Abstract | Stretch blow molding is the process of choice for the production of PET containers, for the food and beverage industry as well as the pharmaceutical sector. The stretch blow molding process involves three stages, the reheat stage where previously injection molded preforms are heated to desired forming temperature distribution, followed by the forming and the solidifcation stages. The process is a high volume process with costly tooling for both the preform and the container. The design of the tooling, via virtual technologies is preferable so as to minimize costly tooling reworks. Industry has readily accepted the use of finite element technologies in the prediction of the stretch blow molding process. This acceptabce is now generating large amounts of information that are invaluable for future designs. The challenge is now to structure and make use of this information in an efficient way as possible. A design database structure has been set up for information representation from past designs, including a design, preform and bottle databases. Mathematical methodology has been established to represent preform design. The design database and a series of user-defined heuristic design rules for stretch blow molded containers are used to extract unknown input needed in the design methodology. The heuristic knowledge represents the different product characteristics based on mechanical requirements. Those rules and the data extraction will evolve and adapt themselves taking into account new design database, new rules and modified rules. The model inputs are the bottle fill level capacity, bottle diameter, bottle length and bottle transition length, whereas the outputs of the model are the preform shape and weight. |
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