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[생산기술부문] 박판 스템핑 공정의 주름 발생 예측에 관한 연구
황보원(Bowon Hwang),금영탁(Youngtag Keum) 한국자동차공학회 2000 한국자동차공학회 춘 추계 학술대회 논문집 Vol.- No.-
A wrinkling is the phenomenon of instability influenced by material properties, part geometry, forming conditions, stress state, etc. In this study, the region in biaxial plane stress state is modeled with a rectangular plate introducing the effective dimension, and critical stress values for the wrinkling are calculated using energy method. Prediction index for the wrinkling is then evaluated by normalizing the actual stress with respect to critical stress.
양우열(WooYul Yang),이승열(SeungYeol Lee),금영탁(YoungTag Keum) 한국자동차공학회 2002 한국자동차공학회 Symposium Vol.2002 No.11
In this study, the methodology to design initial blanks considering the reduction of both springback and flange trimming amounts is introduced. First, the dimensional forming analysis of a trial blank is carried out tsing FEM program and the tentative initial blank shape is determined by cutting the outer edge of the trial blank whose shape is nearly matched with the trimming line. During the shaping the blank edge, the movement of blank outer line is described with a random variables to reduce the sensitivity of initial blank geometry. Next, after performing 2-D FEM forming and springback simulations for the selected sections and optimizing the trimming and springback amounts in terms of section length of the blank, the initial blank is determined. The springback of the initial blank determined by following the proposed method in a stepped s-rail die is tremendously reduced.
양우열(WooYul Yang),이승열(Seung Yeol Lee),금영탁(YoungTag keum),황진영(JinYoung Hwang),윤치상(ChiSang Yoon),신철수(ChirlSoo Shin),조원석(WonSuk Cho) 한국자동차공학회 2002 한국자동차공학회 Symposium Vol.2002 No.11
In order to develope springback reduction technology for high-strength steel sheets, 3 studies have been conducted: dome stretching tests, stepped s-rail forming and springback measurement, and optimally shaped initial blank design. First, to find out the formability of TRIP60, dome stretching test was performed. Next, the stepped s-rail die, which was designed to form a channel type panel with large twist and wall curl, was manufactured and used to know the effect of controlling forming variables, such as blank holding force and flange amount on the springback. Furthermore, new measurement technology of the springback was introduced to define wall curl and twist in geometrically complex panels. Finally, the optimally shaped initial blank was employed to verify one of the best ways to reduce the springback in chanel type, high strength sheet panels.