TOOLING FOR BONDING AN ANTI-WEAR STRIP ON A TURBOMACHINE BLADE

Abstract

Tooling (40) for bonding at least one wear-resistant strip (22) to a turbomachine blade (10), comprising: - a support (50), - at least one first fastening member (60) fixed to the support (50) and adapted to cooperate with the base (14) of the blade (10) in order to immobilize it relative to the support (50), and - at least one second member (70) for holding said at least one wear-resistant strip (22) on the blade (10) and for heating this wear-resistant strip (22) for bonding, this second member (70) being fixed to the support (50) and comprising, on the one hand, at least one expanding cushion (72), and on the other hand, at least one heating element (80) adapted to heat said at least one wear-resistant strip (22) for bonding. Figure for the abbreviation: Figure 5

Description

Title of the invention: TOOL FOR BONDING AN ANTI-WEAR STRIP TO A TURBOMACHINE BLADE Technical field of the invention

[0001] The present invention relates to a tool for bonding at least one anti-wear strip to a turbomachine blade. It further relates to an assembly comprising a tool and a blade, as well as a bonding method using the tool. Technical background

[0002] The use of composite materials is particularly advantageous in the aeronautical industry because these materials are relatively light and have good mechanical properties.

[0003] A composite material commonly used in aeronautics comprises a fibrous preform embedded in a polymer resin. The preform may be produced by three-dimensional weaving or may be obtained by draping and layering several fabrics.

[0004] The resin can be injected into the preform or the preform can be pre-impregnated with the resin.

[0005] The final part is generally shaped using tooling that includes a mold. If resin is to be injected into a preform, the preform is placed in the cavity of a mold, and the mold is covered with a counter-mold. The tooling includes a resin injection port in the mold cavity and a port for evacuating the mold cavity.

[0006] In the case where the preform is already impregnated with the resin, the preform is placed in the cavity of a mold which can be covered with a flexible tarpaulin or a counter-mold.

[0007] The tooling also includes a resin injection port in the mold cavity and a port for vacuuming the mold cavity. The counter-mold applies pressure to the preform due to the vacuum created between the counter-mold and the flexible sheet or the mold. The use of a counter-mold allows for better control of the thickness of the final part.

[0008] In the case of a blade, in particular a blower blade, after the molding operation described above, an operation of applying anti-wear strips to the foot and Péchasse of the blade must be carried out.

[0009] These strips are currently attached and secured to the foot and stilt of the dawn by gluing. Thus, the anti-wear strips are first impregnated with glue, in general phenolic, by hand. Then, the operator places, still manually, the anti-wear strips on the foot and Péchasse de l'aube.

[0010] The blade, now fitted with the wear-resistant strips, is then placed back in the mold, and the wear-resistant strips are bonded under vacuum using a counter-mold or a silicone sheet. The assembly is then placed in an autoclave to heat the strips and bond them to the blade. The adhesive used to attach the strips is a hot-polymerizable type and requires a heating cycle to perform its function.

[0011] This operation of bonding the anti-wear strips is therefore very manual and generates numerous defects in the final part. One of the difficulties encountered with the current process of bonding anti-wear strips to a blade is the difficulty of positioning the strips, to within several tens of millimeters, by hand, on an irregular shape and the difficulty of maintaining this positioning of the strips during the operation of installing the blade coated with the anti-wear strips in the mold and during the vacuum bonding operation.

[0012] Furthermore, there is a significant risk of leakage from the tarpaulin during the autoclave heating cycle (improper seal application, presence of thermocouples, micro-perforations in the waterproof tarpaulin, etc.), which could lead to non-conformities. In addition, this heating cycle generates a large amount of waste because the tarpaulins are single-use consumables (several tons per year).

[0013] The overall cost of the current process is also relatively high.

[0014] Finally, the composite material of the blade can be relatively sensitive to high temperatures and can be thermally affected by the autoclave heating process. This can impact the number of possible adjustments / repairs to the blade, and therefore can limit the blade's service life.

