Endoscopic device for repairing defects in a turbine blade by laser cladding

Abstract

Endoscopic device for repairing defects (16) in a turbine blade (15) by laser cladding, said device (10) comprising tooling (20) adapted to be attached to one end of a flexible rod, tooling (20) comprising at least: - a laser source (22) configured to be positioned opposite a region to be repaired on the blade (15) containing the defect (16), and - at least one material delivery nozzle (26, 28) configured to deposit metallic material onto the region to be repaired, opposite the laser source (22). Figure to be published with the abbreviation: 3

Description

Title of the invention: Endoscopic device for repairing defects in a turbine blade by laser cladding. Technical field of the invention

[0001] The invention relates to an endoscopic device for repairing defects in a turbine blade by laser reconditioning, in particular in a turbine blade of an aircraft turbomachine.

[0002] The invention also relates to a repair method implementing such a device. Prior art

[0003] Figure 1 illustrates a prior art turbomachine 1, intended for use in an aircraft, in particular an airplane. The turbomachine 1 extends along an axis X and comprises, from upstream to downstream in the direction of gas flow, a fan 2, a low-pressure compressor 3, a high-pressure compressor 4, a combustion chamber 5, a high-pressure turbine 6, and a low-pressure turbine 7. The low- and high-pressure compressors 3 and 4, the combustion chamber 5, and the high- and low-pressure turbines 6 and 7 are located in a so-called primary channel 8. A so-called secondary channel 9 extends around the primary channel 8, downstream of the fan 2.

[0004] The terms upstream and downstream are defined with respect to the direction of gas flow within the turbomachine 1.

[0005] The high and low pressure turbines 6, 7 each comprise several rows of blades aligned along the X axis, mounted on rotating movable disks around the X axis, and separated by rows of fixed blades, or distributors.

[0006] During operation, these blades may exhibit non-conformities due to exposure to their environment, particularly to gases from the combustion chamber and to particles and debris in the airflow. These non-conformities may also be due to wear and contact between parts. These non-conformities significantly reduce the service life of the parts and may lead to premature engine removal for repair or replacement of damaged parts.

[0007] Such engine removal operations are costly in terms of time and labor, and result in prolonged and undesirable aircraft downtime. Therefore, it is desirable to reduce the need for and frequency of these removals as much as possible.

[0008] There are types of retouching that can be carried out without removal, directly under the wing, such as retouching of the type known as "boroblending". Such retouching consists of removing a small amount of material at the level of The non-conformity is addressed to prevent the initiation and potential propagation of cracks or fissures. However, this method remains limited, as such material removal can reduce the aerodynamic potential and / or the mechanical strength of the part, which is unacceptable for many turbine blades. Removal for replacement is often necessary.

[0009] There is therefore a need for a method to reduce the effect of these non-conformities in a more suitable and generalizable way, without requiring frequent removal of the engine.

[0010] An example of an endoscopic reloading method is described in document FR 3118593, which involves an endoscopic system to deposit a filler material on the surface to be treated and then a second endoscopic system to perform brazing using a laser beam.

[0011] This method can be further improved to obtain better adhesion of the filler material to the treated surface and improved durability of the repaired area. Presentation of the invention

[0012] To this end, the invention relates to an endoscopic device for repairing defects in a turbine blade by laser cladding, said device comprising tooling adapted to be fixed to one end of a flexible rod, tooling comprising at least:

[0013] - a laser source configured to be positioned opposite a region to be repaired of the dawn including the defect, and

[0014] - at least one material feed nozzle, configured to deposit a material metallic on the area to be repaired, opposite the laser source.

[0015] Such a device makes it possible to repair defects in turbine blades without removing the engine, by carrying out the repair in situ by endoscopic means, and by supplying material to fill cracks or fissures and thus restore the aerodynamic potential of the blade and prevent any propagation or aggravation of the defect.

