• 소성∙가공
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• 제30권3호
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• pp.149-156
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• 2021

Fine blanking is a high-precision process combining principles of metal stamping and cold forming. Unlike conventional metal stamping, fine blanking uses a special triple action such as V-ring force, counter force, shearing force. This study performed the effect of pocket-shaped compression molding on the mold life of the fine blanking using the 7.4mm thick SM45C material. In order to determine the lifespan of the punch and die in the fine blanking molds, a trial mold was manufactured and various punch materials were selected to perform the mold life test. A study on the life of a fine blanking mold by applying a thick plate material was experimentally performed through a mold test.

• Design & Manufacturing
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• 제17권3호
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• pp.41-47
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• 2023

This paper presents the development of a controller that can control the temperature of an heating system based on a thermoelectric module. Temperature controller using Peltier has various external factors such as external temperature, characteristics of an aluminum plate, installation location of temperature sensors, and combination method between the aluminum plate and heating element. Therefore, it is difficult to apply the simulation and simulation results of heating system using Peltier at control algorithm. In general, almost temperature controller is using PID algorithm that finds control gain value heuristically. In this paper, it is proposed mathematical model that explain correlate between the temperature of the heating system and input voltage. And then, optimal parameter of estimated thermal model of the aluminum plate are searched by using genetic algorithm. In addition, based on this estimated model, the optimal PID control gain are inferred using a genetic algorithm. All of the sequence are simulated and verified with proposed real system.

• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2007년도 춘계학술대회
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• pp.89-92
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• 2007

The metallic bipolar plate in PEMFC is widely used for automotive driving because of its advantages, i) high strength, ii) high chemical stability, iii) low gas permeability and iv) applicability to mass production. Especially, the metallic bipolar plate which is manufactured with the sheet metal stamping process can be applied in automotive PEMFC with less volume and weight because of its thin thickness but the formability and springback problems arise in real manufacturing process. The assessment for formability and springback of metallic bipolar plate should be performed before making stamping die sets. In this work, the methodology for determining the allowable draft angle of flow passage is introduced by using finite element analysis. In analysis results, as the draft angle of flow passage increase, the major strain and thinning is increase with exponential function. The allowable draft angle without fracture is presented by fitting the results. Additionally, the staking results with manufactured metallic bipolar plates by stamping process is presented.

• 소성∙가공
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• 제27권1호
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• pp.18-27
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• 2018

As one of the functional metal parts in steam turbine diaphragm assembly, the hollow-partitioned turbine nozzle (stator) has large and thick geometries, as well as an asymmetric configuration. Therefore it is hard to support a metal blank in the die cavity. To ease this situation and control posture and position of metal blank (workpiece), a blank support structure is newly introduced. The blank support structure is basically composed of enlarged arms from the blank, guide pins and linear bearings. It can help to control the intermediate blank without a critical sliding phenomenon. The operation mechanism of this blank support structure, during thick plate forming for the hollow-partitioned turbine nozzle stator, is first evaluated. A series of FEM-based numerical simulations, with respect to the width of the guide arm as geometric design parameters, are carried out to investigate its applicable range. As the results, it is observed the blank support structure for this thick plate forming can guide the workpiece to have stable posture during the plate forming process.

• 한국식품과학회지
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• 제23권2호
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• pp.212-216
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• 1991

유과제조시 가장 걸림돌이 되는 꽈리치기 공정과 반데기 제조공정의 연속공정화 및 표준화를 위하여 기존 chopper의 구조를 변경하고 conveyer를 연결하여 기계화 가능성을 시도하였다. Plate와 die를 새로 제작하여 실험한 결과 꽈리치기 및 반데기를 연속적으로 제조할 수 있었으며, 그 품질도 기존방법에 비하여 차이가 없었다. 반데기의 두께와 폭은 conveyer belt의 속도를 조절하므로써 가능하였으며, chopper에서 반죽의 토출량이 221.8g/sec($Slit\;:\;5{\times}50.5\;mm$)일 때 conveyer의 속도는 87.3 mm/sec가 바람직하였다. Chopper의 구성에서 knife나 plate의 모양 등은 꽈리치기 효과에 큰 영향을 주지 않았으며, 건조 후 반데기의 두께는 $3.0{\sim}3.5\;mm$인 경우 가장 좋은 유과품질을 얻었다. Chopper를 통과하는 횟수는 품질에 큰 영향을 주지 않으나 전연 꽈리치기 하지않은 경우 조직은 대단히 유약하였다.

