• 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.

• 소성∙가공
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• 제10권6호
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• pp.493-499
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• 2001

An optimal robust design methodology has been developed to minimize warpage in injection-molded pats. The response surface methodology was applied to obtain a functional relationship between design variables and warpage value, and the modified complex method was used as an optimization tool to search for an optimal design solution over prescribed design region. To attain robustness against process variations, Taguchi's SN ratio was introduced as the design metric. The proposed optimal design procedure was applied to an actual part, the Guide-ASF model of a fax machine, and the usefulness of the methodology was shown through the CAE simulation using a commercial injection molding software package.

• 한국정밀공학회지
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• 제29권6호
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• pp.648-653
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• 2012

Cavity pressure, an important factor in injection molding process, should be minimized to enhance injection molding quality. In this study, we decided the locations of valve gates to minimize the maximum cavity pressure. To solve this problem, we integrated MAPS-3D (Mold Analysis and Plastic Solution-3Dimension), a commercial injection molding analysis CAE tool, using the file parsing method of PIAnO (Process Integration, Automation and Optimization) as a commercial process integration and design optimization tool. In order to reduce the computational time for obtaining the optimal design solution, we performed an approximate optimization using a meta-model that replaced expensive computer simulations. To generate the meta-model, computer simulations were performed at the design points selected using the optimal Latin hypercube design as an experimental design. Then, we used micro genetic algorithm equipped in PIAnO to obtain the optimal design solution. Using the proposed design approach, the maximum cavity pressure was reduced by 17.3% compared to the initial one, which clearly showed the validity of the proposed design approach.

• 폴리머
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• 제24권6호
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• pp.837-844
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• 2000

본 연구에서는 반도체 봉지제로 사용되는 상용 EMC중 가속제의 함량이 다른 두 종류의 프리프레그에 대하여 그 경화거동을 등온 및 승온조건에서 시차 주사 역량계, 점도계 및 유전율 측정계를 이용하여 분석하였다. 경화반응 속도변수는 Kamal의 자동촉매 반응식을 이용하여 m+n을 2로 가정한 후 Ryan Dutta의 방법에 따라 계산에 의한 경화반응 속도의 예측 치와 실제 실험 데이터가 10$0^{\circ}C$를 제외한 나머지 온도에서는 잘 일치하는 경향을 나타내었다. 경화과정 중 겔화와 유리화와 같은 상 전이를 관찰하였으며 각각의 등온 경화온도에서 경화시간에 따른 유리전이 온도 ($T_{g}$ )를 측정하여 경화온도와 유리전이 온도가 같아지는 유리화점을 구할 수 있었고 절대온도와의 사이에 Arrhenius관계가 성립함을 확인하였다. 또한 평판형 전극을 이용한 DEA는 EMC의 경화 과정을 동정하는데 효과적으로 이용될 수 있음을 알 수 있었다. 같은 종류의 수지 시스템에서는 TTT diagram상에서 $_{gel}$$T_{g}$ 가속제의 농도에 상관없이 일정한 온도에서 나타남을 확인하였다.

• 한국산업융합학회 논문집
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• 제23권5호
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• pp.773-787
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• 2020

In the injection molding process, the controlling stability of products quality is a very important factor in terms of productivity. Even when the optimum process conditions for the desired product quality are applied, uncontrollable external factors such as ambient temperature and humidity cause inevitable changes in the state of the melt resin, mold temperature. etc. Therefore, it is very difficult to maintain prodcut quality. In this study, a system that learns the correlation between process variables and product weight through artificial neural networks and predicts process conditions for the target weight was established. Then, when a disturbance occurs in the injection molding process and fluctuations in the weight of the product occur, the stability control of the product quality was performed by ANN predicting a new process condition for the change of weight. In order to artificially generate disturbance in the injection molding process, controllable factors were selected and changed among factors not learned in the ANN model. Initially, injection molding was performed with a polypropylene having a melt flow index of 10 g/10min, and then the resin was replaced with a polypropylene having a melt floiw index of 33 g/10min to apply disturbance. As a result, when the disturbance occurred, the deviation of the weight was -0.57 g, resulting in an error of -1.37%. Using the control method proposed in the study, through a total of 11 control processes, 41.57 g with an error of 0.00% in the range of 0.5% deviation of the target weight was measured, and the weight was stably maintained with 0.15±0.07% error afterwards.

• Design & Manufacturing
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• 제12권2호
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• pp.22-26
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• 2018

In the automotive industry these days, plastic parts have been developed and replaced with plastic parts by maintaining the same function of existing press parts for a variety of reasons. Injection molding plastic parts are subject to molding defects due to various factors, among which the sink marks usually occur in the areas where bosses and ribs are installed. In this study, we analyzed the influence of various factors on the occurrence of sink marks by using the flow analysis of the forming analysis program(Moldflow analysis) using the rib model with the T-shape. Tests have shown that the greatest influence on the sink mark of cosmetic products is the thickness and pressure of the ribs, and the thickness of the basic moulding thickness of the product increases. However, it was considered that the resin temperature and the mold temperature do not greatly affect the occurrence of the sink mark.

• 한국정밀공학회지
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• 제30권2호
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• pp.216-222
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• 2013

This paper deals with the issue of kinematic modeling and analysis of a toggle mechanism. Based on the mathematic model of a conventional five-point type toggle mechanism. New five-point type toggle mechanism has been analyzed by computer simulation method. A sensitivity ratio has been defined and analyzed to compare its performance with four-point type toggle mechanism. A cycloidal motion has been applied to the cross head as an input and the motion of the moving platen is considered as an output. The effect of link design parameter as well as the type of toggle has been investigated by computer simulation to be available for industrial applications of injection molding machines.

• 한국기계가공학회지
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• 제14권6호
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• pp.90-97
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• 2015

Optimization of multi-quality characteristics in injection molded parts is very important, but it is sometimes difficult for part/mold designers. The objective of this study is to develop a practical design methodology for optimizing two-quality characteristics of injection molded parts. To attain this end, we developed a new design-range reduction algorithm based on Taguchi's orthogonal arrays for two characteristics. Then, the algorithm was integrated with commercial injection-molding simulation tools. A feature of the proposed methodology is that it allows field-designers unfamiliar with general optimization methods to be able to apply the methodology to their design problems with ease. Finally, we have applied the proposed design methodology to optimization of weldlines and deflections in an actual bezel model. The results show the usefulness of this methodology.

• Korea-Australia Rheology Journal
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• 제15권4호
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• pp.159-166
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• 2003

This study is an attempt to understand the birefringence and stress development in an injection molded disk. A computer code was developed to simulate all three stages of the injection molding process filling, packing and cooling by finite element method. The constitutive equation used here was compressible Leonov model. The PVT relationship was assumed to follow the Tait equation. The flow-induced birefringence was related to the calculated flow stresses through the linear stress-optical law. The predicted birefringence was in good agreement with the experimental results.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 2003년도 The Korea-Japan Plastics Processing Joint Seminar
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• pp.41-47
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• 2003

This study is an attempt to understand the birefringence and stress development in an injection molded disk. A computer code was developed to simulate all three stages of the injection molding process - filling, packing and cooling by finite element method. The constitutive equation used here was compressible Leonov model. The PVT relationship was assumed to follow the Tait equation. The flow-induced birefringence was related to the calculated flow stresses through the linear stress-optical law. The predicted birefringence was in good agreement with the experimental results.