Patent Grant
10793943
This disclosure relates generally to methods of producing hollow gas turbine engine components and more particularly to methods of producing hollow gas turbine engine components using additive manufacturing processes.
Historically, some gas turbine engine airfoils (e.g., fan blades, vanes, etc.) have been made from a solid metal (e.g., nickel, aluminum, titanium, or alloys thereof). Such airfoils, particularly large airfoils such as fan blades from a high bypass gas turbine engine, can have significant weight. Some gas turbine engines utilize hollow airfoils that are lighter relative to solid airfoils of similar configuration. Hollow airfoils, while being relatively lighter in weight, can be difficult and expensive to manufacture. For example, in some instances a hollow fan blade may be formed by initially producing a forging. The forging is subsequently formed into a near shape form having a volume significant enough to contain the entire fan blade. A three dimensional geometry representative of the final airfoil geometry may be formed by removing material from the initial forging. In some instances, hollow passages may be formed by “gun drilling” processes. Gun drilling processes tend to be a tedious and inefficient method for removing core material. In other instances, a hollow interior cavity may be formed (e.g., a milled pocket), which interior cavity may be later enclosed by a cover (sometimes referred to as a “sheath”) affixed to the airfoil body. These methods of forming a hollow airfoil typically require significant machining, generate a significant amount of waste metal, and require a substantial lead time. In addition, there are geometric limitations to airfoil features that can be achieved by machining processes.
Accordingly, there is a need for a methodology capable of producing three-dimensional hollow bodies, including but not limited to gas turbine engine fan blades and vanes, capable of producing complex shapes in less time and in a cost effective manner.
According to an aspect of the present disclosure, a method of producing a gas turbine engine fan blade having a geometric configuration is provided. The method includes: plastically deforming an initial substrate comprised of a first metallic material into a formed substrate that has a first face surface, a second face surface, which first face surface is opposite the second face surface, a first end surface and a second end surface, which second end surface is opposite the first end surface; depositing a second metallic material onto the formed substrate using an additive manufacturing process to produce a blade blank, which depositing includes: additively depositing second metallic material to at least one of the first face surface or the second face surface of the formed substrate adjacent the first end surface, to form a root portion; additively depositing second metallic material to at least one of the first face surface or the second face surface of the formed substrate between the root portion and the second end surface to form an airfoil portion; and shaping the blade blank into the geometric configuration of the gas turbine engine fan blade.
According to another aspect of the present disclosure, a method of producing a hollow airfoil having a geometric configuration is provided. The method includes: plastically deforming an initial substrate comprised of a first metallic material into a formed substrate that has a first face surface, a second face surface, which first face surface is opposite the second face surface, a first end surface and a second end surface, which second end surface is opposite the first end surface; depositing a second metallic material on at least one of the first face surface or the second face surface of the formed substrate between the first end surface and the second end surface using an additive manufacturing process; and shaping the blade blank into the geometric configuration of the gas turbine engine fan blade.
In any of the aspects or embodiments described above and herein, the first metallic material and the second metallic material may each comprise titanium.
In any of the aspects or embodiments described above and herein, the step of depositing the second metallic material to form an airfoil portion, may include depositing the second metallic material to define at least one internal cavity.
In any of the aspects or embodiments described above and herein, the step of depositing the second metallic material to form an airfoil portion may include depositing the second metallic material to define a plurality of internal cavities and at least one rib separating adjacent internal cavities.
In any of the aspects or embodiments described above and herein, the step of depositing the second metallic material to form the airfoil portion, may include defining a shelf surface extending around a perimeter of the at least one internal cavity.
In any of the aspects or embodiments described above and herein, the method may include attaching a cover panel to enclose the at least one internal cavity.
In any of the aspects or embodiments described above and herein, the method may include plastically deforming a substrate to form a cover panel, the cover panel configured to mate with a shelf surface.