[0015] The present invention proposes a solution to at least some of the problems mentioned below. Summary of the invention

[0016] The invention relates to a tool for bonding at least one anti-wear strip to a turbomachine blade, this blade comprising a foot connected to a blade and at least one anti-wear strip located on the blade, the tool comprising:

[0017] - a support,

[0018] - at least one first fastening element which is fixed to the support and which is capable of cooperate with the dawn in order to immobilize it in relation to the support,

[0019] characterized in that it further comprises:

[0020] - at least one second retaining element for said at least one anti-wear strip on the dawn and heating of this anti-wear strip for the purpose of its bonding, this second component being fixed to the support and comprising on the one hand at least one expanding cushion capable of adopting a first non-expanded position and a second expanded position in which said at least one cushion is capable of applying pressure on at least one anti-wear strip located on the blade, and on the other hand at least one heating element capable of heating said at least one anti-wear strip for the purpose of gluing it.

[0021] The invention offers several advantages. First, it allows for the precise positioning and securing of the anti-wear strip(s) on the blade by means of the second retaining element(s), preventing them from shifting during the bonding process. Furthermore, this element(s) allows(s) for the application of a predetermined pressure on the strip(s), this pressure being a function of the expansion of the cushion(s). Each cushion is thus expandable between two positions. Finally, the heating element(s) allows(s) for the localized heating of the strip(s), thus avoiding the need to autoclave the entire blade and therefore heating the entire blade. Only the area of ​​the blade receiving the anti-wear strip(s) can be heated, for example, by conduction through the strip, which limits the blade material's exposure to the heating cycle and therefore improves its lifespan.Finally, the tooling is relatively simple and compact, and significantly less expensive than a mold designed to completely enclose the blade for the purpose of bonding anti-wear strip(s).

[0022] The tooling according to the invention may comprise one or more of the following features, taken individually or in combination with each other: - said at least one second organ is independent of said at least one first fixing organ; - said at least one expandable cushion is or includes at least one inflatable bladder; - said at least one second organ includes at least one pressurized air supply channel to said at least one inflatable bladder; - said at least one heating element is or includes at least one heating mat, and in particular a resistive heating mat; - said at least one heating mat is located on or under said at least one expanding cushion; - said second organ comprises a first cushion suitable for extending over a first side of the vane or its foot, a second cushion suitable for extending over a second opposite side of the vane or its foot, or even a third cushion suitable for extending over an upstream or downstream edge of the vane or its foot; - said second organ defines an elongated slot which is configured to receive the blade or its foot by sliding and which includes one or more cushions along its internal edges.

[0023] The present invention also relates to an assembly comprising tooling such as described above and a turbomachine blade, this blade comprising a foot connected to a blade and at least one anti-wear strip located on the blade.

[0024] The blade according to the invention may comprise one or more of the following features, taken individually or in combination with each other:

[0025] — the one or each anti-wear band is made by weaving fibers such as fibers aramids and / or PTFE;

[0026] — the blade is made of composite material from a fibrous preform whose fibers, for example carbon, are coated or impregnated with polymerizable resin and in particular crosslinkable resin (such as an epoxy resin).

[0027] The present invention further relates to a method for bonding at least one anti-wear strip to a turbomachine blade, this blade comprising a foot connected to a blade and at least one anti-wear strip located on the blade, the method using tooling as described above and comprising the following steps: a. immobilization of the blade relative to the tooling support, by means of the first fastening element, b. expansion of said at least one cushion and application of pressure to said at least one anti-wear strip located on the blade, and c. heating of this anti-wear strip for the purpose of gluing it onto the blade, using said at least one heating element.

[0028] Advantageously, before step a), the foot of the blade is inserted into the slot of the second organ.

[0029] Preferably, before step a) and mounting the blade in the tooling, the anti-wear strip or strips are coated with glue and positioned on the blade.

