Tool and method for bending a shim for a rotating rotor wheel blade in a turbomachine

Abstract

One aspect of the invention relates to a bending tool for at least one shim (130) for a rotating rotor wheel blade in a turbomachine, the rotor wheel comprising a disc having an outer surface provided with several recesses, each receiving a rotating blade foot (125), each rotating blade foot (125) being surrounded by a shim (130) positioned between said rotating blade foot and the outer surface of the disc, the bending tool comprising a base (201) equipped with at least one receptacle (210) forming at least partially an imprint of the rotating blade foot (125). Another aspect of the invention relates to a method for bending at least one shim (130) for a rotating rotor wheel blade using the bending tool. Figure to be published with the abstract: Figure 9

Description

Title of the invention: Tool and method for bending a shim for a rotating rotor wheel blade in a turbomachine. TECHNICAL FIELD OF THE INVENTION

[0001] The present invention relates to a bending tool for bending at least one shim around the foot of a rotating rotor blade in a turbomachine. It also relates to a method for bending the shims using this bending tool.

[0002] The invention finds applications in the field of aeronautics and, in particular, in the field of turbomachine rotors to improve the folding of the shims and, thus, improve their retention around the feet of the moving blades. TECHNOLOGICAL BACKGROUND OF THE INVENTION

[0003] Conventionally, a turbomachine turbine, such as the one shown in [Fig. 1], comprises a series of stages 13 arranged one behind the other, along the axis of gas flow. Each stage 13 of the turbine includes a vane forming the rotor 12 and a bladed distributor forming the stator 11. The vane is rotated opposite the corresponding distributor.

[0004] A rotating blade wheel, also called a rotor wheel, comprises several rotating blades 120 mounted in a disk 14. An example of a rotating blade 120 is shown in [Fig.2]. This rotating blade 120 comprises a blade 122 having, in its lower part, a platform 123 extended radially by a foot 125 and, in its upper part, a heel 121 designed to be arranged edge to edge with the heel of the adjacent rotating blades so as to form a rotating circumferential ring delimiting a surface of revolution around the axis of rotation XX of the disk.

[0005] As shown in [Fig. 4], the rotating wheel comprises a disk 14 centered on a rotation axis XX and whose outer periphery is provided with several cavities 15, called recesses. These recesses 15 are arranged alternately between two teeth 16 of the disk 14 and each receives the foot 125 of a rotating blade 120. This foot 125 of the rotating blade 120 (also called the blade foot or simply the foot) is retained radially in a recess 15 of the disk 14 by a cooperation of shapes between said foot 125, generally dovetail-shaped, and the recess whose shape is complementary to that of the foot 125.

[0006] During the operation of the rotor 12, contact between the feet 125 of the movable blades 120, for example made of titanium aluminide, and the disk 14, made for example of a nickel-based alloy, causes premature wear of the feet 125 and / or the recesses 15 of the disk. In order to limit the wear of the feet of the movable blades and the recesses For the disc, it is known to place a contact piece 130, called a shim, at the contact interfaces between the feet 125 of the moving blades 120 and the recesses 15 of the disc. The shim 130 is mounted integrally with the foot 125 of the moving blade 120 and absorbs a large part of the energy dissipated by friction in the contact between the foot 125 and the disc 14, thus limiting wear on the foot.

[0007] An example of a tinsel 130 is shown mounted around a paddle foot 125 in [Fig.3]. This shim 130 has a generally U-shaped cross-section, formed by two lateral arms 132, or lateral surfaces (only one of which is visible in [Fig. 3]), designed to cover the lateral sides 126 of the foot 125 of the movable blade 120 and to hold the shim 130 onto the blade foot 125. The shim 130 also has a base 131, also called the main surface, which connects the lateral surfaces 132 to each other and covers the lower surface 127 of the blade foot 125. This main surface 131 of the shim 130 generally includes radial tabs 133 bearing against the upstream 128 and downstream 129 faces of the blade foot 125. The radial tabs 133 (only one of which is visible in [Fig. 3]) are strips cut at the end of the main surface 131 and folded radially along the upstream and downstream faces 128, 129 of the foot of the blade 125.These radial tabs 133 extend over a greater or lesser width, between the lateral branches 132 of the shim 130, and form stops which prevent relative axial movements between the blade foot 125 and the shim 130. .

