METHOD FOR MANUFACTURING A HOUSING FOR A TURBINE MOTOR AND TOOLS FOR ITS IMPLEMENTATION

Description

Technical field of the invention

[0001] The present invention relates to the field of aircraft turbomachine housings.

[0002] The present invention relates particularly to the manufacture of a casing for a turbomachine, in particular for aircraft, as well as tooling for implementing this process. Technical background

[0003] The prior art includes in particular document EP-A2-2 116 695 which discloses the preamble of claim 1.

[0004] There figure 1 partially represents a fan from an aircraft turbomachine.

[0005] Typically, a turbomachine comprises, from upstream to downstream, i.e. in the direction of gas flow, a blower, one or more compressors, a combustion chamber, one or more turbines, and a nozzle for ejecting the combustion gases exiting the turbine(s).

[0006] The blower 1 includes a blade wheel 2 which is surrounded by a blower housing 3, also called a retention housing because of its function of retaining the blades in case of breakage of the blades, or in case of entry of debris into the blower.

[0007] As can be seen on the figure 2 The fan housing 3 typically comprises a substantially cylindrical body 30 with axis of revolution A extending around the fan blades 2 of the turbomachine. The housing includes an annular mounting flange 31, 32 at each of its axial ends. These flanges 31, 32 are used to fix the housing 3 to annular walls of the turbomachine nacelle.

[0008] There figure 3 is a schematic cross-section illustrating a blower housing 3 according to the prior art.

[0009] The blower housing 3 is connected on one side to an air inlet sleeve 5, and, on the other side, to an intermediate housing ferrule 6. It also carries upstream acoustic panels 7 and downstream acoustic panels 8. The blower housing 3 further includes an abradable support layer 4, positioned on an internal face 34 of the blower housing 3, between the area comprising the upstream acoustic panels 7 and the area comprising the downstream acoustic panels 8.

[0010] In addition to its retention function, the blower housing 3 is also designed to: to ensure mechanical continuity (of forces and moments) between the air inlet 5 and the intermediate casing ferrule 6; to allow the attachment of panels of an aerodynamic duct delimited by the abradable support layer 4, the upstream acoustic panel zone 7 and the downstream acoustic panel zone 8, thus ensuring continuity of the aerodynamic duct; to allow the attachment of equipment and supports known per se; to meet regulatory specifications for fire and leakage; to allow continuity of electrical current for lightning protection, etc. It is known to manufacture the blower casing body from composite material made of woven fibers embedded in a polymer resin, the manufacturing process being of the "RTM" type (English acronym for " Resin Transfer Molding ".

[0011] The use of such a process is particularly advantageous because it allows for the production of parts with a lower overall mass than the same parts when made of metallic material, while exhibiting at least equivalent, if not superior, mechanical resistance.

[0012] However, a deformation compared to the theoretical nominal geometry may be observed upon removal from the mold, that is, during the extraction of the manufactured part (the housing). For example, a defect in the annular flange securing the blower housing may be observed compared to its theoretical circular geometry, manifesting as ovalization of the flange upon its removal from the mold. For example, the figure 4schematically represents a nominal state "En" corresponding to the theoretical circular geometry of the fixing flanges 31, 32 and a deformed state corresponding to a curvature of the fixing flanges 31', 32' at the mold exit of the manufactured blower housing.

[0013] Such defects can be explained in particular by the fact that residual stresses are applied to the part during its manufacture in the mold (e.g. polymerization gradient, winding tension for a part made of composite material), and are released when the part is extracted from the mold, leading to deformation of the extracted part.

[0014] To overcome this drawback, it is known to use at least one mold comprising a molding cavity whose geometry does not correspond to the nominal geometry of the part to be manufactured but to a geometry for which the deformation has been taken into account, so as to finally obtain, when extracting this part from the mold, the nominal geometry of the part.

[0015] Such a process can certainly compensate for the deformation of a part of revolution as it exits the mold. However, during the manufacturing of a blower housing, the observed deformation does not occur solely during its removal from the mold. The manufacturing of the housing subsequently involves various successive operations, such as machining (e.g., contouring, drilling) and bonding (of the abradable layer or acoustic panels, for example).

[0016] Machining operations lead to the release of physical stresses that can promote casing deformation. Bonding operations, on the other hand, are commonly performed in an autoclave. These bonding operations involve heating and pressurizing the casing, followed by a cooling phase. All of these steps also lead to the development of stresses that affect the deformation of the casing flanges. Various casing deformations can therefore occur throughout its manufacturing process and tend to accumulate. The existing state of the art thus appears insufficient to counteract the deformation of the blower casing during its manufacture, given that this deformation does not only occur when the casing is removed from its molding cavity but also during machining and bonding operations.

