FR3107720A1 - TURBINE AUBE, PROCESS FOR MANUFACTURING OR RECONDITIONING THE TALON DE LADITE AUBE - Google Patents

Abstract

The invention relates to a turbine blade comprising a heel (30) positioned at a radially outer end, said heel (30) comprising a platform ( 31) having a first side flank (32) and a second side flank (33) opposed, a wear plate (36, 38) covering at least 80% of the surface of at least one side flank of the first and second side flanks (32, 33). Figure to be published with the abstract: 4

Description

TURBINE BLADE, METHOD FOR MANUFACTURING OR RECONDITIONING THE TALON OF SAID BLADE

TECHNICAL FIELD OF THE INVENTION

The invention relates to the general field of turbomachines.

The invention relates more particularly to a turbine blade comprising a heel whose lateral flanks are provided with an anti-wear material. Furthermore, the invention relates to a process for manufacturing or reconditioning said heel.

TECHNOLOGICAL BACKGROUND OF THE INVENTION

Aeronautical turbomachines conventionally comprise several modules such as a low pressure compressor, a high pressure compressor, a combustion chamber, a high pressure turbine followed by a low pressure turbine, which drive the corresponding low pressure or high pressure compressor, and a gas exhaust system. The turbine, high or low pressure, is made up of a succession of axial stages arranged one behind the other, each comprising a wheel of moving blades, called a rotor, and a wheel of fixed blades, called a distributor.

In the present description, upstream and downstream are defined with respect to the normal flow direction of the gas (from upstream to downstream) through the turbine. The term “axis of the turbomachine” refers to the axis of rotation of the rotor of the turbomachine. The axial direction corresponds to the direction of the axis of the turbomachine and a radial direction is a direction perpendicular to the axis of the turbomachine and intersecting this axis. In addition, the adjectives "internal" and "external", "interior" and "exterior" are used with reference to a radial direction so that the internal part of an element is, in a radial direction, closer to the axis of the turbomachine as the external part of the same element.

Figure 1 is a perspective view of a moving blade of a turbine rotor.

Referring to Figure 1, the moving blade 10 comprises a blade 8 extending radially between a radially inner end and a radially outer end. At its radially inner end, the moving blade 10 comprises a foot 4 by which it is fixed to a disk of the rotor, this disk being common to several moving blades 10. At its radially outer end, the moving blade 10 comprises an element transverse, called heel 6.

Figure 2 is a top view of the heel 6 of the moving blade 10 illustrated in Figure 1.

As can be seen in Figure 2, the heel 6 comprises a platform 18 externally delimiting the flow path of the gas circulating between the blades 8 of the moving blades 10. The platform 18 is delimited by first and second lateral flanks 16, 20 opposite, respectively on the intrados side and on the extrados side of the moving blade 10. In addition, the platform comprises upstream 12 and downstream 14 sealing wipers extending radially outwards from the external face of the platform 18.

Each of the first and second lateral flanks 16, 20 of the platform 18 has, between the upstream 12 and downstream 14 wipers, a substantially "Z" profile with a first portion 16A, 20A, close to the upstream wiper 12, a second portion intermediate 16B, 20B and a third portion 16C, 20C close to the downstream wiper 14. The first portions 16A, 20A and the third portions 16C, 20C are substantially parallel to each other and the second portion 16B, 20B extends obliquely between the first and third portions 16A, 20A and 16C, 20C.

Figure 3 is a top view of the heels 6 of three adjacent blades 10.

As can be seen in FIG. 3, when several moving blades 10 are fixed to the disc of the rotor, the first and second lateral flanks 16, 20 of the heels 6 are arranged end to end so as to form a circumferential ring which has in particular the function of which is to externally delimit the gas flow path passing through the turbine and thus to limit gas leaks at this location.

During operation or shutdown of the turbine, the moving blades 10 of each rotor are in contact with each other via the first and second lateral flanks 16, 20, in particular along the second portions 16B, 20B of the lateral flanks 16, 20. The second portions 16B, 20B therefore define the inter-blade contact surfaces and are the site of significant friction, in particular during operation of the turbine.

In order to protect the beads 6 against wear, the second portions 16B, 20B are covered with a layer 22, 24 of friction-resistant anti-wear material. The anti-wear material is generally a steel alloy with a high chromium and cobalt content, marketed under the brand name Stellite®. Conventionally, this anti-wear material is deposited on the second portions 16B, 20B by welding.

