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유압프레스의 파워 곡선을 고려한 열간 단조 공정의 하중 예측
송민철(M. C. Song),권일근(I. K. Kwon),유지훈(J. H. Yoo),문영훈(Y. H. Moon) 한국소성가공학회 2013 한국소성가공학회 학술대회 논문집 Vol.2013 No.5
The purpose of this study is to predict quantitatively the forging load of a large forged product using the power curve of hydraulic press. In previous forging analysis, it has been assumed that the die speed is constant during the forging process. However the die speed of hydraulic press is actually defined with the power curve, the relationship between die speed and press load. The change of strain rate having a direct relationship with the die speed affects the forging load. So it is necessary to consider the power curve to predict the forging load. In this study,the power curve was determined by measuring the die speed and press load through the several shop tests. According to FE analysis results, the forging analysis result with the variable die speed by the power curve had a good agreement with a measured final forging load within about 5% deviation, whereas the forging analysis with constant die speed overestimated the measured final forging load about 20%.
송민철(M. C. Song),이용욱(Y. U. Lee),문영훈(Y. H. Moon) 한국소성가공학회 2015 한국소성가공학회 학술대회 논문집 Vol.2015 No.5
The core process in the open die forging for a large crank throw is to bend the preform into the “V” shape blank. The preform could be bended asymmetrically due to its asymmetrical shape, uneven temperature distribution and the misalignment between preform and die. Since the asymmetrically bended blank is very difficult to correct, the proper control method shall be required to prevent it. The purpose of this study is to develop the asymmetry control method in the bending process of preform. Numerical simulation results show that the principal factor controlling asymmetrical forged product is identified as the uneven configuration of preform. The floating die was applied to the bending device to control the asymmetry of preform during bending. The validity of he suggested method was verified by the lab scale experiments.
송민철(M. C. Song),박덕수(D. S. Park),이명규(M. G. Lee),이광학(K. H. Lee) 한국소성가공학회 2009 한국소성가공학회 학술대회 논문집 Vol.2009 No.10
The TR forging is a kind of continuous grain flow forging. The preform of crank shaft for TR forging process was a round bar with a ring groove. In the first stage, the preform was partly heated by induction heating and then forged by vertical and horizontal force in sequence. In this study, the simulation process of induction heating was proposed to evaluate the temperature distribution of preform for TR forging. The equivalent circuit method was adopted to fine coil current of the preform with a various dimensions and power levels. With these results, the coupled electromagnetic and transient thermal analysis for induction heating was performed to evaluate the temperature distribution at the preform of crank shaft during induction heating process. This FE analysis technique with equivalent circuit method was verified by comparing the analysis results with the experimental results.