Method for manufacturing an aircraft turbine engine casing

Abstract

The invention relates to a method (400) for manufacturing a casing (102) of a turbine engine (10), the casing (102) comprising a skin (102a) having an annular shape about an axis (A) and comprising tubular vents (106) which project on an outer annular face (102e) of the skin (102a) and are oriented radially with respect to the axis, the method (400) comprising the following steps: - preparing (402) an annular skin made of a thermoplastic-based material, the skin comprising openings (102h) passing through in the radial direction, - preparing (404) tubular vents made of thermoplastic-based material, - attaching (406) the tubular vents to the skin, with the attachment step (406) comprising, for each vent (106): • welding (406a) a support (200) to the skin at one of the openings, and • welding (406b) a sleeve (202) to the support and / or the skin, with the assembly formed by the support and the sleeve forming the vent.

Description

Description TITLE: METHOD FOR MANUFACTURING AN AIRCRAFT TURBOMACHINE HOUSING Technical field of the invention

[0001] The present invention relates to a method for manufacturing a turbomachine casing, in particular for an aircraft, a turbomachine casing obtained via said method and a stage and a turbomachine comprising said casing. Technological background

[0002] The prior art document US-A-5308 226 is known.

[0003] In a turbomachine, variable-pitch stator vane stages are mounted between the rotating wheels of a compressor. More specifically, within a low-pressure or high-pressure compressor of a turbomachine, the stator vanes have variable pitch (also called VSV, an acronym for "Variable Stator Vane") so as to adapt the angle of incidence on the compressor blades according to the rotational speed of the turbomachine.

[0004] These variable-pitch stator (rectifier) ​​blades are carried by an external annular housing and are adjustable in position around their axes of rotation, or pitch axes, to optimize the flow of gases in the turbomachine engine.

[0005] These blades can be arranged in an annular row in one or more stages, usually of a compressor, of the turbomachine.

[0006] Figure 1 illustrates an example of a stage 100 of variable pitch stator blades 108a of a turbomachine 10. The stage 100 comprises at least one annular row of variable pitch blades 108a, a casing 102 of annular shape around a longitudinal axis A and tubular chimneys 106 mounted on an external face of a skin of the annular casing 102.

[0007] Each blade 108a comprises a blade 110 which is connected at its outer radial end by a plate with a substantially circular contour to a radial cylindrical pivot 116 that defines the alignment axis of the blade 108a and is guided in rotation within a corresponding orifice in the outer housing. The orifice in which the radial cylindrical pivot is guided in rotation is machined in the chimney 106.

[0008] The radially inner end of the blade 110 of each blade 108a generally includes a second cylindrical pivot extending along the axis of blade alignment and guided rotation in an orifice of an internal compressor casing.

[0009] The radially external end of the radial cylindrical pivot 116 of each blade is connected by a lever 124 (or a connecting rod) to a control ring 120 which is rotated around the outer housing 102 by means of a hydraulic cylinder or similar actuator. The rotation of the control ring 120 is transmitted by the levers 124 to the cylindrical pivots 116 of the blades 108a and causes them to rotate around their axes.

[0010] Stage 100 may also include an annular row of movable blades 108b carried by a rotor (not shown) of the turbomachine 10 and an abradable layer on a radially internal face of the casing and opposite a radially external end of a movable blade 108b.

[0011] The mounting or assembly of the chimneys 106 on the skin of the casing 102 can however prove complex when the casing 102 and the chimneys 106 are made, for example, of thermoplastic composite material.

[0012] For example, a housing with directly integrated chimneys can be manufactured. However, this method is complex due to the relatively intricate and compact geometry of the areas where the chimneys are located. Indeed, the distance between the pivots of two successive variable-pitch blades is on the order of 20 to 30 mm.

[0013] The chimneys can also be bonded to the casing. However, this type of assembly may have a short lifespan due to aging and the potentially high temperatures in this environment.

[0014] As for assembly by clamping using rivets or screws, it is not feasible due to the size of the parts, which are generally too small, and the limited space.

