CA2971336A1 - Manufacturing process for a composite material, cone or cylindrical shaped part and impregnation tooling for a fibrous cone or cylindrical shaped preform - Google Patents

Abstract

A method of manufacturing a piece of frustoconical shape in composite material comprising the following steps:
- Placement of a fibrous preform of frustoconical shape (200) or cylindrical in a female mold member (110), - placement of an impermeable membrane (120) next to the exposed face (200a) of the fibrous preform (200), the defined space between the inner surface (111a) of the female mold member (110) and the membrane (120) corresponding to an impregnation chamber (140), - Assembling a male mold element (130) with the element of a female mold (110), the diaphragm (120) being interposed between the male mold member (130) and the female mold member (110), the space defined between the male mold element (130) and the membrane (120) corresponding to a compaction chamber (150), injection of a resin (10) into the impregnation chamber (140) injecting a compaction fluid (20) into the chamber of compaction (150), the compaction fluid (20) exerting pressure on the membrane (120) for forcing the resin (10) to impregnate the preform fibrous (200), - polymerization of the resin to obtain a piece composite material comprising a fiber reinforcement densified by a matrix.

Description

Title of the invention Process for producing a piece of frustoconical or cylindrical shape in composite material and tooling for impregnating a fibrous preform of frustoconical or cylindrical shape Background of the invention The present invention relates to the production of shaped parts frustoconical or cylindrical 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 fibrous reinforcement and 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 frustoconical parts in composite material, such as an engine exhaust casing described in Figure 1. In Figure 1, a preform fibrous 30 is formed by shaping a fibrous texture on a mold 51 of an injection molding tool 50, the mold having a shape as close as possible to the inner wall of the piece composite material to be produced. The mold 51 is closed by a membrane deformable waterproof 52 compatible with the resin to be injected in the preform. The membrane 52 is circled at the top and bottom of the mold 51 to seal the tooling 50. The side face outer 30a of the fibrous preform 30 is facing the membrane 52 while the lower and upper faces 30b, 30c of the preform 30 are respectively facing diffusion gates 53 and 54.
The tooling 50 also comprises an injection port 55 connected to an injection machine 60 which is intended to inject under pressure a resin 61 in the tooling 50. The tooling 50 further comprises a port of outlet 56 intended to evacuate the effluents and the excess resin, the port of outlet 56 being connected to an effluent treatment device 70.
The tooling 50 is placed in an autoclave 80 which allows apply pressure to the outside of the tool and inject the resin 61 under pressure, thereby increasing the driving force of the resin and decreases the impregnation time of the preform. The application of a

2 pressure on the outer surface 52a of the diaphragm 52 is also necessary to ensure compaction of the fiber preform 30 during polymerization of the resin to reduce the final porosity.
However, this impregnation technique poses problems especially in terms of the time needed to impregnate completely the fibrous preform, which time must be less than the pot life of the resin. In addition, temperature management remains delicate in particularly for the impregnation of thick preforms (thickness greater than 80 mm) with a resin that is potentially exothermic.
Moreover, the application of a pressure on the membrane during the polymerization of the resin causes defects in the preform fibrous such as ripples and folds that can be crippling for subsequent use of the resulting part. These defects are accentuated if the fibrous preform does not perfectly fit the mold, this which is often the case because the manufacturing tolerance of the preforms is the order of a millimeter while the shape of the mold is difficult adaptable.
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 frustoconical or cylindrical shape without risk of formation of defects while minimizing the impregnation time so to obtain parts made of composite material of good quality.
For this purpose, the invention proposes a method of manufacturing a frustoconical or cylindrical piece of composite material comprising the following steps:
- Placement of a fibrous preform of frustoconical shape or cylindrical in a female mold element of a tool impregnation, the female mold element having a cavity delimited by a side wall having an internal shape surface frustoconical or cylindrical, the fibrous preform being placed opposite the inner surface of said side wall, - placement of an impermeable and deformable membrane in view of the exposed face of the fibrous preform, the membrane

