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Combination of hydroforming and joining

Verfahrenskombination von Hydroumformung und Fügen
: Mauermann, R.; Grützner, R.; Neugebauer, Reimund

Steel research international 76 (2005), No.12, pp.939-944
ISSN: 1611-3683
ISSN: 0177-4832
Journal Article
Fraunhofer IWU ()
joining by forming; hydroforming; spot joining; clinching; selfpierce-riveting; process integration; Umformfügen; Hydroumfomung; Punktfügen; Clinchen; Stanznieten

Manufacturing of complex tube-workpieces often requires medium-based forming processes. Because of the inaccessibility to the inside of the parts, joining of attached parts is difficult. Part handling and a loss of accuracy during thermal joining are disadvantages. A new method of spot-joining by forming is a combination of hydroforming and clinching or hydroforming and self-pierce riveting. In contrast to the standard method the clinching or self-pierce riveting is done without die. A high pressure fluid takes over the task of the die during joining. This die-less procedure also increases the range of possibilities which are not available with standard techniques. By integrating joining into the hydroforming process an additional step in assembly is avoidable. In order to use additional velocity dependent effects of the material, for example the increase of the formability and the decrease of spring back, self-pierce riveting during the hydroforming process by means of impulse load has also been researched among other conventional quasi-static force transmissions. Numeric simulations were used for the theoretical description of the procedure. One goal of simulation is the characterisation of the most influential parameters on the process as a function of the material properties, tool kinematics/-geometry and of the friction conditions. 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.