Method for manufacturing a fibrous tube preform

Abstract

A method for manufacturing a fibrous tube preform comprises: - the three-dimensional weaving of a one-piece fibrous blank (100) between a plurality of warp yarn layers (101) and a plurality of weft yarn layers (102), the fibrous blank comprising a debonding (103) extending over the entire fibrous blank in a longitudinal direction (DL), the debonding (103) extending in the transverse direction (DT) between first and second debonding points (103b, 103c) located set back from the first and second lateral ends (100c, 100d) of the fibrous blank so as to retain bonding portions (105, 107) on each side of the debonding, - the placement of a forming element in a recess (140) of the blank fibrous material formed by unbinding in such a way as to form part of a tubular preform,- the removal of the bonding portion by cutting in cutting zones located at least two columns of warp threads and at most three columns of warp threads from the bottom of the unbinding. Figure for the abbreviation: Fig. 2.

Description

Title of the invention: Method for manufacturing a fibrous tube preform technical field

[0001] The present invention relates to the field of fibrous preforms used to produce parts made of composite material. It relates more particularly to the production of fibrous preforms for manufacturing tubes made of composite material. Previous technique

[0002] Tubular composite material parts are used in the aeronautical field. For example, the new generation of unfaired engines (known as "open fan" or "open rotor" engines) requires more compact blade roots. This need arises from the requirement to be able to rotate the blade around its vertical axis in order to adapt its angle of attack to the flight regime (variable pitch blade). The blade root is formed from a tubular preform produced by three-dimensional weaving and having an internal recess. The preform is shaped by inserting a metallic insert or sleeve into the internal recess of the preform. An external metallic shell is then attached to the external surface of the preform.

[0003] Document EP 3 733 386 describes a method for manufacturing composite material tubes in which the fibrous preform is produced by helical winding of fibrous ribbons onto a mandrel. This method does not allow for the production of continuous fibrous reinforcements sufficient to give the tube adequate mechanical strength.

[0004] Another technique for forming a tubular fibrous preform involves layering two textile layers with a mandrel between them and sewing the two layers together on either side of the mandrel. While such a fibrous preform allows for the formation of a stronger fibrous reinforcement, particularly when using 3D woven textile layers, its manufacture remains complex and exhibits poor repeatability. Description of the invention

[0005] It is therefore desirable to be able to propose a solution for the production of fibrous tube preforms which does not present the aforementioned disadvantages.

[0006] To this end, the present invention proposes a method for manufacturing a fibrous tube preform intended to form the fibrous reinforcement of a part or a portion of a part made of composite material, the method comprising: - the production by three-dimensional weaving of a single-piece fibrous blank between a plurality of layers of warp yarns extending along a longitudinal direction and a plurality of layers of weft yarns extending along a transverse direction, the warp yarns being woven in a plurality of columns spaced apart along the transverse direction, the fibrous blank having a flat shape extending along a longitudinal direction between first and second longitudinal ends and along a transverse direction between first and second lateral ends, the fibrous blank comprising a debinding extending over the whole of the fibrous blank along the longitudinal direction,the unbinding extending along the transverse direction between first and second unbinding grounds located set back from the first and second lateral ends of the fibrous blank so as to retain first and second bonding portions on each side of the unbinding, the unbinding delimiting an internal housing opening at the first and second longitudinal ends of the fibrous blank, a first part of yarns from the plurality of weft yarn layers crossing a second part of yarns from the plurality of weft yarn layers at the level of the first unbinding ground and at the level of the second unbinding ground, , - the placement of a cylindrical forming element in the internal housing of the fibrous blank so as to form a part of the tubular preform, - the removal of the first bond portion by cutting along a thickness direction of the fibrous blank perpendicular to the longitudinal and transverse directions, the cutting being carried out in a first cutting zone located at least two columns of warp threads and at most three columns of warp threads from the first unbonding bottom along the transverse direction, - the removal of the second bonding portion by cutting along the thickness direction of the fibrous blank, the cutting being carried out in a second cutting zone located at least two columns of warp yarns and at most three columns of warp yarns from the second unbonding bottom along the transverse direction so as to obtain a fibrous tube preform.

