Back to results
US 4,728,258 AGranted
Turbine engine component and method of making the same
AssigneeTRW Inc.
InventorsWilliam S. Blazek, Jerry L. Hasch
Life of this patent
Estimating the term…
Loading patent…
Loading patent…
AssigneeTRW Inc.
InventorsWilliam S. Blazek, Jerry L. Hasch
Estimating the term…
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. The shroud rings may be formed of metal having different compositions and crystallographic structures than the metal of the airfoils.
A method of making a turbine engine component having a plurality of airfoils disposed in an annular array between inner and outer shroud rings, said method comprising the steps of positioning a plurality of airfoils having leading and trailing edge portions extending between inner and outer end portions of the airfoils in an annular array with outer end portions of the airfoils at least partially embedded in an outer shroud ring formed of wax and with inner end portions of the airfoils at least partially embedded in an inner shroud ring formed of wax, covering the airfoils and wax shroud rings with ceramic mold material to form a mold, removing the wax material of the shroud rings from the mold to leave inner and outer shroud ring mold cavities having configurations corresponding to the configurations of the wax shroud rings, the inner and outer end portions of the airfoils being at least partially disposed in the shroud ring mold cavities, filling the inner and outer shroud ring mold cavities with molten metal, said step of filling the inner and outer shroud ring mold cavities with molten metal including the steps of at least partially enclosing the inner end portions of the airfoils with a first annular body of molten metal having a configuration corresponding to the configuration of the inner shroud ring and at least partially enclosing the outer end portions of the airfoils with a second annular body of molten metal having a configuration corresponding to the configuration of the outer shroud ring, holding the airfoils in a predetermined spatial relationship with the inner and outer shroud ring mold cavities during filling of the shroud ring mold cavities with molten metal by engaging the airfoils with the ceramic mold material, and solidifying the molten metal in the inner and outer shroud ring mold cavities to form the inner and outer shroud rings, said step of solidifying the molten metal including solidifying the molten metal in the inner shroud ring mold cavity around the inner end portions of the airfoils and solidifying the molten metal in the outer shroud ring mold cavity around the outer end portions of the airfoils.
A turbine engine component comprising an annular one-piece outer shroud ring, said outer shroud ring having a plurality of openings defined by inwardly tapering surfaces of said outer shroud ring, an annular one-piece inner shroud ring being disposed in a coaxial relationship with the outer shroud ring, a plurality of airfoils having inner end portions connected with said inner shroud ring and outer end portions connected with said outer shroud ring, means for interconnecting said inner end portions of said airfoils and said inner shroud ring to hold the airfoils against movement relative to said inner shroud ring, said outer end portion of said airfoils having side surfaces which taper inwardly and are disposed in abutting engagement with the inwardly tapering inner side surfaces of said outer shroud ring when said airfoils and outer shroud ring are at the same temperature, said airfoils being thermally expandable in outward directions relative to said outer shroud ring to move the tapered side surfaces on the outer end portions of the airfoils out of engagement with the inwardly tapering surfaces of said outer shroud ring upon heating of the aifoils to a temperature above the temperature of the outer shroud ring.
A method comprising the steps of providing a turbine engine component having a plurality of airfoils extending between inner and outer shroud rings, heating the airfoils to a temperature above the temperature of the outer shroud ring, thermally expanding the airfoils in an outer direction relative to the outer shroud ring during performance of said step of heating the airfoils, and moving tapered surfaces on outer end portions of the airfoils out of engagement with tapered surfaces on the outer shroud ring during performance of said step of thermally expanding the airfoils.
