Methods for casting a component having a readily removable casting core

A method is provided for casting a component. Accordingly, a casting core is provided within a cavity of a component mold. The casting core defines an inner component shape and includes a core wall. The core wall defines a core outer surface and a core inner surface disposed opposite the core outer surface. The core inner surface defines a core cavity. The casting core also includes a removal facilitation feature. The component is cast within the cavity of the component mold with the casting core positioned therein. The cast component is removed from the component mold and the casting core is removed from the cast component.

FIELD

The present subject matter relates generally to the production of components for gas turbine engines, and more particularly, to a removable casting core and method of manufacturing.

BACKGROUND

Gas turbine engine components, such as turbine airfoils, are frequently manufactured using an investment casting process in which molten metal alloy is introduced into a mold cavity defined between a shell and a core and allowed to solidify, forming a completed casting. A time-consuming step in the manufacturing process is removal of the core after the casting is complete.

The removal of the core after casting often involves leaching out the core material with a caustic solution (usually aqueous sodium hydroxide or potassium hydroxide for ceramic cores). In the future, this challenge will be magnified as higher temperature, yttrium-containing alloys are used, requiring non-reactive casting core materials such as alumina- and zirconia-based ceramics. These core materials leach much more slowly than silica-based materials currently in use.

Additionally, process improvements in other aspects of the production cycle have highlighted a production bottleneck resulting from current leaching techniques. The requirement to use multiple leaching cycles, often spread over days, slows down and disrupts the consistent part flow through the processing facility. Reducing this disruption will reduce work-in-progress inventories and facilitate faster, more consistent part flow.

Accordingly, there remains a need for a casting core that is readily removable.

BRIEF DESCRIPTION

In one aspect, the present disclosure is directed to a method for casting a component. The method may include providing a casting core within a cavity of a component mold. The cavity of the component mold may define an outer component shape and the casting core may define an inner component shape. The casting core may include a core wall. The core wall may define a core outer surface and a core inner surface disposed opposite the core outer surface. The core inner surface may define a core cavity and the casting core may include a removal facilitation feature. The method may also include casting the component within the cavity of the component mold with the casting core positioned therein. Additionally, the method may include removing the cast component from the component mold, with the casting core positioned internally within the component. The method may further include removing the casting core from the cast component.

DETAILED DESCRIPTION

In general, the present subject matter is directed to a method for forming a cast component. The method may include a number of processes each of which may also be a method. These processes may include the casting of the component and the formation of the casting core to be used in the component casting process. The casting core may be formed by various manufacturing methods including casting and additive manufacturing. The casting core may be formed with removal facilitation features, which enable the casting core to be more easily removed from the cast component. The removal facilitation features may include cavities, support webs, or easily-removable sub-cores. Generally, the removal facilitation features enable a leaching solution to contact a greater surface area of the casting core at one time then would be accessible using known techniques. With a greater surface area of the casting core being affected at once, the casting core may be more quickly removed from the cast component.

Referring now to the drawings,FIG.1illustrates a cross-sectional view of one embodiment of a gas turbine engine100that may be utilized with an aircraft in accordance with aspects of the present subject matter. Various components of the gas turbine engine100may be formed via the methods for casting a component disclosed herein. The engine100is shown having a longitudinal or axial centerline axis112extending therethrough for reference purposes. The engine100will be discussed in detail below. Although shown as a turbofan jet engine, the methods described herein may be used on any turbomachine including, but not limited to, high-bypass turbofan engines, low-bypass turbofan engines, turbojet engines, turboprop engines, turboshaft engines, propfan engines, and so forth. The turbomachine may be configured in any suitable manner, such as for vehicle propulsion or ground-based power production.

