• 한국산학기술학회논문지
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• 제9권2호
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• pp.276-280
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• 2008

본 연구에서 개발할 설계기술은 부가가치가 매우 높은 소량 다품종 건축용 내 외장재의 금속 패널 코너가공 법에 관한 것이다. 금속 금구류 및 건축용 내 외장재로 사용되는 2.5mm이상 되는 금속강판을 사용함에 있어서 가장 문제가 되는 직각코너링 접합부위에서 발생되는 내식성(수명성), 내후성, 및 미려성(디자인)을 향상시키므로 품질의 향상뿐만 아니라 소량 다품종의 생산성을 증대시킬 수 있는 국내 최초 금속패널 코너가공을 할 수 있는 벤딩 다이시스템(Bending Die System)을 설계하고자 한다.

• 소성∙가공
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• 제17권8호
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• pp.600-606
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• 2008

In closed-die hot forging, a billet is formed in dies such that the flow of metal from the die cavity is restricted. Some parts can be forged in a single set of dies, whilst others, due to shape complexity and material flow limitations, must be shaped in multi sets of dies. The purpose of a performing operation is to distribute the volume of the parts such that material flow in the finisher dies will be sound. This study focused on the design of preforms, flash thickness and land width by theoretical calculation and finite element analysis, to manufacture the super hot forging product, 70MC type piston crown used in marine engine. The optimal design of preforms by the finite element analysis and the design experiment achieves adequate metal distribution without any defects and guarantees the minimum forming load and fully filling of the cavity of the die for producing the large piston crown. The maximum loads obtained by finite element analysis are compared with the results of experiments. The loads of the analysis have good agreements with those of the experiment. Results obtained using DEFORM-2D enable the designer and manufacturer of super hot forging dies to be more efficient in this field.

• 한국분말재료학회지
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• 제11권5호
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• pp.399-411
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• 2004

Crack generation during die compaction and distortion during sintering have been critical problems for the conventional pressing and sintering process. Until now, trial and error approach with engineers' industrial experiences has been only solution to protect the crack generation and distortion. However, with complexity in shape and process it is very difficult to design process conditions without CAE analysis. We developed the exclusive CAE software (PMsolver/Compaction) for die compaction process. The accuracy of PMsolver is verified by comparing the finite element simulation results with experimental results. The simplified procedures to find material properties are proposed and verified with iron based powder and tungsten carbide powder. Based on the accurate simulation result by PMsolver, the optimal process conditions are designed to get uniform density distribution in a powder compact after die compaction process by using a derivative based optimization scheme. In addition, the effect of non-uniform density distribution in a powder compact on distortion during sintering is shown in case of the fabrication of tungsten carbide insert.

• 한국산학기술학회논문지
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• 제9권6호
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• pp.1518-1522
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• 2008

본 연구에서 개발한 벤딩다이시스템(Bending Die System)제작기술은 부가가치가 매우 높은 소량 다품종 건축용 내 외장재의 금속 패널 코너가공법에 관한 것이다. 금속 금구류 및 건축용 내 외장재로 사용되는 2.5mm이상 되는 금속강판을 사용함에 있어서 가장 문제가 되는 직각코너링 접합부위에서 발생되는 내식성, 내후성, 및 디자인을 향상시키므로 품질의 향상뿐만 아니라 소량 다품종의 생산성을 증대시킬 수 있는 국내 최초 금속패널 코너가공을 할 수 있는 벤딩다이시스템을 설계하여 제작하였다. 이를 제작하여 경제적, 기술적으로 고부가가치를 창출하여 수출증대에 기여할 수 있다.

• 한국산학기술학회:학술대회논문집
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• 한국산학기술학회 2004년도 춘계학술대회
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• pp.42-46
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• 2004

네일 파일(nailfile)을 제조할 때 재료는 강판(두께 0.5mm)을 사용하고 가공방법은 외형형상을 만들고 $\phi$ 0.8-$\phi$ 1.0mm의 구멍을 약 300여개 뚫어 완성한다. 이들의 가공방법은 에칭(etching)에 의존하므로 제조 원가의 $33\%$를 에칭비가 차지하고 있으므로 제조원가의 상승원인이 되고 에칭시 부식제(etching reagent)의 잔류도 환경친화적이 못되며 재료가 강판이기 때문에 제품에 녹(rust)이 생기므로 이들의 문제점을 해결하고자 하였다. 따라서, 재질은 스테인리스판으로 교체하고 에칭가공 대신 금형으로 가공할 수 있는 프로그레시브 퍼퍼레이팅 금형(progressive perforating die)을 개발하였다.

