EP3584413A1 - Cast and shrink-fit annular part of an aircraft turbine engine - Google Patents

Abstract

Part (10) for a turbomachine, this part having a generally annular shape around an axis of revolution, this part comprising a first annular flange (18) for fixing by shrinking and comprising an annular row of screw passage orifices ( 24), this part being produced by foundry and comprising projecting studs necessary for the control and the production of the part by foundry, characterized in that said studs are located on said flange and each comprise a tapping configured to cooperate with a screw flange extraction.

Description

TECHNICAL AREA

The present invention relates to an annular foundry and hooped part of an aircraft turbomachine

STATE OF THE ART

State of the art includes documents EP-A1-3 048 270 , WO-A1-2016 / 051080 and EP-B1-1 931 589 .

An aircraft turbomachine comprises several annular parts, such as for example casings, abradable coating supports, etc., which are coaxial and extend around the longitudinal axis of the turbomachine, which is generally coincident with the axis of rotation of its main rotor or its main rotors.

The housings and the abradable supports must be well centered and tight between them. For this, they are mounted hooped with each other. This is particularly important for abradable supports which provide a seal between moving and fixed parts of the engine.

To dismantle these parts, it is known to equip them with extraction sockets. These sockets are installed at regular intervals on annular flanges for fixing the parts. Dedicated screws for extracting the parts are screwed into these sockets to disassemble the parts from one another. The screws are in fact used so that the tightening torque of the screws is transformed into an extraction force sufficient to overcome the tightening forces of the parts associated with hooping.

These extraction sockets are generally attached and fixed by crimping on the flanges, next to the orifices provided on this flange for the passage of the fixing screws of this flange. This is particularly the case of parts which are produced by forging.

However, certain parts of a turbomachine can be produced by a foundry. In this case, the foundry operation requires the presence of specific studs protruding from the parts which have a double function. These pads first serve as a reference for controlling the part after manufacture, and also serve during the manufacture of the part. These studs must therefore be kept during the life of the part. They are, however, relatively bulky and should ideally be located on the flange of the part to meet the needs of the foundry.

However, it is currently very difficult or even impossible, for reasons of space, to have on a same flange of a piece obtained from foundry orifices for the passage of fixing screws (bolted connections), extraction sleeves, foundry studs, or even also other members such as stiffening ribs.

This problem is accentuated when more than two flanges are applied and fixed between them. In such a case, one of the hooped flanges must comprise extraction sockets as well as notches for passage of extraction sockets of another flange on which this flange is hooped.

The present invention provides a simple, effective and economical solution to this problem.

STATEMENT OF THE INVENTION

The invention relates to a part for a turbomachine, this part having a generally annular shape around an axis of revolution, this part comprising a first annular flange for fixing by shrinking and comprising an annular row of screw passage orifices, this part being produced by foundry and comprising projecting studs necessary for the control and the production of the part by foundry, characterized in that said studs are located on said flange and each comprise a thread configured to cooperate with an extraction screw of the flange.

The invention is advantageous because it makes it possible to integrate the function of the extraction sockets of the prior art with foundry studs. The part therefore does not need extraction sleeves strictly speaking, this which frees up space on its hoop fastening flange. The studs thus have a double function.

• la pièce porte un revêtement annulaire abradable,
• la bride comprend une première face radiale d'appui sur une autre bride, et une face cylindrique radialement interne de frettage sur une portée cylindrique radialement externe de cette autre bride,
• les plots sont en saillie sur une seconde face radiale, opposée à ladite première face radiale d'appui.

The part according to the invention may include one or more of the following characteristics, taken in isolation from one another or in combination with one another:

• the part has an abradable annular coating,
• the flange comprises a first radial face for bearing on another flange, and a radially internal cylindrical face for hooping on a radially external cylindrical bearing surface of this other flange,
• the studs are projecting on a second radial face, opposite to said first radial bearing face.

The invention also relates to an assembly comprising a part as described above, and a first annular element extending around said axis, the first flange of the part being hooped and applied axially against a second annular flange of this first element. so that the threads of said studs are aligned with through holes of the second flange, these holes having a diameter smaller than that of said threads.

