A study of forming pressure in the tube-hydroforming process

The forming pressure required to produce a desired part using the tube-hydroforming process was investigated in the present study. The relationship between hydraulic pressure, outer corner radius of the deformed tube, tube thickness and tube yield stress was established based on a proposed theoretical model. In the theoretical model, the material hardening property was taken into consideration. Since the friction in the tube-hydroforming is smaller than that in the conventional stamping process, the die-closing force was also calculated according to the forming pressure predicted by the proposed theoretical model under frictionless condition. The finite element analysis was performed to validate the proposed theoretical model. In order to confirm the accuracy of the finite element simulations, two different finite element codes were employed to conduct the analysis and the simulation results were compared. The predicted values calculated by the proposed theoretical model were found to agree well with those obtained from the finite element simulation results.