GB552677A - Improvements in or relating to machines for producing concrete reinforcing members - Google Patents

Abstract

552,677. Twisting rods axially or together. PARFITT, A. W. (Trias, Akt.-Ges.). Oct. 10, 1941, No. 13075, [Classes 83 (iii) and 83 (iv)] Chucks.-In an apparatus for twisting concrete reinforcing rods axially or together by feeding the rod. or rods into one or more hollow chucks provided with movable gripping jaws by which they are gripped and twisted and then removing the rods by feeding them longitudinally through the chucks, the jaws are moved by displacement of tapering members, the ends of which are extended outwardly and slidably attached to an open-ended hollow member mounted for axial displacement in a cylinder. The apparatus is provided at opposite ends with a head containing a rotatable chuck-carrying sleeve 1 and a head having a non- rotating chuck. The sleeve 1 which is rotated by gearing 20 from a motor has a tapered bore with grooves 6 in which are slidably mounted wedge-shaped gripping jaws 3 which have T- shaped ends engaging similar slots in an axially movable bushing 4 slidable in a cylinder 5. The bushing is engaged by a spring 11 the initial tension of which is adjusted by a nut 13 screwing in the cylinder 5. The cylinder is provided with an external screw-thread 14 engaging the threaded interior of a member 15 provided on its outer surface with a pair of racks 16 engaged by pinions 18 rotated by an electric motor. In operation, the cylinder 5 is first rotated by hand until the jaws 3 are advanced under the action of the spring 11 sufficiently to adjust them to the diameter of the rods to be twisted. The traversing motor is then switched on to retract the jaws and then the rods to be twisted are fed through the chucks of the stationary head into the jaws 3 of the rotary head. Feeding is effected by three pairs of motor driven grooved rolls arranged respectively on the outer sides of and between the two heads. The traversing motor is then put in to move the jaws 3 so that they grip the work the motor being automatically cut off through a limit switch. The motor for rotating the head 1 to perform the twisting operation is then put in. This motor is automatically switched off when a predetermined number of twists has been completed. The rod may be placed under a predetermined degree of tension prior to twisting. In another form a number of rods or groups of rods may be twisted simultaneously by providing each headstock with a number of, e.g., three, parallel chucks connected together by bevel gear from a shaft rotated by a belt from a single motor. Specifications 516,165 and 523,089, [both in Group X], are referred to. According to the Provisional Specification, the spring may be replaced by fluid pressure. Further predetermined tension may be applied to the rod before twisting by providing the stationary headstock with separate slidable and fixed chucking elements, the slidable element being operated by toggle lever mechanism operated by a right- and left-handed screw driven through a worm by an electric motor.