In any of the aspects or embodiments described above and herein, the step of depositing the second metallic material onto the formed substrate using an additive manufacturing process includes depositing second metallic material to the first face surface of the formed substrate between the root portion and the airfoil portion, and to the second face surface of the formed substrate between the root portion and the airfoil portion to form a platform portion.
In any of the aspects or embodiments described above and herein, the additive manufacturing process may be a plasma arc, wire feed deposition process.
In any of the aspects or embodiments described above and herein, the step of plastically deforming the initial substrate may include hot forming the initial substrate.
In any of the aspects or embodiments described above and herein, at least a portion of the first face surface of the formed substrate may have a convex configuration, and at least a portion of the second face surface of the formed substrate may have a concave configuration.
In any of the aspects or embodiments described above and herein, the step of shaping the blade blank into the geometric configuration of the gas turbine engine fan blade includes producing a leading edge, a trailing edge, and a blade tip surface extending between the leading edge and the trailing edge.
The foregoing features and the operation of the present disclosure will become more apparent in light of the following description and the accompanying drawings.
It is noted that various connections are set forth between elements in the following description and in the drawings (the contents of which are included in this disclosure by way of reference). It is noted that these connections are general and, unless specified otherwise, may be direct or indirect and that this specification is not intended to be limiting in this respect. A coupling between two or more entities may refer to a direct connection or an indirect connection. An indirect connection may incorporate one or more intervening entities.
In the disclosure that follows certain relative positional terms are used such as “forward”, “aft”, “upper”, “lower”, “above”, “below”, “inner”, “outer” and the like. These terms are used with reference to the normal operational attitude of a gas turbine engine and should not be considered otherwise limiting. The forward end of a gas turbine engine generally refers to the axial end of the engine where air is drawn into the engine, and the aft end of the engine generally refers to the opposite axial end where air and other products are expelled from the engine. When referring to an airfoil (e.g., a fan blade), the term “leading edge” generally means the upstream edge of the airfoil, and the term “trailing edge” generally means the downstream edge of the airfoil. The term “radially outward” as used herein generally refers to a direction extending away from the axially extending engine center axis, and the term “radially inward” refers to a direction extending toward the engine center axis.
Referring now to the
The exemplary engine 20 shown in
The low speed spool 30 generally includes an inner shaft 40 that interconnects a fan 42, a low pressure compressor 44 and a low pressure turbine 46. The inner shaft 40 is connected to the fan 42 through a speed change mechanism, which in exemplary gas turbine engine 20 is illustrated as a geared architecture 48 to drive the fan 42 at a lower speed than the low speed spool 30. The high speed spool 32 includes an outer shaft 50 that interconnects a high pressure compressor 52 and high pressure turbine 54. A combustor 56 is arranged in exemplary gas turbine 20 between the high pressure compressor 52 and the high pressure turbine 54. The inner shaft 40 and the outer shaft 50 are concentric and rotate via bearing systems 38 about the engine central longitudinal axis “A” which is collinear with their longitudinal axes.
The core airflow is compressed by the low pressure compressor 44 then the high pressure compressor 52, mixed and burned with fuel in the combustor 56, then expanded over the high pressure turbine 54 and low pressure turbine 46. The turbines 46, 54 rotationally drive the respective low speed spool 30 and high speed spool 32 in response to the expansion. It will be appreciated that each of the positions of the fan section 22, compressor section 24, combustor section 26, turbine section 28, and geared architecture 48 may be varied. For example, geared architecture 48 may be located aft of combustor section 26 or even aft of turbine section 28, and fan section 22 may be positioned forward or aft of the location of geared architecture 48.
The gas turbine engine 20 diagrammatically depicted in
The present disclosure is directed to a method of manufacturing a three-dimensional component (e.g., a gas turbine engine rotor blade such as a fan blade, a guide vane, struts, gas path component, etc.) and to the components themselves. To simplify the description, the present disclosure will be described in terms of a gas turbine engine fan blade. The present disclosure is not, however, limited to methods for manufacturing gas turbine engine fan blades.
