METHOD FOR MANUFACTURING A COMPOSITE PART FOR A TURBOMACHINE

Abstract

A method for manufacturing a part made of composite material for a turbomachine, in particular of an aircraft, includes the steps of: b) arranging a preform made of fibers in a mold, c) injecting polymerizable resin into the mold, d) machining the part, and e) visually checking the part. Step b) is preceded by a step a) in which at least one compliance coating is deposited in the mold. The compliance coating has a calibrated thickness (X) and at least one visual aspect identifiable by an operator. The coating is configured to cover at least one area of the preform and to be rigidly attached thereto by the resin at the end of step c) Step e) includes verifying, by the operator, the presence of the aspect in the area.

Claims

1. A method for manufacturing a part made of composite material for a turbomachine, comprising the steps of: b) arranging a preform made by weaving fibers in three dimensions in a mold, c) injecting the polymerizable resin into the mold to impregnate the preform so as to form the part after solidification, d) machining the part, e) visually checking the part by an operator to validate at least one compliance criterion, wherein step b) is preceded by a step a) during which at least one compliance coating is deposited in the mold, the compliance coating having a calibrated thickness (X) and at least one visual aspect identifiable by an operator, the compliance coating being configured to cover at least one area of the preform and to be secured thereto by the resin at the end of the step c), and wherein step e) comprises verifying by the operator of the presence of said aspect in said area, so as to validate said compliance criterion.

2. The method according to claim 1, wherein said coating has a constant thickness (X) between 10 and 100 .Math.m.

3. The method according to claim 1, wherein said visual aspect is a color or comprises a repetition of a same surface pattern.

4. The method according to claim 1, wherein said coating is deposited in the mold by spreading or spraying.

5. The method according to claim 1, wherein said coating is selected from a colored paint, a colored resin, a glue film, a cloth, or a combination thereof.

6. The method according to claim 5, wherein the cloth is made from glass or carbon fibers.

7. The method according to claim 1, wherein said coating comprises at least one polymerizable compound and the polymerization of which is initiated before the step b).

8. The method according to claim 1, wherein said coating is deposited on a bottom of the mold.

9. The method according to claim 1, wherein said machining is carried out by sandblasting.

10. The method according to claim 1 further comprising, before the step a), a step i) of positioning wedges in the mold, each of the wedges having a thickness equal to said calibrated thickness and being configured to define between them a space for depositing said coating, and between the steps a) and b), a step ii) of removing the wedges from the mold.

11. The method according to claim 10, further comprising, between the steps a) and b), a step iii) of at least partially polymerizing said coating.

12. The method according to claim 1, further comprising, between the steps a) and b), a step iv) of checking the thickness (X) of said coating, for example by Eddy Current.

13. The method according to claim 1, wherein the part is a vane or a casing.

14. The method according to claim 2, wherein said coating has a constant thickness (X) between 20 and 60 .Math.m.

15. The method according to claim 1, wherein said coating has a constant thickness (X) of 40 .Math.m.

16. The method according to claim 6, wherein the cloth is woven.

17. The method according to claim 6, wherein the cloth is impregnated with a polymerizable resin.

Description

BRIEF DESCRIPTION OF THE FIGURES

[0041] Further characteristics and advantages of the invention will become apparent from the following detailed description, for the understanding of which reference is made to the attached drawings in which:

[0042] FIG. 1 is a schematic perspective view of a composite aircraft turbomachine vane, which undergoes several operations during a manufacturing method according to the prior art,

[0043] FIG. 2 is a schematic perspective view of a composite aircraft turbomachine vane,

[0044] FIG. 3 is a block diagram showing steps of a method according to the invention for manufacturing a turbomachine part,

[0045] FIG. 4 is a schematic perspective view of a mould for manufacturing the vane of FIG. 2,

[0046] FIG. 5 comprises highly schematic cross-sectional views of a vane during some of the operations illustrated in FIG. 1,

[0047] FIGS. 6a and 6b are respectively a schematic perspective and cross-sectional view of a mould of the type shown in FIG. 4, in which a compliance coating in the sense of the invention is deposited,

[0048] FIGS. 7a and 7b are schematic cross-sectional views of a mould in which a compliance coating is deposited according to two alternative embodiments of the invention,

[0049] FIGS. 8a and 8b are schematic cross-sectional views of a mould in which a coating comprising a resin in particular is deposited,

[0050] FIGS. 9a and 9b are schematic cross-sectional views of a mould in which a coating comprising a preimpregnated cloth is deposited,

[0051] FIGS. 10a and 10b are schematic cross-sectional views of a mould in which a coating comprising a glue in particular is deposited, and

[0052] FIG. 11 is a schematic perspective view of a composite aircraft turbomachine casing.

