METHOD FOR MANUFACTURING A BLADE FOR AN AIRCRAFT TURBOMACHINE

Abstract

A method of manufacturing a blade (10) for an aircraft turbomachine, comprising the steps of: a) producing a blank of a metal shield (22), b) forging the blank of the shield to form a shield (22), this forging being carried out in a shaping press (40) which comprises second elements (42, 44, 46) bearing on the wings (24, 26) and / or the edge (28) of the shield (22), and c) assembling the shield (22) on an edge (12a) of a blade (12), characterized in that the forging in step b) is carried out in a multi-axial manner, that is to say that the second elements (42, 44, 46) are configured to exert compressive forces on the wings (24, 26) and / or the edge (28) of the shield (22) in at least two directions (F1, F2, F3) different. Figure for abstract: Figure 6

Description

Title of the invention: METHOD FOR MANUFACTURING A BLADE FOR AN AIRCRAFT TURBOMACHINE Technical field of the invention

[0001] The present invention relates to a method of manufacturing a blade for an aircraft turbomachine. Technical background

[0002] The use of composite materials is particularly advantageous in the aeronautical industry because these materials are relatively light and have good mechanical properties.

[0003] A composite material conventionally used for aeronautics comprises a fibrous preform embedded in a polymeric resin. The preform can be produced by three-dimensional weaving or can be obtained by draping and superimposing several fabrics.

[0004] The resin can be injected into the preform or the preform can be pre-impregnated with the resin.

[0005] The shaping of the final part is generally carried out by means of a tool comprising a mold. In the case where a resin must be injected into a preform, the preform is placed in the cavity of a mold and the mold is covered with a counter-mold. The tooling comprises a port for injecting resin into the mold cavity as well as a port for creating a vacuum in the mold cavity.

[0006] In the case where the preform is already impregnated with the resin, the preform is placed in the cavity of a mold which can be covered with a flexible tarpaulin or a counter-mold.

[0007] The tooling also includes a port for injecting resin into the mold cavity and a port for vacuuming the mold cavity. The countermold applies pressure to the preform by vacuuming the preform located between the countermold and the flexible sheet or mold. The use of a countermold allows for better control of the thickness of the final part.

[0008] In order to protect the leading edge of the blade from wear by erosion and / or degradation caused by impacts with foreign bodies, this leading edge is covered with a metal protective shield. The shield is assembled and fixed on the leading edge by gluing. For this purpose, the leading edge or the shield is coated with a layer of glue, then the shield is assembled on the leading edge. This gluing operation can take place before or after the injection of the resin into the preform.

[0009] The leading edge of the blade can have a complex shape and imposes a shape complex with the shield. The shield has a generally elongated shape and has a generally V-shaped cross-section. The shield has two longitudinal wings connected to each other at a longitudinal edge of the shield, and defining between them a longitudinal cavity. The leading edge of the blade is intended to be engaged in this cavity and the wings of the shield are intended to extend over the intrados and extrados of the blade respectively.

[0010] The production of the shield is itself complex and involves several stages. A blank of the metal shield is first produced. Then, this blank undergoes isothermal forging in a shaping press to form the shield. This stage is important for shaping the shield to the shapes and dimensions of the leading edge on which the shield is intended to be mounted.

[0011] In the current technique, this isothermal forging is of the uniaxial type, that is to say that the shaping press is configured to apply a compressive force on the shield in a single compression direction. In the case where the shield should be subjected to compressive forces in several directions, these compressive forces are subjected successively. It is then necessary to use the press several times to apply a compressive force in one direction each time.

[0012] This uniaxial isothermal forging can lead to dimensional and geometric defects in the shield. For example, dimensional defects may appear in the shield cavity, and the wings may undergo deformation such as waviness. These problems are amplified by the fact that isothermal forging may require the shield to be pressed several times.

[0013] The present invention provides a solution to at least some of the problems discussed below. Summary of the invention

[0014] The invention relates to a method of manufacturing a blade for an aircraft turbomachine, comprising the steps of:

[0015] a) production of a blank of a metal shield, this blank of shield having a generally elongated shape and having in cross section a general V shape, the blank of shield comprising two longitudinal wings connected together at a longitudinal edge of the shield and defining between them a longitudinal cavity,

[0016] b) forging of the blank of shield to form a shield, this forging being carried out in a shaping press which comprises at least a first element filling said cavity and second elements bearing on the wings and / or the edge of the shield, and

[0017] c) assembly of the shield on an edge of a blade, the edge of the blade being engaged in the cavity of the shield, the blade being previously obtained by weaving fibers and being embedded or intended to be embedded in a polymer matrix,

[0018] characterized in that the forging in step b) is carried out in a multi-axial manner, that is to say that the second elements are configured to exert compressive forces on the wings and / or the edge of the shield in at least two different directions.

