Polymer(Korea) (폴리머)

The Polymer Society of Korea (한국고분자학회)
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Measurement of Residual Stress Using Photoelasticity and Computer Simulation of Optical Characteristics in a Transparent Injection Molded Article

광탄성을 이용한 투명한 사출성형품의 잔류응력측정 및 광학적 특성의 컴퓨터 모사

  • Hong, Jin-Soo (Graduate School of NID Fusion Technology, Seoul National University Science and Technology) ;
  • Park, Seo-Ri (Graduate School of NID Fusion Technology, Seoul National University Science and Technology) ;
  • Lyu, Min-Young (Department of Product Design and Manufacturing Engineering, Seoul National University of Science and Technology)
  • 홍진수 (서울과학기술대학교 NID융합기술대학원) ;
  • 박서리 (서울과학기술대학교 NID융합기술대학원) ;
  • 류민영 (서울과학기술대학교 제품설계금형공학과)
  • Received : 2010.04.22
  • Accepted : 2010.10.05
  • Published : 2011.01.25
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Abstract

Pressurized high temperature plastic resin flows into the cavity of mold and is solidified in injection molding process. Residual stress is being developed in injection molded part because of high temperature variations and high pressure. Developed residual stress relaxes as time goes. Consequently this makes part deformed and deteriorates quality of product. A measurement method of residual stress for injection molded transparent articles has been investigated using photoelasticity. Light, a composite of electromagnetic waves, is purified into a single wave by a polarized film. When this wave passes through the specimen, birefringence is developed according to the level of residual stress in the specimen and color fringed pattern appears after the second polarized film. Residual stress in the injection molded transparent flat a part has been measured quantitatively using the color fringed pattern. Optical characteristics have been a part also predicted by computer simulation and compared with experimental results.

사출성형은 고온의 수지를 고압으로 금형에 충전하고 냉각하여 제품을 만드는 공정으로 큰 온도차이와 고압에 의해 성형품에 잔류응력이 형성된다. 이러한 잔류응력은 시간이 지남에 따라 이완되면서 제품에 변형을 일으켜 형상 품질을 저하시킨다. 본 연구에서는 광탄성 장치를 이용하여 투명한 사출성형품의 잔류응력을 측정하는 방법을 연구하였다. 빛은 전자파처럼 진행하는데 편광필름을 통과하면 하나의 파장만이 진행하게 된다. 그 파장이 시편을 통과하면서 시편에 존재하는 잔류응력 때문에 복굴절이 형성되고 두 번째 편광필름을 통과하면서 다양한 색의 패턴을 보이게 된다. 이 색의 패턴을 이용하여 사출성형으로 제작된 사각평판의 잔류응력을 정량적으로 측정하였다. 또한 컴퓨터 해석을 통해 사출성형품의 광학적 특성을 예측하였으며 실험과 비교하였다.

Keywords

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