Model-based Heating and Handling Strategy for Pre-Assembled Hybrid Fibre-Reinforced Metal-Thermoplastic Preforms

Abstract

Handling plays a key role in automated processing of continuous fibre-reinforced thermoplastics (organo sheets). Challenges result from the properties and behaviour of the processed semi-finished products in heated state. These include the defined grasping, transport and release of flexible materials, the precise handling of sensitive textiles and the observation of processing temperatures for thin-walled semi-finished products.In the context of multi-material or hybrid lightweight components consisting of organo sheets and metallic parts, the joint consideration of component and process development not only enables cost-efficient lightweight design but also yields potentials regarding the automation-oriented processing of organo sheets. With regard to automated handling, the authors have shown that bringing the different materials together to a hybrid preform before heating leads to advantageous material behaviour. For example, metallic areas of the hybrid composite can serve as rigid support and gripping points which can be grasped by standard grippers.To make use of this approach in the context of thermoforming, an integrated heating and handling strategy is required for automated processing of hybrid preforms with inhomogeneous material thickness and varying material combinations. For this purpose, the preform-related heat transfer behaviour was modelled and empirically validated. Based on the results, it was possible to derive process windows depending on the material combination and layer structure. Finally, these findings were used to design heating and handling strategies for the processing of hybrid preforms.