[0019] The invention thus proposes, during forging in step b), to apply compressive forces simultaneously in several directions on the shield. This solution makes it possible to reduce or even eliminate the risk of geometric and dimensional defects appearing on the shield and also has several advantages which will be described below.

[0020] The shield may be mounted on any edge of the blade or vane, and for example a leading or trailing edge of the blade or vane.

[0021] The shield may be assembled on the blade or vane after production of the blade or vane or during production of the blade or vane. The shield is for example assembled on a blade preform obtained by weaving fibers, in three dimensions or by stacking fabrics, this blade preform being intended to be impregnated with a polymeric resin, by a process of the RTM (Resin Transfer Molding) type for example. Alternatively, the shield may be assembled on a blade already comprising a preform impregnated with a polymeric resin. The shield may be fixed on the blade or vane by gluing or by the impregnation resin.

[0022] The method according to the invention may comprise one or more of the following characteristics, taken in isolation from one another, or in combination with one another: - the second elements are configured to exert compressive forces on the wings and / or the edge of the shield in at least three different directions; - one of the second elements is configured to exert a compressive force on one of the wings in a first direction, another of the second elements is configured to exert a compressive force on the other of the wings in a second direction, and yet another of the second elements is configured to exert a compressive force on the edge of the shield in a third direction; - the forging in step b) is carried out in a thermal enclosure in which said shaping press is located; - the forging in step b) is carried out at a temperature between 650 and 980°C; - during forging in step b), the second elements are moved towards the shield blank at a speed between 0.1 and 5mm / s; - during forging in step b), the press controls the second elements in force and position; - the forging in step b) is of the isothermal type, the blank of the shield and the first and second elements of the press being maintained at the same temperature; - the forging in step b) is of the quasi-isothermal type, the blank of the shield being maintained at a temperature higher than that of the first and second elements of the press; - at least some of the first and second elements are made of refractory metal alloy; - step a) comprises one or more sub-steps chosen from turning, bending, stuffing, spinning, cutting, machining, fitting and dimensional control of the shield blank; - between steps b) and c), the method comprises one or more sub-steps chosen from stripping, machining, milling, polishing, marking, penetrant testing, adjustment, finishing cutting, and dimensional control of the shield;

[0023] — the first element completely fills the cavity of the shield blank. Brief description of the figures

[0024] Other characteristics and advantages will emerge from the following description of a non-limiting embodiment of the invention with reference to the appended drawings in which:

[0025] [Fig-1] [Fig.l] is a perspective schematic of a blade for a tur- aircraft engine, this blade being equipped with a metal shield,

[0026] [Fig.2] [Fig.2] is a schematic perspective view of a metal shield,

[0027] [Fig.3] [Fig.3] is another schematic perspective view of a shield metal and showed the cavity of this shield,

[0028] [Fig.4] [Fig.4] represents steps of a manufacturing method according to the invention,

[0029] [Fig.5] [Fig.5] is a schematic sectional view of a shaping press for a shield blank for uniaxial type forging,

[0030] [Fig.6] [Fig.6] is a schematic sectional view of a press for shaping a shield blank for multi-axial type forging. Detailed description of the invention

[0031] [Fig.l] illustrates a blade 10 made of composite material for a turbomachine, in particular an aircraft one, this blade 10 being for example a propeller or fan blade.

[0032] The blade 10 comprises a blade 12 connected for example by a stilt 14 to a root 16. The root 16 may have a dovetail shape and is shaped to be engaged in a cell of complementary shape of a rotor disk, in order to retain the blade on this disk.

[0033] The blade 12 comprises a leading edge 12a and a trailing edge 12b for the gases flowing into the turbomachine. The blade 12 has a curved or even twisted aerodynamic profile and comprises a lower surface 18 and an upper surface 20 extending between the leading edges 12a and trailing edges 12b.

[0034] The leading edge 12a of the blade 12 is protected by a metal shield 22 which is shown alone in Figures 2 and 3.

