FR3121706A1 - FLASHING TABS FOR TURBOMACHINE ROTOR BLADE FOOT - Google Patents

Abstract

TONGUE STICKERS One aspect of the invention relates to a shim designed to be mounted on a blade root (21) of a blade (2) of a turbomachine rotor (3) comprising: - a base (11), - a first and a second lateral branches (12c, 12d) interconnected by the base (11) and spaced from each other, the two lateral branches (12c, 12d) comprise at least a first lateral tab (14c ) and a second side tab (14d) each comprising a fold end from which each extends from an edge of a surface of the corresponding side branch (12c, 12d), the side tabs (14c, 14d) possibly be folded towards each other while being spaced from each other and each able to be in contact with a surface of a radial edge (23) of the foot (21) of the moving blade (2) forming a axial abutment in at least one axial direction of the shim (1) in the blade root (21). Figure to be published with abstract: Figure 1

Description

FLASHING TABS FOR TURBOMACHINE ROTOR BLADE FOOT

TECHNICAL FIELD OF THE INVENTION

The technical field of the invention is that of turbine blades.

The present invention relates to a shim for a moving blade of a turbine engine, a turbine blade and an assembly comprising a moving blade whose root is provided with said shim. The invention also relates to a turbomachine.

TECHNOLOGICAL BACKGROUND OF THE INVENTION

Conventionally, an axial turbine of a turbomachine consists of a succession of axial stages (along the axis of circulation of the gas flows) arranged one behind the other. Each stage comprises a moving wheel with blades forming the rotor and bladed distributors forming the stator. The mobile wheel is set in rotation vis-à-vis the corresponding distributor.

The moving wheel is conventionally made up of an annular disc centered on the axis of rotation of the wheel, comprising cells and a plurality of moving blades each comprising an attachment member called in the following a blade root in a dedicated cell-shaped housing.

In the contact zones between the root of each moving blade and the cell housing this root, several types of stresses are exerted.

One encounters in particular "fretting", i.e. contact wear, which is the consequence of the repetitive friction of one part on another, the resulting friction forces being able to cause damage to the material by various fatigue process. This phenomenon is particularly sensitive in the case of contact between two parts, for example metal or CMC.

These zones are therefore subject to a significant tendency to damage the material, as well as to wear of the bearing surfaces of the blade root which are the zones in contact with the wall of the cell, or even a deformation of these zones of contact.

In addition, the level of local stresses is very high due to the coefficient of friction at the interface between the walls in contact with the root of the blade and the cell, formed by a metal/metal contact. In the following, this interface is called the blade root span and the slot span.

To solve these problems, the aim is in particular to reinforce the resistance to wear of the surfaces in contact and to reduce the coefficient of friction.

To do this, generally a protective part is used which can be a consumable, formed of one or more metal foils fitting the foot of the blade.

With this type of solution, we manage to reduce the coefficient of friction and we can change the foil instead of a whole blade.

For example, document EP2042689A1 proposes using an assembly with a metal foil between a blade root and a disc.

On the turbine blades, foils are placed between the blade roots and the cells of the discs to prevent wear of these parts. These guarantee the mechanical integrity of the parts with which they are in contact.

In the shims of the prior art, these are held in position on the blade roots by two bent tabs projecting from the base of the shim located at the bottom of the blade root.

However, these tabs are not sufficient to hold the shim in position on the blade root. Indeed, during the operation of the turbine, it was observed in certain situations of possible axial displacements of the foils.

The disengagement of the foils no longer ensures the mechanical integrity of the blade root and the turbine disk. This axial disengagement of the shim therefore causes at least a portion of the blade root without protection and therefore premature wear of the blade root in place of the shim produced by "fretting".

The invention offers a solution to the problems mentioned above, by allowing the foils not to disengage from the blade roots and to ensure the mechanical integrity of the blade root and the turbine disc.

