GB692354A - Improvements in or relating to centrifugally spun concrete products - Google Patents

Abstract

692,354. Reinforced concrete. STANTON IRONWORKS CO., Ltd., CORNELIUS, F. B., WEARMOUTH, J. G., WILLIAMSON, F. L., SUDBURY, W: M., LEE, T. S., and WOODHOUSE, D. P. Jan. 16, 1951 [Jan. 23, 1950], No. 1734/50. Class 20(iv) [Also in Group I] The wire reinforcement embodied in centrifugally spun concrete products such as poles or lighting standards is formed in loops, tension being applied to both legs of the loops which lie parallel to and on opposite sides of the spinning axis in a plane containing the axis. Wire loops 12 are held between spigot end plate and base plate assemblies 5, 7, fixed to opposite ends of mould halves a, a<SP>1</SP>, the wire being looped over rollers 3 on a head 2 having a guide member 4 fitting in plate 5 and adapted to be spaced from the plate by means of threaded studs 6 which pass through apertures in the guide member. In assembly, plate 5 with the wires looped over the rollers is loosely bolted to mould half a<SP>1</SP>, the base plate 7 is fixed to the other end and one end of each wire secured by a wedge c to a block 10 spaced by a compression spring 11 from another block 9 fitting on a screw-threaded boss 8 on plate 7. After mould half a is bolted on, the wires are each tensioned by a hydraulic jack, the loose ends of the wires being secured in jaws d and legs f of the jack positioned round the blocks 9, 10; movement of a piston e draws the jaws from the plate, a wedge is inserted, the piston retracted, the jaws being then released. A final tension is obtained by screwing the spigot end plate away from the mould, the compression of spring 11 at the base plate end being measured by a scale 13. After the mould has been filled and spun and the concrete has set, the wires are cut at the base plate end, the plates removed and the product taken from the mould. Recesses formed by bosses 8 are filled in to protect the wire ends. A modified base plate assembly comprises flanged sleeves incorporating a wedge and surrounded by a ring nut which is screwed therealong against the plate after the sleeve has been pulled out by a jack. In another embodiment the spigot plate is attached to a fixed buttress by an internally threaded flange plate, and .a buttress at the other end carries the jacks and a wire gripping plate beyond the base plate. After the wires have been tensioned and the spigot and base plates bolted to the mould the wires are secured by wedges to the base plate beyond which they are severed, the spigot plate being detached from its buttress and the mould transferred to the spinning machine. A further construction provides a mandrel on which the reinforcement, assembly is mounted; one end of the mandrel abuts the spigot plate and the other engages a rod constituting the ram of a hydraulic jack. After initial tensioning a mould is built up round the assembly the tension transferred to the mould and the mandrelextracted after which a fixed tension is applied by adjustment of nuts on the spigot plate studs, or full tensioning may be obtained in a single operation.