Flexible form-fit joining using incremental sheet metal forming

• Applicant: Dr.-Ing. David Bailly
• Subject Area: Primary Shaping and Reshaping Technology, Additive Manufacturing
• Term: since 2021
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 459861167

The increasing use of multi-material components for lightweight construction poses new challenges for joining processes. The aim of the project is to develop a process that enables the linear joining of sheet-like components made of dissimilar materials, even along curved edges, while maintaining a high degree of flexibility.A frequently used process for linear joining of sheet metal parts, which in principle also allows the joining of dissimilar materials, is hemming. Classic hemming enables high cycle rates, but is only economical for large quantities due to the complex component-specific tools required. Roller hemming, on the other hand, allows a significant reduction in tool dependency and thus high geometric flexibility thanks to coordinate-controlled shaping, usually with industrial robots. Both of the above-mentioned hemming processes show similar process limits with regard to crack formation and geometric defects, such as wrinkles, at the joining edges.A process very similar to roller hemming can be implemented with the help of Incremental Sheet Metal Forming (ISF). This promises a further increase in flexibility as well as an extension of the process limits in terms of formability and geometric defects, due to the even more localized forming. A further advantage is the possibility to integrate the component forming, bending and joining into an ISF-based process chain. In addition, the very flexible process control allows the systematic creation of a remaining flange, which can serve as a joining interface for further components.The general feasibility of form-fit joining by incremental sheet metal forming has already been demonstrated in preliminary investigations. In the proposed project, the process limits of the new approach will be systematically investigated and compared with roller hemming. For this purpose, empirical test studies with both technologies will be carried out on differently complex geometries. Accompanying FE-simulations of both processes will be used to analyze the process limits and differences observed in the experiments with respect to the mechanisms acting in the forming zone. This allows a deeper understanding of the process. Finally, the findings will be transferred to a curved component and the possibility of process integration of component forming, flanging and joining will be exemplarily demonstrated.In the project a comprehensive process knowledge about form-fit joining by means of ISF will be acquired and a quantitative analysis of the process limits compared to roller hemming will be carried out. This allows a substantial evaluation of the potentials of the new technology.

• DFG Programme: Research Grants
• Co-Investigator: Professor Dr.-Ing. Gerhard Hirt