EP2738356A1 - Vane of a turbomachine, vane assembly of a turbomachine, and corresponding assembly method - Google Patents

Abstract

The stator blade has a platform (32) with an attachment (34) attached to a ferrule allowing angular adjustment of the blade. The platform has a contour with an angular profile provided at each lateral edge (36) to mate with the adjacent edge of the platform of an identical adjacent blade, in order to ensure the angular positioning of the blade in one direction of rotation. Independent claims are included for the following: (1) a stator; and (2) a method for assembling annular row of blades on ferrule of stator.

Description

Technical area

The invention relates to axial turbomachine blades, more particularly to an axial turbomachine stator. The invention also relates to a rectifier and an axial turbomachine comprising the rectifier. The invention relates to the angular positioning of the blades of an axial turbomachine. The invention also relates to a method of mounting the axial turbomachine and more particularly to its or its rectifiers.

Prior art

In order to achieve high efficiency, the axial turbomachines have several compressors and possibly several turbines in which compression and expansion of the air occur respectively. Each compressor and turbine presently has several rows of stator and rotor blades alternately. The blades of the successive stages have a progressive evolution of their angle of wedging, which allows to gradually compress the air before it enters the combustion chamber, and gradually relax the exhaust gas.

Calibration is a data item that is calculated for each blade row in order to optimize the efficiency of a given row, and the overall efficiency of a turbomachine. To achieve such a row, several solutions are possible. For example, the row can be made from vanes welded to a shell, a housing or a rotor. The vanes can also be fixed using screw or lockbolts. By providing each blade with two attachment axes, the latter is blocked in rotation. However, this solution is particularly heavy because of the existence of the second attachment axis.

To save weight, it is advantageous to use only one attachment axis. However, this denier is no longer able to block in rotation the dawn so that it keeps its rigging. Stalling can still be respected by providing the dawn of a platform which is placed in an annular groove whose shoulders provide a stop at the corners of the rectangle.

The document EP 1 936 121 B1 discloses a turbomachine having such a blade with a platform housed in such an annular groove. The blade is fixed with a nut screwed onto its threaded axis. However, this solution has manufacturing constraints. She asks to add a throat involving extra thickness in one place. If one of the materials forming a platform or the groove has a reduced hardness, this material may deform during tightening of the nut. Therefore, the precision of the setting of the blade can be altered.

Summary of the invention Technical problem

The object of the invention is to solve at least one of the problems posed by the prior art. The object of the invention is to propose an angular wedging solution for a stator blade. More particularly, the invention aims to provide a blade design to reduce the manufacturing costs of the turbomachine while ensuring satisfactory calibration.

Technical solution

The subject of the invention is an axial turbomachine stator vane intended to be mounted on a ferrule in an annular row of identical vanes, the vane comprising a platform with means for fastening to the ferrule enabling angular adjustment. dawn, an upstream edge, a downstream edge and two opposite side edges; remarkable in this that the outline of the platform has at each of its lateral edges an angled profile adapted to engage with the adjacent edge of the platform of an identical neighboring blade, to ensure angular positioning of the blade in at least one direction of rotation.

The lateral edges can be configured to be able to coincide generally in a transverse translation. Transverse translation means a translation directed along the circumference of the row of blades.

The lateral edges may be configured to be able to coincide mainly with a rotation in the space around the axis of rotation of the turbomachine. This accuracy is useful for rows of blades implanted on an inclined surface. Geometrically, this inclination results in a reduction of platform widths downstream or upstream.

According to yet another advantageous embodiment of the invention, the transverse width of the platform remains substantially constant.

According to an advantageous embodiment of the invention, the bent profile has at least one bearing portion forming a mean angle with the axis of the turbomachine less than or equal to 45 °, preferably less than or equal to 20 °. This angle can also be essentially zero.

According to an advantageous embodiment of the invention, the or at least one of the support portions of the bent profile is generally straight.

According to an advantageous embodiment of the invention, the upstream and downstream edges are generally straight and parallel, the axis of the turbomachine being generally perpendicular to said edges.

