Method for obtaining a blade grid for an aircraft thrust reverser device, blade grid obtained using this method

Abstract

Method for obtaining a blade grid for an aircraft thrust reverser device, blade grid obtained from this method The invention relates to a method for obtaining a blade grid for an aircraft thrust reverser device, said method comprising: a step of manufacturing U-shaped elements (76.1 to 76.4), each of them comprising in one piece a central part (78) corresponding to a blade (64) as well as first and second branches (80, 82) each corresponding to at least a part of a longitudinal wall (62, 62') of the blade grid, an assembly step consisting of connecting the first branches (80) of the different U-shaped elements (76.1 to 76.4) together so as to form a first longitudinal wall (62) and the second branches (82) of the different U-shaped elements (76.1 to 76.4) together so as to form a second longitudinal wall (62').The invention also relates to a blade grid obtained from such a process. Figure 11.

Description

Title of the invention: Method for obtaining a blade grid for an aircraft thrust reverser device, blade grid obtained using this method

[0001] The present application relates to a method for obtaining a blade grid for an aircraft thrust reverser device, to a blade grid obtained from this method and to an aircraft comprising at least one such blade grid.

[0002] According to an embodiment visible in Figures 1 to 3, an aircraft 10 comprises several propulsion units 12 positioned under each of the wings 14 of the aircraft 10 and connected to the latter by masts 16. Each propulsion unit 12 comprises a motorization 18 positioned inside a nacelle 20. The motorization 18 comprises a fan which has an axis of rotation A18.

[0003] For the remainder of the description, a longitudinal direction is parallel to the axis of rotation A18. A longitudinal plane is a plane containing the axis of rotation A18 and a transverse plane is a plane perpendicular to the axis of rotation A18. The concepts front / upstream and rear / downstream refer to the direction of flow of an air flow in the nacelle 20, the latter flowing from the front (upstream) to the rear (downstream).

[0004] The nacelle 20 has an approximately tubular shape and delimits with the motorization 18 an annular duct 22 in which a secondary air flow flows. The nacelle 20 comprises an upstream section 24, called the air inlet, a middle section 26 in which the fan of the motorization 18 is positioned and a downstream section 28 which has a trailing edge 30.

[0005] The nacelle 20 comprises a thrust reverser device 34 positioned at the downstream section 28 and configured to occupy an activated state in which it diverts at least a portion of the secondary air flow circulating in the annular duct 22 towards the outside and upstream of the nacelle 20 as well as an inactivated state in which it does not divert the secondary air flow circulating in the annular duct 22.

[0006] The thrust reversal device 34 comprises at least one movable part 36 which makes it possible to generate at least one lateral opening 38 (visible in [Fig.2]) passing through the nacelle 20.

[0007] The thrust reverser device 34 comprises a deflection system 40 configured to occupy a retracted position, when the thrust reverser device 34 is in the inactivated state, in which the deflection system 40 does not interfere with the secondary airflow, as well as a deployed position, when the thrust reverser device 34 is in the activated state, in which the deflection system 40 interferes with the secondary airflow and directs it towards the lateral opening 38.

[0008] The thrust reverser device 34 also comprises an orientation system 42 configured to orient the air flow deflected by the deflection system 40. According to one embodiment, the orientation system 42 comprises several blade grids 44 called cascades and positioned at each lateral opening 38.

[0009] According to an embodiment visible in Figures 4 and 5, each blade grid 44 comprises longitudinal walls 46 positioned in approximately longitudinal planes as well as blades 48 positioned in approximately transverse planes. The longitudinal walls 46 and the blades 48 delimit cells 50.

[0010] The blades 48 have a profile for deflecting the air flow exiting upstream via each lateral opening 38. For this purpose, each blade 48 is curved and has a depth P, as illustrated in [Fig.5].

[0011] According to one arrangement, the blade grid 44 comprises five longitudinal walls 46 delimiting four rows of blades 48, sixteen blades 48 for each row and sixty-four cells 50.

[0012] Given their geometry and in particular the low depth P of the blades 48, the blade grids 44 have a large number of cells 50 and therefore a relatively high mass, which is penalizing in terms of on-board mass and energy consumption for an aircraft.

[0013] As illustrated in Figures 6 and 7, a blade grid 44 is generally made of composite material by molding, using for each cell 50 a core 52 configured to expand.

[0014] According to one operating mode, a method for obtaining a blade grid 44 comprises a step of stacking fiber plies to obtain first preforms 46', one for each longitudinal wall 46, and second preforms 48', one for each blade 48. As illustrated in [Fig. 6], the first preforms 46' are substantially planar. The second preforms 48' have an H-shaped section provided at each end with first and second wings 48.1', 48.2' intended to be pressed against first preforms 46'.

