Vented casting molds and process of making the same
First Claim
1. A vented casting mold having a body of hard coherent refractory material containing a cavity for casting a desired shape, and at least one vent passage suitable for venting gas from the interior of a portion of said cavity through the exterior of said mold body, said passage comprising:
- a portion of a predetermined regular shape extending only part way through the cavity wall and defining at one end an inlet portion opening into a portion of said cavity, said inlet portion having one of its transverse cross-section dimensions adjacent said opening sufficiently short that said inlet portion has a substantially greater resistance than said cavity portion to penetration therein of casting material, andan outlet portion formed by an irregular crack in said mold body extending from an inner end exposed to said inlet portion through the outer surface of said mold body, said crack having one of its transverse cross-section dimensions sufficiently short to prevent leakage therethrough of casting material able to penetrate said inlet portion.
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Accused Products
Abstract
The mold body contains a cavity and at least one vent passage for venting gas from the cavity through the body. The vent passage has a portion of predetermined regular shape extending part-way through the cavity wall defining at one end an inlet portion opening into a portion of the cavity with a substantially greater resistance than the cavity to penetration therein of casting material. The vent passage further has an outlet portion formed by an irregular crack in the mold body extending from an inner end exposed to the inlet portion through the mold body, the crack having one of its transverse cross-section dimensions short enough to prevent leakage of casting material therethrough. The mold is made by forming a partially bonded ceramic material containing a casting cavity and incorporating in a wall of the cavity a vent pattern of a shape to mold the portion of predetermined regular shape of the vent passage. The mold is heated to a temperature below the melting point temperature of the pattern for a time sufficient so that heat expansion of the pattern causes the crack part of the vent passage to form. The mold is then heated to higher temperatures to cause the vent pattern to volatilize and escape from the mold body.
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Citations
12 Claims
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1. A vented casting mold having a body of hard coherent refractory material containing a cavity for casting a desired shape, and at least one vent passage suitable for venting gas from the interior of a portion of said cavity through the exterior of said mold body, said passage comprising:
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a portion of a predetermined regular shape extending only part way through the cavity wall and defining at one end an inlet portion opening into a portion of said cavity, said inlet portion having one of its transverse cross-section dimensions adjacent said opening sufficiently short that said inlet portion has a substantially greater resistance than said cavity portion to penetration therein of casting material, and an outlet portion formed by an irregular crack in said mold body extending from an inner end exposed to said inlet portion through the outer surface of said mold body, said crack having one of its transverse cross-section dimensions sufficiently short to prevent leakage therethrough of casting material able to penetrate said inlet portion. - View Dependent Claims (2, 3, 4, 5, 6, 7)
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8. A method of making a vented casting mold from a partially bonded, refractory material which is heat-hardenable to a hard, coherent state, comprising the steps of:
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forming the mold body from said material in said partially bonded state containing a casting cavity and incorporating in a wall of said cavity at least one vent pattern having a shape and located to mold in said body a vent passage portion of predetermined, regular shape extending only part way through said wall and having an inlet end with an opening into said cavity; heating the mold body to a temperature below the melting point temperature of said pattern for a time sufficient so that heat-expansion of said pattern causes the mold body to crack, forming a crack extending from said vent passage portion through the exterior of said mold body to complete said vent passage, and having one of its transverse cross-section dimensions too short to permit leakage of material being cast in said cavity therethrough; and further heating the mold at a sufficiently higher temperature and for a time sufficient to cause said pattern to volatilize and escape from said mold body and to completely harden the mold body. - View Dependent Claims (9, 10, 11, 12)
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Specification