• Journal of Korea Foundry Society
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• v.34 no.4
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• pp.123-129
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• 2014

This work presents the results of a thixo-extrusion process applied to aluminum alloy and and reheating characteristics of semi-solid A356 Alloy using have been discussed. The reheating experiment was performed using an electric resistance furnace and multi-stage heating for uniform reheating. The thixo-extrusion was performed at the optimal reheating conditions of the semi-solid A356 alloy, the the extrusion conditions were an extrusion ratio of 33 and ram speed of 6 mm/sec. The results showed that the thixo-extrusion of semi-solid A356 alloy fabricated by the cooling slope reduced the extrusion pressure by 180% in comparison with hot extrusion, and that a sound extrusion could be obtained in spite of the same extrusion ratio and strain rate.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2001.10a
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• pp.212-215
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• 2001

The bending process for the rectangular curved tube can be developed by the hot metal extrusion machine with the multiple punches moving in the different velocity. The bending phenomenon can be controlled by the two variables, the one of them is the difference of velocity at the die exit section by the different velocity of billets through the multi-hole container. The other is the difference by the different hole diameter. The results of the experiment show that the rectangular curved tube can be formed by the extrusion process and that the curvature of the curved product can be controlled by the velocity of punch and the diameter of container hole and that the defects such as the distortion of section and the thickness change of the wall of tube and the folding and wrinkling of thin tube did not happen after the bending processing by the extrusion bending machine.

• Journal of the Korean Society for Precision Engineering
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• v.21 no.7
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• pp.53-61
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• 2004

Condenser tube which is used for a cooling system of automobiles is mainly manufactured by conform extrusion. However, direct extrusion using porthole die in comparison with conform extrusion has many advantages such as improvement of productivity, reduction of production cost etc. In general, the porthole die extrusion process is useful for manufacturing long tubes with hollow sections and consists of three stages(dividing, welding and forming stages). Especially, Porthole die for producing condenser tube is very complex. Thus, in order to obtain the detailed mechanics, to assist in the design of proper die shapes and sizes, and to improve the quality of products, porthole die extrusion should be analyzed in as non-steady state as possible. This paper describes FE analysis of non-steady state porthole die extrusion for producing condenser tube with multi-hole through 3D simulation in the non-steady state during the entire process to evaluate detailed metal flow, temperature distribution, welding pressure and extrusion load. Also to validate FE simulation of porthole die extrusion, a comparison of simulation and experiment results was presented in this paper.

• Journal of the Korean Society for Railway
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• v.6 no.3
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• pp.194-202
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• 2003

To make railway carbody light in weight has advantages at some aspects of both manufacturing and maintenance. Recently, railway carbodys of steel structure have been lightened their weight by using aluminum extrusion plate. for the additional lightening of railway carbody, an optimal design which maintains proper strength and minimizes weight must be achieved. Optimization which is used with finite element analysis for aluminum extrusion plate has the disadvantage of consuming much time. In this paper, the method of equivalent material property which is available to FEA code is established using the method of equivalent stiffness. This method for plate is expanded into the method for railway carbody structure with plates and shells. An objective function is established for maximum stiffness of unit aluminum extrusion plate using established method of equivalent material property. We performed an multi-objective optimization using the penalty function method. As a result, recommendable shapes and sizes of unit extrusion plate for under-frame of high speed train is presented.

• Proceedings of the Materials Research Society of Korea Conference
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• 2007.11a
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• pp.153.1-153.1
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• 2007

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1995.10a
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• pp.236-239
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• 1995

In this paper,Upper bound analysis to predict the formation of corner cavity during the final stage of backward extrusion is used. The critical condition for corner cavity formation is obtained by upper bound analysis. The quantitive relationships between corner cavity formation and process parameters are studied. To broaden forming limit area, driven container and multi-step forming process is proposed. As a result of FEM, forming limit is enlarged. And this results is compared with the analytric results

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 1996.03b
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• pp.130-137
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• 1996

Several cold extrusion processes to produce an axisymmetric steel piston-pin are investigated for comparing each other. Two methods among four conventinal ones are selected to be simulated using the rigid-plastic finite element method. One of the both methods using a mechanical press has one stage process and the other utilizing a cold header applies a multi-stage process to produce a final product. Because the main process is a backward extrusion, the design criteria such as the backward extrusion ration and punch diameter to depth rationare ocnsidered. FEM analysis is performed mainly for strain distributin and load-stroke relationshis. Based on the results of preliminary simulatin, both process sequences are proved to have proper charicteristics suitable for each production method in terms of maximum load. Those simulation results will be a good design criteria in the future work to advance the manufacturing process.

• Transactions of Materials Processing
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• v.23 no.3
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• pp.151-158
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• 2014

Half channel angular extrusion(HCAE) is the integration of equal channel angular extrusion(ECAE), which is a well-known severe plastic deformation(SPD) method, with conventional forward extrusion in order to increase the strain per pass and effectiveness of the grain refinement. In the current study, the effects of processing routes during HCAE(Routes A, B, and C) on the strain distribution of the specimens have been investigated for an AZ61 Mg alloy by using three-dimensional finite element analysis. Comparisons with the results from a multi-pass of ECAE are made.

• Design & Manufacturing
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• v.17 no.4
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• pp.63-71
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• 2023

In order to increase the extrusion production speed of aluminum, extrusion die cooling technology using liquid nitrogen has recently attracted a lot of attention. Increasing the extrusion speed increases the temperature of the bearing area of extrusion dies and the extrusion profile, which may cause defects on the surface of extruded profile. Extrusion die cooling technology is to directly inject liquid nitrogen through a cooling channel formed between the die and the backer inside the die-set. The liquid nitrogen removes heat from the die-set, and gaseous nitrogen at the exit of the channel, covers the extrusion profile of an inert atmosphere reducing the oxidation and the profile temperature. The aim of this study is to evaluate the cooling capacity by applying die cooling to extrusion of Al-Mn-based aluminum alloy flat tubes, and to investigate the effects of die cooling on the change in extrusion characteristics of flat tubes. Cooling capacity was confirmed by observing the temperature change of the extrusion profile depending on whether or not die cooling is applied. To observe changes in material characteristics due to die cooling, surface observation is conducted and microstructure and precipitate analysis are performed by FE-SEM on the surface and longitudinal cross section of the extruded flat tubes.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2001.10a
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• pp.204-207
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• 2001

The bending process for the circular curved tube and rectangular curved tube with fins can be developed by the hot metal extrusion machine with the multiple punches moving in the different velocity. The bending phenomenon can be controlled by the two variables. The one of them is the difference of velocity at the die exit section by the different velocity of billets through the multi-hole container. The other is the one by the different hole diameter. The results of the experiment show that the circular curved tube with fins and rectangular curved tube with pins can be formed by the extrusion process and that the curveture of the product can be controlled by the velocity of punch and diameter of container hole and that the defects such as the distortion of section and the thickness change of the wall of tube the folding and wrinkling of thin tube and fins did not happen after the bending processing by the extrusion bending machine.