[0008] However, during operation, due to thermal expansion and the stresses involved, the shims 130 tend to move axially in a progressive manner, despite the presence of the radial tabs 133. Indeed, the movement of the shims 130 can damage the tabs 133, even causing them to break, and continue until the shims are completely disengaged. Since the shims 130 are no longer held on the blade roots 125, they can disengage from said blade roots and partially or completely come out of the recesses 15 of the disc. An example of a 130a shim, partially disengaged, is shown in [Fig.4], the other 130 shims shown in this [Fig.4] being correctly engaged in alveoli 15 of the disk 14, each around a blade foot 125.

[0009] The disengagement of a shim 130, or even several shims, presents numerous significant drawbacks. On the one hand, the disengaged shim can be released into the turbomachine's air stream and damage the blades of the stages located downstream of the turbine, particularly when these blades are made of titanium aluminide (TiAl), which is especially sensitive to impacts. The disengagement of a shim can also cause a crack in the blade root, that is, a fissure that has a direct consequence on the mechanical strength of the blade root in the disk. An example of a crack in a movable blade root is shown in [Fig. 5], by Reference 17, this crack 17 extending from the upper surface of the blade root 125 and stretching almost to the lower surface of said blade root. Whether partial or total, such a disengagement of a shim necessarily entails the removal and dismantling of the turbine to reposition or replace the shims, resulting in significant costs for parts and labor, as well as downtime for the turbomachine.

[0010] There is therefore a real need for a technique to prevent the disengagement of the shims, particularly by ensuring a high-quality fold of the upstream tab of the shims. Indeed, it has been identified that the tab folds are not all correctly formed and that tabs with incorrect or defective folds are the cause of most shim disengagements. In fact, the tabs of the shims are generally folded manually by operators who, first, fold the tab by hand and then finalize the fold by pressing the tab against a table. Thus, not only is folding the tabs relatively long and risky for the operators, who can cut themselves on the thin sheet metal used to manufacture the shim, but it also requires a certain dexterity and considerable experience to obtain a high-quality fold, identical for each shim. Summary of the invention

[0011] To address the aforementioned problems of defective tab folding, which cause shims to disengage, the applicant proposes a shim folding tool that enables high-quality, reproducible folding of the shims on all shims of a rotor wheel. The applicant also proposes a shim folding method using this folding tool.

[0012] According to a first aspect, the invention relates to a bending tool for at least one shim for a movable rotor wheel blade in a turbomachine, the rotor wheel comprising a disc having an outer surface provided with several recesses each receiving a movable blade foot, each movable blade foot being surrounded by a shim positioned between said movable blade foot and the outer surface of the disc, the bending tool comprising a base equipped with at least one receptacle forming at least partially an imprint of the movable blade foot.

[0013] This folding tool makes it possible to correctly fold the shims so that the downstream tab of the shim is pressed against the lateral radial surface of the blade foot, which ensures that the shim is held around said blade foot and prevents its disengagement from the hole of the disc.

[0014] In this application, the terms "lower" and "upper" in relation to parts of the turbomachine are interpreted with reference to their position relative to to the axis of rotation of the turbomachine, a lower surface being closer to the axis of rotation XX than an upper surface. The term "radial" is to be interpreted as "along a direction perpendicular to the axis of rotation XX" or "along the direction of a radius of the blade ring"; the term "lateral" is to be interpreted as "located on the sides of a part or surface that extends radially along an axis substantially perpendicular to the axis of rotation XX"; and the term "axial" is to be interpreted as "along the direction of the axis of rotation XX". The terms "upstream" and "downstream" are to be interpreted with reference to the direction of airflow within the turbomachine.

[0015] In the present application, the term “receptacle” should be interpreted as a blind or non-through orifice capable of receiving a part or set of parts.

