TOOL FOR CENTERING AN ANNULAR PART

Abstract

The invention relates to a centering tool (10) for centering an annular part (42) around a hub (41) comprising: a body (11) having a central axis (X), suitable for being fixed to the hub, a plurality of centering arms (20) movable in radial translation relative to the central axis (X) and respectively having a radial extension along an extension axis (B) relative to the central axis (X), suitable for coming to bear on an internal annular surface (42a) of the annular part (42), and an adjustment element (15) carried by the body (11) and connected to the centering arms (20), so as to be able to adjust a radial position of each of the centering arms relative to the central axis. Fig. for the abstract: Fig. 3

Description

Title of the invention: TOOL FOR CENTERING AN ANNULAR PART Technical field of the invention

[0001] The invention relates to the field of tools for centering an annular part around a hub. The invention also relates to a method for centering an annular part around a hub. Technical background

[0002] An aircraft turbomachine typically has a longitudinal axis and comprises, for example, from upstream to downstream in a gas flow direction along the longitudinal axis, a fan, a low pressure compressor, a high pressure compressor, a combustion chamber, a high pressure turbine, a low pressure turbine and a gas exhaust nozzle.

[0003] The low pressure compressor and the high pressure compressor respectively comprise a rotor connected to the rotor of the high pressure turbine or the low pressure turbine via a shaft, so as to form a rotating body.

[0004] The rotor of the high-pressure compressor is thus connected to the rotor of the high-pressure turbine by a high-pressure shaft to form a high-pressure body. The rotor of the low-pressure compressor is thus connected to the rotor of the low-pressure turbine by a low-pressure shaft to form a low-pressure body, the low-pressure body being able to drive, directly or via a reducer, a rotor of the fan commonly called a fan.

[0005] Figures 1a and 1b respectively represent a longitudinal sectional view and a detail of such a longitudinal section of a turbomachine of the double-flow double-body type. More particularly, Figures 1a and 1b represent a part of a turbomachine 2, in which a fan 3, a low-pressure compressor 4 and a high-pressure compressor 5 are visible.

[0006] The blower 3 allows the suction of an air flow F, which can be divided into a primary flow F1 and a secondary flow F2. The primary flow F1 passes through a primary vein VI of the turbomachine 2 while the secondary flow F2 is directed towards a secondary vein V2, surrounding the primary vein VL.

[0007] The primary flow Fl is compressed within the low-pressure compressor 4 and the high-pressure compressor 5. The compressed primary flow Fl is then mixed with a fuel and burned within a combustion chamber. Gases from the combustion pass through turbines and then escape through a nozzle whose section allows acceleration of the gases to generate propulsion.

[0008] The fan 3 typically comprises a disk 6 movable in rotation around a longitudinal axis A-A' of the turbomachine 2 and blades 35 mounted on the disk 6. The blades 35 are surrounded by a fan casing 30, centered on the longitudinal axis A-A' and intended in particular to retain the blades 35 in the event of rupture.

[0009] The fan casing 30 is typically surrounded by a nacelle making it possible to give an aerodynamic profile to an assembly thus constituted. In such a configuration, the fan 3 is said to be ducted, as opposed to non-ducted fans, because the blades 35 are surrounded by the fan casing 30.

[0010] The turbomachine 2 further comprises an intermediate casing 40, located downstream of the fan casing 30, and between the low-pressure compressor 4 and the high-pressure compressor 5. The intermediate casing 40 typically comprises a hub 41, centered on the longitudinal axis A-A', and an annular outer shroud 42, arranged coaxially around the hub 4L. In addition, the annular outer shroud 42 is fixed downstream of the fan casing 30 and defines, with the hub 41, a portion of the secondary vein V2. Furthermore, the intermediate casing 40 further comprises radial arms 45 connecting the hub 41 to the annular outer shell 42. The radial arms 45 cross the secondary vein V2 and, in operation, the secondary flow F2 passes through the radial arms 45, also called “OGV” arms, an acronym for the English expression “Outlet Guide Vanes”.

