• 소성∙가공
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• 제9권5호
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• pp.512-525
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• 2000

Designers are frequently faced with multiple quality issues in injection molded parts. These issues are usually In conflict with each other, and thus tradeoff needs to be made to reach a final compromised solutions. The objective of this study is to develop an automated injection molding design methodology, whereby part defects such as warpage and weld line are optimized. The features of the proposed methodology are as follows: first, Utility Function approach is applied to transform the original multiple objective problem into single objective problem. Second is an implementation of a direct search-based Injection molding optimization procedure with automated consideration of process variation. The Space Reduction Method based on Taguchi's DOE(Design Of Experiment) is used as a general optimization tool in this study. The computational experimental verification of the methodology was partially carried out for a can model of Cavallero Plastics Incorporation, U. S. A. Applied to production, this study will be of immense value to companies in reducing the product development time and enhancing the product quality.

• 유변학
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• 제4권2호
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• pp.138-147
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• 1992

사출성형충전공정에서 금형구조가 단섬유배향에 미치는 영향을 예측하기 위하여 수 치모사 프로그램을 개발하였다. 유한요소 /관찰 부피 방법에 복잡한 금형에서의 유동을 해 석하고 섬유와 섬유간의 상호작용을 고려한 섬유배향텐서 변화식을 이용하여 입자 추적법으 로 섬유배향분포를 구하였다. 수치모사 결과 금형 옆벽면과 내부 방해체의 주위에 있는 섬 유들이 전단변형의 영향으로 그들주위를 따라서 정렬되려는 경향을 보였다, 두 유동이 내부 방해체를 지나 접하면서 생성된 웰드라인을 따라서 단섬유들이 정렬되려는 경향을 나타내엇 다. 그리고 수축유동에서는 흐름방향으로 정렬되나 확장유동에서는 흐름방향에 수직으로 배 열되려는 경향을 확인하였다. 위아래 벽에 의한 전단변형의 영향으로 서로 다른두 배향구조 를 보여주는 skin-core 구조를 두께방향의 속도구배를 고려한 수치모사를 통하여 예측할 수 있었다. skin구조에서는 섬유들이 흐름방향으로 정렬되고 core 구조에서는 흐름방향에 수직 으로 배향되는 것을 확인하였으며 섬유상호계수값이 커질수록 임의 배향화하는 경향을 보였다.

• 유변학
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• 제5권1호
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• pp.49-64
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• 1993

사출성형충전공정에서 금형구조가 단섬유배향에 미치는 영향을 예측하기 위하여 수 치모사 프로그램을 개발하였다. 유한요소 /관찰 부피 방법에 복잡한 금형에서의 유동을 해 석하고 섬유와 섬유간의 상호작용을 고려한 섬유배향텐서 변화식을 이용하여 입자 추적법으 로 섬유배향분포를 구하였다. 수치모사 결과 금형 옆벽면과 내부 방해체의 주위에 있는 섬 유들이 전단변형의 영향으로 그들주위를 따라서 정렬되려는 경향을 보였다, 두 유동이 내부 방해체를 지나 접하면서 생성된 웰드라인을 따라서 단섬유들이 정렬되려는 경향을 나타내엇 다. 그리고 수축유동에서는 흐름방향으로 정렬되나 확장유동에서는 흐름방향에 수직으로 배 열되려는 경향을 확인하였다. 위아래 벽에 의한 전단변형의 영향으로 서로 다른두 배향구조 를 보여주는 skin-core 구조를 두께방향의 속도구배를 고려한 수치모사를 통하여 예측할 수 있었다. skin구조에서는 섬유들이 흐름방향으로 정렬되고 core 구조에서는 흐름방향에 수직 으로 배향되는 것을 확인하였으며 섬유상호계수값이 커질수록 임의 배향화하는 경향을 보였다.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2001년도 추계학술대회논문집A
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• pp.766-771
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• 2001

Gas-assisted injection molding is an innovative low-pressure injection molding technique that can provide numerous benefits such as reduced part warpage, excellent surface quality without sink marks, low injection pressure, and greater design flexibility. However, the adoption of gas-assisted injection molding may cause unexpected defects if the gas channel design is not conducted properly. The objective of this paper is to broaden the understanding of gas-assisted injection molding by summarizing the design procedures and experimental results of the gas-assisted injection molding of a 17" flat monitor front cover. The gas channels were designed by using Moldflow(MF/GAS) simulations and a 450 ton injection molding machine with a 5 stage pressure control gas kit was used in the experiments.

