Plate bending method and bending angle detection device

Abstract

The invention relates a bending angle detection apparatus in which labor required for a work of bending a plate can be reduced. According to the invention, a bending angle detection apparatus ( 50 ) has a sensor ring L ( 64 ), a holder ( 62 ), bearings ( 70 ), the motor body of a servomotor ( 60 ), and a rotation angle sensor ( 102 ). The sensor ring L ( 64 ) produces a signal corresponding to whether the apparatus is contacted with a blade member plate or not. The holder ( 62 ) and the bearings ( 70 ) rotatably connect the sensor ring L ( 64 ) to a bending machine. The motor body of the servomotor ( 60 ) drives the sensor ring L ( 64 ) so that it is rotated. The rotation angle sensor ( 102 ) detects the rotation angle of the sensor ring L ( 64 ). In addition, the holder ( 62 ) and the bearings ( 70 ) connect the sensor ring L ( 64 ) to the bending machine so that the rotation axis of the blade member plate in the case where the bending machine bends the blade member plate coincides with that of the sensor ring L ( 64 ).

1 . A method of bending a plate in which a plate is bent by a bending machine ( 80 ), wherein
 a work of bending the plate is repeated a plurality of times until it is detected that an angle of a bent portion of the plate reaches a predetermined angle, in a state where the plate is attached to said bending machine and springback is completed.   
     
     
         2 . A method of bending a plate according to  claim 1 , wherein the plate is further bent (S 286 ) until it is detected (S 284 ) by a bending angle detection apparatus ( 50 ) connected to said bending machine detects, that the angle of the bent portion of the plate reaches the predetermined angle. 
     
     
         3 . A method of bending a plate according to  claim 2 , wherein said bending angle detection apparatus is contacted with the plate to measure a direction of the plate before said bending machine bends the plate, and a direction of the plate after said bending machine bends the plate. 
     
     
         4 . A bending angle detection apparatus which is a bending angle detection apparatus ( 50 ) for detecting an angle, wherein
 said bending angle detection apparatus is connected to a bending machine ( 80 ),   the angle is an angle of a bent portion of a plate which is bent by said bending machine,   said apparatus comprises:   a signal production device ( 64 ,  66 ) which produces a signal corresponding to whether the apparatus is contacted with the plate or not;   a connecting portion ( 62 ,  70 ) which rotatably connects said signal production device to said bending machine;   a drive device ( 100 ) which drives said signal production device so that said signal production device is rotated; and   a rotation angle detection device ( 102 ) which detects a rotation angle of said signal production device,   said connecting portion has:   a holder ( 62 ) which is fixed to said bending machine; and   bearings ( 70 ) which are connected to said the holder, and   said bearings rotatably position said signal production device so that, when said bending machine bends the plate, a rotation axis of the plate coincides with a rotation axis of said signal production device.