[0035] This shield 22 has a generally elongated shape and has a generally V-shaped cross-section. The shield 22 comprises two longitudinal wings 24, 26 connected to each other at a longitudinal edge 28 of the shield 22 and defining between them a longitudinal cavity 30.

[0036] [Fig. 4] shows steps of a method of manufacturing a blade 10 of the aforementioned type.

[0037] The method essentially comprises three steps, each of which may comprise several sub-steps.

[0038] A first step a) of the method comprises the production of a blank of the shield 22. This blank already has a shape and dimensions close to the final shield and thus comprises a generally elongated shape with a V-shaped cross-section. The blank further comprises the wings 24, 26 connected to each other at the edge 28 and defining between them the cavity 30, as mentioned above.

[0039] The method then comprises a step b) of forging the shield blank to form the shield 22.

[0040] Finally, the method comprises a step c) of assembling the shield 22 on the edge 12a of the blade 12. The edge 12a of the blade 12 is engaged in the cavity 30 of the shield 22, after production of the blade or during production of the blade. This means that the shield 22 can be mounted on the edge 12a of the blade 12, in the form of a blade preform, after production of this preform by three-dimensional weaving of fibers or draping of fiber fabrics, and before injection of resin into this preform by an RTM process for example. This also means that the shield 22 can be mounted on the edge 12a of the blade 12 after production of resin injection into the blade or its fiber preform and solidification of this resin.

[0041] The shield 22 can be secured to the blade 12 by gluing or by the impregnation resin of its preform.

[0042] The production of the blade will not be described in more detail in the following since the invention relates rather to the production of the protective shield 22.

[0043] In step b) of forging, the shield blank 22 is placed in a shaping press 32 such as that illustrated in [Fig.5].

[0044] This press 32 comprises at least a first element 34 which fills the cavity 30 of the shield 22, and second elements 36 which bear on the wings 24, 26 and / or the edge 28 of the shield 22.

[0045] In the current technique, the press 32 makes it possible to carry out uniaxial isothermal forging and is configured to apply a compressive force in a single direction (arrow F1) thanks to the second elements 36.

[0046] [Fig. 6] illustrates a shaping press 40 for forging a shield blank 22 according to an embodiment of the method according to the invention.

[0047] The particularity of this forging is that it is carried out in a multi-axial manner, that is to say that the shaping press 40 comprises second elements 42, 44, 46 which are configured to exert compressive forces on the wings 24, 26 and / or the edge 28 of the shield 22 in at least two different directions (F1, F2). The shaping press 40 further comprises a first element 48 which fills the cavity 30 of the shield 22, preferably entirely.

[0048] Advantageously, the second elements 42, 44, 46 are configured to exert compression forces on the wings 24, 26 and / or the edge 28 of the shield 22 in at least three different directions (F1, F2, F3).

[0049] As in the illustrated example, one of the second elements 42 may be configured to exert a compressive force on one of the wings 24 in a first direction F1, another of the second elements 44 may be configured to exert a compressive force on the other of the wings 26 in a second direction F2, and yet another of the second elements 46 is configured to exert a compressive force on the edge 28 of the shield 22 in a third direction F3.

[0050] In the case where only compressive forces are applied in two distinct directions, one of the following combinations of directions could be adopted: F1 and F2, F1 and F3, F2 and F3.

[0051] The directions F1 and F2 can be contained in the same plane, or even on the same axis, and can be opposite.

[0052] The direction F3 can be perpendicular to at least one of the directions F1, F2.

[0053] The forging in step b) may be of the isothermal type and is then preferably carried out in a thermal enclosure 50 in which said shaping press 40 is located. The shield 22 and the elements 42, 44, 46 of the press 40 are then maintained at the same temperature.

[0054] Alternatively, the forging in step b) may be of the quasi-isothermal type. The shield 22 is then maintained at a temperature higher, and preferably slightly su- upper, at the temperature of elements 42, 44, 46 of press 40.

[0055] The forging in step b) is preferably carried out at a temperature between 650 and 980°C.

[0056] During forging in step b), the second elements 42, 44, 46 are preferably moved towards the shield blank 22 at a speed of between 0.1 and 5 mm / s.

[0057] The press 40 can control the second elements 42, 44, 46 by force only, or by both force and position. It is therefore understood that the second elements 42, 44, 46 are moved and positioned independently of each other.

