FR3117390A1 - TOOLING FOR MACHINING AN ABRADABLE ANNULAR LAYER OF A FAN CASE OF AN AIRCRAFT TURBOMACHINE AND METHOD FOR MACHINING USING SUCH TOOLING - Google Patents

Abstract

The invention relates to a tool (20) for machining an abradable annular layer (10b) of a casing (3) of a fan (1) of an aircraft turbine engine, this tool (20) being configured to be at least partly housed in said casing (3) and comprising a central body (30) for centering and fixing on a fan disc (2) of the turbomachine, a measuring tool (40), a tool (50) d machining, and a first motor (52) for driving the machining tool in rotation. The invention also relates to a method for machining an abradable annular layer (10b) of a casing (3) of a fan (1) of an aircraft turbine engine, by means of such a tool (20). Figure for abstract: Fig. 6

Description

TOOLING FOR MACHINING AN ABRADABLE ANNULAR LAYER OF A FAN CASE OF AN AIRCRAFT TURBOMACHINE AND METHOD FOR MACHINING USING SUCH TOOLING

Technical field of the invention

The present invention relates to tooling for machining an abradable annular layer of a fan casing of an aircraft turbine engine as well as a method of machining using such tooling.

Technical background

The main function of a fan casing assembled on an aircraft turbine engine is to guarantee retention in the event of debris ingestion or fan blade loss.

Some of the secondary functions of a fan casing are to ensure the mechanical continuity in terms of forces and moments between an air inlet sleeve and an intermediate casing shroud, to allow the fixing of vein panels, such as the acoustic shroud upstream, the abradable layer support cartridge and the downstream acoustic panel.

Other functions of the fan casing are to allow attachment of equipment and supports, to meet fire and leak specifications and to allow continuity of electrical current for lightning resistance.

For example, on a turbomachine, a number of eighteen fan blades can be installed facing the abradable layer. This abradable layer, frequently made of porous material of a solid color, crumbles in operation in order to guarantee an optimal aerodynamic vein thanks to the fan blades which come into contact with the layer.

When not in operation, it is necessary to guarantee a certain clearance to ensure the mounting of the fan blades in the fan casing.

In operation, the inertia of the fan disc, which is made up, among other things, of all the fan blades, causes the disc to move apart in order to fill the mounting clearance but also to create an optimal aerodynamic vein.

To create this aerodynamic vein, the fan blades come into contact with the abradable layer and crumbles it as needed.

In operation, it may happen that while crumbling, certain detachments of abradable porous material separate from the rest of the surface.

This is not the only source of crumbling of the abradable layer because, during operation, it can happen that the fan sucks up foreign bodies, which can more or less abnormally damage the abradable surface.

These missing surfaces or asperities, of the order of a few micrometers, on one face of the abradable layer sequentially opposite the blades must be reconditioned to avoid in particular loss of performance, problems of non-quality, cosmetic problems or risks of additional degradation in the event of non-compliance.

In order to recondition the abradable annular layer, it is known to dismantle the casing on which the entire abradable layer is located in order to position it in an environment (for example a workshop) allowing the reconditioning of the abradable zone. Dismantling the crankcase, transporting it to the workshop and then the reverse operations are inefficient, costly and require the presence of a specialized workshop near the crankcase.

Consequently, the invention aims to improve the efficiency of the reconditioning of the abradable zones of an aircraft turbomachine fan casing.

The invention therefore proposes tooling for machining an abradable annular layer of a fan casing of an aircraft turbine engine, this tooling being configured to be at least partly housed in said casing and comprising:

- a central centering body configured to cooperate with a fan disc of the turbomachine,

- a measuring tool connected to the central body and comprising at least one feeler configured to rest on said layer, this measuring tool being able to rotate around an axis common to the central body and to the fan disc,

- a machining tool connected to the central body and comprising at least one machining means, this machining tool being rotatable about said common axis, and

- a first drive motor in rotation of said machining means.

The tooling, thanks in particular to its central body, can thus be arranged directly inside the fan casing regardless of the position of the casing. The tool according to the invention then makes it possible, in particular by means of its measuring and machining tools, to machine the abradable annular layer until the disappearance of the roughness without it being necessary to dismantle the assembly. of the housing to recondition the annular abradable layer. In addition, by reducing roughness and other non-conformities, machining makes it possible to improve the performance of the crankcase while avoiding retouching by adding material which could cause subsequent detachment.