FIGS.2A-2Billustrate schematic views of a method200for forming a cast component202. As depicted inFIGS.2A-2B, the method200for forming a cast component202may include a plurality of processes, each of which, may also be a method. For example, the method200may include a core-formation method300or301and a component casting process400. As will be more fully detailed below, the method200may generally include the steps of forming a casting core302via the core-formation method300or301and providing the casting core302within a cavity402of a component mold404. In accordance with the component casting process400, the cast component202may be cast within the cavity402. The casting core302may then be removed from the cast component202. In one embodiment, the cast component202is a turbine engine component of the gas turbine engine100. It should be appreciated that the progression of steps, or processes, in the method200for forming a cast component202is represented inFIG.2Aby arrows A-D and inFIG.2Bby arrows A-C. As shown, the method200may include two distinct molds, the component mold404used in the component casting process400and a core mold304used in method300, and the casting core302produced using the core mold304may be positioned subsequently into the component mold404. In an alternative embodiment, the method200may use only a single mold, the component mold404in the component casting process400, and the casting core302may be provided to the component mold404by simultaneously forming the casting core302and component mold404via an additive manufacturing device303by an additive manufacturing method301inFIG.2B. Additionally, two distinct cores may be used, the casting core302and a sub-core324(FIGS.4A-4B), wherein the sub-core324may be separately formed and positioned in the casting core302or may be simultaneously formed with the casting core302.

As depicted inFIG.2A, the core-formation method300may include the core mold304. The core mold304may be formed with a core mold inner face306, which is the negative of a casting core outer shape308. The casting core302may be a hollow core and may comprise a core wall310defining a core outer surface312and a core inner surface (FIG.3B,314) disposed opposite the core outer surface312. The core inner surface314may define a core cavity (FIG.3B,316). The casting core302may also include a removal facilitation feature (FIG.3B,318), as will be discussed in more detail below. It should be appreciated that the inclusion of the core mold304inFIG.2Ais not intended to limit the core-formation method300to a particular manufacturing method, such as casting. Rather, the casting core302may be formed by any suitable manufacturing method. For example, the casting core302may be an additive manufacturing product, thereby eliminating Step A inFIG.2A. Further, the casting core302may be separately produced by additive manufacturing and positioned into the component mold404as inFIG.2B, or both the casting core302and component mold404may be an additive manufacturing product, produced simultaneously.

The casting core302may be constructed from a refractory material capable of maintaining structural integrity when exposed to molten metal alloys at high temperatures. For example, the core may be formed from a solid ceramic material. Nonlimiting examples of ceramics include those based on silica, alumina, calcium, magnesium, zirconia, and other refractory oxides. Materials such as alumina- and zirconia-based ceramics are considered nonreactive with certain metal alloys. In one embodiment, the casting core302may be constructed of a core material (MC) that may be brittle between 1314° C. and 21° C.

As previously stated, the component casting process400may include a component mold404that may define a cavity402. The cavity402may define an outer component shape204of the cast component202. The casting core302may be provided within the cavity402of the component mold404so that the casting core302defines an inner component shape206. With the casting core302positioned within the component mold404, molten component material (CM) may be introduced into the component mold404to form the cast component202. Once the component material (CM) has cooled and solidified, the cast component202, with the casting core302positioned internally within the cast component202, may be removed from the component mold404. In at least one embodiment, a caustic leaching solution (LS) may be applied to the casting core302to leach the casting core302from within the cast component202. It should be appreciated that in order to remove the casting core302from within the cast component202, the caustic leaching solution (LS) must be brought into contact with the casting core302. As such, the amount of surface area of the casting core302that may be affected by the leaching solution (LS) at any given time may affect the rate at which the leaching process proceeds. Accordingly, in at least one embodiment, the removal facilitation feature318may be a feature of the casting core302that increases the amount of surface area of the casting core302that may be affected by the leaching solution (LS) at any given time.

It should be appreciated that increasing the surface area of the casting core302may increase the effectiveness of other core removal techniques. For example, in at least one embodiment, a water jet may be employed to remove the casting core302from within the cast component202. In such an embodiment, the greater the surface area of the casting core302that may be subjected to the waterjet, the more effective the waterjet may be at removing the casting core302from the cast component202. In another exemplary embodiment, the casting core302may be subjected to a vibration. In such an embodiment, an increase in surface area of the casting core302may permit a greater vibrational movement of the casting core302, which may lead to the fracturing and removal of the casting core302.

