Influence of Process Parameters on the Thickness Distribution of Beverage Bottles in Injection-Stretch-Blow Process

Abstract

PET bottle for beverage is mostly made by the process of injection-stretch-blow. The process parameters influence the thickness distribution obviously. To research the influencing laws of process parameters on thickness distribution, first, we simulate the process of injection-stretch-blow under three different stretching velocities of 0.65, 0.7, and 0.81 m/s, second, we simulate the process under three different delaying times for blowing, such as 0.2, 0.25, 0.3 s. Because the parison needs to be blew when it is stretched in some time of the manufacturing process. Therefore, contact release must be enabled, and which can be enabled only for 3D and shell models. We choose the shell model in the simulation because it has absolutely advantage in calculating speed. The results show that the material of the bottle’s bottom and the thickness on the middle of the bottle increased, and the thickness on the neck of the bottle decrease with the increasing of stretching velocity. And the same thing happened when the delaying time for blowing increase. The increasing of stretching velocity or delaying time is beneficial to the uniformity of bottle’s thickness distribution and helps to improving compressive strength of the bottle. But we must ensure that the parison is not pulled off when the stretching velocity increases, and the impact on the parison’s temperature distribution should be minimized when increasing delaying time. In addition, numerical simulations can provide more help in estimating the thickness distribution of bottle.