A method of manufacturing a blade or propeller from an elastomeric medium

Abstract

The invention relates to a method for manufacturing a blade or a propeller, comprising the following steps: preparing a fibrous blank (100) having an aerodynamic outer shape by a three-dimensional weaving process of yarns, said fibrous blank being provided with an internal recess (104a); introducing a portion (41) of an insert (40) into the internal recess (104a) of the fibrous blank, forming a preform; placing the preform inside a mould cavity of an injection mould matching the outer shape of the blade or propeller to be manufactured; injecting resin into the mould cavity containing the preform and transforming the resin into a matrix by heat treatment. The method further comprises the following steps: before introducing the portion (41) of the insert (40) into the internal recess (104a) of the fibrous blank (100), depositing an elastomer layer (60) on at least said portion of said insert and vulcanizing the elastomer.

Description

Technical Field

[0001] This invention relates to the field of blades or propellers for aircraft, such as blades or propellers in turbine engines. Background Technology

[0002] To obtain lightweight blades or propellers, it is known that composite materials can be used to manufacture propellers, that is, by preparing fiber-reinforced structural components that have undergone matrix densification treatment.

[0003] US Patent document US 2005 / 0084377 describes a method for manufacturing turbine engine blades using integral composite materials. The blades are fabricated using a three-dimensional weaving process of fiber preforms, followed by matrix densification treatment of the preforms. This method can produce blades with extremely high mechanical strength, particularly excellent impact resistance, and eliminates the risk of delamination. However, manufacturing large integral blades or propellers using this technology presents significant challenges.

[0004] Methods for manufacturing blades or propellers have been developed in the industry by introducing one or more inserts into dry fiber preforms.

[0005] US Patent document US 2013 / 0017093 discloses a method for manufacturing a propeller. The propeller's fiber structure is three-dimensionally woven to form an aerodynamic shape and has an internal groove. A portion of the spar and multiple foam molded parts are introduced into the internal groove. Before introduction, the spar and molded parts need to be bonded and fixed to maintain their position for easy positioning within the fiber structure.

[0006] The presence of uncured adhesive within the mold can significantly constrain manufacturing processes, particularly during injection molding. Furthermore, the presence of adhesive increases the risk of producing defective products.

[0007] The spar assembly is inserted into the fiber structure via a release membrane to prevent adhesion between the spar assembly and the dry fiber structure, especially in spars pre-coated with an adhesive film. This release membrane must be removed before the preform injection molding operation. During removal, the release membrane may tear, leaving debris in the final part (foreign object damage). Such contamination can affect the material integrity of the final part and, in some cases, render the part unusable.

[0008] In addition, blades or propellers are subjected to strong vibrations, which may lead to vibration instability (flutter type) and / or reduce their fatigue life under forced loads (such as crosswinds, ground effects). Summary of the Invention

[0009] Therefore, there is an urgent need in the field for a manufacturing solution for aircraft blades or propellers that can minimize the risk of material contamination during the manufacturing process and produce blades or propellers with lower vibration levels.

[0010] Therefore, the present invention proposes a method for manufacturing turbine blades or propellers, the method comprising the following steps:

[0011] A fiber preform with an aerodynamic shape structure is prepared by a three-dimensional weaving process of yarn, and the fiber preform has an internal groove.

[0012] A portion of the insert is introduced into the internal groove of the fiber preform to form a preform;

[0013] The preform is placed in the cavity of an injection mold that matches the shape of the blade or propeller to be manufactured.

[0014] Resin is injected into a mold cavity containing a preform, and the resin is converted into a matrix through heat treatment;

[0015] The method is characterized by further comprising the following steps: depositing an elastomer layer at least on the portion of the insert before introducing the portion of the insert into the internal groove of the fiber preform, and subjecting the elastomer to vulcanization.

[0016] An elastomer layer is deposited on the outer surface of the insert portion into which the fiber preform is to be introduced, and fixed by vulcanization, thus providing protection for the preform during its introduction into the insert portion. This method eliminates the risk of material contamination because the elastomer layer is an integral component of the final blade or propeller, and therefore does not need to be removed after the fiber preform is introduced into the insert.