• une base,
• une première et une deuxième branches latérales reliées entre elles par la base et distantes l'une de l'autre,
• un premier et un deuxième bord latéral s'étendant sur la base et les branches,

la première et deuxième branches latérales comprennent respectivement une première languette latérale et une deuxième languette latérale s’étendant chacune à partir d’un bord latéral, les languettes latérales pouvant être rabattues l’une vers l’autre en étant distantes l'une de l'autre et pouvant chacune coopérer avec le pied d’aube, en étant en contact avec une surface radiale du pied d’aube, pour former un maintien axial dans au moins un sens axial du clinquant par rapport au pied d'aube.A first aspect of the invention relates to a shim intended to be mounted on a blade root of a blade of a turbomachine rotor comprising:

• a base,
• a first and a second lateral branches interconnected by the base and spaced from each other,
• a first and a second lateral edge extending over the base and the branches,

the first and second lateral branches respectively comprise a first lateral tongue and a second lateral tongue each extending from a lateral edge, the lateral tongues being able to be folded towards one another while being spaced apart from one another each other and can each cooperate with the blade root, being in contact with a radial surface of the blade root, to form an axial retention in at least one axial direction of the shim relative to the blade root.

Thus the side tabs allow the shim not to disengage from the blade root. The side tabs reinforce the positioning of the shim in relation to the blade root in a simple way, without modifying the blade root. In addition, the fact that the side tabs are spaced from each other when they are folded towards each other prevents them from overlapping. This thus avoids causing an axial extra thickness and/or avoiding complicated handling of the tabs when bending the tabs against the radial surface of the blade root.

By "the tabs that can be folded towards each other" is meant that they are each folded towards each other at the level of the first lateral edge to allow the foot to be retained. Thus, the foil can be inserted around the foot on the side of the first lateral edge by having the tabs extending longitudinally, then they are then folded towards each other until they are in contact with the radial surface of the foot to form the axial support.

In addition to the characteristics which have just been mentioned in the previous paragraph, the foil according to one aspect of the invention may have one or more additional characteristics from among those mentioned in the following paragraphs, considered individually or in all technically possible combinations:

According to one embodiment, each tab comprises a single ply.

According to one embodiment, the side tabs each comprise a ply end connected to the first side edge at the corresponding side branch, characterized in that the sum of the lengths measured between the ply end and the free end of the first and of the second lateral tab is less than the distance between the two ply ends. Thus the assembly of the foil is facilitated. There is no folding order of the tabs on the foil or cooperation between the two side tabs.

According to one embodiment, each side tongue comprises a fold end connected to the first side edge at the level of the corresponding side branch and a free end opposite the folded end, the free end being distant from another tongue or from the side edge from which it extends when the tabs are folded down. This avoids overlapping and that each tongue can be in contact with a radial surface of the foot.

According to one embodiment, the side tabs extend from a flat surface of the side branch. This allows the tab to be folded down easily since the fold is linear and not curved. This allows the tab when bent to be perpendicular to the flat surface.

According to an example of this embodiment, the flat surface contiguous to the end of the bend of a tongue can be a bearing surface of the blade root.

According to another example of this embodiment, the flat surface contiguous to the bend end of a tab can be a surface comprising a longitudinal edge of a side branch.

According to one embodiment, the foil comprises two pairs of side tabs, each pair forming the first and the second side tabs and in that the side tabs of the first pair extend from the first side edge and the side tabs from the other pair extend from the second side edge. Thus, the pairs of lateral tongues form an abutment in the two axial directions of the shim with respect to the blade root.

According to one embodiment, the shim comprises a central tab projecting from one of the side edges at the level of the base of the shim, and able to cooperate with the radial surface of the blade root while being in contact to ensure axial retention in at least one axial direction of the shim in the blade root.

According to one embodiment, the shim comprises on each side branch a longitudinal edge, the side tabs are located between the base and the corresponding longitudinal edge and remote therefrom.

According to one embodiment, the side tabs are obtained by stamping.

According to one embodiment, the thickness of the side branches and of the base are identical, the foil is in one piece and is made from the same material. The side tabs therefore have the same thickness as the base and are made from the same material.

According to one embodiment, the foil is a deformed plate.

• une aube comprenant
  • une plateforme interne,
  • une pale s'étendant radialement de la plateforme et
  • un pied d'aube s'étendant radialement de cette plateforme à l'opposé de la pale, le pied d'aube comprenant une première et une deuxième face radiale et deux faces longitudinales latérales rejoignant chaque face radiale, au moins un flanc sur chaque face longitudinale latérale destiné à former une portée contre une surface d'un logement du pied d'aube ;
• le clinquant selon le premier aspect de l’invention avec ou sans les différentes caractéristiques des modes de réalisations décrits précédemment, le clinquant étant monté sur le pied de l'aube mobile telle qu'au moins les deux languettes latérales sont chacune rabattue et en contact contre la surface d’une des deux faces radiales du pied d'aube.