• 반도체디스플레이기술학회지
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• 제19권3호
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• pp.30-35
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• 2020

A microlens has been fabricated by various methods such as a thermal reflow, hot embossing, diamond milling, etc. However, these methods require a relatively complex process to control the microlens shape. In this work, we report on a simple and cost-effective method to fabricate a cylindrical microlens (CML), which can diffuse light widely. We have employed a slot-die head with the dual plate (a meniscus guide with a protruded μ-tip and a shim with a slit channel) for coating of a narrow stripe using poly(methyl methacrylate) (PMMA). We have shown that the higher the coating gap, the lower the maximum coating speed, which causes an increase in the stripe width and thickness. The coated PMMA stripe has the concave shape. To make it in the shape of a convex microlens, we have applied the thermal reflow method. When the stripe thickness is small, however, its effect is negligible. To increase the stripe thickness, we have increased the number of repeated coating. With this scheme, we have fabricated the CML with the width of 223 ㎛ and the thickness of 7.3 ㎛. Finally, we have demonstrated experimentally that the CML can diffuse light widely, a feature demanded for light extraction efficiency of organic light-emitting diodes (OLEDs) and suppression of moiré patterns in displays.

• 한국기계가공학회지
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• 제12권6호
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• pp.30-36
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• 2013

An FFD(flexible fine die) is an embossed mold that consists of a thin plate ranging from 0.6 to 3 mm in thickness. FFDs are primarily used for cutting LCD films and F-PCB sheets. In the high-speed micro-milling process of flexible fine dies, the lubrication and cooling of the cutting edges is very important from the aspect of eco machining and cutting performance. In this paper, a comparative study of tool wear and surface roughness between cutting fluid and hybrid lubrication for eco-machining of FFD was conducted for processes of high-speed machining of highly hardened material (STC5, HRC52). Especially, the incorporated fluid method for eco machining, in which the cutting performances can be simultaneously measured, was introduced. The machining results show that hybrid lubrication, instead of conventional cutting fluid, leads to excellent tool wear and surface roughness and represents the proper conditions for eco micro-machining of flexible fine dies.

• Design & Manufacturing
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• 제8권1호
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• pp.40-44
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• 2014

As a rotating machine element, plastic gears are more and more widely used in such as industrial machine element, since plastic gear is lighter, higher wear-resistance, and higher vibration absorbing ability than metal gears. When operating plastic parts, tooth breakage and fatigue life shortened due to increasing number of applying load and tooth flank temperature rising, such that accuracy of plastic gears is divided from allowable range to cause vibration and noise. On this study, a internal plastic gears are developed which improved the filling balance molding process by a new injection mold structure. The new mold structure called HR3P(hot runner type 3plate mold). As the result from this studies, we obtained a very accurate roundness internal gears by using design of experiment.

• Design & Manufacturing
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• 제11권1호
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• pp.14-18
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• 2017

Recently, the injection-molded products are lighter, and thinner than ever. In this work, Injection molding simulation was conducted to analysis the filling pattern imbalance in high speed injection molding process for thin-wall injection component, 8 inches LGP. Numerical analysis shows that shear heated polymer near the side wall causes filling imbalance between center and side of cavity. Short shot experiments were conducted and compared with simulation results. Filling imbalance ratio showed a tendency to increase for wider fan gate.

• 한국생산제조학회지
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• 제5권3호
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• pp.50-57
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• 1996

This study was performed the blankholding force and Vee-ring effects on blanking characteristics, such as maximum blanking force, burnish, dish-shape, hardness. etc. in fine-blanking die by the experimental method. Two types of aluminum (Al.1050-O, Al, 5052-H) Such as annealed and unannealed materials were used for the experiment. In order to get a hydrostatic pressure effect, the clearance was set to 0.5% of the thickness of strip, and the counter punch and stripper plate with Vee-ring was set-up. While this experiment was carry8ing out, the average blanking velocity was constant (37.5mm/sec). As a result of this study, we got a good surface roughness and a dimensions, the good squareness and the reduction of dish-shape could be obtained, and also the additional results obtained were such that the hardness of shear plane was increased and the maximum blanking force was reduce in the condition of Vee-ring height of 1.0~1.5mm, and blankholding force of 1200kg.