Metal sheet bending machine

摘要

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. The bending angle of the metal sheet may be obtained based on the rotating angle of the linear image of projected measuring light formed on the photographed images, or based on an angle formed by the linear image of projected measuring light and a linear image of projected reference light formed by a reference light source for projecting light onto the outer face of the metal sheet while the metal sheet is being bent to the desired angle so as to form the linear image at a desired fixed angle irrespective of the bending angle.