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반경단조 공법을 이용한 사각봉재 제조공정의 최적 금형설계
장성민(S. M. Jang),김홍태(H. T. Kim),장시진(S. J. Jang),전만수(M. S. Joun),문호근(H. K. Moon) 한국소성가공학회 2012 한국소성가공학회 학술대회 논문집 Vol.2012 No.5
In conventional open die forging press, the material is formed by up and down motion of punch and thus the longitudinal elongation per stroke is relatively small, resulting in long manufacturing time. In addition, the center of material is exposed to decisive defects generated during cogging due to Mannesmann’s effect, that is, repeated deformation in compression after tension. To the contrary, four punches or dies in radial forging press the material in four perpendicular directions at the same time, which results in better quality as well as short manufacturing time. In the paper, the manufacturing process of a square bar using radial forging press is simulated to optimize die design and a set of optimized dies are given
대형 축의 자유단조에서 기공압착 관점에서 일반 프레스와 회전단조 프레스의 비교 연구
장성민(S. M. Jang),엄재근(J. G. Eom),김성현(S. H. Kim),이민철(M. C. Lee),전만수(M.S.Joun) 한국소성가공학회 2010 한국소성가공학회 학술대회 논문집 Vol.2010 No.5
We propose an analysis model of simulating the detailed procedure of pore closing in free forging of large shafts. In the analysis model, an artificial symmetric plane is used, on which initial pores are initially located to be traced. The analysis model is employed to carry out three-dimensional simulation of pore closing in shaft free forging by both conventional free forging press and radial forging machine. With this result, two typical types of free forging equipment for manufacture of large shafts are compared in detail. It has shown that the radial forging machine is much superior to the conventional free forging press especially in pore closing under high hydrostatic pressure with sound strain.
대형크랭크샤프트 해머단조공정의 시뮬레이션 및 실험적 검증
장성민(S. M. Jang),김성현(S. H. Kim),이민철(M. C. Lee),제갈영진(Y. J. Jegal),박태현(T. H. Park),조범제(B. J. Cho),전만수(M. S. Joun) 한국소성가공학회 2010 한국소성가공학회 학술대회 논문집 Vol.2010 No.5
In this paper, non-isothermal analysis of hammer forging process for a large crankshaft is conducted. A simple and computationally efficient approach to non-isothermal three-dimensional hot forging simulation, theoretically based on a rigid-thermoviscoplastic finite element method, is employed. In the approach, it is assumed that the temperatures of dies are increased at the same ratio as the workpiece temperature decreases. Hot forging of a large crankshaft is simulated using AFDEX 3D and the simulated result is compared with the actually forged one in detail. It has been verified that the predictions are in good agreement with the experiments. The successful simulation and development of a large crankshaft by the hammer forging technology will contribute to opening a new area of hammer forging application and to enhancing competitiveness of national machinery industries especially including ship part industries.
스프링 힘에 의한 배압부가 단조 공정의 3차원 유한요소해석
장성민(S. M. Jang),김민철(M. C. Kim),이민철(M. C. Lee),전병윤(B. Y. Jun),전만수(M. S. Joun) 한국소성가공학회 2009 한국소성가공학회 학술대회 논문집 Vol.2009 No.10
In this paper, back pressure forging processes of which back pressure are exerted by mechanical forces including spring reaction are simulated by three-dimensional finite element method. The basic three-dimensional approach extended from two-dimensional approach is accounted for. An axisymmetric backward and forward extrusion process having a back pressing die, which is exposed to oscillation of forming load due to variation of reduction ratios with stroke and its related frequent variation of major deforming region, is simulated by both two and three dimensional approaches to justify the presented approach by their comparison. A three-dimensional forging process having a back pressing die attached to the punch by a mechanical spring is simulated and the results are investigated to reveal accuracy of the presented approach.
유한요소법을 이용한 해머단조 공정에서 타격 횟수의 결정
장성민(S. M. Jang),김성현(S. H. Kim),이민철(M. C. Lee),조범제(B. J. Cho),전만수(M. S. Joun) 한국소성가공학회 2009 한국소성가공학회 학술대회 논문집 Vol.2009 No.10
In this paper, three-dimensional finite element approach to determining the number of blows in hammer forging is presented. Energy efficiency which is a major factor affecting the number of blows in hammer forging is assumed to decrease linearly as die-material contact area increases. The approach is applied to predicting the number of blows in counterblow hammer forging of large crank shaft for medium sized ship engine.
한승상(S. S. Han),엄재근(J. G. Eom),장성민(S. M. Jang),이민철(M. C. Lee),전만수(M. S. Joun),강신준(S. J. Kang),손요헌(Y. H. Son) 한국소성가공학회 2009 한국소성가공학회 학술대회 논문집 Vol.2009 No.5
In this paper, limitation of rigid-plastic finite element method caused from rigid-plasticity assumption and numerical problem is investigated in detail and a useful scheme is proposed to get rid of the plastic deformation in rigid or elastic region, A typical example of a possible long bar extrusion process is given, which may be impossible to simulate without using the proposed scheme. The scheme is successfully applied to simulating the long bolt forging process.
원웨이 클러치 베어링 외륜의 열간과 냉간 복합단조 공정 기술 개발
장수진(S. J. Jang),전병윤(B. Y. Jun),장성민(S. M. Jang),전만수(M. S. Joun),문호근(H. K. Moon),성현석(H. S. Sung),허민호(M. H. Heo) 한국소성가공학회 2009 한국소성가공학회 학술대회 논문집 Vol.2009 No.5
In this research, a hot and cold combined forging process for manufacturing net-shape one-way clutch bearing outer race of an automobile automatic transmission unit is developed. The process is composed of hot forging for manufacturing an optimized gear-like perform and precision cold forging for sizing the perform into final net-shape product. Finite element simulation techniques are applied to find the optimized process designs including blank and die shapes. The predictions and experiments are compared, revealing that they are in good agreement with each other. The dimensional test showed that the important dimensional requirements on gear tooth-like shape of the forged product were fulfilled.