Composite blade for an aircraft engine and method for manufacturing and repairing the composite blade

Abstract

This disclosure discloses a method for manufacturing a composite material blade (10) for a turbine, particularly an aircraft turbine engine, the blade comprising an airfoil (12) having a pressure side (14) and a suction side (16) extending from a leading edge (12a) to a trailing edge (12b) of the airfoil, the blade further comprising a metal shroud (22) extending along the leading edge of the airfoil, the method comprising the steps of: a) arranging a preform made of three-dimensionally woven fibers in a mold, the shroud being positioned on an edge of the preform for forming the leading edge of the airfoil; b) injecting a polymerizable resin into the mold to impregnate the preform to form the airfoil after curing, characterized in that, during step a), at least one double-sided adhesive film is inserted between the shroud and the edge of the preform.

Description

Technical Field

[0001] The present invention relates to a composite material blade for an aircraft turbine and a method for manufacturing and repairing such a blade. Background Technology

[0002] The prior art specifically includes documents FR-A1-2 956 057, FR-A1-3 029 134, FR-A1-3 051386, US-A1-2011 / 194941 and US-A1-2007 / 092379.

[0003] The use of composite materials is advantageous in the aerospace industry, especially because these materials offer beneficial mechanical properties for relatively low mass.

[0004] One method known to those skilled in the art for manufacturing composite material components for the aerospace industry is the RTM molding method, abbreviated as RTM for Resin Transfer Molding.

[0005] This is a method for producing composite material parts based on resin-impregnated fibers. This method, for example, is used to manufacture fan blades and includes several sequential steps.

[0006] First, the fibers are woven together to obtain a three-dimensional preform blank, which is then cut to obtain a preform that roughly has the desired blade shape. The preform is then placed in an injection mold, which is closed. Resin is then injected into the mold while maintaining pressure on the resin in a liquid state, and the part is polymerized by heating.

[0007] The resin used is a highly fluid resin that penetrates the fibers of the preform well, even when injected under reduced pressure. During polymerization, under the influence of heat, the injected resin sequentially changes from a liquid state to a gel state, and finally to a solid state.

[0008] To manufacture blades, for example, for turbine fans, preforms are made by weaving and then impregnated with resin to form the blade. The blade includes a pressure side and a suction side extending from the leading edge to the trailing edge.

[0009] Composite blades are relatively fragile and particularly sensitive to impact, and it is known to protect composite blades by fitting and attaching metal sheaths to the leading edge of the blade.

[0010] The sheath can be attached to the impeller in two ways. The first method involves adhesively bonding the sheath to the impeller after resin polymerization. The adhesive is then in the form of a paste.

[0011] Another approach involves attaching the sheath by co-molding it with a fiber preform. The preform is arranged in a mold, and the sheath is positioned on the edge of the preform that forms the leading edge of the impeller. Injected resin impregnates the preform and makes contact with the sheath to ensure that the sheath is secured to the impeller after polymerization and curing.

[0012] This invention relates to an improvement on the second technology, wherein the sheath and the preform are co-molded.

[0013] Document US-A1-2007 / 0092379 proposes distributing a paste-like adhesive between the sheath and the preform before injecting the resin into the preform to form an adhesive layer or film between these components. However, this operation is delicate and has several drawbacks: it is difficult to ensure that the adhesive is well distributed across the entire surface to be bonded, and it is impossible to guarantee a constant thickness of the adhesive on that surface. In short, this solution is not optimal and cannot be industrialized because manufacturing is difficult to achieve a good level of repeatability.

[0014] This invention provides a simple, effective, and economical solution to ensure proper positioning and optimal mechanical strength of the sheath on the blade. Summary of the Invention

[0015] This invention proposes a method for manufacturing composite blades for turbines, particularly turbines for aircraft, the blade comprising a rotor blade having a pressure side and a suction side extending from a leading edge to a trailing edge, the blade further comprising a metal sheath extending along the leading edge of the rotor blade, the method comprising the following steps:

[0016] a) A preform made of three-dimensional woven fibers is arranged in a mold, and a sheath is positioned on the edge of the preform that forms the leading edge of the impeller.

[0017] b) Injecting polymerizable resin into a mold to impregnate the preform, so that it forms a blade after curing.

[0018] The feature is that, during step a), at least one double-sided adhesive film is inserted between the edge of the sheath and the preform.