[0017] This elastomer layer also eliminates the need for adhesives to fix the insert to the preform, because the elastomer and the resin of the injected preform will naturally and directly bond together as the resin transforms into the matrix.

[0018] In addition, the blades or propellers obtained in this way have vibration damping function due to the presence of the elastomer layer.

[0019] According to a specific feature of the method of the present invention, the insert comprises a spar made of metal and a foam body, the spar having a first portion and a second portion, the foam body extending beyond the second portion of the spar, and an elastomeric layer being deposited on both and vulcanized before the second portion of the spar and the foam body are introduced into an internal groove of the fiber preform. By using the elastomeric layer to fix the foam body to the second portion of the spar, there is no need to bond the foam body to the second portion of the spar, thus simplifying the manufacturing method.

[0020] According to another specific feature of the method of the present invention, the first portion of the spar constitutes the root of the blade or propeller.

[0021] According to another specific feature of the method of the present invention, the resin injected into the mold cavity is epoxy resin, and the vulcanized elastomer layer contains an unsaturated elastomer; the method further includes the step of pretreating the outer surface of the vulcanized unsaturated elastomer layer before inserting the insert into the internal groove of the fiber preform. This pretreating step includes grafting halogen elements onto the surface of the component via a halogenation reaction. This can improve the bonding strength between the composite material and the elastomer in the aerodynamic shape of the blade or propeller, thereby reducing the risk of adhesive failure at the interface between the elastomer and the composite material.

[0022] According to another specific feature of the method of the present invention, the method further includes: evacuating the mold cavity before injecting resin into the mold cavity. The presence of the elastomer layer facilitates the evacuation operation of the mold cavity because it creates a sealing effect on the foam in the preform.

[0023] The present invention also proposes a turbine engine blade or propeller comprising an aerodynamically shaped structure and an insert; the aerodynamically shaped structure is composed of at least one fiber reinforcement, which is formed by three-dimensional weaving of yarn and densified by a matrix; the insert includes a portion located within a groove formed in the fiber reinforcement; characterized in that a vulcanized elastomer layer is provided between the outer surface of the first portion of the insert and the inner surface of the groove in the fiber reinforcement. When the blade is subjected to bending and / or torsional vibrations, the elastomer layer between the outer surface of the insert portion and the inner surface of the groove in the fiber reinforcement provides a damping function for the blade or propeller, which is achieved, in particular, through the shear deformation of the elastomer layer.

[0024] According to a specific feature of the blade or propeller of the present invention, the insert comprises a metal spar and a foam body, the spar having a first portion and a second portion, the foam body extending beyond the second portion of the spar; the second portion of the spar and the foam body are located within a groove of a fiber reinforcement, and the first portion of the spar extends beyond the fiber reinforcement.

[0025] According to another specific feature of the blade or propeller of the present invention, the first portion of the spar forms the root of the blade or propeller. Attached Figure Description

[0026] Figure 1 This is a perspective view of a turbine engine blade according to an embodiment of the present invention.

[0027] Figure 2 It is used for manufacturing Figure 1 A schematic diagram of the three-dimensional weaving process of the fiber preform for the aerodynamic shape of the propeller.

[0028] Figure 3A It constitutes Figure 1Enlarged partial cross-sectional view of the yarn layer group of the medium fiber preform.

[0029] Figure 3B It constitutes Figure 1 Another enlarged partial sectional view of the yarn layer assembly of the medium fiber preform.

[0030] Figure 4 It is used for preparation Figure 1 A schematic perspective view of the insert of the precast blade.

[0031] Figure 5 yes Figure 4 A schematic perspective view of an insert with an elastomer layer covering the middle.

[0032] Figure 6 yes Figure 1 Exploded view of the preparation process of the middle blade preform.

[0033] Figure 7 Injection molds and Figure 6 An exploded perspective view illustrating the placement of precast components within the mold.

