Online compensation of force-induced deformation for high-precision riveting machine based on force–displacement data analysis

Press working causes structural deformation of the machine tool, especially the machine tool with large-span gantry or double columns used for the large-sized workpiece. The structural deformation makes the press tool out of accurate positioning, which leads to dimension deviation of the pressed workpiece. Even more, for thin-walled panel riveting, the structural deformation of the riveting machine will cause local deformations of the panel at rivet joints; this accumulated deformation will make the panel out of tolerance. An online deformation measurement and compensation method is developed for adaptive riveting with high accuracy and efficiency in this paper. During the process of servo driving riveting combined with force measurement, the force–displacement data points can be online obtained, and the recognized feature data points by a robust algorithm can represent the critical points during rivet deformation. Combined with the analytical springback of the rivet joint, the deformation of the machine tool can be accurately solved and compensated to the displacement of press tool for high­precision riveting. Simultaneously, with this innovative measurement method, the online quantity inspection for rivet joints can be realized synchronously. Also, a contrast experiment is conducted to validate the effectiveness of the online adaptive deformation compensation based on force–displacement data analysis. The results demonstrate the feasibility of the proposed method in riveting error compensation and riveting quantity inspection.