[0015] It may therefore be desirable to provide a method of assembling the casing, and in particular of mounting the chimneys on the casing, which makes it possible to overcome at least some of the aforementioned problems and constraints. Summary of the invention

[0016] A manufacturing process for a turbomachine housing is therefore proposed; this housing comprises an annular skin around an axis and includes tubular chimneys projecting from an external annular face of the skin and oriented radially with respect to the axis, the process comprising the following steps: preparation of an annular skin of thermoplastic-based material, this skin having radially through holes; preparation of tubular chimneys of thermoplastic-based material; attachment of the tubular chimneys to the skin, these chimneys being attached at the level of the holes in the skin, the attachment step comprising, for each chimney: • the welding of a support onto the skin, at the level of one of the orifices, and, • the welding of a socket onto the support and / or the skin, the assembly formed by the support and the socket forming said chimney.

[0017] Thus, thanks to the invention, it is possible to assemble a housing and chimneys made of thermoplastic material by increasing the interface surfaces between the chimneys and the housing skin through welding. This solution ensures a durable, long-lasting bond.

[0018] The invention also allows for a reduction in mass through the use of thermoplastic composite material for the preparation of the casing skin and the preparation of the chimneys.

[0019] The invention may further include one or more of the following optional features, in any technically feasible combination: the tubular portion is frustoconical; the sleeve has a shape complementary to the support; the sleeve includes a frustoconical orifice; the skin is radially interposed between the collar and the sleeve; the skin is welded respectively to the collar and the sleeve; the sleeve is mounted around the tubular portion; and the support is fixed to the skin by a sonotrode; the support includes a tubular portion which is mounted radially through the corresponding orifice; the support is attached and welded radially to the skin from the inside of the skin; The support comprises an annular collar which is pressed against an inner face of the skin, opposite the outer face, the support being welded to the skin via its collar; the sleeve is attached and fixed from the outside of the skin; the sleeve is mounted around the support and fixed to the support by welding; a resistive film is disposed on at least a part of the faces of the sleeve bearing on the support before its fixing by welding to the support; the skin is intercalated radially between the collar and the sleeve; the skin (102a) is welded respectively to the collar (200b) and to the sleeve; the method further comprises a step of crushing a free end of the support against the sleeve, said free end passing radially through an orifice of the sleeve and emerging above this orifice; the sleeve and / or the support is / are made of thermoplastic composite material preferably fiber-reinforced.

[0020] The invention also relates to a casing for an aircraft turbomachine, this casing comprising: an annular skin about an axis, including an inner annular face and an outer annular face; tubular chimneys projecting from the outer annular face of the skin and oriented radially with respect to the axis, each of these chimneys being formed by a support fixed by welding in a radial orifice of the skin and by a socket fixed by welding to the support and / or to the skin.

[0021] The housing, according to the invention, may further include one or more of the following optional features, in any technically feasible combination: the support comprises: • a tubular portion inside the radial orifice, the tubular portion passing through the orifice in a radial direction; and • a collar fixed to the inner annular face of the skin; the socket includes a resistive film on at least part of its faces in contact with the support.

[0022] The invention also relates to a stage for an aircraft turbomachine, the stage comprising: an annular casing as described above; an annular row of variable-pitch blades, each variable-pitch blade having a blade comprising a cylindrical pivot at its radially external end, this pivot being mounted in a tubular chimney of the casing and defining a blade pitch axis; and a blade pitch control ring, this ring extending around the casing and being connected to the blade pivots.

[0023] The invention also relates to a stage for an aircraft turbomachine comprising a stage as described above. Brief description of the figures

[0024] The invention will be better understood with the aid of the following description, given solely by way of example and made with reference to the accompanying drawings in which: Figure 1 is a schematic cross-sectional view of a variable-pitch stage of an aircraft turbomachine according to the prior art; Figure 2 is a schematic partial view of the stage of Figure 1; Figure 3 is a schematic representation of a stack of an aircraft turbomachine casing according to the invention; Figure 4 is a schematic representation of the manufacturing process of the casing of Figure 3; Figure 5 is a schematic representation of the mounting of the stack support of Figure 3; and Figure 6 is a schematic representation of the mounting of the stack bushing of Figure 3; Figure 7 is a schematic representation of the crushing of a free end of the support against the bushing of Figure 3;Figure 8 is a schematic representation of the chimney in Figure 3 after the free end of the support has been crushed. Detailed description of the invention

[0025] In general, in the description below, the terms "longitudinal" and "axial" refer to the orientation of structural elements extending along the direction of a longitudinal axis. This axis can be considered the axis of rotation of a turbomachine rotor. The term "radial" describes an orientation of structural elements extending in a direction perpendicular to the longitudinal axis. The terms "inside" and "outside," and "internal" and "external," are used in reference to positioning relative to the longitudinal axis. Thus, a structural element extending along the axis has an inner face facing the axis and an outer surface opposite its inner surface. Similarly, the terms "upstream" and "downstream" are defined in relation to the direction of airflow within the turbomachine.