[0007] Locating each cutting zone of the bonding portions at least two columns of warp yarns from the unbinding base ensures a sufficiently strong textile bond on each side of the unbinding, thus preventing the risk of the tube preform opening after the bonding portions are removed. Furthermore, locating each cutting zone of the bonding portions at no more than three columns of warp yarns from the unbinding base ensures a fiber content in the cut areas equivalent to that of the rest of the preform. In other words, if the cutting zones were extended beyond three columns of warp yarns from the unbinding bases, the fibrous preform would exhibit localized fibers at the cut areas. a higher volumetric fiber content than in the rest of the preform, which would negatively impact the material health of the resulting composite part.

[0008] According to a particular feature of the process of the invention, the fibrous blank comprises on one face first and second tracer wires aligned respectively with the first and second cutting zones. Locating the cutting zones is thus facilitated.

[0009] According to another particular feature of the process of the invention, before the first and second bonding portions are removed, the fiber blank with the cylindrical forming element present in the internal housing is placed in a holding tool comprising a lower wedge and an upper wedge between which the tubular preform portion is held. The upper wedge has first and second slots opposite the first and second cutting zones, respectively. The first and second bonding portions are cut by a cutting tool through the first and second slots. With this tool, the fiber blank can be held in a reference position during cutting, which greatly improves the accuracy and repeatability of the bonding portion removal and, consequently, of the preform manufacturing process.Furthermore, holding the blank in place by clamping it between shims significantly reduces the risk of the blank re-bulking after the connecting portions have been cut.

[0010] According to another particular feature of the method of the invention, the holding tooling comprises, among other things, a first pair of lateral flanges between which the first bonding portion of the fiber blank is held and a second pair of lateral flanges between which the second bonding portion of the fiber blank is held. This further improves the holding of the fiber blank in its reference position by clamping the bonding portions during their cutting.

[0011] According to another particular feature of the method of the invention, it comprises, after cutting the first and second connecting portions, compacting the fibrous tube preform by the lower and upper shims of the holding tool and by lateral shims arranged on each side of said fibrous tube preform. Compacting the preform in the holding tool used for cutting the connecting portions simplifies the preform manufacturing process and allows for precise adjustment of the fiber volume percentage within it, since it is still held in its reference position and it is easy to define a precise compaction ratio based on the distance between the shims and the preform.

[0012] According to another particular feature of the method of the invention, the lower and upper wedges of the holding tooling each have a groove-shaped imprint cooperating with a portion of the tubular preform portion of the fibrous blank. This improves the accuracy of maintaining the blank and preform in the reference position during cutting and compaction operations.

[0013] According to another particular feature of the process of the invention, the fibrous preform is moistened before compaction. The water then acts as a lubricant which facilitates the sliding of the fibers against each other during compaction.

[0014] According to another particular feature of the process of the invention, the fibrous preform is dried after compaction. Evaporation of the water causes the sizing to migrate and then solidify, which allows the fibrous preform to remain in its compacted state after removal from the tooling.

[0015] According to another particular feature of the method of the invention, the fibrous tube preform corresponds to a portion of the foot preform of a blade or propeller. The method of the invention finds a particularly advantageous application in the production of foot or propeller preform portions for the new generation of unfaired engines (known as "open fan" or "open rotor" engines) which have a shape of revolution. In this case, the method may further include the placement of an outer shell around the foot preform portion. Controlling the dimensions of the tube preform makes it easier and more secure to attach the outer shell.

