Tooling for machining an abradable annular layer of a blower housing of an aircraft turbomachine and machining method using such tooling

Abstract

Tooling (20) for machining an abradable annular layer (10b) of a fan housing (3) of an aircraft turbomachine, comprising: - a central centering body (30) configured to be fixed to a fan disk (2) of the turbomachine, - a machining tool (50) connected to the central body (30) and comprising at least one machining means (51) configured to come into contact with the abradable layer, and - a first motor (52) for rotating said machining means (51), characterized in that the central body (30) comprises or carries a copy cam (70) which includes a cam profile (72) that is a function of a desired surface profile for the abradable layer (10b) after machining. Figure for the abstract: Fig. 7

Description

Title of the invention: Machining tool for an abradable annular layer of a blower housing of an aircraft turbomachine and machining method using such a tool Technical field of the invention

[0001] The present invention relates to a tooling for machining an abradable annular layer of a blower housing of an aircraft turbomachine and to a machining method using such a tooling. Technical background

[0002] The technical background includes in particular documents WO-A1-2016 / 2023141 and WO-A 1-2023 / 062302.

[0003] A fan casing assembled on an aircraft turbomachine has as its main function to ensure retention in case of ingestion of debris or loss of fan blade.

[0004] Some of the secondary functions of a blower housing are to ensure mechanical continuity in forces and moments between an air inlet sleeve and an intermediate housing ferrule, to allow the fixing of the vein panels, such as the upstream acoustic ferrule, the cartridge of the abradable layer support and the downstream acoustic panel.

[0005] Other functions of the blower housing are to allow the attachment of equipment and supports, to maintain specifications against fire and leakage and to allow continuity of electrical current for lightning protection.

[0006] For example, on a turbomachine, eighteen fan blades can be installed opposite the abradable layer. This abradable layer, frequently made of a plain-colored porous material, crumbles during operation to ensure optimal aerodynamic flow through the fan blades that come into contact with the layer.

[0007] When not in operation, it is necessary to ensure a certain amount of play to ensure the mounting of the blower blades in the blower housing.

[0008] In operation, the inertia of the blower disc, which is composed, among other things, of all the blower blades, causes the disc to move apart in order to fill the mounting gap but also to create an optimal aerodynamic flow.

[0009] To create this aerodynamic vein, the blower blades come into contact with the abradable layer and flake it off as needed.

[0010] During operation, it may happen that, as it crumbles, some detachments of abradable porous material separate from the rest of the surface.

[0011] This is not the only source of flaking of the abradable layer because, in operation, it may happen that the blower sucks up foreign bodies, which can damage the abradable surface.

[0012] These missing surfaces or asperities, on the order of a few micrometers, on one face of the layer abradable sequentially opposite the blades must be reconditioned to avoid in particular losses of performance, cosmetic problems or even risks of further degradation in case of non-compliance.

[0013] In order to recondition the abradable annular layer, it is known to disassemble the entire housing on which the abradable layer is located in order to position it in an environment (for example, a workshop) that allows for machining and reconditioning of the abradable layer. Disassembling the housing, transporting it to the workshop, and then reversing the disassembly process is inefficient, costly, and requires the presence of a specialized workshop near the housing.

[0014] Therefore, there is a need to improve the efficiency and repeatability of machining an abradable layer of an aircraft turbomachine fan housing.

[0015] The Applicant has already proposed a machining tool for an abradable annular layer of a blower housing in document FR-A1-3 117 390.

[0016] The invention provides an improvement to this type of tooling and in particular improves the quality of machining. Summary of the invention

[0017] The invention provides for this purpose a tooling for machining an abradable annular layer of a fan housing of an aircraft turbomachine, this tooling being configured to be at least partially housed in said housing and comprising:

[0018] - a central centering body configured to be attached to a blower disc of the turbomachine, so as to be mobile in rotation around an axis of rotation of the blower disk,

[0019] - a machining tool connected to the central body and comprising at least one means machining configured to come into contact with the abradable layer, and

[0020] - a first rotating drive motor for said machining means,

[0021] characterized in that the central body comprises or carries a copy cam which includes a cam profile which is a function of a desired surface profile for the abradable layer after machining, the machining tool being movable relative to the copy cam and being configured to follow the cam profile so that the machining means machines the abradable layer according to the cam profile.

