Form-fit joining of hybrid busbars using a flexible tool demonstrator

This paper is focused on hybrid busbars made from copper and aluminum strips and presents a flexible tool demonstrator capable of replicating material flow in the lancing, bending and compression stages of a new joining by forming process without auxiliary elements. The flexible tool demonstrator is defined by its modular concept that allows the active tool components to be easily interchanged for testing and exploring different materials and thickness combinations, surface conditions and cross-section areas of the strips under laboratory conditions. Experimental and numerical simulation with a selected hybrid busbar geometry validates the overall concept and fabrication of the demonstrator and shows that the new joining by forming process can produce permanent form-fit joints with smooth upper and lower surfaces containing all the plastically deformed material within the thickness of the two strips. Complete filling of the free volume left in-between the thickness of the two strips allows obtaining an electric resistance lower than that of fastened hybrid busbars.

Assembly of lightweight sandwich panels through joining by forming

This paper is focused on the assembly of lightweight sandwich panels built upon the patented ‘Opencell’ structure concept. The objective is to investigate the possibility of joining the connection members of the core to the adjoining skin sheet by plastic deformation at ambient temperature, instead of welding or adhesive bonding. The methodology draws from earlier developments of the authors in joining by forming using the mortise-and-tenon concept to experimentation and finite element modelling of the assembly process in unit cells that are representative of the sandwich panels. It is shown that replacing welding by joining by forming allows fabricating sandwich panels from sheet materials that are difficult or impossible to weld while preventing thermal cycles that are responsible for causing metallurgical changes, distortions, and residual stresses. Replacing adhesive bonding by joining by forming circumvents the need of surface preparation, time for the adhesive to cure and environmental compliance, among other requirements.

Vernetzte Fertigung/Connected manufacturing - Considering the manufacturing history of sheet metal components when joining by forming

Die Herstellung von Blechbauteilen umfasst mehrere Schneid- und Umformoperationen, welche die resultierenden Bauteileigenschaften beeinflussen. Daher weichen die Eigenschaften vom Ausgangszustand des Halbzeugs ab, was bei der Auslegung von Clinchverbindungen berücksichtigt werden muss. Durch die Vernetzung der Einzelverfahren auf Basis der Prozessdaten werden ein Vorgehen zur Ermittlung der Halbzeugeigenschaften beim Scherschneiden und die Auswirkungen auf die Verbindungsqualität beim Clinchen aufgezeigt.   Sheet metal components are manufactured in various cutting and forming operations influencing the resulting properties of the parts. As these properties differ from the initial state of the semi-finished products, they have to be considered in the design of clinched joints. By connecting individual processes, this paper presents an approach for determining the properties of semi-finished parts in shear-cutting operations as well as their effects on the joint quality in clinching.