A METHOD OF REPAIRING A COMPOSITE BLADE

Abstract

The invention relates to a method of repairing a blade (1) made of composite material, extending in a so-called axial direction (X), the said blade (1) comprising a root (2) and a blade (3), the axial end of which opposite the root (2) comprises an area to be repaired, the said blade (3) comprising an intrados (4) surface and an extrados (5) surface.

Claims

1-9. (canceled)

10. A method of repairing a blade made of composite material, extending in an axial direction (X), said blade comprising a root and a blade whose axial end opposite the root comprises an area to be repaired, said blade comprising an intrados surface and an extrados surface, the method comprising: a) positioning the blade in a tooling, b) positioning at least a first foil and at least a second foil, at the level of the end area to be repaired, respectively on the intrados surface and on the extrados surface of the blade, each foil having an axial end opposite the root extending axially beyond the corresponding end of the blade and positioned with respect to a reference of the tooling said end of each foil defining the axial end of the area to be repaired, said foils delimiting between them a refill volume, c) filling the refill volume with a pasty or fluid refill material, such as a non-polymeric resin such as an unpolymerized resin or a composite refill paste, so that the refill material does not extend beyond the refill volume, d) curing the refill material by baking or polymerizing said material, e) removing the foils.

11. The method according to claim 10, wherein the tooling comprises bearing surfaces forming reference surfaces and cooperating with the blade root so as to position said blade axially in the tooling, the tooling further comprising a stop capable of coming to bear on the root or the blade of the blade, so as to position said blade in the tooling in a direction (Y) perpendicular to the axial direction (X).

12. The method according to claim 11, wherein step (c) is performed when the blade is mounted in the tooling.

13. The method according to claim 10, wherein step (c) is performed when the blade is mounted in the tooling.

14. The method according to claim 10, wherein during step (b), the said foils are immobilised in position on the blade, the assembly formed by the said blade and the foils then being removed from the tooling before step (c).

15. The method according to claim 10, wherein in step (b) the foils are positioned axially with respect to a reference surface of the tooling.

16. The method according to claim 15, wherein in step (c), excess refill material extending beyond the refill volume is removed by levelling or scraping.

17. The method according to claim 15, wherein the corresponding end of the blade, the reference surface and the foils delimit the refill volume, the material being inserted into the said volume in step (c), so as to fill it completely.

18. The method according to claim 10, wherein the refill material is a thermosetting resin.

19. The method according to claim 10, wherein a closing wall covers said ends of the foils so as to close the refill volume, the refill material being inserted or injected into said refill volume.

20. A method of repairing a blade made of composite material, extending in an axial direction (X), said blade comprising a root and a blade whose axial end opposite the root comprises an area to be repaired, said blade comprising an intrados surface and an extrados surface, the method comprising: a) positioning the blade in a tooling, b) positioning at least a first foil and at least a second foil, at the level of the end area to be repaired, respectively on the intrados surface and on the extrados surface of the blade, each foil having an axial end opposite the root extending axially beyond the corresponding end of the blade and positioned with respect to a reference of the tooling said end of each foil defining the axial end of the area to be repaired, said foils delimiting between them a refill volume, c) filling the refill volume with a pasty or fluid refill material, such as a non-polymeric resin such as an unpolymerized resin or a composite refill paste, so that the refill material does not extend beyond the refill volume, d) curing the refill material by baking or polymerizing said material, e) removing the foils, wherein the tooling comprises bearing surfaces forming reference surfaces and cooperating with the blade root so as to position said blade axially in the tooling, the tooling further comprising a stop capable of coming to bear on the root or the blade of the blade, so as to position said blade in the tooling in a direction (Y) perpendicular to the axial direction (X).

21. The method according to claim 20, wherein during step (b), the said foils are immobilized in position on the blade, the assembly formed by the said blade and the foils then being removed from the tooling before step (c).

22. The method according to claim 20, wherein in step (b) the foils are positioned axially with respect to a reference surface of the tooling.

23. The method according to claim 22, wherein the corresponding end of the blade, the reference surface and the foils delimit the refill volume, the material being inserted into the said volume in step (c), so as to fill it completely.

24. The method according to claim 20, wherein in step (c), excess refill material extending beyond the refill volume is removed by levelling or scraping.

25. The method according to claim 20, wherein the refill material is a thermosetting resin.

26. The method according to claim 20, wherein a closing wall covers said ends of the foils so as to close the refill volume, the refill material being inserted or injected into said refill volume.

Description

BRIEF DESCRIPTION OF THE FIGURES

[0031] FIG. 1 is a diagram illustrating the different steps of a method for repairing a blade, according to an embodiment of the invention;

[0032] FIG. 2 is a schematic perspective view of a blade mounted in the tooling;

[0033] FIG. 3 is a schematic perspective view of the blade tip and foils;

[0034] FIGS. 4 to 6 are schematic views of the blade tip, illustrating various successive steps in the method;

[0035] FIG. 7 is a schematic view of the blade tip, illustrating another embodiment of the invention.

DETAILED DESCRIPTION OF THE INVENTION

[0036] A method for repairing a composite fan blade 1 for a turbomachine, according to one embodiment, is illustrated schematically in FIGS. 1 to 6.

