FR3161706A1 - TURBOMACHINE CRANKCASE FEATURING A THERMAL PROTECTION COATING AND A METHOD FOR MANUFACTURING THIS CRANKCASE - Google Patents

Abstract

The invention relates to a turbomachine (10) housing (3), particularly for aircraft, comprising: - an annular body (30) including a fibrous preform embedded in a first polymer matrix, and - an annular thermal protection coating (32) extending around the annular body (30) and being integral with the body (30), characterized in that the coating (32) has a fiber density of zero or less than that of the body (30) and comprises a second polymer matrix different from the first polymer matrix. Figure for the abstract: Figure 4

Description

TURBOMACHINE CRANKCASE FEATURING A THERMAL PROTECTION COATING AND A METHOD FOR MANUFACTURING THIS CRANKCASE Technical field of the invention

The present invention relates to the field of turbomachine housings, particularly for aircraft, comprising a thermal protection coating (for example, fire protection). The present invention also relates to a turbomachine comprising such a housing and a method for manufacturing such a housing.

Technical background

Typically, a turbomachine, particularly an aircraft turbomachine, comprises a casing arranged around one or more rotating components. One example of such a casing is a fan casing, which is centered on a longitudinal axis of the turbomachine. The fan casing is typically arranged around a fan rotor and its primary function is to retain the fan blades in the event of a partial or complete failure of one or more of them.

To reduce the overall mass of the turbomachine, it has been proposed to manufacture the turbomachine casings, particularly the fan casing, from composite material. The composite material typically comprises a fibrous preform embedded in a polymer matrix.

Such a composite housing is typically manufactured using resin transfer molding, also known by the acronym RTM. In the manufacturing process, for example, of a blower housing made of composite material, a fibrous preform is first arranged in a mold, and then a polymer resin is injected into the mold. The resin is then polymerized to form the polymer matrix of the blower housing's composite material.

In addition to its retention function, the turbomachine casing, particularly the blower casing, is also designed to meet fire and leakage regulations. These specifications require that, firstly, the mechanical characteristics of the casing be maintained during the onset of a flame and for fifteen minutes after the flame has been extinguished, and secondly, that fumes from the casing resin dissipate rapidly after the flame has been extinguished.

There FIG. 1 illustrates an example of a casing 3 of annular shape comprising an annular body 30 and an annular thermal protection coating 32, in particular against fire, which extends around this body 30.

The current manufacturing process for the housing with the annular thermal protection coating can be complex and costly. Currently, the thermal protection coating is applied manually around the annular body of the housing. Specifically, the coating is formed around the annular body by joining several sections of the coating end to end. This can generate non-conformities that are difficult to repair, such as visual defects, non-conformities in the overlap of the coating ends, etc. These non-conformities can compromise the mechanical strength of the housing under exceptional operating conditions such as fire or very high temperatures.

Furthermore, the manual application of the coating requires several control steps, such as the location of each portion of the coating, the length of the overlap areas between two portions of the coating to achieve a splice, the distance between two overlap areas, the repair (or touch-up) area allowed in case of non-conformities, etc.

There FIG. 2 illustrates an example of a housing 3 with several Z overlapping zones (or in other words splices) which are non-compliant.

In this context, it is interesting to propose a solution that addresses at least one of the aforementioned drawbacks, in particular by optimizing and simplifying the integration of a robust annular thermal protection coating into a turbomachine housing.

The present invention offers a simple, effective and economical solution to the aforementioned drawbacks of the prior art.

To this end, the invention proposes a turbomachine housing, particularly for aircraft, comprising:
- an annular body comprising a fibrous preform embedded in a first polymeric matrix, and
- an annular thermal protection coating extending around the annular body and being integral with the body.

According to the invention, the coating has a fiber density of zero or less than that of the body and comprises a second polymeric matrix different from the first polymeric matrix.

Thus, this solution achieves the aforementioned objective. Indeed, the housing according to the invention generally exhibits enhanced mechanical strength. In particular, the new configuration of the thermal protection coating of the invention increases the fire resistance (or, more generally, resistance to high temperatures) of the turbomachine housing. The second polymer matrix offers excellent resistance to high temperatures (especially above 200°C). The absence of fibers or a reduced fiber content (particularly compared to that of the annular body) combined with the second polymer matrix further increases the coating's heat resistance while simultaneously reducing the housing's weight.

The invention therefore has the advantage of being based on a simple design, offering very high reliability (in particular reinforced thermal protection), and little penalizing in terms of cost and size.

The housing according to the invention may comprise one or more of the following features, considered independently of each other or in combination with each other:

- the body and the covering are one piece;

- the second polymeric matrix is loaded with a phosphorus additive;

- at least one of the first and second polymer matrices comprises an epoxy, a bismaleimide or a polyester;

- the first and second polymer matrices comprise a common base, including an epoxy, a bismaleimide or a polyester, and distinct additives;

- the coating comprises a first annular layer and a second annular layer interposed between said first layer and the body, in which the first layer is made in said second polymeric matrix and the second layer is made in a third polymeric matrix different from the first polymeric matrix;

- the coating comprises a first annular layer and a second annular layer interposed between said first layer and the body, in which the first layer is made in said second polymeric matrix and the second layer is made in a third polymeric matrix identical to the first polymeric matrix;

-- the first, second and third polymer matrices may have a common base (which includes for example an epoxy, a bismaleimide or a polyester) and distinct additives.

