ASSEMBLY OF PARTS FOR AN AIRCRAFT TURBOMACHINE

Abstract

Assembly of parts (10, 12) for an aircraft turbomachine, this assembly comprising: - a first part (10) comprising a first annular flange (10a), - a second part (12) comprising a second annular flange (12a), - bolts (20) which pass through orifices (10b) of the second flanges (10a, 12a), and - washers (20) which are axially interposed between heads (18a1) of the screws (18a) and one of the flanges (10a), characterized in that the washers (20) have a Young's model lower than that of each flange (10a, 12a). Figure for the abstract: Figure 3

Description

Title of the invention: ASSEMBLY OF PARTS FOR AN AIRCRAFT TURBOMACHINE Technical field of the invention

[0001] The present invention relates to an assembly of parts for an aircraft turbomachine. Technical background

[0002] An aircraft turbomachine comprises assemblies of bolted parts and the present invention relates to this type of assembly.

[0003] As illustrated in [Fig.l], this type of assembly comprises two or more parts 10, 12, 14, 16 comprising flanges 10a, 12a, 14a, 16a which are applied axially one on the other and tightened axially one against the other or against each other by bolts 18 which pass through the flanges 10a, 12a, 14a, 16a.

[0004] The flanges 10a, 12a, 14a, 16a are generally made of metal alloys and have orifices 10b, 12b, 14b, 16b for the passage of the screws 18a of the bolts 18 ([Fig.2]). Each of the screws 18a comprises a head 18al connected to a threaded rod 18a2 which passes through the orifices 10b, 12b, 14b, 16b of the flanges and is screwed into a nut 18b. The flanges 10a, 12a, 14a, 16a are interposed between the nuts 18b, on the one hand, and the heads 18al of the screws 18a, on the other hand, and washers 20 are interposed between the heads 18al of the screws 18a and one of the flanges 10a to compensate for axial clearances linked to assembly and manufacturing tolerances.

[0005] In the current technique, the washers are made of rigid materials that are neither deformable nor compressible, and in any case more rigid than the materials of the flanges. This configuration, however, has drawbacks.

[0006] In operation, the parts and their flanges are likely to deform, which can result in a lack of parallelism of the flanges and therefore a lack of axial support and tightening of the flanges together. This defect can also appear at rest because the manufacturing tolerances of the parts mean that the flanges are not always perfectly parallel, as illustrated in [Fig.2]. This defect is problematic because it can cause the screw to bend during tightening and therefore reduce its service life.

[0007] The invention provides a solution to this problem which is simple, effective and economical. Summary of the invention

[0008] The invention proposes an assembly of parts for an aircraft turbomachine, this assembly comprising:

[0009] - a first part comprising a first annular flange which extends around of an axis and which has a radial orientation relative to this axis, this first annular flange comprising a first series of axial orifices distributed around the axis,

[0010] - a second part comprising a second annular flange which extends around the axis and which has a radial orientation relative to this axis, this second annular flange comprising a second series of axial orifices distributed around the axis and axially aligned with the orifices of the first series,

[0011] - bolts which are distributed around the axis and which are parallel to the axis, each of these bolts passing through one of the holes in the first flange and one of the holes in the second flange and comprising a nut and a screw which has a head connected to a threaded rod capable of being screwed into the nut, and

[0012] - washers which are distributed around the axis and which are crossed by the rods threaded screws, the washers being axially inserted between the heads of the screws and the first flange

[0013] characterized in that the washers have a Young's model lower than that of each flange.

[0014] The invention thus proposes to use washers which are more deformable and / or compressible than the flanges. When tightening the flanges or in operation, in the case where the flanges are not perfectly parallel, the washers deform and compensate for this lack of parallelism, which prevents the bolts from deforming by bending. This makes it possible to improve the screw life of the bolts and therefore of the assembly.

[0015] The assembly according to the invention may comprise one or more of the following characteristics, taken in isolation from one another or in combination with one another: - the washers have a Young model at least five times lower than that of each flange; - the washers have a Young model at least ten times lower than that of each flange; - the washers are made from a material chosen from lead, aluminum, bronze, and their alloys; - the Young's modulus of the washers is between 100MPa and 200MPa, and preferably between 20MPa and 120MPa; - the flanges are made of nickel-based superalloy; - the assembly further comprises a third part comprising a third annular flange which extends around the axis and which has a radial orientation relative to this axis, this third annular flange comprising a third series of axial orifices distributed around the axis and axially aligned with the orifices of the first and second series, the orifices of this third series being crossed by the bolts; - the assembly further comprises a fourth part comprising a fourth annular flange which extends around the axis and which has a radial orientation relative to this axis, this fourth annular flange comprising a fourth series of axial orifices distributed around the axis and axially aligned with the orifices of the first, second and third series, the orifices of this fourth series being crossed by the bolts;

[0016] — the bolts are crimped onto the second flange and in particular into the holes of this second bridle.

