CRANKCASE FOR AN AIRCRAFT TURBOMACHINE AND MANUFACTURING METHOD FOR THE CRANKCASE

Abstract

The invention proposes an aircraft turbomachine casing, comprising an annular shell (9) extending around an axis A and made of a composite material comprising a fibrous texture reinforcement (13; 16, 17) embedded in a resin matrix (14), in which the shell (9) further comprises a metal ring (15) arranged radially internally to the fibrous texture reinforcement (13; 16, 17) and integrated into the resin matrix (14). The invention also provides a method for manufacturing an aircraft turbomachine housing (3) in which a metal ring (15) is placed on an impregnation mandrel (31) internally within the fibrous texture reinforcement (13; 16, 17) before a resin injection step (14) into an impregnation mold enclosing the impregnation mandrel (31) and the fibrous texture reinforcement (13; 16, 17). Figure 2

Description

Title of the invention: CASING FOR AN AIRCRAFT TURBOMACHINE AND METHOD FOR MANUFACTURING A CASING Technical field of the invention

[0001] The present invention relates to the production of a casing, in particular a fan casing, for an aircraft turbomachine. Technical background

[0002] Conventionally, a turbomachine comprises from upstream to downstream, that is to say in the direction of flow of the gas flows, a fan, one or more compressors, a combustion chamber, one or more turbines, and a nozzle for ejecting the combustion gases leaving the turbine(s).

[0003] [Fig.l] partially and schematically represents a fan 1 of an aircraft turbomachine.

[0004] The fan 1 comprises a bladed wheel 2 which is surrounded by a fan casing 3, also called a retention casing due to its retention function in the event of debris being ingested into the fan or blade being lost.

[0005] The fan casing 3 typically comprises an annular casing 9 with an axis of revolution A which extends around the fan blades 2 of the turbomachine. This casing comprises an annular fixing flange 3', 3” at each of its axial ends. These flanges 3', 3” are used to fix the casing 3 to annular walls of the nacelle of the turbomachine.

[0006] The fan casing 3 is connected, upstream, to an air inlet sleeve 5, and, downstream, to an intermediate casing shroud 6.

[0007] The casing also comprises an upstream acoustic shroud 7 and a downstream acoustic panel 8. The fan casing 3 also comprises an annular layer 4 of abradable material, positioned on an internal annular surface of the casing, between the upstream shroud 7 and the downstream panel 8.

[0008] In addition to the retention function, the fan casing 3 is also designed to: - ensure mechanical continuity (forces and moments) between the air inlet sleeve 5 and the intermediate casing shell 6; - allow the fixing of the vein panels (upstream ferrule 7, acoustic panel 8 and layer of abradable material 4), - allow the attachment of equipment and supports; - meet regulatory specifications for fire and leaks; - allow continuity of electric current for lightning resistance, etc.

[0009] A retention zone 10 is defined on the casing 9 opposite the fan blades 2 ([Fig. 1]). The retention zone 10 is for example conventionally locally materialized by an excess thickness 10' of the casing 9. The retention zone 10 can be defined between the front end of the layer of abradable material 4 and a rear limit directly radially opposite the blades 2 as illustrated in [Fig.l]

[0010] The envelope 9 may be made of composite material.

[0011] The retention capacity of a casing 3 with a casing 9 made of composite material is ensured by the quantity of fibers and the quality of the weaving of the composite material, in particular in the retention zone 10.

[0012] In a known turbomachine casing, glass plies are added in the retention zone on the composite casing after polymerization of the resin on the reinforcement of the composite material. The winding of the glass plies is then carried out over several turns during a relatively long operation.

[0013] In another turbomachine casing, the glass plies are replaced by Kevlar. The operation is long. Kevlar is subject to moisture absorption and degrades with age. The resulting part is of significant mass.

[0014] The invention therefore aims to propose an alternative to existing solutions for aircraft turbomachine casings with a reinforced retention zone. The invention therefore proposes in particular a turbomachine casing and a method for manufacturing such a casing. The invention must make it possible to improve the retention capacity of the casing. The invention must be simple, economical and easy to implement. Summary of the invention

[0015] The invention thus relates to an aircraft turbomachine casing, comprising an annular casing extending around a longitudinal axis and made from a composite material comprising:

[0016] - a fibrous texture reinforcement embedded in a resin matrix, and

[0017] - a metal ring integrated into the resin matrix,

[0018] characterized in that the fibrous texture reinforcement is arranged exclusively externally with respect to the metal ring.

