METHOD FOR MANUFACTURING A THRUSH REVERSING GRILLE FOR A NACELLE OF AN AIRCRAFT PROPULSION ASSEMBLY

Abstract

The invention relates to a method for manufacturing a thrust reverser grid (5) made of composite material, the method comprising the steps of: (a) providing tooling extending along a longitudinal axis (X) and having cores (90) movable in translation, (b) placing first layers of fibers (600) on transverse surfaces (96) of the cores to form preforms of transverse profiles, (c) placing second layers of fibers (700) on longitudinal surfaces (97) of the cores to form preforms of longitudinal profiles, (d) performing at least one thermocompression along a transverse direction of said first layers of fibers and / or said second layers of fibers, (e) consolidating the preforms of transverse and longitudinal profiles by impregnating said first and second layers of fibers with a resin,and (f) solidify the preforms of transverse and longitudinal profiles to form the thrust inverter grid (5). Figure for the abbreviation: Figure 6,

Description

Title of the invention: METHOD FOR MANUFACTURING A THRUST REVERSER GRILLE FOR A NACELLE OF AN AIRCRAFT PROPULSION UNIT Field of invention

[0001] The field of the present invention is that of propulsion assemblies, for example for aircraft, comprising a nacelle.

[0002] The present invention relates to a method of manufacturing a thrust reverser grid for an aircraft nacelle, more particularly made of composite material. Technical background

[0003] An aircraft is powered by at least one propulsion unit comprising a turbomachine housed in a nacelle. Each propulsion unit is attached to the aircraft by a mast located under or on a wing or at the fuselage of the aircraft.

[0004] A nacelle generally has a tubular structure comprising an air inlet upstream of the turbomachine, a middle section intended to surround a fan of the turbomachine, a downstream section which can house thrust reverser means (called thrust reversers) and intended to surround the combustion chamber of the turbomachine, and is generally terminated by an ejection nozzle whose outlet is located downstream of the turbomachine.

[0005] The thrust reversers comprise movable thrust reverser elements, generally two movable thrust reverser elements, carried by the nacelle to move between a closed position (direct jet) in which the thrust reverser is inactive, and an open position (reverse jet) in which the thrust reverser is active, that is to say it returns at least a portion of the gas flow generated by the turbojet in the opposite direction to the flow guided by the nacelle.

[0006] In many types of thrust reverser, the movable thrust reverser elements include air directing elements that deflect at least a portion of the gas flow outward and forward. These air directing elements may be grilles such as finned grilles (also called cascades).

[0007] Each grid comprises longitudinal profiles (such as side members) and transverse profiles (such as blades) delimiting air passage cells.

[0008] The grids are advantageously made of composite materials, in order to make them lighter and more resistant than metal grids. Some composite materials are usually composed of a fibrous reinforcement densified by a matrix.

[0009] Such grids are generally manufactured by a manual draping process of many pieces of composite fabric, which is very expensive and does not allow for truly scalable aerodynamic profiles.

[0010] In a variant, the thrust reverser grids can be produced by a thermocompression molding process. This makes it possible to densify a fiber reinforcement pre-impregnated with a resin by applying pressure and carrying out a heat treatment at high temperature. In the case of a fiber reinforcement of the laminated preform type (stack of plies in a determined sequence) made of continuous fibers, thermocompression is limited by the shape of the parts and it proves necessary to drape each cell of the grid individually, which can be time-consuming and expensive. In the case of a sheet of long discontinuous fibers (DLF) in combination with thermocompression, it is possible to obtain significant manufacturing cost savings and the manufacture of more complex shapes.Such a method makes it possible to produce thrust reverser grids by using fiber sheets comprising pieces of fibers (such as DLF fibers) to fully drape the cells or to drape in a U shape connection zones between the transverse and longitudinal profiles, then thermocompression to press the pieces of fibers onto the surfaces of the so-called elementary preforms forming the transverse and longitudinal profiles of the grids. However, this technique can prove to be long (and consequently expensive) and complex to carry out (in particular the U-shaped draping and the full draping of the cells).

[0011] In these different contexts, it is interesting to propose a solution making it possible to simplify and facilitate the production of a thrust reverser grid in composite material, while having the best aerodynamic and mechanical performances. Summary of the invention

[0012] The present invention provides a simple, effective and economical solution to at least some of the aforementioned problems.

[0013] To this end, the invention proposes a method for manufacturing a thrust reverser grid for a nacelle of an aircraft propulsion unit, the grid being made of composite material and comprising a plurality of transverse profiles connected to longitudinal profiles, said transverse profiles being perpendicular to said longitudinal profiles, the grid also comprising cells each delimited by two transverse profiles and at least partly by two longitudinal profiles, the method comprising the steps of: (a) providing a tool extending along a longitudinal axis and comprising cores movable in translation relative to the longitudinal axis and configured to form the cells of the grid, (b) placing first fiber sheets on transverse surfaces of the cores to form preforms of transverse profiles, (c) placing second fiber plies on longitudinal surfaces of the cores to form preforms of longitudinal profiles, (d) carrying out at least one thermocompression in a transverse direction of said first layers of fibers and / or said second layers of fibers to press and secure said first and second layers of fibers against each other, (e) consolidating all of the preforms of the transverse and longitudinal profiles by impregnating said first and second fiber layers with a resin, and (f) solidifying all of the preforms of the transverse and longitudinal profiles to form the thrust reverser grid.

