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유한요소법을 이용한 가변 스트레치 성형공정의 적합성 검증
서영호(Y. H. Seo),허성찬(S. C. Heo),박중원(J. W. Park),송우진(W. J. Song),구태완(T. W. Ku),김정(J. Kim),강범수(B. S. Kang) 한국소성가공학회 2009 한국소성가공학회 학술대회 논문집 Vol.2009 No.10
This paper deals with a usefulness verification of stretch forming process using flexible die. The stretch forming method is widely used in aircraft and high-speed train industries for manufacturing of skin structure, which is made of sheet metal. A great number of solid dies are originally used and developed for specific shapes with respect to different curvature radii of the skin structures. Accordingly, flexible stretch forming process is proposed in this study. It replaces the conventional solid dies with a set of height adjustable discrete punches. A usefulness of the flexible die is verified through extensive numerical simulations of the stretch forming process for simply curved sheet plate. The elastic recovery in considered and formability evaluations are conducted through a comparison of symmetry plane configurations.
박중원(J. W. Park),구태완(T. W. Ku),강범수(B. S. Kang) 한국소성가공학회 2010 한국소성가공학회 학술대회 논문집 Vol.2010 No.10
Piercing in sheet metal forming process is widely adopted to manufacture a specified and precise nozzle used for ink-jet printer and fuel injection component, and so forth, in various industrial fields. Until present, the piercing process by using shear deformation has been focused on the hole manufacturing in the thickness direction of thin sheet material as a perpendicular one, and many researches have been reported. In this study, a specific angled piercing process has been introduced to obtain the precisely angled piercing hole from a thin sheet material of SUS304, which is the initial thickness of 0.2㎜. In the fuel injection nozzle, the angled piercing holes are required as non-axisymmetric positioned 4-piercing holes on one component, and each micro hole has the slope angle of 19.5°. To develop the manufacturing technology of mentioned component, firstly, finite element analysis is carried out by using DEFORM. In this study, the finite element method combined with the ductile fracture criteria is also conducted. Formability of the micro hole is investigated with regard to the shear surface of the micro hole, and the systematic comparison between the numerical simulation and the experimental result is carried out.
하성찬(S. C. Heo),서영호(Y. H. Seo),박중원(J. W. Park),구태완(T. W. Ku),송우진(W. J. Song),김정(J. Kim),강범수(B. S. Kang) 한국소성가공학회 2009 한국소성가공학회 학술대회 논문집 Vol.2009 No.10
Flexible forming process for sheet metal using reconfigurable die is introduced based on numerical simulation. Numerical simulation of sheet metal forming process is carried out by using flexible dies model instead of conventional matched die set. Elastic cushion which has high resilience behavior from excessive deformation are inserted between forming punches and blank material for smoothing the forming surface which has discrete due to characteristics of the flexile die. As an elastic cushion, urethane pads are utilized using hyperelastic material model in the simulation. Formability in view of surface defect such as onset of dimple is compared with regard to various punch sizes. Consequently, it is confirmed that the flexible forming process for sheet material has appropriate capability and feasibility for manufacturing of smoothly curved surface instead of conventional die forming process.
Knife Press Forming 공정의 후육관 성형성 예측
박중원(J. W. Park),노학곤(H. G. Noh),구태완(T. W. Ku),강범수(B. S. Kang) 한국소성가공학회 2009 한국소성가공학회 학술대회 논문집 Vol.2009 No.10
Roll bending process has been used for manufacturing the pipes. However, it is not suitable process for the thick pipes. Knife press forming is acceptable process for thick pipes. Recently, the knife press forming process using brake bending press have been performed. In this study, the estimation on formability of knife press forming process for the thick pipes is carried out. From the results, it is ensured that the thick pipes could be obtained by the knife press forming process.