3 having a frustoconical or cylindrical shape, the space delimited between the internal surface of frustoconical or cylindrical shape of the side wall of the female mold element and the membrane corresponding to a impregnation chamber in which the fiber preform is present, - assembly of a male mold element with the element of female mold, the male mold element comprising a body axisymmetric housed in the cavity of the female mold element, the outer surface of the axisymmetric body being placed opposite and at a determined distance from the frustoconical internal surface or cylindrical side wall of the female mold member, the membrane being interposed between the outer wall of the axisymmetric body of the male mold element and the frustoconical inner surface or cylindrical of the side wall of the female mold element, the space delimited between the outer surface of the axisymmetric body and the membrane corresponding to a compaction chamber, injection of a resin into the impregnation chamber, injection of a compaction fluid into the chamber of compaction, the compaction fluid exerting pressure on the membrane to force the resin to impregnate the fibrous preform, - polymerization of the resin to obtain a piece composite material comprising a fiber reinforcement densified by a matrix.
By first injecting the resin into an impregnation chamber containing the fibrous preform before being pushed into the preform fibrous when injecting fluid compaction, the preform is impregnated in its thickness and no longer in its axial section as in the prior art described above, this considerably reduces the impregnation time, which allows more flexibility in manufacturing of the composite material part.
In addition, the membrane applying pressure to the preform directed from the inner face of the preform to the outer face of the preform, it is possible to use non-conforming preforms perfectly the shape of the wall of the female mold element or does not not perfectly against it without the risk of ripple and / or crease type defects.

4 According to a first particular aspect of the method of the invention, the resin is injected at the lower edge of the fibrous preform, the fluid compaction being injected from the bottom of the compaction chamber located in the vicinity of the lower edge of the fibrous preform. This allows the membrane to grow back gradually the resin in the preform and optimize the impregnation of the preform in all its volume.
According to a second particular aspect of the method of the invention, the resin is injected into a circular channel present on the bottom of the female mold element, which allows the resin to spread uniformly around the lower edge of the preform during its injection.
According to a third 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 ensures that a space is present between the membrane and the preform before injection of the resin. So, when the injection of the resin, this one spreads preferentially in the space free and not in the preform which has a lower permeability vis-over free space.
According to a fourth particular aspect of the method of the invention, the fibrous preform is obtained by three-dimensional weaving or multilayer.
According to a fifth aspect of the method of the invention, the fibrous preform is obtained by stacking fibrous layers unidirectional interconnected by needling or obtained by weaving two-dimensional.
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.
The resin may be chosen from at least one of the resins epoxy resin, phenolic resin, precursor resin, carbon and precursor resin of silicon carbide.

5 The invention also relates to a tool for impregnation for a fibrous preform of frustoconical or cylindrical shape, tooling comprising:
a female mold element comprising a cavity delimited by a side wall having an internal shape surface frustoconical or cylindrical, a male mold element comprising a body axisymmetric housed in the cavity of the female mold element, the outer surface of the axisymmetric body being placed opposite and at a determined distance from the frustoconical internal surface or cylindrical of the side wall of the female mold member, an impermeable and deformable membrane presenting a frustoconical or cylindrical shape, the membrane being placed opposite of the outer wall of the axisymmetric body of the male mold element, the space delimited between the internal surface of frustoconical shape or cylindrical side wall of the female mold member and the membrane corresponding to an impregnation chamber, the defined space between the outer surface of the axisymmetric body and the membrane corresponding to a compaction chamber, the female mold element comprising at least one port resin injection opening in the impregnation chamber, the male mold element comprising at least one port injection of a compaction fluid opening into the chamber of compaction.
According to a particular aspect of the tooling of the invention, each resin injection port opens into the impregnation chamber at level of a bottom of the female mold element, said bottom having a circular channel into which the injection port or ports of resin.
Brief description of the drawings Other features and advantages of the invention will emerge of the following description of particular embodiments of the invention, given by way of non-limiting examples, with reference to the attached drawings, in which:

6 FIG. 1 is a schematic sectional view of a tool impregnation according to the prior art, FIG. 2 is a diagrammatic perspective exploded view impregnation tools according to an embodiment of the invention, FIG. 3A is a schematic sectional view of the tooling of FIG. 2, once closed, showing the injection of a resin into the tooling, FIGS. 3B and 3C are schematic sectional views of the tool of FIG. 2 showing impregnation steps of a fibrous preform according to one embodiment of the invention, FIG. 4 is a schematic perspective view of a part obtained according to a method of the invention.
Detailed description of embodiments FIG. 2 represents an injection tooling 100 according to an embodiment of the invention. tooling of impregnation 100 comprises a female mold member 110 constituted of a side wall 111 whose inner surface 111a has a shape frustoconical and delimits a cavity 112. The inner surface 111a is intended to be in contact with a fiber preform 200 to be impregnated.
The female mold member 110 also includes a bottom 113 closing the lower part 1110 of the side wall 111. In the example described here, the upper portion 1111 of the side wall 111 has a first and second annular grooves 1112 and 1113 which are intended to receive respectively a first and a second seals O-rings 1114 and 1115. Still in the example described here, a seal ring 1140 is further disposed between the upper part 1111 of the side wall 111 and a flange 114 attached to the upper part 1111 by screws 1141.
The impregnation tooling 100 also includes an element of male mold 130 having an axisymmetric body 131 which is intended to be housed in the cavity 112 of the female mold element 110 when closing the impregnation tool 100. The body axisymmetric 131 has a suitable shape to ensure the recovery of the compaction liquid to inject the resin into the texture from bottom to top as described below. In the example described here, the

7 axisymmetric body 131 fits inside a truncated cone and has an outer surface 131a of concave shape.
When the male mold member 130 is assembled with the female mold member 110, the outer surface 131a of the body axisymmetric 131 is placed opposite and at a determined distance from the internal frustoconical surface 111a of the side wall 111 of the female mold member 110 (Fig. 3A). The male mold element comprises a removable cover 132 which is fixed on a flange 1310 present on the upper part of the frustoconical body 131 by means of screw 1320.
The impregnation tooling 100 also includes a impermeable membrane 120 having a frustoconical shape, the membrane, for example made of silicone, being able to deform (lie down) without breaking under the pressure of the compacting liquid. The membrane 120 is interposed between the outer surface 131a of the body axisymmetric 131 of the male mold element and the inner surface 111a of the side wall 111 of the female mold member 110. The membrane 120 is placed near the outer wall 131a of the body 131 of the male mold element 130. The defined space between the inner surface 111a of the side wall 111 of the female mold 110 and the face 120a of the membrane facing the surface 111a corresponds to an impregnation chamber 140 in which is has a fiber preform 200 to impregnate (Figure 3A). Space delimited between the outer surface 131a of the axisymmetric body and the face 120b of the membrane 120 opposite the surface 131a corresponds to a compaction chamber 150.
In the example described here, the female mold element 110 comprises two injection ports 115 and 116 present on the bottom 113 of the female mold element. Injection ports 115 and 116 open in the impregnation chamber 140 (Figure 3A). Injection ports 115 and 116 are used to inject a resin into the chamber impregnation when it contains a fibrous preform to be impregnated.
The male mold member may further include ports 117 disposed on the opposite side from the ports 115 and 116, here positioned at the flange 114 (FIGS.
3C). Evacuation ports 117 are in communication with the chamber

