• Journal of the Korean Society for Precision Engineering
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• v.18 no.3
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• pp.61-67
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• 2001

The finishing process for die is an important process because it has influence on final quality of products. Recently s study on development of 5-axis die automated finishing machine has been progressed. But die must be moved from the cutting machine to the die automated finishing machine. So manufacturing cost and time increase and machining error occurs by transfer. So, in this study, a 3-axis machining center was applied to die finishing. Because cutting tool can be changed to finishing tool by ATC, both of cutting and finishing process are possible on the machine. However, this application results in the decrease of finishing for the improvement of form accuracy. So this study focused on the generation of finishing tool path suitable to 3-axis die finishing for the improvement of form accuracy. The form accuracy evaluation is performed by the measurement of removal depth using a stylus profilometer. From the result, it is confirmed that form accuracy was improved less than 2$\mu$m of removal depth error.

• Transactions of Materials Processing
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• v.5 no.3
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• pp.239-255
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• 1996

A new forming technology has been developed to fabricate near-net shape products using light metal. A semi-solid forming technology has some advantages compared with the conventional forming processes such as die casting squeeze casting and hot/cold forging. In this study the numerical analysis of semi-solid filling for a straight die shape and orifice die shape in gate pattern is studied on semi-solid materials(SSM) of solid fraction fs =30% in A356 aluminum alloy. The finite difference program of Navier-Stokes equation coupled with heat transfer and solidification has been developed to predict a filling pattern and the temperature distribution of SSM. The programdeveloped in this study gives die filling patterns of SSM and final solidifica-tion region.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1996.04a
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• pp.783-786
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• 1996

In the temperature analysis, the heat transfer between the workpiece and the die has an important influence upon the temperature distribution. The accuracy of thermal analysis depends on the proper description of boundafy conditions. A t the contact surface of two materials with different temperature, this requires the knowledge of overall heat transfer coefficients. In order to evaluate the overall heat transfer coefficients, a technique is developed. This technique involves temperature measurement at the contact surface during hot upsetting operations and finite element computation to calcualte the overall heat transfer coefficient.

• Transactions of Materials Processing
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• v.7 no.2
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• pp.139-149
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• 1998

The technology of Semi-Solid Forging(SSF) has been actively developed to fabricate near net shape products using light and hardly formable materials. Generally the SSF process is composed of slug is compressed during a certain holding time in order to completely fill the die cavity and accelerate the solidification rate. The decision of compression time is important since it can affect microstructural characteristics, mechanical properties and shape of products.. In order to determine it proper overall heat transfer coefficient between the slug and dies should be investigated. This paper presents the procedure to find the overall heat transfer coefficient between the slug and dies by nonlinear optimization of temperature and solid fraction for a cylindrical slug at compression step in closed-die semi-solid forging. In finite ele-ment heat transfer analysis release of latent heat during solidification was considered. The influence of the predicted compression time on miscrostructural characteristics mechanimcal properties and shape of products is finally investigated by experiment.

• Journal of Advanced Marine Engineering and Technology
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• v.35 no.8
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• pp.1048-1054
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• 2011

Laser surface hardening process is the method of hardening surface by inducing rapid self quenching of laser injected area through transfer of surface heat to inside after rapid heating of laser injected area only by high density energy heat source. This surface treatment method does not involve virtually any thermal deformation by heat treatment nor accompanies any other process after surface hardening treatment. In addition, allowing local machining, this method is a surface treatment method suitable for die with complicated shape. In this study, die material cast iron was surface-treated by using high power diode laser with beam profile suitable for heat treatment. Since the shapes of die differ by press die process, specimens were heat-treated separately on plane and corner depending on the applied parts. At this time, corner heat treatment was done with optic head inclined at $10^{\circ}$. As a result, corner heat treatment easily involves concentration of heat input due to limitation of heat transfer route by the shapes compared with plane part, so the treatment accomplished hardening at faster conveying speed than plane heat treatment.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2008.10a
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• pp.110-113
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• 2008

This study was performed to predict the shape of polymer extrusion product and to find the cause of defective products Experiments was performed to extrude the complex profile shape using PC/ABS composite resin with new profile die and cooling die. A finite element analysis for the Polymer Extrusion process considering the heat transfer and thermal deformation was also performed, and the result was compared with the experimental data. It is found that the predicted profile shape in F. E. M was similar to the experimental result and the thickness of extruded product was thin when the velocity of profile die outlet was slow than the velocity of production (2m/min).