[0026] With reference to Figure 2, a (non-limiting) example of a variable-pitch turbine stage 100 of an aircraft turbomachine 100 in which the invention is implemented will now be described. The turbomachine 10 can be a turbojet or a turboprop.

[0027] Stage 100, which is for example a stage 100 of a high-pressure compressor of the turbomachine 10, includes an annular row of variable-pitch blades 108a, an annular housing 102 having an axis of revolution A, and a control ring 120 for the pitching of the blades 108a.

[0028] Stage 100 may also include an annular row of movable blades 108b carried by a rotor (not shown) of the turbomachine.

[0029] Each variable-pitch blade 108a comprises a blade 110 having a cylindrical pivot 116 at its radially external end. The cylindrical pivot 116 defines a pitch axis C of the variable-pitch blade 108a.

[0030] The angular orientation of the 108a variable-pitch blades can be adjusted to optimize gas flow in the compressor. In particular, the 108a variable-pitch blades can be rotated around their C axes between a closed or near-closed position and an open or fully open position.

[0031] In the closed position, the blades 110 of the vanes are inclined with respect to a longitudinal axis X of the turbomachine 10 and define between them a minimum cross-section for airflow in the duct. The longitudinal axis X of the turbomachine 10 corresponds substantially to the axis A of the annular casing 102. The variable-pitch vanes 108a are brought into this closed position when the turbomachine is at low speed or idle, at which point the airflow into the compressor is at a minimum. In the open position, the blades 110 of the variable-pitch vanes 108a extend substantially parallel to the axis of the turbomachine 10 so that the air passage area between the blades is maximized. The variable-pitch blades 108a are brought into this open position when the turbomachine 10 is at full throttle, at which point the air flow into the compressor has a maximum value.

[0032] The blade 110 and the cylindrical pivot 116 can be connected by a disc or "plate" 118 extending perpendicularly to the pitch axis C, of ​​the variable pitch blade 108a, in a corresponding housing 114 of the annular housing 102. A radially internal surface 112 of the disc 118 can be aligned with an internal wall 102i of the annular housing 102 so as not to oppose the gas flow.

[0033] An external radial end of the cylindrical pivot 116 of each variable pitch blade 108a can be connected to the control ring 120 by a connecting rod 124, the connecting rod 124 being connected to a linking member 122 to the cylindrical pivot 116. This control ring 120 extends around the annular housing 102 in Figure 1.

[0034] The distance between adjacent cylindrical pivots of 108a blades with variable pitch is for example between 20 and 30 mm.

[0035] The housing 102 comprises at least one annular skin 102a about the axis of revolution A, having an inner annular face 102i and an outer annular face 102e, and tubular chimneys 106 projecting from the outer annular face 102e of the skin 102a. The tubular chimneys 106 are oriented radially with respect to the axis A. The cylindrical pivot 116 of each blade 108a can extend inside each tubular chimney 106.

[0036] With reference to Figure 3, each tubular chimney 106 includes a support 200 which is fixed by welding in a radial orifice 102h of the skin 102a and a socket 202 which is also fixed by welding to the support 200 and / or to the skin 102a of the housing 102.

[0037] The support 200 comprises a tubular portion 200a inside the radial orifice 102h, the tubular portion 200a passing through the orifice 102h in a radially outward direction. The tubular portion 200a of the support 200 is preferably frustoconical.

[0038] The support also includes an annular collar 200b fixed to the inner annular face 102i of the skin 102a of the annular housing 102.

[0039] The support also includes a cylindrical passage 200i intended for the passage of the pivot 116 of the variable-pitch blade 108a.

[0040] Preferably, the support is made of thermoplastic material and preferably of a thermoplastic composite material reinforced with short fibers.

