CALCULATION OF SOME PARAMETERS OF POLYHEDRON BULGING PROCESS

Single-curvature polyhedron bulging technology for manufacturing spher ical vessels is to build spherical vessels by assembling and welding s heet blanks of zero-curvature and single-curvature into a polyhedron, then gradually bulging the polyhedron into a spherical vessel. With th e technology, heavy presses and large dies are not needed, so spherica l vessels can be built at low cost. In order to make a polyhedron afte r being bulged satisfy given dimension requirements of the spherical v essel, it is necessary to calculate wall thickness and diameter of the polyhedron under bulging pressure. In this paper, wall thickness decr ement and deflection of a point on a single-curvature polyhedron durin g bulging are measured, it proves that the wall thickness decrement is much smaller than the deflection. Under the assumption that wall thic kness of a polyhedron keeps constant during bulging, the constant-area spheritaxis principle is put forward. With this principle, methods of calculating diameter, wall thickness of a polyhedron and pressure und er which the polyhedron becomes a spherical vessel are got. Besides, o ther applications of the principle are also given.