GB827262A - Improvements in or relating to the continuous centrifugal casting of metals - Google Patents

Abstract

827,262. Casting-processes. METALLURGIQUE D'ESPERANCE-LONGDOZ S.A: Nov. 8, 1957 [Nov. 9, 1956], No. 34914/57. Class 83 (1). In a method of continuous centrifugalcasting in a mould, or between two concentricmoulds 1, 2, a ring 5 of molten metal heavier than the casting-metal is interposed between the casting and the interior of the external mould 2. The heavy metal, which is particularly lead, silver, bismuth or alloys thereof, should not contaminate the cast-metal, e.g. steel, and must have a melting-point much lower than the cast-metal and a boiling-point, at the pressure created by the centrifuging, at least higher than the temperature existing in the mould at the contact with the solidified wall of the casting. The interior of the external mould may be finned, and in a further modification, Fig. 3, a member 8a reduces the heavy metal-ring to a thin lubricating film over the greater part of its length. The leakage may be collected by a trough, which may be of spiralform and connected to the mould, and returned to the supply. The system is self-regulating, in that a variation of the flow of heavy-metal will cause a variation in pressure in the ring, with consequent variation of casting diameter, which is then balanced by a variation of leakage-flow acting in the opposite direction on the pressure in the heavy-metal ring. The system can be controlled, manually or otherwise, by measuring the strain exerted by the external mould on its bearings and regulating the supply of heavy-metal to maintain this strain at an acceptable value. Specification 817,847 is referred to.