METHOD FOR MANUFACTURING A RING SECTOR

Abstract

The invention relates to a three-dimensionally woven multilayer fibrous structure (20) having the same number of warp yarns woven at any level along the warp direction, the fibrous structure (20) comprising, in the warp direction, a first part (22) and a second part (24), the first part (22) having a thickness measured in a direction perpendicular to the warp and weft directions, greater than the second part (24), characterised in that the spacing between two weft planes along the warp direction is greater in the second part than in the first part (22), and in that the number of weft yarns is lower in the second part (24) than in the first part (22).

Claims

1.-9. (canceled)

10. A three-dimensionally woven multilayer fibrous structure (20) having the same number of warp yarns woven at any level along the warp direction, the fibrous structure (20) comprising, in the warp direction, a first part (22) and a second portion (24), the first part (22) having a thickness measured in a direction perpendicular to the warp and weft directions, greater than the second part (24), characterised in that the spacing between two weft planes along the warp direction is greater in the second portion than in the first part (22), and in that the number of weft yarns per weft plane of the second part is lower than the number of weft yarns per weft plane of the first part, the first part (22) of the fibrous structure (20) comprising a first portion (16) and a second portion (18), the first portion (16) being arranged in said perpendicular direction, over a second portion (18) and being structurally independent of the second portion (18), said first portion (16) and second portion (18) of the first part (22) being woven to the second part (24) at a transition from the first part (22) to the second part (24).

11. A fibrous structure (20) according to claim 10, wherein the number of weft yarns is greater than the number of warp yarns in one and/or other of the first portion (16) and the second portion (18).

12. A fibrous structure (20) according to claim 10, wherein in the second part (24) the number of weft yarns is lower than the number of warp yarns.

13. A fibrous structure (20) according to claim 10, wherein the spacing between two warp planes is identical between the first part (22) and the second part (24).

14. A fibrous structure (20) according to claim 10, wherein the spacing between two warp planes is different.

15. A fibrous structure (20) according to claim 10, comprising a third part (26) identical to the first part (22) and woven to the second part (24) along the warp direction opposite the first part (22).

16. A method for manufacturing a fibrous structure (20) according to claim 10, wherein during the transition in the warp direction from the first part (22) of the fibrous texture (20) to the second part (24) of the fibrous texture (20), the number of weft yarns is reduced and the spacing between two successive weft planes along the warp direction is increased.

17. A method for manufacturing a fibrous structure (20) according to claim 10, wherein during the transition in the warp direction from the second part (24) of the fibrous texture (20) to the first part (22) of the fibrous texture (20), the number of weft yarns is reduced and the spacing between two successive weft planes along the warp direction is increased.

18. A method for manufacturing a composite material, comprising the following steps: a) Obtaining a fibrous structure (20) by means of the method according to claim 16; b) Shaping the fibrous structure (20); c) Obtaining a composite material by injecting a matrix inside the fibrous structure (20).

19. A method for manufacturing a composite material, comprising the following steps: a) Obtaining a fibrous structure (20) by means of the method according to claim 17; b) Shaping the fibrous structure (20); c) Obtaining a composite material by injecting a matrix inside the fibrous structure (20).

20. A three-dimensionally woven multilayer fibrous structure (20) having the same number of warp yarns woven at any level along the warp direction, the fibrous structure (20) comprising, in the warp direction, a first part (22) and a second portion (24), the first part (22) having a thickness measured in a direction perpendicular to the warp and weft directions, greater than the second part (24), characterised in that the spacing between two weft planes along the warp direction is greater in the second portion than in the first part (22), and in that the number of weft yarns per weft plane of the second part is lower than the number of weft yarns per weft plane of the first part, the first part (22) of the fibrous structure (20) comprising a first portion (16) and a second portion (18), the first portion (16) being arranged in said perpendicular direction, over a second portion (18) and being structurally independent of the second portion (18), said first portion (16) and second portion (18) of the first part (22) being woven to the second part (24) at a transition from the first part (22) to the second part (24); wherein the number of weft yarns is greater than the number of warp yarns in one and/or other of the first portion (16) and the second portion (18).

21. A fibrous structure (20) according to claim 20, wherein in the second part (24) the number of weft yarns is lower than the number of warp yarns.

22. A fibrous structure (20) according to claim 20, wherein the spacing between two warp planes is identical between the first part (22) and the second part (24).

23. A fibrous structure (20) according to claim 20, wherein the spacing between two warp planes is different.

24. A fibrous structure (20) according to claim 20, comprising a third part (26) identical to the first part (22) and woven to the second part (24) along the warp direction opposite the first part (22).

25. A method for manufacturing a fibrous structure (20) according to claim 20, wherein during the transition in the warp direction from the first part (22) of the fibrous texture (20) to the second part (24) of the fibrous texture (20), the number of weft yarns is reduced and the spacing between two successive weft planes along the warp direction is increased.

