Composite spacer ring and manufacturing method thereof

Abstract

A method (200) of manufacturing a composite spacer ring for a turbine engine fan includes preparing (210) an upstream skin preform, preparing (220) a downstream skin preform, preparing (230) an insert preform, inserting (251) the insert preform between the upstream skin preform and the downstream skin preform so as to form a rotating spacer ring preform, and forming (252) the rotating spacer ring preform. And baking (260) the rotating spacer ring preform. Preparation (210) of an upstream skin preform and / or preparation (220) of a downstream skin preform includes overhang formation (212, 222) of a prepreg tow by automated fiber placement on a skin mold.

Description

Technical Field

[0001] The present invention relates to spacer rings for turbine engine fans and, more particularly, to methods of making them. Background Art

[0002] A turbine engine fan rotor typically includes a fan disk having a plurality of blades secured to the disk and extending in a generally radial direction therefrom. The disk also includes inter-blade platforms interposed between the blades to internally define a secondary flow duct. These inter-blade platforms are secured to the disk via upstream and downstream retaining flanges.

[0003] One type of downstream retaining flange is a "rotating spacer ring" or "flow path spacer". These rotating spacer rings consist of a radial collar fixed to a component integral with the disk and extending through a ring projecting axially upstream. The ring is defined by a revolution of a generally V-shaped generatrix pointing upstream. The ring comprises an inner leg defining an inwardly facing axial shoulder that abuts the inter-blade platform and an outer leg defining a generally frustoconical outer surface that internally delimits the secondary flow duct. The outer leg is extended by a hook-shaped appendage to provide a seal between the fan rotor and the turbine engine casing.

[0004] Traditionally, the rotating spacer rings have been made of metal, most commonly titanium. Recently, it has been proposed that in order to make the rotating spacer rings lighter, the rotating spacer rings should be made of composite materials using resin transfer molding technology.

[0005] However, the use of resin transfer molding to produce rotating spacer rings is not entirely satisfactory. More specifically, this method is expensive and complex to implement.

[0006] A technique for manufacturing composite preforms is also known and is called "automatic fiber placement" (AFP), in which a drape-forming machine lays down a strip consisting of a plurality of juxtaposed narrow strips (typically 3 mm to 13 mm wide) (called "tows") on a support by means of a laying head. These tows consist of fibers oriented in the direction of elongation of the tows and embedded in a matrix. These tows are introduced into the head via a feed system comprising a plurality of reels, each of which houses one of the tows to be laid. The tows are unwound from the reels and fed to the head, which heats the tows before rollers press them onto the support. The head is connected to a robot that positions the head during the drape-forming process, the entire system being controlled by a computer program that is defined according to the desired fiber arrangement in the final product. Automated fiber placement thus enables the production of composite parts in a highly reproducible manner.

[0007] In the aerospace industry, this technology is often used to produce large, simple geometric parts such as wing and fuselage elements.

[0008] However, due to limitations in roller size and tow width, automated fiber placement is generally considered unsuitable for producing small parts or parts with complex geometries, such as rotating spacer rings, as such parts require specific, non-instantaneous deposition and / or cutting strategies. Summary of the Invention

[0009] It is an object of the present invention to simplify and automate the production of rotating spacer rings in a cost-reducing manner.

[0010] To this end, according to a first aspect, an object of the present invention is a method for manufacturing a spacer ring made of composite material for a turbine engine fan, said spacer ring comprising an upstream skin, a downstream skin, and an annular insert, the upstream skin defining the upstream surface of said spacer ring when it is mounted on the turbine engine, the downstream skin defining the downstream surface of said spacer ring when it is mounted on the turbine engine, the annular insert being housed between said upstream skin and said downstream skin, said method comprising the following steps:

[0011] - Preparation of upstream skin preforms,

[0012] - Preparation of downstream skin preforms,

[0013] - preparation of an insert preform,

[0014] - inserting the insert preform between the upstream skin preform and the downstream skin preform so as to form a rotating spacer ring preform, and

[0015] - Baking of rotating spacer ring preforms,

[0016] Wherein, preparing the upstream skin preform and / or preparing the downstream skin preform includes forming prepreg tows by draping on a skin mold through automatic fiber placement.

[0017] According to a particular embodiment of the present invention, the manufacturing method further has one or more of the following features, taken alone or in any technically possible combination:

[0018] - draping a prepreg tow on a skin mold to produce an annular preform blank, preparing an upstream skin preform and / or preparing a downstream skin preform after said draping comprises: shaping the preform blank to form the upstream skin preform and / or the downstream skin preform respectively;

[0019] - the shaping of the preform blank is carried out by thermoforming;

[0020] - the skin mould has a rotationally symmetrical shape centered on the axis of revolution, a cylindrical coordinate system is associated with the skin mould so that at each point there is an axial direction parallel to the axis of revolution, a radial direction connecting the axis of revolution to said point, and a circumferential direction perpendicular to said axial and radial directions, each prepreg tow being suspended along a direction forming a non-zero angle with the local circumferential direction at each point;

[0021] - preparing an insert preform comprising: draping a prepreg tow on an insert mould by automated fibre placement, said insert mould having a disc shape, with the prepreg tow draped over the edge of said disc,

[0022] - the disk is rotationally symmetric about the central axis, a cylindrical coordinate system is associated with the insert mold so that at each point there is an axial direction parallel to the central axis, a radial direction connecting the central axis to the point, and a circumferential direction perpendicular to the axial and radial directions, and each prepreg tow is suspended substantially parallel to the circumferential direction,

[0023] -Draping the prepreg tow on the insert mold includes:

[0024] o producing at least one stack of prepreg tow layers stacked in radial direction, said stack having axial edges defined by overhanging, the axial edges defined by overhanging having an axial extension, and

[0025] o machining a machined axial edge of the stack by clean cutting of the stack, the machined axial edge being opposite to the axial edge defined by the overhanging formation;

[0026] For at least one stack, the axial edge defined by the overhang is curved and the machined axial edge is straight, or the axial edge defined by the overhang is inclined and the machined axial edge is radial.

[0027] - producing a plurality of stacks, the stacks comprising an inner stack and an outer stack radially superposed on the inner stack, the machined axial edges of the inner stack being obtained by cleanly cutting the inner stack along a primary cutting surface, and the machined axial edges of the outer stack being obtained by cleanly cutting the outer stack along a secondary cutting surface different from the primary cutting surface;

[0028] - the axial edge of the outer stack defined by the overhang radially extends the machined axial edge of the inner stack, and the secondary cutting surface radially extends the axial edge of the inner stack defined by the overhang;

[0029] - the axial edge of the outer stack defined by the overhang radially extends the axial edge of the inner stack defined by the overhang, and the secondary cutting surface radially extends the machined axial edge of the inner stack;

[0030] - The machined axial edge is obtained by cleanly cutting the stack along a radial or frustoconical cutting surface.

[0031] Another object of the invention, according to a second aspect, is a spacer ring obtained by such a method.

[0032] According to a third aspect, a further object of the present invention is a fan rotor comprising such a spacer ring.

[0033] According to a fourth aspect, another object of the invention is a turbine engine comprising such a fan rotor.

[0034] According to a fifth aspect, another object of the invention is an aircraft comprising such a turbine engine. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Other features and advantages of the present invention will appear on reading the following description, given by way of example only and with reference to the accompanying drawings, in which:

[0036] - Figure 1 is a top view of an aircraft according to an exemplary embodiment of the present invention,

[0037] - Figure 2 yes Figure 1 A simplified cross-sectional view of a turbine engine of an aircraft,

[0038] - Figure 3 yes Figure 2 View of the detail marked III,

[0039] - Figure 4 yes Figure 2 A cross-sectional view of a rotating spacer ring of a turbine engine,

[0040] - Figure 5 It is an explanation Figure 4 Schematic diagram of the manufacturing method of the rotating spacer ring,

[0041] - Figure 6 It shows Figure 5 Schematic diagram of the preparation steps of the insert preform of the manufacturing method,

[0042] - Figures 7 to 25 Shown Figure 5 The various steps and sub-steps of the manufacturing method. DETAILED DESCRIPTION

[0043] Figure 1 The illustrated aircraft 10 includes a turbine engine 12 that propels the aircraft.

