ROTOR DISC FOR AN AIRCRAFT TURBOMACHINE

Abstract

Rotor disk (100) for an aircraft turbomachine (10), said disk (100) having an annular shape around an axis (A) and comprising: - an outer peripheral part (100a) which is configured to carry blades (28) or to be connected to blades, - an inner peripheral part (100c) internally delimiting a central bore (110) of the disk, characterized in that it is made of at least two parts (102, 104) fixed together by bolts (106), the disk (100) comprising an outer annular part (102) forming said outer peripheral part (100a) and at least one inner annular part (104) forming said inner peripheral part (100c), the inner and outer annular parts (102, 104) being axially applied to each other and comprising axial orifices (112, 114) aligned mounting of said bolts (106). Figure for the abbreviation: Figure 3

Description

Title of the invention: ROTOR DISC FOR AN AIRCRAFT TURBOMACHINE Technical field of the invention

[0001] The present invention relates in particular to a rotor disc for an aircraft turbomachine, and especially to a turbine of such a turbomachine. Technical background

[0002] An aircraft turbomachine 10, such as that shown in [Fig. 1], generally comprises at least one compressor 12, 14, an annular combustion chamber 16 and at least one turbine 18, 20. The air entering the compressor 12, 14 is compressed and then mixed with fuel and burned in the combustion chamber 16. The combustion gases are then expanded in the turbine 18, 20, which drives the turbine rotor into rotation, which in turn drives the compressor rotor.

[0003] A turbine rotor 22 as represented in [Fig.2] generally comprises one or more rotor wheels 24. In the present application, a rotor wheel 24 is understood to mean the association of a rotor disk 26 with rotor blades 28, the blades being located and distributed around the periphery of the disk 26.

[0004] There are two types of rotor wheels 24. Wheels of the first type are monobloc and are also called DAM, which is an acronym for monobloc bladed disc. A wheel of this type is formed in one piece, that is to say, its disc and its blades are formed in one piece. The disc 26 is then connected at its outer periphery to the blades 28.

[0005] The wheels according to the second type are obtained by assembling the blades 28 to the outer periphery of the disc 26. The disc then carries the blades which are mounted individually to the outer periphery of the disc, for example by fasteners of the fir or dovetail type.

[0006] The present invention applies to both types of wheel or disc, that is to say to discs whose outer periphery is configured to be connected to blades or to carry blades.

[0007] In general, a disk 26 has an annular shape around an axis A and comprises:

[0008] - an external peripheral part 26a which is configured to carry the blades 28 or to be connected to the 28th row of paddles,

[0009] - an internal peripheral part 26c which internally delimits a central bore 30 of the disc, and

[0010] - a thinned median portion 26b situated between the internal peripheral portions and external 26a, 26b, this median part 26c having an axial thickness E2 less than that E3 of the internal peripheral part 26c, or even less than that E1 of the external peripheral part 26a.

[0011] The disc 26 may further comprise one or two lateral annular ferrules 32, each of these ferrules 32 being connected to the external peripheral 26a and carrying an annular mounting flange 34 which has a radial orientation with respect to the axis A. This flange 34 serves to fix the disc 26 to another disc and is applied axially against a lateral annular face of this other disc. Bolts 36 pass through openings in the flange 26 and the other disc to secure the discs to each other and to form the turbine rotor 22.

[0012] In the current technique, the rotor disc 26 is formed from a single piece of metal alloy. This means that the different parts 26a, 26b, 26c of the disc are monoblocs and therefore formed from a single piece.

[0013] The alloy used to manufacture the disc is generally Inconel718, that is to say, a nickel-cobalt alloy. This alloy is advantageous because it can withstand high temperatures.

[0014] During operation, the turbine rotor is subjected to very high temperatures, and significant thermal gradients have been observed in the rotor disks. Typically, the outer peripheral portion 26a of the disk, which is closer to the turbine runner, has been found to be subjected to higher temperatures than its inner peripheral portion 26c.

[0015] One solution to this problem could be to use a metal alloy resistant to higher temperatures than Inconel718. This is the case, for example, with certain nickel-based alloys which have a temperature resistance approximately 50° higher than that of Inconel718.

[0016] However, it is more difficult to produce a rotor disc in these other alloys without material heterogeneity than a rotor disc in Inconel718. Chemical heterogeneity can indeed be observed during the solidification phase of these other alloys, which is likely to affect the local behavior of the alloy during the heat treatment steps that will follow.