[0015] The method for obtaining a blade grid 44 comprises, for each row of blades, a step of placing, alternating them, second preforms 48' and cores 52 between two first preforms 46' substantially parallel to each other, the first wings 48.1' of all the second preforms 48' being pressed against the first preform 46' located on the left, the second wings 48.2' of all the second preforms 48' being pressed against the first preform 46' located on the right. When all the first and second preforms 46', 48' are positioned, the method of obtaining comprises a consolidation or polymerization step, to connect the first and second preforms 46', 48' together, during which the whole is compressed and subjected to a rise in temperature.

[0016] The rise in temperature causes an expansion of the cores 52 which compress the second preforms 48'. After the consolidation or polymerization step, the blade grid 44 obtained and the cores 52 are cooled, which causes the cores 52 to shrink. The production method then comprises a demolding step during which the cores 52 are extracted from the blade grid 44.

[0017] Given the relatively small depth P of the blades 48, the cores 52 compress them correctly during the consolidation or polymerization step, which makes it possible to control the structural integrity of the blade grid 44 obtained.

[0018] This production method makes it possible to obtain a good compromise between ensuring pressure build-up by expansion and maintaining a demolding capacity when the blades have a small depth. This method, suitable for blades with a small depth, is not suitable if the blades have a significant depth, the cores not expanding sufficiently to compress the preforms. To be able to demold a blade grid which has blades with a significant depth, it is necessary to provide relatively complex drawer cores which are difficult, or even impossible, to extract.

[0019] More generally, due to their geometry, blade grilles are complex parts to manufacture.

[0020] The present invention aims to remedy all or part of the drawbacks of the prior art.

[0021] To this end, the invention relates to a method for obtaining a blade grid for an aircraft thrust reverser device, said blade grid comprising at least first and second longitudinal walls oriented in a longitudinal direction as well as blades positioned between said first and second longitudinal walls, connected to the latter and oriented in a transverse direction.

[0022] According to the invention, the obtaining method comprises: a. a step of manufacturing U-shaped elements, one for each blade, each U-shaped element comprising a central part corresponding to one of the blades, a first branch corresponding to at least one part of the first longitudinal wall and a second branch corresponding to at least one part of the second longitudinal wall, the central part, the first and second branches forming a single piece, b. a step of assembling the U-shaped preforms consisting of connecting the first branches of the different U-shaped preforms together so as to form the first longitudinal wall and connecting the second branches of the different U-shaped preforms together so as to form the second longitudinal wall.

[0023] The fact of producing a blade grid by assembling U-shaped elements makes it possible to obtain blades with significant depths while maintaining simple tooling due to the geometry without undercutting of the U-shaped elements.

[0024] According to another characteristic, each U-shaped element is a U-shaped preform made of composite material, the manufacturing step comprising, for at least one U-shaped preform, at least one compression phase and at least one baking or polymerization phase during which said U-shaped preform is compressed and at least partially baked or polymerized,

[0025] According to another characteristic, each U-shaped preform is partially cooked or polymerized during the manufacturing step which comprises a partial cooking or polymerization phase, a final cooking or polymerization phase being carried out subsequently and at the latest during the assembly step.

[0026] According to another characteristic, each U-shaped preform is completely cooked or polymerized during the manufacturing step.

[0027] According to another characteristic, at least one U-shaped preform has an inner face without undercut. In addition, the step of manufacturing U-shaped preforms comprises, prior to the compression phase and for at least one U-shaped preform, a draping phase during which fiber plies are positioned on a first mold shaped like the inner face of the U-shaped preform.

[0028] According to another characteristic, during the manufacturing step, the U-shaped preform is compressed between, on the one hand, the first mold and, on the other hand, at least one counter-mold and / or at least one compression bladder.

[0029] According to another characteristic, during the draping phase, the fiber folds are positioned so as to have fibers oriented mainly in the transverse direction at the central part and fibers oriented mainly in the longitudinal direction at the level of each of the first and second branches.

[0030] According to another characteristic, during the draping phase, at least one fold of fibers is positioned so as to extend over the central part as well as at least over one of the first and second branches.

[0031] According to another characteristic, for each U-shaped element, the first and second branches are spaced apart by a spacing distance that is substantially constant over their length. In addition, the spacing distances separating the first and second branches of the different U-shaped elements decrease from one end to the other of the blade grid in order to be able to form the first and second longitudinal walls by stacking respectively the first and second branches of the different U-shaped elements.

