An approximate deformation, analysis and FEM analysis for the incremental bulging of sheet metal using a spherical roller

A flexible and incremental sheet metal bulging machine using a path-control led spherical roller performed a wide range of sheet metal shaping of compl ex shapes, e.g., pyramidal shells, shells of the frustum of a pyramid, shal low pans and embossed panels. The deformation analysis on the incremental f orming of sheet metal becomes a very useful method for the planning of shel l products, the choice of material, the design of the forming process and t he planning of the non-traditional machine tool. In this article, firstly, an approximate deformation analysis for the bulgi ng height, the strain distributions and the forming load of the shell. is p roposed, using a plane-strain deformation model and a forming-limit diagram . Secondly, the FEM based on the shell theory is applied to the calculation of the bulging height, the strain and the stress distributions and to an e xplanation of the plane-strain deformation, which is a unique phenomenon in incremental forming. The predictions by the approximate deformation analysis and the FEM analysi s for the shell of the frustum of a quadrangular pyramid were in reasonably good agreement with experimental values for annealed aluminum sheet. (C) 2 001 Elsevier Science B.V. All rights reserved.