[0016] In addition, the use of laser cladding makes it possible to limit the thermal impact of the repair on the turbine blade and to obtain a good metallurgical bond of the material supplied with the turbine blade and good resistance of the deposited layers, as well as low shrinkage during cooling.

[0017] The deposition of metallic material opposite the laser source allows the material to be deposited in a state heated by the laser beam, in a remelting zone formed by the laser beam on the surface of the blade at the level of the deposit, improving the mechanical strength of the filler material.

[0018] The turbine blade is in particular a low pressure turbine blade, for example a movable blade mounted on a disc, or a fixed blade or deflector.

[0019] The defect is for example a crevice or a crack.

[0020] At least one material feed nozzle may include a metallic material feed nozzle in powder form.

[0021] Such a feature allows for a simple and easy supply of material, particularly in hard-to-reach places such as the bottom of a cove or a crack, and facilitates its fusion by laser.

[0022] The nozzle for supplying metallic material in powder form may include an annular conduit substantially coaxial with the laser source and opening through an annular aperture, the device being configured to circulate a powder entrainment gas in said annular conduit.

[0023] Such a feature allows the laser to ensure both the preheating of the powder before contact with the defect, and the superficial remelting of the blade material.

[0024] The at least one material feed nozzle may include at least one metallic material feed nozzle in the form of wire.

[0025] Such a characteristic allows material to be supplied in a dense form, leading to a layer of supplied material exhibiting low porosity and therefore good mechanical resistance.

[0026] The device may include at least two metallic material supply nozzles, configured to deposit at least two different materials from each other, successively or simultaneously.

[0027] Such a feature makes it possible to deposit successively or simultaneously two different materials for the repair, in order to obtain advantageous mechanical properties of the repaired area.

[0028] The two nozzles can be of the same type, for example two powder feed nozzles or two wire feed nozzles, or of different types.

[0029] The laser source may be capable of delivering variable power over a range extending between 900 W and 1700 W.

[0030] Such control of the power delivered within a range of relatively low power levels makes it possible to limit the thermally affected area around the repaired defect, and a higher power is not necessarily required for a blade repair which requires a fairly short time overall.

[0031] The invention also relates to a method for repairing a defect, such as a crack or fissure, in a turbine blade, implementing a device as described above, the method comprising the steps of:

[0032] - setting up the tooling against the defect, the laser source being positioned facing failing that,

[0033] - emission of a laser beam by the laser source to melt the surface material of the blade at the defect,

[0034] - deposition of metallic material by at least one feed nozzle, during the step laser beam emission, and

[0035] - continuation of the deposition and emission steps until the defect is plugged.

[0036] Such a method is notably implemented in situ, on the turbine blades of an engine still installed on an aircraft, without removing the engine.

[0037] The material deposition may include a deposition of a first metallic material in a bottom part of a supplied material, then a deposition of a second metallic material in a surface part of the supplied material.

[0038] Such a feature allows two different materials to be successively deposited in the bottom and on the surface of the deposit, in order to obtain advantageous mechanical properties for each part of the repaired area.

[0039] The first metallic material can be supplied in powder form and the second metallic material can be supplied in wire form.

[0040] This allows a material to be deposited in powder form at the bottom of the defect to reach said bottom more easily, and in wire form at the surface, to obtain lower surface porosity.

[0041] The laser beam can be emitted with a power between 900W and 1700W, in particular between 900W and 1300W, and preferably between 900W and 1000W.

[0042] Such relatively low power makes it possible to limit the thermally affected area around the repaired defect, and higher power is not necessarily required for a blade repair, which requires a fairly short overall time. Brief description of the figures

[0043] [Fig-1] is a longitudinal cross-sectional view of an aircraft turbomachine,

[0044] [Fig.2] is a schematic view of an endoscopic defect repair device according to the invention,

[0045] [Fig.3] is a schematic cross-sectional view of a defect repair tool included in the device of [Fig.1], and

[0046] [Fig.4] is a schematic cross-sectional view of a defect repaired according to a method according to the invention. Detailed description of the invention

[0047] Figure 2 represents an endoscopic device comprising a rod endoscopic flexible 11 and a head 12 placed at the end of the endoscopic rod 11.