26. A method for manufacturing a fibrous structure (20) according to claim 20, wherein during the transition in the warp direction from the second part (24) of the fibrous texture (20) to the first part (22) of the fibrous texture (20), the number of weft yarns is reduced and the spacing between two successive weft planes along the warp direction is increased.

27. A method for manufacturing a composite material, comprising the following steps: a) Obtaining a fibrous structure (20) by means of the method according to claim 25; b) Shaping the fibrous structure (20); c) Obtaining a composite material by injecting a matrix inside the fibrous structure (20).

28. A method for manufacturing a composite material, comprising the following steps: a) Obtaining a fibrous structure (20) by means of the method according to claim 26; b) Shaping the fibrous structure (20); c) Obtaining a composite material by injecting a matrix inside the fibrous structure (20).

Description

BRIEF DESCRIPTION OF THE FIGURES

[0044] FIG. 1 described above, is a perspective view of a ring sector according to the prior art;

[0045] FIG. 2 described above, is a schematic representation of a fibrous structure for the manufacture of the ring sector of FIG. 1 obtained according to the prior art;

[0046] FIG. 3 described above, is a schematic representation of the 3D Pi conformation of the fibrous structure of a ring sector;

[0047] FIG. 4 is a schematic illustration of the fibrous structure according to the invention;

[0048] FIG. 5 is a diagram of a ring sector incorporating the fibrous structure of FIG. 4.

DETAILED DESCRIPTION OF THE INVENTION

[0049] In the embodiments detailed below, the fibrous structure woven from SiC fibres preferably has a target fibre content of between 25 and 50% by volume.

[0050] FIG. 5 is a diagram of a fibrous structure 20 according to the invention in which a warp direction C and a weft direction T and a direction E are shown, these directions being perpendicular to each other. This fibrous structure 20 has the same number of warp yarns woven at any level of the fibrous structure along the warp direction C.

[0051] The fibrous structure 20 comprises a first part 22, a second part 24 and a third part 26 along the warp direction C, best seen in the schematic illustration of the fibrous structure 20 before shaping. The first 22, second 24 and third 26 parts each have a thickness e.sub.1, e.sub.2, e.sub.3 measured in a direction E perpendicular to the warp and weft directions. In this example, the fibrous structure 20 comprises a second part 24 whose thickness e.sub.2 is lower than the thickness e.sub.1, e.sub.2 of each of the first part 22 and the third part 26.

[0052] The first 22 and third 26 parts each comprise a first portion 16 and a second portion 18. Once the fibrous structure 20 has been formed into the shape of Pi as seen in FIG. 5, the first portions 16 of the first 22 and third 26 parts are arranged to form a non-zero angle, preferably between 0° and 45°, with the second portions 18 of the first 22 and third 26 parts respectively. Prior to this shaping of the fibrous structure 20, i.e. at the end of the three-dimensional weaving, for each of the first 22 and third 26 parts, the first portion 16 is arranged above the second portion 18 along the E-direction, also called the thickness direction. The first 16 and second 18 portions, although woven simultaneously, are structurally independent, i.e. they are not woven to each other, which allows an arrangement of the first 16 portions at a non-zero angle to the second 18 portions and the second 24 part. The first 16 and second 18 portions of the first 22 and third 26 parts each have a thickness, in the E direction, of e.sub.p11, e.sub.p12, e.sub.p31 and e.sub.p32 respectively, such that e.sub.p11+e.sub.p12=e.sub.1 et e.sub.p31+e.sub.p32=e.sub.3.

[0053] For the following, it will be assumed that the thicknesses of the first and second portions are identical for the first and third parts, i.e e.sub.p11=e.sub.p31 et e.sub.p12=e.sub.p32.

[0054] Of course, it is possible that the thicknesses e.sub.1 and e.sub.3 are different, and also that the thicknesses e.sub.p11, e.sub.p31, e.sub.p12 et e.sub.p32 are different from each other in pairs.

[0055] The first portion 16 and the second portion 18 of the first part 22 are woven to the second part 24 at a transition from the first part 22 to the second part 24. The first portion 16 and the second portion 18 of the first part 26 are woven to the second part 24 at a transition from the first part 26 to the second part 24. These transitions, indicated by two boxes A and B, correspond to an intertwining of the wires from the first portion 16 and the second portion 18 of the first part 22, to form the second part 24.

[0056] The fibrous structure 20 is characterised by the spacing between two weft planes along the warp direction C being greater in the second part 24 than in the first part 22 and the third part 26. In addition, the number of weft yarns is lower in the second part 24 than in the first part 22 and in the third part 26. The number of weft yarns per weft plane of the second part may be less than the number of weft yarns per weft plane of the first part. The number of weft yarns per weft plane of the second part may be less than the number of weft yarns per weft plane of the first part. This allows the warp-weft ratio of the first 22 and third 26 parts to be influenced relative to that of the second part 24, to limit the thickness of the second part 24, without trimming. The second part 24 of the fibrous structure 20 thus has a thickness such that e.sub.2≤e.sub.1 et e.sub.2≤e.sub.3.

