The present invention relates to a device for coating a surface of an annular casing of a turbine engine, comprising an abradable layer obtained by polymerisation of a resin.
The prior art includes in particular documents FR-A-2 339 741, U.S. Pat. No. 3,346,175 and EP-A1-2 202 264.
A turbine engine includes, at its upstream end (in relation to the flow of gasses in the turbine engine), a fan comprising an impeller which is surrounded by a casing, referred to as a retention casing owing to its function of retaining blades in the event of a breakage of said blades.
In a known manner, the impellers of a turbine engine are surrounded by a stator which has an annular coating made of an abradable material. The coating extends around and in close radial proximity to the blades, which may rub against the material and abrade said material during operation. This makes it possible to optimise the radial clearances between the blades and the stator surrounding said blades, and thus to limit gas leaks at the apexes or radially outer ends of the blades.
In the case of a retention casing, the fan blades are surrounded by an abradable layer which covers an inner annular surface of the casing. In the prior art, this abradable layer is obtained by spreading a polymerisable resin over the surface. Said resin is manually hammered in order to remove as many air bubbles as possible and in order to press the resin onto the casing. The finishing is completed by means of calendering, which is achieved by passing a design rule without any possible control on the force imposed. In addition, said calendering tends to exert a separating force on the resin. It is therefore a manual operation which can involve risk in the metering of components, and it is also an operation which is very restrictive for operators. In addition, said operation requires a lot of experience, which thus means it takes a long time to implement.
The present invention proposes a simple, effective and economical solution to at least some of the above-mentioned disadvantages of the prior art.
The present invention relates to a device for coating a surface of an annular casing of a turbine engine, comprising an abradable layer obtained by polymerisation of a resin, which device is characterised in that it includes:
The device according to the invention allows at least some of the manual operations from the prior art to be replaced by operations that are automated and thus more easily reproducible. The plastics film prevents the resin from adhering to the spreading means and makes it possible to ensure that the abradable layer has a good surface finish (for example smooth and shiny).
The device according to the invention can include one or more of the following features, taken independently or in combination:
the second means are designed to be able to move along at least two axes, preferably three axes,
The present invention also relates to an apparatus comprising a device as described above and a carriage for transporting and rotating an annular casing of a turbine engine, said carriage comprising means for rotating the casing about a substantially horizontal spin axis of the casing.
The apparatus according to the invention can include one or more of the following features, taken independently or in combination:
The present invention also relates to a method for coating a surface of an annular casing of a turbine engine, by means of at least one apparatus as described above, which method is characterised in that it includes the following automated steps of:
The invention will be better understood and further details, features and advantages of the invention will become more clearly apparent upon reading the following description, given by way of non-limiting example, and with reference to the accompanying drawings, in which:
Reference is first made to
The annular casing 10 has a generally substantially cylindrical shape having spin axis A. Said casing includes an annular attachment flange 12 at each of its axial ends. Said flanges 12 are used to attach the casing 10 of the annular walls of the nacelle of the turbine engine. The casing 10 may further include annular stiffeners 14.
The casing 10 includes a radially inner annular surface 16 that is covered by an abradable layer 18. Said layer 18 is continuous over 360° and has a length or axial dimension, along the axis A, which is 20 to 40% of the length of the casing in the example shown. In this case, said layer 18 is located close to the upstream end of the casing 10 and is intended to extend opposite the apex of the blades of the fan wheel. The layer 18 is obtained by polymerisation of a resin which is prepared from at least two components A and B.
The present invention proposes a coating device, in particular for coating the surface 16 of the casing 10 from
The apparatus includes in particular a carriage 20 for supporting and transporting the casing 10, a coating device 21 comprising a frame 22 for supporting a coating controller 24, and a console 26 for controlling said controller 24.
The carriage 20, which can be seen more clearly in
The framework 27 is fitted with wheels 29, in this case numbering four, which allow movements of the carriage, as well as of the casing 10 intended to be placed on the carriage. Said wheels 29 can engage with rails (not shown) in order to guide the carriage during said movements, and in particular in order to move said carriage further away from or closer to the frame 22 supporting the controller 24.