FIG.3Aillustrates a schematic cross-sectional view of an embodiment of a method for forming a casting core for use in the exemplary method200. As depicted inFIG.3A, the core-formation method300may include an injection apparatus320. The injection apparatus320may be inserted into the core mold304. With further reference toFIG.3B, in an embodiment, the injection apparatus320may deposit one or more layers322of core material (MC) on the core mold inner face306to form the core wall310. In at least one embodiment, the injection apparatus320may deposit sufficient core material (MC) to establish a core wall thickness (T) of 0.1 mm to 5 mm. The casting core302may have a core wall310comprising a single core layer322having the core wall thickness (T) of 0.1 mm to 5 mm. In an alternative embodiment, as shown inFIG.3B, the core wall310may comprise a plurality of core layers322to establish the core wall thickness (T) of 0.1 mm to 5 mm. By way of further example, the core wall thickness (T) may be 0.1 mm to 4 mm, 0.5 mm to 4 mm, 0.5 mm to 2.5 mm, 0.1 mm to 2.5 mm, 1 mm to 3 mm, or 2 mm to 4 mm. It should be appreciated that, in at least one embodiment, the thickness (T) may be the removal facilitation feature318. As such, the thickness (T) may be selected to ensure the casting core302is of sufficient strength to resist compression as the cast component202is cast, while minimizing the amount of core material (MC) to be removed and maximizing the amount of surface area of the casting core302that may be affected by the leaching solution (LS) at any given time.

With specific reference to the embodiment ofFIG.3B, the core wall310may comprise a plurality of core layers322. The injection apparatus320may deposit successive core layers322until the core wall thickness (T), e.g., 0.1 mm to 5 mm, is achieved. In an exemplary embodiment wherein the injection apparatus320deposits successive core layers322, the injection apparatus320may be inserted into the core mold304and may deposit a core layer322as the injection apparatus320is withdrawn from the core mold304. The injection apparatus320may then be reinserted into the core mold304and may deposit an additional core layer322as the injection apparatus320is again withdrawn from the core mold304. The process of inserting the injection apparatus320and depositing a core layer322may be repeated until the core wall thickness (T), e.g., 0.1 mm to 5 mm, is achieved.

In the various embodiments in accordance with the present disclosure, the removal facilitation feature318may include structures and materials that may serve to make the casting core302more susceptible to known removal processes. For example, the core wall310may have sufficient strength to resist deformation during the component casting process400and, thus, the core cavity316may be formed without the inclusion of any additional support elements. In such an embodiment, the entirety of the surface area of the core inner surface314may be simultaneously exposed to known leaching processes. In additional embodiments, the casting core302may include, within the core cavity316, additional support structures as may be necessary to reduce, or eliminate, deformation of the casting core302during the casting process. In such embodiments, the removal facilitation features318may include filling the core cavity316with a highly-removable sub-core or a support web to provide structural support while maintaining a maximal surface area that may be instantly exposed to a removal process, such as leaching.

FIG.4Aillustrates a schematic cross-sectional view of one embodiment of a method for forming a casting core, which may have a sub-core, for use in the exemplary method200. As depicted inFIG.4A, the core-formation method300may include a sub-core324comprising a sub-core material326. The core mold304may be formed with a core mold inner face306that is the negative of a casting core outer shape308. The sub-core324may be secured within the core mold304and a portion of core material (MC) may be introduced into the core mold304to form the core wall310as a single core layer322. Once the core material (MC) has cooled and solidified, the casting core302may be removed from the core mold304. The sub-core324may be removed from the casting core302to expose the core cavity316.

The sub-core material326, in an alternative embodiment, may comprise an easily removable material yet possess sufficient rigidity to provide structural support to the casting core302. As such, the sub-core324may be easily removable, and may be the removal facilitation feature318within the core cavity316. In such an embodiment, the sub-core324may be maintained in the casting core302until the cast component202is cast. Once the cast component202is cast, the sub-core324may be exposed to rapid leaching and removed from the casting core302. The rapid leaching of the sub-core324may expose a greater surface area of the casting core302to the leaching process.

In another embodiment as depicted inFIG.4A, the casting core302may be formed by any of the methods described herein, wherein the casting core302is formed with the core cavity316. The sub-core324, comprising the sub-core material326, may be formed separately and inserted into the core cavity316. In such an embodiment, the casting core302may have a core wall thickness (T) of 0.1 mm to 5 mm and may be structurally supported by the spanning of the core cavity316by the sub-core324. Because the sub-core material326may be an easily removable material, the sub-core324may be the removal facilitation feature318within the core cavity316.

