Casing for protecting blade roots during coating operations and related methods

Abstract

A protective housing (20) is used to receive the root (6) of a blade (2) during a coating operation. The blade (2) is provided with a root (6) for mounting the blade in a slot in a rotor disk. The root (6) extends axially from an upstream face (16) to a downstream face (18). The housing (20) includes a plurality of components (22, 24) configured to assemble with each other and together form a recess (30) for the root (6) of the blade (2). The recess (30) is larger than the root (6) of the blade (2). The assembled housing (20) includes: - an upstream portion (32), - a downstream portion (34), and - The intermediate portion (36), which extends from the upstream portion (32) to the downstream portion (34), has an axial dimension equal to that of the root (6) of the blade (2) and is used to receive the root (6) of the blade (2) during the coating operation. The joint (38) between the components (22, 24) is entirely formed in the intermediate portion (36) while maintaining a certain distance from the axial end of the intermediate portion (36). The recess (30) of the root (6) of the blade (2) has a larger size than the root (6) of the blade (2) and is able to receive the root (6) of the blade (2) in the housing (20) such that a gap is maintained between the root (6) of the blade (2) and the wall of the housing (20) forming the recess (30) of the root (6) of the blade (2).

Description

Technical Field

[0001] The technical field of this invention relates to blades, particularly aircraft turbine blades, and more specifically to blade coating operations.

[0002] In particular, the present invention relates to a protective housing at the root of a blade during a coating operation and a method for coating the blade. Background Technology

[0003] To protect turbine blades from the high-temperature environment of the turbine, a coating is usually applied to the turbine blades.

[0004] During the coating operation, it is advantageous to cover certain surfaces of the blades to prevent coating from depositing on these surfaces.

[0005] It is known that a protective cover forms around the base of the blade. When this cover comes into contact with the blade, the coating on the blade may peel off during the removal of the cover.

[0006] During vapor phase spraying of the coating, the coating may penetrate through the joint of the cover and deposit on the root of the blade.

[0007] During visual inspection of the leaf roots, it can sometimes be difficult to detect coating overflow. Summary of the Invention

[0008] Therefore, one object of the present invention is to overcome all or part of the above-mentioned disadvantages, and in particular to provide a protective housing that is easy to assemble and facilitates visual inspection of any coating overflow on the blades.

[0009] This invention relates to a protective housing designed to receive the root of a blade during a coating operation. The blade has a root portion that mounts the blade in a groove in a rotor disk, the root portion extending axially from an upstream face to a downstream face. The housing includes multiple components configured to be assembled and collectively form a recess in the root of the blade, the recess being larger than the root of the blade. The assembled housing includes:

[0010] - Upstream section,

[0011] - Downstream section, and

[0012] - The middle portion, which extends from the upstream portion to the downstream portion, has an axial dimension equal to the axial dimension of the root of the blade, and is designed to accommodate the root of the blade during the coating operation.

[0013] The joints of the component are all formed in the middle portion, while maintaining a certain distance from the axial end of the middle portion.

[0014] After assembling the housing around the root of the blade, the upstream portion of the housing is intended to be located on the upstream side of the root of the blade, i.e., upstream of the root of the blade.

[0015] After assembling the housing around the root of the blade, the downstream portion of the housing is intended to be located on the downstream side of the root of the blade, i.e., on the downstream side of the root of the blade.

[0016] The terms radial, axial, and tangential are defined relative to the axis of the turbine on which the rotor disk is mounted. The axis of the turbine also coincides with the axis of rotation of the rotor disk.

[0017] The terms upstream and downstream are defined relative to the direction of gas flow in the turbine.

[0018] The root of the blade is composed of a spherical portion and a stalk-like portion. The spherical portion provides a mechanical connection between the blade and the rotor. The stalk-like portion extends radially outward from the spherical portion, particularly to the radially inner platform of the blade between the blade body and the root. The root of the blade extends axially from the upstream face of the spherical portion to the downstream face of the spherical portion.

[0019] In one particular embodiment, the blade is a turbine blade or a compressor blade.

[0020] The shell forms a barrier that prevents coating particles from moving toward the root of the blade. Therefore, the surface condition and mechanical properties of the material at the root of the blade remain constant.

