Abstract: A turbine engine component is made by forming a heat resistant layer on each airfoil of a plurality of airfoils. This heat resistant layer has a higher melting temperature than the melting temperature of material forming the airfoil. After heat resistant layers have been formed on the airfoils, a mold is formed around the airfoils. Molten metal is poured into the mold. The molten metal engages the heat resistant layers on the airfoils and solidifies to form a shroud ring. As the molten metal solidifies, slip joints between the solidified metal and end portions of the airfoils are free of bonds. The heat resistant layer is at least partially formed of chromium sesquioxide (Cr.sub.2 O.sub.3). A layer of chromium sesquioxide is formed by heating a nickel-chrome superalloy airfoil. As the airfoil is heated, the layer of metal immediately adjacent to the outer surface of the airfoil is depleted of chromium.

Abstract: A turbine engine component includes an annular array of airfoils which extend between inner and outer shroud rings. In order to accommodate thermal expansion of the airfoils, space is provided in a shroud ring rail. To provide space in the shroud ring rail, core material is positioned at the ends of the airfoils. The core material may be preformed separetely from the airfoils or may be a coating which is applied to end portions of the airfoils. Wax pattern material partially encloses the end portions of the airfoils and core material. The shroud ring pattern and the core material are covered with ceramic mold material to form a mold. The shroud ring pattern is then removed from the mold to leave the core material disposed in the shroud ring mold cavity at the end portions of the airfoils. As the mold is preheated, bonds between the core material and the airfoils are broken and the core material is gripped between end portions of the airfoils and the ceramic mold material.

Abstract: An improved turbine engine component includes an annular array of airfoils which extend between inner and outer shroud rings. In order to accommodate thermal expansion of the airfoils, cavities are provided in one of the shroud rings. The cavities may be formed by moving a shroud ring under the influence of forces applied to the shroud ring by a gating system. The cavities which are formed in the shroud ring to accommodate thermal expansion of the airfoils may be open-ended, completely closed-ended or partially closed-ended. When a turbine engine component having cavities in an inner shroud ring is to be formed, molten metal in an outer shroud ring mold cavity is first solidified to firmly grip outer ends of the airfoils. The molten metal in an inner shroud ring mold cavity is then solidified. As the molten metal in the inner shroud ring mold cavity solidifies, the gating system contracts to pull the metal in the inner shroud ring mold cavity inwardly relative to the airfoils.

Abstract: A turbine engine component includes an annular array of airfoils which extend between inner and outer shroud rings. In order to accommodate thermal expansion of the airfoils, space is provided in a shroud ring rail. To provide space in the shroud ring rail, core material is positioned at the ends of the airfoils. The core material may be preformed separately from the airfoils or may be a coating which is applied to end portions of the airfoils. Wax pattern material partially encloses the end portions of the airfoils and core material. The shroud ring pattern and the core material are covered with ceramic mold material to form a mold. The shroud ring pattern is then removed from the mold to leave the core material disposed in the shroud ring mold cavity at the end portions of the airfoils. As the mold is preheated, bonds between the core material and the airfoils are broken and the core material is gripped between end portions of the airfoils and the ceramic mold material.

Abstract: An improved method is provided to cast a one-piece wheel having a circular hub and a plurality of airfoils. The method includes providing a mold having a circular main section and a plurality of open-ended airfoil forming sections. Each of the airfoil forming sections has a thick leading edge portion and a thin trailing edge portion. During a casting operation, the mold is preheated while it is spaced from a chill. The mold and chill are then moved into abutting engagement with the chill extending across the open outer end portion of the airfoil forming sections. The relatively thick leading edge portions of the airfoil forming sections are disposed adjacent to a portion of the chill. Molten metal is poured into the mold cavity and flows outwardly through the airfoil forming sections into engagement with the chill. This results in solidification of columnar grains of metal in a direction toward the center of the mold cavity.

Abstract: To form a turbine engine component, metal airfoils are positioned in an annular array. Outer end portions of the airfoils are embedded in a wax outer shroud ring pattern and inner end portions of the airfoils are embedded in a wax inner shroud ring pattern. A mold is formed by covering the metal airfoils and the shroud ring patterns with ceramic mold material. The wax of the shroud ring patterns is then removed from the mold to leave inner and outer shroud ring mold ring cavities. The shroud ring mold cavities are filled with molten metal which is solidified to form inner and outer shroud rings interconnecting the airfoils. To accommodate thermal expansion of the airfoils relative to the shroud rings, a slip joint is provided between at least one end portion of each of the airfoils and a shroud ring. To enable the slip joint to be formed, molten metal solidifies in the shroud ring to be formed, molten metal solidifies in the shroud ring cavities free of metallurgical bonds to the airfoils.

Abstract: An improved method of assembling molds enables the size of successive molds to be adjusted to provide cast articles having a desired size. In practicing the method, a first or initial mold is assembled in a fixture. This initial mold is used to form a cast article. The cast article formed in the initial mold is measured to determine the extent to which the dimensions of the article deviate from predetermined design dimensions. The fixture is then adjusted to compensate for the deviations in the dimensions of the cast article from the intended or design dimensions. A second mold is then assembled in the fixture. Since the fixture has been adjusted to compensate for the inaccuracies in the first mold, a product cast with the second mold will have dimensions closer to the desired dimensions.

