This invention relates to the manufacture of a casing, in particular of a fan, for an aircraft turbine engine.
The prior art comprises in particular, the documents FR-A1-2 997 725, FR-A1-2 997 726, FR-A1-3 005 100, US-A1-2014/367 290 and FR-A1-3 037 854.
In a known way, a double or triple body turbine engine comprises, from upstream to downstream, i.e., in the direction of flow of the gas streams, a fan, at least one low-pressure compressor, a high-pressure compressor, a combustion chamber, a high-pressure turbine, at least one low-pressure turbine, and an exhaust nozzle of the combustion gases leaving the turbines. A rotor of the high-pressure compressor is connected to a rotor of the high-pressure turbine by a high-pressure shaft, and these rotors form a high-pressure body. At least one rotor of a low-pressure compressor is connected to a rotor of a low-pressure turbine by a low-pressure shaft, and these rotors thus form at least one low-pressure body. The low-pressure shaft passes coaxially through the high-pressure shaft and drives a rotor of the fan, either directly or via a reducer.
The fan comprises a bladed wheel surrounded by a fan casing, also known as a retention casing, because of its function of retaining the vanes in the event of their breakage, or in the event of debris entering the fan. Such a casing is composed of an axial annular envelope which extends around the fan blades of the turbine engine and which comprises an upstream annular section carrying upstream acoustic panels on the inside, a downstream section carrying downstream acoustic panels on the inside, and an intermediate section, arranged axially between the upstream and downstream sections, comprising a first internal annular surface to which is attached an annular cartridge of abradable material, made in one piece or sectorized. The fan casing is connected upstream to an air inlet sleeve downstream, to a shroud of an intermediate casing of the turbine engine.
In addition to its retention function, the fan casing ensures the continuity of the aerodynamic vein via the annular cartridge made of abradable material. It also ensures a mechanical continuity of forces and moments between the air inlet sleeve and the shroud of the intermediate casing. It can also be used to fix various items of equipment and supports, to ensure compliance with fire and leakage regulations, and to ensure continuity of electrical current to withstand lightning strikes on the turbine engine.
The annular cartridge of abradable material is made, for example, in the form of a shroud produced by injection molding or in the form of an assembly of sectors.
The annular cartridge is conventionally immobilized axially with respect to the envelope so that it coincides axially with the intermediate section of the envelope provided for this purpose. To do this, the intermediate section of the envelope conventionally comprises, at least one of its ends, a series of axial abutments which are fixed to an inner circumference of the envelope, to receive the annular cartridge in abutment, in order to define its position.
The annular cartridge is then flanged in the envelope and subjected to a bonding step on the first internal annular surface, during which the casing is heated and held and compressed by means of a removable system arranged at least partly inside the casing. Thanks to the removable system, a mechanical pressure force is applied to the annular cartridge, enabling the annular cartridge to be held in position during the heating step. The bonding is carried out in an autoclave.
Conventionally, the axial abutments are attached to the envelope. For example, the envelope receives skids each having a longitudinal portion extending along the first internal annular surface and a transverse portion extending perpendicular to the longitudinal portion and forming an axial abutment. The longitudinal portion comprises bores that are intended to be crossed with screws allowing the attachment of each skid to the envelope.
This technical solution requires a preliminary bore of the envelope according to a rigorous positioning, and then each of the skids to be mounted, which increases the cost of manufacturing such a casing.
There is therefore a need for a casing for a turbine engine equipped with one or more axial abutments means of simple embodiment that do not require complex mounting operations.
The invention responds to this need by proposing a method for manufacturing a casing for a turbine engine comprising one or more axial abutment means integrated directly into the envelope during its manufacture.
To this end, the invention proposes a method for manufacturing a casing for an aircraft turbine engine, comprising at least:
This embodiment allows us to produce an envelope of casing in which the abutment means are integrated into the envelope during its manufacture, with the advantage of not requiring costly and time-consuming operations after the envelope has been manufactured.
According to other characteristics of the method:
The invention also relates to an annular envelope of axis A of a casing for a turbine engine molded by resin injection from an annular preform made of 3-dimensional woven fibres, characterised in that it comprises at least one annular intermediate section which is intended to receive an annular cartridge made of an abradable material and a first internal annular surface of which comprises at least one axial abutment means which projects from said first internal annular surface and which is molded with the resin of said envelope.
Other characteristics of the envelope include:
The invention also relates to a mold for manufacturing of an annular envelope of a casing for a turbine engine of the type described above, characterised in that it comprises an outer annular shell of axis A with an inner annular recess and an inner annular shell of axis A with an outer annular recess, said recesses delimiting a cavity of the mold, said shells being capable of being arranged respectively outside and inside the preform so that the cavity receives a preform and is filled with resin by injection, characterized in that an intermediate section of the inner shell comprises an annular groove of axis A formed in the outer annular recess and capable of being filled with resin.
