METAL BLADE FOR AN AIRCRAFT TURBOMACHINE AND ITS MANUFACTURING PROCESS

Abstract

Metallic blade (8, 50) for an aircraft turbomachine (1), said blade (8, 50) comprising: - a metallic body having at least one aerodynamic blade (14, 55) having an internal ventilation cavity (20, 60), this cavity (20, 60) extending along an axis of elongation of the blade (55) and opening at a longitudinal end of the blade or the body, to form an opening (30, 70) on a surface (32, 81) of this end, - at least one metallic plate (40, 80) fixed by brazing or welding to said surface (32, 81) and configured to at least partially close said opening (30, 70), characterized in that the body includes centering pins (90) which project from said surface (30, 70) and whose function is to cooperate with a peripheral edge of the plate (40, 80) in order to center it on the surface (32, 81) during its fixing. Figure for the abbreviation: Figure 9

Description

Title of the invention: METAL BLADE FOR AN AIRCRAFT TURBOMACHINE AND ITS MANUFACTURING METHOD Technical field of the invention

[0001] The present invention relates to a metallic blade for an aircraft turbomachine and to a method for manufacturing this blade. Technical background

[0002] An aircraft turbomachine, such as a turbojet, typically comprises, from upstream to downstream in the direction of gas flow, a movable fan rotating about a longitudinal axis, a low-pressure compressor, a high-pressure compressor, a combustion chamber, a high-pressure turbine, a low-pressure turbine and a combustion gas exhaust nozzle.

[0003] The blower allows the intake of an airflow that splits into a primary flow and a secondary flow. The primary flow passes through a primary channel of the turbomachine while the secondary flow is directed towards a secondary channel surrounding the primary channel.

[0004] The primary flow is compressed within the compressors. The compressed air is then mixed with fuel and burned within the combustion chamber. The combustion gases pass through the turbines and then escape through the nozzle, the cross-section of which allows these gases to be accelerated to generate propulsion.

[0005] Turbines are typically equipped with several stages, each comprising rotor blades and stator blades.

[0006] In the present application, a blade is a part comprising at least one aerodynamic blade intended to extend in a gas flow. The blade typically comprises an intrados face and an extrados face connected by a leading edge and a trailing edge.

[0007] Turbine blades are located downstream of the combustion chamber and are subjected to high temperatures during operation. These blades are typically made of metallic material but cannot be subjected to temperatures exceeding the limits to which their metallic material can withstand.

[0008] In this context, it has already been proposed to equip the blades with a ventilation system in order to increase the temperature range in which these blades can be used. The ventilation system comprises a ventilation circuit arranged inside the blade and allowing the passage of air from the compressors into the blade. The ventilation circuit includes at least one internal cavity formed during the manufacturing of the blades. Each internal cavity is delimited by the internal wall of the blade.

[0009] The internal cavity of the blade extends along an axis of blade elongation and opens at a longitudinal end of the blade, generally forming an opening. This opening can be chosen to supply air to the cavity, or to exhaust air from this cavity.

[0010] This opening may also result from the method of manufacturing the blade. In the case of manufacturing a blade using the lost-wax casting technique, for example, the opening may be used to remove a ceramic core intended to define the internal cavity of the blade during molding.

[0011] It is known to close this type of opening, partially or totally, by means of a plate which is attached to the surface of the body having the opening, and which is fixed to this surface by brazing or welding.

[0012] In the case where this opening includes a peripheral shoulder, or a peripheral recess, the plate can be shaped to fit the shape of this shoulder or recess, which allows it to be automatically centered on the surface before it is fixed.

[0013] However, such a shoulder or indentation is not always present on the surface and in particular is not always feasible during the manufacture of the blade.

[0014] On a blade lacking such a shoulder or recess, there is therefore a risk of incorrect positioning of the insert and thus of misalignment of the insert relative to the opening intended to be covered by the insert. This can lead to leaks if the insert is to completely seal the opening, or an excessive airflow if the insert is to partially seal the opening in order to define a predetermined air passage cross-section with the opening.

[0015] The present invention proposes a solution to at least some of the problems mentioned below. Summary of the invention

[0016] The invention relates to a metallic blade for an aircraft turbomachine, this blade comprising:

[0017] - a metallic body comprising at least one aerodynamic blade comprising a internal ventilation cavity, this cavity extending along an axis of elongation of the blade and opening at a longitudinal end of the blade or body, to form an opening on a surface of that end,

[0018] - at least one metal plate fixed by brazing or welding to said surface and configured to at least partially close said opening,

[0019] characterized in that the body includes centering pins which are projecting on said surface and which have the function of cooperating with a peripheral edge of the plate in order to center it on the surface when it is fixed.

