Abstract
A flexible and incremental sheet metal bulging method using a high-speed water jet has been developed for the small-batch manufacture of nonsymmetrical shallow shells, for the erasure of tool marks and for clean forming without the need for lubricating oil. The computer-controlled bulging machine shaped a wide range of complex shapes of sheet metal, for example, pyramidal shells, shells of pyramid frustums, shallow pans and embossed panels. An approximate deformation analysis for the bulging height and the strain distributions of a shell was proposed, using a plane-strain deformation model, the membrane theory and the momentum theory of hydrodynamics. Predictions for the shell of a quadrangular pyramid frustum and the shell of a circular cone frustum were generally in good agreement with experimental values for an annealed aluminum sheet.
