Method for manufacturing a part from a thermosetting material reinforced with fibers

Abstract

[Title] Method for manufacturing a part from a fiber-reinforced thermosetting material. Method for manufacturing at least one part (1; 18) comprising at least locally a rounded shape and / or an angle and formed from a fiber-reinforced thermosetting material, the method comprising the following successive steps: - at least one step (100; 110) of winding at least one pre-impregnated fiber of a thermosetting material to form on the mandrel (M) a drape (8; 21) comprising a plurality of layers of wound and superimposed fibers, - at least one step (200; 210) of cutting the drape (8; 21) formed, - at least one step (300; 310) of removing from the mandrel (M) one or more preforms (11, 12; 22, 23) of said part (1; 18) to be manufactured from the drape (8; 21) cut, and - a step (500; 510) of polymerization inside a mold (15) of at least one of the preforms (11, 12; 22, 23) obtained.

Description

Title of the invention: Method for manufacturing a part from a thermosetting material reinforced with fibers Technical field of the invention

[0001] The present invention relates, in general, to parts made of composite material comprising a thermosetting material reinforced with fibers.

[0002] More specifically, the invention relates to a method for manufacturing a part comprising at least locally a rounded shape and / or an angle, and formed in a fiber-reinforced thermosetting material, such as a fitting for connecting at least two members. Prior art

[0003] The use of a fitting made of composite material, in particular of a thermosetting material reinforced with fibers, such as carbon or glass fibers, is particularly interesting as a replacement for metal fittings in fields where weight saving is essential, such as in aeronautics.

[0004] Certain types of fittings have at least locally complex, rounded and / or angled shapes.

[0005] It is known to manufacture these fittings from sheets formed by a flat stacking of layers of fibers bonded by a thermosetting material.

[0006] The sheets are deformed and assembled to create a preform. Certain portions of the sheets are pleated, folded, or even cut and moved to form the rounded portions and angles of the fitting to be manufactured.

[0007] Conventionally, the preform is introduced into a mold for compression and polymerization of the thermosetting material, or subjected to other known cooking processes, and the fitting thus obtained is extracted from the mold.

[0008] However, pleating the sheets to create non-deployable, rounded or angular shapes using such a manufacturing process implies mechanical weaknesses which greatly impair the performance of the fitting by reducing its mechanical resistance properties.

[0009] Furthermore, the correct arrangement of the material in the rounded portions and angles to form the preform remains complex, which hinders industrialization. Summary of the invention

[0010] The invention therefore aims to remedy these drawbacks and to propose a simple manufacturing process for a part, such as a fitting, in a thermosetting material reinforced with fibers and comprising complex non-deployable portions, which retains the mechanical properties of the part.

[0011] A manufacturing process is therefore proposed for at least one part comprising at least locally a rounded shape and / or an angle and formed from fiber-reinforced thermosetting material, characterized in that it comprises the following successive steps:

[0012] - at least one winding step of at least one pre-impregnated fiber of a thermosetting material, or at least one fiber not impregnated with a thermosetting material, around a mandrel to form on the mandrel a drape comprising one layer of wound fibers or several layers of wound and superimposed fibers,

[0013] - at least one step of cutting the formed drape,

[0014] - at least one mandrel removal step from one or more preforms of said a piece to be made from the cut drapery,

[0015] - optionally a step of adding thermosetting material to the preform when the fiber wound around the mandrel is a fiber not impregnated with a thermosetting sand material,

[0016] - a polymerization step inside a mold of at least one of the preforms obtained, and

[0017] - an extraction step of the obtained part out of the mold.

[0018] Such a manufacturing process makes it possible to obtain a composite part with a thermosetting matrix reinforced with fibers and comprising at least one complex, non-deployable shape, such as a rounded portion or an angle, without the need for pleating, folding, or cutting to conform the preform to the desired shape. Thus, a composite part is obtained with increased mechanical strength compared to a part obtained by flat stacking layers of fibers.

[0019] The production of preforms by filament winding facilitates the manufacturing process of composite parts with a thermosetting fiber-reinforced matrix containing non-deployable portions. Such a manufacturing process becomes faster, reproducible and industrializable.

[0020] Advantageously, the polymerization step may include a step of compressing the preforms obtained inside the mold.

[0021] Advantageously, a filler material such as a bulk molding mix can be added to the mold before the compression and polymerization step.

[0022] Advantageously, the step of winding the fiber around the mandrel can be computer controlled.

