An Adaptive Pressbrake Control Using an Elastic-Plastic Material Model

An adaptive controller for a pressbrake has been designed, built, and tested. The controller measures force and displacement during the early part of the bend cycle to estimate workpiece parameters. These parameters are used in an elastic-plastic material model to predict the correct final punch position to yield the desired unloaded angle. A microcomputer is used to control a Cincinnati CB90 hydraulic pressbrake. Data acquisition and computation times are short enough to bend a minimum flank angle of 15 deg using the standard forming rate of 6.7 mm/s (16 in./min) and a 25 mm (1 in.) V-die. Errors in flank angle were less than 1.5 deg in all cases.