A method for manufacturing a fiber preform of a brake disc having an extended service life

Abstract

The present invention relates to a method of manufacturing a fiber reinforcement of a composite brake disc, comprising: producing (E10) a plurality of fiber portions (11) using a tailored fiber placement technique, each of said plurality of fiber portions intended to define a different friction face (F1) of the brake disc, wherein, for each of said plurality of fiber portions, carbon or carbon precursor fibers are laid down on a substrate and stitched to the substrate by a thread made of carbon or polymeric material; positioning (E20) an intermediate fiber portion (13) between said plurality of fiber portions, the intermediate fiber portion intended to define a non-friction area of the brake disc; and assembling (E30) the intermediate fiber portion (13) with said fiber portions (11).

Description

Technical Field

[0001] This disclosure relates to a method for manufacturing a brake disc fiber preform, in which at least the friction region is formed using custom fiber layup (TFP) technology to increase the Z-fiber ratio and heat dissipation capacity during operation. The invention also relates to the manufacture of related brake discs. Background Technology

[0002] Brake discs with extended service life are desired. Summary of the Invention

[0003] This disclosure relates to a method for manufacturing a fiber preform intended to form a fiber reinforcement of a brake disc made of a composite material, the method comprising:

[0004] A first fiber portion and a second fiber portion are produced using a custom fiber layup technique. Each of the first and second fiber portions is designed to define a different friction surface of the brake disc. For each of the first and second portions, carbon or carbon precursor fibers are laid on a substrate and sewn to the substrate with stitches made of carbon or polymer materials.

[0005] The intermediate fiber portion is positioned between the first fiber portion and the second fiber portion, the intermediate fiber portion being designed to define the non-friction area of ​​the brake disc, and

[0006] The intermediate fiber portion is assembled with the first fiber portion and the second fiber portion.

[0007] In the following text, the custom fiber placement technology will be referred to as "TFP technology".

[0008] This invention relates to the use of TFP technology in the manufacture of friction surfaces for brake discs. By selecting threads made of carbon or polymer as stitching, these stitches increase the Z-fiber ratio, thereby providing more heat dissipation channels to limit the temperature rise of the brake disc during operation and thus extend its service life. These stitches have a Z-direction component, and the Z-fiber ratio is increased solely by the presence of these stitches. The material used for these threads also endows them with the ability to be transferred in the Z direction, and, as will be detailed below, assembly with non-friction parts can be performed by transferring the stitches in the Z direction; the invention is not limited to this variant. Furthermore, compared to cutting brake discs from a pre-obtained block of material, the use of TFP technology advantageously reduces material loss and additional machining during the manufacture of the preform. TFP technology enables the direct acquisition of the final shape or a shape very close to the final shape (approaching a mesh shape) after layup.

[0009] In one exemplary embodiment, assembly is accomplished by stitching.

[0010] The needlework allows for the transfer of the suture in the Z-direction.

[0011] Specifically, each of the first and second parts can have a Z-direction transfer suture ratio between 1% and 8% after assembly. This feature corresponds to the contribution of the sutures used in TFP technology to the Z-fiber ratio.

[0012] The Z-fiber ratio (ZFP) in a given region is a quantity known to those skilled in the art; it corresponds to the ratio of the fiber volume extending along the preform thickness direction (Z-direction) to the preform volume. The Z-fiber ratio can be determined through morphological analysis (image analysis). In this case, cutting is performed in the XY plane; therefore, the fibers are perpendicular to this plane, and the Z-fiber ratio is inferred by counting the cross-sectional areas of the fibers. The Z-fiber ratio corresponds to the sum of the cross-sectional areas of the fibers in the Z-direction divided by the total area of ​​the analyzed region (fibers + pores). The Z-fiber ratio can also be determined using tomographic analysis (a non-destructive method).

[0013] However, the present invention is not limited to assembly by stitching; other techniques may also be used. Therefore, according to one variant of the invention, assembly can be accomplished by tufting.

[0014] In one exemplary embodiment, the suture is made of carbon.

[0015] In one variant, the sutures are made from a carbon precursor polymer.

[0016] In one exemplary embodiment, the substrate is a carbon sheet or a carbon precursor material sheet.

