Deformation Behaviour and Formability of a Tube in Hydroforming with Radial Crushing

The formability of a tube in hydroforming with radial crushing (THFRC) is reported to be improved more that in the conventional hydroforming, i.e. free hydro-bugling (FHB). A simple and practical experimental device was developed for the FHB and THFRC experiments. The deformation behaviour and the formability of a tube in the THFRC are investigated via the experiments and finite element simulations. Emphasis is put on the friction characteristics, the corner-filling ability, the bugled profile, the wall thickness distribution in cross-section and the potential fracturing location of the bugled workpiece. The results show that better formability could be obtained by THFRC than that by FHB; however, a poor asymmetric bugled profile in cross-section arises inevitably due to the exclusive friction characteristics existing between the tube and the die and can be improved by a reasonable loading path during the THFRC process.