Novel Robot-Based Process Chain for the Flexible Production of Thermoplastic Components with CFRP Tape Reinforcement Structures

Abstract

A process for flexible preforming of thermoplastic CFRP tapes strips has been implemented at wbk Institute of Production Science. An overview of the preforming process and the approach for the further processing of the preformed strips by additive manufacturing (AM) are presented in this paper. The combination of the novel preforming process and the future AM processing results in a fully flexible process chain for fiber reinforced components. The novel, robot-bending based process is used to manufacture near-net shape preforms for reinforcement structures with a high accuracy. First, possible angles, the bending parameter selection and the obtainable accuracy are described. Afterwards, a toolbox for deriving a process compliant reinforcements shape from the target geometry is presented. Required parameters, such as bending angles, are automatically derived using shape analysis and evolutionary optimization. The second step after preforming the strips is their assembly to a reinforcement structure and subsequently a component. To maintain the flexibility, molding shall be replaced or complemented by AM techniques. In this paper, a projected overall process chain is presented as well as results of the processing of the strips in AM. AM and a local consolidation unit are used to join the strips. The first step of joining consists of aligning the strips to each other and to the components. The AM process is used to apply additional layers and to join structures to the strips and components. For the production of a tough material bond, the printed layers and strips are selectively heated and pressed together with a local consolidation unit. Various strategies and suitable process parameters for joining are experimentally identified. In combination with a second collaborating robot, this opens up new approaches for joining preforms to reinforcement structures and for fiber reinforcement in AM. Furthermore, possible applications of this process are presented.