熱可塑性樹脂の射出成形における適応制御一型内圧力制御の有用性の検討一
Adaptive Process Control in Injection Molding-Effectiveness of Cavity Pressure Control-
焼本数利・前川善一郎・_田泰以・酒井忠基
Yakemoto, Kazutoshi / Maekawa, Zenichiro / Hamada, Hiroyuki / Sakai, Tadamoto
The effectiveness of cavity pressure control in the injection molding process was investigated with regard to reproducibility in product quality.
Since injection molding is generally carried out under varying mold temperature or melt temperature condition, the effectiveness of a process control should be considered with relation to temperature variations. From the analysis of the relationship among temperature, pressure, and product weight, it was derived that cavity pressure control can be effective in improving the reproducibility in product weight if the product weight fluctuations caused by cavity pressure variations are larger than those caused by material temperature variations in the cavity.
To confirm the analytical results above, experiments were carried out under both varying and constant temperature conditions. When the melt temperature was varied, the product weight fluctuations caused by pressure variations were relatively large, and the control was effective. On the other hand, when the mold temperature was varied, the product weight fluctuations caused by the temperature variations were relatively large, and the control was not effective. Under constant mold temperature and melt temperature conditions, differences in product weight fluctuations with and without the control were not observed.
In conclusion, it was confirmed that cavity pressure control can be effective under stable mold temperature conditions. And when the control can not be effective, necessity to develop the control which takes temperature variations into consideration was suggested.
Key words: Injection Molding / Cavity pressure control / Product weight / Mold temperature / Melt temperature