• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2003.10a
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• pp.277-280
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• 2003

It was investigated that the "ㄱ" type angle product could be bended with a curvature during extrusion by extru-bending process. The bending process for the "ㄱ" type angle product can be developed by the hot metal extru-bending machine with the two punches moving in the different velocity. Because of non-symmetry of product, it is important to design the ruled surface contour of dies cavity for the welding and bending with two billets. So it is designed that the multi-hole container has two non-symmetric holes and non-symmetric contour of dies entrance. The results of the experiment show that "ㄱ" type angle product can be bended by the extrusion process and that the curvature of the product can be controlled by the velocity of punch and that the defects such as the distortion of section and the thickness change of the product and the folding and wrinkling of the product 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.16 no.11
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• pp.116-121
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• 1999

Since the material flow near the die part in CONFORM (Continuous Extrusion Forming) process is similar to that of side-extrusion, the side-extrusion model of tube shaped aluminum profiles was studied for the die design in CONFORM process. In this paper, the effects of process parameters in the side -extrusion through a two-hole die face, such as material flow, height and thickness of the tube, velocities of punch and lengths of bearing land were investigated using UBET program and DEFORM commercial FEM code. The optimum lengths of the bearing lands and punch velocities for obtaining the straight shape products required were determined.

• Transactions of Materials Processing
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• v.1 no.1
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• pp.66-74
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• 1992

According to the variation of hydrostatic pressure on the central axis of deformable material, the V-shaped central bursting defect may be created in extrusion or drawing processes. The process factors which affect the generation of defects are semi-angle of die, reduction ratio of cross-sectional area, friction factor, material properties and so on. The combination of these factors can determine the possibility of defect creation and the shape of various round holes which have been created inside already. By the rigid plastic finite element method, this paper describes the observations of change in shape of round holes with process conditions such as semi-angle of die, reduction ratio of cross-sectional area and friction factor at the non-steady state of axisymmetrical extrusion process when the round hole is already existed inside the original billet. Also, the effects of process factors are investigated to prevent the possible defects.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1995.10a
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• pp.232-235
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• 1995

A side-extrusion model, meant for deeper understanding of the material flow in the CONFORM (continuous extrusion forming) of trub shaped aluminum profiles is presented. In order to get the desirded straight shape of the extrudate,every part of its cross-section must exit the die with the same velocity. Problem is assumed by plane strain UBET-model to analyze it in a simplified way. This has been done by studying the side-extrusion through a two -hole die face. The flow is balanced by determining the optimum lengths of the bearing lands, i.e., those lengths which result in equal exit velocities of the extrudates. Furthermore, the material flow, as influenced by the punch velocity, has been investigated.

• Transactions of Materials Processing
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• v.24 no.2
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• pp.89-94
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• 2015

Medical catheter tubes are disposable devices that are inserted into the body cavities such as the pleura, trachea, esophagus, stomach, urinary bladder, ureter, or blood vessels for surgical procedures. Each hole of the inner tube is called a lumen, which is used as a passage for drug injections, waste discharge, polypus removal, blood transport, or injection of a camera or sensor. The catheter tube is manufactured by extrusion. The flow in the inner extrusion die affects the thickness and diameter of the tube. In the current study computer simulation of flow in an extrusion die for catheter tubing was performed. Velocity, pressure, shear rate, and shear stress were investigated and the die design was examined.

• 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.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2003.10a
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• pp.313-317
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• 2003

Porthole die extrusion is the method which put the billet in the container and push it between die hole by ram. This method make it possible that product manufacture which have complex shape of area with excellent induction of area, in addition that this is economical. So this method is used as the basic manufacturing method of many industrial materials. The subject of this research is the forming technology development of heat sink which is being produced by extrusion process in my country. Flow condition of extrusion for heat sink, and metal flow of billet in the die are estimated by the means of rigid-plasticity finite element method.

• Transactions of Materials Processing
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• v.13 no.8
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• pp.663-670
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• 2004

The bending phenomenon has been known to be occurred by the difference of velocity at the die exit. The difference of velocity at the die exit section can be obtained by the different velocity of billets through the multi-hole container. The difference of velocity at the die exit can be controlled by the two variables, the one of them is the different velocity of extrusion punch through the multi-hole container, the other is the difference of hole diameter of muliti-hole container. In this paper the difference of hole diameter is applied. So it can bend during extruding products because of the different amount of two billets when billets would be bonded in the porthole dies cavity. And the bending curvature can be controlled by the size of holes. The experiments with aluminum material for the curved tube product had been done for circular or rectangular curved tube section. The results of the experiments show that the curved tube product can be formed by the extru-bending process without the defects such as distortion of section and thickness change of wall of tube and folding and wrinkling. The curvature of product can be controlled by shape of cross section and the difference of billet diameters. And it is known that the bonding and extruding and bending process can be done simultaneously in the die cavity by the experiments that rectangular hollow curved tubes could be extruded by porthole dies with four different size billets made of aluminum material. And it shows that bending phenomenon can happen during extruding with for different billets from the analysis by DEFORM-3D.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1992.04a
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• pp.79-83
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• 1992

According to the variation of hydrostatic pressure on the central axis of deformable material, the V-shaped central bursting defect may be created on extrusion or drawing processes. The process factors whichaffect the generation of defects are die semi-angle, reduction ratio of cross-sectional area, friction factor, material properties and so on. The combination of these factors can determine the prossibility of defect creation and the shape of various round holes which have been created inside already. By the rigid plastic finite element method, this paper describes the observations of change in shape of a round hole with process conditions suchas die semi-angle, reduction ratio of cross-sectional area and friction factorat the unsteady state of axi-symmetrical extrusion process when the round hole is alreadyexisted inside the original billet, and also, the effects of process factors are investigated to prevent the possible defects.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2004.10a
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• pp.346-349
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• 2004

In the previous experimental study about extru-bending of angle product, the bending of extruded angle products with the '${\wedge}$' section and 'ㄱ' section can be abtained by the hot metal extru-bending machine with the two punches moving in the different velocity. The bending curvature can be controlled by the different velocity of billets through the two-hole container. This paper describes simulation of extru-bending process by the difference of punch velocities. The result of the forming simulation by $DEFORM^{TM}-3D$ shows that the bending phenomenon at the die exit during extrusion can be abtained by the two punches moving in the different velocity. And it is possible to design extrusion dies and to control the curvature of product through the simulation of extru-bending process by analysis