[0016] The invention also relates to a method for manufacturing a tubular part made of composite material comprising manufacturing a fibrous tube preform according to the invention and densifying said fibrous tube preform with a matrix. Brief description of the drawings

[0017] [Fig-1] Fig. 1 is a schematic view illustrating a fibrous rough for the manufacture of a tube preform according to an embodiment of the invention,

[0018] [Fig.2] [Fig.2] is an enlarged cross-sectional view in the weft direction of a set of yarn layers showing the formation of a debond in the rough of [Fig.1] along a section plane II-II,

[0019] [Fig.3] The [Fig.3] is a schematic perspective view showing the shaping of the fibrous blank of the [Fig.1],

[0020] [Fig.4] [Fig.4] is a schematic perspective view of the fibrous roughing of the [Fig.1] shaping,

[0021] [Fig.5] [Fig.5] is a schematic exploded perspective view of a holding tool in which the fibrous blank of [Fig.4] is placed according to an embodiment of the invention,

[0022] [Fig.6] Fig.6 is a schematic perspective view of the tooling of Fig.5 once assembled and showing the cutting of connecting portions of the fiber blank,

[0023] [Fig.7] Fig.7 is a schematic perspective view of a fiber tube preform,

[0024] [Fig.8] The [Fig.8] is a schematic perspective view showing the compaction of the fibrous preform of the [Fig.7],

[0025] [Fig. 9] [Fig. 9] is a schematic perspective view of a composite material tube obtained from the fibrous tube preform of [Fig. 7]. Description of embodiments

[0026] The invention applies generally to the manufacture of fibrous preforms or parts of tube preforms intended to form reinforcements for composite material tubes. The invention finds an advantageous but not exclusive application in the manufacture of blade roots or propellers for unfaired rotating wheels such as in so-called "open rotor" aircraft engines.

[0027] In the following description, the embodiment examples are described in relation to the manufacture of a blade or propeller for unshod, rotating turbomachine wheels. However, the embodiment examples also apply to tubular parts intended for other applications.

[0028] Fig. 1 shows very schematically a fibrous blank 100 intended to form the fibrous preform of a tube to be produced.

[0029] The fibrous blank 100 is obtained, as schematically illustrated in [Fig. 1], by three-dimensional (3D) weaving carried out in a known manner using a Jacquard-type loom (not shown in [Fig. 1]) on which a bundle of warp yarns 101 or strands is arranged in a plurality of layers extending along a longitudinal direction DL, the warp yarns being linked by weft yarns 102 belonging to layers of weft yarns extending along a transverse direction DT. The fibrous blank 100 is woven in a single piece and has a flat shape. The fibrous blank 100 extends in the longitudinal direction DL between first and second longitudinal ends 100a and 100b and along the transverse direction DT between first and second lateral ends 100c and 100d.

[0030] In the illustrated example, the 3D weave is an "interlock" weave. By "interlock" weave, we mean here a weave structure in which each layer of weft yarns connects several layers of warp yarns with all the yarns in the same weft column having the same movement in the plane of the weave.

[0031] Other known types of three-dimensional weaving may be used, such as those described in WO 2006 / 136755. This document describes, in particular, the production of fibrous structures by weaving in a single piece. reinforcement for parts such as blades having a first type of core armor and a second type of skin armor which make it possible to confer both the mechanical and aerodynamic properties expected for this type of part.

[0032] The fibrous blank according to the invention can be woven in particular from carbon fiber yarns or ceramic such as silicon carbide.

[0033] According to the invention, during weaving, a debonding 103 is made within the fiber blank 100 between two successive layers of warp yarns. The debonding 103 extends along a plane parallel to the surface of the fiber blank and over a debonding zone delimited by a contour 103a, locally separating the fiber blank 100 into two woven portions 113 and 114. The debonding 103 extends over the entire fiber blank along the longitudinal direction DL so as to open at the longitudinal ends 100a and 100b. In addition, the linkage 103 extends in the transverse direction DT between first and second linkage bottoms 103b and 103c located set back from the lateral ends 100c and lOOd (i.e. the linkage 103 does not open onto the lateral ends 100c and lOOd) so as to retain first and second linkage portions 105 and 107 on each side of the linkage 103.The debonding 103 thus forms in the fibrous rudiment 100 an internal housing 140 which opens at the longitudinal ends 100a and 100b of said rudiment.