[0057] Table 1 below illustrates an example of a fibrous structure 12 according to the prior art, comprising a first part and a second part comprising a first portion 16 and a second portion 18, wherein the second part 14 has a thickness e.sub.2>e.sub.p12 and in particular wherein e.sub.1=e.sub.2.

TABLE-US-00001 TABLE 1 1.sup.st part 2nd Areas 1st portion portion 2nd part Number of layers 14 7 21 Number of weft planes 14 7 21 Number of warp planes 14 7 21 Warp spacing (mm) 1.25 1.25 1.25 Weft spacing (mm) 1.25 1.25 1.25 WWR (warp/weft ratio) 50/50 50/50 50/50 Moulding thickness (mm) 4 2 6

[0058] This fibrous structure 12 made in the previous technique from 21 textile layers by a three-dimensional multi-layer weaving of the fibrous structure 12 has a warp-weft ratio of 50/50 invariant in the different parts of the fibrous structure 12.

[0059] In this case, the number of layers, warp and weft planes in the second part 14 is equal to the sum of the number of layers, warp and weft planes in the first 16 and second 18 portions of the second part 14 (and the third part if applicable), respectively.

[0060] The fibrous structure 20 according to the invention makes it possible to limit the thickness e.sub.2 of the second part 24, intended to form the bathtub, so that its thickness e.sub.2 is close to the thickness e.sub.p12 of the second portion 18 of the first part 22 (and the third part 26 if applicable). In other words, e.sub.1, e.sub.2 and e.sub.3 can thus be different and this without trimming.

[0061] Table 2 illustrates a fibrous structure 20 according to a first embodiment of the invention, comprising a first part 22 and a second part 24 comprising a first 16 and a second 18 portion:

TABLE-US-00002 TABLE 2 1.sup.st part 2nd Areas 1st portion portion 2nd part Number of layers 14 7 21 Number of weft planes 14 7 9 Number of warp planes 14 7 21 Warp spacing (mm) 1.25 1.25 1.25 Weft spacing (mm) 1.25 1.25 1.5 WWR (warp/weft ratio) 50/50 50/50 74/26 Moulding thickness (mm) 4 2 4.1

[0062] The thickness e.sub.2 of the second part 24 of this fibrous structure 20, once shaped, is reduced to 4.1 mm, with parameters for the first 16 and second 18 portions of the first part 22 unchanged from table 1 illustrating the prior art. For this purpose, the spacing between two weft planes along the warp direction is increased from 1.25 mm to 1.5 mm so that it is greater than the spacing between two consecutive weft planes in the first part 22, in particular in the first 16 and second 18 portions of the first part 22. Furthermore, the number of weft yarns of the second part 24 is lower than the sum of the numbers of weft yarns of the first part 22, i.e. the sum of the weft yarns of the first 16 and second 18 portions of the first part 22, by locally disengaging weft yarns at the transition A between the first 22 and second 24 parts, in order to achieve a warp-weft ratio close to the 75/25 limit.

[0063] Thus, the combination of increasing the spacing between two consecutive weft planes and not inserting weft yarns locally, so as to reduce the weft planes [, unbalances the warp-weft ratio, in the example shown at 74/26. This allows the thickness e.sub.2 of the second part 24 of the fibrous structure 20 intended to form the bathtub of the ring sector to be reduced by 1.9 mm compared to the prior art fibrous structure 12 illustrated in table 2.

[0064] Thus, in the second part 24 of the fibrous structure 20, the number of weft yarns is lower than the number of warp yarns, respectively 9 and 21. For practical reasons, the imbalance in the warp-weft ratio is achieved by adjusting the spacing between two successive weft planes, not the spacing between two successive warp planes. As a result, the distance between two warp planes is identical between the first part 22 and the second part 24.

[0065] In the particular case, not illustrated, of weaving parts at 90° to the orientation presented in this document, it is possible to play with the spacing between two successive warp planes and keep the spacing between two successive weft planes constant.

[0066] Although the example illustrated here describes the particular situation with a fibrous structure 20 having a first 22 and second 24 part, the fibrous structure 20 may comprise a third part 26 identical to the first part 22 and woven to the second part 24 along the warp direction opposite the first part 22.

