The incremental forming is an innovative process which consists in forming a sheet by the progressive movements of a punch. A solution to improve the productivity of the process and the complexity of the parts shapes is to use robots (serial or parallel). The scientific aim of this work is to define a global approach of the problem by studying the mesoscopic scale of the process and the macroscopic scale of the machine. In this context, a process/machine coupling approach which combines a Finite Element Analysis (FEA) of the process and an elastic modeling of the robot structure is presented.First, the punch forces necessary to form the part are computed assuming a machine structure perfectly stiff. To minimize the error between the predicted forming forces and the measured ones, the weight of three numerical and material parameters of the FEA is investigated. This study shows that an appropriate choice of parameters avoids the force measurement step, unlike the available approaches in the literature.Then, the predicted forces are defined as input data of the elastic model of the robot structure to compute the Tool Center Point (TCP) pose errors. To consider the behavior of the elastic structure, the modeling of robotized structures by beam elements is chosen and applied to an industrial robot Fanuc S420if. The identified elastic model permits to predict the TCP displacements induced by the elastic behavior of the robot structure over the workspace whatever the load applied on the tool. The prediction maximum error of ±0.35 mm remains compatible with the process requirements.To validate the approach, two parts are formed by the robot: a truncated cone and a twisted pyramid. The geometry of these two parts confirms the hypothesis of the simulation and the global approach. These two tests give very interesting results since an improvement of 80 % of the TCP poseaccuracy is identified.Finally, an optimization loop based on a parametric trajectory and on a FEA anticipates the springback effects before the unclamping of the sheet, and then minimizes the error between the nominal shape and the formed one. The application of the process/machine coupling approach for this trajectory leads to a geometric accuracy of the part before unclamping of ± 0.15 mm. These results open interesting perspectives for the methodology application.