[0034] A 3D interlock weave of the blank 100 is shown schematically in [Fig. 2]. [Fig. 2] is a partial enlarged view of a warp cross-section in a portion of the blank 100 including the unlinking zone 103 (section II-II in [Fig. 1]). In this example, the blank 100 comprises eight layers Ci to C8 of warp yarns 101 extending substantially in the longitudinal direction DL. The warp yarns 101 are woven in a plurality of columns spaced apart along the transverse direction DT.

[0035] In [Fig.2], the eight layers of warp yarns are linked by weft yarns Ti to T8 in the linking portions 105 and 107 of the fibrous blank 100, the weft yarns extending substantially in the transverse direction DT. At the linking 103, a first woven portion 113 comprises four layers Ci to C4 of warp yarns 101 linked together by four weft yarns T2, T5 and T6 while a second woven portion 114 comprises the four other layers C5 to C8 of warp yarns 101 linked together by four weft yarns T3, T4, T7 and T8.

[0036] In other words, the fact that the weft yarns T2, T5 and T6 do not extend into the warp yarn layers of the second woven portion 114 and that the weft yarns T3, T4, T7 and T8 do not extend into the warp yarn layers of the first woven portion 113 ensures the unbinding 103 which separates the woven portions 113 and 114.

[0037] In the weaving example shown in [Fig. 2], a first set of weft yarns crosses a second set of weft yarns in a region of the fiber blank 100 located near the unlinking 103 along the transverse direction DT. The yarns of the first set of weft yarns 102 extend on one side of the unlinking 103 along the transverse direction DT, while the yarns of the second set of yarns from the plurality of weft yarn layers 102 extend on the other side of the unlinking 103 along the transverse direction DT. More precisely, one or more weft yarns 102 linking warp yarn layers forming a set of yarn layers 108 in the first linking portion 105 are used to link warp yarn layers forming a set of yarn layers 109 in the second linking portion 107, and vice versa. In the example illustrated in the [Fig.2], weft yarns T3 and T4, linking warp yarn layers 101 of the yarn layer set 108 in the first linking portion 105 are deflected before the unlinking 103 to link warp yarn layers 101 of the yarn layer set 109. Similarly, weft yarns T5 and T6, linking warp yarn layers 101 of the yarn layer set 109 in the first linking area 105 are deflected before the unlinking 103 to link warp yarn layers 101 of the yarn layer set 108.After the unbinding 103, the weft yarns T3 and T4 are again deflected at the end of the unbinding 103, i.e., upon their entry into the second bonding section 107, to bind layers of warp yarns 101 of the yarn layer set 109, while the weft yarns T5 and T6 are again deflected at the end of the unbinding 103, i.e., upon their entry into the second bonding section 107, to bind layers of warp yarns 101 of the yarn layer set 108. The crossing of the weft yarns T3 and T4 and the weft yarns T5 and T6 upstream and / or downstream of the unbinding 103 along the transverse direction DT improves the strength of the fiber blank in the first and second layers 103b and 103c of the unbinding. 103. .

[0038] Creating weft yarn crossover zones between the woven portions 113 and 114, separated by the unbinding 103, allows for the reproduction of a textile configuration similar to that of two stitched layers, in that these crossover zones are flexible during the shaping of the blank. This prevents buckling of the portions on either side of the unbinding in the vertical areas of the preform. It also allows for a standard preform design that adapts to different desired geometries (an operation performed during forming).

[0039] Once the weaving is finished, the non-woven yarns present around the fibrous blank 100 are cut to extract the blank and then the foot part of the blank is shaped.

[0040] As illustrated in Figures 3 and 4, the shaping of a portion of the tubular preform is carried out by separating the woven portions 113 and 114 and introducing a cylindrical forming element 130 into the internal cavity 140 formed by the debonding 103 in the fibrous blank 100. The cylindrical forming element may, in particular, be made of metallic material or resin by additive manufacturing, for example. The cylindrical forming element may also be made of a flexible material.