[0032] According to another characteristic, the first and second branches of the different U-shaped elements have free ends located at one of the ends of the blade grid.

[0033] According to another characteristic, for at least first and second U-shaped elements, each of the first and second branches comprises a first section which extends from the central part, a second section which extends from the first section to a free end of the first or second branch as well as a groove connecting the first and second sections. In addition, the first sections of the first and second branches of the first and second U-shaped elements are spaced apart by a first distance, the second sections of the first and second branches being spaced apart by a second distance greater than the first distance, the first sections of the first and second branches of the second U-shaped element being positioned between the second sections of the first and second branches of the first U-shaped element and connected to these second sections.

[0034] According to another characteristic, for at least one U-shaped element, the central part comprises a first part forming a body of a blade as well as a second part, substantially perpendicular to the first part, forming a wing of the blade.

[0035] According to another characteristic, the second part extends over the entire central part and at least partially along at least one of the first and second branches.

[0036] The invention also relates to a blade grid obtained from a production method according to one of the preceding characteristics as well as an aircraft comprising at least one such blade grid.

[0037] Other characteristics and advantages will emerge from the description of the invention which follows, a description given by way of example only, with reference to the appended drawings, among which:

[0038] [Fig. 1] is a perspective view of an aircraft and a propulsion assembly illustrating one embodiment,

[0039] [Fig.2] is a side view of a propulsion assembly illustrating an embodiment of the prior art,

[0040] [Fig.3] is a schematic section of a propulsion assembly equipped with a thrust reverser device in the inactivated state illustrating an embodiment of the prior art,

[0041] [Fig.4] is a perspective view of a blade grid illustrating an embodiment of the prior art,

[0042] [Fig.5] is a longitudinal section along the PV plane of the blade grid visible in [Fig.4],

[0043] [Fig.6] is a schematic representation of a step of placing longitudinal walls, blades and cores illustrating an embodiment of the prior art,

[0044] [Fig.7] is a top view of a blade grid during a consolidation or polymerization step illustrating an embodiment of the prior art,

[0045] [Fig-8] is a perspective view of a blade grid illustrating a mode of rea lization of the invention,

[0046] [Fig.9] is a longitudinal section along plane P-IX of the blade grid visible on [Fig.8],

[0047] [Fig. 10] is a perspective view of a blade illustrating one embodiment of the invention,

[0048] [Fig. 11] is a perspective view of a portion of a blade grid being assembled illustrating one embodiment of the invention,

[0049] [Fig. 12] is a cross-section of a blade profile positioned on a mold illustrating an embodiment of the invention

[0050] [Fig. 13] is a longitudinal section of a blade profile positioned between a mold and a counter mold illustrating an embodiment of the invention,

[0051] [Fig. 14] is a top view of end plates illustrating one embodiment of the invention,

[0052] [Fig. 15] is a top view of a portion of a blade grid being assembled illustrating one embodiment of the invention,

[0053] [Fig. 16] is a top view of an assembled blade grid illustrating one embodiment of the invention,

[0054] [Fig. 17] is a top view of a portion of a blade grid being assembled illustrating another embodiment of the invention.

[0055] According to one application, an aircraft comprises at least one thrust reverser device comprising at least one blade grid 60.

[0056] According to an embodiment visible in Figures 8 to 10, a blade grid 60 comprises at least first and second longitudinal walls 62, 62' positioned in approximately longitudinal planes as well as blades 64 positioned between said first and second longitudinal walls 62, 62', connected to the latter and positioned in approximately transverse planes, the longitudinal walls 62 and the blades 64 delimiting cells 66.

[0057] Each longitudinal wall 62 extends between inner and outer edges 62.1, 62.2. Each blade 64 extends between inner and outer edges 64.1, 64.2. According to one arrangement, the inner edges 62.1, 64.1 of the longitudinal walls 62 and the blades 64 are positioned at a first surface forming an inner surface F60 of the blade grid 60, the outer edges 62.2, 64.2 of the longitudinal walls 62 and the blades 64 being positioned at a second surface forming an outer surface F60' of the blade grid 60. According to one configuration, the inner and outer surfaces F60, F60' are curved to adapt to the curvature of a nacelle. Of course, the invention is not limited to this geometry for the outer and inner surfaces F60, F60'.

[0058] The blades 64 have inner and outer edges 64.1, 64.2 which are substantially parallel to each other and oriented in a transverse direction which is substantially perpendicular to the longitudinal direction.

[0059] According to one configuration, each blade 64 has a substantially constant section in the transverse direction. The blades 64 may have identical sections. Alternatively, as illustrated in [Fig.9], the blades 64 have different sections from one blade to another.

