Annular shroud for a turbomachine casing, and production method thereof

Abstract

The invention relates to an annular shroud (30) for an annular casing (3) of an aircraft propulsion assembly, the shroud (30) comprising an annular body (300) which extends around an axis (A) and which is made of a composite material, the shroud (30) comprising an axial end (302) having an annular rim (304) projecting radially outwards with respect to said axis, the shroud (30) comprising a metal insert (310) which extends around the axial end (302) and which is joined to the rim (304), the metal insert (310) having an annular groove (318) open radially outwards with respect to said axis; wherein the body (300) and the rim (304) are made from at least one fibrous preform (P1, P2, P3) which is obtained by draping plies of composite material at least partially onto the metal insert (310) and densified by a matrix (M), so as to secure the body (300) and the metal insert to one another.

Description

[0001] DESCRIPTION

[0002] TITLE: ANNULAR SHELL FOR A TURBOMACHINE CASING AND ITS MANUFACTURING METHOD

[0003] Technical field of the invention

[0004] The present invention relates to the general field of annular casings for an aircraft propulsion unit, and more precisely to an annular shell of such an annular casing and its manufacturing method.

[0005] Technical background

[0006] The state of the art includes in particular documents FR-A1 -3121709 and F R-A1 -3009697.

[0007] An aircraft propulsion system typically includes a turbomachine and a nacelle configured to attach around the turbomachine.

[0008] The nacelle is typically equipped with several cowls surrounding the turbomachine, allowing access to the latter in the open position. These cowls are known as fan cowls and thrust reverser cowls.

[0009] The turbomachine comprises several annular casings, such as a fan casing extended rearwardly by a so-called intermediate casing. The intermediate casing corresponds to a structural element arranged between the fan casing located further upstream, and nacelle cowls located further downstream. The intermediate casing generally comprises an annular shroud (known as the VCI intermediate casing shroud), an internal hub, as well as structural arms distributed angularly and extending radially between the internal hub and the annular shroud which they connect.

[0010] The intermediate casing including the VCI shell is typically a single-piece machined metal part.

[0011] Figure 1 illustrates a common example of the VCI annular ferrule construction. This annular ferrule 30 comprises an annular body 300 which extends around a longitudinal axis A and made of composite material, an axial end 302, an annular rim 304 projecting radially outwards relative to the axis A, and a metal insert 310 which extends around the axial end 302. The metal insert 310 comprises first and second annular lateral walls 312, 314 connected to each other by an annular bottom wall 316. In the example of FIG. 1, the second lateral wall 314, which is the furthest downstream, forms the annular rim 304 of the annular ferrule 30. These lateral and bottom walls 312, 314, 316 delimit between them an annular groove 318. The annular groove 318 has in axial section a generally V-shaped or V-shaped shape. U. This annular groove 318 is intended to receive a connecting member of the thrust reverser cover.The cooperation between the connecting member and the annular groove of the annular shroud allows the transmission of aerodynamic forces from the nacelle to the turbomachine, during takeoff, flight and landing phases, in particular axial forces, and even more particularly axial counter-thrust forces when thrust reverser systems fitted to the nacelle cowls are actuated.

[0012] In the annular ferrule 30 of FIG. 1, the metal insert 310 is attached and fixed to the axial end 302 by screws V. This has the disadvantage of making the annular ferrule bulky and heavy. In addition, the manufacture and assembly of such an annular ferrule can be complex to carry out.

[0013] It is also known to produce the annular body 300 and the axial end 302 with the annular rim 304 integrally from composite material, then to attach the metal insert 310 by gluing, as illustrated in FIG. 2. For this, the annular ferrule 300 is produced from two annular fiber preforms P1, P2 obtained by three-dimensional weaving and densified by a matrix. A first annular fiber preform P1 forms a part of the axial end 302 and comprises an annular tab P10 forming a part of the annular rim 304, a second annular fiber preform P2 forms the other part of the axial end 302 and comprising an annular arm P20 forming a part of an annular rib 306 of the annular ferrule 300. The annular tab P10 and the annular arm P20 delimit between them the annular groove 318. The metal insert 310 is glued inside this annular groove 318.

[0014] The annular ferrule 30 of Figure 2 thus proposes to produce an annular body made of composite material and the metal insert separately and assembled together by gluing. This solution also has the disadvantage that the manufacture and assembly of such an annular ferrule can be complex to carry out because it requires a large number of operations which are in particular very little automated.

[0015] In these different contexts, it is interesting to overcome the drawbacks of the prior art, by proposing an annular shell for an annular casing of an aircraft propulsion unit which is more robust and easy to produce and assemble.

[0016] Summary of the invention

[0017] The present invention provides a simple, effective and economical solution to at least some of the above-mentioned problems.

[0018] To this end, the invention proposes an annular ferrule for an annular casing of an aircraft propulsion unit, the annular ferrule comprising an annular body which extends around an axis A and which is made of composite material, the annular ferrule comprising an axial end having an annular rim projecting radially outwards relative to said axis A, the annular ferrule comprising a metal insert which extends around the axial end and which is attached to the annular rim, the metal insert having an annular groove open radially outwards relative to said axis A.

[0019] According to the invention, the annular body and the annular rim are made from at least one annular fibrous preform obtained by draping plies of composite material at least in part over the metal insert and densified by a matrix, so as to make the annular body and the metal insert integral. This solution makes it possible to achieve the aforementioned objective. For this, the invention proposes to link (and also to form) the annular body of composite material and the metal insert in a single piece (or in other words in a single piece and in a single piece) and to eliminate the mechanical type fixing means (such as screws or glue).

[0020] This one-piece connection (produced for example by draping) is simple to implement (in particular in an automated manner), solid and difficult to damage during operation. In particular, the annular shell according to the invention proposes to simultaneously form the annular body and the annular rim in composite material by draping at least in part directly onto the metal insert. The one-piece connection also makes it possible to form the annular shell (in particular the annular rim) more robust to the mechanical stresses exerted for example by the covers of the propulsion unit. This thus significantly improves the mechanical strength of this annular shell.

