Sand mold member and method
AssigneeGeneral Motors Corporation
InventorsJune-Sang Siak, William T. Whited, Mark A. Datte, Richard M. Schreck
Life of this patent
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Abstract
A foundry mold member made from a plurality of sand particles bound together with a binder which is concentrated at the contact points between contiguous sand particles and consists essentially of gelatins having a Bloom rating less than about 175 Bloom grams. The sand particles are first coated with a sol of the gelatin, cooled to ambient temperature and conditioned to a prescribed water content necessary to effect migration of the gelatin to the interparticle contact points upon heating of the coated particles in a pattern mold.
Claims33
A method of making a mold member for shaping molten metal cash thereagainst, comprising the steps of:
- a. preparing a batch of coated sand particles coated with an aqueous sol comprising water and sufficient gelatin to bind said particles together upon drying, said gelatin consisting essentially of gelatins having a Bloom rating less than about 175 grams;
- b. cooling the coated sand particles sufficiently to gelatinize said sol as a coating of gel on said sand particles;
- c. conditioning the coated sand particles to provide conditioned sand particles having a water content in said gel between about 70% to about 85% by volume;
- d. heating the conditioned sand particles in a mold sufficiently to (1) liquefy said gel and cause it to migrate along the surfaces of the sand particles and concentrate at contact points between contiguous said sand particles, and (2) there to coalesce with liquefied gel accumulated at said contact points;
- and
- e. drying the liquefied gel in said mold to crystallize and harden said gel at said contact points sufficiently to form said mold member.
A method of making a mold member comprising the steps of:
- a. coating a plurality of sand particles with an aqueous sol of gelatin at a coating temperature of about 85.degree. C. to about 102.degree. C., said gelatin comprising about 0.5% to about 1.6% by weight of the coated particles and consisting essentially of gelatins having a Bloom rating less than about 175 Bloom grams;
- b. cooling the coated sand particles go about ambient temperature to provide a coating of gel on said particles;
- c. conditioning the coated sand particles to provide conditioned sand particles having a moisture content of between about 70% to about 85% by weight water in the coating thereon;
- d. introducing the conditioned sand particles into a pattern mold at about ambient temperature to shape said particles into the shape of said mold member;
- e. heating the conditioned sand particles in said pattern mold sufficiently to liquefy said coating and cause it to migrate along the surfaces of the sand particles to become concentrated at, and coalesce at, contact points between contiguous said particles;
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- f. drying the sand particles in said pattern mold to crystallize and harden said gel at said contact points.
A foundry mold member comprising a plurality of sand particles each bound to the next by a binder which (1) is concentrated at contact points between contiguous said particles, (2) consists essentially of gelatins having a Bloom rating less than about 175 Bloom grams, and (3) is present in an amount between about 0.5% to about 1.6% by weight of said member.
Dependencies are inferred from the claim text.