Patent Description:
Guide vanes of a gas turbine engine typically include an airfoil body that is disposed between a radially inner platform defined on a foot of the guide vane, and a radially outer platform defined on a head of the guide vane. Guide vanes are typically arranged in rows and serve to guide the gas stream passing through the engine to a desired speed and angle. Guide vanes must also withstand erosion, abrasion, and impact from foreign objects that may enter the gas turbine engine. Guide vanes are generally made of metal, but it is becoming desirable to make them out of composite materials to reduce their weight. Unfortunately, methods of fabricating guide vanes out of composite materials can be complex, require expensive tooling and are time consuming. Improvement is desirable.

A prior art method of manufacturing a composite guide vane of a gas turbine engine having the features of the preamble of claim <NUM> is disclosed in <CIT>.

In one aspect, the present invention provides a method of manufacturing a composite guide vane of a gas turbine engine in accordance with claim <NUM>.

In another aspect, the present invention provides a guide vane for a gas turbine engine in accordance with claim <NUM>.

The following disclosure describes constructions of composite guide vanes for gas turbine engines and methods for manufacturing such composite guide vanes. In some embodiments, the methods described herein can facilitate the manufacturing of composite guide vanes in a relatively simpler and time efficient manner using fiber-reinforced unidirectional tape for example. In some embodiments, the methods described herein can also facilitate the retention of a metallic leading edge on a composite guide vane.

The terms "attached", "connected" or "coupled" may include both direct attachment, connection or coupling (in which the two components contact each other) and indirect attachment, connection or coupling (in which at least one additional component is located between the two components). The term "substantially" as used herein may be applied to modify any quantitative representation which could permissibly vary without resulting in a change in the basic function to which it is related.

<FIG> illustrates a gas turbine engine <NUM> of a type preferably provided for use in subsonic flight, generally comprising in serial flow communication, a fan <NUM> through which ambient air is propelled, a multistage compressor <NUM> for pressurizing the air, a combustor <NUM> in which the compressed air is mixed with fuel and ignited for generating an annular stream of hot combustion gases, and a turbine section <NUM> for extracting energy from the combustion gases. Engine <NUM> may be of a type suitable for use in aircraft applications. For example, engine <NUM> may be a turbofan (as illustrated), a turboshaft or a turboprop type of engine.

Engine <NUM> may also include one or more guide vanes <NUM> (referred hereinafter in the singular) made using one or more methods described herein. Vane <NUM> may be of a type known as a "guide vane" or "stator vane" that are used to direct fluid flow toward a desired direction so as to be received into downstream rotor blades at a desired angle for example. In some embodiments, vane <NUM> may be suitable for installation in a core gas path <NUM> of engine <NUM>. For example, vane <NUM> may be a (e.g., variable orientation) inlet guide vane disposed upstream of compressor <NUM>. Vane <NUM> may instead be disposed between two rotor stages of compressor <NUM>. Alternatively, vane <NUM> may be a bypass stator vane disposed in a bypass duct <NUM> of turbofan engine <NUM>. In various embodiments, vane <NUM> may have a fixed orientation within engine <NUM> or may have a controllably variable orientation within engine <NUM>.

Engine <NUM> may have central axis CA corresponding to an axis of rotation of one or more spools of engine <NUM>. Bypass duct <NUM> may extend generally annularly about central axis CA. Core gas path <NUM> may also extend generally annularly about central axis CA. In some embodiments of engine <NUM>, a plurality of vanes <NUM> may be angularly distributed about central axis CA in bypass duct <NUM> and/or in core gas path <NUM>.

<FIG> is a perspective view of an exemplary vane <NUM> of engine <NUM>. Vane <NUM> includes body <NUM> for interacting with a flow of fluid. Body <NUM> is made from a fiber-reinforced composite material. Vane <NUM> also includes metallic sheath <NUM> covering part of body <NUM>. Metallic sheath <NUM> defines leading edge <NUM> of vane <NUM>. Metallic sheath <NUM> may provide resistance against erosion, abrasion and impact from foreign objects that may enter engine <NUM>. Leading edge <NUM> and trailing edge <NUM> of vane <NUM> are illustrated in relation to a general direction F of the flow of fluid interacting with vane <NUM>.