Referring to
Each root portion 64 is configured to be received in a mating void (sometimes referred to as a “groove” or “slot”—not shown) disposed in a hub configured to be rotated about an axially extending centerline; e.g. the axial centerline of the engine. In a geared turbofan engine, the axial centerline of the fan section of the engine may be displaced from the axial centerline of other sections of the engine; e.g., the compressor section and/or the turbine section. The mating configuration between the root portion 64 and respective void maintains the connection between the respective fan blade and the hub as the hub rotates. The root portion 64 may have a variety of different configurations; e.g., a “dovetail” configuration, a “fir tree” configuration, etc. The present disclosure is not limited to any particular root portion configuration. The root portion 64 may be solid or may be hollow (e.g., have one or more interior cavities).
In those fan blade embodiments that include a platform 66, the platform 66 typically includes a first side portion 66A that extends generally circumferentially outwardly from one side of the fan blade 60 (e.g., circumferentially outwardly from the concave side surface), and a second side portion 66B that extends generally circumferentially outwardly from the opposite side of the fan blade (e.g., circumferentially outwardly from the convex side surface). Collectively, the fan blade platforms 66 within a fan blade stage collectively form a radially inward gas path surface.
An aspect of the present disclosure includes a method of manufacturing a hollow component, which component is described hereinafter as a hollow fan blade. As indicated above, however, the present method may be used to produce a variety of different components and is not limited to making hollow fan blades.
Referring to
The material properties (e.g., type of material, metallurgical properties, etc.) of the initial substrate 78 may depend on the particular component being manufactured, and the operating environment in which the component is designed to operate (e.g., thermal, loading, stress environments etc.) For performance and durability, the operating environment of a component may dictate that certain materials are preferred over other materials. In terms of a fan blade for a gas turbine engine, the initial substrate 78 may for example comprise a titanium alloy or aluminum alloy. In terms of a turbine exhaust guide vane, which has a much higher temperature operating environment, the initial substrate 78 may, for example, comprise a nickel alloy.
In some applications, the initial substrate 78 may be subjected to a forming process that plastically deforms the initial substrate into a predetermined three-dimensional geometry (referred to hereinafter as a “formed substrate 92”). For example, when the present method is used to manufacture a fan blade, the initial substrate 78 may be formed (i.e., plastically deformed) to create a formed substrate 92 having a concave side and a convex side, with a predetermined twist that will affect the camber and chord lines of the finished airfoil portion 62 of the fan blade 60. The amount of predetermined twist may vary along the radial extent of the airfoil portion 62. A variety of different processes may be used to form (plastically deform) the initial substrate 78, and the present method is not limited to any particular forming process.
An example of an acceptable forming process is a “hot forming” process wherein the initial substrate 78 is heated to an elevated temperature that will facilitate plastic deformation of the initial substrate 78. The heated initial substrate 78 may be subsequently placed in a forming press (e.g., with dies configured to create the desired geometry) and an adequate amount of force applied to cause the plastic deformation of the initial substrate 78. The initial substrate is subsequently cooled and thereafter retains its formed geometry; i.e., it is the “formed substrate 92”; e.g., see
The formed substrate 92 is subsequently subjected to an additive manufacturing process wherein a material compatible with the material of the formed substrate 92 (e.g., the same type of material) is added to regions of the formed substrate 92. In general terms, additive manufacturing techniques involve successively added layers of material to a substrate. Some additive manufacturing processes use energy from an electron beam or a laser beam to melt and deposit a feed stock (e.g., a wire or a powder flow). Other additive manufacturing processes used a plasma arc to melt and deposit a feed stock (e.g., a wire or a powder flow). The present disclosure is not limited to any particular type of additive manufacturing process. An example of an acceptable additive manufacturing process is one that uses a plasma are and a wire feed stock. In many instances, it is desirable to have the material added during the additive manufacturing process be the same as, or nearly the same as, the material comprising the formed substrate. For example, in the example of manufacturing a titanium fan blade, the formed substrate may be a titanium alloy and the feed stock being additively deposited on the formed substrate during the additive manufacturing process may be the same titanium alloy, or a compatible titanium alloy.