[0058] At least some of the first and second elements 42, 44, 46, 48 are made of refractory metal alloy, and for example of steel, nickel-based alloy, etc.

[0059] [Fig.4] can be used to illustrate steps and sub-steps of the method according to the invention.

[0060] Step a) of the method may comprise one or more sub-steps chosen from turning, bending, stuffing, spinning, cutting, machining, fitting and dimensional control of the shield blank.

[0061] Between steps b) and c), the method may comprise one or more sub-steps d) chosen from stripping, machining, milling, polishing, marking, penetrant testing, adjustment, finishing cutting, and dimensional control of the shield.

[0062] The invention thus provides several advantages, including: • the method makes it possible to significantly improve the geometry of the cavity 28 of the shield 22; • the method makes it possible to significantly improve the shape of the wings 24, 26 of the shield 22; • the method reduces the need for retouching operations of the shield 22; • the process makes it easier to assemble the shield on the blade; • forging is carried out in a single operation and therefore a single pass through the shaping press, which simplifies industrial implementation; • the process makes it possible to reduce shear forces in the press, and therefore improve its service life; • the process allows the kinematics of the forging to be adapted by controlling the elements of the shaping press; • etc.

Claims

Claims

1. A method of manufacturing a blade (10) for an aircraft turbomachine, comprising the steps of: a) producing a blank metal shield (22), this blank shield (22) having a generally elongated shape and having a generally V-shaped cross-section, the blank shield (22) comprising two longitudinal wings (24, 26) connected together at a longitudinal edge (28) of the shield and defining between them a longitudinal cavity (30), b) forging the blank shield to form a shield (22), this forging being carried out in a shaping press (40) which comprises at least a first element (48) filling said cavity (30) and second elements (42, 44, 46) bearing on the wings (24, 26) and / or the edge (28) of the shield (22), and c) assembling the shield (22) on an edge (12a) of a blade (12), the edge (12a) of the blade (12) being engaged in the cavity (30) of the shield (22),the blade (12) being previously obtained by weaving fibers and being embedded or intended to be embedded in a polymer matrix, characterized in that the forging in step b) is carried out in a multi-axial manner, that is to say that the second elements (42, 44, 46) are configured to exert compressive forces on the wings (24, 26) and / or the edge (28) of the shield (22) in at least two different directions (F1, F2, F3).,

2. The method of claim 1, wherein the second elements (42, 44, 46) are configured to exert compressive forces on the wings (24, 26) and / or the edge (28) of the shield (30) in at least three different directions (F1, F2, F3).

3. The method of claim 2, wherein one of the second elements (42) is configured to exert a compressive force on one of the wings (24) in a first direction (F1), another of the second elements (44) is configured to exert a compressive force on the other of the wings (26) in a second direction (F2), and yet another of the second elements (46) is configured to exert a compressive force on the edge (28) of the shield (22) in a third direction (F3).

4. Method according to one of the preceding claims, in which the forging in step b) is carried out in a thermal enclosure (50) in which is located said shaping press (40).

5. Method according to one of the preceding claims, in which the forging in step b) is carried out at a temperature between 650 and 980°C.

6. Method according to one of the preceding claims, wherein, during forging in step b), the second elements (42, 44, 46) are moved towards the shield blank (22) at a speed of between 0.1 and 5 mm / s.

7. Method according to one of the preceding claims, in which, during forging in step b), the press (40) controls the second elements (42, 44, 46) in force and position.

8. Method according to one of the preceding claims, in which the forging in step b) is of the isothermal type, the blank of the shield (22) and the first and second elements (42, 44, 46, 48) of the press (40) being maintained at the same temperature.

9. Method according to one of claims 1 to 7, in which the forging in step b) is of the quasi-isothermal type, the blank of the shield (22) being maintained at a temperature higher than that of the first and second elements (42, 44, 46, 48) of the press (40).

10. A method according to any preceding claim, wherein at least some of the first and second elements (42, 44, 46, 48) are made of a refractory metal alloy.

11. Method according to one of the preceding claims, in which step a) comprises one or more sub-steps chosen from turning, bending, stuffing, spinning, cutting, machining, fitting and dimensional control of the shield blank (22).

12. Method according to one of the preceding claims, in which, between steps b) and c), the method comprises one or more sub-steps chosen from stripping, machining, milling, polishing, marking, penetrant testing, adjustment, finishing cutting, and dimensional control of the shield (22).

Images