Abstract
Thanks to the single stage injection blow molding process, specific hollow parts can be produced with standard injection molding machine. A specific mold is designed, enabling the preform injection molding, as well as its blow molding on the same machine. The preform is blow molded right after its injection molding. This particular process does not involve preform storage and reheating before the blow molding stage. This implies that the preform has to remain sufficiently malleable to be blown while being viscous enough to avoid being pierced during the blow molding stage. The polymer used is a polypropylene random copolymer. Therefore the process takes place between the melting temperature and the crystallization one. As the preform is blow molded right after being injected, this single stage process involves high temperature before the blowing. The polymer rheological behavior is investigated through dynamic rheometry in its molten state at various temperatures. A viscous Cross model is used with the thermal dependence assumed by an Arrhenius law. The process is simulated through a finite element code (Polyflow) in the ANSYS Workbench framework. The geometry allows an axisymmetric approach. The transient simulation is run under anisothermal conditions and viscous heating is taken into account. Two geometries are simulated. First, the flask geometry has been used to show the process efficiency. The yoghurt pot geometry has been designed later for industrial application in a more sophisticated mold than the flask mold. Blow molded parts are analyzed by tomography and the thickness has been measured by the tomography data image analysis. The simulation results are compared to the experimental ones. The simulation fits well with the experimental results concerning both geometries. The simple numerical model proposed proves to be robust enough to predict well the blow molded parts final thickness repartitions provided that the relevant temperature and pressure conditions are well defined.
References
Bellet, M., Monasse, B. and Agassant, J. F., “Simulation Numérique des Procédés de Soufflage”, Techniques de l'Ingénieur (in French), (2002)10.51257/a-v1-am3705Search in Google Scholar
Biglione, J., “Simulation et Optimisation du Procédé d'Injection Soufflage Cycle Chaud”, PhD Thesis (in French), MEGA de Lyon, INSA Lyon, Oyonnax (2015)Search in Google Scholar
BiglioneJ., Béreaux, Y., Charmeau, J. Y., Balcaen, J. and Chhay, S., “Numerical Simulation and Optimization of the Injection Blow Molding of Polypropylene Bottles – A Single Stage Process”, Int. J. Mater. Form., 8, (2015a) 10.1007/s12289-015-1234-ySearch in Google Scholar
Biglione, J., Béreaux, Y, Charmeau, J. Y., Rinaldi, R. G., Balcaen, J. and Chhay, S., “Injection Blow Molding Single Stage Process – Approach of the Material Behaviour in Process Conditions and Numerical Simulation”, Key Eng. Mater., 651–653, 805–811 (2015b)10.4028/www.scientific.net/KEM.651-653.805Search in Google Scholar
Bordival, M., Schmidt, F. M., Maoult, Y.L. and Velay, V., “Optimization of Preform Temperature Distribution for the Stretch-Blow Molding of Pet Bottles: Infrared Heating and Blowing Modeling”, Polym. Eng. Sci., 49, 783–793 (2009)10.1002/pen.21296Search in Google Scholar
Fatt, M. S. H., Ouyang, X., “Three-Dimensional Constitutive Equations for Styrene Butadiene Rubber at High Strain Rates”, Mechanics of Materials, 40, 1–16 (2008)10.1016/j.mechmat.2007.06.002Search in Google Scholar
Gahleitner, M., Jääskeläiner, P., Ratajsko, E., Paulik, C., Reussner, J., Wolfschwenger, J., Neißl, W., “Propylene-Ethylene Random Copolymers: Comonomer Effects on Crystallinity and Application Properties”, J. Appl. Sci., 95, 1073–1081 (2005)10.1002/app.21308Search in Google Scholar
Groot, J. A. W. M., Giannopapa, C. G. and Mattheij, R. M. M., “A Computer Simulation Model for the Stretch Blow Moulding Process of Polymer Containers”, ASME Pressure Vesseuls Piping Division/K-PVP Conference, Bellevue, Washington, USA (2010)10.1115/PVP2010-25710Search in Google Scholar
Pham, X. T., Thibault, F. and Lim, L. T., “Modeling and Simulation of Stretch Blow Molding of Polyethylene Terephthalate”, Polym. Eng. Sci., 44, 1460–1472 (2004)10.1002/pen.20142Search in Google Scholar
Pierre, N., Barré, L., Graebling, D., Charmeau, J. Y. and Béreaux, Y., “Polyamide 6-6 Degradation during Injection Moulding”, Polymer Processing Society 17th Annual Meeting, Montreal, Canada (2001)Search in Google Scholar
Reuge, N., Schmidt, F. M., Maoult, Y. L., Rachik, M. and Abbe, F., “Elastomer Biaxial Characterization Using Bubble Inflation Technique. I: Experimental Investigations”, Polym. Eng. Sci., 41, 522–531 (2001)10.1002/pen.10749Search in Google Scholar
Salomeia, Y., Menary, G. H., Armstrong, C. G., Nixon, J. and Yan, S., “Measuring and Modelling Air Mass Flow Rate in the Injection Stretch Blow Moulding Process”, Int. J. Mater. Form. (2015), ISSN 1960–6214 10.1007/s12289-015-1240-0Search in Google Scholar
Schmidt, F. M., Agassant, J. F. and Bellet, M., “Experimental Study and Numerical Simulation of the Injection Stretch/Blow Molding Process”, Polym. Eng. Sci., 38, 1399–1412 (1998)10.1002/pen.10310Search in Google Scholar
Thevenon, A., Fulchiron, R., “Evolution of Poly(propylene) Morphology in the Rubbery State under Uniaxial Strain”, Macromol. Mater. Eng., 299, 165–177 (2014)10.1002/mame.201300043Search in Google Scholar
Yang, L. M., Shim, V. P. W. and Lim, C. T., “A Visco-Hyperelastic Approach to Modeling the Constitutive Behavior of Rubber”, Int. J. Impact Eng., 24, 545–560 (2000)10.1016/S0734-743X(99)00044-5Search in Google Scholar
© 2016, Carl Hanser Verlag, Munich