The invention also relates to a turbomachine, particularly for aircraft, comprising a housing according to any one of the features of the invention. The housing could be, for example, a fan housing for the turbomachine.

The invention also relates to a method of manufacturing a turbomachine casing, in particular for an aircraft, according to any one of the features of the invention.

The housing thus comprises an annular body including a fibrous preform embedded in a first polymeric matrix, and an annular thermal protection coating extending around the annular body and being integral with the body, the coating having a fiber density of zero or less than that of the body and comprising a second polymeric matrix different from the first polymeric matrix.

The process includes the following steps:
(a) provide tooling comprising at least one annular injection compartment,
(b) arrange the fibrous preform in the injection compartment,
(c) inject a first resin into the injection compartment,
(d) pre-densify the fibrous preform by polymerizing the first resin, so as to pre-form the first polymer matrix,
(e) inject a second resin, and possibly a third resin, into the injection compartment around the fibrous preform pre-densified by the first resin, and
(f) simultaneously and completely polymerize the first and second resins, and optionally the third resin, so as to form the first and second polymer matrices, and optionally a third polymer matrix of said coating.

The process according to the invention facilitates the production of a turbomachine housing incorporating a thermal protection coating. Specifically, the process allows the second polymer matrix to be formed directly onto the fibrous preform, notably through the tooling configuration in which the first and second resins are injected into the same injection compartment containing the fibrous preform. This enables the formation of a robust bond between the fibrous preform embedded in the first polymer matrix and the second polymer matrix forming the thermal protection coating, particularly without the use of adhesives or mechanical fasteners such as bolts or rivets.

The process according to the invention also makes it possible to form the desired casing with the correct proportions of fiber volume fractions (TVF) and matrix volume fractions (TVM).

Furthermore, several steps of the process can be automated, such as the steps of forming the thermal protection coating in order to reduce, for example, the number of non-conformities related to the manual application of the coating.

By optimizing the manufacturing of the casing in composite material, the present invention makes it possible to reduce the environmental impact of these parts during operation, particularly in an aircraft turbomachine. Indeed, the composite material reduces the mass of the part, thereby reducing fuel consumption, which in turn leads to a reduction in polluting and/or harmful emissions (such as CO, CO2, NOx gases, etc.).

The method according to the invention may comprise one or more of the following features, considered independently of each other or in combination with each other:

- the process includes, between steps (c) and (d), the following substep:
(c ₁ ) inject a compaction fluid into an annular compaction compartment of the tooling which extends around the injection compartment and which is separated from this injection compartment by an elastically deformable membrane of the tooling;

- the process includes, between steps (e) and (f), the following substep:
(e ₁ ) inject a compaction fluid into the compaction compartment;

- the process includes, between steps (d) and (e), the following substep:
(d ₁ ) empty the compaction fluid from the compaction compartment;

- Step (e) is repeated at least twice, and between two successive steps (e), the process includes the following substeps:
step (e) of injecting the third resin into the injection compartment around the fibrous preform pre-densified by the first resin,
substep (e ₁ ) of injecting the compaction fluid into the compaction compartment,
(e ₂ ) polymerize the third resin,
(e ₃ ) empty the compaction fluid from the compaction compartment,
step (e) of injecting the second resin into the injection compartment around the third resin, and
the substep (e ₁ ) of injecting the compaction fluid into the compaction compartment;

- The process includes, between steps (a) and (b), the following substeps:
(i ₁ ) to create a fibrous texture by weaving fibers or by draping and layering several layers of fibers, and
(i ₂ ) shaping of the fibrous texture by winding it onto a mandrel, in order to obtain the fibrous preform intended to form the body of the housing;

-- the polymerization of the first resin in step (d) is partial and has a predetermined partial polymerization rate;

-- the predetermined partial polymerization rate is between 50 and 70%;

-- the polymerization of the first and second resins, and possibly the third resin, in step (f) is total and complete;

-- the polymerization rate of the first resin (also of the second resin, and possibly of the third resin) is 100% at step (f).

Brief description of the figures

The invention will be better understood and other details, features and advantages of the invention will become more apparent upon reading the following description, given by way of non-limiting example and with reference to the accompanying drawings in which:

there FIG. 1 is a schematic half-life in axial cross-section of a fan housing of a turbomachine according to the prior art,

there FIG. 2 is a schematic perspective view of the crankcase of the FIG. 1 including a thermal protection coating;

there FIG. 3 is a schematic perspective view of a turbomachine according to the invention,

there FIG. 4 is a schematic perspective view of an example of a turbomachine housing according to the invention,

there FIG. 5 is a schematic half-view in axial cross-section of another example of a housing according to the invention,

there FIG. 6 is a block diagram representing steps in a manufacturing process for the crankcase of the FIG. 4 or of the FIG. 5 ,

there FIG. 7 is a schematic half-view in axial section of a tool for making the housing of the FIG. 4 or of the FIG. 5 ,

