FE-simulation and validation of liquid-bi-orientation

An established method to produce thin walled bottles is Stretch Blow Molding (SBM). Polyethylene terephthalate (PET)-preforms are first heated above their glass transition temperature and subsequently transferred into a closed cavity. In a second step the hot preforms are axially elongated by a stretch rod and simultaneously inflated by pressurized air until a contact with the cavity wall is reached (blowing stage). After a cooling phase, the resulting bottle is ejected and further transferred to a filling station, where the desired liquid content is poured in (filling stage). Alternatively to this sequential procedure, a new process combines the blowing and filling phases. This is done by using the desired liquid content as a pressure medium to inflate the hot preforms. Hence, no separated filling station is required. Moreover the filling time is drastically reduced and the cooling is increased through the heat transfer between hot preform and cold liquid. In the following this process is denoted as liquid-bi-orientation (LBO). Despite of its obvious advantages, LBO is not yet used for industrial series production because SBM is well controlled and established. In this paper the LBO process is investigated by experiments and FE-simulations to obtain a deeper insight and to increase process knowledge. The experiments are conducted at a prototype machine. Hereby, a high speed camera in combination with a transparent cavity enables a recording of the preform deformation. Furthermore, FE-simulations with coupled fluid-structure interactions are conducted to predict the process. In comparison to the high speed video the capabilities of the process model are evaluated.