[0030] The glue is, for example, a phenolic glue. Brief description of the figures

[0031] 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:

[0032] [Fig-1] [Fig.1] is a schematic perspective view of a turbine blade for a turbine aircraft engine,

[0033] [Fig.2] [Fig.2] is a larger-scale schematic view of part of the blade of [Fig.1], and in particular of its foot on which anti-wear strips are located,

[0034] [Fig.3] [Fig.3] is a very schematic cross-sectional view of a tool for bonding anti-wear strips onto the blade,

[0035] [Fig.4] [Fig.4] is a schematic perspective view of part of the tooling of the [Fig.3],

[0036] [Fig. 5] [Fig. 5] is a schematic perspective view of a gluing tool anti-wear strips on a blade, according to one embodiment of the invention,

[0037] [Fig. 6] [Fig. 6] is another schematic perspective and transparency view of the tooling of [Fig.5],

[0038] [Fig.7] [Fig.7] is a schematic perspective view of a detail of the tooling the [Fig.5],

[0039] [Fig.8] [Fig.8] is a schematic view of another detail of the tooling of [Fig.5], and

[0040] [Fig.9] [Fig.9] is another schematic perspective view of the tooling of [Fig.5]. Detailed description of the invention

[0041] Reference is made first to figures 1 and 2 which illustrate a blade 10 made of composite material for a turbomachine, in particular for an aircraft, this blade 10 being for example a propeller or fan blade.

[0042] The blade 10 comprises a blade 12 connected for example by a strut 14 to a foot 16. The foot 16 may have a dovetail shape and is shaped to be engaged in a socket of complementary shape of a rotor disk, in order to retain the blade on this disk.

[0043] The blade 12 comprises a leading edge 12a and a trailing edge 12b of the gases flowing into the turbomachine. The blade 12 has a curved or even twisted aerodynamic profile and comprises an intrados 18 and an extrados 20 extending between the leading edge 12a and trailing edge 12b.

[0044] Anti-wear fabric strips 22 are attached to the blade 10.

[0045] In the example shown, the blade 10 includes four anti-wear strips 22, namely two on each side of the foot 16 and two more on each side of the stilt 14 or the blade 12.

[0046] As their name indicates, the strips 22 are configured to limit wear on the surfaces to which they are attached, by contact and / or friction. These strips 22 are located on the foot 16 and the strut 14 or the blade 12, which are likely to come into contact with the bearing surfaces of the aforementioned rotor disc.

[0047] Each band 22 has a generally elongated shape and extends substantially from the leading edge 12a to the trailing edge 12b of the blade 12. A band 22 has, for example, a length between 2 and 50cm, and a width between 2 and 7cm.

[0048] An anti-wear strip 22 is made by weaving fibers such as aramid fibers and / or PTFE.

[0049] The blade 10 is made of composite material from a fibrous preform whose fibers, for example carbon, are coated or impregnated with poly- resin merizable and in particular crosslinkable (such as an epoxy resin).

[0050] The tooling used to manufacture the blade 10 includes a mold and a counter-mold, the mold and the counter-mold defining between them a cavity configured to receive the fibrous preform.

[0051] During the manufacturing of a blade, the tooling is opened and a fibrous preform is placed in the cavity. This can be achieved with a three-dimensional woven preform or with fabrics that are draped and layered within the cavity. This step can be performed manually or by robot. The tooling is then closed by sealing the counter-mold onto the mold.

[0052] The preform is pre-impregnated with resin or resin is injected into the mold to impregnate the preform.

[0053] The tooling is heated to increase the temperature of the resin and induce its polymerization.

[0054] After polymerization of the resin and rigidification of the blade, the strips 22 are glued, for example with a phenolic glue, onto the blade 10.

[0055] For this purpose, the tooling 24 illustrated in figures 3 and 4 is used in the prior art.

[0056] The tooling 24 includes a mold 26 and a counter-mold 28 or a flexible sheet, the mold 26 and the counter-mold 28 defining between them a cavity 30 configured to receive the blade 10 ([Fig.3]).

[0057] Before installing the blade 10 in the mold, the fabric strips 22 are coated with glue and then positioned on the blade 10. The blade 10 is then installed between the mold 26 and the counter-mold 28. The strips 22 are held on the blade 10 and applied with a certain pressure to the blade 10 by compressing the blade 10 between the mold 26 and the counter-mold 28 or by applying a vacuum to the tarpaulin which covers the blade 10 and the mold 26.