A second aspect of the invention relates to an assembly for a turbomachine rotor comprising:

• a dawn comprising
  • an internal platform,
  • a blade extending radially from the platform and
  • a blade root extending radially from this platform opposite the blade, the blade root comprising a first and a second radial face and two lateral longitudinal faces joining each radial face, at least one flank on each face longitudinal side intended to form a seat against a surface of a housing of the blade root;
• the shim according to the first aspect of the invention with or without the different characteristics of the embodiments described previously, the shim being mounted on the root of the moving blade such that at least the two lateral tabs are each folded down and in contact against the surface of one of the two radial faces of the blade root.

• un disque comprenant une pluralité d’alvéoles et
• au moins un ensemble selon le deuxième aspect de l’invention, dans lequel le pied et le clinquant sont montés dans une des alvéoles.

A third aspect of the invention relates to a rotor of a turbomachine comprising:

• a disc comprising a plurality of cells and
• at least one assembly according to the second aspect of the invention, in which the foot and the shim are mounted in one of the cells.

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 a foil according to one embodiment of the invention

is a front view of an assembly according to one embodiment of the invention including the foil shown in the surrounding a dawn foot.

is a perspective view of a portion of a turbomachine rotor comprising the assembly shown in the inserted into a cavity of a rotor disk.

DETAILED DESCRIPTION

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

The invention relates to a shim for a root of a moving blade of a turbine engine as well as to an assembly for a rotor of a turbomachine comprising a moving blade having its root inserted in such a shim and finally the rotor comprising a rotor disk comprising cells and at least one blade root inserted in the cell.

There shows a representation of a foil 1 according to one embodiment of the invention.

The shim 1 comprising a base 11 as well as a first and a second lateral branches 12c, 12d connected to each other via the intermediary of the base 11. The shim 1 comprises a first and a second lateral edges 15a, 15b extending over the base 11 and over the side branches 12c, 12d, forming the opposite ends of the foil 1 longitudinally. The foil 1 also includes at the end of its side branches 12c, 12d a longitudinal edge 16c, 16d connecting the two side edges 15a, 15b.

The two side branches 12c, 12d comprise at least a first side tongue 14c and a second side tongue 14d each comprising a fold end 140c, 140d each of which extends from one of the side edges 15a, 15b, in this case in this example of each side edge 15a, 15b (of which only one tongue of the pair of tongues extending from the side edge 15b is visible on the ).

The shim 1 therefore comprises in this example, two pairs of lateral tongues 14c, 14d, one pair of which comprises the first and the second lateral tongues 14c, 14d which each extend from a first lateral edge 15a and the other pair comprises a first and a second lateral tabs which each extend from the second lateral edge 15b. In other words the first and the second lateral branches 12c, 12d comprise a lateral tongue 14c, 14d of each pair of tongues.

On the the tabs 14c, 14d are shown folded without surrounding the blade root shown below on the , but before the shim 1 is inserted around the blade root 21, at least one of the two pairs comprises side tabs 14c, 14d which are not folded.

In this example, the side tabs 14c, 14d each project perpendicularly from a flat surface of the corresponding side branch 12c, 12d. The side tabs 14c, 14d are located between the base 11 and a longitudinal edge 16c, 16d and remote therefrom.

Advantageously, the side tabs 14c, 14d are obtained by stamping.

The side tabs 14c, 14d are made from the same material as the foil 1. Advantageously, the material of the foil 1 is a deformed plate.

Advantageously, the thickness of the side tabs 14c, 14d are identical to the radial thickness of the shim 1.

In this example, the side tabs 14c, 14d are rectangular in shape but may have another shape.

Each side tongue 14c, 14d comprises a free end 141c, 141d, opposite the folded end 140c, 140d, and two edges connecting the free end 141c, 141d to the folded end 140c, 140d

One end of a tab is said to be free when it is distant from the other tabs and from the side edge 15a, 15b when the tabs 14c, 14d are folded down to be in contact with a face of a foot as can be seen in the figures.

The side tabs 14c, 14d each include a length measured between the fold end 140c, 140d and the free end 141c, 141d of the tab 14c, 14d opposite the fold end 140c, 140d. This length is determined so as not to overlap another tongue or exceed the side edge 15a, 15b.

In other words, each tongue 14c, 14d includes its free end 141c, 141d remote from another tongue or from the corresponding side edge 15a, 15b.