[0021] The recess at the root of the blade, which is larger than the blade root, is able to accommodate the blade root within the housing, without the blade root contacting the wall of the recess. This prevents the coating on the blade from peeling off when the housing is removed.

[0022] The joints of the components are all formed within the intermediate portion, while maintaining a certain distance from the axial end of the intermediate portion. This ensures that any coating overflow will not gravitate towards the upstream and downstream surfaces of the blade root. Therefore, visual inspection of overflows at the blade root is more reliable, as the protruding edge of the blade root represents an area with a higher risk of error during visual inspection of overflows.

[0023] Advantageously, the entire joint is formed between a first axial coordinate and a second axial coordinate, the first axial coordinate corresponding to a position at 20% of the axial dimension of the intermediate portion, and the second axial coordinate corresponding to a position at 80% of the axial dimension of the intermediate portion. Alternatively, the first axial coordinate may correspond to a position at 40% of the axial dimension of the intermediate portion, and the second axial coordinate may correspond to a position at 60% of the axial dimension of the intermediate portion. Therefore, the risk of coating overflow from the upstream and downstream surfaces of the blade root is further spatially eliminated.

[0024] Advantageously, the housing includes: a first component having a recess in a first portion of the root of the blade; and a second component having a recess in a second portion of the root of the blade, the first component and the second component being configured to be assembled such that the recesses in the first and second portions of the root of the blade together form the recess in the root of the blade.

[0025] The structure of the housing is simplified by using only two components to form the recess at the root of the blade. The first component can be assembled with the second component around the root of the blade by being axially guided from upstream to downstream. The second component can be assembled with the first component around the root of the blade by being axially guided from downstream to upstream.

[0026] In this case, the depression in the first portion of the root of the leaf includes: the depression in the first portion of the bulbous part and the depression in the first portion of the stalk-like part. Similarly, the depression in the second portion of the root of the leaf includes: the depression in the second portion of the bulbous part and the depression in the second portion of the stalk-like part.

[0027] Preferably, the first component and the second component are assembled by interlocking.

[0028] According to one specific design, the first component includes a first sealing portion and a second sealing portion, the first sealing portion being offset toward the outside of the housing relative to the second sealing portion, and the second component includes an intermediate sealing portion, the intermediate sealing portion being located between the first sealing portion and the second sealing portion when the first component and the second component are interlocked.

[0029] The first and second sealing portions of the first component and the intermediate sealing portion of the second component together form a labyrinth seal, further reducing the intrusion of coating particles.

[0030] Advantageously, the joint of the component forms a groove on the outer surface of the housing, the groove being located in a plane. Preferably, this plane is orthogonal to the axial direction.

[0031] Therefore, any coating spillage will be located close to this plane, making visual inspection of spillage more reliable.

[0032] The housing may include a first edge extending outward from the outer edge of the recess at the root of the blade.

[0033] Therefore, the risk of coating overflow is reduced.

[0034] Optionally, the first edge may extend radially outward from the radially outer edge of the recess at the root of the blade.

[0035] The housing may include a second edge extending from the outer edge of the first edge toward the inner side of the housing.

[0036] Therefore, the risk of coating overflow is further reduced.

[0037] Optionally, the second edge may extend tangentially toward the inside of the housing from the radially outer edge of the first edge.

[0038] The present invention also relates to an assembly comprising a protective housing and a blade as described above, the blade having a root portion for mounting the blade in a slot in a rotor disk, the root portion extending axially from an upstream face to a downstream face and intended to be received in a recess in the root portion of the blade of the protective housing, such that a gap is maintained between the root portion of the blade and the wall of the housing forming the recess in the root portion of the blade.

[0039] Advantageously, the root of the blade is received in a recess in the root of the protective housing, particularly for coating operations, and a gap is maintained between the root of the blade and the wall of the housing that forms the recess in the root of the blade.