[0019] The proposed solution thus makes it possible to reinforce the retention zone using the metal ring while limiting the thickness of the composite material in the retention zone. The metal ring is in fact capable of effectively retaining the metal leading edges of any lost rotor blades. By being positioned on the inner barrel of the turbomachine casing, the ring absorbs the first sharp impact in the event of blade loss. The risk and extent of damage to the composite material, i.e. of cutting of its strands, which would have the effect to interrupt the continuity of the composite material which is its strength, are thus strongly limited. The ring thus protects the composite material and absorbs part of the impact energy in the event of an impact.

[0020] The casing according to the invention may comprise one or more of the following characteristics, considered independently of one another or in combination with one another:

[0021] - the metal ring is made of a single layer of metal wound over 360°, so as to form a complete ring;

[0022] - the metal ring is arranged without direct or indirect superposition of the ring metallic on itself;

[0023] - the thickness of the metal ring is between 0.2 and 2 mm, preferably between 0.5 and 1mm;

[0024] - the metal ring is made of titanium;

[0025] - the metal ring is cylindrical in shape;

[0026] - the metal ring forms a complete ring and / or extending over 360°.

[0027] The invention also relates to an aircraft turbomachine comprising a casing according to the above.

[0028] The invention also relates to a method for manufacturing an aircraft turbomachine casing according to the above, the method comprising: placing the metal ring on an impregnation mandrel internally to the fiber texture reinforcement produced before a step of injecting resin into an impregnation mold enveloping the impregnation mandrel and the fiber texture reinforcement.

[0029] The method of manufacturing a casing according to the invention may comprise one or more of the following characteristics, considered independently of one another or in combination with one another:

[0030] - a step of placing the metal ring on the impregnation mandrel is carried out before a step of winding the reinforcement in fibrous texture onto the impregnation mandrel;

[0031] - the winding of the reinforcement in fibrous texture on the impregnation mandrel is carried out at least simultaneously with the installation of the metal ring on the impregnation mandrel.

[0032] The invention also relates to a method for manufacturing an aircraft turbomachine casing, this casing comprising an annular envelope extending around a longitudinal axis and made from a composite material comprising a fiber texture reinforcement embedded in a resin matrix,

[0033] the method comprising:

[0034] - a step of winding the reinforcement in fibrous texture onto a mandrel of impregnation and,

[0035] - a step of injecting resin into an impregnation mold surrounding the impregnation mandrel and fibrous texture,

[0036] method in which the annular envelope further comprises a metal ring, the metal ring being placed on the impregnation mandrel internally to the fiber texture reinforcement and before the step of injecting resin into the impregnation mold enveloping the impregnation mandrel and the fiber texture reinforcement. Brief description of the figures

[0037] Other characteristics and advantages of the invention will appear during the reading of the detailed description which follows for the understanding of which reference will be made to the appended drawings in which:

[0038] [Fig-1] The [Fig. 1] already discussed partially shows a sectional view of a fan of an aircraft turbomachine according to the state of the art;

[0039] [Fig.2] [Fig.2] is a perspective view of a fan casing according to the invention;

[0040] [Fig.3] [Fig.3] illustrates in schematic section a stack of layers of the envelope according to plane P of [Fig.2];

[0041] [Fig.4] [Fig.4] illustrates in perspective a step of a method of manufacturing a casing of a turbomachine fan housing according to the invention. Detailed description of the invention

[0042] In the following description, the invention is applied to a fan casing such as the casing 3 partially illustrated in [Fig. 1]. The invention is however not limited to this type of casing and can be applied to other casings of a turbomachine.

[0043] The casing 3 to which the invention applies has a generally annular shape around the longitudinal axis A. An arrow F materializes a forward direction of the elements illustrated with regard to their orientation once installed in the turbomachine.

[0044] The casing 3 comprises an annular envelope 9 which itself extends around the axis A ([Fig.2]).