According to an advantageous embodiment of the invention, the attachment means of the platform comprise rotation clamping means, arranged substantially in the center of the platform, the or at least one of the support portions of the angled profile being positioned so as to bear against the corresponding profile of the adjacent edge of the neighboring blade when the platform pivots in the clamping direction of the fastening means.

According to an advantageous embodiment of the invention, the support portion of the bent profile is part of a projecting zone of the corresponding lateral edge of the platform.

According to an advantageous embodiment of the invention, each of the lateral edges of the platform further comprises a hollow-shaped zone, the projecting and hollow-shaped zones being disposed on either side of a transverse axis passing through the pivot center of dawn. When the hollow-shaped area is adjacent to one of the upstream and downstream edges, it is more of a cutout shape.

According to an advantageous embodiment of the invention, the profile of each of the lateral edges of the platform has a generally straight central portion and a bearing portion at an upstream or downstream position, preferably at each of the two upstream and downstream positions.

According to an advantageous embodiment of the invention, the fixing means comprise a stud extending from a face of the platform, said face serving as mounting face to the ferrule.

The invention also relates to an axial turbomachine rectifier, comprising a shell with an inner surface, and an annular row of blades comprising identical platforms arranged side by side on the inner surface of the shell; remarkable in that the blades are in accordance with the invention, several consecutive blades having at least a portion of their profile bent on the same lateral side bearing on the corresponding profile of the adjacent blade.

According to an advantageous embodiment of the invention, the attachment means of the platform comprise rotation clamping means, arranged substantially in the center of the platform, the or at least one of the support portions of the angled profile being positioned so as to bear against the corresponding profile of the adjacent edge of the neighboring blade when the platform pivots in the clamping direction of the fastening means, and the platforms of the blades have between them a mechanical assembly play. corresponding to a tolerance of angular positioning of the blades, the bent profiles of the plurality of consecutive blades being in mutual support in the clamping direction of the fastening means.

According to an advantageous embodiment of the invention, the plurality of consecutive vanes are configured to pivot more than 20 ', preferably more than 40', more preferably more than 80 ', even more preferably more than 120' around their fastening means when they are not tight.

According to yet another advantageous embodiment of the invention, the shell has a substantially constant thickness.

According to yet another advantageous embodiment of the invention, the ferrule has a mounting surface in contact with the essentially smooth blade platforms.

According to yet another advantageous embodiment of the invention, the housing is made of composite material.

The invention also relates to a compressor comprising at least one annular row of blades, remarkable in that the blades of the row of blades are in accordance with the invention.

The invention also relates to an axial turbomachine with a compressor and / or a turbine provided with a rectifier, remarkable in that the rectifier is in accordance with the invention, and or the compressor is in accordance with the invention.

The subject of the invention is also a method of mounting an annular array of vanes on an axial turbomachine stator shroud, the vanes being according to the invention and the platform attachment means comprising clamping means by rotation, arranged substantially in the center of the platforms, the or at least one of the support portions of the angled profiles being positioned so as to bear on the corresponding profile of the adjacent edge of the neighboring blade when the platforms rotate in the clamping direction of the fixing means, remarkable in that it comprises the steps of:

(a) mounting a reference blade substantially according to the final angular positioning of said row,

(b) successively placing a plurality of vanes on the shell so as to form said row of blades with the reference blade,

(C) successively clamping the fastening means of the plurality of vanes starting from the reference vane, so as successively to bring the or at least one of the support portions of the bent profile of each of said vanes bearing on the corresponding profile contiguous to the previous dawn.

According to an advantageous embodiment of the invention, step (b) covers only a part of the circumference of the rectifier, step (a) being performed at several points of said circumference.

According to an advantageous embodiment of the invention, the reference blade is a false blade corresponding to at least two contiguous blades, and in that the method further comprises the following step:

(d) replacing the false reference blade (s) with vanes corresponding to the other vanes.