[0044] In the example shown, the aircraft 10 is an airplane. The airplane conventionally includes a fuselage 14, a tail assembly 16, and two wings 18. In this case, there are two turbine engines 12, each mounted beneath a respective wing 18. In an alternative embodiment (not shown), the turbine engines 12 are positioned along the fuselage 14, for example, near the tail assembly 16. In another alternative embodiment (also not shown), the aircraft 10 includes a single turbine engine 12 or at least three turbine engines 12.

[0045] Figure 2 One of the turbine engines 12 is shown in FIG.

[0046] As can be seen in this figure, the turbine engine 12 is elongated along a longitudinal axis X. Typically, a turbine engine has an angular symmetry about said longitudinal axis X, in other words, in the case of a rotation about the longitudinal axis X, at least one angle of the turbine engine is constant.

[0047] Herein and hereinafter, the terms "inner" and "outer", "inner" and "outer" and their variations are understood to refer to an axis X, elements defined as "inner" or "inner" being oriented towards the axis X, while "outer" or "outer" elements are oriented in a direction opposite to the axis X. The term "radial" and its variations are understood to refer to a direction perpendicular to the axis X.

[0048] Conventionally, the turbine engine 12 includes a nacelle 20 , an internal duct 22 for circulating airflow through the nacelle 20 , a combustion chamber 24 housed in the duct 22 , an engine rotor 26 , and an exhaust nozzle 28 .

[0049] In the following, the terms “upstream” and “downstream” are understood to refer to the flow direction of the air stream through the duct 22 .

[0050] The engine rotor 26 includes a compressor 30, a turbine 32, and a drive shaft 34 that couples the turbine 32 to the compressor 30 to drive the compressor 30 via the turbine 32. The compressor 30 is disposed upstream of the combustion chamber 24 and supplies compressed air to the combustion chamber 24. The turbine 32 is disposed downstream of the combustion chamber 24 and receives exhaust gas leaving the combustion chamber 24.

[0051] The longitudinal axis X is the axis of rotation of the drive shaft 34 .

[0052] The drive shaft 34 is guided in rotation relative to the nacelle 20 by bearings (not shown).

[0053] In the example shown, the turbine engine 12 is a multi-rotor turbine engine, in particular a twin-rotor turbine engine, comprising a low-pressure rotor 40 in addition to the engine rotor 26. Thus, the engine rotor 26 constitutes a high-pressure rotor, the compressor 30 is a high-pressure compressor, the turbine 32 is a high-pressure turbine, and the drive shaft 34 is a high-pressure shaft.

[0054] The low-pressure rotor 40 includes a low-pressure compressor 42 , a low-pressure turbine 44 , and a low-pressure shaft 46 coupling the low-pressure turbine 44 to the low-pressure compressor 42 for driving the low-pressure compressor 42 by the low-pressure turbine 44 .

[0055] The low-pressure compressor 42 is provided upstream of the high-pressure compressor 30 and supplies compressed air to the high-pressure compressor 30. The low-pressure turbine 44 is provided downstream of the high-pressure turbine 32 and receives exhaust gas leaving the high-pressure turbine.

[0056] The low pressure shaft 46 is guided for rotation relative to the nacelle 20 by bearings (not shown).

[0057] The low-pressure shaft 46 is coaxial with the high-pressure shaft 34 . Its axis of rotation is therefore also the longitudinal axis X. In particular, the low-pressure shaft 46 extends inside the high-pressure shaft 34 .

[0058] The turbine engine 12 further comprises a fan 50 for driving the air flow in an outer circulation duct 52 surrounding the nacelle 20. Thus, a primary air flow A (hot), constituted by the portion of the air flow driven in the inner circulation duct 22, can be distinguished from a secondary air flow B (cold), constituted by the portion of the air flow driven in the outer circulation duct 52.

[0059] The fan 50 includes a fan rotor 54. The fan rotor 54 is rotatably mounted relative to the nacelle 20 about the longitudinal axis X. The fan rotor includes a disk 55 provided with fan blades 56 extending substantially radially outward from the disk 55. When these blades 56 rotate, they drive the air flow in the outer circulation duct 52.

[0060] The fan rotor 54 is rotated by the low-pressure turbine 44 via the low-pressure shaft 46. In the example shown, this drive is direct, in other words, the fan rotor 54 is constrained to rotate with the low-pressure shaft 46. In an alternative (not shown), this drive is achieved through a speed reducer 57 that enables the fan rotor 54 to rotate at a speed lower than that of the low-pressure shaft 46.

[0061] The fan rotor 54 is particularly arranged upstream of the inner circulation duct 22 and also drives the air flow in the inner circulation duct.

[0062] In the example shown, the fan 50 also includes a fan stator 58 , also called a flow straightener, comprising fixed blades 59 arranged on the periphery of the nacelle 20 in the outer circulation duct 52 along a plane perpendicular to the longitudinal axis X. This fan stator 58 is here arranged downstream of the fan rotor 54 .

[0063] The external circulation duct 52 is defined here between the nacelle 20 and a fan casing 60 surrounding the fan 50. The turbine engine 12 generally consists of a turbojet engine with a high bypass ratio, defined as the ratio of the flow rate of the secondary flow B (cold) divided by the flow rate of the main flow A (hot).

[0064] In the example shown, the turbine engine 12 also includes a booster compressor 62 located at the inlet of the inner duct 22. The booster compressor 62 includes alternating fixed blades 64 and movable blades 66, the movable blades continuously extending into the inner duct 22. The fixed blades 64 are integral with the nacelle 20. The movable blades 66 are mounted on a booster compressor shaft 68. The booster compressor shaft 68 is fixed to the disk 55 of the fan rotor 54.

[0065] Reference Figure 3 The fan rotor 54 also comprises inter-blade platforms 70 circumferentially interposed between the blades 56 and flanges 72, 74 holding said platforms 70 on the disk 55. In the example shown, the fan rotor 54 also comprises a conical flywheel 76 mounted upstream of the disk 55 and the inter-blade platforms 70.

[0066] Each inter-blade platform 70 has an outer surface 78 that internally delimits the portion of the outer duct 52 between the blades 56 .

[0067] The flanges 72 , 74 are each annular and centered on the longitudinal axis X. Like the inter-blade platforms 70 , the flanges each define a portion of the outer duct 52 at the fan 50 . The flanges include an upstream flange 72 located upstream of the inter-blade platforms 70 and a downstream flange 74 located downstream of the inter-blade platforms 70 .

[0068] Here, the upstream flange 72 is interposed between the flywheel 76 and the inter-blade platform 70. The upstream flange comprises a radial collar 80 fixed to the disk 55 and a lug 82 projecting axially downstream from said collar 80. This lug 82 has an outer surface 84 that internally delimits the portion of the outer duct 52 at the fan 50, and an inner surface 86 that abuts against an upstream end 88 of the inter-blade platform 70.

[0069] The downstream flange 74 is formed by a rotating spacer ring 90. Typically, the outer diameter of the downstream flange is between 600 mm and 1200 mm.

[0070] Reference Figure 4 The rotating spacer ring 90 includes a radial collar 92 fixed to the boost compressor shaft 68 and a ring 94 extending the collar 92 radially outward.

[0071] The collar 92 is substantially planar. The collar extends substantially in a radial plane. The collar has an inner end 96 attached to the boost compressor shaft 68 and an outer end 98 connected to the ring 94.

[0072] The ring 94 extends around the collar 92 and projects axially upstream relative to the collar 92. The ring is connected to the collar 92 by a fillet 100, the concave surface of which faces upstream. The fillet 100 typically has a radius of curvature of between 10 mm and 60 mm.

[0073] The ring 94 is defined by revolution about an axis X of a generally V-shaped generatrix directed upstream. The ring comprises an inner leg 102 and an outer leg 104 converging towards each other in an upstream direction of an upstream end 105 of the ring 94 .