[0020] The invention thus proposes to provide protruding pins directly on the surface of the body for centering the insert before brazing or welding. These pins may have no other function and may remain permanently on the blade.

[0021] The blade according to the invention may comprise one or more of the following features, taken individually or in combination with each other:

[0022] - the number of centering pins is greater than or equal to 3;

[0023] - the centering pins are formed in one piece with the body and are by example formed by machining the body;

[0024] - the centering pins are distributed around the opening;

[0025] - the centering pins have a general parallelepiped shape;

[0026] - each of the centering pins has a length that extends along the edge peripheral area of ​​the platelet, which represents less than 5% of the perimeter of this platelet;

[0027] - each of the centering pins has a thickness less than or equal to that of the plaque;

[0028] - the centering pins have identical shapes and / or dimensions.

[0029] The present invention also relates to a method for manufacturing a blade as described above, characterized in that it comprises the following steps:

[0030] a) the manufacture of a metallic body comprising an aerodynamic blade having an internal ventilation cavity, this cavity extending along an axis of elongation of the blade and opening at a longitudinal end of the blade or the body, to form an opening on a surface of this end, the body comprising centering pins which are projecting on said surface,

[0031] b) the positioning of a metal plate on said surface to at least partially close said opening, this plate having a peripheral edge which cooperates with the centering pins in order to center the plate on the surface, and

[0032] c) fixing the plate to the surface by brazing or surface.

[0033] Advantageously, in step a), the centering pins are made by machining the body. Brief description of the figures

[0034] Other features and advantages will become apparent from the following description of a non-limiting embodiment of the invention with reference to the accompanying drawings in which:

[0035] [Fig.1] [Fig.1] is a schematic half-view in cross-section of an aircraft turbomachine,

[0036] [Fig.2] [Fig.2] is a schematic perspective view of a rotor blade for an aircraft turbomachine turbine,

[0037] [Fig.3] [Fig.3] is a very schematic cross-sectional view of the rotor blade of [Fig.2],

[0038] [Fig.4] [Fig.4] is a partial schematic perspective view of one foot of the rotor blade of [Fig.2],

[0039] [Fig.5] [Fig.5] is a schematic perspective view of a stator blade for an aircraft turbomachine turbine,

[0040] [Fig.6] [Fig.6] is a schematic cross-sectional view of one of the stator blades of [Fig.5],

[0041] [Fig.7] [Fig.7] is another schematic perspective view of the stator blade of [Fig.5],

[0042] [Fig.8] [Fig.8] is a larger scale view of part of [Fig.7];

[0043] [Fig.9] [Fig.9] is a view similar to that of [Fig.7] and illustrates a mode of realization of the invention, and

[0044] [Fig. 10] the [Fig. 10] a larger scale view of part of the [Fig.9]. Detailed description of the invention

[0045] An example of an aircraft turbomachine 1 is shown in [Fig. 1]. The turbomachine 1 extends around and along a longitudinal axis X.

[0046] In the present application, the terms "upstream" and "downstream" are defined with respect to the direction of gas flow in the turbomachine 1 along the longitudinal axis X.

[0047] The terms "axial", "axially", "radial", "radially", "longitudinal", "longitudinally", are defined with respect to the longitudinal axis X of the turbomachine 1.

[0048] The terms "internal", "interior", "external", "outside", "externally" are defined with respect to the distance of the longitudinal axis X of the turbomachine 1 along a radial axis.

[0049] The turbomachine 1 comprises, from upstream to downstream, a blower 2, at least one compressor such as a low-pressure compressor 3 and a high-pressure compressor 4, a combustion chamber 5, at least one turbine such as a high-pressure turbine 6 and a low-pressure turbine 7, and a nozzle (not shown).

[0050] The blower 2 allows the intake of an airflow F which divides into a primary airflow Fl and a secondary airflow F2. The primary airflow Fl passes through a primary channel of the turbomachine 1 while the secondary airflow F2 is directed towards a secondary channel surrounding the primary channel.

[0051] The primary airflow Fl is compressed within the low pressure compressor 3 and then the high pressure compressor 4. The compressed air is then mixed with a fuel and burned within the combustion chamber 5. The gases formed by the combustion pass through the high pressure turbine 6 and low pressure turbine 7. The gases finally escape through the nozzle whose cross-section allows the acceleration of these gases to generate propulsion.

