DRYING AND COMPACTION MOLD FOR A FIBROUS PREFORM

Abstract

The invention relates to a drying mold (10) for a fibrous preform comprising at least one portion (11) having internal faces (13.1-13.5) defining an cavity (14) of the mold (10) against which the fibrous preform, moistened with a wetting liquid, is intended to come into contact for shaping. This portion (11) has a porous structure allowing the passage of the wetting liquid through this portion of the mold (10). The porous structure of this portion (11) consists of a plurality of interwoven filaments (17) defining through openings (18) allowing the passage of the wetting liquid. Figure 1

Description

[0023] [Fig.4] Fig.4 shows the detail of the lacunar structure of the part comprising the imprint of the compaction and drying mold according to the invention.

[0024] It should be noted that, in the figures, structural and / or functional elements common to the different embodiments may have the same reference numerals. Thus, unless otherwise stated, such elements have identical structural, dimensional and material properties.

[0025] Figures 1, 2, and 3 show a mold 10 for drying and compacting a fibrous preform (not shown) comprising a part 11 having a gap structure and a part 12 playing a role of mechanical reinforcement and / or airtight envelope surrounding the first part 11.

[0026] The part 11 having a porous structure comprises internal faces 13.1-13.5 defining a cavity 14 of the mold 10 against which the fibrous preform, moistened with a wetting liquid, in particular water, is intended to come into contact for shaping. The part 11 having a porous structure allows the passage of the wetting liquid through said part of the mold 10.

[0027] Part 12, having a rigid structure, is intended in this case to provide force transfer during a compaction operation of the fibrous preform by means of a counterform cooperating with the cavity 14 of the mold 10. Part 12, having a rigid structure, is arranged around part 11, having a porous structure. Part 12, having a rigid structure, has a higher density than part 11, having a porous structure.

[0028] More specifically, the part 11 having a lacunar structure comprises two opposing and parallel lateral walls 15.1, 15.2. The lateral walls 15.1, 15.2 each comprise an internal face 13.1, 13.3, respectively. These walls 15.1, 15.2 are connected by two other opposing and generally parallel lateral walls 15.3, 15.4. The lateral walls 15.3, 15.4 each comprise respectively an internal face 13.2, 13.4. Part 11 also has a bottom wall 15.5 comprising the internal face 13.5. Part 11 having a lacunar structure thus has a parallelepiped shape open in a direction D perpendicular to the bottom 15.5 to receive the fibrous preform.

[0029] As illustrated by [Fig.4], the part 11 having the lacunar structure is made up of a plurality of interlaced filaments 17 defining through openings 18.

[0030] According to an example embodiment, a gap L1 between two adjacent filaments 17 is between 0.2 mm and 2 mm, or even between 0.2 mm and 1 mm. Below 0.2 mm, the filaments 17 are likely to stick together, thus making the area "watertight," which is contrary to the objective. Furthermore, a gap that is too small hinders the drainage of the wetting liquid. Beyond 2 mm, the preform could be marked and / or deformed by the mold fibers. A width L2 or a diameter of a filament 17 is, for example, between 0.2 mm and 1 mm, or even between 0.2 mm and 0.5 mm.

[0031] The gap structure may comprise a plurality of first filaments 17 parallel to each other extending along a first direction DI and a plurality of second filaments 17 parallel to each other extending along a second direction D2. In this case, the first direction DI and the second direction D2 form an angle of approximately 90 degrees with each other. Alternatively, the directions DI and D2 may form an angle of 45 degrees or any other non-zero angle suitable for the application. The gap L1 can be measured between two adjacent filaments 17 extending along the direction DI or between two adjacent filaments 17 extending along the direction D2.

[0032] Thanks to the presence of the through openings 18 between the filaments 17, the part 11 allows an internal circulation of the wetting liquid from at least one internal face to at least one external face opposite to the internal face of the part 11. In other words, the wetting liquid can pass through the part 11 from one side to the other.

[0033] Furthermore, the rigid structure of part 12 comprises two opposing and parallel lateral walls 21.1, 21.2. The lateral walls 21.1, 21.2 are connected to each other by two other opposing and parallel lateral walls 21.3, 21.4.

[0034] The internal faces of the walls 21.1, 21.2 of part 12 are in contact with the external faces of the walls 15.1, 15.2 of part 11. The internal faces of the walls 21.3, 21.4 are in contact with the external faces of the walls 15.3, 15.4 of part 11.

[0035] Part 12 thus has a parallelepiped shape defining a through opening along the direction D of the opening of part 11, which has a lacunar structure. Thus, the bottom wall 15.5 of part 11 opens onto one end of the opening made in part 12.

[0036] Part 12 is not necessarily open and may also include a bottom located opposite the bottom wall 15.5 of part 11 having a lacunar structure. However, the more open the mold 10's configuration, the more easily the moisture from the fibrous preform can escape from the mold 10. Furthermore, the mold 10 requires less material to manufacture. It will therefore be faster and less expensive to produce.

[0037] Part 12 can be made of a solid material. Part 12 therefore does not have any internal cavity that could weaken its structure.

[0038] Of course, the mold 10 is not limited to a parallelepiped shape and may have any other geometric shape suitable for the application.