[0048] The endoscopic rod 11 is for example fully or segmentally flexible, and allows access to regions of a turbomachine otherwise inaccessible without dismantling, for example the internal space of the turbines, in particular the low pressure turbine 7.

[0049] The head 12 is mounted at the end of the endoscopic rod 11 and can be remotely orientable in all directions.

[0050] The head 12 includes image acquisition means 13, comprising for example at least one camera and illumination means, for example by optical fiber. This allows observation of the internal space of the low-pressure turbine 7 and the turbine blades 15, in order to detect defects 16 and guide the head 12 to the defect 16.

[0051] The defect 16 is for example a crack or fissure formed in the blade 15, caused for example by an impact of an object external or internal to the turbomachine.

[0052] According to the invention, the head 12 also includes a tool 20 for repairing defects 16.

[0053] The defect repair tool 20 is shown in detail in [Fig.3], positioned opposite a defect 16 of a blade 15.

[0054] The tooling 20 includes a laser source 22 adapted to generate a laser beam 24. Said laser source 22 is oriented so that the laser beam 24 is incident on the defect 16 under operating conditions.

[0055] The tooling 20 is, for example, dimensioned so that the laser source 22 is positioned at a distance of less than 10 millimeters (mm) from the defect 16 under operating conditions. Preferably, this distance is on the order of 8 mm.

[0056] The tooling 20 also includes at least one nozzle 26, 28 for supplying metallic material. For example, the tooling 20 here includes a nozzle 26 for supplying material in powder form and a nozzle 28 for supplying material in wire form.

[0057] The laser beam 24 is projected along a Y axis of the laser source 22.

[0058] The laser beam 24 is projected onto the defect 16 in order to heat a filler material before its contact with dawn 15.

[0059] Advantageously, the laser beam 24 is also projected so as to generate a refusion zone Z of the material of the blade 15 at the level of the defect 16, to ensure good retention of the filler material at the blade 15.

[0060] Said refusion zone Z corresponds to a zone of the blade 15 in which the material forming the blade 15 is partially melted on the surface, by the supply of heat from the laser beam 24.

[0061] This reflow zone Z covers at least part of the defect 16, and, depending on the shape and extent of said defect 16, may cover the entire extent of the defect 16.

[0062] Advantageously, the reflow zone Z extends mainly over the defect 16 and only to a lesser extent over the undamaged parts of the blade 15.

[0063] The laser source 22 includes, for example, one or more laser diodes, for example infrared laser diodes.

[0064] The laser source 22 is capable of emitting the laser beam 24 with a power controlled by an operator. This power can vary, in particular, within a power range extending at least between 900 Watts (W) and 1700 W dynamically during the repair, under the control of the operator.

[0065] Preferably, the power actually used for the laser beam 24 for repairing the defect 16 is relatively low, for example between 900W and 1700W, and in particular between 900W and 1300W, advantageously between 900W and 1000W.

[0066] Such a power value is sufficient to melt a small quantity of filler material, particularly in powder form, and makes it possible to limit the area of ​​the blade 15 affected by the heat input around the defect 16.

[0067] Indeed, such a power value for the laser beam 24 makes it possible to obtain material deposition rates of, for example, between 4 g / min (grams per minute) and 9 g / min. Such deposition rates make it possible, for typical defect sizes, to carry out the repair in a short time, for example on the order of a few minutes.

[0068] The material supply nozzle 26 in powder form comprises an annular conduit 29 circumferentially surrounding the laser source 22 in a substantially coaxial manner.

[0069] The annular conduit 29 opens opposite the laser beam 24 through an annular opening 30.

[0070] The nozzle 26 delivers a metallic filler material in the form of a powder P carried by a driving gas Gl, directly into the laser beam 24.

