• Journal of the Korea Academia-Industrial cooperation Society
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• v.9 no.6
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• pp.1726-1732
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• 2008

Injection molding is one of plastic forming technology which can easily mass-produce plastic parts with various and even complex shape. The technology has lots of difficulties in making a good part due to phase change of material, high applied pressure, and fast melt flow speed in the cavity. To overcome the problems, they had to make trial and error method until the CAE(Computer Aided Engineering) could be a tool for concurrent engineering. In this paper, we investigate the optimal design for a plastic DVD tray part by systematic approach of the commercial CAE program. In design, we should consider two objectives which are both dimensional stability and cost-down. The dimension of the part is crucial because the tray should carry a DVD correctly, but the part is too thin to injection-mold easily. In order to improve the moldability, the mold is designed in the form of stack mold which is a kind of 4 hot runner system. In first, we changed the stack-mold system with one hot-runner to cost down, and decided the optimal position of the gate. After that, we investigate the effect of both the layout of cooling channels and the cooling temperature on the shrinkage of the DVD tray. A optimal simulation approach, the gate design is 2Gate#3 and the layout is Case2 cooling line as the optimal temperature of $70^{\circ}C$. The Moldflow and PC+ABS are used for the CAE program and material respectively.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.12 no.3
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• pp.1051-1057
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• 2011

By the recently developed GMP(Glass Molding Press) process, aspheric glass lenses are widely used in many optical applications such as digital cameras, optical data storages and electrical devices etc. The GMP process can economically produce complex shaped glass lenses with high precision and good repeatability. This study deals the optimization of molding conditions for aspheric glass lenses in progressive GMP process through Design Of Experiment(Taguchi method). Tree main factors for molding conditions were selected based on pressure, temperature and cooling time at 1st cooling stage. From the analysis of experiments which were preformed with 3-cavity glass mold, it was revealed that the cooling time was the most sensitive parameter for form accuracy(PV) in progressive GMP process.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.11 no.4
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• pp.1361-1366
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• 2010

This research aims to develop polymer composites which can be used for PEMFC separators by injection molding process. Considering the moldability and stiffness, we used PPS(Poly(phenylene sulfide)) and PP(Polypropylene) as base resin. In order to improve electrical conductivity and physical properties, we chose glass fiber, carbon fiber, carbon black, and both expanded graphite and synthetic graphite. The 3 type composites are prepared for injection molding of PEMFC separators. and CAE(Computer Aided Engineering) analysis was conducted to optimize injection processing parameters(injection pressure, heat time, mold temperature etc.). We did successfully fabricate the separators by injection molding, and measure the electrical conductivity of the samples by using four point probe device. Conclusively, PP/SG/CB composite showed better both electrical conductivity and moldability than the others.

• Transactions of the Korean Society of Mechanical Engineers
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• v.16 no.11
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• pp.2082-2089
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• 1992

An experimental study on forging an axi-symmetric dome type of AISI4130 was carried out using modeling material. In order to verify the validity of the experimental data, a similarity study between plasticine and AISI4130 has been made. Friction conditions were characterized by ring test for the various lubricants. For the closed-die forging experiments of an axi-symmetric dome type of AISI4130 using the plasticine, various cylindrical billets with different aspect ratios were forged and different flash width to thickness(W/T) ratios were used in order to determine the optimum forging conditions. As W/T ratios decrease forging loads decrease while excess volumes increase. It was found out that the experimental results reproduce the similiar results available in the literature. As a result of these experiments, it was construed physical modeling is an excellent tool for forging process simulation at a practical level.

• Journal of the Korea Convergence Society
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• v.10 no.7
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• pp.169-174
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• 2019

Because the warm and cozy demand of automotive driving seat increases, the research development of heating seat has been actively made. In this study, the thermal stress analysis and the structural analysis were carried out with three kinds of heating seats of A, B and C. By executing the thermal analysis with the same material, model A was shown to have the heat transfer better than model B or model C at the study result. So, it could be seen that the heat transfers became different each other though models had the same material according to the configuration of product. Adding the hot wire in order to expect the safer heating can be better heating, but there is the limit on the aspect considering the capability in contrast to the price of product. Generally, model B is thought to be safest thermally than model A or model C in every respect. As the design data of the automotive heating seat product with the durability and safety acquired by this study result are used, the artistic environment can be promoted by being grafted onto the automotive driving seat.

• Journal of Korea Foundry Society
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• v.43 no.4
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• pp.187-193
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• 2023

Shell core making is an excellent process in terms of formability and desanding, but when the molten aluminum comes into con- tact with the shell core, gas generation by pyrolysis of the resin is inevitable. In addition, when the ventilation is inadequate, pores will remain inside the casting, which can directly lead to defects of the casting. While studies on the gas generation behavior of shell core making have been reported, the modeling of gas generation has not been extensively investigated. We will develop a gas evolution analysis method that considers the relationship between temperature and gas quantity for the core to be developed. We then use the developed method to analyze the flow and solidification behavior of metal molten metal during core mold design and low-pressure casting of cylinder head products, and predict the occurrence of casting defects to derive a casting method that min- imizes the occurrence of defects.

