Method for manufacturing a tubular fibrous preform

Abstract

A method for manufacturing a tubular fibrous preform comprises: • - placing a portion (110) of a moistened fibrous blank (100) on a sheet (10) of flexible material, • - positioning a part (20) of circular section on said at least one portion (110) of the first fibrous blank (100), • - winding the portion (110) of the fibrous blank (100) around the part (20) of circular section, • - circular clamping of the sheet (10) of flexible material so as to compact the portion (110) of the fibrous blank (100), • - drying the fibrous blank, • - removing the sheet (10) of flexible material so as to obtain a tubular fibrous preform or a preform with a tubular preform portion.

Description

[0001] Description

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

[0003] Technical Field

[0004] The present invention relates to the field of fibrous preforms used to produce parts from composite materials. It relates more particularly to the shaping and compaction of tubular fibrous preforms.

[0005] Previous technique

[0006] The new generation of unfaired engines (known as "open fan" or "open rotor" engines) requires more compact blade feet. 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). This requirement, combined with the fact that the blade must be integrated as low as possible on the rotor disc, necessitates a significant reduction in the size of the foot.

[0007] For this purpose, the feet of the new generation blades have an axisymmetric or substantially axisymmetric shape and reduced dimensions like the blade disclosed in document WO 2023 / 209289.

[0008] The blade foot is formed from a tubular foot preform produced by three-dimensional weaving and incorporating an internal housing. The foot preform is shaped by inserting a metallic insert or sleeve into the internal housing. An external metallic shell is then attached to the outer surface of the foot preform.

[0009] However, the tube shaping of the foot preform part and its compaction can prove tricky when these two operations are carried out on a preform interposed between an insert and an outer shell.

[0010] Description of the invention

[0011] It is therefore desirable to be able to offer a solution for the production of tubular fibrous preforms which allows for improved control of the shaping and compaction of a fibrous preform when it is intended to be integrated between an insert and an external part.

[0012] To this end, the present invention proposes a method for manufacturing a tubular fibrous preform or part of a tubular preform intended to form the fibrous reinforcement of a part or part of a part made of composite material, the method comprising:

[0013] - the three-dimensional weaving of at least a first fibrous rough draft,

[0014] - the placement of at least part of the first fibrous roughing on an internal surface of a sheet,

[0015] - the moistening of the first fibrous blank before or after placing part of the first fibrous blank on the inner surface of the sheet,

[0016] - the positioning of a forming part on the first fibrous blank,

[0017] - the winding of the first fibrous blank around the forming piece,

[0018] - the circular clamping of the sheet in order to compact the fibrous part of the first rough draft,

[0019] - the drying of said first fibrous rough-out,

[0020] - the removal of the sheet so as to obtain a tubular fibrous preform or a preform with a part of a tubular preform.

[0021] Using a sheet as a forming tool and clamping this sheet in a circular fashion allows for both great flexibility in shaping the fiber blank and precise control of the clamping force. This significantly improves control over the desired dimensions and compaction, thus ensuring good manufacturing repeatability. Furthermore, the forming tool is reusable.

[0022] According to a particular feature of the process of the invention, the sheet is made of flexible material.

[0023] According to a particular feature of the process of the invention, the forming piece has a circular cross-section. According to another particular feature of the process of the invention, the sheet has perforations. This facilitates the drying of the shaped and compacted fibrous blank before its extraction from the sheet.

[0024] According to another particular feature of the process of the invention, the portion of the first fibrous blank extends lengthwise along a longitudinal direction and widthwise along a transverse direction. This portion of the first fibrous blank comprises at least a first segment having a first width and a second segment having a second width less than the first width. The formed part comprises first and second segments located on the first and second segments of the portion of the first fibrous blank, respectively. The first segment of the formed part has a diameter less than the diameter of the second segment of said formed part. The process of the invention is thus perfectly suited to the shaping and compaction of tubular preforms having variable cross-sections and / or dimensions.Indeed, by adapting the dimensions of the forming part according to the width of the portions of the blank or the part of the blank intended to form a tubular preform, we obtain a resultant clamping force balanced over the entire length of the blank or the part of the blank present in the sheet.

