Flexible and Incremental Sheet Metal Bulging using a Path-Controlled Spherical Roller.

Abstract

A flexible and incremental sheet metal bulging machine using a path-controlled spherical roller has been developed for the small-batch manufacture of nonsymmetrical shallow shells. The computer operations-controlled bulging machine performed a wide range of sheet metal shaping on complex shapes, for example, pyramidal shells, shells of the frustum of a pyramid, shallow pans and embossed panels. In order to predict the forming limit of incremental shaping, a new incremental bulging test by a ball punch was performed on an annealed aluminum sheet, and the experimental results showed that fracture occurred when the thickness strain reached n constant value. An approximate calculation method for the maximum bulging height of the shell was proposed, using this fracture limit and a geometrical deformation model. The predictions for the shell of the frustum of a quadrangular pyramid and the quadrangular pyramidal shell were in reasonably good agreement with experimental values for the annealed aluminum sheet.