Finally, the invention relates to a dual-flow aircraft turbine engine comprising a fan casing of the type described above.
Further characteristics and advantages of the invention will become apparent from the following detailed description, for the understanding of which reference is made to the attached drawings in which:
In a known way, a double or triple body turbine engine comprises, from upstream to downstream, i.e., in the direction of flow of the gas streams, a fan, at least one low-pressure compressor, a high-pressure compressor, a combustion chamber, a high-pressure turbine, at least one low-pressure turbine, and an ejection nozzle of the combustion gases leaving the turbines. A rotor of the high-pressure compressor is connected to a rotor of the high-pressure turbine by a high-pressure shaft, thus forming a high-pressure body. At least one rotor of a low-pressure compressor is connected to a rotor of a low-pressure turbine by a low-pressure shaft, thus forming at least one low-pressure body. The low-pressure shaft passes coaxially through the high-pressure shaft and drives a rotor of the fan, either directly or via a reducer.
The fan 10 comprises a bladed wheel 12 which is surrounded by a fan casing 14, also known as a retention casing because of its function of retaining the vanes in the event of their breakage, or in the event of debris entering the fan.
In the remainder of this description, the invention is applied to a fan casing 14. However, the invention is not limited to this type of casing and can be applied to other casings of a turbine engine.
As can be seen more particularly in
As illustrated more particularly in the schematic section of
This cartridge 30 can be made either in the form of an annular shroud, or in the form of panels forming angular sectors of shroud, which are assembled to one another.
As we have seen, the casing 14 comprises an annular envelope 16 extending around the axis A, which is made from a composite material comprising woven fibres embedded in a resin. The envelope 16 comprises an upstream section 32, suitable for receiving the upstream acoustic panel 26, a downstream section 34, suitable for receiving the downstream acoustic panel 26, and an intermediate section 36, suitable for receiving the cartridge 30 made of abradable material.
The annular cartridge 30 covers a first internal annular surface 38 of the intermediate section 36, while the upstream acoustic panel 26 is fixed to a second internal annular surface 40 of the upstream section 3,2 for example using screwing means 41, and the downstream acoustic panel 26 is attached to a third internal annular surface 42 of the downstream section 34, for example using screwing means 43.
The annular cartridge 30 is designed to be attached by bonding to the first internal surface 38 of the envelope 16.
To do this, the cartridge 30 is uniquely positioned axially in the envelope 14, then immobilised therein. This is followed by a bonding step, during which the casing 14 is subjected to heat treatment under pressure.
In practice, during the bonding operation, and more specifically during the heating operation, the casing 14 is placed in an autoclave (not shown) so that its axis A is oriented vertically.
A pressurisation system 54 can be fitted inside the casing 14, this system 54 being shown schematically in
The skids 50, 52 allow the cartridge 30 to be axially immobilized in the intermediate section 36, forming axial abutment means.
In the example shown here, the tooling 44 comprises two series 46, 48 of skids 50, 52 forming axial abutments, but this configuration is not restrictive of the invention, and the tooling could comprise only one series 46 or 48 of skids 50 or 52 to receive a first end of the cartridge 30 as a abutment, the latter being immobilised axially in another way at its second opposite end.
The skid 50 comprises a longitudinal portion 56 and a transverse portion 58. The longitudinal portion 56 is designed to be mounted in a removable manner against the envelope 16 and more precisely against the respective first internal annular surface 38 of the intermediate section 36 designed to receive the cartridge 30 made of abradable material, at one end of this section 36. To do this, the longitudinal portion 56 comprises at least one bore 60 through which a fastening means (not shown), such as a screw, pin, fastener, etc., can pass and which is received in the intermediate section 36.
The transverse portion 58 is designed to extend transversely to the longitudinal portion 56. The transverse portion 58 has a contact surface 62 designed to receive and bear against the cartridge 30 made of abradable material. The skid 50 can be made in two parts, the longitudinal portion 56 being positioned in contact with the respective first internal annular surface 38 of the intermediate section 36 and fixed by means of the aforementioned screws, before the transverse portion 58 is mounted on the longitudinal portion 56.
Each series 46, 48 of skids 50, 52 comprises between 4 and 20 skids distributed evenly, i.e., equidistantly, around the periphery of the end of the intermediate section 36 of the envelope. The bearing load of the cartridge 30 is thus distributed evenly around the circumference.
A method for manufacturing a casing 14 according to the prior art comprises a first step of manufacturing the annular envelope 16, during which an annular preform of axis A of the envelope is placed, made of a composite material comprising 3-dimensional woven fibres, in a mold which comprises an annular cavity for complementarily receiving the preform, then during which a resin is injected into said cavity and the resin is subsequently polymerised. As this embodiment has been extensively documented by the prior art, it is cited here only for the record and will not be the subject of a broader description.