[0045] As visible in [Fig.2], the casing 9 comprises the flanges 3' and 3” described in the preamble and a cylindrical part 9a, which extends longitudinally between the flanges 3' and 3”. The cylindrical part 9a has an internal surface 9aa delimiting an internal volume 9ab in which the rotor blades 2 mentioned in the preamble are housed.

[0046] The envelope 9 is here made of a composite material comprising a fiber texture reinforcement 13, a resin matrix 14 and a metal ring 15. More precisely, the fiber texture reinforcement 13 and the metal ring 15 are integrated into the resin matrix 14. The metal ring 15 is arranged radially inside the fiber texture reinforcement 13. In other words, the texture reinforcement fibrous is arranged exclusively externally with respect to the metal ring.

[0047] The manufacturing process allowing the metal ring 15 to be integrated into the resin 14 is detailed further on.

[0048] The metal ring 15 is in the form of a cylinder. The thickness of the metal ring is between 0.2 mm and 2 mm, preferably between 0.5 mm and 1 mm. The axial length of the metal ring 15 may correspond to all or part of the retention zone 10. This length is for example between 100 and 400 mm.

[0049] Since the interface between the composite material and the metal is in contact with the air in the turbomachine, the ring 15 is preferably made of titanium. The occurrence of galvanic corrosion is thus avoided.

[0050] As illustrated in [Fig.3], the envelope 9 can be formed from a stack, from the inside to the outside, of the metal ring 15 and the fibrous texture reinforcement 13. The fibrous texture reinforcement 13 here comprises substantially: two plies 16a of a first fibrous material 16 and one ply 17a of a second fibrous material different from the first fibrous material 17.

[0051] In the example of [Fig. 3], the metal ring 15 is made up of a single layer of metal wound over 360°, so as to form a complete ring. For example, two opposite ends of the ring can be abutted. Preferably, the metal ring 15 does not extend beyond 360°. Preferably, the metal ring 15 is thus arranged without direct superposition of the metal ring 15 on itself. Also preferably, the metal ring 15 is arranged without indirect superposition of the metal ring 15 on itself, that is to say without an element such as a part of a ply 16 or 17 of the reinforcement 13 being sandwiched between two thicknesses of the metal ring 15. More preferably, the fibrous texture reinforcement 13 is arranged exclusively externally with respect to the metal ring 15.Thus, the metal ring 15 is present only on the internal face 9aa of the envelope 9, and not between each thickness of the composite reinforcement, which makes it possible to avoid delamination of the envelope 9 and its plies 16 and 17.

[0052] In [Fig.3], the first fibrous material 16 is wound over two complete turns, so as to form the two plies 16a, and over an additional overlapping portion 16b of angular extent al around the longitudinal axis A. This makes it possible to guarantee continuity of the composite so that this area is not weakened. The angular extent al is for example between 1° and 20°.

[0053] In [Fig.3] also, the second fibrous material 17 is wound over a complete turn, so as to form the fold 17a, and over an additional overlapping portion 17b of angular extent a2 around the longitudinal axis A. This allows also to ensure good coverage so that this area is not weakened. The angular extent a2 is for example between 5° and 90°, preferably between 20 and 70°, and more preferably around 45°.

[0054] The casing 9 of the casing 3 is manufactured using an impregnation tool 30 provided with an impregnation mandrel 31, forming a central drum, illustrated in [Fig. 4]. The tool 30 also comprises an outer shell, not illustrated, complementary to the mandrel 31, and an internal surface of which makes it possible to form the outer surface 9ba of the casing 9 (see [Fig. 2]).

[0055] As illustrated in [Fig.4], the mandrel 31 has in particular a cylindrical longitudinal section 32 and a front radial section 33' and a rear radial section 33”.

[0056] The casing 9 of the casing 3 is manufactured by placing the metal ring 15 and the fiber texture reinforcement 13 around the impregnation mandrel 31. The metal ring is therefore placed during the shaping of the casing 9 at 360°. Once the fiber texture reinforcement 13 is in place on the mandrel 31, the reinforcement 13 defines a preform 10 ([Fig.4]) prefiguring the shape that the envelope 9 will take after injection of the resin matrix 14. The preform 10 here comprises a cylindrical longitudinal section 22 and a front radial section 23' and a rear radial section 23”, respectively arranged and formed on the longitudinal section 32 and the radial sections 33' and 33” of the mandrel 31. The radial sections 23' and 23” extend radially and outwards from the cylindrical longitudinal section 22.The cylindrical section 22 corresponds to the cylindrical part 9a of the casing 9, while the radial sections 23' and 23” correspond to the flanges 3' and 3”.

