Research on the integral hydrobulge forming technology of spheroidal shells

In the present paper an alternative novel process of manufacturing oblate spheroidal vessels is proposed: the integral hydro-bulge forming (IHBF) technology of oblate spheroidal shells. A few mild steel and stainless steel oblate spheroidal shells for industrial use were manufactured using this new technology with one of the major diameters as high as 3 m. There is a critical value of the ratio between the vertical diameter and the horizontal diameter of the shell before forming, which can determine whether the shell will be wrinkled during hydro-bulging. The processes were analysed afterwards, using the explicit finite element code LS-DYNA3D. The numerical results are discussed and compared with the practical processes. Based on the numerical results a few proposals for the improvement of the IHBF technology of the spheroidal shells are presented.