[0011] The hub 41 of the intermediate casing 40 comprises an annular inner skin 44, centered on the longitudinal axis A-A', and an annular outer skin 43, arranged coaxially around the inner skin 44. The annular outer skin 43 defines, with the annular inner skin 44, a portion of the primary vein V1 located at the outlet of the low-pressure compressor 4 and supplying the high-pressure compressor 5.

[0012] The hub 41 of the intermediate casing is thus located between the low pressure compressor 4 and the high pressure compressor 5.

[0013] The hub 41 of the intermediate casing 40 generally serves as a support for centering bearings 50 ensuring guidance of the rotor of the low pressure compressor 4 and of the blower 3.

[0014] The different elements of the turbomachine 2 are generally arranged in several modules, previously manufactured independently of one another, then assembled together along the longitudinal axis A-A' in order to facilitate the manufacture and assembly of the turbomachine 2. The assembly of these different modules must take into account the tolerance constraints of the different parts constituting them.

[0015] As shown in [Fig.lb], the blades 35 are separated from the fan casing 30 by radial clearances J which must meet very precise and limited specifications due to their risks of multiple impacts. Radial clearances J which are too large will have an impact on the operability and on the performance of the turbomachine 2, while that radial clearances J that are too small entail increased mechanical risks given the contacts between the blades 35 and the fan casing 30 as well as the risks of wear.

[0016] In practice, the radial clearances J result from a chain of dimensions which includes several parts whose manufacturing and assembly tolerances can have a significant impact on the radial clearances J. However, in terms of orders of magnitude, the radial clearances J should, preferably, be adjusted with precision to the nearest hundredth of a millimeter.

[0017] Although attempts have already been made to limit such tolerances, for example by using specific tools for assembly, the proposed solutions have proved inconclusive.

[0018] However, to the extent that the fan casing 30 is fixed to the intermediate casing 40, the existence of excessive clearances essentially results from poor positioning of the intermediate casing 40 around the hub 41 and, more particularly, from inappropriate centering of the annular outer shell 42 of the intermediate casing 40 around the hub 41.

[0019] Fig. 2 is a schematic view of a casing following a misalignment of an outer annular hub around a shaft of a turbomachine. More specifically, Fig. 2 illustrates the consequences of such a situation on the centering of a casing line, i.e. a structure formed by an assembly of the blower casing 30 and the outer annular hub 42 of the intermediate casing 40, with respect to the blades 35.

[0020] In the situation schematically illustrated in Fig. 2, the outer annular hub 42 of the intermediate casing 40 has a slight inclination with respect to the longitudinal axis A - A' and thus with respect to the axis of rotation of the shaft 41. Incidentally, the blower casing 30 is thus not axially aligned with the longitudinal axis A - A' of the turbomachine 2.

[0021] Such misalignment of the fan casing 30 is even more marked than that of the annular outer shroud 42 since the fan casing 30 is further from the hub 41 than the intermediate casing 40.

[0022] The consequence of such a tilting of the casing line relative to the hub 41 is an increase in the clearances between the blades 35 and the fan casing 30.

[0023] There is therefore a need to find an effective solution for centering the casing line around the blades 35.

[0024] Several solutions could be used to center the annular outer ferrule 42 around the hub 41, and thus allow the correct positioning of the casing line relative to the blades 35.

[0025] A first solution would consist of centering the external ferrule annular 42 taking as a reference the rotor line, and in particular the disk 6 of the fan 3. The first solution would allow precise centering, that is to say of the order of a hundredth of a millimeter. However, such a first solution would not always be applicable, in particular for reasons of accessibility of the disk 6 of the fan 3.

[0026] A second solution could consist of centering the annular outer shell 42 by taking the hub 41 as a reference, as illustrated in [Fig.2]. The annular outer shell 42 would then be docked and centered on the hub 4L. Such a second solution is more delicate than the first solution described previously because the chain of dimensions between the fan 3 and the hub 41 highlights numerous contributions, in particular due to the tolerances of the parts, which makes the control of the radial clearances J between the blades 35 and the fan casing 30 more sensitive and generating more dispersion.