there FIG. 8 is a schematic perspective view of a shaping step of a fibrous preform of an annular housing body on a mandrel according to the process of the FIG. 6 ,

there FIG. 9 is a schematic half-view in axial section of a step in the arrangement of the fibrous preform in the tooling of the FIG. 7 according to the process of FIG. 6 ,

there FIG. 10 is a schematic half-view in axial section of a closing step of the tooling of the FIG. 7 with the fibrous preform,

there FIG. 11 is a schematic half-view in axial section of a step in the injection of a first resin into an injection compartment of the tooling of the FIG. 7 according to the process of FIG. 6 ,

there FIG. 12 is a schematic half-view in axial section of a compaction fluid injection step into a compaction compartment of the tooling of the FIG. 7 according to the process of FIG. 6 ,

there FIG. 13 is a schematic half-view in axial cross-section of a step in the emptying of the compaction fluid from the compaction compartment according to the process of the FIG. 6 ,

there FIG. 14 is a schematic half-view in axial section of a step in the injection of a second or third resin into the injection compartment according to the process of the FIG. 6 ,

there FIG. 15 is a schematic half-view in axial section of a compaction fluid injection step into the compaction compartment according to the process of the FIG. 6 ,

there FIG. 16 is a schematic half-view in axial cross-section of a step in the polymerization of resins according to the process of the FIG. 6 ,

there FIG. 17 is a block diagram representing steps in the manufacturing process of the crankcase of the FIG. 5 .

Elements having the same functions in different implementations have the same references in the figures.

Detailed description of the invention

By convention, in the description below, the terms "longitudinal" and "axial" refer to the orientation of structural elements extending along a longitudinal axis (such as in a turbomachine or housing). The terms "radial" or "vertical" refer to the orientation of structural elements extending in a direction perpendicular to the longitudinal axis. The terms "interior" and "exterior," and "internal" and "external," are used to refer to positioning relative to the longitudinal axis. Thus, a structural element extending along the longitudinal axis has an interior face facing the longitudinal axis and an exterior surface opposite its interior surface.

Figures 1 and 2 have been described in the technical background of this application and illustrate an example of a turbomachine housing with a thermal protection coating.

An example of a turbomachine 10 according to the invention, in particular an aircraft turbomachine, is shown on the FIG. 1 The turbomachine 10 can be a turbofan engine.

The turbomachine 10 can extend along a longitudinal axis X. A gas flow F flows into the turbomachine 10.

Typically, the turbomachine 10 can comprise, from upstream to downstream (relative to the direction of gas flow F), a blower 1 and a gas generator. The gas generator can comprise, from upstream to downstream, at least one compressor 2a (for example, a low-pressure compressor and a high-pressure compressor), a combustion chamber 2b, at least one turbine 2c (for example, a high-pressure turbine and a low-pressure turbine), and optionally an exhaust nozzle (not shown in the figure). FIG. 1 ).

The gas flow F passes through the blower 1 and splits into a primary airflow through a primary channel and a secondary airflow through a secondary channel surrounding the primary channel. The primary airflow passes through the compressor 2a. The compressed primary airflow then passes through the combustion chamber 2b where it is mixed with fuel. The combustion gases then pass through the turbine 2c.

The blower 1 may include blades 1a (called blower blades) which are regularly distributed around the X axis.

The turbomachine 10 may include at least one housing 3, 4.

In the present invention, a casing is a fixed structure of the turbomachine 10.

Casing 3, 4 could be a blower casing 3. For example... FIG. 1 , the blower housing 3 can be arranged around the blades 2a.

The crankcase 3, 4 can be an intermediate crankcase 4. For example, the FIG. 1 , the intermediate casing 4 can be located downstream of the blower casing 3 and surround the compressor 2a.

In the following description, the invention is described below in the context of its application to the blower housing 3. However, the invention is not limited to the blower housing and can be applied to other turbomachine housings (such as the intermediate housing 4).

With reference to Figures 4 and 5, the housing 3 comprises an annular body 30 and an annular thermal protection coating 32 (also referred to as "coating" or "thermal protection coating" in this application).

The body 30 can extend around an axis A of revolution. The axis A corresponds approximately to the X axis of the turbomachine 10.

The body 30 may include an upstream annular mounting flange 34 and a downstream annular mounting flange 36, to allow the housing to be mounted and connected to other element(s) of the turbomachine. The upstream flange 34 and downstream flange 36 extend radially outwards at each of the axial ends of the body 3.

The body 30 can be made of composite material. In particular, the body 30 comprises a fibrous preform 300 embedded in (or otherwise densified or impregnated by) a first polymeric matrix.

The 300 fiber preform can include fibers, for example, woven in two or three dimensions. Alternatively, the 300 fiber preform can be layered and comprise several layers of fibers superimposed on one another.

The 300 fibrous preform may include glass fibers, carbon fibers, aramid fibers, polyamide fibers, ceramic fibers (such as silicon carbide, glass, or aramid), metallic fibers, oxide fibers, or a mixture of at least two of these fibers.

The first polymer matrix can be made from a thermosetting or thermoplastic material. In particular, the first polymer matrix can include an epoxy, a bismaleimide, or a polyester.