In yet another embodiment as depicted inFIG.4B, multi-material additive manufacturing may be used to form the casting core302, sub-core324, and component mold404simultaneously. The casting core302with the sub-core324therein may thus be provided to the component mold404simultaneously with formation of the component mold404. The cavity402may include one or more features (not shown) connecting the casting core302to the component mold, which may serve as support structures during casting, and which may leach out to form features, such as holes and passages, in the cast component202. Alternatively, the sub-core324may be formed separately and thereafter inserted into the additively manufactured casting core302and component mold404to provide support during the subsequent component casting process400.

FIGS.5A,5B,5C, and6illustrate schematic top views of embodiments of a method for forming a casting core, which may have a support web, for use in the exemplary method200. As depicted inFIGS.5A-5C, the core formation methods300and301may include a support web328contained within the core cavity316and coupled to the core inner surface314. The support web328may be a removal facilitation feature318within the core cavity316. The support web328may comprise a plurality of pores, cavities, or voids330. The plurality of pores, cavities, or voids330may facilitate penetration of a caustic leaching solution (LS) during core removal. In other words, because the support web328permits the penetration of the caustic leaching solution (LS), maximal surface area of the core inner surface314may be exposed to the leaching process at once. Additionally, the plurality of pores, cavities, or voids330may increase the effectiveness of other core removal methods, such as a water jet or vibration.

In addition to facilitating transportation of the leaching solution (LS) into and out of the core cavity316, the support web328may be configured to provide structural support for the core302. The support web328may ensure mechanical support is provided in areas subject to high stress during the component casting process400. The support web328may also limit or control thermal expansion of the core302during the casting process. The support web328may take any suitable form including a plurality of support members332, a single structural member334, or a foam (FIG.6,336). It should be appreciated that the web328may be formed from the core material (MC), the sub-core material326, or other suitable material.

In an embodiment such as depicted inFIGS.5A and5C, the support web328may comprise a plurality of support members332. The plurality of support members332may span the core cavity316and be coupled to the core inner surface314. At least two support members of the plurality of support members332may meet at an intersection338. In one embodiment, the plurality of support members332may be arranged in a repeating pattern to form a lattice structure having a plurality of intersections338. The plurality of support members332may intersect the core inner surface314at specific locations where a high stress load is computed. For example, the location having a high stress load may be a gradient peak having a stress concentration value which is greater than the stress concentration of at least one adjacent region. In such an embodiment, the arrangement of the plurality of support members332may have no discernible pattern and may not include the intersection338. In one embodiment, the plurality of support members332may comprise a plurality of beams. In another embodiment, the plurality of support members332may comprise a plurality of dividers or walls extending. Each divider or wall may be a unitary structure extending substantially along the core inner surface. For example, in at least one embodiment, each divider wall may have an edge length substantially equal to a depth of the core cavity316. In yet another embodiment, the plurality of support members332may comprise at least one beam and at least one divider or wall, wherein the at least one beam has a maximal length greater than a maximal thickness. It should be appreciated that, in an exemplary embodiment, the plurality of support members332may form a lattice structure, such as a honeycomb, on the core inner surface314. The lattice structure may conform to the shape of the core inner surface314and may not span the core cavity316.

FIG.5Bdepicts an embodiment wherein the support web328may comprise a single structural member334. The single structural member334may have a first support end340coupled to a first inner surface attachment location342and a second support end344coupled to a second inner surface attachment location346. The first inner surface attachment location342and the second inner surface attachment location346may be located along the core inner surface314at locations selected to orient the single structural member334to ensure mechanical support is provided in areas subject to high stress during the component casting process400. It should be appreciated that in one embodiment, the single structural member may be a beam, and in an additional embodiment, the single structural member may be a divider or wall.

In an embodiment in accordance withFIGS.5A and5B, the core formation method300may include forming the casting core302by a casting process. In one embodiment wherein the casting core302is formed by casting, the sub-core324may be formed to integrate the support web328. In such an embodiment, the sub-core324, integrating the support web328, may remain in the casting core302following the removal of the casting core302from the core mold304. The casting core302, containing the integrated support web328, may then be employed in the component casting process400as previously discussed. In an alternative embodiment, the sub-core324may be formed to integrate the support web328into the core inner surface314. Following the casting of the casting core, the sub-core324may be removed from the casting core302leaving the casting core302and the support web328as a unitary structure.