[0021] Furthermore, the invention makes it possible to reduce the number of additional parts (such as screws, nuts, bolts, bonding interfaces between the annular body made of composite material and the metal insert) to produce the less massive and space-saving annular shell.

[0022] 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, mass and size in an aircraft propulsion system.

[0023] Laying means stacking and superimposing several layers / plies of composite material (e.g. in the form of strips or ribbons). Composite material generally includes fibers.

[0024] By two parts or pieces "formed from a single piece" or "monobloc", we mean the fact that these two parts or pieces are physically connected to each other and cannot be separated without damaging them. The annular ferrule according to the invention may comprise one or more of the following characteristics, taken in isolation from each other or in combination with each other:

[0025] - the metal insert comprises first and second annular side walls and an annular bottom wall which connects these first and second side walls, the first and second side walls and the bottom wall delimiting between them said annular groove;

[0026] - the annular ferrule further comprises an interface layer located between the metal insert and said at least one fiber preform;

[0027] - said at least one fiber preform comprises a first annular fiber preform having an L-shape in axial section, this first fiber preform comprising an annular tab forming a part of said annular rim; and at least a part of the metal insert, such as the second side wall, forming another part of this annular rim;

[0028] - said axial end further comprises an annular rib extending parallel to the annular rim, and at a distance from the latter, this annular rib extending radially outwards relative to said axis A, said metal insert being located between this annular rib and said annular rim;

[0029] - said at least one fiber preform further comprises second and third annular fiber preforms, the second fiber preform comprising in axial section a U-shape, first and second annular arms forming, respectively, at least one part of the annular rib and at least another part of the annular rim, and the third fiber preform comprising in axial section an L-shape and comprising an annular leg forming another part of the annular rib; -- the metal insert has in axial section a U-shape, a V-shape or a T-shape;

[0030] -- the metal insert is annular and extends around the axis A;

[0031] -- the metal insert is sectorized into several metal insert sectors;

[0032] -- the metal insert sectors are connected to each other by a joint, so as to form the annular-shaped metal insert;

[0033] -- the metal insert comprises between one and six metal insert sectors;

[0034] -- the metal insert sector has an angular extent of between 60° and 360°;

[0035] -- the fiber preform comprises carbon fibers, ceramic fibers (such as silicon carbide, glass, or aramid), polyamide fibers, metal fibers, oxide fibers, or a mixture of at least two of these fibers;

[0036] -- the metal insert is made of aluminum, steel or titanium;

[0037] -- the annular ferrule further comprises at least one annular cavity between the metal insert and the at least one fiber preform, this annular cavity being filled with a filling material, such as a resin.

[0038] The invention also relates to an annular casing for an aircraft propulsion assembly, comprising an annular shroud according to the invention.

[0039] The annular casing may be an intermediate casing of the aircraft propulsion unit.

[0040] The invention also relates to an aircraft propulsion assembly comprising a turbomachine and a nacelle surrounding at least a portion of the turbomachine. The aircraft propulsion assembly comprises an annular shroud according to one of the features of the invention or an annular casing according to the invention, this propulsion assembly further comprising a connecting member, for example of a cowl of the nacelle, which is fixed in the annular groove of the annular shroud. The invention further relates to a method for manufacturing an annular shroud according to one of the features of the invention. The method comprises the steps of:

[0041] (a) providing the metal insert and a layup tool each having an annular shape, the metal insert and the tool each having an annular inner layup surface and furthermore at least one annular radial layup surface relative to the axis A,

[0042] (b) producing at least one annular fibrous blank by draping plies of composite material at least in part on at least one of said internal and radial surfaces of the metal insert and on at least one of said internal and radial surfaces of the tool,

[0043] (c) densifying the at least one fibrous blank and the metal insert with the matrix by co-firing to form said at least one fibrous preform secured to the metal insert of the annular ferrule.

[0044] The method according to the invention makes it possible to simplify and make more robust the manufacture of the annular shell. To this end, one or more annular fiber preforms are obtained by draping plies of composite material. Then, the annular fiber preform(s) are secured directly to the metal insert during the densification and co-firing step to form the annular shell of the invention.

[0045] In addition, this method is suitable for automated (for example by a suitable machine) or manual manufacture of the annular ferrule. In particular, the draping can be carried out manually or automatically, for example using the AFP technique (acronym for "Automated Fiber Laying"), the ATL technique (acronym for "Automated Tape Laying") or the P&P technique (acronym for "Pick&Place" for a gripping and positioning system). In the present application, the term "fiber blank" means a fiber texture obtained by draping plies of composite material and intended to form at least part of the part to be produced before the densification step.

[0046] By "fiber preform" is meant a fibrous texture intended to form at least part of the part to be produced after the densification step. The fiber preform is thus formed from a blank which is densified (and therefore embedded) in a resin.

[0047] The term "co-firing" means the act of simultaneously firing (in particular by heat treatment or otherwise by heating) the metal insert (produced separately) and the annular fibrous blank(s) (which are draped at least in part over this metal insert) to form a single piece subjected to firing.

[0048] In this application, the term "curing" will be understood as curing in the proper sense, for example for materials such as epoxy type resins which need to be cured, or consolidation, for example for materials such as thermoplastic type resins which require consolidation.

[0049] The manufacturing method according to the invention may comprise one or more of the following characteristics, taken in isolation from one another or in combination with one another:

[0050] - step (c) comprises a polymerization of said at least one fibrous blank with a resin and the transformation of this resin into a matrix by a co-firing heat treatment;

[0051] - said resin is injected into said at least one fibrous blank in step (c), or said at least one fibrous blank is previously impregnated with the resin before step (b) of draping;

[0052] - in step (b), the metal insert and the tooling are aligned axially side by side along the axis A, then first plies of composite material are draped at least in part over said internal surfaces and one of said radial surfaces of the metal insert so as to form the first fibrous blank with an L-shape in axial section;

[0053] - step (b) comprises the following sub-steps:

[0054] (bi) draping second plies of composite material at least in part over said internal and radial surfaces of the metal insert to form the second fibrous blank with a U-shape in axial section,

[0055] (b2) draping third plies of composite material at least in part over said internal and radial surfaces of the tooling to form the third fiber blank with an L-shape in axial section,

