Method of manufacturing a blade for a turbine engine

Abstract

The invention relates to a method for manufacturing a blade (2) for a turbine engine comprising a root (6) connected to a wheel blade (4) extending in a longitudinal direction, the method comprising the steps of: - providing an assembly (10) comprising: o a first part (12) intended to form the root (6) of the blade (2); o a second part (14) protruding in extension from the first part (12) in the longitudinal direction; - providing a mold comprising a first mold cavity (50) and a second mold cavity (52), the first and second mold cavities together delimiting a cavity (58), the cavity (58) comprising a first space (64) and a second space (66); - arranging the first part (12) in the first space (64) of the cavity (58) and the second part (14) in the second space (66) of the cavity (58); - injecting an aluminum-based alloy, the alloy forming a third part (16).

Description

Technical Field

[0001] The present invention relates to a method for manufacturing blades for turbine engines, the blades comprising a root made of a titanium-based alloy, the root being connected to an aluminum-based impeller. Background Technology

[0002] A novel turbine engine architecture is sought to meet aerospace requirements. This novel architecture necessitates the use of a compressor capable of withstanding high rotational speeds. This architectural change generates additional or new stresses, which must be considered when manufacturing the compressor's rotor and stator blades.

[0003] The quality of the rotating blades is particularly challenging. Conventionally, it is known to manufacture blades comprising a root and a whorl, using titanium to provide a certain mechanical strength to the assembly. However, blades made of titanium alloys impose high centrifugal forces, specifically on the disk supporting the blades, thus necessitating the search for low-density material solutions.

[0004] Using alloys such as aluminum to reduce blade density is not without consequences. For example... Figure 1 As shown, the current method for welding a blade 4 made of an aluminum-based alloy to a root 6 made of a titanium-based alloy results in only loading the connection region 8 between the root 6 and the blade 4. Due to the properties of the two materials to be joined, performing this weld using conventional welding methods is extremely difficult or even impossible. This is because titanium and aluminum have very different melting points, and this weld subsequently causes the formation of a fragile intermetallic phase in the connection region 8. Even if welding were still possible, the connection region 8 containing the fragile intermetallic phase, forming a surface-to-surface interface between the blade 4 and the root 6, is at risk of fracture because all the forces between the blade 4 and the root 6 are concentrated on the fragile connection region 8. This risk of fracture is particularly high at high turbine engine rotational speeds.

[0005] If other assembly methods such as brazing or riveting are used, the problem remains similar. This is because, in such cases, punctures in the connection area 8 cause mechanical stress to concentrate in this connection area 8, which may lead to cracks. Summary of the Invention

[0006] The present invention relates to a method for manufacturing blades for a turbine engine, the turbine engine comprising a root connected to a blade extending in a longitudinal direction, the method comprising the following steps:

[0007] - Provide an assembly comprising:

[0008] The first part, which is specifically formed at the root of the blade, is produced from a titanium-based alloy.

[0009] ○ The second part extends protrudingly from the first part in the longitudinal direction;

[0010] - Provide a mold including a first mold cavity and a second mold cavity, the first mold cavity and the second mold cavity together defining a cavity in which the blade is to be formed, the cavity including a first space to be formed of the blade and a second space to be formed of the root;

[0011] - The first part is arranged in the first space of the cavity and the second part is arranged in the second space of the cavity;

[0012] - An aluminum-based alloy is injected, which forms a third part, into which the second part is embedded.

[0013] In this way, the third part of the blade, made of an aluminum-based alloy injected into the mold, is embedded into the second part, thus ensuring optimal radial retention of the third part at the blade root. The connection between the blade and the root is therefore no longer an issue: the second part provides mechanical assembly and attachment between the root and the blade. It should be understood that the second and third parts together form the blade.

[0014] The first part is made of a titanium-based alloy with a melting point between 1600°C and 1700°C, and the second part is made of an aluminum-based alloy with a melting point between 500°C and 600°C. This difference in the melting points of aluminum and titanium limits the interaction between the third part on one side and the first and second parts on the other side, and thus limits the formation of the fragile phase.

[0015] The assembly can be produced using additive manufacturing.

[0016] The second part may include a generally U-shaped portion comprising a first arm and a second arm connected by a top portion.

[0017] The second part, by its shape, hardens the blade when it is not sufficiently hard. This second part, therefore, includes components for adjusting the hardness of the blade by its shape.

[0018] The first arm and / or the second arm may include a protrusion.

[0019] The protrusion provides a large specific surface area, thereby providing effective anchoring between the first and third parts.

[0020] The protrusion may include protrusions extending laterally toward the interior of the general U-shape and / or protrusions extending laterally toward the exterior of the general U-shape.

[0021] The second part may include at least one internal air circulation loop capable of receiving hot air from outside the blades.

[0022] The second part's internal air circulation loop thus heats the impeller blades and therefore prevents ice buildup.

[0023] The internal air circulation loop may include an air outlet that appears on the outer surface of the third part.