However, the deposition by welding of the anti-wear material on the second portions 16B, 20B of the side flanks 16, 20 is a complex operation. Indeed, insofar as the anti-wear material is in liquid form during the deposition, the deposition must be carried out manually. However, it is difficult to deposit the anti-wear material only on the second portions 16B, 20B, i.e. without overflowing from these portions. Also, it is necessary, after the deposition of the anti-wear material, to proceed with the machining of the lateral flanks 16, 20 and of the upper surface of the heel 6 and in certain cases, to also carry out manual touch-ups so as to get the desired result.

In addition, it has been observed that any cracks appear after the drops of Stellite® have been deposited on the heels 6, which leads to the scrapping of certain moving blades 10. These cracks are explained by a thermal gradient that is too high between the temperature of the blade 10 and the temperature of the drops of anti-wear material.

Furthermore, the friction between the lateral flanks 16, 20 of the heels 6 during the operation of the turbine causes the wear or even the loss of the layer 22, 24 of anti-wear material which leads to poor positioning of the heels 6, to a deterioration of the lateral flanks 16, 20 and to a loss of contact between the heels 6. Thus, the heels 6 of the moving blades 10 are regularly reconditioned. During the reconditioning operation, the wear-resistant material is removed, generally by local milling, then redeposited on the lateral flanks 16, 20 of the heels 6 by drop or laser welding. However, for the same reasons as those mentioned above, the deposition of the anti-wear material by drop or laser welding can lead to the formation of cracks on the heel and in the anti-wear material, which leads to the scrapping of the moving blades 10.

The invention offers a solution to the problems mentioned above, by proposing a turbine blade whose heel is more resistant to friction and which is easier to manufacture and/or to recondition.

A first aspect of the invention relates to a turbine blade comprising a heel positioned at a radially outer end, said heel comprising a platform having a first lateral flank and a second opposite lateral flank, an anti-wear plate covering at least 80% of the area of at least one lateral flank among the first and second lateral flanks.

By "wear pad" is meant a one-piece insert which is formed from wear-resistant material as opposed to wear-resistant material deposited drop by drop on the sidewalls so as to form a "reconstituted" layer of wear-resistant material.

Thanks to the anti-wear plate, the blade stub is easier to manufacture and recondition. Indeed, a few spot welds are enough to fix the anti-wear plate on the lateral side of the heel. In addition, it is no longer necessary to carry out a machining operation or manual retouching on the heel, which saves considerable time during manufacturing or reconditioning. Similarly, when reconditioning the heel, removing the anti-wear plate is easy and quick to perform because the anti-wear plate is only connected to the heel by a few spot welds.

In addition, the local residual thermal stresses during the welding of the wear-resistant material on the side flanks are reduced. In fact, insofar as a few spot welds are sufficient to fix the anti-wear plate on a lateral side of the heel, there is less risk of seeing cracks appear in the anti-wear material or in the heel during the manufacture or reconditioning of the heel.

Moreover, insofar as the anti-wear plate is manufactured before its attachment to the lateral side of the bead, the thickness of anti-wear material is always optimal.

Thus, the use of the anti-wear plate makes it possible to greatly reduce the number of scrap parts and therefore to considerably reduce the manufacturing and reconditioning costs of the blade stubs.

In addition to the characteristics which have just been mentioned in the previous paragraph, the turbine blade according to the first aspect of the invention may have one or more additional characteristics among the following, considered individually or according to all technically possible combinations.

According to a non-limiting embodiment, the anti-wear pad entirely covers said at least one lateral flank.

According to a non-limiting embodiment, the anti-wear plate is fixed to said at least one lateral flank by spot welds.

According to a non-limiting embodiment, the heel platform comprises an upstream wiper and a downstream wiper, each of the first and second lateral flanks of the platform having, between the upstream wiper and the downstream wiper, a substantially Z-shaped profile.

According to a non-limiting embodiment, the anti-wear plate is made from a cobalt-based material.

According to a non-limiting embodiment, the anti-wear plate has a thickness of between 0.08 and 2 mm.

According to a non-limiting embodiment, the turbine blade is a moving blade of a low pressure turbine.

A second aspect of the invention relates to a turbomachine comprising a turbine comprising at least one turbine blade according to the first aspect of the invention.