[0016] In addition to the characteristics mentioned in the preceding paragraph, the bending tool according to one aspect of the invention may have one or more additional characteristics from among the following, considered individually or according to all technically possible combinations: • the receptacle has a longitudinal section in the shape of a right trapezoid with faces perpendicular to each other and at least one oblique face. • The receptacle has an open upper surface to receive the clapper and the foot of the moving vane, and five walls including: • two longitudinal walls parallel to each other and forming a support for lateral branches of the cladding against the lateral sides of the vane foot, • a lower wall forming the bottom of a receptacle, • a first lateral wall connecting the longitudinal walls to each other and forming a buttress for a first radial tongue of the shim • a second lateral wall, oblique, forming an angle greater than 90° with the lower wall, and constituting a guiding surface for the blade foot. • the first radial tab of the shim is a downstream tab positioned along a downstream radial face of the blade foot, a second radial tab, opposite the first radial tab, being an upstream tab positioned along an upstream radial face of the blade foot. • The bending tool has several receptacles, each receptacle forming an imprint for the foot of one of the movable blades of a rotor stage. • the second oblique lateral wall forms, with respect to the lower wall, an angle between 110° and 120°. • the first lateral wall forms, with the longitudinal walls and / or the bottom wall, an angle between 65° and 90°. • The base comprises a polymer material.

[0017] A second aspect of the invention relates to a method for bending at least one shim for a moving rotor wheel blade of a turbomachine, said method comprising the following operations: • positioning, against the lower surface of the movable blade foot, of a pre-cut metal plate to form a shim, • folding of the lateral branches of the tinsel along the lateral sides of the awl foot, • folding of an upstream radial tab of the shim along a second radial surface of the movable blade foot, • Installation of the movable blade foot, equipped with the partially mounted shim, in a receptacle for the bending tool as defined previously, the movable blade foot being positioned between two longitudinal walls and in contact with a second lateral wall of the receptacle, and • Insertion of the movable blade foot equipped with the partially mounted shim inside the receptacle by sliding along the second side wall of the receptacle until the first downstream radial tab is folded and pressed against the first radial surface of the movable blade foot.

[0018] This process not only allows for high-quality folding of the downstream radial tab of the shims but also for reproducible folding from one shim to another. This folding process makes it possible to limit, or even eliminate, the risk of shim disengagement.

[0019] Advantageously, a shim is mounted around each movable blade foot of the rotor by means of a specific receptacle whose imprint corresponds to said movable blade foot, the shims of each rotor wheel being folded successively in different receptacles of the same folding tool. BRIEF DESCRIPTION OF THE FIGURES

[0020] Other advantages and features of the invention will become apparent from the following description, illustrated by the figures in which:

[0021] Fig. 1, already described, represents a schematic cross-sectional view of a turbomachine turbine;

[0022] The [Fig.2], already described, represents, according to a perspective view, a movable blade of the turbine of the [Fig.1];

[0023] Fig. 3, already described, represents a schematic perspective view of a vane foot equipped with a clapper;

[0024] Fig. 4, already described, represents a schematic perspective view of a portion of a rotor wheel, with portions of movable blades mounted on a disk;

[0025] The [Fig.5], already described, schematically represents part of a movable blade foot in which a crevice has formed;

[0026] Fig. 6 schematically represents a partial view of two stages of a rotor;

[0027] Figure 7 represents a schematic perspective view of an embodiment of a folding tool according to the invention;

[0028] Fig. 8 represents schematic perspective views of another embodiment of the bending tool according to the invention;

[0029] Fig. 9 represents a schematic perspective view of a shim being bent in the bending tool according to the invention;

[0030] Figure 10 represents a schematic side view of a shim after bending using the bending tool according to the invention; and

[0031] Fig. 11 represents several schematic side views of a shim at different stages of the folding process according to the invention. DETAILED DESCRIPTION

[0032] An example of an embodiment of a tool for bending shims for turbine blades and its implementation method is described in detail below, with reference to the accompanying drawings. This example illustrates the features and advantages of the invention. It should be noted, however, that the invention is not limited to this example.

[0033] In the figures, identical elements are identified by identical reference numerals. For the sake of readability, the size scales between represented elements are not respected.

[0034] Figure 7 represents a first embodiment of the bending tool 200. In this first embodiment, the bending tool 200 comprises a base 201 containing at least one receptacle 270 whose shape and dimensions correspond to those of a blade foot 125 equipped with its shim 130 so as to form at least in part an imprint of this blade foot 125. This receptacle 270, the shape of which will be described in detail later, is designed to receive the foot 125 of one of the movable blades 120 of a rotor wheel as well as the shim 130 to be mounted on this blade foot.The base 201 of the bending tool 200 is preferably made of a polymer material, such as ABS (Acrylonitrile Butadiene Styrene), PA6 (Nylon), PEEK (Polyether Ether Ketone) or PMMA (Polymethyl Methacrylate) which, although impact resistant, has the advantage of not risking damage to the blade foot or the shim during the shim bending operations around the blade foot.

