RING FOR A TURBOMACHINE HOUSING AND ITS MANUFACTURING PROCESS

Abstract

The invention relates to an annular ferrule (30) for an annular casing (3) of an aircraft propulsion assembly, the ferrule (30) comprising an annular body (300) extending around an axis (A) and made of composite material, the ferrule (30) having an axial end (302) having an annular rim (304) projecting radially outwards with respect to said axis, the ferrule (30) comprising a metal insert (310) extending around the axial end (302) and attached 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) obtained by draping plies of composite material at least in a portion on the metal insert (310) and densified by a matrix (M), so as to bond the body (300) and the metal insert. Figure for abbreviation: Figure 7

Description

Title of the invention: RING FOR A TURBOMACHINE HOUSING AND ITS MANUFACTURING METHOD Technical field of the invention

[0001] The present invention relates to the general field of annular housings for an aircraft propulsion assembly, and more specifically to an annular ferrule of such an annular housing and its manufacturing process. Technical background

[0002] An aircraft propulsion assembly typically comprises a turbomachine and a nacelle configured to attach around the turbomachine.

[0003] The nacelle is conventionally equipped with several hoods surrounding the turbomachine, allowing access to it in the open position. These hoods are known as the fan hood and the thrust reverser hood.

[0004] The turbomachine comprises several annular casings, such as a fan casing extended rearward by an intermediate casing. The intermediate casing is a structural element arranged between the fan casing located further upstream and nacelle cowlings located further downstream. The intermediate casing generally comprises an annular ring (known as the intermediate casing ring VCI), an internal hub, and structural arms distributed angularly and extending radially between the internal hub and the annular ring they connect.

[0005] The intermediate housing containing the VCI ferrule is conventionally a metal part machined from a single piece.

[0006] Fig. 1 illustrates a widespread example of an embodiment of the VCI annular ferrule. This annular ferrule 30 comprises an annular body 300 extending around a longitudinal axis A and made of composite material, an axial end 302, an annular rim 304 projecting radially outward from the axis A, and a metal insert 310 extending around the axial end 302. The metal insert 310 comprises first and second lateral annular walls 312, 314 connected by a bottom annular wall 316. In the example of [Fig. 1], the second lateral wall 314, which is the most downstream, forms the annular rim 304 of the annular ferrule 30. These lateral and bottom walls 312, 314, 316 define an annular groove 318. The annular groove 318 generally has a V- or U-shaped axial cross-section. This groove annular 318 is intended to receive a connecting element for the thrust reverser hood.

[0007] The cooperation between the connecting organ and the annular groove of the annular ferrule, 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 equipping the nacelle cowlings are actuated.

[0008] In the annular ferrule 30 of [Fig. 1], the metal insert 310 is attached to and fixed at the axial end 302 by screws V. This has the disadvantage of making the annular ferrule bulky and heavy. Furthermore, manufacturing and assembling such an annular ferrule can be complex.

[0009] It is also known to produce the annular body 300 and the axial end 302 with the annular rim 304 integrally from composite material, and then to attach the metal insert 310 by bonding, as illustrated in [Fig. 2]. For this purpose, the annular ferrule 300 is made from two annular fibrous preforms PI, P2 obtained by three-dimensional weaving and densified by a matrix. A first annular fibrous preform PI forms part of the axial end 302 and includes an annular tab P10 forming part of the annular rim 304; a second annular fibrous preform P2 forms the other part of the axial end 302 and includes an annular arm P20 forming part of an annular rib 306 of the annular ferrule 300. The annular tab P10 and the annular arm P20 define the annular groove 318. The metal insert 310 is bonded inside this annular groove 318.

[0010] The annular ferrule 30 of [Fig. 2] thus proposes to produce an annular body in composite material and the metal insert separately and bonded together. This solution also has the disadvantage that the manufacture and assembly of such an annular ferrule can be complex because it requires a large number of operations, many of which are not highly automated.

[0011] In these different contexts, it is advantageous to overcome the drawbacks of the prior art by proposing an annular ferrule for an annular housing of an aircraft propulsion system that is more robust and easier to manufacture and assemble. Summary of the invention

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

[0013] To this end, the invention proposes an annular ferrule for an annular casing of an aircraft propulsion assembly, the annular ferrule comprising an annular body which extends around an axis A and which is made of composite material, the annular ferrule having an axial end having an annular rim projecting radially outwards with respect to said axis A, the annular ferrule comprising a metallic insert which extends around the axial end and which is attached to the annular rim, the metallic insert having an annular groove open radially outwards with respect to said axis A.

[0014] According to the invention, the annular body and the annular rim are made from at least one annular fibrous preform obtained by draping folds of composite material at least partly over the metal insert and densified by a matrix, so as to make the annular body and the metal insert bonded.

[0015] This solution makes it possible to achieve the aforementioned objective. For this purpose, the invention proposes to link (and also to form) the annular body made of composite material and the metal insert in a monobloc manner (or in other words, in one piece and in one piece) and to eliminate mechanical fastening means (such as screws or glue).

