GB552917A - An improved form for arch concrete constructions - Google Patents

Abstract

552,917. Expanding cores. PORTER, W. A. Nov. 4, 1940, No. 16079. Convention date, Aug. 12. [A Specification was laid open to inspection under Sect. 91 of the Acts, May 1, 1941.] [Class 20 (ii)] An expanding core for use in constructing arches, conduits, and the like in situ, comprises a deformable rigid support and a band of flexible material attached at its ends to rollers and adapted to be wrapped around the support and to assume the shape thereof. In one form rods 27 with shaped longitudinally disposed end members 29 are adapted to slide in apertures between guide plates 23, two series of these plates being used spaced apart lengthwise of the core and joined together by the tubes 53. The rods at their inner ends are adapted to abut on the surfaces 33 of sleeves which are connected together by a tube 50, the front sleeve having a screwed aperture to coact with a central screwed shaft 49 supported in end plates 44 which are attached to the guide plates 23 and which with these plates form the framework of the core. Each sleeve 33 is provided with cylindrical portions 34, 35, 36 of different diameters connected together by inclined portions 37, 38 and are provided with inclined slots 40, 41 at their lower portion. The sleeves are prevented from rotation by sector plates 23a attached to the guide plates. A flexible band of rubberized cloth 30 passes from ratchet rollers 31 around the outsides of the members 29, the rollers being disposed in a recess of the supporting frame which also contains adjustable rollers 20 by which the frame is supported during movement from one casting position to another. The action. is as follows:-the core is positioned, the rollers loosened and the flexible band drawn therefrom around the expandible framework and the cores 33 actuated to expand the rods 27 on to the surfaces 35 thereof. The two outer expanding rods pass continuously up the inclined slot 41 so that the lower edges of the flexible cover are positioned on to the insert and raised off the rollers after the rollers have been locked before the other expanding rods are actuated to finish the tightening of the band. Should another diameter be required, the cores are actuated until the surface 36 comes beneath the ends of the expanding rods, or the rods may be replaced by longer or shorter ones. In a modification, the rods are replaced by pistons 61 guided in cylinders 64 attached to longitudinally-spaced spider frames 68 and the sleeves are expanded and contracted by means of connecting rods 73 connected eccentrically to a rotatable disc 75 on a central shaft 60; the pistons carry at their outer ends shaped longitudinal members 71 which in their expanded position form a square with relieved corners and a flexible band 80 stretches over the core and has its ends attached to rollers 81. The lower piston carries a wheel frame on which the core can be supported during the moulding and on which it is moved to different positions.