[0056] (bs) axially aligning side by side along axis A, the second and third draped fiber blanks, respectively, on the metal insert and the tooling, and

[0057] (b4) draping first plies of composite material at least in part over annular inner faces of the second and third fibrous blanks and an annular radial face of the second fibrous blank to form the first fibrous blank with an L-shape in axial section;

[0058] - before step (b), the method comprises a step (i) of depositing the interface layer at least in part on at least one of said internal and radial surfaces of the metal insert;

[0059] - the resin is in a thermosetting or thermoplastic material, for example based on epoxy, polyepoxide, polyimide, polybismaleimide, polyurethane, polyester or vinylester;

[0060] -- the draping step (b) is carried out manually or automatically with a suitable machine;

[0061] -- the composite material plies each comprise glass fibers, carbon fibers, aramid fibers, polyamide fibers, ceramic fibers (such as silicon carbide, glass, or aramid), metal fibers, oxide fibers, or a mixture of at least two of these fibers. Brief description of the figures

[0062] The invention will be better understood and other details, characteristics and advantages of the invention will appear more clearly on reading the following description given by way of non-limiting example and with reference to the appended drawings in which: Figure 1 is a schematic half-view in axial section of an annular ferrule according to a first embodiment of the prior art, comprising a metal insert attached by screws to an annular body made of composite material; Figure 2 is a schematic half-view in axial section of an annular ferrule according to a second embodiment of the prior art, comprising a metal insert bonded to an annular body made of composite material obtained by three-dimensional weaving of threads; Figure 3 is a schematic half-view in axial section of an aircraft propulsion assembly according to the invention;Figure 4 is a schematic perspective view of an annular casing of a turbomachine of the aircraft propulsion assembly of Figure 3; Figure 5a is a schematic half-view in axial section of a first example of an annular shell of the annular casing of Figure 4 and a connecting member of the aircraft propulsion assembly; Figure 5b is a schematic half-view in axial section of a variant of the annular shell of Figure 5a; Figure 6 is a schematic half-view in axial section of a second example of an annular shell of the annular casing of Figure 4; Figure 7 is a schematic half-view in axial section of a third example of an annular shell of the annular casing of Figure 4; Figure s is a schematic half-view in axial section of a fourth example of an annular shell of the annular casing of Figure 4;Figure 9 is a block diagram of a method for manufacturing the annular ferrule of the invention, Figure 10 schematically represents a first example of production of a fiber preform by draping plies of composite material on the metal insert to obtain the annular ferrule of Figure 5a; Figure 11 schematically represents a second example of production of several fiber preforms by draping plies of composite material on the metal insert to obtain the annular ferrule of Figure 6. The elements having the same functions in the different implementations have the same references in the figures.;

[0063] Detailed description of the invention

[0064] By convention, in the description below, the terms "longitudinal" and "axial" describe the orientation of structural elements extending in the direction of a longitudinal axis (such as that of an aircraft propulsion system). 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 in reference 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. Similarly, the terms "upstream" and "downstream" are defined in relation to the direction of circulation of the gases in the aircraft propulsion system.

[0065] Figures 1 and 2 have been described in the technical background of the present application, and they illustrate examples of an annular ferrule according to the prior art, for an annular casing of an aircraft propulsion assembly.

[0066] The invention applies in a general and non-limiting manner to an aircraft propulsion assembly 10, illustrated for example in FIG. 3. This aircraft propulsion assembly 10 comprises a turbomachine 1 and a nacelle 2 surrounding at least a portion of the turbomachine 1.

[0067] The aircraft propulsion assembly 10 can extend along a longitudinal axis X.

[0068] The nacelle 2 may extend along a longitudinal axis which may correspond to the X axis. The nacelle 2 may comprise one or more covers. Each nacelle cover 2 may be a single-part cover of annular shape or half-covers of semi-cylindrical shape which are hinged together.

[0069] With reference to Figure 3, the nacelle 2 comprises, from upstream to downstream in the direction F of gas flow, an annular air inlet structure 2a, a fan cowl 2b and a thrust reverser cowl 2c.

[0070] The thrust reverser cowl 2c can delimit an annular channel 20 of secondary air flow F2, thanks to internal 21 and external 22 annular skins. In particular, the external skin 22 can be formed by the thrust reverser cowl 2c and the internal skin 21 can be formed by an annular casing (such as that of an intermediate casing 3 of the turbomachine

[0071] The turbomachine 1 can also extend around a longitudinal axis which can correspond to the X axis. This turbomachine 1 can be configured to be fixed to a structure of the aircraft (for example an aircraft wing or along an aircraft fuselage).

[0072] The turbomachine 1 generally comprises several modules comprising, from upstream to downstream in a gas flow direction F, a fan 1 a, one or more compressor stages (for example a low pressure compressor 1 b and a high pressure compressor 1 c), a combustion chamber 1 d, one or more turbine stages (for example, a high pressure turbine 1 e and a low pressure turbine 1 f), and possibly a gas exhaust nozzle.

[0073] The turbomachine 2 may be a dual-flow turbojet. In this configuration, the fan 1, generally at the front of the turbomachine 1, delivers a compressed air flow which is separated into two concentric annular flows: a primary air flow F1 and a secondary air flow F2 extending around the primary air flow F1.

[0074] The turbomachine 1 may comprise several annular casings, such as at least one of the following casings:

[0075] - a fan casing 4 extending around the fan 1 a,

[0076] - the intermediate casing 3 extending over an upstream part of the rest of the turbomachine 1 (namely the low pressure compressor 1 b in the example of figure 3), and

[0077] - a central casing 5 extending a hub 32 of the intermediate casing 3 downstream, and to which it is connected.

[0078] This turbomachine 1 of the shrouded type, can be a turbojet or a turboprop.

[0079] In the example of Figure 3, the central casing 5 can extend around the compressor stage 1a, 1b, the combustion chamber 1d, the turbine stage 1e, 1f and possibly the exhaust nozzle.

[0080] The intermediate casing 3 may comprise an annular shell 30, the hub 32 said to be internal relative to the axis X, as well as structural arms 34 distributed angularly and extending radially between the hub 32 and the annular shell 30 which they connect. The annular shell 30 extends around the hub 32.

