| 摘要 |
1,224,454. Angular bending. DOMINION BRIDGE CO. Ltd. 30 April, 1969 [4 March, 1969], No. 21946/69. Heading B3E. A method of forming an elongate trough member from an elongate planar workpiece comprises applying opposing forces to the longitudinal edges of the workpiece in a direction inward of the edges and at right angles to the edges to move the edges towards each other, and constraining the edges to move in a common plane. In one embodiment a workpiece 11, having an initial upward prebend, is inserted between pressure plates 8 and 9 and is bent by moving guides 6 toward pressure plate 8 by means of an hydraulic piston and cylinder assembly 10. An adjustable limit switch 15 is provided to limit the inward movement of the guides 6. In a second embodiment a workpiece 31 is inserted between pressure plates 20 and guides 23 are moved towards each other by means of transverse right- and left-handed screws 24. As the initial compressive force is imparted to the workpiece, jacks 30 engage the central mid-portion of the workpiece causing it to bow upwardly, thus causing jaws 25 to pivot about pins 26. In a third embodiment, a workpiece 56 is placed between pressure plates 49 and 58 in a plane eccentric to the plane of pivot pins 48 and 68 so that upon initial application of a force by means of chains 63 an upward force will be generated so avoiding the use of jacks or an initial prebend. An air hose 65 assists in the initial movement when a heavy load is required to bend the workpiece.
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