MOLD FOR THE MANUFACTURE OF AN RING COVER

Abstract

The invention relates to a mold (15) for manufacturing an annular housing for an aircraft turbomachine, the housing comprising a composite material including a polymer matrix and an annular fibrous preform embedded in the matrix, the mold (15) comprising: - a mandrel (16) extending about a principal axis (Y), - an annular outer wall (17) arranged coaxially around the mandrel (16), - an annular cavity defined between the mandrel (16) and the outer wall (17) and intended to receive the fibrous preform, characterized in that the mold (15) further comprises at least one membrane (20) located in the annular cavity (19) and fixed to the outer wall (17), the fibrous preform being intended to be arranged between the membrane (20) and the mandrel (16). Illustration figure: 4

Description

Title of the invention: MOULD FOR THE MANUFACTURE OF AN ANNULAR CASING Technical field of the invention

[0001] The invention relates to the field of molds for the manufacture of an annular casing comprising a composite material.

[0002] The invention relates in particular to the field of manufacturing annular casings for aircraft turbomachines, such as fan casings. Technical background

[0003] An aircraft turbomachine generally extends along and around a longitudinal axis. It comprises a gas generator which typically comprises from upstream to downstream, in the direction of gas flow in the turbomachine, a low pressure compressor, a high pressure compressor, a gas combustion chamber, a high pressure turbine and a low pressure turbine.

[0004] The rotor of the low pressure compressor is typically connected to the rotor of the low pressure turbine via a low pressure shaft. The rotor of the high pressure compressor is connected to the rotor of the high pressure turbine via a high pressure shaft.

[0005] The turbomachine further comprises a fan which is located upstream of the gas generator. The fan comprises a rotor comprising a disc centered on the longitudinal axis and which is rotated about the longitudinal axis by a fan shaft. The fan further comprises blades extending radially from the disc.

[0006] The turbomachine further comprises annular casings generally arranged around the rotating elements of the turbomachine ensuring the retention, for example, of the rotor blades. Among these casings, the fan casing is known, for example, which is annular and centered on the longitudinal axis of the turbomachine. The fan casing is typically arranged around the rotor of the fan and has the main function of retaining the fan blades.

[0007] In order to reduce the overall mass of the turbomachine, it has been proposed to make the casings of the turbomachine, in particular the fan casing, from a composite material. The composite material typically comprises a polymer matrix and fibers embedded in the polymer matrix. The fibers are organized in the form of an annular fiber preform. They are, for example, chosen from carbon, aramid or glass fibers.

[0008] Such a composite material fan casing is typically made by Resin transfer molding, also known by the acronym RTM for "Resin Transfer Molding". In the context of the manufacture, for example, of a fan casing, made of composite material, a step of arranging an annular fiber preform in a mold is carried out and then a polymer resin is injected into the mold. A resin polymerization step is then carried out to form the polymer matrix of the composite material of the fan casing.

[0009] The mold typically comprises an annular mandrel and an annular outer wall arranged coaxially around the mandrel. The mandrel and the outer wall of the mold define between them an annular cavity in which the fiber preform is arranged. The mold further comprises a port for injecting the resin into the annular cavity.

[0010] The mandrel conditions the internal profile of the fan casing while the external wall conditions the external profile of the casing. This external profile of the fan casing can evolve within the framework, for example, of redesign phases or mass optimization studies of the fan casing. Thus, each modification of the external profile of the fan casing involves the machining of a new external wall of the mold corresponding to this new external profile.

[0011] However, the lead time for supplying the external wall of the mold can be up to nine months, thus involving particularly long manufacturing times for new casings. The design and manufacture of new external mold walls also considerably increases the manufacturing costs of the fan casing.

[0012] Therefore, there is a need to provide a mold for manufacturing annular casings made of composite material for an aircraft turbomachine, the external profiles of which can vary, which make it possible to reduce manufacturing times and costs. Summary of the invention

[0013] To this end, the invention proposes a mold for manufacturing an annular casing of an aircraft turbomachine, the casing comprising a composite material comprising a polymer matrix and an annular fiber preform embedded in the matrix, the mold comprising:

[0014] - a mandrel extending around a main axis,

[0015] - an annular external wall arranged coaxially around the mandrel,

[0016] - an annular cavity defined between the mandrel and the external wall and intended to receive the fiber preform.

[0017] The mold is remarkable in that it further comprises at least one membrane located in the annular cavity and fixed to the external wall, the fiber preform being intended to be arranged between the membrane and the mandrel.