• Journal of Korea Foundry Society
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• v.17 no.6
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• pp.608-614
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• 1997

The effect of mold preheating temperature on the microstructure such as grain size, eutectic silicon morphology was investigated for the Al-7wt%Si-0.3wt%Mg alloy. Microstructural variations have been characterized as a function of Sr addition and cooling rate during solidification. Microstructures were correlated with cooling rate, local solidification time and eutectic nucleation temperature, etc. In this study, Sr addition caused increase of local solidification time, undercooling and reduction of eutectic plateau temperature. In logarithmic scale, local solidification time was in inverse proportion to cooling rate. Eutectic nucleation temperature was in inverse proportion to cooling rate of logarithmic scale. Increasing the cooling rate refined dendrite arm spacing and eutectic silicon. Dendrite arm spacing was logarithmically in inverse proportion to cooling rate. Without modifier addition, eutectic silicon was modified at cooling rate of $7^{\circ}C/s$ or higher.

• Transactions of Materials Processing
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• v.18 no.2
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• pp.107-111
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• 2009

Temperature variation happens in micro prism roll mold processing system during machining the prism pattern roll mold using manufacturing optical films of LCD (liquid crystal display). This temperature variation induces pitch errors of the prism patterns. The temperature variation displaces the positions of the diamond cutting tool on the roll which was coated by the copper. In order to prevent the pitch errors, the stabilizing the temperature of machining environment is needed. Therefore, the researching on the temperature variation of the ultra-precision roll mold processing system on the machining of micro prism rot 1 mold is needed. In this paper, the temperature variation of micro prism roll mold processing system is researched, the influence is analyzed, and the study for reducing the pitch errors carried out.

• Proceedings of the KSME Conference
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• 2007.05a
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• pp.1542-1547
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• 2007

Laser surface treatment technologies have been used to improve characteristics of wear and to enhance the fatigue resistance for mold parts. The optical lens with the elliptical profile is designed to obtain a wide surface hardening area with a uniform hardness. The objective of this research work is to investigate the influence of the process parameters, such as power of laser and defocused spot position, on the characteristics of laser surface treatment for the case of SKD61 steel and SCM4 steel. From the results of the experiments, it has been shown that the maximum average hardness is approximatly 700${\sim}$780 Hv when the power, focal position and the travel of laser are 1,095 W, 0mm and 0.3 m/min, respectively. In samples treated with lower scanning speeds, some small carbide particles appear in the interdendritic regions. This region contains fine martensite and carbide in proportions which depend on the local thermal cycle.

• The Korean Journal of Rheology
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• v.8 no.3_4
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• pp.207-214
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• 1996

사출성형은 많은 장점과 유용성에도 불구하고 싱크마크나 휨과 같은 변형문제를 피 하기 어렵다. 이것은 성형품의 부위별 온도분포 및 냉각속도 차이에 의한 잔류응력에 기인 하는 것으로 구조가 복잡하거나 크기가 쿤 경우에 더욱 더 문제가 되기 쉽다. 이와 같은 문 제를 해결하기 위하여 성형품의 내부에 기포를 형성시켜 수지의 수축분을 기포의 성장으로 보상하여 주는 가스사출성형이 개발되어 많이 활용되고 있는 실정이다. 한편 일반 가스성형 과 달리 수지를 완전히 채운후 저압의 공기를 이용하여 기포를 발생시켜 수지의 체적수축분 을 보상해주는 PFP성형기술은 가스사출의 나점인 공기의 유동조절문제를 해결하고 비용이 저렴한 등의 잇점을 가지고 있다. 이 과정은 가스성형공정의 2차 침투과정과 매우 유사하나 아직까지 이에대한 이해나 연구는 매우 부족한 실정이다 본 연구는 기포의 성장이 수지의 체적수축에 의한 것이라는 가정에 근거하여 기포성장길이에 관한 모델링을 수행한 것이다. 실험결과와의 비교를 통하여 기본 가정에 대한 타당성을 검증하고 여러 인자들의 영향을 살 펴보았다. 본 연구는 PFP성형공정에 대한 이해를 증진시켜 금형설계 및 성형조건 설정에 대한 가이드라인을 제시하며 아울러 PFP공정에 대한 보다 체계적인 이해 및 일반가스성형 의 2차 침투과정 등의 관련 현상에 대한 이해 및 연구에 도움이 될것으로 기대된다.