[0081] With reference to Figure 4, the annular ferrule 30 comprises:

[0082] - an annular body 300 which extends around an axis A,

[0083] - an axial end 302 having an annular rim 304 projecting radially outwards relative to the axis A, and

[0084] - a metal insert 310 which extends around the axial end 302 and which is attached to the annular rim 304.

[0085] The axis A may extend longitudinally and may substantially correspond to the longitudinal axis X of the aircraft propulsion assembly 10.

[0086] The annular shroud 30 may also comprise a radial flange 301 for attachment, for example, to the fan casing 4. This radial flange 301 may be annular in shape and located opposite the axial end 302. In the example of FIG. 4, the annular body 300 forming the basic structural part of the annular shroud 30, comprises from upstream to downstream (relative to the direction F of gas flow) the radial flange 301, a shroud barrel 300a of cylindrical shape and circular section, the axial end 302 and the annular rim 304. The radial flange 301, the shroud barrel 300a, and the axial end 302 with the annular rim 304 may be in one piece.

[0087] The annular body 300 is made of composite material. Thus, the ferrule barrel 300a, the axial end 302 with the annular rim 304, and possibly the radial flange 301, can be made of composite material.

[0088] The metal insert 310 comprises an annular groove 318 open radially outwards relative to the axis A. The annular groove 318 may have a general U or V shape in axial section. This annular groove 318 may be configured to receive a connecting member 24 of the aircraft propulsion assembly 10 (such as one of the cowls of the nacelle 2 and in particular the thrust reverser cowl 2c).

[0089] Examples of this metal insert 310 are illustrated in a non-limiting manner in FIGS. 5a to 8.

[0090] Advantageously, the metal insert 310 may be annular and extend around the axis A (in particular on and around the axial end 302). The metal insert 310 may either be formed from a single piece and in a single piece, or sectorized into several metal insert sectors.

[0091] For example, the metal insert 310 may comprise between one and six metal insert sectors. Preferably, the metal insert 310 may be formed from two metal insert sectors.

[0092] The metal insert sector may have an angular extent (relative to the axis A) of between 60° and 360°. Thus, the angular extent may be 360° when the metal insert 310 is formed from a single metal insert sector and is annular in shape. The angular extent may be 180° when the metal insert 310 is formed from two metal insert sectors. The angular extent may be 60° when the metal insert 310 is formed from six metal insert sectors. The metal insert 310 may be made of aluminum, steel or titanium.

[0093] The metal insert 310 may have in axial section a U-shape, a V-shape (as illustrated in FIGS. 5a to 7), a T-shape (as illustrated in FIG. 8) or any other so-called hollow shape capable of accommodating (or otherwise said to be complementary) to the shape in particular of the axial end 302 of the annular ferrule.

[0094] This metal insert 310 may comprise first and second annular side walls 312, 314 and an annular bottom wall 316. This bottom wall 316 connects the first and second side walls 312, 314 to each other. The first and second side walls 312, 314 extend radially outward relative to the axis A in the example of FIG. 5a. The bottom wall 316 may extend axially along the axis A. The first and second side walls 312, 314 and the bottom wall 316 delimit the annular groove 318 between them.

[0095] The first and second side walls 312, 314 and the bottom wall 316 may be formed as a single piece (i.e., integrally formed).

[0096] The sectorized metal insert 310 may comprise a seal 319 intended to connect the metal insert sectors together. The seal 319 may be a silicone adhesive. For example, the seal 319 may be arranged in the annular groove 318, in particular on and around the annular bottom wall 316 of the metal insert sectors.

[0097] The metal insert 310 (in particular the bottom wall 316) may comprise an internal annular surface 310c (relative to the axis A). The metal insert 310 (in particular each of the first and second side walls 312, 314) may comprise first and second radial annular surfaces 310a, 310b (relative to the axis A). These radial surfaces 310a, 310b and internal 310c are preferably spaced from the annular groove 318.

[0098] The second side wall 314 (in particular the second radial surface 310b) may be attached to the annular rim 304 and / or may correspond to a part of this annular rim 304. In this way, the annular rim 304 is reinforced to withstand the mechanical stresses exerted by the covers of the nacelle 2 in operation.

[0099] The bottom wall 316 (in particular the inner surface 310c) may extend around at least a portion of the axial end 302.

[0100] In the example of Figure 5a and in a non-limiting manner, the first side wall 312 may have a first diameter D312 less than a second diameter D314 of the second side wall 314. According to a variant not illustrated in the figures, the first diameter D312 may be equal to the second diameter D314. The first and second diameters D312, D314 are measured along a plane perpendicular to the axis A.

[0101] One of the particularities of the invention is that the annular body 300 and the annular rim 304 are made from at least one annular fiber preform P1, P2, P3. This or these fiber preforms P1, P2, P3 are obtained by draping plies of composite material (simplified hereinafter by "draping") at least in part on the metal insert 310 and densified by a matrix M. In this way the annular body 300 is made integral with the metal insert 310. In other words, the annular body 300 and the annular rim 304, which are formed of composite material, and the metal insert 310 are monobloc and formed in one piece.

[0102] The fiber preform(s) P1, P2, P3 may each comprise a U-shape or L-shape in axial section. The dimensions (axial length, radial height, etc.) of the U-shapes and L-shapes of the fiber preforms P1, P2, P3 may vary depending on the different embodiments of the invention described below.

[0103] The annular ferrule 30 may further comprise an interface layer 308 located between the metal insert 310 and the fiber preform P1, P2. This interface layer 308 may extend annularly around the axis A. The interface layer 308 may be made of elastomer. The interface layer 308 makes it possible to withstand differential expansions, in particular thermal expansions, between the metal insert 310 and the fiber preform P1, P2. These differential expansions may occur during manufacturing (for example during a step of injecting resin into a mold) or as a function. The interface layer 308 also makes it possible to protect the annular body 300 and the annular rim 304 made of composite material against possible galvanic corrosion, in particular when the metal insert 310 is made of aluminum.