[0041] The first and second bonding portions 105 and 107 are then removed. More specifically, and in accordance with the invention, the first bonding portion 105 is cut along the thickness direction (DE) of the fiber blank, the cut being made in a first cutting zone ZCi ([Fig. 2]) located at least two columns of warp yarns and at most three columns of warp yarns from the first bottom 103b of the bond 103 along the transverse direction DT. Similarly, the second bonding portion is cut along the thickness direction DE of the fiber blank, the cut being made in a second cutting zone ZC2 ([Fig. 2]) located at least two columns of warp yarns and at most three columns of warp yarns from the second bottom 103c of the bond 103 along the transverse direction DT.Locating each cutting zone of the bonding sections at least two columns of warp yarns from the bottom of the debinding ensures a sufficiently strong textile bond on each side of the debinding, thus preventing the risk of the tube preform opening after the bonding sections are removed. Furthermore, locating each cutting zone of the bonding sections at no more than three columns of warp yarns from the bottom of the debinding ensures a fiber content in the cut areas equivalent to that of the rest of the preform.

[0042] According to a particular feature, the fibrous blank 100 may have, on its cutting face, marker yarns, i.e., yarns having a different color from the warp and weft yarns used to weave the blank, in order to facilitate the identification of the cutting areas. In the example described here, the fibrous blank 100 has, on its upper face, two marker yarns 150 and 151 (Figures 2 to 5) allowing the cutting areas ZCi and ZE2* to be identified respectively.

[0043] Preferably, before the removal of the first and second connecting portions 105 and 107, the fibrous blank 100 with the cylindrical forming element 130 present in the internal housing 140 is placed in a holding tool 300 as illustrated in Figures 5 and 6. The holding tool 300 comprises a lower wedge 310 and an upper wedge 320 between which the tubular preform portion 210 formed in the fibrous blank 100 is held. In the example described here, the lower wedge 310 has a groove-shaped recess 312 cooperating with a lower portion of the tubular preform portion 210, while the upper wedge 320 has a groove-shaped recess 323 cooperating with an upper portion of the tubular preform portion 210. Guide rods 311 fixed to the lower wedge 310 cooperate with holes 324 present on the upper wedge 320 to guide the assembly of these wedges during the mounting of the tool ([Fig. 6]).In the example described here, the holding tooling 300 comprises a first pair of lateral flanges 330 and 331 between which the first connecting portion 105 of the fiber blank 100 is held, and a second pair of lateral flanges 340 and 341 between which the second connecting portion 107 of the fiber blank 100 is held. The fiber blank is thus held in a reference position during the subsequent manufacturing steps of the horn tube preform described below.

[0044] The upper wedge 310 has two slots 321 and 322 for the passage of a cutting tool. The slots 321 and 322 are aligned respectively with the tracer wires 150 and 151 and, consequently, with the cutting areas ZC1 and ZC2-

[0045] As illustrated in [Fig. 6], the cutting of the bonding portions 105 and 107 is carried out through the slots 321 and 322 by a cutting tool, here a cutting tool 350 projecting a pressurized water jet 351. The cutting of the bonding portions can be carried out using other cutting tools such as a laser beam or a blade. The fiber blank is thus held in the holding tooling during cutting, which ensures high cutting accuracy and very good repeatability.

[0046] As shown in [Fig. 7], a fibrous tube preform 200 is obtained, exhibiting a 3D weave with near-continuity of the fibrous network over the entire cylindrical wall of the preform. It is thus possible to manufacture composite material tubes from this preform with material health, i.e., mechanical properties, that are far superior to those of tube preforms manufactured according to the prior art.

[0047] As illustrated in [Fig. 7], part of the holding tooling is disassembled. More specifically, the upper wedge 320, the first pair of side flanges 330 and 331 and the second pair of side flanges 340 and 341 are disassembled while the fibrous tube preform 200 is held in the reference position on the lower wedge 310.