8 impregnation 140 and facilitate the injection of the resin into the impregnation chamber evacuating the air present in the chamber impregnation, the evacuation ports that can be connected to a draft pump. According to an alternative embodiment, the element of female mold may comprise only one injection port or more two injection ports.
In the example described here and as shown in FIGS.
and 3A to 3C, the bottom 113 of the female mold member 110 may comprise a circular ditch 1131 in which the ports directly open 115 and 116. The channel 1131 distributes the injected resin via the injection ports 115 and 116 uniformly at the bottom 113 and, therefore, at the lower edge 201 of the preform fibrous 200 to be impregnated.
In the example described here, the male mold element 130 comprises an injection port 133 present at the bottom 134 of the body axisymmetric 131, the injection port 133 opening into the chamber of compaction 150. The injection port 133 is used to inject a fluid of compaction in the compaction chamber 150 as described below in detail. The male mold member 130 may further include discharge ports 135 to facilitate the introduction of the fluid of compaction in the compaction chamber 150 evacuating the present air in said chamber. According to an alternative embodiment, several ports injection can be present on the male mold element 130. On can also use injection port 133 and vent 135 to make circulate the compaction fluid at a temperature allowing contribute to the polymerization of the resin during the cooking phase of the composite part.
A method of injecting a resin into a a fiber preform according to an embodiment of the invention. The method requires holding means such as a press (not shown in FIGS. 3A to 3C).
As illustrated in FIG. 2, the elements of the male mold are assembled, namely the parts 114, 131, 132 and the membrane 120 and the porous material 1140. The male part thus equipped is fixed under the top plate of the press using screws 1141. A preform fibrous 200 is introduced in the cavity 112 of the female mold element

9 110 which is equipped with seals 1114 and 1115. The tool is closed by lowering of the upper plate of the press.
Once the impregnation tool has been closed, a resin 10 is injected into the impregnation chamber 140 between the exposed face 200a of the fibrous preform and the face 120a of the membrane 120 next to the face 200a of the preform 200 (Figure 3A). The resin 10 is injected into the impregnation chamber 140 via the injection ports 115 and 116, that is to say say at the lower edge 201 of the fiber preform 200. The resin 10 is evenly distributed around the lower edge 201 of the preform 200 through the channel 1131 in which the ports open 115 and 116. In the example described here, the injection ports 115 and 116 are positioned so as to open into an empty space of the impregnation chamber 140, that is to say a space that is not occupied by the fibrous preform 200. In this case, the resin 10 is injected in this free space to be pushed further inside the preform as explained below. According to an alternative embodiment, the injection ports 115 and 116 can be positioned to to emerge at the lower edge 201 of the preform 200. In this case, the resin 10 is directly injected into the preform.
Optionally, before the injection of the resin into the impregnation chamber 140, a depression may be previously applied in the compaction chamber 150, for example by connecting a vacuum pump at the injection port 133 and the discharge ports 135. This depression ensures that a space is present between the membrane and the preform before injection of the resin. So, when the injection of the resin, this one spreads preferentially in the space free and not in the preform which has a lower permeability vis-over free space.
The quantity of resin 10 introduced into the chamber of impregnation 140 is determined according to the volume of the preform 200 to impregnate and its fiber content. When the quantity determined of resin 10 was injected into the impregnation chamber 140, the ports injection 115, 116 and the discharge ports 117 are closed. A fluid compaction 20 is then introduced into the compaction chamber 150 via the injection port 133 present at the bottom 134 of the body axisymmetric 131, a conduit 21 connecting the injection port 133 to the inlet

