Optimised tool-path design to reduce thinning in ISF process

Abstract

Although the competitiveness of the Incremental Sheet Forming process is deeply assessed, some specific aspects penalise its industrial application. In particular, the idea to take advantage of the bigger formability appears of a great interest but the non homogeneous thickness distribution reduces the industrial applicability. It is well known that the process allows to work in the critical “necking-to-tearing” space which results in a strong thinning before failure. However, a significant improvement in the thickness distribution can be obtained by using a modified tool trajectory. In fact, previous experimental investigations carried out by the authors showed that it is possible to influence the thinning phenomenon by applying a proper tool trajectory. Rather than the conventional tool path, which describes the tangent profile to the desired shape, the imposed wall angle can be modified in order to compensate the localised thinning. Unfortunately, this approach increases the process design complexity and suggests to consider the tool trajectory as a decision variable to be optimised in the process design. For this reason, an optimisation model is required in order to simplify the choice among all the possible alternatives. In this paper, a promising analytical model is highlighted and a user friendly procedure is set up to simplify the approach. Satisfactory experimental results which validate the proposed technique are also presented.