[0017] The present invention also relates to an aircraft turbomachine, comprising at least one assembly as described above. The assembly may be part of a turbine, for example high pressure, and in particular of a turbine rotor. Brief description of the figures

[0018] The invention will be better understood and other details, characteristics and advantages of the invention will appear more clearly on reading the following description given by way of non-limiting example and with reference to the appended drawings in which:

[0019] [Fig-1] [Fig.l] is a partial schematic view in axial section of an assembly of parts for an aircraft turbomachine,

[0020] [Fig.2] [Fig.2] is a view similar to that of [Fig.l] and illustrates an assembly of parts for an aircraft turbomachine according to the invention,

[0021] [Fig.3] [Fig.3] is a view similar to that of [Fig.l] and illustrates an assembly of parts in accordance with the invention. Detailed description of the invention

[0022] Figures 1 and 2 have been partially described in the above.

[0023] These figures as well as [Fig.3] can be considered as illustrating characteristics of the invention.

[0024] The invention relates to an assembly of parts 10, 12, 14, 16 for an aircraft turbomachine, this assembly comprising:

[0025] - a first part 10 comprising a first annular flange 10a which extends around an axis and which has a radial orientation relative to this axis, this first annular flange 10a comprising a first series of axial orifices 10b distributed around the axis,

[0026] - a second part 12 comprising a second annular flange 12a which extends around the axis and which has a radial orientation relative to this axis, this second annular flange 12a comprising a second series of axial orifices 12b distributed around the axis and axially aligned with the orifices 12a of the first series,

[0027] - bolts 18 which are distributed around the axis and which are parallel to the axis, each of these bolts 18 each passing through one of the holes 10b of the first flange 10a and one of the orifices 12b of the second flange 12a and comprising a nut 18b and a screw 18a which comprises a head 18al connected to a threaded rod 18a2 capable of being screwed into the nut 18b, and

[0028] - washers 20 which are distributed around the axis and which are crossed by the rods threaded 18a2 of the screws 18a, the washers 20 being interposed axially between the heads 18al of the screws 18a and the first flange 10.

[0029] As seen in the figures, the assembly according to the invention is not limited to a particular number of flanges. It may comprise two flanges 10a, 12a as illustrated in [Fig.3]. The assembly then comprises the aforementioned first and second flanges 10a, 12a.

[0030] The assembly may comprise three flanges 10a, 12a, 14a as illustrated in [Fig.2]. The assembly then comprises a third flange 14a interposed for example between the first and second flanges 10a, 12a mentioned above. It is therefore understood that the assembly further comprises a third part 14 comprising this third annular flange 14a which extends around the axis and which has a radial orientation relative to this axis. The third annular flange 14a comprises a third series of axial orifices 14b distributed around the axis and axially aligned with the orifices 10b, 12b of the first and second series, the orifices 14b of this third series being crossed by the bolts 18.

[0031] The assembly may comprise four flanges 10a, 12a, 14a, 16a as illustrated in [Fig.l]. The assembly then comprises, in addition to the aforementioned third flange 14a, a fourth flange 16a interposed for example between the aforementioned third and second flanges 14a, 12a. It is therefore understood that the assembly further comprises a fourth part 16 comprising this fourth annular flange 16a which extends around the axis and which has a radial orientation relative to this axis. The fourth annular flange 16a comprises a fourth series of axial orifices 16b distributed around the axis and axially aligned with the orifices 10b, 12b, 14b of the other series, the orifices 16b of this fourth series being crossed by the bolts 18.

[0032] According to the invention, the washers 20 have a Young's model lower than that of each flange 10a, 12a, 14a, 16a. This allows the washers 20 to have a deformation and / or compression capacity that is preferential compared to the flanges 10a, 12a, 14a, 16a. [Fig. 2] shows, for example, that a lack of parallelism of the flanges 10a, 12a, 14a, 16a will cause deformation of at least part of the washers 20 (which will have a variation in thickness over their entire periphery due to the distribution of the compression forces) and will prevent the bolts 18 from bending. The invention thus makes it possible to avoid the introduction of bending stresses in the bolts 18 (too harmful for their proper functioning) by sacrificing part of the tightening force in the deformation of the washers 20 making it possible to increase the admissible tolerance level. on the flanges.

