CA2971421A1 - Tooling and impregnation process for a fibrous revolution preform - Google Patents

Abstract

A process for impregnating a fibrous preform (300) with a resin comprises:
- The winding of a fibrous texture (200) on a surface molding (114) of an impregnation tool so as to form a fibrous preform of revolution (300), - the placement of an impermeable and deformable membrane (120) facing the exposed face (300a) of the fibrous preform (300), the membrane having a form of revolution corresponding to the shape of the molding surface (114) of the impregnation tool, the space defined between the molding surface (114) and the membrane (120) corresponding to an impregnation chamber, the closure of the mold by a plurality of sectors angular (140) forming counter-molds, the space delimited between the face internal (140a) angular sectors (140) and the membrane (120) corresponding to a compaction chamber (150), injecting a resin (10) into the impregnation chamber, injection of an incompressible compaction fluid (20) into the compaction chamber (150), the compaction fluid exerting a pressing the membrane (120) to force the resin (10) to impregnate the fibrous preform (300).

Description

Title of the invention Tooling and method for impregnating a fibrous preform of revolution Background of the invention The present invention relates to the production of revolution in composite material.
A field of application of the invention is more particularly the production of structural composite material parts, that is to say Structural parts with fiber reinforcement densified by a matrix. The composite materials make it possible to produce parts having a mass overall lower than these same parts when they are made in metallic material.
A conventional method for obtaining parts of revolution in composite material, such as an engine blower housing aeronautics is described in Figures 1 and 2. In Figure 1, a preform fibrous 30 is formed by winding a fibrous texture in the form of of tape on a mold 51 of injection molding equipment 50.
counter-molds 52 are used to close the mold 51. Once the injection mold tooling 50 thus closed, a resin is injected 60 in the preform 30. More precisely and as illustrated in the figure

2, the resin 60 is injected into the fiber preform 30 through ports injection 511 present on the lower flange 510 of the mold 51, 513 output ports being present on the upper flange 512.
preform 30 is, therefore, impregnated into its section from its lower flange and up to its upper flange. At the end of resin injection, the 513 output ports are closed and a consolidation pressure is applied via injection ports 511. This pressure of consolidation allows to complete the impregnation of the preform. In In some cases, this consolidation pressure is necessary in order to avoid a phenomenon of steaming resin components that can lead to the formation of porosities in the final piece.
However, this impregnation technique requires control the rate of impregnation of the fiber preform, that is to say the injection rate of the resin in the tooling to prevent the formation of porosity of flow. Indeed, if the resin gels prematurely in one of the injection ports, the consolidation pressure is no longer applied at the level of this port because the consolidation pressure is not applied at the level of the injection ports. In this case, porosities of chemical origin can then be formed.
Object and summary of the invention The present invention aims to overcome the disadvantages mentioned above and to propose a solution which makes it possible to impregnate fibrous preforms of revolution without risk of porosity formation.
For this purpose, the invention proposes a method for impregnating a fibrous preform with a resin comprising:
- the winding of a fibrous texture on a surface of molding an impregnation tool so as to form a preform fibrous of revolution, the impregnation tool comprising a mold having a mandrel extending in width in an axial direction between a first and second annular flange extending over the mandrel in a radial direction, the first and second flanges and the mandrel defining the molding surface on which the texture fibrous is rolled up, - the placement of an impermeable and deformable membrane opposite the exposed face of the fibrous preform, the membrane having a shape of revolution corresponding to the shape of the surface molding, the membrane extending in the axial direction between free ends of the first and second flanges, the space delimited between the molding surface and the membrane corresponding to a chamber impregnation the closure of the mold by a plurality of sectors angular counter-molds, the angular sectors being placed in vis-à-vis the exposed face of the membrane, each angular sector having on its inner face in the radial direction a shape complementary to the molding surface with in the axial direction first and second flanges keeping the membrane in contact with the free ends of the first and second flanges, the space delimited between the inner face of the angular sectors and the membrane corresponding to a compaction chamber, the injection of a resin into the impregnation chamber,