The support web328may, in an exemplary embodiment, be an additive manufacturing product. The sub-core324integrating the support web328may be produced through additive manufacturing processes. The sub-core324may then be employed in the core formation process300to form the casting core302. In an additional embodiment, the support web328may be incorporated into the casting core302as a unitary structure. The casting core302and the integrated support web328may be produced via additive manufacturing processes. As shown inFIG.5C, the component mold404also may be simultaneously formed via the additive manufacturing process, or it may be formed separately and the additively manufactured casting core302with integrated support web328may thereafter be positioned in the cavity402. It should be appreciated that the support web328may, alternatively, be additively manufactured and inserted into the core cavity316of the core302produced by any of the processes discussed above.

FIG.6depicts an embodiment wherein the support web328, and thus the removal facilitation feature318, comprises a foam336. The foam336may be any suitable material. For example, the foam may be a ceramic foam, a metallic foam, or an expanding foam. In one embodiment, the foam336may be the sub-core material326and the foam336may be the sub-core324. The foam336, when employed as the sub-core324, may be used in the core formation process300when casting the casting core302. In an alternative embodiment, the casting core302may be formed with the core cavity316by any of the processes described herein. The foam336may be inserted into the core cavity316to provide structural support to the casting core302while still permitting the leaching solution (LS) to penetrate into the core cavity316during the leaching process. Similarly, in one embodiment, the core cavity316may be formed as discussed above. The foam336may be an expanding foam that may be introduced into the cavity316and permitted to expand and fill the cavity316. The expanding foam may also comprise a material that is highly removable. The expanding foam may be formulated with a ceramic and have a self-skinning feature wherein the foam336may expand to fill the cavity316and form a skin at the surface. The support web328, when comprising the foam336, may be the removal facilitation feature318.

As used herein, the terms “additively manufactured” or “additive manufacturing techniques or processes” refer generally to manufacturing processes wherein successive layers of material(s) are provided on each other to “build-up,” layer-by-layer, a three-dimensional component. The successive layers generally fuse together to form a monolithic component that may have a variety of integral sub-components. Although additive manufacturing technology is described herein for the fabrication of complex objects by building objects point-by-point, layer-by-layer, typically in a vertical direction, other methods of fabrication are possible and within the scope of the present subject matter. For example, although the discussion herein refers to the addition of material to form successive layers, one skilled in the art will appreciate that the methods and structures disclosed herein may be practiced with any additive manufacturing technique or manufacturing technology. For example, embodiments of the present invention may use layer-additive processes, layer-subtractive processes, or hybrid processes.

Suitable additive manufacturing techniques in accordance with the present disclosure include, for example, Fused Deposition Modeling (FDM), Selective Laser Sintering (SLS), 3D printing such as by inkjets, laser jets, and binder jets, Sterolithography (SLA), Direct Selective Laser Sintering (DSLS), Electron Beam Sintering (EBS), Electron Beam Melting (EBM), Laser Engineered Net Shaping (LENS), Laser Net Shape Manufacturing (LNSM), Direct Metal Deposition (DMD), Digital Light Processing (DLP), Direct Selective Laser Melting (DSLM), Selective Laser Melting (SLM), Direct Metal Laser Melting (DMLM), and other known processes.

The additive manufacturing processes described herein may be used for forming components using any suitable material. For example, the material may be plastic, metal, concrete, ceramic, polymer, epoxy, photopolymer resin, wax, or any other suitable material. These materials are examples of materials suitable for use in the additive manufacturing processes described herein and may be generally referred to as “additive materials.”

In addition, one skilled in the art will appreciate that a variety of materials and methods for bonding those materials may be used and are contemplated as within the scope of the present disclosure. As used herein, references to “fusing” may refer to any suitable process for creating a bonded layer of any of the above materials. For example, if an object is made from polymer, fusing may refer to creating a thermoset bond between polymer materials. If the object is epoxy, the bond may be formed by a crosslinking process. If the material is ceramic, the bond may be formed by a sintering process. If the material is powdered metal, the bond may be formed by a melting or sintering process. One skilled in the art will appreciate that other methods of fusing materials to make a component by additive manufacturing are possible, and the presently disclosed subject matter may be practiced with those methods.