Vane <NUM> also has foot <NUM> and/or head <NUM> attached to respective opposite ends of vane <NUM>. In some embodiments, vane <NUM> may have either foot <NUM> or head <NUM> for attachment of vane <NUM> only from one end of vane <NUM>. In relation to central axis CA of engine <NUM>, foot <NUM> may be disposed at a radially-inner end of body <NUM> of vane <NUM>. Head <NUM> may be disposed at a radially-outer end of body <NUM> of vane <NUM>. Foot <NUM> may serve for the attachment of vane <NUM> to a radially-inner support structure (e.g., inner ring, shroud, engine casing, low pressure compressor housing) and head <NUM> may be used to attach the same vane <NUM> to a radially-outer support structure (e.g., outer ring, shroud, engine casing. Vane <NUM> may also include radially-inner platform <NUM> and radially-outer platform <NUM> for interacting with the flow of fluid. Platforms <NUM>, <NUM> may define flow-interacting surfaces between guide vanes <NUM> that are adjacent in the angular/circumferential direction about central axis CA. Foot <NUM> and head <NUM> may have a generally T-shape, L-shape or any shape suitable to facilitate installation and attachment of vane <NUM> within engine <NUM>.

<FIG> is a flowchart of an exemplary method <NUM> for manufacturing vane <NUM> or other vane made of fiber-reinforced composite material. Aspects of method <NUM> may be combined with aspects of other methods and may include other actions and/or aspects described herein. Aspects of method <NUM> are further described below in relation to <FIG>. Method <NUM> includes: receiving body <NUM> (shown in <FIG>) made of a fiber-reinforced composite material (e.g., see block <NUM>), body <NUM> including body mid portion <NUM> for interacting with a fluid and body end portions <NUM> and/or <NUM> (shown in <FIG>); applying metallic sheath <NUM> on part of body <NUM> (e.g., see block <NUM>), metallic sheath <NUM> including: sheath mid portion <NUM> defining a leading edge of vane <NUM>;
and sheath end portions <NUM> and/or <NUM> applied respectively to body end portions <NUM> and/or <NUM> of body <NUM> (shown in <FIG>); and overmolding head <NUM> and/or foot <NUM> onto body end portion(s) <NUM> and/or <NUM> of body <NUM> and onto sheath end portion(s) <NUM> and/or <NUM> (e.g., see block <NUM> and <FIG>).

<FIG> is a flowchart of an exemplary method <NUM> for manufacturing body <NUM> of vane <NUM>. Aspects of method <NUM> may be combined with aspects of other methods and may include other actions and/or aspects described herein. Aspects of method <NUM> are further described below in relation to <FIG>. In various embodiments, method <NUM> may include: receiving a precursor (e.g., layup <NUM> shown in <FIG>) including substantially parallel and non-interlaced reinforcement fibers embedded in a resin (see block <NUM>); compression molding the precursor into preform <NUM> of a core of vane body <NUM> (see block <NUM> and <FIG>); and overmolding a skin of vane body <NUM> on preform <NUM> of the core (see block <NUM> and <FIG>).

In various embodiments of the methods described herein, body <NUM> may be made from any suitable fiber-reinforced composite material(s) using any suitable process. For example, body <NUM> may include long and/or short fibers embedded in a suitable (e.g., polymeric) matrix material. Fibers may, for example, be made from glass and/or carbon. Matrix materials may include thermoplastic resins and/or thermosetting resins. In various embodiments, suitable matrix materials for body <NUM>, foot <NUM> and/or head <NUM> may include polyether ether ketone (PEEK), such as product numbers 450CA30 or 90HMF40 by VICTREX™, polyamide, epoxy, polyurethane, phenolic and amino resins, and bismaleimides (BMI) for example.