[0058] The tooling 24 is then placed in an autoclave to heat the adhesive and ensure its polymerization. The strips 22 are then bonded to the blade 10, which can be removed from the mold after the autoclave heating cycle.

[0059] Alternatively, the strips 22 could be glued onto the blade 10 outside the mold.

[0060] The gluing operation therefore remains an essentially manual operation which is the source of many defects in the final part, as we have seen previously.

[0061] Figures 5 and following illustrate an embodiment of a tool 40 according to the invention which allows the bonding of one or more strips 22 onto a blade 10.

[0062] This tooling 40 essentially comprises three parts, namely:

[0063] - a support 50,

[0064] - at least one blade fixing element 60 10,

[0065] - at least one organ 70 for holding the band(s) 22 on the vane 10.

[0066] In the example shown, the support 50 is in the form of a flat plate which is intended to be placed flat on a horizontal surface such as a workshop workbench.

[0067] The support 50 thus includes an upper surface 50a substantially flat and horizontal in the example.

[0068] The support 50 may include a plurality of tapped holes 52 for screwing screws 54.

[0069] The support 50 may include markings 56, such as positioning lines, intended to facilitate the positioning of the blade 10 when it is mounted in the tooling 40.

[0070] The fixing member 60, also called the first member, is fixed to the support 50 and is able to cooperate with the blade 10, and for example or especially its foot, in order to immobilize it with respect to the support 50.

[0071] In the example shown, the fixing member 60 first of all comprises a base 62 which is fixed on the support 50 and which is intended to be interposed between the blade 10 and the support 50. In other words, the blade 10 rests on the base 62 fixed on the support 50.

[0072] The base 62 has an adjustable position relative to the support 50, in particular along an axis A which is intended to extend along an axis B of extension of the foot 16. The position of the base 62 along the axis A can thus be modified and immobilized, the aforementioned marks 56 allowing a reference point for the position chosen or to be adopted.

[0073] The movement of the base 62 on the support can allow the blade 10 to be positioned precisely with respect to the support 50.

[0074] The movement of the base 62 on the support 50 can be made possible by means of a rail-slide type system 64 carried by the support 50 and intended to receive the base 62.

[0075] The fixing of the system 64 on the support 50 or the immobilization of the base 62 on the support 50 can be achieved by means of the aforementioned screws 54.

[0076] In the example shown, the fixing member 60 further includes jaws 66 which are intended to extend on either side of the blade 10 or its foot 16 and which are intended to clamp it in order to immobilize it.

[0077] It is understood that the distance between the jaws 66 is adjustable, for example from a wide position allowing the blade 10 to be mounted between the jaws 66, to a close position allowing the blade 10 to be clamped and immobilized between the jaws 66.

[0078] Flexible pads 68, for example made of elastomer, can be carried by the jaws 66 and resting on the blade 10 in order to avoid damaging its material.

[0079] Although not shown in the drawings, these jaws 66 can be connected or fixed to support 50 by appropriate means.

[0080] The support organ 70, also called the second organ, has a dual function.

[0081] It allows the band(s) 22 to be held on the blade 10 on the one hand, but also to Heat each of these strips 22 in preparation for gluing them. Therefore, autoclaving the tooling 10 is no longer necessary.

[0082] The retaining member 70 is fixed to the support 50 for example by means of the aforementioned screws 54.

[0083] As can be seen in the drawings, and in particular in [Fig. 5], the components 60 and 70 are advantageously independent. This means that they are fixed to the support 50 independently of each other and can also be removed independently of each other. This also means that they can be handled and adjusted independently of each other.

[0084] The retaining member 70 comprises, on the one hand, at least one expandable cushion 72 capable of adopting a first non-expanded position and a second expanded position to apply a predetermined pressure on the or each strip 22 located on the blade, and on the other hand, at least one heating element 80 capable of heating the or each strip 22 for the purpose of its bonding.

[0085] By expansion, we mean a capacity to increase in volume. The cushion or each cushion 72 therefore has the capacity to increase in volume and to move from a non-expanded position of low volume to an expanded position of greater volume.

