1,250,049. Angular bending; stretch bending. J. W. DAWSON. 3 Feb., 1969, No. 5726/69. Heading B3E. A method of bending an elongate metal workpiece 10, which may be an I-beam, channel, angle or a tube, comprises placing alongside the workpiece at least one column such that for the same force applied longitudinally to both the workpiece is stressed so as to exceed its elastic limit whilst that of the column is not exceeded and a bending force is then applied to the workpiece to bend it into a desired shape. The force applied may be extensive or compressive. In an apparatus, Fig. 3, a column 11 is secured to a beam 10 by a pulling clamp 18, the other ends of the column and beam are connected to a machine for applying force, the beam being secured to a frame 26 carrying an hydraulic piston-cylinder assembly 23 the piston of which acts via a yoke 29 on the end of column 11. When the force has reached its desired value a pull 19 on the clamp 18 serves to bend the beam 10 into a desired shape as shown by dashed lines. Pins 20 may be used to define the shape and are adjustable in their positions. The columns may be continuous or in articulated sections and lubricant strips may be provided between adjacent column and workpiece surfaces.
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