[0037] The blade 1 extends along an axis X and comprises a dovetail-shaped blade root 2, located at the bottom in FIG. 2, and a profiled blade 3, comprising an intrados 4 surface and an extrados 5 surface. The blade 3 has a first axial end, connected to the blade root 2, and a second axial end, also referred to as the tip 6 (FIG. 3), opposite the first end. The root 2 has two inclined surfaces 7 facing the tip 6 of the blade, forming bearing surfaces for co-operation with complementary surfaces of a rotor disc of the fan.

[0038] The intrados 4 surface and extrados 5 surface meet at a leading edge 8 and a trailing edge 9.

[0039] The leading edge 8 is intended to be located upstream of the trailing edge 9, relative to the direction of airflow through the fan.

[0040] The blade 1 is made of a composite material comprising for example a fibrous fabric embedded in a resin matrix.

[0041] The objective of the repair process according to the invention is to reconstitute the original geometry of the tip 6 of the blade 1 after damage to said tip 6. The reconstitution, also known as refill, of the tip 6 of the blade 1 must be carried out with the same dimensional tolerances as an original blade 1, for example of the order of 0.2 mm, which requires in particular perfect control of the axial distance between the corresponding end 6 of the blade 3 and the axis of the fan rotor, and therefore the axial distance between the corresponding end 6 of the blade 3 and the bearing surfaces 7 of the blade root 2.

[0042] The repair method according to the invention comprises first of all a step (E1) of positioning and locking the blade 1 in a tooling 10.

[0043] The tooling 10 comprises a fixed support 11, two support areas 12 and a stop member 13 which are fixed with respect to the support 11.

[0044] Each support area 12 comprises an inclined surface 12a intended to form a support or a bearing for the complementary bearing surfaces 7 of the blade root 2, so as to limit the displacement of the blade 1 along the X axis, upwards in FIG. 2.

[0045] The downstream end or the end forming the trailing edge 9 of the blade root 2 also comes to bear on the stop member 13 of the tooling 10, so as to ensure the positioning of the blade 1 with respect to the tooling 10 along an axis Y, perpendicular to the axis X.

[0046] Locking means, such as a clamp of the claw type, exert an axial force F directed upwards in FIG. 2, so as to hold the bearing surfaces 7 of the blade root 2 on the bearing surfaces 12a of the support areas 12.

[0047] The tooling 10 further comprises foils 14 which are placed on either side of the blade apex area 6, i.e. against the intrados 4 surface and extrados 5 surface of the blade 1. The shape of each foil 14 is adapted to the shape of the intrados 4 surface or extrados 5 surface of the blade 1. Each foil 14 has a first axial end 15, facing the blade root 2, and a second axial end 16 opposite. The position of the second axial ends 16 of the foils 14 with respect to the rest of the tooling 10 is controlled, for example by pressing said second ends 16 against a support area 17 of the support 11. In other words, it is possible to control the axial distance between the bearing surfaces 7 and the second ends 16 of the foils 14. The side edges 18 of the foils 14 meet at the trailing edge 9 and the leading edge 8 of the tip 6 of the blade 3.

[0048] The damaged tip 6 of the blade 3 and the foils 14 then delimit a volume 19 to be reconstituted.

[0049] The foils 14 can be integral with the tooling 10 or can be made integral with the blade 1. In the latter case, the foils 14 can be clamped to the blade tip 6, for example, by any appropriate means, such as clamps.

[0050] The blade 1 and the foils 14 can then be removed from the tooling 10.

[0051] The aforementioned volume 19 can then be filled with a pasty or fluid refill material 20 (step E, FIGS. 1 and 4). This material 20 is for example a thermosetting resin, for example an epoxy or polyurethane based resin. For example, the resin is filled with short reinforcing fibres, such as glass fibres, which are less than 3 mm long. Alternatively, the resin can be filled with glass beads having a diameter of between 50 and 100 microns.

[0052] Excess thermosetting material 20 can be removed in a shaving or scraping step (step E3, FIGS. 1 and 5) using a tool, for example which can be a flexible silicone tool, so as to avoid any damage to the foils 14. In particular, it is necessary to avoid changing the dimension between the second ends 16 of the foils 14 and the bearing surfaces 7 of the blade root 2.

[0053] The refill material 20 is then cured by polymerization, for example in a baking step (step E4, FIG. 1). In this step, the refill material has, for example, a shrinkage of less than 2%. The position of the second ends 16 of the foils 14 can be adjusted to take into account or to anticipate such shrinkage and thus obtain the desired dimension after shrinkage and hardening.

[0054] The foils 14 can then be removed (step E5, FIGS. 1 and 6) so as to obtain the repaired blade 1, i.e., the blade 1 whose damaged tip 6 has been reconstituted, reloaded or rebuilt, so as to recover the original dimensions of the blade 1, within the dimensional tolerances.

[0055] According to another embodiment illustrated in FIG. 7, a closing wall 21 can cover the second ends 16 of the foils 14 so as to close the volume 19 to be reconstituted. The refill material 20 can be inserted or injected into said volume 19, for example by means of a syringe, through an opening 21a, so as to completely fill said volume 19. The blade 1, the foils 14 and the closing wall 21 can be held in position on the remainder of the tooling 10 during the step of inserting or injecting the refill material 20 into said volume.

[0056] Said material 20 can then be cured, for example by baking, and then the reconstituted blade 1 can be removed from the tooling 10.