• l'ensemble comprend un seconde élément annulaire s'étendant autour dudit axe et comportant une troisième bride frettée et appliquée axialement contre la deuxième bride, du côté opposé à la première bride, de façon à ce que les taraudages et lesdits trous traversants soient alignés avec des trous borgnes de la troisième bride, ces trous ayant un diamètre supérieur à celui desdits trous traversants,
• lesdits trous traversants et/ou lesdits trous borgnes sont non taraudés,
• ledit premier élément est un support de paliers et/ou ledit second élément est un carter de turbine,
• l'ensemble comprend une cavité annulaire située à l'interface entre la première bride et la deuxième bride, et ladite cavité est configurée pour relier chaque taraudage desdits plots au trou de la deuxième bride,
  • ladite cavité comprend une demi-portion en creux sur une face radiale aval de la deuxième bride et une autre demi-portion en creux sur la première face radiale d'appui de la première bride,
  • ladite deuxième bride a une épaisseur prédéterminée E destinée à être supérieure à une longueur L1 d'un prolongement de la vis.

The assembly according to the invention may include one or more of the following characteristics, taken in isolation from one another or in combination with one another:

• the assembly comprises a second annular element extending around said axis and comprising a third hooped flange and applied axially against the second flange, on the side opposite to the first flange, so that the threads and said through holes are aligned with blind holes in the third flange, these holes having a diameter greater than that of said through holes,
• said through holes and / or said blind holes are not tapped,
• said first element is a bearing support and / or said second element is a turbine casing,
• the assembly includes an annular cavity situated at the interface between the first flange and the second flange, and said cavity is configured to connect each tapping of said studs to the hole of the second flange,
  • said cavity comprises a hollow half-portion on a radial face downstream of the second flange and another hollow half-portion on the first radial support face of the first flange,
  • said second flange has a predetermined thickness E intended to be greater than a length L1 of an extension of the screw.

The present invention also relates to an aircraft turbomachine, comprising a part or an assembly as described above.

1. a) insertion d'une vis d'extraction dans le taraudage de chacun des plots de la pièce,
2. b) vissage des vis d'extraction dans les taraudages jusqu'à ce que leurs extrémités libres prennent appui sur la deuxième bride,
3. c) poursuite du vissage des vis d'extraction de façon à ce que le couple de serrage de la vis génèrent une force d'extraction de la pièce par rapport à la deuxième bride et au premier élément,
4. d) retrait de la pièce.

The present invention finally relates to a method for dismantling a part in an assembly as described above, comprising the steps of:

1. a) insertion of an extraction screw into the thread of each of the studs of the part,
2. b) screwing the extraction screws into the threads until their free ends bear on the second flange,
3. c) continued screwing in of the extraction screws so that the tightening torque of the screw generates a force for extracting the part with respect to the second flange and to the first element,
4. d) removal of the part.

• avant l'étape a),
  une étape de (i) montage d'une butée sur l'extrémité libre de chacune des vis d'extraction, de façon à les rallonger,
• entre les étapes a) et c), des étapes de
  • (ii) vissage des vis d'extraction dans les taraudages jusqu'à ce que les butées prennent appui sur la troisième bride,
  • iii) poursuite du vissage des vis d'extraction de façon à ce que le couple de serrage de la vis génèrent une force d'extraction de la pièce et du premier élément par rapport à la troisième bride et au deuxième élément,
  • (iv) retrait de la pièce et du premier élément.

The method can further comprise:

• before step a),
  a step of (i) mounting a stop on the free end of each of the extraction screws, so as to lengthen them,
• between stages a) and c), stages of
  • (ii) screwing the extraction screws into the threads until the stops bear on the third flange,
  • iii) further tightening of the extraction screws so that the tightening torque of the screw generates a force for extracting the part and the first element relative to the third flange and to the second element,
  • (iv) removal of the part and the first element.

The extraction screw used in step c) may include the stop and an extension having a predetermined length L1 which is configured to pass through the threads and part of the holes. Preferably, the stop and the extension have a total predetermined length L2.

DESCRIPTION OF THE FIGURES

• la figure 1 est une vue schématique partielle en coupe axiale d'une turbomachine d'aéronef,
• la figure 2 est une vue schématique partielle en perspective d'une bride annulaire d'une pièce selon la technique antérieure,
• la figure 3 est une vue schématique partielle en perspective d'une bride annulaire d'une pièce selon l'invention,
• la figure 4 est une vue très schématique en coupe axiale et en perspective de brides frettées selon une ensemble conforme à l'invention,
• les figures 5a à 5e sont des vues très schématiques en coupe axiale de l'ensemble de la figure 4, et illustrent des étapes de démontage et en particulier d'extraction d'une première bride, et
• les figures 6a à 6h sont des vues très schématiques en coupe axiale de l'ensemble de la figure 4, et illustrent des étapes de démontage et en particulier d'extraction d'une deuxième bride puis d'une première bride.