In addition, the additive manufacturing process disclosed herein allows a single component to be formed from multiple materials. Thus, the components described herein may be formed from any suitable mixtures of the above materials. For example, a component may include multiple layers, segments, or parts that are formed using different materials, processes, and/or on different additive manufacturing machines. In this manner, components may be constructed that have different materials and material properties for meeting the demands of any application. In addition, the components described herein may be constructed entirely by additive manufacturing processes, or all or a portion of these components may be formed via casting, machining, and/or any other suitable manufacturing process. Indeed, any suitable combination of materials and manufacturing methods may be used to form these components.

An exemplary additive manufacturing process will now be described. Additive manufacturing processes fabricate components using three-dimensional (3D) information, for example a three-dimensional computer model, of the component. Accordingly, a three-dimensional design model of the component may be defined prior to manufacturing. In this regard, a model or prototype of the component may be scanned to determine the three-dimensional information of the component. As another example, a model of the component may be constructed using a suitable computer aided design (CAD) program to define the three-dimensional design model of the component as depicted inFIGS.2A-6.

The design model may include 3D numeric coordinates of the entire configuration of the component including both external and internal surfaces of the component. For example, the design model may define the body, the surface, and/or internal passageways such as openings, support structures, etc. In one exemplary embodiment, the three-dimensional design model is converted into a plurality of slices or segments, e.g., along a central (e.g., vertical) axis of the component or any other suitable axis. Each slice may define a thin cross section of the component for a predetermined height of the slice. The plurality of successive cross-sectional slices together form the 3D component. The component is then “built-up” slice-by-slice, or layer-by-layer, until finished.

In this manner, the components described herein may be fabricated using the additive process, or more specifically each layer is successively formed, e.g., by fusing or polymerizing a plastic using laser energy or heat or by sintering or melting metal powder. For example, a particular type of additive manufacturing process may use an energy beam, for example, an electron beam or electromagnetic radiation such as a laser beam, to sinter or melt a powder material or polymerize a liquid. Any suitable laser and laser parameters may be used, including considerations with respect to power, laser beam spot size, and scanning velocity. The build material may be formed by any suitable powder or material selected for enhanced strength, durability, and useful life, particularly at high temperatures.

Each successive layer may be, for example, between about 10 μm and 200 μm, although the thickness may be selected based on any number of parameters and may be any suitable size according to alternative embodiments. Therefore, utilizing the additive formation methods described above, the components described herein may have cross sections as thin as one thickness of an associated powder layer, e.g., 10 μm, utilized during the additive formation process.

In addition, utilizing an additive process, the surface finish and features of the components may vary as needed depending on the application. For example, the surface finish may be adjusted (e.g., made smoother or rougher) by selecting appropriate laser scan parameters (e.g., laser power, scan speed, laser focal spot size, etc.) during the additive process, especially in the periphery of a cross-sectional layer that corresponds to the part surface. For example, a rougher finish may be achieved by increasing laser scan speed or decreasing the size of the melt pool formed, and a smoother finish may be achieved by decreasing laser scan speed or increasing the size of the melt pool formed. The scanning pattern and/or laser power can also be changed to change the surface finish in a selected area.

Notably, in exemplary embodiments, several features of the components described herein were previously not possible due to manufacturing restraints. However, the present inventors have advantageously utilized current advances in additive manufacturing techniques to develop exemplary embodiments of such components generally in accordance with the present disclosure. While the present disclosure is not limited to the use of additive manufacturing to form these components generally, additive manufacturing does provide a variety of manufacturing advantages, including ease of manufacturing, reduced cost, greater accuracy, etc.

In this regard, utilizing additive manufacturing methods, even multi-part components may be formed as a single piece of additive ceramic or additive plastic, and may thus include fewer sub-components and/or joints compared to prior designs. The integral formation of these multi-part components through additive manufacturing may advantageously improve the overall assembly process. For example, the integral formation reduces the number of separate parts that must be assembled, thus reducing associated time and overall assembly costs. Additionally, existing issues with, for example, leakage, joint quality between separate parts, and overall performance may advantageously be reduced.