[0027] The invention proposes to solve the problem mentioned above by centering the annular external shell 42 around a hub 41 of a turbomachine, in a simple, efficient and economical manner. Summary of the invention

[0028] The invention proposes in this regard a tool for centering an annular part, such as an annular external ferrule, in particular around a hub, characterized in that it comprises: - a body comprising a central axis, capable of being fixed to the hub, - a plurality of centering arms movable in radial translation relative to the central axis and respectively having a radial extension along an extension axis relative to the central axis, capable of coming to bear on an internal annular surface of the annular part, and - an adjustment element carried by the body and connected to the centering arms, so as to be able to adjust a radial position of each of the centering arms relative to the central axis.

[0029] The centering tool according to the invention makes it possible to overcome the drawbacks of the prior art. Indeed, the centering tool of the invention comprises a plurality of centering arms which can move radially using an adjustment element carried by the body. The invention therefore makes it possible to center a casing line including the centering shroud, with respect to fan blades, and thus to optimize the radial clearances at the tips of the fan blades. Naturally, the invention can be applied to any other environment or module in a turbomachine.

[0030] According to different characteristics of the invention which can be taken together or separately: • the centering arms are distributed around the central axis and connected to the body; • the centering arms respectively adopt the same radial position vis- opposite the central axis; • the adjustment element ensures a synchronous adjustment of the radial position of each of the centering arms relative to the central axis; • the centering arms are connected to the body by a sliding connection, in particular along the extension axis of the centering arm; • the adjustment element is a wheel which can rotate around the central axis; • at least one centering arm comprises at least one slot cooperating with a pin arranged on the body; • the body comprises at least one slot cooperating with at least one pin arranged on at least one of the centering arms; • at least one centering arm comprises an external radial end, capable of coming to bear on an internal annular surface of the annular part; • the outer radial end of the centering arm has an elastomer stop; and / or • the centering arms are regularly spaced around the adjustment element; • each of the centering arms is formed by a radially elongated tab; • the body includes a disc; • the centering arms are mounted on a circular face of the disc; and / or • the centering tooling includes between two and ten centering arms, in particular between four and eight centering arms.

[0031] The invention further relates to an assembly comprising a turbomachine and a centering tool as described previously, the turbomachine comprising a stator hub, as a means according to the invention, and an annular external shell, as an annular part according to the invention, located around the stator hub, the annular external shell having a diameter greater than a diameter of the body of the centering tool.

[0032] In such a case, the stator hub is connected by radial arms to the annular outer shell to form an intermediate casing of the turbomachine.

[0033] The invention also relates to a method for centering an annular part around a hub, by means of a centering tool as described previously. More specifically, the centering method comprises at least - a positioning step, during which the centering tool is centered and fixed on the hub; - a deployment step, during which centering arms of the centering tool are moved radially outwards; and - a centering step, during which external radial ends of the centering arms of the centering tool bear on an internal annular surface of the annular part.

[0034] More specifically, the annular casing is a fan casing. In such a case, the assembly further comprises a fan surrounded by the fan casing and driven in rotation by a shaft guided by at least one bearing carried by the stator hub.

[0035] Preferably, the deployment step and the centering step are performed by rotating an adjustment element in a rotational direction around a central axis of the centering tool. Brief description of the figures

[0036] The present invention will be better understood and other objects, characteristics and advantages will appear even more clearly on reading the detailed description which follows, comprising embodiments given by way of illustration with reference to the appended figures, presented as non-limiting examples, which may serve to complete the understanding of the present invention and the description of its embodiment and, where appropriate, contribute to its definition, in which: - [Fig. 1a] is a longitudinal sectional view of a double-spool turbomachine having, among other things, a low-pressure compressor of the turbomachine; - [Fig. 1b] is a detailed view of the longitudinal section of the turbomachine illustrated in [Fig. 1a]; - [Fig.2] is a schematic view of a casing following incorrect positioning of an external annular shroud around a turbomachine hub; - [Fig.3] illustrates a centering tool, according to an embodiment of the present invention, in the retracted position; - [Fig.4] illustrates the centering tool of [Fig.3] in the support position; - [Fig.5] illustrates a centering arm of the centering tool according to a mode of carrying out the present invention; - [Fig.6] illustrates a device for adjusting the centering tool according to the invention; and - [Fig.7] illustrates a flowchart of a method of centering an annular part around a hub according to the invention. Detailed description of the invention

[0037] The turbomachine 2 is preferably a double-flow double-spool turbomachine generally used in aircraft. However, the invention is not limited to double-flow double-spool turbomachines and applies to any type of turbomachine. Thus, the present description will be made by taking as an illustrative example the case of the double-flow double-spool turbomachine.