[0014] This solution makes it possible to achieve the aforementioned objective. For this, the method according to the invention uses a specific tool comprising cores (intended to form the cells of the grid) movable in translation to allow the direct draping, on the one hand, of the first layers of fibers (intended to form the transverse profiles) on transverse surfaces of the cores of the tool, and on the other hand, of the second layers of fibers (intended to form the longitudinal profiles) on longitudinal surfaces of the cores of the tool.

[0015] By "fiber sheet" is meant either a fiber reinforcement pre-impregnated with a resin, or a fiber reinforcement to which a resin will be added in a second step in order to form the composite material constituting the thrust reverser grid. As described below, the fiber sheet may comprise continuous fibers and / or discontinuous fibers (DLF).

[0016] Unlike the prior art (describing entire or complex U-shaped layups of the air passage cells), the longitudinal and transverse surfaces of the cores of the tooling are configured to have a simple geometry (such as flat and / or at least partly curved surfaces). This facilitates the layup and thermocompression of the first and second fiber sheets. Thus, the first and second fiber sheets are placed in the tooling so as to cover and envelop all the longitudinal and transverse surfaces of the cores of the tooling. These cores are said to be mobile because they are able to slide in translation (relative to the longitudinal axis X and / or a transverse axis Y substantially perpendicular to the longitudinal axis X) relative to each other, in order to compress the first and second fiber sheets against the cores when a force is applied towards these cores.

[0017] Furthermore, the draping and thermocompression of the first and second fiber sheets according to the invention make it possible to obtain good entanglement between the first and second fiber sheets at their junction zones (or in other words connection zones) between the transverse and longitudinal profiles. In fact, thermocompression allows the fiber layers to flow into longitudinal and transverse cavities (particularly formed between adjacent cores) of the tooling, so as to firmly bond the first and second fiber layers together. This makes it possible to form a high-performance mechanical strength for the junction zones of the thrust reverser grid made of composite material.

[0018] The invention therefore has the advantage of being based on a simple design, offering very high reliability, and with little penalty in terms of cost and size in an aircraft propulsion system.

[0019] The manufacturing method of the invention also comprises one or more of the following features and / or steps, taken alone or in combination:

[0020] - step (b) is carried out by draping said first sheets of fibers on flat or curved transverse surfaces of the cores;

[0021] - each of the first layers of fibers has a length greater than or equal to less than that of a corresponding longitudinal surface of the nuclei;

[0022] -the first fiber sheets and / or the second fiber sheets comprise discontinuous fibers and / or continuous fibers;

[0023] - the discontinuous fibers have lengths between 5 and 50 mm;

[0024] - intrados surfaces and / or extrados surfaces of said first plies of fibers and / or longitudinal surfaces of said second fiber sheets comprise pieces of fibers having for example a polygonal shape of width between 5 and 20mm and length between 5 and 35mm;

[0025] - at least 80% of the first fiber sheets comprise discontinuous fibers randomly distributed in a plane;

[0026] - at least 80% of the second fiber sheets comprise continuous fibers;

[0027] - each of the first layers of fibers comprises at its transverse ends materials with discontinuous fibers or pleated or torn fibers;

[0028] - the transverse profile preforms are connected to the longitudinal profile preforms tudinal in step (d) by connection zones formed from at least one of said first and second fiber sheets, these connection zones having a curved or L-shaped folded shape;

[0029] - said connection zones have a radius of curvature of between 0.5 and 5mm;

[0030] - said first and second fiber sheets are pre-impregnated with the resin, and / or the resin is injected in step (e).

[0031] The invention also relates to a thrust reverser grid for an aircraft nacelle, this thrust reverser grid being produced by the method having any one of the preceding characteristics and comprising a plurality of transverse profiles connected to longitudinal profiles and cells each delimited by two transverse profiles and at least partly by two longitudinal profiles.

[0032] The transverse profiles may be blades and the longitudinal profiles may be spars of the grid.

[0033] The invention further relates to an aircraft nacelle comprising at least one thrust reverser grid as described above. Brief description of the figures

[0034] The invention will be better understood, and other aims, details, characteristics and advantages thereof will appear more clearly on reading the detailed explanatory description which follows, of embodiments of the invention given as purely illustrative and non-limiting examples, with reference to the appended schematic drawings in which:

[0035] [Fig.l] is a schematic perspective view of a nacelle of an aircraft propulsion unit comprising a thrust reverser having a plurality of grids according to the invention;

[0036] [Fig.2] is a schematic perspective view of a thrust reverser grid of [Fig.l];

[0037] [Fig.3] represents a flowchart of a manufacturing process of the thrust reverser grid of [Fig.2];

[0038] [Fig.4] is a partial schematic perspective view of a tool used in the manufacturing method of the invention;

[0039] [Fig.5] is a partial schematic perspective view of the placements of the first and second fiber sheets according to the manufacturing method of [Fig.3];

[0040] [Fig.6] represents several partial schematic views and axial sectional views of certain steps of the manufacturing process of [Fig.3] including the thermocompression step according to a first embodiment;

[0041] [Fig.7] represents several partial schematic views and axial sectional views of certain steps of the manufacturing process of [Fig.3] including the thermocompression step according to a second embodiment;

[0042] [Fig.8] is a partial schematic view in axial section of the connection zones of the thrust reverser grid in production.

