• 소성∙가공
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• 제32권1호
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• pp.5-11
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• 2023

The aim of this study is to manufacture an aluminum pipe yoke of automotive steering system for lightweight. In a multistage cold forging process for aluminum pipe yoke, the surface defects frequently occur due to excessive deformation or friction during extrusion process for forming hollow pipe part. It is import to reduce the friction between the material and the forging die. This study investigated a multistage forging process with sliding die to reduce friction for aluminum pipe yoke. After evaluating by FE analysis, the forging experiment with the sliding die was carried out. As a result, it was possible to manufacture a sound aluminum pipe yoke.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 1998년도 춘계학술대회논문집
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• pp.126-129
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• 1998

Proper design of blocker dies is one of the most important aspect of impression and closed-die forging to achieve adequate metal distribution. Determination of the blocker configuration is a very difficult task and is art in itself, requiring skills achieved only by years of extensive experience. To save the cost and time of blocker design, many methods using computer were proposed. In this research, low pass filter method proposed by Oh etc. was applied to blocker die design of spoiler support, part of aircraft and plasticine model experiment of closed die forging of spoiler support was accomplished to verify the validity of the blocker designed.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 1997년도 춘계학술대회논문집
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• pp.281-286
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• 1997

Thin study is concerned with the cold repressing of sintered preform by rotary forging process. A experiment has been carried out using the rotary powder forging press(500kN) which was designed and constructed in the authors' laboratory. The effect of process variables and aspect ratios of sintered preform was observed and measured by several mechanical test, such as working force, hardness distribution, density, and microstructures of the specimens. It is found that the highly densified P/M parts can be obtained and this process is very effective for improving quality of the powder products.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 1995년도 추계학술대회논문집
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• pp.30-36
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• 1995

Conventionally design for multi-stage cold forging depends on the designer's experience and decision-making. Due to such non-deterministic nature of the process sequence design, a flexible inference engine is needed for process design expert system. In this study, A* searching algorithm was introduced to arrive at the vetter process sequence design considering the number of forming stages and levels of effective strain, effective stress, and forming load during the porcess. In order to optimize the process sequence in producing the final part, cost function was defined and minimized using the proposed A* searching algorithm. For verification of the designed forming sequences, forming experiments and finite element analyses were carried out in the present investigation. The developed expert system using A* searching algorithm can produce a flexible design system based on changes in the number of forming stages and weights.

• 소성∙가공
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• 제18권6호
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• pp.458-464
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• 2009

Thermal energy control is a important factor to control properties of large sized product in ingot-forging. Good control of thermal energy helps to increase characteristics and eliminate defects of large cast-forged part, such as large sized forged shell. We have studied about not only large size ring forging process and after heat treatment process by FEM simulation. Changes of temperature and microstructure for forged shell were predicted according to different heat treatment conditions. Therefore, we can choose the proper heat treatment condition by FEA. The sectional properties confirmed by practical experiment and evaluation have presented possibilities of process design by computational analysis.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 2009년도 춘계학술대회 논문집
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• pp.437-440
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• 2009

In this paper, an aluminum ring forging process of manufacturing an optimized perform for a hot forging process is simulated using AFDEX 3D, a general-purpose metal forming simulator based on rigid-thermoviscoplastic finite element method. Non-isothermal analysis is carried out and the predictions are compared with the experiments in terms of dimensional accuracy. It was shown that the predictions are in good agreement with the experiments.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 2007년도 추계학술대회 논문집
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• pp.338-343
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• 2007

We presented a special method of forging hollow shafts of hard-to-form material, which is composed of piercing with back pressing and hollow shaft extrusion. The presented method was applied to cold forging a bushing of an excavator. The finite element simulation technology was employed for developing the optimized process and the predictions were compared with the experiments. The method was also applied to an automotive part and was verified to be powerful for manufacturing the cold forged hollow shafts of the hard-to-form materials.

• 한국정밀공학회지
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• 제17권1호
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• pp.209-215
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• 2000

Precision forging technology that can control flow velocity of workpiece have been developed to minimize the amounts of machining. To get the uniform rib length, flow velocity distribution is needed to be estimated and controlled. Computer-aided design is known for very effective to estimate the deformation behavior and design the die for controlling the flow velocity. In this study, die design to control the deformation velocity are investigated using the DEFORM-2D about rib-web shape parts. Also we can get uniform rib length by enforcing the back pressure at end section of rib. The applied load of back pressure farming is lower than that of conventional forging. These results are analysed and confirmed by the experiment.

• 한국산학기술학회논문지
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• 제2권1호
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• pp.1-6
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• 2001

회전성형법은 프레스 축 중심에 대하여 일정한 각도로 경사진 요동축과 원추형상의 상부 금형을 축 중심에 대하여 회전시키고 소재를 상승 가압하면 상부금형과 소재가 점진적으로 접촉하면서 제품을 성형하는 공정이다. 본 연구팀에서 개발된 회전 분말단조 프레스(500kN)를 이용해서 산업용 고밀도 베벨기어의 성형성 실험을 수행하였다. 실험결과로 회전 분말단조 공정과 회전 분말성형 공정에서의 성형하중, 성형밀도, 경도, 미세조직 등의 변화를 조사하여 제품의 기계적 성질을 규명하고 실제로 산업 전반에 적용할 수 있는 가능성을 제시한다.

• 소성∙가공
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• 제15권8호
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• pp.621-627
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• 2006

Recently, micro-alloyed steels which could eliminate heat treatments after forging has been developed. These non heat-treated micro-alloyed steels have several advantages over the conventional quenched and tempered steel for cold forging. First of all, long components can be fabricated with a better dimensional accuracy since bending of long forged part after quenching treatment could be avoided. And it is possible to eliminate two energy consuming heat treatment steps, which are a spherodizing before forging and quenching/tempering after forging. Therefore, more cost effective and environment friendly process could be designed. However, there is non-uniform distribution of strain occurred across the forged part, since these non heat-treated micro-alloyed steel use strain hardening mechanism. In the present study, it was investigated how to lessen non-uniformity and increase strength together for cold forging when a baking heat treatment is applied in micro-alloyed steels. For this purpose, micro-alloyed steels developed by Se-A Besteel recently was used for the experiment.