Optimization of process parameters and part geometry for high diameter tube hydroforming

The aim of this research is to study the feasibility of vases with tube hydroforming, identifying the limits of this technology. The goal of the simulation study was the identification of the maximum pressure needed to realize vases with big diameter and length. Initially the attention was focused on the realization of a square vase geometry. The initial tubes have a high diameter of 120 mm. Many simulations were conducted to optimize process parameters for this square geometry, namely actuators stroke and water pressure, but it wasn’t possible to completely achieve the die shape at the protrusion edges due to the big diameter expansion and to the rib geometries (thickness, height and fillet radii). Different vase geometries characterized by lower diameter expansion and same dimension of the ribs, were tested. The formability results were improved but there are still problems when the material is filling the ribs (material breakage). In order to realize a safe square part, it was necessary to optimize the rib geometrical dimensions. Other simulations were conducted for a round vase geometry, to check the maximum diameter expansion. Some general design rules were finally summarized.