[0086] In a preferred embodiment, the cushion or cushions 72 are or comprise at least one inflatable bladder. The bladder is inflated by means of a fluid, such as air. It is therefore understood that supplying air to the bladder causes it to inflate and thus expand, and that removing the air from the bladder causes it to deflate and thus reduce its volume.

[0087] In the case where each cushion 72 is an inflatable bladder, the organ 70 includes at least one channel 74 for supplying pressurized air to each bladder as illustrated in [Fig.7].

[0088] Inflating a bladder can be done in a few seconds (between 2 and 10 seconds for example), at a relative pressure between 0.1 bar and 3 bars for example (0.01 to 0.3 MPa), this relatively low pressure level allows the use of inexpensive and readily available tools.

[0089] In the example shown, the tooling 40 includes several cushions 72 or bladders. These cushions 72 are, for example, three in number, although this number is not limiting.

[0090] The organ 70 defines an elongated slot 76 which is configured to receive the blade 10 or its foot 16 by sliding and which includes one or more cushions along its internal edges.

[0091] The member 70 has a general M-shape in the example shown and includes a middle part 78 comprising this slot 76. The sides of the member 70 and the M-shape are formed by two tabs 79 which are fixed to the support by screws 54.

[0092] The middle part 78 of the organ 70 extends above the base 62. It is therefore understood that the foot 16 of the blade 10 is inserted in the slot 76 and rests on the base 62 located directly below the slot 76.

[0093] The slot 76 is open at one of its longitudinal ends, opposite here to the marks 56. The slot 76 thus comprises three edges, namely two lateral edges 76a intended to extend on either side of the blade 10 or its foot 16, and a median edge 76b connecting these lateral edges 76a.

[0094] As can be seen in the drawings, each of these edges 76a, 76b carries a cushion 72. The cushions 72a located at the edges 76a have an elongated shape and extend over the entire length of the slot 72. These cushions 72 are intended, in the expanded position, to bear against the strips 22 applied to the blade 10, in order to apply a certain pressure on these strips.

[0095] The cushion 72b located at the edge 76b extends over the entire width of the slot 72. It bears on the blade 10 and in particular on an upstream (or leading) or downstream (or trailing) edge of the blade or its foot, but is not necessarily used to bear on a band 22 of the blade.

[0096] The heating element(s) 80 may be or may include at least one heating mat, and in particular a resistive heating mat. This heating mat may be located on or under each cushion 72. It may thus be in direct contact with the strip to be heated or heat a strip through the cushion 72, by conduction and / or convection. Heating by conduction allows for more localized heating and reduces the risk of thermally affecting the material of the blade 10.

[0097] Alternatively, the heating element or each heating element 80 is formed by an electrical heating resistance integrated for example in the cushion or each cushion 72.

[0098] The heating element 80 is preferably suitable for heating the strip 22 to a temperature between 80°C and 200°C for example.

[0099] The present invention also relates to the assembly formed by the tooling 40 and the blade 10.

[0100] The present invention further relates to a method of bonding at least one anti-wear strip onto a turbomachine blade 10, this method using the tooling 40 as described above.

[0101] The process comprises the following steps, some of which are optional:

[0102] - the strips are coated with glue and are positioned on the blade 10 or its foot 16,

[0103] - the tooling cushions 72 are (brought) into a non-expanded position,

[0104] - the blade is mounted in the tooling 40, by inserting its foot between the jaws 66 that is to say, in slot 72 of organ 70,

[0105] - the blade 10 is immobilized vis-à-vis the support 50 by means of the fastening member 60,

[0106] - the cushions 72 are expanded so that they assume their expanded position and that they bear against the bands 22 located on the blade 10, and apply a certain pressure to these bands 22,

[0107] - the heating of the strips 22 is activated in order to bond them to the blade, thanks to the heating element 80 of each cushion 72; heating can be carried out at a polymerization temperature between 80°C and 200°C for a duration of between 1h and 4h, depending on the glue used.