Advantageously, the fibrous preform 30 can include carbon fibers and the first polymer matrix includes epoxy (for example, an epoxy resin marketed under the name Cycom ^® PR 520 N).

The coating 32 extends around the body 3. The coating 32 is integral with this body 30. The coating 32 can be located on an external annular surface of the body 30, and possibly on radial walls of the upstream flanges 34 and downstream flanges 36 (figures 4 and 5).

The body 30 and the coating 32 can be one piece (i.e. made from one piece of material).

Coating 32 can be made of composite material.

One of the distinctive features of the invention is that the coating 32 has a fiber density of zero or less than that of the body 3 (in particular, the fibrous preform 300). The coating 32 comprises a second polymer matrix that differs from the first polymer matrix of the body 30.

The second polymer matrix can be made from a thermosetting or thermoplastic material. In particular, the second polymer matrix can include an epoxy, a bismaleimide, or a polyester.

The second polymer matrix can be loaded with a phosphorus additive. This enhances the flame-retardant properties of the coating 32. Alternatively, the second matrix can be loaded with any other flame-retardant additive, such as nitrogen compounds, silicone compounds, or inorganic hydroxides.

The first and second polymer matrices may comprise a common base, including an epoxy, a bismaleimide or a polyester, and distinct additives.

The term "common base" refers to a principal or dominant substance (or mixture of substances) constituting the first and second polymer matrices (and possibly the third polymer matrix). This principal substance may therefore be present in a majority proportion (or quantity) in the first and second polymer matrices (and possibly the third polymer matrix). The common base thus forms a main basic structure of the first and second polymer matrices (and possibly the third polymer matrix), and the distinct additives are additional elements added to at least one of the first and second polymer matrices to differentiate them. Consequently, the common base may comprise a larger proportion, and the additives may be elements present in smaller quantities (relative to the proportion of the common base). The common base may be defined in terms of percentage, mass, or other chemical parameters. For example, and without limitation, the first and second matrices (and possibly the third polymeric matrix) may have a common base with a proportion greater than 50% (by weight or by volume) and distinct additives with a proportion less than 50%.

With reference to the FIG. 5 The coating 32 may comprise a first annular layer 32a and a second annular layer 32b which is intercalated between the first layer 32a and the body 30. The first layer 32a comprises the second polymer matrix and the second layer 32b comprises a third polymer matrix.

The third polymer matrix of the second layer 32b may be different from the first polymer matrix. According to another variant, the third polymer matrix of the second layer 32b may be identical to the first polymer matrix.

The third polymer matrix of the second layer 32b can be identical to the second polymer matrix of the first layer 32a.

The third polymer matrix can be made from a thermosetting or thermoplastic material. In particular, the third polymer matrix can include an epoxy, a bismaleimide, or a polyester.

The third polymer matrix can be loaded with a phosphorus additive.

The first, second and third polymer matrices may have a common base (which includes, for example, an epoxy, a bismaleimide or a polyester) and distinct additives.

With reference to FIG. 6 to 17, the present application will now describe a manufacturing process for the turbomachine casing 3 (in particular described above with reference to figures 3 to 5).

There FIG. 6 diagrams the different stages of implementation of the process of the invention, in which the optional stages are represented by dotted lines.

The process according to the invention comprises the following steps:
(a) provide tooling 5 comprising at least one annular injection compartment 52,
(b) arrange the fibrous preform 300 in the injection compartment 52,
(c) inject a first resin R ₁ into the injection compartment 52,
(d) pre-densify the fibrous preform 300 by polymerizing the first resin R ₁ , so as to pre-form the first polymeric matrix,
(e) inject the second resin R ₂ , and possibly the third resin R ₃ , into the injection compartment 52 around the fibrous preform 300 pre-densified by the first resin R ₁ , and
(f) simultaneously and completely polymerize the first _R1 and second _R2 resins, and possibly the third resin _R3 , so as to form the first and second polymer matrices, and possibly a third polymer matrix of the coating 32.

The process according to the invention may include, between steps (c) and (d), the following substep:
(c ₁ ) inject a compaction fluid Fc into an annular compaction compartment 54 of the tooling 5 which extends around the injection compartment 52 and which is separated from this injection compartment 52 by an elastically deformable membrane 57 of the tooling 5.

The process according to the invention may include, between steps (d) and (e), the following substep:
(d ₁ ) empty the compaction fluid Fc from the compaction compartment 54.

The process according to the invention may include, between steps (e) and (f), a following substep:
(e ₁ ) inject a compaction fluid Fc into the compaction compartment 54.

The compaction fluid Fc injected at substep (e ₁ ) can be identical to that of substep (c ₁ ).

The process according to the invention may include a final step in which the housing 3 obtained at the end of step (f) is demolded.

There FIG. 7 illustrates a non-limiting example of tooling 5 enabling the production of the housing 3 of the invention.

Tooling 5 can be annular and extend around an axis of revolution. Tooling 5 can have a profile corresponding to that of the housing 3 to be produced.