[0016] This one-piece connection (made, for example, by draping) is simple to implement (particularly in an automated manner), robust, and difficult to damage during operation. In particular, the annular ferrule according to the invention proposes to simultaneously form the annular body and the annular rim in composite material by draping, at least partially, directly onto the metal insert. The one-piece connection also makes it possible to form the annular ferrule (particularly the annular rim) more robust to the mechanical stresses exerted, for example, by the propulsion assembly cowlings. This significantly improves the mechanical strength of this annular ferrule.

[0017] Furthermore, the invention makes it possible to reduce the number of additional parts (such as screws, nuts, bolts, bonding interfaces between the annular body in composite material and the metal insert) to make the annular ferrule less massive and less bulky.

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

[0019] The term "draping" refers to the stacking and layering of several layers / plies of composite material (for example, in the form of strips or ribbons). The composite material generally comprises fibers.

[0020] Two pieces or parts "formed from a single piece" or "monoblocs" means that these two pieces or parts are physically connected to each other and cannot be separated without damaging them.

[0021] The annular ferrule according to the invention may comprise one or more of the following features, taken individually or in combination with each other:

[0022] - the metal insert comprises first and second lateral annular walls and an annular bottom wall which connects these first and second lateral walls, the first and second lateral walls and the bottom wall delimiting between them said annular groove;

[0023] - the annular ferrule further comprises an interface layer located between the insert metallic and said at least one fibrous preform;

[0024] - said at least one fibrous preform comprises a first fibrous preform annular having in axial section an L-shaped form, this first fibrous preform having an annular tab forming part of said annular rim; and at least part of the metallic insert, such as the second lateral wall, forming another part of this annular rim;

[0025] - said axial end further comprises an annular rib extending parallel attached to the annular rim, and at a distance from the latter, this annular rib extending radially outwards with respect to said axis A, said metallic insert being situated between this annular rib and said annular rim;

[0026] - said at least one fibrous preform further comprises second and third annular fibrous preforms, the second fibrous preform having in axial section a U-shaped form, with first and second annular arms forming, respectively, at least part of the annular rib and at least part of the annular rim, and the third fibrous preform having in axial section an L-shaped form and having an annular leg forming another part of the annular rib;

[0027] — the metallic insert has a U, V or T shape in axial section;

[0028] — the metallic insert is annular and extends around the axis A;

[0029] — the metal insert is divided into several metal insert sectors;

[0030] — the metal insert sectors are connected to each other by a joint, so as to form the annular-shaped metal insert;

[0031] — the metal insert comprises between one and six metal insert sectors;

[0032] — the metallic insert sector has an angular range between 60° and 360°;

[0033] — the fibrous preform comprises carbon fibers, ceramic fibers (such as silicon carbide, glass, or aramid), polyamide fibers, metallic fibers, oxide fibers, or a mixture of at least two of these fibers;

[0034] — the metal insert is made of aluminium, steel or titanium;

[0035] — the annular ferrule further comprises at least one annular cavity between the insert metallic and at least one fibrous preform, this annular cavity being filled with a filling material, such as a resin.

[0036] The invention also relates to an annular housing for a propulsion assembly aircraft, comprising an annular ferrule according to the invention.

[0037] The annular housing can be an intermediate housing of the aircraft propulsion assembly.

[0038] 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 includes an annular ferrule according to one of the features of the invention or an annular casing according to the invention, this propulsion assembly further comprising a connecting element, for example for a nacelle cover, which is fixed in the annular groove of the annular ferrule.

[0039] The invention further relates to a method for manufacturing an annular ferrule according to one of the features of the invention. The method comprises the steps of: (a) providing the metal insert and a draping tool, each having an annular shape, the metal insert and the tool each having an internal annular draping surface and, in addition, at least one radial annular draping surface with respect to axis A, (b) produce at least one annular fibrous blank by draping layers of composite material at least partially over at least one of said internal and radial surfaces of the metal insert and over at least one of said internal and radial surfaces of the tooling, (c) densify at least one fibrous blank and the metal insert with the matrix by co-cooking to form said at least one fibrous preform bonded to the metal insert of the annular ferrule.

[0040] The process according to the invention simplifies and strengthens the manufacturing of the annular ferrule. To this end, one or more annular fibrous preforms are obtained by draping layers of composite material. Then, the annular fibrous preform(s) are directly bonded to the metal insert during the densification and co-curing step to form the annular ferrule of the invention.

[0041] Furthermore, this process is suitable for automated (e.g., by a suitable machine) or manual manufacturing of the annular ferrule. In particular, the draping can be carried out manually or automatically, for example according to the AFP (Automated Fiber Laying) technique, the ATL (Automated Tape Laying) technique, or the P&P (Pick & Place) technique.

[0042] In this application, "fibrous rough" means a fibrous texture obtained by draping layers of composite material and intended to form at least part of the part to be produced before the densification step.

[0043] By "fibrous preform" is meant a fibrous texture intended to form at least part of the part to be produced after the densification step. The fibrous preform is thus formed from a blank which is densified (and therefore embedded) in a resin.