Two specific examples of acceptable additive manufacturing processes that utilize a plasma are and a wire feed stock are disclosed in U.S. Pat. Nos. 9,481,931 and 9,346,116, both of which are issued to Norsk Titanium AS of Norway, and each of which is hereby incorporated by reference in its entirety. The ‘931 patent is directed to a “Method and Arrangement for Building Metallic Objects by Solid Freeform Fabrication”, and discloses a device that includes a welding torch with an integrated wire feeder, a system for positioning and moving a substrate relative to the welding torch, and a control system operable to utilize a computer assisted design (CAD) model to regulate the position and movement of the substrate relative to the welding torch. The ‘931 patent further discloses that the welding torch may comprise first and second plasma transferred arc (PTA) torches, each configured to heat and excite a stream of inert gas to a plasma plume extending out from a nozzle. The thermal energy from the plasma plumes creates a molten pool of substrate material and melted feed stock for deposition on the substrate. In terms of methodology, the ‘931 patent discloses the steps of: a) employing a holding substrate made of a similar metallic material as the object is to be made of, and each successive deposit is obtained by; i) employing a first plasma transferred arc (PTA) to preheat and form a molten pool in the base material at the position at which the metallic material is to be deposited, ii) feeding the metallic material to be deposited in the form of a wire to a position above the molten pool, iii) employing a second plasma transferred arc (PTA) to heat and melt the wire such that molten metallic material is dripping into the molten pool, and iv) moving the holding substrate relative to the position of the first and second PTA in a predetermined pattern such that the successive deposits of molten metallic material solidifies and forms the three-dimensional object. The ‘931 patent discloses further that the methodology may be automated using a system for positioning and moving the holding substrate relative to the welding torch, and a control system able to read a computer assisted design (CAD) model of the object which is to be formed and employ the CAD-model to regulate the position and movement of the system for positioning and moving the holding substrate and to operate the welding torch with integrated wire feeder such that a physical object is built by fusing successive deposits of the metallic material onto the holding substrate. The ‘116 patent is directed to a “Method and Device for Manufacturing Titanium Objects”. The devices and methodologies disclosed in these patents are non-limiting examples of acceptable additive manufacturing processes.
The formed substrate 92 with the deposited additive material 97, which is a unitary body, may be referred to as a “component blank” or a “blade blank”. The component blank may be altered (e.g., machined, or otherwise formed) to a finished geometry that requires no further geometric alteration, or to a semi-finished geometry that generally reflects the finished geometry of component (e.g., the fan blade). For example, a component blank, as described above and shown in
The present disclosure is not limited to any particular order or process for forming a component blank into a substantially finished component; e.g., a substantially finished fan blade. Indeed, the particular order of forming a component blank into a substantially finished component may vary depending on the component being manufactured. For example, in some instances the forming processes (e.g., machining) used to substantially finish the airfoil portion 62 of a fan blade 60 may have a higher error rejection rate than the forming processes of other portions of the fan blade; e.g., the root or platform portions 64, 66. In such instances, the airfoil portion 62 may be formed before other portions and inspected for defects. If an insurmountable defect is produced during the airfoil formation process, the partially formed fan blade may be scrapped. On the other hand if no defects are incurred during the airfoil formation process, the remaining portions of the fan blade may be formed.
As indicated above, the fan blade embodiment shown in
In some instances, the present disclosure may include additional steps in the manufacturing of a component. For example, in some instances the blade blank shape into the geometric configuration of the gas turbine engine fan may be heat treated to create desirable metallurgical properties, and/or may be subjected to “surface finishing” processes that produce a desirable surface finish. The present method does not require these additional steps or others.
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