• Design & Manufacturing
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• 제16권4호
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• pp.24-33
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• 2022

Fiber-reinforced plastics(FRPs) have excellent specific stiffness and strength, so they are usually used as automotive parts that require high rigidity and lightweight instead of metal. However, it is difficult to predict the mechanical properties of injection molded parts due to the fiber orientation and breakage of FRPs. In this paper, the fiber orientation characteristics and mechanical properties of injection molded specimens were evaluated in order to fabricate automotive transmission side covers with FRPs and design a rib structure for improvement of their rigidity. The test molds were designed and manufactured to confirm the fiber orientation characteristics of each position of the injection molded standard plate-shaped specimens, and the tensile properties of the specimens were evaluated according to the injection molding conditions and directions of specimens. A gusset-rib structure was designed to improve the additional structural rigidity of the target products, and a proper rib structure was selected through the flexural tests of the rib-structured specimens. Based on the evaluation of fiber orientation and mechanical characteristics, the optimization analyses of gate location were performed to minimize the warpage of target products. Also, the deformation analyses against the internal pressure of target product were performed to confirm the rigidity improvement by gusset-rib structure. As a result, it could be confirmed that the deformation was reduced by 27~37% compared to the previous model, when the gusset-rib structure was applied to the joining part of the target products.

• 한국표면공학회:학술대회논문집
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• 한국표면공학회 2014년도 추계학술대회 논문집
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• pp.29-29
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• 2014

최근 화석에너지 고갈 및 에너지 수요의 폭발적 팽창을 해결하기 위하여 경량화와 내마모 측면에서 고효율 시스템을 적용한 자동차 및 각종 성형 기기들이 개발되고 있다. 특히 장치의 고성능화라는 요구조건을 충족시키기 위해서는 금속가공산업에서 표면개질의 중요성이 부각되고 있다. 이러한 표면개질에는 일반적으로 표면의 성질을 개선하여 마모(abrasion) 및 국부 압력(local stress) 또는 피로(fatigue), 마식(wear and corrosion)에 견디게 하여 부품의 수명증대와 제품의 소형화에 기여하고 있다. 이러한 표면개질법에는 경질의 물질을 표면에 코팅시켜 재료표면의 특성을 향상시키는 방법과 금속의 표면에 다른 원소를 침투 및 확산시키는 방법으로 나눌 수 있다. 확산방법으로 침탄, 질화, 보로나이징, 크마이징 처리 방법 등이 있다. 상업적으로 가장 많이 사용되는 표면 개질법은 침탄기술로서, 고온에서 짧은 시간내에 물성 향상이 가능하지만, 강의 변태점 이상의 온도에서 진행됨으로서, 변형에 따른 문제가 발생되어 후처리를 필요로 하는 문제점을 가지고 있다. 반면, 질화법은 변태점 이하의 저온에서 철강 표면에 N을 침투시켜 강을 경화시키는 특징을 가진다. 변형이 적고 질소원자가 강내에 침투함으로 인해 내마모성, 내피로성, 내식성 등의 물리적 성질을 향상시키는 점에서 유리하여 각종 정밀 부품 및 자동차 부품, 금형 등에 많이 사용된다. 또한, 경도 향상 및 결정구조의 영향으로 코팅처리시 모재와 코팅 층의 밀착력 향상을 가져오면 이러한 이유로 코팅 층의 하지 층으로써 각광 받고 있다. 본 발표에서는 플라즈마 질화의 이해를 높이기 위해 관련 기술에 대한 전반적인 소개와 향후 플라즈마 질화 기술의 적용이 기대되는 침탄대체 적용 가능 부품, 침류질화 기술, PECVD 공정과의 접목 등 산업적은 응용 측면에서 응용 분야에 대한 소개를 진행하고자 한다.

• 한국산학기술학회논문지
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• 제19권7호
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• pp.50-55
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• 2018

압출기술에서 중요한 것은 금형의 설계 및 제작이며, 원하는 형태의 압출이 원활히 이루어지는 동시에 금형의 수명을 최대한 연장하고 효율성을 높이기 위한 금형의 설계가 필수적이다. 압출 온도, 압출 속도 등이 압출시의 주된 변수이며, 압출비 및 재료의 물성, 압출 형태에 따라 각기 다른 조건이 부가되어야 한다. 본 연구에서는 고속전철 내외장재 부품용 알루미늄 6xxx 계열 주조 합금의 압출공정에 대해 연구하였다. 6063, 6061, 6N01, 6005, 5083 and 6060 알루미늄 합금의 압출 금형 단면을 설계하였으며 이에 대한 실험을 실시하였다. 또한, 빌렛온도, 압출온도 및 재료의 변화에 따른 압출 압력과 같은 압출 조건들을 분석하였다. 6063 알루미늄 합금이 가장 낮은 온도와 압력에서 압출이 가능한 반면 6061 합금은 가장 높은 온도와 압력에서 압출이 가능하였다. 이들 실험결과로부터 수립된 조건들을 이용하여 성공적인 압출제품을 제조할 수 있었다.