[0041] The sleeve 202, which is mounted around the tubular portion 200a of the support 200, has a shape complementary to the support 200 and more specifically to the tubular portion 200a. Thus, in the case where the tubular portion has a frustoconical shape, the sleeve 202 includes a frustoconical orifice 202h in which the tubular portion 200a of the support 200 extends, the wall of the orifice 202h conforming to the frustoconical shape of the tubular portion 202a.

[0042] The sleeve 202 further comprises a resistive film 204 on at least a portion of its faces bearing against the support 200 (or on the tubular portion 202a of the support 200). The sleeve 202 may also comprise a resistive film 204 on at least a portion of its faces bearing against the skin 102a of the housing 102, as illustrated in Figure 3. The resistive film 204 may be in the form of a grid or a single filament.

[0043] With reference to Figure 4, a process 400 for manufacturing a casing 102 for a variable pitch blade stage 100 of an aircraft turbomachine 100 will now be described.

[0044] The process 400 includes the preparation 402 of an annular skin 102a made of a thermoplastic-based material. During this preparation 402, at least orifices 102h are machined in the annular skin 102a. The machined orifices 102h are through-holes in the radial direction.

[0045] Preferably, the annular skin 102a is made of a thermoplastic-based material and preferably of a continuous fiber-reinforced thermoplastic composite material

[0046] The process 400 for manufacturing the crankcase further includes the preparation 404 of tubular chimneys 106. During the preparation 404 of tubular chimneys 106, supports 200 and bushings 202 are machined.

[0047] The machining of each support includes the production of the tubular portion 200a and the flange 200b, the tubular portion 200a being configured to pass in a radially external direction through one of the orifices 102h machined in the annular skin 102a. The support can be made in one block comprising the tubular portion 200a and the flange 200b fixed to one end of the tubular portion 200a or, in two blocks that can be assembled, the first block comprising the tubular portion 200a and the second the flange 200b.

[0048] The machining of each bushing 202 includes at least the creation of an orifice 202h having a shape complementary to that of the tubular portion 200a of the machined support 200. Thus, in the case where the tubular portion has a frustoconical shape, the machined orifice 202h is frustoconical in shape.

[0049] Preferably, the support 200 and the socket 202 are made of a thermoplastic-based material, and more preferably of a thermoplastic composite material reinforced with short fibers. For example, the short fibers are carbon microfibers (micro-fillers) with a concentration of between 20 and 30%, and preferably between 25 and 30%.

[0050] With further reference to Figure 4, following preparations 402 and 404 respectively of the annular skin 102a and the chimneys 106, the tubular chimneys are fixed 406 to the annular skin 102a.

[0051] The fixing 406 of the tubular chimneys 106 includes the welding 406a of each support 200 on the annular skin 102a at one of the orifices 102h of the annular skin 102a.

[0052] During the welding 406a of the support 200, the tubular portion 200a is mounted through the material in a radially outward direction, that is, from the inner face 102i of the skin 102a to the outer face of the skin (moving away from the axis A of the skin 102a of the housing 102), inside the corresponding opening. In this way, the annular flange 200 is pressed against an inner face 102i of the annular skin 102a, opposite the outer face 102e of the skin 102a. The support 200 is then attached and welded to the skin from the inside of the skin, via its flange 200b.

[0053] The support 200 is ultrasonically welded to the skin 102a using a sonotrode 500, as illustrated in Figure 5. The ultrasound is generated by a piezoelectric effect. The sonotrode 500 is applied, in the S500 direction, to the entire surface of the flange 200b opposite the surface in contact with the inner face 102i of the skin 102a. The sonotrode is shaped like a flat disc to ensure contact with the entire flange. Variable shapes 200c, which can be conical, crenellated, or trapezoidal, can be provided on the face of the flange 200b in contact with the inner face 102i of the skin 102a, serving as energy directors. This shape can be obtained by 3D printing or by injection molding. These energy directors can also be brought to the interface via a rough thermoplastic film with similar shapes.

[0054] During the welding 406a of the support 200, a cylindrical metal component 300, for example a steel or aluminum shaft, is inserted into the orifice of A 200i passage of support 200 is provided to support the geometry of the support. To allow the passage of the metal component 300, a hole 500i is provided in the center of the sonotrode.

