METHOD FOR MANUFACTURING A FIBROUS PREFORM OF A BLADE

Abstract

The invention relates to a method for manufacturing a fibrous preform (15) comprising the following steps: (a) providing a blank (22) comprising at least first and second layers (23, 24) each comprising weft yarns (26), the weft yarns (26) of each of the first and second layers (23, 24) being connected to each other by the same warp yarns (27), (b) unlinking the warp yarns (27) and the weft yarns (26) on a part (P11) of the first layer (23) to form float yarns (28), (c) cutting the float yarns (28), characterized in that step (c) comprises the following substeps: (c0) positioning a protective mat (29) between the float yarns (28) of the first layer (23) and the second layer (24), and (c1) cutting the float yarns (28) with a motorized rotary cutting tool (30). Abbreviated figure: Figure 6

Description

Title of the invention: METHOD FOR MANUFACTURING A FIBROUS PREFORM OF A BLADE Technical field of the invention

[0001] The invention relates to the field of manufacturing processes for fibrous preforms of aircraft turbomachine blades.

[0002] The invention relates in particular to the field of manufacturing processes for fibrous preforms comprising a step of cutting the fibrous preform. Technical background

[0003] An aircraft turbomachine typically has a longitudinal axis. It includes, for example, from upstream to downstream in the direction of gas flow along the longitudinal axis, a fan, a low-pressure compressor, a high-pressure compressor, a combustion chamber, a high-pressure turbine, a low-pressure turbine, and a gas exhaust nozzle.

[0004] The blower allows the intake of an airflow that splits into a primary flow and a secondary flow. The primary flow passes through a primary channel of the turbomachine while the secondary flow is directed towards a secondary channel surrounding the primary channel.

[0005] The primary flow is compressed within the compressors. The compressed air is then mixed with a fuel and burned within the combustion chamber. The gases from the combustion pass through the turbines and then escape through the nozzle, the cross-section of which allows these gases to be accelerated to generate propulsion.

[0006] The blower typically comprises a movable disk rotating about the longitudinal axis and blades extending radially from the disk.

[0007] Each blade typically comprises a radially extending blade with an aerodynamic shape. The blade thus has an intrados and an extrados face connected by a leading edge and a trailing edge. The blade typically has a variable thickness, in particular a thickness that decreases towards the trailing edge.

[0008] The blades can be made of metallic material. However, in order to reduce the overall weight of the turbomachine while preserving the mechanical properties of the blades, it has been proposed to make the blades from a composite material. The composite material of the blades typically comprises a polymer matrix and fibers embedded in the polymer matrix. The polymer matrix is, for example, an epoxy resin. The fibers are, for example, glass or carbon fibers. The fibers are typically arranged in the form of a three-dimensional fibrous preform of the blade.

[0009] The three-dimensional fibrous preform typically comprises a plurality of Layers of woven threads. The number of layers depends on the thickness of the blade. Each layer comprises weft threads which are connected to each other by the same warp threads, forming a layered weave.

[0010] In order to provide a blade of variable thickness, it is necessary to manufacture a three-dimensional fibrous preform of also variable thickness. A fibrous preform of variable thickness is a preform in which the number of yarn layers varies. To produce such a preform, a rough draft of the fibrous preform is first created. In this step, the rough draft of the fibrous preform has a constant thickness equal to the maximum thickness of the blade. Then, the warp yarns are removed from a portion of a layer so that in this portion, the warp and weft yarns are unbound. The unbound, unwoven warp and weft yarns are generally called "floated yarns." These floated yarns are subsequently cut, resulting in a fibrous preform of variable thickness.

[0011] Although this manufacturing process allows for the production of a fibrous preform of variable thickness, it is not entirely satisfactory. Indeed, cutting the floated fibers is an operation performed manually by operators using cutting scissors. This is therefore a tedious, time-consuming, and costly step. Furthermore, performing this step manually poses a health risk to the operators, who must exert considerable effort to cut the blank.

[0012] Finally, since the blank is cut manually, there is a high risk of accidentally cutting woven threads from an underlying layer not intended to be cut. This creates a risk of non-conformity and the scrapping of the blade.

