Process development for a new mechanical joining technology of aluminium alloys

Self-pierce riveting with semi-tubular rivet (SPR-ST) or solid rivet (SPR-S) are standard joining techniques for processing 5xxx and 6xxx series aluminium alloys in the automotive industry. When using the conventional variants of these joining technologies for joining brittle die-cast aluminium or 7xxx series aluminium alloys, cracks may form in the components due to the limited ductility of the materials. A new way to join these materials reliably and with high quality is the self-pierce riveting with solid formable rivet (SPR-SF).The developed rivet geometry supports a reliable piercing process as well as the necessary radial spreading in the bottom area of the rivet. The local deformation from the die-side aluminium alloy can be shifted into the rivet element. As a result, the deformation and the damage materials can be minimised. Another significant advantage of this method is the flexibility. The joining direction can be determined both: free from the mechanical properties of the considered materials to be joined and also from the parts thicknesses. This paper shows different problems during the conventional mechanical joining of aluminium alloys (AlSi9Mn, EN AW-7075 T6) by conventional self-pierce riveting with solid rivet and illustrates the numerical as well as the experimental development of the new rivet technology. On the basis of different sensitivity analyses, significant influence parameters and design parameters on the joining process can be determined and are presented in the form of meta models. The first manufactured prototypes then show the potential of this joining technology on real joints for material combinations like EN AW-6016 T4 (t = 2.0mm) into AlSi9Mn (t = 2.0mm) and EN AW-6016 T4 (t = 1.2mm) into EN AW-7075 T6 (t = 2.0mm).