WO2020094965A1

WO2020094965A1 - Method for laying up prepreg plies

Info

Publication number: WO2020094965A1
Application number: PCT/FR2019/052612
Authority: WO
Inventors: Philippe Jean Pierre HENRIO; Magali Mélanie COULAUD; Sébastien DUNAUD; Claire DUPUIS
Original assignee: Safran
Priority date: 2018-11-06
Filing date: 2019-11-05
Publication date: 2020-05-14
Also published as: FR3088029A1; FR3088029B1

Abstract

Disclosed is a method for laying up at least one fibrous ply (100) pre-impregnated with a precursor of a matrix on a forming tool (200) comprising a main face (210) and first and second side faces (220, 230) extending perpendicular to each other and meeting at a suitcase corner (240). Each ply comprises a first edge (111) extending in a first direction (A) and a second edge (112) extending in a second direction (B) perpendicular to the first direction (A), the first and second edges (111, 112) being pressed respectively onto the first and second side faces (220, 230) of the forming tool, deforming a junction portion (120) where the edges meet on the suitcase corner (240). Each ply comprises an overlength portion (130) extending along part of the first and second edges (111, 112) at their junction portion (120), one or more tensile forces (Fri) being applied to the overlength portion during the deformation of the junction portion (120) on the suitcase corner (240).

Description

Title of invention

PROCESS FOR DRAPING PRE-IMPREGNATED FOLD

Invention background

The present invention relates to the general field of parts made of composite material having a complex geometry, in particular parts comprising one or more corners of the suitcase.

A technique for manufacturing parts of composite material having a complex geometry consists in draping one or more fibrous plies pre-impregnated with a liquid precursor of a matrix on a mold or shaping tool.

Document WO 2014/170586 describes a process for producing parts of composite material with complex geometry comprising draping a fibrous texture pre-impregnated on a mold or shaping tool.

During the draping of the pleat (s) on the shaping tool, these are deformed in order to conform to the shape of the tool. However, in the case of a part to be produced comprising a corner, known as a suitcase corner, the draping of the prepreg folds proves to be delicate and has certain drawbacks whatever the technique used.

A first technique consists in making cuts in the folds in order to facilitate their conformation on the tooling. However, due to the presence of cutouts in the folds and, consequently, of material interruption, the level of sealing at the level of the wedge formed is considerably reduced.

Another technique which does not involve cutting in the folds consists in imposing on the folds a significant deformation on the part of the shaping tool intended to allow the formation of the corner of the suitcase. However, this technique has the following drawbacks:

- excessive deformation of the fold which reduces the mechanical properties of the final part,

- absence of mark for the operator resulting in a lack of control of the deformation of the fold, - length and repetition of the handling operations in order to position and adjust the fold causing a loss of tack of the fold, the matrix precursor becoming powdery due to the evaporation of the solvent,

- risk of improper draping (shaping) of a fold affecting the following folds,

- impossibility of compacting the angle of the suitcase corner correctly, which could lead to the appearance of unacceptable pinches if an excess bead is generated during draping.

Subject and summary of the invention

It is therefore desirable to be able to have a solution for draping pre-impregnated folds in the corner of the suitcase which makes it possible to minimize the deformation of the folds in the area of the corner of the suitcase while ensuring the seal in the final piece.

To this end, according to the present invention, there is provided a method of draping at least one fibrous ply pre-impregnated with a matrix precursor on a shaping tool comprising a main face and first and second side faces extending from the main face, the main face and the first and second side faces extending perpendicularly to each other and meeting at least in one corner, called a suitcase corner, each fold comprising a first edge extending in a first direction and a second edge extending in a second direction perpendicular to the first direction, the first and second edges being respectively pressed against the first and second lateral faces of the shaping tool deforming a junction portion between said edges on the corner of the suitcase, characterized in that each ply comprises an over-length portion extending along a part of the first and second edges at their junction portion, one or more tensile forces being exerted on the over-length portion during the deformation of the junction portion on the corner of the suitcase.

The use of an over-length portion at the useful part of the fold intended to be draped over a corner of the suitcase makes it possible to considerably limit the deformations in this useful part. Indeed, as the tensile force is only applied from the over-length portion, most of the deformation due to traction, in particular the increase in the spacing between the warp threads and the weft threads, is concentrated in this portion. This makes it possible to limit the deformation of the useful zone to its shaping on the corner of the suitcase. The over-length portion corresponding to a sacrificial part which is removed before forming the final part, the deformations present in the over-length portion have no impact on the mechanical properties of the part and make it possible to ensure a good seal even in the wedge-shaped area.