[0017] This heterogeneity therefore constitutes a defect in the material which can generate cracks or fissures during operation, depending on the location of this defect within the disk. It is therefore necessary to implement material health monitoring to eliminate parts whose defect location could seriously impair the disk's lifespan.

[0018] There is therefore a need for a solution allowing the use of one or more distinct materials for the production of a rotor disk, and to facilitate this production- lization.

[0019] The invention meets this need in a simple, efficient and economical way. Summary of the invention

[0020] The invention relates to a rotor disk for an aircraft turbomachine, this disk having an annular shape around an axis and comprising:

[0021] - an external peripheral part which is configured to carry blades or to be connected to the paddle wheels,

[0022] - an internal peripheral part internally delimiting a central bore of the disk,

[0023] characterized in that it is made of at least two pieces fixed together, the disc comprising an external annular piece forming said external peripheral part and at least one internal annular piece forming said internal peripheral part, the internal and external annular pieces being applied and fixed axially against each other or against each other.

[0024] The invention is advantageous for several reasons. First, it allows the rotor disc to be made from several different materials, rather than just one as in the prior art. At least two different materials, such as Inconel 718 and another nickel-based alloy, for example, can be used to make the disc components, each component being made from one of these materials. Limiting the use of a material to a portion of the disc, i.e., to a single disc component, reduces the risk of material heterogeneity in that portion or component. Furthermore, the manufacturing of the disc is simplified, and complex disc shapes can be produced more easily.

[0025] The rotor disc according to the invention may comprise one or more of the following features, taken individually or in combination with each other:

[0026] - said at least two parts are fixed together by bolts, the parts an internal and external nuclei having aligned axial mounting holes for said bolts; the holes for fixing the parts together can further be used to allow the disc to be fixed to at least one other adjacent disc.

[0027] — said at least two parts are fixed together by friction welding;

[0028] - the disc further comprises a thinned central portion located between the parts internal and external peripherals, this middle part having an axial thickness less than that of the internal peripheral part;

[0029] - said at least one internal annular piece forms said median part;

[0030] - said middle part and said inner peripheral part are located entirely radially inside the outer annular piece;

[0031] - said at least one internal annular piece is applied against at least one face annular of the external annular piece;

[0032] — the openings of the external annular piece open onto this annular face;

[0033] - said at least one face comprises a centering element configured to cooperate with a complementary element of said at least one internal annular piece, in order to center the annular pieces on said axis;

[0034] - said centering element is a cylindrical bearing surface;

[0035] - the disc comprises two internal annular pieces applied respectively on two opposite annular faces of the external annular piece so that the external annular piece is sandwiched between the internal annular pieces;

[0036] - the two internal annular pieces are located on either side of a perpendicular plane dicular to the axis and passing through the middle of the external annular piece;

[0037] - the two internal annular pieces are at an axial distance from each other;

[0038] - the disc further comprises at least one lateral annular ferrule which carries a annular fixing flange, this annular flange having a radial orientation with respect to the axis;

[0039] - said at least one internal annular piece forms said at least one ferrule.

[0040] - said outer annular piece is made of a different material from said outer annular piece minus one internal annular piece;

[0041] - said at least one internal annular part is made of Inconel718 and said at unless an external ring piece is made of a nickel-based alloy different from Inconel718.

[0042] The present invention also relates to an aircraft turbine or turbomachine, comprising at least one rotor disc as described above. Brief description of the figures

[0043] Other features and advantages will become apparent from the following description of a non-limiting embodiment of the invention with reference to the accompanying drawings in which:

[0044] [Fig-1] [Fig.1] is a schematic axial cross-sectional view of a turbomachine aircraft,

[0045] [Fig.2] [Fig.2] is a semi-schematic axial cross-sectional view of a turbine rotor,

[0046] [Fig.3] [Fig.3] is a semi-schematic perspective and axial section view of a rotor disc, according to one embodiment of the invention,

[0047] [Fig.4] [Fig.4] is another schematic half-view in axial section of the disk of rotor of [Fig. 3], and shows a larger-scale detail of the disk, and

[0048] [Fig. 5] [Fig. 5] is a view similar to that of [Fig. 3] and showing a variant of manufacturing a rotor disc according to the invention. Detailed description of the invention

[0049] Figures 1 and 2 have already been described above.

[0050] Figures 3 and 4 illustrate a first embodiment of a rotor disk 100 according to the invention for an aircraft turbine or turbomachine 10, such as that illustrated in [Fig.1].