[0019] Therefore, this invention proposes to ensure the sheath is attached to the blade by co-molding and by a double-sided adhesive film, i.e., by strips or tapes of adhesive material. The adhesive film is inserted between the edges of the sheath and the preform, designed to improve and maintain the position of the sheath on the edge of the preform, and also designed to improve the sheath's fixation and tear resistance relative to the blade. Thus, it can be understood that during the injection of resin into the manufacturing mold of the blade, the resin will impregnate the preform and will also come into contact with the film or even the sheath, thereby ensuring optimal attachment of the sheath to the blade.

[0020] The method according to the invention may include one or more of the following features, which may be used individually or in combination:

[0021] -During step a), the adhesive film is cut according to the shape of the edge and / or sheath;

[0022] - Apply adhesive film to the edge of the preform before positioning the sheath on it;

[0023] - The sheath is bifacial and defines a groove with a V-shaped cross-section, wherein at least one adhesive film is glued to the sheath within the groove;

[0024] - The first adhesive film is glued to the first longitudinal wall of the sheath in the groove, and the second adhesive film is glued to the second longitudinal wall of the sheath in the groove;

[0025] - The edge is compressed before the sheath is positioned on the edge of the precast component;

[0026] - The edge of the preform is compressed until it reaches a thickness of 75% to 95% of the maximum lateral width or dimension of the groove at the end of step b);

[0027] - The preform is wetted before its edges are compressed;

[0028] - At least one interface fabric is inserted between the preform and the adhesive film, and extends along the said edge of the preform; this fabric is particularly advantageous in the repair of blades, as described below;

[0029] - A single interface fabric is folded and inserted into the groove;

[0030] - The adhesive film or even the interfacial fabric is heated to promote adhesion;

[0031] - The adhesive film protrudes from the sheath and extends onto the surface of the preform not covered by the sheath.

[0032] The present invention also relates to a composite material blade for a turbine, particularly a turbine for an aircraft, the blade comprising a blade having a pressure side and a suction side extending from the leading edge of the blade to the trailing edge, the blade further comprising a metal sheath extending along the leading edge of the blade, the blade being manufactured by the method described above, and comprising at least one adhesive film between the sheath and the leading edge of the blade, or even comprising at least one interface fabric inserted between the blade and the adhesive film.

[0033] Finally, this invention relates to a method for repairing a blade, which is a blade as described above, and which is equipped with the interface fabric described above, wherein the blade sheath is damaged and needs to be replaced. The method includes the following steps:

[0034] - Remove the sheath and adhesive film, where the interface fabric is intended to remain on the leading edge of the impeller, and

[0035] - Glue the new sheath onto the interface fabric. Attached Figure Description

[0036] Other features and advantages of the invention will become apparent from the following detailed description, and with reference to the accompanying drawings for understanding the description, in which:

[0037] [ Figure 1 ] Figure 1 This is a schematic perspective view of a composite material aircraft turbine blade.

[0038] [ Figure 2 ] Figure 2 This illustrates the use of the present invention for manufacturing such as Figure 1 The flowchart illustrates the steps of the method for producing the blade.

[0039] [ Figure 3 ] Figure 3 This is a schematic perspective view of two adhesive films used within the scope of the manufacturing method according to the present invention.

[0040] [ Figure 4 ] Figure 4 This is a schematic perspective view of the sheath. Figure 3 The two membranes were glued to the sheath.

[0041] [ Figure 5 ] Figure 5 This is a schematic perspective view of the interface fabric manipulated by an operator during the manufacturing method according to the invention.

[0042] [ Figure 6 ] Figure 6 This is a schematic perspective view of the sheath. Figure 5 The interface fabric is positioned on the sheath.

[0043] [ Figure 7 ] Figure 7 It is a schematic perspective view of a prefabricated component with one edge subjected to compression.

[0044] [ Figure 8 ] Figure 8 yes Figure 7 A schematic perspective view of the prefabricated components. Figure 6 The sheath is positioned on one edge of the precast component.

[0045] [ Figure 9 ] Figure 9 This is a schematic perspective view of the mold, showing the preforms and sheaths intended to be arranged within the mold, and the resin intended to be injected into the mold.

[0046] [ Figure 10 ] Figure 10 This is a schematic perspective view of the preform and illustrates an alternative embodiment of the invention, in which an adhesive film is glued to one edge of the preform. Detailed Implementation

[0047] First, refer to Figure 1 , Figure 1 A composite blade 10 for a turbine is shown, which is, for example, a fan blade.

