Numerical simulation and experiments of hydroforming of rectangular-section tubular component

In order to reduce high calibration pressure in the hydroforming of components with too small radii, a method was proposed to manufacture automotive hollow components with rectangular shape by relatively lower pressure. The process is simulated and analyzed. It is thought that the friction force between the die surface and tube is a main reason why high pressure is needed to form small radii. Using the method proposed in this paper, a petal-like section shape is first preformed so that the central zones of the four sides of the preform section do not contact with the die sides, thus the tube metal is easy to flow into the transition radii area in the calibration stage. Moreover, a positive force along the side is produced by the internal pressure, which is beneficial to overcome the friction force and push the material into the radii. Therefore, the pressure for forming the transition radii is greatly reduced and the components with small radii can be formed with relatively lower pressure. For the experimental case conducted in this paper, the forming pressure is reduced by about 28.6% as compared with the estimated forming pressure.