According to yet another advantageous embodiment of the invention, the number of reference blades is less than 1/10 of the number of vanes of the rectifier, preferably less than 1/15, more preferably less than 1/20.

Benefits brought

The invention makes it possible to proceed precisely to the wedging of a row of blades, without resorting to a shoulder at the level of the fixing support such as a ferrule. In this way, the mounting bracket can be lightened. This feature also makes it possible to make a fastening support in composite materials, which offers the opportunity to still gain weight.

The wedging achieved by the invention requires conventional surface conditions, the mechanical clearances can be increased locally. Thus, the invention makes it possible to reduce manufacturing costs. In addition, the invention makes it possible to simplify the measurements and the controls necessary to achieve a given calibration. This aspect can still save money.

Brief description of the drawings

The figure 1 represents an axial turbomachine according to the invention.

The figure 2 is a representation of the low-pressure compressor of the axial turbomachine of the figure 1 , the compressor comprising several rectifiers according to the invention.

The figure 3 is a first view of an axial turbomachine blade according to a first embodiment of the invention.

The figure 4 is a second view of the dawn of the figure 3 .

The figure 5 illustrates an annular row of vanes of a straightener, the vanes corresponding to Figures 3 and 4 .

The figure 6 illustrates a blade according to a second embodiment of the invention.

The figure 7 illustrates a blade according to a third embodiment of the invention.

The figure 8 illustrates a blade according to a fourth embodiment of the invention.

The figure 9 illustrates a blade according to a fifth embodiment of the invention.

The figure 10 illustrates a blade according to a sixth embodiment of the invention.

Description of the embodiments

In the description which follows, the terms "inside" and "outside" refer to a positioning relative to the axis of rotation of the axial turbomachine. The terms "transverse" and "lateral" are expressed relative to the longitudinal direction of the turbomachine and the rectifier, this direction corresponding to the axis of rotation of the machine.

The figure 1 schematizes an axial turbomachine. It is in this case a double-flow turbojet engine. The turbojet engine 2 comprises a first compression level, called a low-pressure compressor 4, a second compression level, called a high-pressure compressor 6, a combustion chamber 8 and one or more levels of turbines 10. In operation, the mechanical power of the turbine 10 transmitted via the central shaft to the rotor 12 sets in motion the two compressors 4 and 6. Reducing means can increase the speed of rotation transmitted to the compressors. Or, the different turbine stages can each be connected to the compressor stages via concentric shafts. The latter comprise several annular rows of rotor blades associated with rows of stator vanes. The rotation of the rotor about its axis of rotation 14 thus makes it possible to generate an air flow and to compress it progressively until it reaches the combustion chamber 8.

An inlet fan commonly referred to as "turbofan" 16 is coupled to the rotor 12 and generates a flow of air that divides into a primary flow 18 passing through the various levels mentioned above of the turbomachine, and a secondary flow 20 passing through an annular duct (partially shown) along the machine to then join the primary flow at the turbine outlet.

The figure 2 is a sectional view of a low-pressure compressor 4 of an axial turbomachine 2 such as that of the figure 1 . There can be observed a portion of the turbofan 16 and the separation nozzle 22 of the primary flow 18 and the secondary flow 20. The rotor 12 comprises several annular rows of rotor blades 26, for example three; and a plurality of annular rows of stator vanes 28, for example four. Each row of stator vanes 28 is associated with a row of rotor blades 26 to straighten its air flow, so as to convert the speed of the flow into pressure. Each pair of rows of associated rotor blades and stator forms a compression stage of the compressor 4.

The low-pressure compressor 4 has a mechanically welded stator with a housing 30 serving as an attachment support for the stator vanes 28. The housing 30 forms a wall indirectly delimiting the primary flow 18. It may have a substantially smooth inner surface, preferably free of rim . It has a form of revolution around the axis 14 of rotation of the low pressure compressor 4 which corresponds to the axis of the turbomachine. Its revolution profile can be curved and move closer to the axis 14 downstream. The housing 30 may comprise or forming a plurality of annular members, such as ferrules arranged axially relative to each other so as to extend along the length of the compressor. It is remarkable that at the fourth row of stator vanes 28, the housing has an inclination greater than 15 °. Optionally, the inclination may be greater than 25 °.