[0038] The general structure of the turbomachine 2 has been described in the preamble in relation to figures 1a and 1b.

[0039] A centering tool 10 according to the invention aims in particular to allow centering of a casing line, constituted by an assembly of the fan casing 30 and the annular external shroud 42 of the intermediate casing 40, relative to blades 35 of the fan 3.

[0040] The centering tool 10 according to the invention aims, in particular, to allow appropriate positioning of the fan casing 30 relative to the blades 35 of the fan 3 in order to reduce radial clearances J between the fan casing 30 and the blades 35.

[0041] The casing line therefore comprises at least the fan casing 30 and the annular external shroud 42 fixed to the fan casing 30, the annular external shroud 42 forming, in particular, part of the intermediate casing 40.

[0042] In the context of the invention, the centering of the casing line is thus achieved by centering the annular external ferrule 42 on the hub 4L.

[0043] The invention thus achieves the centering of the fan casing 30 relative to the blades 35 by means of a centering of the annular external shroud 42 around the hub 41 of the turbomachine 2, preferably to within a hundredth of a millimeter.

[0044] The centering of the annular external ferrule 42 is carried out by the centering tool 10 according to the invention.

[0045] [Fig. 3] illustrates the centering tool 10, according to an embodiment of the present invention, in the retracted position. The centering tool 10 makes it possible to ensure centering of an annular part 42 around a means 4L

[0046] In the illustrative example presented, with reference to [Fig. 3], the centering tool 10 is applied to an annular external shell 42 of a turbomachine 2, as an annular part 42, intended to be centered around a hub 41 of the turbomachine 2, the casing and the hub 41 being able to form part of the same module of the turbomachine 2.

[0047] More specifically, the centering tool 10 according to the invention comprises a body 11 comprising a central axis X. The centering tool 10 is configured to be fixed on the hub 4L

[0048] In use, that is to say when centering of the annular external shell 42 is carried out around the hub 41, the central axis X of the centering tool 10 also corresponds to the longitudinal axis A-A' of the turbomachine 2.

[0049] In the embodiment illustrated in [Fig.3], the body 11 comprises a support 12, in particular in the form of a disc, on which various constituent elements of the centering tool 10 are intended to be mounted.

[0050] The support 12 is centered on the central axis X of the centering tool 10, the latter passing through it perpendicularly.

[0051] According to a particular embodiment presented in [Fig. 3], the support 12 has the shape of a disc having a diameter smaller than the diameter of the annular external ferrule 42 intended to be centered around the hub 41.

[0052] The interest of such a configuration will be better understood in the remainder of this description.

[0053] In addition, the centering tool 10 according to the invention comprises a plurality of centering arms 20 distributed around the central axis X and connected to the body 11. More particularly, the centering arms 20 are configured to bear simultaneously on an internal annular surface 42a of the annular external ferrule 42, so as to position precisely, that is to say preferably to the nearest hundredth of a millimeter, the annular external ferrule 42 relative to the hub 4L.

[0054] For this purpose, each centering arm 20 has a radial extension relative to the central axis X. In addition, each centering arm 20 is movable in radial translation relative to the central axis X.

[0055] In the particular case mentioned above, the centering arms are able to move in a synchronized manner. Thus, the outer radial ends of the centering arms are always located at the same distance from the central axis at all times during their manipulation by the operator.

[0056] Thus, when the centering tool is used to center an annular part, such as an annular outer ferrule, around a hub, all the outer radial ends reach the annular part simultaneously. Such an arrangement thus makes it possible to make the positioning of the casing more reliable with respect to the centering tool and therefore to make the movement and positioning of the latter more reliable around the stator hub.

