Abstract: Incremental sheet metal forming is a class of flexible sheet metal forming methods. In order to reduce the circumferential distortion of parts by incrementally forming with continuous trajectories, an incrementally pressing forming (IPF) process is proposed, in which a part is made by having a small punch with hemispherical tip discretely point-to-point press contours (trajectories) of increasing depth. In IPF processes the vertical displacements of tool, distances of adjacent pressing points and positions of each pressing point are calculated on the geometric data of parts. The smaller circumferential distortion of IPF is due to the less material circumferential flow for the forming tool pressing the sheet axially. The intersections of each deformation zone on pressing point are calculated from forming parameters. And the bigger intersections bring about better surface quality of parts. Comparative analyses on the IPF and the incremental forming with continuous trajectories are performed on experiments and simulation. The experimental and simulation results show that IPF is an effective flexible sheet metal forming method, having smaller circumferential distortion and high forming accuracy of the formed part. And the simulation results match the tests.

Key words: Finite element method, Formability, Incremental forming, Trajectories