Method for manufacturing a tube fiber preform

Abstract

The invention relates to a method for manufacturing a tube fiber preform, the method comprising: - three-dimensional weaving of a fiber blank (100) in one piece between a plurality of layers of warp yarns (101) and a plurality of layers of weft yarns (102), the fiber blank comprising a gap (103) extending over the entire fiber blank in a longitudinal direction (DL), the gap (103) extending in a transverse direction (DT) between first and second gap bottoms (103b, 103c) distanced from the first and second lateral ends (100c, 100d) of the fiber blank so as to retain connecting portions (105, 107) on each side of the gap; - placing a forming element in a cavity (140) of the fiber blank formed by the gap so as to form a tubular preform portion; - removing the connecting portions by cutting in cutting zones located at least two warp yarn columns and at most three warp yarn columns from the gap bottom.

Description

[0001] Description

[0002] Title of the invention: Method for manufacturing a fibrous tube preform

[0003] Technical Field

[0004] The present invention relates to the field of fibrous preforms used to manufacture parts from composite materials. More particularly, it concerns the production of fibrous preforms for manufacturing tubes from composite materials.

[0005] Previous technique

[0006] Tubular composite parts are used in the aerospace industry. For example, the new generation of unfaired engines (known as "open fan" or "open rotor") requires more compact blade roots. This need arises from the requirement to be able to rotate the blade around its vertical axis 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 incorporating an internal cavity. The preform is shaped by inserting a metal insert or sleeve into the cavity. An external metal shell is then attached to the outer surface of the preform.

[0007] Document EP 3 733 386 describes a process for manufacturing composite tubes in which the fibrous preform is produced by helical winding of fibrous ribbons around a mandrel. This process does not allow for the production of continuous fibrous reinforcements sufficient to give the tube adequate mechanical strength.

[0008] Another technique for forming tubular fibrous preforms 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 can produce a stronger fibrous reinforcement, particularly when using 3D woven textile layers, its manufacture remains complex and exhibits poor repeatability. Description of the invention

[0009] It is therefore desirable to be able to propose a solution for the production of fibrous tube preforms that does not present the aforementioned disadvantages.

[0010] 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:

[0011] - 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 rough 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 rough, 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,

[0012] - the placement of a cylindrical forming element in the internal cavity of the fibrous blank so as to form part of a tubular preform,

[0013] - the removal of the first bonding 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 base along the transverse direction,

[0014] - 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.

[0015] Locating each cutting zone of the bonding sections at least two columns of warp yarns from the debonding base ensures a sufficiently strong textile bond on each side of the debonding, 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 debonding 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 debonding bases, the fibrous preform would locally exhibit a higher fiber volume percentage in the cut areas than in the rest of the preform, which would negatively impact the material health of the resulting composite part.

[0016] 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. The identification of the cutting zones is thus facilitated.

[0017] According to another particular feature 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, clamping the blank between shims significantly reduces the risk of the blank splaying again after the bonding portions are cut. According to another particular feature of the invention, the holding tooling comprises, among other things, a first pair of lateral clamps between which the first bonding portion of the fiber blank is held, and a second pair of lateral clamps 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.

[0018] According to another particular feature of the invention, the process 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 within 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 the preform remains in its reference position and it is easy to define a precise compaction ratio based on the distance between the shims and the preform.

[0019] According to another particular feature of the invention, the lower and upper clamps of the holding tool each have a groove-shaped indentation that cooperates with a portion of the tubular preform of the fibrous blank. This improves the accuracy of holding the blank and preform in their reference position during cutting and compacting operations.

[0020] 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.

[0021] According to another particular feature of the process of the invention, the fibrous preform is dried after compaction. The evaporation of the water causes the sizing to migrate and then solidify, thus maintaining the fibrous preform in its compacted state after removal from the tooling. According to another particular feature of the process of the invention, the fibrous tube preform corresponds to a portion of the base preform of a blade or propeller. The process of the invention finds a particularly advantageous application in the production of base 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 process may further include placing an outer shell around the base preform portion. Controlling the dimensions of the tube preform facilitates and secures the attachment of the outer shell.

[0022] 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.

[0023] Brief description of the drawings

[0024] [Fig. 1] Figure 1 is a schematic view illustrating a fibrous blank for manufacturing a tube preform according to one embodiment of the invention,

[0025] [Fig. 2] Figure 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 Figure 1 along a section plane ll-ll,

[0026] [Fig. 3] Figure 3 is a schematic perspective view showing the shaping of the fibrous roughing of Figure 1,

[0027] [Fig. 4] Figure 4 is a schematic perspective view of the shaped fibrous roughing of Figure 1,

[0028] [Fig. 5] Figure 5 is a schematic exploded perspective view of a holding tool in which the fibrous blank of Figure 4 is placed according to an embodiment of the invention,

[0029] [Fig. 6] Figure 6 is a schematic perspective view of the tooling of Figure 5 once assembled, showing the cutting of connecting portions of the fiber blank. [Fig. 7] Figure 7 is a schematic perspective view of a fiber tube preform.