[0043] Elements having the same functions in different implementations have the same references in the figures. Detailed description of the invention

[0044] By convention, in the description below, the terms “longitudinal” and “axial” qualify the orientation of structural elements extending in the direction of an axis Ion- longitudinal. The terms "radial" or "vertical" describe an orientation of structural elements extending in a direction perpendicular to the longitudinal axis. The terms "inner" and "outer," and "internal" and "external" are used to refer to a positioning relative to the longitudinal axis. Thus, a structural element extending along the longitudinal axis has an inner face facing the longitudinal axis and an outer surface, opposite its inner surface.

[0045] Similarly, by convention in the present application, the terms “upstream” and “downstream” are defined in relation to the direction of circulation of the gases in the turbomachine of an aircraft propulsion unit.

[0046] The invention applies in a non-limiting manner to an aircraft propulsion unit 10. [Fig. 1] illustrates this aircraft propulsion unit 10 comprising a turbomachine 3 which is surrounded by a nacelle 1.

[0047] The aircraft propulsion assembly 10 may be suspended from a fixed structure of an aircraft, for example under a wing or on a fuselage, by means of a pylon 2 (or mast) attached to the turbomachine 3 or to the nacelle 1 in the case of the example in [Fig.l].

[0048] The turbomachine 3 may be a double-flow turbomachine which comprises, from upstream to downstream (depending on the direction of gas flow), a fan, a low-pressure compressor, a high-pressure compressor, an annular combustion chamber, a high-pressure turbine and a low-pressure turbine, which define a flow path for a primary air flow (called a hot air flow).

[0049] The nacelle 1 extends along a first longitudinal axis A.

[0050] The nacelle 1 may comprise, from upstream to downstream, an upstream air intake section 4, a middle section (not visible in [Fig.l]), a downstream section housing a thrust reverser I and possibly a terminal nozzle section. The sections of the nacelle are connected together so as to extend around the turbomachine 3 and define around it an annular flow vein for a secondary air flow (or cold air flow).

[0051] The thrust reverser I comprises a plurality of grilles 5 making it possible to form a member for deflecting an air flow (in particular that of the cold air flow). These grilles 5 can be connected in a movably manner with an external cover 50 of the thrust reverser. The grilles 5 can be pivotally mounted between a closed position (direct jet) in which these grilles 5 are substantially parallel to the first longitudinal axis A, and an open position (reverse jet) in which these grilles 5 are inclined relative to the first longitudinal axis A. [Fig.l] illustrates the thrust reverser in the open position so as to uncover the grilles 5.

[0052] With reference to [Fig.2], each grid 5 of the thrust reverser extends along a second longitudinal axis C and a first transverse axis B (relative to the second axis longitudinal axis C). The second longitudinal axis C may be substantially parallel to the first longitudinal axis A of the nacelle 1.

[0053] The grid 5 comprises a plurality of transverse profiles 6 (also called blades) connected to longitudinal profiles 7a, 7b (also called spars). In particular, the transverse profiles 6 each extend in a first direction (parallel to the first transverse axis B) and the longitudinal profiles 7a, 7b each extend in a second direction (parallel to the second longitudinal axis C), in which the first direction and the second direction are substantially perpendicular.

[0054] In the example of grid 5 of [Fig.2], the transverse profiles 6 are perpendicular to the longitudinal profiles 7a, 7b.

[0055] As illustrated in [Fig.2], the transverse profiles 6 are connected to the longitudinal profiles 7a, 7b by junction zones 67. The transverse profiles 6, the longitudinal profiles 7a, 7b and the junction zones 67 can thus be formed from a single piece (made from the same material).

[0056] The grid 5 also comprises so-called air passage cells 8. These cells 8 are each delimited by two transverse profiles 6 and at least partly by two longitudinal profiles 7a, 7b.

[0057] The grid 5 may be a straight or deflected flow grid. In the case of a so-called “straight” counter-thrust grid 5, the grid 5 comprises aerodynamic transverse profiles 6, also called vanes, and longitudinal profiles 7a, 7b that are substantially planar without aerodynamic lift: the aerodynamic thrust of the transverse profiles 6 being oriented in a radial plane longitudinal to the grid 5. In the case of a so-called “deflected” counter-thrust grid 5, either the transverse profiles 6 develop a deflected counter-thrust in the radial direction relative to the grid 5 and the longitudinal profiles 7a, 7b remain substantially planar, or the transverse profiles 6 develop a longitudinal counter-thrust and the longitudinal profiles 7a, 7b are formed to develop a lateral counter-thrust, the sum of the two providing a deflected counter-thrust.