[0104] The composite material plies of the fiber preform(s) P1, P2, P3 may comprise glass fibers, carbon fibers, aramid fibers, polyamide fibers, ceramic fibers (such as silicon carbide, glass, or aramid), metal fibers, oxide fibers, or a mixture of at least two of these fibers.

[0105] The present application will now describe the different possible configurations of the annular ferrule 30 of the invention, and in particular of the fiber preform(s) P1, P2, P3, with reference to FIGS. 5a to 8.

[0106] Figures 5a and 5b illustrate a first embodiment of the annular ferrule 30, in which the annular body 300 and the annular rim 304 (as described above with reference to Figures 3 and 4) can be made from a first annular fiber preform P1. This first fiber preform P1 can have a general L-shape in axial section. The first fiber preform P1 can have an axial length LPI measured along the axis A.

[0107] The first fiber preform P1 may comprise a cylindrical portion P100 of circular section which extends along the axis A and which is intended to form at least one part of the annular body 300 (such as the ferrule barrel 300a and possibly the radial flange 301 and the axial end 302).

[0108] The cylindrical portion P100 may comprise an annular end portion P102 intended to form at least a portion of the axial end 302. In the example of FIGS. 5a and 5b, the end portion P102 may form at least a portion of the axial end 302 of the annular ferrule 30. In particular, this end portion P102 may be attached to the internal surface 310c. Thus, the bottom wall 316 may extend around the end portion P102.

[0109] The first fiber preform P1 may comprise an annular tab P10. The annular tab P10 may extend radially outward relative to the axis A in the example. In particular, this annular tab P10 may be attached to the second side wall 314 (in particular at the level of the second side surface 310b). This annular tab P10 is intended to form a portion of the annular rim 304 of the annular ferrule 30, and the metal insert (in particular the second side wall 314) forms another portion of this annular rim 304. Thus, the annular tab P10 and the second side wall 314 may together form the annular rim 304.

[0110] The annular tab P10 may have a third diameter Dpio which is measured along a plane perpendicular to the axis A (or the axis X). In the example of Figures 5a and 5b, the third diameter Dpio is similar to the second diameter D314 of the second side wall 314. In a variant not illustrated in the figures, the third diameter Dpio may be less than the second diameter D314 of the second side wall 314. According to another variant, the third diameter Dpio may be similar to the first diameter D312 of the first side wall 312.

[0111] The first fiber preform P1 can therefore be monobloc and formed in one piece with the metal insert 310.

[0112] With reference to Figure 5b, the annular ferrule 30 of the first embodiment may comprise the interface layer 308 between at least a portion of the first fiber preform P1 and the metal insert 310. This interface layer 308 may be formed, on the one hand, between the bottom wall 316 (in particular the internal surface 310c) and at least a portion of the first fiber preform P1 (in particular the end portion P102), and on the other hand, between the second side wall 314 (in particular the second radial surface 310b) and at least a portion of the annular tab P10. Thus, the interface layer 308 may be interposed between, on the one hand, the second radial surface 310b and the annular tab P10, and on the other hand, between the internal surface 310c and the end portion P102.

[0113] In the annular ferrule 30 of the first embodiment, the metal insert 310 has a substantially U-shaped general shape in axial section. As for the annular groove 318, it has a substantially V-shaped general shape in axial section.

[0114] Figure 6 illustrates a second embodiment of the annular ferrule 30 which differs from the annular ferrule 30 of the first embodiment by the presence of an additional annular rib 306 and the presence of several additional fiber preforms P2, P3 to form the annular body 300 and the annular rim 304.

[0115] Indeed, the annular ferrule 30 of the second embodiment further comprises this annular rib 306 which extends parallel to the annular rim 304, and at a distance from this annular rim 304. The annular rib 306 projects radially outwards relative to the axis A. In this configuration, the metal insert 310 is located between the annular rib 306 (in particular a first annular arm P22 of the second fiber preform P2) and the annular rim 304 (in particular a second annular arm P24 of the second fiber preform P2). Thus, the annular rib 306 can be attached to the first side wall 312 (in particular on the first radial surface 310a), and the annular rim 304 can be attached to the second side wall 314 (in particular on the second radial surface 310b).

[0116] The annular rib 306 may have a fourth diameter D306 less than or equal to a fifth diameter D304 of the annular rim 304. The fourth diameter D306 may be identical (FIG. 6) or less than the first diameter D312. The fifth diameter D304 may be identical (FIG. 6) or less than the second diameter D314. The fourth D306 and fifth D304 diameters are measured along a plane perpendicular to the axis A. Furthermore, the annular body 300 and the annular rim 304 of the second embodiment may be made from the first fiber preform P1 (as described above with reference to FIGS. 5a and 5b) and also from a second annular fiber preform P2 and a third annular fiber preform P3.

[0117] The first fiber preform P1 of the second embodiment differs from that of the first embodiment by its position in the annular ferrule 30. In the second embodiment, the second and third fiber preforms P1, P2 can extend, on the one hand, axially side by side (or otherwise said attached to one another), and on the other hand, radially around the first fiber preform P1 (in particular the cylindrical portion P100 and possibly the end portion P102 for the second fiber preform P2).

[0118] The second fiber preform P2 may have a general U-shape in axial section. This second fiber preform P2 may have a second axial length LP2 measured along the axis A. This second axial length LP2 may be less than the first axial length LPI.

[0119] The second fiber preform P2 may comprise the first P22 and second P24 annular arms intended to form, respectively, at least a portion of the annular rib 306 and at least a portion of the annular rim 304.

[0120] The first and second annular arms P22, P24 may each extend radially outwardly relative to the axis A. The first annular arm P22 may be attached to the first side wall 312 (in particular on the first radial surface 310a). The second annular arm P24 may be attached to the second side wall 314 (in particular on the second radial surface 310b).

[0121] The first and second annular arms P22, P24 may have, respectively, sixth and seventh diameters DP22, DP24 which are measured along a plane perpendicular to the axis A. The first diameter D312 may be identical (figure 6) or smaller than the sixth diameter DP22. The second diameter D314 may be identical (figure 6) or smaller than the seventh diameter DP24.