[0040] The present invention also relates to a method for coating blades, the blades being provided with a root portion for mounting the blades in a groove in a rotor disk, the root portion extending axially from an upstream surface to a downstream surface, the method comprising the following steps:

[0041] - The step of assembling multiple components around the root of the blade to form a protective shell, the components collectively forming a recess at the root of the blade, the recess being larger than the root of the blade, and the joints of the components all being axially formed between the upstream and downstream surfaces of the root of the blade; and

[0042] - The step of spraying the coating onto the blade.

[0043] Advantageously, the root of the blade is accommodated in a recess at the root of the blade, such that the blade is kept at a certain distance from the wall of the shell.

[0044] The method may include the step of checking whether there is coating overflow on the axial surface of the root of the blade after the coating is sprayed.

[0045] The axial surface of the root of the blade is the surface of the root of the blade that extends axially from the upstream surface of the root of the blade to the downstream surface. Attached Figure Description

[0046] Other objects, features, and advantages of the invention will become apparent from the following description, given only as a non-limiting example and with reference to the accompanying drawings, in which:

[0047] [ Figure 1 The blade is shown schematically;

[0048] [ Figure 2 The illustration schematically shows a housing housed according to a first exemplary embodiment of the invention. Figure 1 The base of the leaves;

[0049] [ Figure 3 ]Schematic illustration Figure 2 The joint of the shell;

[0050] [ Figure 4 The diagram schematically illustrates the joint of the housing according to a second exemplary embodiment of the present invention;

[0051] [ Figure 5 The illustration schematically shows a housing housed according to a third exemplary embodiment of the invention. Figure 1 The base of the leaves;

[0052] [ Figure 6 The illustration schematically shows a housing housed according to a fourth exemplary embodiment of the invention. Figure 1 The base of the leaves; and

[0053] [ Figure 7 The diagram schematically illustrates a method for coating blades according to an exemplary embodiment of the present invention. Detailed Implementation

[0054] Figure 1 Blade 2 is shown, here being a blade for an aircraft turbine, and more specifically a low-pressure turbine blade.

[0055] The blade 2 includes: a blade body 4, a root portion 6 capable of being mounted in a slot in the rotor disk of the turbine, a radially inner platform 8 between the blade body 4 and the root portion 6, and a crown 10, the crown including a radially outer platform and fins. The root portion 6 of the blade 2 includes: a spherical portion 12 that ensures a mechanical connection between the blade 2 and the rotor; and a shank portion 14 that extends between the spherical portion 12 and the radially inner platform 8.

[0056] The root 6 of the blade 2 includes an upstream surface 16 and a downstream surface 18, and the root 6 extends axially from the upstream surface 16 to the downstream surface 18.

[0057] The terms radial, axial, and tangential are defined relative to the axis of the turbine.

[0058] Figure 2 The root 6 of the blade 2 is shown, housed within a protective housing 20. During the coating operation, the housing 20 protects the root 6 of the blade 2 from the sprayed coating (e.g., a vapor-phase sprayed coating such as aluminum). The housing 20 comprises multiple components, including, herein, a first component 22 and a second component 24 assembled together.

[0059] The first component 22 is provided with a recess 26 in the first part of the root 6 of the blade 2.

[0060] The recess 26 of the first part of the root 6 of the blade 2 includes a recess in the first part of the bulbous part 12 and a recess in the first part of the stalk-like part 14. Here, the size of the recess 26 of the first part of the root 6 of the blade 2 is larger than the size of the upstream half of the root 6 of the blade 2.

[0061] The recess 26 of the first part of the root 6 of the blade 2 forms a cavity that opens radially outward and axially toward the downstream in the first component 22.

[0062] The second component 24 is provided with a recess 28 in the second part of the root 6 of the blade 2.

[0063] The recess 28 of the second part of the root 6 of the blade 2 includes a recess in the second part of the bulbous part 12 and a recess in the second part of the stalk-like part 14. The size of the recess 28 of the second part of the root 6 of the blade 2 is larger than the size of the downstream half of the root 6 of the blade 2.

[0064] The recess 28 of the second part of the root 6 of the blade 2 forms a cavity in the second component 24 that opens radially outward and axially towards the upstream.

[0065] During the assembly of the first component 22 and the second component 24, the recesses 26 and 28 of the first and second portions of the root 6 of the blade 2 engage to collectively form the recess 30 of the root 6 of the blade 2.