[0030] [Fig. 8] Figure 8 is a schematic perspective view showing the compaction of the fibrous preform of Figure 7,

[0031] [Fig. 9] Figure 9 is a schematic perspective view of a composite material tube obtained from the fibrous tube preform of Figure 7.

[0032] Description of the implementation methods

[0033] 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 those found in so-called "open rotor" aircraft engines.

[0034] In the following description, examples of embodiments are described in relation to the manufacture of a blade or propeller for unshod, moving wheels of a turbomachine. However, the embodiment examples also apply to tubular parts intended for other applications.

[0035] Figure 1 shows very schematically a fibrous blank 100 intended to form the fibrous preform of a tube to be produced.

[0036] The fiber blank 100 is obtained, as schematically illustrated in Figure 1, by three-dimensional (3D) weaving carried out in a known manner using a Jacquard-type loom (not shown in Figure 1) on which a bundle of warp yarns 101 or strands is arranged in a plurality of layers extending along a longitudinal direction Di_, the warp yarns being joined by weft yarns 102 belonging to layers of weft yarns extending along a transverse direction DT. The fiber blank 100 is woven in a single piece and has a flat shape. The fiber blank 100 extends in the longitudinal direction DL between first and second longitudinal ends 100a and 100b and in the transverse direction DT between first and second lateral ends 100c and 100d.

[0037] In the illustrated example, the 3D weave is an "interlock" weave. By "interlock" weave, we mean a weave structure in which each layer of weft yarns connects several layers of warp yarns, with all yarns in the same weft column having the same movement in the plane of the weave.

[0038] Other known three-dimensional weaving types may be used, such as those described in document WO 2006 / 136755. This document describes in particular the production by weaving in one piece of fibrous reinforcement structures 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.

[0039] The fibrous blank according to the invention can be woven in particular from carbon fiber yarns or ceramic such as silicon carbide.

[0040] 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 100d (i.e. the linkage 103 does not open onto the lateral ends 100c and 100d) 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 rough 100 an internal housing 140 which opens at the longitudinal ends 100a and 100b of said rough.

[0041] A 3D interlock weave pattern of the blank 100 is shown schematically in Figure 2. Figure 2 is a partial enlarged view of a warp cross-section in a portion of the blank 100 including the unlinking zone 103 (section ll-ll in Figure 1). In this example, the blank 100 comprises eight layers Ci to Cs 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. In Figure 2, the eight warp yarn layers are linked by weft yarns Ti to Ts in the linking portions 105 and 107 of the fiber blank 100, the weft yarns extending substantially in the transverse direction DT.At the level of the unlinking 103, a first woven portion 113 comprises four layers Ci to C4 of warp yarns 101 linked together by four weft yarns Ti, T2, Ts and Te while a second woven portion 114 comprises the other four layers Cs to Cs of warp yarns 101 linked together by four weft yarns T3, T4, T7 and Ts.

[0042] In other words, the fact that the weft yarns T1, T2, Ts and Te do not extend into the warp yarn layers of the second woven portion 114 and that the weft yarns T3, T4, T? and Ts 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.

[0043] In the weaving example shown in Figure 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 Figure 2, the weft yarns T3 and T4, linking layers of warp yarns 101 of the set of yarn layers 108 in the first bonding portion 105 are deflected before the unlinking 103 to link layers of warp yarns 101 of the set of yarn layers 109. Similarly, the weft yarns Ts and Te, linking layers of warp yarns 101 of the set of yarn layers 109 in the first bonding area 105 are deflected before the unlinking 103 to link layers of warp yarns 101 of the set of yarn layers 108.After the unbinding 103, the weft yarns T3 and T4 are again deflected at the end of the unbinding 103, i.e., at their entry into the second portion of the bond 107, to bind layers of warp yarns 101 of the set of yarn layers 109, while the weft yarns Ts and Te are again deflected at the end of the unbinding 103, i.e., at their entry into the second portion of the bond 107, to bind layers of warp yarns 101 of the set of yarn layers 108. The crossing of the weft yarns T3 and T4 and the weft yarns Ts and Te 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.

[0044] Creating weft thread crossover zones between the woven sections 113 and 114, separated by the unbinding 103, allows for 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 sections 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).

[0045] Once the weaving is finished, the non-woven yarns around the 100 fibrous blank are cut to extract the blank, then the foot part of the blank is shaped.

[0046] As illustrated in Figures 3 and 4, the shaping of a portion of the tubular preform is achieved by separating the woven sections 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 can be made of metallic material or resin, for example, by additive manufacturing. The cylindrical forming element can also be made of a flexible material.