[0057] According to a particular embodiment, notably illustrated in [Fig. 3], the centering arms 20 are regularly distributed around the central axis X. Thus, the angle formed between two successive centering arms 20 is identical for all of the centering arms 20 and is constant. The centering arms 20 are therefore regularly spaced from one another around the central axis X.

[0058] According to the example presented in [Fig.3], the centering tool 10 according to the invention can comprise eight centering arms 20 regularly distributed around the central axis X and connected to the body 11. In such a configuration, the angle formed between two successive centering arms 20 is 45°.

[0059] However, while remaining within the scope of the invention, the angle between two successive centering arms 20 may vary depending on the number of centering arms 20 of the tooling. In addition, the angle between two successive centering arms 20 may not be identical for all of the centering arms 20 and may not be constant.

[0060] The centering tool 10 according to the invention may in particular comprise between two and ten centering arms 20. A minimum of two centering arms 20 is necessary to allow the centering tool 10 to rest on the internal annular surface 42a of the annular external ferrule 42.

[0061] Furthermore, it may be preferable not to exceed a number of ten centering arms 20 in order to maintain a tool that is simple to manufacture.

[0062] According to a particularly suitable embodiment, the centering tool 10 comprises between four and eight centering arms 20. Such an arrangement of the centering tool 10 makes it possible to obtain a good compromise between reliable support of the centering tool 10 on the internal annular surface 42a and simplicity of manufacture of the centering tool 10.

[0063] The centering tool 10 according to the invention may in particular comprise an odd number of centering arms 20.

[0064] The centering tool 10 according to the invention may also comprise an even number of centering arms 20. In such a configuration, the centering arms 20 may be formed in pairs, that is to say that the centering arms 20 are functionally linked two by two. Indeed, each pair may be formed by the centering arms 20 arranged symmetrically with respect to the central axis X.

[0065] According to the example presented in [Fig.3], the centering tool 10 comprises four pairs of centering arms 20, respectively: - a first pair of centering arms 20a, oriented parallel to a first radial axis Y, perpendicular to the central axis X, - a second pair of centering arms 20b, forming an angle of 45° relative to the first pair of centering arms 20a, - a third pair of centering arms 20c, forming an angle of 45° with the second pair of centering arms 20b, and - a fourth pair of centering arms 20d, forming an angle of 45° with the third pair of arms 20c.

[0066] The third pair of centering arms 20c is therefore oriented parallel to a second radial axis Z, perpendicular to the central axis X and to the first radial axis Y. The central axis X, the first radial axis Y and the second radial axis Z form an orthonormal reference frame.

[0067] More specifically, as is better seen in [Fig. 5], each centering arm 20 extends along an extension axis B and comprises an external radial end 22. The external radial end 22 is free and is able to come to bear on the internal annular surface 42a. More particularly, the external radial end 22 is a end of the centering arm 20 distal from the central axis X, that is to say the furthest from the central axis X.

[0068] According to a preferred implementation, the external radial end 22 of the centering arm 20 comprises a stop 24, in particular made of elastomer. The stop 24 makes it possible not to mark the internal annular surface 42a when the centering arm 20 comes into contact with the internal annular surface 42a of the annular external ferrule 42. In addition, the use of the stop 24 allows adjustment to the local shape tolerances of the internal annular surface 42a of the annular external ferrule 42, for example due to roughness of the annular external ferrule 42.

[0069] The centering tool 10 may further comprise an adjustment element 15 carried by the body 11 and connected to the centering arms 20 in order to allow a synchronized adjustment of the respective radial positions of the centering arms 20 relative to the central axis X.

[0070] According to a particular embodiment, the centering arms 20 of the same pair are configured to move in translation along their respective radial axis, B, in opposite directions and simultaneously. This is made possible in particular by the adjustment element 15.

[0071] Thus, when an operation of centering the annular outer ferrule 42 is implemented, the outer radial ends 22 of the centering arms 20 are configured to adopt the same distance from the central axis X at each instant during the translational movement of the centering arms 20.

[0072] Incidentally, the distance separating the external radial end 22 of the centering arms 20 from the central axis X is the same for a given pair of centering arms, in particular for all the pairs of centering arms given the centering tool 10, and / or for all the centering arms 20. Such a configuration allows the centering tool 10 according to the invention to center the annular external ferrule 42 around the hub 41, preferably to within a hundredth of a millimeter.