[0017] The present invention proposes a solution to limit the risk of deformation of the fixing flanges of a blower housing, during a bonding operation of an abradable annular layer.

[0018] During this operation, the housing is placed in an autoclave, and part of a pressure system is mounted inside the housing to apply pressure to the abradable layer, radially from the inside out. This system is relatively bulky and prevents the use of known prior art solutions, such as that described in document FR-A1-3 060 438, which involve incorporating several annular parts (rims, flanges, drums, bladders, etc.) inside the housing, occupying all the available space.

[0019] The present invention offers a simple, effective and economical solution to this problem. Summary of the invention

[0020] The invention thus proposes a method for manufacturing an aircraft turbomachine casing, this casing comprising: an annular body extending around an axis A and made of a composite material comprising woven fibers embedded in a resin, said body comprising an annular fixing flange extending radially outwards at each of its axial ends, and an annular layer of abradable material disposed inside said body, and covering a first internal annular surface of an intermediate section of said body, the process comprising a step b) of bonding the layer to the first surface, during which the casing is heated and compressed by means of a system present at least partly inside the casing.

[0021] The method according to the invention includes, prior to step b) of heating and compression of the housing, a step a) of mounting at least two shaping tools between the flanges, each of the tools being located in a circumferential area outside the annular body of the housing so as to exert support forces in opposite axial directions on these flanges.

[0022] The support forces exerted on the flanges by the tooling are intended to elastically deform at least one of the flanges so that the resulting displacements compensate for the deformations that will occur during step b) of bonding. These so-called corrective deformations then simply reposition the flanges in their original positions and shapes. Advantageously, the tooling is as compact as possible and is arranged on the outer surface of the housing. This allows, on the one hand, for easy handling and movement of each tooling between the circumferential zones of the annular body of the housing, and on the other hand, for not interfering with the bonding operation in which the annular body may be traversed by part of the system necessary for heating and / or pressurizing the housing during step b).

[0023] The method according to the invention may comprise one or more of the following features, considered independently of each other or in combination with each other: In step a) of the process, each tool comprises a first plate applied against a radial face of one of the flanges, a second plate applied against a radial face opposite the other flange, and connecting rods of said plates whose lengths are increased to exert said forces on the flanges; the lengths of the rods are adjusted by means of a manual knurled and / or sliding system; in said step a), said first and second plates have a generally curved shape and said plates are arranged on the annular body so that their concavity is oriented towards the axis A; in said step a), at least one of said first and second plates comprises pins engaged in orifices of the flanges; at said step b), the casing is placed in an autoclave and subjected to a temperature between 25 and 300°C, and to a pressure between 1 and 10 bars, for a period of between 60 and 500 minutes;In said step b), the crankcase is subjected to a temperature between 80 and 200°C, and to a pressure between 2 and 6 bar, for a period of between 180 and 300 minutes; the number of tools is at least three, these tools being regularly distributed around the axis A; the process includes, after step b) of heating and compressing the crankcase, a step c) of dismantling and removing the tools.

[0024] The present invention further relates to tooling configured for implementing the process according to one of the features of the invention, each piece of tooling comprising: a first plate configured to be applied against a radial face of one of the flanges, a second plate configured to be applied against a radial face opposite the other of the flanges, connecting rods of the plates whose lengths are adjustable so as to be able to adjust the inter-plate distance, each plate has a general elongated and curved shape.

[0025] Each shaping tool according to the invention may include one or more of the following features, taken individually or in combination with each other: said tooling is removable; the rods of one of the plates extend substantially radially from an internal wall of said plate to connect in the rods of the other plate in a complementary manner; the rods of one of the plates are connected to each other by a manual system with a knob and / or slide; each plate has a generally curved shape; the circumferential extent of each plate (with respect to axis A) is between 5 and 45°, preferably between 5 and 10°; the first plate and one of the rods are monobloc; and the second plate and one of the rods are monobloc. Brief description of the figures