[0033] As illustrated in [Fig.2], the bolts 18b can be crimped onto the second flange 14a and in particular into the orifices 14b of this second flange 14a.

[0034] Preferably, the washers 20 have a Young's model at least five times lower than that of each flange 10a, 12a, 14a, 16a. More preferably, the washers 20 have a Young's model at least ten times lower than that of each flange 10a, 12a, 14a, 16a.

[0035] The washers 20 may be made of a material chosen from lead, aluminum, bronze, and their alloys (lead-based alloy, aluminum-based alloy, alloy comprising bronze (copper and tin), lead-based and / or aluminum-based and / or bronze-based alloy).

[0036] The Young's modulus of the washers 20 is preferably between 100 MPa and 200 MPa, and preferably between 20 MPa and 120 MPa. By comparison, the Young's modulus of each of the flanges 10a, 12a, 14a, 16a may be greater than 600 MPa or even 1200 MPa.

[0037] The flanges 10a, 12a, 14a, 16a are for example made of nickel-based superalloy.

[0038] The present invention also relates to an aircraft turbomachine, comprising at least one assembly as described above.

[0039] The assembly may be part of a turbine, for example a high-pressure turbine, and in particular a turbine rotor, as illustrated in the drawings. The parts 10, 12, 14, 16 are then, for example, bladed turbine discs.

[0040] The advantages linked to the invention are in particular the following: - correction of runout and parallelism defects between the flanges of the parts, - maintaining the tightening and forces of the bolts, - etc.

Claims

Claims

1. Assembly of parts (10, 12, 14, 16) for an aircraft turbomachine, this assembly comprising: - a first part (10) comprising a first annular flange (10a) which extends around an axis and which has a radial orientation relative to this axis, this first annular flange (10a) comprising a first series of axial orifices (10b) distributed around the axis, - a second part (12) comprising a second annular flange (12a) which extends around the axis and which has a radial orientation relative to this axis, this second annular flange (12b) comprising a second series of axial orifices (12b) distributed around the axis and axially aligned with the orifices (10b) of the first series, - bolts (20) which are distributed around the axis and which are parallel to the axis,each of these bolts (20) passing through one of the orifices (10b) of the first flange (10a) and one of the orifices (12b) of the second flange (12a) and comprising a nut (18b) and a screw (18a) which has a head (18al) connected to a threaded rod (18a2) capable of being screwed into the nut (18b), and - washers (20) which are distributed around the axis and which are crossed by the threaded rods (18a2) of the screws (18a), the washers (20) being interposed axially between the heads (18al) of the screws (18a) and the first flange (10a), characterized in that the washers (20) have a Young's model lower than that of each flange (10a, 12a, 14a, 16a).,

2. An assembly according to claim 1, wherein the washers (20) have a Young's model at least five times lower than that of each flange (10a, 12a, 14a, 16a).

3. An assembly according to claim 2, wherein the washers (20) have a Young's model at least ten times lower than that of each flange (10a, 12a, 14a, 16a).

4. Assembly according to one of the preceding claims, in which the washers (20) are made of a material chosen from lead, aluminum, bronze, and their alloys.

5. Assembly according to one of the preceding claims, in which the Young's modulus of the washers (20) is between 100 MPa and 200 MPa, and preferably between 20 MPa and 120 MPa.

6. Assembly according to one of the preceding claims, in which the flanges (10a, 12a, 14a, 16a) are made of nickel-based superalloy.

7. Assembly according to one of the preceding claims, in which it further comprises a third part (14) comprising a third annular flange (14a) which extends around the axis and which has a radial orientation relative to this axis, this third annular flange (14a) comprising a third series of axial orifices (14b) distributed around the axis and axially aligned with the orifices (10b, 12b) of the first and second series, the orifices (14b) of this third series being crossed by the bolts (18).

8. Assembly according to the preceding claim, in which it further comprises a fourth part (16) comprising a fourth annular flange (16a) which extends around the axis and which has a radial orientation relative to this axis, this fourth annular flange (16a) comprising a fourth series of axial orifices (16b) distributed around the axis and axially aligned with the orifices (10b, 12b, 14b) of the first, second and third series, the orifices (16b) of this fourth series being crossed by the bolts (18).

9. Aircraft turbomachine, comprising at least one assembly according to one of the preceding claims.

10. Turbomachine according to the preceding claim, in which the assembly is part of a turbine, for example high pressure, and in particular of a turbine rotor.

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