In some embodiments, body <NUM> may be made by stacking pre-impregnated (e.g., woven) tissue/fabric layers and forming such stack of layers in a mold using heat. Alternatively, a resin transfer molding (RTM) process may be used with dry tissue/fabric layers. In some embodiments, body <NUM> may be partially or entirely made by injection molding using randomly oriented short fibers embedded in a thermoplastic or thermosetting matrix material. Such short fibers may have lengths of a few millimeters or less. For example, such short fibers may have lengths of about <NUM> or less. In some embodiments, such short fibers may have lengths of about <NUM> or less. In some embodiments, such short fibers may have lengths of about <NUM> or less. In some embodiments, body <NUM> may be made of a thermosetting or thermoplastic material that is devoid of any fiber reinforcement. In some embodiments, an inner/central core of body <NUM> may, as described below, include long continuous and optionally unidirectional fibers embedded in a suitable thermosetting or thermoplastic matrix material. The core of body <NUM> may include a location of a mid section or mid point of a mean camber line of body <NUM>. The core of body <NUM> may include an innermost region of body <NUM> located at a depth from the skin of body <NUM>.

<FIG> is a schematic representation of an exemplary process for forming body <NUM> using layup <NUM> of fiber-reinforced composite sheets <NUM>. Each sheet <NUM> may be a continuous fiber reinforced thermoplastic (CFRT) composite. For example, each sheet <NUM> may be a layer of continuous, substantially parallel and non-interlaced fibers pre-impregnated with a thermoplastic or thermosetting resin. In some embodiments, each sheet <NUM> may be of a type known as "unidirectional tape" or "UD tape" where a single-layered, fiber-reinforced (e.g., thermoplastic) composite sheet in which long continuous fibers are unrolled, laid and impregnated with a (e.g., thermoplastic) resin. The UD tape may be pre-impregnated with resin. In some embodiments, each sheet <NUM> may be a woven tissue/fabric cloth that is pre-impregnated with resin. As non-limiting examples, sheets <NUM> may each have a thickness of about <NUM> inch (<NUM>) or about <NUM> inch (<NUM>).

Sheets <NUM> may be cut automatically on a standard ply cutting table or formed using automated tape laying (ATL) equipment. Sheets <NUM> may be stacked manually or robotically in a mold. Sheets <NUM> may be pre-consolidated in a press or tack welded together before placing in the mold. Sheets <NUM> may be cut and stacked based on the desired final shape of body <NUM> after forming (e.g., stamping, compression molding) using mold portions 56A, 56B. Layup <NUM> of sheets <NUM> may be consolidated (e.g., at least partially densified) into a single unified precursor using heat and pressure prior to loading such consolidated precursor into a press defined by mold portions 56A, 56B for stamping.

The orientation of respective sheets <NUM> in layup <NUM> may be selected to tailor the mechanical properties of body <NUM> in desired loading directions. In various embodiments, sheets <NUM> in layup <NUM> may have different orientations (stacking angles). In some situations, the use of sheets <NUM> with continuous unidirectional fibers and stacking angles may provide control over the final mechanical properties of body <NUM>. In some embodiments, at least some sheets <NUM> and hence some of the continuous unidirectional fibers may extend continuously along substantially an entire span length SL (shown in <FIG>) of body <NUM>. For example, at least some of the long fibers from sheets <NUM> may extend continuously from radially-inner body end portion <NUM>, through body mid portion <NUM> and to radially-outer body end portion <NUM>.

<FIG> also shows a schematic representation of an optional step of injection overmolding a skin over preform <NUM> stamped using mold portions 56A, 56B and heat to obtain body <NUM>. Preform <NUM> may have a substantially solid (i.e., non-hollow) interior. In some situations, body <NUM> may be formed directly by stamping (e.g.. consolidated) layup <NUM> of pre-impregnated sheets <NUM> as shown in the upper part of <FIG>. Body <NUM> obtained from stamping layup <NUM> may have acceptable dimensional accuracy for some applications and may approximate the desired final shape of body <NUM>. However, in cases where higher dimensional accuracy is required or body <NUM> includes relatively sharp edges for example, the optional overmolding step as shown in the lower part of <FIG> may be additionally carried out. In this case, the product resulting from the stamping process would be (e.g., a single) preform <NUM> provided to the subsequent overmolding process. The lower part of <FIG> schematically shows body <NUM> as including preform <NUM> made from layup <NUM> of sheets <NUM> as described above that is encapsulated by overmolding material <NUM> to achieve the desired geometry of body <NUM>.