The invention will be better understood and other details, characteristics and advantages of the invention will appear on reading the following description given by way of non-limiting example and with reference to the appended drawings in which:

• the figure 1 is a partial schematic view in axial section of an aircraft turbomachine,
• the figure 2 is a partial schematic perspective view of an annular flange of a part according to the prior art,
• the figure 3 is a partial schematic perspective view of an annular flange of a part according to the invention,
• the figure 4 is a very schematic view in axial section and in perspective of hooped flanges according to an assembly according to the invention,
• the figures 5a to 5e are very schematic views in axial section of the whole of the figure 4 , and illustrate steps for dismantling and in particular for extracting a first flange, and
• the figures 6a to 6h are very schematic views in axial section of the whole of the figure 4 , and illustrate steps for dismantling and in particular for extracting a second flange and then a first flange.

DETAILED DESCRIPTION

The figure 1 is a partial schematic view of a turbomachine and more precisely of a rear or downstream portion of the turbomachine, the upstream and downstream expressions taking into account the flow of gases in the turbomachine. In the case of a conventional turbomachine, for example with double body and double flow, the gases flow from a blower inside a nacelle towards the inside and around a gas generator which successively comprises low pressure and high pressure compressors, a combustion chamber, high pressure and low pressure turbines, and a gas ejection nozzle.

In the figure 1 , references 10, 12 and 14 respectively designate an annular support for abradable coating, an annular support for bearings, and an internal casing of the high pressure turbine.

These three annular parts are centered on the longitudinal axis of the turbomachine and are assembled to each other by shrinking and fixing of flanges.

The support 10 has a generally cylindrical shape in the example shown and carries an abradable annular coating 16 at its downstream end. The support 10 comprises at its upstream end a first flange 18. The flange 18 comprises two radial faces, respectively upstream 18a of support and downstream 18b, and a radially internal cylindrical surface 18c of hooping. The face 18a and the surface 18c are connected to each other.

The support 12 has a generally frustoconical shape flared upstream in the example shown, and is here surrounded by the support 10. It comprises at its upstream end a second flange 20. The flange 20 comprises two radial faces, respectively upstream 20a and downstream support 20b, as well as two cylindrical bearing surfaces, respectively upstream 20c and downstream 20d, of hooping. The face 20a and the bearing surface 20c are connected together, and the face 20b and the bearing surface 20d are connected together ( figure 4 ).

The casing 14 has a generally frustoconical shape flared downstream in the example shown and comprises at its upstream end a third flange 22. The flange 22 comprises two radial faces, respectively downstream 22b of support and upstream 22a, and a surface radially internal cylindrical hoop 22c. The face 22b and the surface 22c are connected to each other ( figure 4 ).

The flanges 18, 20 and 22 comprise aligned orifices for the passage of fixing screws 24, the heads 24a of which bear, for example, on the downstream radial face 18b of the first flange 18, and the threaded bodies of which receive nuts 24b which bear on the upstream radial face 22a of the third flange 22 ( figure 4 ).

In addition to being fixed by bolting, the flanges 18, 20, 22 are hooped, that is to say that they are fixed together by radial tightening one on the other. For this, the part intended to be fixed on another part is heated to expand it and facilitate its engagement on the other part. When it cools, the part retracts and tightens radially against the other part.

In the example shown, the flange 18 is hooped by its surface 18c on the surface 20d of the flange 20, and the flange 22 is hooped by its surface 22c on the surface 20c of the flange 20.

The flange 20 is interposed between the flanges 18, 22 and its radial faces 20a, 20b are supported on the flanges 22, 18 respectively and therefore does not include projections.

According to the invention, one of the other parts such as for example the support 10 is made of foundry and comprises on its downstream radial face 18b of the studs 26 projecting (visible at the figure 3 ) which are necessary for checking the part and for manufacturing the part. The studs 26 have a generally parallelepiped shape in the example shown.

Furthermore, due to the mounting by hooping of the flanges 18, 20, 22, these flanges must be equipped with extraction means, that is to say means capable of generating a sufficient axial separation force between two parts in order to to extract them from each other by straightening them.