[0058] As an example, [Fig.2] represents a so-called “straight” counter-thrust grid.

[0059] The transverse profiles 6 can be arranged in a ladder between, and / or on either side on the other hand, longitudinal profiles 7a, 7b. The transverse profiles 6 can also be arranged on only one side of the one or more longitudinal profiles 7a, 7b.

[0060] Furthermore, it is possible to use grids 5 having only two longitudinal profiles 7a, 7b, and it is also possible to have grids 5 having up to seven or even fifteen longitudinal profiles 7a, 7b.

[0061] More precisely and according to this particular embodiment, the transverse profiles 6 are arranged parallel to each other in the same row 60 between two longitudinal profiles 7a, 7b, of grid 5.

[0062] The transverse profiles 6 comprise transverse faces which respectively constitute an intrados face 6b and an extrados face 6b of the transverse profile 6. The “intrados” face designates the inner face of the transverse profile 6, namely the face oriented towards the cold flow vein during its use, while the “extrados” face designates the outer face of the transverse profile opposite the intrados face and oriented mainly towards the outside of the nacelle during its use.

[0063] The longitudinal profiles 7a, 7b extend along the second longitudinal axis C which is substantially perpendicular to the first transverse axis B.

[0064] The number of longitudinal profiles 7a, 7b, provided there is at least one, is not limiting. In the example of [Fig.2], the grid 5 comprises two first longitudinal profiles 7a on either side of a second central longitudinal profile 7b, separating two rows 60 of transverse profiles 6. The transverse profiles of a row 60 are parallel to each other and aligned (with respect to the first transverse axis B). A row 60 of transverse profiles 6 of [Fig.2] is thus connected by one of the first longitudinal profiles 7a and by the second central longitudinal profile 7b.

[0065] The longitudinal profiles 7a, 7b may be connected to fixing flanges 52 intended for fixing the grid 5 on the nacelle 1. These fixing flanges 52 may extend in the first direction (parallel to the first transverse axis B). The transverse profiles 6, the longitudinal profiles 7a, 7b, the junction zones 67 and the fixing flanges 52 may also be formed from a single piece (i.e., made from a single piece).

[0066] The fixing flanges 52 can be arranged on either side of the rows 60 of transverse profiles. Two transverse profiles 6 can be integrated into a fixing flange 52. The first two longitudinal profiles 7a and the two fixing flanges 52 can form a peripheral frame 54 surrounding the transverse profiles 6.

[0067] The grid 5 may optionally comprise fasteners or fixing means (not shown) along the first two longitudinal profiles 7a.

[0068] The transverse profiles 6 channel the air flow and deflect it in one direction along the second longitudinal axis C, producing thrust on the transverse profiles 6. The longitudinal profiles 7a, 7b channel the air flow and possibly deflect it in another direction along the first transverse axis B. All of the aerodynamic forces applied to the transverse profiles 6 and the longitudinal profiles 7a, 7b can be collected in the peripheral frame 54 and transmitted to the structure of the inverter via attachments on the fixing flanges 52.

[0069] The grid 5 as described above is made of composite material comprising, for example, a fibrous reinforcement embedded in a matrix.

[0070] The composite grid 5 can be made from sheets of fibers comprising discontinuous fibers (DLF) and / or continuous fibers.

[0071] In particular, each transverse profile 6 is obtained from a transverse profile preform and each longitudinal profile 7a, 7b is obtained from a longitudinal profile preform.

[0072] The transverse profile preform can be made from one or more first fiber sheets 600, and the longitudinal profile preform can be made from one or more second fiber sheets 700.

[0073] The first and / or second fiber sheets 600, 700 may comprise discontinuous fibers and / or continuous fibers.

[0074] The first fiber sheets 600 of each transverse profile preform may each have an intrados surface 600a (intended to form the intrados face 6a of the transverse profile to be produced) and an extrados surface 600b (intended to form the extrados face 6b).

[0075] Each of the intrados 600a and extrados 600b surfaces can extend transversely along a plane parallel to the first transverse axis B.

[0076] The intrados 600a and / or extrados 600b surfaces of the first fiber sheets 600 may comprise continuous fibers and / or DLF fibers randomly distributed in a plane (which is substantially parallel to the first transverse axis B of the grid 5).

[0077] The first fiber sheets 600 preferably comprise at least 80% of discontinuous fibers.

[0078] Even more preferably, the first fiber sheets 600 comprise at least 80% of discontinuous fibers, and at most 20% of the intrados 600a and / or extrados 600b surfaces at the junction zones 67 comprise continuous fibers.

[0079] Advantageously, at least 80% of the intrados surfaces 600a or the extrados surfaces 600b of the first fiber sheets 600 comprise continuous fibers and at most 20% of these intrados surfaces 600a or the extrados surfaces 600b comprise DLF fibers.

[0080] The second fiber sheets 700 of each longitudinal profile preform may each have at least one longitudinal surface.

[0081] The longitudinal surfaces of the second fiber sheets 700 may comprise continuous fibers and / or DLF fibers randomly distributed in another plane (which is substantially parallel to the second longitudinal axis C).