[0048] Figure 8 illustrates a compaction step of the fiber preform 200, which allows, in particular, adjustment of the fiber volume fraction in the preform. The holding tool 300 is reassembled with a first lateral wedge 360 ​​and a second lateral wedge 361 interposed between the lower and upper wedges 310 and 320 on each side of the fiber preform. A compaction pressure Pc is then applied to each of the wedges, which allows the fiber preform 200 to be compacted in four directions. The wedges are designed with reference marks to determine their exact position relative to the fiber preform and thus control the level of compaction applied and, consequently, the fiber volume fraction in the preform. The compaction force can be applied by using presses on the wedges or by clamping the wedges.As an example, the PC compaction pressure applied to each of the wedges can be 15 bars, which makes it possible to achieve a fiber volume percentage of approximately 60%.

[0049] The fibrous preform is moistened with water before compaction, for example before cutting the bond portions 105 and 107 or when it is still at the stage of the fibrous rough 100. The water acts as a lubricant which facilitates the sliding between the yarns, which reduces disturbances or disruptions to the initial weave during shaping and compaction.

[0050] The fibrous preform, held in its shape and compacted state within the holding tool, is placed in an oven or similar device to dry it, for example, at a temperature of 120°C for a 12-hour cycle. In addition to facilitating sliding between the fibers during compaction, moistening the preform allows the sizing present in the fibers to dissolve and diffuse into the blank. Drying the fibrous preform removes the water present within it and solidifies it in its compacted state through the hardening of the sizing, even after its removal from the holding tool.

[0051] The fibrous preform 200 is then densified to obtain the final part, here a tube 400 made of composite material, as illustrated in [Fig. 9]. The densification is carried out in a manner known per se, using the liquid process. The liquid process consists of impregnating the preform with a liquid composition containing a precursor of the matrix material. The precursor is usually in the form of a polymer, such as a high-performance epoxy resin, possibly diluted in a solvent. The preform is placed in a mold that can be sealed tightly with a cavity having the shape of the final molded tube. The mold is then closed, and the liquid matrix precursor (for example, a resin) is injected into the entire cavity to impregnate the entire fibrous portion of the preform.

[0052] The transformation of the precursor into a matrix, namely its polymerization, is carried out by heat treatment, generally by heating the mold, after the removal of a possible solvent and polymer crosslinking, the preform always being held in the mold having a shape corresponding to that of the part to be produced.

[0053] In the case of forming a carbon or ceramic matrix, the heat treatment consists of pyrolyzing the precursor to transform the matrix into a carbon or ceramic matrix, depending on the precursor used and the pyrolysis conditions. For example, liquid carbon precursors can be resins with a relatively high coke content, such as phenolic resins, while liquid ceramic precursors, particularly SiC, can be polycarbosilane (PCS), polytitanocarbosilane (PTCS), or polysilazane (PSZ) type resins. Several consecutive cycles, from impregnation to heat treatment, can be carried out to achieve the desired degree of densification. Alternatively, an epoxy resin with a temperature class of 180 °C (maximum temperature withstood without loss of properties) can be used.The choice of temperature class and / or chemical nature of the resin is determined according to the thermomechanical stresses to which the part must be subjected.

[0054] The densification processes described above make it possible to produce, from the fibrous preform of the invention, mainly parts such as blades or propeller blades in organic matrix composite material (CMO), carbon matrix (C / C) and ceramic matrix (CMC).

[0055] In the example described here, the fibrous tube preform 200 is intended for manufacturing a blade or propeller root made of composite material for unshod drive wheels of a turbomachine. In this case, the fibrous preform may be a portion of a root preform located in the extension of a portion of a blade preform of a fibrous blade or propeller preform. Also in the case of manufacturing a blade or propeller root made of composite material for unshod drive wheels of a turbomachine, a metallic insert or internal sleeve is introduced into the internal housing of the tube preform. The insert may also be the cylindrical forming element, which in this case is made of a material compatible with the application of the part.In addition, an external shell, for example made of metal, can be placed around the tube preform or the composite material tube to allow the integration of the blade or propeller into a rotor disc.

