Design of a sensor for on-line measurement of loaded bend angle for pressbrake control

Controlling springback in small radius pressbrake bending operations is mot ivated by the need to produce small lot parts of high quality. A new techni que for springback control has been developed based on a simplified analyti c model of material and tooling geometry variables. This technique requires the on-line measurement of loaded angle with a robust, high resolution opt ical sensor which is insensitive to material surface finish. The design of the sensor minimizes systematic error due to placement on the press bed. Lo aded angle measurement accuracy of less than one are minute is achieved. In combination with a press ram position control scheme, this sensor provides a more accurate bending process necessary for the further development of p recision, small-lot sheet metal assembly manufacture. (C) 2001 Published by Elsevier Science Ltd.