GB411283A - A process and device for the production of concrete and the like pipes - Google Patents

Abstract

411,283. Moulding pipes in centrifugal machines. NIGG, H., Hergiswil, near Lucerne, Switzerland. May 18, 1933, No. 14372. Convention date, May 20, 1932. [Class 87 (ii).] In a process of moulding or lining pipes, the concrete or like material is introduced between two concentric rotating cylinders and is packed initially by the rotation, and then thrown outwards by centrifugal action against the outer cylinder and at the same time compressed from within by the expansion of the inner cylinder. In the illustrated form the pipe material is charged into the annular space between a cylinder 13 and an expansible core while the apparatus is rotating slowly. The cylinder is clamped between a fixed headstock 29 and a removable headstock 16 which is fixed in position by the pin 81. The core comprises overlapping segmental plates slidably mounted on the radial arms 10 and having weights 11 attached to them so that the core as a whole expands under centrifugal force when the apparatus is rotated rapidly. After completion of the charging and initial packing, the rotation is speeded up whereby the concrete is forced outwards centrifugally by the rotation and in addition is compressed by the expanding core. Spring latches 25, Fig. 5, may be used to maintain the core in its expanded position automatically while the pipe is setting. The outer surface of the core may be coated with a wash of water and cement to produce a smooth interior to the pipe or may be coated with a quick-setting cementitious material such as cement and plaster-of-Paris to facilitate separation of the core from the pipe. In some cases a pro-cast concrete pipe may be used as the outer mould in order to produce multi-layer pipes. Reinforcement can be laid inside the pre-moulded pipe in this case for embedding in the inner layer.