[0022] The tooling, thanks in particular to its central body, can thus be positioned directly inside the blower housing regardless of the housing's orientation. The tooling according to the invention allows for precise machining of the abradable layer thanks to the copy cam, which is selected based on its cam profile. The abradable layer will be machined according to this cam profile, which significantly improves the machining quality and, in particular, the dimensional and geometric conformity of the abradable layer after machining.

[0023] In this application, the term surface profile means the profile (i.e., the general shape) of a surface in cross-section. The surface considered is the internal annular surface of the abradable layer, and the profile of this surface is therefore the general shape of this surface when considering a cross-section of this abradable layer.

[0024] The tooling according to the invention may comprise one or more of the following features, taken individually or in combination with each other: • the machining tool is a ball end mill; • the tooling includes a second drive motor for rotating the machining tool around said axis of rotation; • the motor or motors are brushless electric motors; • The copy cam is mounted in a removable and interchangeable manner on the central body; • the copy cam includes a flat plate in which is formed an elongated through-hole, this hole having a longitudinal edge which defines the desired surface profile, i.e. an axial section shape of an internal annular surface of the abradable layer; • the plate has a general parallelepiped shape; • the flat plate extends in a plane passing through the axis of rotation; • the machining tool includes a follower, such as a roller, which cooperates by sliding or rolling with said longitudinal edge; • the copy cam is clamped onto the central body by fixing brackets and / or clamping screws; • said machining means is housed in a protective and dust and chip containment hood, this hood being carried by the tool; • the hood is connected by a hose to a pump for sucking up chips and dust; • the tooling further includes a measuring tool connected to the central body and comprising at least one probe configured to bear against said layer, this measuring tool being for example diametrically opposite to the machining tool with respect to said axis of rotation; • the central body is equipped with balancing masses that can be adjusted in position to limit the effort required to rotate the central body around the axis of rotation; • The tooling also includes formwork risers intended to be mounted on either side of the abradable layer and to be tightened axially against the abradable layer.

[0025] The invention also relates to a method for machining an abradable annular layer of a fan casing of an aircraft turbomachine, using tooling according to one of the preceding claims, comprising the steps of:

[0026] a) determine the desired surface profile for the abradable layer after machining,

[0027] b) select a copy cam having a cam profile that corresponds to this surface profile, and mount it removably on the central body, and

[0028] c) machine the abradable layer according to the cam profile. Brief description of the figures

[0029] Other features and advantages of the invention will become apparent upon reading the detailed description that follows, for an understanding of which reference should be made to the accompanying drawings in which:

[0030] [Fig-1] [Fig.1] is a schematic representation of an axial cross-sectional view of a aircraft turbomachine fan,

[0031] [Fig.2] [Fig.2] is a schematic representation of a perspective view of a blower housing

[0032] [Fig.3] [Fig.3] is a schematic representation of a side view of a crankcase blower and machining tooling according to the invention,

[0033] [Fig.4] [Fig.4] is a schematic representation of an axial cross-sectional view of a machining tooling according to the invention inserted into a part of a blower disc,

[0034] [Fig. 5] [Fig. 5] is a schematic representation of a perspective view of a central body of the machining tooling according to the invention,

[0035] [Fig.6] [Fig.6] is a schematic representation of an axial cross-sectional view of tooling risers according to the invention, and

[0036] [Fig.7] [Fig.7] is a schematic representation of a perspective view of a machining tool and a copy cam for the machining tooling according to the invention,

[0037] [Fig.8] [Fig.8] is a schematic representation of another perspective view of the machining tool and the copying cam of the machining tooling according to the invention,

[0038] [Fig.9] [Fig.9] is a schematic representation of another perspective view of the copy cam of the machining tooling according to the invention,

[0039] [Fig. 10] [Fig. 10] is a schematic representation of a perspective and cross-sectional view of the copy cam of the machining tooling according to the invention,

[0040] [Fig. 11] [Fig. 11] is a schematic representation of another perspective and cross-sectional view of a part of the machining tooling according to the invention, and

[0041] [Fig. 12] [Fig. 12] is a schematic perspective representation of the masses of the machining tooling according to the invention of the tooling copying cam. Detailed description of the invention

[0042] Fig. 1 partially represents a fan of an aircraft turbomachine.