[0024] This internal air circulation loop also improves the aerodynamics of the impeller and removes the restrictive layer that circulates near the first part and near the outer surface of the third part forming the rear edge. Attached Figure Description

[0025] [ Figure 1 [A schematic diagram of turbine engine blades is shown;]

[0026] [ Figure 2 It shows:

[0027] -exist Figure 2 A is a schematic diagram of a first embodiment of the assembly comprising a first part and a second part according to the present invention;

[0028] -exist Figure 2 In Figure B, a schematic diagram of a first embodiment of a turbine engine blade as seen from the front according to the present invention;

[0029] -exist Figure 2 C is a schematic diagram of a first embodiment of a turbine engine blade as seen from the side according to the present invention;

[0030] [ Figure 3 [A schematic diagram of a second embodiment of a turbine engine blade including an air circulation loop according to the present invention is shown;]

[0031] [ Figure 4 [A schematic diagram of a third embodiment of a turbine engine blade including an air circulation loop according to the present invention is shown;]

[0032] [ Figure 5 A schematic diagram of a mold according to the present invention is shown; Detailed Implementation

[0033] The present invention relates to a blade 2 comprising a root 6 made of a titanium-based alloy, the titanium-based alloy being compatible with the material of the disk (or collar) for supporting the root 6 of the blade 2.

[0034] This compatibility makes it possible to envision, for example, direct assembly between the longitudinally extending blade 2 and the disk (or collar) via friction welding. The blade 2 also includes a wheel blade 4 made of aluminum alloy.

[0035] Figure 2A schematic diagram of a first embodiment of a turbine engine blade 2 according to the present invention is shown. More precisely, Figure 2 A shows a schematic diagram of assembly 10 including first part 12 and second part 14. Figure 2 B is a schematic diagram of turbine engine blade 2 as seen from the front, and Figure 2 C is a schematic diagram of the turbine blade 2 as seen from the side.

[0036] like Figure 2 As shown, the second portion 14 includes a generally U-shaped form adapted to extend from the first portion 12 in the longitudinal direction at a longitudinal dimension between 20% and 90% of the blade's longitudinal dimension. This second portion 14 is intended to form the blade's impeller together with the third portion 16. This second portion 14 includes a first arm 18 and a second arm 20 connected to each other via a top portion 22. The first arm 18 and the second arm 20 each include ends 24a, 24b on a side opposite to the top portion 22. These ends 24a, 24b of the first arm 18 and the second arm 20 are each connected to the first portion 12. One or the other, or both, of the first arm 18 and the second arm 20 include protrusions 26. These protrusions 26 include protrusions extending laterally into the interior 26a of the generally U-shaped form and / or protrusions extending laterally toward the exterior 26b of the generally U-shaped form. These protrusions 26 form attachment areas including surface conditions that optimize attachment to the third portion 16.

[0037] The first part 12 is intended to form the root 6 of the blade 2. The first part 12 may have an initial shape that differs from the final shape of the root 6 of the blade 2. This first part 12 of the preform to which the root can be formed can therefore be processed to match the desired final shape of the root 6 of the blade 2.

[0038] according to Figure 3 The second embodiment shown, similar to the first embodiment, includes a first portion 12, a second portion 14, and a third portion 16 for the blade 2. In this embodiment, the second portion 14 includes an internal air circulation loop 28. This internal air circulation loop 28 includes a first section 30 having an end 32 that appears outside the first portion 12 on the side opposite to the blade 4. This internal circulation loop 28 also includes a second section 34 having a generally U-shape that passes through the second portion 14, and a third section 36 that is continuously connected to the second section 34 and appears outside the first portion on the side opposite to the blade.

[0039] according to Figure 4The third specific embodiment shown, similar to the first embodiment, includes a first portion 12, a second portion 14, and a third portion 16 in the blade 2. In this third embodiment, the internal air circulation loop 28 begins with a first arm 18 at an end opposite the top portion 22. This end opposite the top portion 22 includes a first region 38 adjacent to the first portion 12 and a second region 40 appearing on the exterior of the blade 2. This second region 40 may include a single region or multiple regions appearing on the exterior of the blade at a dimension between 0% and 80% of the longitudinal dimension of the third portion. The second arm 20 of the second portion 14 is free, i.e., not connected to the first portion 12, and includes air outlets 42 appearing on the outer surface of the third portion 16. These air outlets 42 may, for example, be three in number, but this number of air outlets is not limiting, and there may be a single air outlet or multiple air outlets.

[0040] like Figure 5 As shown, this blade 2 is manufactured using mold 44. The blade 2 to be manufactured ultimately matches the geometry of mold 44. Mold 44 includes at least a first housing 46 and a second housing 48, which are arranged one against the other to form mold 44. The first housing 46 includes a first internal surface forming a first mold cavity 50. The second housing 48 includes a second internal surface forming a second mold cavity 52. ​​When the first housing 46 and the second housing 48 are assembled one against the other, the first mold cavity 50 and the second mold cavity 52 together form a cavity 58 in which the blade is to be formed.

