• Journal of the Korean Society for Precision Engineering
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• v.13 no.9
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• pp.165-173
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• 1996

The dimensional accuracy of a final product is mainly affected by elastic die deformation during the forging and elastic recovery after the ejection in cold forging process. The investigations on elastic recovery are not so much as those of elastic die deformation. The elastic recovery can be determined by using the elastic-plalstic finite element analysis, but, this method has some limits such as poor conver- gence and long computational time, etc. In this paper, a theoretical analysis for predicting the elastic recovery of a final product in axi-symmetric forging process by using the rigid-plastic finite element method is presented. The rigid-plastic finite element analysis of a cold forward extrusion process involving loading, ejecting process is accomplished by rigid-plastic FE code, DEFORM. The effect of elastic die deformation on the final product dimenmsion is also considered. The calculated elastic recovery is compared is compared with the analysis result of elastic-plastic FE code. ABAQUS.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 1999.03b
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• pp.94-97
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• 1999

The study has been performed for the relation between die and product in closed die upsetting by the experiment. the strain of die has been given by the simple experiment using the strain gauge located at the outer surface of die and the deformation history of die and product has been given by the experiment and Lame's formula. the product with accurate dimension and shape can be obtained by analysing elastic deformation of die during upsetting process. The deformation of die during metal forming process has been given by the experiment and lame's formula. The product with accurate dimension and shape can be obtained by analysing elastic deformation of die during upsetting process. The deformation of die during metal forming process has been usually predicted by the experience of industrial engineers of finite element analysis. But it is difficult to predict the dimension of product at unloading and ejected states. The study has given useful result for the deformation history of die and product through the experiment and Lame's formula at closed die upsetting and can be applied in the die design for product with accurate dimension.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.27 no.11
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• pp.1897-1906
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• 2003

A finite element analysis for near-net-shape forming of A16061 powder was performed under warm rubber isostatic pressing and warm die pressing. The advantages of warm compaction by rubber isostatic pressing were discussed to obtain a part with better density distributions. The shape of rubber mold was designed by determining a cavity shape that provides a desired shape of the final powder compact. To simulate densification and deformed shape of a powder compact during pressing, the elastoplastic constitutive equation based on yield function of Shima-Oyane was implemented into a finite element program(ABAQUS). The hyperelastic constitutive equation based on the Ogden strain energy Potential was employed to analyze nonlinear elastic response of rubber. Finite element results were compared with experimental data for Al6061 powder compacts under warm die pressing and warm isostatic pressing.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.14 no.11
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• pp.5352-5356
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• 2013

Plastic product manufacturing industry has usually focused on a mechanical and physical characteristics of molding. Recently, not only these characteristics but also the aesthetic value is significantly considering. Especially, the molding's gloss, which we can easily distinguish, is an important aesthetic point. In this study, it were investigated that the gloss variation of ABS moldings by changing injection conditions such as injection pressures, injection speed, holding pressures melt and mold temperatures by injection molding experiment. The experimental results revealed that the holding pressure was the most active condition on gloss of ABS molding.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.8 no.5
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• pp.979-983
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• 2007

In this thesis, a strip layout drawing of LCD S/C (shield case) was prepared. In the press die, strip layout drawing is a major factor that decides the mass production of a product. The 3D CAD/CAM system was applied for the easy correction of the interference factor with other parts to be mounted. The material use ratio was enhanced to 60.17% by optimizing the blank layout and strip layout in double width array. Furthermore, the flatness of the product was made to fit the requirements by adding the bidding process intensively on the notching part where the occurrence of the change in shape is expected owing to the thin material. For the 3D CAD/CAM software, Unigraphics NX3.0 was used. The strip layout drawing was prepared in 12 processes.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.10 no.7
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• pp.1453-1458
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• 2009

This study is to apply the mechanical press joining method to join two kinds of sheet metals with circular holes by mechanical pressing instead of laser beam. Usage of the mechanical pressing avoids the thermal deformation of sheet metals which occurs inevitably in laser joining. A die design has been proposed to make the mechanical press joining applicable with finite element analysis. Five design factors related to the joining force have been selected and applied to the Taguchi method for optimization. Among five factors, 'Forming Depth' and 'Punch Corner Radius' have been revealed to be the most influential ones.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.15 no.2
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• pp.653-659
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• 2014

Computer simulation has been performed to optimize cold forging process of automotive LPI fuel filter housing. A mold and the test product have been manufactured considering the strain and load distribution during the cold forging process. Also, fuel flow simulation has been performed to analyze flow characteristics of existing model and new model. Simulation result shows that two models have equivalent pressure drop. Compared with the mass of existing product, raw material reduction of 16 g and 30.5 g has been achieved from the upper and lower housing, respectively. Total mass reduction of the new housing was 46.5 g. Leak test and internal pressure test have been performed to verify the safety standard and test results were satisfactory.

• Polymer(Korea)
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• v.28 no.3
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• pp.263-272
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• 2004

Using computer simulation, the processibility and properties of the inst겨ment panel of automobile produced by gas injection molding were predicted and evaluated. The P-V-T data of ABS, resin were used in the gas injection molding process in order to estimate the mold filling phenomena. The optimum process conditions were found by adjusting the process parameters including pressure, filling time, the positions of gas channel and runner. The process was simplified and the final instrument panel produced by the gas injection molding was found to have improved dimension stability compared to the one produced by conventional injection molding.

• Transactions of Materials Processing
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• v.12 no.5
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• pp.498-503
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• 2003

The die for cold forging gets a very high axial load and radial pressure during processing and hence deforms considerably in the radial direction. This radial deformation of die becomes a important factor influencing the dimensional accuracy of a product. In order to obtain the product with highly accurate dimension, therefore, it is essential to acquire some information on elastic deformation of the die and the product. The study has been performed for the relation of the deformation between the die and the product in backward extrusion. The strain of the die has been given by the simple experiment using the strain gauges attached to the outer surface of the die. Also the history of the deformation of the die and the product has been given by the experiment and Lames' formula. The results has been compared with the previous another method. The study has given useful results for the deformation history of the die and the product through the experiment and Lame's formula in backward extrusion, which can be applied in the die design for the product with accurate dimension.

• Journal of the Korean Society for Precision Engineering
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• v.12 no.8
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• pp.63-72
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• 1995

Closed-die forging of spur gears with hollow cylindrical billet has been analysed by using the upper-bound method. A kinematically admissible velocity field has been developed, wherein, an involute curve has been introduced to represent the forging die profile. In the analysis, the deformation region has been divided into nine zones. A constant frictional stress has been assumed on the contacting surfaces. Utilizing the formulated velocity field, numerical calculations have been carried out to investigate the effects of various parameters, such as module, number of teeth and friction factor, on the forging of spur gears. Hardness and accuracy of forged gears are measured. The following results have been obtained: (1) It is verified that an axisymmetric deformation zone exists between root circle and center of gear through forged gears. (2) The average relative forging pressure is predominantly dependent on the number of teeth and increases near the final filling stage as the addendum modification coefficient increases. (3) Close agreement was found between the predicted values of forging load and those obtained from experimental results.