[0043] In a conventional manner, a turbomachine comprises, from upstream to downstream, i.e. in the direction of gas flow, a blower, one or more compressors, a combustion chamber, one or more turbines, and a nozzle for ejecting the combustion gases exiting the turbine(s).

[0044] The blower 1 includes a bladed disc 2 which is surrounded by a blower housing 3, also called a retention housing because of its function of retaining the blades in case of breakage of the latter, or in case of entry of debris into the blower.

[0045] As can be seen in [Fig.2], the blower housing 3 has a general cylindrical shape with axis of revolution A.

[0046] It includes an annular mounting flange 3' at each of its axial ends. These flanges 3' are used to fix the housing 3 to annular walls of the turbomachine nacelle or to the shell of an intermediate housing downstream.

[0047] As shown in this [Fig.2], a layer of abradable material 10b is present inside the blower housing 3, being of revolution in the blower housing 3.

[0048] The blower housing 3 therefore extends around the blower blade disc 2. It therefore comprises an internal cylindrical surface which is provided with an annular layer 10b of abradable material.

[0049] The annular layer 10b of abradable material, hereinafter referred to as the abradable layer 10b, extends around and at a short radial distance from one 2a of the blades, sequentially during the rotation of the bladed disk 2. The blades 2a can, during operation, successively rub against the abradable layer 10b and wear it down by friction.

[0050] This allows the radial clearances between the blades 2a and the fan housing 3 that surrounds it to be optimized, and therefore to limit gas leaks at the radially external tips or ends of the blades, and thus to optimize the performance of the turbomachine.

[0051] The abradable layer 10b can be supported by a solid support cartridge 4 or one having a honeycomb structure. This cartridge 4 is generally riveted or screwed onto the blower housing 3.

[0052] A machining tool 20 according to the invention is shown in [Fig. 3] (outside the housing 3) and in [Fig. 4] (inside the housing 3). Such a tool 20 is configured to machine the abradable layer 10b of the blower housing 3 1, in particular for the purpose of reconditioning this abradable layer 10b.

[0053] Tooling 20 includes for this purpose:

[0054] - a central body 30 for centering, or even fixing, on the disc 2 of turbomachine blower, this central body 30 being intended to be mobile in rotation around the axis A of rotation of the blower disk 2,

[0055] - a machining tool 50 connected to the central body 30 and comprising at least one means machining, such as a rotary end mill 51, configured to come into contact with the abradable layer 10b, and

[0056] - a first motor 52 for rotating the milling cutter 51.

[0057] The tooling 20 may further include a measuring tool 40 connected to the central body 30 and comprising at least one probe 41 configured to bear against the abradable layer 10b, this measuring tool being mobile in rotation around the axis A of the central body 30.

[0058] The tooling 20 may further include a second motor 32 for rotating at least the measuring tools 40 and machining tools 50 around the axis A. Alternatively, this rotation could be carried out manually by an operator around the axis A.

[0059] The machining tools 50 and measuring tools 40, as well as the central body 30, are for example connected to each other by a shaft 90. The shaft extends radially by a dimension substantially smaller than that of an inner diameter of the housing 3 in order to allow the axial insertion of the tooling 20 into the housing 3. The machining tools 50 and measuring tools 40 are in particular substantially diametrically opposite with respect to the axis A.

[0060] The tooling 20 can be brought inside the housing 3 by means of a rolling trolley 60, such as that described in document WO-A1-2023 / 062302, for example. The tooling 20 can have a mass of between 100 and 150 kg.

[0061] Once the tooling 20 is centered with respect to the housing 3, it is inserted along axis A into the housing 3. Once the tooling 20 is inserted inside the housing 3, it is fixed to the blower disc 2 by means of a fixing means 31 which includes the central body 30.