[0051] The particularity of the invention is related to the fact that the rotor disc 100 is made in at least two pieces 102, 104 fixed together by bolts 106.

[0052] The disk 100 includes an external annular piece 102 forming an external peripheral portion 100a of the disk. The external peripheral portion 100a is configured to carry blades 108 or to be connected to blades, as mentioned above. In the example shown, the external periphery of this portion 100a includes recesses 109, for example dovetailed, for mounting the feet of the blades 108.

[0053] The disk 100 further comprises at least one internal annular part 104 (two internal annular parts 104 in the example shown) which forms an internal peripheral part 100c of the disk. The internal peripheral part 100c internally delimits a central bore 110 of the disk 100.

[0054] The internal and external annular parts 102, 104 are applied axially against each other or against each other.

[0055] They can be fixed together by bolting and then have aligned axial holes 112, 114 for mounting the bolts 106. Alternatively, they could be fixed by friction welding for example.

[0056] In the example shown, the disk 100 further comprises a thinned middle portion 100b which is located between the inner and outer peripheral portions 100a, 100c, this middle portion 100b having an axial thickness E2 less than that E3 of the inner peripheral portion 100c. This middle portion 100b can be formed by the inner annular piece 104, as illustrated in the drawings.

[0057] The drawings also show that the middle part 100b and the inner peripheral part 100c are located entirely radially inside the outer annular part 102.

[0058] In the example shown, the external part 102 includes a radially internal annular rim 120 whose internal periphery is thickened in its axial dimension. In other words, this rim 120 comprises a radially external annular portion 120a which has an axial thickness XI and a radially internal annular portion 120b which has an axial thickness X2, which is greater than XL

[0059] At the junction between these parts 120a, 120b, the rim 120 comprises two cy supports lindriques 122 located respectively on both sides of the disc 100 or the piece 102. Part 102 thus comprises a first lateral face having a cylindrical bearing surface 122, and a second opposite lateral face having another cylindrical bearing surface 122.

[0060] In the example shown, the bearing surfaces 122 have identical dimensions and, in particular, identical diameters. Alternatively, these dimensions could be different to ensure error-proofing during assembly of the parts.

[0061] The orifices 112 are formed here in the part 120b and extend over the entire axial dimension of this part. They thus open onto the two lateral faces of the part 102.

[0062] In the case of using a single internal annular piece 104 ([Fig.5]), the piece 104 is applied against one of the annular faces of the external annular piece 102.

[0063] In the case of using two internal parts 104 (figures 3 and 4), the parts 104 are applied respectively against the two annular faces of the external part 102.

[0064] The orifices 112 of the part 102 are aligned with the orifices 114 of the part or parts 104.

[0065] Each span 122 preferably forms a centering element configured to cooperate with a complementary element of the corresponding internal annular part 104, in order to center the parts with respect to the axis A.

[0066] The or each part 104 thus includes an annular recess 124 intended to receive the internal part 120b and comprising a cylindrical shoulder 126 intended to cooperate by support in the radial direction and sliding in the axial direction with the cylindrical bearing surface 122 of the part 102.

[0067] In the example shown, the external part 102 and in particular its rim 120 is sandwiched between the parts 104. The two parts 104 are located on either side of a plane P perpendicular to the axis A and passing through the middle of the part 102.

[0068] It can be seen in the drawings that the parts 104 are axially clamped on the part 102 and are axially separated from each other radially inside the part 102. The axial clearance J between the parts 104 helps to limit the risk of interaction between these parts in operation.

[0069] The disc 10 according to the invention may further comprise at least one lateral annular ferrule 130 which carries an annular fixing flange 132, this annular flange 132 having a radial orientation with respect to the axis A.

[0070] In the example shown, each of the parts 104 includes such a ferrule 130, so the disc includes two opposing lateral ferrules 130.

[0071] Each of the parts 104 essentially comprises three annular zones in the example shown.

[0072] The radially external zone ZI includes the ferrule 130 which extends from the rest of part 104, around and along axis A. The flange 132 that it carries can be continuous over 360° or notched as in the example shown.

[0073] The radially internal zone Z3 of each part 104 includes the median 100b and internal peripheral 100c parts of the disk 100.

[0074] The median area Z2 of each part 104 is applied against the face of the part 102 and includes the aforementioned recess 124.

[0075] The radially internal zone Z3 of part 104 includes a flat lateral face 140 oriented opposite the other part 104, which defines the aforementioned clearance J. The face 140 is flat so that this clearance J is constant. On the side opposite this face, the internal zone Z3 of part 104 includes a contour C defining an axial thickness in a radially internal portion and a thinning in a radially external portion.