[0035] In a rotor 12, not all the movable blades 120, and in particular their roots 125, are identical. Indeed, the roots of the blades 125 of a rotor may have characteristics and / or shapes that vary from one to another, particularly depending on the stage to which they belong. As a reminder, and as shown in [Fig. 6], a rotor 12 of a turbine 10 comprises several stages 13 (only the penultimate stage 13b and the last stage 13a are visible in [Fig. 6]). Each rotor stage 13 comprises a rotor wheel formed by a disk 14 and a plurality of movable blades 120. Each movable blade 120 is retained by its foot 125 in a recess 15 of the disk 14. A shim 130 is housed between the foot 125 of the movable blade 120 and the wall of the recess 15 of the disk 14 to protect said blade foot and said recess from premature wear. The rotor stages 13 of the rotor 12 are arranged one after the other from upstream to downstream.Regardless of their number, the stages 13 comprise a first stage positioned upstream of the turbine (not visible in [Fig. 6]), a final stage 13a positioned downstream of the turbine, and one or more intermediate stages 13b positioned between the first and final stages. In most turbines, the rotor stages 13 have, on either side of the blade roots 125, a retaining ring 18 housed in a retaining hook 124 extending radially from the platform 123 of the blade root 125 towards the axis of rotation XX. Most of the rotor 12 stages 13 have a first arresting ring 18a (or upstream ring) which extends along the upstream surfaces of the blade roots 125 and a second arresting ring 18b (or downstream ring) which extends along the downstream surfaces of the blade roots 125. However, the last rotor stage 13a has only one arresting ring, namely the upstream ring 18a.Indeed, since the last stage 13a of the rotor is only linked to the preceding intermediate stage 13b, the blade feet 125 of this last stage 13a are not equipped with any retaining hook 124 on their downstream surface; therefore, no retaining ring extends along the downstream surface of the blade feet 125 of this last stage 13a.

[0036] Thus, the feet 125 of the movable blades 120 of the last stage 13a of the rotor differ significantly from the feet 125 of the movable blades 120 of the other stages. Other particularities may also exist between the blade feet of the different stages 13 of the rotor.

[0037] One embodiment of the bending tool 200 is specifically designed to adapt the bending of the blades to all the blade feet 125 of the same rotor, regardless of the shape and dimensions of these blade feet. To this end, the base 201 of the bending tool 200 has several receptacles 210-270, the shape and dimensions of each receptacle 210-270 being adapted to the blade feet of one of the rotor stages. However, a single receptacle 210-270 can be compatible with several blade feet 125 from several stages when the dimensions of these blade feet 125 are close to each other. An example of a bending tool 200 with several receptacles 210-270 are shown in drawings A and B of [Fig. 8]. In this example, the bending tool 200 is designed for a seven-stage rotor; each of the receptacles 210-270 is adapted for the moving blades 120a-120g of one of the rotor stages. In particular, and as shown in drawing B of [Fig.[8] The first receptacle 210 is suitable for folding the shims of the feet 125 of the moving blades 120a of the first rotor stage, the second receptacle 220 is suitable for folding the shims of the feet 125 of the moving blades 120b of the second rotor stage, the third receptacle 230 is suitable for folding the shims of the feet 125 of the moving blades 120c of the third rotor stage, the fourth receptacle 240 is suitable for folding the shims of the feet 125 of the moving blades 120d of the fourth rotor stage, the fifth receptacle 250 is suitable for folding the shims of the feet 125 of the moving blades 120e of the fifth rotor stage, the sixth receptacle 260 is suitable for folding the shims of the feet 125 of the moving blades 120f of the sixth and penultimate stage 13b of the rotor, and the seventh receptacle 270 is adapted for folding the shims of the feet 125 of the moving blades 120g of the seventh and last stage 13a of the rotor. .