DETAILED DESCRIPTION OF THE INVENTION

[0053] FIG. 1 has already been described above.

[0054] Reference is made to FIG. 2 which illustrates a composite material vane 16 for a turbomachine, this vane 16 being for example a fan or straightener vane of a secondary flow in the case of a turbofan engine.

[0055] The vane 16 comprises a blade 22 connected by a stilt 24 to a root 26 which has, for example, a dovetail shape and is shaped to be engaged in a complementarily shaped cell of a rotor disc, in order to retain the vane on this disc.

[0056] The blade 22 comprises a leading edge 16a and a trailing edge 16b for the gases flowing through the turbomachine. The blade 22 has a curved or twisted aerodynamic profile and comprises an intrados 28 and an extrados 30 extending between the leading 16a and trailing 16b edges.

[0057] The blade 22 is made from a fibrous preform 10 (see FIG. 1) obtained by three-dimensional weaving of fibres, for example carbon.

[0058] The leading edge 16a of the blade is reinforced and protected by a metal sheath 14 which is attached to this leading edge 16a. The sheath 14 is for example made of a nickel, cobalt and/or titanium based alloy.

[0059] This attachment can be carried out by co-moulding the preform 10 with the sheath 14, and on the other hand by gluing the sheath 14 with a glue 34.

[0060] FIG. 3 is a flowchart that illustrates steps in a method for manufacturing a composite vane 16 such as the one shown in FIG. 2.

[0061] The steps b) to e), which are surrounded by a dotted rectangle, represent a manufacturing method according to the prior art.

[0062] The first step b) of the method of the prior art comprises the production of the fibrous preform 10 by weaving fibres, preferably in three dimensions, using a weaving machine of the Jacquard type for example. The resulting preform 10 is raw and can undergo operations such as a cutting or a compression.

[0063] The preform 10 is then arranged in the mould 12 (FIG. 4).

[0064] The mould 12 is then closed, for example by means of a counter-mould not shown, and is heated according to a predefined heating cycle to a temperature of preferably between 160 and 200° C. and for example 180° C.

[0065] The method comprises a subsequent step c) of injecting polymerizable resin into the mould 12.

[0066] The resin injected into the mould 12 is intended to impregnate the preform 10.

[0067] The resin is for example an epoxy-based thermosetting resin.

[0068] The image on the left in FIG. 5 illustrates the surface state of the vane 16 as it leaves the mould 12.

[0069] The method then comprises a step d) of machining the vane 16, preferably by sandblasting. This corresponds to the first sandblasting operation S1 mentioned above and shown in FIG. 1. In the example shown in FIG. 5, the second image from the left shows a vane 16 with both faces, the intrados 16a and the extrados 16b, machined. A thickness of material was removed which exposed some of the fibres 38 of the vane.

[0070] The method then comprises a step e) of checking the part by an operator. In the context of the present invention, this check is visual and allows to validate at least one compliance criterion according to which the thickness of material removed during the preliminary machining step d) does not exceed a certain threshold which would be critical for the health of the vane.

[0071] The sheath 14 can then be fitted and attached by gluing to the edge of the preform 10. The sheath 14 is generally dihedral in shape and defines a groove with V-shaped cross-section into which an edge of the preform is inserted. The glue can be deposited in the groove of the sheath and/or on the edge of the preform 10.

[0072] A polyurethane film 40 is then deposited on the vane 16 (on the side of the extrados in the example shown) which then undergoes the second machining operation S2 mentioned above to modify its surface condition and in particular the surface condition of the area of the blade covered by the film 40. A bonding primer 18 and an anti-erosion paint 20 are then deposited to each of the faces of the blade, which then undergoes machining operations S3 of finishing with belt grinding and of grinding.

[0073] FIG. 3 shows the additional steps, some of which are optional, prior to the manufacturing method according to the invention.

