Untersuchung der Kombination von Hydroumformung und Fügen von Blechen

Joining procedures called hydro-joining are combinations of hydroforming and clinching or hydroforming and self-pierce riveting. Therefore the on one side of the sheet metal high pressure fluid is used as active component. In the research could be proven that both procedures are applicable for joining homogeneous materials as well as steel-aluminium-mix joinings. The result is a traction and form closure joining. Numeric simulations were used for the theoretical description of the procedure. The geometry of joints and the force and way characteristics determined by experiment and simulation were compared for the verification of the FEM models. The numerical results agree with the experiment after fine calibration of the models. For the material separation with hydro-self-pierce riveting a reliably separation criterion could be defined. Thus a stable computing without user interference could be achieved. The simulation results permit not only the characterisation of the process, but also the theoretical predetermination of optimal joining parameters for different connections with fewer experiments. The internal pressure and the punch kinematics could be identified as essential factors of influence on the process of hydro-self-pierce riveting. The superposition of the axial punch movement with a wobble movement causes the decrease of the necessary joining force and the necessary internal pressure. Further the partial joining by wobble-forming could increase the joining strength. In the investigations the initial geometry modifications could be substituted for a purposeful thermal treatment. The joining quality is regarding to their geometric joining characteristics, the strength and damage behaviour comparable with conventional joinings by self-pierce riveting. By increasing of punch velocity the changed friction conditions of aluminium materials could be used positively for extension of the operation limits