• 한국기계가공학회지
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• 제9권4호
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• pp.32-37
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• 2010

One of the most common engineering processes using plastics is the injection molding. In addition, plastics are utilized over the entire areas in our life including cars and home appliances among others for their characteristics with no deterioration even after a long time, as well as for their light weights in addition to their good durability. This paper aimed to minimize defects through prior analyses on the weld line, air traps, filling time, molding temperature and deformation patterns among others while carrying out interpretations on the cooling, filling and deformation in the injection process using the moldflow for rear lamp reflectors among components for a car in making parts through the coating process after injection.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2000년도 추계학술대회 논문집
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• pp.608-611
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• 2000

This study is for stabilizer, a parts of automotive suspension system, that would be changed to Plastic Material. The part is designed and analyze by PRO-E. The position of Weld Line is founded by the C-mold, computer software with FEM. Then a Mold is designed by consideration with locating Weld Line. Mechanical property tests, such as tensile test, compression test, ball pull-out test, fatigue test and durability test are done the part by SAE test spec. Most of all the result of the tests show over requirement result without the compression test.

• 한국생산제조학회지
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• 제20권5호
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• pp.659-665
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• 2011

Recently, the plastic resin such as PC, ABS are widely used in IT market. Especially, in most cases the keypads mounted on the mobile phone are the dual-injection-plated type. Environmental regulation is based on the quality of injection-molded products and the minimum process steps are required to avoid the plating defects. Various parameters to produce the injection-molded plastic products make it difficult to obtain the desired stability. However, the past experience and the use of CAE analysis make it possible to predict the problems occurred in injection molding process. Especially, the problems of the weld lines such as runner balancing, bending, deformation and forming defects can be solved systematically and minimized by CAE analysis. Through this study, the non-uniform volumetric shrinkage and the difference in temperature distribution induce the deformation and the high value of stress causes the problems such as crack.

• 한국정밀공학회지
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• 제30권12호
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• pp.1295-1301
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• 2013

The cause of flow mark defect is known as non-uniform temperature of mold surface when the flow front meets the cold cavity. The exact definition and classification of Flow mark is not clear because the mechanism of flow mark is not figured out till now. Any injection molding analysis software can not predict the flow mark phenomena. To solve weldline and flow mark defects, the gate thickness is reduced to increase the melt front velocity and the melt front velocity of the flow mark area is increased from 82.3mm/s to 104.7mm/s. In addition, the bulk temperature of the flow mark area is increased from $178.3^{\circ}C$to $215.2^{\circ}C$ by adding a cold slug well. The flow mark phenomena can be greatly reduced by increasing the flow front velocity and elevating the bulk temperature.

• 한국정밀공학회지
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• 제20권2호
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• pp.25-32
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• 2003

Molding properties of etched surface pattern are presented. Injection molding has given attention on improving dimensional accuracy and productivity. However, the molding of etched surface pattern on plastic parts is not researched relatively for its additional values, which can meet design function and customer's attraction. Specimens, whose surface patterns are made by print-type etching, are investigated. The molding properties of surface pattern are estimated with roughness deviation of surface pattern on part and mold. The etching properties are related to physical properties of plastic materials and surface roughness of etched pattern. Also, flow mark and gate location can give influence on surface pattern molding. The experimental result can contribute to good molding of surface pattern in injection molding.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2006년도 춘계학술대회 논문집
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• pp.357-358
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• 2006

Importance of using an injection molding analysis has been increased. However the application of it has not been increased because the results of analysis do not sometime match to practical molding. Therefore, the difference of flow analysis and practical molding should be decreased. This study presents reasons of the difference for the location of weld-line in the flow analysis and practical molding on automobile bumper molding.