[0074] The step b) is thus preceded by a step a) in which at least one compliance coating 50 is deposited in the mould 12. This coating 50 is intended to cover at least one area of the preform 10 and to be secured to it by the resin at the end of the step c).

[0075] This coating 50 has a calibrated thickness and at least one visual aspect identifiable by an operator.

[0076] It is therefore understood that in the step e), the operator must check for the presence of this particular aspect in the area, so as to validate the compliance of the vane. If this aspect is not visible, it means that the area covered by the coating 50 has been over-machined and the vane should be discarded.

[0077] The coating 50 therefore has a calibrated, i.e. controlled, thickness. This means that this thickness is known and constant over the entire length of the coating. This thickness is for example between 10 and 100 .Math.m, preferably between 20 and 60 .Math.m, and more preferably 40 .Math.m.

[0078] In the present application, “visual aspect “ means a distinguishing sign visible to the naked eye that allows easy identification of the areas of the vane coated with the coating from areas that would not be coated.

[0079] In a particular embodiment of the invention, this visual aspect is a colour, e.g. black, blue, yellow, etc., which is naturally different from the colour of the other portions or layers of the vane.

[0080] In one variant of embodiment, this visual aspect comprises a repetition of a same surface pattern. The coating may, for example, comprise a herringbone pattern which would be repeated throughout. This pattern could be obtained by a cloth for example, and in particular by a particular weaving pattern of this cloth in the case of a woven cloth. Alternatively, this pattern could be achieved by a printed or marked cloth, this cloth being not necessarily woven.

[0081] As can be seen in FIGS. 6a and 6b, the coating 50 is intended to be deposited in the mould, for example on the bottom of the mould, by spreading or spraying. FIG. 6b shows the calibrated thickness X of this coating 50.

[0082] This calibration can for example be achieved by the steps i) and ii) shown in FIG. 3.

[0083] Prior to the step a), the method comprises the step i) of positioning wedges 52 in the mould 12 (FIG. 6b). These wedges 52 each have a thickness equal to said calibrated thickness and are intended to define between them a space for depositing the coating 50.

[0084] Between the steps a) and b), the method then comprises the step ii) of removing the wedges 52 from the mould 12.

[0085] Depending on the nature of the coating and as will be discussed in more detail below in relation to more concrete examples of embodiments, the coating may comprise at least one polymerizable compound. In this case and in order to limit the displacement and the deformation of the coating 50 during the steps b) and c), an at least partial polymerisation of this compound and the coating can be carried out before the step b).

[0086] The method in FIG. 3 thus shows, between the steps a) and b), this step iii) of at least partial polymerisation of the coating 50. This polymerisation can be carried out by heating or baking the coating. This heating or this baking can take place before the coating is deposited in the mould 12 or even afterwards. In the latter case, the mould serves as a support for the coating for this polymerisation.

[0087] The method in FIG. 3 shows a further optional step iv), between the steps a) and b), of checking the thickness X of the coating 50, for example by Eddy Current.

[0088] FIGS. 7a to 10b illustrate several variants of implementation of the manufacturing method.

[0089] In the variant embodiment shown in FIGS. 7a and 7b, the coating 50 is a paint 54 of a predefined colour, which may be reinforced with a cloth 56 of woven or non-woven fibres. The visual aspect to be checked by the operator on the final vane obtained is the colour of the paint.

[0090] In the variant embodiment shown in FIGS. 8a and 8b, the coating 50 is a resin 58, which may or may not be coloured, and which may be reinforced with a woven or non-woven fibre cloth. The visual aspect is the colour of the resin and/or the particular weaving pattern of the cloth for example.

[0091] In the alternative embodiment shown in FIGS. 9a and 9b, the coating 50 is a resin pre-impregnated cloth 62 which may be reinforced with an additional fabric. The visual aspect is the colour of the cloth 62 or the resin and/or the particular pattern of the fabric for example.

[0092] In the variant embodiment shown in FIGS. 10a and 10b, the coating 50 is a glue 66 which may be reinforced with a cloth and/or a fabric 68. The visual aspect is the colour of the glue and/or the particular pattern of the fabric 68 for example.

[0093] Finally, FIG. 11 shows that the manufacturing method according to the invention is not only applicable to a vane but can be applied to other composite parts of a turbomachine, such as a casing 72, for example, as a casing undergoes machining operations, in particular of its external cylindrical surface.