An Integrated Control System for Sheet Metal Flexible Forming on Multi-Point Die

Multi-point forming (MPF) is a flexible forming method for sheet metal parts. It uses two reconfigurable pin groups which function as the stamping dies to form sheet. The height of each adjacent arranged pin is numerical controlled. The shape contour of the pin group can be changed via computer accordingly. The paper outlines the computer integrated control system for MPF process. It mainly includes MPF CAD/CAM software, tool control subsystem, and a measurement subsystem. The CAD/CAM software is for design of the pin group shapes, shape error compute etc. The tool control subsystem is a computer distributed control system based on industrial field bus. On the control of it, the heights of several hundreds pins are set to the desired height according to the data from host computer. The self developed laser scanning measurement subsystem is to measure the shape of formed part. After the MPF system was built, forming experiments were done. To overcome spring-back during forming, a non-parametric model was obtained by online identification with input and feedback spatial shapes. With that model the shapes of the two pin groups were predicted and used in the next cycle forming. The part shape converged to the designed shape gradually