Advantageously, the sum of the length of the first and of the second lateral tabs 14c, 14d is less than the distance between the two ends of folds 140c, 140d of a pair of lateral tabs 14c, 14d.

In this example, the tabs 14c, 14d extend in the direction of the base 11.

In addition, in this embodiment, the shim 1 has two central tabs 17, only one of which is visible in the figures, projecting from the base 11 at the level of the first and second side edges 15a, 15b. The shim 1 may according to another embodiment comprise only one central tab 17 or none.

Each central tab 17 has a free end 170 opposite its folded end contiguous to the base 11 remote from the free ends of the side tabs 14c, 14d. Identically to the side tongues 14c, 14d extending at least from one of the two sides of the side edge 15a, 15b, a central tongue 17 extends longitudinally from the base 11 to insert the shim 1 around the foot 21 and then this central tab 17 is folded against one face of the foot 21.

There is a view of an assembly 100 comprising the shim 1 surrounding a blade root 21 to protect it.

There is a perspective view of a portion of a turbomachine rotor 10 comprising the assembly 100 shown in the , inserted in a cell 31 of a disc 3 of the rotor 10.

The blade 2 comprises a blade (not visible) extending radially between a radially outer end and a radially inner end. At its radially outer end, the moving blade 2 comprises a heel (not shown). At its radially internal end, the moving blade 2 comprises an internal platform (not shown) extended internally by the blade root 21 by which it is fixed to a rotor disk 3 visible on the . The blade root 21 comprises a first radial face 23 and a second radial face on either side longitudinally of the root 21 and two lateral longitudinal faces joining each radial face 23, at least one flank on each lateral longitudinal face intended to form a bearing against a surface of a blade root housing 21.

The blade root 21 of the mobile blade 2 is in the shape of a dovetail.

The foot 21 comprises a base portion 21l comprising the spans and a restricted portion 21h extending between the internal platform and the base portion 21l. Dotted lines on the represent the border between the restricted part 21h and the base portion 21l. The base portion 21l flares out from the restricted portion 21h by widening to form the staves then thins out to an inner surface 27 to be opposite the bottom of the cell 31 of the disc 3.

With reference to the , the blade root 21 of the moving blade 2 is engaged in a cell 31 formed in the outer periphery of the disc 3 and held radially in the cell 31 by shape cooperation between the blade root 21 and the cell 31.

When the rotor disk 3 rotates, the moving blades 2 are subjected to centrifugal forces and the bearing surfaces of the feet 21 come into abutment against the bearing surfaces of the cells 31 of the disk, via the shim 1.

In order to limit the wear of the feet 21, the shim 1 is positioned at the contact interface between the feet 21 and the cells 31 of the disc 3.

In this example, each lateral longitudinal face of a foot 2 comprises in the restricted portion 21h a flat surface 28c, 28d extending from the base portion 21l. In addition, in this example, the restricted portion 21h comprises a surface flaring out towards the internal platform visible on the .

The shim 1 comprises a complementary shape with the foot 22. In particular, the shim 1 surrounds the base portion 21l of the foot 21 and at least partially the restricted portion 21h of the foot 21.

The base 11 of the shim 1 covers the lower surface 27 of the foot 21 and the first side branch 12c and the second side branch 12d cover the lateral longitudinal faces of the foot 21.

In this example, the shim 1 comprises on each side branch 12c, 12d, a flat surface 18 surrounding part of the flat surface 28c, 28d of the restricted portion.

The lateral tongues 14c, 14d of a pair form abutments which bear against the corresponding radial face 23 of the blade root 21 so as to block in at least one direction the axial translation of the shim 1 in the blade root. 21.

Advantageously, in this example, the two pairs of lateral tabs 14c, 14d make it possible to block in both directions the axial translation of the shim 1 in the blade root 21.

The surface of the side branch 12c, 12d contiguous to the bend end of the side tabs 14c, 14d are in contact with a bearing surface of the blade root 21.

In other words, in this example each lateral tab 14c, 14d forms an axial abutment against the radial face 23 at the level of the base portion 21l.

According to another example not shown, each surface of the side branch 12c, 12d contiguous to the bend end of each side tab 14c, 14d of a pair, extend so as to surround the flat surface 28c, 28d of the restricted portion 9 p.m. In other words, in this example the bend end of each side tongue 14c, 14d of a pair extends from a surface of the corresponding side branch 12c, 12d surrounding the restricted portion 21h. The pair of lateral tongues 14c, 14d form abutments against the radial face 23 at the level of the restricted portion 21h.

