• 한국정밀공학회지
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• 제16권9호
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• pp.123-134
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• 1999

A new forming technology has been developed to fabricate near-net shape components by using aluminum alloys with globular microstructure. The estimations of filling characteristic in the forging simulation with arbitrarily shaped dies of SSM are calculated by finite element method with proposed algorithm. The proposed model and various boundary conditions for arbitrarily shaped die are investigated with the coupling calculation between the liquid phase flow and the solid phase deformation. The simulation processes with arbitrarily shaped dies are performed on the isothermal conditions and axisymmetric problems. To analyze the forging process simulation with SSM, new stress-strain relationship for semi-solid behaviour is described, and forging the liquid flow. Furthermore, For the purpose of getting net shape of SSM, it is important to be obtain a solid fraction in forging process with arbitrarily shaped dies. To produce a automotive part which have good mechanical properties, the filling pattern in accordance with die velocity and solid fraction distribution has to be estimated for arbitrarily shaped die.

• 수산해양기술연구
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• 제36권4호
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• pp.281-286
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• 2000

저층트롤 실물 어구를 이용한 해상 실험을 통하여 예망 중인 어구의 망구 형태에 관련되는 전개판의 간격 및 망고 등을 예망 속도별, 끌줄의 길이별로 측정하고, 이론적인 수치 해석 결과와 비교하여 실물어구의 수중 현황을 해석함으로서 어구의 효율적인 운용과 어획효과의 증대를 위한 기초자료를 제공하고자 한다. 수중 현황을 해석한 결과를 요약하면 다음과 같다. 1. 전개판의 전개간격은 예망 속도와 끌줄길이의 증가에 따라 직선적으로 증가하며 끌줄 길이에 의한 증가율이 예망 속도에 의한 증가율보다 현저히 크게 나타났으며, 그 간격의 변화는 57.0∼82.8m로서 후릿줄과 그물목줄 및 그물길이 전체의 43∼62%를 차지하였다. 2. 망구의 높이는 예망 속도와 끌줄길이의 증가에 따라 직선적으로 감소하며, 예망 속도에 의한 감소율이 끌줄 길이에 의한 감소율보다 현저히 크게 나타났는데 그 높이의 변화는 3.1∼4.0m로 나타났다. 3. 양 날개끝의 간격이 커지면 망고는 낮아지나 끌줄 길이가 증가할수록 날개 끝 간격의 증가에 대한 망구 높이 감소율의 비는 점차 작아졌다. 4. 망고에 대한 양 날개 끝 간격의 비는 예망속도와 끌줄 길이의 증가에 따라 점차 커졌는데, 그 비는 4.17∼7.81로 나타났다.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 2004년도 춘계학술대회 논문집
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• pp.114-117
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• 2004

The isothermal forging design of a Ti-6Al-4V wing shape was performed by 3D FE simulation. The design focuses on near-net shape forming by the single stage. The process variables such as the die design, pre-form shape and size, ram speed and forging temperature were investigated. The minimization of forging load and uniform strain distribution in a given forging condition were considered as main design factors. The FE simulation results fur the final process design were compared with the isothermal forging tests. Finally, the modified process design for producing the uniform Ti-6Al-4V wing product without forming defects was suggested.

• 소성∙가공
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• 제17권3호
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• pp.218-224
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• 2008

A recent trend in automotive parts has been an integration of sub-assemblies with unified shapes. Tube structures also have been integrated to one body structure by using a near net shape forming instead of adopting welding. A cylindrical elastomer-forming process can be utilized to form a steel tube compressed in a radial direction. This process has some advantages compared to a hydro-forming or a swaging process in the viewpoint of a lower investment and a higher productivity. In order to predict a feasible specification of products within a work capability of the elastomer-forming equipment developed previously, effects of geometrical parameters of a tube on its shape accuracy are examined. Two characteristic parameters to account for the shape accuracy are chosen. One is the curvature radius at the corner part and the other is the straight ratio of the formed region. Careful examination of two parameters has led that the shape accuracy can be easily predicted by the regression equation obtained from the response surface method.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 2000년도 추계학술대회 논문집
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• pp.178-184
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• 2000

To obtain high quality component with thixoforming process, it is important that the homegeneous distribution of solid particles without liquid segregation. In closed-die semi-solid forging process, liquid segregation is strongly affected by injection velocity than any other process variables because the material has to travel relatively long distance to fill the cavity through a narrow gate before solidification begins. The optimal injection velocity and die temperature were investigated to fabricate near-net-shape compressor component called Al frame.

