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Investigation of the Molding Conditions to Minimize Residual Stress and Shrinkage in Injection Molded Preform of PET Bottle  

Cho, Sung-Hwan (Samyang Central R&D Center)
Hong, Jin-Su (Graduate School of NID Fusion Technology, Seoul National University of Science and Technology)
Lyu, Min-Young (Department of Product Design and Manufacturing Engineering, Seoul National University of Science and Technology)
Publication Information
Polymer(Korea) / v.35, no.5, 2011 , pp. 467-471 More about this Journal
Abstract
PET bottle is manufactured by blow molding the preform, which is molded by injection molding. The neck part of the preform of PET bottle for juice or grain-based beverage is crystallized before blowing to improve heat resistance at the entrance of the bottle. However, residual stress, developed during injection molding of preform, prevents the crystallization. In order to release the residual stress in the preform, the preform is annealed after the injection molding. If the residual stress is reduced by optimizing the injection molding conditions of preform the annealing time would be shortened. In this study, the optimum conditions for minimizing the residual stress and increasing dimensional accuracy of the injection molded preform are suggested through CAE analysis. In order to optimize the molding conditions, minimizing residual stress and shrinkage, computer simulations have been carried out with help of design of experiment scheduling. Injection temperature, initial packing pressure and filling time were selected for control parameters. Residual stress was affected by injection temperature and filling time. Shrinkage was affected by injection temperature. It was found that maximum residual stress, distribution of residual stress and shrinkage were decreased by 22%, 40% and 25%, respectively at an optimum molding condition compared with the results of previous molding condition.
Keywords
preform; injection molding; residual stress; shrinkage; design of experiment;
Citations & Related Records
Times Cited By KSCI : 1  (Citation Analysis)
Times Cited By Web Of Science : 0  (Related Records In Web of Science)
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