[0044] The term "co-cooking" means the simultaneous cooking (in particular by heat treatment or in other words by heating) of the metallic insert (made separately) and the annular fibrous blank(s) (which are draped at least in part over this metallic insert) to form a single piece subjected to cooking.

[0045] In the present application, the term "baking" shall be understood as baking in the literal sense, for example for materials such as epoxy resins which must be baked, or consolidation, for example for materials such as thermoplastic resins which require consolidation.

[0046] The manufacturing process according to the invention may include one or more of the following features, taken individually or in combination with each other:

[0047] - 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-baking heat treatment;

[0048] - said resin is injected into said at least one fibrous blank in step (c), or said at least one fibrous blank is pre-impregnated with the resin before step (b) of draping;

[0049] - in step (b), the metal insert and the tooling are axially aligned side by side. along axis A, then the first layers 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 rough with an L-shaped axial section;

[0050] - step (b) comprises the following substeps consisting of: (bl) drape second layers of composite material at least partially over said internal and radial surfaces of the metallic insert to form the second fibrous blank with an axial U-shaped shape, (b2) drape third layers of composite material at least partially over said internal and radial surfaces of the tooling to form the third fibrous blank with an L-shaped axial section, (b3) align axially side by side along axis A, the second and third draped fibrous blanks, respectively, on the metal insert and the tooling, and (b4) drape the first plies of composite material at least in part over annular internal 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-shaped axial section;

[0051] - before step (b), the process includes a step (i) of depositing the layer interface at least in part on at least one of said internal and radial surfaces of the metallic insert;

[0052] - the resin is in a thermosetting or thermoplastic material, for example in epoxy, polyepoxide, polyimide, polybismaleimide, polyurethane, polyester or vinyl ester base;

[0053] — the draping step (b) is carried out manually or automatically with a suitable machine;

[0054] — the composite material plies each comprise glass fibers, fibers carbon, aramid fibers, polyamide fibers, ceramic fibers (such as silicon carbide, glass, or aramid), metallic fibers, oxide fibers, or a mixture of at least two of these fibers. Brief description of the figures

[0055] The invention will be better understood and other details, features and advantages of the invention will become more apparent from the reading of the following description given by way of non-limiting example and with reference to the accompanying drawings in which: - [Fig. 1] is a schematic half axial cross-sectional view 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; - [Fig.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 glued to an annular body of composite material obtained by three-dimensional weaving of threads; - [Fig.3] is a schematic half view in axial section of an aircraft propulsion assembly according to the invention; - [Fig.4] is a schematic perspective view of an annular casing of a turbomachine from the aircraft propulsion assembly of [Fig.3]; - [Fig.5a] is a schematic half view in axial section of a first example of an annular ferrule of the annular housing of [Fig.4] and a linking element of the aircraft propulsion assembly; - [Fig.5b] is a schematic half view in axial section of a variant of the annular ferrule of [Fig.5a]; - [Fig.6] is a schematic half view in axial section of a second example of an annular ferrule of the annular housing of [Fig.4]; - [Fig.7] is a schematic half view in axial section of a third example of an annular ferrule of the annular housing of [Fig.4]; - [Fig.8] is a schematic half view in axial section of a fourth example of an annular ferrule of the annular housing of [Fig.4]; - Figure 9 is a block diagram of a manufacturing process for the annular ferrule of the invention, - [Fig. 10] schematically represents a first example of the realization of a fibrous preform by draping folds of composite material on the metal insert to obtain the annular ferrule of [Fig. 5a]; - [Fig. 11] schematically represents a second example of the production of several fibrous preforms by draping layers of composite material over the metal insert to obtain the annular ferrule of [Fig. 6].

[0056] Elements having the same functions in the different implementations have the same references in the figures. Detailed description of the invention

[0057] By convention, in the following description, the terms "longitudinal" and "axial" refer to the orientation of structural elements extending along a longitudinal axis (such as that of an aircraft propulsion system). The terms "radial" or "vertical" refer to the orientation of structural elements extending in a direction perpendicular to the longitudinal axis. The terms "inner" and "outer," and "internal" and "external," are used with reference to 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 with respect to the direction of gas flow in the aircraft propulsion system.

[0058] Figures 1 and 2 have been described in the technical background of this application, and they illustrate examples of an annular ferrule according to the prior art, for an annular housing of an aircraft propulsion assembly.

[0059] The invention applies generally and not limited to an aircraft propulsion assembly 10, illustrated for example in [Fig.3].

[0060] This aircraft propulsion assembly 10 comprises a turbomachine 1 and a nacelle 2 surrounding at least a part of the turbomachine 1.

[0061] The aircraft propulsion assembly 10 can extend along a longitudinal axis X.

[0062] The nacelle 2 can extend along a longitudinal axis which can correspond to the axis X. The nacelle 2 may include one or more hoods. Each hood of nacelle 2 may be a single-piece hood of annular shape or half-hoods of hemispherical shape that are hinged together.