[0074] The inner leg 102 defines an inwardly facing axial shoulder 106. The shoulder 106 is substantially cylindrical, i.e., the shoulder has no radial extension or at least a very small radial extension compared to its other dimensions. In particular, the shoulder is substantially cylindrical. The shoulder 106 abuts against the downstream end 108 ( Figure 2 ).

[0075] In particular, inner leg 102 extends fillet 100 upstream.

[0076] The outer leg 104 defines a generally frustoconical outer surface 110 that widens in the downstream direction and internally defines a portion of the outer duct 52. The outer leg 104 has a greater axial extension than the inner leg 102. Assuming that both legs 102, 104 have the same upstream extremity (they both terminate at the upstream end 105 of the ring 94), this means that the outer leg 104 projects downstream relative to the inner leg 102. In particular, the outer leg 104 also projects downstream relative to the collar 92.

[0077] Here, the upstream end 105 defines a radial shoulder 112 which is substantially planar and lies in a radial plane facing upstream.

[0078] The ring 94 also includes a hook-shaped appendage 114 that extends the outer leg 104 downstream. The appendage 114 is bent outward. The appendage has an upstream end 116 connected to the outer leg 104 and a free downstream end 118. The distance from the downstream end 118 to the axis X is less than or equal to the distance from the upstream end 116 to the axis X; in the example shown, the two distances are substantially equal to each other. The appendage 114 is located between the fan rotor 54 and the housing 119 ( Figure 2 ) provide a seal between.

[0079] The ring 94 also comprises a reinforcing core 120 inserted between the legs 102, 104. Said core 120 is housed between the legs 102, 104 at the bottom of the space 122, ie where it touches the upstream end 105 of the ring 94.

[0080] In particular, rotating spacer ring 90 is formed by an upstream skin 122 , a downstream skin 123 , and an annular insert 124 .

[0081] Upstream skin 122 forms the upstream portion of collar 92 and the upstream portion of fillet 100, as well as inner leg 102, upstream end 105, and outer portion of outer leg 104 of ring 94. Upstream skin 122 thus defines an upstream surface 126 of rotating spacer ring 90.

[0082] Downstream skin 123 forms the downstream portion of collar 92 and the downstream portion of fillet 100, as well as the inner portion of appendage 114 and outer leg 104 of ring 94. Downstream skin 123 also extends downstream of core 120 between inner leg 102 and outer leg 104. Downstream skin 123 thus defines a downstream surface 128 of rotating spacer ring 90.

[0083] An insert 124 is housed between the skins 122 , 123 . The insert forms the core 120 .

[0084] Skins 122, 123 and insert 124 are each formed of a composite material comprising fibers embedded in a matrix. The fibers of insert 124 are preferably oriented primarily in a circumferential direction (i.e., perpendicular to the axial and radial directions) to withstand circumferential and radial loads during rotation of fan rotor 54.

[0085] Now refer to Figures 5 to 25 A method 200 of manufacturing the rotating spacer ring 90 is described.

[0086] As in Figure 5 As can be seen in FIG, the method 200 comprises a first step 210 of preparing an upstream skin preform 300 ( Figure 18 ). This step 210 begins by draping 212 prepreg tows via automated fiber placement.

[0087] As in Figure 7 As can be seen in FIG, the prepreg tows are draped over a first upstream skin mold 302 , thereby producing an annular upstream skin preform blank 304 .

[0088] The first upstream skin mold 302 has a rotationally symmetrical shape centered about an axis of revolution (not shown). For the remainder of the description, directional terms are understood to refer to Figure 7A cylindrical coordinate system is shown in relation to the first upstream skin mold 302, wherein at each point it is possible to distinguish:

[0089] an axial direction A, which extends parallel to the axis of rotation from rear to front,

[0090] a radial direction B, perpendicular to the axial direction A, connecting the axis of revolution to said point and extending from the inside to the outside, and

[0091] A circumferential direction C, which is perpendicular to the axial direction A and the radial direction B.

[0092] The first upstream skin mold 302 has a front surface 306 with a raised outer annular edge 308. The outer annular edge 308 includes a frustoconical outer portion 310 that widens rearwardly, a substantially planar annular middle portion 312 that extends substantially in a radial plane and projects inwardly from the forward end of the outer portion 310, and an inner portion 314 that extends inwardly from the middle portion 312 and has a frustoconical shape that widens forwardly.

[0093] The prepreg tows are draped over the outer annular edge 308. In this way, they are draped over a convex surface, which is very suitable for automated fiber placement because the placement head of the draping machine cannot press the prepreg tows against a support having a concave shape when the radius of curvature of the concave shape is smaller than the radius of curvature of the placement head rollers.

[0094] In particular, each prepreg tow is draped in a direction (not shown) which forms at each point a non-zero angle, preferably between 25° and 90°, with the local circumferential direction C. In other words, the draping direction of each prepreg tow has a radial component at each point.

[0095] Preferably, the different layers of prepreg tows are draped successively so that the upstream skin preform blank 304 is formed by a stack of several layers stacked along the axial direction A. Advantageously, the orientation of the draping direction of the tows alternates from one layer to the next. For example, the draping direction of the tows in the even (respectively odd) layers is oriented substantially at 90° to the circumferential direction C, and the draping direction of the tows in the odd (respectively even) layers is oriented substantially at 30° to the circumferential direction C.

[0096] The upstream skin preform blank 304 thus comprises:

[0097] a frustoconical outer portion 316 widening towards the rear, corresponding to the outer portion of the outer leg 104 of the ring 94, and

[0098] An annular, substantially flat intermediate portion 317 protruding inwardly from the front end of the outer portion 316 , said intermediate portion 317 corresponding to the upstream end 105 of the ring 94 .

[0099] On the other hand, upstream skin preform 304 does not include a portion corresponding to inner leg 102 of ring 94, the upstream portion of fillet 100, or the upstream portion of collar 92. Instead, upstream skin preform 304 includes an inner portion 318 extending inwardly from middle portion 317, the inner portion 318 having a frustoconical shape that widens toward the front.

[0100] Thus, overhang forming 212 is followed by step 214 of shaping upstream skin preform blank 304 to form a portion corresponding to inner leg 102 of ring 94 , an upstream portion of fillet 100 , and an upstream portion of collar 92 , thereby obtaining upstream skin preform blank 300 .

[0101] This forming is accomplished, for example, by vacuum thermoforming. Figure 8 As can be seen in FIG, the upstream skin preform blank 304 is placed on a second upstream skin mold 320. The second upstream skin mold 320 has a rotationally symmetrical shape centered around an axis of revolution (not shown). For the remainder of the description, orientation terms are understood to mean Figure 8 The cylindrical coordinate system shown in relation to the second upstream skin mold 320 , in which it is possible to distinguish at each point:

[0102] an axial direction A', which is parallel to the axis of rotation and extends from rear to front,

[0103] a radial direction B′, perpendicular to the axial direction A′, connecting the axis of revolution to said point and extending from the inside to the outside, and

[0104] - a circumferential direction C', which is perpendicular to the axial direction A' and to the radial direction B'.

[0105] In a manner similar to the first upstream skin mold 302, the second upstream skin mold 320 has a front surface 322 with a raised outer annular edge 324 including a frustoconical outer portion 326 that widens rearwardly and a substantially flat annular middle portion 328 that extends substantially in a radial plane and projects inwardly from the front end of the outer portion 326. In particular, the outer portion 326 and the middle portion 328 are substantially identical, and advantageously identical, to the outer portion 310 and the middle portion 312, respectively, of the first upstream skin mold 302.

[0106] Unlike the first upstream skin mold 302, the outer annular edge 324 of the second upstream skin mold 320 does not include a frustoconical inner portion that widens forward. Instead, the outer annular edge 324 includes:

[0107] a cylindrical portion 330 extending rearwardly from the inner end of the intermediate portion 328,

[0108] a substantially flat annular inner portion 332 extending substantially in a radial plane and delimiting the inner end of the outer annular edge 324, and

[0109] An annular fillet 334 connecting the cylindrical portion 330 to the inner portion 332 .

