• Proceedings of the Korean Society of Precision Engineering Conference
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• 2003.06a
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• pp.414-417
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• 2003

A copper-clad aluminium composite bar is lighter and less expressive than a commercial copper alloy bar. Copper-clad aluminium composite bar can be fabricated by hot hydrostatic extrusion process. In this work, the effect of die angle on the compressive properties of copper-clad aluminium composites fabricated using hydrostatic extrusion process was investigated experimentally. The results showed that optimum half die angle was in the range of 40$^{\circ}$ to 50$^{\circ}$ for an extrusion ratio of 19. The results also showed that the half die angle had little influence on the compressive strength of copper-clad aluminium composites. A diffusion layer increased with increasing die angle.

• Journal of the Korean Society for Precision Engineering
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• v.21 no.7
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• pp.179-184
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• 2004

In this work, a copper-clad aluminum composite was fabricated using hot hydrostatic extrusion with various extrusion ratios (8.5, 19, 49) and semi-die angles (30, 45, 60 degree) at a temperature of 32$0^{\circ}C$, Material characteristics of copper-clad aluminum composites were determined from compression tests and hardness tests The results showed that for ER of 8.5, the optimum semi-die angle was below or equal to 30 degree and a pressure drop was about 31%. For ER of 19, the optimum semi-die angle was in the range of 40 to 50 degree and a pressure drop was about 38%. In the case of ER=49, the optimum semi-die angle was above or equal to 60 degree and a pressure drop was about 36%. Compressive yield strength was maximum for ER of 8.5 and semi-die angle of 30 degree and the value of maximum was 155 MPa. Uniform hardness distribution was obtained as the extrusion ratio increases and the semi-die angle decreases. In the case of ER=8.5 and semi-die angle of 30 degree, the lowest extrusion pressure and the maximum compressive yield strength was obtained. Therefor, it was concluded that the optimum extrusion condition for fabricated copper-clad aluminum composites under hydrostatic pressure environment was ER of 19 and semi-die angle of 30 degree.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 1999.03b
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• pp.77-81
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• 1999

The predictions of metal flow forging load optimal die angle and preform size are not so easy in turbine blade forging. First of all the quality of final product is influenced by side force which is one of the significant factors. in this study slab method is applied to determine optimal die angle minimizing side force and the position of preform Finally drawing of die design is obtained in optimal die angle with developing tool that is composed of Visual Basic.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2002.11a
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• pp.23-32
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• 2002

The torsional forward extrusion is the process that is executed by punch travel and die rotation. The advantages of having the die rotation on this process are that forming load can be reduced and optimal die angle can be increased. This provides a possibility to extrude cold-worded material where a large extrusion force and die angle are required. Also, this process can improve the material properties owing to the high deformation and uniform strain distribution. The forming load and optimal die angle of this process are determined by the upper bound analysis using stream function and the optimization technique. To verify the theoretical result, we have carried out experiments and FE simulations using DEFORM3D.

• Transactions of Materials Processing
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• v.14 no.5 s.77
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• pp.444-451
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• 2005

A new extrusion process of the circular section product with helical fins could be developed by rotating extrusion die. The twisting of extruded product is caused by the twisted conical die surface connecting the die entrance section and the die exit section linearly. But, until now, because the process has used fixed extrusion die, it needs high pressure in order to twist billet and form fin shape on the surface of billet. So, during extruding billet, in order not to twist billet, the extrusion die is needed to rotate itself instead of twisting of billet. It is known that it is possible to reduce extrusion load of product with helical fins by analysis and experiments using rotating die. And it is known that, through the extrusion load analysis by $DEFORM^{TM}-3D$ software, optimal rotational velocity of rotating die can be obtained according to reduction ratio of area and twisted angle of die. And experiments and analysis using rotating extrusion die show that the twisted angle of product can be controlled by twisted angle of extrusion helical die and the rotational velocity of extrusion helical die.

• Transactions of Materials Processing
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• v.19 no.2
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• pp.132-137
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• 2010

In the multi-pass shape drawing process, the appropriate process design is very important to produce sound products. The reduction ratio, die angle, and the intermediate die shape are very important process variable of the multi-pass shape drawing. The aim of this study is the determination of the reduction ratio, die angle, and the intermediate die shape of the 2 pass shape drawing process for producing steering spline shaft. In this study, FE analysis, Taguchi method, and ANN(artificial neural network) were applied to determine the appropriate reduction ratio, die angle, and intermediate die shape. After the determination of the process variables, FE analysis and drawing experiment were performed to evaluate the effectiveness of the determined process variables. The dimensional accuracy of the final drawn spline shaft was evaluated by using 3D surface profiler and 3D laser digitizing system.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2002.10a
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• pp.329-332
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• 2002

The upper bound analysis by stream function is used to study the torsional forward extrusion. The torsional forward extrusion process not only reduces forming load but also increase optimal die angle. Optimal die angle is determined by the optimization technique. The advantages of this process are that the low capacity of pressing machine can be used and the process with a large die angle can be applied. To verify the theoretical result, we have carried out experiments using model material (plasticine) and FE simulations using DEFORM3D.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2005.10a
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• pp.834-837
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• 2005

This study presents a study on the influence of process parameters(semi-die angle, die reduction, friction condition, and bearing length) in drawn wire on residual stresses were investigated using FE-analysis. In this study, semi-die angle and die reduction have a significant effect on the residual stresses at the surface of drawn wire. In the previous study, in order to reduce the residual stresses, several methods were suggested: addition of axial tension, application of skin pass, straightening in multi-roll straightener etc. In this study, it can be known that the concurrent application of skin pass with low die reduction and low semi-die angle at the final stage of drawing operation reduces dramatically the both axial and hoop residual stresses after drawing.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2003.05a
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• pp.221-224
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• 2003

In the open die forging process, it is difficult to optimize process parameters such as die shape, initial ingot size, feeding pitch, rotation angle and other process parameters in the operational environments. Therefore in this study, 3D finite element analysis has been performed to obtain optimal process condition for open die forging process. FEM analyses at various feeding pitches and rotation angles provide process conditions to make round bar having precise dimensional accuracy.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2000.04a
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• pp.101-105
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• 2000

In cold forging die the shrink fitting is generally used to decrease stress and increase die life. In this paper we have studied about the effect of fitting type, When the die insert is splitted into several pieces the maximum stress could be decreased as much as 50~70% The fitting angle could be selected to minimize the maximum stress and the variation of stress on loading and unloading, . In F, E.M result in case 3。 fitting angle the maximum and variation of stress may be minimized.