[0082] The DLF fibers of the first 600 and / or second 700 fiber sheets may have lengths of between 5 and 50 mm. In particular, the DLF fibers of the first 600 and / or second 700 fiber sheets (for example the intrados 600a and / or extrados 600b surfaces of the first fiber sheets 600, and / or the longitudinal surfaces of the second fiber sheets 700) may be in the form of a piece. Each piece of DLF fibers may have a polygonal shape with a width of, for example, between 5 and 20mm and length for example between 5 and 35mm.

[0083] The pieces of fibers can form chips of discontinuous fibers (DLF), unidirectional and / or woven, arranged in directions parallel to the intrados 600a and / or extrados 600b surfaces of the first fiber sheets 600 and / or to the longitudinal surfaces of the second fiber sheets 700.

[0084] In a preferred embodiment, the DLF fibers used in the first and / or second fiber sheets 600, 700 are in accordance with patent FR-B1-3068277.

[0085] In another embodiment, the DLF fibers used in the first and second fiber sheets 600, 700 may also come from ribbons of unidirectional carbon fibers, for example 6.3 mm wide (+ / -0.5) and with a thickness of between 0.12 and 0.2 mm.

[0086] As described above, the first fiber sheets 600 and / or the second fiber sheets 700 may be pre-impregnated with resin or in the raw state. By "raw state" is meant fiber sheets 600, 700 comprising fibers not previously impregnated with resin.

[0087] By way of example, the first fiber sheets 600 and / or the second fiber sheets 700 comprise carbon, glass, aramid and / or polyamide fibers.

[0088] The junction zones 67 between the transverse profiles 6 and the longitudinal profiles 7a, 7b may be formed from the transverse profile preform and / or the longitudinal profile preform (described below with reference to FIGS. 6 and 7).

[0089] These preforms of transverse profiles and longitudinal profiles can be densified by a resin to obtain the final shape of the grid 5 in composite material.

[0090] We will now describe a manufacturing method 100 of such a grid 5 made of composite material with reference to FIGS. 3 to 8.

[0091] Generally, the method 100 comprises the following steps: (a) provide a tool 9 extending along a longitudinal axis X (hereinafter called “third” longitudinal axis X) and comprising cores 90 configured to form the cells 8 of the grid 5, (b) placing first fiber sheets 600 on transverse surfaces 96 of the cores 90 to form transverse profile preforms (intended to form the transverse profiles 6), (c) placing second fiber sheets 700 on longitudinal surfaces 97 of the cores 90 to form longitudinal profile preforms (intended to form the longitudinal profiles 7a, 7b), (d) carrying out at least one thermocompression along a transverse direction of said first fiber sheets 600 and / or said second fiber sheets 700 to press and secure said first 600 and second 700 fiber sheets. against each other, (e) consolidating (or otherwise densifying) all of the preforms of transverse and longitudinal profiles by impregnating the first 600 and second 700 fiber layers with a resin, and (f) solidifying all of the transverse and longitudinal profile preforms to form the thrust reverser grid 5.

[0092] This method is represented in [Fig.3], in which the optional steps are represented in dotted lines.

[0093] The tool 9 of step (a) is illustrated by way of example in [Fig.4]. The tool 9 thus forms a mold making it possible to manufacture the grid 5 according to the method of the invention. Such tooling and these advantages are described in particular in the document WO-A1-2021 / 123628 of the Applicant.

[0094] The tool 9 therefore extends along the third longitudinal axis X, a transverse axis Y (hereinafter called the “second” transverse axis Y) and a vertical axis Z. The second transverse axis Y is substantially perpendicular to the third longitudinal axis X and to the vertical axis Z. The third longitudinal axis X is substantially parallel to the second longitudinal axis C of the grid 5 to be produced, and the second transverse axis Y is substantially parallel to the first transverse axis B.

[0095] The tooling 9 comprises the cores 90 configured to delimit cells 8 of the grid 5 to be manufactured. The cores 90 are movable, for example relative to the third longitudinal axis X and / or to the second transverse axis Y. The tooling 9 may comprise a first 92a and a second 92b sole. The first sole 92a makes it possible to receive the cores 90 and the fiber sheets 600, 700, and the second sole 92b makes it possible to close the tooling 9.

[0096] The cores 90 can be removable and arranged on the first sole 92a according to the configuration of the part to be produced.

[0097] Each core 90 may comprise transverse surfaces 96 and longitudinal surfaces 97. These transverse surfaces 96 may extend along the second transverse axis Y and the longitudinal surfaces 97 may extend along the third longitudinal axis X. In the example of the tool 9 of [Fig.4], the transverse surfaces 96 may be perpendicular to the longitudinal surfaces 97.

[0098] The transverse surfaces 96 may have a planar or curved shape. Each of the planar transverse surfaces 96 may be defined in a plane parallel to the plane defined by the X and Z axes. In the example of [Fig.4] or [Fig.5], the transverse surfaces 96 are curved.

[0099] Each of the transverse surfaces 96 may have a first length L96 measured relative to the third longitudinal axis X.