<FIG> shows schematic transverse cross-section views in relation to body <NUM>. Preform <NUM> produced by stamping layup <NUM> of sheets <NUM> using mold portions 56A, 56B and heat may be received in molds 60A, 60B where overmolding is carried out by the injection of overmolding material <NUM> when molds portions 60A, 60B are closed. Preform <NUM> may occupy a core region of body <NUM> and overmolding material <NUM> may occupy a skin region of body <NUM>. In some embodiments, preform <NUM> may occupy a majority of a transverse cross-sectional area of body <NUM> as shown in <FIG>. Overmolding material <NUM> may include a thermoplastic or thermosetting resin containing relatively short reinforcement fibers as described above. The fibers in overmolding material <NUM> may be shorter than the fibers in preform <NUM>. Alternatively, overmolding material <NUM> may include a thermoplastic or thermosetting resin that is devoid of reinforcement fibers. The thermoplastic or thermosetting resin selected for overmolding material <NUM> may be substantially identical or chemically compatible with a resin used in preform <NUM>.

In some situations, the use of optional overmolding may facilitate higher dimensional accuracy of body <NUM>. For example, overmolding material <NUM> may fill-in regions of body <NUM> that are not filled-in by preform <NUM> and thereby substantially establish the final shape of body <NUM>. It is understood that, in some situations, sanding, grinding or other process(es) may be performed on body <NUM> after the stamping and/or overmolding processes illustrated in <FIG>.

In some situations, sheath <NUM> may be placed into mold portions 56A, 56B together with layup <NUM>, and/or into mold portions 60A, 60B together with preform <NUM> and co-consolidated together with body <NUM> in the composite forming operation.

<FIG> also shows body <NUM> having a substantially symmetrical airfoil shape but it is understood that body <NUM> may instead have a cambered airfoil shape as shown in <FIG>.

<FIG> is a schematic cross-sectional view of another exemplary body <NUM> of vane <NUM>. Body <NUM> may be made according to the methods described above and may have a construction generally similar to that of body <NUM> already described above. Like elements are identified using like reference numerals. Body <NUM> may be made from a plurality of sheet <NUM> of continuous, substantially parallel and non-interlaced long fibers occupying a core of body <NUM>. The long-fiber core (e.g., preform <NUM> of <FIG>) of body <NUM> may optionally be encapsulated by overmolding material <NUM>.

<FIG> is a schematic cross-sectional view of body <NUM> with an optional metallic leading edge <NUM>. In some embodiments where supplemental leading edge protection is desired, metallic sheath <NUM> may be applied to part of body <NUM> so as to define leading edge <NUM> of body <NUM>. In some embodiments, metallic sheath <NUM> may be formed from sheet metal made of a titanium-based alloy, an aluminum-based alloy, a nickel-based alloy or stainless steel of the <NUM> series for example. Metallic sheath <NUM> may be formed to a desired shape by stamping for example. Alternatively, metallic sheath <NUM> may be formed as a coating by electrodeposition (i.e., electroforming, electroplating) or chemical vapor deposition. For example, metallic sheath <NUM> of a desired thickness may be deposited directly onto the applicable portion of body <NUM>. In some embodiments, metallic sheath <NUM> may be deposited on another substrate of a desired shape and then transferred (e.g., installed and adhesively bonded) onto body <NUM>. In some embodiments, metallic sheath <NUM> may be deposited as a coating based on the teachings of <CIT>. In some embodiments, metallic sheath <NUM> may be made from a nanocrystalline metallic material. For example, metallic sheath <NUM> may be applied by nickel plating directly on part (e.g., the leading edge portion) of body <NUM>. In some embodiments, metallic sheath <NUM> may have a thickness of between <NUM> inch (<NUM>) and <NUM> inch (<NUM>). In various embodiments, metallic sheath <NUM> may have a thickness of about <NUM> inch (<NUM>), about <NUM> inch (<NUM>) or about <NUM> inch (<NUM>).

In some embodiments where deposition (e.g., plating) of metallic sheath <NUM> directly onto body <NUM> is conducted, it may be desirable to have a skin of body <NUM> relatively resin rich for improved quality of plating of the metallic sheath <NUM> deposited on body <NUM>. Accordingly, overmolding material <NUM> may be devoid of fiber reinforcement or may have a relatively low volume fraction of reinforcement fibers.