Also, the additive manufacturing methods described above enable much more complex and intricate shapes and contours of the components described herein. In addition, the additive manufacturing process enables the manufacture of a single component having different materials such that different portions of the component may exhibit different performance characteristics. The successive, additive nature of the manufacturing process enables the construction of these novel features. As a result, the components described herein may enable more intricate internal cast component shapes.

Referring now toFIG.7, a flow diagram of a method200for casting a component is presented. The exemplary method200includes at210providing a casting core within a cavity of a component mold. The cavity of the component mold may define an outer component shape and the casting core may define an inner component shape. The casting core may comprise a core wall, the core wall defining a core outer surface and a core inner surface disposed opposite the core outer surface. The core inner surface may define a core cavity, and the casting core may include a removal facilitation feature. The exemplary method200includes at212, casting the component within the cavity of the mold with the casting core positioned therein. The exemplary method200includes at214, removing the component from the mold, with the casting core positioned internally within the component. Additionally, the exemplary method200includes at216, removing the casting core from the cast component.

Referring again toFIG.1, in general, the engine100may include a core gas turbine engine (indicated generally by reference character114) and a fan section116positioned upstream thereof. The core engine114may generally include a substantially tubular outer casing118that defines an annular inlet120. In addition, the outer casing118may further enclose and support a booster compressor122for increasing the pressure of the air that enters the core engine114to a first pressure level. A high pressure, multi-stage, axial-flow compressor124may then receive the pressurized air from the booster compressor122and further increase the pressure of such air. The pressurized air exiting the high-pressure compressor124may then flow to a combustor126within which fuel is injected by a fuel system162into the flow of pressurized air, with the resulting mixture being combusted within the combustor126. The high energy combustion products are directed from the combustor126along the hot gas path of the engine100to a first (high pressure, HP) turbine128for driving the high pressure compressor124via a first (high pressure, HP) drive shaft130, and then to a second (low pressure, LP) turbine132for driving the booster compressor122and fan section116via a second (low pressure, LP) drive shaft134that is generally coaxial with first drive shaft130. After driving each of turbines128and132, the combustion products may be expelled from the core engine114via an exhaust nozzle136to provide propulsive jet thrust.

It should be appreciated that each turbine128,132may generally include one or more turbine stages, with each stage including a turbine nozzle and a downstream turbine rotor. As will be described below, the turbine nozzle may include a plurality of vanes disposed in an annular array about the centerline axis112of the engine100for turning or otherwise directing the flow of combustion products through the turbine stage towards a corresponding annular array of rotor blades forming part of the turbine rotor. As is generally understood, the rotor blades may be coupled to a rotor disk of the turbine rotor, which is, in turn, rotationally coupled to the turbine's drive shaft (e.g., drive shaft130or134).

Additionally, as shown inFIG.1, the fan section116of the engine100may generally include a rotatable, axial-flow fan rotor138surrounded by an annular fan casing140. In particular embodiments, the (LP) drive shaft134may be connected directly to the fan rotor138such as in a direct-drive configuration. In alternative configurations, the (LP) drive shaft134may be connected to the fan rotor138via a speed reduction device137such as a reduction gear gearbox in an indirect-drive or geared-drive configuration. Such speed reduction devices may be included between any suitable shafts/spools within engine100as desired or required.

It should be appreciated by those of ordinary skill in the art that the fan casing140may be supported relative to the core engine114by a plurality of substantially radially-extending, circumferentially-spaced outlet guide vanes142. As such, the fan casing140may enclose the fan rotor138and its corresponding fan rotor blades144. Moreover, a downstream section146of the fan casing140may extend over an outer portion of the core engine114to define a secondary, or by-pass, airflow conduit148that provides additional propulsive jet thrust.

During operation of the engine100, it should be appreciated that an initial air flow150(indicated by arrow) may enter the engine100through an associated inlet152of the fan casing140. The initial air flow150then passes through the fan blades144and splits into a first compressed air flow154(indicated by arrow) that moves through conduit148and a second compressed air flow156(indicated by arrow) that enters the booster compressor122. The pressure of the second compressed air flow156is then increased and enters the high-pressure compressor124(as indicated by arrow158). After mixing with fuel and being combusted within the combustor126, the combustion products160exit the combustor126and flow through the first turbine128. Thereafter, the combustion products160flow through the second turbine132and exit the exhaust nozzle136to provide thrust for the engine100.