[0062] The tooling 20 further includes movement means 58 for moving the machining tool 50 in translation relative to the shaft 90, i.e., radially. These movement means 58 thus allow the cutter 51 to be positioned in contact with the abradable layer in order to adjust the depth of cut and therefore perform the machining.

[0063] At least one of the first 52 and second 32 motors is electric and preferably brushless to reduce noise during operation and improve operator comfort during machining.

[0064] Each of the first 52 and second 32 motors can have a separate control. Consequently, they can rotate at two distinct speeds. It is then possible to perform a complete rotation of the measuring tool 40 and the machining tool 50 with the probe in contact with the abradable layer to measure its thickness without the cutter 51 being rotated.

[0065] The milling cutter 51 can be housed in a protective and dust-containing hood 53, this hood 53 being carried by the machining tool 50.

[0066] The hood 53 is connected here by a pipe 54 to a chip and dust extraction pump (not shown). The vacuum cleaner thus prevents any dust from being inhaled by the operators. The hood 53 is, for example, transparent to allow visualization of the cutter 51 and the abradable layer 10b during machining.

[0067] Figures 5 and following show different parts of a more concrete embodiment of the tooling 20 according to the invention.

[0068] Fig. 5 shows the central body 30 of this tool, which has a general annular shape and which is here carried by the aforementioned carriage 60.

[0069] Fig. 6 shows formwork risers 62, 64 intended to be mounted on either side of the abradable layer 10b and to be tightened axially against the abradable layer 10b.

[0070] These risers 62, 64 are used to recondition the abradable layer 10b after machining. The risers 62, 64 allow the creation of a mold for applying the new abradable material.

[0071] A straight spatula 66 is guided in or on the risers 62, 64 to apply a new abradable in controlled overthickness.

[0072] Figures 7 to 9 show that the central body 30 includes or carries a copy cam 70 which includes a cam profile 72 which is a function of a desired surface profile for the abradable layer 10b after machining.

[0073] The machining tool 50 is movable relative to the copy cam 70 and is configured to follow the cam profile 72 so that the milling cutter 51 machines the abradable layer 10b according to the cam profile 72.

[0074] The copy cam 70 is preferably removably mounted on the central body 30 so that the copy cam 70 can be selected according to its cam profile 72 and the cam profile 72 thus adapted to the blower housing 3 to be machined. The abradable layers 10b of the blower housings of several engines or references of the same engine may have different surface profiles. The number of copy cams 70 available is preferably equal to the number of surface profiles different from these blower housings 3. It is therefore understood that an operator must select the copy cam 70 having the desired surface profile for the abradable layer 10b, and mount this copy cam on the tooling 20.

[0075] The copy cam 70 can be clamped onto the central body 30 by fixing brackets 74 and / or clamping screws 76.

[0076] In the example shown, the copy cam 70 comprises a flat plate 80 in which an elongated through-hole 82 is formed. The hole 82 has a longitudinal edge 84 which defines the desired surface profile, that is to say, an axial cross-sectional shape of an internal annular surface of the abradable layer 10b.

[0077] Plate 80, for example, has a general parallelepiped shape.

[0078] The plate 80 preferably extends in a plane passing through the axis of rotation A.

[0079] The machining tool 50 may include a follower 91, such as a roller, which cooperates by sliding or rolling with the longitudinal edge 84 of the light 82.

[0080] Fig. 11 shows a micrometric adjustment system 92 for adjusting machining depths, and a positioning system 93 using conical surfaces and retaining screws.

[0081] Fig. 12 shows that the central body 30 can be equipped with balancing masses 94 adjustable in position so as to limit the effort required to drive the central body 30 in rotation around the axis of rotation A.

[0082] When not in use, the tooling 20 can be stored in a case which can also be used for its transport.

[0083] The present invention also relates to a method for machining an abradable annular layer 10b of a fan housing 3 of an aircraft turbomachine, using the tooling 20 described above, comprising the steps of:

[0084] a) determine the desired surface profile for the abradable layer 10b after machining,

[0085] b) select a copy cam 70 having a cam profile that corresponds to this surface profile, and mount it removably on the central body, and

[0086] c) machine the abradable layer 10b according to the cam profile.

