Numerical Investigation of the Effects of Tool Geometry on Multi-Point Forming Process

Abstract

Metal forming is an essential technique for manufacturing of lightweight components that offer enhanced energy efficiency, functionality, and sustainability. This study presents a comprehensive numerical investigation into the influence of forming tool geometry on the quality and performance of the multi-point forming (MPF) process. Finite element simulations were employed to systematically evaluate the effects of geometric tool design variables, namely, tip geometry, shank configuration, and tip structure (solid or hollow) on the predicted forming performance responses, namely, wrinkling behavior, springback displacement, and thickness variation. The numerical results show that the parabolic and elliptical tip geometries prove superior forming performance by effectively suppressing wrinkling and minimizing springback while hemispherical and spherical tips result in increased wrinkling susceptibility and higher residual elastic stresses. Moreover, the inclined shank configuration leads to higher wrinkling and springback compared to other shank configurations. Solid tip structures induce higher wrinkling levels and springback compared to hollow tips. In addition, thickness uniformity is markedly improved when smooth tool profiles such as flat-end, elliptical, and rounded hemispherical geometries are employed. In contrast, the combined use of a hemispherical tip with a square section and an inclined shank results in the most pronounced thickness variation. Furthermore, solid tip designs generally promote a more uniform thickness distribution across the blank, whereas hollow tips exhibit a greater tendency toward localized thinning. Ultimately, the optimal MPF tool configuration consists of a parabolic or elliptical tip geometry combined with a hollow tip and a straight shank configuration, as it presents the best compromise for minimizing wrinkling and springback while maintaining acceptable thickness distribution.