Clause 1. A method for casting a component, the method comprising: providing a casting core within a cavity of a component mold, wherein the cavity of the component mold defines an outer component shape and the casting core defines an inner component shape, the casting core comprising a core wall, the core wall defining a core outer surface and a core inner surface disposed opposite the core outer surface, wherein the core inner surface defines a core cavity, and wherein the casting core includes a removal facilitation feature; casting the cast component within the cavity of the component mold with the casting core positioned therein; removing the cast component from the component mold, with the casting core positioned internally within the component; and removing the casting core from the cast component.

Clause 2. The method of any preceding clause, wherein the core wall comprises a plurality of core layers.

Clause 3. The method of any preceding clause, wherein the casting core is formed by a core-formation method comprising: inserting an injection apparatus into a core mold, wherein the core mold is formed with a core mold inner face being the negative of a casting core outer shape; low depositing a layer of a core material on the core mold inner face; forming the removal facilitation feature by depositing additional layers of the core material until a core wall thickness of 0.1 mm to 5 mm is established; and removing the casting core from the core mold.

Clause 4. The method of any preceding clause, wherein the removal facilitation feature comprises the core wall having a core wall thickness of 0.1 mm to 5 mm.

Clause 5. The method of any preceding clause, wherein the casting core is formed by an additive manufacturing process.

Clause 6. The method of any preceding clause, wherein the component mold is formed by the additive manufacturing process simultaneously with forming the casting core.

Clause 7. The method of any preceding clause, wherein the casting core is formed by a core-formation method comprising: forming a sub-core comprising a sub-core material; securing the sub-core within a core mold, wherein the core mold is formed with a core mold inner face being the negative of a core outer shape; introducing a core material into the core mold to form the core wall; removing the casting core from the core mold; and leaching the sub-core from the casting core.

Clause 8. The method of any preceding clause, wherein the removal facilitation feature comprises: a support web contained within the core cavity and coupled to the core inner surface.

Clause 9. The method of any preceding clause, wherein the support web is a single structural member with a first support end coupled to a first inner surface attachment location and a second support end coupled to a second inner surface attachment location.

Clause 10. The method of any preceding clause, wherein the support web comprises: a plurality of support members each having a first support end coupled to a first inner surface attachment location and a second support end coupled to a second inner surface attachment location.

Clause 11. The method of any preceding clause, wherein the support web is a ceramic foam or a metallic foam.

Clause 12. The method of any preceding clause, wherein the casting core is formed by a core-formation method comprising: forming a sub-core comprising the support web; securing the sub-core within a core mold having a core mold inner face that is the negative of a core outer shape; introducing a core material into the core mold to form the core outer shape; and removing the casting core from the core mold.

Clause 13. The method of any preceding clause, wherein the casting core and the support web are formed simultaneously by an additive manufacturing process.

Clause 14. The method of any preceding clause, wherein the support web comprises: a plurality of support members each having a first support end coupled to a first inner surface attachment location and a second support end coupled to a second inner surface attachment location, the plurality of support members forming a lattice structure spanning the core cavity.

Clause 15. The method of any preceding clause, further comprising: forming the core wall, the core outer surface, and the core inner surface; and introducing an expanding foam into the core cavity.

Clause 16. The method of any preceding clause, wherein the cast component is a turbine engine component.

Clause 17. The method of any preceding clause, wherein the removal facilitation feature comprises: a first core material having a thickness of 0.1 mm to 5 mm; and a second core material contained within the core cavity, wherein the second core material leaches at a faster rate than the first core material.

Clause 18. The method of any preceding clause, further comprising: forming a sub-core comprising the second core material; securing the sub-core within a core mold having a core mold inner face that is the negative of a core outer shape; introducing the first core material into the core mold to form the core outer shape; and removing the casting core from the core mold.

Clause 19. The method of any preceding clause, further comprising: inserting an injection apparatus into a core mold having a core mold inner face that is the negative of a casting core outer shape; depositing a layer of the first core material on the core mold inner face; depositing additional layers of the first core material until a core wall having a thickness of 0.1 mm to 5 mm is established; introducing the second core material into the cavity; and removing the casting core from the core mold.

Clause 20. The method of any preceding clause, wherein the casting core is formed by an additive manufacturing process.