A method of making a metal turbine engine component having a plurality of metal airfoils disposed in an annular array between inner and outer shroud rings, said method comprising the steps of positioning a plurality of metal airfoils having leading and trailing edge portions extending between inner and outer end portions of the metal airfoils in an annular array with outer end portions of the metal airfoils at least partially embedded in an outer shroud ring formed of wax and with inner end portions of the metal airfoils at least partially embedded in an inner shroud ring formed of wax, said step of positioning the metal airfoils in an annular array with end portions of the airfoils embedded in wax shroud rings includes molding segments of the wax inner shroud ring around inner end portions of the metal airfoils, molding segments of the wax outer shroud ring around outer end portions of the metal airfoils, placing the wax segments of the inner shroud ring in an annular array, placing the wax segments of the outer shroud ring in an annular array, interconnecting the wax segments of the inner shroud ring, and interconnecting the wax segments of the outer shroud ring, said steps of interconnecting the wax segments of the inner and outer shroud rings being performed with the metal airfoils extending between the wax segments of the inner and outer shroud rings, covering the metal airfoils and wax shroud rings with ceramic mold material to form a mold, removing the wax material of the shroud rings from the mold to leave inner and outer shroud ring mold cavities having configuration corresponding to the configurations of the wax shroud rings, the inner and outer end portions of the metal airfoils being at least partially disposed in the shroud ring mold cavities, filling the inner and outer shroud ring mold cavities with molten metal, said step of filling the inner and outer shroud ring mold cavities with molten metal including the steps of at least partially enclosing the inner end portions of the metal airfoils with a first annular body of molten metal having a configuration corresponding to the configuration of the inner shroud ring and at least partially enclosing the outer end portions of the metal airfoils with a second annular body of molten metal having a configuration corresponding to the configuation of the outer shroud ring, and solidifying the molten metal in the inner and outer shroud ring mold cavities to formm the inner and outer shroud ring, said step of solidifying the molten metal including solidifying the molten metal in the inner shroud ring mold cavity around the inner end portions of the metal airfoils and solidifying the molten metal in the outer shroud ring mold cavity around the outer end portions of the metal airfoils.
A method of making a metal turbine engine component having a plurality of metal airfoils disposed in an annular array between inner and outer shroud rings, said method comprising the steps of positioning a plurality of metal airfoils having leading and trailing edge portions extending between inner and outer end portions of the metal airfoils in an annular array with outer end portions of the metal airfoils at least partially embedded in an annular outer shroud ring formed of wax and with inner end poritons of the metal airfoils at least partially embedded in an annular inner shroud ring formed of wax, covering the metal airfoils and wax shroud rings with ceramic mold material to form a mold, removing the wax material of the shroud rings from the mold to leave coaxial inner and outer shroud ring mold cavities having annular configurations corresponding to the configurations of the wax shroud rings, the inner and outer end portions of the metal airfoils being at least partially disposed in the shroud ring mold cavities, filling the inner and outer shroud ring mold cavities with molten metal while the central axis of the annular shroud ring mold cavities is in an upright orientation, said step of filling the inner and outer shroud ring mold cavities with molten metal including the steps of at least partially enclosing the inner end portions of the metal airfoils with a first annular body of molten metal having a configuration corresponding to the configuration of the inner shroud ring, directing molten metal through openings in an axially lower end portion of the outer shroud ring mold cavity, directing molten metal through openings in an axially upper end portion of the outer shroud ring mold cavity, and at least partially enclosing the outer end portions of the metal airfoils with a second annular body of molten metal having a configuration corresponding to the configuration of the outer shroud ring, and solidifying the molten metal in the inner and outer shroud ring mold cavities to form the inner and outer shroud rings, said step of solidifying the molten metal including solidifying the molten metal in the inner shroud ring mold cavity around the inner end portions of the metal airfoils and solidifying the molten metal in the outer shroud ring mold cavity around the outer end portions of the metal airfoils and then in directions extending upwardly and downwardly from the outer end portions of the metal airfoils toward the openings in the axially upper and lower end portions of the outer shroud ring mold cavity to prevent the formation of defects due to a lack of sufficient molten metal in the axially upper and lower end portions of the outer shroud ring mold cavities during solidification of the molten metal in the outer shroud ring mold cavity.
Dependencies are inferred from the claim text.