[0060] According to an embodiment visible in [Fig. 10], each blade 64 comprises a body 68 which extends between a first edge 68.1 corresponding to the inner edge 64.1 of the blade 64 and a second edge 68.2 as well as a wing 70 situated in the extension of the body 68 which extends between a first edge 70.1 corresponding to the outer edge 64.2 of the blade 64 and a second edge 70.2 secured to the second edge 68.2 of the body 68. In a longitudinal plane, the wing 70 is substantially perpendicular to the body 68. For each blade 64, the body 68 and the wing 70 form a single and same piece.

[0061] According to one configuration, the wing 70 is substantially flat and located at the level of the outer surface F60' of the blade grid 60.

[0062] The blade 64 has a depth P which corresponds to a maximum distance separating a plane PL, passing through the inner and outer edges 64.1, 64.2 of the blade 64, and a generatrix C of the body 68 furthest from the plane PL.

[0063] According to one configuration, the depth P of the blade 64 is relatively large. By relatively large, it is meant that the depth P does not allow the blade grid to be demolded using simple cores according to a prior art method visible in FIGS. 6 and 7.

[0064] According to one arrangement, the blade grid 60 comprises three longitudinal walls 62 defining two rows of blades 72, 72' as well as four blades 64 per row of blades, the longitudinal walls 62 and the blades delimiting eight cells 66.

[0065] Taking into account the depth P of the blades 64, it is possible to reduce their number, which tends to reduce the mass of the blade grid 60.

[0066] Generally, a blade grid 60 comprises several rows of blades 72, 72'. However, a blade grid 60 could comprise only a single row of blades 72.

[0067] Whatever the embodiment, the blade grid 60 comprises longitudinal end walls corresponding to the most spaced longitudinal walls 62. It extends between a front end 60.1 located approximately in a first transverse plane and a rear end 60.2 located approximately in a second transverse plane.

[0068] According to one embodiment, the blade grid 60 comprises at least one end plate 74, located at the front or rear end 60.1, 60.2, connecting the longitudinal end walls and positioned at the outer surface F60' of the blade grid 60. According to a configuration visible in FIGS. 14 and 15, each end plate 74 is a substantially rectangular strip of material which has long sides substantially parallel to the transverse direction. At least one end plate 74 comprises at least one through-hole 74.1 configured to fix the blade grid 60 to a structure of an aircraft.

[0069] According to one arrangement, the blade grid 60 comprises two end plates 74, 74' positioned at the front and rear ends 60.1, 60.2 of the blade grid 60.

[0070] According to an operating mode visible in figures 11 to 17, a method for obtaining a blade grid comprises: a. a step of manufacturing U-shaped preforms 76.1 to 76.4 made of composite material, one for each blade 64, each U-shaped preform comprising a central part 78 corresponding to one of the blades 64, a first branch 80 corresponding to at least a part of a first longitudinal wall 62 as well as a second branch 82 corresponding to at least a part of a second longitudinal wall 62', the central part 78, the first and second branches 80, 82 forming only one and the same piece, b. a step of assembling the U-shaped preforms 76.1 to 76.4 so as to obtain a row of blades by connecting the first branches 80 of the different U-shaped preforms 76.1 to 76.4 together in order to form the first longitudinal wall 62 and by connecting the second branches 82 of the different U-shaped preforms 76.1 to 76.4 together in order to form the second longitudinal wall 62'.

[0071] When the blade grid 60 comprises several rows of blades 72, 72', the method for obtaining a blade grid comprises a step of assembling the different rows of blades 72, 72' so as to obtain the blade grid 60.

[0072] When the blade grid 60 comprises at least one end plate 74, 74', the method for obtaining a blade grid comprises a step of manufacturing each end plate 74, 74' and a step of assembling each end plate 74, 74' consisting of connecting it with at least one U-shaped preform 76.1 to 76.4.

[0073] Each U-shaped preform 76.1 to 76.4 made of composite material comprises fibers embedded in a matrix of thermosetting or thermoplastic resin. Each end plate 74, 74' is made of a composite material comprising fibers embedded in a matrix of thermosetting or thermoplastic resin. According to one configuration, the U-shaped preforms 76.1 to 76.4 and the end plates 74, 74' are made of the same composite material.

[0074] The steps of assembling the U-shaped preforms 76.1 to 76.4, the rows 72, 72' and the end plates 74, 74' may be separate steps. Alternatively, the steps assembly of the U-shaped preforms 76.1 to 76.4, the rows 72, 72' and the end plates 74, 74' are carried out at the same time and constitute a single step.