[0038] In a variant of [Fig. 7], the bending tool 200 comprises a single receptacle 270 whose shape and dimensions are adapted to those of the feet of the movable blades of the last rotor stage. Indeed, as explained previously, the last rotor stage does not have a retaining ring 18 downstream of the blade feet. The shims 130 of this last stage 13a are therefore particularly prone to disengaging completely from the disk's recesses. In fact, given the rotation of the rotor and the upstream to downstream flow of gas, the shims 130 tend to disengage downstream of the rotor.In the first and intermediate rotor stages, the presence of a retaining ring 18 downstream of the blade roots allows for some retention of the disengaging shims; in other words, the shims 130 of the first and intermediate rotor stages can disengage from the grooves, but the disengagement is generally partial because the shims 130 are held in place by the downstream retaining rings of the rotor wheels. Conversely, due to the absence of a retaining ring 18 downstream of the last rotor stage, no retention of the shims is possible. The disengagement of the shims 130 from this last stage is therefore more likely to be complete. It is therefore essential to prevent the disengagement of the shims 130 from the last rotor stage 13a by ensuring reliable folding of the downstream tab of these shims.The variant of the folding tool 200 in which the base 201 only has a receptacle 270 adapted to the feet of the moving blades of the last stage therefore avoids this risk of total disengagement of the cladding of the last stage of the rotor.

[0039] The [Fig.9] and the [Fig. Figures 10 represent an example of a receptacle 210 for the bending tool 200 and a blade foot 125 with its shim 130, respectively, before and after its arrangement in the receptacle 210 of the bending tool 200. The receptacle 210 is a non-through orifice whose shape partly represents the imprint of the blade foot 125. This receptacle 210 has a right trapezoidal longitudinal section (as shown in Figure 10) with an open upper face 210f, a lower face 210e parallel to the open face 210f and forming the bottom of the receptacle, a first lateral face 210c perpendicular to the upper face 210f and lower face 210e and forming a buttress for the downstream tab 133a of the shim 130, and a second oblique lateral face 210d, forming a non-right angle with the lower face 210e and forming a guide for the upstream tongue 133b of the shim 130.

[0040] The receptacle 210 comprises, more specifically, five walls 210a, 210b, 210c, 210d, 210e and an open upper surface 210f. The open upper surface 210f is the face which corresponds to the upper face of the longitudinal section of the receptacle, through which the shim 130 and the blade foot 125 are inserted inside said receptacle.

[0041] The walls of the receptacle 210 comprise: • a lower wall 210e, which corresponds to the lower face of the longitudinal section of the receptacle, and forms the bottom of the receptacle 210; this lower wall 210e is a flat surface, parallel to the upper surfaces 201a and lower surfaces 201b of the base 201; it is rectangular in shape and forms the bottom of the receptacle 210. The lower wall 210e has dimensions adapted to the dimensions of the base of the blade foot, that is to say dimensions equal, within a clearance, to those of said base of the blade foot (the base corresponding to the lower surface 127 plus the curvatures of the lateral sides 126). More precisely, the lower wall 210e has a length L1 equal to the length L2 of the blade foot 125 less a clearance J of the order of a millimeter, this clearance J ensuring an end of travel when the downstream tongue 133a of the shim is correctly folded and pressed against the downstream face of the blade foot.The lower wall 210e has a width 11 equal to the width 12 of the base 126 / 127 of the blade foot plus a clearance J of the order of a millimeter, this clearance J preventing any blockage of the blade foot / clapper assembly in the receptacle. • two longitudinal walls 210a, 210b, facing each other and perpendicular to the lower wall 210e. The longitudinal walls 210a, 210b extend on either side of the length of the blade foot 125, along each of the sides 126 of said blade foot; these longitudinal walls 210a, 210b are trapezoidal in shape and form a support for the blades The lateral walls 132 of the shim 130 are positioned against the convex curves of the blade foot flanks 126. Each of the longitudinal walls 210a and 210b has dimensions adapted to the dimensions of the blade foot flanks 126. In particular, each longitudinal wall 120a, 120b has a first length L1 equal to the length of the lower wall, a second length L3 greater than the first length L1, and a height hl approximately equal to the height h2 of the shim 130. • a first lateral wall 210c, corresponding to the first lateral face of the longitudinal section of the receptacle. This first lateral wall 210c connects the two longitudinal walls 210a, 210b to each other and forms, with each of these longitudinal walls 210a, 210b, an angle of between 65° and 90°, and preferably between 70° and 75°. This lateral wall 210c also forms an angle with the lower wall 210e of between 65° and 90°. The side wall 210c thus forms a buttress for the downstream tongue 133a of the shim 130, this buttress ensuring the folding of said downstream tongue 133a against the downstream face 129 of the blade foot 125. The first side wall 210c has dimensions adapted to the dimensions of the downstream face 129 of the blade foot with, for example, a width 11 equal to the width 12 of the base 126 / 127 of the blade foot plus a clearance J of the order of a millimeter and a height hl substantially equal to the height h2 of the shim 130. • A second side wall 210d, corresponding to the second lateral face of the longitudinal section of the receptacle, is positioned obliquely relative to the longitudinal walls 210c and 210d to form a slanted surface within the receptacle 210. This second side wall 210d forms an angle greater than 90° with the lower wall 210e, for example, an angle between 110° and 120°, which guides the blade foot 125 towards the interior of the receptacle. An angle between approximately 110° and 120° ensures optimal guidance of the blade foot 125, guaranteeing both optimal folding of the downstream tab 133a and limited effort from the operator performing the folding of the shim. The second side wall 210d has dimensions substantially identical to those of the first side wall 210c, described above.