The tool according to the invention may comprise one or more of the characteristics below, taken separately with each other or in combination with each other:

- the machining and measuring tools are substantially diametrically opposed with respect to said axis;

- a second rotary drive motor, at least measuring and machining tools, around said common axis,

- At least one of the first and second motors is pneumatic;

- said machining means is housed in a shavings and dust protection and containment cover, this cover being carried by the machining tool;

- the cover is connected by a pipe to a chip and dust suction pump;

- the feeler has an elongated shape along said axis and is connected by its longitudinal ends to guides allowing movement of the feeler in a radial direction with respect to said axis;

- said machining means has a machining dimension along said axis, which is configured to represent at least 90% of the dimension of the abradable layer along this axis;

-- said machining means is a rotary cutter;

-- the central body is configured to be fixed to the fan disk.

The invention also relates to a method for repairing an abradable annular layer of a fan casing of an aircraft turbine engine, using a tool as described above, comprising the steps consisting of:

a) center the central body on the fan disc,

b) rotating said machining means by means of the first motor, and rotating the measuring and machining tools around said axis, so as to machine the abradable layer of the casing.

The process according to the invention comprises at least one preliminary step chosen from:

- the dismantling of a cone vis-à-vis said fan disc,

- the rotation of the measuring and machining tools around said axis, for example by means of the second motor, without rotating the cutter, so as to ensure that the probe bears and is correctly positioned on the layer abradable,

- the mounting of the measuring and machining tools on the central body, these tools being chosen according to the shape and dimensions of the casing as well as the abradable layer, and

- lifting and moving the tool from a storage area to the turbine engine, by means of a hoist and a connecting beam from the hoist to the tool, this powder having for example a general shape L or U.

Advantageously, the fan disc is driven in rotation with the measuring and machining tools in step b), for example by said second motor.

Advantageously, step b) comprises performing at least one annular pass with the cutter on the abradable layer, and preferably two successive annular passes, so as to remove a thickness of the abradable layer of between 2 and 10 mm.

Brief description of figures

Other characteristics and advantages of the invention will appear during the reading of the detailed description which will follow for the understanding of which reference will be made to the appended drawings in which:

there is a schematic representation of an axial sectional view of a fan of an aircraft turbomachine,

there is a schematic representation of a perspective view of a fan casing,

there is a schematic representation of a partial axial sectional view of a fan casing,

there is a schematic representation of an axial sectional view of an abradable layer intended for a fan casing,

there is a schematic representation of a side view of a fan casing and of a machining tool according to the invention,

there is a schematic representation of an axial sectional view of a machining tool according to the invention inserted into a part of a fan disc,

there is a schematic representation of an axial sectional view of part of the machining tooling of the ,

there is a schematic representation of an axial sectional view of a machining tool of the machining tool according to the invention, and

there is a schematic representation of an axial sectional view of part of the machining tool according to the invention.

Detailed description of the invention

There partially represents a fan of an aircraft turbine engine.

Conventionally, a turbomachine comprises, from upstream to downstream, that is to say in the direction of flow of the gas flows, a fan, one or more compressors, a combustion chamber, one or more turbines, and a nozzle for ejecting the combustion gases leaving the turbine or turbines.

The fan 1 comprises a disk 2 with blades which is surrounded by a casing 3 of the fan, also called a retention casing because of its function of retaining the blades in the event of their breaking, or in the event of entry of debris in the blower.

As can be seen on the , the fan casing 3 has a generally cylindrical shape with an axis of revolution A.

It includes a 3' annular fixing flange at each of its axial ends. These flanges 3′ are used to fix the casing 3 to the annular walls of the nacelle of the turbomachine.

As shown at this , a layer of abradable material 10b is present inside the casing 3 of the fan while being of revolution in the casing 3 of the fan.

The fan casing 3 therefore extends around the disk 2 with fan blades. It therefore comprises an internal cylindrical surface which is provided with an annular layer 10b of abradable material.

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

This makes it possible to optimize the radial clearances between the blades 2a and the fan casing 3 which surrounds it and therefore to limit the gas leaks at the tops or radially outer ends of the blades, and thus to optimize the performance of the turbomachine.

