• Proceedings of the Korean Society of Precision Engineering Conference
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• 2004.05a
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• pp.84-84
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• 2004

다단 냉간단조 공정에서는 결함이 없는 재료의 유동, 금형내부의 완전한 충만과 금형의 수명향상 등을 위하여 예비성형체의 설계가 중요시되고 있다. 특히 최근 제품의 정밀도에 관심이 집중되어 냉간 상태에서 완제품으로 성형하여 후속 기계가공을 없앰으로써 재료의 절약, 에너지 절감, 가공공정수 단축 등 냉간단조를 고부가가치 가공의 유력한 수단으로 응용하려는 추세이다. 이러한 경우 예비성형체의 형상은 제품의 정밀도와 금형의 수명에 지대한 영향을 미친다.(중략)

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 1999.03a
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• pp.22-25
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• 1999

'There are a lot of process variables, exerted influence on the formability of products, in deep drawing process. Particularly, it is important that the punch and die shape radius of the process variables. Though researches have been performed on the deep drawing of sheet metal forming, like this study, but it is insufficient the actual circumstances that researches for process variables of the non-axisymmetric deep drawing products. In this study, An effect on thickness distribution is grasped as alteration of the punch and die shape radius in the process of non-axisyrnmetric deep drawing products, and then the optimal punch and die shape radius were presented, they were verified by the numerical analysis method (FEM).

• 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.10
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• pp.180-187
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• 2004

Die design to minimize the die wear in the cold forging process is very important as it reduce the production cost and the increase of the production rate. The quantitative estimation fur the die wear is too hard because the die wear is caused by many process variables. So, in this paper, the optimal shape of the backward extrusion punch is newly designed through the FE-analysis considering the surface expansion and Archard wear model in order to reduce the rapid wear rate that is generated for the backward extruded products exceeding the forming limit. The main shape variables of the backward extrusion punch are the flat diameter, angle, and round of the punch nose part. As the flat diameter and angle of the punch nose are larger, the surface expansion is reduced and the wear rate is decreased according to the reduction of the punch round. These results obtained through this study can be applied to the real manufacturing process.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.8 no.4
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• pp.708-712
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• 2007

Restriking is a shaping method added to the processed products to get higher precision and accuracy in the press die process. This method is frequently used in bending works and drawing works. The purpose of this research is to develop a design for rectangular drawing die punch and die block form which enables drawing formation and restriking in one set.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.33 no.6
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• pp.216-225
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• 2023

This paper describes the finite element analysis and die design change of cold heading punching process to increase the cold forging tool life and reduce the tool wear and stress concentration. Through this study, the optimization of punch tool design has been studied by an analysis of tool stress and wear distribution to improve the tool life. Plastic deformation analysis was carried out in order to understand the cold heading process between tool and workpiece stress distribution. Cold heading punch die design was set up to each process with different four types analysis progressing, the cold heading punch dies shapes with combination of point angle and punch edge corner radius shapes of cold forging dies, punch die material properties and frictional coefficient. The design parameters of point angle and corner radius of punch die geometry, die material properties and frictional coefficient were selected to apply optimization with the DoE (design of experiment) and Taguchi method. DoE and Taguchi method was performed to optimize the cold heading punch die design parameters optimization for bolt head cold forging process, it was possible to expect an reduce the cold heading punch die wear to the 37 % compared with current using cold heading punch in the shop floor.

• Transactions of the Korean Society of Mechanical Engineers
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• v.14 no.4
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• pp.769-776
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• 1990

본 연구에서는 소재형상을 미끄름선장법으로 구하고, 이것을 등고컵(cup with uniform height이하 h-uni cup)을 얻을 수 있는 이상적인 소재형상으로 보았으며, 이 로 부터 8각형을 소재로 취할 경우의 최적 모따기 량을 얻고, 또 정사각형 소재도 포 함하여 세가지 소재형상을 대상으로 하여, 광범위한 펀치의 모서리반경에 따른 한계드 로잉비(L.D.R), 유효 컵높이, 드로잉하중, 두께 분포 등을 고찰하였다.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2013.05a
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• pp.1275-1276
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• 2013

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2000.11a
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• pp.575-578
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• 2000

Die design to minimize the die wear in the cold forging process is very important as it reduce the production cost and the increase of the production rate. The quantitative estimation for the die wear is too hard because the prediction of the die wear is determined with many process variables. So, in this paper, the optimal shape of the backward extrusion punch is newly designed through the FE-analysis considering the surface expansion and Archard's wear model in order to reduce the rapid wear rate that is generated for the backward extrusion product exceeding the forming limit. The main shape variables of the backward extrusion punch are the flat, angle, and round of the punch nose part. As the flat and angle of the punch nose are larger, the surface expansion is reduced. and, the wear rate is decreased according to the reduction of the punch round. These results obtained through this study are applied to the real manufacturing process, it is implemented the reduction of the wear rate.

• Transactions of the Korean Society of Mechanical Engineers
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• v.17 no.5
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• pp.1132-1137
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• 1993

A simple simulative test was developed to evaluate stamping formability in plane strain stretching mode. The stamping formability was evaluated by limit punch height(LPH) in plane strain punch stretching test(PSST) compared to limit dome height(LDH) in hemispherical punch stretching test. PSST shows stable plane strain condition and good reproducibility with minimum scatter. Moreover LPH-value in PSST well ranks the stamping formability of various material and correlates with press performance.