• 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

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1995.04b
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• pp.171-177
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• 1995

In this paper, the deformation method for inner and outer races of rollr-bearing bymeans of the warm precision forging is investigated. We adapted the process designsuch as following that, toincrease Die life, reduce heat transfer through conduction and the eccentricity of preform in warm forging of bearing gace, the bottom portion of billet is formed during upsetting process. Then it is backward extruded, and thus obtained ring preform is formed by combined extrusion. Also, we compared it with the froming method in China and Japan, and we have known it is more excellent method. Basides, this forming method is simulated by UBST which is based on the merits of UBET nd FEM. The results show that it is easy to know the exact location of neutral surface through the inspection of streamline during combined extrusion, and the velocity vector distribution along the surface of velocity discontinuity is investigationed. Also the effectiveness of this method is proved by te experiment using model material that is Plasticine.

• Transactions of Materials Processing
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• v.9 no.1
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• pp.10-16
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• 2000

This research investigates microstructures and fatigue properties of the weldments of 6005A aluminum alloy developed for railroad vehicles. The samples were extruded into a truss structure and welded together using the gas metal arc welding process. The extruded sample showed a wide variation in grain size, possibly due to the frictional heating as well as the inghomogeneous metal flow in the extrusion die. The mechanical properties of the samples were affected by the mirocstructures. The fatigue strength of the welded structure was found to decrease significantly from that of the base metal. It was found that the fatigue characteristics of the welded structure were determined by the microstructure of the parent metal as well as weld defects such as porosities and the liquation cracks.

• Transactions of the Korean Society of Machine Tool Engineers
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• v.17 no.2
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• pp.114-120
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• 2008

This study is to compare and analyze the material flow, deformation characteristics, and forming load of flange by means of similitude experimental method of model material using plasticine. In order to find optimal forming conditions, prototype experiments were designed to investigate forming characteristics of general-purpose flange under various working conditions. As a result of prototype experiments, billet thickness and gap-height ratio was found to be the most influential experimental parameter in flange forming. Forming loads from prototype experiments were compared to the results of finite element analysis after conducting estimation of forming loads of real material. Results of prototype experiments based on model material techniques are expected to be used as a basic data of die design f3r the development of products and process.

• Journal of the East Asian Society of Dietary Life
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• v.17 no.3
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• pp.379-383
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• 2007

The effects of phenolic acids on the physical properties of wheat flour extrudate were investigated. Ferulic acid, fumaric acid, and p-coumaric acid were mixed with hard wheat flour, respectively, and extruded under a twin screw extruder. We found that by adding the phenolic acids, longitudinal expansion at the die increased, textural hardness decreased, and the water absorption capacity of the extrudate decreased. The results showed that the addition of phenolic acids produced a softer textured, more longitudinally puffed and hydrophobic extrudate compared to the control extrudate. Moreover, the addition of phenolic acids did not significantly affect the color of the extrudate: oxidative browning of the phenolic acids was not observed, due to inactivation of the browning enzymes under the hot temperature and reduced oxygen conditions of the extrusion process.

• Journal of the Korean Society for Precision Engineering
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• v.17 no.8
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• pp.151-156
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• 2000

A kinematically-admissible velocity field is proposed to determine the forming load the average extruded length and the velocity distribution in the forward and backward extrusion process of a socket. Experiments are carried out with antimony-lead billets at room temperature using the rectangular punch and the hexagonal die. The theoretical predictions of the forming load and the average extruded length are in good agreement with the experimental results.

• Journal of the Korean Society for Precision Engineering
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• v.17 no.11
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• pp.213-219
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• 2000

A impeller hub is usually made through three forging processes : forward extrustion, upsetting and finishing. The finishing process is closed die forging in which the load increases abruptly at the final stage, resulting in underfilling in the finished product due to insufficient load capacity of the press. In this study, the rigid-plastic finite element analysis was applied to the impeller hub forging process in order to optimize process and to estimate required load. As a result, two kind of improvements for the process were suggested to reduce the load requirement in the finishing process.

• Journal of the Korean Society for Precision Engineering
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• v.16 no.11
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• pp.148-157
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• 1999

The objective of this study is to investigate the effect of three main chemical compositions(Mg, Zn, Si) on extrudability of 7xxx Al alloy with high tensile strength. A few Al alloys based on 7xxx alloys were metal mold cast with various weight*%) of Mg 0.3-1.2%, Zn 5.0-8.0% and Si 0.4-0.7%, to envestigate the effects of extrudability, as well as mechanical properties. To measure the extrudability of cast billets, maximum extrusion pressure and surface temperature at die exit before tearing occurs were obtained by experiment and simulation of thermo-viscoplastic F.E.M. Also the yield and tensile strength of extruded products were tested.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2009.10a
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• pp.470-473
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• 2009

In this paper, back pressure forging processes of which back pressures 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.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 1997.04a
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• pp.54-61
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• 1997

Furthermore the rothor pole, with a solid type, manufactured by cold forging process at present should dmploy 3 press lines which consist of total 7 processes. Since A.S.B. treatment is prerequisite for the press line, the 3 times of A.S.B. treatment requires a long lead time, with little contribution to the reduction in cost. The author has investigated, through this researach, the possibility of a new forging method for a rotor pole production with (1) 2 pass instead of 3 press lines (2) only one A.S.B. treatment instead of 3 ones (3) solid type instead of sectional type, and (4) improvment of material property during process using a modified forging process and a specially designed die.