• 소성∙가공
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• 제8권2호
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• pp.135-142
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• 1999

Tube Process(TP) is one of the processes to produce permanent magnets. Advantage claimed for this process is that it can accmplish both densification and anisotropication in one step forming. This process is distinguished from other processes since it uses deformable tube for densification of powder magnets. TP has, however, difficulties in manufacturing permanent magnets from Nd-Fe-B green powder due to folding resulted from large height reduction and localized densification. Therefore, an adequate preform is necessary to reduce folding resulted from large height reduction and localized densification. Therefore, an adequate preform is necessary to reduce folding, lead magnets into almost desired final shape and get uniform densification. In this paper, preform design for TP is carried out without a deformable tube to investigate the behaviour of magnet sinter-forging. Preform design is accomplished to increase the effective magnet area with a near net shape and uniform densification.

• 소성∙가공
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• 제18권6호
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• pp.444-447
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• 2009

Piston crown to the hot forge a unified nature of the product has a shape with multi-level step forging process, so if you are not a mechanical professional, this process could lead to a significant loss to the material. Therefore, material technology in minor terms; continue to improve the collection rate that undamaged the product material. The piston crown and the manufacturing products such as marine diesel engines are being forged to reduce costs and to improve mechanical properties. Piston crown molding is a hot forging process that works in large volume forging products. Because of the size of the hard plastic material flow process for improving the design and actual field experience through advanced plastic technology, it is important to interpret the results. Also for many experimental plastic procedures, the accumulation of results is very important.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 2009년도 춘계학술대회 논문집
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• pp.98-101
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• 2009

Piston crown to the hot forge a unified nature of the product has a shape with multi-level step forging process, so if you are not a mechanical process that can be a significant loss is material. Therefore, minor in terms of material technology; continue to improve the collection rate should be. The Piston crown and the manufacturing of products such as marine diesel engines, reducing costs and to improve mechanical properties of the method are being forged. Piston crown molding hot forging process the large volume forging products handling because of the size of the size of the hard plastic material flow process for improving the design and actual field experience through advanced plastic technology, and it is important to interpret the results and for many experimental plastic The accumulation of results is very important.

• 소성∙가공
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• 제14권2호
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• pp.126-132
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• 2005

The isothermal forging design of a Ti-6Al-4V wing shape was performed by 3D FE simulation. The design focuses on near-net shape forming by the single stage. The process variables such as the die design, pre-form shape and size, ram speed and forging temperature were investigated. The main design priorities were to minimize forging loads and to distribute strain uniformly in a given forging condition. The FE simulation results for the final process design were compared with the isothermal forging tests. The instability of deformation was evaluated using a processing map based on the dynamic materials model(DMM), including flow stability criteria. Finally, a modified process design for producing a uniform Ti-6Al-4V wing product without forming defects was suggested.

• 소성∙가공
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• 제7권2호
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• pp.139-149
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• 1998

The technology of Semi-Solid Forging(SSF) has been actively developed to fabricate near net shape products using light and hardly formable materials. Generally the SSF process is composed of slug is compressed during a certain holding time in order to completely fill the die cavity and accelerate the solidification rate. The decision of compression time is important since it can affect microstructural characteristics, mechanical properties and shape of products.. In order to determine it proper overall heat transfer coefficient between the slug and dies should be investigated. This paper presents the procedure to find the overall heat transfer coefficient between the slug and dies by nonlinear optimization of temperature and solid fraction for a cylindrical slug at compression step in closed-die semi-solid forging. In finite ele-ment heat transfer analysis release of latent heat during solidification was considered. The influence of the predicted compression time on miscrostructural characteristics mechanimcal properties and shape of products is finally investigated by experiment.