Process fusion: tube hydroforming and crushing in a square die

The objectives of this study are to evaluate the quality of the tubes formed by process fusion: hydroforming and crushing. The plastic flow pattern of the tubes during the process fusion in a square cross-sectional die is explored. Finite element simulations using the commercial software DEFORM for the tube expansion test and process fusion of circular tubes formed into a square cross-section have been conducted. The tubes in the process fusion have larger diameter and smaller thickness than the tubes used in the expansion test. The relationship between the forming pressurization and loading pass is discussed. Comparisons of the simulation results such as thickness distribution of the formed product, clamping force and forming pressure for the expansion test and process fusion are made. It is known that the internal pressures and the clamping forces of the die needed in process fusion are much less than those in the expansion test. The thickness distribution obtained by process fusion is much more uniform than that obtained in the expansion test.