According to a particular characteristic of the invention, the over-length portion defines a first lateral tab present on the side of the first edge, a second lateral tab present on the side of the second edge and a central tab present between the first and second lateral tabs. The tongues constitute benchmarks for the operator with regard in particular to the orientation of the woven threads greatly facilitating the handling of the fold during its draping. It is thus possible to determine a procedure for deforming the fold in order to distribute the material of the fold on either side of the edge of the corner of the suitcase so as to remain within the thickness tolerance determined for each fold and avoid formation of a bead on the edge.

According to one embodiment of the method of the invention, the ply (s) have a two-dimensional weaving between a first plurality of threads oriented at an angle of 0 ° and a second plurality of threads oriented at an angle of 90 °, a tensile force being exerted on the central tongue while a tensile force is exerted on the opposite ends of the first and second lateral tabs during the deformation of the junction portion on the corner of the suitcase. Thanks to the presence of tabs formed by the over-length portion it is possible to control the application of the tensile forces so as to take account of the orientation of the wires in the fold and to obtain a more symmetrical deformation.

According to another embodiment of the method of the invention, the ply (s) have a two-dimensional weaving between a first plurality of threads oriented at an angle of 45 ° and a second plurality of wires oriented at an angle of -45 °, a tensile force being exerted on the first and second lateral tabs during the deformation of the junction portion on the corner of the suitcase. Thanks to the presence of tongues formed by the over-length portion, it is possible to control the application of the tensile forces so as to take account of the orientation of the wires in the fold and to obtain a more symmetrical deformation.

According to another particular characteristic of the method of the invention, it comprises cutting the over-length portion after the lay-up of said at least one fold on the shaping tool.

According to another particular characteristic of the method of the invention, the ply (s) are produced with wires chosen from wires made of carbon fibers, glass fibers or silicon carbide fibers.

According to another particular characteristic of the process of the invention, the ply (s) are pre-impregnated with a liquid precursor of a carbon, ceramic or organic matrix.

The invention also relates to a method of manufacturing a piece of composite material comprising draping at least one fibrous ply pre-impregnated with a matrix precursor on a shaping tool according to the draping method of the invention and the transformation of the precursor into a matrix so as to obtain a part made of composite material comprising a fibrous reinforcement densified by a matrix. Brief description of the drawings

The invention will be better understood from the description given below, by way of indication but not limitation, with reference to the appended drawings in which:

- Figure 1 very schematically illustrates a two-dimensional fibrous ply intended to be draped over a shaping tool in accordance with an embodiment of the invention;

- Figures 2 and 3 show the layup of the fold of Figure 1 for the production of a fibrous preform;

- Figure 4 illustrates a composite material part obtained from the preform of Figure 3; - Figure 5 illustrates very schematically a two-dimensional fibrous ply intended to be draped over a shaping tool in accordance with another embodiment of the invention;

- Figures 6 and 7 show the layup of the fold of Figure 7 for the production of a fibrous preform;

FIG. 8 illustrates a part made of composite material obtained from the preform of FIG. 7.

Detailed description of embodiments

The invention applies generally to the production of parts made of composite material produced by draping one or more fibrous plies pre-impregnated with a liquid matrix precursor such as a resin, the part comprising at least a portion having the shape of a suitcase corner.

FIG. 1 very schematically illustrates a fibrous ply 100 which is intended to be draped over a shaping tool 200. The tool 200 comprises a main face 210 and first and second lateral faces 220 and 230 extending from the main face. The main face 210 and the first and second lateral faces 220 and 230 extend perpendicularly to each other and meet in a corner 240, called "suitcase corner".

The fold 100 is produced by two-dimensional weaving between a plurality of warp threads 101 and a plurality of weft threads 102. In the example described here, the warp threads 101 are oriented at an angle of 0 ° while the threads of weft 102 are oriented at an angle of 90 °.

The fibers used to make the strata can in particular be carbon, glass or silicon carbide fibers depending on the performance and the costs sought.

The fold 100 is further pre-impregnated with a liquid precursor of a matrix such as, for example, a phenolic type resin for obtaining a carbon matrix, a polycarbosilane resin for obtaining a carbide matrix. silicon, or an epoxy resin to obtain an organic resin matrix.

In the example described here, the fold 100 has a rectangular shape defined by a useful area 110, that is to say the area used to make the final piece. The fold 100 has a first edge 111 extending in a first direction A and a second edge 112 extending in a second direction B perpendicular to the first direction A. The first and second edges 111 and 112 are intended to be pressed respectively on the first and second lateral faces 220 and 230 of the shaping tool 200 by deformation of the junction portion 120 between the edges 220 and 230 on the suitcase corner 240 as explained below in detail.

According to the invention, the fold 100 further comprises an over-length portion 130 extending along a part of the first and second edges 111 and 112 at their junction portion 120.

