GB1228886A - - Google Patents

Abstract

1,228,886. Ejecting concrete pipes from moulds. HUMES Ltd. 13 Sept., 1968, No. 43763/68. Heading B5A. [Also in Divisions B8, C7 and F2] A centrifugally cast reinforced circular section concrete pipe is cast within a slightly tapered steel mould 1, e.g. of # inch less diameter at the top than at the bottom whereafter, with the mould 1 vertically aligned, it is stripped from the pipe by vertically raising the mould whilst simultaneously preventing movement of the pipe by applying a downward force thereto. The reinforcement cage 8, of elliptical configuration, is located within the mould 1 by electrically insulated spacers and is provided with a conducting lead 9 whereby, after casting, an expandable ring is inserted into the mould to support the circular pipe and a direct current is passed through the pipe thereby causing electrolysis of the water in the pipe to produce a hydrogen layer between the pipe and the mould 1 to facilitate subsequent release. The vertical mould is then engaged, at diametrically opposed trunnions 5 thereof, by a pair of "V"- shaped elements 15, carried by a vertically displaceable pair of arms 14 of a fork lift truck 13, a locating pin 16 engaging a boss 6 vertically below a trunnion 5. The mould assembly is conveyed on the truck 13 to an ejection location wherein it is lowered to be supported on the ground upon legs 11 attached to a pipe support ring 3. Clamps 10 and 12 are then released to release the bottom pipe support ring 3 and an upper ring 4 to the latter whereof a downward force is applied by a hold-down cross 21 on the truck 13, until the initial release of the pipe has been effected by simultaneously raising the mould 1 by the truck arms 14. The hold-down cross 21 is vertically displaced by an hydraulic cylinder 22 and is pivotable into position above the mould 1 by a further hydraulic cylinder 20.