BENDING MACHINE

PURPOSE:To perform precise bending by detecting the height space of an upper frame and a lower frame and raising/lowering a lower frame so as to obtain a prescribed height space. CONSTITUTION:A detector 37 for height space is provided in a frame 5 with a part 39 to be detected and with a non-contact sensor 41 for detecting the height space. Then, the height space between the upper frame 5 and the lower frame 7 is measured by the detector 37. The lower frame 7 is moved vertically by a hydraulic cylinder, etc., so that the height space becomes a prescribed value. When the height space becomes the prescribed value, by operating an upper limit valve 35 and stopping the raising operation of the lower frame 7, an upper bending die 11 is made to relatively protrude only for a prescribed quantity against a lower bending die 13. Consequently, by relatively protruding the frames 5, 7 only for the prescribed quantity even where the frames are accompanied by deformation with lapse of time such as thermal deformation, a precise bending is performed for a sheet material.