[0023] Preferably, the fiber is wound around the mandrel so as to form a plurality of angles with respect to the axis of the mandrel.

[0024] In one embodiment, cutting the drape can lead to obtaining two identical preforms during the mandrel removal step for the simultaneous formation of two identical parts.

[0025] For process reasons, the preform may have a slightly different shape from the shape of the final part to be manufactured; the polymerization step in the mold will allow the desired final shape to be obtained.

[0026] For example, the material of the fibers wound around the mandrel can be chosen from: carbon, glass, Kevlar®, or a mixture of these.

[0027] In a particular embodiment, the polymerization step may include compressing the obtained preforms inside the mold. Alternatively, the polymerization step may be carried out differently using other known curing methods.

[0028] In one embodiment, the manufacturing process may include a plurality of winding steps, a plurality of cutting steps of the formed drapes, a plurality of mandrel removal steps of one or more preforms of said part to be manufactured from each cut drape, the manufacturing process further including a step of superimposing a plurality of the preforms obtained, said polymerization step being carried out on said superposition of preforms.

[0029] The invention also relates to a fitting made of composite material manufactured by implementing the manufacturing process as previously described. Brief description of the figures

[0030] Other purposes, advantages and features will become apparent from the following description, given for illustrative purposes only and made with reference to the accompanying drawings on which:

[0031] [Fig. 1] illustrates a first fitting to be manufactured,

[0032] [Fig.2] is a flowchart illustrating the steps of a manufacturing process for the first fitting illustrated in [Fig.1] according to an example of implementation of the invention,

[0033] [Fig.3A], [Fig.3B], [Fig.3C], [Fig.3D] and [Fig.3E] are schematic views in perspective of the first fitting illustrated in [Fig. 1] at different stages of its manufacture according to an example of the implementation of the manufacturing process of the invention,

[0034] [Fig.4] illustrates a second fitting to be manufactured,

[0035] [Fig.5] is a flowchart illustrating the steps of a manufacturing process for the second fitting illustrated in [Fig.4] according to an example of an implementation of the invention, and

[0036] [Fig.6A], [Fig.6B] and [Fig.6C] are schematic perspective views of the second fitting illustrated in [Fig.4] at different stages of its manufacture according to an example of implementation of the manufacturing process of the invention. Detailed description of the invention

[0037] Fig. 1 illustrates a first embodiment of a part to be manufactured 1. The part to be manufactured 1 is a T-shaped fitting used to connect two members in relative ball-joint motion, particularly intended for use in the field of aeronautics.

[0038] In what follows, the fitting according to the first embodiment is referred to as the “first fitting”.

[0039] The first fitting 1 includes a body 2. The body 2 includes a first part 2a, also called a sail, and a second part 2b taking the form of a base and including a fixing area for the first member to be connected.

[0040] The first part 2a has a through hole 3 formed near one upper end and intended to accommodate a ball joint. The first part 2a and the second part 2b are monolithic and extend respectively along essentially perpendicular geometric planes.

[0041] By essentially perpendicular, it is meant here that the angle formed between the two geometric planes is included in the interval 60° and 90°C.

[0042] The veil 2a here comprises first and second principal faces 4 and 5 that are opposed. The two principal faces 4, 5 are essentially parallel and diverge, moving away from each other in a lower part of the veil until they come into contact with the base.

[0043] The first fitting 1 shown comprises two complex-shaped portions, each formed by a boss. A first boss 6 extends at the junction of the first face 4 and the base 2b, and a second similar boss extends at the junction between the second face 5 and the base 2b. These bosses 6 give a wavy appearance to the body 2 and improve the rigidity of the first fitting 1.

[0044] A first example of implementation of the manufacturing process according to the invention, aimed at manufacturing the first fitting 1 in composite material formed from fiber-reinforced thermosetting material, is described with reference to the flowchart of [Fig.2],

[0045] As illustrated in [Fig. 3A], in a step 100, one or more fibers pre-impregnated with a thermosetting material are wound around a mandrel M to form, on the mandrel M, a drape 8 comprising a plurality of layers of wound fibers superimposed one on top of the other. Alternatively, the drape 8 may comprise a single layer of wound fibers.

[0046] In the illustrated example, a fiber in the form of a strip is wound around the mandrel M.

[0047] According to an alternative, several fibers can be wound simultaneously around the mandrel M.

[0048] Each fiber is initially pre-wound onto a head.