[0110] The cylindrical portion 330 , the inner portion 332 and the annular fillet 334 together define a concave recess 336 in the front surface 322 , i.e., the surface created by the combination of these three regions 330 , 332 , 334 is recessed relative to the surface connecting the inner end of the middle portion 328 with the inner end of the outer annular edge 324 .

[0111] Thus, outer annular edge 324 has the shape of upstream skin 122 .

[0112] Advantageously, by removing the insert 338 ( Figure 7 ) A second upstream skin mold 320 is obtained from the first upstream skin mold 302 , the insert filling the groove 336 and defining the inner portion 314 of the outer annular edge 308 of the front surface 306 of the first upstream skin mold 302 .

[0113] The second upstream skin mold 320 is placed on the forming platform 340, and the upstream skin preform blank 304 is then covered by the bladder 342, preferably with a partition 344 and a drain pipe 346 inserted between the upstream skin preform blank 304 and the bladder 342. A seal is formed between the bladder 342 and the forming platform 340, and the assembly is then heated, typically to a temperature between 80° C. and 90° C., while a vacuum is simultaneously created between the bladder 342 and the forming platform 340. The bladder 342 is thus pressed against the second upstream skin mold 320 and, together with the second upstream skin mold, carries the upstream skin preform blank 304, softening due to the heat and thereby assuming the shape of the outer annular edge 324 of the upstream surface 322 of said mold 320.

[0114] Thus, an upstream skin preform 300 is obtained.

[0115] Back to Figure 5 The manufacturing method 200 further includes a second step 220 of preparing a downstream skin preform 350 ( Figure 22). The second step 220 is performed in parallel with the first step 210. Alternatively, the second step is performed after the first step 210, or even before said first step 210.

[0116] In a manner similar to the first step 210, the second step 220 begins by draping 222 prepreg tows via automated fiber placement. Figure 9 As shown, the prepreg tows are draped over a first downstream skin mold 352 to produce an annular downstream skin preform blank 354 .

[0117] The first downstream skin mold 352 has a rotationally symmetrical shape centered about an axis of revolution (not shown). For the remainder of the description, orientation terms are understood to refer to Figure 9 The cylindrical coordinate system shown in relation to the first downstream skin mold 352 , in which it is possible to distinguish at each point:

[0118] - an axial direction A", which is parallel to the axis of rotation and extends from rear to front,

[0119] a radial direction B″, which is perpendicular to the axial direction A″, connects the axis of revolution to said point and extends from the inside to the outside, and

[0120] - a circumferential direction C", which is perpendicular to the axial direction A" and to the radial direction B".

[0121] The first downstream skin mold 352 has a front surface 356 with a raised outer annular edge 358. The outer annular edge 358 includes a frustoconical outer portion 360 that widens rearwardly, a substantially planar annular middle portion 362 that extends substantially in a radial plane and projects inwardly from the forward end of the outer portion 360, and an inner portion 364 that extends inwardly from the middle portion 362 and has a frustoconical shape that widens forwardly.

[0122] The first downstream skin mold 352 also has an outer cylindrical surface 366. The diameter of the outer cylindrical surface 366 is smaller than the outer diameter of the front surface 356. A collar 367 defining a rearwardly facing shoulder 368 ensures engagement between the outer cylindrical surface 366 and the front surface 356.

[0123] The prepreg tows are overhung on the outer annular edge 358 and the front end section 370 of the outer cylindrical surface 366. Thus, the prepreg tows are essentially overhung on a convex surface, which, as we have seen, is very suitable for automated fiber placement. If the tows were also overhung on a concave surface at the interface between the front surface 356 and the outer cylindrical surface 366, this would not cause any difficulties given the small size of the relevant surfaces: in fact, on such a small surface, it is not a problem that the tows do not press against the mold 352.

[0124] In particular, each prepreg tow is draped along a direction (not shown) which, at each point, forms a non-zero angle with the local circumferential direction C″, said angle preferably being between 25° and 90°. In other words, the draping direction of each prepreg tow has a radial component at each point.

[0125] Preferably, the different layers of prepreg tows are draped continuously along the axial direction A", so that the downstream skin preform blank 354 is formed by an axial stack of several layers. Advantageously, the orientation of the draping direction of the tows alternates from one layer to the next. For example, the draping direction of the fiber tows in the even (respectively odd) layers is essentially at a 90° angle to the circumferential direction C", and the draping direction of the tows in the odd (respectively even) layers is essentially at a 30° angle to the circumferential direction C".

[0126] Thus, the downstream skin preform blank 354 comprises:

[0127] - an axially extending rear cylindrical portion 370,

[0128] a frustoconical outer portion 372 which widens rearwardly to a rear end 373 having a diameter greater than that of the rear portion 370 , said outer portion 372 corresponding to the inner portion of the outer leg 104 of the ring 94 ,

[0129] a substantially planar collar 374 extending substantially in a radial plane, said collar 374 connecting the front end of the rear portion 370 to the rear end 373 of the outer portion 372 , said collar 374 corresponding to the upstream end 116 of the appendage 114 of the ring 94 , and

[0130] A substantially flat annular intermediate portion 376 protruding inwardly from the front end of the outer portion 372 , said intermediate portion 374 corresponding to the portion of the downstream skin 123 extending downstream of the core 120 between the inner leg 102 and the outer leg 104 of the ring 94 .

[0131] In contrast, the downstream skin preform blank 354 does not include a portion corresponding to the downstream portion of the fillet 100 or the downstream portion of the collar 92. Instead, it includes an inner portion 378 extending inwardly from the middle portion 376, the inner portion 378 having a frustoconical shape that widens forward. In particular, the angle at the apex of the inner portion 378 is greater than the angle of the inner portion 318 of the upstream skin preform blank 304.

[0132] Thus, overhang formation 222 is followed by step 224 of shaping downstream skin preform blank 354 to form a component corresponding to the downstream portion of fillet 100 and the downstream portion of collar 92 , thereby obtaining downstream skin preform 350 .

[0133] This forming is accomplished, for example, by vacuum thermoforming. Figure 10 As can be seen in FIG, the downstream skin preform blank 354 is placed on a second downstream skin mold 380. The second downstream skin mold 380 has a rotationally symmetrical shape centered about an axis of revolution (not shown). For the remainder of the description, directional terms are understood to mean Figure 10 The cylindrical coordinate system shown in relation to the second downstream skin mold 380 , in which it is possible to distinguish at each point:

[0134] an axial direction A''', which extends parallel to the axis of rotation from rear to front,

[0135] a radial direction B'''', perpendicular to the axial direction A'''', connecting the axis of revolution to said point and extending from the inside to the outside, and

[0136] - a circumferential direction C''", which is perpendicular to the axial direction A''' and to the radial direction B'''.

[0137] In a manner similar to the first downstream skin mold 352, the second downstream skin mold 380 has a front surface 382 with a raised outer annular edge 384 comprising a frustoconical outer portion 385 that widens rearwardly and a substantially flat annular middle portion 386 that extends substantially in a radial plane and projects inwardly from the front end of the outer portion 385. The second downstream skin mold 380 also has an outer cylindrical surface 387 having a smaller diameter than the outer diameter of the front surface 382 and a collar 388 that defines a rearwardly facing shoulder 389 and ensures engagement between the outer cylindrical surface 387 and the front surface 382.

[0138] In particular, the outer portion 385 , middle portion 386 , outer cylindrical surface 387 , and collar 388 are substantially identical, and advantageously identical, to the outer portion 360 , middle portion 362 , outer cylindrical surface 366 , and collar 367 , respectively, of the first downstream skin mold 352 .

[0139] Unlike the first downstream skin mold 352, the outer annular edge 384 of the second downstream skin mold 380 does not include a frustoconical inner portion that widens forward. Instead, the outer annular edge 384 includes:

[0140] a substantially flat annular inner portion 392 extending substantially in a radial plane, set back from the intermediate portion 386 and defining the inner end of the outer annular edge 384, and

[0141] An annular fillet 394 connecting the inner portion 392 to the inner end of the intermediate portion 386 .

