• Proceedings of the Korean Society of Precision Engineering Conference
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• 2003.10a
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• pp.232-232
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• 2003

• Transactions of the Korean Society of Mechanical Engineers A
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• v.34 no.3
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• pp.299-305
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• 2010

In general, the flexible forming die that has been used in the flexible forming process has the identical punch size; hence, its flexibility is relatively low because the range of allowable curvature radii is limited due to the uniform punch tip radius. Hence, a conceptual design of a sectional flexible die is presented for enhancing the flexibility of the forming process. Two punches of different sizes are used to configure the arbitrary forming surface. For a forming region with a relatively large curvature radius, a large punch array block is used; on the other hand, for the forming regions with small curvature radii, a small punch block is used. The cross-sectional profiles are compared with the target shape for evaluating the effectiveness of the process. Consequently, it is confirmed that the sectional flexible die can be used along with a combination of punch blocks of different sizes for manufacturing objective surfaces of complex shapes.

• Journal of the Korean Society for Precision Engineering
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• v.21 no.9
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• pp.32-40
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• 2004

This paper deals with an automated computer-aided process planning and die design system by which designer can determine operation sequences even if they have a little experience in process planning and die design for axisymmetric products. An attempt is made to link programs incorporating a number of expert design rules with the process variables obtained by commercial FEM softwares, DEFORM and ANSYS, to form a useful package. The system is composed of four main modules. The process planning and the die design modules consider several factors, such as the complexities of preform geometry, punch and die profiles, specifications of available multi former, and the availability of standard parts. They can provide a flexible process based on either the reduction in the number of forming sequences by combining the possible two processes in sequence, or the reduction of deviation of the distribution on the level of the required forming loads by controlling the forming ratios. Especially in die design module an optimal design technique and horizontal split die were investigated for determining appropriate dimensions of components of multi-former die set. It is constructed that the proposed method can be beneficial for improving the tool life of die set at practice.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2004.10a
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• pp.1307-1311
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• 2004

This paper deals with an automated computer-aided process planning and die design system by which designer can determine operation sequences even if they have a little experience in process planning and die design for axisymmetric products. An attempt is made to link programs incorporating a number of expert design rules with the process variables obtained by commercial FEM softwares, DEFORM and ANSYS, to form a useful package. They can provide a flexible process based on either the reduction in the number of forming sequences by combining the possible two processes in sequence, or the reduction of deviation of the distribution on the level of the required forming loads by controlling the forming ratios. Especially in die design module an optimal design technique and horizontal split die were investigated for determining appropriate dimensions of components of multi-former die set. It is constructed that the proposed method can be beneficial for improving the tool life of die set at practice.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.21 no.11
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• pp.1912-1920
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• 1997

In the analysis of metal forming process, ALE(Arbitrary Lagrangian Eulerian) finite element methods have been increasingly used for the capability to control mesh independently from material flow. The methods can be divided into two groups i.e., coupled and split formulations. In the present work, the split ALE formulation is used for computational efficiency. A split ALE finite element method developed for rigid-viscoplastic materials and applied to the analysis of hot square die extrusion. Since thermal state greatly affects the product quality, an ALE scheme for temperature analysis is also presented. As computational examples, profile shapes as square and cross-like sections are chosen.

• Journal of Korea Foundry Society
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• v.18 no.3
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• pp.211-221
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• 1998