[0049] To perform the filament winding, the mandrel M is rotated around its axis X.

[0050] An initial winding substep of the pre-impregnated fibers around the mandrel M allows a first layer to be formed around the mandrel M. This first layer is formed with the rotation of the mandrel M around its X axis and the movement of the heads supporting the fibers parallel to the X axis.

[0051] Then, a succession of fiber winding sub-steps allows the drape 8 to be formed by superimposing layers one on top of the other around the mandrel M.

[0052] Advantageously, step 100 of winding the fibers around the mandrel M can be computer controlled and thus automated.

[0053] Preferably, each fiber is wound around the mandrel M so as to form a plurality of angles with respect to the X-axis of the mandrel M relative to the axis of the mandrel M in order to improve the final mechanical strength properties of the first fitting 1 manufactured. Preferably, the angle varies between 0 and 90°.

[0054] Advantageously, the angle varies along the mandrel and according to the layers of wound fibers.

[0055] For example, the fibers may be glass fibers, carbon fibers, Kevlar® fibers, or any other suitable material.

[0056] The thermosetting material is, for example, an epoxy resin.

[0057] With reference to figures 3A and 3B, in this first example of implementation, the mandrel M has an outer surface having first and second radially opposed grooves M1 and M2 intended to form first and second grooves 13 and 14 on the draping 8, and the first and second bosses 6 of the first fitting 1 to be manufactured.

[0058] In a step 200, the drape 8 obtained at the end of the filament winding step 100 is cut.

[0059] The number of cuts may vary depending on the number and shape of the preforms to be obtained for the manufacture of the desired part to be manufactured.

[0060] As illustrated in [Fig.3B], in the first illustrated embodiment, four cuts are made on the drape 8. Of course, the number of cuts can be different.

[0061] Next, in a step 300, the cut parts of the drape 8 are removed from the mandrel M.

[0062] The first and second ends 9 and 10 of the drape 8 are removed via two cuts made in a plane perpendicular to the axis of the mandrel M and are not used.

[0063] Two other cuts are made in two distinct planes parallel to the X axis of the mandrel M so as to obtain identical first and second central parts forming respectively first and second preforms 11 and 12 substantially identical.

[0064] Each of the first and second preforms 11 and 12 comprises one of the first and second grooves 13 and 14.

[0065] As can be seen in [Fig.3C], the first and second main opposite faces are each formed from one of the preforms thus obtained from the common draping 8 formed in step 100 of filament winding and positioned against each other.

[0066] With reference to [Fig.3D], the first and second preforms 11 and 12 are, in a step 500, positioned inside a mold 15 for polymerization.

[0067] In the illustrated example, compression is carried out simultaneously with polymerization step 500.

[0068] Optionally, a filler material 16, such as a bulk molding compound (BMC), may be added to the mold 15 before compression and polymerization. The bulk molding compound may include pieces of reinforcing fibers, such as glass fibers, carbon fibers, Kevlar® fibers, or any other suitable material.

[0069] In the illustrated example, filler material 16 is added to the first and second preforms 11 and 12 so as to form the base 2b of the first fitting 1.

[0070] The compression and heat treatment for polymerization of the thermosetting material are carried out under temperature and pressure conditions dependent on the thermosetting material.

[0071] The filling material is also heated during the compression and polymerization step 500 so that it bonds to the first and second preforms 11 and 12.

[0072] After compression and polymerization, the resulting part 17, shown in [Fig.3E], is extracted from the mold 15 in a step 600.

[0073] According to embodiments, the extraction step 600 can be followed by optional finishing steps 700 of the part 17, for example machining and / or polishing and / or surface treatment and application of a coating and / or insertion of a ball joint to obtain the first fitting 1 as illustrated in [Fig.1].

[0074] According to an alternative, the fibers wound around the mandrel M to form the drape 8 in step 100 can be dry fibers, i.e. fibers not impregnated with thermosetting material.

[0075] In this case, the thermosetting material that is not added in the winding step 100 is added to the first and second preforms 11 and 12 in a subsequent step. Preferably, the thermosetting material is injected into the mold 15 during the polymerization step 500.

[0076] Figure 4 illustrates a second embodiment of a part to be manufactured. The part to be manufactured is a fitting, known as a trunk corner, used to join, reinforce and stiffen three planes together, and specifically intended for use in the field of aeronautics.

[0077] In what follows, the fitting according to the second embodiment is referred to as the “second fitting”.