[0100] The longitudinal surfaces 97 may have a planar or curved shape. Each longitudinal surfaces 97 can be defined in a plane parallel to the plane defined by the Y and Z axes. In the example of [Fig.5], the longitudinal surfaces 97 are curved.

[0101] The cores 90 can be movable in translation between the first 92a and second 92b soles. In particular, the cores 90 can translate along the third longitudinal axis X and / or the second transverse axis Y.

[0102] Attachment means (not shown in [Fig.4]) may connect the first 92a and second 92b soles to lock the tooling 9.

[0103] The tool 9 may also comprise peripheral bars 94 arranged on the periphery of the cores 90. These bars 94 are configured to delimit the grid 5 to be manufactured, at least one peripheral bar 94 being movable in translation between the first 92a and second 92b soles (relative to the third longitudinal axis X and / or the second transverse axis Y).

[0104] The cores 90 may be arranged in columns, i.e. aligned one after the other along the second transverse axis Y ([Fig.4]). In this configuration, the tooling 9 may therefore comprise transverse cavities 95 (along the second transverse axis Y) which each extend at the transverse surfaces 96, for example between two adjacent cores 90 and / or between a peripheral bar 94 and a core 90. The tooling 9 may also comprise longitudinal cavities 98 (along the third longitudinal axis X) which each extend at one of the longitudinal surfaces 97 of the cores 90, for example between two adjacent cores 90 and / or between a peripheral bar 94 and a core 90.These transverse 95 and longitudinal 98 cavities make it possible, on the one hand, to facilitate the deposition of the fiber sheets 600, 700 on the surfaces 96, 97 of the cores 90, and on the other hand, to allow the finishing of material coming from the first and second fiber sheets 600, 700 in at least one of these cavities 95, 98.

[0105] Steps (b) and (c) can be carried out in different ways.

[0106] [Fig.5] illustrates an example of arrangement of the first 600 and second 700 fiber sheets on the tooling 9. Step (b) can be carried out by draping (or in other words by stacking) one or more first fiber sheets 600 on the transverse surfaces 96 of the cores 90. Similarly, step (c) can be carried out by draping one or more second fiber sheets 700 on the longitudinal surfaces 97 of the cores 90.

[0107] The first 600 and second 700 fiber sheets can be placed with the cores 90 on the first sole 92a, then the second sole 92b is placed above the cores 90 and the first sole 92a to close the tooling 9.

[0108] By way of example, one or more first layers of fibers 600 are deposited on one of the transverse surfaces 96 of a first core 90, this deposition is repeated for each of the cores 90 intended to form a first row 60 of transverse profiles 6. Then, one or more second fiber sheets 700 are deposited on at least one of the longitudinal surfaces 97 of all the cores 90 intended to form the first row 60 of transverse profiles 6. Finally, the depositions of the first and second fiber sheets 600, 700 according to this configuration can be repeated as many times as necessary to form two or more than two rows 60 of transverse profiles 6.

[0109] Advantageously, the first sheets of fibers 600 to be placed on one of the transverse surfaces 96 have a second length L600. This second length L600 may be less ([Fig.6]) or greater ([Fig.7]) than the first length L%.

[0110] The first fiber sheets 600 may each comprise discontinuous fiber materials or pleated or torn fibers 606 at their ends 602, 604. This makes it easier to finish the material in the cavities 95, 98 of the cores 96 during step (d).

[0111] The ends 602, 604 of the first fiber sheets 600 may extend transversely along a plane parallel to the first transverse axis B (or the second transverse axis Y).

[0112] The placement of the first 600 and second 700 layers of fibers can be carried out manually and / or automatically by a suitable machine.

[0113] For example, the first and second fiber sheets 600, 700 may be deposited, respectively, on the transverse 96 and longitudinal 97 surfaces of all the cores 90 by the “Pick&Place” technique (English term for a gripping and positioning system). For this, the first and second fiber sheets 600, 700 are prepared on a flat work surface by stacking pieces of discontinuous fibers and / or continuous fibers.

[0114] In another example, the first fiber sheets 600 can be formed by directly depositing on the transverse surfaces 96 discontinuous fibers and possibly pre-cut continuous fibers.

[0115] During the thermocompression step (d), a maximum compaction pressure of 150 bars may be applied to the first 600 and second 700 fiber sheets. For example, the maximum compaction pressure applied to the fiber sheets 600, 700 is 50 bars. In particular, the compaction of the second fiber sheets 700 comprising continuous fibers is carried out with a maximum pressure of 20 bars. The compaction pressure applied in step (d) may vary depending on several parameters, such as the materials used, the viscosity of the matrix, the proportion and / or the shape of the fibers and / or the matrix to be used to compact and cause the material to flow.

[0116] The thermocompression step (d) can be carried out according to several methods of rea- lization illustrated in a non-limiting manner in figures 6 and 7.