3 the injection of an incompressible compaction fluid into the compaction chamber, the compaction fluid exerting a pressure on the membrane to force the resin to impregnate the fiber preform.
By using an impermeable and deformable membrane as well that a compaction chamber, it is possible to limit the speed of the front of resin during the impregnation of the fiber preform and thus to limit the porosity of flow. In addition, the resin is first injected into an impregnation chamber before being pushed into the preform fibrous when injecting fluid compaction, the preform is impregnated in its thickness and no longer in its section as in the prior art described above. This further reduces the appearance porosity of flow.
According to a first particular aspect of the method of the invention, before the injection of the resin into the impregnation chamber, a depression is applied in the compaction chamber.
This depression helps to ensure that a space is well present between the membrane and the preform before the injection of the resin.
Thus, during the injection of the resin, it is spread preferentially in the free space and not in the preform that has a permeability lower vis-à-vis the free space.
According to a second particular aspect of the method of the invention, the pressure of the incompressible fluid of compaction applied on the waterproof and deformable membrane is adjusted to a value determined. Thanks to the use of a flexible and deformable membrane, the pressure is applied hydrostatically over the entire preform fibrous. So, even if locally some of the resin gels prematurely, the nearby resin is still under pressure thanks to the membrane, which makes it possible to avoid the appearance of the original porosities chemical.
According to a third particular aspect of the method of the invention, the fibrous texture is obtained by three-dimensional or multilayer weaving.
The yarns of the preform may be made of fibers made up one or more of the following materials: carbon, silicon carbide, glass, alumina, mullite, aluminosilicate, borosilicate, or a mixture of many of these materials.

4 The resin may be chosen from at least one of the resins following: epoxy resin, carbon precursor resin and resin precursor of silicon carbide.
The invention also relates to a tool for impregnation for a fibrous preform, the tooling comprising:
a mold comprising a mandrel extending in width in an axial direction between first and second flanges rings extending above the mandrel in a radial direction, the first and second flanges each having a free end extending above the outer surface of the mandrel in the direction radially, the first and second flanges and the mandrel defining a molding surface on which a fibrous preform is intended to be formatting by winding, an impermeable and deformable membrane presenting a shape of revolution corresponding to the shape of the molding surface, the membrane extending in the axial direction between the free ends first and second flanges, the space delimited between the surface of molding and the membrane corresponding to an impregnation chamber, a plurality of angular sectors forming counter-molds, each angular sector presenting on its internal face in the direction radial a complementary shape of the molding surface with in the axial direction first and second flanges now the membrane in contact with the free ends of the first and second flaccid, the space delimited between the internal faces of the angular sectors and the membrane corresponding to a compaction chamber, the first flange or the second flange comprising at less a resin injection port opening into the chamber impregnation at least one angular sector comprising a port injection of a compaction fluid opening into the chamber of compaction.
Brief description of the drawings Other features and advantages of the invention will emerge of the following description of particular embodiments of

5 the invention, given by way of non-limiting examples, with reference to the attached drawings, in which:
FIG. 1 is a schematic perspective view of a impregnation tools according to the prior art, FIG. 2 is a schematic sectional view of the tooling of Figure 1 according to the plane II shown in Figure 1, FIG. 3 is an exploded perspective schematic of a impregnation tools according to an embodiment of the invention, FIG. 4 is a schematic perspective view of the tool of Figure 3 once closed, FIG. 5 is a schematic sectional view of the tooling of FIG. 4 along the plane V indicated in FIG.
FIG. 6A is a schematic perspective view showing the formation of a fibrous preform on the mold of the tooling impregnation of Figure 3, FIG. 6B is a schematic perspective view showing the establishment of a flexible and deformable membrane in the impregnation tool of FIG. 3 and the closure of the tooling, FIG. 6C is a schematic perspective view showing the tool of Figure 6B when closed, FIGS. 7A to 7D are schematic sectional views of the tool of FIG. 6C according to plane VII indicated in FIG. 6C
showing steps of a process for impregnating a fibrous preform according to one embodiment of the invention, FIG. 8 is a schematic perspective view of a part obtained with a process according to the invention.
Detailed description of embodiments FIGS. 3 to 5 represent an injection tool or impregnation 100 according to one embodiment of the invention.
The impregnation tool 100 comprises a mold 110 consisting of a chuck or drum 111 extending in width in one direction axial axis DA between first and second annular flanges 112 and 113 integral with the mandrel 111 and extending over it in accordance with a