Then, during a second step, a first series 48 of skids 52 forming as many axial abutment means is arranged projecting from the first internal annular surface 38 of the intermediate section 36 of the envelope 16, at a first end of said intermediate section 36.
Then, in a third step, the annular cartridge 30 made of abradable material is placed inside the annular envelope 16 in contact with the skids 52, covering the first annular surface 38. A second series 46 of skids 50 are then arranged, forming axial abutment means projecting from the first internal annular surface 38 of the intermediate section 36 of the envelope 16, at a second end of the intermediate section 36.
Then, in a fourth bonding step, the annular cartridge 30 made of abradable material is bonded to the first internal annular surface 38. During this step, the casing 16 is heated and maintained by means of a system present at least in part inside the casing. In particular, this system comprises the pressurisation system 54 which urges the cartridge 30 into contact with the envelope 16.
Overall, this configuration is satisfactory, but it requires on the one hand the operations to prepare the envelope 16 and on the other hand the operations to position and mount the skids 50, 52, which increases the total cost of manufacturing the casing 14.
The invention remedies this disadvantage by proposing a method for manufacturing a casing 14 for the turbine engine incorporating one or more axial abutment means directly integrated into the envelope 16 during its manufacture.
As previously, and as illustrated in
During this step ET1, as illustrated in
Then, similarly to the method used in the art, in a second step ET2, at least one axial abutment means 70 is arranged projecting from the first internal annular surface 38 of the intermediate section of the envelope 36, at a first end of this intermediate section.
The difference between the method covered by the invention and the method according to the prior art lies in the fact that, according to the invention, the second step ET2 takes place simultaneously with the first step ET1 and in that, during this second step ET2, this axial abutment means 70 is molded with the preform 66 in the mold 64.
The axial abutment means 70 molded with the preform 66 can take different forms. It may initially consist of a skid substantially similar to the skids 52 previously described, which would not be fixed to the envelope but overmolded in the resin with the preform 66 so as to be integrated into the envelope.
However, preferably, as shown in
In its simplest form, the axial abutment means 70 is an annular bead which could be obtained from an annular ring 78 received with the preform 66 in the mold 64. To this end, as shown in
More particularly, an intermediate section 77 of the inner shell comprises the annular groove 76 of axis A formed in the outer annular recess which can be filled with resin, and this section 77 defines the counter-form of the intermediate section 36 of the envelope 16 which is designed to receive the cartridge 30.
The bead 70 is therefore the result of overmolding the ring 78 with the preform 66 with the resin of the envelope 30, and the ring 78 is therefore covered with resin in the groove 76.
However, according to a preferred embodiment of the invention, the groove 76 is only intended to be filled with resin when it is injected into the cavity, to form said bead 70 after the resin has polymerised and demolded. In this case, the groove 76 does not receive a ring before the resin is injected and the axial abutment means 70 is an annular bead of axis A made entirely and solely from the resin of the envelope 30.
In these last two embodiments, as the envelope 16 is oriented vertically for bonding the cartridge 30, it is understood that the final dimensions of the bead 70 are designed to support the weight of the cartridge 30.
By way of example, the bead 70 typically has a radial thickness or dimension of between 10 and 30 mm and/or an axial width or dimension along axis A of between 2 and 3 mm.
It will therefore also be understood in both embodiments that to obtain a bead 70 capable of supporting the weight of the cartridge 30, the dimensions of the groove 76 must be calculated judiciously, and in particular for the latter embodiment in which the volume of the groove must be provided to generate an annular cord of resin of sufficient strength.
Similar to the method according to the prior art, the method comprises a third step ET3 during which the annular cartridge 30 made of abradable material is placed inside the annular envelope 16 in contact with the axial abutment means 70, covering said first annular surface 38.
This configuration is shown in
The annular cartridge can then be bonded in abradable material. The casing 14 is heated, for example to a temperature of between 25 and 300° C., and preferably between 80 and 200° C. This operation can be realized during a cycle lasting between 60 and 500 minutes, and preferably between 180 and 300 minutes.
At the end of the heating operation, the temperature to which the casing 14 is subjected is lowered. Once the casing 14 has cooled completely, the abradable layer 30 is bonded and fixed to the envelope 16.
From an industrial point of view, the invention has the advantage of improving the manufacture (repeatability, robustness) and assembly of the casing and also its three-dimensional control, as the positioning of the annular layer of abradable material is guaranteed by the molded axial abutment means. The invention thus allows to improve the mechanical and aerodynamic performance of the casing, as well as its manufacturing method and overall cycle time.
The invention therefore allows to simplify manufacturing operations for a fan casing 16. It therefore allows to have a dual-flow aircraft turbine engine comprising a fan casing manufactured using the manufacturing method described above, thereby reducing the overall manufacturing costs.
Number | Date | Country | Kind |
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FR2109701 | Sep 2021 | FR | national |
Filing Document | Filing Date | Country | Kind |
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PCT/FR2022/051728 | 9/14/2022 | WO |