[0066] The size of the recess 30 at the root 6 of the blade 2 is larger than that at the root 6 of the blade 2, so that a gap is maintained between the root 6 of the blade 2 and the wall of the shell 20 that forms the recess 30 at the root 6 of the blade 2.

[0067] The assembled housing 20 includes an upstream portion 32, a downstream portion 34, and an intermediate portion 36 extending from the upstream portion 32 to the downstream portion 34.

[0068] The intermediate portion 36 is formed by a portion of the first component 22 and a portion of the second component 24. The upstream portion 32 is formed by a complementary portion of the portion of the first component 22. The downstream portion 34 is formed by a complementary portion of the portion of the second component 24.

[0069] The axial dimension of the intermediate portion 36 is equal to the axial dimension of the root 6 of the blade 2, which is taken as the distance from the upstream surface 16 to the downstream surface 18 of the root 6 of the blade 2. The intermediate portion 36 accommodates the root 6 of the blade 2 and extends axially from a first plane containing the upstream surface 16 of the root 6 of the blade 2 to a second plane containing the downstream surface 18 of the root 6 of the blade 2. The upstream portion 32 extends upstream of the intermediate portion 36. The downstream portion 34 extends downstream of the intermediate portion 36.

[0070] The first component 22 and the second component 24 are assembled such that the joint 38 of components 22 and 24 is entirely formed in the intermediate portion 36, while maintaining a certain distance from the axial end of the intermediate portion 36. Therefore, the joint 38 is entirely formed between a first plane containing the upstream surface 16 of the root of the blade 2 and a second plane containing the downstream surface 18 of the root of the blade 2, and more specifically between a first axial coordinate and a second axial coordinate, the first axial coordinate corresponding to a position at 40% of the axial dimension of the intermediate portion 36, and the second axial coordinate corresponding to a position at 60% of the axial dimension of the intermediate portion 36. The joint 38 thus formed reduces the risk of sediment overflow at the edge of the root of the blade 2, any overflow subsequently occurring approximately at the axial midpoint of the axial surface of the root 6 of the blade 2.

[0071] like Figure 3 As shown more clearly in the diagram, the first component 22 and the second component 24 are interlocked.

[0072] The second component 24 includes a shoulder 40. The first component 22 includes a first seal 42 that is radially abutting against a surface extending axially from the shoulder 40 and axially abutting against a surface extending radially from the shoulder 40. Therefore, the first seal 42 forms a barrier that prevents the flow of coating particles toward the blade 2 during the coating operation.

[0073] The first component 22 further includes a concave end 44, which is biased toward the inside of the housing 20 relative to the first sealing portion 42 and axially biased in the upstream direction relative to the first sealing portion 42. The second component 24 includes a convex end 46 at its upstream end, which is interlocking in the concave end 44 of the first component 22.

[0074] When the housing 20 is assembled, the joint 38 of the housing 20 is formed by the first sealing portion 42 and concave end portion 44 of the first component 22 and the shoulder portion 40 and convex end portion 46 of the second component 24.

[0075] refer to Figure 2 The joint 38 of the first component 22 and the second component 24 forms a groove 48 on the outer surface of the housing 20. The groove 48 is located in the same plane, which passes through the axial center of the root 6 of the blade 2.

[0076] exist Figure 2 and Figure 3 In the example shown, the recess 30 of the root 6 of the blade 2 is such that when the root 6 of the blade 2 is received in the housing 20, its radial outer edge is located radially between the radial outer surface and the radial inner surface of the radial inner platform 8.

[0077] Figure 4 The second exemplary embodiment shown is in conjunction with Figure 2 and Figure 3 The difference in the first exemplary embodiment shown is that the first component 22 includes a first sealing portion 42 and a second sealing portion 50 offset toward the inside of the housing 20 relative to the first sealing portion 42, wherein the same elements as those in the foregoing figures are given the same reference numerals. Here, the second component 24 includes an intermediate sealing portion 52, which is capable of being located between the first sealing portion 42 and the second sealing portion 50 of the first component.