[0017] This disclosure also relates to a method for manufacturing a brake disc made of composite materials, comprising (a) manufacturing a fiber preform by performing the method described above, and (b) densifying the preform with a matrix. The brake disc may be made of carbon or carbon composite materials. The brake disc may be mounted on a vehicle, such as an aircraft, like an airplane or helicopter. Attached Figure Description

[0018] ( Figure 1 ) Figure 1 This is a flowchart illustrating the sequence of steps in an example of the method according to the present invention.

[0019] ( Figure 2 ) Figure 2 A schematic cross-sectional view along its thickness direction is shown of an example of a first or second fiber portion that can be used within the scope of the present invention.

[0020] ( Figure 3 ) Figure 3 The diagram schematically illustrates the production of the first or second fiber portion using TFP technology.

[0021] ( Figure 4 ) Figure 4 The diagram schematically illustrates the positioning of the intermediate fiber portion between the first fiber portion and the second fiber portion.

[0022] ( Figure 5 ) Figure 5 A schematic cross-sectional view along the thickness direction of an example of a fiber preform according to the invention is shown. Detailed Implementation

[0023] The invention will now be described with reference to the accompanying drawings, which are descriptive illustrations given to illustrate certain embodiments of the invention and should not be construed as limiting the invention.

[0024] The first and second fiber portions, each designed to define different friction surfaces of the brake disc, are produced using TFP technology (step E10). During the production of each of the first and second portions, fibers are laid on a substrate and sewn to the substrate with thread made of carbon or polymer material.

[0025] Figure 2 A schematic diagram illustrates a fiber portion 11 (the aforementioned first or second fiber portion) designed to define a friction surface, obtained via TFP technology. This portion 11 comprises multiple stacked fiber layers 111 sewn to the same substrate. The substrate is not... Figure 2 As shown in the image.

[0026] The process of producing part 11 by implementing TFP technology is as follows: Figure 3 As shown, a roving 111a, composed of multiple filaments, is laid on a substrate S and then sewn to the substrate via thread 111b. The roving 111a is unwound through a guide element EG, which has two openings OEG1 and OEG2, through which the roving 111a is laid. A needle A, moving perpendicular to the substrate S, guides the thread 111b to sew the roving 111a to the substrate S.

[0027] The sewn roving 111a is laid out in a plane P defined by the X and Y directions to form a first layer 111. Within the same layer 111, the sewn roving 111a can be oriented in a single direction, or as... Figure 3 As shown in the example, the roving is oriented in multiple different directions. Continue laying the roving 111a until the required area of ​​layer 111 is obtained. Once the first layer 111 is complete, begin laying the second layer 111 covering the first layer 111, proceeding in a similar manner to that just described. Continue in this way, forming the required number of layers 111. Multiple layers of roving 111a are thus stacked to form part 11. The orientation of the roving 111a between two different layers 111 can be the same or different.

[0028] Position the first fiber portion and the second fiber portion 11 on both sides of the intermediate fiber portion 13, which is intended to define the non-friction area of ​​the brake disc (step E20). Figure 4 Part 13 can also be obtained using TFP technology, or through traditional techniques of stacking and stitching fiber sheets. The substrate S on which each part 11 is sewn is not... Figure 4 As shown in the diagram, the substrate S can be made of a material intended to be retained in the brake disc obtained after matrix densification. Therefore, the substrate S can be a carbon sheet or a sheet of carbon precursor material such as oxidized or unoxidized polyacrylonitrile. According to one variant, the substrate S can be made of a volatile material that is removed during a heat treatment process following the formation of the fiber reinforcement. In this case, the substrate S can be a polyvinyl alcohol (PVA) sheet.

[0029] Section 13 includes multiple stacked fiber layers 131. Layers 131 may be unidirectional or multidirectional fiber layers. The intermediate section may include an outer circumferential region that includes at least one tenon region 14.

[0030] The fibers forming portions 11 and 13 may be carbon fibers, such as carbon fibers sold under the label HexTow® AS4, or fibers such as polyacrylonitrile (which may be oxidized or unoxidized) carbon precursors.

[0031] Then, portion 13 can be assembled with portion 11 by transferring fibers 15 from portion 11 and / or 13 in the Z-direction (step E30). Figure 5 This transfer is carried out using techniques known per se, such as needle stitching. Needle stitching is a known mechanical bonding method in which a barbed needle penetrates the fiber structure, and the fibers become entangled in the needle. This causes the fibers to transfer from one fiber layer to another in the Z direction (i.e., along the thickness direction of the preform), thereby establishing a mechanical bond between the fiber layers in that direction. According to one variant, the assembly of part 13 with part 11 (E30, Figure 5 It is done through tufting, and it should be understood that stitching and tufting techniques can be used in combination.