[0063] With reference to [Fig. 3], the nacelle 2 comprises, from upstream to downstream in the direction F of gas flow, an annular air inlet structure 2a, a blower hood 2b and a thrust reverser cover 2c.

[0064] The thrust reverser hood 2c can delimit an annular channel 20 of secondary airflow F2, by means of internal annular skins 21 and external annular skins 22. In particular, the external skin 22 can be formed by the thrust reverser hood 2c and the internal skin 21 can be formed by an annular casing (such as that of an intermediate casing 3 of the turbomachine 1).

[0065] 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).

[0066] The turbomachine 1 generally comprises several modules including, from upstream to downstream in a direction F of gas flow, a blower la, one or more compressor stages (for example a low pressure compressor 1b and a high pressure compressor le), a combustion chamber Id, one or more turbine stages (for example, a high pressure turbine le and a low pressure turbine If), and optionally a gas exhaust nozzle.

[0067] The turbomachine 2 can be a turbofan engine. In this configuration, the fan, generally located at the front of the turbomachine 1, delivers a flow of compressed air which is separated into two concentric annular flows: a primary air flow Fl and a secondary air flow F2 extending around the primary air flow FL

[0068] The turbomachine 1 may comprise several annular housings, such as at least one of the following housings: - a blower housing 4 extending around the blower la, - the intermediate casing 3 extending over an upstream part of the rest of the turbomachine 1 (namely the low-pressure compressor 1b in the example of [Fig.3]), and - a central housing 5 extending a hub 32 of the intermediate housing 3 downstream, and to which it is connected.

[0069] This ducted type turbomachine 1 can be a turbojet or a turboprop.

[0070] Following the example of [Fig.3], the central casing 5 can extend around the compressor stage la, 1b, the combustion chamber Id, the turbine stage le, If and possibly the exhaust nozzle.

[0071] The intermediate housing 3 may include an annular ferrule 30, the hub 32 (internal with respect to the X-axis), and structural arms 34 distributed angularly and extending radially between the hub 32 and the annular ferrule 30, which they connect. The annular ferrule 30 extends around the hub 32.

[0072] With reference to [Fig.4], the annular ferrule 30 comprises: - an annular body 300 which extends around an axis A, - an axial end 302 having an annular rim 304 projecting radially outwards with respect to axis A, and - a metallic insert 310 which extends around the axial end 302 and which is attached to the annular rim 304.

[0073] The axis A can extend longitudinally and can correspond substantially to the longitudinal axis X of the aircraft propulsion assembly 10.

[0074] The annular ferrule 30 may also include a radial flange 301 for fixing, for example, to the blower housing 4. This radial flange 301 may be annular in shape and located opposite the axial end 302.

[0075] As shown in [Fig.4], the annular body 300 forming the basic structural part of the annular ferrule 30 comprises, from upstream to downstream (with respect to the direction F of gas flow), the radial flange 301, a ferrule shaft 300a of cylindrical shape and circular cross-section, the axial end 302 and the annular rim 304. The radial flange 301, the ferrule shaft 300a, and the axial end 302 with the annular rim 304 can be one piece.

[0076] The annular body 300 is made of composite material. Thus, the ferrule shaft 300a, the axial end 302 with the annular rim 304, and optionally the radial flange 301, can be made of composite material.

[0077] The metal insert 310 includes an annular groove 318 open radially outwards with respect to the axis A. The annular groove 318 may have in axial section a general U or V shape. This annular groove 318 may be configured to receive a linking member 24 of the aircraft propulsion assembly 10 (such as one of the nacelle hoods 2 and in particular the thrust reverser hood 2c).

[0078] Examples of this metal insert 310 are illustrated in a non-limiting way in [Fig.5a] to 8.

[0079] Advantageously, the metal insert 310 can be annular and extend around the axis A (in particular on and around the axial end 302). The metal insert 310 can be either formed in one piece and in one piece, or divided into several metal insert sectors.

[0080] For example, the metal insert 310 may comprise between one and six metal insert sectors. Preferably, the metal insert 310 may be formed of two metal insert sectors.

[0081] The metal insert sector can have an angular range (with respect to axis A) between 60° and 360°. Thus, the angular range can be 360° when the metal insert 310 is formed from a single annular metal insert sector. The angular range can be 180° when the metal insert 310 is formed from two metal insert sectors. The angular range can be 60°. when the metal insert 310 is formed of six metal insert sectors. The metal insert 310 can be made of aluminum, steel or titanium.

[0082] The metal insert 310 may have in axial section a U shape, a V shape (as illustrated in Figures 5a to 7), a T shape (as illustrated in [Fig.8]) or any other so-called hollow shape capable of accommodating (or otherwise said complementary) to the shape in particular of the axial end 302 of the annular ferrule.

[0083] This metal insert 310 may include first and second annular side walls 312, 314 and a bottom annular wall 316. This bottom wall 316 connects the first and second side walls 312, 314. The first and second side walls 312, 314 extend radially outwards from axis A, as shown in [Fig. 5a]. The bottom wall 316 may extend axially along axis A. The first and second side walls 312, 314 and the bottom wall 316 define the annular groove 318.