[0025] According to another particular feature of the process of the invention, the circular clamping force applied by the sheet on said at least a part of the first fibrous rough is determined as a function of a predetermined compaction thickness.

[0026] According to another particular feature of the process of the invention, it further comprises, after winding said at least a portion of the first fibrous blank around the forming piece, winding at least a portion of a second moistened fibrous blank around said at least a portion of the first fibrous blank. This makes it possible to form tubular preforms known as "double-scarf" preforms.

[0027] According to another particular feature of the invention, the tubular preform portion corresponds to a preform portion at the base of a blade or propeller. The invention finds a particularly advantageous application in the production of preform portions at the base or propeller 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 the placement of an outer shell around the base preform portion. Controlling the dimensions of the tubular preform portion facilitates and secures the attachment of the outer shell.

[0028] The invention also relates to tooling for manufacturing a tubular fibrous preform or part of a tubular preform intended to form the fibrous reinforcement of a part or part of a part made of composite material, the tooling comprising at least one sheet, a forming piece and a plurality of circular clamping members.

[0029] According to a particular feature of the tooling of the invention, the sheet is made of a flexible material.

[0030] According to another particular feature of the tooling of the invention, the forming part has a circular cross-section.

[0031] According to another particular feature of the tooling of the invention, the sheet (10) has perforations.

[0032] Brief description of the drawings

[0033] [Fig. 1] Figure 1 is a schematic view illustrating a fibrous blank for the manufacture of a blade or propeller,

[0034] [Fig. 2] Figure 2 is a schematic view of the fibrous blank of Figure 1 arranged in a shaping and compacting tool according to one embodiment of the invention,

[0035] [Fig. 3] Figure 3 is a schematic view showing the closure of the tooling of Figure 2,

[0036] [Fig. 4] Figure 4 is a schematic view showing the compaction of the fibrous blank in the tooling of Figure 3,

[0037] [Fig. 5] Figure 5 is a schematic view of a fibrous preform obtained after compacting the fibrous blank, [Fig. 6] Figure 6 is a schematic view of the fibrous preform of Figure 5 equipped with an outer shell.

[0038] Description of the implementation methods

[0039] The invention applies generally to the manufacture of fibrous preforms or tubular preform parts formed around a circular cross-section. 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.

[0040] 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.

[0041] Figure 1 schematically illustrates a first fiber blank 100. The fiber blank 100 is obtained by three-dimensional (3D) weaving, carried out in a known manner using a Jacquard-type loom on which a bundle of warp yarns or strands is arranged in a plurality of layers of several hundred yarns each, the warp yarns being joined by weft yarns. The fiber blank 100 is woven in a single piece. The 3D weave can, in particular, be an interlock weave. By interlock weave, we mean here a weave structure in which each layer of weft yarns joins several layers of warp yarns, with all the yarns in the same weft column having the same movement within the plane of the weave. Other known types of three-dimensional weaves may be used, such as those described in document WO 2006 / 136755.The fibrous blank according to the invention can be woven in particular from carbon fiber yarns or ceramic such as silicon carbide.

[0042] The fiber blank 100 extends lengthwise along a longitudinal direction DL and widthwise along a transverse direction DT. In the example described here, the fiber blank 100 includes a blank portion 110 intended to form a tubular fiber preform for a blade or propeller root. The fiber blank 100 also includes another blank portion 120 extending from the blank portion 110. The blank portion 120 is intended to form a portion of an airfoil preform or a spar preform suitable for assembly with an airfoil preform. The shaping of the blank portion 120 is not described here for the sake of simplicity.

[0043] The rough part 110 comprises a first portion 111 having along the transverse direction DT a first width hn, the first portion extending over a first length Lm along the longitudinal direction DL and a second portion 112 having along the transverse direction DT a second width 1112 less than the first width lm, the second portion 112 extending in the continuation of the first portion 111 over a length Li 12 along the longitudinal direction DL.