[0142] The inner portion 392 and the annular fillet 394 together define a concave recess 396 in the front surface 382 , i.e., the surface resulting from the combination of these two areas 392 , 394 is recessed relative to the surface connecting the inner end of the intermediate portion 386 with the inner end of the outer annular edge 384 .

[0143] Thus, outer annular edge 384 has the shape of downstream skin 123 .

[0144] Advantageously, by removing the insert 398 ( Figure 9 ) A second downstream skin mold 380 is obtained from the first downstream skin mold 352 , the insert filling the groove 396 and defining the inner portion 364 of the outer annular edge 358 of the front surface 356 of the first downstream skin mold 352 .

[0145] The second upstream skin mold 380 is placed on the forming platform 400, and the downstream skin preform blank 354 is then covered by the bladder 402, preferably with a partition 404 and a drain pipe 406 inserted between the downstream skin preform blank 354 and the bladder 402. A seal is created between the bladder 402 and the forming platform 400, and the assembly is then heated, typically to a temperature between 80° C. and 90° C., while a vacuum is created between the bladder 402 and the forming platform 400. The bladder 402 is thus pressed against the second downstream skin mold 380 and, together with the second downstream skin mold, carries the upstream skin preform blank 354, softened by the heat, thereby assuming the shape of the outer annular edge 384 of the upstream surface 382 of said mold 380.

[0146] Thus, a downstream skin preform 350 is obtained.

[0147] Back to Figure 5, the manufacturing method 200 again comprises a third step 230 of preparing an insert preform 410 ( Figure 20 ). The third step 230 is performed after the first step 210 and the second step 220. Optionally (not shown), the third step is performed in parallel with the steps 210 and 220, or between the steps 210 and 220, or even before the steps 210 and 220.

[0148] See also Figure 6 The third step 230 includes placing the fibers on the insert mold 412 ( Figure 11 ) is suspended to form 231 prepreg tow. Figure 11 As can be seen in the figure, the insert mold 412 has a disc shape 414 comprising two opposing large disc surfaces 415, 416 connected together by a circumferential edge 418. In particular, the disc 414 is rotationally symmetric about a central axis (not shown). For the remainder of the description, directional terms are understood to refer to Figure 11 A cylindrical coordinate system is shown in relation to the insert mold 412, wherein at each point it is possible to distinguish:

[0149] - an axial direction P, which extends parallel to the central axis from rear to front,

[0150] a radial direction R, perpendicular to the axial direction P, connecting the central axis to said point and extending from the inside to the outside, and

[0151] A circumferential direction Q, which is perpendicular to the axial direction P and the radial direction R.

[0152] During the draping 231 , the prepreg tows are draped over the edge 418 of the disk 414 substantially parallel to the circumferential direction Q (i.e., in a direction forming an angle of less than 5°, or even less than 1°, with the circumferential direction Q). As a result, the fibers of the insert 124 are primarily oriented in the circumferential direction, which enables the insert 124 to withstand high circumferential and radial loads during the rotation of the fan rotor 54 .

[0153] Back to Figure 6 , drape formation 231 begins with a first sub-step 232 of creating a first stack 420 of layers of prepreg tows ( Figure 11 ).

[0154] During the first sub-step 232, the prepreg tows are draped in successive layers along the radial direction R. The first layer (not labeled) is first draped directly on the edge 418 of the mold 412, and each subsequent layer is then draped on the outer surface of the previous layer. For example, 40 to 60 layers are draped continuously to form the first stack 420.

[0155] The axial position of each layer is defined by reference to the first axial edge 422 (in this case, the trailing edge) of the first stack 420. In other words, the layers are axially positioned relative to one another such that the first axial edge 422 of the first stack 420 has a predefined radial profile, i.e., lies within a radial plane. In particular, the layers are positioned such that the first axial edge 422 has an axial extension, wherein, advantageously, as shown, the outer end 424 of the first axial edge 422 is axially set back relative to the inner end 425 of the first axial edge 422. In other words, the outer end 424 of the first axial edge 422 is axially offset forward relative to the inner end 425.

[0156] More specifically, the layers are positioned so that the first stack 420 includes an inner section 427 in which the first axial edge 422 has an axial extension, and an outer section 428 in which the first axial edge 422 extends substantially in a radial plane, i.e., the axial extension of the first axial edge 422 in this outer section 428 is substantially zero. The inner section 427 defines an inner end (not shown) of the first stack 420, and the outer section 428 defines an outer end (not shown) of the first stack 420. The radial profile of the first axial edge 422 is substantially continuous and conductive at the junction between the inner section 427 and the outer section 428. In the inner section 427, the radial profile of the first axial edge 422 is concave, with a concave surface directed radially outward.

[0157] The inner segment 427 and the outer segment 428 have substantially the same radial thickness.

[0158] Advantageously, the prepreg tows are arranged in a staggered manner in outer section 428. To this end, outer section 428 comprises alternating layers that are axially offset relative to one another, the layers being offset alternately forward and rearward. In other words, outer section 428 comprises a plurality of first layers that are radially aligned with one another, between which are inserted second layers that are axially offset forward or rearward relative to the first layers, the second layers themselves being radially aligned with one another. This axial offset is typically between 1 mm and 2 mm, for example substantially equal to 1.5 mm. Thus, spatial alignment between the tows, which could lead to brittleness within insert 410, is avoided.

[0159] Preferably, the radially aligned layers are grouped into groups of at least two layers, for example three layers, which are stacked consecutively without radially offset layers in between.

[0160] Back to Figure 6 , sub-step 232 is followed by sub-step 233: processing the first stack 420. Figure 12As can be seen in FIG, during this sub-step 233, the axial edge (in this case, the leading edge) of the first stack 420 opposite the axial edge 422 defined by the overhang is machined, thereby forming a first machined axial edge 430. In particular, this machining is performed by cleanly cutting the first stack 420 along a first radial cutting surface 432 by means of a cutting tool 434 having a blade 436 extending along said first cutting surface 432.

[0161] Back to Figure 6 Sub-step 233 is followed by sub-step 234 of securing a gasket 438 ( Figure 13 ). As in Figure 13 As can be seen in FIG, the shim 438 is placed on the edge 418 of the mold 412 and follows the shape of the axial edge 422 defined by the overhang. The shim has substantially the same radial thickness as the first stack 420 and is flush with the outer surface 439 of the first stack 420.

[0162] Back to Figure 6 , sub-step 234 is followed by sub-step 235 of producing a second stack 440 of layers of prepreg tows on top of the first stack 420 ( Figure 13 ).

[0163] During this sub-step 235, the prepreg tows are draped in the radial direction R in successive layers across the first stack 420 and the spacer 438. The first layer (not shown) is first draped directly over the first stack 420 and the spacer 438, and each subsequent layer is then draped outside the previous layer. For example, 40 to 60 layers are draped continuously to form the second stack 440.

[0164] The axial position of each layer is defined by reference to a first axial edge 442 (in this case, the leading edge) of the second stack 440. In other words, the layers are axially positioned relative to one another such that the first axial edge 442 of the second stack 440 has a predetermined radial profile, i.e., taken from a radial plane. This first axial edge 442 extends one of the axial edges 422, 430 of the first stack 420 (in this case, the machined axial edge 430), i.e., the inner end 443 of the first axial edge 442 is flush with the outer end 444 of the machined axial edge 430.

[0165] In particular, the layers are positioned so that the first axial edge 442 has an axial extension and, advantageously, as shown, the outer end 445 of the first axial edge 442 is axially set back relative to the inner end 443 of the first axial edge 442. In other words, the outer end 445 of the first axial edge 442 is axially offset rearward relative to the inner end 443. In particular, the outer end 445 is axially interposed between the inner end 443 and the washer 438.

