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US 4,170,256 AGranted
Mold assembly and method of making the same
AssigneeTRW Inc.
InventorsWilliam S. Blazek, Thomas S. Piwonka, James D. Jackson, Philip N. Atanmo
Life of this patent
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AssigneeTRW Inc.
InventorsWilliam S. Blazek, Thomas S. Piwonka, James D. Jackson, Philip N. Atanmo
Estimating the term…
A segmented mold assembly is utilized to cast a turbine engine component having a relatively heavy hub from which relatively light vanes project. The mold assembly includes a plurality of sections which are formed of a ceramic mold material and are interconnected at flange joints. The mold sections are advantageously formed by repetitively dipping patterns in a slurry of liquid ceramic mold material to form wet coatings on the patterns. These wet coatings are dried and separated from the patterns to form the mold sections. The mold sections which are used to cast the vanes retard the removal of heat from the vanes to provide time for the hub to solidify. This can be accomplished by using relatively thick walled mold sections to form the mold cavities in which vanes are cast and relatively thin walled mold sections to form the cavity in which the hub is cast. This could also be accomplished by forming the vane mold section of material having a relatively low rate of heat removal and the hub mold section of a material having a relatively high rate of heat removal.
A method of making a mold assembly having portions of different thicknesses and different heat transfer rates, said method comprising the steps of providing a plurality of separate disposable patterns each of which has a surface area with a configuration similar to a portion of a surface area of a product, at least partially coating each of the disposable patterns with a wet covering of ceramic mold material while maintaining the patterns separate from each other, drying the wet covering on the separate patterns, repeating the coating and drying steps with a first one of the plurality of patterns a first number of times to build up a relatively thick covering of ceramic mold material on the first pattern, repeating the coating and drying steps with a second one of the plurality of patterns a second number of times which is less than the first number of times to build up a relatively thin covering of ceramic mold material which is disposed on the second pattern and is separate from the relatively thick covering on the first pattern, separating the relatively thick covering of ceramic mold material from the first pattern to provide a relatively thick walled mold section having a first heat transfer rate, separating the relatively thin covering of ceramic mold material from the second pattern to provide a relatively thin walled mold section which is separate from the relatively thick walled mold section and has a second heat transfer rate which is greater than the first heat transfer rate, and interconnecting the relatively thick and thin walled mold sections to at least partially form the mold assembly.
A method of forming a mold assembly comprising the steps of providing a plurality of separate disposable patterns each of which has a surface area with a configuration similar to a portion of a surface area of a cast product, at least partially coating each of the disposable patterns with a wet covering ceramic mold material, drying the wet coverings on the patterns, repeating the coating and drying steps until coverings of ceramic mold material of desired thicknesses have built up on the patterns, said step of coating the patterns includes at least partially covering a first pattern with material having a first rate of heat removal, said step of coating the patterns further includes at least partially covering a second pattern with a material having a second rate of heat removal, the second rate of heat removal being greater than the first rate of heat removal, separating the covering from the first pattern to at least partially form a first mold section, separating the covering from the second pattern to at least partially form a second mold section having a rate of heat removal which is greater than the rate of heat removal of the first mold section, and interconnecting the first and second mold sections to at least partially form a mold assembly having portions with different rates of heat removal.
Dependencies are inferred from the claim text.