10 tooling at the cover 132 (Figure 3B). The ports evacuation 135 are opened at first to allow chase the air repelled by the fluid compaction 20, and then are closed in a second time to allow the pressurization of the fluid of compaction.
The injection of the compaction fluid into the chamber of compaction 20 has the effect of pushing the membrane 120 towards the fibrous preform 200 in directions indicated by the arrows represented in FIGS. 3B and 3C and forcing the resin 10 to penetrate in the preform200. 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 3B and 3C. By the action of the compaction fluid 20 on the membrane 120, the membrane exerts compaction pressure on the preform, which pressure is applied from the inside, that is to say on the inner face 200a of the preform, outwards, that is to say towards the outer face 200b of the fibrous preform 200.
The compaction fluid 20 is preferably injected from the lower part 151 of the compaction chamber 150 located in the vicinity of the lower edge 201 of the fiber preform 200, which allows the membrane 120 to gradually push the resin 10 in the preform 200 and optimize the impregnation of the preform in all its volume.
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 impregnation tools, by example by circulation of a coolant in coils surrounding the tooling and in the compaction chamber after disposal possible solvent and crosslinking of the polymer. During the polymerization, a pressure, called polymerization pressure, is always applied by the membrane 120 on the fibrous preform 200 because the fluid compaction always exerts itself a pressure on the membrane.
The application of both a compaction pressure during impregnation of the preform and of a polymerization pressure during

11 the polymerization of the resin in the preform causes a decrease the thickness of it at the same time as an increase in its inner diameter, these displacements being limited by the deformations possible of the preform (compressibility).
The organic matrix can in particular be obtained from epoxy resins, such as, for example, epoxy resin at 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 phenolic, while liquid precursors of ceramics, especially SiC, may be polycarbosilane type resins (PCS) or polytitanocarbosilane (PTCS) or polysilazane (PSZ).
After the polymerization, as illustrated in FIG.
obtains a piece 400 made of composite material comprising a reinforcement fibrous material consisting of the preform 200 densified by a matrix formed by the resin impregnated and polymerized in the preform. The demolding of the piece 400 is made by removing the male mold member 130, the flange 114 and the membrane 120.
The fibrous preform 200 is produced in a known manner by weaving using a jacquard loom on which we have arranged a bundle of warp yarns or strands into a plurality of layers, the warp threads being bound by weft threads or Conversely. The fibrous texture can be made by stacking strata or plies obtained by two-dimensional weaving (2D). By weaving two-dimensional means here a conventional weaving mode by which each weft thread passes from one side to the other of threads of a single layer of chain or vice versa. The fibrous texture can also be realized directly in one piece by three-dimensional weaving (3D) or multilayer. By three-dimensional weaving or multilayer weaving, here we mean a mode of weaving by which at least some of the son of weft bind string yarns on multiple layers of warp yarns or

12 inversely following a weave corresponding to a weave weave which can be chosen in particular from one of the following armor: interlock, multi-canvas, multi-satin and multi-twill. The fibrous preform can still be made from needle punched unidirectional fibrous layers between them.
The method of the invention is particularly suitable for allow the introduction of a liquid composition into textures fibrous 2D (textures obtained by stacking layers or 2D folds) or 3D of high thickness, that is fibrous structures having a at least 90 mm thick with a fiber content greater than 30%, example 40%. 3D textures also have geometry complex in which it is difficult to introduce and distribute homogeneous liquid compositions loaded or not. The process of the invention is also very well suited for the introduction of a liquid composition in 3D woven fiber textures.
The yarns used to form the fibrous preform 200 and, by therefore, the fibrous reinforcement of the composite material part 400 may consist in particular of fibers made from one of the materials carbon, silicon carbide, glass, alumina, mullite, aluminosilicate, borosilicate, or a mixture of several of these materials.
The method of the invention has been described previously in application to the manufacture of a frustoconical piece. However, the manufacturing method and the impregnation tooling of the invention also apply to the manufacture of composite material parts cylindrical shape. In this case, the preform, the lateral wall delimiting the cavity of the female mold element and the impermeable membrane and deformable have a cylindrical shape while the body axisymmetric of the male mold element fits inside a cylinder and has an outer surface of concave shape.