[0047] The first and second bonding portions 105 and 107 are then removed. More specifically, and according to 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 (Figure 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 (Figure 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.

[0048] According to a particular feature, the fiber blank 100 may have marker yarns on its cutting face. These marker yarns are yarns of a different color than 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 fiber blank 100 has two marker yarns 150 and 151 (Figures 2 to 5) on its upper face, allowing the cutting areas Zci and Zœ to be identified, respectively.

[0049] Preferably, before the removal of the first and second connecting portions 105 and 107, the fiber 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 fiber 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 shim 310 cooperate with holes 324 on the upper shim 320 to guide the assembly of these shims during tooling assembly (Figure 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.

[0050] 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 Zci and Zœ.

[0051] As illustrated in Figure 6, the cutting of the bond portions 105 and 107 is performed 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 bond portions can be performed 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.

[0052] As shown in Figure 7, a fibrous tube preform 200 is obtained, exhibiting a 3D weave with near-continuous fibrous network across the entire cylindrical wall of the preform. It is thus possible to manufacture composite material tubes from this preform with significantly better material health, meaning mechanical properties, than with tube preforms manufactured using prior art methods.

[0053] As illustrated in Figure 7, part of the holding tooling is disassembled. 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.

[0054] Figure 8 illustrates a compaction step of the fiber preform 200, which allows, in particular, adjustment of the fiber volume fraction within 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, compacting the fiber preform 200 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 within 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 allows a fiber volume percentage of approximately 60% to be achieved.

[0055] 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.

[0056] The fibrous preform, held in its compacted shape within the holding tooling, 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 dissolves the sizing present in the fibers and diffuses it into the blank. Drying the fibrous preform removes the water it contains and solidifies it in its compacted state through the hardening of the sizing, even after its removal from the holding tooling.

[0057] The fibrous preform 200 is then densified to obtain the final part, in this case a composite tube 400, as illustrated in Figure 9. Densification is carried out using a well-known liquid-based process. This process involves impregnating the preform with a liquid composition containing a precursor of the matrix material. The precursor is usually 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 shaped like the final molded tube. The mold is then closed, and the liquid matrix precursor (e.g., a resin) is injected into the entire cavity to impregnate the entire fibrous portion of the preform.

[0058] The transformation of the precursor into a matrix, namely its polymerization, is carried out by heat treatment, generally by heating the mold, after removal of any solvent and crosslinking of the polymer, the preform always being kept in the mold having a shape corresponding to that of the part to be produced.

[0059] In the case of carbon or ceramic matrix formation, 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 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 performed to achieve the desired degree of densification. Alternatively, an epoxy resin with a temperature class of 180 °C (the maximum temperature that can withstand it 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.

[0060] 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).

[0061] In the example described here, the 200 mm tube fiber preform is intended for manufacturing a blade or propeller root made of composite material for unshod turbine wheels. In this case, the fiber preform may be a portion of a root preform extending from a portion of a blade or propeller fiber preform. Also in the case of manufacturing a blade or propeller root made of composite material for unshod turbine wheels, 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. Furthermore, an external shell, for example made of metal, may be placed around the tube preform or the composite tube to allow the blade or propeller to be integrated into a rotor disc.

Claims

Demands

1. 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 unlinking funds (103b,103c) located set back from the first and second lateral ends (100c, 100d) of the fibrous blank so as to retain first and second bonding portions (105, 107) on each side of the unbinding, the unbinding (103) delimiting an internal housing (140) opening at the first and second longitudinal ends (100a, 100b) of the fibrous blank (100), a first part of yarns (T3, T4) of the plurality of weft yarn layers (102) crossing a second part of yarns (Ts, Te) of the plurality of weft yarn layers at the level of the first unbinding bottom (103b) and at the level of the second unbinding bottom (103c), - the placement of a cylindrical forming element (130) in the internal housing (140) of the fibrous blank (100) so as to form a part of a tubular preform (210), - the removal of the first bonding 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 threads and at most three columns of warp threads from the first unbinding bottom (103b) along the transverse direction (DT), - the removal of the second bonding portion (107) by cutting along the thickness direction (DE) of the fibrous blank, the cutting being carried out in a second cutting zone (Zcz) located at least two columns of warp wires and at most three columns of warp wires from the second unbinding 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. A method according to claim 3 or 4, comprising, after cutting the first and second connecting portions (105, 107), compacting the fibrous tube preform (200) with the lower wedges and upper (310, 320) of the holding tooling (300) and by lateral wedges (360, 361) arranged on each side of said fibrous tube preform.

6. A 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).

7. A method according to claim 5 or 6, wherein the preform is moistened before compaction.

8. A method according to claim 7, wherein the preform is dried after compaction.

9. A method according to any one of claims 1 to 8, wherein the fibrous tube preform (200) corresponds to a portion of the foot preform of a blade or propeller.

10. Method of manufacturing a tubular part of 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.

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