As illustrated in FIG. 2, the draping of the fold 100 on the shaping tool 200 begins with the positioning of the fold 100 on the main face 210 of the tool and the folding down of the edges 111 and 112 respectively on the lateral faces 220 and 230 of the tool 200. The shaping of the fold 100 on the suitcase corner 240 of the tool is carried out by applying a tensile force to the portion of extra length, for example manually. In this case, an operator grasps the over-length portion 130 and pulls on it in the direction or directions making it possible to press the junction portion 120 between the edges 111 and 112 of the fold 100 on the corner of the suitcase 240.

More specifically, the over-length portion 130 defines a first lateral tab 131 present on the side of the first edge 111 of the fold 100, a second lateral tab 132 present on the side of the second edge 112 of the fold 100 and a central tab 133 present between the first and second lateral tabs 131 and 132. In the example described here, the fibrous ply 100 has a two-dimensional weaving with warp threads oriented at an angle of 0 ° and weft threads oriented at an angle of 90 °. In this case, a tensile force Fri is mainly exerted on the central tongue 133 in a direction substantially parallel to the edge of the bag corner 240 and, to a lesser extent, on the ends 1310 and 1320 respectively of the lateral tongues 131 and 132, respectively in directions substantially parallel to the lateral faces 220 and 230 of the tool 300. Once the draping operation is finished, a fibrous preform 300 is obtained as illustrated in FIG. 3 comprising a useful area 310 corresponding to the useful area 110 of the fold 100 and a sacrificial portion 330 corresponding to the over-length portion 130 of the fold 100 which was deformed by the draping. As the tensile force is only applied from the over-length portion 130, most of the deformation due to traction, in particular the increase in the spacing between the warp threads and the weft threads, is concentrated in this portion. This makes it possible to limit the deformation of the useful area, here the junction portion 120 between the edges 111 and 112 of the fold 100, to its shaping on the corner of the suitcase 240. The portion of extra length 130 corresponding to a sacrificial part which is removed before the final part is formed, the deformations present in the over-length portion 130 have no impact on the mechanical properties of the part. In addition, the over-length portion allows better guidance for the operator during layup. Indeed, the over-length portion defines tabs which constitute marks for the operator vis-à-vis in particular the orientation of the woven threads greatly facilitating the handling of the fold during its draping. It is thus possible to determine a procedure for deforming the fold in order to distribute the material of the fold on either side of the edge of the corner of the suitcase so as to remain within the thickness tolerance determined for each fold and avoid formation of a bead on the edge.

The sacrificial portion 330 is then detached from the useful area 310 of the preform 300 (not shown in FIG. 3). Several fibrous folds can be draped successively over the fold 100 according to a procedure identical to that described above.

The final preform, comprising one or more fibrous plies shaped as described above, is then subjected to a treatment allowing the transformation of the liquid precursor impregnating the ply (s) into a matrix. This treatment may for example correspond to a heat treatment for polymerizing a resin. As illustrated in FIG. 4, a rigid piece of composite material 10 is then obtained, comprising a fibrous reinforcement densified by a matrix and comprising a part in the shape of a suitcase corner 14 having the same mechanical properties and level of tightness as the other parts of the part.

FIG. 5 illustrates another embodiment of the invention which differs from that described above in that the draping of a fibrous ply 400 having a two-dimensional weaving between a plurality of warp threads 401 and a plurality is carried out. of weft threads 402, the warp threads 401 are oriented at an angle of 45 ° while the weft threads 402 are oriented at an angle of -45 °. The fold 400 is further pre-impregnated with a liquid precursor of a matrix such as for example a phenolic type resin for obtaining a carbon matrix, a polycarbosilane resin for obtaining a carbide matrix. silicon, or an epoxy resin to obtain an organic resin matrix.

As previously, a shaping tool 500 is used which comprises a main face 510 and first and second lateral faces 520 and 530 extending from the main face. The main face 510 and the first and second lateral faces 520 and 530 extend perpendicularly to each other and meet in a corner of a suitcase 540.

In the example described here, the fold 400 has a rectangular shape defined by a useful area 410, that is to say the area used to produce the final part. The fold 400 has first and second edges 411 and 412 intended to be pressed respectively on the first and second lateral faces 520 and 530 of the shaping tool 500 by deformation of the junction portion 420 between the edges 220 and 230 on the corner of suitcase 240.

According to the invention, the fold 400 further comprises an over-length portion 430 extending along a part of the first and second edges 411 and 412 at their junction portion 420.

As illustrated in FIG. 6, the draping of the fold 400 on the shaping tool 500 begins with the positioning of the fold 400 on the main face 510 of the tool and the folding of the edges 411 and 412 respectively on the lateral faces 520 and 530 of tool 500.

The over-length portion 430 defines a first lateral tab 431 present on the side of the first edge 411 of the fold 400, a second lateral tab 432 has on the side of the second edge 412 of the fold 400 and a central tab 433 has between the first and second lateral tabs 431 and 432. In the example described here, the fibrous fold 400 has a two-dimensional weaving with threads warp oriented at an angle of 45 ° and weft threads oriented at an angle of -45 °. In this case, a tensile force FT2 is exerted simultaneously on the two lateral tabs 431 and 432, the tensile force being first applied from the ends 4310 and 4320 of the lateral tabs 431 and 432 then towards the central tab 433.