Conventionally, these extraction means comprise attached sockets 28, visible at the figure 2 . These sockets 28 are mounted crimped in holes in a flange and receive screws which are intended to bear on a flange adjacent to the flange carrying the sockets, so as to apply the above-mentioned spacing force.

According to the invention, the flange which carries the studs 26 does not comprise extraction sockets 28 because the function of these sockets is integrated into the pads. The studs 26 indeed include threads 30 for screwing in the extraction screw, as can be seen on the figure 3 .

The threads 30 are through and threaded to cooperate with the extraction screws which are intended to bear on at least one of the other flanges 20, 22 of the assembly. The internal threads 30 are oriented axially, that is to say parallel to the axis of revolution and of the assembly of the parts. The extraction screws are screwed from downstream into the threads 30 in the example shown.

The figures 5a to 5e illustrate steps for dismantling a first embodiment of a method according to the invention, only the support 10 being dismantled and therefore separated from the other two parts (support 12 and casing 14).

Each extraction screw 32 has a generally cylindrical shape and comprises a threaded body 32b of which a longitudinal end is connected to a drive head 32c and of which an opposite longitudinal end comprises an axial extension 32a having a diameter less than that of the body.

It can be seen that the flange 20 comprises through holes 34 aligned with the threads 30 of the flange 18. These holes 34 are not threaded and have an internal diameter smaller than that of the threads 30, and between the diameter of the extension 32a and the diameter of the body 32b of the screw 32. It is also found that each tapping 30 is connected to a hole 34 by an annular cavity 36 which is located at the interface between the flanges 18, 20. This cavity 36 has a diameter greater than the diameters of the hole 34 and of the internal thread 30 and comprises a half-portion formed by a recess on the downstream radial face 20b of the flange 20 and another half-portion formed by a recess on the upstream radial face 18a of the flange 18 ( figure 4 ).

The flange 22 comprises blind holes 38 aligned with the holes 34 and the internal threads 30. These holes 38 are not threaded and here have an internal diameter greater than the internal diameter of the holes 34.

The internal threads 30 are for example three in number regularly distributed around the axis of the support 10. It is therefore understood that the flange 20 comprises in this case three holes 34 and that the flange 22 comprises three holes 38.

Each screw 32 is first aligned on the axis of a thread 30 then engaged by its extension 32a in this thread 30 ( Figures 5a and 5b ). The screw is screwed into the thread by means of a suitable tool engaged with the drive head 32c, until the extension 32a engages in the hole 34 and the end of the body 32b connected to the extension take support on the bottom of the hollow of the downstream radial face 20b of the flange 20 ( figures 5c and 5d ).

It then suffices to apply a sufficient tightening torque to the screw 32 so that an extraction force is applied to the support (arrow F1) for the axial spacing of the flanges 18, 20 until the surface 18c of the flange is no longer in contact with the bearing surface 20d of the flange 20.

This operation can here be made possible by the fact that the extension 32a has a length L1 less than the thickness E of the flange 20 (and more exactly, L1 is less than the thickness E 'remaining between the bottom of the forming recess of the cavity 36 on the face 20b, and the opposite face 20a - figure 5d ) and does not risk coming into contact with the flange 22 during screwing. It is further understood that, for the sole disassembly of the support 10, this extension 32a is not compulsory since it has no particular utility during this extraction.

The figures 6a to 6h illustrate another embodiment of the method according to the invention which here consists of extracting the flanges 18, 22 from the flange 20 and therefore completely dismantling the assembly.

For this, the same screw 32 is used but is here equipped with a stop 40 which is removably mounted on the extension 32a. This stop has a generally cylindrical shape and is axially aligned on the extension 32a and the body 32b of the screw, the external diameter of this stop being similar to that of the extension and therefore less than that of the body.

Preferably, the total length L2 of the stop 40 and the extension 32a is greater than the thickness E (E ') of the flange 20 so that the stop and the extension can be engaged in the hole 34 and pass through it .

Each screw 32 is first aligned with the axis of a tapping 30 and then engaged by its extension 32a in this tapping 30 ( Figures 6a and 6b ). The screw is screwed into the internal thread until the stop 40 and the extension 32a engage in the hole 34 and this stop bears on the bottom of the blind hole 38 of the downstream radial face 22b of the flange 22 ( figures 6c and 6d ).