The stator vanes 28 comprise platforms 32 pressed against the inner surface of the housing 30. They may be substantially planar or may be left-handed surfaces. Their surfaces coming into contact with the housing 30 are generally smooth. The contact between a platform 32 and the inner surface of the housing 30 is close to a plane-to-plane contact. The inclination of the platforms 32 with respect to the axis of rotation 14 increases substantially in the downstream rows.

Between the rows of stator vanes 28, strips 35 of abradable material are applied. More specifically, these strips 35 are arranged between the platforms 32 of the different rows of stator vanes 28. The thickness of the strips is substantially equal to the overall thickness of the platforms 32.

The stator vanes 28 are fixed to the casing 30 by means of fixing means 34. The fixing means 34 extend from their platform in a direction opposite to the aerodynamic part of the blade. The fixing means are essentially cylindrical. Fastening means 34 may comprise a fastening pin such as a screw or a stud, intended to receive a nut. Preferably, the fastening means of each blade essentially comprise a fixing axis. They are inserted into openings in the housing 30.

The fixing means comprise clamping means, for example nuts adapted to engage a screw or a stud. The clamping force of a clamping means can substantially rotate a blade around its fixing means 34 since its platform 32 is smooth and in plane-plane bearing against the housing 30.

In order to stem this pivoting, the platforms 32 have specific contours. The figure 3 represents a platform 32 according to a first embodiment of the invention. The platform 32 may have a general shape of a quadrilateral such as a rectangle, a trapezium or a parallelogram. The contour of the platform 32 comprises opposite side edges 36 and two transverse edges 38 which are arranged perpendicular to the axis of rotation 14, one being upstream of the body of the blade and the other being downstream. The platform 32 has an inverted "Z" shape. The lateral edges 36 have an angled profile and materialize a material engagement for locking in rotation.

The bent profiles of the edges 36 each comprise a bearing portion 48 intended to come into contact with the corresponding portion of the adjacent edge of a neighboring blade. This support forms a material commitment. The bearing portions 48 each form a projecting zone 40. The bent profiles also each comprise a hollow-shaped zone 42 with respect to the general shape of the platform rectangle. The hollow-shaped area corresponds to the projecting area of the opposite edge.

According to a preferred embodiment of the invention, the platforms 32 of the same row of blades are identical. In this way, an area projecting from a platform 32 can cooperate by engagement of material with a cut-out or hollow-shaped area 42 of a neighboring platform 32. The adjacent lateral edges 36 interpenetrate and block in rotation the platforms 32 according to at least one, possibly two directions of rotation around their fastening means 34. Thus, the angular orientation of a stator vane 28 can be adjusted precisely during assembly. The angular orientation of the stator vanes can be achieved reliably and repeatedly. The calibration measurement operations can be reduced, possibly eliminated.

The angular orientation or wedging of a blade is determined by the angle formed by the rope 44 of a blade with the axis of rotation 14 of the turbomachine 2. The rope used for this measurement is that at the junction at the level of of the platform 32.

The bearing portion 48 of a lateral edge abuts on the corresponding portion of the adjacent edge of the neighboring blade during the pivoting of the dawn caused by the tightening. In the case of the representation of the platform of the figure 3 , the tightening tends to rotate it in the clockwise direction. The bearing portion is generally parallel to the transverse direction, corresponding to the circumferential direction of the blade row. For this reason, the contact force between two neighboring blades generates little or no effort in the transverse direction. In addition, this support allows an angular position independent of the tolerances at the distance between the blades, more precisely between the holes of the shell receiving the fastening means 34. The tolerances at the distances between the orifices are greater than those relating to their alignment according to the circumference of the ferrule.

