Abstract 879,388. Making shell moulds. MELLEN, E. J. May 29, 1959 [June 17, 1958], No. 18433/59. Class 87(2). A refractory mould for casting metal is made by dipping a destructible pattern of e.g. wax, polystyrene or acrylic or methacrylic resins in a slurry, removing the pattern from the slurry and drying it in an air stream which has .a wet bulb temperature of room temperature and a dry bulb temperature not less than 5‹F. above room temperature, and then after drying, repeating the process until several layers have been built up. Successive coats may be dried at increased dry bulb temperatures e.g. 5‹F. per layer. The layers (except the last) may be dusted with refractory particles, e.g. silicon oxide glass. The slurry may be made from quartz, alumina, silicon carbide, graphite, aluminium silicate, flint, zirconium silicate, and silicon oxide glass, with colloidal silica or ethyl silicate as a binder, methyl cellulose as a thickener, and water or alcohol.
THE METHOD OF PREPARING REFRACTORY MOLDS HAVING A WALL THICKNESS OF LESS THAN ONE-HALF INCH FOR CASTING METALS THEREIN COMPRISING THE STEPS OF (1) DIPPING A DESTRUCTIBLE PATTERN IN AN AQUEOUS SLURRY CONTAINING REFRACTORY MATERIALS AND A BINDER THEREFOR TO FORM A FIRST COATING OF REFRACTORY MATERIALS ON SAID PATERN, SAID PATTERN AND SAID SLURRY BEING AT ABOUT ROOM TEMPERATURE, (2) ADIBATICALLY DRYING SAID FIRST COATING SO THAT THE TEMPERATURE OF THE PATTERN REMAINS SUBSTANTIALLY CONSTANT, SAID DRYING BEING ACHIEVED BY THE USE OF A VOLUME OF AIR OF CONTROLLED HUMIDITY THAT IS MOVED RAPIDLY PAST SAID PATTERN WITH SAID FIRST COATING THEREON, SAID AIR CONTAINING SUFFICIENT MOISTURE TO MAINTAIN A SUBSTANTIALLY CONSTANT WET BULB TEMPERATURE WHICH IS SUBSTANTIALLY THE SAME AS THE INITIAL TEMPERATURE OF SAID PATTERN AND HAVING A DRY BULB TEMPERATURE WHICH IS AT LEAST 10*F. HIGHER THAN SAID WET BULB TEMPERATURE, (3) DIPPING SAID PATTERN IN AN AQUEOUS REFRACTORY SLURRY TO FROM ADDITIONAL COATINGS ON SAID PATTERN, AND (4) ADIABATICALLY DRYING EACH SUSSESSIVE COATING IN THE MANNER DESCRIBED FOR SAID FIRST COATING WHILE MAINTAINING THE TEMPERATURE OF SAID PATTERN SUBSTANTIALLY CONSTANT, (5) DESTROYING SAID PATTERN, AND (6) FIRING SAID BUILT-UP COATINGS TO FORM A REFRACTORY MOLD.
Claim 2
Independent Claim
200 words
THE METHOD OF PREPARING REFRACTORY MOLDS HAVING A WALL THICKNESS OF LESS THAN ONE-HALF INCH FOR CASTING METALS THEREIN COMPRISING THE STEPS OF (1) DIPPING A DESTRUCTIBLE PATTERN IN AN AQUEOUS SLURRY CONTAINING REFRACTORY MATERIALS AND A BINDER THEREFOR TO FORM A FIRST COATING OF REFRACTORY MATERIALS ON SAID PATERN, SAID PATTERN AND SAID SLURRY BEING AT ABOUT ROOM TEMPERATURE, (2) ADIBATICALLY DRYING SAID FIRST COATING SO THAT THE TEMPERATURE OF THE PATTERN REMAINS SUBSTANTIALLY CONSTANT, SAID DRYING BEING ACHIEVED BY THE USE OF A VOLUME OF AIR OF CONTROLLED HUMIDITY THAT IS MOVED RAPIDLY PAST SAID PATTERN WITH SAID FIRST COATING THEREON, SAID AIR CONTAINING SUFFICIENT MOISTURE TO MAINTAIN A SUBSTANTIALLY CONSTANT WET BULB TEMPERATURE WHICH IS SUBSTANTIALLY THE SAME AS THE INITIAL TEMPERATURE OF SAID PATTERN AND HAVING A DRY BULB TEMPERATURE WHICH IS AT LEAST 10*F. HIGHER THAN SAID WET BULB TEMPERATURE, (3) DIPPING SAID PATTERN IN AN AQUEOUS REFRACTORY SLURRY TO FROM ADDITIONAL COATINGS ON SAID PATTERN, AND (4) ADIABATICALLY DRYING EACH SUSSESSIVE COATING IN THE MANNER DESCRIBED FOR SAID FIRST COATING WHILE MAINTAINING THE TEMPERATURE OF SAID PATTERN SUBSTANTIALLY CONSTANT, (5) DESTROYING SAID PATTERN, AND (6) FIRING SAID BUILT-UP COATINGS TO FORM A REFRACTORY MOLD.