[0032] Thus obtained Figure 5 The brake disc preform 1 is shown.

[0033] The fiber preform 1 may have an annular shape surrounding a central through-hole 20. Multiple portions 11 are each designed to define a different friction surface F1 of the brake disc. The multiple portions 11 are surface portions of the fiber preform 1. The thickness e11 of each portion 11 may account for 10% to 25% of the total thickness e1 of the fiber preform 1, for example, 15% to 25%. The thickness e11 may be between 2 mm and 20 mm. A portion 13 may define a central portion of the thickness of the fiber preform 1.

[0034] Figure 5 Vertical assembly lines 15 extending along the Z-direction are shown, for example, penetrating the entire thickness of the fiber preform 1. These lines enable the assembly of layer 111 of portion 11 with layer 131 of portion 13. Figure 5 As shown, the maximum dimension of part 13 is greater than the maximum dimension of part 11, thus defining the tenon region 14 that protrudes beyond part 11 (see Figure 5 The tenon region 14 is designed to define the tenon of the brake disc that mates with the recess of the wheel to be braked. Unless otherwise specified, the maximum dimension is measured perpendicular to the Z direction. The thickness e13 of portion 13 may be greater than the thickness of each portion 11. The thickness e13 of portion 13 may account for 50% to 90% of the total thickness e1 of the fiber preform 1. The thickness e13 may be between 10 mm and 40 mm. The fiber preform 1 comprises a stack of multiple fiber layers 111 and fiber layers 131. The fiber preform 1 is not helical. Typically, the thickness e1 of the fiber preform 1 may be between 15 mm and 50 mm. It should also be noted that the preform 1 may be symmetrical with respect to a plane of symmetry perpendicular to the Z direction, which makes the deformation under thermal load more uniform.

[0035] Fiber preform 1 is designed to form a fiber reinforcement for brake discs, particularly brake discs made of carbon / carbon composite materials. This brake disc can be integrated into aircraft, such as airplanes or helicopters.

[0036] This method can be continued by densifying the preform 1 with a matrix (e.g., a carbon matrix) (step E40). In the case where the sutures are made of a carbon precursor, the precursor is pyrolyzed to convert the sutures into carbon before the matrix material is introduced into the pores of the preform 1.

[0037] The densification step is a known step in itself. The matrix can be obtained wholly or partially by chemical vapor infiltration (CVI) or by polymer impregnation pyrolysis (PIP). If desired, these two techniques can be combined. Finishing can then be performed, and a protective composition, for example to improve its oxidation resistance, can be applied to the surface of the brake disc, before the brake disc is integrated into the vehicle braking assembly in a manner known in itself.

Claims

1. A method for manufacturing a fiber preform (1), said fiber preform being intended to form a fiber reinforcement of a brake disc made of a composite material, said method comprising: A first fiber portion (11) and a second fiber portion (12) are produced using a custom fiber layup technique (E10), each designed to define a different friction surface (F1) of the brake disc. For each of the first and second portions, carbon or carbon precursor fibers are laid on a substrate and sewn to the substrate using sutures made of carbon or polymer materials. The intermediate fiber portion (13) is positioned (E20) between the first fiber portion and the second fiber portion, the intermediate fiber portion being intended to define the non-friction area of ​​the brake disc, and The intermediate fiber portion is assembled with the first fiber portion and the second fiber portion (E30).

2. The method according to claim 1, wherein, The assembly (E30) is completed by stitching.

3. The method according to claim 2, wherein, Each of the first part (11) and the second part (11) has a Z-direction transfer suture ratio between 1% and 8% after assembly (E30).

4. The method according to claim 1, wherein, The assembly (E30) is accomplished by tufting.

5. The method according to any one of claims 1 to 4, wherein, The sutures are made of carbon.

6. The method according to any one of claims 1 to 4, wherein, The suture is made of a precursor polymer.

7. The method according to any one of claims 1 to 6, wherein, The substrate is a carbon sheet or a carbon precursor material sheet.

8. A method for manufacturing a brake disc made of a composite material, comprising (a) manufacturing a fiber preform (1) by the method according to any one of claims 1 to 7, and (b) densifying the preform with a matrix (E40).

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