[0122] The second fiber preform P2 may further comprise a bottom P202 connecting the first and second annular arms P22, P24 together. This bottom P202 may extend axially along the axis A. The bottom P202 may be intended to form at least a portion of the axial end 302 of the annular ferrule 30 and the other portion of the axial end 302 being formed by the end portion P102 of the first fiber preform P1.

[0123] Advantageously, the metal insert 310 may be covered at least in part by the second fiber preform P2. In particular, the second fiber preform P2 (via the first and second annular arms P22, P24 and the bottom P202) covers the radial surfaces 310a, 310b and internal surfaces 310c of the metal insert 310.

[0124] The third fiber preform P3 may have a general L-shape in axial section. This third fiber preform P3 may have a third axial length Lps measured along the axis A. This third axial length Lps may be less than the first axial length LPI. The third axial length LPS may be greater than the second axial length LP2.

[0125] The third fiber preform P3 may comprise a cylindrical portion P300 of circular section which extends along the axis A and which is intended to form at least one other portion of the annular body 300 (such as the ferrule barrel 300a and possibly the radial flange 301). This cylindrical portion P300 may extend at least partly around the cylindrical portion P100. The third fiber preform P3 may comprise an annular leg P30. The annular leg P30 may extend radially outward relative to the axis A in the example of FIG. 6. In particular, this annular leg P30 may be attached to the first annular arm P22. This annular leg P30 may be intended to form another portion of the annular rib 306 of the annular ferrule 30.In this configuration, the first annular arm P22 (with possibly the first side wall 312) forms a part of the annular rib 306 and the annular leg P30 forms the other part of this annular rib 306.

[0126] The annular leg P30 can have an eighth diameter DPSO which is measured along a plane perpendicular to the A axis (or the X axis). In the example of Figure 6, the eighth diameter DPSO is similar to the first and sixth diameters D312, DP22.

[0127] The first, second and third fiber preforms P1, P2, P3 can therefore be single-piece and formed in one piece with the metal insert 310. In the example of FIG. 6 and in a non-limiting manner, the annular ferrule 30 of the second embodiment can comprise the interface layer 308 between at least a portion of the second fiber preform P2 and the metal insert 310. This interface layer 308 can be formed between:

[0128] - the bottom wall 316 and the bottom P202 of the second fiber preform P2,

[0129] - the first side wall 312 and the first annular arm P20 of the second fiber preform P2, and

[0130] - the second side wall 314 and the second annular arm P24 of the second fiber preform P2.

[0131] Thus, the interface layer 308 can be interposed between the radial surfaces 310a, 310b and internal 310c of the metal insert 310 and the annular arms P22, P24 and the bottom P202 of the second fiber preform P2.

[0132] Figure 7 illustrates a third embodiment of the annular ferrule 30 which differs from the annular ferrule 30 of the second embodiment by the metal insert 310.

[0133] Indeed, the metal insert 310 of the third embodiment may have one of the first and second side walls 312, 314 which is inclined relative to one of the corresponding annular arms P22, P24, so as to form an annular cavity between the side wall and the corresponding annular arm. This annular cavity may be filled with a filling material, such as a so-called polymerization resin forming the densification matrix M. This resin may be in a thermosetting or thermoplastic material, for example based on epoxy, polyepoxide, polyimide, polybismaleimide, polyurethane, polyester or vinylester.

[0134] In the example of Figure 7 and in a non-limiting manner, the first side wall 312 is inclined relative to the first annular arm P22. This first side wall 312 may thus comprise a first radial end 312a which extends radially outwards (relative to the axis A) and a second radial end 312b opposite this first radial end 312a. The first radial end 312a is attached to the first annular arm P22 and the second radial end 312b is distant from this first annular arm P22.

[0135] Figure 8 illustrates a fourth embodiment of the annular ferrule 30 which differs from the annular ferrule 30 of the first, second and third embodiments by the metal insert 310. In particular, the metal insert 310 has the axial section of the T shape.

[0136] This metal insert 310 of Figure 8 comprises the first and second annular side walls 312, 314, the annular bottom wall 316 (as described above) and an axial tab 317. This axial tab 317 may be an axial extension of the annular bottom wall 316. The axial tab 317 may extend between a first end and a second end opposite the first end. The first end may be connected to the annular bottom wall 316 and to the second annular side wall 314. The second end may be free. At least a portion of the axial tab 317 (in particular the second end) may be thickened.

[0137] In this example of figure 8, the first annular lateral wall 302 can be attached to the annular rim 304 of the annular body 300. In a variant not illustrated in the figures, the second annular lateral wall 314 can be attached to the annular rim 304 and the axial tab 317 can be connected to the first annular lateral wall 312 and to the annular bottom wall 316. According to another variant not illustrated, the annular rim 304 is optional and can be absent from the annular ferrule 30 when the metal insert 310 has a T shape in axial section.

[0138] Furthermore, the metal insert 310 of FIG. 8 is sectorized and therefore comprises the seal 319 making it possible to connect the metal insert sectors so as to form an annular part. In a non-limiting manner, this seal 319 is arranged at the axial tab 317. In particular, the seal 319 may be in the form of an annular strip on which the axial tabs 317 of the metal insert sectors are glued.

[0139] As described with reference to the first embodiment of the annular ferrule, the annular body 300 according to the example of FIG. 8 can be produced from the first annular fiber preform P1.

[0140] The present application now describes a method of manufacturing the annular ferrule 30 of the invention, successive steps of the method of which are for example summarized in Figure 9. The optional steps are represented in dotted lines.

[0141] According to the invention, the method comprises the following steps:

[0142] (a) provide the metal insert 310 and a draping tool O,

[0143] (b) producing at least one fiber blank T1, T2, T3 by draping plies of composite material at least partly on the metal insert 310 and at least partly on the tool O,

[0144] (c) densifying this at least one fibrous blank T1, T2, T3 and the metal insert 310 with the matrix M by co-firing to produce the at least one fibrous preform P1, P2, P3 secured to the metal insert 310 of the annular ferrule 30.

[0145] In step (a), the metal insert 10 may be formed from a single piece or sectorized. The metal insert sectors may be connected to each other, in particular by the seal 319, so as to form an annular piece. The metal insert 310 and the tool O may therefore each have an annular shape.