[0166] More particularly, the layers are positioned so that the first axial edge 442 has no concave section with an inwardly directed concavity, i.e., so that no layer is offset axially forward relative to the underlying layer. Furthermore, the layers are positioned so that each section of the first axial edge 442 has an axial extension, i.e., the second stack 440 has no section in which the first axial edge 442 extends substantially in a radial plane.

[0167] In the example shown, the layers are positioned such that second stack 440 includes an inner segment 447, in which first axial edge 442 is convex, with a convex surface directed radially outward, and an outer segment 448, in which first axial edge 442 is substantially frustoconical, centered about the central axis. In inner segment 447, the radial profile of first axial edge 442 is, in particular, substantially in the shape of a circular arc. In particular, the inclination of first axial edge 442 in segment 448 is substantially equal to the inclination of outer surface 110 of rotating spacer ring 90 and forms an angle, for example, between 20° and 45°, with rim 418 of mold 412.

[0168] The radial profile of the first axial edge 442 is substantially continuous and conductive at the junction between the inner segment 447 and the outer segment 448 .

[0169] Back to Figure 6 , sub-step 235 is followed by sub-step 236: processing the second stack 440. Figure 14 As can be seen in FIG, during this sub-step 236, the axial edge (in this case, the rear edge) of the second stack 440 opposite the axial edge 442 defined by the overhang is machined, thereby forming a second machined axial edge 450. In particular, this machining is performed by cleanly cutting the second stack 440 along the second radial cutting surface 452 by means of a cutting tool 454 having a blade 456 that traverses the second cutting surface 452.

[0170] The second cutting surface 452 is different from the first cutting surface 432. In particular, the second cutting surface is axially offset relative to the first cutting surface 432. The second cutting surface radially extends the axial edge 422 of the first stack 420 defined by the overhang, i.e., the second cutting surface intersects the outer surface 439 of the first stack 420 at the axial edge 422.

[0171] Preferably, the shim 438 is removed before performing sub-step 236 .

[0172] Back to Figure 6 Sub-step 236 is followed by sub-step 237 of securing the shim 458 along the second machined axial edge 440 ( Figure 15 ). As in Figure 15 As seen in FIG, the shim 458 is placed on the edge 418 of the mold 412 and follows the shape of the axial edge 422 defined by the overhanging formation of the first stack 420 and the shape of the second machined axial edge 440. The shim has substantially the same radial thickness as the first stack 420 and the second stack 440 combined and is flush with the outer surface 459 of the second stack 440.

[0173] Back to Figure 6 , sub-step 237 is followed by sub-step 238 of making a third stack 460 of layers of prepreg tows on top of the second stack 440 ( Figure 15 ).

[0174] During this sub-step 237, the prepreg tows are draped in the radial direction R in successive layers across the second stack 440 and the spacer 458. A first layer (not shown) is first draped over the second stack 440 and the spacer 458, and each subsequent layer is then draped over the outer surface of the previous layer. For example, 40 to 60 layers are draped continuously to form the third stack 460.

[0175] The axial position of each layer is defined by reference to a first axial edge 462 (in this case, the leading edge) of the third stack 460. In other words, the layers are axially positioned relative to one another so that the first axial edge 462 of the third stack 460 has a predetermined radial profile, i.e., taken from a radial plane. This first axial edge 462 extends one of the axial edges 442, 450 of the second stack 440 (in this case, the axial edge 442 defined by the overhang), i.e., the inner end 463 of the first axial edge 462 is flush with the outer end 464 of the axial edge 442 defined by the overhang.

[0176] In particular, the layers are positioned so that the first axial edge 462 has an axial extension and, advantageously, as shown, the outer end 465 of the first axial edge 462 is axially set back relative to the inner end 463 of the first axial edge 462. In other words, the outer end 465 of the first axial edge 462 is axially offset rearwardly relative to the inner end 463. In particular, the outer end 465 is located radially above the washer 458, i.e. a radial plane passing through the outer end 465 intersects the washer 458.

[0177] More particularly, the layers are positioned so that the first axial edge 462 has no concave section with an inwardly directed concave surface, i.e., so that no layer is offset axially forward relative to the underlying layer. Furthermore, the layers are positioned so that each section of the first axial edge 462 has an axial extension, i.e., the third stack 460 has no section in which the first axial edge 462 extends substantially in a radial plane.

[0178] In the example shown, the first axial edge 462 is substantially frustoconical in shape and is centered on the central axis. In particular, the first axial edge has an inclination substantially equal to the inclination of the outer surface 110 of the rotating spacer ring 90 and forms an angle, for example, between 20° and 45° with the edge 418 of the mold 412.

[0179] Back to Figure 6 Sub-step 238 is followed by step 239: processing the third stack 460. Figure 16 As can be seen in FIG, during this sub-step 239, the axial edge (in this case the rear edge) of the third stack 460 opposite the axial edge 462 defined by the overhanging is machined, thereby forming a third machined axial edge 470. In particular, this machining is performed by neatly cutting the third stack 460 along a third radial cutting surface 472 by means of a cutting tool 474 having a blade 476 that traverses said third cutting surface 472.

[0180] The third cutting surface 472 is different from the first cutting surface 432 and the second cutting surface 452. Specifically, the third cutting surface 472 is a frustoconical surface centered on the central axis and widening rearward. The third cutting surface radially extends the axial edge 442 of the second stack 440 defined by the overhang. In other words, the third cutting surface intersects the outer surface 459 of the second stack 440 at the axial edge 442 defined by the overhang, and intersects the outer end 465 of the axial edge 462 of the third stack 460 defined by the overhang.

[0181] Preferably, the shim 458 is removed before performing this sub-step 239 .

[0182] Thus, an insert preform 410 is obtained.

[0183] It should be noted that, through sub-steps 232 to 239, this insert preform 410 of small size and complex shape is obtained without implementing a complex cutting strategy. More specifically, the insert preform 410 is simply divided into a plurality of concentric regions 420, 440, 460, each with a planar or frustoconical axial edge, and for each of these regions 420, 440, 460, the axial edge with the most complex geometry (for example, because it is curved while another edge is straight, or because it is inclined while another edge is radial) is directly formed during the draping process simply by programming the robot to offset the strip from one layer to the other, which is very easy to do. Then, in order to obtain the planar or frustoconical axial edge, it is sufficient to machine the opposite axial edge by a clean cut. This cutting of one of the two axial edges is still necessary because the tow has a fixed width (typically 6.35 mm) which is the same for all layers and is not small compared to the width of the insert preform 410 (each layer is formed from only a few tows placed side by side, the number of these tows typically being between 1 and 20, more typically between 3 and 9). Therefore, during the drape formation, it is not possible to adjust the distance between the axial edges by adjusting the width of the tow or the number of tows deposited in each layer. As a result, at the end of each production 232, 235, 238 of the layer stack, the axial edge opposite to the edge defined by the drape formation remains, having a geometry substantially identical to that of the edge defined by the drape formation (this aspect is schematically illustrated in FIG. Figure 11 、 Figure 13 and Figure 15 (not shown in the drawing, however, in practice the two axial edges in question do have substantially the same geometry). In order to give this axial edge the desired geometry (which differs from the geometry of the edge defined by the overhanging formation), said axial edge is machined.

[0184] Back to Figure 5 In the example shown, the method further comprises a fourth step 240 of preparing a strand preform 480 ( Figure 23 ). In this case, the fourth step 240 is performed after the first step 210, the second step 220 and the third step 230. Alternatively (not shown), the fourth step is performed in parallel with the steps 210, 220, 230, or between the steps 210, 220, 230, or even before the steps 210, 220, 230.

[0185] refer to Figure 17In this step 240, the prepreg tows 482 are stacked continuously in a strand mold 484. The strand mold 484 is curved, and its inner radius of curvature is substantially equal to the outer radius of the rear end 373 of the outer portion 372 of the downstream skin preform 350. The strand mold has a radial cross section, that is, a cross section taken in a plane perpendicular to the curvature direction of the mold 484, which is substantially V-shaped, widening from the bottom 486 to the opening 488. The strand mold is defined between two walls 490, 492 converging toward the bottom 486, each wall 490, 492 extending from the opening 488 to the bottom 486. The first wall 490 has a radial profile that is substantially straight. The second wall 492 has a radial profile in the shape of an arc of a circle, and its radius of curvature is substantially equal to the fillet 494 ( Figure 22 )’s outer radius of curvature.