[0013] Therefore, there is a need to provide a solution that allows a fibrous preform with a variable thickness to be provided in a simple, fast, reliable and inexpensive way. Summary of the invention

[0014] To this end, the invention proposes a method for manufacturing a fibrous preform of an aircraft turbomachine blade, the method comprising the following steps:

[0015] (a) provide a blank exhibiting a three-dimensional weave, the blank comprising at least first and second layers of woven yarns, the first and second layers each comprising weft yarns, the weft yarns of each of the first and second layers being joined together by the same warp yarns,

[0016] (b) unraveling the warp yarns and the weft yarns over a portion of the first layer to form floating threads,

[0017] (c) cut the floating threads from this part of the first layer.

[0018] The manufacturing process is remarkable in that step (c) comprises the following substeps:

[0019] (cO) position a protective mat between the floating yarns of the first layer and the second layer, and

[0020] (cl) cut the floating threads with a motorized rotary cutting tool.

[0021] According to the invention, the blank cutting step therefore uses on the one hand a protective mat and on the other hand a motorized cutting tool.

[0022] The motorized cutting tool allows the floating wires of the blank to be cut efficiently, i.e. without effort for the operator, more precisely, i.e. limiting the risks of accidental cutting of the wires of the second layer and offering improved safety for the operator.

[0023] In addition, the protective mat helps to protect the threads of the second layer from accidental cutting during the handling of the cutting tool, which helps to improve the reliability of the cutting step by reducing scrap.

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

[0025] - the cutting tool includes a gripping handle and a rotating blade cutout connected to the gripping handle,

[0026] - the rotating blade is circular and free to rotate about its axis of revolution,

[0027] - the rotating blade has a diameter between 20 mm and 100 mm, of Preference between 30 mm and 50 mm,

[0028] - the rotating blade comprises a metallic material,

[0029] - the cutting tool further comprises a housing mounted around the rotating blade and featuring a suction duct,

[0030] - the housing is made of polymer material,

[0031] - the cutting tool includes a drive motor for the rotating blade,

[0032] - the protective mat comprises a polymeric material, preferably chosen among thermoplastics,

[0033] - the protective mat has a thickness between 1 mm and 10 mm, of Preference between 1 mm and 5 mm.

[0034] The invention also relates to a method for manufacturing an aircraft turbine blade, the manufacturing method comprising the following steps:

[0035] - supply the fibrous preform according to the fibrous preform manufacturing process according to any one of the above characteristics,

[0036] - densify the fibrous preform.

[0037] Advantageously, the densification step comprises the following steps:

[0038] - place the fibrous preform in a mold,

[0039] - inject a resin into the mold. Brief description of the figures

[0040] Other features and advantages will become apparent from the following description of non-limiting embodiments of the invention with reference to the accompanying drawings in which:

[0041] [Fig. 1] is a schematic longitudinal cross-sectional representation of half an aircraft turbomachine,

[0042] [Fig.2] is a schematic perspective representation of a dawn,

[0043] [Fig. 3] is a schematic perspective representation of part of the fibrous preform of the dawn of the [Fig.2],

[0044] [Fig. 4] is a schematic cross-sectional representation along a plane parallel to the third direction, of a rough version of the fibrous preform, in a first step of the fibrous preform manufacturing process,

[0045] [Fig. 5] is a schematic cross-sectional representation along a plane parallel to the third direction, of the blank in a second stage of the manufacturing process of the fibrous preform,

[0046] [Fig.6] is a schematic cross-sectional representation along a plane parallel to the third direction, of the blank in a third stage of the manufacturing process of the fibrous preform,

[0047] [Fig.7] is a perspective representation of the cutting tool according to the invention,

[0048] [Fig.8] is a synoptic diagram of the manufacturing process according to the invention. Detailed description of the invention

[0049] An example of a turbomachine 1 for an aircraft is shown in [Fig. 1]. The turbomachine 1 extends around and along a longitudinal axis A.

[0050] In the present application, the terms "upstream" and "downstream" are defined with respect to the direction of gas flow in the turbomachine 1 along the longitudinal axis A.

[0051] The terms “axial”, “axially”, “radial”, “radially” are defined with respect to the longitudinal axis A.

