Device for use in the manufacture of spigot and socket pipes of concrete having pre-tensioned reinforcements

797,682. Moulding concrete socketed pipes. AKTIEBOLAGET TRYCKRÍR. June 15, 1955, No. 17251/55. Class 87(2). A concrete pipe moulding device in which an expansible sleeve surrounds a rigid core in an expansible outer casing is adapted to mould the internal socket surface of the pipe by a second expansible sleeve of greater diameter and to mould the outer spigot surface by a rigid ring. The core 1 comprises a rubber sleeve 5 on a tube 4 anchored by fitting beadings 7 on the ends of the sleeve into grooves in rings 6 welded to the ends of the pipe. Water under pressure can be forced between the tube 4 and sleeve 5 through pipes 8, 9. An outer casing 2 comprises two (or more) stiffened parts joined by spring-loaded bolts through longitudinal flanges and having top and bottom flanges 13, 12. On the top flange 13 rests a ring 14 of two halves rigidly bolted together, with a gasket between the flange 13 and a flange 14a on the ring 14. To form a pipe socket a collar 17 fits over the ring 6, surrounded by a rubber sleeve 18 anchored by beadings 18a fitting in grooves in the collar 17. A flange 17b on the collar 17 is bevelled at 17c and round it fits a bevelled ring 22 which engages with the semi-circular flanges 12. Water under pressure can be forced between the collar 17 and the sleeve 18. The core 1 is centred by distance pieces 25 between the rings 6 and 23 and is supported from a bed plate 19. The tensioned longitudinal reinforcement rods 24 are anchored at their ends in slots in the rings 22, 23, with circumferential reinforcement 26 wound round them. Then the outer casing with the cage of reinforcement is placed over the core 1 and centred. The mould is filled with concrete, vibrated, and water is supplied under pressure through the pipes 8, 9, 21. The resulting expansion of the rubber sleeve tensions the circumferential reinforcement 26, the outer casing 2 expanding against the pressure of the spring- loaded bolts, the water pressure being maintained while the concrete sets. At its upper end the concrete is pressed against the rigid ring 14 and given a truly circular shape.