In some embodiments, metallic sheath <NUM> may be adhesively bonded to body <NUM> using a suitable scrim-supported epoxy film adhesive or a polymeric adhesive material disposed between metallic sheath <NUM> and body <NUM>. Suitable surface preparation/treatment (e.g., abrasion) may be performed on surfaces of metallic sheath <NUM> and/or of body <NUM> to be bonded together to facilitate bonding.

<FIG> is a schematic perspective view of body <NUM> together with metallic sheath <NUM> to be applied to a forward portion of body <NUM>. Metallic sheath <NUM> may include sheath mid portion <NUM> for application to and wrapping around a forward portion of body mid portion <NUM> so that sheath mid portion <NUM> may define leading edge <NUM> (shown in <FIG>) of vane <NUM>. Radially-inner sheath end portion <NUM> may be applied to radially-inner body end portion <NUM>. Similarly, radially-outer sheath end portion <NUM> may be applied to radially-outer body end portion <NUM>. Body <NUM> may have a span length SL.

As explained further below, radially-inner sheath end portion <NUM> and radially-inner body end portion <NUM> may be regions to be encapsulated by overmolded foot <NUM> of vane <NUM>. Similarly, radially-outer sheath end portion <NUM> and radially-outer body end portion <NUM> may be regions to be encapsulated by overmolded head <NUM> of vane <NUM>. The overmolding of foot <NUM> or head <NUM> of vane <NUM> may provide mechanical retention of metallic sheath <NUM> onto body <NUM>.

Anchoring features are provided on metallic sheath <NUM> and optionally on body <NUM> for engagement with overmolded foot <NUM> and/or head <NUM> to further enhance the mechanical retention of metallic sheath <NUM> and body <NUM> into the overmolded foot <NUM> and/or head <NUM>. As illustrated in <FIG>, such anchoring features include one or more holes <NUM> formed in metallic sheath <NUM> and optionally one or more holes <NUM> formed in body <NUM>. Holes <NUM> may be punched, drilled or machined into metallic sheath <NUM>. Holes <NUM> may be drilled or machined into body <NUM>. Alternatively, holes <NUM> in body <NUM> may be formed through the use of mold inserts or by way of the configuration of mold portions 56A, 56B and/or mold portions 60A, 60B shown in <FIG> depending on whether overmolding material <NUM> is used.

Holes <NUM>, <NUM> may be of any suitable shape including circular, oval and rectangular for example. Holes <NUM>, <NUM> may include recesses, elongated channels and/or slots for example. Hole(s) <NUM> may extend partially or fully through metallic sheath <NUM>. Hole(s) <NUM> may extend partially or fully through body <NUM>. In addition to holes <NUM>, <NUM>, anchoring features may include one or more protrusions extending from metallic sheath <NUM> or from body <NUM> for engagement with foot <NUM> and/or head <NUM>.

Hole(s) <NUM> in metallic sheath <NUM> and corresponding hole(s) <NUM> in body <NUM> may be disposed so that after installation of metallic sheath <NUM> onto body <NUM>, hole(s) <NUM> may be at least partially aligned with corresponding hole(s) <NUM> in body <NUM> to permit overmolding material from foot <NUM> or head <NUM> to enter hole(s) <NUM> in body <NUM> by passing through corresponding hole(s) <NUM> in metallic sheath <NUM>. In some embodiments, hole(s) <NUM> in metallic sheath <NUM> may be in complete alignment with respective corresponding hole(s) <NUM> in body <NUM>. In some embodiments, hole(s) <NUM> in metallic sheath <NUM> may be in partial alignment with (i.e., overlap) respective corresponding hole(s) <NUM> in body <NUM>.

<FIG> is a schematic cross-sectional view of body <NUM> of <FIG> taken along line <NUM>-<NUM> of <FIG>, together with metallic sheath <NUM> to be applied to the forward portion of body <NUM>. In some embodiments, body <NUM> may be formed to define joggle <NUM> to accommodate the presence of metallic sheath <NUM> and provide a substantially flush (e.g., even or leveled) transition between an upstream outer surface of metallic sheath <NUM> and a downstream outer surface of body <NUM>. Joggle <NUM> may be an offset formed on an outer surface of body <NUM>. A size of such offset may be determined based on a thickness of metallic sheath <NUM> and a bonding substance disposed between metallic sheath <NUM> and body <NUM>. In some embodiments, the size of the offset provided by joggle <NUM> may be between <NUM> inch (<NUM>) and <NUM> inch (<NUM>). Joggle <NUM> may provide a step transition between a recessed forward surface of body <NUM>, to which metallic sheath <NUM> may be bonded, and the remainder of body <NUM>.

