Hybridfügen durch Fließlochformen

Abstract

Various processes with and without additional fasteners are currently used for the production of hy-brid material connections. This leads to different requirements and problems when joining. A cohesive hybrid composite joint of fiber reinforced plastics (FRP) and metal by gluing requires, for example, complex pretreatment of the joining partners. With mechanical joining concepts, the joining elements usually destroy the load-bearing fibers locally and require access to the metal and FKV semi-finished products from both sides. In addition, there is a lot of effort in positioning accuracy. The new process principle, which was developed jointly by the Fraunhofer Institute for Machine Tools and Forming Technology (IWU) and the Technical University of Braunschweig, represents an additional joining pro-cess for joining metal sheets with FRP, wood and plastic semi-finished products. The semi-finished products described are positioned in between at least two metal sheets. The metallic semi-finished products and the (fiber reinforced) plastic and wood semi-finished products can have the same or different dimensions. One of the metallic sheets or both metallic sheets can also be part of a sand-wich structure. Then the defined penetration of all semi-finished products takes place with a flow punch former. The metals are heated and deformed. This happens without material removal. The matrix of the FRP semi-finished product is melted and the reinforcing fibers are, if applicable, dis-placed by the flow punch former and not destroyed, so that a continuous fiber load path is guaran-teed. The deformed metal forms a kind of sleeve, which in turn can be used for shaping or for cutting or forming a thread. With a targeted choice of process parameters and material combination, a form closure and adhesive bond can be produced. The principle of the procedure for joining a metallic sheet with an FRP sheet and a metallic top layer of a metal foam sandwich has already been experi-mentally tested. The result is shown in Figure 1