[0075] When the U-shaped preforms 76.1 to 76.4 and the possible end plates 74, 74' each comprise a thermosetting resin matrix, each assembly step consists of connecting the U-shaped preforms 76.1 to 76.4 and the possible end plates 74, 74' with fixing elements, such as rivets or screws for example, possibly using fishplates. Alternatively, the U-shaped preforms 76.1 to 76.4 and the possible end plates 74, 74' are connected by gluing or by co-firing.

[0076] When the U-shaped preforms 76.1 to 76.4 and the optional end plates 74, 74' each comprise a thermoplastic resin matrix, each assembly step consists of connecting the U-shaped preforms 76.1 to 76.4 and the optional end plates 74, 74' with fastening elements, such as rivets or screws for example, possibly using fishplates. Alternatively, the U-shaped preforms 76.1 to 76.4 and the optional end plates 74, 74' are connected by gluing, co-baking, co-consolidation or welding.

[0077] According to a first operating mode, each U-shaped preform 76.1 to 76.4 is partially baked or polymerized during the manufacturing step which comprises a partial baking or polymerization phase, a final baking or polymerization phase being carried out subsequently and at the latest during the assembly step.

[0078] According to a second operating mode, each U-shaped preform 76.1 to 76.4 is completely baked or polymerized during the manufacturing step which comprises a phase of complete baking or polymerization of the U-shaped preform 76.1 to 76.4.

[0079] According to a first embodiment visible in Figures 15, 16, each of the first and second branches 80, 82 of each U-shaped preform 76.1 to 76.4 is flat or curved. For each U-shaped preform 76.1 to 76.4, the first and second branches 80, 82 are spaced apart by a spacing distance that is substantially constant over their length. According to this first embodiment, the spacing distances separating the first and second branches 80, 82 of the different U-shaped preforms 76.1 to 76.4 decrease from one end to the other of the blade grid 60 in order to be able to form the first and second longitudinal walls 62, 62' by stacking respectively the first and second branches 80, 82 of the different U-shaped preforms 76.1 to 76.4. According to one arrangement, the spacing distances separating the first and second branches 80, 82 of the U-shaped preforms 76.1 to 76.4 decrease from the rear end 60.2 towards the front end 60.1 of the blade grid 60.According to this first embodiment, the spacing distances separating the first and second branches 80, 82 of the different U-shaped preforms 76.1 to 76.4 are determined so that, for the . first longitudinal wall 62, the first branches 80 are stacked against each other and connected to each other and that for the second longitudinal wall 62', the second branches 82 are stacked against each other and connected to each other.

[0080] According to this first embodiment, the first and second branches 80, 82 of the different U-shaped preforms 76.1 to 76.4 have free ends 80.1, 82.1 located at one of the ends of the blade grid 60, in particular the front end 60.1 of the blade grid 60. According to this first embodiment, the blade grid 60 comprises first, second, third and fourth U-shaped preforms 76.1 to 76.4 offset in the longitudinal direction. The first preform 76.1 has a central portion 78 located at the rear end 60.2 of the blade grid 60 as well as first and second branches 80, 82 which extend from the rear end 60.2 to the front end 60.1 of the blade grid 60. The first and second branches 80, 82 of the second, third and fourth U-shaped preforms have free ends 80.1, 82.1 located, like those of the first and second branches 80, 82 of the first U-shaped preform 76.1, at the front end 60.1 of the blade grid 60. In addition, the end plate 74 located at the front end 60.1 has ends connected at least to the first and second branches 80, 82 of the fourth U-shaped preform 76.4 having the central part 78 closest to the front end 60.1 of the blade grid 60. .

[0081] According to a second embodiment visible in Figures 11 and 17, for at least first and second U-shaped preforms 76.1 to 76.4, each of their first and second branches 80, 82 comprises a first section T1 which extends from the central part 78, a second section T2 which extends from the first section T1 to a free end 80.1, 82.1 of the first or second branch 80, 82 as well as a groove 84 connecting the first and second sections T1, T2.

[0082] According to this second embodiment, the first sections T1 of the first and second branches 80, 82 are spaced apart by a first distance DI and the second sections T2 of the first and second branches 80, 82 of the first and second U-shaped preforms 76.1 to 76.4 are spaced apart by a second distance D2 greater than the first distance DI. All the U-shaped preforms 76.1 to 76.4 have the same first distance DI and the same second distance D2.

[0083] According to this second embodiment, the first sections T1 of the first and second branches 80, 82 of the second U-shaped preform are positioned between the second sections T2 of the first and second branches 80, 82 of the first U-shaped preform and connected to these second sections T2.

