PROBLEM TO BE SOLVED: To provide a method and an apparatus for accurately bending a metal plate even in the case a bending work for which an angle sensor is unusable is coexisted during the bending of a workpiece while detecting the bending angle of the workpiece by using the angle sensor.;SOLUTION: This method is a bending method using a metal plate bending machine. When the relative stroke position of a punch to a die is calculated by the die information of the punch 3 and the die 5, the material information of a workpiece and the working information for bending the work and the first bending to the workpiece on the basis of the result of arithmetic operation, related data of the stroke position and the bending angle are prepared by detecting the bending angle of the workpiece with the angle sensor 15 and also detecting the relative stroke position of the punch with a stroke position sensor 11. When the bending work of a place for which the angle sensor is unusable is performed, the bending work of the workpiece is performed by determining the difference between the result of the arithmetic operation and the related data, correcting the stroke position of the result of the arithmetic operation on the basis of the difference and controlling the relative stroke position of the punch by the corrected stroke position.;COPYRIGHT: (C)2006,JPO&NCIPI
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