[0055] A metallic holding tool 302, for example a steel or aluminum counter-mold, is also arranged around the tubular portion 200a (as illustrated in Figure 5) and rests against the outer face 102e of the skin 102a. Advantageously, the holding tool 302 prevents the tubular portion 200a from separating from the support and the skin 102a, the skin also being made of thermoplastic composite material.

[0056] The welding 406a of the support 200, and more precisely of the collar 200b of the support 200, on the skin 102a is on the order of a few seconds, for example between one and four second(s) (including the time of holding under pressure).

[0057] Following the welding 406a of the support 200 on the skin 102a, the socket 202 is welded 406b on the support 200 and / or the skin 102a.

[0058] In this welding step 406b of the bushing 202, the bushing is mounted around the support 200 and more specifically around the tubular portion 200a. The bushing 202 is attached to the support 200, and in particular to its tubular portion 200a, in a radially inward direction (approaching the axis A of the skin 102a of the housing 102). The skin 102a is then radially interposed between the bushing 202 and the flange 200b, as illustrated in Figure 6. Thus, the bushing 202 is attached and fixed from the outside of the skin 102a. A free end 200e of the support 200, and specifically of its tubular portion 200a, opposite the end of the support 200 comprising the collar 200b, passes through the frustoconical orifice 202h of the socket 202 and has a portion opening above this orifice 202h. This portion of the free end 200e has a radial dimension dR (see Figure 7) which can be, for example, on the order of 5 to 10 mm.

[0059] A resistive film 204 is placed, beforehand, on at least part of the faces of the socket 202 resting on the support and / or on the skin 102a before its fixing by welding 406b on the support 200 and / or the skin 102a.

[0060] Applying a vertical force or pressure S700 then allows the interface between the sleeve 202 and the tubular section 200a and / or between the sleeve 202 and the skin 102a to be welded 406b. In the case where a resistive film 204 is also present between the sleeve 202 and the skin 102a, the interfaces between the sleeve 202 and the tubular section 200a and between the sleeve 202 and the skin 102a are welded simultaneously.

[0061] Advantageously, the presence of a resistive film at the interface between the 202 socket and the 200a tubular portion and / or the 102a skin allows for a great deal of simplification. The welding tooling is designed solely to address the dimensional issue of reducing gaps at the interfaces (between the sleeve 202 and the tubular section 200a and / or between the sleeve 202 and the skin 102a) by applying pressure to the parts and without any heat quality requirements, unlike a conduction welding process, for example. The truncated conical shape of the tubular section 200a of the support 200 and the sleeve 202 allows pressure forces to be applied to the inclined plane with a single vertical force.

[0062] Thus, after welding steps 406a and 406b, the skin 102a is welded respectively to the collar 200b and the socket 202. The assembly including the support 200 and the socket 202 then forms the chimney 106.

[0063] With further reference to Figure 4, the manufacturing process 400 may also include, following the fixing 406 of the chimney to the skin 102, a crushing step 408 of the free end 200e of the support 200, which opens above the orifice 202h of the socket 202, against the socket 202.

[0064] In this crushing step 408, a metal plate 800 is first heated and then applied to the portion of the free end 200e of the support 200 that opens above the orifice 202h of the sleeve 202. Pressure is then exerted on the free end 200e, from top to bottom, in the direction S900 as illustrated in Figure 7. The application of the heated plate 800 melts the free end 200e of the support 200, which spreads and solidifies onto the sleeve 202 as illustrated in Figure 8. The crushing 408 is controlled so that the orifice 200i of the tubular portion 200a of the support 200 is not obstructed by a portion of the molten free end 200e.

[0065] The person skilled in the art will understand that the crushing 408 of the free end 200e of the support 200 against the sleeve 202 makes the free end 200e of the support 200 and the sleeve 202 fixed together and thus reinforces the fixing of the sleeve 202 to the support 200. Thus the risk of loss of the sleeve 202 is considerably reduced or prevented.

[0066] In the detailed presentation of the invention given above, the terms used shall not be interpreted as limiting the invention to the embodiments set forth in this description, but shall be interpreted as including all equivalents which can be foreseen by a person skilled in the art by applying their general knowledge to the implementation of the teaching which has just been disclosed to them.