[0084] Of course, the invention is not limited to these embodiments for connecting the U-shaped preforms 76.1 to 76.4 together.

[0085] According to an embodiment visible in figures 15 to 17, for at least one U-shaped preform 76.1 to 76.4, the central part 78 comprises a first part 78.1 corresponding to the body 68 of the blade 64 and a second part 78.2, corresponding to the wing 70, substantially perpendicular to the first part 78.1 and extending only at the level of the central part 78 of the U-shaped preform.

[0086] According to another embodiment visible in [Fig. 11], for at least one U-shaped preform 76.1 to 76.4, the second part 78.2 extends over the entire central part 78 as well as at least partially along at least one of the first and second branches 80, 82. According to one arrangement, the wing 70 extends at the central part 78 and over each of the first and second branches 80, 82, in particular at the first sections T1 of the first and second branches 80, 82. This embodiment allows better absorption of the forces produced on the wing 70 by an air flow deflected by the blade grid 60, these forces being transmitted to the body 68 and the first and second branches 80, 82.

[0087] At least one U-shaped preform 76.1 to 76.4 has an inner face F76 comprising the inner surface F1 of the body 68 of the central part 78 oriented towards the first and second branches 80, 82, the inner surface F2 of the wing 70 oriented towards the first and second branches 80, 82 as well as the inner surfaces F3, F4 of the first and second branches 80, 82 oriented towards each other. According to a feature of the invention, the inner face F76 of each U-shaped preform 76.1 to 76.4 does not have an undercut shape in an extraction direction DT substantially parallel to the longitudinal direction.

[0088] According to one embodiment, the step of manufacturing the U-shaped preforms 76.1 to 76.4 comprises, for at least one U-shaped preform 76.1 to 76.4 and preferably all of them, at least one phase of compression of said U-shaped preform 76.1 to 76.4 as well as at least one phase of curing or polymerization during which said U-shaped preform 76.1 to 76.4 is compressed and at least partially cured or polymerized.

[0089] According to one variant, the two phases of compression and cooking or polymerization are simultaneous. According to another variant, the cooking or polymerization phase ends before the end of the compression phase. According to this variant, the U-shaped preform 76.1 to 76.4 is compressed until at least partial cooking or polymerization is complete.

[0090] By way of example, during the compression and curing or polymerization phases, each U-shaped preform 76.1 to 76.4 is compressed at a pressure of between 2 and 7 bars and brought to a temperature of the order of 180°C. Of course, the invention is not limited to these pressures and this temperature. The latter vary depending on the materials of the U-shaped preforms 76.1 to 76.4.

[0091] At the end of the manufacturing step, each U-shaped preform 76.1 to 76.4 is sufficient firmly baked or polymerized to maintain stable geometry and dimensions.

[0092] These phases of compression and at least partial cooking or polymerization make it possible to guarantee the structural integrity of the blade grid 60.

[0093] Prior to the compression phase, the step of manufacturing the U-shaped preforms 76.1 to 76.4 comprises, for at least one U-shaped preform 76.1 to 76.4, a draping phase during which fiber plies 88 are positioned on a first mold 86.1 shaped like the inner face F76 of the U-shaped preform 76.1 to 76.4.

[0094] To implement the manufacturing step, a tool 86 comprises, for each U-shaped preform 76.1 to 76.4 to be produced, at least one first mold 86.1 on which the U-shaped preform 76.1 to 76.4 is positioned at least during the compression and cooking or partial polymerization phases.

[0095] The fact of providing for each U-shaped preform 76.1 to 76.4 an inner face F76 without undercut makes it possible to use a simple first mold 86.1 and to be able to demold the U-shaped preform 76.1 to 76.4 without difficulty.

[0096] According to a first operating mode, during the manufacturing step, the U-shaped preform 76.1 to 76.4 positioned on the first mold 86.1 is compressed using at least one compression bladder. In this case, the tooling 86 comprises, in addition to the first mold 86.1, at least one compression bladder.

[0097] According to a second operating mode visible in Figures 12 and 1, during the manufacturing step, the U-shaped preform 76.1 to 76.2 is compressed between the first mold 86.1 and at least one counter-mold 86.2. In this case, the tooling 86 comprises, in addition to the first mold 86.1, at least one counter-mold 86.2.

[0098] According to a third operating mode, during the manufacturing step, the U-shaped preform 76.1 to 76.2 is compressed between, on the one hand, the first mold 86.1 and, on the other hand, at least one counter-mold and at least one compression bladder. In this case, the tooling 86 comprises, in addition to the first mold 86.1, at least one counter-mold 86.2 and at least one compression bladder.

