Design of an electro-hydraulic CNC press brake

Design principles of computer controlled hydraulic press brake system is presented. A press brake is retrofitted with a pair of electrohydraulic actuators. The electrohydraulic system consists of a variable displacement pump, a pressure accumulator, two servo valves and two asymmetrical piston-cylinder type actuators holding the press ram. Basic modelling and identification of the electrohydraulic drive system dynamics is given for each actuator. The design and implementation of a digital pole placement control algorithm for a CNC system is presented. The position accuracy of the press is maintained within the resolution of the encoder unit. From a series of sheet metal bending rests, the compliances of each actuator and their influence on the bending precision are predicted. Copyright (C) 1996 Elsevier Science Ltd.