6 radial direction DR. The first and second flanges 112 and 113 each comprise a free end 1123, 1133 extending above the outer surface 111a of the mandrel 111 in the radial direction DR. The faces 112a and 113a facing each other flanges 112 and 113 and the outer surface 111a of the mandrel 111 define together a molding surface 114 on which a fibrous preform is intended to be shaped by winding as explained below.
after.
Injection tooling 100 also includes a membrane waterproof and deformable 120 having a form of revolution corresponding to the shape of the molding surface 114. The membrane 120 is preformed but must have sufficient flexibility to can be put in place in the injection equipment. The membrane 120 can be made for example of silicone membrane 120 extends over the entire circumference of the mold 110 and in the axial direction between the free ends 1123 and 1133 of the first and second flanges 112 and 113 against which it is maintained once the mold 110 closed as explained below in detail. The space delimited between the surface of molding 114 and the face 120b of the membrane 120 facing the surface 114 forms an impregnation chamber 130 in which is arranged a fibrous preform to be injected.
The impregnation tool 100 further comprises a plurality angular sectors 140 forming counter-molds. Each sector angular 140 has on its inner face 140a in the radial direction DR a complementary shape of the molding surface 114 with, in the axial direction DA, first and second flanges 141 and 142 now the membrane 120 in sealing contact with the ends 1120 and 1130 respectively of the first and second flanges 112 and 113, a sealed contact being also established between the membrane 120 and the first and second flanges 141 and 142. The space delimited between the inner face 140a of the angular sectors 140 and the face 120a of the membrane 120 opposite the face 140a corresponding to a chamber of compaction 150.
In the example described here, the first flange 112 comprises a plurality of injection ports 1120 evenly distributed in the direction circumference of the tooling 100. Each injection port 1120 opens

7 in the impregnation chamber 130. The injection ports 1120 are used to inject a resin into the impregnation chamber when contains a fibrous preform to be impregnated. The second flange 113 may include a plurality of discharge ports 1130 in communication with the impregnation chamber 130 allowing facilitate the injection of the resin into the impregnation chamber evacuating the air present in the impregnation chamber. According to a variant embodiment, the injection ports can be placed on the second flask 113 while the evacuation ports are placed on the first flange 112 when used. According to another variant, the first or the second flange may comprise only one injection port.
In the example described here, each angular sector 140 includes 1400 injection ports opening into the chamber of compaction 150. The 1400 injection ports are used to inject a fluid compaction in the compaction chamber 150 as described above.
after in details. The angular sectors 140 may comprise in in addition to evacuation ports 1401 to facilitate the introduction of the compaction fluid in the compaction chamber 150 evacuating the air present in said chamber. According to an alternative embodiment, one or only part of the angular sectors include one or more injection ports and possibly one or more discharge ports.
We now describe a process for impregnating a resin in a fiber preform according to an embodiment of the invention. As illustrated in FIG. 6A, the process starts with winding a fibrous texture 200 on the molding surface 114 of the mold 110 of the impregnation tool 100 so as to form a fibrous preform of revolution 300 (FIG. 6B). Once the preform 300 thus formed, the impermeable and deformable membrane 120 is wound around the mold 110 facing the exposed face 300a of the preform fibrous 300 (FIG. 6B). The membrane 120 has a shape of revolution corresponding to the shape of the molding surface 114. The membrane 120 extends in the axial direction DA between the ends 1123 and 1133 respectively of the first and second flanges 112 and 113 free, the space delimited between the molding surface 114 and the membrane 112 defining the impregnation chamber 130.