The tooling 5 may include the annular injection compartment 52 and the annular compaction compartment 54. The compaction compartment 54 extends around the injection compartment 52 and is separated from this injection compartment 52 by the elastically deformable membrane 57. This membrane 57 may be annular.

For example, the FIG. 7 The tooling 5 may comprise at least two shells 56, 58 which are assembled to define between them an annular cavity 50. This annular cavity 50 may be intended to receive the fibrous preform 300. The two shells 56, 58 may comprise two annular shells, respectively internal 56 and external 58. The elastically deformable membrane 57 may be interposed between the two shells 56, 58, so as to separate the annular cavity 50 into two injection compartments 52 and compaction compartments 54.

The inner shell 56 may include a first resin injection port 562 which is connected to the injection compartment 52. This first port 562 may be configured to be connected to one or more resin source(s) for the purpose of injecting resin into the injection compartment 52.

The inner hull 56 may include a second outlet port 564 (or in other words a vent) which is connected to the injection compartment 52.

The resin source(s) may include one or more reservoirs containing resin(s) and one or more injectors for creating a vacuum in the injection compartment 52 if necessary, and/or for supplying resin(s) from the source to the injection compartment 52, and/or for draining excess resin(s) from the injection compartment 52 back to the resin source(s). For example, the source may include separate reservoirs containing, respectively, the first resin _R1 and the second resin _R2 , and possibly a third resin _R3 .

The third resin _R3 may be identical to the second resin _R2 and may be different from the first resin _R1 . Alternatively, the third resin _R3 may be identical to the first resin _R1 and may be different from the second resin _R2 .

_R1 , _R2 , _R3 resins may have a common base (which includes, for example, an epoxy, a bismaleimide, or a polyester) and distinct additives.

The first 562 and second 564 ports can be located on two opposite sides of the inner shell 56. The first port 562 can open, on the one hand, into the injection compartment 52, and on the other hand, to the outside of the tooling 5, in particular to the resin source(s). Similarly, the second port 564 can open, on the one hand, into the injection compartment 52, and on the other hand, to the outside of the tooling 5, in particular to the resin source(s).

The outer shell 58 may include a third port 582 for injecting compaction fluid Fc which is connected to the compaction compartment 54. This third port 562 may be configured to be connected to a source of compaction fluid for the purpose of supplying the compaction compartment 54 with compaction fluid Fc.

The outer shell 58 may include a fourth output port 584 which is connected to the compaction compartment 54.

The compaction fluid source Fc may include a reservoir containing the compaction fluid Fc and an injector to create a vacuum in the compaction compartment 54 if required, and/or for supplying compaction fluid Fc from the source to the compaction compartment 54, and/or for draining excess compaction fluid Fc from the compaction compartment 54 to the compaction fluid source Fc.

As an example, the compaction fluid Fc can be water or oil.

The third 582 and fourth 584 ports can be located on two opposite sides of the outer shell 58. The third port 582 can open, on the one hand, into the compaction compartment 54, and on the other hand, outside the tooling 5, in particular at the compaction fluid source Fc. Similarly, the fourth port 584 can open, on the one hand, into the compaction compartment 54, and on the other hand, outside the tooling 5, in particular at the compaction fluid source Fc.

The outer shell 58 can include several angular sectors extending around the axis of revolution of the tooling 5. The number of angular sectors can be between two and ten.

The port(s) 562, 564, 582, 584 can be formed directly in the corresponding hull (i.e. at least one of the inner hull 56 and outer hull 58).

Port(s) 562, 564, 582, 584 can form a passage hole for resin(s) or compaction fluid Fc.

The process of the invention may include, between steps (a) and (b), the following substeps:
(i ₁ ) produce a T ₃₀₀ fibrous texture by weaving fibers or by draping and layering several fibers, and
(i ₂ ) shaping of the fibrous texture T ₃₀₀ by winding on a mandrel 6, in order to obtain the fibrous preform 300 intended to form the body 30 of the housing 3.

At step (i ₁ ), the weaving of fibres can be carried out in two dimensions or in three dimensions, for example by means of a Jacquard type loom, to form a woven T ₃₀₀ fibrous texture.

As an alternative to step (i ₁ ), draping and layering several layers of fibers makes it possible to form a stratified T ₃₀₀ fibrous texture.

There FIG. 8 illustrates a non-limiting example of a mandrel 6 allowing the formation of the fibrous preform 300 in step (i ₂ ). The mandrel 6 can be annular and extend around an axis of revolution.

The mandrel 6 can have a profile corresponding to that of the housing 3 to be produced. To achieve this, the mandrel 6 can include an external annular surface 60 corresponding to an internal annular surface of the housing 3 to be produced. By winding around the mandrel 6, the fibrous texture T ₃₀₀ conforms to its profile. The mandrel 6 can also include two flanges 62, 64 to form portions of the fibrous preform 300 corresponding to the upstream flanges 34 and downstream flanges 36 of the housing 3.

The fibrous texture T ₃₀₀ , whether woven or laminated, in the form of a strip can be wound several times around the mandrel 6 and form the fibrous preform 300.

The 300 fibrous preform can be dry, that is to say, it is not pre-impregnated with resin.