Claims

Demands [1] A method (400) for manufacturing a housing (102) for a turbomachine (10), said housing (102) comprising a skin (102a) of annular shape about an axis (A) and comprising tubular chimneys (106) projecting from an external annular face (102e) of the skin (102a) and oriented radially with respect to the axis (A), the method (400) comprising the following steps: preparation (402) of an annular skin (102a) of thermoplastic-based material, this skin (102a) having radially through holes (102h), preparation (404) of tubular chimneys (106) of thermoplastic-based material, attachment (406) of the tubular chimneys (106) to the skin (102a), these chimneys being attached at the level of the holes (102h) of the skin (102a), the fixing step (406) comprising, for each chimney (106): • the welding (406a) of a support (200) onto the skin (102a), at the level of one of the orifices (102h), and • the welding (406b) of a socket (202) on the support (200) and / or the skin (102a), the assembly formed by the support and the socket forming said chimney (106). [2] Method (400) of manufacturing a housing (102) according to claim 1, in which the support (200) comprises a tubular portion (200a) which is mounted through, in a radial direction, inside the corresponding orifice (102h). [3] Method (400) of manufacturing a housing (102) according to claim 1 or 2, wherein the support (200) is attached and welded to the skin (102a) radially from the inside of the skin (102a). [4] Method (400) of manufacturing a housing (102) according to any one of claims 1 to 3, wherein the support (200) comprises an annular collar (200b) which is pressed against an inner face (102i) of the skin (102a), opposite the outer face (102e), the support (200) being welded to the skin (102a) via its collar (200b). [5] Method (400) of manufacturing a housing (102) according to any one of claims 1 to 4, wherein the bushing (202) is attached and fixed from outside the skin (102a). [6] Method (400) of manufacturing a housing (102) according to any one of claims 1 to 5, wherein the bushing (202) is mounted around the support (200) and fixed to the support (200) by welding. [7] Method (400) of manufacturing a housing (102) according to claim 6, in which a resistive film (204) is disposed on at least a part of the faces of the sleeve (202) bearing on the support (200) before its fixing by welding on the support (200). [8] Method of manufacturing a housing (102) according to any one of claims 4 to 7, wherein the skin (102a) is welded respectively to the collar (200b) and to the bushing (202). [9] Method of manufacturing a housing (102) according to any one of claims 1 to 8, further comprising a step of crushing (408) a free end (200e) of the support (200) against the sleeve (202), said free end (200e) radially passing through an orifice (202h) of the sleeve (202) and emerging above this orifice (202h). [10] Method (400) of manufacturing a housing (102) according to any one of claims 1 to 9, wherein the bushing (202) and / or the support (200) is / are made of thermoplastic composite material preferably fiber-reinforced. [11] Annular housing (102) for an aircraft turbomachine (10), this housing (102) comprising: a skin (102a) of annular shape about an axis (A), comprising an inner annular face (102i) and an outer annular face (102e), tubular chimneys (106) projecting on the outer annular face (102e) of the skin (102a) and oriented radially with respect to the axis (A), each of these chimneys (106) being formed by a thermoplastic support (200) fixed by welding in a radial orifice (102h) of the skin (102a) and by a thermoplastic bushing (202) fixed by welding to the support (200) and / or to the skin (102a). [12] Annular housing (102) for an aircraft turbomachine (10), according to the preceding claim, in which the support (200) comprises: a tubular portion (200a) inside the radial orifice (102h), the tubular portion (200a) passing through the orifice (102h) in a radial direction; and a collar (200b) fixed on the inner annular face (102i) of the skin (102a). [13] Annular housing (102) for an aircraft turbomachine (10), according to any one of claims 11 and 12, wherein the sleeve (202) comprises a resistive film (204) on at least a portion of its faces bearing on the support (200). [14] Stage (100) for an aircraft turbomachine (10), comprising at least: - an annular casing (102) according to any one of claims 11 to 13; an annular row of variable-pitch blades (108a), each variable-pitch blade (108a) having a blade (110) comprising a cylindrical pivot (116) at its radially external end, this pivot (116) being mounted in a tubular chimney (106) of the casing (102) and defining a pitch axis (C) of the blade (108a); and a blade pitch control ring (120), this ring extending around the casing and being connected to the blade pivots. [15] Aircraft turbomachine (10) comprising at least one stage (100) according to the preceding claim.

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