8 The mold 110 is then closed by the plurality of sectors angular 140 which form counter-molds (Figures 6B, 6C and 7A).
In the example described here, the angular sectors 140 are fixed by means of screws 1411 that pass through holes 1410 and 1420 present respectively on the flanges 141 and 142 of the angular sectors 140, the screws being tightened in threads 1122 and 1132 made respectively in the flanges 112 and 113 (Figure 3). Fixing angular sectors on the flanges 112 and 113 makes it possible to maintain the edges 121 and 122 of the membrane 120 in sealing contact with both the flanges of the angular sectors 140 and the radial edges 121 and 1131 respectively flanges 112 and 113. The space delimited between the face internal 140a angular sectors 140 and the face 120a of the membrane 120 opposite the face 140a defines the compaction chamber 150.
Once the mold 110 closed by the angular sectors 140, a resin 10 is injected into the impregnation chamber 130 between the exposed face 300a of the fibrous preform and the face 120b of the membrane 120 opposite the preform 300 via the injection ports 1120 (Figure 7B). Optionally, before the injection of the resin into the impregnation chamber 130, a depression may be previously applied in the compaction chamber 150, for example by connecting a vacuum pump at injection ports 1400 and discharge ports 1401 (Figure 7A). This depression helps to ensure that a space is well present between the membrane and the preform before the injection of the resin.
Thus, during the injection of the resin, it is spread preferentially in the free space and not in the preform that has a permeability lower vis-à-vis the free space.
The quantity of resin 10 introduced into the chamber impregnation 130 is determined according to the volume of the preform 300 to impregnate. When the determined amount of resin 10 has been injected into the impregnation chamber 130, the injection ports 1120 and the evacuation ports 1130 are closed. An incompressible fluid of compaction 20 is then introduced into the compaction chamber 150 via the injection ports 1400 present on the angular sectors 1401 (FIG.
7C). The 1401 evacuation ports are opened at first to allow to expel the air repelled by the fluid compaction 20, then

9 are closed in a second step to allow the setting pressure of the compaction fluid.
Injection of the incompressible compaction fluid into the compaction chamber 20 has the effect of repelling the membrane 120 towards the fibrous preform 300 in directions indicated by the arrows represented in FIGS. 7C and 7D and forcing the resin 10 to penetrate in the preform 300. As the fluid is injected compaction in the compaction chamber 150, the membrane 120 pushes both the resin in the free space of the impregnation chamber 130 and in the preform as illustrated in Figures 7C and 7D.
At the end of the injection, the incompressible compaction fluid applies a consolidation pressure on the membrane 120 which is also applied on the resin. The pressure is applied from hydrostatically on the entire fiber preform. So, even if locally a part of the resin gels prematurely, the resin to proximity is still under pressure thanks to the membrane, which prevents the appearance of porosities of chemical origin. Pressure of consolidation of the incompressible compaction fluid applied to the waterproof and deformable membrane is adjusted to a value determined which may be between 1 and 20 bar.
A fibrous preform impregnated with a matrix precursor. The transformation of the precursor into a matrix organic, namely its polymerization, is carried out by treatment thermal, generally by heating the mold, after removal of the possible solvent and crosslinking of the polymer, the preform being always maintained in the mold having a shape corresponding to that of the piece to realize. The organic matrix can in particular be obtained from epoxy resins, such as, for example, the epoxy resin to high performance, or liquid precursors of carbon matrices or ceramic.
In the case of the formation of a carbon matrix or ceramic, heat treatment consists of pyrolyzing the precursor organic to transform the organic matrix into a carbon matrix or ceramic according to the precursor used and the pyrolysis conditions. AT
For example, liquid carbon precursors may be resins with a relatively high coke content, such as resins

10 phenolic, while liquid precursors of ceramics, especially SiC, may be polycarbosilane type resins (PCS) or polytitanocarbosilane (PTCS) or polysilazane (PSZ).
After the polymerization, a piece 400 such is obtained illustrated in Figure 8. The release of the part 400 is facilitated by the differential expansion between the metal mold 110, for example in steel, and the composite piece 400. On cooling, piece 400 is takes off from the mold 110. The latter, in several parts (not shown in the figures), is then open. The mold 110 may be generally two ring parts which each have a flange 112 or 113 and which is separate axially at the opening. Alternatively, the mold 110 may have flanges which are separated from the central body carrying its supports fixing, the flanges then being separated from the body. In the end, the 400 piece is cut away to remove excess resin and chamfers are machined to obtain a crankcase.
The fibrous texture 200 is obtained by three-dimensional weaving or multilayer made in a known manner by means of a loom of jacquard type on which a bundle of warp yarns or strands into a plurality of layers, the strings being linked by son frame. In the example described above, the multilayer weave is a interlock weave. By weaving "interlock" is meant here a weave weave in which each layer of weft threads binds several layers of warp threads with all the threads of the same column weft with the same movement in the plane of the armor. other known multilayer weaving types can be used, such as particularly those described in document WO 2006/136755, the content is incorporated herein by reference.
The yarns used to weave the fibrous texture 200 for forming the fibrous preform 300 and, consequently, the fibrous reinforcement of the piece 400 made of composite material may in particular be formed of fibers consisting of one of the following materials: carbon, carbide silicon, glass, alumina, mullite, aluminosilicate, borosilicate, or a mix of many of these materials.

