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Mechanical joining with self piercing solid-rivets at elevated tool velocities

 
: Neugebauer, Reimund; Jesche, F.; Kraus, C.; Hensel, S.

:
Preprint urn:nbn:de:0011-n-1747601 (577 KByte PDF)
MD5 Fingerprint: 1c1dd1d4e4f82a2a304e40d1f67197e2
Copyright AIP
Created on: 2.8.2011


Menary, G. ; American Institute of Physics -AIP-, New York:
14th International ESAFORM Conference on Material Forming 2011 : 27-29 April 2011, Belfast
New York, N.Y.: AIP Press, 2011 (AIP Conference Proceedings 1353)
ISBN: 978-0-7354-0911-8
ISBN: 0-7354-0911-0
ISSN: 0094-243X
pp.1278-1283
International Conference on Material Forming <14, 2011, Belfast>
English
Conference Paper, Electronic Publication
Fraunhofer IWU ()
self-piercing rivet; high-velocity image; mechanical joining; numerical simulation; damage; strain-rate dependent hardening

Abstract
In the present paper the influence of a higher setting velocity in the joining process of self piercing solid-rivets is shown. In the conventional process tool velocities well below 1 m/s are common. The present research results show the potential of increasing them in the range of about 5 m/s. The results are especially relevant for joining high-strength steels. These steel sheets often cause problems in the process of riveting mixed materials, e. g. aluminium-steel compound. The high strength of the steel sometimes leads to undesirable material flow in the joining process or unwanted burr development. These effects, which are described in detail in the article, can be reduced significantly for the investigated cases by the use of higher tool velocities. Using a high speed camera and a load cell, a test setup based on a drop tower was realized. It was used to time the force signals and the motion profile of the high speed riveting process. The results of the force analysis show an oscillating force progression. Within a numerical research the principal effects influencing the results of the riveting process can be shown. It was found that the pulse-like force transmission between riveting machine and punch, results in various vibrations especially of long and thin tool parts. Hence the rivet penetrates the sheet metal with non-uniform velocities. As a result the early indentation of die into the lower sheet metal at the beginning of the process is reduced, so that the final process step provides a sufficient material flow into the circular rivet groove. A strain-rate dependent process model with elastic tool properties and consideration of inertia effects is presented.

: http://publica.fraunhofer.de/documents/N-174760.html