PREDICTING DEFECT FORMATION FROM THE ANALYSIS OF SHAPE PARAMETERS

D. Antonelli, P. Chiabert

Politecnico di Torino, Italy

The study aims at the development of a method for the prediction of necking and wrinkling sensitivity just during the designing phase. The only information available from the CAD model, at this stage of project development, consists of the geometrical definition of the part. Neglecting some material and machine effects, it is possible to roughly estimate the probability of defect insurgence, which is of furthermost importance in order to guide the designer among different project alternatives.
The proposed method is based on the analysis of the main geometrical features of the die surface. A set of curves is drawn along the surface. The knowledge of the value assumed by gradients, curvatures and torsion along these curves allows making simplified assumptions on the metal sheet behavior during forming. A weighted combination of these values consents to induce the tendency of the material to exceed its formability limits, following to the insurgence of defects like necking, cracks or wrinkling.

Keywords : Die Design, Differential Geometry, Deep Drawing