[0078] When the housing 20 is assembled, the joint 38 of the housing 20 is formed by the first sealing part 42 and the second sealing part 50 of the first component 22 and the intermediate sealing part 52 of the second component 24, and the first sealing part, the second sealing part and the intermediate sealing part together form a labyrinth seal.

[0079] Figure 5 The third exemplary embodiment shown is in conjunction with Figure 2 and Figure 3 The difference in the first exemplary embodiment shown is that the housing 20 includes a first edge 54 extending radially outward from the radially outer edge of the recess 30 at the root 6 of the blade 2, wherein elements identical to those in the foregoing figures are designated by the same reference numerals. More specifically, the first component 22 includes a first portion of the first edge 54, and the second component 24 includes a second portion of the first edge 54.

[0080] The first edge 54 of the housing 20 is such that when the root 6 of the blade 2 is housed within the housing 20, its radially outer edge is radially offset outward relative to the radially outer surface of the radially inner platform 8. Therefore, the risk of coating overflow onto the root 6 of the blade 2 is further eliminated.

[0081] Figure 6 The fourth exemplary embodiment shown is in conjunction with Figure 5 The difference in the third exemplary embodiment shown is that the housing 20 includes a second edge 56 extending tangentially from the radially outer edge of the first edge 54 toward the inside of the housing, wherein elements identical to those in the foregoing figures are designated by the same reference numerals. More specifically, the first component 22 includes a first portion of the second edge 56 extending tangentially from the radially outer edge of the first portion of the first edge 54 toward the inside of the first component 22, and the second component 24 includes a second portion of the second edge 56 extending tangentially from the radially outer edge of the second portion of the first edge 54 toward the inside of the second component 24.

[0082] Figure 7 The method for coating blade 2 is illustrated schematically.

[0083] The method begins with assembly step 58, in which multiple components (here, first component 22 and second component 24) are assembled around the root 6 of blade 2 to form a protective housing 20. First component 22 is positioned upstream of the root 6 of blade 2, while second component 24 is positioned downstream of the root 6 of blade 2. Subsequently, first component 22 is axially guided downstream such that the upstream portion (here, the upstream half) of the root 6 of blade 2 is received in a recess 26 of the first portion of the root 6 of blade 2. Before, after, or simultaneously with guiding first component 22, second component 24 is axially guided upstream such that the downstream portion (here, the downstream half) of the root 6 of blade 2 is received in a recess 28 of the second portion of the root 6 of blade 2. Components 22 and 24 are interlocked such that a joint 38 is entirely axially formed between the upstream surface 16 and the downstream surface 18 of the root 6 of blade 2, and more specifically, such that the joint 38 is entirely formed between a first axial coordinate and a second axial coordinate.

[0084] Advantageously, the root 6 of the blade 2 is accommodated in the recess 30 of the root 6 of the blade 2 formed by the components 22 and 24, so that the blade 2 maintains a certain distance from the wall of the housing 20, that is, does not contact the housing 20.

[0085] Subsequently, step 60 is performed to spray the coating onto the blade 2.

[0086] Subsequently, components 22 and 24 are removed from housing 20 by guiding the first component 22 axially upstream and the second component 24 axially downstream.

[0087] Finally, inspection step 62 is preferably performed, particularly a visual inspection step, to confirm whether there is any coating overflow on the axial surface of the root 6 of the blade 2.

Claims

1. A protective housing (20) for receiving the root (6) of a blade (2) during a coating operation, the blade (2) having a root (6) for mounting the blade in a slot in a rotor disk, the root (6) extending axially from an upstream face (16) to a downstream face (18), the housing (20) comprising a plurality of components (22, 24) configured to be assembled and collectively form a recess (30) of the root (6) of the blade (2), the recess being larger than the root (6) of the blade (2), the assembled housing (20) comprising: Upstream section (32) Downstream portion (34), and The middle section (36), which extends from the upstream section (32) to the downstream section (34), has an axial dimension equal to the axial dimension of the root (6) of the blade (2) and is used to house the root (6) of the blade (2) during the coating operation. The feature is that the joint (38) of the components (22, 24) is formed entirely in the middle part (36) and is kept at a certain distance from the axial end of the middle part (36). The recess (30) of the root (6) of the blade (2) is larger in size than the root (6) of the blade (2) and can accommodate the root (6) of the blade (2) in the housing (20), so that a gap is maintained between the root (6) of the blade (2) and the wall of the housing (20) that forms the recess (30) of the root (6) of the blade (2).