[0084] The first and second side walls 312, 314 and the bottom wall 316 can be formed from a single piece (i.e. from material).

[0085] The sectorized metal insert 310 may include a seal 319 for connecting the metal insert sectors together. The seal 319 may be a silicone adhesive. By way of example, the seal 319 may be disposed in the annular groove 318, in particular on and around the bottom annular wall 316 of the metal insert sectors.

[0086] The metal insert 310 (in particular the bottom wall 316) may include an internal annular surface 310c (with respect to axis A). The metal insert 310 (in particular each of the first and second side walls 312, 314) may include first and second radial annular surfaces 310a, 310b (with respect to axis A). These radial surfaces 310a, 310b and internal surface 310c are preferably located away from the annular groove 318.

[0087] The second side wall 314 (in particular the second radial surface 310b) can be attached to the annular rim 304 and / or can correspond to a part of this annular rim 304. In this way, the annular rim 304 is reinforced to support the mechanical stresses exerted by the hoods of the nacelle 2 in operation.

[0088] The bottom wall 316 (in particular the internal surface 310c) can extend around at least a part of the axial end 302.

[0089] Following the example of [Fig. 5a] and without limitation, the first lateral wall 312 may have a first diameter D3i2 smaller than a second diameter D3i4 of the second lateral wall 314. According to a variant not illustrated in the figures, the first diameter D3i2 may be equal to the second diameter D3i4. The first and second diameters D3i2, D3i4 are measured along a plane perpendicular to the axis A.

[0090] 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 fibrous preform PI, P2, P3. This or these fibrous preforms PI, P2, P3 are obtained by draping layers of composite material (hereafter simplified as "draping") at least in part over 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 monoblocs and formed in one piece.

[0091] The fibrous preform(s) PI, P2, P3 may each include in axial section a U or L shape. The dimensions (axial length, radial height, etc.) of the U and L shapes of the fibrous preforms PI, P2, P3 may vary according to the different embodiments of the invention described below.

[0092] The annular ferrule 30 may further include an interface layer 308 located between the metal insert 310 and the fibrous preform PI, P2. This interface layer 308 may extend annularially around the axis A. The interface layer 308 may be made of elastomer. The interface layer 308 accommodates differential expansions, particularly thermal ones, between the metal insert 310 and the fibrous preform PI, P2. These differential expansions may occur during manufacturing (for example, during a resin injection step into a mold) or during operation. The interface layer 308 also protects the annular body 300 and the annular rim 304, made of composite material, from potential galvanic corrosion, particularly when the metal insert 310 is made of aluminum.

[0093] The composite material plies of the fibrous preform(s) PI, P2, P3 may include glass fibers, carbon fibers, aramid fibers, polyamide fibers, ceramic fibers (such as silicon carbide, glass, or aramid), metallic fibers, oxide fibers, or a mixture of at least two of these fibers.

[0094] The present application will now describe the different possible configurations of the annular ferrule 30 of the invention, and in particular of the fibrous preform(s) PI, P2, P3, with reference to Figures 5a to 8.

[0095] 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 fibrous preform PL. This first fibrous preform PI can have a general L-shaped axial cross-section. The first fibrous preform PI can have an axial length LPi measured along axis A.

[0096] The first fibrous preform PI may include a cylindrical portion P100 of circular cross-section which extends along the axis A and which is intended to form at least a part of the annular body 300 (such as the ferrule shaft 300a and possibly the radial flange 301 and axial end 302).

[0097] The cylindrical portion P100 may include an annular end portion P102 intended to form at least part of the axial end 302. In the example of Figures 5a and 5b, the end portion P102 may form at least part 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.

[0098] The first fibrous preform PI may include an annular tab P10. The annular tab P10 may extend radially outward from the axis A in the example. In particular, this annular tab P10 may be attached to the second side wall 314 (specifically at the second side surface 310b). This annular tab P10 is intended to form part of the annular rim 304 of the annular ferrule 30, and the metal insert (specifically the second side wall 314) forms another part of this annular rim 304. Thus, the annular tab P10 and the second side wall 314 together can form the annular rim 304.

[0099] The annular leg P10 may have a third diameter DPi0 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 DPi0 is similar to the second diameter D3i4 of the second side wall 314. In an alternative not shown in the figures, the third diameter DPi0 may be smaller than the second diameter D3i4 of the second side wall 314. According to another alternative, the third diameter DPi0 may be similar to the first diameter D3[2 of the first side wall 312.

[0100] The first fibrous preform PI can therefore be monobloc and formed in one piece with the metallic insert 310.

[0101] With reference to [Fig. 5b], the annular ferrule 30 of the first embodiment may comprise the interface layer 308 between at least a portion of the first fibrous preform PI 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 fibrous preform PI (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.