[0034] Figure 8 It refers to the mold-closed state during the resin injection process. Figure 7 A schematic perspective view of the injection mold. Detailed Implementation

[0035] This invention is generally applicable to various blades or propellers used in aero engines, especially large blades or propellers mounted in rotatable or variable-pitch systems; however, its application is not limited to these. Such blades or propellers are typically equipped with a base that is both compact (occupies little space) and effectively resists tensile stress, bending stress, and circumferential compressive stress. The blades described in this invention can be used, in particular, as blades of ducted rotors, such as fan blades, or as blades of non-ducted rotors, such as blades in what is called an open rotor aero engine.

[0036] The following description will illustrate an embodiment of the method of the present invention in conjunction with the manufacturing process of a non-ducted rotary turbine blade, but this embodiment is equally applicable to the manufacturing of other types of aero-turbine engine blades or propellers.

[0037] Figure 1 shows a blade 10 for an aircraft turboprop engine. The blade employs a structure known in the art, including an aerodynamic profile 20 constituting the aerodynamic section of the blade, a root 33 consisting of a thicker section, such as having a spherical cross-section, and extending from a strut 34. The cross-section of the aerodynamic profile 20 is curved, with variable thickness between the leading edge 20a and the trailing edge 20b. The blade 10 includes a sparsity 30 having a first portion 31 extending outside the aerodynamic profile 20 and a second portion 32 disposed inside the aerodynamic profile 20; the first portion 31 includes the root 33 and the strut 34, and the second portion 32 extends inside the aerodynamic profile 20 from a foam body 35. As described in detail below, an elastomer layer 60 is sandwiched between the assembly consisting of the second portion 32 of the sparsity 30 and the foam body 35 and the fiber reinforcement of the aerodynamic profile 20 of the blade 10.

[0038] Figure 2 shows a fiber preform 100 in a highly simplified form, which is used to form a fiber preform for the aerodynamic shape structure of a blade.

[0039] As shown schematically in Figure 2, the fiber preform 100 is made by three-dimensional weaving, which is carried out using a jacquard loom known in the art; the warp bundles 101 or warp strands on the loom are arranged into several layers, each layer containing hundreds of yarns, and the warp yarns of each layer are interwoven and fixed by the weft yarns 102.

[0040] In this embodiment, the three-dimensional weaving is interlocking weaving. Interlocking weaving refers to a weaving structure in which each layer of weft yarn is connected to multiple layers of warp yarn, and all yarns in the same weft yarn column move along the same trajectory in the weaving plane.

[0041] The present invention may also employ other known three-dimensional weaving forms, such as the weaving forms disclosed in patent document WO 2006 / 136755.

[0042] The fiber preform can be woven from ceramic fibers such as carbon fiber or silicon carbide.

[0043] When weaving a fiber preform with varying thickness and width, some warp yarns do not participate in the weaving process. This method defines the required profile of the fiber preform 100 and its continuously varying thickness. Patent document EP 1 526 285 discloses an example of an advanced three-dimensional weaving process, which in particular enables the fiber preform to achieve a thickness gradient between a first edge intended to form a leading edge and a second edge with a smaller thickness intended to form a trailing edge.

[0044] During the weaving process, between two adjacent warp layers inside the fiber preform, and in the non-interlocking region 104 ( Figure 6 A non-interlocking structure 103 (Figure 2) is formed on the fiber preform 100. The non-interlocking region 104 is provided with an internal groove 104a, which allows the insert to be introduced into the fiber preform 100 to form a preform with an aerodynamic shape structure.

[0045] Figures 3A and 3B show the three-dimensional interlocking weaving structure of the fiber preform 100 in a simplified form. Figure 3A is a partially enlarged view of the cross-sections of two adjacent warp yarns in the fiber preform 100 where there is no non-interlocking structure, i.e., the region in the fiber preform located outside the non-interlocking structure 103; while Figure 3B is a partially enlarged view of the cross-sections of two adjacent warp yarns in the fiber preform 100 where there is the non-interlocking structure 103.

