RESEARCH ON THE INTEGRAL HYDROBULGE FORMING TECHNOLOGY OF SPHEROIDAL SHELLS

In the present paper an alternative novel process of manufacturing obl ate spheroidal vessels is proposed: the integral hydro-bulge forming ( IHBF) technology of oblate spheroidal shells. A few mild steel and sta inless steel oblate spheroidal shells for industrial use were manufact ured 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 d iameter 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 el ement code LS-DYNA3D. The numerical results are discussed and compared with the practical processes. Based on the numerical results a few pr oposals for the improvement of the IHBF technology of the spheroidal s hells are presented.