[0026] The invention will be better understood and other details, features and advantages of the invention will become more apparent upon reading the following description, given by way of non-limiting example and with reference to the accompanying drawings in which: [ Fig. 1 ] there figure 1is a partial schematic half-view in axial cross-section of a fan of an aircraft turbomachine according to the prior art; [ Fig. 2 ] there figure 2 is a schematic perspective view of a blower housing according to the prior art; [ Fig. 3 ] there figure 3 is a schematic cross-sectional view of a crankcase according to the prior art; [ Fig. 4a ] there figure 4a is a very schematic side view showing a nominal state of the housing mounting flanges after a bonding operation; [ Fig. 4b ] there figure 4b is a very schematic side view showing a deformed state of the crankcase mounting flanges observed in the prior art during a bonding operation; [ Fig. 5 ] there figure 5 is a view similar to that of the figure 4 and showing very schematically the elastic deformation applied to the casing to compensate for the effects of the deformations, in accordance with the method according to the invention; [ Fig. 6 ] there figure 6 is a schematic perspective view of tooling for implementing the process according to the invention; [ Fig. 7 ] there figure 7 is a schematic perspective view of a housing according to the invention which is equipped with several tools of the figure 6 ; Fig. 8 ] there figure 8 is a schematic perspective view of the housing equipped with the tooling of the figure 7 , in a step b) of gluing the process according to the invention. Detailed description of the invention

[0027] For the purposes of this application, the terms "inside" and "outside," and "internal" and "external," are used with reference to positioning relative to a rotational axis A of a turbomachine. Thus, a cylinder extending along the engine's axis A has an inner face facing the engine axis and an outer surface opposite its inner surface. "Longitudinal" or "longitudinally" means any direction parallel to axis A, and "transversely" or "transversely" means any direction perpendicular to axis A. Similarly, the terms "upstream" and "downstream" are defined with respect to the direction of airflow within the turbomachine.

[0028] THE figures 1 to 3 represent a fan casing 3 of an aircraft turbomachine, for example a turbojet or turboprop, as described earlier in the technical background of this application.

[0029] In the following description, the invention is applied to a blower housing 3, as illustrated in the figures 2 And 3 of the prior art. The invention is not limited to this type of housing and can be applied to other housings of a turbomachine.

[0030] This housing 3, to which the method according to the invention is applied, comprises an annular body 30 extending about an axis of revolution A. The housing 3 includes an annular mounting flange, respectively upstream 31 and downstream 32, extending radially outwards at each of the axial ends of its annular body 30.

[0031] In the example shown, the housing 3 further includes an annular layer 4 of abradable material disposed inside the body 30, and covering a first internal annular surface 34 of an intermediate section 33 of the body 30.

[0032] The housing body 30 can be made of a composite material comprising woven fibers embedded in a resin.

[0033] The annular layer 4 is configured to be bonded to the first internal surface 34 of the housing body 30. As mentioned above, during this bonding step, the housing 3 is heated and compressed, which can generate deformation of the flange 31, 32. The flanges 31, 32 generally tilt towards the body 30, which represents the most massive element of the housing 3. For example, the deformation of the upstream flange 31 is manifested by a downstream tilt of the outer periphery of the flange 31, while the outer periphery of the downstream flange 32 tilts upstream ( figure 4 ).

[0034] To avoid this deformation, the invention proposes a specific tool 10 which is positioned outside the housing 3 and which allows the housing 3 to be shaped during the bonding operation, during which the housing 3 is subjected to heat treatment under pressure. Indeed, the tool 10 compensates for these deformations by exerting support forces (double arrow at the figure 5 ) which are oriented in opposite axial directions. These forces generate an elastic deformation that at least partially corrects the distortion of flange 31, 32. The figure 6 illustrates an embodiment of this tooling 10 which includes two coaxial plates 11, 12 and connecting rods 13 of the plates 11, 12 whose lengths can be modified so as to be able to adjust the inter-plate distance.

[0035] The plates 11, 12 have a generally elongated and substantially curved shape. The plates 11, 12 are intended to be arranged on the body 30 so that their concavity is oriented towards axis A. In particular, these plates 11, 12 are configured to be applied against a radial face of the flanges 31, 32. The plates 11, 12 preferably have identical or similar circumferential extents. The circumferential extent of the plate 11, 12 with respect to axis A may be between 5 and 45°, preferably between 10 and 20°.

[0036] Each plate 11, 12 is connected to at least two connecting rods 13, 14. On the figure 6The rods 13, 14 are three in number, evenly distributed along the longitudinal or circumferential extent of the plate. The rods 13 and the first plate 11 are preferably one-piece, and the rods 14 and the second plate are preferably one-piece. The rods 13 can be mounted telescopically within the rods 14. Each rod 13, 14 extends substantially along a plane P. The plane P is substantially parallel to the axis A. Thus, the rods 13 of the first plate 11 slide telescopically within the rods 14 of the second plate 12, each along a sliding axis. This sliding axis passes substantially along the plane P. For example, the rods of at least one of the plates are tubular such that the rods of the other plate engage in the tubular openings of these tubular rods. On the figure 6, the rods 13 are inserted at least partially into the rods 14 of the second plate 12. According to an embodiment not shown, the ends of the rods can be threaded so as to make screw connections with the rods of the other plate.