[0186] The tows are evenly compacted in the mold 484, and the stacking and compacting steps are repeated until the mold 484 is completely filled. The tow stack is then removed from the mold 484, thereby obtaining the tow preform 480.

[0187] Advantageously, the strand preform 480 does not form a complete ring: the aforementioned steps are then repeated as many times as necessary to obtain a plurality of strand preforms 480 sufficient to form a complete ring. Alternatively, the strand preform 480 forms a complete ring; a single strand preform 480 is then produced in step 240.

[0188] The prepreg tows used to make the upstream skin preform 300, the downstream skin preform 350, the insert preform 410, and (where applicable) the strand preform 480 are advantageously all of substantially the same composition. The tows are typically unidirectional fiber tows, the fibers being carbon fibers, such as AS7 fibers, embedded in an epoxy resin, such as 8552 resin.

[0189] Back to Figure 5 After steps 210, 220, 230, and 240, the method 200 further includes step 250: preparing a rotating spacer ring preform 490 ( Figure 25 ).

[0190] This step 250 begins with a sub-step 251 of inserting an insert preform 410 between the upstream skin preform 300 and the downstream skin preform 350 .

[0191] This sub-step 251 begins by positioning 252 the upstream skin preform 300 in the rotating spacer ring mold 500 ( Figure 18 ).like Figure 18As shown, the mold 500 has a shape that is rotationally symmetrical about a principal axis (not shown). For the remainder of the specification, directional terms are understood to refer to Figure 18 The cylindrical coordinate system shown in relation to the mold 500 , in which at each point it is possible to distinguish:

[0192] a vertical direction Z, parallel to the main axis, extending from the bottom to the top,

[0193] a radial direction U, perpendicular to the vertical direction Z, connecting the main axis to said point and extending from the inside to the outside, and

[0194] A circumferential direction V, perpendicular to the vertical direction Z and to the radial direction U.

[0195] In particular, the mold 500 has a disc-like shape with an upper surface 502 comprising:

[0196] - a substantially disc-shaped central plate 504,

[0197] - an annular peripheral plate 506, and

[0198] An annular notch 508 extending downwardly relative to the central plate 504 and the peripheral plate 506 between the central plate 504 and the peripheral plate 506 .

[0199] The central plate 504 and the peripheral plates 506 are each substantially perpendicular to the main axis and substantially parallel to each other. The peripheral plates 506 are vertically offset upward relative to the central plate 504.

[0200] The slot 508 is defined between a generally cylindrical inner wall 510 centered about the major axis and a generally frustoconical outer wall 512 centered about the major axis and widening in an upward direction, the walls 510, 512 converging toward a bottom 514 of the slot 508. The inner wall 510 is connected to the center plate 504 by a fillet 516 having an outer radius of curvature substantially equal to the inner radius of curvature of the fillet 100 of the rotating spacer ring 90.

[0201] The center plate 504 , fillet 516 , inner wall 510 , bottom 514 , and outer wall 512 together define a surface within the groove that is complementary to the upstream surface 126 of the rotating spacer ring 90 .

[0202] The upstream skin preform 300 is thus positioned in the mold 500 so that its middle portion 317 extends into the bottom 514 of the slot 508 and its outer portion 316 abuts the outer wall 512 and extends partially outside the slot 508 , above the outer panel 502 .

[0203] Back to Figure 5, sub-step 251 also includes cutting 253 the upstream skin preform 300. As in Figure 19 As can be seen in FIG, during this cutting 253, the portion 518 ( Figure 18 ) was removed.

[0204] Still refer to Figure 5 , sub-step 251 also includes positioning 254 the insert preform 410. As in Figure 20 As can be seen in FIG, during this positioning 254, the insert preform 410 is received in the upstream skin preform 300 at the bottom of the notch 508, with the front surface of said preform 410 facing downwards.

[0205] Positioning 254 is followed by compression 255 of the insert preform 410. Figure 21 As seen in FIG, during this compression 255, a punch 520 presses the rear surface of the insert preform 410 into the notch 508, thereby compressing it into the notch 508. The punch 520 has a flat, downward-facing bearing surface 522 having an inner edge 524 and an outer edge 524, each of which is curved upward. This step allows the rear surface of the insert preform 410 to be shaped so that it better matches the downstream skin preform 350.

[0206] Compression 255 is followed by positioning 256 the downstream skin preform 350. Figure 22 As can be seen in FIG, during this positioning 256, the downstream skin preform 350 is placed on top of the upstream skin preform 300 and the insert preform 410, with the front surface of the downstream skin preform facing downward. The outer portion 372 of the downstream skin preform 350 is placed against the outer portion 316 of the upstream skin preform 300, and its middle portion 376 is placed against the rear surface of the insert preform 410. The rear portion 370 of the downstream skin preform 350 then extends substantially vertically, and the annular space 528 remains free between the rear end of the outer portion 316 of the upstream skin preform 300 and the fillet 494 that forms the joint between the outer portion 372 of the downstream skin preform 350 and the collar 374.

[0207] Thus, the insert preform 410 is inserted between the upstream skin preform 300 and the downstream skin preform 350 .

[0208] Sub-step 251 is followed by sub-step 257: Positioning the strand preform 480. Figure 23As seen in , in this sub-step 257 , the strand preform 480 is placed in the annular space 528 between the rear end of the outer portion 316 of the upstream skin preform 300 and the fillet 494 of the downstream skin preform 350 , so as to fill said annular space 528 .

[0209] Sub-step 257 is followed by sub-step 258: Positioning the mold insert 530 ( Figure 24 ). As in Figure 24 As can be seen in FIG, in this sub-step 258, a mold insert 530 is placed on the peripheral panel 506. The insert 530 is placed to cover the peripheral panel 506, the aft end of the outer portion 316 of the upstream skin preform 300, the strand preform 480, and the collar 374 of the downstream skin preform 350. The insert is in contact with the base of the aft portion 370 of the downstream skin preform 350.

[0210] The insert 530 is annular with an inner radius of curvature substantially equal to the outer radius of curvature of the rear portion 370 of the downstream skin preform 350. The insert is substantially planar and has a large lower surface 532 in contact with the peripheral panel 506, a large upper surface 534 opposite and substantially parallel to the large lower surface 532, and an inner edge 536 connecting the large surfaces 532, 534. The thickness of the insert 530 is substantially equal to the distance between the ends 116, 118 of the appendage 114 of the rotating spacer ring 90.

[0211] The insert 530 is advantageously formed of several parts (not shown) juxtaposed to one another.

[0212] Finally, sub-step 258 is followed by sub-step 259 of folding the downstream skin preform 350. Figure 25 As seen in , during this sub-step 259 , the rear portion 370 of the downstream skin preform 350 is folded outwardly onto the mold insert 530 .

[0213] A die 540 is used to achieve this folding. The die 540 comprises a core 542 having a lower surface 544 which comprises, from the outside to the inside:

[0214] - an outer frustoconical portion 546 that widens upwards,

[0215] a substantially flat annular intermediate portion 548 extending substantially in a radial plane and projecting inwardly from the lower end of the outer portion 546 ,

[0216] an annular fillet 550 having an inwardly and downwardly directed concave surface extending upwardly from the inner end of the intermediate portion 548, and

[0217] A substantially flat annular inner portion 552 extending substantially in a radial plane set back from the intermediate portion 548 , in extension of the inner end of the fillet 550 .

[0218] The core 542 also includes an outer surface 554 that includes, from top to bottom:

[0219] a cylindrical portion 556 having a diameter smaller than the outer diameter of the lower surface 544,

[0220] a collar 558 extending radially outwardly from the lower end of the cylindrical portion 556 and defining an upwardly facing shoulder, and

[0221] A rounded corner 560 with an outwardly directed projection connecting the outer end of the collar 558 to the outer end of the outer portion 546 of the lower surface 544 .