[0018] The mold membrane allows the dimensions of the annular cavity to be adjusted according to the external profile of the desired casing. It is thus possible to manufacture a plurality of casings that differ in their external profile, with a mold having a single external wall. Only the mold membrane can be modified or even replaced depending on the desired external profile of the casing.

[0019] Manufacturing times are therefore reduced since, thanks to the mold of the invention, the time required to supply the external wall of the mold corresponding to the desired casing is eliminated. Manufacturing costs are therefore also considerably reduced.

[0020] The invention may comprise one or more of the following features, taken in isolation from one another or in combination with one another:

[0021] — the membrane is fixed to the external wall in a removable manner;

[0022] - the membrane comprises a polymer material or a composite material comprising a polymer matrix and reinforcing fibers,

[0023] - the polymer material comprises a silicone,

[0024] - the membrane is fixed to the external wall by chemical bonding, for example by gluing or by mechanical connection, for example by bolting,

[0025] - the membrane has a constant or variable thickness in one direction parallel to the main axis and / or a circumferential direction,

[0026] - the outer wall comprises a metallic material,

[0027] - the external wall is sectorized and comprises a plurality of angular sectors distributed around the main axis, the membrane being fixed to at least one of the angular sectors,

[0028] - the membrane is sectorized and comprises a plurality of circular segments, each angular sector being fixed to one of the circular segments,

[0029] - the number of angular sectors is equal to the number of circular segments and extend along the same angular extent, each angular sector covering a corresponding circular segment.

[0030] The invention also relates to a method of manufacturing an annular casing for an aircraft turbomachine, the casing comprising a polymer matrix and an annular fibrous preform embedded in the matrix, the manufacturing method comprising the following steps:

[0031] (a) providing a mandrel extending about a main axis,

[0032] (b) arranging a fibrous preform around the mandrel,

[0033] (c) mounting an outer wall coaxially around the mandrel, the mandrel and the wall external defining an annular cavity in which the fiber preform is located,

[0034] (d) injecting a polymeric material into the annular cavity,

[0035] (e) polymerizing the polymeric material to form the matrix.

[0036] The method is remarkable in that in step (c), a membrane is fixed to the outer wall and is located in the annular cavity, the fibrous preform being arranged between the membrane and mandrel. Brief description of the figures

[0037] Other characteristics and advantages will emerge from the following description of non-limiting embodiments of the invention with reference to the appended drawings in which:

[0038] [Fig-1] [Fig.l] is a perspective view of an example of a turbomachine aircraft according to the invention;

[0039] [Fig.2] [Fig.2] is a perspective view of a fan casing fitted to the turbine bomachine of [Fig.l];

[0040] [Fig.3] [Fig.3] is a longitudinal sectional view of the housing of [Fig.2];

[0041] [Fig.4] [Fig.4] is a perspective view of a mold for the manufacture of a turbomachine casing, such as the fan casing of [Fig.2];

[0042] [Fig.5] [Fig.5] is a longitudinal sectional view of the mold of [Fig.4];

[0043] [Fig.6] [Fig.6] is a block diagram of the manufacturing process of the invention. Detailed description of the invention

[0044] An example of an aircraft turbomachine 1 according to the invention is shown in [Fig. 1]. The turbomachine 1 is for example a dual-flow turbojet.

[0045] The turbomachine 1 extends along a longitudinal axis X. A gas flow F flows in the turbomachine 1.

[0046] For the purposes of the present invention, the terms “upstream” and “downstream” are understood to mean relative to the direction of flow of the gas flow F in the turbomachine 1.

[0047] Furthermore, the terms “longitudinal”, “longitudinally”, “radial”, "radially" means relative to the longitudinal axis X of the turbomachine 1. The terms "external", "internal" mean relatively to the distance from the longitudinal axis X along a radial axis perpendicular to the longitudinal axis X.

[0048] The turbomachine 1 comprises, from upstream to downstream, a fan 2 and a gas generator. The gas generator comprises, from upstream to downstream, a low-pressure compressor 3, a high-pressure compressor 4, at least one combustion chamber 5, a high-pressure turbine 6 and a low-pressure turbine 7. The fan 2 is typically mounted upstream of the low-pressure compressor 3.

[0049] Each compressor 3, 4 comprises a compressor rotor and each turbine 6, 7 comprises a turbine rotor. The compressor and turbine rotors are composed of a plurality of stages each comprising a bladed wheel.

[0050] The compressor rotor of the low pressure compressor 3 is connected to the turbine rotor of the low pressure turbine 7 by a low pressure shaft (not shown). They form a low pressure body.

[0051] The compressor rotor of the high-pressure compressor 4 is connected to the turbine rotor of the high-pressure turbine 6 by a high-pressure shaft (not shown). They form a high-pressure body.