[0087] During machining, the casing vein can be protected by flanges or similar, such as those described in document WO-A1-2023 / 062302 for example.

[0088] The invention offers several advantages, including:

[0089] - improved ergonomics for operators, particularly with regard to nuisances sound,

[0090] - a dimensional conformity of the abradable layer 41b, which can be detected live during machining by probe 4 701,

[0091] - a faster reconditioning time in order to reduce as much as possible the engine downtime,

[0092] - increased repeatability of reconditioning,

[0093] - a high level of safety for operators,

[0094] - adaptability of the tooling to different surface profile configurations, thanks to the interchangeability of the copy cam, etc.

Claims

Claims

1. Tool (20) for machining an abradable annular layer (10b) of a fan casing (3) of an aircraft turbomachine, this tool (20) being configured to be at least partly housed in said casing (3) and comprising: - a central centering body (30) configured to be fixed to a fan disc (2) of the turbomachine, so as to be movable in rotation about an axis of rotation (A) of the fan disc (2), - a machining tool (50) connected to the central body (30) and comprising at least one machining means (51) configured to come into contact with the abradable layer, and - a first motor (52) for driving in rotation said machining means (51), characterized in that the central body (30) comprises or carries a copy cam (70) which comprises a cam profile (72) which is a function of a desired surface profile for the abradable layer (10b) after machining,the machining tool (50) being movable relative to the copy cam (70) and being configured to follow the cam profile (72) so that the machining means (51) machines the abradable layer (10b) according to the cam profile (72), and in that the copy cam (70) comprises a flat plate (80) in which a through-hole (82) of elongated shape is formed, this hole (82) having a longitudinal edge (84) which defines the desired surface profile, the machining tool (51) comprising a follower (91) which is engaged in the hole (82) and which cooperates by sliding or rolling with said longitudinal edge (84).,

2. Tooling (20) according to claim 1, wherein the machining means is a ball end mill (51).

3. Tooling (20) according to claim 1 or 2, in which it comprises a second motor (32) for driving the machining tool (50) in rotation around said axis of rotation (A).

4. Tooling (20) according to one of the preceding claims, in which the or each motor (32, 52) is an electric motor of the brushless type.

5. Tooling (20) according to one of the preceding claims, in which the copying cam (70) is removably and interchangeably mounted on the central body (30).

6. Tooling (20) according to one of the preceding claims, in which the plate (80) has a generally parallelepiped shape.

7. Tooling (20) according to one of the preceding claims, in which the flat plate (80) extends in a plane passing through the axis of rotation.

8. Tooling (20) according to one of the preceding claims, in which the follower (91) is a roller.

9. Tool (20) according to one of claims 5 to 8, in which the copy cam (70) is clamped on the central body (30) by fixing brackets (74) and / or clamping screws (76).

10. Tool (20) according to one of the preceding claims, in which said machining means (51) is housed in a cover (53) for protecting and confining chips and dust, this cover (53) being carried by the machining tool (50).

11. Tool (20) according to claim 10, in which the cover (53) is connected by a pipe (54) to a chip and dust suction pump.

12. Tooling (20) according to one of the preceding claims, in which it further comprises a measuring tool (40) connected to the central body (30) and comprising at least one probe (41) configured to bear on said layer (10b), this measuring tool (40) being for example diametrically opposite relative to the machining tool with respect to said axis of rotation (A).

13. Tool (20) according to one of the preceding claims, in which the central body (30) is equipped with balancing masses (94) adjustable in position so as to limit the force necessary for driving the central body in rotation around the axis of rotation (A).

14. Tooling (20) according to one of the preceding claims, in which it further comprises formwork extensions (62, 64) intended to be mounted on either side of the abradable layer (10b) and to be clamped axially against the abradable layer (10b).

15. Method of machining an abradable annular layer (10b) of a casing (3) of a fan (1) of an aircraft turbomachine, by means of a tool (20) according to one of the preceding claims, comprising the steps consisting of: a) determining the desired surface profile for the abradable layer (10b) after machining, b) selecting a copy cam (70) having a cam profile (72) which corresponds to this surface profile, and removably mounting it on the central body (30), and c) machining the abradable layer (10b) according to the cam profile (72).

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