Progressive die for Test Work was manufactured using CNC milling, grinding, wire-cutting and polishing. The production was successfully completed using mechanical press and product showed very good accuracy satisfying all dimensional tolerances.
이성근,정진오,김승규,정완진,Lee, Sung-Geun,Jung, Jin-Oh,Kim, Seung-Kyu,Chung, Wan-Jin 한국금형공학회 2012 한국금형공학회지 Vol.6 No.1
In the manufacturing of a LCD TV bottom chassis, the distortion after forming should be suppressed below pre-defined amount to avoid contact with electric components. Finite element analysis procedure of forming and springback of a LCD TV bottom chassis is developed to investigate the distortion behaviour. It is shown that after the first forming large distortion occur due to uneven metal flow induced by various embossings. In the second forming, distortion is decreased by introducing bead that absorbs the excessive metal flow. It is proved that analysis method could describe these behaviour effectively. The developed analysis method can be used to find the proper location and shape of bead more quickly and effectively.