[0052] The low pressure and high pressure shafts are centered on the longitudinal axis X and rotatable about the longitudinal axis X. The high pressure shaft is arranged coaxially around the low pressure shaft.

[0053] The gas flow F passes through the blower 2 and is divided into a primary air flow passing through a primary vein and a secondary air flow passing through a secondary vein surrounding the primary vein. The primary air flow passes through the low pressure 3 and high pressure 4 compressors. The compressed primary air flow then passes through the combustion chamber 5 in which it is mixed with a fuel. The gases resulting from the combustion thus pass through the high pressure 6 and low pressure 7 turbines. The energy of the gases is transformed by the turbine rotor of the low pressure turbine 7 into mechanical energy making it possible to drive the low pressure shaft and consequently the low pressure compressor in rotation.

[0054] The fan 2 comprises a disk 2a centered on the longitudinal axis X and rotatable about the longitudinal axis X. The disk 2a is driven in rotation by a fan shaft. Advantageously, the fan shaft is connected to the low-pressure shaft via a mechanical speed reducer (not shown). The speed reducer allows the fan shaft to be driven at a rotational speed lower than the rotational speed of the low-pressure shaft. This makes it possible to increase the bypass ratio of the turbomachine 1. The fan 2 further comprises blades 2b regularly distributed on the disk 2a and extending radially from the disk 2a.

[0055] The turbomachine 1 further comprises at least one casing. In the present description, a casing is a fixed structure of the turbomachine 1. According to the invention, the casing comprises a composite material. The composite material comprises a matrix and fibers embedded in the matrix. The matrix is ​​polymeric and is chosen from thermoplastic or thermosetting polymers. The thermoplastic polymer is for example a polyamide, a polyethylene, a polypropylene, an epoxy or a polyvinylidene fluoride or a mixture thereof. The fibers are for example carbon, glass or aramid fibers or a mixture thereof. The fibers are organized in the form of a fiber preform. The fiber preform is for example woven.

[0056] The casing may be a fan casing 8 and / or an intermediate casing 9 or any other casing.

[0057] The fan casing 8 is arranged around the blades 2b. The possible intermediate casing 9 is located downstream of the fan casing 8 and surrounds the low compressor pressure 3.

[0058] As best seen in [Fig.2], the fan casing 8 is centered on the longitudinal axis X. It comprises an annular body 10, an upstream annular flange 11 and a downstream annular flange 12 which are located at the axial ends of the annular body 10. The downstream annular flange 12 is for example connected by bolting to the intermediate casing 9.

[0059] As best seen in [Fig. 3], the fan casing 8 has an external profile 13 and an internal profile 14. The external profile 13 may vary from one fan casing to another depending on the specifications of the fan casing 8. For example, the distance d separating the external profile 13 from the internal profile 14 may vary depending on the fan casings 8. This distance d is measured radially.

[0060] The casings 8, 9 made of composite material of the turbomachine 1, in particular the fan casing 8, are manufactured by injection molding, also known by the English acronym RTM for “Resin Transfer Molding”.

[0061] In order to take into account the variability of the external profiles 13 of the fan casing 8 for example, the invention proposes a mold 15 for the manufacture of the fan casing 8.

[0062] The mold 15 is described for the manufacture of the fan casing 8 but can be used for the manufacture of the intermediate casing 9 or any casing of the turbomachine 1.

[0063] With reference to [Fig.4], the mold 15 comprises a mandrel 16 and an external wall 17.

[0064] The mandrel 16 is annular and has a main axis Y.

[0065] In the remainder of the description of the mold 15, the terms “longitudinal”, "longitudinally", "radial", "radially" are understood in relation to the main Y axis. The terms "external", "internal" are understood relatively in relation to the distance from the main Y axis along a radial axis perpendicular to the main Y axis.

[0066] The mandrel 16 comprises a body 16a for depositing the fiber preform of the fan casing 8. The body 16a has, for example, an external surface around which the fiber preform is wound. The fiber preform may be formed from several sheets which are draped over the mandrel. The mandrel 16 further comprises first and second radial walls 16b, 16c located at the axial ends of the body 16a. The first and second radial walls are annular and connected to the body 16a of the mandrel 16. They each have an annular external peripheral edge 16c having, for example, fixing orifices.

[0067] The mandrel 16 is for example metallic. It is advantageously formed from a single piece.