[0048] The blade 10 includes a wheel blade 12 which is connected to a root 16 via a support 14. The root has, for example, a dovetail shape and is shaped to engage in a pouch of a complementary shape to the rotor disk so as to hold the blade on the disk.

[0049] The blade 12 includes a leading edge 12a and a trailing edge 12b through which gas flows. The blade 12 has a curved or twisted aerodynamic profile and includes a pressure side 18 and a suction side 20 extending between the leading edge 12a and the trailing edge 12b.

[0050] The blade 12 is made of a fiber preform obtained by three-dimensionally weaving fibers (e.g., carbon).

[0051] The leading edge 12a of the blade is reinforced and protected by a metal sheath 22 attached to the leading edge 12a. The sheath 22 is made, for example, of a nickel- and cobalt-based alloy.

[0052] In this invention, such attachment is performed on the one hand by co-molding the preform with the sheath 22, and on the other hand by adhesively bonding the sheath 22 with at least one adhesive film 24.

[0053] Figure 2 It shows the use of manufacturing such as Figure 1 A flowchart of the steps in the method for the composite material blade 10 shown.

[0054] The method may include multiple steps, some of which are optional.

[0055] The first step a) of the method comprises several sub-steps or operations. During the first operation a1) described above, a fiber preform 26 is formed by weaving fibers, which is particularly... Figure 8As can be seen, the obtained preform 26 is brute and can withstand operations such as cutting. The ends of the fibers in the preform 26 tend to protrude from the outer surface of the preform, which causes the preform to thicken beyond the required final size of the blade.

[0056] During the further operation a2) of this method, such as Figure 3 As shown, one or more adhesive films 24 are prepared. The adhesive film 24 is intended to be inserted between the sheath 22 and the preform 26 before the resin is injected into the manufacturing mold of the blade.

[0057] The adhesive film 24 is a double-sided film, meaning it is glued to both sides. The film is coated or impregnated with adhesive on both sides, for example, by 3M using a numbered... or The adhesive sold by Solvay is labeled with a serial number. Adhesive for sale.

[0058] The adhesive film 24 has, for example, a thickness between 0.1 mm and 0.2 mm. The film 24 can be in the form of a strip. Therefore, the adhesive film can have an elongated shape, the size of which depends on the size of the sheath 22.

[0059] like Figure 4 As shown, the sheath 22 is bifacial in shape and defines a groove 22a with a V-shaped cross-section.

[0060] The adhesive film 24 is preferably adhered to the sheath 22 inside the groove 22a. For example... Figure 3 As shown, the simplest and most effective way is to cut the two adhesive films 24 and glue them to the first longitudinal wall 22b and the second longitudinal wall 22c of the sheath inside the groove 22a, respectively.

[0061] Then we obtain as Figure 4 The components shown.

[0062] However, the optional but preferred subsequent operation a3) includes inserting an interface fabric 28 between one or more adhesive films 24 and the preform 26 before injecting resin into the preform 26.

[0063] like Figure 5As shown, preferably, the interface fabric 28 is pre-cut to the correct size. Unlike the membrane 24 described above, individual fabrics 28 can be cut. It should be understood that the fabric 28 will be folded in half and inserted into the groove 22a, covering the adhesive film 24, such that one side of the fabric extends inside the groove 22a on the adhesive film deposited on the first longitudinal wall 22b of the sheath 22, and the other side of the fabric 28 extends inside the groove 22a on the adhesive film 24 deposited on the second longitudinal wall 22c of the sheath.

[0064] Then we obtain as Figure 6 The components shown.

[0065] Figure 7 An advantageous operation of the manufacturing method is shown, which includes compressing the edge 26a of the preform 26, to which the sheath 22 is intended to be attached (operation a4).

[0066] This compression can be accomplished, for example, by a press. Preferably, the edge 26a of the preform 26 is compressed until it reaches a thickness of 75% to 95% of the maximum lateral width or dimension of the groove 22a of the sheath 22 at the end of the process. Due to the aforementioned protrusion, the thickness of the preform can be approximately 120% of the final thickness of the blade before compression.

[0067] Figure 8 The subsequent operation of the method is shown (a5), during which the sheath 22, which is equipped with adhesive film 24 and optional interface fabric 28, is positioned on the optional compression edge 26a of the preform 26.