[0117] [Fig.6] represents the thermocompression step (d) of the method 100 according to a first embodiment, in which this step (d) is carried out by applying the following compaction(s): - a first compaction (di) of the first layers of fibers 600 in a first direction called transverse (which is perpendicular to the third longitudinal axis X or parallel to the second transverse axis Y), and - a second compaction (d2) of the second layers of fibers 700 in a second direction called longitudinal (which is perpendicular to the second transverse axis Y or parallel to the third longitudinal axis X).

[0118] The direction of compactions (di), (d2) is illustrated by arrows in [Fig.6].

[0119] In other words, the first compaction (dj is carried out along the second axis transverse Y and the second compaction (d2) is carried out along the third longitudinal axis X.

[0120] The second length L60o of the first fiber sheets 600 is preferably less than the first length L96 of the transverse surface 96 of the cores 90.

[0121] The first compaction (di) thus makes it possible to press the first fiber sheets 600 (in particular the pieces of fibers) against each other and to make the material flow into the longitudinal cavities 98. In this way, the second length L60o extends into the longitudinal cavities 98 to be greater than the first length L96. This makes it possible, during the second compaction (d2), to press the second fiber sheets 700 against the first fiber sheets 600 (in particular the ends 602, 604) to bond them. This thermocompression bonding makes it possible to create connection zones 670 between the first 600 and second 700 fiber sheets, which will be made robust after consolidation in step (e). These connection zones 670 are intended to form the junction zones 67 of the grid 5 to be produced.

[0122] [Fig.7] represents the thermocompression step (d) of the method 100 according to a second embodiment which differs from step (d) of the first embodiment by the following compactions: - the first compaction (dj which is applied to the second layers of fibers 700 in a longitudinal direction (along the third longitudinal axis X), and - the second compaction (d2) which is applied to the first layers of fibers 600 in a transverse direction (along the second transverse axis Y).

[0123] The direction of compactions (di), (d2) is also illustrated by arrows in [Fig.7].

[0124] The second length L600 of the first fiber sheets 600 is preferably greater than the first length L96 of the transverse surface 96 of the cores 90. Thus, the ends 602, 604 of the first fiber sheets 600 extend into the longitudinal cavities 98.

[0125] In this second embodiment of step (d), the first compaction (dj) makes it possible to press the second fiber sheets 700 against the first fiber sheets 600. In this way, the ends 602, 604 of the first fiber sheets 600 bond to the second fiber sheets 700 to create the connection zones 670 intended to form the junction zones 67. The second compaction (d2) makes it possible to press the first fiber sheets 600.

[0126] In particular, the second compaction (d2) can also form undulations 702 of the second fiber sheets 700 between the first 600 and second 700 fiber sheets, in particular at the connection zones 670. These undulations 702 provide resistance to rupture in the direction of elongation of the longitudinal profiles 700 (namely the second transverse axis Y). Thus, the thermocompression of step (d) according to the second embodiment has increased mechanical resistance to rupture stresses of the longitudinal profiles (along the second transverse axis Y) compared to that of the longitudinal profiles produced by the thermocompression of step (d) according to the first embodiment.

[0127] At the end of step (d), the transverse profile preforms are thus connected to the longitudinal profile preforms in particular by the connection zones 670. These connection zones 670 can be formed from the first fiber sheets 600 and / or the second fiber sheets 700. The connection zones 670 make it possible to fix at least a portion of the first fiber sheets 600 to at least a portion of the second fiber sheets 700 while maintaining the continuity of the intrados 6a and extrados 6b faces of the transverse profiles 6 to be produced.

[0128] In particular, each preform of transverse profile is extended by four connection zones 670. Indeed, each of the ends 602, 604 of the first fiber sheets 600 can be connected to two longitudinal surfaces of the second fiber sheets 700.

[0129] [Fig.8] illustrates a first example of embodiment of the connection zones 670 which may have a curved shape. The curved connection zones 670 may each have a radius of curvature R. The radius R is measured either between a first transverse plane Pn and a second transverse plane PT2 or between a first longitudinal plane PLi and a second longitudinal plane PL2. The first Pn and second PT2 transverse planes are parallel to the second transverse axis Y. The first PLi and second PL2 longitudinal planes are parallel to the third longitudinal axis X. The transverse planes Pn, PT2 may be substantially perpendicular to the longitudinal planes PLi, PL2. The radius R may be between 0.5 and 5 mm.

[0130] [Fig.8] represents different examples of values ​​of the radius R of the connection zones 670.

[0131] This [Fig.8] illustrates several L connections between the first 600 and the second 700 fiber sheets.

[0132] The first example of embodiment of the connection zones 670 has the advantage that at the connection zones 670, the second fiber sheets 700 of the longitudinal profile preforms are in contact with the first fiber sheets 600 contingent on the intrados 600a and / or extrados 600b surfaces.

[0133] According to a second exemplary embodiment, the connection zones 670 may have a folded “L” shape. In this configuration, the longitudinal surface of the longitudinal profile preforms and one of the intrados 600a and / or extrados 600b surfaces of the transverse profile preforms form a right angle. Thus, the first fiber sheets 600 of the transverse profile preforms extend transversely to the second fiber sheets 700 of the longitudinal profile preforms.