A third aspect of the invention relates to a method for manufacturing or reconditioning the heel of the blade according to the first aspect, comprising a step of fixing the anti-wear plate to said at least one lateral flank among the first and second side flanks of the heel by welding points.

In addition to the characteristics that have just been mentioned in the previous paragraph, the manufacturing or reconditioning process according to the third aspect of the invention may have one or more additional characteristics among the following, considered individually or in all technically possible combinations.

According to a non-limiting embodiment, the manufacturing or reconditioning method comprises a step of manufacturing the anti-wear plate by cutting and stamping a sheet.

The invention and its various applications will be better understood on reading the following description and examining the accompanying figures.

BRIEF DESCRIPTION OF FIGURES

The figures are presented for information only and in no way limit the invention.

is a perspective view of an example of a turbine blade according to the prior art.

is a top view of the root of the blade shown in Figure 1.

is a top view of the heels of three adjacent moving blades according to the prior art.

is a top view of the heels of three adjacent moving blades, according to one embodiment of the invention.

is a side view of one of the heels shown in Figure 4.

is a sectional view along the line CC visible in Figure 4.

is a sectional view along the line DD visible in Figure 4.

DETAILED DESCRIPTION

Unless specified otherwise, the same element appearing in different figures has a single reference.

Conventionally, a turbomachine comprises, from upstream to downstream in the direction of flow of the gas flow, a fan, one or more compressor stages, for example a low-pressure compressor and a high-pressure compressor, a combustion chamber , one or more turbine stages, for example a high pressure turbine and a low pressure turbine, and a gas exhaust nozzle.

Each turbine, i.e. low and high pressure, consists of a succession of axial stages arranged one behind the other. Each stage comprises a wheel of moving blades forming the rotor and a wheel of fixed blades forming the distributor. The mobile wheel is set in rotation vis-à-vis the corresponding distributor.

The invention relates to a turbine blade, preferably a moving turbine blade, comprising a heel.

In the remainder of the description, it will be assumed that the blade according to the invention is a mobile turbine rotor blade.

It is recalled that a moving blade comprises a blade extending radially between a radially outer end and a radially inner end. At its radially inner end, the moving blade comprises a foot by which the moving blade is attached to a disc of the rotor (not shown) of the turbine which rotates around the axis of the turbomachine. At its radially outer end, the mobile blade comprises a heel. When several moving blades are fixed to the rotor disk, their heels are arranged side by side so as to form a rotating circumferential ring delimiting a surface of revolution around the axis of rotation of the disk.

FIG. 4 is a top view of the stubs 30 of three adjacent moving blades, according to one embodiment of the invention.

For reasons of clarity, the references in FIG. 4 have only been indicated for one of the three heels 30.

Referring to Figure 4, each heel 30 comprises a platform 31 externally delimiting the flow path of the gas circulating between the blades 37 of the rotor. The platform 31 has a first lateral flank 32 and a second lateral flank 33 opposite located, respectively, on the intrados side and on the extrados side of the moving blade, as well as an upstream edge 26 and a downstream edge 28.

In addition, the platform 31 of the heel 30 comprises an upstream sealing wiper 34 and a downstream sealing wiper 35 extending radially outwards from the outer face of the platform 31. When the moving blades are fixed on the disk of the rotor, the upstream 34 or downstream 35 wipers of the moving blades are arranged side by side so as to form a rotating ring. Such a ring has the particular function of limiting the play existing between the moving blades and the casing, which surrounds them, in order to limit gas leaks at this location.

Furthermore, each of the first and second lateral flanks 32, 33 of the platform 31 has, between the upstream 34 and downstream 35 wipers, a substantially "Z" profile, with a first portion 32A, 33A, close to the upstream wiper 34 , a second intermediate portion 32B, 33B, and a third portion 32C, 33C, close to the downstream wiper 35. In particular, the first 32A, 33A and third portions 32C, 33C are substantially parallel to each other and the second portion 32B, 33B extends obliquely between the first 32A, 33A and third portions 32C, 33C. In a variant embodiment not illustrated, each first and second lateral flanks 32, 33 of the platform 31 has, between the upstream 34 and downstream 35 wipers, a profile other than that illustrated, for example substantially V, U or S .