The body 28 of the carriage 20 includes a rigid structure made of metal girders 30 that are mutually attached for example by welding, the structure being surrounded by cowls 32. The general shape of the structure is that of a U or V, comprising a lower, substantially horizontal middle portion and two substantially vertical lateral portions. The casing 10 is intended to be positioned on the carriage 20 such that the lateral portions of the U or V extend on either side of the casing. The front and rear cowls 32 of the body 28 of the carriage each include an upper peripheral edge 34 in a C-shape of which the opening is oriented upwards. The radii of said peripheral edges 34 are similar to the radius of the casing 10, as can be seen in
The front and rear cowls 32 are preferably separated from one another by a distance greater than the length of the casing 10 such that said casing can be housed between the cowls.
The structure of the body 28 is fitted with rollers 34 for supporting and guiding the casing 10 in rotation. The rollers 34 are mounted so as to rotate freely about axes parallel to the axis A, and number four in the example shown. In this case, said rollers are grouped in pairs, a first pair of rollers 34 being positioned at an upper end of a lateral portion of the structure, and a second pair of rollers being positioned at an upper end of the other lateral portion of the structure.
The structure supports at least one pinion 36 having an outer toothing for engaging with a toothed ring 38 (
The pinion 36 has a rotational axis parallel to the axis A and is connected to a manually driven flywheel 40. In this case, said flywheel 40 is positioned in the region of the front cowl 32. The carriage includes another driven flywheel 42 in the region of a lateral cowl 32, which is connected to means for moving the carriage on the above-mentioned rails. Said flywheel 42 has a rotational axis perpendicular to the axis A.
The structure also supports a braking system, in this case comprising at least two mechanical brakes 44. The brakes 44 include pads that can be moved between a first position in which they are remote from the casing 10 and a second position in which they abut the casing in order to brake the rotation thereof or lock said casing in rotation. The brakes 44 are moved from the first position into the second position by operating a pedal 46 supported by the framework or the structure. The brakes 44 are released and moved from the second into the first position by operating a lever 48 of the carriage body, which lever passes through an oblong hole in the front cowl 32.
The device comprising the frame 22 and the controller 24 can be seen more clearly in
The controller 24 is preferably mounted so as to be able to move on the frame 22 along three axes, and includes a robotic arm controlled by the console 26 and supporting a plurality of pieces of equipment and accessories.
The controller 24 may firstly include means for depositing the resin, which include means for preparing the resin and means for ejecting said resin.
The means for preparing the resin include removable cartridges 52, 52′ for storing the components of the resin, and means 56 for mixing said components. In the example shown, in which the resin is obtained by mixing two components, the controller 24 supports a plurality of cartridges 52, 52′ of each component. In this case, said controller includes three cartridges 52 of a component A such as a base (including a monomer, for example epoxy) and three cartridges 52′ of a component B such as a crosslinking agent or hardener. In this case, the cartridges 52, 52′ have a generally elongate cylindrical shape and are arranged in parallel with one another in the same vertical plane B. The three cartridges 52 are arranged in front of the cartridges 52′ and the rear ends thereof are connected to a common chamber 54 for receiving component A from the cartridges 52. The three cartridges 52′ are aligned with the cartridges 52 and the front ends thereof are connected to a common chamber 54′ for receiving component B from the cartridges 52.
The means 56 for mixing components A and B are arranged between the chambers 54, 54′. Said mixing means include, for example, an endless screw mixer 56, which is supplied with components A and B under pressure. Components A and B can be expelled from the cartridges and received in the chambers 54, 54′ by means of pressure, for example hydraulic pressure.
The means for preparing the resin may include means for heating the cartridges 52, 52′ or chambers 54, 54′ in order to optimise the viscosity of the components A and B and in order to minimise the risk of air bubbles forming in the resin.
The components A and B are for example components sold by the company 3M™ under the name Scotch-Weld™ 3524 B/A.
The depositing means include at least one nozzle 58 for ejecting the resin after mixing. In the example shown, the nozzle 58 has a rectilinear elongate shape and extends vertically downwards from the mixer 56. The resin is intended to be expelled from the bottom end of the nozzle 58.
