ブロー成形技術への粘弾性流動解析の適用第1報 パリソンのスウェル比についての検討
Application of Numerical Studies on Polymer Melt Flow to Blow Molding TechnologyPart 1 A Study on the Parison Swelling Ratio
寺田耕輔・山部 昌・田上秀一・梶原稔尚・船津和守
Terada, Kousuke / Yamabe, Masashi / Tanoue, Shuichi / Kajiwara, Toshihisa / Funatsu, Kazumori
In the blow molding process, pellets are melted and pumped by a screw device into an accumulator. By plunger extrusion, the polymer melt flows into an annular die and emerges vertically downward to form a parison.
The shape of the parison (diameter, thickness, length) should be controlled by setting the molding conditions (shape of annular die, flow rate, temperature, polymer properties, etc.) to make a successful blow molding process. Therefore, a method for predicting dimensions of the parison is necessary to research the best molding conditions.
We performed numerical studies of polymer melt flows in several types of real annular dies using the finite element method. The constitutive model for polymer melts that we used was the Giesekus model.
It was found that the relationship between the measured swelling ratio of parisons in these annular dies and the normal stress difference at the exit dies from analysis results could be expressed by a function. The function was independent of the geometry of the die in this study. This function may play an important role for the pre-diction of shape of parisons.
Key words: : Polymer melts / Blow molding / Giesekus model / Annular die / Swelling ratio