Numerical and experimental investigation on the material flow in an orbital forming process to join functional components from dissimilar materials

Abstract

The manufacturing industry is currently facing major challenges. Environmental protection requirements, component complexity and material costs are continually growing. Lightweight design offers a solution, particularly in hybrid components, reducing weight while maintaining strength. Joining by forming processes based on plastic deformation offer high material efficiency and a reduced number of required parts. However, industrially established processes oppose a lack in flexibility for varying material thickness and strength class. Current research focuses on innovative and versatile mechanical joining processes. In this context, the process of orbital forming was investigated to be used as mechanical joining operation for dissimilar materials. The rotational movement of the tool enables a radial material flow, ensuring permanent form and force closure. To establish a reliable joint, a fundamental understanding of the process in terms of the material behavior is necessary. Therefore, the main focus of this investigation is introducing a novel numerical and experimental approach to identify the material flow during forming. A numerical model is utilized to simulate an orbital forming process and analyze the stress conditions as well as the resulting material flow. The joining partners include the dual-phase steel DP600 and the aluminum alloy EN AW-5754 with a thickness of 3.0 mm. The numerical simulation indicates that with increasing forming force, the material flow increases due to elevated compressive stresses. This assumption is confirmed by experimental investigations using various forces. In addition, the geometrical and mechanical properties of the joint were measured in further investigations, in order to validate the numerical process model.