Abstract: An image recognition system using a light-section method which has versality and does not shorten the service life of light projector means. Projection of light from a light source onto a workpiece is continued between the time when a measuring command is issued and the time just after light has been converged by the automatic aperture control mechanism of a television camera. An image processing unit processes an image picked up by the television camera just after the convergence of light by the automatic aperture control mechanism so as to obtain three dimensional configuration data on the workpiece.

Abstract: A major object of the present invention is to compensate for variations in springback angle resulting from variations in material properties from one lot to the next, for the realization of high angle accuracy bending. Based on the difference between a workpiece actual bend angle detected during bending and an estimated bend angle of a workpiece W at an arbitrary penetration point of an upper die 5, a correction value for prestored data relating to a springback behavior under a processing condition is obtained. Based on the correction value, a final penetration point of the upper die 5 is obtained.

Abstract: For the purpose of making it possible to estimate the spring back angle and/or final driving position of the driving die with good accuracy even if there are some variations from lot to lot in the material characteristics values, and thereby achieve bending with extremely high angle accuracy, the actual bending angle is directed at no less than two provisional driving positions of the driving die during the bending of a workpiece. Based on the relationship of the amount of change in the driving amount to the amount of change in the actual bending angle relating to those provisional driving positions, a determination is made of the relationship of the spring back angle to the target bending angle of the workpiece for the respective working conditions of the bending concerned which are stored in advance. From this relationship, a determination is made for the final driving position of the driving die, and the driving die is driven to that determined final driving position.

Abstract: The angle of bend is detected at a plurality of points in a workpiece by angle detecting units during bending of the workpiece. Based on the difference between the bend angle detected at each point and a target bend angle for the workpiece, ball screws are controlled so as to deform a bed for supporting an upper die or lower die, thereby compensating for the boat form of the workpiece.

Abstract: In bending angle detection, a linear projected light image formed on the surface of a workpiece is photographed by a photographing device; the actual inclination angle of a specimen is stored as data in correspondence with the inclination angle and position of the specimen in an image; and the bending angle of the workpiece is obtained by accessing the data, with the inclination angle and position of the linear projected light image in an image produced by photographing. In main straight line extraction, main pixels are obtained from the distribution of the brightness of pixels aligned on specified axes and a main straight line is obtained from a plurality of main pixels. For extracting only a necessary straight line from an image including unnecessary straight lines, the photographing device is so disposed as to photograph a lower bender and a second straight line from the bottom end of the image is extracted.

Abstract: In bending angle detection, a linear projected light image formed on the surface of a workpiece is photographed by a photographing device; the actual inclination angle of a specimen is stored as data in correspondence with the inclination angle and position of the specimen in an image; and the bending angle of the workpiece is obtained by accessing the data, with the inclination angle and position of the linear projected light image in an image produced by photographing. In main straight line extraction, main pixels are obtained from the distribution of the brightness of pixels aligned on specified axes and a main straight line is obtained from a plurality of main pixels. For extracting only a necessary straight line from an image including unnecessary straight lines, the photographing device is so disposed as to photograph a lower bender and a second straight line from the bottom end of the image is extracted.

Abstract: In bending angle detection, a linear projected light image formed on the surface of a workpiece is photographed by a photographing device; the actual inclination angle of a specimen is stored as data in correspondence with the inclination angle and position of the specimen in an image; and the bending angle of the workpiece is obtained by accessing the data, with the inclination angle and position of the linear projected light image in an image produced by photographing. In main straight line extraction, main pixels are obtained from the distribution of the brightness of pixels aligned on specified axes and a main straight line is obtained from a plurality of main pixels. For extracting only a necessary straight line from an image including unnecessary straight lines, the photographing device is so disposed as to photograph a lower bender and a second straight line from the bottom end of the image is extracted.

Abstract: A metal sheet bending machine for bending a metal sheet inserted between an upper bender and lower bender to a desired angle. While the metal sheet is being bent to the desired angle, a linear image of projected measuring light, which rotates with a change in the bending angle of the metal sheet, is formed by a measuring light source on an outer face of the bent metal sheet and sequentially photographed and stored. Based on the stored images, the bending angle of the metal sheet is calculated. Based on the result of the calculation, the positions of tile upper and/or lower benders are controlled whereby the metal sheet can be bent to the desired angle.

Abstract: A bending angle detector for use in a bending machine, capable of detecting a bending angle of a workpiece with high accuracy even if workpieces of different materials are bent by the bending machine.

Abstract: A springback angle measuring instrument for V-bending designed to detect the springback angle of a workpiece in such a way: A bending angle .theta..sub.1 of the workpiece is detected when an upper bender is lowered to an unloading starting position, and the instantaneous position of the upper bender and pressure imposed on the workpiece are detected while the upper bender being lifted at a very slow speed. The increment of the bending force per unit lifting distance of the upper bender is calculated and the bending angle of the workpiece at a point at which the increments of the bending force converge on a certain value is detected. Based on data on the bending angle and bending force obtained after this point, the relationship between the bending angle and the position of the upper bender and the relationship between the bending force and the position of the upper bender are respectively, approximated to a linear expression.