Patent GB-595836-A (GB)
Title: Metal bending and stretching method and apparatus
IPC: B21D11/02
Filed: 1944-05-16
Abstract: 595,836. Angular bending and stretching. GOODYEAR AIRCRAFT CORPORATION. May 16, 1944, No. 9372. Convention date, Sept. 11, 1943. [Class 83 (iv)] Rolled, extruded or otherwise shaped bars or other metal members are bent round a former while under tension sufficient to stretch them beyond their elastic limit by rotating the former during the stretching and bending operation, the metal being wound round the former from or about one end toward the other. The ends of the work W are secured in clamps 88, 86, respectively mounted on a rotary table 34 carrying a two-part bending former 100, and on a piston rod 74 movable in an hydraulic cylinder 70 vertically adjustable in a support 66 pivotally mounted at 63 on a slide 58, 56, slidable in a slot in the bed 10 and forming an adjustable link of a chain 32. The chain may be driven from the shaft 18 of the turntable which may be driven by a reversible electric motor 38 of the variable multi-speed type through gearing 40. The piston is controlled by fluid from a pump 120 driven by an electric motor to stretch the work during bending by applying a constant or variable tensile force, the pivotal mounting of the cylinder resulting in the stretching force being applied in a direction always tangential to the circumference of the former. The clamping jaws 86 are operated by a piston rod 84 in a pneumatic cylinder 82 carried by a hollow extension 78 of the piston rod 74, and the jaws 86a of the clamp 88 by a pneumatic cylinder 92. The former 100 may be fixed by bolts 106, 108 to a block 110 secured to the turntable, or may be swingable about the bolt 108 by providing an arcuate slot 112 through which the bolt 106 passes so that, particularly when the turntable is rotated through more than a right angle to bend the work to less than a right angle, friction between the work and the former will turn the former in the opposite direction to the turntable so that stretching is applied equally to both ends of the work. The former has a hole 116 which may be aligned with a hole 118 in the block 110 so that the former may be fixed by a locking pin during bending, whereupon the pin is removed and the work given a final stretch by rocking the former about the pivot 108. A turntable and former may also be provided on the shaft 16 to co-operate with an hydraulic cylinder on the other stretch of the chain. In another modification, the rotation of the turntable 34a, Fig. 4, may be effected through the chain by positively moving the cylinder 70a. Rotation of the turntable may be varied by a brake 200 to obtain the desired relation between the bending and the stretching. In a further form in which a positively rotated turntable is used, the chain may be dispensed with and the traversed cylinder replaced by a fixed cylinder force to turn about a vertical pivot. The former, Fig. 6, may consist of a fixed part 216 and a part 218 pivotally mounted on a bolt 220. The former parts which are carried by a block clamped to the turntable 210, when used for bending channel bars, consist of main portions provided on each side with grooved thin plates to receive the side flanges of the channels. Specification 565,582 is referred to.