As can be seen in
The frame 22 further includes means for spreading the resin after it has been deposited on the surface 16 of the casing 10 to be coated. In this case, said spreading means include a series of rolls 60 mounted so as to rotate freely about axes parallel to the plane P and about the above-mentioned axis A. Said rolls 60 can be seen more clearly in
The resin ejected by the nozzle 58 is thus intended to be spread and shaped into layers by means of the rolls 60. However, a plastics film is interposed between the resin and the rolls 60 in order to facilitate said spreading operation and address the risk of the resin adhering to the rolls 60. Covering with the plastics film spreads the resin. For this purpose, the frame 22 includes at least one plastics film reel 64 (
It can be seen in
The film 69 is preferably a polyester film such as a polyethylene terephthalate film. Said film can have a thickness of approximately 0.125 mm.
As can be seen in
In this case, the scraping means 68 include a scraper 70 for scraping the coated surface 16 of the casing 10 and for removing the resin which is then discharged into a storage container 72. Said scraping means can be supported by the controller 24 or connected to the frame 22 so as to be able to move between at least two positions, a first stowed, non-operational position and a second operational position.
The frame 22 also includes means 74 for attachment to the carriage 20 so as to be able to lock the carriage relative to the frame and vice versa. Said attachment means 74 are, for example, snap locks, which can be seen more clearly in
The frame 22 also includes centring means 75 for engaging with the carriage 20. Said frame can further include at least one device for sensing the presence of the carriage.
The frame 22 also includes means 76 for retaining the casing 10 relative to the frame 20 so as to prevent movements of the casing relative to the frame in directions parallel to the axis A. Said retaining means 76 include, for example, rollers of which some (rear rollers) are stationary and the others (front rollers) can move between a position for locking and retaining the casing, which can be seen in
The frame 22 further includes means 78 for cutting the resin and the plastics film, such as those shown in
Reference is now made to
A first step of the method consists in mounting two rings 38, 82 on the axial ends of the casing 10, respectively. Said rings are intended not only to protect the casing 10 but also to allow it to rotate by means of the flywheel 40 and the pinion 36. The rings are removably attached to the flanges 12 of the casing 10 and are preferably divided into sectors in order to make it easier to mount and dismount said rings. The ring 38 includes an outer annular toothing 84 designed to engage with the pinion 36 of the carriage. Each ring 38, 82 can engage with a pinion 36 of the carriage.
Another step of the method consists in mounting lifting means 86 on the casing 10. Said lifting means include means 88 for attachment to the casing and, for example, to the stiffeners 14 of the casing 10 and lifting slings 90.
As can be seen in
The slings 90 are detached and the carriage 2 can then be moved on the rails (not shown) by means of the flywheel 42, as far as a position in which the carriage can be locked relative to the frame 22 by means of the snap locks 74 in
A portion of the plastics film of the roll 64 is drawn by an operator and slid between the rolls 60 and the surface 16 of the casing 10 to be coated. The brakes 46 of the carriage can then be released by the lever 48 so as to allow a rotational movement of the casing 10 about its axis A.
The controller 24 is then controlled to start the steps of preparing the resin and depositing the resin on the surface 16 of the casing 10 to be coated (
As can be seen in
When the casing 10 is coated with a layer over close to 360° of its angular extent, the free circumferential end of the layer corresponding to the end of the deposition can be cut in order to define another perfectly rectilinear end edge. The two end edges of the layer corresponding to the start and the end of the deposition of the resin are preferably at an angular distance from one another, for example of a few centimetres. This space can be manually filled in with resin in order to ensure a perfect finish and a perfect joint between said end edges. Said joint is preferably positioned on the casing at 12 o'clock, using the analogy of a clock face. It is therefore understandable that the steps of rotating the casing, depositing resin on the surface of the casing, and spreading resin by means of the plastics film, are stopped before a complete rotation of the casing. The casing 10 can thus be stored in a place that is conducive to the complete polymerisation of the resin.
Number | Date | Country | Kind |
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1555597 | Jun 2015 | FR | national |
Filing Document | Filing Date | Country | Kind |
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PCT/FR2016/051402 | 6/10/2016 | WO | 00 |