Patent GB-770085-A (GB)
Title: Improvements in or relating to sheet metal bending machines
IPC: B21D5/04
Filed: 1955-04-18
Abstract: 770,085. Angular bending. USSPURWIES GES., J. April 18, 1955 [April 17, 1954], No. 11044/55. Class 83 (4). A metal sheet-bending machine comprising an upper platen which carries a clamping beam, a lower platen, between which and the clamping beam the sheet is held, and a bending platen which bends the projecting part of the clamped sheet up against the clamping beam, is characterized in that the clamping beam is mounted so as to be capable of rotation at least 180 degrees about a vertical pivot on the upper platen. A metal sheet 47 to be bent into box section is inserted between a clamping former 5 and a lower platen 2 with a portion of the sheet projecting over the edge of the platen 2. A pedal 19, previously held depressed, is then allowed to rise so as to let spring pins 18 move through the platen 2 to enter positioning holes in the clamping former 5. At the same time the release of the pedal 19 allows a series of pairs of pivoted spring-urged positioning tongues 39 to rise in the platen 2. The tongues are of different lengths and the sheet 47 is positioned with its edge against the shortest pair. The sheet 47 is then clamped by lowering, by rods 17, an upper platen 3, carrying, on a vertical pivot 26, a beam 6 which, through struts 7 and a strut 8 having a pivoted link 9 resting on the clamping former 5, urges the former 5 down. The former 5 is cambered on its underface to compensate for tendency to be deflected upwardly under the applied load. The pivot 26, secured to a base 27, Fig. 4, dove-tailed in the upper platen 3, supports a bearing 29 and the beam 6 rests with an annular groove 32 on the lower side of its upper wall 33 loosely fitting on an annular rim 34 on the bearing. A small clearance exists, in the region of the bearing, between the upper wall 33 of the beam 6 and the platen 3 so that pressure is transmitted from the platen 3 to the beam 6 at positions to the side of the bearing. Distance-pieces 24 between the upper and lower platens are provided. A bending member 4 is then swung up to bend up the projecting part of the sheet 47 against the former 5, through an angle of slightly more than 90 degrees. The sheet 47 is then moved until its edge engages another pair of positioning tongues 39 and a second bend is formed by the member 4; similarly for a third bend, Fig. 8. A plate on the upper surface of the former 5 is then raised by rotating a camcarrying rod 14 by a lever 13, to engage and hold the bent sheet 47. The platen 3 is then raised, the former positioning pins 18 lowered, and the former 5 and bent sheet turned 180 degrees about the pivot 26. The sheet 47 is then repositioned on the former and the final bend made by the member 4, Figs. 2, 9, the lever 13 being connected to the member 4 so that the plate on the former 5 is raised and the bent sheet section stretched slightly. The former 5 is then rotated about the pivot 26 and the finishing box section 47 removed. As the bends are of slightly more than 90 degrees the section is completely closed, but spacing strips may be inserted between the abutting edges of the section.