According to another example not shown, a pair of tongues cooperates with the radial face 23 at the level of the restricted portion 21h to form an axial retention of the shim 1 with respect to the blade root 21 and the other pair of lateral tongues cooperates with the other radial face 23 at the level of the base portion 21l to form an axial retention of the shim 1 with respect to the blade root 21 in the other axial direction.

According to another example not shown, a pair of tongues comprises a lateral tongue 14c against the radial face 23 at the level of the restricted portion 21h and the other lateral tongue 14d at the level of the base portion 21l.

The central tongues 17 form abutments which bear axially against the radial faces 23 at the level of the base portion 21l of the blade root 21 so as to block the relative movements between the blade root 21 and the shim 1.

Claims (10)

Foil (1) intended to be mounted on a blade root (21) of a blade (2) of a turbomachine rotor (3) comprising:

• a base (11),
• a first and a second lateral branches (12c, 12d) interconnected by the base (11) and spaced from each other,
• a first side edge (15a) and a second side edge (15b) opposite each extending over the base (11) and the branches (12c, 12d),

characterized in that the first and second lateral branches (12c, 12d) respectively comprise a first lateral tongue (14c) and a second lateral tongue (14d) each extending from the first lateral edge (15a), the lateral tongues ( 14c, 14d) that can be folded towards each other while being spaced from each other and that can each cooperate with the blade root (21), being in contact with a radial surface (23) of the blade root (21), to form axial support in at least one axial direction of the shim (1) relative to the blade root (21). Foil (1) according to the preceding claim, the lateral tongues (14c, 14d) each comprise a fold end (140c, 140d) connected to the first lateral edge (15a) at the level of the corresponding lateral branch (12c, 12d), characterized in that the sum of the lengths measured between the ply end (140c, 140d) and a free end (141c, 141d) of the first and second side tabs (14c, 14d) is less than the distance between the two ply ends (12c, 12d). Foil (1) according to any one of the preceding claims, characterized in that the lateral tabs (14c, 14d) extend from a flat surface of the lateral branch (12c, 12d). Foil (1) according to any one of the preceding claims, in which the foil comprises two pairs of side tabs (14c, 14d), each pair forming the first and second side tabs (14c, 14d) and in that the tabs side tabs (14c, 14d) of the first pair extend from the first side edge (15a) and the side tabs (14c, 14d) of the other pair extend from the second side edge (15b). Foil (1) according to the preceding claim, characterized in that it comprises a central tab (17) projecting from one of the lateral edges (15a, 15b) at the level of the base (11) of the foil (1), and capable of cooperating with the radial surface (23) of the blade root (21) to ensure the maintenance in at least one axial direction of the shim (1) relative to the blade root (21). Foil (1) according to any one of the preceding claims, characterized in that it comprises on each lateral branch (12c, 12d) a longitudinal edge (16c, 16d), the lateral tabs (14c, 14d) are located between the base (11) and the longitudinal edge (16c, 16d) corresponding and remote therefrom. Foil (1) according to any one of the preceding claims, characterized in that the lateral tabs (14c, 14d) are obtained by stamping. Foil (1) according to any one of the preceding claims, characterized in that the thickness of the lateral branches (12c, 12d) and of the base (11) are identical, the foil (1) is in one piece and comes from a same material. Assembly (100) for a turbomachine rotor characterized in that it comprises:

• a moving blade (2) comprising:
  • an internal platform,
  • a blade extending radially from the platform and
  • a blade root (21) extending radially from this platform opposite the blade, the blade root (21) comprising a first and a second radial face (23) and two lateral longitudinal faces joining each face radial (23), at least one flank on each lateral longitudinal face, intended to form a seat against a surface of a housing of the blade root (21)
• the shim according to one of claims 1 to 8, mounted on the root (21) of the moving blade (2), and in that at least the two lateral tabs (14c, 14d) are each folded down and in contact against the surface of one of the two radial faces (23) of the blade root (21).

Rotor (10) of a turbomachine comprising:

• a disc (3) comprising a plurality of cells (31) and
• at least one assembly (100) according to claim 9,
• wherein the foot (21) and the shim (1) are mounted in one of the cells (31).