BENDING ANGLE MEASURING DEVICE OF BENDER, MEASURING METHOD, AND BENDING METHOD USING THIS MEASURING DEVICE

PURPOSE: To provide a bending angle measuring device of a bender, the measuring method and the bending method using this measuring device where the device is attached easily and bending can be executed accurately. CONSTITUTION: In a time of bending, the shape of a work W is detected by up and down scanning a bending part of the work W with a camera (sensor) 69 attached on a knock patch 57 of a back gage 45 and measuring the distance to the work W over multi points, the detected shape is approximated linearly in the method of least squares with an arithmetic part 87 of the NC (numerical control) device 17, and the bending angle of the work W is obtained. Further, because the work W is moved with a robot 3 for handling the work W so that the bending part of the work W is positioned within the measuring range of the bending angle measuring device, the bending angle can be obtained surely. The measured bending angle of the work W is compared with the target bending angle, if it is not reached to the target bending angle, the additional bending is executed and the bending with the accurate angle can be executed.