To be protected against wear, the surfaces of the first lateral flank 32 and the second lateral flank 33 are covered, respectively, with a first anti-wear plate 36 and a second anti-wear plate 38 made of an anti-wear material. - wear, i.e. resistant to friction. In particular, the first and second anti-wear pads 36, 38 cover at least 80% of the surface of the first and second lateral flanks 32, 33, preferably between 90 and 100%.

Figure 5a is a side view of one of the heels 30 shown in Figure 4.

As can be seen in Figure 5a, the first anti-wear plate 36 has a shape and dimensions substantially identical to the shape and dimensions of the first lateral flank 32 of the heel 30 so that the first anti-wear plate 36 covers completely the first lateral flank 32. Naturally, the second lateral flank 33 which is not visible in FIG. 5a is also completely covered with a second anti-wear plate 38 whose shape and dimensions are substantially identical to the shape and to the dimensions of the second lateral flank 33. The anti-wear pads 36, 38 preferably have a thickness e of between 0.08 and 2 mm. Advantageously, the anti-wear material is a cobalt-based alloy, such as and in a non-limiting manner the alloys known under the following names: HA 188, MAR-M-509, HS25.

FIG. 5b is a sectional view along the line C-C of FIG. 4 which illustrates the interface between the lateral flanks 32, 33 of two adjacent heels 30, at the level of the second portions 32B, 33B of the lateral flanks 32, 33. FIG. 5c is a sectional view along the line D-D of FIG. 4 which illustrates the interface between the lateral flanks 32, 33 of the three heels 30, at the level of an upstream part of the heels 30. As can be seen in the Figures 5b and 5c, the contact between the anti-wear plates 36, 38 takes place only at the level of the second portions 32B, 33B.

The invention also relates to a method of manufacturing or reconditioning the heel 30 of the moving blade.

In a first step, the first and second anti-wear pads 36, 38 are manufactured. Advantageously, the manufacturing step is carried out by cutting and stamping a sheet, preferably made from a cobalt-based material.

In a second step, the first anti-wear plate 36 and the second anti-wear plate 38 are fixed, respectively, on the first lateral flank 32 and on the second lateral flank 33 of the heel 30 by spot welds 39. Advantageously, the welding material is for example based on cobalt. This is a manual operation because the welding material is in liquid form when deposited. According to the embodiment of FIG. 4, seven spot welds 39 are deposited on each of the side flanks 32, 33 of the heel 30 and are distributed identically over all the side flanks 32, 33. In particular, a spot weld 39 is arranged on the second portion 32B, 33B, three weld points 39 are distributed between the upstream edge 26 of the platform 31 and the upstream wiper 34 and the other three weld points 39 are distributed between the downstream wiper 35 and the edge downstream 28 of the platform 31.

Naturally, the invention is not limited to the various embodiments which have been described, and variant embodiments are possible.

Claims (9)

Turbine blade comprising a heel (30) positioned at a radially outer end, said heel (30) comprising a platform (31) having a first lateral flank (32) and a second lateral flank (33) opposed, characterized in that an anti-wear plate (36, 38) covers at least 80% of the surface of at least one lateral flank among the first and second lateral flanks (32, 33). Turbine blade according to the preceding claim, characterized in that the anti-wear plate (36, 38) is fixed to said at least one lateral flank by spot welds (39). Turbine blade according to any one of the preceding claims, characterized in that the platform (31) of the heel (30) comprises an upstream wiper (34) and a downstream wiper (35), each of the lateral flanks (32, 33) of the platform (31) having, between the upstream wiper (34) and the downstream wiper (35), a substantially Z-shaped profile. Turbine blade according to any one of the preceding claims, characterized in that the anti-wear plate (36, 38) is made from a cobalt-based material. Turbine blade according to any one of the preceding claims, characterized in that the anti-wear plate (36, 38) has a thickness (e) of between 0.08 and 2 mm. Turbine blade according to any one of the preceding claims, characterized in that the said blade is a moving low-pressure turbine blade. Turbomachine comprising a turbine, characterized in that said turbine comprises at least one blade according to any one of the preceding claims. Process for manufacturing or reconditioning the turbine blade according to any one of Claims 1 to 6, characterized in that it comprises a step of fixing an anti-wear plate (36, 38) on at least one lateral flank among the first and second lateral flanks (32, 33) of the heel (30) by spot welding. Manufacturing or reconditioning method according to the preceding claim, characterized in that it includes a step of manufacturing the anti-wear plate (36, 38) by cutting and stamping sheet metal.