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FEM 을 이용한 주조금형의 (鑄造金型) 탄소성 (彈塑性) 열응력 (熱應力) 및 열변형 해석
김옥삼,구본권,민수홍 ( Ok Sam Kim,Bon Kwon Koo,Soo Hong Min ) 한국주조공학회 1993 한국주조공학회지 Vol.13 No.1
N/A It is well-known that the analysis of elasto-plastic thermal stress and deformation are substantially important in optimal design of metal casting mould. The unsteady state thermal stress and deformation generated during the solidification process of ingot and mould have been analyzed by two dimensional thermal elasto-plastic theories. Distributions of temperature, stress and relative displacement of the mould are calculated by the finite element method and compared with experimental results. In the elasto-plastic thermal stress analysis, compressive stress occurred at the inside wall of the mould whereas tensile stress occurred at outside wall. A coincidence between the analytical and experimental results is found to be fairly good, showing that the proposed analytical method is reliable.
민수홍,구본권,김옥삼 ( Soo Hong Min,Bon Kwon Koo,Ok Sam Kim ) 한국주조공학회 1991 한국주조공학회지 Vol.11 No.3
N/A It is known that the analysis of thermal stresses is substantially important in optimal design of casting mould. In this paper unsteady state thermal stresses generated in ingot and mould during the solidification process are analyzed by the two dimensional thermal elasto-plastic analysis. Distribution of temperature and stress of the mould is calculated using the finite element method and compared with experimental result. The significant results obtained in this study are as follows. At the early stage of the casting process, abrupt temperature change was shown in the vicinity of the inner surface of the mould. The largest temperature gradient is occurred at the corner of the mould. In the thermal stress analysis, compressible stress occurred in the inside wall of the mould where as tensile stress on outside wall. Smaller thermal stress is observed at the rounded corner. It is also observed that the shown is influenced by the thickness of the wall. A fairly good coincidence is found between analytical and experimental results, showing that the proposed analytical methodology is reliable.
Quenching과정에서 상변태를 고려한 탄소성 열으역의 유한요소해석(1) - 오스테나이트에서 퍼얼라이트의 변태 -
김옥삼,구본권 ( Ok Sam Kim,Bon Kwon Koo ) 한국열처리공학회 1994 熱處理工學會誌 Vol.7 No.4
Constitutive relation of thermoelasto-plastic material undergoing phase transformation during quenching process were developed on the basic of continuum thermodynamics. The metallic structure, temperature and residual stresses distributions were numerically calculated by the finite element technique. The metallic structure were defined by transformation from austenite to pearlite and characterized as a fuction of thermal history and mixture rule of phase. On the distribution of thermal stress along the radial direction, axial and tangential stresses are compressive in the surface, and tential in the inner part. Radial stress is tensile in the whole body. The reversion of residual stress takes plase at 11.5∼15.5㎜ from the center.
탄소강의 Quenching처리 과정에서 변형율이력을 고려한 탄소성열응력의 유한요소 해석 (2) -탄점소성 열응력 해석-
김옥삼,구본권 ( Ok Sam Kim,Bon Kwon Koo ) 한국열처리공학회 1996 熱處理工學會誌 Vol.9 No.2
The aero-industry in union industry which includes a research development type, a knowledge accumulation type and a developed country type. The aero-industry of Korea is in semi-developed type stage but departed later than that of other country such as Taiwan, Indonesia etc. Therefore, the necessity of domestic airplane material is required. This study on 7050Al extruded alloy aims to suggest an adequate heat treatment conditions of T73, T74 and T76. The results of this study show that: 1. The optimum conditions of T7x heat treatment in extruded 7050Al alloy show this; T73 : 121℃×7hr+177℃×14hr T74 : 121℃×7hr+177℃×10hr T76 : 121℃×7hr+163℃×21hr 2. The 2nd step aging heat treatment such as T73, T74 and T76 etc. is effective in 7050Al alloy but the variation otf microstructure and mechanical property with dispersive inclusions produced for extrusion process causes some troubles. Accordingly, in order to produce a good 7050Al alloy, a careful attention is needed in manufacturing process.
민수홍,김옥삼,구본권 ( Soo Hong Min,Ok Sam Kim,Bon Kwan Koo ) 한국주조공학회 1991 한국주조공학회지 Vol.11 No.1
N/A The process of solidification of metal is accompanied by liquid-solid change and known as Stefan`s heat conduction problem on the moving boundary. In this study the temperature distribution in ingot and metallic mould during casting was analyzed by the two dimensional heat conduction theory. The transient temperature distribution was numerically calculated using a finite element method on the nodal point of mesh screen representing ingot and mould cross section. The theory was applied on the casting of aluminum(purity ; 99%) in flat ingot mould of GC25. The analysis will make it possible to calculate an optimum mould shape of which temperature gradient becomes minimum.
탄소강의 담금질 처리과정에서 변형율이력을 고려한 탄소성열응력의 유한요소 해석(1) - 온도분포의 해석 -
김옥삼,조의일,구본권 ( Ok Sam Kim,Eui Il Cho,Bon Kwon Koo ) 한국열처리공학회 1995 熱處理工學會誌 Vol.8 No.3
Temperature distribution, transformation and residual stresses generated during the quenching process of carbon steel. It follows many difficulties in the analytical considerations on those quenching process because of the coupling effects on temperature and metallic structures. In this paper one of the basic study on the quenching stresses was carried out for the case of the round steel bar specimen(SM45C) with 40㎜ both in its diameter and length. The temperature distributions considering strain hysteresis were numerically calculated by finite element technique. In calculating the transient temperature field, the heat flux between water and rod surface was determined from the heat transfer coefficient. The gradient of temperature is almost same to geometric of specimen. At early stage of the quenching process, the abrupt temperature gradient has been shown in the surface of the specimen.
금형의 자동 계측시스템을 위한 측정 모듈설계 및 시뮬레이션 소프트웨어 개발
김옥삼,구본권 한국공작기계학회 2001 한국생산제조학회지 Vol.10 No.5
On-machine automatic measuring system of Numerically control(NC) machines permit computer control of basic material cutting processes of moulds. A part of mould designed within a CAD/CAM system can be manufactured by generation of tool paths by the measuring systems. Since the three-dimensional geometry by AutoCAD of the part is contained in the data base, the manufacturing specialist, combined with the appropriate software simulation, can not only create the commands to drive the virtual measuring and standardization of measuring modules but also can check for mistakes by viewing the computer graphics simulation of the tool cutting sequence.
具本權,金鈺三 서울産業大學校 1990 논문집 Vol.32 No.1
In this study the temperature distribution originated in ingot mould during solidification of ingot in contact was analyzed by the two dimensional heat conduction theory. The transient temperature distribution was numerically calculated using a finite element method on the nodal points of mesh screen representating ingot and mould cross section. It was applied on the casting process aluminum (purity; 99.98%) and flat ingot mould, GC25. The above analysis has made it possible to calculate the thermal stresses of mould and derive an optimum mould shape.
具本權,金鈺三 서울産業大學校 1990 논문집 Vol.32 No.1
In this study thermal stresses originated in ingot mould during solidification of metal were analyzed by the two dimensional thermo elasto-plastic theory. The transient temperature distribution was obtained on the nodal points of mesh screen representation the cross section of ingot an mould. Thermal stresses and temperature distribution were calculated by the finite element method, where the imaginary division of mould as a continum into a finite number of elements in a common procedure and each of them satisfies the compatibility and equilibrium conditions. It was applied in the casting process of pure aluminum in flat ingot mould of GC25. The above analysis has made it possible to obtain an optimum mould shape.