[0071] The metallic powder P is then heated by the laser beam 24 and is deposited in the remelting zone Z where it forms a filler layer A bonded to the material of the blade 15.

[0072] Advantageously, the tooling 20 also includes a nozzle 32 for supplying a screening gas G2. Said nozzle 32 includes, for example, an annular conduit circumferentially surrounding the laser source 22. Said annular conduit opens through an annular aperture 34 located, for example, between the laser source 22 and the annular aperture 30 of the nozzle 26 for supplying material in powder form.

[0073] The nozzle 32 for supplying the screening gas G2 makes it possible in particular to protect the laser source 22 from a reflux of powder P.

[0074] The entrainment gas G1 and the screening gas G2 are, for example, inert gases, and may be identical or different from each other.

[0075] The material supply nozzle 28 in the form of wire includes a conduit in which a metal wire 36 is disposed, as well as means for depositing the metal wire 36.

[0076] The nozzle 28 is adapted to deposit the metal wire 36 through an opening 38 in the conduit, which opens below the opening 30 of the nozzle 26 for supplying powdered material. In particular, the opening 38 is arranged so as to deposit the metal wire 36 directly into contact with the blade 15, within the laser beam 24.

[0077] The filler material deposited in the form of a wire and the filler material deposited in the form of a powder are, for example, different from each other and exhibit different mechanical properties once solidified.

[0078] For example, the metal wire 36 may be made of a rigid metallic material, for example superalloys, particularly nickel-based ones. These include, for example, materials known as Inconel 625 (NiCrMoFeNbTaCoMnSiAlTiCPS superalloy) or René 142 (NiCoCrMoTiAlTaBZrC superalloy), which are compatible with blades made of nickel-based superalloys.

[0079] According to alternative embodiments, the tooling 20 comprises only the nozzle 26 for supplying material in powder form or only the nozzle 28 for supplying material in wire form.

[0080] Alternatively, the tooling 20 may include several nozzles of the same type, for example two nozzles 26 for supplying material in powder form, in particular configured to deliver two different materials from each other.

[0081] The method for repairing a defect 16, such as a crack or a crevice, in a turbine blade 15, implementing the device 10 is described below.

[0082] The method includes a preliminary step of placing the tooling 20 against the defect 16, by means of the endoscopic rod 11 of the device 10 by an operator.

[0083] The defect 16 can be detected by the operator using the image acquisition means equipping the head 12 of the endoscopic device 10, or it may have been detected beforehand, during an inspection of the turbine, for example using another endoscopic device.

[0084] The head 12 equipped with image acquisition means allows the tooling 20 to be positioned precisely and remotely controlled by the operator, in relation to the defect 16 and with an appropriate orientation for repair.

[0085] Thus, the laser source 22 is oriented towards the defect 16, so as to project the laser beam 24 onto the defect 16.

[0086] The process then includes a step of emitting said laser beam 24 in the direction of the defect 16, by the laser source 22, so as to form the refusion zone Z.

[0087] The laser beam 24 is emitted with a power between 900W and 1700W, in particular between 900W and 1300W, and preferably between 900W and 1000W. As mentioned above, such power is sufficient to deposit the small amount of material required to fill a defect in a reasonable time, and limits the size of the area thermally affected in the blade 15 by the laser beam 24.

[0088] The method also includes a step of depositing metallic material by at least one deposition nozzle 26, 28. The step of depositing metallic material takes place during the emission of the laser beam 24, so that the laser beam 24 heats the metallic material while it is being deposited.

[0089] For example, the metallic material deposition step can start simultaneously with the laser beam emission step 24.

[0090] Alternatively, the metallic material deposition step can start a predetermined time after the start of the laser beam emission step 24, for example to allow sufficient refusion zone Z to be created before deposition.

[0091] The metallic material deposition step includes, for example, two successive sub-steps of supplying two different materials through nozzles 26, 28.

