• 한국주조공학회지
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• 제20권6호
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• pp.400-406
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• 2000

Computer simulation for the predictions of casting defects is very important to produce high quality castings with less cost. Complicate shaped Al solenoid housing part was selected to be cold chamber die cast and a numerical simulation technique was applied for the optimization of the chill vent position and gating. A first design led to insufficient central flow. This flow left the last filled areas falling into the inner portion of the part. And last filled area did not fit the chill vent position. So these resulted in a high possibility of air entrapment in the casting and the design was not proper for the part. The design was improved by using a proper gating system, a more chill vent and proper overflow positions. New design provided a homogenous mold filling pattern and the last filled areas that being located at the overflow and chill vent. Casting plan which produce good quality solenoid housing part was established by using the computer simulation.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 2002년도 금형가공 심포지엄
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• pp.125-131
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• 2002

Surface defects in injection molded parts are due to the unsteady flow of polymer melt which are related to the geometries of cavity and gate, the operational conditions of injection and the rheological properties of polymer. In this study we have examined jetting phenomena in injection molding process for three kinds of PCs which have different molecular weight and structure, PBT and PC/ABS alloy with several injection speeds. We have used various cavity shapes that are tensile, flexural and impact test specimens with various gate and cavity thicknesses. Through this study we have observed that the formation of surface defect associated with jetting during filling stage in injection molding is strongly related to die swell. This means that the jetting is strongly affected by the elastic property rather than the viscous property in viscoelastic characteristics of molten polymer. Large die swell would eliminate jetting however, the retardation of die swell would stimulate jetting. In the point of mold design, reducing the thickness ratio of cavity to gate can reduce or eliminate jetting and associated surface defects regardless of magnitude of elastic property. It also enlarges process window that can produce steady flow of polymer melt in injection molding.

• 한국지능시스템학회논문지
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• 제18권4호
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• pp.488-493
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• 2008

본 논문은 연속 주조 공정에서의 용강 높이에 대한 수학적인 비선형모델을 유도하는데, 여기에는 용강 높이, 몰드내의 입출력 유량, 스토퍼의 위치와 입력유량의 관계 등이 고려되었다. 비선형 모델은 MATLAB을 사용하여 구현되었으며 실제 데이터와 비교하여 수학적 모델이 유효함을 확인하였다. 구현된 비선형 모델을 사용하여, 퍼지 시스템에 의하여 변화하는 $K_p$값을 가지는 퍼지 PI 제어기를 사용하여, 기존에 사용되던 PI 제어기보다 나은 제어 성능 및 외란에의 강인성을 가짐을 시뮬레이션으로 보였다.

• 한국정밀공학회지
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• 제22권6호
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• pp.55-60
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• 2005

This paper has been focused in developing of plastic lens with ultra-precision and low birefringence ability using by injection molding simulation tools. The simulation tools, $3D-Timon^{TM}\;and\;Asu-Mold^{TM}$ were applied to visualize indirectly the flow pattern of melted polymer enter the mould and the simulation results are verified as compared with the experimental results. Birefringence and polarized light generated in injection molding process was also calculated for each injection conditions and compared with .the pictures of experimented optical lens go through the polarized light plates device. A spherical radius of plastic optical lens transcribed from profile of mould core surface was measured to estimate the geometrical accuracy fer the each injection conditions. It is confirmed that the simulation results about flow pattern and polarized light area coincided in experimental results. It is known that increasing in thickness shrinkage at center of lens, the spherical radius is larger from comparing the graph measured spherical radius and the thickness shrinkage at center of lens

• 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.

• 한국융합학회논문지
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• 제11권9호
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• pp.175-180
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• 2020

본 연구에서는 화물 운송 차량들을 모델링하였고 화물 운송 차량의 화물칸 및 윈드 디플렉터의 유무에 따른 유동해석을 수행하였다. Model A, B, C 모두, 100km/hr의 운행 속도를 기준으로 하여, 모델 형상의 윗부분에서 58m/에서 59m/s 사이로 가장 높은 유동 속도가 나타났다. Model A, B, C 세 모델들 모두 모델 형상의 앞부분에서 652Pa에서 671Pa사이에 공기저항의 압력이 가장 높게 나타났다. Model A의 최대 압력은 Model B 및 C에 비하여, 작게 나타나서, 속도에 대한 유동 저항이 가장 적게 작용한 것으로 사료된다. 따라서 Model A가 유류비 측면에서 공기 저항에 대한 유리한 조건을 가짐을 알 수 있다. Model C는 화물칸에서 급격하게 유동저항이 발생하는 Model B와 달리 유선형 형상의 윈드 디플렉터를 타고 공기가 조금 더 원활하게 흐르는 것을 확인할 수 있다. 따라서 각진 형상보다 유선형의 형상에서 공기저항 측면에서는 더 유리하다고 사료된다. 트럭 화물칸 및 윈드 디플렉터에 따른 운행중 공기흐름에 대한 해석 연구 결과를 적용함으로서, 본 연구가 실제적인 효율적인 설계와 미적인 융합에 적합하다고 보인다.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 2008년도 추계학술대회 논문집
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• pp.426-430
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• 2008

Hot shear-welding is a process of bonding two plates together by using shearing stress in a controlled manner. This study dealt with the hot shear-welding process of two aluminum plates. These two plates were piles up in the shear-welding mold. Due to the shearing stress, these two plates were cut off longitudinally, and meantime they were welded together. During this process the control of the surplus material flow is very important, and it can be realized by designing the overlapping length and the shape of the cavity. The commercial software Deform-3D was employed to predict the effect of these two factors. The overlapping length and the shape of the cavity that presents the optimum design was then developed to get a good shear-welding process.

• 한국기계가공학회지
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• 제14권2호
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• pp.87-92
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• 2015

The injection molding process is widely used in the production of most plastic products. In order to make metal-colored plastic products like those found in modern luxury home alliances, metallic pigments are mixed with a basic resin material for injection molding. However, process control for metal-colored plastic products is extremely difficult due to the non-uniform melt flow of the metallic resin pigments. In this study, the effect of process parameters on the quality of a metal-colored plastic product is evaluated. A rapid mold cooling method using a compressed cryogenic fluid is also proposed to decrease the content of undesired compounds within the plastic product.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 2003년도 The Korea-Japan Plastics Processing Joint Seminar
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• pp.33-39
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• 2003

Injection molding is widely used in producing various plastic parts due to its high productivity and the demand for high precision injection molded products is ever increasing. To achieve successful product quality and precision, the design of gating and runner systems in the injection mold is very important since it directly influences melt flow into the cavity. Some defects such as weld lines and overpacking can be effectively controlled with proper selection of gate locations. In the present study, the design of gate locations in injection molding of a dashboard for automobiles was carried out with CAMPmold, a PC-based simulation system for injection molding. A dummy runner was developed to simulate a runner system in order to increase the efficiency of the analysis. The numbers and locations of gates were varied in the present investigation as that an acceptable design was obtained in terms of reduced maximum pressure and clamping force.

• 대한기계학회논문집
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• 제11권6호
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• pp.1026-1035
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• 1987

본 연구에서는 두께방향에 따른 유동을 해석하는데 "fountain effect" 및 열 전달 현상을 동시에 고려하면서 진전하는 자유표면의 형상을 정확히 구하기 위한 유한 요소법을 이용한 수치해석법을 제안하고 그 방법을 적용하여 금형벽의 온도를 변화시 켜가면서 구체적인 유동특성을 해석하였다.특성을 해석하였다.