The platform 32 is made of metal, preferably titanium. It may have come from matter with the body of dawn. To respect a precise shape, its contour is machined, possibly rectified to meet strict tolerances.

The lateral edges 36 describe similar profiles, preferably identical. It is found that the profiles generally coincide if one translates a distance equal to the width of the platform 32, according to a vector oriented along the transverse edges (upstream and downstream) 38. The platform 32 generally has a width constant. The width may decrease substantially downstream due to the curvature of the housing 30. The width is measured transversely. Both profiles have substantially symmetry with respect to the center of the fixing means 34.

The two profiles can correspond exactly by translation in the case of platforms 32 parallel to the axis of rotation 14. With regard to the inclined platforms 32, and in particular those of the last row of stator vanes, the two profiles are substantially divergent. The two profiles can be matched by performing an isometry, namely a rotation along the axis of rotation 14 of the turbomachine.

The platform 32 has an excess thickness 46. The latter forms a disc cut laterally by the longitudinal edges 36. Due to the left form of the shell or housing 30, the contact with the disk may be in two points or in two arcs upstream and downstream. These contacts facilitate a slight slip when mounting a row of blades and improves the positioning and automatic orientation of the blades.

The figure 4 represents the stator dawn 28 of the figure 1 according to the first embodiment of the invention. It has a body 50, or blade 50, forming a profiled surface intended to extend in the primary stream 18. Its shape makes it possible to modify the flow of the stream. The head of the blade may have devices for attachment to an inner shell.

At the level of the extra thickness 46, the lateral edges 36 have an increased height. Thus, the platforms have a better locking in rotation and a better locking in tangential translation. The fixing means 34 may comprise a smooth cylindrical bearing surface 54 extending in the thickness of the casing 30. They also comprise a threaded portion 52 outside the casing 30.

To facilitate the assembly of a row of vanes, mechanical clearances are defined at the level of the platforms 32 as well as at the level of the fixing means 34. figure 5 illustrates a portion of a blade array according to the first embodiment of the invention. The row, which generally forms a ring, is here seen in plan. In order to allow the assembly of the row, mechanical clearances at the side edges 36 are defined. A first set of mechanics J1 is observed between the rectilinear portions 56 of the lateral edges 36, and a second mechanical clearance J2 between the bent portions of the lateral edges 36. The rectilinear portions 56 of two, preferably all of the neighboring blades may be at a distance. one from the other. The second mechanical clearance is present at the contact between the projecting zones 40 and the hollow-shaped zones 42, more precisely at the level of the bearing portions.

The first set J1 allows a transverse displacement of the platforms 32 in combination with the games at the fastening means 34. The second set J2 allows a pivoting of the platforms 32 and a displacement in the longitudinal direction of the machine , in combination with the clearance J3 at the fixing means 34. The games J2 and J3 may be between 0.01 mm and 0.30 mm, preferably between 0.01 mm and 0.20 mm. The games may be different, especially the J1 game may be higher than the J2 and J3 games. It may for example be greater than 0.05 mm, or greater than 0.50 mm. For aerodynamic reasons, it can become interesting to seal the game J1 with a silicone material. The smaller the required games, the higher the manufacturing accuracy, as well as the tight tolerance range. These games result in a possibility of pivoting between the platforms 32 and thus a variation of angular orientation of the blades.

During the design of the blades, they are defined a theoretical angular orientation that achieves a desired operation. In this same design, the shapes of the side edges are also fixed. To allow the assembly of a row of blades, it is mandatory to define the mechanical clearances J1, J2 and J3. But these allow a pivoting blades when clamping the fastening means, which has the effect of distorting the angular orientations of the blades. It should be noted that these angular orientation errors of the blades are in the direction of rotation of the clamping means. These errors also have an average value with a small standard deviation. As a result, the vanes are produced with a compensation angle, making it possible to compensate for the angular orientation error. Since the standard deviation of the error is small, the compensation angle allows for a blade array whose angular orientation dispersions are acceptable. Advantageously, the average angular orientation error and / or the compensation angle is greater than 5 ', preferably greater than 30'. The compensation angle is generally proportional to games J1, J2 and J3. It should be noted that the compensation angle is oriented in the opposite direction to the clamping means. The calculation of the compensation angle can be based on average values of the mechanical clearances, as well as on their standard deviations. Calculation of the calibration difference can also take geometric tolerances into account platforms surfaces.