[0102] In the annular ferrule 30 of the first embodiment, the metal insert 310 has in axial section substantially a general U-shaped form. As for the annular groove 318, it has in axial section substantially a general V-shaped form.

[0103] 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 a rib. additional annular 306 and the presence of several additional fibrous preforms P2, P3 to form the annular body 300 and the annular rim 304.

[0104] 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 extends radially outwards with respect 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 fibrous preform P2) and the annular rim 304 (in particular a second annular arm P24 of the second fibrous preform P2). Thus, the annular rib 306 can be attached to the first lateral wall 312 (in particular on the first radial surface 310a), and the annular rim 304 can be attached to the second lateral wall 314 (in particular on the second radial surface 310b).

[0105] 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 the same ([Fig. 6]) or smaller than the first diameter D302. The fifth diameter D304 may be the same ([Fig. 6]) or smaller than the second diameter D304. The fourth D306 and fifth D304 diameters are measured along a plane perpendicular to the axis A.

[0106] Furthermore, the annular body 300 and the annular rim 304 of the second embodiment can be made from the first fibrous preform PI (as described above with reference to Figures 5a and 5b) and also from a second annular fibrous preform P2 and a third annular fibrous preform P3.

[0107] The first fibrous preform PI 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 fibrous preforms PI, P2 can extend, on the one hand, axially side by side (or in other words, joined to each other), and on the other hand, radially around the first fibrous preform PI (in particular the cylindrical portion P100 and possibly the end portion P102 for the second fibrous preform P2).

[0108] The second fibrous preform P2 may have a general U-shaped axial cross-section. This second fibrous preform P2 may have a second axial length LP2 measured along axis A. This second axial length LP2 may be less than the first axial length Lpl

[0109] The second fibrous preform P2 may include the first P22 and second P24 annular arms intended to form, respectively, at least a part of the annular rib 306 and at least a part of the annular rim 304.

[0110] The first and second annular arms P22, P24 can each extend radially outwards with respect to axis A. The first annular arm P22 can be attached to the first lateral wall 312 (in particular on the first surface radial 310a). The second annular arm P24 can be attached to the second lateral wall 314 (in particular on the second radial surface 310b).

[0111] 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 D3[2 may be the same ([Fig.6]) or smaller than the sixth diameter DP22. The second diameter D3i4 may be the same ([Fig.6]) or smaller than the seventh diameter DP24.

[0112] The second fibrous preform P2 may further comprise a base P202 connecting the first and second annular arms P22, P24 to each other. This base P202 may extend axially along the axis A. The base P202 may be intended to form at least a portion of the axial end 302 of the annular ferrule 30, the other portion of the axial end 302 being formed by the end portion P102 of the first fibrous preform PL

[0113] Advantageously, the metal insert 310 can be covered at least partially by the second fibrous preform P2. In particular, the second fibrous preform P2 (via the first and second annular arms P22, P24 and the bottom P202) covers the radial surfaces 310a, 310b and internal 310c of the metal insert 310.

[0114] The third fibrous preform P3 may have a general L-shaped axial section. This third fibrous preform P3 may have a third axial length LP3 measured along axis A. This third axial length LP3 may be less than the first axial length LP1. The third axial length LP3 may be greater than the second axial length LP2.

[0115] The third fibrous preform P3 may include a cylindrical portion P300 of circular cross-section extending along axis A and intended to form at least one other part of the annular body 300 (such as the ferrule shaft 300a and optionally the radial flange 301). This cylindrical portion P300 may extend at least partially around the cylindrical portion P100.

[0116] The third fibrous preform P3 may include an annular leg P30. The annular leg P30 may extend radially outwards from axis A, as in [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 part of the annular rib 306 of the annular ferrule 30. In this configuration, the first annular arm P22 (optionally with the first side wall 312) forms one part of the annular rib 306, and the annular leg P30 forms the other part of this annular rib 306.

[0117] The annular leg P30 may have an eighth diameter DP30 which is measured along a plane perpendicular to the axis A (or the axis X). In the example of [Fig.6], the eighth diameter DP30 is similar to the first and sixth diameters D3[2, DP22.

[0118] The first, second and third fibrous preforms PI, P2, P3 can therefore be monoblocs and formed in one piece with the metallic insert 310.

[0119] Following the example of [Fig. 6] and without limitation, the annular ferrule 30 of the second embodiment may comprise the interface layer 308 between at least a portion of the second fibrous preform P2 and the metal insert 310. This interface layer 308 may be formed between: - the bottom wall 316 and the bottom P202 of the second fibrous preform P2, - the first lateral wall 312 and the first annular arm P20 of the second fibrous preform P2, and - the second lateral wall 314 and the second annular arm P24 of the second fibrous preform P2.

[0120] Thus, the interface layer 308 can be intercalated 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 fibrous preform P2.

[0121] Figure 7 illustrates a third embodiment of the annular ferrule 30 which differs from the annular ferrule 30 of the second embodiment by the metallic insert 310.

[0122] Indeed, the metal insert 310 of the third embodiment may have one of the first and second side walls 312, 314 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 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 vinyl ester.