[0073] More specifically, the adjustment element 15 is connected to the centering arm 20 by an internal radial end 21.

[0074] [Fig. 6] illustrates an adjustment device according to the invention. More particularly, the adjustment device is produced by meshing the internal radial end 21 with the adjustment element 15.

[0075] A particular embodiment of the adjustment device is shown in [Fig.6]. The adjustment device comprises a gear 16 for providing a connection for the adjustment element 15. In the example, the gear 16 comprises a first toothed wheel 17a and a second toothed wheel 17b, meshed with each other, each being capable of rotating about a rotation shaft. The gear 16 also comprises a first rack 18a and a second rack 18b fixed on a pair of centering arm 20 given.

[0076] More specifically, the first rack 18a is meshed with the first gear wheel 17a and is fixed to a first centering arm 20 of the first pair of centering arms 20a, respectively of the second pair of centering arms 20b, of the third pair of centering arms 20c, of the fourth pair of centering arms 20d, while the second rack is meshed with the second gear wheel 17b and is fixed to a second centering arm 20, respectively of the first pair of centering arms 20a, of the second pair of centering arms 20b, of the third pair of centering arms 20c, of the fourth pair of centering arms 20d.

[0077] According to a first configuration, the first toothed wheel 17a, respectively the second toothed wheel 17b, is motorized.

[0078] When the first wheel 17a, respectively the second toothed wheel 17b, is rotated, it simultaneously drives the second wheel 17b, respectively the first toothed wheel 17a.

[0079] Thus when the first wheel 17a, respectively the second toothed wheel 17b, is rotated, it drives the first rack 18a. Concomitantly, since the second wheel 17b is driven by / drives the first wheel 17a, the second rack 18b is also driven by the movement of the first wheel 17a, respectively the second wheel 17b.

[0080] Since the first gear wheel 17a and the second gear wheel 17b rotate simultaneously, in opposite directions, the first rack 18a and the second rack 18b are caused to move simultaneously in translation in opposite directions. Such a configuration makes it possible to move the centering arms 20 of the first pair of arms 20a, respectively of the second pair of centering arms 20b, of the third pair of centering arms 20c, of the fourth pair of centering arms 20d, in translation in opposite directions.

[0081] Such a mechanism may be employed for all pairs of centering arms 20.

[0082] Alternatively, the first gear wheel 17a and the second gear wheel 17b are both motorized. In such a case, only one of the motors may be activated to actuate such a mechanism.

[0083] The centering tool 10 thus makes it possible to precisely center the annular external ferrule 42 around the associated hub 41.

[0084] It should also be noted that other gears 16 may be envisaged such as, for example, bevel gears, gears.

[0085] According to the example presented in [Fig.3], the centering arm 20 is formed by a tab of elongated shape along the extension axis B of the centering arm 20.

[0086] In addition, the centering arm 20 is thin in the sense that the centering arm 20 has a dimension considered along a transverse axis C, perpendicular to the axis extension axis B and the central axis X, less than a dimension considered along the extension axis B

[0087] The dimension of the centering arm 20 considered along the extension axis B is called “length”, while the dimension considered along the transverse axis C is called “width”.

[0088] In particular, the ratio of the width to the length of the centering arm 20 can be between 1:3 and 1:5, which advantageously makes it possible to reduce the force supported by the centering arm 20 in the radial direction.

[0089] A ratio of 1:3 means that the length of the centering arm 20 is three times the width of the centering arm 20.

[0090] According to a particular embodiment, the centering arms 20 may be identical. They therefore all have the same length and the same width. In addition, they may also be made of the same material, which allows them to withstand the same forces.

[0091] Thus, in such an arrangement, when the centering arms 20 are supported on the internal annular surface 42a, the forces are therefore distributed homogeneously around the central axis X.

[0092] Furthermore, the centering arm 20 comprises two opposite faces, separated by a thickness considered along the central axis X. The faces of the centering arm 20 are preferably flat, allowing the centering arm 20 to be in flat support on the body 11.