[0067] Table 3 illustrates a fibrous structure 20 according to a first embodiment of the invention, comprising a first part 22 and a second part 24 comprising a first 16 and a second 18 portion:

TABLE-US-00003 TABLE 3 1.sup.st part 2nd Areas 1st portion portion 2nd part Number of layers 10 6 16 Number of weft planes 15 7 16 Number of warp planes 10 6 16 Warp spacing (mm) 1.25 1.25 1.25 Weft spacing (mm) 1 1 1.5 WWR (warp/weft ratio) 35/65 41/59 55/45 Thickness obtained in 4.1 2.1 4.2 moulding (mm)

[0068] In this structure 20, the warp-weft ratio is varied in the first 16 and second 18 portions of the first part 22, in order to reduce the number of textile layers subsequently woven in the second part 24.

[0069] Thus, in the second portion 18 of the first part 22, the number of weft planes is greater than the number of warp planes. In the first portion 16 of the first part 22, the number of weft planes is 1.5 times the number of warp planes. The spacing between two successive weft planes in the first 16 and second 18 portions is reduced to 1 mm.

[0070] The modification of these parameters, unbalancing the warp-weft ratio of the first 16 and second 18 portions to 41/59 and 35/65 respectively, combined with an increase in the spacing between two successive weft planes, thus makes it possible to obtain, for a thickness of 2.1 mm and 4.1 mm respectively for the first 16 and second 18 portions of the shaped fibrous structure 20, a thickness e.sub.2 of the second part 24 equal to 4.2 mm.

[0071] In this example of a fibrous structure 20, the number of weft yarns is greater than the number of warp yarns in the first portion 16 and in the second portion 18 of the first part 22 of the fibrous structure 20.

[0072] The invention also relates to a fibrous structure 22, the thickness of which e.sub.2 of the second portion 24 is lower than the thickness of the first portion 22, i.e. the sum of the thicknesses of the first 16 and second 18 portions. Table 4 illustrates a third embodiment of the invention:

TABLE-US-00004 TABLE 4 1.sup.st part 2nd Areas 1st portion portion 2nd part Number of layers 10 6 16 Number of weft planes 15 7 7 Number of warp planes 10 6 16 Warp spacing (mm) 1.25 1.25 1.25 Weft spacing (mm) 1 1 1.5 WWR (warp/weft ratio) 35/65 41/59 73/27 Thickness obtained in 4.1 2.1 3.1 moulding (mm)

[0073] Keeping the parameters of the first 16 and second 18 portion of the first part 22 of the fibrous structure 20 of the example in table 3, the thickness of the second part 24 is further reduced, changing the warp-weft ratio to 73/27 by reducing the number of weft planes of the second part 24 of the fibrous structure 20 from 16 to 7.

[0074] A thickness of 3.1 mm is then obtained for this second part 24 compared to 4.2 mm for the structure described with reference to table 3.

[0075] Thus, the invention also relates to the method of making the fibrous structures 20 as described with reference to tables 2 to 4.

[0076] The method for manufacturing the weaving of a fibrous structure 20 according to the invention thus comprises a step consisting of decreasing the spacing between two successive weft planes along the warp direction and decreasing the number of weft yarns during a transition in the warp direction from a first part of the fibrous texture to a second part 24 of the fibrous texture 20 having a thickness greater than that of the first part 22.

[0077] The manufacturing process also includes a step of increasing the number of weft yarns and decreasing the spacing between two successive weft planes along the warp direction, during the transition in the warp direction from the second part 24 of the fibrous texture 20 to the first part 22 of the fibrous texture 20.

[0078] The resulting fibrous structures 20 can then be used to manufacture a composite part, for example a stator sector 12, as described above.

[0079] Thus, the invention also relates to a method for manufacturing a composite material, comprising the following steps:

[0080] a) Obtaining a fibrous structure 20 by means of the method as presented above;

[0081] b) Shaping the fibrous structure 20;

[0082] c) Obtaining a composite material by injecting or densifying a matrix inside the fibrous structure.

[0083] Step b) consists in obtaining from the fibrous structure 20 a fibrous preform intended to form the fibrous reinforcement of the composite part. This fibrous preform has a shape similar to that of the composite part. Thus, in the example of a stator sector 12 as described above, the woven fibrous structure 20 is “Pi” shaped, that is, the first portions 16 of the first 22 and third 26 parts of the fibrous structure 20, are arranged so as to form an angle with the second portions 18 of the first 22 and third 26 parts and with the second part 24 (the latter three being substantially aligned). This is done with the help of shaping tools, allowing the preform to be held in a shape close to that of the part to be manufactured.

[0084] The composite part is then obtained by densifying the fibrous preform, i.e. by injecting a matrix inside the shaped fibrous structure. The matrix may be a resin or, in the case of a thermostructural composite, a refractory material such as carbon or ceramic.

[0085] The matrix injection can be carried out for example by Chemical Vapour Infiltration (CVI), by the process known by the acronym PIP for Polymer Infiltration and Pyrolysis or any other process conventionally known for the design of CMC parts.