[0037] Furthermore, the tooling 10 includes a system 15 allowing adjustment of the lengths of the rods 13, 14 between the plates 11, 12. The system 15 can include the rods of one of the plates, in particular the rods 14 of the second plate 12 on the figure 6 and a part 151 connecting the rods together. Part 151 includes a locking and / or sliding knurled knob 150. Thus, this system 15 can be operated manually or by means of a sliding mechanism. In the first case, the rod lengths are adjusted by manually moving the rods 13 closer to or further from the rods 14 of the second plate 12, and then the knurled knob 150 is used to lock the rods adjusted to the desired lengths ( figure 6 In the second case (not shown in the figures), the rod lengths are adjusted by sliding the rods, which are connected to each other by the sliding joint, and locking them at the desired lengths. The adjustment system 15 can be attached to or integrated onto the rods of one of the plates.

[0038] Advantageously, at least one of the plates 11, 12 includes pins 16. The pins 16 can be attached to the plate 11, 12 or formed as a single piece with the plate 11, 12 during machining. These pins 16 are configured to engage in holes 37 in the flanges 31, 32 so as to immobilize the tooling 10 circumferentially on the housing body 30. According to an embodiment not shown in the figures, the pins 16 can be formed by the ends of the rods 13, 14 that pass through the plates 11, 12 and can be inserted into the holes 37 in the flanges 31, 32. These pre-existing holes 37 are advantageously those intended to receive the screws for attaching the impeller 2 to another stator element of the turbomachine. The present invention uses some of these orifices 37 to temporarily attach the tooling 10 to the flanges of the housing 3.

[0039] The tooling 10 of the invention can be made from a metallic alloy, such as steel.

[0040] The steps of the manufacturing process according to the invention are described with reference to figures 7 to 8 .

[0041] To carry out the steps of the manufacturing process of the invention, the present invention uses a housing 3, shaping tools 10 according to the invention, an autoclave 9 and a pressurization system 19.

[0042] In practice, during the bonding operation, the housing 3 is positioned in the autoclave 9 so that its axis A is oriented vertically. The system 19 is mounted inside the housing 3; this system 19 is schematically represented in Figure 9 and occupies part of the internal space of the housing 3. The tooling 10 is designed to take this constraint into account.

[0043] Thus, a first step a) of the method of the invention consists of mounting the tools 10 on the external circumferential surface of the body 30 of the housing 3, between the flanges 31, 32. For this purpose, at least two tools 10 are regularly distributed in circumferential zones Z on the outside of the body 30 (visible on the figure 7 ) so as to homogenize the support forces around the flanges. In the example shown, the number of tools is three.

[0044] The first plate 11 of each tool 10 is applied against a radial face of the flange 31, and the second plate 12 is applied against a radial face opposite the other flange 32. To achieve this, each tool 10 is manipulated by an operator to increase the length of the rods 13, 14 in order to exert the necessary bearing forces on the flanges 31, 32, as described above. The lengths of the rods 13, 14 can be adjusted using the manual handwheel 150 and / or sliding system 15.

[0045] To ensure precise positioning of the tools 10 on the housing 3, it is also possible to align the pre-existing orifices 37 of the flanges 31, 32 with the pins 16 of the tools 10.

[0046] Finally, pins 16 of the plates 11, 12 are engaged in the orifices 37 of the flanges 31, 32, so as to lock, at least temporarily, the tooling assembly onto the housing.

[0047] In a particular embodiment of the invention, the set of tools 10 fitted on the housing 3 has a total weight between 8 and 15 kg.

[0048] A second step b) of the process of the invention consists of bonding the abradable layer 4 to the internal surface 34 of the intermediate section 33 of the housing 3. During this step b), the housing 3 is placed in the autoclave 9 and part of the system 19 is installed inside the housing ( figure 8The housing 3 in step b) can be subjected to a pressure of between 1 and 10 bar, and preferably between 2 and 6 bar. This pressurization can be achieved by applying a vacuum to the housing, for example, between two annular elements located respectively inside the abradable layer and outside the casing. The housing 3 can be subjected to a temperature of between 25 and 300°C, and preferably between 80 and 200°C. This operation can be carried out in a cycle lasting between 60 and 500 minutes, and preferably between 180 and 300 minutes.