[0093] Advantageously, the centering arm 20 is connected to the body 11 by a sliding connection. More precisely, the centering arm 20 is capable of performing a translational movement along the body 11 along the extension axis B. Thus, the centering arm 20 is only allowed to move relative to the body 11 in one direction.

[0094] More particularly, the support 12 carries pins 13 engaged in slots 23 arranged in the centering arm 20. Conversely, the slots 23 can be engaged in the pins 13. The slots 23 and the pins 13 are configured to allow only a translational movement of the centering arm 20 relative to the body 11.

[0095] In the embodiment illustrated in [Fig. 3], the centering arm 20 comprises two slots 23 in which two pins 13 of the support 12 are configured to engage. Each slot 23 can advantageously define an opening 23a in which one of the pins 13 of the support 12 is capable of moving by a sliding connection along the extension axis B.

[0096] The number of slots 23 per centering arm 20 may be greater than two without departing from the scope of the present invention. Similarly, the number of pins 13 associated with each slot 23 may be greater than one without departing from the scope of the present invention.

[0097] Advantageously, the number of slots 23 is at least equal to two, in order to avoid tolerances associated with a slide connection formed by a slot and a single pin, or even more. Indeed, a single slide is more likely to generate tolerances in use through wear than a double slide, i.e. two slides, because of the constraints. The constraints exerted on a single slide are in fact likely to degrade it more quickly and, through wear, to cause an increase in structural defects in the centering tool 10, making it less precise over time.

[0098] It is therefore very advantageous to have a double slide, in order to distribute the force linked to the weight of the annular external ferrule 42 on the centering tool 10, when the centering arms 20 are in support against the internal annular surface 42a.

[0099] According to a particular embodiment, the adjustment element 15 is a wheel movable in rotation around the central axis X. The wheel covers the gears 16 by which it is connected to the internal radial ends 21 of the centering arms 20.

[0100] According to a particular embodiment, the centering arms 20 are regularly spaced around the central axis X and therefore around the adjustment element 15.

[0101] Such an implementation can be envisaged independently of the fact that the adjustment element 15 is a wheel, these two specificities being independent.

[0102] The adjustment element 15, as a wheel, is easily grippable and configured to allow simultaneous moving away and moving towards the first pair of centering arms 20a, respectively the second pair of centering arms 20b, the third pair of centering arms 20c, the fourth pair of centering arms 20d while performing a rotation around the central axis X.

[0103] For this purpose, the adjusting element 15 is connected to the gears 16 in a fixed manner, so that the rotational movement of the adjusting element 15 is transmitted simultaneously to the gears 16. The centering arms 20 can therefore simultaneously move along their respective extension axis B when the thumbwheel rotates around the central axis X.

[0104] The invention also relates to an assembly 1 comprising a turbomachine 2 and a centering tool 10 as previously described. As indicated, the turbomachine 2 comprises, among other things, a hub 41 and an annular external shroud 42 located around the hub 4L. The structure of the turbomachine 2 has been described in detail in the preamble to the present description.

[0105] In the context of the invention, the annular outer ferrule 42 has a diameter greater than a diameter of the body 11 of the centering tool 10. Thus, the centering tool 10 according to the invention is configured so that the centering arms 20 bear on the inner annular surface 42a of the annular outer ferrule 42, when the centering arms 20 are deployed in the radial direction, i.e. in the direction of the annular outer ferrule 42.

[0106] [Fig.7] illustrates a flowchart of a method 100 for centering an annular part 42 around a hub 41 according to the invention.

[0107] More particularly, the centering method 100 according to the invention makes it possible to ensure centering of an annular external shell 42 around a stator hub 41 of a turbomachine 2.

[0108] The centering method 100 according to the invention is implemented by means of an assembly 1 as previously described.

[0109] The centering method 100 comprises a positioning step a), during which the centering tool 10 is centered and fixed on the hub 41, in particular via the body 11. The centering carried out during the positioning step a) is a pre-alignment of the centering tool 10 relative to the hub 4L.

[0110] Once the centering tool 10 has been centered and fixed to the hub 41 at the end of the positioning step a), the centering method 100 comprises a deployment step b), during which the centering arms 20 are moved radially outwards, in particular under the action of the adjustment element 15.