There FIG. 9 illustrates an example of an embodiment of step (b), in which the fibrous preform 300, in particular from step (i ₂ ), can be placed in the cavity 50, and in particular in the injection compartment 52 of the tooling 5. The cavity 50 can have a shape complementary to that of the fibrous preform 300.

Once the fibrous preform 300 (with or without the mandrel 6) is installed in the injection compartment 52, the elastically deformable membrane 57 covers the injection compartment 52 and at least partially the inner shell 56. Then, the assembly is hermetically sealed by the outer shell 58, as illustrated, without limitation, in the FIG. 10 .

There FIG. 11 illustrates an example of implementation of step (c) in which, once tooling 5 is closed, the first resin R ₁ can be injected into the injection compartment 52 through the first port 562 of tooling 5.

The quantity of first resin R ₁ injected can correspond to the volume of the fibrous preform 300 to be impregnated and to the desired TVF and TVM rates in the annular body 30 of the housing 3 to be produced.

The first _R1 resin can be thermosetting or thermoplastic. For example, the first _R1 resin may comprise an epoxy, a bismaleimide, or a polyester. Advantageously, the first _R1 resin may be an epoxy, for example, the epoxy resin marketed under the name ^Cycom® PR 520 N.

There FIG. 12 illustrates an example of implementation of substep (c ₁ ) in which the compaction fluid Fc can be injected into the compaction compartment 54 through the third port 582. This allows the fibrous preform 300 impregnated with the first resin R ₁ to be compacted.

Step (c ₁ ) may also include vacuuming the tooling 5 to trap the fibrous preform 300 locally between the inner shell 56 and the elastically deformable membrane 57. In this way, the membrane 57 can apply a compaction force to the fibrous preform 300, pressing it against the bottom of the cavity 50. The vacuuming can be achieved by removing the air from the injection compartment 62 through the second port 564. This vacuuming can be carried out simultaneously with the injection of the compaction fluid Fc.

The amount of compaction fluid Fc injected can correspond to a desired level of homogeneous hydrostatic pressure. This level of hydrostatic pressure forces the first resin _R1 to impregnate the fibrous preform 300 and fill the porosity of the fibrous preform 300 throughout its entire volume.

After substep (c ₁ ), an excess quantity of first resin R ₁ can be discharged through the fourth port 584 of the tooling.

After impregnation of the fibrous preform 300 by the first resin R ₁ , the tooling 5 can be heated to pre-densify the fibrous preform 300 by polymerization and hardening of the first resin R ₁ .

The term "pre-densify" refers to a partial densification of the fibrous preform 300 by the first resin R _1. In particular, the first resin R ₁ can be partially polymerized and partially hardened in the fibrous preform 300.

The polymerization of the first resin _R1 may be partial and exhibit a predetermined partial polymerization rate. The predetermined partial polymerization rate of the first resin _R1 may be between 50 and 70% at step (d).

The heating of tooling 5 can be carried out at a predetermined temperature between 100°C and 200°C, and for a predetermined duration between 10h and 20h (hour).

This predetermined temperature and heating time allow, in particular, the partial polymerization of the first resin R ₁ to be achieved.

At the end of step (d), the fibrous preform 300 can therefore be embedded in the first resin _R1 , which has a viscous, gel-like consistency. This particular consistency of the first resin _R1 allows for the preforming of the first polymer matrix of the annular body 30 of the housing 3 to be produced. In particular, the viscosity of the first resin at the end of step (d) may be less than its elasticity.

Tooling 5 can be cooled before carrying out substep (d ₁ ).

There FIG. 13 illustrative example of implementation of substep (d ₁ ) in which the compaction fluid Fc contained in the compaction compartment 54 can be emptied for example through the fourth port 584 of the tooling 5. This allows the compaction force applied by the membrane 57 on the fibrous preform 300 to be released, so as to carry out step (e).

There FIG. 14 illustrates an example of implementation of step (e) in which the second resin R ₂ , and possibly the third resin R ₃ , can be injected into the injection compartment 52 of the tooling 5 through the first port 562.

The second resin R ₂ (or the third resin R ₃ ) can at least partially cover the pre-densified fibrous preform 300 by the first resin R ₁ .

The quantity of second resin R ₂ injected can correspond to a predetermined thickness of the thermal protection coating 32 to be formed and the desired TVM rate in the final part 3, for example when the coating 32 comprises only the first layer 32a containing the second polymer matrix.

The second resin _R2 can be either thermosetting or thermoplastic. For example, the second resin _R2 could include an epoxy, a bismaleimide, or a polyester.

The second resin _R2 may be different from the first resin _R1 .

The second resin _R2 can be filled with a phosphorus additive. Advantageously, the second resin _R2 can be an epoxy, for example the epoxy resin marketed under the name ^Cycom® PR 520 N, and filled or not with the phosphorus additive.

The first _R1 and second _R2 resins may include a common base (e.g., containing an epoxy, a bismaleimide, or a polyester), and distinct additives.

The third resin _R3 can be of the thermosetting or thermoplastic type. For example, the third resin _R3 can include an epoxy, a bismaleimide, or a polyester.

The third resin _R3 can be loaded with a phosphorus additive. Advantageously, the third resin _R3 can be an epoxy, for example the epoxy resin marketed under the name ^Cycom® PR 520 N, with or without a phosphorus additive.

