In the tube hydroforming process, the friction behavior between the tube blank and the die is very complex. As a result, it is very difficult to build a precise friction model in accordance with the actual working conditions by fully taking into account the various factors. In this paper, the friction behaviors between the tube blank and the die in the guided, transition and expansion zones have been studied with the help of numerical simulation and experimental tests. The influences of the different friction conditions in the three zones as well as the uneven friction behavior in the expansion zone on the thickness distribution of tube wall and the characteristics of material flow have been analyzed and experimental tests have been carried out for the verification. The conclusions have provided theoretical references for the process planning, selection of lubrication and tooling design in the actual production process of tube hydroforming.