[0046] In this embodiment, the fiber preform 100 includes six layers of warp yarns 101 extending along the X direction. In Figure 3A, the six warp yarns are interwoven and fixed by weft yarns T1 to T5; in Figure 3B, the three warp yarns 101 constituting yarn layer group 105 are interwoven and fixed by two weft yarns T1 and T2, and the three warp yarns constituting yarn layer group 106 are also interwoven and fixed by two weft yarns T4 and T5. In other words, weft yarns T1 and T2 do not extend to yarn layer 106, and weft yarns T4 and T5 do not extend to yarn layer 105. This design forms a non-interlocking structure 103, which separates warp yarn layer groups 105 and 106 from each other.

[0047] After the weaving process is completed (Figure 2), the warp and weft yarns are cut at the boundary of the woven body using methods such as high-pressure water jetting, and the dry fiber preform 100 is removed (Figure 6 shows the dry fiber preform after three-dimensional weaving without any shaping treatment). The non-interlocking region 104 formed during the weaving process can form two independently woven parts 110 and 111, and define an internal groove 104a inside the fiber preform 100. The two parts 110 and 111 are used to form the skins 21 and 22 of the aerodynamic structure 20, and the internal groove 104a opens at the lower edge 100c of the fiber preform 100. The leading edge 100a of the fiber preform 100 connects the two parts 110 and 111, and this leading edge is intended to form the leading edge 20a of the aerodynamic shape structure 20 of the blade 10; the trailing edge 100b of the fiber preform 100 is the part where the trailing edge 20b of the aerodynamic shape structure is intended to be formed (Figure 1).

[0048] In the manufacturing process of this blade, the insert 40 used is the spar 30 and foam body 35 shown in Figure 4.

[0049] According to the design of the present invention, as shown in FIG5, an elastomer layer 60 is deposited on the outer surface of the second part 32 of the spar 30 and the outer surface of the foam 35, which is attached to and collinear with the second part 32. Subsequently, the elastomer is vulcanized on the outer periphery of the foam 35 and the second part 32 of the spar, thereby fixing the two together. It is unnecessary to bond the foam 35 to the second part 32 of the spar 30, because the vulcanized elastomer can fix the two components together.

[0050] Preferably, the metal surface of the second part 32 of the spar 30 is chemically treated to improve its adhesion to the elastomer during vulcanization. It is known in the art that such chemical treatment can employ chemical conversion agents, specialized acid solutions, or other chemicals to activate the surface, creating an active surface conducive to adhesion. The metal surface of the second part 32 of the spar 30 can also be treated with halogenation.

[0051] In this embodiment, the spar 30 is made of metal (such as titanium alloy), and the foam 35 is made of Evonik's ROHACELL material. ® Made from HERO series foam materials.

[0052] As shown in Figure 6, a portion 41 of the insert 40 is introduced into the internal groove 104a to form a dry fiber preform 100. The insert corresponds to the second portion 32 of the spar 30 and the foam 35, both of which are covered with a vulcanized elastomer layer 60. The presence of the elastomer layer 60 makes it easier for the portion 41 of the insert to be introduced into the fiber preform, as it fixes the spar 30 and the foam 35. Furthermore, the outer surface of the portion 41 of the insert is free of adhesive film, a design that greatly simplifies the manufacturing process, eliminating the need for protection during the introduction of the insert into the preform; the omission of the adhesive film also simplifies the injection molding process.

[0053] This yields the blade preform 200, which is located along the longitudinal direction D. L The preform 211 includes a portion 211 with an aerodynamic shape, which is composed of a dry fiber preform 100. A portion 41 of the insert 40 is inserted into the inner groove 104 of the dry fiber preform 100 (Fig. 7). At this time, a vulcanized elastomer layer 60 is sandwiched between the portion 41 and the dry fiber preform 100. The aerodynamically shaped preform portion 211 extends laterally along D... T It extends between the leading edge portion 211a and the trailing edge portion 211b.

[0054] As shown in Figure 7, the blade preform 200 is placed in the injection mold 300, which includes a first mold shell 310 and a second mold shell 320. The first mold shell 310 has a first cavity 311 at its center, and the second mold shell 320 has a second cavity 321 at its center. The shapes and sizes of the two mold shells are respectively matched with the partial structures of the blade to be manufactured.

