화학공학소재연구정보센터
홈 로그인 로그아웃 연락처 사이트맵
Polymer(Korea), Vol.40, No.2, 175-180, March, 2016
DOI10.7317/pk.2016.40.2.175  Export Citation
투명 사출품에서 성형조건에 따른 복굴절 및 잔류응력의 분석
Analysis of Residual Stress and Birefringence in a Transparent Injection Molded Article for Molding Condition
우정우, 홍진수1, 김현구2, 류민영2, †
  • 서울과학기술대학교 대학원 제품설계금형공학과
  • 1한국타이어 중앙연구소
  • 2서울과학기술대학교 기계시스템디자인공학과
Jeong-Woo Woo, Jin-Su Hong1, Hyun-Ku Kim2, and Min-Young Lyu2, †
  • Department of Product Design Manufacturing Engineering, Graduate School of Seoul National University of Science and Technology, 172 Gongneung-dong, Nowon-gu, Seoul 01811, Korea
  • 1Hankook Tire Central R & D Center, Gajeongbuk-ro, Yuseong-gu, Daejeon 34111, Korea
  • 2Department of Mechanical System Design Engineering, Seoul National University of Science and Technology, 172 Gongneung-dong, Nowon-gu, Seoul 01811, Korea
E-mail:
초록
사출성형품에 형성된 잔류응력은 시간이 지남에 따라 제품에 변형이나 휘어짐을 일으키고 투명한 제품의 경우 복굴절을 일으킨다. 사출성형 중에 형성되는 잔류응력은 성형온도, 금형온도, 냉각조건, 보압조건과 같은 사출성형 조건에 의해 다르게 나타난다. 잔류응력의 측정방법 중 광탄성을 이용한 측정법은 다른 방법들에 비해 간편하고 쉽게 측정할 수 있는데 투명한 제품에만 적용이 가능한 방법이다. 복굴절 분포와 잔류응력의 크기를 PC, PS, 그리고 PMMA를 이용한 사출성형 시편을 통해 연구하였다. 그리고 컴퓨터 시뮬레이션을 통해 복굴절 패턴을 모사하고 실험결과와 비교하였다. PS 시편은 가장 높은 복굴절을 나타냈고 PMMA는 가장 낮은 복굴절을 보였다. 제품의 잔류응력은 게이트 근처에서 가장 컸고 게이트에서 멀수록 작았다. 사출성형에서 냉각시간이 길고, 사출온도가 높고, 보압시간이 길수록 제품 내에 잔류응력은 줄어들었다.
Residual stresses are developed during injection molding process and these cause a warpage and invoke a birefringence in a molded article. The levels of residual stresses are dependent of molding conditions, such as melt temperature, mold temperature, cooling condition, and packing condition. Among the residual stress measurement methods, the photoelasticity method is simple and convenience to measure compared with other methods. However this method can be utilized only for a transparent product. Birefringence and residual stress have been observed in injection molded polycarbonate (PC), polystyrene (PS), and polymethylmethacrylate (PMMA) specimens according to injection molding conditions. Computer simulation has been performed and compared with experimental observation of birefringence. PS specimen showed the highest birefringence whereas PMMA showed the lowest birefringence among them. Locations close to the gate showed higher residual stress than locations far from the gate. Long cooling time, high injection temperature, and long packing time reduced residual stress.
Keywords:residual stress;birefringence;injection molding;molding condition;transparent material
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