Method for reinforcing at least one area to be protected of an aircraft turbomachine casing, and casing reinforced using such a method

Abstract

The invention relates to a method for reinforcing at least one area to be protected (Z) of an aircraft turbomachine casing (9), the method comprising at least one step of depositing a protective layer (C) comprising a wear-resistant material on a portion of the external surface of the casing so as to cover at least the entirety of the area(s) to be protected (Z). Figure 4.

Description

Title of the invention: Method for reinforcing at least one area to be protected of an aircraft turbomachine casing, and casing reinforced using such a method Technical field

[0001] The present invention relates to the field of aeronautics. It relates more particularly to the protection of aircraft turbomachine elements such as a casing, and in particular a compressor, turbine or exhaust casing. State of the art

[0002] The turbomachines used for aircraft propulsion comprise a gas generator. The gas generator comprises in particular, from upstream to downstream in relation to the direction of gas circulation, a rectifier, a low-pressure compressor, a high-pressure compressor, a combustion chamber, a high-pressure turbine and a low-pressure turbine.

[0003] These different elements are contained in respective casings, which are generally made from alloys having the required qualities of lightness and strength, for example titanium-based alloys. The progress made in the field of materials and manufacturing processes has led manufacturers to produce casings having significantly thinner walls than before, in order to reduce the weight of these elements. Due to the thinness of their walls, these elements can be sensitive to impacts, for example impacts linked to tool strikes during maintenance operations. When an element such as a turbomachine casing is marked by an impact, it may happen that this requires the replacement of the entire part.

[0004] The objective of the present invention is to propose a method for locally reinforcing casing-type parts, only in areas likely to receive impacts. Statement of the invention

[0005] To this end, the invention relates to a method for reinforcing at least one area to be protected of an aircraft turbomachine casing, the method comprising at least one step of depositing a protective layer comprising a wear-resistant material on a portion of the external surface of the casing so as to cover at least the entirety of the area(s) to be protected.

[0006] Thus, by making it possible to locally reinforce a casing by means of a protective layer comprising a wear-resistant material, the method which is the subject of the invention makes it possible to provide more resistant casings without, however, increasing their weight.

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[0018] too significantly. The method according to the invention makes it possible to increase the durability of the parts concerned by avoiding their premature replacement in the event of significant and / or repeated impacts on the same area. Advantageously, the protective layer is made of wear-resistant material. In one embodiment, the wear-resistant material of the protective layer is chosen from the following materials: - a steel alloy containing chromium and cobalt; - a nickel-based alloy, containing chromium and aluminum. In one embodiment, the wear-resistant material of the protective layer is deposited by welding, by a plasma thermal spraying process or by a hypersonic thermal spraying process. In one embodiment, the method comprises, before the state of deposition of a protective layer, a step of at least partial removal of a pre-existing protective layer made of a wear-resistant material. In one embodiment, the pre-existing protective layer is partially removed, so that over the entire area(s) to be protected, there remains a minimum thickness of the pre-existing protective layer forming a residual layer. In one embodiment, the protective layer is deposited on the residual layer. In one embodiment, the housing is one of the following: - a high pressure compressor housing; - a combustion chamber casing; - a high pressure turbine housing; - a low pressure turbine housing; - an exhaust casing. In one embodiment, the casing comprises a titanium-based or nickel-based alloy. The invention also relates to an aircraft turbomachine casing, the casing being reinforced by means of a reinforcement method as defined above and comprising at least one protective layer. The invention also relates to a turbomachine for aircraft, comprising at least one casing as defined above. Brief description of the drawings [Fig.l] [Fig.l] is a schematic side view of an aircraft turbomachine according to the invention. [Fig.2] [Fig.2] is a detailed sectional view of the turbomachine's attachment elements at the exhaust casing.

[0019] [Fig.3] [Fig.3] is a detailed perspective view showing an unreinforced exhaust casing that has been impacted.

[0020] [Fig.4] [Fig.4] shows the exhaust casing of [Fig.3] after implementation of a method according to the invention.

[0021] [Fig.5] [Fig.5] shows a protective layer located near the exhaust housing mounting flange.

[0022] [Fig.6] [Fig.6] shows the protective layer of [Fig.5] showing marks following impacts.

[0023] [Fig.7] [Fig.7] shows the protective layer of [Fig.6] being replaced.