Claims (7)

11 1. Process for impregnating a fibrous preform (300) with a resin comprising:
- The winding of a fibrous texture (200) on a surface molding (114) of an impregnation tool (100) so as to to form a fibrous preform of revolution (300), the tooling impregnation device comprising a mold (110) having a mandrel (111) extending in width in an axial direction (DA) between a first and second annular flanges (112, 113) extending above the mandrel (111) in a radial direction (DR), the first and second flanges (112, 113) and the mandrel (114) defining the molding surface (114) on which fiber texture (200) is wound, - the placement of an impermeable and deformable membrane (120) facing the exposed face (300a) of the fibrous preform (300), the membrane having a form of revolution corresponding to the shape of the molding surface (114), the membrane (120) extending in the axial direction (DA) between free ends of the first and second flanges, the space defined between the molding surface (114) and the membrane (120) corresponding to an impregnation chamber (130), the closure of the mold by a plurality of sectors angular members (140) forming counter molds, the angular sectors being placed opposite the exposed face (120a) of the membrane (120), each angular sector having on its inner face (140a) in the radial direction (DR) a complementary shape of the molding surface (114) with in the axial direction (DA) a first and a second flanges (141, 142) holding the membrane in contact with the ends free of the first and second flanges (112, 113), the space delimited between the inner face (140a) of the angular sectors (140) and the membrane (120) corresponding to a compaction chamber (150), the injection of a resin (10) into the impregnation chamber (130) the injection of an incompressible compaction fluid (20) in the compaction chamber (150), the compaction fluid exerting pressing the membrane (120) to force the resin (10) to impregnating the fiber preform (300). 2. The method of claim 1, wherein before injecting the resin (10) into the impregnation chamber (130), a depression is applied in the compaction chamber (150). The method of claim 1 or 2, wherein, the incompressible compaction fluid pressure (20) applied to the impermeable and deformable membrane (120) is adjusted to a value determined. 4. Method according to any one of claims 1 to 3, wherein the fibrous texture (200) is obtained by weaving three-dimensional or multilayer. 5. Method according to any one of claims 1 to 4, wherein the fibers of the fibrous preform (300) are formed of fibers made of one or more of the following materials: carbon, carbide silicon, glass, alumina, mullite, aluminosilicate, borosilicate, or a mix of many of these materials. 6. Process according to any one of claims 1 to 5, wherein the resin (10) is selected from at least one of the resins following: epoxy resin, carbon precursor resin and resin precursor of silicon carbide. 7. Impregnation tools (100) for a fibrous preform (300), the tool comprising:
a mold (110) comprising a mandrel (111) extending in width in an axial direction (DA) between a first and second annular flanges (112, 113) extending above the following mandrel a radial direction (DR), the first and second flanges comprising each having a free end extending above the outer surface (111a) of the mandrel (111) in the radial direction, the first and second flanges (112, 113) and the mandrel (111) defining a surface molding (114) on which a fiber preform (300) is intended for be shaped by winding, an impermeable and deformable membrane (120) presenting a form of revolution corresponding to the shape of the surface of molding (114), the membrane extending in the axial direction (AD) between the free ends of the first and second flanges (112, 113), the space defined between the molding surface (114) and the membrane (120) corresponding to an impregnation chamber (130), a plurality of angular sectors (140) forming molds, each angular sector (140) having on its inner face (140a) in the radial direction a shape complementary to the surface molding (114) with in the axial direction (DA) a first and a second flanges (141, 142) holding the membrane (120) in contact with the free ends of the first and second flanges (112, 113), the space delimited between the inner face (140a) of the angular sectors (140) and the membrane (120) corresponding to a compaction chamber (150) the first flange (112) or the second flange (113) comprising at least one resin injection port (1120) opening in the impregnation chamber (130), at least one angular sector (140) comprising a port injection (1400) of a compaction fluid opening into the chamber of compaction (150).