高分子溶融体の二重管押出しのダイスウェルシミュレーション
Numerical Simulation of Die Swell of Polymer Melts in Extrusion from Annular Dies
梶原稔尚・橋本替幸・船津和守
Kajiwara, Toshihisa / Hashimoto, Tomoyuki / Funatsu, Kazumori
This paper describes a numerical study of the die swell of viscoelastic fluids in extrusion from annular dies. The Oldroyd-B model was used as the constitutive equation in order to investigate the elastic effects. The shape of the free surface, swelling ratio and the stress and pressure distributions were analyzed by the finite element method. The effects of elasticity of fluid and inner/outer diameter ratio of the annular die on the die swell phenomena were investigated. It was found that the extruded fluid shifts slightly outward after swelling radially outward and inward once. The thickness swelling ratios in the exit flow from the annular dies were found to approach the values in the planar exit flow as the inner/outer diameter ratio approaches unity and those in the capillary exit flow as the diameter ratio approaches zero. From the calculated results of stress and pressure distributions for the Oldroyd-B and the Newtonian fluids, the details of the effects of elasticity on the flow were clarified.
Key words: Die Swell / Annular Die / Oldroyd-B Model / Viscoelastic Flow / Finite Element Method