[0123] Following the example of [Fig. 7] and without limitation, the first lateral wall 312 is inclined with respect to the first annular arm P22. This first lateral wall 312 may thus comprise a first radial end 312a extending radially outwards (with respect to 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.

[0124] 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 T shape in axial section.

[0125] This metallic insert 310 of [Fig. 8] comprises the first and second lateral annular walls 312, 314, the bottom annular wall 316 (as described below) above) and an axial leg 317. This axial leg 317 may be an axial extension of the bottom annular wall 316. The axial leg 317 may extend between a first end and a second end opposite the first end. The first end may be connected to the bottom annular wall 316 and to the second lateral annular wall 314. The second end may be free. At least a portion of the axial leg 317 (in particular the second end) may be thickened.

[0126] In this example of [Fig. 8], the first lateral annular wall 302 can be attached to the annular rim 304 of the annular body 300. In an alternative not shown in the figures, the second lateral annular wall 314 can be attached to the annular rim 304 and the axial tab 317 can be connected to the first lateral annular wall 312 and to the bottom annular wall 316. According to another alternative not shown, the annular rim 304 is optional and can be absent from the annular ferrule 30 when the metal insert 310 has a T-shaped axial cross-section.

[0127] Furthermore, the metal insert 310 of [Fig. 8] is sectored and therefore includes the gasket 319 for connecting the metal insert sectors to form an annular piece. This gasket 319 is located at the axial tab 317. In particular, the gasket 319 may be in the form of an annular strip to which the axial tabs 317 of the metal insert sectors are bonded.

[0128] As described with reference to the first embodiment of the annular ferrule, the annular body 300 according to the example in [Fig. 8] can be produced from the first annular fibrous preform PL

[0129] The present application now describes a method for manufacturing the annular ferrule 30 of the invention, successive steps of which are summarized, for example, in [Fig. 9]. Optional steps are shown in dashed lines.

[0130] According to the invention, the process comprises the following steps consisting of: (a) providing the metal insert 310 and a draping tool O, (b) producing at least one fibrous blank T1, T2, T3 by draping plies of composite material at least partly over the metal insert 310 and at least partly over the tool O, (c) densify this at least one fibrous blank T1, T2, T3 and the metal insert 310 with the matrix M by co-cooking to produce at least one fibrous preform PI, P2, P3 bonded to the metal insert 310 of the annular ferrule 30.

[0131] In step (a), the metal insert 10 can be formed in one piece or divided into sections. The metal insert sections can be connected together, in particular by the joint 319, so as to form an annular piece.

[0132] The metal insert 310 and the tooling O can therefore each have an annular shape.

[0133] The tooling O has an internal annular surface O; and an annular surface lateral Oi, each configured to receive the draping of the step (b). This lateral surface Oi extends radially outwards (relative to 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 draping of the step (b).

[0134] 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.

[0135] The draping step (b) can be carried out in different ways.

[0136] Figure 10 illustrates a first example of an 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 partially over the internal surface Oi of the tooling and over at least one of the internal 310c and radial surfaces 310a, 310b of the metal insert 310 to form a first annular fibrous blank Tl with an L-shaped axial cross-section. This first fibrous blank Tl is intended to form the first fibrous preform PI (in particular after step (c)).

[0137] In particular, the L-shaped axial section of the first fibrous blank T1 can be achieved by draping the internal surfaces O1, 310c and the second radial surface 310b with the first plies of composite material. Thus, draping the internal surfaces O1, 310c allows the cylindrical portion P100 and the end portion P102 to be formed (especially after the densification step (c)) and draping the second radial surface 310b allows the annular tab P10 to be formed (especially after the step (c)).

[0138] Figure 11 illustrates a second example of implementation of step (b), which may include the following substeps: (bi) draping second plies of composite material at least partly over the internal 310c and radial 310a, 310b surfaces of the metal insert 310 to form a second annular fibrous blank T2 with an axial U-shaped shape and intended to form the second fibrous preform P2 (in particular after step (c)), (b2) drape third layers of composite material at least partly over the internal O and lateral Oi surfaces of the tooling O to form a third annular fibrous blank T3 with an L-shaped axial section and intended to form the third fibrous preform P3 (particularly after step (c)), (b3) align axially side by side along axis A, the second and third fiber blanks T2, T3 draped, respectively, on the metal insert 310 and the tooling O, and (b4) drape the first plies of composite material at least in part over internal annular faces T2i5 T3; of the second and third fibrous blanks T2, T3 and a radial annular face T2r of the second fibrous blank T2 to form the first fibrous blank Tl with an axial section in the shape of L.

[0139] Step (b3) allows the second and third fiber blanks T2, T3 to be assembled and aligned along axis A to form, on the one hand, the inner face T2; and the radial face T2r of the second fiber blank T2, and on the other hand, the inner face T3; of the third fiber blank T3. In the example of [Fig. 11], the inner faces T2; , T3i can extend longitudinally along axis A, and the radial face T2; can extend radially outwards with respect to this axis A. These inner faces T2; , T3i and radial face T2r are each configured to receive the draping of step (b4).

