The integrally hydroforming process of spherical vessels

Abstract Recent developments in the manufacturing technology for spherical vessels involve the use of integral hydrobulge forming. The ‘hastening-sphere’ property and the bending moment effect of the ‘hastening-sphere’ of the polyhedrons are utilized in the hydroforming procedure of spherical vessels: when a polyhedron of a certain structure is freely hydrobulged without dies, a spherical vessel can be obtained. The hydrobulging process of a 32-sided polyhedron is described and analyzed, the stress and strain distribution on the experimental shell are measured and analyzed, and the ‘hastening-sphere’ mechanism is revealed by the experimental results.