[0024] [Fig.8] [Fig.8] shows the protective layer of [Fig.6] after replacement.

[0025] [Fig.9] [Fig.9] is a diagram illustrating the steps of a method according to the invention. Detailed description

[0026] [Fig. 1] represents an aircraft turbomachine 1 according to the invention, in the example a bypass turbojet (represented without the normally associated nacelle). The turbomachine 1 comprises a fan, surrounded by a fan casing 3, and a gas generator 4. In the example, the gas generator comprises, from upstream to downstream (relative to the direction of circulation of the gases in the turbomachine), a low-pressure compressor (not visible), a high-pressure compressor, a combustion chamber, a high-pressure turbine and a low-pressure turbine, and a gas exhaust casing, to which an exhaust nozzle is connected (not shown).

[0027] The turbomachine thus comprises different casings 5, 6, 7, 8, 9, such as the high-pressure compressor casing 5, the combustion chamber casing 6, the high-pressure turbine casing 7, the low-pressure turbine casing 8, or the exhaust casing 9 (often referred to by the acronym TRF corresponding to the English term “turbine rear frame”). These casings 5-9 are generally made of a titanium-based or nickel-based alloy (such as, for example, the alloys marketed under the brand Inconel©), and are elements likely to receive impacts, whether during operation of the turbomachine, for example due to friction or collision with other parts, or during maintenance operations, for example due to impacts caused by tools.

[0028] [Fig. 2] is a detailed sectional view of the exhaust casing 9 of the turbomachine 1, when the latter is attached under the wing. As visible in [Fig. 2], in order to allow the turbomachine 1 to be fixed to a pylon secured to an aircraft, the exhaust casing 9 comprises fixing clevises 90 cooperating with an axis retaining pin 92. A locking pin 94 is installed on the retaining pin 92. During operation of the turbomachine 1, the relative movements between the turbomachine and the pylon can cause the locking pin 94 to rub on the exhaust casing 9, or to generate shocks on the latter, and thus cause deterioration of the external surface 9a of the exhaust casing 9.

[0029] [Fig. 3] is a detailed view of the exhaust casing 9 showing the external surface 9a of this casing near one of the fixing yokes 90. The external surface 9a of the exhaust casing 9 is marked by impacts I due to the locking pin 94 and occurring during the operation of the turbomachine. As mentioned above, these impacts can in certain cases lead to the replacement of the exhaust casing 9.

[0030] In order to avoid these drawbacks, the method according to the invention makes it possible to locally reinforce a casing, in the example the exhaust casing 9, in order to better withstand the shocks and impacts suffered during normal operation, but also during maintenance operations. As can be seen in [Fig. 3], a zone to be protected Z is defined locally, the zone to be protected Z encompassing an extent of the external surface 9a of the exhaust casing 90 likely to receive shocks. Thus, in the example of [Fig. 4], the zone to be protected Z located near the location of the locking pin 94 encompasses the zone in which the impacts I of [Fig. 3] are located.

[0031] As visible in [Fig.4], the area to be protected Z is reinforced by implementing a step of depositing a protective layer C comprising a wear-resistant material, the protective layer C covering the external surface 9a of the exhaust casing at the area to be protected Z, and extending so as to cover at least the entire area to be protected Z. Preferably, the wear-resistant material of the protective layer C will be chosen so that it has a hardness greater than or equal to the hardness of the material of the area to be protected Z. Advantageously, the protective layer C is made of the wear-resistant material.

[0032] Different wear-resistant materials can be used, in particular depending on the temperature in service, and for example: - a steel alloy containing chromium and cobalt, such as the material marketed under the brand name Stellite©, such a material being able to be deposited for example by welding; - a nickel-based alloy, comprising chromium and aluminium, such as the material marketed under the brand name Inconel©, such a material being able to be deposited by a plasma thermal spraying process or by a hypersonic thermal spraying process (known by the acronym HVOF corresponding to the English term “high velocity oxygen fuel”).