2. The housing (20) according to claim 1, comprising: The first component (22) has a recess (26) in the first part of the root (6) of the blade (2). And a second component (24) having a recess (28) of the second part of the root (6) of the blade (2), the first component (22) and the second component (24) being configured to be assembled such that the recesses (26, 28) of the first part and the second part of the root (6) of the blade (2) together form the recess (30) of the root (6) of the blade (2).

3. The housing (20) according to claim 2, wherein, The first component (22) and the second component (24) are assembled by interlocking.

4. The housing (20) according to claim 3, wherein, The first component (22) includes a first sealing portion (42) and a second sealing portion (50), the first sealing portion (42) being offset toward the outside of the housing (20) relative to the second sealing portion (50), and the second component (24) including an intermediate sealing portion (52), the intermediate sealing portion being located between the first sealing portion (42) and the second sealing portion (50) when the first component (22) and the second component (24) are interlocked.

5. The housing (20) according to any one of claims 1 to 4, wherein, The joint (38) of the components (22, 24) forms a groove (48) on the outer surface of the housing (20), the groove (48) being located in a plane.

6. The housing (20) according to any one of claims 1 to 5, comprising: The first edge (54) extends outward from the outer edge of the recess (30) at the root (6) of the leaf (2).

7. The housing (20) according to claim 6, comprising: The second edge (56) extends from the outer edge of the first edge (54) toward the inside of the shell.

8. A component, the component comprising: According to any one of claims 1 to 7, the protective housing (20) and the blade (2) are provided with a root (6) for mounting the blade in a groove in a rotor disk, the root (6) extending axially from an upstream face (16) to a downstream face (18) and for receiving in a recess (30) of the root (6) of the blade (2) of the protective housing (20), such that a gap is maintained between the root (6) of the blade (2) and the wall of the housing (20) forming the recess (30) of the root (6) of the blade (2).

9. The component according to claim 8, wherein, The root (6) of the blade (2) is accommodated in the recess (30) of the root (6) of the blade (2) of the protective housing (20), especially for coating operations, a gap is maintained between the root (6) of the blade (2) and the wall of the housing (20) that forms the recess (30) of the root (6) of the blade (2).

10. A method for coating a blade (2), the blade being provided with a root (6) for mounting the blade in a groove in a rotor disk, the root (6) extending axially from an upstream face (16) to a downstream face (18), characterized in that, The method includes the following steps: Step (58) of assembling multiple components (22, 24) around the root (6) of the blade (2) to form a protective shell (20), the assembled shell (20) including an upstream portion (32), a downstream portion (34) and an intermediate portion (36), the intermediate portion extending from the upstream portion (32) to the downstream portion (34) and having an axial dimension equal to the axial dimension of the root (6) of the blade (2), the components (22, 24) collectively forming a recess (30) of the root (6) of the blade (2), the recess being larger than the root (6) of the blade (2), the root (6) of the blade (2) The recess (30) of 6) is larger in size than the root (6) of the blade (2) and is able to accommodate the root (6) of the blade (2) in the housing (20) such that: a gap is maintained between the root (6) of the blade (2) and the wall of the housing (20) forming the recess (30) of the root (6) of the blade (2); the joint (38) of the components (22, 24) is entirely formed in the intermediate portion, while maintaining a certain distance from the axial end of the intermediate portion (36), and is axially located between the upstream surface (16) and the downstream surface (18) of the root (6) of the blade (2); and Step (60) of spraying the coating onto the blade (2).

11. The method according to claim 10, wherein, The root (6) of the blade (2) is accommodated in the recess (30) of the root (6) of the blade (2) such that a gap is maintained between the root (6) of the blade (2) and the wall of the shell (20) forming the recess (30) of the root (6) of the blade (2).

12. The method according to claim 10 or 11, comprising: Step (62) is to check whether there is coating overflow on the axial surface of the root (6) of the blade (2) after spraying the coating.

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