赤外ふく射加熱支援による薄肉射出成形品の充_性の改善
Flow-ability Improvement for Thin Injection Molded Products by Infrared Irradiation
斉藤卓志・佐藤 勲・黒崎晏夫
Saito, Takushi / Satoh, Isao / Kurosaki, Yasuo
This paper deals with a model that can predict flow-ability improvements due to radiation heating for the injection molding process. The model is derived through considering the thermal energy balance within a molded product, and can provide a quantitative estimation without the need for complex heat transfer calculations or numerical simulation of the polymer flow. Experimental molds, equipped with a transparent window (heat-resistant glass), were used to mold simple disc shaped samples. Infrared radiation, which was provided by a high power infrared lamp, was introduced from the outside of the mold and directly irradiated the molten polymer to maintain its flow-ability during the filling stage. The weight of all the molded products were measured with an electronic balance to investigate the effect of the following molding parameters : wall temperature, melt temperature, flow rate of the melt, product thickness, radiation absorption coefficient, and irradiation intensity. Flow available time, meaning the time that the polymer melt can be kept flowing in the cavity, was introduced. It was calculated by considering the thermal energy balance that includes all the parameters listed above. The estimation of the molded product weight by the model agreed well with the experimental results under various molding conditions.
Key words: Injection molding / Radiation heating / Flow-ability / Convection heat transfer coefficient