[0042] In certain embodiments, such as that shown in [Fig. 10], the first and / or second side walls 210c, 210d may have a flared edge 202. This flared edge 202 is a slanted or rounded portion of the side walls 210c, 210d at the intersection with the open surface 210f. This flared edge 202, which can extend over a thickness d of approximately 0.5 mm, has the advantage of facilitating the insertion of the blade / shim assembly into the receptacle 210 without risk of damage to the shim. This flared edge 202 can also help guide the blade / shim assembly when inserted into the receptacle 210. Although not visible in the figures, the longitudinal walls 210a and 210b can also be provided with a flared edge 202 similar to that of the side walls, the flared edge then extending over the entire periphery of the receptacle 210.

[0043] Figures 9 and 10 have been described for the receptacle 210, that is, the receptacle provided for the blade feet 125 of the first rotor stage. Those skilled in the art will understand that all the receptacles of the bending tool 200 have identical characteristics to those described for the receptacle 210, only the dimensions vary from one receptacle to another so as to correspond to the footprint of the blade feet of each rotor stage.

[0044] The bending tool 200 just described can be used in a process for bending a shim for a movable rotor blade foot. An example of such a bending process is shown, at least partially, in [Fig. 11]. This process includes a first operation 310 of partially shaping the shim 130 around the blade foot 125. This partial shaping first involves selecting a pre-cut metal plate in the shape of the shim and positioning this metal plate against the lower surface 127 of the blade foot 125. The pre-cut metal plate is called the shim 130 even though, at this stage of the process, it is not yet bent and does not yet cover the blade foot.For this positioning operation, the main surface 131 of the shim is placed against the lower surface 127 of the blade foot, and the lateral branches 132 of said shim are folded along the sides 126 of the blade foot so as to cover said sides. The operation 310 of partially shaping the shim 130 around the blade foot 125 then includes a step of folding a second radial tab 133b of the shim 130 along the first radial surface 128 of the blade foot. This second radial tab 133b is preferably the upstream tab of the shim 130.

[0045] Once the shim 130 is partially mounted around the blade foot 125, the assembly consisting of the blade foot 125 and its partially mounted shim 130 – called the blade foot / shim assembly – is presented above the receptacle 210 of the bending tool (operation 320). The first tab 133a, preferably the downstream tab, is deployed longitudinally in line with the main surface 131 of the shim 130.

[0046] The process continues with an operation 330 of installing the blade / spark assembly inside the receptacle 210. In this operation 330, the blade / spark assembly is positioned in the open surface 210f of the receptacle 210 so as to be between the two longitudinal walls 210a and 210b and in contact with the wall oblique lateral 210d of the receptacle. The second tab 133b is then in contact with the oblique lateral wall 210d.

[0047] The process continues with an operation 340 of inserting the blade foot / spark assembly deeper into the receptacle 210 by sliding, or moving, said assembly along the oblique side wall 210d of the receptacle. This sliding of the blade foot / spark assembly along the oblique side wall 210d causes the downstream tab 133a to be progressively folded against the first side wall 210c. The further the blade foot / spark assembly is inserted into the receptacle 210, the more the downstream tab 133a folds, until the downstream tab 133a is perfectly folded and pressed against the downstream face 129 of the blade foot 125.As explained previously, it is important that the length L1 of the lower wall 210e of the receptacle be less than a clearance J compared to the length L2 of the blade foot, so that the stroke of the blade foot / shim assembly in the receptacle stops when the downstream tab 133a is folded and pressed against the downstream face 129 of the blade foot. If the stroke of the blade foot / shim assembly in the receptacle stopped when the main surface 131 of the shim abutted the lower surface 210e of the receptacle, then there would be no certainty regarding the quality of the folding of the downstream tab 133a. Once operation 340 is completed, the shim 130 is fully mounted around the blade foot 125 and its downstream tab 133a is perfectly folded, which avoids or at least limits the risks of the shim 130 disengaging from the disc cavity.