The invention exploits the clamping force and the contour geometry of the platforms. The tightening effort tends to rotate the platforms in a given direction in proportions that arise games. Making the vanes with a geometry that is the inverse of the positioning error makes it possible to respect the mounting timing, by presenting a consistent average value and a reduced standard deviation.

The teaching of the invention can therefore be applied to a stage of stator or rotor blades which have platforms coming into contact with each other, and which are fixed on a mounting support by means of fixation may influence the angular orientation of the blades in one direction when tightening the clamping means. The teaching of the invention can be used for blades whose lateral edges are essentially straight, free of elbows.

To mount a row of blades 28 on its support, several methods are possible. The method may comprise a step of successively placing the blades in the housing 30. Then the method may comprise a step of successively tightening the clamping means in turn, proceeding from neighboring blade to neighboring blade. Fixing can be done from several starting points or starting blades. The nesting of the platforms makes it possible to respect the setting of the blades.

To improve the accuracy of the setting, the method may include a preliminary step of mounting at least one reference blade 28A or blade den. Preferably, during this step, several reference vanes are used, for example more than six for a row of one hundred and twenty blades in all. The reference blade 28A may be a conventional blade whose setting is adjusted and retained after fixation. Then begins the blade placement step so as to form a row of blades. At this time, the blades do not necessarily have a proper mounting timing. Then begins the step of successively tightening the clamping means. The nuts are tightened continuously, proceeding from neighboring blade to neighboring blade. Fixing can be performed starting from one side of a reference blade 28A, or both.

If the manufacturing precision of the blades 28 is reduced, the number of reference vanes will advantageously be increased. In this way the manufacturing costs can be reduced. Conversely, it is possible to decrease the number of reference vanes if the manufacturing accuracy is improved. In this way, the adjustment and control costs of the calibration of the reference vanes can be reduced.

To further increase the accuracy of calibration, it is possible to use in the mounting step of at least one reference blade another type of reference vanes. This type of blade is similar to conventional blades, but has an enlarged platform and two fastening means 34. These are introduced into two remote orifices, which allows to orient precisely this reference blade. The platforms have lateral edges to block in rotation the neighboring blades according to the mounting timing. The reference blade may be a false blade comprising a platform 32 with two fixing means 34. The greater the distance between the orifices used, the greater the accuracy of the setting assured is important. This accuracy is achieved without the need to perform measurement and control steps. Thus, it is possible to save time of manpower.

Following the blade attachment step, the method comprises a step of replacing the false blades. This step leaves free spaces in the blade row formed during the blade placement step.

Therefore, the method comprises a subsequent step of setting up and fixing blades in the free spaces. The latter blades benefit from the mounting precision of the blades which were in contact with the reference vanes, and which were fixed during the clamping step.

The figure 6 represents a platform according to a second embodiment of the invention. This figure 6 resumes the numbering of Figures 3 and 4 for identical or similar elements, however, the count is incremented by 100.

The platform 132 has a general shape of rectangle. It has transverse edges 138, and side edges 136 which each have forms of lugs 140 and 146 nodes conjugates. The lugs 140 and the notches 142 are spaced from the transverse edges 138. Their angles are rounded, they can however be salient, for example at right angles. Each of the lugs 140 comprises two support portions 148 as a function of the pivoting direction of the blade. This platform can thus provide rotational locking in both pivoting directions.

This platform 132 is longer than that shown in FIG. figure 3 . It is adapted to a blade whose wedging angle is closer to 0 °, for example less than 10 °. On this platform 132, the fixing means are also offset relative to the body of the blade. Thus, the fixing means can be deported in order to adapt to a specific turbomachine structure.

