Hier finden Sie wissenschaftliche Publikationen aus den Fraunhofer-Instituten.

Media based press hardening of tubes-opportunities and challenges

: Neugebauer, Reimund; Werner, M.; Paul, A.; Schieck, F.

Manabe, K.-i. ; Japan Society for Technology of Plasticity:
Tube Hydroforming Technology : TUBEHYDRO2011; July, 24-27, 2011, Noboribetsu
Noboribetsu, 2011
ISBN: 978-4-930963-00-0
International Conference on Tube Hydroforming (TUBEHYDRO) <5, 2011, Noboribetsu>
Fraunhofer IWU ()
press hardening; tube; media based forming; gaseous forming media; boron-manganese alloyed steel

The press hardening of blanks made from boron manganese alloyed steel is at the present time state-of-the-art for crash-relevant structural parts in current car bodies. The increasing number of press-hardened structural parts reflects the developing trend of reducing car structural weight to achieve the required savings in fuel consumption. On the other hand, there is concern that factors such as car safety, performance and quality are becoming more and more demanding. In addition to press-hardened components, complex hydro-formed profiles also provide a high level of potential for applications in structural car body elements with high loads. Media-based forming at elevated temperatures provides new capabilities as regards technology combinations. By using nitrogen as forming media, the temperature limits for feasible process windows permit forming temperatures above 900 degrees Centigrade. This temperature level ensures direct integration of the head treatment into the media-based forming process and enables the efficient manufacture of high complexity structural profiles. Initial theoretical feasibility studies and technological tests have proved the practicability of this innovative process combination. During practical studies conducted over the last two years various test parts with strength levels above 1500 MPa were produced. Compared to hydro-formed structural parts in volume production today the strength of the test parts was increased by a factor of three. The transfer of this technological approach to volume production ushers in a complete new level in lightweight design structural parts such as A, B, C - pillars, side members or sub-frame components. By means of process development, it proved possible to identify the limits and possibilities, optimize process parameters as well as develop the required devices. As a general rule an efficient heating technology also formed part of the investigation, such as is provided by induction heating. All experimental investigations were supported by a parallel thermo-mechanical FE simulation of the process with "LS-DYNA®". The following paper gives an overview of process development and optimization activities aimed at qualifying this innovative combination of technologies for volume production.