Claims (10)

13 1. Method for manufacturing a frustoconical piece (400) or cylindrical composite material comprising the steps following:
- Placement of a fibrous preform of frustoconical shape (200) or cylindrical in a female mold element (110) of a impregnation tooling (100), the female mold member (110) having a cavity (112) delimited by a side wall (111) having an inner frustoconical surface (111a) or cylindrical, the fibrous preform (200) being placed against the surface internal (111a) of said side wall (111), - placement of an impermeable and deformable membrane (120) opposite the exposed face (200a) of the fibrous preform (200), the membrane (120) having a frustoconical or cylindrical shape, the space delimited between the frustoconical internal surface (111a) or cylindrical side wall (111) of the female mold member (110) and the membrane (120) corresponding to an impregnation chamber (140) wherein the fiber preform (200) is present, - Assembling a male mold element (130) with the element female mold member (110), the male mold member (130) comprising a an axisymmetric body (131) housed in the cavity (112) of the mold element female (110), the outer surface (131a) of the axisymmetric body (131) being placed opposite and at a determined distance from the inner surface of frustoconical (111a) or cylindrical shape of the side wall (111) of the female mold member (110), the diaphragm (120) being interposed between the outer wall of the axisymmetric body (131a) of the male mold (130) and the frustoconical inner surface (111a) or cylindrical side wall (111) of the female mold member (110), the space delimited between the outer surface (131a) of the axisymmetric body (131) and the membrane (120) corresponding to a compaction chamber (150) injection of a resin (10) into the impregnation chamber (140) injecting a compaction fluid (20) into the chamber of compaction (150), the compaction fluid (20) exerting pressure on the membrane (120) for forcing the resin (10) to impregnate the preform fibrous (200), - polymerization of the resin to obtain a piece composite material (400) comprising fiber reinforcement densified by a matrix. 2. The process according to claim 1, wherein the resin (10) is injected at the lower edge (201) of the fibrous preform (200), the compaction fluid (20) being injected from the part lower part (151) of the compaction chamber (150) situated in the vicinity the lower edge (201) of the fibrous preform (200). 3. The process according to claim 2, wherein the resin (10) is injected into a circular channel (1131) present on the bottom (113) of the female mold member (110). 4. Method according to any one of claims 1 to 3, wherein, prior to injection of the resin (10) into the chamber impregnation (140), a depression is applied in the chamber of compaction (150). 5. Method according to any one of claims 1 to 4, wherein the fibrous preform (200) is obtained by weaving three-dimensional or multilayer. 6. Method according to any one of claims 1 to 4, wherein the fiber preform (200) is obtained by stacking fibrous strata obtained by two-dimensional weaving. 7. Method according to any one of claims 1 to 6, wherein the fibers of the fibrous preform (200) 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. 8. Process according to any one of claims 1 to 7, 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. 9. Impregnation tools (100) for a fibrous preform of frustoconical (200) or cylindrical shape, the tool comprising:
a female mold element (110) comprising a cavity (112) delimited by a side wall (111) having a surface internal frustoconical (111a) or cylindrical, a male mold element (130) comprising a body axisymmetric (131) housed in the cavity (112) of the mold element female (110), the outer surface (131a) of the axisymmetric body (131) being placed opposite and at a determined distance from the inner surface of frustoconical (111a) or cylindrical shape of the side wall (111) of the female mold member (110), an impermeable and deformable membrane (120) presenting a frustoconical or cylindrical shape, the membrane being placed opposite screw of the outer wall (131a) of the axisymmetric body (131) of the element of a male mold (130), the space delimited between the inner shape surface frustoconical (111a) or cylindrical side wall (111) of the element of the female mold (110) and the membrane (120) corresponding to a impregnation chamber (140), the space delimited between the external surface (131a) of the axisymmetric body (131) and the corresponding membrane (120) at a compaction chamber (150), the female mold element (110) comprising at least one resin injection port (115) opening into the chamber impregnation (140), the male mold element (130) comprising at least one port injecting (133) a compaction fluid opening into the chamber of compaction (150). The tool of claim 9, wherein each port injection (115) of resin opens into the impregnation chamber (140) at a bottom (113) of the female mold member (110), said bottom including a circular channel (1131) into which the or injection pits (115) of resin.