[0140] In particular, the U-shaped form of the second fibrous blank T2 can be produced by draping the radial surfaces 310a, 310b and internal 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 (particularly after step (c)).

[0141] The L-shaped axial section of the third fiber blank T3 can be produced by draping the internal O and lateral Oi surfaces of the tooling O with the third layers of composite material. This makes it possible to form, in particular simultaneously, on the one hand, the cylindrical part P300 (particularly after step (c)), and on the other hand, the annular leg P30 (particularly after step (c)).

[0142] The L-shaped axial cross-section of the first fiber blank T1 can be produced by simultaneously draping the inner faces of the second and third fiber blanks T2, T3 with the first plies of composite material. This allows the simultaneous formation of, on the one hand, the cylindrical portion P100 and the end portion (particularly after step (c)), and on the other hand, the annular tab P10 (particularly after step (c)).

[0143] The draping step (b), in particular steps (bj, (b2) and (b4), can be carried out manually or automatically with a suitable machine. By way of example, automated draping can be carried out according to one of the AFP, ATL and P&P techniques.

[0144] As described above, the first, second and third plies of composite material may each comprise glass fibers, carbon fibers, aramid fibers, polyamide fibers, ceramic fibers (such as silicon carbide, glass, or aramid), metallic fibers, oxide fibers, or a mixture of at least two of these fibers.

[0145] Step (c) allows co-molding (and also co-injection when the composite material plies are dry, i.e., without being pre-impregnated with resin) of the fibrous blank(s) T1, T2, T3 directly onto the metal insert (optionally with the interface layer 308) in a single step and cooking cycle (i.e. by co-cooking).

[0146] The term “co-molding” or “co-injecting” refers to a single step for molding several parts or injecting a material simultaneously in the manufacturing process.

[0147] Step (c) may include polymerizing the fibrous blank(s) T1, T2, T3 with a resin and transforming this resin into a matrix by a heat treatment (or other heating) of the co-curing method. In this way, the resin hardens, bonding the formed fibrous preform(s) PI, P2, P3 with the metal insert 310.

[0148] The resin can be injected in step (c), in particular into a manufacturing mold, to polymerize and harden the fibrous blank(s) T1, T2, T3 into the corresponding fibrous preform(s) PI, P2, P3. Alternatively, the composite material plies composing the fibrous blank(s) T1, T2, T3 can be pre-impregnated with the resin, for example before the draping step (b).

[0149] As described above, the resin may be in a thermosetting or thermoplastic material, for example based on epoxy, polyepoxide, polyimide, polybis-maleimide, polyurethane, polyester or vinylester.

[0150] The manufacturing process may include, before step (b), a step (i) of depositing the interface layer 308 at least partially 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 cover at least partially the internal surface 310c and the second radial surface 310b ([Fig.5b]), and optionally the first radial surface 310a ([Fig.6]).

[0151] As described above, the interface layer 308 can be made of elastomer.

Claims

Claims

1. Annular ferrule (30) for an annular casing (3) of an aircraft propulsion unit (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 annular fibrous preform (PI, P2, P3) 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 (PI, P2).

4. Annular ferrule according to any one of claims 1 to 3, characterized in that said at least one fiber preform (PI, P2, P3) comprises a first annular fiber preform (PI) having an L-shape in axial section, this first fiber preform (PI) having an annular tab (P 10) 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. An annular ferrule according to any one of claims 1 to 4, ca- 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 a portion 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 a cover (2c) of the nacelle (2), which is fixed in the annular groove (318) of the annular shroud (30).

9. A method of 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 lay-up tool (O) each having an annular shape, the metal insert (310) and the tool (O) each having an annular lay-up internal surface (310c, O;) and furthermore at least one annular radial lay-up surface (310a, 310, Or) relative to the axis (A), (b) producing at least one annular fibrous blank (T1, T2, T3) by lay-up plies of composite material at least in part on at least one of said internal (310c) and radial (310a, 310b) surfaces of the insert metallic (310) and on at least one of said internal (O;) and radial (Or) surfaces of the tool (0), (c) densifying the at least one fibrous blank (Tl, T2, T3) and the metallic insert (310) with the matrix (M) by co-firing to form said at least one fibrous preform (PI, P2, P3) secured to the metallic 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 first plies of composite material 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 (Tl) 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: (bl) draping second plies of composite material at least in part on said internal (310c) and radial (310a, 310b) surfaces of the metal insert (310) to form the second fiber blank (T2)) with a U-shape in axial section, (b2) draping third plies of composite material at least in part on said internal (O;) and radial (Or) surfaces of the tool (O) to form the third fiber blank (T3) with an L-shape in axial section, (b3) 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 tool (O), and (b4) draping first plies of composite material at least partly over annular inner faces (T2;, T3i) of the second and third fibrous blanks (T2, T3) and an annular radial face (T2r) of the second fibrous blank (T2) to form the first fibrous blank (Tl) 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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