[0099] According to one procedure, the step of manufacturing a U-shaped preform 76.1 to 76.4 comprises a phase of draping fiber plies 88 onto a laying mold having a laying surface F90 shaped like the inner face F76 of the U-shaped preform 76.1 to 76.4. According to one configuration, the laying mold on which the fiber plies 88 are deposited corresponds to the first mold 86.1. Of course, the invention is not limited to this embodiment. The laying mold and the first mold 86.1 could be two separate molds.

[0100] For at least one U-shaped preform, during draping, at least one ply of fibers 88 is positioned so as to extend astride the first and second parts 78.1, 78.2 of the central part 78 to obtain a body 68 and a wing 70 in one piece, this which contributes to a better recovery of the efforts between these two parts of the dawn 64.

[0101] For at least one U-shaped preform, during the draping phase, the fiber plies 88 are positioned so as to have fibers oriented mainly in the transverse direction at the central portion 78 and fibers oriented mainly in the longitudinal direction at each of the first and second branches 80, 82.

[0102] To ensure better absorption of forces between the blade 64 and the side walls 62, 62', the central part 78 is connected to each of the first and second branches 80, 82 by a relatively large radius of curvature so as to ensure better transmission of forces from the central part 78 to the first and second branches 80, 82.

[0103] According to one embodiment, for at least one U-shaped preform 76.1 to 76.2, during the draping phase, at least one ply of fibers 88 is positioned so as to extend over the central portion 78 and at least one of the first and second branches 80, 82. This embodiment makes it possible to improve the transfer of forces from the central portion 78 to the first and second branches 80, 82. Preferably, at least one ply of fibers 88 is positioned so as to extend over the first and second portions 78.1, 78.2 of the central portion 78 and at least one of the first and second branches 80, 82.

[0104] According to an arrangement, as illustrated in [Fig. 12], at least one fiber fold 88 of the first branch 80 has a portion 88.1 positioned at the central portion 78. The portions 88.1 of the fiber folds 88 of the first branch 80 are stacked alternately with the fiber folds 92 of the central portion 78. This arrangement, provided at the junction zone between the central portion 78 and the first branch 80, can be duplicated at the junction zone between the central portion 78 and the second branch 82.

[0105] Of course, the invention is not limited to the embodiments described. Thus, the U-shaped preforms made of composite material could be replaced by metal U-shaped profiles obtained by stamping.

[0106] Whatever the embodiment, a method for obtaining a blade grid 60 comprises: a. a step of manufacturing U-shaped elements 76.1 to 76.4, one for each blade 64, each U-shaped element 76.1 to 76.4 comprising a central part 78 corresponding to one of the blades 64, a first branch 80 corresponding to at least a part of the first longitudinal wall 62 as well as a second branch 82 corresponding to at least a part of the second longitudinal wall 62', the central part 78, the first and second branches 80, 82 forming only one and the same piece,

[0107]

[0108] b. a step of assembling the U-shaped elements 76.1 to 76.4 consisting of connecting the first branches 80 of the different U-shaped preforms 76.1 to 76.4 together so as to form the first longitudinal wall 62 and the second branches 82 of the different U-shaped preforms 76.1 to 76.4 together so as to form the second longitudinal wall 62'. When the blade grid is made of composite material, the U-shaped elements correspond to U-shaped preforms. When the blade grid is made of metal, the U-shaped elements correspond to U-shaped profiles. Creating a blade grid by assembling U-shaped elements makes it possible to obtain blades with significant depths while maintaining simple tooling due to the geometry without undercutting of the U-shaped elements.

Claims

Claims

1. Method for obtaining a blade grid for an aircraft thrust reverser device, said blade grid (60) comprising at least first and second longitudinal walls (62, 62') oriented in a longitudinal direction as well as blades (64) positioned between said first and second longitudinal walls (62, 62'), connected to the latter and oriented in a transverse direction; characterized in that the method of obtaining comprises: a. a step of manufacturing U-shaped elements (76.1 to 76.4), one for each blade (64), each U-shaped element comprising a central part (78) corresponding to one of the blades (64), a first branch (80) corresponding to at least a part of the first longitudinal wall (62) as well as a second branch (82) corresponding to at least a part of the second longitudinal wall (62'), the central part (78), the first and second branches (80, 82) forming only one and the same piece, b.a step of assembling the U-shaped preforms (76.1 to 76.4) consisting of connecting the first branches (80) of the different U-shaped preforms (76.1 to 76.4) together so as to form the first longitudinal wall (62) and the second branches (82) of the different U-shaped preforms (76.1 to 76.4) together so as to form the second longitudinal wall (62').

