In an Internal High Pressure Forming (IHPF) process several forming zones are distinguished based on contact normal stress, sliding velocity, and degree of deformation. The precise design of an IHPF process requires an extensive investigation of the tribological conditions in these different zones. So far laboratory investigation of tribology in IHPF processes has involved pushing a pressurized tube through a tool in order to measure the friction force or determine the friction coefficient. However, such experimental set-ups only represent the guiding zone of IHPF. The prevailing loads require a careful consideration of the individual forming zones. This led to the establishment of further experimental setups for the investigation of transition and expanding zones. These experimental setups, in particular those for the expanding zone, permit a more accurate examination of the friction properties of lubricants. Thus, performance differences that would be indiscernible using the traditional guiding zone test are revealed. Oil and slide lacquer were compared to one another. Differences in friction coefficients in the guiding zone area were not too large and the potential of the slide lacquer was first revealed in experiments in the expanding zone.
During the 8. Hydroforming Forum, February 14.-15., 2002 at Darmstadt - Germany we had the change to visit some companies at their booth. Please enjoy the pictures of the sample parts that we have seen. The following companies showed hydroformed parts. hde Metallwerk GmbH, Gräbener Hydroforming, VAW aluminium AG, Schuler Hydroforming, Fischer stainless tubes.