[0039] Advantageously, a pneumatic fitting 23 is in fluidic communication with the part 11 having a porous structure. The pneumatic fitting 23 is fixed to the part 12 through which said pneumatic fitting 23 passes. In this case, the part 12 defines a sealed enclosure surrounding at least partially, preferably completely, the part 11 having a porous structure (except for the upper part of the part 11 having a porous structure, this open upper part being intended to be closed by a cover). For this purpose, an external or internal wall delimiting the part 12 is sealed. Alternatively, the part 12 is made of a solid material.

[0040] The pneumatic fitting 23 is intended to be connected to a vacuum pump in order to extract the wetting liquid from the preform via the part 11. This vacuum liquid extraction can be carried out in addition to drying by heating or mechanical wringing linked to the compaction force applied to the wetted fibrous preform.

[0041] Depending on the desired level of drying, vacuuming is not essential. Indeed, it is possible to perform drying only, for example at a temperature above 100°C to reach the boiling point of water, without having to use the pneumatic fitting 23.

[0042] Alternatively, it is possible to carry out drying at the same time as compaction by means of a counterform pressing the fibrous preform against the mold 10.

[0043] For optimum drying, drying can be achieved by drawing a vacuum through the mold 10. This embodiment requires closing the mold 10 and providing a vacuum bag around it so that the vacuum can extract the wetting liquid from the fibrous preform. Alternatively, a lid and a seal attached to the upper surface of part 12 can be used if part 12 has a sealed bottom or is fixed to such a bottom.

[0044] Advantageously, the part 11 having a porous structure and the part 12 having a rigid structure form a single piece. These two parts 11 and 12 are fixedly joined to each other. There may be continuity of material between the part 11 and the part 12. In particular, there may be continuity of material between the filaments 17 constituting the part 11 and the filaments 17 constituting the Part 12. To create part 11 with a porous structure, the filaments 17 are interlaced and spaced as previously described. To create part 12 with a rigid structure, the filaments 17 are arranged edge to edge to create a solid material or are spaced very close together (less than 0.2 mm, for example).

[0045] Preferably, the entire mold 10, or at least the part 11 having a porous structure, is made of amorphous thermoplastic polyetherimide (PEI) resin. Advantageously, the material used is a material of the Ultem 1010 type (registered trademark) because its glass transition temperature (Tg) of 215°C is compatible with a drying temperature of approximately 100°C. Furthermore, this material exhibits good mechanical properties. Alternatively, it is possible to use a material of the Ultem 9085 type (registered trademark) having a glass transition temperature (Tg) of 185°C.

[0046] The mold 10, or at least the part 11 having a gap structure, is preferably obtained by an additive manufacturing process using filament deposition 17. Such a manufacturing process is inherently well-suited to the part to be manufactured, insofar as the different rows of filaments can be produced sequentially by successive addition of material. Alternatively, the mold 10 can be produced by metal additive manufacturing, for example using lattice molds, or by any other manufacturing process suitable for the application.

[0047] Alternatively, the part 12 having a rigid structure is made of a metallic material, such as for example aluminium, or a plastic material.

[0048] It should be noted that, in some cases, the mold 10 can be used only for drying the fibrous preform, without suction or pressing other than that necessary to introduce the fibrous preform into the mold 10.

[0049] The invention further relates to a method for drying a fibrous preform comprising at least one step of placing the fibrous preform inside a drying mold 10.

[0050] Of course, the different features, variants and / or embodiments of the present invention can be combined with each other in various ways insofar as they are not incompatible or mutually exclusive.

[0051] Furthermore, the invention is not limited to the embodiments described above and provided solely by way of example. It encompasses various modifications, alternative forms, and other variants that a person skilled in the art may consider within the scope of the present invention, and in particular all combinations of the different modes of operation described above, which may be taken separately or in combination.

Claims

Demands

1. A method for drying a fibrous preform characterized in that said method comprises at least one step of placing the fibrous preform inside a mold (10) for drying a fibrous preform comprising at least one part (11) comprising internal faces (13.1-13.5) defining an impression (14) of the mold (10) against which the fibrous preform, wetted by a wetting liquid, is intended to come into contact for shaping, said part (11) having a porous structure allowing the passage of the wetting liquid through said part of said mold (10), the part (11) having a porous structure being constituted by a plurality of interlaced filaments (17) defining through openings (18) allowing the passage of the wetting liquid.

2. Method according to claim 2, characterized in that a gap between two adjacent filaments (17) is between 0.2mm and 2mm, or even between 0.2mm and 1mm.

3. A method according to claim 1 or 2, characterized in that the mold (10) is obtained by an additive manufacturing process by filament deposition (17).

4. A method according to any one of claims 1 to 3, characterized in that the mold (10) further comprises a part (12) having a rigid structure arranged around the part (11) having a gap structure.

5. Method according to claim 4, characterized in that the part (12) having a rigid structure has a higher density than the part (11) having a lacunar structure.

6. Method according to claim 4 or 5, characterized in that the part (12) having a rigid structure is made of a solid material.

7. A method according to any one of claims 4 to 6, characterized in that the part (11) having a gap structure and the part (12) having a rigid structure form one and the same piece.

8. A method according to any one of claims 4 to 7, characterized in that the mold (10) comprises a pneumatic fitting (23) in fluidic communication with the part (11) having a lacunar structure, the part (12) having a rigid structure defining a sealed envelope surrounding at least partially the part (11) having a lacunar structure.

9. A method according to any one of claims 1 to 8, characterized in that the part (11) having a gap structure is made of amorphous thermoplastic polyetherimide-based resin.

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