• Journal of the Korea Institute of Military Science and Technology
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• v.6 no.1
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• pp.68-80
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• 2003

The backward extrusion process of titanium alloy with large length to diameter ratio was simulated for different punch and die shape. The process variables such as initial billet shape, interface friction, contacting time and punch velocity were investigated and compared with experimental results. To make more effectively titanium alloy cup shape forging products with vertical wall, a modified die design which can reduce forging load, prevent sticking with punch and minimize material loss was suggested.

• Transactions of Materials Processing
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• v.13 no.8
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• pp.723-730
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• 2004

This paper describes the analysis of extrusion process and integrity for a condenser tube which is a component of the heat exchanger in automobile and all conditioning apparatus. Recently, according to the development of analysis method using the computer, the numerical simulation have been applied to the 3-dimensional hot extrusion process with complex section area of the non-steady statement and then results of the analysis have been applied to optimal die design and process design. In this paper, firstly, the die design was performed for a condenser tube with a multi-hole section and the rigid-plasticity FE analysis performed of extrusion process. Secondly, we estimated metal flow of billet, extrusion load, welding pressure in chamber etc. and evaluated the pressure and elastic strain of the die land and mandrel tooth profile through a stress analysis of the die. Finally, the extrusion test was performed to estimate the validity of FE analysis. This paper confirmed that the designed extrusion die of the research is satisfactorily designed fur integrity of condenser tube.

• Journal of the Korean Society for Railway
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• v.2 no.2
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• pp.1-5
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• 1999

Based on the development of designed technology for aluminum carbody. the prototype aluminum carbody has been constructed. All extrusion profiles required for the carbody has been produced and their quality has also been proven. For sound construction. welding technology to join aluminum extrusion profiles has been developed and jigs for precise assembly of blocks have been made. The aluminum carbody for urban subway train has been completed with the required chamber being set and the welding deformations being constrained by jigs. The safety of the carbody structure has also been proven by the static load test. And also, painting technology has been developed and the surface of the carbody has been pre-treated and painted. The developed technology to construct the aluminum carbody can be used in mass production of aluminum cars ordered by domestic and foreign customers.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2011.06a
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• pp.1243-1244
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• 2011

• 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.9
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• pp.96-103
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• 1999

A kinematically admissible velocity field is derived to analyze the forming load and the extruded length in the extrusion/forging process of trochoidally headed bars from round billets. The forming load and the extruded length are obtained by minimizing the total energy-consumption rate. Experiments are carried out with lead billets at room temperature using trochoidally shaped punches. The theoretical predictions of forming load and extruded length are in good agreement with the experimental results.

• 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.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.5 no.2
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• pp.56-64
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• 2006

Rapid progress in many branches of technology has led to a demand on new materials such as high strength light weight alloys, powdered alloys and composite materials. The hydrostatic extrusion is essentially a method of extruding a clad rod through a die. In order to investigate the effect of the process conditions such as friction heat, deformation and clad thickness on the clad extrusion process, viscoplastic finite element simulations were conducted. A specific model for theoretical analysis used in this study is The single scalar variable version of Hart's model. An experiment also has been carried out using 1.5MN hydrostatic extruder with variable speed ram, LVDT and load cell for comparison. It is found that the hydrostatic extrusion pressure considering the effect of heat dissipation in this theoretical work was closer to the experimental pressure than the isothermal hydrostatic extrusion pressure.

• Transactions of Materials Processing
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• v.10 no.6
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• pp.485-492
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• 2001

The paper is concerned with plastic flow in the port and welding chamber of rectangular hollow section extrusion through the porthole die. The extrusion process is analyzed by numerical simulation and experiments in the unsteady state. The effects of types of inlet with and without taper on the flow and extrusion load are mainly discussed and compared by FEA and experiments. Experiments are carried out by using the plasticine as a model material at room temperature. To visualize the plastic flow in the extrusion process, some split dies and punches are designed and manufactured by EDM. The theoretical predictions by FEM are reasonable agreements with experimental results on the deformed configurations and welding lines.

• Transactions of the Korean Society of Mechanical Engineers
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• v.13 no.3
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• pp.330-336
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• 1989

In analyzing the axisymmetric backward extrusion process a new method of analysis using upper-bound theorem is proposed in which the plastic zone and dead metal zone cam be predicted. Experiments are carried out with commercial aluminum. The metal flow on the meridional plane has been visualized experimentally by using the gridded specimens. It is shown that the theoretical results both in extrusion load and deformation pattern are in good agreement with the experimental results and they can be used for effective punch and die design to consider various process parameters in axisymmetric backward extrusion.