The abradable layer 10b can be supported by a solid support cartridge 4 or having a honeycomb structure. This cartridge 4 is generally riveted or screwed onto the casing 3 of the fan.

The fan casing 3 is connected on the one hand to an air inlet 5, and on the other hand to an intermediate casing shell 6. It also carries an upstream acoustic shell 7 and a downstream acoustic panel 8.

Without this being essential in the context of the present invention, three types of zone can be recognized on the fan casing 3 .

The first type of zones called zones Z1 groups together the flange zones comprising an upstream flange zone and a downstream flange zone. The upstream flange zone includes the connection between the fan casing 3 and the air inlet duct 5 and the downstream flange zone includes the connection between the fan casing 3 and the intermediate casing shell 6.

The second type of zones called Z2 zones groups together the structural zones comprising an upstream structural zone and a downstream structural zone. The upstream structural zone is located at the level of the upstream acoustic shroud 7 and the downstream structural zone is located at the level of the downstream acoustic panel 8.

The third type of zone comprises a single retention zone, called zone Z3. This zone Z3 performs the primary function of the fan casing 3 and guarantees the static and dynamic mechanical strength of the assembly by ensuring rapid dynamics. The third zone Z3 houses the middle portion of the fan casing 3, the support cartridge 4 of the abradable layer 10b and the abradable layer 10b.

As mentioned previously, and with regard to the , the abradable layer 10b can be damaged, for various reasons and not only because of its cooperation with the bladed disc, by the formation of a locally hollowed surface forming a local asperity 11a, 11b, 11c in the layer and this according to several depth levels all requiring progressively greater reconditioning as depth increases. Asperity is understood to mean a surface unevenness due to a removal of material, local and of micrometric size, on the face of the abradable annular layer.

The face 10a having this or these asperities, advantageously a lack of material forming an asperity 11a, 11b, 11c more or less wide and / or more or less deep, of respective depths referenced l1, l2 and l3 is the face located in screw -to 10a sequentially with one 2a of the blades of a fan bladed disc as shown previously in .

The roughness or roughnesses are caused, in particular but not exclusively, by local crumbling on the facing face 10a causing the creation on the face 10a, facing a blade 2a, of an asperity 11a, 11b, 11c of a respective depth l1, l2, l3 in the abradable layer 10b.

It is of course possible that there are other roughnesses with intermediate roughnesses or even deeper roughnesses.

A machining tool 20 according to the invention is represented on the (outside crankcase 3) and on the (inside housing 3). Such a tool 20 is configured to machine the abradable layer 10b of the casing 3 of the fan 1 with the aim in particular of reconditioning this abradable layer 10b, in particular by machining the abradable layer 10b until the roughness disappears, that is that is to say according to a depth at least identical to the greatest depth of the asperities.

The tool 20 includes for this:

- a central body 30 for centering, or even also for fixing, on the fan disc 2 of the turbomachine,

- a measuring tool 40 connected to the central body 30 and comprising at least one feeler 41 configured to rest on the abradable layer 10b, this measuring tool being able to rotate around the axis A common to the central body 30 and to the disk 2 blower,

- a machining tool 50 connected to the central body 30 and comprising at least one machining means such as a rotary cutter 51, this machining tool being rotatable about said common axis A,

- a first motor 52 for driving the machining cutter 51 in rotation, and preferably

- a second motor 32 for driving in rotation, at least measuring tools 40 and machining tools 50, around the axis A.

The machining 50 and measuring 40 tools as well as the central body 30 are, for example, interconnected by a shaft 90. The shaft extends radially along a dimension substantially smaller than that of an inside diameter of the casing 3 in order to allow the axial insertion of the tool 20 in the casing 3. The machining 50 and measuring 40 tools are in particular substantially diametrically opposed with respect to the axis A.

The invention also relates to a method for repairing an abradable annular layer 10b by means of the tool 20, comprising the steps consisting in:

a) center or even fix the central body 30 on the fan disc 2,

b) rotating the milling cutter 51 by means of the first motor 52, and rotating the measuring 40 and machining 50 tools around the axis A, for example by means of the second motor 32, so as to machine the abradable layer of the crankcase.