[0033] Figures 5 to 8 are detailed views of the exhaust casing 9 partially showing a fixing flange 96 of this casing. The fixing flange 96 is used to fix the exhaust casing 9 to the low-pressure turbine casing 8. The fixing flange 96 has for this purpose a plurality of holes 98 allowing the fixing flange to be bolted. The area of ​​the exhaust casing 9 located near the fixing flange 96 thus constitutes an area to be protected Z. Indeed, the proximity of the fixing flange 96 generates significant risks that the external surface 9a of the exhaust casing 9 receives impacts due to tools during maintenance operations, and more precisely during the assembly or disassembly of the exhaust casing 9. As visible in [Fig. 5], the portion of the external surface 9a of the exhaust casing 9 located in the immediate vicinity of the flange thus constitutes an area to be protected Z.According to the invention, this area to be protected Z is reinforced by a protective layer C comprising a wear-resistant material.

[0034] The zones Z protected in accordance with the invention remain, however, liable to be damaged over time. Thus, as visible in [Fig. 6], the protective layer C may be marked by impacts I. Depending on the number and the importance of these impacts, it may prove necessary to replace or recharge the existing protective layer (hereinafter pre-existing protective layer C'), in order to prevent it from being altered to the point of no longer correctly protecting the exhaust casing 9. The steps for replacing the pre-existing protective layer C' are described below.

[0035] As shown in [Fig.7], the replacement of a pre-existing protective layer C' requires the implementation of a preliminary step of partial removal of this layer. The removal of the pre-existing protective layer C' can be carried out in particular by machining. Preferably, the pre-existing protective layer C' is removed so that a minimum thickness of wear-resistant material remains over the entire area to be protected. Thus, after the implementation of the removal step, a residual layer C" remains over the entire area to be protected Z.

[0036] As shown in [Fig.8], the protective layer C is then deposited, which in the example constitutes a new protective layer, or replacement layer.

[0037] The protection method according to the invention can be implemented both during the manufacture of a new part and during the adaptation of an existing part (in other words, during a "retrofit" operation). Finally, the method according to the invention can also be used to protect an already damaged part, such as for example the part in [Fig. 3].

[0038] [Fig.9] represents the steps of implementing a reinforcement method in accordance with the invention described above in relation to figures 3 to 8.

[0039] Thus, the reinforcement method 100 comprises at least one step 104 of depositing a protective layer C comprising a wear-resistant material on a portion of the external surface of the casing 5-9 so as to cover at least the entirety of the zone(s) to be protected Z. The depositing step can be implemented in particular in the manner described above.

[0040] Optionally, the method may comprise, prior to the deposition step 104, a step 102 of at least partial removal of a pre-existing protective layer C' comprising a wear-resistant material. This removal step may be implemented in the manner described above.

Claims

Claims

1. Method for reinforcing (100) at least one area to be protected (Z) of a casing (5-9) of an aircraft turbomachine (1), the method comprising at least one step of depositing (104) a protective layer (C) comprising a wear-resistant material on a portion of the external surface of the casing (5-9) so as to cover at least the entirety of the area(s) to be protected (Z).

2. Reinforcing method (100) according to the preceding claim, wherein the wear-resistant material of the protective layer (C) is chosen from the following materials: - a steel alloy comprising chromium and cobalt; - a nickel-based alloy, comprising chromium and aluminum.

3. Reinforcing method (100) according to one of the preceding claims, in which the wear-resistant material of the protective layer (C) is deposited by welding, by a plasma thermal spraying method or by a hypersonic thermal spraying method.

4. Reinforcing method (100) according to one of the preceding claims, comprising, before the state of deposition of a protective layer (C), a step of at least partial removal (102) of a pre-existing protective layer (C') made of a wear-resistant material.

5. Reinforcing method (100) according to the preceding claim, in which the pre-existing protective layer (C') is partially removed, so that over the entire area(s) to be protected (Z), there remains a minimum thickness of the pre-existing protective layer (C') forming a residual layer (C”).

6. Reinforcing method (100) according to the preceding claim, in which the protective layer (C) is deposited on the residual layer (C”).

7. Reinforcing method (100) according to the preceding claim, wherein the casing is one of the following: - a high pressure compressor casing (5); - a combustion chamber casing (6); - a high pressure turbine casing (7); - a low pressure turbine housing (8); - an exhaust housing (9).

8. Reinforcing method (100) according to one of the preceding claims, in which the casing (5-9) comprises a titanium-based or nickel-based alloy.

9. Casing (5-9) of an aircraft turbomachine (1), the casing being reinforced by means of a reinforcement method according to one of the preceding claims and comprising at least one protective layer (C).

10. Turbomachine (1) for aircraft, comprising at least one casing (5-9) according to the preceding claim.

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