[0052] The terms "internal", "interior", "internally", "external", "exterior", "externally", are defined with respect to the distance from the longitudinal axis A along a radial axis.

[0053] The turbomachine 1 is preferably a turbojet, for example a twin-spool, twin-spool turbojet. It comprises, from upstream to downstream, a fan 2, at least one compressor such as a low-pressure compressor 3 and a high-pressure compressor 4, a combustion chamber 5, at least one turbine such as a high-pressure turbine 6 and a low-pressure turbine 7, and a nozzle exhaust gases.

[0054] The low-pressure and high-pressure compressors 3, 4 and the high-pressure and low-pressure turbines 6, 7 each comprise at least one rotor. The rotor of the low-pressure compressor 3 is connected to the rotor of the low-pressure turbine 7 by a low-pressure shaft 8, and the rotor of the high-pressure compressor 4 is connected to the rotor of the high-pressure turbine 6 by a high-pressure shaft 9. The high-pressure shaft 9 is arranged coaxially around the low-pressure shaft 8. The low-pressure and high-pressure shafts 8, 9 are centered on the longitudinal axis A.

[0055] The blower 2 comprises a rotating disc about the longitudinal axis A and blades 10 extending radially from the disc. The blower 2 further comprises a blower shaft 2a connected to the low-pressure shaft 8 via a speed reducer 11, for example.

[0056] The fan 2 may be of the shrouded type. The turbomachine 1 may therefore include a fan casing 2b. The fan casing 2b is annular and centered on the longitudinal axis X. It is arranged around the blades 10. According to another example, the fan 2 may be of the unshrouded type.

[0057] The blower 2 allows the intake of an airflow F which divides into a primary airflow Fl and a secondary airflow F2. The primary airflow Fl passes through a primary channel vl of the turbomachine 1 and the secondary flow F2 flows into a secondary channel v2 of the turbomachine 1. The secondary channel v2 surrounds the primary channel vl.

[0058] The primary flow Fl is compressed within the low pressure compressor 3 and then the high pressure compressor 4. The compressed air is then mixed with a fuel and burned within the combustion chamber 5. The gases formed by the combustion pass through the high pressure and low pressure turbines 6, 7. The gases finally escape through the nozzle whose cross-section allows the acceleration of these gases to generate propulsion.

[0059] With reference to [Fig.2], each blade 10 comprises a blade 12 extending between a head 13 and a foot 14. The blade 12 has an aerodynamic shape and comprises an intrados face 12i and an extrados face (not visible) connected by a leading edge 12a and a trailing edge 12b.

[0060] Each blade 10 has a variable thickness. For example, the blade 10 has a first thickness e1 as measured at the leading edge 12a greater than a second thickness e2 as measured at the trailing edge 12b. In particular, the thickness of the blade 10 decreases towards the trailing edge 12b.

[0061] According to the invention, each blade 10 comprises a composite material. The composite material is an organic matrix composite, also known by the acronym CMO. The composite material thus comprises fibers embedded in an organic matrix. The fibers are, for example, glass fibers, carbon fibers, ceramic fibers, or fibers of polyester, or polypropylene, or polyamide. The organic matrix is ​​chosen, for example, from thermosetting polymers such as epoxy resins or thermoplastic polymers such as polyolefins.

[0062] The fibers are typically organized in the form of a three-dimensional fibrous preform 15 of the blade 10.

[0063] With reference to [Fig. 3], the fibrous preform 15 comprises a plurality of layers 16, 17, 18 of woven yarns. The layers 16, 17, 18 are stacked along a first direction XI defining the thickness of the fibrous preform 15. Each layer 16, 17, 18 comprises weft yarns 20 extending along a second direction X2. The weft yarns 20 of the layers 16, 17, 18 are interconnected by warp yarns 21 extending along a third direction X3 perpendicular to the first and second directions XI, X2. In other words, the weft yarns 20 and the warp yarns 21 of the layers 16, 17, 18 are interlaced to form a weave. Advantageously, the weave is of the interlock type. Any other type of weave is applicable to the invention.