[0055] As shown in Figure 8, after the mold 300 is closed, the first cavity 311 of the first mold shell 310 and the second cavity 321 of the second mold shell 320 together enclose a mold cavity 301 that is consistent with the shape of the blade to be manufactured, and the blade preform 200 is fixed in the mold cavity.

[0056] The subsequent step involves densifying the fibrous portion of the preform (in this embodiment, the shaped fibrous preform), as shown in Figure 8. Densification of the fibrous portion of the preform involves filling its pores with a matrix material. This densification process is carried out using a liquid chromatography-mass spectrometry (LCM) process known in the art, which involves impregnating the preform with a liquid composition containing a matrix material precursor. The precursor is typically a polymer such as a high-performance epoxy resin, which can be diluted with a solvent as needed.

[0057] The conversion of the precursor to the matrix (i.e., the polymerization reaction) is achieved through heat treatment. Typically, after removing the solvent and completing the polymer crosslinking, the injection mold is heated. The preform is always held within a mold cavity that matches the shape of the part to be manufactured. In this embodiment, the injection mold 300 also includes a lower part 340 and an upper part 350, with a first mold shell 310 and a second mold shell 320 disposed between them. Both the lower part 340 and the upper part 350 are equipped with heating elements (not shown in Figure 8).

[0058] According to one aspect of the invention, densification of the fiber preform can be carried out using a resin transfer molding (RTM) method known in the art. In this method, the fiber preform is placed within a mold that matches the outer contour of the part to be manufactured. A thermosetting resin is injected into the cavity of the mold containing the fiber preform. Typically, a pressure gradient is established in the internal space between the resin inlet and the resin outlet to control and optimize the impregnation effect of the resin on the preform.

[0059] As shown in Figure 8, this invention employs a resin transfer molding method. Resin 380 (such as thermosetting resin) is injected into the mold cavity 301 containing the preform 200 through the injection port 313 of the first mold shell 310. Before injecting the resin 380, the mold cavity 301 is evacuated through the port 323 of the second mold shell 320, which is connected to a vacuum pipeline (not shown in Figure 8). This structural design creates a pressure gradient between the resin injection end (lower end) of the preform 200 and the upper end near the port 323. As a result, the resin 360 injected from near the lower end of the preform gradually permeates the entire fibrous portion of the preform as it flows to the discharge port 323, and excess resin is discharged through the discharge port 323. Of course, the first mold shell 310 and the second mold shell 320 of the mold 300 can each be provided with multiple injection ports and multiple discharge ports.

[0060] The presence of the elastomer layer makes vacuuming of the mold cavity easier because it seals the foam in the preform 200.

[0061] The resin used can be an epoxy resin with a temperature rating of 180°C (this temperature rating represents the highest temperature at which the resin can withstand without loss of performance). Resins suitable for resin transfer molding are materials known in the art. Low-viscosity resins are preferred to facilitate injection into the fiber gaps. The temperature rating and / or chemical properties of the resin are determined based on the thermomechanical stresses the component will withstand during operation. After the resin is completely injected into the fiber reinforcement, it undergoes a polymerization reaction through heat treatment according to the requirements of the resin transfer molding method.

[0062] The process of injecting resin into the fiber preform and converting it into a matrix achieves both densification / consolidation of the aerodynamic preform portion 211 of the blade preform composed of the dry fiber preform 100 and adhesion between the elastomer layer and the inner surface of the internal groove 104 of the dry fiber preform 100, wherein the portion 41 in which the insert 40 is inserted is located.

[0063] After the resin injection and polymerization reaction are completed, the blade is demolded. Finally, the blade is trimmed to remove excess resin and chamfered. Since the blade is molded, its dimensions meet the design requirements, so no additional machining process is required. The final composite blade 10 shown in Figure 1 is obtained, whose fiber reinforcement is a fiber preform 100 that has undergone matrix densification treatment.

[0064] An elastomer layer 60 exists between the outer surface of part 41 of insert 40 (second part 32 of spar 30 and foam 35) and the inner surface of fiber reinforcement groove 104, which enables blade 10 to have a damping function; especially when the blade is subjected to bending and / or torsional vibration, this damping function is achieved through the shear deformation of the elastomer layer.