[0068] The outer wall 17 is annular and centered on the main axis Y. It is arranged coaxially around the mandrel 16. The outer wall 17 is for example metallic. It is fixed to the first and second radial walls 16b, 16c. It comprises for example lateral flanges 17c fixed to the outer peripheral edge 16c of the radial walls 16a, 16b of the mandrel 16 by bolting for example. The lateral flanges 17c are fixed radially to the outer peripheral edges 16c. The outer wall 17 further has an outer surface 17a and an inner surface 17b facing the mandrel 16.

[0069] According to a particularly preferred embodiment of the invention, the external wall 17 of the mold 15 is sectorized. It comprises a plurality of angular sectors 18 regularly distributed around the main axis Y. Each angular sector 18 extends around the main axis Y over an angular range of between 30° and 120°, preferably between 30° and 90°, even more preferably between 45° and 60°. Advantageously, the external wall 17 comprises between three and twelve angular sectors 18, preferably between four and twelve angular sectors 18, even more preferably between six and eight angular sectors 18. Only two of the sectors 18 are shown in [Fig. 4]. The number of sectors will of course depend on the dimensions of the mold 15 and consequently on those of the casing to be obtained.

[0070] The mold 15 further comprises an annular cavity 19 defined between the external wall 17 and the mandrel 16. Indeed, the external wall 17 cooperates with the mandrel 16 to delimit the annular cavity 19. The annular cavity 19 thus extends all around the main axis Y. The annular cavity 19 has a radial dimension r of between 1 mm and 50 mm.

[0071] The fiber preform (not shown) is located in the annular cavity 19.

[0072] In a manner not illustrated, the mold 15 further comprises an injection port of a resin in the annular cavity 19.

[0073] The external profile 13 of the fan casing 8 is imposed by the external wall 17 of the mold 15. Thus, for each configuration of the fan casing 8, it is necessary to machine a new external wall 17 to correspond to the corresponding external profile 13. However, the supply times are particularly long, therefore imposing particularly significant manufacturing times and costs for the fan casing 8.

[0074] To overcome these main drawbacks, the mold 15 according to the invention further comprises a membrane 20 arranged in the annular cavity 19 so that the fiber preform is located (radially) between the membrane 20 and the mandrel 16.

[0075] As best seen in [Fig.5], the membrane 20 is fixed to the external wall 17. Advantageously, the membrane 20 is fixed to the external wall 17 in a removable manner.

[0076] According to a first embodiment, the membrane 20 is chemically fixed to the external wall 17. For example, the membrane 20 is glued to the external wall 17, in particular to the internal surface 17b of the external wall 17 using for example a layer of glue or adhesive tape.

[0077] According to a second embodiment, the membrane 20 is mechanically fixed to the external wall. For example, the membrane 20 is connected to the external wall 17 by bolting.

[0078] Advantageously, the membrane 20 comprises a polymer material. The polymer material is preferably chosen from silicones. According to another advantageous example, the membrane 20 comprises a composite material. The composite material comprises a matrix and reinforcing fibers embedded in the matrix. The matrix is ​​for example chosen from fluorinated polymers such as polytetrafluoroethylene (PTFE) and the fibers are for example glass fibers. According to yet another example, the membrane 20 comprises a metallic material.

[0079] The membrane 20 has a thickness e of between 0.1 mm and 10 mm. The thickness e of the membrane 20 may be constant, that is to say it is identical at all points or variable in a direction parallel to the main axis Y and / or a circumferential direction.

[0080] The membrane 20 is advantageously capable of withstanding temperatures greater than or equal to 200°C. This allows the membrane 20 to be used in the molding process which involves temperatures which may be greater than or equal to 200°C.

[0081] According to a preferred embodiment, the membrane 20 has a coefficient of thermal expansion of between 1.10 4 K 1 and 1.106 K 1. This makes it possible to maintain the radial dimension r of the annular cavity 19 throughout the molding process since the thermal expansions of the membrane 20 are low.

[0082] According to a preferred embodiment, the membrane 20 is sectorized. It comprises a plurality of circular segments 21 fixed to the external wall 17, and in particular to each angular sector 18. Each circular segment 21 extends around the main axis Y over an angular range for example between 30° and 120°, preferably between 30° and 90°, even more preferably between 45° and 60°.

[0083] Preferably, the angular extent of the circular segments 21 of the membrane 20 is identical to the angular extent of the angular sectors 18 of the external wall 17.

[0084] Advantageously, the membrane 20 comprises between three and twelve circular segments 21, preferably between four and twelve circular segments 21 and even more preferably between six and eight angular sectors 21.

[0085] Preferably, each circular segment 21 of the membrane 20 covers a corresponding angular sector 18 of the external wall 17. Thus, when mounted end to end around the main axis Y, the membrane 20 covers the internal surface 17b of the external wall 17.

