Development of a Digital Metal Forming System

Digital metal forming is being developed to reduce production time and increase product precision in low volume metal forming. This paper discusses the development of a novel digital metal forming system that incrementally works metal parts without specialty dies and tools. An electric ram is utilized to provide the bending force, and the die and workpiece position is controlled by a linear axis. A multi axis force sensor and a machine vision camera are equipped to monitor forces acting on the ram and the part bend angle, respectively, during the process. A C++ program is created to integrate the interpolation, motion control, and force and camera measurement tasks. The function of the system is demonstrated with a sheet metal bending experiment in which an aluminum bar is bent to 30° using an iterative learning controller. An analytical bending model estimating the springback angle after bending is utilized and the controller gain is obtained and adjusted based on the linearized gain of an analytical bending model. The results demonstrate the controller is able to bend the bar to the desired angle in under three iterations in spite of model uncertainties. The designed digital metal forming system is expected to coordinate monitoring system tasks, motion control tasks, and the iterative learning controller to obtain a part with a desired shape in a completely automated process for more types of free forming processes, such as incremental sheet forming.