Abstract

The extrusion blow molding process is the standard manufacturing method for hollow plastic parts such as bottles, cans and large containers. The process consists of two main steps. In a first step a hollow tube which is called parison is extruded. This parison is then in a second step captured by a mold and inflated until it meets the walls of the cooled mold. After a certain cooling time the final part can be demolded. The use of virtual methods not only reduces development costs and time but also the need for prototypes and physical tests. The standard CAE workflow for extrusion blow molded parts involves the process simulation of the parison inflation followed by the simulation of different product tests like drop test, internal pressure test or top-load test. More recent research activities are dealing with the consideration of the process history in the virtual product tests and the prediction of temperature induced shrinkage and warpage. In this work, a comprehensive integrative optimisation workflow for extrusion blow molded components is presented. In contrast to other manufacturing processes, such as injection molding, the mechanical properties of blow molded components are significantly influenced not only by the design of the article, but also by the distribution of wall thicknesses resulting from the manufacturing process. For safety reasons, components are often oversized, i.e. more material is used than necessary. Directly linked to the weight of the article is the cycle time, which significantly determines the energy consumption in production. In order to achieve the desired mechanical properties with the least possible use of material, wall thicknesses and design must therefore be treated simultaneously in an coupled optimization strategy. Because different software tools are used for parison creation, process simulation and structural analysis the transfer of simulation data is not straightforward. Therefore, the vendor-neutral VMAP interface standard which was developed during ITEA3 research project VMAP (A new Interface Standard for Integrated Virtual Material Modelling in Manufacturing Industry) is used for data exchange between the different utilized CAE software tools.