[0048] When the bending tool 200 conforms to the embodiment of [Fig.8], then the blade feet 125 of each rotor stage are mounted successively one after the other in the different receptacles of the bending tool 200. The same process 300 is implemented for each moving blade of each rotor stage.

[0049] Although described through a number of examples, variants and embodiments, the bending tool according to the invention, and its method of implementation, include various variants, modifications and improvements which will be obvious to a person skilled in the art, it being understood that these variants, modifications and improvements are part of the scope of the invention.

Claims

Demands

1. Bending tool (200) of at least one shim (130) for a movable blade (120) of rotor wheel in a turbomachine, the rotor wheel comprising a disc (14) having an outer surface provided with several recesses (15) each receiving a movable blade foot (125), each movable blade foot (125) being surrounded by a shim (130) positioned between said movable blade foot and the outer surface of the disc, the bending tool (200) comprising a base (201) equipped with at least one receptacle (210) forming at least partially an imprint of the movable blade foot (125).

2. A folding tool according to claim 1, characterized in that said at least one receptacle (210) has an open upper surface (210f) for receiving the shim (130) and the foot of the movable blade (125), and five walls of which: - two longitudinal walls (210a, 210b) parallel to each other and forming a support for lateral branches (132) of the shim against lateral sides (126) of the foot of the movable blade, - a lower wall (210e) forming a bottom of the receptacle, - a first lateral wall (210c) connecting the longitudinal walls to each other and forming a buttress for a first radial tab (133a) of the shim, and - a second lateral wall (210d), oblique, forming an angle greater than 90° with the lower wall (210e), and constituting a guiding surface for the foot of the movable blade.

3. Bending tool according to claim 2, characterized in that the first radial tab (133a) of the shim is a downstream tab positioned along a downstream radial face (129) of the movable blade foot, a second radial tab (133b), opposite the first radial tab, being an upstream tab positioned along an upstream radial face (128) of the movable blade foot.

4. Bending tool according to any one of claims 1 to 3, characterized in that it comprises several receptacles (210-270), each receptacle forming an imprint for the foot (125) of one of the movable blades (120) of a rotor stage.

5. Bending tool according to any one of claims 2 to 4, characterized in that the second oblique side wall (210d) forms, with respect to the lower wall (210e), an angle between 110° and 120°.

6. Bending tool according to any one of claims 2 to 5, characterized in that the receptacle (210) has a flared edge (202) extending at least along the first and second side walls (210c, 210d).

7. Bending tool according to any one of claims 2 to 6, characterized in that the first side wall (210c) forms, with the longitudinal walls (210a, 210b) and / or the bottom wall (210e), an angle between 65° and 90°.

8. Bending tool according to any one of claims 1 to 7, characterized in that the base (201) comprises a polymer material.

9. A method for bending at least one shim (130) for a rotating blade (120) of a turbine rotor wheel, said method comprising the following operations: - positioning (310), against the lower surface of the rotating blade root, of a pre-cut metal plate to form a shim, - bending (310) the lateral arms (132) of the shim along lateral sides (126) of the rotating blade root (125), - bending (310) of a second radial tab (133b) of the shim along a second radial surface (128) of the rotating blade root, - installing the rotating blade root (125) equipped with the partially mounted shim (130), in a receptacle (210) of the bending tool (200) according to any one of the preceding claims, the rotating blade root being positioned between two longitudinal walls (210a, 210b) and in contact with a second lateral wall (210d) of the receptacle,and - insertion of the movable blade foot (125) equipped with the clapper (130) partially mounted inside the receptacle (210) by sliding along the second lateral wall (210d) of the receptacle until the first radial tab,

10. (133a) be folded and pressed against the first radial surface (129) of the movable blade foot. Method according to claim 9, characterized in that a shim (130) is mounted around each foot (125) of movable rotor blade by means of a specific receptacle (210-270) the imprint of which corresponds to said foot of movable blade, the shims of each rotor wheel being folded successively in different receptacles of the same folding tool.

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