주조방안이란 주형(금형)에 공동부를 어떻게 설계하고 공동부의 어떤 위치에 어떻게 탕도, 탕구 등을 설계할 것인지, 또 over-flow 및 air-vent는 어떻게 설계하여 가스뽑기 및 용탕을 공동부에 원활히 충진시켜 완전한 제품을 얻을 수 있을까에 대한 제반적인 주조방법의 계획이다. 즉, 용탕을 공동부에 충진시키는 시스템이며, 주조상에 발생하는 제문제 및 주조제품의 품질에 가장 큰 영향을 미치는 요소 중의 하나이다. 따라서 만약 주조방안 시스템이 부적절하여 불량률이 높은 경우에는 대폭적인 금형수정이나 경우에 따라서는 불가피하게 금형을 신작해야 하는 큰 문제도 야기될 수 있다. 또한 기본적인 품질문제로 탕회, 탕경, 크랙 등의 외관불량과 기동 등의 내부결함, 내압불량등도 유발될 수 있다. 그러나 이러한 불량대책으로 쉽게 주조방안을 수정하는 것은 주조 시스템 자체가 변해버리기 때문에 피해야 하며 다른 대책을 선행하여 해결할 수 없었을 때 최종적으로 신중히 검토 후 주조방안을 수정하는 것이 바람직하다. 따라서, 본고에서는 Al합금 다이캐스트 주조기술에 있어 주조품질을 결정하는 중요한 요소인 주조방안의 효과적인 설계를 위한 주조기 선정, 금형분할면 선정, 탕구계의 설계와 탕구선정, over-flow 및 air-vent설계, 수축여유 및 금형냉각방안 선정기술에 대한 기본적 방안을 제시하고 실제 주조방안의 대표적인 사례를 소개하고자 한다.

• Transactions of the Korean Society of Mechanical Engineers
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• v.16 no.6
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• pp.1064-1074
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• 1992

Eliminating the under-cut caused by interference between a mold and a product in designing a mold for in jection molding processes is a very important problem. In general, the under-cut problem can be avoided by side cores which are the principal members of a mold assembly. In this research, a procedure has been developed by which the side cores and the corresponding core and cavity plates of a mold are generated after identifying the mold faces preventing product faces from moving while being discharged. The characteristic features of the procedure suggested in this paper are as follows. One is that the interference faces between the product and the mold are derived only from the core plate(or cavity plate) alone without considering the product together. The other is that the algorithm in the designing of side cores and modifying molds, is very efficient because it uses Euler operations instead of Boolean operations.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2000.11a
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• pp.377-380
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• 2000

The dimensional accuracy of the cold forged part is depended on the elastic characteristics of the die. To obtain the high stiffness of the prestressed die, the first stress ring of the tungsten carbide material is considered. For the design, Lam 's equation is used. The design of the prestressed die has been compared with the conventional that. For the comparison, the FE-analysis using ANSYS has been performed. The results indicate that the prestressed die with the high stiffness can be obtained by the using the high stiffness material as the first stress ring.

• Journal of the Korean Society for Precision Engineering
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• v.18 no.12
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• pp.145-151
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• 2001

The dimensional accuracy of the cold forged part is depended on the elastic characteristics of the die. To increase the stiffness of the prestressed die, the first stress ring of the tungsten carbide alloy (WC) is considered. For the design, Lame's equation is used. Diameter ratios and interferences have been determinated by maximum inner pressure without yielding of materials. The design of the prestressed die has been compared with the conventional one. For the comparison, the FE-analysis using ANSYS has been performed. The results indicate that the prestressed die with the high stiffness can be obtained by the using the high stiffness material as the first stress ring.

• Journal of the Korean Society for Precision Engineering
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• v.16 no.2 s.95
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• pp.87-94
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• 1999

The automated die design program is developed for cold forging of axisymmetric parts which are mainly produced by forward extrusion, backward extrusion, composite extrusion and upsetting. For this study, firstly classification of forged parts and investigation of die construction type usually employed in forging industry are carried out and the most proper type from several kinds of die construction is proposed as a standardized one. Based on the die design rules summarized in the references such as handbooks, technical papers, monthly journals, etc. the automated die design program was made using AutoLISP language available in AutoCAD software of personal computer. This program interactively runs for only input data, for example, forging process, shape of forged parts, type of punch, split of die insert and design of shrinkage rings and then displays details of drawings necessary to make a forging die. When a variety of forging processes and forged parts are tested to examine the validity of this program, it was confirmed to give good results applicable to the forging die design in press shop.