There FIG. 15 illustrates an example of implementation of substep (e ₁ ) in which the compaction fluid Fc can be injected into the compaction compartment 54 through the third port 582. This allows the second resin R ₂ (or the third resin R ₃ ) extending around the pre-densified fibrous preform 300 of the first resin R ₁ to be compacted.

The amount of compaction fluid Fc injected can correspond to a desired level of homogeneous hydrostatic pressure. This level of hydrostatic pressure allows a compaction force to be applied to the second resin _R2 (or the third resin _R3 ) and the pre-densified 300 fibrous preform.

After substep (e ₁ ), an excess quantity of second resin R ₂ (or third resin R ₃ ) can be removed through the second port 564 of the tooling, for example by drainage.

There FIG. 16 illustrates an example of implementation of step (f) in which tooling 5 can be heated to simultaneously polymerize and cure the first R ₁ and second R ₂ resins, and possibly the third resin R ₃ .

At step (f), the polymerization of the first R ₁ and second R ₂ resins (and possibly the third resin R ₃ ) can be total and complete.

The polymerization rate of the first resin R ₁ (and also of the second resin R ₂ and possibly of the third resin R ₃ ) can be 100% at the end of step (f).

The heating of tooling 5 can be carried out at a predetermined temperature between 100°C and 200°C, and for a predetermined duration between 10h and 20h (hour).

This predetermined temperature and predetermined heating time allows in particular to obtain a complete polymerization of the first R ₁ and second R ₂ resins (and possibly the third resin R ₃ ) and forms the first and second polymer matrices (and possibly the third polymer matrix) of the housing 3.

Furthermore, during this step (f), covalent bonds can be created at the interface between the first _R1 and second _R2 resins (or between the first _R1 and third _R3 resins) to form a homogeneous network of crosslinking points.

Step (f) thus makes it possible to form the desired housing 3, namely the annular body 30 and the thermal protection coating 32 extending around this body 30.

Step (e) of the process may be repeated at least twice, and between two successive steps (e), the process may include the following substeps:
step (e) of injecting the third resin R ₃ into the injection compartment 52 around the fibrous preform 300 pre-densified by the first resin R ₁ ,
substep (e ₁ ) of injecting the compaction fluid Fc into the compaction compartment 54,
(e ₂ ) polymerize the third resin R ₃ ,
(e ₃ ) empty the compaction fluid Fc from the compaction compartment 54,
step (e) of injecting the second resin R ₂ into the injection compartment 52 around the third resin R ₃ , and
the substep (e ₁ ) of injecting the compaction fluid Fc into the compaction compartment 54.

Carrying out step (e) in at least two stages makes it possible to form the thermal protection coating 32 with the first layer 32a and the second layer 32b described in particular with reference to the FIG. 5 .

When step (e) is carried out at least twice (in particular with a succession of injection of third resin R ₃ then of second resin R ₂ ), the different resins R ₁ , R ₂ , R ₃ of the injection compartment 52 can be polymerized simultaneously and totally in step (f).

The polymerization of the third resin _R3 in substep ( _e2 ) may be partial and exhibit a predetermined partial polymerization rate. The predetermined partial polymerization rate of the second resin _R2 may be between 50 and 70% in step ( _e2 ).

Substep (e ₂ ) allows preforming the third polymer matrix of the thermal protection coating 32 of the housing 3 to be produced.

Polymerization at substep (e ₂ ) can be carried out by heating tooling 5 to a predetermined temperature between 100°C and 200°C, and a predetermined duration between 10h and 20h (hour).

This predetermined temperature and predetermined heating time allow for partial polymerization of the third resin R ₃ .

Substep (e ₃ ) can be carried out in the same way as substep (d ₁ ).

There FIG. 17 diagrams a second, non-limiting example of the process of the invention in which step (e) is performed twice. Depending on the embodiment of the FIG. 17 The process according to the invention may include the following steps:
(a) provide the tooling 5 comprising the injection compartment 52 and the compaction compartment 54 extending around the injection compartment 52 and separated from this injection compartment 52 by the elastically deformable membrane 57,
(b) arrange the fibrous preform 300 in the injection compartment 52,
(c) inject the first resin R ₁ into the injection compartment 52,
(c ₁ ) inject the compaction fluid Fc into the compaction compartment 54,
(d) pre-densify the fibrous preform 300 by polymerizing the first resin R ₁ , so as to pre-form the first polymeric matrix,
(d ₁ ) empty the compaction fluid Fc from the compaction compartment 54,
step (e) of injecting the third resin R ₃ into the injection compartment 52 around the fibrous preform 300 pre-densified by the first resin R ₁ ,
substep (e ₁ ) of injecting the compaction fluid Fc into the compaction compartment 54,
(e ₂ ) polymerize the third resin R ₃ ,
(e ₃ ) empty the compaction fluid Fc from the compaction compartment 54,
step (e) of injecting the second resin R ₂ into the injection compartment 52 around the third resin R ₃ ,
the substep (e ₁ ) of injecting the compaction fluid Fc into the compaction compartment 54, and
(f) simultaneously and completely polymerize the first _R1 , second _R2 and third _R3 resins, so as to form, respectively, the first, second and third polymeric matrices.