[0076] In the embodiment of [Fig.5], the disk 100 comprises a single internal piece 104 which is applied against one of the lateral faces of the external piece 102.

[0077] In this case, the external part 102 and in particular its rim 120, is applied axially against the part 104 and these parts 102, 104 are centered with respect to each other as mentioned above.

[0078] Part 104 essentially comprises three annular zones in the example shown.

[0079] The radially external zone ZI may include the ferrule 130 and the flange 132 as mentioned above.

[0080] The median zone Z2 is applied against the face of the part 102 and includes the aforementioned recess 124.

[0081] The radially internal zone Z3 comprises the median 100b and internal peripheral 100c parts of the disk 100. It is observed that this zone Z3 is crossed by the median plane P and that it has a symmetry with respect to this plane.

[0082] Due to this symmetry, on each side of this zone Z3, the part comprises two opposite lateral faces which each have a contour C' defining an axial thickness in a radially internal portion, and a thinning in a radially external portion.

[0083] Advantageously, the outer annular piece 102 is made of a different material from the or each inner annular piece 104.

[0084] The internal annular part 104 is for example made of Inconel718.

[0085] The outer annular piece or each 102 is for example made of a nickel-based alloy different from Inconel718.

Claims

Claims

1. Rotor disc (100) for an aircraft turbomachine (10), this disc (100) having an annular shape around an axis (A) and comprising: - an external peripheral part (100a) which is configured to carry blades (28) or to be connected to blades, - an internal peripheral part (100c) internally delimiting a central bore (110) of the disc, characterized in that it is made of at least two parts (102, 104) fixed together, the disc (100) comprising an external annular part (102) forming said external peripheral part (100a) and at least one internal annular part (104) forming said internal peripheral part (100c), the internal and external annular parts (102, 104) being applied and fixed axially against each other or against each other and.

2. A rotor disc (100) according to claim 1, wherein said at least two pieces (102, 104) are secured together by bolts (106), the inner and outer annular pieces (102, 104) having aligned axial holes (112, 114) for mounting said bolts (106).

3. Rotor disk (100) according to claim 1 or 2, further comprising: - a thinned middle portion (100b) located between the inner and outer peripheral portions (100a, 100b), this middle portion (100b) having an axial thickness (E2) less than that (E3) of the inner peripheral portion (100c).

4. A rotor disc (100) according to claim 3, wherein said at least one inner annular piece (104) forms said middle portion (100b).

5. A rotor disc (100) according to claim 3 or 4, wherein said middle portion (100b) and said inner peripheral portion (100c) are located integrally radially inside the outer annular part (100a).

6. Rotor disc (100) according to one of the preceding claims, wherein said at least one internal annular part (104) is applied against at least one annular face of the external annular part (102).

7. Rotor disk (100) according to claim 6, wherein said at least one face comprises a centering element (122) configured to cooperate with an element (126) complementary to said at least one internal annular part (104), in order to center the annular parts (102, 104) on said axis (A).

8. A rotor disc (100) according to claim 7, wherein said centering element is a cylindrical bearing surface (122).

9. Rotor disc (100) according to one of claims 6 to 8, comprising two internal annular pieces (104) applied respectively to two opposite annular faces of the external annular piece (102) so that the external annular piece (102) is sandwiched between the internal annular pieces (104).

10. Rotor disc (100) according to claim 9, in which the two internal annular parts (104) are located on either side of a plane (P) perpendicular to the axis (A) and passing through the middle of the external annular part.

11. A rotor disc (100) according to claim 9 or 10, wherein the two inner annular pieces (104) are axially spaced from each other.

12. Rotor disc (100) according to one of the preceding claims, in which it further comprises: - at least one lateral annular ferrule (130) which carries an annular fixing flange (132), this annular flange (132) having a radial orientation relative to the axis (A).

13. A rotor disc (100) according to claim 12, wherein said at least one inner annular piece (104) forms said at least one ferrule (130).

14. Rotor disc (100) according to one of the preceding claims, wherein said outer annular part (104) is made of a different material from said at least one inner annular part (102).

15. A rotor disc (100) according to claim 14, wherein said at least one inner annular piece (104) is made of Inconel718 and said at least one outer annular piece (102) is made of a nickel-based alloy other than Inconel718.

16. Aircraft turbine (18, 20) or turbomachine (10), comprising at least one rotor disk (100) according to one of the preceding claims.

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