[0086] The membrane 20 makes it possible to adjust the radial dimension r of the annular cavity 19. Thanks to such a membrane 20, it is possible to manufacture fan casings 8 whose external profiles 13 vary greatly with the same external wall 17. Indeed, the membrane 20 makes it possible to reduce the radial dimension r of the annular cavity 19 according to the external profile 13 of the desired fan casing 8. It is no longer necessary to manufacture an external wall 17 of the mold 15 for each fan casing 8 since only the membrane 20 conditioning the external profile 13 can be modified. The manufacturing times and costs of the fan casing 8 are therefore considerably reduced.

[0087] A method of manufacturing the fan casing 8 will now be described with reference to [Fig. 6]. This manufacturing method applies to any casing of the turbomachine 1, such as the intermediate casing 9.

[0088] The manufacturing process comprises the following steps:

[0089] (a) providing the mandrel 16,

[0090] (b) arranging the fiber preform around the mandrel 16,

[0091] (c) mounting the outer wall 17 coaxially around the mandrel 16, the mandrel 16 and the external wall 17 defining the annular cavity 19 in which the fiber preform is located,

[0092] (d) injecting a polymeric material into the annular cavity 19,

[0093] (e) polymerizing the polymeric material to form the matrix.

[0094] In step (c), the external wall 17 is coated with the membrane 20 so that the fiber preform is located between the membrane 20 and the mandrel 16. The radial dimension r of the annular cavity 19 is therefore reduced by the membrane 20.

[0095] In step (d), the polymeric material is for example injected under pressure. It is for example injected at a pressure of between 5 bars and 20 bars, in particular between 5 bars and 15 bars.

[0096] In step (e), the mold 15 is subjected to a temperature between 100°C and 200°C. The mold 15 is for example placed in an oven for the polymerization of the polymeric material.

Claims

Claims

1. Mold (15) for manufacturing an annular casing (8, 9) of an aircraft turbomachine (1), the casing (8, 9) comprising a composite material comprising a polymer matrix and an annular fiber preform embedded in the matrix, the mold (15) comprising: - a mandrel (16) extending around a main axis (Y), - an annular external wall (17) arranged coaxially around the mandrel (16), - an annular cavity (19) defined between the mandrel (16) and the external wall (17) and intended to receive the fiber preform, characterized in that the mold (15) further comprises at least one membrane (20) located in the annular cavity (19) and fixed to the external wall (17), the fiber preform being intended to be arranged between the membrane (20) and the mandrel (16).

2. Mold according to the preceding claim, characterized in that the membrane (20) comprises a polymer material or a composite material comprising a polymer matrix and reinforcing fibers.

3. Mold according to the preceding claim, characterized in that the polymer material comprises a silicone.

4. Mold according to any one of the preceding claims, characterized in that the membrane (20) is fixed to the external wall (17) by chemical bonding, for example by gluing or by mechanical bonding, for example by bolting.

5. Mold according to any one of the preceding claims, characterized in that the membrane (20) has a constant or variable thickness (e) in a direction parallel to the main axis (Y) and / or a circumferential direction.

6. Mold according to any one of the preceding claims, characterized in that the external wall (17) comprises a metallic material.

7. Mold according to any one of the preceding claims, characterized in that the external wall (17) is sectorized and comprises a plurality of angular sectors (18) distributed around the main axis (Y), the membrane (20) being fixed to at least one of the angular sectors (18).

8. Mold according to the preceding claim, characterized in that the membrane (20) is sectorized and comprises a plurality of circumferential segments. culars (21), each angular sector (18) being fixed to one of the circular segments (21).

9. Mold according to the preceding claim, characterized in that the number of angular sectors (18) is equal to the number of circular segments (21) and extend along the same angular extent, each angular sector (18) covering a corresponding circular segment (21).

10. Method for manufacturing an annular casing (8, 9) for an aircraft turbomachine (1), the casing (8, 9) comprising a polymer matrix and an annular fibrous preform embedded in the matrix, the manufacturing method comprising the following steps: (a) providing a mandrel (16) extending around a main axis (Y), (b) arranging a fibrous preform around the mandrel (16), (c) mounting an outer wall (17) coaxially around the mandrel (16), the mandrel (16) and the outer wall (17) defining an annular cavity (19) in which the fiber preform is located, (d) injecting a polymeric material into the annular cavity (19), (e) polymerizing the polymeric material to form the matrix, the method being characterized in that in step (c), a membrane (20) is attached to the outer wall (17) and is located in the annular cavity (19), the fiber preform being arranged between the membrane (20) and the mandrel (16).

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