[0092] The two materials are chosen to give properties suitable for the different parts Al, A2 of the repaired area, as seen in [Fig.4].

[0093] For example, the first deposited material, forming the first Al supply zone, can be chosen to restore the mechanical resistance of the blade 15 and to exhibit good flowability and good adhesion, allowing the most complete possible filling of the defect 16.

[0094] The first feed material is for example delivered in powder form through the corresponding nozzle 26, directly into the laser beam 24, said material being carried along by the entrainment gas Gl. Once introduced into the laser beam 24, the material in powder form is heated by the laser beam 24 and deposited in the remelting zone Z under the entrainment of the entrainment gas Gl and the screening gas G2, to form a first feed zone Al, visible in [Fig.4].

[0095] The powdery nature of the first filler material allows for rapid melting by the laser beam 24 and deposition in a hard-to-reach location, such as the bottom of the defect 16 for example.

[0096] The second material is chosen for example to have good surface hardness and good resistance to the internal conditions in the turbine, in order to prevent the formation of new cracks around the repaired area.

[0097] The second filler material is for example deposited in the form of a wire, after the deposition of the first filler material, to constitute a second filler zone A2 on the surface of the defect 16.

[0098] The solid nature of the second filler material makes it possible to give the second filler zone a low porosity and thus good mechanical, chemical and thermal resistance.

[0099] The process includes continuing the laser beam emission and material deposition steps until the defect 16 is plugged.

Claims

Demands

1. Endoscopic device (10) for repairing defects (16) in a turbine blade (15) by laser reloading, said device (10) comprising a tooling (20) adapted to be fixed to one end of a flexible rod (11), the tooling (20) comprising at least: - a laser source (22) configured to be positioned opposite a region to be repaired of the blade (15) comprising the defect (16), and - at least one material supply nozzle (26, 28), configured to deposit a metallic material onto the region to be repaired, opposite the laser source (22).

2. Device (10) according to the preceding claim, wherein at least one material supply nozzle (26, 28) comprises a metallic material supply nozzle (26) in powder form (P).

3. Device (10) according to the preceding claim, wherein the nozzle (26) for supplying metallic material in powder form comprises an annular conduit (29) substantially coaxial with the laser source (22) and opening through an annular aperture (30), the device (10) being configured to circulate a powder (P) entrainment gas (Gl) in said annular conduit (29).

4. Device (10) according to any one of the preceding claims, wherein at least one material feed nozzle (26, 28) comprises at least one metallic material feed nozzle (28) in the form of wire (36).

5. Device (10) according to any one of the preceding claims, comprising at least two nozzles (26, 28) for supplying metallic material, configured to deposit at least two materials different from each other, successively or simultaneously.

6. Device (10) according to any one of the preceding claims, wherein the laser source (22) is capable of delivering variable power over a range extending from 900 W to 1700 W.

7. Method for repairing a defect (16) in a turbine blade (15), implementing a device (10) according to any one of the preceding claims, the method comprising the steps of: - placing the tooling (20) against the defect (16), the laser source (22) being positioned facing the defect (16), - emitting a laser beam (24) from the laser source (22) to melt the surface material of the blade (15) at the level of the defect (16), - deposition of metallic material by at least one nozzle (26, 28) of supply, during the laser beam emission step (24), and - continuation of the deposition and emission steps until the defect (16) is closed.

8. Method according to the preceding claim, wherein the material deposition comprises a deposition of a first metallic material in a bottom part (Al) of a supplied material (A), then a deposition of a second metallic material in a surface part (A2) of the supplied material (A).

9. Method according to claim 7 or 8, wherein the first metallic material is supplied in powder form (P) and the second metallic material is supplied in wire form (36).

10. Method according to any one of claims 7 to 9, wherein the laser beam (24) is emitted with a power between 900W and 1700W, in particular between 900W and 1300W, and preferably between 900W and 1000W.