• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 1999.03b
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• pp.280-283
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• 1999

Square dies are widely used for hot extrusion processes with high production rate. However the design and manufacture of square dies mainly relies on experience of industrial engineers To overcome such difficulty this study develops a method of automatic generation of NC-codes for the manufacture of extrusion square dies. The result shows that the method can reduce the lead time for the design and manufacture of square dies as well as eliminating engineers ow experience.

• Transactions of Materials Processing
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• v.9 no.2
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• pp.179-185
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• 2000

Square dies are widely used for hot extrusion processes with high production rate, however, the design and manufacture of square dies mainly relies on experience of industrial engineers. To overcome such difficulty, this study presents a method of automatic generation of NC-codes for the manufacture of extrusion square dies. The result shows that the method can reduce the lead-time for the design and manufacture of square dies.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 1999.03b
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• pp.80-83
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• 1999

Rigid Plasticity Finite Element Analysis is developed for the shapes of dead metal zone and the curving velocity distribution in the eccentric square dies extrusion. The shape of dead metal zone is defined as the boundary surface with the maximum friction constant between the deformable zone and the rigid zone. The curving phenomenon in the eccentric square dies is caused by the eccentricity of square dies. The deviated velocity is changed with the distance form the center of cross-section of the workpiece. The results show that the curving of products and the shapes of the dead metal zone are determined by Rigid Plasticity Finite Element Analysis and that the curvature of the extruded products increases with the eccentricity.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1995.04b
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• pp.187-191
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• 1995

An experimental study to analyze thd hot extrusion processes of regular square section through square dies is carried out by using plasticine as a model material at room temperature. The experimental setup for the extrusion of squared section from round billets through square dies is designed and manufactured. In order to visullize the plastic flow in the extrusion process the technique of gridding on the planes of the sysmmetries and a stacking the desks with different colors are employed. Velocity fields on the symmetry planes are obtained by using grid distortion.

• Transactions of Materials Processing
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• v.5 no.2
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• pp.156-164
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• 1996

To investigate the behavior of plastic deformation in axisymmetric extrusion through square dies, experimental works with the plasticine as a model material are carried out at the room temperature. Some mechanical properties of the model material are determined by compression and ring compression tests. Visioplasticity method using expermental grid distortion in extrusion is introduced to analyze the plastic flow strain rate and strain distribution. In spite of severe deformation during the extrusion through square die the visioplasticity method shows good results for the distribution of effective strain rate and effective strain.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2001.10a
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• pp.208-211
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• 2001

In the drawing from round billet to non-circular section there are two different processes through solid hole die(HD) and the other cassette roller dies(CRD). The CRD process has several cassette type rollers and a billet is able to move through the given gaps between two profiled rollers. The objective of this study is based on the analysis and evaluation of two aforementioned processes using experiments and finite element simulation. In order to simulate the multi-stage drawing process from circular sectioned billet to rounded square section, the finite element analysis is applied to the process using a commercially available DEFORM-3D code. Two types of experimental drawing tests through designed and manufactured dies for pure copper and aluminum alloy are carried out at room temperature. The analysis included comparison of material properties before and after drawing of each process and also provide some useful information by a FEM simulation.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2000.04a
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• pp.63-66
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• 2000

This study presents development of an software for process and die design of hot extrusion through square dies. The design of extrusion dies is still an art rather than a science with increasing complexity of shape and thinness of section. Therefore most of the die design is still dependent on personal judgement intuition and experience. The objective of this study is to develop an software system which includes a design rule extracted from literatures and experts in the extrusion industry. The developed system is effectively used to design extrusion processes and dies with reduced lead time and trial extrusion.

• Transactions of Materials Processing
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• v.4 no.4
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• pp.322-334
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• 1995

This study presents development of an expert system for process and die design of hot extrusion through square dies. The design of extrusion dies is still an art rathere than a science with increasing complexity of shape and thinness of section. Therefore, most of the die design is still dependent on personal judgement, intuition and experience. The objective of this study is to develop an expert system which includes a rule base system extracted from literatures and experts in the extrusion industry. The system also includes finite element simulation program. The developed system is effectively used to design two types of processes and dies with lead time and trial extrusion.

• Transactions of the Korean Society of Mechanical Engineers
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• v.16 no.2
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• pp.207-225
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• 1992

The study is concerned with the thermo-viscoplastic finite element analysis of axisymmetric forward hot extrusion through square dies. The problem is treated as a nonsteady state problem because the distribution of temperature and material properties are continuously changing with the punch travel. In square die extrusion, difficulties arise from the severe distortion and die interference of elements at the aperture rim of the die even with a small punch travel. And finite element computation is impossible without intermittent remeshing. Accordingly, an automatic remeshing technique is proposed by employing specially designed mesh structure near the aperture rim. The analysis of temperature distribution includes heat conduction through material interfaces, heat convection and radiation to the atmosphere and is carried out by decoupling the heat analysis from the analysis of the deformation. The extrusion load and the distributions of strain rate and temperature are computed for the given cases rendering reasonable results. Computed grid distortions are found to be in good agreement with the experimental results. It has been thus shown that the proposed method of analysis can be effectively applied to the axisymmetric hot extrusion through square dies.

• Transactions of Materials Processing
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• v.7 no.1
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• pp.72-80
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• 1998

This study is concerned with the thermo-biscoplastic finite element analysis of hot tube extrusion through square dies with a mandrel. The problem is treated as a non-steady state and the ALE description is used due to abruptly turning flow at the die aperture. Since the contact heat transfer coefficient and the friction factor are required in the analysis experiments are also carried out to determine the values, In order to apply ceramics to an extrusion die the study is focussed on under-standing the characteristics of the process. The simulated results provide the useful informations such as metal flow temperature distribution stress state etc. The elastic analysis of the dies is carried out to obtain the stress state of the ceramic dies.