[0057] The casing manufacturing method may comprise:

[0058] - a step of winding the fibrous texture reinforcement 13 onto the mandrel of impregnation 31 and,

[0059] - a resin injection step 14 into the impregnation mold surrounding the impregnation mandrel 31 and the fibrous texture reinforcement 13.

[0060] Preferably, the aforementioned casing 3 is manufactured according to a method in which the positioning of the metal ring 15 on the impregnation mandrel 31 inside the fiber texture reinforcement 13 is carried out before a step of injecting resin 14 into an impregnation mold enveloping the impregnation mandrel 31 and the fiber texture reinforcement 13.

[0061] The placement of the metal ring 15 on the impregnation mandrel 31 can be carried out, at least partially, simultaneously with the winding of the fibrous texture reinforcement 13 onto the impregnation mandrel 31. As a variant, the placement of the metal ring 15 on the impregnation mandrel 31 is carried out before the winding of the fibrous texture reinforcement 13 onto the impregnation mandrel 31.

[0062]

[0063]

[0064]

[0065] During injection, for example by RTM injection (from the English Resin Transfer Molding), the resin polymerizes, which allows bonding of the metal ring 15 on the casing 9 by direct integration, therefore with excellent cohesion of the ring 15 and the other components. The invention provides advantages on several levels. From a technical point of view: - the reinforcement of the retention zone allows the use of a preform that is less mechanically efficient and therefore less expensive; - co-injection of the ring with the preform makes it possible to obtain a bonding interface between the ring and the casing that is more resistant than in the event of gluing the ring after injection. From an industrial point of view: - the addition of a metal ring inside the envelope in the manner described above allows the use of a lower performance composite preform, which allows for production hazards having an effect on the mechanical properties; - the manufacturing cycle is minimally affected thanks to the common injection which does not require additional tooling; - feedback is more important on metal parts than on composite materials. The invention therefore brings significant gains both on the technical and industrial levels.

Claims

Claims

1. Aircraft turbomachine casing, comprising an annular casing (9) extending around an axis A and made of a composite material comprising: - a fiber texture reinforcement (13; 16, 17) embedded in a resin matrix (14), and - a metal ring (15) integrated in the resin matrix (14), characterized in that the metal ring (15) consists of a single layer of metal wound over 360°, so as to form a complete split ring, and in that the fiber texture reinforcement (13; 16, 17) is arranged exclusively externally with respect to the metal ring (15).

2. Housing according to the preceding claim, in which the metal ring (15) is arranged without direct or indirect superposition of the metal ring (15) on itself.

3. Housing according to one of the preceding claims, in which the thickness of the metal ring (15) is between 0.2 and 2 mm, preferably between 0.5 and 1 mm.

4. Housing according to one of the preceding claims, in which the metal ring (15) is made of titanium.

5. Aircraft turbomachine comprising a casing according to one of the preceding claims.

6. Method for manufacturing a casing (3) of an aircraft turbomachine according to one of claims 1 to 4, the method comprising: placing the metal ring (15) on an impregnation mandrel (31), by winding a single layer of metal through 360° so as to form a complete split ring inside the fiber texture reinforcement (13; 16, 17), this placing being carried out before a step of injecting resin (14) into an impregnation mold enveloping the impregnation mandrel (31) and the fiber texture reinforcement (13; 16, 17).

7. Method of manufacturing a casing (3) according to the preceding claim, in which a step of placing the metal ring (15) on the impregnation mandrel (31) is carried out before a step of winding the fibrous texture reinforcement (13; 16, 17) on the impregnation mandrel (31).

8. A method of manufacturing a casing according to claim 7, wherein the winding of the fibrous texture reinforcement (13; 16, 17) onto the impregnation mandrel (31) is carried out at least simultaneously with the placement of the metal ring (15) onto the impregnation mandrel (31)

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