2. Method for obtaining a blade grid according to the preceding claim, characterized in that each U-shaped element (76.1 to 76.4) is a U-shaped preform (76.1 to 76.4) made of composite material, the manufacturing step comprising, for at least one U-shaped preform (76.1 to 76.4), at least one compression phase as well as at least one baking or polymerization phase during which said U-shaped preform (76.1 to 76.4) is compressed and at least partially baked or polymerized,

3. Method for obtaining a blade grid according to the preceding claim, characterized in that each U-shaped preform (76.1 to 76.4) is partially baked or polymerized during the manufacturing step which comprises a partial baking or polymerization phase, a final baking or polymerization phase being carried out subsequently and at later during the assembly stage.

4. Method for obtaining a blade grid according to claim 2, characterized in that each U-shaped preform (76.1 to 76.4) is completely baked or polymerized during the manufacturing step.

5. Method for obtaining a blade grid according to one of claims 2 to 4, characterized in that at least one U-shaped preform (76.1 to 76.4) has an inner face (F76) without undercut and in that the step of manufacturing U-shaped preforms (76.1 to 76.4) comprises, prior to the compression phase and for at least one U-shaped preform (76.1 to 76.4), a draping phase during which fiber plies (88) are positioned on a first mold (86.1) shaped like the inner face (F76) of the U-shaped preform (76.1 to 76.4).

6. Method for obtaining a blade grid according to the preceding claim, characterized in that during the manufacturing step, the U-shaped preform (76.1 to 76.2) is compressed between, on the one hand, the first mold (86.1) and, on the other hand, at least one counter-mold (86.2) and / or at least one compression bladder.

7. Method for obtaining a blade grid according to one of claims 5 to 6, characterized in that, during the draping phase, the fiber folds (88) are positioned so as to have fibers oriented mainly in the transverse direction at the central part (78) and fibers oriented mainly in the longitudinal direction at each of the first and second branches (80, 82).

8. Method for obtaining a blade grid according to one of claims 5 to 6, characterized in that during the draping phase, at least one fold of fibers (88) is positioned so as to extend over the central part (78) as well as at least over one of the first and second branches (80, 82).

9. Method for obtaining a blade grid according to one of the preceding claims, characterized in that, for each U-shaped element (76.1 to 76.4), the first and second branches (80, 82) are spaced apart by a spacing distance that is substantially constant over their length and in that the spacing distances separating the first and second branches (80, 82) of the different U-shaped elements (76.1 to 76.4) decrease from one end to the other of the blade grid (60) in order to be able to form the first and second longitudinal walls (62, 62') by stacking respectively the first and second branches (80, 82) of the different U-shaped elements (76.1 to 76.4).

10. Method for obtaining a blade grid according to the preceding claim, characterized in that the first and second branches (80, 82) of the different U-shaped elements (76.1 to 76.4) have free ends (80.1, 80.2) located at one of the ends of the blade grid (60).

11. Method for obtaining a blade grid according to one of claims 1 to 8, characterized in that, for at least first and second U-shaped elements (76.1 to 76.4), each of the first and second branches (80, 82) comprises a first section (T1) which extends from the central part (78), a second section (T2) which extends from the first section (T1) to a free end (80.1, 82.1) of the first or second branch (80, 82) as well as a groove (84) connecting the first and second sections (T1, T2); in that the first sections (T1) of the first and second branches (80, 82) of the first and second U-shaped elements (76.1 to 76.4) are spaced apart by a first distance (Dl), the second sections (T2) of the first and second branches (80, 82) being spaced apart by a second distance (D2) greater than the first distance (Dl); and in that the first sections (Tl) of the first and second branches (80, 82) of the second U-shaped element are positioned between the second sections (T2) of the first and second branches (80, 82) of the first U-shaped element and connected to these second sections (T2).

12. Method for obtaining a blade grid according to one of the preceding claims, characterized in that, for at least one U-shaped element (76.1 to 76.4), the central part (78) comprises a first part (78.1) forming a body (68) of a blade (64) as well as a second part (78.2), substantially perpendicular to the first part (78.1), forming a wing (70) of the blade (64).

13. Method for obtaining a bladed grid according to the preceding claim, characterized in that the second part (78.2) extends over the entire central part (78) and at least partially along at least one of the first and second branches (80, 82).

14. Blade grid obtained from a production method according to one of the preceding claims.

15. Aircraft comprising at least one blade grid according to the preceding claim.

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