[0146] The tooling O has an internal annular surface Oi and a lateral annular surface Oi which are each configured to receive the layup of step (b). This lateral surface Oi extends radially outward (relative to the axis A). The first and second radial surfaces 310a, 310b and the internal surface 310c of the metal insert 310 are each configured to receive the layup of step (b).

[0147] In step (b), the draping is carried out at least in part on at least one of the internal surfaces 310c and radial surfaces 310a, 310b of the metal insert 310 and on the internal surface Oi of the tooling.

[0148] The draping step (b) can be carried out in different ways.

[0149] Figure 10 illustrates a first example embodiment of step (b), in which the metal insert 310 and the tooling O can be aligned axially side by side along the axis A. In particular, the lateral surface Oi of the tooling O and the first radial surface 310a of the metal insert 310 can be joined along the axis A. Then, first plies of composite material can be draped, in particular simultaneously, at least in part on the internal surface Oi of the tooling and on at least one of the internal surfaces 310c and radial surfaces 310a, 310b of the metal insert 310 to form a first annular fiber blank T1 with an L-shape in axial section. This first fiber blank T1 is intended to form the first fiber preform P1 (in particular after step (c)).

[0150] In particular, the L-shape in axial section of the first fiber blank T1 can be produced by draping the internal surfaces Oi, 310c and the second radial surface 310b by the first plies of composite material. Thus, the draping of the internal surfaces Oi, 310c makes it possible to form the cylindrical portion P100 and the end portion P102 (in particular after the densification step (c)) and the draping of the second radial surface 310b makes it possible to form the annular tab P10 (in particular after the step (c)). Figure 11 illustrates a second example of embodiment of step (b) which can comprise the following sub-steps consisting of:

[0151] (bi) draping second plies of composite material at least in part over the internal 310c and radial 310a, 310b surfaces of the metal insert 310 to form a second annular fibrous blank T2 with a U-shape in axial section and intended to form the second fibrous preform P2 (in particular after step (c)),

[0152] (b2) draping third plies of composite material at least in part over the internal Oi and lateral Oi surfaces of the tool O to form a third annular fibrous blank T3 with an L-shape in axial section and intended to form the third fibrous preform P3 (in particular after step (c)),

[0153] (bs) axially aligning side by side along the axis A, the second and third fiber blanks T2, T3 draped, respectively, on the metal insert 310 and the tooling O, and

[0154] (b4) draping the first plies of composite material at least partly over internal annular faces T2i, T3i of the second and third fiber blanks T2, T3 and a radial annular face T2 r of the second fiber blank T2 to form the first fiber blank T1 with the L shape in axial section.

[0155] Step (bs) makes it possible to assemble the second and third fiber blanks T2, T3 and align them along the axis A in order to be able to form, on the one hand, the internal face T2i and the radial face T2r of the second fiber blank T2, and on the other hand, the internal face T3i of the third fiber blank T3. In the example of Figure 11, the internal faces T2i, T3i can extend longitudinally along the axis A, and the radial face T2i can extend radially outwards relative to this axis A. These internal faces T2i, T3i and radial T2 r are each configured to receive the draping of step (b4).

[0156] In particular, the U-shape of the second fiber blank T2 can be produced by draping the radial surfaces 310a, 310b and internal surfaces 310c of the metal insert with the second plies of composite material. This makes it possible to form the first and second annular arms P22, P24 and the bottom P202 (in particular after step (c)).

[0157] The L-shape in axial section of the third fiber blank T3 can be produced by draping the internal Oi and lateral Oi surfaces of the tool O with the third plies of composite material. This makes it possible to form, in particular simultaneously, on the one hand, the cylindrical part P300 (in particular after step (c)), and on the other hand, the annular leg P30 (in particular after step (c)).

[0158] The L-shape in axial section of the first fiber blank T1 can be produced by draping, in particular simultaneously, the internal faces of the second and third fiber blanks T2, T3 with the first plies of composite material. This makes it possible to simultaneously form, on the one hand, the cylindrical portion P100 and the end portion (in particular after step (c)), and on the other hand, the annular tab P10 (in particular after step (c)).

[0159] The draping step (b), in particular steps (bi), (b2) and (b4), can be carried out manually or automatically with a suitable machine. For example, automated draping can be carried out using one of the AFP, ATL and P&P techniques.

[0160] As described above, the first, second, and third composite material plies may each comprise glass fibers, carbon fibers, aramid fibers, polyamide fibers, ceramic fibers (such as silicon carbide, glass, or aramid), metal fibers, oxide fibers, or a mixture of at least two of these fibers.

[0161] Step (c) makes it possible to co-mold (and also to co-inject when the composite material plies are dry, i.e. without being pre-impregnated with resin) the fiber blank(s) T1, T2, T3 directly onto the metal insert (possibly with the interface layer 308) in a single step and curing cycle (i.e. by co-curing). By “co-molding” or “co-injecting” is meant a single step for molding several parts or injecting a material simultaneously in the manufacturing process.

[0162] Step (c) may comprise a polymerization of the fiber blank(s) T1, T2, T3 with a resin and the transformation of this resin into a matrix by a heat treatment (or so-called other heating) of the co-firing. In this way, the resin hardens by securing the fiber preform(s) P1, P2, P3 formed with the metal insert 310.

[0163] The resin may be injected in step (c), in particular into a manufacturing mold, to polymerize and harden the fiber blank(s) T1, T2, T3 into the corresponding fiber preform(s) P1, P2, P3. Alternatively, the composite material plies making up the fiber blank(s) T1, T2, T3 may be previously impregnated with the resin, for example before the draping step (b).

[0164] As described above, the resin may be in a thermosetting or thermoplastic material, for example based on epoxy, polyepoxide, polyimide, polybismaleimide, polyurethane, polyester or vinylester.

[0165] The manufacturing method may comprise, before step (b), a step (i) of depositing the interface layer 308 at least in part on at least one of the internal 310c and radial 310a, 310b surfaces of the metal insert 310. By way of example, this interface layer 308 may be deposited so as to at least in part cover the internal surface 310c and the second radial surface 310b (figure 5b), and possibly the first radial surface 310a (figure 6).

