Three-dimensional simulation on multilayer parison shape at pinch-off stage in extrusion blow molding

• Published in: Polymer engineering and science Vol. 50; no. 7; pp. 1476 - 1484
• Main Authors: Fukuzawa, Youhei, Tanoue, Shuichi, Iemoto, Yoshiyuki, Kawachi, Ryuichi, Tomiyama, Hideki
• Format: Journal Article
• Language: English
• Published: Hoboken Wiley Subscription Services, Inc., A Wiley Company 01.07.2010; Wiley; Society of Plastics Engineers, Inc; Blackwell Publishing Ltd
• Subjects: Applied sciences; Blow molding; Blow moulding; Computer simulation; Exact sciences and technology; Extrusion process; Finite element analysis; Finite element method; Flow visualization; Machinery and processing; Mathematical models; Mechanical properties; Melts; Methods; Molding (Chemical technology); Moulding; Multilayers; Parisons; Plastics; Polyethylene; Polyethylenes; Polymer industry, paints, wood; Production processes; Simulation; Technology of polymers; Thickness ratio; Japan; Non Newtonian fluid; Viscosity; Rheological model; High density ethylene polymer; Theoretical study; Multiple layer; Modeling; Finite element method; Three dimensional model; Low density ethylene polymer; Extrusion blown molding; Olefin polymer; Numerical simulation; Parison; Rheological properties
• ISSN: 0032-3888; 1548-2634
• DOI: 10.1002/pen.21672

We tried to predict the multilayer parison shape at pinch‐off stage in extrusion blow molding by nonisothermal and purely viscous non‐Newtonian flow simulation using the finite element method (FEM). We assumed the parison deformation as a flow problem. The Carreau model was used as the constitutive equation and FEM was used for calculation method. Multilayer parison used in this simulation was composed of high‐density polyethylene (HDPE) as inner and outer layers and low‐density polyethylene (LDPE) of which viscosity is five times lower than HDPE as a middle layer. We discussed multilayer parison shape in pinch‐off region. The results obtained are as follows; the parison shape of each layer was clearly visible in the pinch‐off during the mold closing. In addition, the distribution of parison thickness ratios for each layer was located for a large deformation near the pinch‐off region. The melt viscosity for each layer has an influence on the melt flow in the pinch‐off region. In a comparison with an experimental data of parison thickness ratios, the simulation results are larger than the experimental data. These simulation results obtained are in good agreement with the experimental data in consideration of the standard deviations. POLYM. ENG. SCI., 2010. © 2010 Society of Plastics Engineers