It then suffices to apply a sufficient tightening torque to the screw 32 so that an extraction force is applied to the support (arrow F2) for the axial spacing of the flanges 18, 20, on the one hand, the flange 22, on the other hand, until the surface 22c of the flange 22 is no longer in contact with the bearing surface 20c of the flange 20.

The screw 32 is screwed back into the internal thread 30 until the end of the body 32b connected to the extension 32a bears on the downstream radial face 20b of the flange 20 ( figures 6g ).

It then suffices to apply a sufficient new tightening torque to the screw 32 so that an extraction force is applied to the support (arrow F1) for the axial spacing of the flanges 18, 20, until the surface 18c of the flange 18 is no longer in contact with the bearing surface 20d of the flange 20 ( figure 6h ).

Claims (15)

Part (10) for a turbomachine, this part having a generally annular shape around an axis of revolution, this part comprising a first annular flange (18) for fixing by shrinking and comprising an annular row of screw passage holes ( 24), this part being produced by foundry and comprising studs (26) projecting necessary for the control and the production of the part by foundry, characterized in that said studs are located on said flange and each include a thread (30) configured to cooperate with a flange extraction screw (32). Part (10) according to claim 1, wherein the part carries an abradable annular coating (16). Piece (10) according to claim 1 or 2, wherein the flange (18) comprises a first radial face (18a) bearing on another flange (20), and a radially internal cylindrical face (18c) hooping on a radially outer cylindrical bearing surface (20d) of this other flange. Piece (10) according to claim 3, in which the studs (26) project on a second radial face (18b), opposite to said first radial bearing face (18a). Assembly comprising a part (10) according to one of the preceding claims, and a first annular element (12) extending around said axis, the first flange (18) of the part (10) being hooped and applied axially against a second annular flange (20) of this first element (12) so that the threads (30) of said studs (26) are aligned with holes (34) passing through the second flange, these holes having a diameter smaller than that of said threads. Assembly according to claim 5, in which it comprises a second annular element (14) extending around said axis and comprising a third flange (22) hooped and applied axially against the second flange (20), on the side opposite to the first flange (18), so that that the internal threads (30) and said through holes (34) are aligned with blind holes (38) of the third flange, these blind holes having a diameter greater than that of said through holes. An assembly according to claim 5 or 6, wherein said through holes (34) and / or said blind holes (38) are unthreaded. Assembly according to one of claims 5 to 7, in which said first element is a bearing support (12) and / or said second element is a turbine casing (14). Assembly according to one of claims 5 to 8, characterized in that it comprises an annular cavity (36) situated at the interface between the first flange (18) and the second flange (20), and said cavity (36) is configured to connect each thread (30) of said studs (26) to the hole (34) of the second flange (20). Assembly according to claim 9, characterized in that said cavity (36) comprises a hollow half-portion on a downstream radial face (20b) of the second flange (20) and another hollow half-portion on the first radial face support (18a) of the first flange (18). Assembly according to one of claims 5 to 10, characterized in that said second flange (20) has a predetermined thickness E intended to be greater than a length L1 of an extension (32a) of the screw (32). Aircraft turbomachine, comprising a part according to one of claims 1 to 4 or an assembly according to one of claims 5 to 8. Method for dismantling a part (10) in an assembly according to one of claims 5 to 8, comprising the steps of: a) insertion of an extraction screw (32) into the thread (30) of each of the studs (26) of the part, b) screwing the extraction screws into the threads until their free ends bear on the second flange (20), c) continued screwing in of the extraction screws so that the tightening torque of the screw generates a force for extracting the part relative to the second flange and to the first element (12), d) removal of the part (10). The method of claim 10, further comprising - before step a),
a step of (i) mounting a stop (40) on the free end of each of the extraction screws (32), so as to lengthen them, - between stages a) and c), stages of (ii) screwing the extraction screws into the threads (30) until the stops bear on the third flange (22), iii) further tightening of the extraction screws so that the tightening torque of the screw generates a force for extracting the part and the first element (12) relative to the third flange (22) and to the second element (14), (iv) removal of the part (10) and the first element (12). Method according to claim 14, characterized in that the extraction screw (32) used in step c) comprises the stop (40) and an extension (32a) having a predetermined length L1 which is configured to pass through the threads ( 30) and part of the holes (34); and in that the stop (40) and the extension (32a) have a total predetermined length L2.

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