[0068] Then, Figure 8 The sheath is positioned in mold 30, which is closed, for example, by a reverse mold. Figure 9 Closing the mold 30 must ensure that sufficient pressure is applied to the sheath 22 to prevent resin from covering the sheath during injection. This pressure can cause deformation of the sheath, particularly a reduction in the width of the groove 22a, which will therefore take on a value corresponding to the desired cumulative thickness of the blade, one or more films, and the interface fabric.

[0069] The consecutive operations a1) to a5 (some operations are optional) represent the first step a) of the manufacturing process.

[0070] During the second step b) of the method, resin is injected into mold 30, and the resin is intended to impregnate the preform and contact the interface fabric 28 when present, and otherwise contact the adhesive film and sheath. After resin polymerization and curing, sheath 22 is integrated with the impeller via adhesive film 24 and resin.

[0071] After the resin is polymerized, the blade 10 obtained therefrom has the advantage that the sheath 22 of the blade is perfectly positioned and held on the impeller 12.

[0072] Figure 10 An alternative embodiment of the manufacturing method according to the invention is shown, wherein the adhesive film 24 is glued to the preform 26 instead of to the sleeve 22. Thus, it can be understood that the sleeve 22 is then positioned and mounted on the edge 26a of the preform 26, to which the adhesive film 24 is glued. Resin can then be injected into the preform located in the mold 30 and polymerized.

[0073] Prior to this step, the interface fabric 28 can be positioned on the preform 26. Then, before the sheath 22 is positioned on the edge 26a of the preform 26 and on the adhesive film 24, the adhesive film 24 is glued to the interface fabric 28.

[0074] The present invention also relates to a composite material blade 10 obtained by the above method, and a method for repairing this type of blade. When the sheath 22 is damaged and needs to be replaced, the method includes the following steps:

[0075] - Remove the sheath 22 and adhesive film 24, while the interface fabric 28 is present, which is designed to remain on the leading edge of the impeller, and

[0076] - When the interface fabric is present, the new sheath is specially glued to the interface fabric.

Claims

1. A method for repairing a blade, the blade comprising a vane, a metal sheath, at least one adhesive film, and at least one interface fabric, the vane having a pressure side and a suction side extending from a leading edge to a trailing edge of the vane, the metal sheath extending along the leading edge of the vane. The blade is manufactured by the following steps: a) arranging a preform made of three-dimensionally woven fibers in a mold, the metal sheath being positioned on the leading edge of the preform for forming the blade; b) injecting a polymerizable resin into the mold to impregnate the preform to form the blade after curing; during step a), at least one adhesive film is inserted between the metal sheath and the edge of the preform, and at least one interface fabric is inserted between the preform and the adhesive film. in, The metal sheath of the blade is damaged and needs to be replaced. The method for repairing the blade includes: Remove the metal sheath and the adhesive film, and retain the interface fabric on the leading edge of the impeller; as well as The new metal sheath is glued to the interface fabric.

2. The method according to claim 1, wherein, The adhesive film is cut according to the edge of the preform and / or the shape of the metal sheath.

3. The method according to claim 1, wherein, The adhesive film is glued to the edge before the metal sheath is positioned on the edge of the preform.

4. The method according to claim 1, wherein, The metal sheath is bifacial and defines a groove with a V-shaped cross-section, wherein at least one adhesive film is glued to the metal sheath within the groove.

5. The method according to claim 4, wherein, The at least one adhesive film includes a first adhesive film and a second adhesive film, wherein the first adhesive film is glued to the first longitudinal wall of the metal sheath in the groove, and the second adhesive film is glued to the second longitudinal wall of the metal sheath in the groove.

6. The method according to claim 4, wherein, The edge is compressed before the metal sheath is positioned on the edge of the preform.

7. The method according to claim 6, wherein, The edge of the preform is compressed until it reaches a thickness of 75% to 95% of the maximum lateral width or dimension of the groove.

8. The method according to claim 6, wherein, The preform is wetted before its edges are compressed.

9. The method according to claim 1, wherein, The adhesive film or the interface fabric is heated to promote adhesion.

10. The method according to claim 1, wherein, The adhesive film protrudes from the metal sheath and extends onto the surface of the preform not covered by the metal sheath.

11. The method according to claim 1, wherein, The edge is compressed before the metal sheath is positioned on the edge of the preform.

12. The method according to claim 11, wherein, The preform is wetted before its edges are compressed.

Images