• Design & Manufacturing
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• 제13권2호
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• pp.1-5
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• 2019

In this study, micro cellular injection molding of automobile head lamp housing with uneven thickness structure was performed to obtain improvement on deformation and light-weight of the part. The thickness of the presented model was uniformly modified to control the deformation of the molded part. In order to maximize the lightweight ratio, the model having an average thickness of 2.0 mm were thinly molded to an average thickness of 1.6 mm. GFM(Gas Free Molding) and CBM(Core Back Molding) technology were applied to improve the problems of the conventional foam molding method. Equal Heat & Cool system was also applied by 3D cooling core and individual flow control system. Warpage of the molded parts with even cooling was minimized. To improve the mechanical properties of foamed products, complex resin containing nano-filler was used and variation of mechanical properties was evaluated. It was shown that the weight reduction ratio of products with light-weighted injection molding was 8.9 % and the deformation of the products was improved from the maximum of 3.6 mm to 2.0 mm by applying Equal Heat & Cool mold cooling system. Also the mechanical strength reduction of foamed product was less than 12% at maximum.

• Design & Manufacturing
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• 제13권1호
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• pp.55-60
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• 2019

Smart-phone in the recently released high-end applied to the camera module is equipped with the most features auto focusing camera module. Also, auto focusing camera module is divided into voice coil motor, encoder, and piezo according to type of motion mechanism. Auto focusing camera module is composed of voice coil motor (VCM) as an actuator and leaf spring as a guide and suspension. VCM actuator is made of magnet, yoke as a metal, and coil as a copper wire. Recently, the assembly as yoke and magnet is made by human resources. These process has a long process time and it is difficult to secure quality. Also, These process is not economical in cost, and productivity is reduced. Therefore, an automatic assembly as yoke and magnet is needed in the present process. In this paper, we have developed an automatic assembly device that can automatically assemble yoke and magnet, and performed verifying performance. Therefore, by using the developed automatic assembly device, it is possible to increase the productivity and reduce the production cost.

• 한국산학기술학회논문지
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• 제4권3호
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• pp.164-167
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• 2003

본 연구에서는 무선부품의 일종인 cavity filter금형을 제작하여 도금용 ABS 수지와 PC/ABS alloy 수지를 사용하여 일반사출성형과 금형온도가 높은 MmSH방식, 두 타입으로 성형품을 제작하였다. 성형품의 수축률 변화는 MmSH 방식일 때 ABS 성형품의 단위캐비티 격막부분에서 수축률이 감소되었다. 중량변화는 ABS와 PC/ABS 성형품 모두 MmSH 방식일 때 증가하였고, 성형품 표면 거칠기는 MmSH 방식일 때 모두 거칠기가 감소되었다.

• Design & Manufacturing
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• 제14권2호
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• pp.34-41
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• 2020

Typical characteristics of medical device parts are that they can not be reused and there are many disposable products. Therefore, there is a need for an injection molding machine having excellent repeatability of molding conditions and a precision injection mold for mass production. Recently, the performance of an injection machine has made a remarkable evolution compared to the past. However, defects such as short-shot, flash, weld line, gas burning, warpage, and deformation, which are typical defects, still do not disappear at all. This is due to the lack of gas ventilation from the product cavities, even if the gas is smoothly vented from the sprue and runner of the mold. For this reason, the internal pressure of the cavity rises and is directly connected to the quality defects. In this study, an active gas vent system was designed to prevent defects due to trapped gas in the cavity. Since it can be easily adjustable in response to the molding conditions and the mold temperature changes, it is expected to improve productivity due to the reduction of the defective ratio.

• Design & Manufacturing
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• 제11권3호
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• pp.25-28
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• 2017

The production of carbon fiber reinforced thermoplastics(CFRTP) parts using an injection/compression molding process that differs from the conventionally used fabrication methods was investigated Before the application of composite molding in the injection/compression molding process, a simple compression molding experiment was performed using a hydraulic press machine to determine the characteristics of resin impregnation and to obtain a basic physical property data for the CFRTP. Based on these results, injection/compression molded specimens were manufactured and an additional insert/over molding process was applied to improve the impregnation rate of the molded specimens. The results demonstrated that the tensile strength of the molded parts using the faster injection/compression process was similar to that of a hydraulic press molded product.

• Design & Manufacturing
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• 제9권2호
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• pp.25-29
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• 2015

This paper presented characterization of spray velocity and angle of spray nozzle systems for cosmetic products. Diameter and length of nozzle orifice were chosen as shape factors of the spray system. Spray orifice of the spray pattern is a factor influencing the quality of the product. Fluid analysis was conducted by using "Fluent" to obtain spray angle and velocity. RSM (Response Surface Method) was used to approximate the relationship between these 2 factors and spray characteristics. To evaluate the proposed method, experimental work with existing was conducted and good agreement between simulation and experimental results.

• Design & Manufacturing
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• 제15권3호
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• pp.32-38
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• 2021

Plate-shaped works are one of the materials that can be applied to the entire industry due to their various shapes and sizes. Plate-shaped parts workpieces are thin and wide, and when processing is completed, they are often bent or deformed in various directions, making it difficult to produce normal products. In particular, this study intends to study the processing deformation and distortion of plate-shaped parts fastened to the jig during milling processing. In this study, a method for preventing deformation occurring in plate-shaped parts was derived through jig element change and CAE analysis, and this was applied to actual processing to produce products with stable dimensions. Through a finite element analysis experiment, it was found that installing two supports on the back of the plate-shaped part results in minimal deformation and the optimal distance between the two supports is 150 mm. Through this experiment, when processing a thin plate product, a support was installed in a direction opposite to the cutting force applied to the thin plate to prevent deformation of the product, thereby improving defects.