• 소성∙가공
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• 제23권5호
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• pp.303-310
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• 2014

Functionally graded properties are characterized by the gradual variation in composition and structure through the volume of the material, resulting in corresponding gradation in properties of the material. Direct laser melting (DLM) is a prototyping process whereby a 3-D part is built layer-wise by melting metal powder with laser scanning. Studies have been performed on the functionally graded properties induced by direct laser melting of compositionally selected metallic powders. For the current study, quadrangle structures were fabricated by DLM using Fe-Ni-Cr powders having variable compositions. Hardness and EDX analysis were conducted on cross-sections of the fabricated structure to characterize the properties. From the analysis, it is shown that functionally graded properties can be successfully obtained by DLM of selected metallic powders with varying compositions.

• 소성∙가공
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• 제14권4호
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• pp.338-350
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• 2005

Recently, in the field of automobile industry, to solve the problem of reducing the weight of automobile for the improvement of fuel efficiency and the protection of environment, the aluminum alloy parts have been substituted for the steel parts. However, the aluminum alloy does not have as good mechanical property as the steel part. To improve the mechanical property, the semi-solid die casting process is performed to make automobile parts. In the fabrication of semisolid material the control of the liquid segregation is very important to improve the material properties of aluminum alloy. In the present paper we examine the influence of the liquid segregation by the injection conditions in the semi-solid die casting has been investigated.

• 한국정밀공학회지
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• 제17권4호
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• pp.48-68
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• 2000

The high-speed machining technology of difficult-to-cut material is needed to achieve the high-efficiency of die manufacturing. The high-speed machining is applied in automobile, airplane and electricityㆍelectro industry etc, because it can improve machining efficiency and productivity with high speed, high power and high rotation. In this study, high speed machinability, tool wear characteristics and its monitoring, characteristics of damaged layer, machinability of difficult-to-cut material, characteristics of a free curved surface and method of CAD/CAM system were introduced to acquire the shortening of machining time, the improvement of machining efficiency and the high quality of machined surface. Therefore, we establish the stabilization condition of difficult-to-cut material machining and present the optimal cutting condition for high-efficiency cutting.

• 한국정밀공학회지
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• 제14권8호
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• pp.82-91
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• 1997

The major objective of this study is to establish analytical technique in order to analyze the behaviour of semi-solid material considering induction heating of the billet. Induction heating process is analyzed by using commerical finite element software. ANSYS. The finite element program, SFAC2D, for the simulation of deformation in semi-solid state is developed in the present study. The semi-solid behaviour is described by a viscoplastic model for the solid phase, and by the Darcy's law for the liquid flow. Simple compression and closed-die compression process considering induction heating are analyzed, and also it is found that the distribution of initial solid fraction of the billet has an important effect on deformation behaviour of semi-solid material. In order to verify the effectiveness of proposed analytical technique the simulation result is compared with experimental result.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 2003년도 추계학술대회논문집
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• pp.84-88
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• 2003

In this paper, The optimum design of a die shape has been carried out the FEM analysis of a pilger mill process considering various factors. The pilger mill forming process consists of a pair of rotating die which has appropriate surface shape. The important design parameters of the pilger mill are the feed rate and the profile of grooved die. Optimum design procedure was performed in order to investigated effects on the forming load and the deformed shape of material depending on the die radius profile. Profile of the die surface for the optimum design were suggested with the linear, the cosine and the quadratic curve considering a physical forming process. The surface of each die was modeled using the 3DAutoCAD and the analysis of pilger forming process was performed using the LS-DYNA3D. The optimum profile of the die shape for the pilger mill was determined to the quadratic profile. Since the analysis results provide that the model of the quadratic profile gives the lowest forming load and a proper deformed shape.