• 소성∙가공
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• 제21권1호
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• pp.5-12
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• 2012

The weight of the bipolar plate is one of the crucial aspects of improving power density in PEMFC stacks. Aluminum alloys have good mechanical properties such as density, electrical resistivity, and thermal conductivity. Furthermore, using aluminum in a bipolar plate instead of graphite reduces the bipolar plate cost and makes machining easier. Therefore in this study, an aluminum alloy was selected as the appropriate material for a bipolar plate. Results from feasibility experiments with the aim of developing fuel cells consisting of Al bipolar plates with multiple channels are presented. Dynamic loading was applied and the formability of micro channels was estimated as a function of punch pressure and die radius. Sheets of Al5052 with a thickness of 0.3mm were used. For a die radius of 0.1mm the formability was optimized with a sine wave dynamic load of 90kN at maximum pressure and 5 cycles of a sine wave punch travel. The experimental results demonstrate the feasibility of the proposed manufacturing technique for producing bipolar plates.

• 소성∙가공
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• 제14권3호
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• pp.207-214
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• 2005

Blanking process is widely used fur producing various structural parts. However, fine blanking technology is frequently used as a single step blanking operation with clean cut surface of a sheared surface because the fractured surface of parts causes serious problems in the final product and therefore it must be removed by the post-processing in case of the conventional blanking. In the present investigation, a fine blanking process was designed within the framework of progressive die to produce a carrier plate assembled within the auto transmission. Finite element analysis of the shearing behavior at the respective stage of the progressive fine blanking was conducted to validate the designed die parameters. Finally the designed progressive fine blanking process was experimentally evaluated by using the machined die.

• 한국주조공학회지
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• 제35권4호
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• pp.80-87
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• 2015

The Al die casting process has been widely used in the manufacturing of automotive parts when the process requires near-net shape casting and a high productive rate. However, porosity arises in the casting process, and this hampers the wider use of this method for the creation of high-durability automotive components. The porosity can be controlled by the shot condition, but, it is critical to set the shot condition in the sleeve, and it remains difficult to optimize the shot condition to avoid air entrapment efficiently. In this study, the 4.5 mm, 2.0 mm plate die castings were fabricated under various shot conditions, such as plunger velocities of 0.7 m/s ~ 3.0 m/s and fast shot set points of the cavity of -25%, 0%, 25%, and 50%. The mold filling behavior of Al melts in the cavity was analyzed by a numerical method. Also, according to the shot conditions, the results of numerical analyses were compared to those of die-casting experiments. The porosity levels of the plate castings were analyzed by X-ray CT images and by density and microstructural analyses. The effects of the porosity on the mechanical properties were analyzed by tensile tests and hardness tests. The simulation results are in good general agreements with the die-casting experimental results. When plunger velocity and fast shot set point are 1.0 m/s and cavity 25% position, castings had optimum condition for good mechanical properties and a low level of porosity.

• Design & Manufacturing
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• 제2권4호
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• pp.1-4
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• 2008

Micro pattern is applied to the light guiding plate(LGP) to enhance the uniformity of the brightness of the LCD. The micro cones are molded in intaglio on the surface of the LGP. The surface roughness of each cone was 40nm and 38nm in negative and positive die for laser ablation. In chemical etching, the surface roughness was 25nm, 24nm in negative and positive. And the surface roughness of negative and positive dies were 4nm and 5nm for LIGA-reflow process.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2006년도 춘계학술대회 논문집
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• pp.207-208
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• 2006

Sandwich structures, which are composed of a thick core between two faces, are commonly used in many engineering applications because they combine high stiffness and strength with low weight. In this paper, we have investigated the buckling protection of an inner structure plate and the useful corrugated configuration for contact, and the fabrication method of the inner structure plate for large area using the continuous molding process. Also, we have guaranteed the accuracy of the molding process through the micro corrugated mold fabrication and analyzed aspect properties of the inner structure plate fabricated for a large area using the partial mold process.

• 한국기계가공학회지
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• 제12권6호
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• pp.84-92
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• 2013

This study improves the formability in fine-blanking the lock plate of car seat belts using a low carbon steel(SM35C) plate. The optimal die design for the forming process is proposed using rules for process planning based on theories and field experiences. The optimal design is analyzed using commercial finite element software in order to solve the fracture problems in the extrusion process. Through the improved layout based on the FEM results, the fracture of the extruded part and the roll over problem are solved. Furthermore, it is demonstrated through the shown from experiments that the extruded part does not break in the modified die.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2005년도 추계학술대회 논문집
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• pp.279-284
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• 2005

The casting defects that are caused by molten metal were cold shut formation, entrapment of air, gas, and inclusion. But the control of casting defects has been based on the experience of the foundry engineers. In this thesis, the computer simulation analyzed the flow of molten metal. The quantitative analyses which proposed the effective mold design was executed Flow patterns of 0.15-0.16m/s molten metal in 15 mm thin plate casting were investigated in order to optimize die-casting process. As increasing ingate velocity in thin plate casting, cold shot was decreased. The parameters of runner shape that affected on the optimized conditions that was calculated with simple equation were investigated. These die casting process control techniques of automobile valve body mid-plate have achieved good agreement with the experimental data of tensile strength, hardness test, and material structure photographies satisfactory results.

• 산업공학
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• 제7권2호
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• pp.145-155
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• 1994

In this paper, we analyzed weak points of press process with the rolled thin flexible plate. The problems which are caused by the adhesion of blank on the surface of die and the separation of blank from scrap during its transportation after blanking were solved by the redesign of the structure of die and the development of special equipment for material handling. It is our purpose to make better the automation of blanking process and the safety for worker by the improvement of flexible material handling.

• 한국산학기술학회:학술대회논문집
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• 한국산학기술학회 2006년도 춘계학술발표논문집
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• pp.192-195
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• 2006

본 논문에서는 다이 플레이트(Die Plate)를 제작할 때 생산성 향상을 위해서 3D CAD/CAM 시스템을 적용하였다. 사용된 3D CAD/CAM 소프트웨어는 UG NX 3.0이며 생성된 NC 코드는 CNC밀링 및 와이어 컷 방전가공기에 전송되어 다이 플레이트를 자동 가공한다.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2011년도 춘계학술대회 논문집
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• pp.17-18
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• 2011