[0111] More precisely, during this deployment step b), the adjustment element 15 is actuated so that it rotates around the central axis X. Concomitantly with the movement of the adjustment element 15 around the central axis X, the centering arms 20 move in translation along their respective radial axis B.

[0112] Consequently, the centering method 100 comprises a centering step c), during which the external radial ends 22 bear on the internal annular surface 42a of the annular external ferrule 42.

[0113] In particular, [Fig.4] shows the centering tool of [Fig.3] in the support position and illustrates the centering arms 20 at the end of the centering step c). In this state, the external radial ends 22 of the centering arms 20 are supported on the internal annular surface 42a.

[0114] In practice, as the centering arms 20 bear two by two symmetrically, according to a symmetry of central axis X, on the internal annular surface 42a, the centering tool 10 bears on the internal annular surface 42a of the annular external shell 42 by means of the external radial free ends 22.

[0115] This makes it possible to center the annular outer ferrule 42 around the hub 41, since the outer radial ends 22 of the centering arms 20 cannot have different radial positions relative to the central axis X.

[0116] The centering method 100 according to the invention enables an appropriate positioning of the blower housing 30 relative to the blades 35 of the blower 2. The centering method 100 according to the invention thus enables precise adjustment, that is to say accurate to within one hundredth of a millimeter, of the radial clearances J between the blower housing 30 and the blades 35.

[0117] The configurations shown in the figures are merely possible, non - limiting examples of the invention which, on the contrary, encompasses design variants within the reach of those skilled in the art. For example, the module is not necessarily the module comprising an intermediate housing having an outer annular collar and a hub around which this outer annular collar is located. The invention also covers cases where the outer annular collar and the hub are not located in the same module of the turbomachine 2.

Claims

Claims

1. Centering tool (10) for an annular part (42), in particular around a hub (41), characterized in that it comprises: - a body (11) comprising a central axis (X), capable of being fixed on the hub (41), - a plurality of centering arms (20) movable in radial translation relative to the central axis (X) and respectively having a radial extension along an extension axis (B) relative to the central axis (X), capable of coming to bear on an internal annular surface (42a) of the annular part (42), and - an adjustment element (15) carried by the body (11) and connected to the centering arms (20), so as to be able to adjust a radial position of each of the centering arms (20) relative to the central axis (X).

2. Centering tool (10) according to claim 1, in which the centering arms (20) are distributed around the central axis (X), in particular regularly spaced around the adjustment element (15), and connected to the body (11).

3. Centering tool (10) according to claim 1 or 2, wherein the centering arms (20) respectively adopt the same radial position with respect to the central axis (X).

4. Centering tool (10) according to claim 3, wherein the adjustment element (15) ensures a synchronous adjustment of the radial position of each of the centering arms (20) relative to the central axis (X).

5. Centering tool (10) according to any one of the preceding claims, wherein the centering arms (20) are connected to the body (11) by a sliding connection.

6. Centering tool (10) according to any one of the preceding claims, in which the adjustment element (15) is a wheel movable in rotation around the central axis (X).

7. Centering tool (10) according to any one of the preceding claims, in which at least one centering arm (20) comprises at least one slot (23) cooperating with a pin (13) arranged on the body (H).

8. Centering tool (10) according to the preceding claim, in which the body (11) comprises at least one slot (23) cooperating with at least one pin (13) arranged on at least one of the centering arms (20).

9. Centering tool (10) according to any one of the preceding claims, in which at least one centering arm (20) comprises an external radial end (22), in particular made of elastomer, capable of coming to bear on an internal annular surface (42a) of the annular part (42).

10. Method for centering (100) an annular part (42) around a hub (41) by means of a centering tool (10) according to any one of claims 1 to 9, comprising at least: a. a positioning step a), during which the centering tool (10) is centered and fixed on the hub (41); b. a deployment step b), during which centering arms (20) of the centering tool (10) are moved radially outwards; and c. a centering step c), during which external radial ends (22) of the centering arms (20) of the centering tool (10) bear on an internal annular surface (42a) of the annular part (42).

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