• Journal of the Korean Society for Precision Engineering
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• v.24 no.11
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• pp.44-51
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• 2007

Condenser tubes are mainly produced by precision extrusion with a porthole die and are used in the flow pass of refrigerant cooling systems in automobiles. The recent technical trend of condenser tube requires the tube to be of more multi cellizing, high strength and small size, and to increase the heat transfer area and heat efficiency. Hence, this paper is shown that the results of FE-simulation are in good agreement with the experimental ones. Finally, the extrusion die shape is proposed through analysis of FE-simulation and performance of trial extrusion. Chamber shape dimension and initial temperatures of die is adjusted analysis results. And the possibility of extrusion is estimated that forming load, welding pressure and stress analysis of die in this paper. The validity of simulated results was verified into extrusion experiments on the condenser tubes.

• Koreanishche Zeitschrift fur Deutsche Sprachwissenschaft
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• v.1
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• pp.375-400
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• 1999

Bei der maschinellen $\"{U}bersetzung(=M\"{U})\;\"{u}bernimmt$ ein Computer die Aufgabe, Texte von einer $nat\"{u}rlichen$ Sprache in eine andere automatisch zu $\"{u}bertragen$. Die meisten $M\"{U}-Systeme$ wurden bis in die 90er Jahre $haupts\"{a}chlich$ von grossen Firmen benutzt, die viele kostenaufwendige $\"{U}bersetzungsarbeiten\;zu\;bew\"{a}ltigen$ hatten. Aber die schnelle Verbreitung des Internets in den Alltag vieler Menschen hat die Situation radikal $ge\"{a}ndert$, und zwar so, $da\ss$ ein $M\"{U}-System$ viel $h\"{a}ufiger$ verwendet wird und es auch bei individuellem Bedarf Anwendung findet. Mit zunehmendem Volumen der zu $\"{u}bersetzenden$ Texte im Internet wird die Nachfrage nach einem $M\"{U}-System\;immer\;gr\"{o}sser$. Ziel der vorliegenden Arbeit ist es, ein Verfahren der maschinellen $\"{U}bersetzung$ der deutschen WWW-Texte ins Koreanische zu beschreiben. Dazu habe ich versucht, zwei unterschiedliche $M\"{U}-Systeme$ zu koppeln. Das Potential dieser Methode ist vor allem deswegen zu untersuchen, weil die sogenannte Lingware fur das Koreanische und Deutsche, wie z.B. Lexikon, Grammatik, Transfer-Lexikon, nur begrenzt zur $Verf\"{u}gung$ steht. Das erste System ist das $M\"{U}-System\;SYSTRAN\;f\"{u}r$ das Sprachpaar Deutsch-Englisch, das die deutschen WWW-Texte ins Englische $\"{u}bersetzt$. Das zweite ist em $M\"{U}-System\;f\"{u}r$ das Sprachpaar Englisch-Deutsch, das die vom Deutschen ins Englische $\"{u}bersetzten$ Texte ins Koreanische $\"{u}bersetzt$. Bei der Evaluierung der $\"{U}bersetzungen$ vom Deutschen ins Koreanische konnten etwa $30\%$ der Ausgaben als korrekt bewertet werden.

• Transactions of Materials Processing
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• v.19 no.6
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• pp.378-386
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• 2010

Nowadays there has been great interest in using heat treated cast material for press dies due to several advantages like reduction in die production costs. However, in hot press forming processes H13 forged tool steel is mostly used. Cooling performance of dies in hot press forming processes is considered as an important factor of study and also the IHTC parameter between cast material die and sheet metal should be considered as an essential. In the present study, the IHTC was calculated for the sheet metal in the hot press forming process with cast and forged material dies. The temperature measurements were performed for the sheet metal, casting and forged material dies by applying various contact pressure in hot press forming. IHTC was calculated and studied by adopting the inverse heat convection method in DEFORM-2D. Each IHTC was considered as a function of contact time and contact pressure. The experimental data were compared with calculated data obtained from the proposed equation and references.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2012.10a
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• pp.459-460
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• 2012