GB1131633A - Improvements in or relating to apparatus for forming hollow cylindrical moulds in mould boxes - Google Patents

Abstract

1,131,633. Moulding-machines; centrifugal-casting machines. A. E. CRAWLEY and A. C. RAY. 11 Feb., 1966 [12 Feb., 1965], No. 6140/65. Heading B3F. A hollow sand mould (M), Fig. 7 (not shown), is formed in a perforated tubular mould-box B held coaxially in an outer casing 12 rotatable by supporting-rollers 5 during the moulding operation and, possibly, during subsequent casting. Sand is fed into the mould-box B, in a manner similar to that described in Specification 969,616, by a screw conveyer S of varying pitch in a casing SC inserted into the box by movement of either the box B or the casing SC. A helical guide vane G is secured by one end to the end of the conveyer casing SC and, because its pitch decreases towards its free end T (initially adjacent an end closure ring ER of the box B), sand forced out of a port E of the casing SC towards the box end is compacted between the end closure ER, the vane end T and a former F mounted for free rotation on a shaft 15 (fixed to an end plate 17 of the casing SC) and extending coaxially through the vane G and end closure ER. The compacted mass of sand forms the mould (M) (with a bore determined by the former F) as an axial movement of the box B and its outer casing 12, relative to the screw conveyer casing SC with its vane and former, causes the mass to be built up along the box. Compressed air is fed to the casing SC and to perforated pipes 72 at the back of the screw, and the screw is faced and edged with rubber, to facilitate sand movement. The tubular mould box B has a longitudinal slit 73, Fig. 6, so that when clamps 75 are released it opens sufficiently to release the mould (M). The bore of the sand mould may be finished by spraying with refractory powder. Centrifugal-casting machines.-When the tubular sand mould (M) is complete, end rings ER of the mould-box B are removed and refractory cores (64, 65), Fig. 7 (not shown) are inserted at both ends of the box and covered by the end rings, for forming flange or socket ends on a cast pipe. After spraying and drying, the outer casing 12 with the contained box B is spun, with molten metal inside, by the supporting rollers 5 of the moulding-machine or by a further spinning machine. The mould and its box B may be extracted from the outer casing 12 before core fitting &c., then spun elsewhere for casting.