GB521279A - Improvements in or relating to the manufacture of centrifugal castings - Google Patents

Abstract

521,279. Casting-machines lining moulds. DEUTSCHE EISENWERKE AKT.-GES. Nov. 11, 1938,'No. 32818. Convention date, Nov. 20, 1937. [Class 83 (i)] [Also in Group V] Mould materials; moulds.-In casting, for instance pipes of iron or steel or non-metals in a centrifugal mould lined with granular material, distributed centrifugally, the material is in a loose and preferably dry condition and the speed of rotation is sufficiently, high, during casting, to resist disturbance of said material by the inflowing metal. The speed may be reduced when the metal begins to solidify. The layer is preferably between 1 to 20 mm. thick and is varied as regards grain size, or thickness, or by using materials having different conductivity or density, or by preheating to give the desired rate of cooling and surface formation. The grains are not less than 0.1 mm. though preferably less than 2 mm. in size and are preferably as spherical as possible. Materials adapted to refine the outer zone of the casting, increase its resistance to corrosion, or form thereon an enamel-like coating may be applied to or embedded in the lining. To avoid the lining slipping at projecting parts of the mould, e.g. at the socket end, pins &c. may be arranged there or the loose sand may be replaced at these parts by a sleeve of dried oil-sand or chamotte. Granular sand, coal, slag, metal, or other material is applied by a tilting trough with inserted filling pieces, if necessary, so that the amount supplied at each point axially is such as to produce the same thickness of powder at all parts of the mould. A cast-iron casing, subdivided axially and radially, having a natural or grooved inner face for venting and an inserted ring of metal, chamotte, or dried sand at its upper end, of the same diameter internally as the desired lining, may be slipped over a split tube, containing silver sand, which is tilted while the casing is rotating. The lined casing has its speed increased, and its axis inclined and the metal is poured in, commencing at the upper end. Impurities are discharged from the mould at its lower end.