Step b) comprises for example the production of at least one annular pass with the cutter 51 on the abradable layer 10b, and preferably two successive annular passes, so as to remove a thickness of the abradable layer 10b comprised between 2 and 10mm. By "pass" is meant the realization of a complete rotation of the tool 20 around the axis A.

The method can also comprise at least one preliminary step chosen from:

- removing a cone (referenced 15 on the ) opposite fan disc 2,

- the rotation of the measuring tools 40 and machining 50 around the axis A, for example by means of the second motor 32, without rotating the cutter 51, so as to ensure that the feeler 41 takes support and is correctly positioned on the abradable layer 10b,

- the mounting of the measuring 40 and machining 50 tools on the central body 30, these tools 40, 50 being chosen according to the shape and dimensions of the casing 3 as well as of the abradable layer 10b, and

- lifting and moving the tool 20 from a storage area to the turbine engine, by means of a hoist 60 and a connecting beam 70 from the hoist 60 to the tool 20, this powder 70 having for example a general L or U shape.

The tool 20 is thus brought inside the casing 3, in particular via the hoist 60 and the beam 70. The tool 20 has a mass of between 100 and 150 kg.

The hoist 60 is vertically mobile, that is to say it moves from top to bottom, in order to position the tool 20 at the height of the casing 3, that is to say at the height at which the casing 3 and the tool 20 share the same axis of revolution A, in order to allow the centering, insertion and fixing of the tool 20 in the casing 3.

The beam 70 here has a U-shape. The beam 70 thus comprises three bars 71, 72, 73 forming the U. The first bar 71 extends substantially horizontally and is mounted on the hoist 60 via a link mobile allowing its horizontal displacement, that is to say in particular parallel to the axis A. The first bar 71 is mounted on the hoist 60 so as to horizontally center the center of gravity of the assembly of the tool 20 and of the beam 70 with respect to the hoist 60. The second bar 72 extends substantially vertically and connects the first bar 72 to a third bar 73 of the beam 70. The third bar 73 extends substantially horizontally and is fixed at the level from its free end 74 to the tool 20 and in particular at any point on the shaft 90. The first, second and third bars 71, 72, 73 are fixed relative to each other.

Thus, once the tool 20 is centered relative to the casing 3 thanks to the hoist 60, it is inserted along the axis A in the casing 3 by a horizontal displacement of the beam 70 relative to the hoist 60, in particular by the through its first bar 71. Once the tool 20 has been inserted inside the casing 3, it is fixed to the fan disc 2 by means of a fixing means 31 which the central body 30 comprises.

The beam 70 is then separated from the tool 20 and makes a reverse translation to come out of the casing 3.

The tool 20 further comprises movement means 58 allowing the machining tool 50 to be moved in translation with respect to the shaft 90, that is to say radially. These displacement means 58 thus make it possible to position the cutter 51 in contact with the abradable layer in order to be able to adjust the depth of cut and therefore to carry out the machining.

The fan disc 2 is driven in rotation with the measuring 40 and machining 50 tools in step b), for example via the second motor 32.

At least one of the first 52 and second 32 motors is pneumatic.

The tool 20 comprises in particular a pneumatic input 80 to rotate the second motor 32, for example at a speed of 3500 rpm. The tool 20 also includes a pneumatic circuit 81 intended to supply the first motor 52. The first motor 52 in particular drives the cutter 51 in rotation around an axis substantially parallel to the axis A.

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

As best seen in Figures 7 and 8, the cutter 51 is housed in a cover 53 for protection and containment of chips and dust, this cover 53 being carried by the machining tool 50.

The cover 53 is here connected by a pipe 54 to a pump (not shown) for suction of chips and dust. The vacuum cleaner thus makes it possible to prevent any aspiration of dust by the operators. The cover 53 is for example transparent in order to have a visualization of the cutter 51 and the abradable layer 10b during machining.

The cutter 51 has a machining dimension along the axis A, which is configured to represent at least 90% of the dimension of the abradable layer 10b along this axis A. Thus it is not necessary to provide an axial displacement of the cutter 51 to recondition the abradable layer once the tool 20 is positioned axially correctly inside the casing 3. The cutter 51 here has a dimension H of 120 mm in height and a length L of 213 mm. The cutter 51 is in particular of complementary shape to that of the abradable layer.