[0049] At the end of this step b), the temperature and pressure to which the housing 3 is subjected are lowered. After the housing 3 has completely cooled, the abradable layer 4 is bonded and fixed to the internal surface 34, and the tooling 10 can be disassembled and removed.

[0050] The invention offers advantages on several levels. From a technical standpoint, there is no longer a need to perform integration studies based on the deformation state of the housing flanges to ensure they correspond to their final nominal operating state in a turbomachine. From an industrial standpoint, there is no longer a need for custom machining of the flange faces or rework in cases of excessive deformation. The manufacturing and assembly of the housing are simplified, as is its three-dimensional inspection. The invention thus improves the mechanical and aerodynamic performance of the housing, as well as its manufacturing process, and reduces overall cycle time.

Claims

1. A method for manufacturing a casing (3) of an aircraft turbine engine, said casing comprising: - an annular body (30) extending around an axis A and made of a composite material comprising fibres woven and embedded in a resin, said body (30) comprising an annular fastening flange (31, 32) extending radially outwards at each axial ends thereof, and - an annular layer (4) of abradable material arranged inside said body (30), and covering a first internal annular surface (36) of an intermediate section (33) of said body (30), the method comprising a step b) of bonding the layer (4) to the first surface (36), during which the casing (3) is heated and compressed by a system (18) present at least partly inside the casing (3), characterised in that the method comprises, prior to the step b) of heating and compressing the casing (3), a step a) of mounting at least two shaping tools (10) between the flanges (31, 32), each of the tools (10) being located in a circumferential area (Z) outside the body (30) so as to exert bearing forces in opposite axial directions on these flanges (31, 32).

2. The method according to claim 1, characterised in that in the step a) of the method, each tool (10) comprises a first plate (11) applied against a radial face of one of the flanges (31), a second plate (12) applied against a radial face facing the other of the flanges (32), and rods (13, 14) for connecting said plates, the lengths of which are increased to exert said forces on the flanges.

3. The method according to claim 2, characterised in that the lengths of the rods (13, 14) are adjusted by a manual system (15) with knob adjuster (150) and / or slide.

4. The method according to claim 2 or 3, characterised in that in said step a) said first (11) and second (12) plates are of generally curved shape and said plates are mounted on the annular body (3) so that their concavity is oriented towards the axis (A).

5. The method according to one of claims 1 to 4, characterised in that in said step a) at least one of said first and second plates (11, 12) comprises pins (16) engaged in orifices (37) of the flanges (31, 32).

6. The method according to one of claims 1 to 5, characterised in that in said step b), the casing (3) is placed into an autoclave (9) and subjected to a temperature of between 25 and 300°C, and to a pressure of between 1 and 10 bars, for a time of between 60 and 500 minutes.

7. The method according to one of claims 1 to 5, characterised in that in said step b), the casing (3) is placed into an autoclave (9) and subjected to a temperature of between 80 and 200°C, and to a pressure of between 2 and 6 bars, for a time of between 180 and 300 minutes.

8. The method according to one of claims 1 to 7, characterised in that the number of tools (10) is at least equal to three, these tools (10) being regularly distributed around the axis (A).

9. The method according to one of claims 1 to 8, characterised in that it comprises, after the step b) of heating and compressing the casing (3), a step c) of dismantling and removing the tools (10).

10. Tools (10) configured for the implementation of the method according to any of claims 1 to 9, each of the tools (10) comprising: - a first plate (11) configured to be applied against a radial face of one of the flanges (31), - a second plate (12) configured to be applied against a radial face facing the other of the flanges (32), and - rods (13, 14) for connecting the plates (11, 12), the lengths of which are adjustable so that the inter-plates distance can be adjusted, characterised in that each plate (11, 12) has an elongated and curved shape.

11. The tools (26) of claim 10, characterised in that the rods (13, 14) of one of the plates (11, 12) are slidably mounted into the other rods (13, 14) of the other plate (11, 12).

12. The tools (26) according to claim 10 or 11, characterised in that the rods (13, 14) of one of the plates (11, 12) are connected with each other by a manual system (15) with knob adjuster (150) and / or slide.

13. The tools (26) according to any of claims 10 to 12, characterised in that the circumferential extent of each plate (11, 12) is between 5 and 45°, preferably between 10° and 20°.

14. The tools (26) of any of claims 10 to 13, characterised in that the first plate (11) and one of the rods (13) are integral and / or the second plate (12) and one of the rods (14) are integral.