Abstract: An improved apparatus for assembling molds enables the size of successive molds to be adjusted to provide cast articles having a desired size. In using the apparatus, a first or initial mold is assembled in a fixture. This initial mold is used to form a cast article. The cast article formed in the initial mold is measured to determine the extent to which the dimensions of the article deviate from predetermined design dimensions. The fixture is then adjusted to compensate for the deviations in the dimensions of the cast article from the intended or design dimensions. A second mold is then assembled in the fixture. Since the fixture has been adjusted to compensate for the inaccuracies in the first mold, a product cast with the second mold will have dimensions closer to the desired dimensions.

Abstract: A plurality of mold wall segments are positioned in a circular array in an adjustable fixture to form a mold assembly. The fixture includes a base with a plurality of upstanding pin members. Two of the pin members engage the bottom portion of each mold wall segment. Each pin member is eccentrically mounted on a disc. By rotating the discs relative to their base, the mold wall segments may be moved inward or outward. This movement varies the diameter of the lower portion of the mold assembly. The pin members have threaded end portions which enable the pin members to be moved along their upstanding central axes. This movement varies the height of the lower portion of the mold assembly. In addition, the fixture includes a plurality of radially extending adjusting rods, each rod engages a radially inner side surface of a mold segment.

Abstract: An improved method is utilized to make a mold for a cast product having a plurality of spaced apart surfaces. Although the method could be used for forming molds for different products, the method is advantageously used to form a mold for a cast product having a plurality of airfoils disposed in a circular array. To form the mold, a plurality of airfoil pattern segments are placed in a circular array with surfaces of the segments abutting at joints which are free of material interconnecting the segments. A coating of liquid ceramic mold material is applied over the airfoil pattern segments. Since the joints between the airfoil pattern segments are free of interconnecting material, the liquid ceramic mold material can flow into the joints. After the ceramic mold material has been dried and the airfoil pattern segments disposed of, the ceramic mold material which entered the joints between the airfoil pattern segments forms a plurality of relatively thin projections from the main wall of the mold.

Abstract: An improved method of assembling molds enables the size of successive molds to be adjusted to provide cast articles having a desired size. In practicing the method, a first or initial mold is assembled in a fixture. This initial mold is used to form a cast article. The cast article formed in the initial mold is measured to determine the extent to which the dimensions of the article deviate from predetermined design dimensions. The fixture is then adjusted to compensate for the deviations in the dimensions of the cast article from the intended or design dimensions. A second mold is then assembled in the fixture. Since the fixture has been adjusted to compensate for the inaccuracies in the first mold, a product cast with the second mold will have dimensions closer to the desired dimensions.

Abstract: The present invention provides an improved method of forming a metal article having a plurality of airfoils which extend outwardly from a hub. The metal airfoils are formed separately from the hub. In forming a mold to cast the article, blade portions of the metal airfoils are coated with wax. The metal airfoils are then placed in a circular array and are covered with a coating of liquid ceramic mold material. This wet coating of ceramic mold material is dried to form an annular mold wall section having a plurality of recesses in which the blades of the metal airfoils are disposed. The wax coating over the metal airfoil blades is subsequently removed from the recesses to provide space between the blades and the side walls of the recesses. The annular mold wall section in which the blade containing recesses are formed is then connected with top and bottom mold sections to further define a mold cavity having a configuration corresponding to the hub portion of the article.

Abstract: An improved method of forming inner and outer sections of a shroud with an airfoil extending between them includes forming the airfoil and shrouds in sections. An upper or convex section of an airfoil is formed with a radially inner section of the shroud while a concave or lower section of the airfoil is formed with a radially outer section of the shroud. A free end portion of the convex or upper airfoil section is inserted into an opening formed in the outer shroud section while a free end portion of the concave or lower airfoil section is inserted into an opening formed in the inner shroud section. The free end portions of the airfoil sections are then connected with the shroud sections to form a complete airfoil and a portion of the inner and outer shroud sections.

Abstract: 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.

Abstract: A segmented mold assembly is utilized to cast a turbine engine component having an annular inner wall and an annular outer wall which are interconnected by a plurality of struts or vanes. The mold assembly includes a plurality of sections which are formed of a ceramic mold material and are interconnected at flange joints. A pair of mold sections are advantageously formed simultaneously by repetitively dipping a single pattern in a slurry of liquid ceramic mold material to form a wet coating on the pattern. This wet coating of ceramic mold material is then dried. After a covering of the desired thickness has been built up by repetitively dipping and drying the coatings on the wax pattern, the wax pattern is destroyed. To facilitate separating the mold sections after destroying the wax pattern, at least some of the wet coatings are wiped away in an area between portions of the wet coatings which will eventually form the mold sections.

Abstract: An improved method of making a ceramic mold having a cavity in which a cast product is accurately formed includes reinforcing relatively flexible wax pattern material having a configuration which corresponds to the configuration of the mold cavity. Supporting the flexible pattern material with a relatively rigid reinforcing member prevents the pattern material from deflecting during removal from the injection die, pattern storage, pattern and gating assembly and dipping of the pattern in liquid ceramic mold material. Between dipping steps, portions of a wet ceramic coating are wiped away in areas between portions of the wet coating which will eventually form mold sections. After the ceramic mold material on the pattern has been dried, the pattern material is destroyed by heating or other methods. The resulting mold sections are then separated and the rigid reinforcing member removed from between the mold sections.