The cutter 51 comprises at least one machining element 55 and in particular from 2 to 8 machining elements, configured to be in contact with the abradable layer in order to machine it. The machining element(s) 55 are for example made of carbide and in particular fixed to a cutter body 56 by means of screws 57. The machining element(s) 55 are for example blades or edges.

As best seen at the , the feeler 41 has an elongated shape along the axis A thus having the shape of a measuring arm. The feeler 41 thus takes the form of the abradable layer and/or that of the casing. The measuring tool 40 comprises for example 2 to 4 feelers 41. The feeler(s) 41 are connected by their longitudinal ends 42a, 42b to guides 43a, 43b allowing movement of the feeler(s) 41 in a radial direction with respect to to the axis A. The feeler(s) 41 therefore move radially to remain in contact with the abradable layer in order to precisely measure its thickness and make it possible to provide information on the thickness of the abradable layer that remains to be machined and/ or already machined. The guides 43a, 43b thus allow the probe(s) 41 to bear and to be correctly positioned on the abradable layer 10b.

Claims (11)

Tooling (20) for machining an abradable annular layer (10b) of a casing (3) of a fan (1) of an aircraft turbine engine, this tooling (20) being configured to be at least partially housed in said casing (3) and comprising:
- a central centering body (30) configured to cooperate with a fan disc (2) of the turbine engine,
- a measuring tool (40) connected to the central body (30) and comprising at least one feeler (41) configured to rest on said layer (10b), this measuring tool being rotatable about a common axis ( A) to the central body (30) and to the fan disc (2),
- a machining tool (50) connected to the central body (30) and comprising at least one machining means (51), this machining tool being rotatable around said common axis (A), and
- a first motor (52) for driving said machining means (51) in rotation. Tooling (20) according to claim 1, in which the machining (50) and measuring (40) tools are substantially diametrically opposed with respect to said axis (A). Tooling (20) according to claim 1 or 2, in which it comprises a second rotary drive motor (32), at least measuring (40) and machining (50) tools, around said common axis (A ). Tool (20) according to one of the preceding claims, in which the said machining means (51) is housed in a cover (53) for protecting and containing shavings and dust, this cover (53) being carried by the machining tool (50). Tool (20) according to claim 4, in which the cover (53) is connected by a pipe (54) to a suction pump for shavings and dust. Tool (20) according to one of the preceding claims, in which the feeler (41) has an elongated shape along the said axis (A) and is connected by its longitudinal ends (42a, 42b) to guides (43a, 43b) allowing movements of the feeler (41) in a radial direction with respect to said axis (A). Tooling (20) according to one of the preceding claims, wherein said machining means (51) has a machining dimension along said axis (A), which is configured to represent at least 90% of the dimension of the abradable layer (10b) along this axis (A). Method for repairing an abradable annular layer (10b) of a casing (3) of a fan (1) of an aircraft turbine engine, by means of a tool (20) according to one of the preceding claims, comprising the steps consisting of:
a) center the central body (30) on the fan disc (2),
b) rotating said machining means (51) by means of the first motor (52), and rotating the measuring tools (40) and machining tools (50) about said axis (A), so as to machine the abradable layer of the housing. Process according to claim 8, in which it comprises at least one preliminary step chosen from:
- the dismantling of a cone (15) vis-à-vis said fan disc (2),
- rotating the measuring (40) and machining (50) tools around said axis (A), without rotating the cutter (51), so as to ensure that the feeler (41) bears and is correctly positioned on the abradable layer (10b),
- the mounting of the measuring (40) and machining (50) tools on the central body (30), these tools (40, 50) being chosen according to the shape and dimensions of the casing (3) as well as the abradable layer (10b), and
- lifting and moving the tool (20) from a storage area to the turbine engine, by means of a hoist (60) and a beam (70) connecting the hoist (60) to the tool (20), this powder (70) having for example a general L or U shape. Method according to Claim 8 or 9, in which the fan disc (2) is rotated with the measuring (40) and machining (50) tools in step b). Method according to one of Claims 8 to 10, in which step b) comprises performing at least one annular pass with the cutter (51) on the abradable layer (10b), and preferably two successive annular passes, so as to remove a thickness of the abradable layer (10b) comprised between 2 and 10mm.