Claims

1. Demands A method for manufacturing a fibrous tube preform intended to form the fibrous reinforcement of a part or a portion of a part made of composite material, the method comprising: - the production by three-dimensional weaving of a one-piece fibrous blank (100) between a plurality of layers of warp yarns (101) extending along a longitudinal direction (DL) and a plurality of layers of weft yarns (102) extending along a transverse direction (DT), the warp yarns (101) being woven in a plurality of columns spaced apart along the transverse direction (DT), the fibrous blank having a flat shape extending along a longitudinal direction (DL) between first and second longitudinal ends (100a, 100b) and along a transverse direction (DT) between first and second lateral ends (100c, 100d), the fibrous blank comprising a debonding (103) extending over the entire fibrous blank along the longitudinal direction (DL), the debonding (103) extending along the transverse direction (DT) between first and second unbinding fund (103b,103c) located back from the first and second lateral ends (100c, 100d) of the fiber blank so as to retain first and second bonding portions (105, 107) on each side of the unbonding, the unbonding (103) defining an internal cavity (140) opening at the first and second longitudinal ends (100a, 100b) of the fiber blank (100), a first portion of yarns (T3, T4) from the plurality of weft yarn layers (102) crossing a second portion of yarns (T5, T6) from the plurality of weft yarn layers at the level of the first unbonding base (103b) and at the level of the second unbonding base (103c), - the placement of a cylindrical forming element (130) in the internal cavity (140) of the fiber blank (100) so as to form a preform portion tubular (210), - the removal of the first bond portion (105) by cutting along a thickness direction (DE) of the fibrous blank perpendicular to the longitudinal (DL) and transverse (DT) directions, the cutting being carried out in a first cutting zone (ZCi) located at least two columns of warp yarns and at most three columns of yarns of the first unlinking bottom (103b) along the transverse direction (DT), - the removal of the second linking portion (107) by cutting along the thickness direction (DE) of the fibrous blank, the cutting being carried out in a second cutting zone (ZC2) located at least two columns of warp yarns and at most three columns of warp yarns from the second unlinking bottom (103c) along the transverse direction (DT) so as to obtain a fibrous tube preform (200).

2. Method according to claim 1, wherein the fibrous blank (100) has on one face first and second tracer wires (150, 151) aligned respectively with the first and second cutting zones (ZCi, ZC2).

3. A method according to claim 1 or 2, wherein, before the removal of the first and second connecting portions (105, 107), the fibrous blank (100) with the cylindrical forming element (130) present in the internal housing (140) is placed in a holding tool (300) comprising a lower wedge (310) and an upper wedge (320) between which the tubular preform portion (210) is held, the upper wedge (320) having first and second slots (321, 322) respectively opposite the first and second cutting zones (ZCi, ZC2), the cutting of the first and second connecting portions (105, 107) being carried out by a cutting tool (350) through the first and second slots.

4. Method according to claim 3, wherein the holding tooling (300) comprises in addition a first pair of lateral flanges (330, 331) between which the first bonding portion (105) of the fibrous blank (100) is held and a second pair of lateral flanges (340, 341) between which the second bonding portion (107) of the fibrous blank is held.

5. Method according to claim 3 or 4, comprising, after cutting the first and second bonding portions (105, 107), compacting the fibrous tube preform (200) by the lower and upper wedges (310, 320) of the holding tool (300) and by lateral wedges (360, 361) arranged on each side of said fibrous tube preform.

6.

7.

8.

9.

10. Method according to any one of claims 3 to 5, wherein the lower and upper wedges (310, 320) of the holding tool (300) each have a groove-shaped imprint (312, 323) cooperating with a portion of the tubular preform portion (210) of the fibrous blank (100). A method according to claim 5 or 6, wherein the preform is moistened before compaction. A method according to claim 7, wherein the preform is dried after compaction. A method according to any one of claims 1 to 8, wherein the fibrous tube preform (200) corresponds to a part of the foot preform of a blade or propeller. Method of manufacturing a tubular part in composite material comprising manufacturing a fibrous tube preform (200) according to any one of claims 1 to 9 and densifying said fibrous tube preform with a matrix.

Images