A Computational Model for the Normal Pressure between the Tube and the Hydroforming Die

The normal pressure between the tube and the die in the guiding zone has a great effect on the friction force. Therefore, it is an important consideration in the design of tube hydroforming process. In the present study, a mathematical model for calculating the normal pressure between the tube and the die in the guiding zone is proposed. It is shown that the normal pressure is determined by the Poisson's ratio of the material, the ratio of the outer diameter to the inner diameter and the internal pressure. Simulations and experiments of free forming are performed. The simulation and experimental results show that the mathematical model proposed is very reliable.