[0041] The first mold cavity 50 and the second mold cavity 52 each include first regions 60a and 60b and second regions 62a and 62b. The first region 60a of the first mold cavity 50 and the first region 60b of the second mold cavity 52 together define a first space 64 of the cavity 58, which is intended to form a blade. The second region 62a of the first mold cavity 50 and the second region 62b of the second mold cavity 52 together define a second space 66 of the cavity 58, which is intended to receive a first portion 12 of the blade 2. The first space 64 and the second space 66 of the cavity 58 together form the internal cavity 58 of the mold 44, which is intended to receive a second portion 14 of the blade 2.

[0042] The first housing 46 includes a first internal channel 54, a first end of which appears at a first portion 64 of a cavity 58, and a second end of which appears outside the mold 44. The second housing 48 includes a second internal channel 56, a first end of which appears at a second portion 66 of a cavity 58, and a second end of which appears outside the mold 44.

[0043] The first space 64 of cavity 58 defines the area into which liquid metal is injected to form the third portion of the blade. The second space 66 of cavity 58 can also specifically receive the root of the blade, preferably manufactured by additive manufacturing.

[0044] According to the invention, a first portion 12 is arranged in a second space 66 of cavity 58, and a second portion 14 is arranged in a first space 64 of cavity 58. An aluminum-based alloy is injected to form a third portion 16 and embed it into the second portion 14, the second portion being subsequently surrounded by the third portion. The second portion 14 and the third portion 16 thus form the blade 4 of blade 2.

[0045] It should be understood that the second portion 14 ensures the attachment of the third portion 16 to the second portion 14, thus forming an attachment member between the root of the portion forming the aluminum alloy blade 2 and the third portion 16. This is because the shape of the second portion 14, and specifically the protrusion, produces a large specific surface area, thereby providing effective anchoring between the second portion 14 and the third portion 16. The shape of the second portion provides radial mechanical retention, and the surface condition optimizes attachment in the lateral direction by increasing the specific surface area. This surface condition also compensates for shrinkage associated with the curing of the third portion around the U-shape.

[0046] When the blade is not sufficiently hardened, the second part 14 further hardens the blade through its shape. This second part 14 thus forms a component for adjusting the hardness of the blade through its arrangement and configuration.

[0047] The second part's internal air circulation loop 28 can heat the blades and thus avoid ice buildup caused by air circulation within the blades' internal structure. This internal air circulation loop 28 also improves the aerodynamics of the blades 4 and removes the restrictive layer that circulates near the outer surface of the third part forming the trailing edge.

[0048] The first part 12 is advantageously made of a titanium-based alloy having a melting point between 1600°C and 1700°C, and the second part is made of an aluminum-based alloy having a melting point between 500°C and 600°C. This difference in the melting points of aluminum and titanium limits the interaction between the third part 16 on one side and the first part 12 and the second part 14 on the other side, and thus limits the formation of the fragile phase.

[0049] The first part 12 and the second part can be obtained by means of additive manufacturing methods. In this way, the second part 14 can have any shape and shape suitable for attaching the third part 16 to the second part 14.

Claims

1. A method for manufacturing a blade (2) for a turbine engine, said turbine engine comprising a root (6) connected to a wheel blade (4) extending in a longitudinal direction, said method comprising the steps of: - providing an assembly (10) comprising: o a first part (12) intended to form a root (6) of the blade (2), this first part (12) being produced from a titanium-based alloy, o a second part (14) protruding in the longitudinal direction from the first part (12); - providing a mold comprising a first mold cavity (50) and a second mold cavity (52), said first and second mold cavities together delimiting a cavity (58) in which the blade is intended to be formed, said cavity (58) comprising a first space (64) intended to form the wheel blade and a second space (66) intended to form the root (6); - arranging the first part (12) in the first space (64) of the cavity (58) and the second part (14) in the second space (66) of the cavity (58); - injecting an aluminum-based alloy, this alloy forming a third part (16) in which the second part (14) is embedded, wherein the second part comprises a substantially U shape comprising a first arm (18) and a second arm (20) connected by a top part (22).

2. The method for manufacturing a blade for a turbine engine of claim 1, wherein, The assembly (10) is produced by additive manufacturing.

3. The method for manufacturing a blade for a turbine engine of claim 1, wherein, The first arm (18) and / or the second arm (20) comprise a protrusion (26).

4. The method for manufacturing a blade for a turbine engine of claim 3, wherein, The protrusion (26) comprises a protrusion extending transversely towards an inside (26a) of the substantially U shape and / or a protrusion extending transversely towards an outside (26b) of the substantially U shape.

5. The method for manufacturing a blade for a turbine engine of claim 1, wherein, The second part (14) comprises at least one internal air circulation circuit (28) capable of receiving hot air from outside the blade (2).

6. The method for manufacturing a blade for a turbine engine of claim 5, wherein, The internal air circulation circuit (28) comprises an air outlet (42) emerging on an outer surface of the third part (16).

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