The figure 7 represents a blade platform according to a third embodiment of the invention. This figure 7 resumes the numbering of Figures 3 and 4 for identical or similar elements, however, the count is incremented by 200. Specific numbers are used for the specific elements of this embodiment.

The platform 232 has a general shape of "S" so as to be adapted to fastening means with a step to the right. It comprises three parallelograms and is symmetrical with respect to its attachment axis 234. The profile of the lateral edges 236 each have a central support portion 248 and two upstream and downstream portions 249. The upstream and downstream portions 249 are essentially parallel. and of the same length. The support portions 248 form an angle close to 45 ° with the transverse direction and are in contact with the support portions 248 of the neighboring blades. This platform configuration is adapted to fastening means whose clamping is in the clockwise direction. For clamping means in the anti-clockwise direction, it is necessary to provide inverted profiles, that is to say symmetrical to those of the figure 7 relative to the longitudinal machine direction.

The figure 8 represents a blade platform according to a fourth embodiment of the invention. This figure 8 resumes the numbering of Figures 3 and 4 for the same or similar elements, the count however, being incremented by 300.

This platform 332 is similar to that presented in figure 3 . It comprises two generally parallel side edges 336. It has a general parallelogram shape and describes an inverted "Z". The general direction of the parallelogram is substantially parallel to the rope 344 of the dawn. By general direction is meant the direction of the long sides of the parallelogram. The platform 332 makes it possible to adapt to blades having an angle of wedge opposite to that of the figure 3 .

The platform 332 includes projecting areas 340 and cut-out areas 342 formed in its general parallelogram form. The projecting zones 340 form an acute angle with the longitudinal portions 354 of the lateral edges 336.

The figure 9 represents a blade platform according to a fifth embodiment of the invention. This figure 9 resumes the numbering of Figures 3 and 4 for identical or similar elements, however, the numbering is incremented by 400.

This platform 432 has a general parallelogram shape. It includes side edges 436 which form arches-shaped support portions 448. The side edges 436 embrace the contiguous side edges over a majority of their length. Part of their length may not be in contact with the side edge of the next blade.

The figure 10 represents a blade platform according to a sixth embodiment of the invention. This figure 10 resumes the numbering of Figures 3 and 4 for identical or similar elements, however, the numbering is incremented by 500.

The blade comprises a platform 532 and attachment means 534. The platform 532 has a general shape of "C". The shape can be an inverted "C". This platform has a symmetry with respect to a transverse plane passing through the fixing means 534.

The platform 532 includes side edges 536 and transverse edges 538. Each of the side edges 536 comprises two bearing portions 548. One is at an upstream portion of the edge and the other at a downstream portion. They have opposite inclinations, which presents the advantage that the lateral edge in question allows to bear on the adjacent edge of a neighboring blade in one direction of rotation as in the other.

Claims (15)