[0064] The fibrous preform 15 has a variable thickness according to the profile of the blade 10 along a chord of the blade profile 10 or along the longitudinal axis A. The fibrous preform 15 comprises at least a first part PI having a first thickness e1' and a second part P2 having a second thickness e2', for example, less than the first thickness e1'. In the first part PI of the fibrous preform 15, the number of layers 16, 17, 18 is greater than the number of layers 16, 17, 18 in the second part P2.

[0065] An example of a manufacturing process for the blade 10 will now be described with reference to [Fig. 8]. The manufacturing process for the blade 10 may include the following steps:

[0066] (100) provide the fibrous preform 15, and

[0067] (200) densify the fibrous preform 15.

[0068] The densification step (200) may include the following steps:

[0069] (201) place the fibrous preform 15 in a mold, and

[0070] (202) inject a resin into the mold.

[0071] According to the invention, the manufacturing process for the fibrous preform 15 comprises the following steps:

[0072] (a) provide a blank 22 of the fibrous preform 15, the blank 22 comprising first and second layers 23, 24 of woven yarns and optionally at least a third layer 25 of woven yarns, the first and second layers 23, 24 each comprising weft yarns 26, the weft yarns 26 of each of the first, second and third layers 23, 24, 25 being joined together by the same warp yarns 27,

[0073] (b) unraveling the warp yarns 27 and the weft yarns 26 on a first part PI 1 of the first layer 23 to form floating threads 28, and

[0074] (c) cut the floating threads 28 from this first part PI 1 of the first layer 23.

[0075] With reference to [Fig. 4], in step (a), the blank 22 of the fibrous preform 15 of The blade 12 has a constant thickness ell. The thickness ell of the blank 22 at this step (a) is equal to the first thickness el' of the first part PI of the fibrous preform 15.

[0076] In step (a), the weaving of the yarns of the blank 22 is advantageously of the interlock type.

[0077] With reference to [Fig. 5], in step (b), the warp yarns 26 are removed from the first part PI 1 of the blank 22, for example manually. At the end of this step (b), in this first part PI 1, the warp yarns 27 and the weft yarns 26 are unbound and are therefore no longer interlaced. The unbound warp yarns 27 and weft yarns 26 are floating yarns 28.

[0078] With reference to [Fig. 6], according to the invention, step (c) of cutting the floated wires 28 comprises the following steps:

[0079] (cO) position a protective mat 29 between the floated wires 27 of the first layer 23 and the wires 26, 27 of the second layer 24, and

[0080] (cl) cut the floating wires 28 with a motorized rotary cutting tool 30.

[0081] The protective mat 29 allows the protection of the wires of the second layer 25 during the cutting step (c) in order to limit the risks of accidental cutting of the wires of the second layer 25.

[0082] The protective mat 29 can extend for example over the entire first part of the fold along the second and third directions X2, X3.

[0083] The protective mat 29 comprises a polymeric material. The polymeric material may be a thermoplastic polymer or a thermosetting polymer. The thermoplastic polymer is, for example, selected from polyolefins, fluoropolymers, styrenic polymers, polyacrylic polymers, polyamides, polyesters, or polychlorides. Preferably, the thermoplastic polymer is polyvinyl chloride (PVC). The thermosetting polymer is, for example, selected from epoxy resins.

[0084] The protective mat 29 may comprise a plurality of superimposed protective layers. The protective mat 29 comprises, for example, three protective layers 29.

[0085] Advantageously, the protective mat 29 has a thickness of between 1 mm and 10 mm, preferably between 1 mm and 5 mm, and even more preferably 3 mm. Such a thickness of the protective mat 29 allows for easy handling while ensuring effective protection of the threads of the second layer 25 during the cutting step (c).

[0086] The rotary, motorized cutting tool 30 enables fast and effortless cutting by an operator. The operator's health is protected, and production rates are increased compared to manual cutting without a motorized cutting tool. The cutting tool 30 allows for precise cutting and further reduces the risk of accidentally cutting the second layer 24.

[0087] Preferably, the cutting tool 30 comprises a gripping handle 31 and a rotating cutting blade 32 connected to the gripping handle 31.

[0088] The gripping handle 31 facilitates gripping the cutting tool 30. The gripping handle 31 has an elongated shape. This shape of the gripping handle 31 increases operator safety by keeping the rotating blade 32 further away.

