• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 1996.10a
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• pp.14-19
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• 1996

This study presents development of finite element simulation program and analysis of hot extrusion through square dies with mandrel. The design of extrusion dies is still an art rather than science. Die design for a new extrusion is developed from through in-plant trials. In the present paper, three-dimensional steady-state finite element simulation program is developed. The developed system is effectively used to simulate extrusion of clamp shaped hollow section. The objective of the present paper is to study the possibility of integrating this method into the design of dies for extrusion of complex section. To obtain sound product, the distributions and effects of temperature, effective strain rate, mean strain rate and mean stress are studied.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 1997.10a
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• pp.45-48
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• 1997

The kinematically admissible velocity field is developed for the eccentric extrusion of circular shaped products. The curving of product in extrusion is caused by the difference of the linearly distributed longitudinal velocity on the cross-section of the workpiece at the dies exit. The results of the eccentric extrusion by upper bound analysis show that the curvature of product increases with the increase in eccentricity of gravity center of the cross-section of workpiece at dies entrance from that of the corss-section at the dies exit end. By the DEFORMTM-3D analysis, the curving of circular shaped product in extrusion is changed by the eccentricity, die land length and the die length. The result of the analysis by DEFORMTM-3D software shows that the curvature of circular shaped product increases with the eccentricity. The two analysis and one experiment show the curving phenomenon in eccentric extrusion process.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2001.11a
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• pp.99-106
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• 2001

The design for cold extrusion dies is very important, because the die insert is subjected to very high radial and hoop stresses. The design of cold extrusion dies has many constrained conditions. In this paper, the used assumptions are such that the yield strength of each ring is selected according to the allowable tensile or compressive hoop stress in each ring and the maximum allowable inner pressure, when yielding occurs in one ring of the dies, is obtained by the proposed equation. In order to obtain design variables, such as diameter ratios and interferences, using the maximum inner pressure, the flexible tolerance method was used for shrink-fitted thick-walled cylinders. ANSYS APDL was used to perform the repeated analysis of deformation of the dies due to the variation of the design variables. The response surface methodology is utilized to analyze the relationship between the design variables and the maximum radial displacement of the die insert during extrusion. From the results, it is found that outer diameter of the die Insert has the largest effect on the minimization of maximum radial displacement at the inner surface of the dies.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1997.10a
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• pp.531-534
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• 1997

A design system of dies for hot extrusion of structural shapes such as Z' s, L' s, T' s, U' s and H' s from aluminum alloys was developed in this study. The developed design system of dies is based of established die design rule system. The design rules for die design are obtained from the handbooks, plasticity theories and relevant references. The environment of the system is AutoCAD and AutoLISP, the graphic programming language was used for the configuration of the system. This system includes five major modules such as section shape design module, die opening number module. die opening layout module, die correction module and die bearing design module that are used to determine design variables. This system would be used to design of dies for hot extrusion from aluminum alloys and widely used in manufacturing course..

• 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.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2001.10a
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• pp.170-173
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• 2001

The design for cold extrusion dies is very important because the die insert is subjected to very high radial and hoop stresses. The design of cold extrusion dies has many constrained conditions. In this paper, two assumptions were proposed. First assumption was selected by yielding strength dependent on the to hoop stress of each ring in dies. Second assumption is that the maximum inner pressure is determined when yielding occurs in one ring of dies. To obtain the maximum inner pressure the flexible tolerance method was applied. A comparison of design values between the proposed method and the conventional method has been discussed.

• 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.

• Transactions of Materials Processing
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• v.19 no.8
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• pp.460-467
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• 2010

It was studied that two plates of aluminum can be welded by extru-riveting experiments with extru-rivet welding dies, and that the welding strength and metal flow on the welding section were analyzed by computer simulation according to the welding variable such as the diameter of extrusion insert dies. It was known by computer simulation that welding strength on the welding section of plates could be influenced by the diameter of extrusion insert dies. And it was known by experiments that two plates of aluminum can be welded on a spot point on aluminum plate by extru-rivet welding process, and that welding strength is higher and higher if the diameter of extrusion insert die is smaller and smaller, and that welding strength is the highest when diameter of extrusion insert dies is ${\emptyset}4.2$mm in the case that the diameter of rivet is 5 mm, when aluminum 5052 two plates with 1.5 mm thickness and one plate with 3mm thickness for rivet plate are used as welding material.

• Journal of the Korean Society for Precision Engineering
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• v.22 no.1
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• pp.167-174
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• 2005

The design for cold extrusion dies is very important, because the die insert is subjected to very high radial and hoop stresses. The design of cold extrusion dies has many constrained conditions. In this paper, the used assumptions are such that the yield strength of each ring is selected according to the allowable tensile or compressive hoop stress in each ring and the maximum allowable inner pressure, when yielding occurs in one ring of the dies, is obtained by the proposed equation. In order to obtain design variables, such as diameter ratios and interferences, using the maximum inner pressure, the flexible tolerance method was used for shrink-fitted thick-walled cylinders. ANSYS APDL was used to perform the repeated analysis of deformation of the dies due to the variation of the design variables. The response surface methodology is utilized to analyze the relationship between the design variables and the maximum radial displacement of the die insert during extrusion. From the results, it is found that outer diameter of the die insert has the largest effect on the minimization of maximum radial displacement at the inner surface of the dies.

• Transactions of Materials Processing
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• v.14 no.2 s.74
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• pp.160-167
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• 2005

In the present study about extru-bending of angle product, the bending of extruded angle products with the $'\Lambda'$ section and 'ㄱ', section can be obtained using two extrusion billets 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 simulations and experiments of extru-bending process that can make bending during extruding by the difference of stem velocities. And they are applied to two kinds of dies, that is, one of them is conical dies with symmetry $'\Lambda'$ section and the other one is conical dies with asymmetry 'ㄱ' section. The results of the forming simulation by $DEFORM^{TM}-3D$ and results of experiments show that the bending phenomenon at the die exit during extrusion can be obtained with two extrusion billet by the two stems moving in the different velocity. And it was known that it is possible to design the structure of conical cavity of extrusion dies and to control the curvature of product through the simulation and experiment of extru-bending process.