[0222] The core 542 is complementary in shape to the rear surface of the downstream skin preform 350 .

[0223] The die 540 further includes a folding ring 562. The folding ring 562 projects radially outward from the core 542 at a distance from the collar 558. The folding ring has a substantially flat lower surface 564 that, together with the cylindrical portion 556 of the outer surface 554 of the core 542 and the collar 558, defines an outer recess 566, the bottom of which is formed by the cylindrical portion 556. The width of the outer recess 566, which is comprised of the distance from the folding ring 562 to the collar 558, is substantially equal to the thickness of the mold insert 530 plus twice the thickness of the downstream skin preform 350.

[0224] The die 540 is preferably made of silicone. Advantageously, the die is composed of a plurality of sectors (not shown).

[0225] To fold the aft portion 370 of the downstream skin preform 350, the press die 540 is positioned so that the recess 566 fits over the inner edge 536 of the mold insert 530, and the outer portion 546 and the middle portion 548 of the front surface 544 of the core 542 bear against the outer portion 372 and the middle portion 376, respectively, of the downstream skin preform 350. In doing so, the folding ring 562 presses against the aft portion 370 of the downstream skin preform 350 and folds the aft portion over the mold insert 530.

[0226] A rotating spacer ring preform is thus obtained.

[0227] Finally, step 250 is followed by step 260: baking the rotating spacer ring preform. In this step 260, the rotating spacer ring preform remains in the mold 500 (with the mold insert 530 and the die 540 in place) and is conventionally heated to a suitable temperature to allow the matrix to crosslink and the preform to cure. The preform is then cooled and removed from the mold, resulting in the rotating spacer ring 90.

[0228] Because the die 540 is made of silicone, it expands during the baking process. Thus, during the curing process, the die presses against the downstream skin preform 350, which ensures a good bond between the upstream skin 122, the downstream skin 123, and the insert 124 at the end of the baking process.

[0229] Therefore, a rotating spacer ring 90 made of a composite material with excellent mechanical properties can be obtained simply and cheaply by the above method 200. The method 200 is also easily repeatable, which means that the rotating spacer rings obtained using the method are highly consistent.

[0230] In particular, the method 200 cleverly solves the problem of applying automated fiber placement drape forming technology to the manufacture of rotating spacer rings. In particular, the thermoforming 214, 224 of the preforms 300, 350 after the drape forming 212, 222 solves the problem of managing small recessed areas. This thermoforming 214, 224 is made possible by depositing the tows in a direction forming a non-zero angle with the circumferential direction during the drape forming 212, 222, even though this arrangement of the tows is counterintuitive because it violates the goals of mechanical strength generally sought for components of this type. This arrangement itself is made possible by separating the two functions of the skins 122, 123, which hold the components together and define the surface seen by the airflow, and the mechanical reinforcement function of the insert 124 (for which the fibers are deposited in the circumferential direction).

Claims

1. A method (200) for manufacturing a spacer ring (90) made of composite material for a turbine engine fan, the spacer ring (90) comprising an upstream skin (122), a downstream skin (123) and an annular insert (124), the upstream skin defining an upstream surface (126) of the spacer ring (90) when the spacer ring is mounted on the turbine engine, the downstream skin defining a downstream surface (128) of the spacer ring (90) when the spacer ring is mounted on the turbine engine, the annular insert being accommodated between the upstream and downstream skins (122, 123), the manufacturing method (200) comprising the following steps: - preparing (210) an upstream skin preform (300), - preparing (220) a downstream skin preform (350), - preparing (230) an insert preform (410), - inserting (251) the insert preform (410) between the upstream skin preform (300) and the downstream skin preform (350) so as to form a rotating spacer ring preform, and - baking (260) the rotating spacer ring preform, wherein preparing (210) the upstream skin preform (300) and / or preparing (220) the downstream skin preform (350) comprises: draping (212, 222) prepreg tows on a skin mold (302, 352) by automated fiber placement, wherein preparing (230) the insert preform (410) comprises: draping (231) a prepreg tow on an insert mold (412) by automated fiber placement, the insert mold (412) having a disk shape (414), the prepreg tow being draped on an edge (418) of the disk (414), wherein the disk (414) is rotationally symmetric about a central axis, a cylindrical coordinate system is associated with the insert mold (412) such that at each point there is an axial direction (P) parallel to the central axis, a radial direction (R) connecting the central axis to the point, and a circumferential direction (Q) perpendicular to the axial direction and the radial direction, and each prepreg tow is suspended substantially parallel to the circumferential direction (Q), Wherein, forming (231) a prepreg tow suspended on the insert mold (412) comprises: - producing (232, 235, 238) at least one stack (420, 440, 460) of prepreg tow layers stacked in said radial direction (R), said stack (420, 440, 460) having an axial edge (422, 442, 462) defined by overhanging, said axial edge having an axial extension, and - machining (233, 236, 239) a machined axial edge (430, 450, 470) of the stack (420, 440, 460) by cleanly cutting the stack (420, 440, 460), the machined axial edge being opposite to the axial edge (422, 442, 462) defined by overhanging.

2. The manufacturing method (200) according to claim 1, wherein: Draping (212, 222) a prepreg tow on the skin mold (302, 352) to produce an annular preform blank (304, 354), preparing (210) the upstream skin preform (300) and / or preparing (220) the downstream skin preform (350) after the draping (212, 222) includes: shaping (214, 224) the preform blank (304, 354) to form the upstream skin preform (300) and / or the downstream skin preform (350), respectively.

3. The manufacturing method (200) according to claim 1 or 2, wherein: The skin mold (302, 352) has a rotationally symmetrical shape centered on the axis of revolution, and a cylindrical coordinate system is associated with the skin mold (302, 352) so that at each point, there is: an axial direction (A, A") parallel to the axis of revolution, a radial direction (B, B") connecting the axis of revolution to the point, and a circumferential direction (C, C") perpendicular to the axial direction and the radial direction, and each prepreg tow is suspended along a direction forming a non-zero angle with the local circumferential direction (C, C") at each point.

4. The manufacturing method (200) according to any one of the preceding claims, wherein: For at least one stack (420, 440), the axial edge (422) defined by the overhang is curved and the machined axial edge (430) is straight, or the axial edge (442) defined by the overhang is inclined and the machined axial edge (450) is radial.

5. The manufacturing method (200) according to any one of the preceding claims, wherein: A plurality of stacked bodies (420, 440, 460) are produced, wherein the stacked bodies (420, 440, 460) include an inner stacked body (420, 440) and an outer stacked body (440, 460) radially superimposed on the inner stacked body (420, 440), wherein the machined axial edges (430, 450) of the inner stacked bodies (420, 440) are obtained by neatly cutting the inner stacked bodies (420, 440) along a main cutting surface (432, 452), and the machined axial edges (450, 470) of the outer stacked bodies (440, 460) are obtained by neatly cutting the outer stacked bodies (440, 460) along a secondary cutting surface (452, 472) different from the main cutting surface (432, 452).

6. The manufacturing method (200) according to claim 5, wherein: The axial edge (442) defined by the overhang of the outer stacking body (440) radially extends the machined axial edge (430) of the inner stacking body (420), and the secondary cutting surface (452) radially extends the axial edge (422) defined by the overhang of the inner stacking body (420), or the axial edge (462) defined by the overhang of the outer stacking body (460) radially extends the axial edge (442) defined by the overhang of the inner stacking body (440), and the secondary cutting surface (472) radially extends the machined axial edge (450) of the inner stacking body (440).

7. The manufacturing method (200) according to any one of the preceding claims, wherein: The machined axial edges (430, 450, 470) are obtained by cleanly cutting the stack (420, 440, 460) along radial or frustoconical cutting surfaces (432, 452, 472).

8. A spacer ring (90) obtained by the manufacturing method (200) according to any one of claims 1 to 7.

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