[0065] According to a specific feature of the invention, the resin injected into the preform is an epoxy resin, which polymerizes to form an organic matrix; in this case, the vulcanized elastomer layer preferably contains an unsaturated elastomer, and the outer surface of the unsaturated elastomer is pretreated before being introduced into the inner groove of the fiber preform to improve its adhesion to the inner surface of the preform.

[0066] The pretreatment step for the outer surface of the unsaturated elastomer is carried out using an addition halogenation reaction, which is well known in the art. This halogenation reaction allows halogen atoms to react with the double bonds in the elastomer's molecular structure. The halogenation reaction is an addition reaction, where halogen atoms add to the double bonds of the unsaturated elastomer. Therefore, the pretreatment of the assembled surface involves grafting halogen elements onto the outer surface of the elastomer.

[0067] Due to the electronegativity difference between halogen atoms and carbon atoms, unsaturated elastomers become polar after halogenation. Therefore, saturating the unsaturated bonds of the elastomer with halogens allows the elastomer to form extremely strong polar bonds with the resin injected into the preform during the polymerization stage. Chlorine gas is a particularly suitable halogen for this purpose. ), fluorine ( ), bromine ( ) or iodine ( This method significantly improves the bonding performance between the elastomer and the composite material of the component.

Claims

1. A method for manufacturing a turbine blade or propeller (10), the method comprising the following steps: A fiber preform (100) with an aerodynamic shape structure is prepared by a three-dimensional weaving process of yarn, and the fiber preform is provided with an internal groove (104a). A portion (41) of the insert (40) is introduced into the internal groove (104a) of the fiber preform to form a preform (200). The preform (200) is placed in the cavity (301) of the injection mold (300) that matches the shape of the blade or propeller to be manufactured; Resin (380) is injected into a mold cavity (301) containing a preform (200), and the resin is converted into a matrix by heat treatment; The method is characterized by further comprising the following steps: depositing an elastomer layer (60) at least on said portion of the insert (40) before introducing a portion (41) of the insert (40) into the internal groove (104a) of the fiber preform (100), and subjecting the elastomer to vulcanization.

2. The method according to claim 1, wherein, The insert (40) includes a metal spar (30) and a foam body (35), the spar having a first part (31) and a second part (32), the foam body extending the second part of the spar; before the second part of the spar and the foam body are introduced into the internal groove (104a) of the fiber preform (100), an elastomer layer (60) is deposited on the second part of the spar and the foam body and vulcanized.

3. The method according to claim 2, wherein, The first part (31) of the spar (30) forms the root (33) of the blade or propeller.

4. The method according to any one of claims 1 to 3, wherein, The resin (380) injected into the mold cavity (301) is an epoxy resin, wherein the vulcanized elastomer layer (60) contains an unsaturated elastomer; the method further includes the following steps: before inserting the insert into the inner groove of the fiber preform, pretreating the outer surface of the vulcanized unsaturated elastomer layer, the pretreating including grafting halogen elements onto the assembly surface by a halogenation reaction.

5. The method according to any one of claims 1 to 4, wherein, The method further includes: evacuating the mold cavity before injecting resin (380) into the mold cavity (301).

6. A turbine engine blade or propeller (10) comprising an aerodynamically shaped structure and an insert (40); the aerodynamically shaped structure (110) comprising at least one fiber reinforcement (200) formed by three-dimensional weaving of yarn and densified by matrix treatment; a portion (41) of the insert being located in a groove formed inside the fiber reinforcement; characterized in that, A vulcanized elastomer layer (60) is provided between the outer surface of the first part (41) of the insert (40) and the inner surface of the fiber reinforcement groove.

7. The blade or propeller according to claim 6, wherein, The insert (40) includes a metal spar (30) and a foam body (35), the spar having a first part (31) and a second part (32), the foam body extending the second part (32) of the spar; the first part (31) of the spar and the foam body (35) are located in the groove of the fiber reinforcement, the first part (31) of the spar extending to the outside of the fiber reinforcement.

8. The blade or propeller according to claim 7, wherein, The first part (31) of the spar (30) forms the root (33) of the blade or propeller.

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