[0044] As illustrated in Figure 2, the blank portion 110 is placed flat on an internal surface 11 of a sheet 10 of a tubular preform manufacturing tool. The sheet 10 is preferably made of a flexible yet rigid material, for example, sheet metal. The blank portion 110 is moistened with water before or after being placed on the sheet 10. The water acts as a lubricant that facilitates sliding between the threads, thus reducing disturbances or disruptions to the initial weave during shaping and compaction.

[0045] A forming piece 20 made of rigid material, for example metal, is then positioned on the exposed face of the blank 110 as shown in Figure 2. In the example described here, the forming piece 20 has a circular cross-section. However, the forming piece can have other, more complex cross-sectional geometries, such as a figure-eight shape. More generally, any geometry without sharp edges can be considered for the forming piece, and its thickness can be constant or variable depending on the length of the piece.

[0046] As explained below, the forming piece's function is, in particular, to participate in shaping and compacting the roughing portion. In the example described here, the forming piece 20 comprises a first portion 21 located on the first section 111 of the roughing portion 110 and a second portion 22 located on the second section 112 of the roughing portion 110. The first portion 21 has a smaller diameter than the second portion. The diameter of the first portion 21 can be determined based on the existing extra width between the first and second sections 111 and 112 of the roughing portion 110 in order to maintain a constant cross-section across the entire roughing portion 110 when the latter is wrapped around the forming piece 20.In other words, the diameter of the forming part can be variable depending on the differences in width present in a fiber blank in order to compensate for the variations in cross-section after winding the fiber blank onto the part and thus allow tubular forming with a constant diameter and uniform concentric compaction over the entire length of the fiber blank or the relevant part of the fiber blank.

[0047] The sheet 10 and the rough part 110 are wrapped around the forming piece as illustrated in Figure 3, the assembly being held in place by means of circular clamping elements 30, such as clamping collars, arranged around the sheet 10.

[0048] A circular clamping force is then applied to the sheet 10 via the circular clamping elements 30 in order to complete the shaping and proceed to the compaction of the rough part 110 as illustrated in figure 4. The use of a sheet wrapped around the rough part and its clamping with circular clamping elements makes it possible to apply a concentric and, therefore, balanced compaction force at every point of the part of the rough concerned, the forming part 20 making it possible to apply a contact force on the internal part of the rough and thus participate in the compaction.

[0049] As a non-limiting example, the 100 mm fibrous preform exhibits an initial bulk of +56% compared to the target final thickness, corresponding here to the difference between an initial thickness of 30 mm and a target final thickness of 19 mm. The number of 30 circular clamping elements used is determined according to the desired clamping force. Again, in the non-limiting example described here, 30 circular clamping elements are used to apply a circular clamping force of 15 bar, which makes it possible to achieve the target thickness of 19 mm with a preform having a diameter of 100 mm.

[0050] Once the blank portion 110 has been shaped and compacted, the assembly, including the blank portion 110 held in its shaped and compacted state within the sheet 10, is placed in an oven or similar device to dry the blank portion. In addition to facilitating sliding between the fibers within the blank, moistening the preform allows the sizing present in the fibers to dissolve and diffuse into the blank. Drying the blank portion 110 removes the water present within it and fixes it in its compacted state through the hardening of the sizing. The sheet 10 may have perforations 12 that facilitate the removal of water from the fibrous blank during its drying process.

[0051] After the fibrous blank has dried, the circular clamping elements 30 and the sheet 10 are removed. A fibrous preform 200 is then obtained, as shown in Figure 5, comprising a part of a tubular preform 210 with the diameter in the compaction state targeted.

[0052] In the example described here, the preform 200 is intended for manufacturing a blade or propeller made of composite material for unshod drive wheels of a turbomachine. The tubular preform portion 210 is intended to form the root of the blade or propeller. As illustrated in Figure 6, an outer shell 50, for example made of metal, is placed around the tubular preform portion to allow the blade or propeller to be integrated into a rotor disk.