A blade (28) for an axial turbomachine rectifier (2), intended to be mounted on a shell in an annular row of identical blades, the blade (28) comprising a platform (32, 132, 232, 332, 432 532) with fastening means (34; 134; 234; 334; 434; 534) to the ferrule for angular adjustment of the blade, an upstream edge (38; 138; 238; 338; 438; 538); a downstream edge (38; 138; 238; 338; 438; 538) and two opposite side edges (36; 136; 236; 336; 436; 536);
characterized in that
the outline of the platform has at each of its lateral edges an angled profile adapted to engage with the contiguous edge of the platform of a blade (28) identical neighbor, to ensure angular positioning of the dawn in at least one pivoting direction. A blade (28) according to claim 1, characterized in that the bent profile has at least one bearing portion (48; 148; 248; 348; 448; 548) forming a mean angle with the axis of the turbomachine (14). ) less than or equal to 45 °, preferably less than or equal to 20 °. Blade (28) according to claim 2, characterized in that the or at least one of the bearing portions (48; 148; 248; 348; 448; 548) of the bent profile is generally straight. Blade (28) according to one of claims 2 and 3, characterized in that the upstream and downstream edges (38; 138; 238; 338; 438; 538) are generally straight and parallel, the axis (14) of the turbomachine being generally perpendicular to said edges (38). Blade (28) according to one of claims 2 to 4, characterized in that the means for fixing the platform (32, 132, 232, 332, 432, 532) comprise rotation clamping means (34; 134; 234; 334; 434; 534), arranged essentially in the center of the platform, the at least one of the bearing portions (48; 148; 248; 348; 448; 548) of the angled profile being positioned to abut on the corresponding profile of the adjacent edge of the neighboring blade when the platform pivots in the tightening direction of the fastening means. Blade (28) according to one of claims 2 to 5, characterized in that the bearing portion (48; 148; 248; 348; 448; 548) of the bent profile is part of a protruding area (40; 140; 240; 340; 440; 540) of the corresponding lateral edge (36; 136; 236; 336; 436; 536) of the platform. A blade (28) according to claim 6, characterized in that each of the side edges (36; 136; 236; 336; 436; 536) of the platform further comprises a hollow-shaped area (42; 142; 242; 342 442; 542), the projecting (40; 140; 240; 340; 440; 540) and recess-like regions (42; 142; 242; 342; 442; 542) being disposed on either side of a transverse axis passing through the pivoting center of the blade (28). Blade (28) according to one of claims 1 to 7, characterized in that the profile of each of the side edges (36; 136; 336; 436; 536) of the platform (32; 132; 332; 432; 532) has a generally straight central portion and a bearing portion (48; 148; 348; 448; 548) at an upstream or downstream position, preferably at each of the two upstream and downstream positions. Blade (28) according to one of Claims 1 to 8, characterized in that the fastening means (34; 134; 234; 334; 434; 534) comprise a stud extending from one face of the platform. said face serving as mounting face to the ferrule. An axial turbomachine rectifier (2) comprising a ferrule (30) with an inner surface, and an annular array of vanes (28) including identical platforms (32; 132; 232; 332; 432; 532) disposed side by side on the inside surface of the ferrule; characterized in that the blades according to one of claims 1 to 9, a plurality of blades (28) consecutive having at least a portion of their profile bent the same lateral side bearing on the corresponding profile of the blade (28) contiguous. Rectifier according to claim 10, characterized in that the blades (28) are in accordance with claim 5, and the platforms (32; 132; 232; 332; 432; 532) of the vanes (28) have a clearance between them. mounting mechanism corresponding to an angular positioning tolerance of the blades (28), the bent profiles of the plurality of consecutive blades being in mutual support in the clamping direction of the fastening means (34; 134; 234; 334; 434; 534). Rectifier according to one of claims 10 and 11, characterized in that the plurality of consecutive blades (28) are configured to be able to pivot more than 20 ', preferably more than 40', more preferably more than 80 ', more preferably still more than 120 'around their fixing means (34; 134; 234; 334; 434; 534) when the latter are not tight. A method of mounting an annular array of vanes (28) on an axial turbomachine stator shroud (30) (2), the vanes according to one of claims 1 to 9 and according to claim 5, characterized in that he understands the steps of: - (a) mounting a reference blade (28A) substantially according to the final angular positioning of said row, - (b) successively placing a plurality of the blades (28) on the shell so as to form said blade row with the reference blade (28A), - (c) successively clamping the fastening means (34) of the plurality of vanes (28) starting from the reference vane (28A), so as successively to bring the or at least one of the bearing portions ( 48; 148; 248; 348; 448; 548) of the bent profile of each of said vanes resting on the corresponding contiguous profile of the preceding blade. The method of claim 13, characterized in that step (b) covers only a portion of the circumference of the rectifier, step (a) being performed at a plurality of locations of said circumference. Method according to one of claims 13 and 14, characterized in that the reference blade is a false blade corresponding to at least two contiguous blades, and in that the method further comprises the following step: - (d) replacing the reference blade or blades false blades according to the other blades.

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