<FIG> is a schematic representation of an exemplary vane <NUM> illustrated together with mold portions 68A, 68B for injection overmolding head <NUM> and mold portions 68C, 68D for injection overmolding foot <NUM> on body <NUM> and on metallic sheath <NUM>. Head <NUM> and foot <NUM> may be overmolded using overmolding material <NUM>. Overmolding material <NUM> may include a thermoplastic or thermosetting resin containing relatively short reinforcement fibers as described above. The fibers in overmolding material <NUM> may be shorter than the fibers in preform <NUM> (shown in <FIG>). Alternatively, overmolding material <NUM> may include a thermoplastic or thermosetting resin that is devoid of reinforcement fibers. The thermoplastic or thermosetting resin selected for overmolding material <NUM> may be substantially identical or chemically compatible with a resin used in body <NUM>.

<FIG> shows head <NUM> and foot <NUM> as being transparent for the purpose of illustrating the components encapsulated into head <NUM> and foot <NUM> by way of overmolding. For example, radially-inner sheath end portion <NUM> and radially-inner body end portion <NUM> may be disposed inside of overmolded foot <NUM> and mechanically retained inside of foot <NUM>. Similarly, radially-outer sheath end portion <NUM> and radially-outer body end portion <NUM> may be disposed inside of overmolded head <NUM> and mechanically retained inside of head <NUM>.

<FIG> is a schematic cross-sectional view of vane <NUM> of <FIG> taken along line <NUM>-<NUM> in <FIG>. Radially-outer sheath end portion <NUM> and radially-outer body end portion <NUM> are shown as being encapsulated by overmolded head <NUM> and mechanically retained inside of head <NUM>. Holes <NUM>, <NUM> are shown as being filled with overmolding material <NUM> used to form head <NUM>. The presence of holes <NUM>, <NUM> may provide stronger retention of sheath end portion <NUM> and radially-outer body end portion <NUM> into head <NUM> by providing further mechanical engagement (e.g., anchoring, interlocking)
between head <NUM> and sheath end portion <NUM>, and also between head <NUM> and radially-outer body end portion <NUM>.

<FIG> is a schematic representation of another exemplary type of anchoring feature that may be used instead of, or in addition to holes <NUM>. Such anchoring feature may include one or more tabs <NUM> projecting outwardly from body end portion <NUM> and for engaging with overmolding material <NUM> of head <NUM> for example. Tab <NUM> may be made by having composite sheet(s) <NUM> extend outwardly from layup <NUM> and molded into tab <NUM> during the forming of body <NUM> or preform <NUM> shown in <FIG>. The formation of one or more tabs <NUM> may require a subsequent forming/molding of sheets <NUM> required to form tab <NUM> on preform <NUM> or body <NUM> in addition to the molding step shown in the upper portion of <FIG>.

Claim 1:
A method (<NUM>) of manufacturing a composite guide vane (<NUM>) of a gas turbine engine (<NUM>), the method comprising:
receiving a body (<NUM>; <NUM>) made of a fiber-reinforced composite material, the body (<NUM>; <NUM>) including a body mid portion (<NUM>) for interacting with a fluid, and a body end portion (<NUM>, <NUM>);
applying a metallic sheath (<NUM>) on part of the body (<NUM>; <NUM>), the metallic sheath (<NUM>) including:
a sheath mid portion (<NUM>) applied to the body mid portion (<NUM>) to define a leading edge (<NUM>) of the guide vane (<NUM>); and
a sheath end portion (<NUM>, <NUM>) applied to the body end portion (<NUM>, <NUM>); and
overmolding a head (<NUM>) or a foot (<NUM>) of the guide vane (<NUM>) onto the body end portion (<NUM>, <NUM>) and onto the sheath end portion (<NUM>, <NUM>),
characterised by:
forming a sheath hole (<NUM>) in the sheath end portion (<NUM>, <NUM>); and
receiving overmolding material (<NUM>; <NUM>) into the sheath hole (<NUM>) during the overmolding.