GB1013411A - Improvements in or relating to sheet-metal bending machines - Google Patents

Abstract

1,013,411. Curving. G. H. LAGHER. June 16, 1964 [June 17, 1963], No. 24975/64. Heading B3E. A roller type sheet metal bending machine for making, for example, pipes, gutters, comprises a driven feeding roll and a parallel movable roll adjacent thereto, both being of a ferromagnetic material, a third parallel roll, all three rolls engaging the material, and electromagnetic means to produce a magnetic field passing radially through those regions where the driven and movable rolls face one another so that the rolls and the sheet passing therethrough are subjected to the force of attraction. The machine comprises bushings 1a, 1b in which are rotatably driven rolls 2, 3, attached to a support 1 surrounded by an electromagnetic winding 5 of insulated copper or aluminium strips 5a and an adjustable cylindrical shallow steel roll 4 which may be driven from the same source as the rolls 2, 3. The roll 4 which may not be journalled, is freely vertically adjustable and frictionally rotated by contact with the other rolls and a sheet 6 to be bent. The magnetic forces 7 produced by the field of the winding 5 in conjunction with gravitational forces maintain the roll 4 in contact with the sheet. Scrapers and/or bushes may be arranged adjacent the roll gaps to clean the rolls. The bushings may be replaced by one or more magnetically interconnected support rolls equal in length to the rolls 2, 3. A single roll supporting both rolls 2, 3 may be used in conjunction with a stationary electromagnetic winding. The windings should preferably be D.C. fed. Non-uniform magnetic force distribution, to off-set the loading over the length of the rollers, may be obtained by selectively increasing the wall thickness of the roll 4 or bushings 1a 1b The rolls, which may be non-circular, may be bending bars for producing, for example, squaresectioned tubes. The rolls and support may be encased and operated in a vacuum.