Spherical and spheroidal steel structure products made by using integral hydro-bulge forming [IHBF] technology. S.H. Zhang et al. J. Construct. Steel Res., April-June 1998, 46(1--3), 338, 339. (Synopsis, see abstract 1848 for full details).
This new technology dispenses with dies and presses when forming the spherical or spheroidal steel parts. Steel plates are first cut into predesigned shapes and the blanks are then fabricated and welded into a closed polyhedral shell according to certain patterns. The shell is filled with fluid media and finally hydraulically bulged into a pre-designed spherical or spheroidal shell. This technology has been proved cost effective.