Flexible and incremental bulging of sheet metal using high-speed water jet

A flexible and incremental sheet metal bulging method using a high sped mat er jet has been developed for the small batch manufacture of nonsymmetrical shallow shells, for the erasure of tool marks and for clean forming withou t the need fur lubricating oil. The computer controlled bulging machine sha ped at wide range trf complex shapes of sheet metal, for example, pyramidal shells, shells of pyramid frustums, shallow pans and embossed panels. An a pproximate deformation analysis for the bulging height and the strain distr ibutions of a shell was proposed, using a plane-strain deformation model, t he membrane theory and the momentum theory of hydrodynamics. Predictions fu r the shell of a quadrangular pyramid frustum and the shell of a circular c one frustum were generally in good agreement with experimental values for a n annealed aluminum sheet.