[0166] As previously described, the interface layer 308 may be made of an elastomer.

Claims

CLAIMS 1. Annular ferrule (30) for an annular casing (3) of an aircraft propulsion assembly (10), the annular ferrule (30) comprising an annular body (300) which extends around an axis (A) and which is made of composite material, the annular ferrule (30) comprising an axial end (302) having an annular rim (304) projecting radially outwards relative to said axis (A), the annular ferrule (30) comprising a metal insert (310) which extends around the axial end (302) and which is attached to the annular rim (304), the metal insert (310) having an annular groove (318) open radially outwards relative to said axis (A), characterized in that the annular body (300) and the annular rim (304) are made from at least one fiber preform (P1, P2, P3) annular obtained by draping plies of composite material at least in part on the metal insert (310) and densified by a matrix (M),so as to make the annular body (300) and the metal insert (310) integral., 2. Annular ferrule according to claim 1, characterized in that the metal insert (310) comprises first (312) and second (314) annular lateral walls and an annular bottom wall (316) which connects these first and second lateral walls (312, 314), the first and second lateral walls (312, 314) and the bottom wall (316) delimiting between them said annular groove (318).

3. Annular ferrule according to claim 1 or 2, characterized in that the annular ferrule (30) further comprises an interface layer (308) located between the metal insert (310) and said at least one fiber preform (P1, P2).

4. Annular ferrule according to any one of claims 1 to 3, characterized in that said at least one fibrous preform (P1, P2, P3) comprises a first annular fibrous preform (P1) comprising in axial section an L-shape, this first fibrous preform (P1) comprising an annular tab (P10) forming a part of said annular rim (304); and at least a part of the metal insert (310), such as the second side wall (314), forming another part of this annular rim (304).

5. Annular ferrule according to any one of claims 1 to 4, characterized in that said axial end (302) further comprises an annular rib (306) extending parallel to the annular rim (304), and at a distance from the latter, this annular rib (306) extending radially outwards relative to said axis (A), said metal insert (310) being located between this annular rib (306) and said annular rim (304).

6. Annular ferrule according to claim 5, characterized in that said at least one fiber preform (P1, P2, P3) further comprises second (P2) and third (P3) annular fiber preforms, the second fiber preform (P2) having a U-shape in axial section, first (P22) and second (P24) annular arms forming, respectively, at least one part of the annular rib (306) and at least one other part of the annular rim (304), and the third fiber preform (P3) having an L-shape in axial section and comprising an annular leg (P30) forming another part of the annular rib (306).

7. Annular casing (3) for an aircraft propulsion unit (10), comprising an annular shroud (30) according to any one of the preceding claims.

8. Aircraft propulsion assembly (10) comprising a turbomachine (1) and a nacelle (2) surrounding at least part of the turbomachine (2), characterized in that it comprises an annular shroud (30) according to any one of claims 1 to 6 or an annular casing (3) according to claim 7, the aircraft propulsion assembly (10) further comprising a connecting member (24), for example of a cover (2c) of the nacelle (2), which is fixed in the annular groove (318) of the annular shell (30).

9. Method for manufacturing an annular ferrule (30) according to any one of claims 1 to 6, characterized in that the method comprises the steps of: (a) providing the metal insert (310) and a layup tool (O) each having an annular shape, the metal insert (310) and the tool (O) each having an annular layup internal surface (310c, Oi) and furthermore at least one annular layup radial surface (310a, 310, Or) relative to the axis (A), (b) producing at least one annular fibrous blank (T1, T2, T3) by draping plies of composite material at least in part on at least one of said internal (310c) and radial (310a, 310b) surfaces of the metal insert (310) and on at least one of said internal (Oi) and radial (Or) surfaces of the tool (O), (c) densifying the at least one fibrous blank (T1, T2, T3) and the metal insert (310) with the matrix (M) by co-firing to form said at least one fibrous preform (P1, P2, P3) secured to the metal insert (310) of the annular ferrule (30).

10. Manufacturing method according to claim 9, characterized in that step (c) comprises a polymerization of said at least one fibrous blank (T1, T2, T3) with a resin and the transformation of this resin into a matrix by a heat treatment of the co-firing.

11. Manufacturing method according to claim 10, characterized in that said resin is injected into said at least one fibrous blank (T1, T2, T3) in step (c), or said at least one fibrous blank (T1, T2, T3) is previously impregnated with the resin before the draping step (b).

12. Manufacturing method according to any one of claims 9 to 11, characterized in that in step (b), the metal insert (310) and the tooling (O) are aligned axially side by side along the axis (A), then the first composite material plies are draped at least in part over said internal surfaces (310c, Oi) and one of said radial surfaces (310a, 310b) of the metal insert (310) so as to form the first fibrous blank (T1) with an L-shape in axial section.

13. Manufacturing method according to any one of claims 9 to 11, characterized in that step (b) comprises the following sub-steps consisting of: (bi) draping second plies of composite material at least in part over said internal (310c) and radial (310a, 310b) surfaces of the metal insert (310) to form the second fibrous blank (T2) with a U-shape in axial section, (b2) draping third plies of composite material at least in part over said internal (Oi) and radial (Or) surfaces of the tool (O) to form the third fiber blank (T3) with an L-shape in axial section, (bs) axially aligning side by side along the axis (A), the second and third fiber blanks (T2, T3) draped, respectively, on the metal insert (310) and the tooling (O), and (b4) draping first plies of composite material at least partly over annular internal faces (T2i, T3i) of the second and third fiber blanks (T2, T3) and a radial face (T2 r ) annular of the second fibrous blank (T2) to form the first fibrous blank (T1) with an L-shape in axial section.

14. Manufacturing method according to any one of claims 9 to 13, characterized in that before step (b), the method comprises a step (i) of depositing the interface layer (308) at least in part on at least one of said internal (310c) and radial (310a, 310b) surfaces of the metal insert (310).

15. Manufacturing method according to any one of claims 9 to 14, characterized in that the resin is in a thermosetting or thermoplastic material, for example based on epoxy, polyepoxide, polyimide, polybismaleimide, polyurethane, polyester or vinylester.

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