[0134] The consolidation step (e) (also designated by the terms densification, forming or shaping) and the solidification step (f) make it possible to stiffen the preforms of transverse profiles and longitudinal profiles obtained at the end of step (d) to arrive at the final shape of the thrust reverser grid 5 made of composite material.

[0135] In a first embodiment, as described above, the first fiber sheets 600 and / or the second fiber sheets 700 may be pre-impregnated with the resin (i.e. before step (a) of the method 100). Alternatively, the first fiber sheets 600 and / or the second fiber sheets 700 are in a raw state or lightly coated with an organic binder, and then the resin may be injected into the tooling 9, for example by RTM (acronym for “Resin Transfer Molding”), in step (e).

[0136] The resin may be thermosetting. For example, the thermosetting resin is an epoxy resin. In the case of thermosetting resin, the transverse and longitudinal profile proforms are consolidated and solidified by polymerization of the resin, possibly by application of a thermal cycle at the same time and after the thermocompression step.

[0137] The resin may be thermoplastic. For example, the thermoplastic resin is a polyether-ether-ketone, poly-aryl-ether-ketone or poly-ether-imide resin. In this case, an injection of the thermoplastic resin in step (e) or a thermocompression of the first and second pre-impregnated fiber sheets 600, 700 may be carried out at a temperature high enough for this resin to be injectable or malleable. The solidification of step (f) of the part may be carried out by cooling, for example to a temperature for stiffening the thermoplastic resin.

Claims

Claims

1. A method of manufacturing a thrust reverser grid (5) for a nacelle (1) of an aircraft propulsion unit (10), the grid (5) being made of composite material and comprising a plurality of transverse profiles (6) connected to longitudinal profiles (7a, 7b), said transverse profiles (6) being perpendicular to said longitudinal profiles (7a, 7b), the grid (5) also comprising cells (8) each delimited by two transverse profiles (6) and at least partly by two longitudinal profiles (7a, 7b), the method comprising the steps of: (a) providing a tool (9) extending along a longitudinal axis (X) and comprising cores (90) movable in translation relative to the longitudinal axis (X) and configured to form the cells (8) of the grid (5), (b) placing first fiber sheets (600) on transverse surfaces (96) of the cores (90) to form preforms of transverse profiles,(c) placing second fiber sheets (700) on longitudinal surfaces (97) of the cores (90) to form longitudinal profile preforms, (d) performing at least one thermocompression along a transverse direction of said first fiber sheets (600) and / or said second fiber sheets (700) to press and secure said first (600) and second (700) fiber sheets against each other, (e) consolidating all of the transverse and longitudinal profile preforms by impregnating said first (600) and second (700) fiber sheets with a resin, and (f) solidifying all of the transverse and longitudinal profile preforms to form the thrust reverser grid (5).,

2. Manufacturing method according to claim 1, characterized in that step (b) is carried out by draping said first fiber sheets (600) on flat or curved transverse surfaces (96) of the cores (90).

3. Manufacturing method according to claim 1 or 2, characterized in that each of the first fiber sheets (600) has a length (L60o) greater or less than that (L96) of a longitudinal surface (96) corresponding to the nuclei (90).

4. Manufacturing method according to any one of the preceding claims, characterized in that the first fiber sheets (600) and / or the second fiber sheets (700) comprise discontinuous fibers and / or continuous fibers.

5. Manufacturing method according to the preceding claim, characterized in that the first fiber sheets (600) and / or the second fiber sheets (700) comprising the discontinuous fibers have lengths of between 5 and 50 mm.

6. Manufacturing method according to claim 4 or 5, characterized in that the first fiber sheets (600) and / or the second fiber sheets (700) comprising the discontinuous fibers, intrados surfaces (600a) and / or extrados surfaces (600b) of said first fiber sheets (600) and / or longitudinal surfaces of said second fiber sheets (700) comprise pieces of fibers having for example a polygonal shape of width between 5 and 20 mm and length between 5 and 35 mm.

7. Manufacturing method according to any one of claims 4 to 6, characterized in that the first fiber sheets (600) and / or the second fiber sheets (700) comprising the discontinuous fibers, at least 80% of the first fiber sheets (600) comprise discontinuous fibers randomly distributed in a plane.

8. Manufacturing method according to any one of claims 4 to 7, characterized in that at least 80% of the second fiber sheets (700) comprise continuous fibers.

9. Manufacturing method according to any one of the preceding claims, characterized in that each of the first fiber sheets (600) comprises at its transverse ends (602, 604) materials with discontinuous fibers or pleated or lacerated fibers.

10. Manufacturing method according to any one of the preceding claims, characterized in that the transverse profile preforms are connected to the longitudinal profile preforms in step (d) by connection zones (670) formed from at least one of said first (600) and second (700) fiber sheets, these connection zones (670) having a curved or L-shaped folded shape.

11. Manufacturing method according to the preceding claim, characterized in that said connection zones (670) have a radius of curvature (R) of between 0.5 and 5 mm.

12. Manufacturing method according to any one of the preceding claims, characterized in that said first (600) and second (700) fiber sheets are pre-impregnated with the resin, and / or the resin is injected in step (e).

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