[0052] The fan 2 is, for example, shrouded. It is surrounded by an annular casing 2b centered on the longitudinal axis X. The casing 2b is, for example, surrounded by a nacelle (not shown) of the turbomachine 1.

[0053] With reference to [Fig. 2], the high-pressure turbine 6 comprises rotor blades 8 extending radially from a disk (not shown) that rotates about the longitudinal axis X. Each blade 8 extends along an elongation axis Y between a head 10 and a foot 12 mounted in the disk to retain the blade 8 on the disk. The elongation axis Y of the blade 8 extends radially about the longitudinal axis X of the turbomachine 1 when the blade 8 is mounted in the turbomachine 1.

[0054] Each blade 8 comprises a blade 14 extending along the Y-axis between the tip 10 and the foot 12. The blade 14 comprises an outer wall 16 and an inner wall 18 located inside the outer wall 16. The outer wall 16 has an aerodynamic shape and comprises an intrados face 16i and an extrados face 16e connected by a leading edge 16a and a trailing edge 16b.

[0055] The blade 8 is made of metallic material.

[0056] In order to improve the temperature resistance of the blades 8, each blade 8 includes a ventilation system. With reference to [Fig. 3], the ventilation system includes at least one internal cavity 20 for the circulation of a ventilation airflow F3. Advantageously, a plurality of internal cavities 20 are provided in the blade 8.

[0057] Each internal cavity 20 is located inside the blade 8 and advantageously extends along the elongation axis Y between the head 10 and the foot 12 of the blade 8. Each internal cavity 20 is delimited or defined by the internal wall 18 of the blade 8.

[0058] The ventilation airflow F3 is for example taken from the low pressure compressor 4 and is routed to the internal cavities 20.

[0059] In order to further improve the temperature resistance of the blades 8, the ventilation system further includes at least one first air outlet 22 provided in the external wall 16 ([Fig.2]).

[0060] At least one of the internal cavities 20 opens at a longitudinal end of the blade 8, and for example at the foot 12 to form an opening 30 as illustrated in [Fig.4].

[0061] This opening 30 is partially or completely closed by a metal plate 40 which is attached to the surface 32 of the foot 12 onto which the opening 30 opens and which is fixed to this surface 32 by brazing or welding. In the case shown, a recess 34 made in the surface 32, all around the opening 30, allows the plate to be received and correctly positioned before being fixed. However, this recess 34 is not always present or possible to make.

[0062] Reference is now made to figures 5 to 8 which represent a stator blade 50, of the distributor type, for an aircraft turbomachine turbine.

[0063] The blade 50 comprises coaxial annular platforms, respectively internal 53 and external 54, which delimit between them the annular gas flow channel in the turbine and between which radially extend blades 55 ([Fig.5]).

[0064] Figure 6 illustrates a cross-sectional view of one of the distributor blades 55 50 equipped with a ventilation sleeve 56. The distributor blade 55 50 comprises an internal cavity 60 in which a perforated tubular sleeve 56 is mounted, allowing ventilation air to circulate from a supply chamber radially external to the external platform 54 of the distributor. This air passes partly through perforations in the sleeve 56, impacts the internal wall of the blade 55 for ventilation, and is then discharged into the turbine gas flow stream through perforations 61 in the blade 55. The ventilation air is drawn upstream from a compressor of the turbomachine and conveyed to the supply chamber via ducts not shown. The radially external end of the sleeve 56 is open for air supply, and its radially internal end can be opened, as in Figure 6.

[0065] As can also be seen in figures 5 to 8, the sleeves 56 are inserted into the internal cavities 60 of the blades 55 by means of openings 70 formed in the external platform 54 and opening into the cavities 60. After mounting the sleeves 56, the openings 70 are partially closed by plates 80 which are attached to surfaces 81 of the platform 54 and which are fixed to these surfaces 81 by welding or brazing.

[0066] Unlike [Fig.4], the mounting surfaces 81 of the plates 80 are flat, so the operator who positions the plates 80 must take the greatest possible care to position the plates 80 correctly. A misalignment of a plate 80 with respect to the opening 70 could, for example, cause an unintentional leak Q which would lead to a malfunction of the ventilation system of the blade 50 ([Fig.8]).

[0067] The present invention thus proposes a solution which can be applied to a rotor blade 8 or stator blade 50 as described above.

[0068] The following description relates to a stator blade 50, such as that illustrated in Figures 9 and 10, but it is understood that the invention also applies to a rotor blade 8 which would not include, for example, a recess 34 as illustrated in [Fig. 4],

[0069] As mentioned above, the blade 50 comprises a metallic body having an aerodynamic blade 55 having an internal ventilation cavity 60. This cavity 60 extends along an axis of elongation of the blade 55 and opens at a longitudinal end of the blade 55 or of the body, to form an opening 70 on a surface 81 of this end, as mentioned above.