[0089] The gripping handle 31 may include a coating. The coating in particular includes a polymeric material such as polyurethane or polyamide.

[0090] The rotating blade 32 has a circular or annular shape. It thus has an axis of revolution R. The rotating blade 32 has a diameter, for example, between 20 mm and 100 mm, preferably between 30 mm and 50 mm, and even more preferably 45 mm. The diameter of the rotating blade can be adjusted according to the dimensions of the blank 22. The rotating blade 32 can have a rotational speed between 150 rpm and 300 rpm, preferably between 200 rpm and 250 rpm, and even more preferably 240 rpm, the acronym rpm standing for "revolutions per minute".

[0091] The rotating blade 32 comprises a metallic material, such as titanium. Such a material allows for efficient cutting of the floating wires 27. The rotating blade 32 may be diamond-coated.

[0092] According to an advantageous embodiment illustrated in [Fig.7], the cutting tool 30 comprises a housing 33 mounted around the rotating blade 32. The housing 33 advantageously comprises a semi-annular body 34 centered on the axis of revolution R and a suction conduit 35 extending outward from the body 34.

[0093] The body 34 is connected to the gripping handle 31 and is fixedly mounted around the rotating blade 32.

[0094] The suction duct 35 allows the aspiration of debris generated during the cutting step (c), thus preventing contamination of the blank 22 and consequently, of the fibrous preform 15. The suction duct 35 may have a diameter between 20 mm and 50 mm, preferably between 20 mm and 30 mm, and even more preferably 27 mm. The suction duct 35 may be connected to a suction device.

[0095] The housing 33 is preferably made of polymer material. This allows to reduce the overall weight of the cutting tool 30.

[0096] The cutting tool 30 includes, in a manner not illustrated, a drive motor for the cutting blade 30.

[0097] Thanks to the automated cutting tool 30 and the protective mat 29 according to the invention, it is possible to achieve an efficient, reliable, fast and safe cutting of the blank 22 of the fibrous preform 15.

Claims

Demands

1. A method for manufacturing a fibrous preform (15) of an aircraft turbomachine (1) blade (12), the method comprising the following steps: (a) providing a blank (22) having a three-dimensional weave, the blank (22) comprising at least first and second layers (23, 24) of woven yarns, the first and second layers (23, 24) each comprising weft yarns (26), the weft yarns (26) of each of the first and second layers (23, 24) being linked together by the same warp yarns (27), (b) unlinking the warp yarns (27) and the weft yarns (26) on a portion (PI 1) of the first layer (23) to form float yarns (28), (c) cutting the float yarns (28) from this portion (PI 1) of the first layer (23), characterized in that step (c) comprises the sub-steps following: (cO) position a protective mat (29) between the floating yarns (28) of the first layer (23) and the second layer (24),and (cl) cut the floating threads (28) with a motorized rotary cutting tool (30).

2. A manufacturing method according to the preceding claim, characterized in that the cutting tool (30) comprises a gripping handle (31) and a rotating cutting blade (32) connected to the gripping handle (31).

3. A manufacturing method according to the preceding claim, characterized in that the rotating blade (32) is circular and movable in rotation around its axis of revolution (R).

4. A manufacturing method according to claims 2 and 3, characterized in that the rotating blade (32) has a diameter between 20 mm and 100 mm, preferably between 30 mm and 50 mm.

5. A manufacturing method according to any one of claims 2 or 3 or 4, characterized in that the rotating blade (32) comprises a metallic material.

6. A manufacturing method according to any one of claims 2 to 5, characterized in that the cutting tool (30) further comprises a housing (34) mounted around the rotating blade (32) and having a suction conduit (35).

7. A manufacturing process according to the preceding claim, characterized in that the casing (34) is made of polymer material.

8. A manufacturing method according to claim 2 or any of the preceding claims in combination with claim 2, characterized in that the cutting tool (30) comprises a drive motor for the rotating blade (32).

9. A manufacturing method according to any one of the preceding claims, characterized in that the protective mat (29) comprises a polymeric material, preferably selected from thermoplastics.

10. A manufacturing method according to any one of the preceding claims, characterized in that the protective mat (29) has a thickness of between 1 mm and 10 mm, preferably between 1 mm and 5 mm.

Images