[0108] It is understood that the position of the cushions 72 of the component 70 depends on the position of the bands 22 on the blade 10. In the example shown, the bands are located at the foot 16 of the blade 10, and the cushions 72 are therefore located at the foot of the blade. Alternatively, the bands could be located at another area of ​​the blade, in which case the cushions 72 would be located at that area. The tooling 40 would therefore be adapted according to the position of the bands 22 on the blade 10, and this adaptation would be within the capabilities of a person skilled in the art.

[0109] The invention thus offers several advantages, including: limiting the exposure of the blade to the heating and polymerization cycle of the adhesive (which reduces the impact on the number of possible adjustments / repairs of the blade), the reliable positioning and maintenance of the blade during the bonding and polymerization stage, maintaining pressure on the bands on the blade, Reducing the time and cost of implementing the bonding process: particularly through the simplification of tools, the elimination of the risk of non-compliance linked to a leak from the vacuum tank of the previous technique, the reduction of waste from the autoclave bonding process, the use of tooling for the manufacture of the blade but also for its possible repair with a view to changing its anti-wear strips.

Claims

Claims

1. Tooling (40) for bonding at least one anti-wear strip (22) to a turbomachine blade (10), this blade (10) comprising a root (16) connected to a blade (12) and at least one anti-wear strip (22) located on the blade (10), the tooling (40) comprising: - a support (50), - at least one first fixing member (60) which is fixed to the support (50) and which is capable of cooperating with the blade (10) in order to immobilize it with respect to the support (50), characterized in that it further comprises: - at least one second member (70) for holding said at least one anti-wear strip (22) on the blade (10) and for heating this anti-wear strip (22) with a view to bonding it,this second member (70) being fixed to the support (50) and comprising on the one hand at least one expandable cushion (72) capable of adopting a first non-expanded position and a second expanded position in which said at least one cushion (72) is capable of applying pressure to at least one anti-wear strip (22) located on the blade (10), and on the other hand at least one heating element (80) capable of heating said at least one anti-wear strip (22) with a view to bonding it.,

2. Tooling (40) according to claim 1, wherein said at least one second member (70) is independent of said at least one first fixing member (60).

3. Tooling (40) according to claim 1 or 2, wherein said at least one expandable cushion (72) is or comprises at least one inflatable bladder.

4. Tooling (40) according to claim 3, wherein said at least one second member (70) comprises at least one channel (74) for supplying pressurized air to said at least one inflatable bladder.

5. Tooling (40) according to one of claims 1 to 4, wherein said at least one heating element (80) is or comprises at least one heating mat, and in particular a resistive heating mat.

6. The tooling (40) of claim 5, wherein said at least one heating mat is located on or under said at least one expandable pad (72).

7. Tooling (40) according to one of claims 1 to 6, in which said second member (70) comprises a first cushion (72a) capable of extending on a first side of the blade (10) or its root (16), a second cushion (72a) capable of extending on a second opposite side of the blade (10) or its root (16), or even a third cushion (72c) capable of extending on an upstream or downstream edge of the blade (10) or its root (16).

8. Tooling (40) according to one of claims 1 to 7, wherein said second member (70) defines an elongated slot (76) which is configured to receive the blade (10) or its root (16) by sliding and which comprises one or more cushions (72a, 72b) along its internal edges.

9. Assembly comprising a tool (40) according to one of the preceding claims and a turbomachine blade (10), this blade (10) comprising a root (16) connected to a blade (12) and at least one anti-wear strip (22) located on the blade.

10. Method for bonding at least one anti-wear strip (22) to a turbomachine blade (10), this blade (10) comprising a root (16) connected to a blade (12) and at least one anti-wear strip (22) located on the blade (10), the method using a tool (40) according to one of claims 1 to 8 and comprising the following steps: a. immobilizing the blade (10) with respect to the support (50) of the tool (40), by means of the first fixing member (60), b. expanding said at least one cushion (72) and applying pressure to said at least one anti-wear strip (22) located on the blade (10), and c. heating this anti-wear strip (22) with a view to bonding it to the blade (10), by means of said at least one heating element (80).

11. Method according to the preceding claim, in which the tooling (40) is as defined in claim 8 and in which, before step a), the root (16) of the blade (10) is inserted into the slot (76) of the second member (70).

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