• Design & Manufacturing
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• 제12권1호
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• pp.13-17
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• 2018

It was analyzed and experimented on the change of the material thickness according to the size of the "R" of the punch and die corners using the material of SCP-1 0.25mm As a result, the following conclusions were obtained. Tensile strength analysis and safety analysis of materials are very important process for each process in strip layout, and Through this, the Influx of material and the deformation of the material were found. As a result of safety analysis and tensile thickness analysis, when the corner R of the punch was 0.3 mm and the edge R of the die was 1.0 mm The inflow of the material was not smooth, and the thickness of the corner part became 0.2 mm, causing cracks. when the corner R of the punch was 0.5 mm and the edge R of the die was 1.5 mm The inflow of the material was smooth, The thickness of the corners of the product is 0.21mm and It was considered that cracks do not occur when the thickness of the bottom surface and the body part becomes thin. The results obtained by applying the results obtained from the analysis, In Experimental Condition 1, a crack occurred in the same part of the analysis In Experimental Condition 2, the flow of the material was smooth and the drawing processing could be performed without generating cracks.

• 대한기계학회논문집
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• 제19권4호
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• pp.896-907
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• 1995

Titanium 6242(.alpha. + .betha.) alloy has a good strength/weight ratio and is used for aircraft components such as engine disks and compressor blades. When this material is forged at an elevated temperature, the process parameters should be carefully controlled because the process window of this material is quite narrow. In the present investigation, a rigid-thermoviscoplastic finite element method is used to predict the deformation behavior and temperature/strain distributions in an engine disk during near-net shape hot forging. The purpose of the investigation is to obtain a proper ram speed profile, assuming the hydraulic press used in the forging is capable of varying ram speed during loading. In result, it was found that the ram speed at constant strain-rate of 0.5/sec shows a sound deformation behavior, a relatively uniform deformation and a good temperature distribution. This information is also valuable in predicting resulting microstructures in the disk.

• 대한기계학회논문집
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• 제16권7호
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• pp.1314-1321
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• 1992

본 연구에서는 중실형의 해석을 확장하고 유선함수와 상계해법을 이용하여 일 반적 경계역을 갖는 관형압출의 체계적 해석법을 연구해서 보다 정확한 압출하중의 예 측 뿐아니라 소성변형역 및 소성유동도 예측 가능한 방법을 제안하고자 한다.

• 소성∙가공
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• 제12권1호
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• pp.18-25
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• 2003

This paper explains the process design for improving tool life in the conventional hot forging process. The thermal load and the thermal softening are happened by contact between the hotter billet and the cooler tools in hot forging process. Tool life decreases considerably due to the softening of the surface layer of a tool was caused by a high thermal load and long contact time between the tools and the billet. Also, tool life is to a large extent limited by wear, heat crack and plastic deformation in hot forging process. Above all, the main factors which affect die accuracy and tool life we wear and the plastic deformation of a tool. The newly developed techniques for predicting tool life are applied to estimate the production quantity for a spindle component and these techniques can be applied to improve the tool life in hot forging process.

• 한국공작기계학회논문집
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• 제11권4호
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• pp.26-33
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• 2002

One characteristic of Fine-Blanking is that the size and the direction of stress and strain are very complex in the plastic flow according to the condition of blanking. Especially, they are affected by the clearance of punch and die, by the force of blanking holder and by the force of counter punch. The purpose of this research is to how the deformation behavior in shear zone more clearly, based on Green & Cauch's large deformation theory. The deformation behavior and cracks were investigated in each step of shear, according to punch penetration increase, the use of V-indenter ring and the hardness of materials. This research found that the transforming behavior was the same as pure discretion and the cracks could be prevented when hardness is low.

• 한국정밀공학회지
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• 제19권8호
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• pp.187-193
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• 2002

Much research efforts have been made on the equal channel angular pressing (ECAP) which produces ultra-fine grains. Among many process parameters such as channel angles, frictions, die deformations and materials employed, the effects of material properties on the deformation behavior have been investigated. The finite element method has been used to investigate this issue.

• 대한기계학회논문집
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• 제19권7호
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• pp.1642-1650
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• 1995

Process design is one of the most important fields in metal forming, where the finite element method has appeared a useful method for industrial applications. In this study, a program using the rigid plastic finite element has been developed for process design in three-dimensional plastic deformation. The surface integration for calculation of the friction between die and workpiece has been implemented with care in numerical treatment. The developed program is applied to a precision coining process of electronic components. It is confirmed that the program developed here is suitable for process design in metal forming with three-dimensional plastic deformation.

• 한국주조공학회지
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• 제13권1호
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• pp.81-93
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• 1993

It is well-known that the analysis of elasto-plastic thermal stress and deformation are substantially important in optimal design of metal casting mould. The unsteady state thermal stress and deformation generated during the solidification process of ingot and mould have been analyzed by two dimensional thermal elasto-plastic theories. Distributions of temperature, stress and relative displacement of the mould are calculated by the finite element method and compared with experimental results. In the elasto-plastic thermal stress analysis, compressive stress occurred at the inside wall of the mould whereas tensile stress occurred at outside wall. A coincidence between the analytical and experimental results is found to be fairly good, showing that the proposed analytical method is reliable.

• 소성∙가공
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• 제26권4호
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• pp.205-209
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• 2017

In this paper, finite element prediction of deformation of material due to springback after material removal by an axisymmetric forging fabrication at room temperature is conducted. An elastoplastic finite element method is employed considering die plastic deformation. The predictions of a springback analysis conducted after the final stroke of an axisymmetric cold forging process containing residual stresses are utilized to be mapped onto the final material after the material removal. It is assumed that material removal occurs at an instant, i.e., all the material to be removed disappears at once. The predictions are compared with experiments, revealing strong qualitative agreement.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 1994년도 춘계학술대회 논문집
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• pp.63-70
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• 1994

An upper bound elemental technique(UBET) is applied to predict forging load and die-cavity filling for non-axisymmetric ring forging. The finial product is divided into three different deformation regions. That is axisymmetric part in corner, lateral plane-strain part and shear deformation on boundaries between them. The plane-strain and axisymmetric part are combinded by building block method. Also the total energy is computered through combination of three deformation part. Experiments have been carried out with pure plasticine billets at room temperature. The theoretical predictions of the forging load and the flow pattern are in good agreement with the experimental results.