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: MOLD FOR THE MANUFACTURE OF AN ANNULAL COVER Technical field of the invention

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

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

[0003] An aircraft turbomachine generally extends along and around a longitudinal axis. It comprises a gas generator which typically includes, 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, on the other hand, is connected to the rotor of the high-pressure turbine via a high-pressure shaft.

[0005] The turbomachine further comprises a fan located upstream of the gas generator. The fan comprises a rotor including a disk centered on the longitudinal axis and driven in rotation about the longitudinal axis by a fan shaft. The fan further comprises blades extending radially from the disk.

[0006] The turbomachine further comprises annular housings generally arranged around the rotating elements of the turbomachine, ensuring the retention, for example, of the rotor blades. Among these housings, the fan housing, which is annular and centered on the longitudinal axis of the turbomachine, is a well-known example. The fan housing is typically arranged around the fan rotor and its main function is to retain the fan blades.

[0007] In order to reduce the overall mass of the turbomachine, it has been proposed to make the turbomachine casings, 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 arranged in the form of an annular fibrous preform. They are, for example, selected from carbon, aramid, or glass fibers.

[0008] Such a blower housing made of composite material is typically made by Resin transfer molding, also known by the acronym RTM, is a manufacturing process used, for example, in the production of a blower housing made of composite material. This process involves first placing an annular fibrous preform in a mold, then injecting a polymer resin into the mold. The resin is then polymerized to form the polymer matrix of the blower housing's composite material.

[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 an annular cavity in which the fibrous preform is arranged. The mold further comprises a resin injection port for the annular cavity.

[0010] The mandrel determines the internal profile of the blower housing, while the external wall determines the external profile of the housing. This external profile of the blower housing can change, for example, during redesign phases or mass optimization studies of the blower housing. Thus, each modification of the external profile of the blower housing requires machining a new external wall of the mold corresponding to this new external profile.

[0011] However, the lead time for supplying the outer wall of the mold can be up to nine months, thus implying particularly long lead times for manufacturing new housings. The design and manufacture of new external mold walls also significantly increase the manufacturing costs of the blower housing.

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

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

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

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

[0016] - an annular cavity defined between the mandrel and the outer wall and intended to receive the fibrous 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 fibrous 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 desired external profile of the housing. It is thus possible to manufacture a plurality of The housings differ in their external profile, with a mold featuring a single outer wall. Only the mold membrane can be modified or even replaced to achieve the desired external profile of the housing.

[0019] Manufacturing times are therefore reduced since the mold of the invention eliminates the lead time for supplying the outer wall of the mold corresponding to the desired housing. Manufacturing costs are consequently also considerably reduced.

[0020] The invention may comprise one or more of the following features, taken individually or in combination with each other:

[0021] — the membrane is attached to the outer 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 outer wall by chemical bonding, for example by gluing or mechanical fastening, for example by bolting

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

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

[0027] - the outer wall is sectorized and comprises a plurality of angular sectors distributed around the main axis, with the membrane 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 for manufacturing an annular housing for an aircraft turbomachine, the housing comprising a polymer matrix and an annular fibrous preform embedded in the matrix, the manufacturing method comprising the following steps:

[0031] (a) provide a chuck extending around a main axis,

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

[0033] (c) mount an external wall coaxially around the chuck, the chuck and the wall external, defining an annular cavity in which the fibrous preform is located,

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

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

[0036] The process 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 features and advantages will become apparent from the following description of non-limiting embodiments of the invention with reference to the accompanying drawings in which:

[0038] [Fig-1] [Fig.1] 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 blower housing equipping the tur bomachine of the [Fig.l];

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

[0041] [Fig.4] [Fig.4] is a perspective view of a mold for manufacturing a turbomachine casing, such as the blower 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 synoptic 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 turbofan engine.

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

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

[0047] Furthermore, the terms "longitudinal", "longitudinally", "radial", "Radially" is understood in relation to the longitudinal axis X of the turbomachine 1. The terms "outside", "inside" are understood in relation 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 stage 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 unit.

[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 are free to rotate 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 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 low-pressure compressor 3 and the high-pressure compressor 4. The compressed primary airflow then passes through the combustion chamber 5 where it is mixed with fuel. The combustion gases thus pass through the high-pressure turbine 6 and the low-pressure turbine 7. The energy of the gases is transformed by the turbine rotor of the low-pressure turbine 7 into mechanical energy, which drives the low-pressure shaft and, consequently, the low-pressure compressor.

[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 increases the bypass ratio of the turbomachine 1. The fan 2 further comprises blades 2b evenly distributed on the disk 2a and extending radially from the disk 2a.

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

[0056] The housing can be a blower housing 8 and / or an intermediate housing 9 or any other housing.

[0057] The blower housing 8 is arranged around the blades 2b. The optional intermediate housing 9 is located downstream of the blower housing 8 and surrounds the low-pressure compressor pressure 3.

[0058] As more clearly seen in [Fig.2], the blower housing 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 housing 9.

[0059] As more clearly seen in [Fig.3], the blower housing 8 has an external profile 13 and an internal profile 14. The external profile 13 can vary from one blower housing to another according to the specifications of the blower housing 8. For example, the distance d separating the external profile 13 from the internal profile 14 can vary depending on the blower housings 8. This distance d is measured radially.