Once the draping operation is completed, a fibrous preform 600 is obtained as illustrated in FIG. 7 comprising a useful area 610 corresponding to the useful area 410 of the fold 400 and a sacrificial portion 630 corresponding to the over-length portion 430 of the fold 400 which was deformed by the draping. As the tensile force is only applied from the over-length portion 430, most of the deformation due to traction, in particular the increase in the spacing between the warp threads and the weft threads, is concentrated in this portion. This makes it possible to limit the deformation of the useful area, here the junction portion 420 between the edges 411 and 412 of the fold 400, to its shaping on the suitcase corner 540. The portion of extra length 430 corresponding to a sacrificial part which is removed before the final part is formed, the deformations present in the over-length portion 430 have no impact on the mechanical properties of the part. In addition, the over-length portion allows better guidance for the operator during layup. Indeed, the over-length portion defines tabs which constitute benchmarks for the operator vis-à-vis in particular the orientation of the woven threads greatly facilitating the handling of the fold during its draping. It is thus possible to determine a procedure for deforming the fold in order to distribute the material of the fold on either side of the edge of the corner of the suitcase so as to remain within the thickness tolerance determined for each fold and avoid formation of a bead on the edge.

The sacrificial portion 630 is then detached from the useful area 610 of the preform 600 (not shown in FIG. 7). Several folds fibrous can be draped successively on the fold 400 according to a procedure identical to that described above.

The final preform, comprising one or more fibrous plies shaped as described above, is then subjected to a treatment allowing the transformation of the liquid precursor impregnating the ply (s) into a matrix. This treatment may for example correspond to a heat treatment for polymerizing a resin. As illustrated in FIG. 8, a rigid piece of composite material 20 is then obtained, comprising a fibrous reinforcement densified by a matrix and comprising a part in the shape of a suitcase corner 24 having the same mechanical properties and level of sealing as the other parts. of the room.

Claims

1. Method for draping at least one fibrous ply (100) pre-impregnated with a precursor of a matrix on a shaping tool (200) comprising a main face (210) and first and second lateral faces (220 , 230) extending from the main face, the main face (210) and the first and second lateral faces (220, 230) extending perpendicularly to each other and meeting at least in one corner, said suitcase corner (240), each fold comprising a first edge (111) extending in a first direction (A) and a second edge (112) extending in a second direction (B) perpendicular to the first direction ( A), the first and second edges (111, 112) being respectively pressed against the first and second lateral faces (220, 230) of the shaping tool by deforming a junction portion (120) between said edges on the suitcase corner (240),

characterized in that each ply comprises a portion of extra length (130) extending along a portion of the first and second edges (111, 112) at their junction portion (120), one or more traction forces (FTI) being exerted on the over-length portion during the deformation of the junction portion (120) on the suitcase corner (240).

2. Method according to claim 1, in which the over-length portion (130) defines a first lateral tab (131) present on the side of the first edge (111), a second lateral tab (132) present on the side of the second edge (112) and a central tab (133) present between the first and second lateral tabs.

3. The method of claim 2, wherein said at least one ply (100) has a two-dimensional weaving between a first plurality of son (101) oriented at an angle of 0 ° and a second plurality of son (102) oriented 90 ° angle, a pulling force being exerted on the central tongue (133) while a pulling force is exerted on the opposite ends (1310, 1320) of the first and second side tabs (131, 132) when the junction portion (120) is deformed on the case corner (240).

4. The method of claim 2, wherein said at least one fold (400) has a two-dimensional weaving between a first plurality of son (401) oriented at an angle of 45 ° and a second plurality of son (402) oriented angle of -45 °, a tensile force being exerted on the first and second lateral tabs (431, 432) during the deformation of the junction portion (420) on the suitcase corner (540).

5. Method according to any one of claims 1 to 4, comprising cutting the over-length portion (130) after draping said at least one fold on the shaping tool (200).

6. Method according to any one of claims 1 to 5, wherein said at least one ply (100) is produced with wires chosen from wires made of carbon fibers, glass fibers or fibers of silicon carbide.

7. Method according to any one of claims 1 to 5, wherein said at least one ply (100) is prepreg with a liquid precursor of a carbon, ceramic or organic matrix.

8. Method for manufacturing a piece of composite material comprising draping at least one fibrous ply (100; 400) pre-impregnated with a matrix precursor on a shaping tool according to the draping method according to any one of claims 1 to 7 and the transformation of the precursor into a matrix so as to obtain a piece of composite material (10; 20) comprising a fibrous reinforcement densified by a matrix.