The manufacturing process of the FIG. 17 This allows the coating 32 to be formed, comprising the first 32a and second 32b layers around the annular body 30, as illustrated in a non-limiting way on the FIG. 5 .

Claims (14)

Turbomachine (10) housing (3), in particular for aircraft, comprising:
- an annular body (30) comprising a fibrous preform embedded in a first polymeric matrix, and
- an annular thermal protection coating (32) extending around the annular body (30) and being integral with the body (30), characterized in that the coating (32) has a fiber density of zero or less than that of the body (30) and comprises a second polymeric matrix different from the first polymeric matrix. Turbomachine housing according to claim 1, characterized in that the body (30) and the cladding (32) are monoblocs. Turbomachine housing according to claim 1 or 2, characterized in that the second polymeric matrix is loaded with a phosphorus additive. Turbomachine housing according to any one of claims 1 to 3, characterized in that at least one of the first and second polymer matrices comprises an epoxy, a bismaleimide or a polyester. Turbomachine housing according to any one of claims 1 to 3, characterized in that the first and second polymer matrices comprise a common base, comprising an epoxy, a bismaleimide or a polyester, and distinct additives. Turbomachine housing according to any one of claims 1 to 5, characterized in that the coating (32) comprises a first annular layer (32a) and a second annular layer (32b) intercalated between said first layer (32a) and the body (30), in which the first layer (32a) is made in said second polymeric matrix and the second layer (32b) is made in a third polymeric matrix different from the first polymeric matrix. Turbomachine housing according to any one of claims 1 to 5, characterized in that the coating (32) comprises a first annular layer (32a) and a second annular layer (32b) interposed between said first layer (32a) and the body (30), in which the first layer (32a) is made in said second polymeric matrix and the second layer (32b) is made in a third polymeric matrix identical to the first polymeric matrix. Turbomachine (1), in particular aircraft, characterized in that it comprises a casing (3) according to any one of the preceding claims, said casing (3) being for example a fan casing of the turbomachine (1). Method for manufacturing a turbomachine (1) housing (3), in particular for aircraft, the housing (3) comprising an annular body (30) including a fibrous preform (300) embedded in a first polymeric matrix, and an annular thermal protection coating (32) extending around the annular body (30) and being integral with the body (30), the coating (32) having a fiber density of zero or less than that of the body (30) and comprising a second polymeric matrix different from the first polymeric matrix,
The process involves the following steps:
(a) provide tooling (5) comprising at least one annular injection compartment (52),
(b) arrange the fibrous preform (300) in the injection compartment (52),
(c) inject a first resin (R ₁ ) into the injection compartment (52),
(d) pre-densify the fibrous preform (300) by polymerizing the first resin (R ₁ ), so as to pre-form the first polymeric matrix,
(e) inject a second resin (R ₂ ), and possibly a third resin (R ₃ ), into the injection compartment (52) around the fibrous preform (300) pre-densified by the first resin (R ₁ ), and
(f) simultaneously and completely polymerize the first (R ₁ ) and second (R ₂ ) resins, and possibly the third resin (R ₃ ), so as to form the first and second polymeric matrices, and possibly a third polymeric matrix of the coating (32). A manufacturing process according to claim 9, characterized in that it comprises, between steps (c) and (d), a following substep:
(c ₁ ) inject a compaction fluid into an annular compaction compartment (54) of the tooling (5) which extends around the injection compartment (52) and which is separated from this injection compartment (52) by an elastically deformable membrane of the tooling (5). A manufacturing process according to claim 10, characterized in that it comprises, between steps (e) and (f), a following substep:
(e ₁ ) inject a compaction fluid into the compaction compartment (54). A manufacturing process according to claim 11, characterized in that it comprises, between steps (d) and (e), a following substep:
(d ₁ ) empty the compaction fluid from the compaction compartment (54). A manufacturing process according to any one of claims 9 to 12, characterized in that step (e) is repeated at least twice, and between two successive steps (e), the process comprises the following substeps:
step (e) of injecting the third resin (R ₃ ) into the injection compartment (52) around the fibrous preform (300) pre-densified by the first resin (R ₁ ),
the substep (e ₁ ) of injecting the compaction fluid (Fc) into the compaction compartment (54),
(e ₂ ) polymerize the third resin (R ₃ ),
(e ₃ ) empty the compaction fluid (Fc) from the compaction compartment (54),
step (e) of injecting the second resin (R ₂ ) into the injection compartment (52) around the third resin (R ₃ ), and
the substep (e ₁ ) of injecting the compaction fluid (Fc) into the compaction compartment (54). A manufacturing process according to any one of claims 9 to 13, characterized in that it comprises, between steps (a) and (b), the following substeps:
(i ₁ ) produce a fibrous texture (T ₃₀₀ ) by weaving fibers or by draping and layering several layers of fibers, and
(i ₂ ) shaping of the fibrous texture (T ₃₀₀ ) by winding on a mandrel (6), in order to obtain the fibrous preform (300) intended to form the body (30) of the housing (3).