[0070] The blade 50 also includes at least one metal plate 80 fixed by brazing or welding to the surface 81 and configured to at least partially close the aforementioned opening 70.

[0071] According to the invention, the body includes centering pins 90 which are projecting on the surface 81 and which have the function of cooperating with a peripheral edge of the plate 80 in order to center it on the surface 81 when it is fixed.

[0072] Advantageously, the number of centering pins 90 is greater than or equal to 3.

[0073] The centering pins 90 are preferably formed in one piece with the body and are, for example, formed by machining the body.

[0074] The centering pins 90 are preferably distributed around the opening 70.

[0075] In the example shown, the centering pins 90 have a general parallelepiped shape.

[0076] To limit the amount of material added by the pins 90, each of the centering pins 90 has a length L which extends along the peripheral edge of the plate 90, which represents less than 5% of the perimeter of this plate.

[0077] Each of the centering pins 90 can have a thickness E less than or equal to that of the plate 80.

[0078] The centering pins 90 may have identical shapes and / or dimensions.

[0079] The present invention also relates to a method for manufacturing a blade 50, characterized in that it comprises the following steps:

[0080] a) the manufacture of a metallic body comprising an aerodynamic blade 55 having an internal ventilation cavity 60, this cavity 60 extending along an axis of elongation of the blade 55 and opening at a longitudinal end of the blade 55 or of the body, to form an opening 70 on a surface 81 of this end, the body comprising centering pins 90 which are projecting on this surface 81,

[0081] b) the positioning of a metal plate 80 on the surface 81 to at least partially close the opening 70, this plate 80 having a peripheral edge which

[0082]

[0083] cooperates with the centering pins 90 in order to center the insert 80 on the surface 81, and c) the fixing of the insert 80 to the surface by brazing or surface. In step a), the centering pins 90 are preferably made by machining the body.

Claims

Demands

1. A metallic blade (8, 50) for an aircraft turbomachine (1), said blade (8, 50) comprising: - a metallic body having at least one aerodynamic blade (14, 55) having an internal ventilation cavity (20, 60), this cavity (20, 60) extending along an axis of length of the blade (55) and opening at a longitudinal end of the blade or the body, to form an opening (30, 70) on a surface (32, 81) of this end, - at least one metallic plate (40, 80) fixed by brazing or welding to said surface (32, 81) and configured to at least partially close said opening (30, 70), characterized in that the body comprises centering pins (90) which project from said surface (30, 70) and whose function is to cooperate with an edge peripheral of the plate (40, 80) in order to center it on the surface (32, 81) during its fixing.

2. Blade (8, 50) according to claim 1, wherein the number of centering pins (90) is greater than or equal to 3.

3. Blade (8, 50) according to claim 1 or 2, wherein the centering pins (90) are formed in one piece with the body and are for example formed by machining the body.

4. Blade (8, 50) according to any one of the preceding claims, wherein the centering pins (90) are distributed around the opening (30, 70).

5. Blade (8, 50) according to any one of the preceding claims, wherein the centering pins (90) have a general parallelepiped shape.

6. Blade (8, 50) according to any one of the preceding claims, wherein each of the centering pins (90) has a length (L) which extends along the peripheral edge of the plate (40, 80), which represents less than 5% of the perimeter of this plate.

7. Blade (8, 50) according to any one of the preceding claims, wherein each of the centering pins (90) has a thickness less than or equal to that of the plate (40, 80).

8. Blade (8, 50) according to any one of the preceding claims, wherein the centering pins (90) have identical shapes and / or dimensions.

9.

10. A method for manufacturing a blade (8, 50) according to any one of the preceding claims, characterized in that it comprises the following steps: a) the manufacture of a metallic body comprising an aerodynamic blade (55) having an internal ventilation cavity (20, 60), this cavity (20, 60) extending along an axis of elongation of the blade (55) and opening at a longitudinal end of the blade (55) or of the body, to form an opening (30, 70) on a surface (32, 81) of this end, the body comprising centering pins (90) which project from said surface (32, 81), b) the positioning of a metal plate (40, 80) on said surface to at least partially close said opening (32, 81), this plate (40, 80) having a peripheral edge which cooperates with the centering pins (90) in order to center the plate (40, 80) on the surface (32, 81), and c) fixing the plate to the surface by brazing or surface. Method according to claim 9, wherein, in step a), the centering pins (90) are made by machining the body.

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