[0053] The 200 fibrous preform is then densified to obtain the final part, in this case a blade or propeller made of composite material. 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 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 shaped to match the final molded blade. 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.

[0054] The transformation of the precursor into a matrix, namely its polymerization, is achieved through heat treatment, generally by heating the mold after removing any solvent and crosslinking the polymer. The preform remains in the mold, which has a shape corresponding to that of the part to be produced. 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 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 (maximum temperature withstood without loss of properties) can be used. The choice of temperature class and / or the chemical composition of the resin is determined according to the thermomechanical stresses to which the part will be subjected.

[0055] 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).

[0056] In the example described here, the forming piece 20 is retained in the final part. However, the invention remains within the scope of the invention if the forming piece is removed after the formation of the tubular preform. The forming piece can be removed at the end of the preform manufacturing process if, for example, the mold for manufacturing the final composite part includes a piece identical to the forming piece.

[0057] According to a particular feature of the process of the invention, it may further comprise, after winding the portion 110 of the first fiber blank 100 around the forming piece 20, winding a portion of a second, moistened fiber blank around the portion of the first fiber blank. The second fiber blank may, in particular, have a weave, dimensions, and geometry similar to those of the first fiber blank. In this case, the first and second fiber blanks may be dried simultaneously after winding.According to the invention, the method for manufacturing a tubular fiber preform or a portion of a tubular preform intended to form the fiber reinforcement of a part or part of a part made of composite material is implemented using tooling available in kit form and comprising at least one sheet such as the sheet 10 described above, a forming piece such as the forming piece 20 described above, and a plurality of circular clamping elements such as the elements 30 described above. The tooling of the invention is notable in that it can be reused for the mass production of fiber preforms.

Claims

Demands

1. A method for manufacturing a tubular fibrous preform or part of a tubular preform intended to form the fibrous reinforcement of a part or part of a part made of composite material, the method comprising: - the three-dimensional weaving of at least a first fibrous rough draft (100), - the placement of at least a portion (110) of the first fibrous roughing on an internal surface (11) of a sheet (10), - the moistening of the first fibrous blank (100) before or after placing said at least a part (110) of the first fibrous blank on the inner surface (11) of the sheet (10), - the positioning of a forming part (20) on said at least a part (110) of the first fibrous blank (100), - the winding of said at least a part (110) of the first fibrous blank (100) around the forming piece (20), - the circular clamping of the sheet (10) so as to compact said at least a part (110) of the first fibrous rough (100), - the drying of said first fibrous rough-out, - the removal of the sheet (10) so as to obtain a tubular fibrous preform or a preform with a part of a tubular preform (210).

2. Method according to claim 1, wherein the sheet (10) is made of flexible material.

3. A method according to claim 1 or 2, wherein the formed part has a circular cross-section.

4. A method according to any one of claims 1 to 3, wherein the sheet (10) has perforations (12).

5. A method according to claim 3 or 4, wherein said at least one part (110) of the first fibrous blank (100) extends lengthwise along a longitudinal direction (DL) and widthwise along a transverse direction DT), said at least one part of the first fibrous blank comprising at least a first portion (111) having a first width (hn) and a second portion (112) having a second width (1112) less than the first width, and in which the forming piece (20) has first and second parts (21, 22) respectively present on the first and second portions (111, 112) of said at least one part (110) of the first fibrous blank (100), the first part (21) of the forming piece (20) having a diameter less than the diameter of the second part (22) of said forming piece.

6. A method according to any one of claims 1 to 5, wherein the circular clamping force applied by the sheet (10) on said at least a part (110) of the first fibrous blank (100) is determined as a function of a predetermined compaction thickness.

7. A method according to any one of claims 1 to 6, further comprising, after winding said at least a portion (110) of the first fibrous blank (100) around the forming piece (20), winding at least a portion of a second moistened fibrous blank around said at least a portion of the first fibrous blank.

8. A method according to any one of claims 1 to 7, wherein the tubular preform portion (210) corresponds to a preform portion of the foot of a blade or propeller.

9. Method according to claim 8, further comprising placing an outer shell (50) around the foot preform portion.

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