[0060] The housings 8, 9 of composite material of the turbomachine 1, in particular the blower housing 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 blower housing 8 for example, the invention proposes a mold 15 for the manufacture of the blower housing 8.

[0062] The mold 15 is described for the manufacture of the blower housing 8 but can be implemented for the manufacture of the intermediate housing 9 or of any housing of the turbomachine 1.

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

[0064] The chuck 16 is annular and has a principal axis Y.

[0065] In the continuation of the description of mold 15, the terms "longitudinal", "Longitudinally", "radially", "radially" are understood with respect to the principal Y axis. The terms "exterior", "interior" are understood with respect to the distance from the principal Y axis along a radial axis perpendicular to the principal Y axis.

[0066] The mandrel 16 comprises a body 16a for depositing the fibrous preform of the blower housing 8. The body 16a has, for example, an external surface around which the fibrous preform is wound. The fibrous preform may be formed of several layers that 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. Each has an annular external peripheral edge 16c having, for example, attachment holes.

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

[0068] The outer wall 17 is annular and centered on the principal 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 includes, for example, lateral flanges 17c fixed to the outer peripheral edge 16c of the radial walls 16a, 16b of the mandrel 16, for example by bolting. The lateral flanges 17c are fixed radially to the outer peripheral edges 16c. The outer wall 17 further has an external surface 17a and an internal surface 17b facing the mandrel 16.

[0069] According to a particularly preferred embodiment of the invention, the outer wall 17 of the mold 15 is sectorized. It comprises a plurality of angular sectors 18 regularly distributed around the principal axis Y. Each angular sector 18 extends around the principal axis Y over an angular range of between 30° and 120°, preferably between 30° and 90°, and even more preferably between 45° and 60°. Advantageously, the outer wall 17 comprises between three and twelve angular sectors 18, preferably between four and twelve angular sectors 18, and 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 housing to be obtained.

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

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

[0072] Not shown, the mold 15 further includes an injection port of resin in the annular cavity 19.

[0073] The external profile 13 of the blower housing 8 is determined by the external wall 17 of the mold 15. Thus, for each configuration of the blower housing 8, it is necessary to machine a new external wall 17 to match the corresponding external profile 13. However, the supply lead times are particularly long, therefore imposing particularly significant manufacturing times and costs for the blower housing 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 fibrous preform is located (radially) between the membrane 20 and the mandrel 16.

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

[0076] According to a first embodiment, the membrane 20 is chemically fixed to the outer wall 17. For example, the membrane 20 is glued to the outer wall 17, in particular to the inner surface 17b of the outer 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 outer wall. For example, the membrane 20 is connected to the outer 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 fluoropolymers 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 between 0.1 mm and 10 mm. The thickness e of the membrane 20 can be constant, i.e., identical at every point, or variable along a direction parallel to the principal axis Y and / or a circumferential direction.

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

[0081] According to a preferred embodiment, the membrane 20 has a coefficient of thermal expansion 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 outer wall 17, and in particular to each angular sector 18. Each circular segment 21 extends around the principal 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 outer 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 outer wall 17. Thus, when mounted end-to-end around the principal axis Y, the membrane 20 covers the inner surface 17b of the outer wall 17.

[0086] The membrane 20 allows the radial dimension r of the annular cavity 19 to be adjusted. Thanks to such a membrane 20, it is possible to manufacture fan housings 8 with external profiles 13 that vary greatly, using the same external wall 17. Indeed, the membrane 20 allows the radial dimension r of the annular cavity 19 to be reduced according to the desired external profile 13 of the fan housing 8. It is no longer necessary to manufacture an external wall 17 of the mold 15 for each fan housing 8, since only the membrane 20, which determines the external profile 13, can be modified. The manufacturing time and costs of the fan housing 8 are therefore considerably reduced.

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

[0088] The manufacturing process comprises the following steps:

[0089] (a) supply the chuck 16,

[0090] (b) arrange the fibrous preform around the mandrel 16,

[0091] (c) mount 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 fibrous preform is located,

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

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

[0094] In step (c), the outer wall 17 is coated with the membrane 20 so that the fibrous 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 between 5 bar and 20 bar, in particular between 5 bar and 15 bar.

[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

Demands

1. Mold (15) for manufacturing an annular housing (8, 9) for an aircraft turbomachine (1), the housing (8, 9) 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 around a principal axis (Y), - an annular outer wall (17) arranged coaxially around the mandrel (16), - an annular cavity (19) 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).

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 outer 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 principal axis (Y) and / or a circumferential direction.

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

7. Mold according to any one of the preceding claims, characterized in that the outer wall (17) is sectorized and comprises a plurality of angular sectors (18) distributed around the principal 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 circum- segments cular (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 extends along the same angular extent, each angular sector (18) covering a corresponding circular segment (21).

10. A method for manufacturing an annular housing (8, 9) for an aircraft turbomachine (1), the housing (8, 9) comprising a polymer matrix and an annular fibrous preform embedded in the matrix, the manufacturing method comprising the following steps: (a) provide a mandrel (16) extending around a principal axis (Y), (b) arrange a fibrous preform around the mandrel (16), (c) mount 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 fibrous preform is located, (d) injecting a polymeric material into the annular cavity (19), (e) polymerizing the polymeric material to form the matrix, the process being characterized in that in step (c), a membrane (20) is fixed to the outer wall (17) and is located in the annular cavity (19), the fibrous preform being arranged between the membrane (20) and the mandrel (16).

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