[0078] The second fitting 18 comprises a body 19. The body 19 comprises a first part 19a, a second part 19b and a third part 19c monoblocs and extend respectively along different geometric planes.

[0079] The first and second parts 19a and 19b form two wings whose junction forms a folding line 20 and extending in two essentially perpendicular planes.

[0080] The third part 19c extends along a plane essentially perpendicular to the plane of the first part 19a and essentially perpendicular to the plane of the second part 19b, and extends from a first end of the first part 19a to a first end of the second part 19b.

[0081] By essentially perpendicular, it is meant here that the angle formed between the geometric planes considered two by two is included in the interval 60° and 90°C.

[0082] The outer face of each of the first part 19a, second part 19b and third part 19c forms a coupling zone with one of the three planes of an assembly on which the second fitting 18 is intended to be fixed.

[0083] A second example of implementation of the manufacturing process according to the invention, aimed at the simultaneous manufacture of two second fittings 18 in composite material formed in fiber-reinforced thermosetting material is described with reference to the flowchart of [Fig.5].

[0084] As illustrated in [Fig.6A], in a step 110, one or more pre-impregnated fibers of a thermosetting material are wound around a mandrel M to form, on the mandrel M, a drape 21 comprising a plurality of layers of wound fibers superimposed on one another.

[0085] In the illustrated example, a fiber in the form of a strip is wound around the mandrel M.

[0086] According to an alternative, several fibers can be wound simultaneously around the mandrel M.

[0087] Each fiber is initially pre-wound onto a head.

[0088] To achieve filament winding, the mandrel M is rotated around its axis X.

[0089] An initial winding substep of the pre-impregnated fibers around the mandrel M allows a first layer to be formed around the mandrel M. This first layer is formed with the rotation of the mandrel M around its X axis and the displacement of the fibers parallel to the X axis.

[0090] Then, a succession of fiber winding sub-steps allows the drape 21 to be formed by superimposing layers one on top of the other around the mandrel M.

[0091] Advantageously, step 110 of winding the fibers around the mandrel M can be computer controlled and thus automated.

[0092] Preferably, each fiber is wound around the mandrel M so as to advantageously form a plurality of angles with respect to the X-axis of the mandrel M relative to the axis of the mandrel M in order to improve the final mechanical strength properties of the second fitting 18 manufactured. Preferably, the angle varies between 0 and 90°.

[0093] For example, for the same layer of fibers, the angle formed with respect to the X axis of the mandrel M can be substantially constant to plus or minus 5°, and for each new layer the angle formed with respect to the X axis of the mandrel M for this new layer can be different from the angle of the previous layer while being substantially constant to plus or minus 5° during the formation of this new layer.

[0094] For example, the fibers may be glass fibers, carbon fibers, Kevlar® fibers, or any other suitable material.

[0095] With reference to figures 6A and 6B, in this second example of implementation, the mandrel M has first and second radially opposed angular portions M3 and M4, which extend axially between the two ends of the mandrel M, and each intended to form a bending line of one of the two second fittings 18 to be manufactured.

[0096] In a step 210, the drape 21 obtained at the end of the filament winding step 110 is cut.

[0097] As illustrated in [Fig.6B], in the second embodiment shown, a single cut is made on the drape 21. Of course, the number of cuts can be different.

[0098] Next, in a step 310, the cut parts of the drape 21 are removed from the mandrel M.

[0099] The cutting is carried out in an oblique plane relative to the X axis of the mandrel M so as to obtain first and second preforms 22 and 23. The first and second preforms 22 and 23 are substantially identical and allow the obtaining of two identical second fittings 18.

[0100] Each of the first and second preforms 22 and 23, shown in [Fig.6C], includes one of the bend lines 20 of each of the two second fittings 18 to be manufactured.

[0101] The first and second preforms 22 and 23 obtained from the common draping 21 are, in a step 510, positioned inside a mold, not illustrated, for compression and polymerization.

[0102] The compression step 510 and the polymerization of each of the first and second preforms 22 and 23 is carried out separately and each of the first and second preforms 22 and 23 is positioned in a clean mold.

[0103] Optionally, a filler material, such as a bulk molding mix, may be added to the mold before compression and polymerization. The bulk molding mix may include pieces of reinforcing fibers, such as glass fibers, carbon fibers, Kevlar® fibers, or any other suitable material.

[0104] In the illustrated example, filler material is added to each of the first and second preforms 22 and 23 so as to reinforce the third part 19c of the second fittings 18.

[0105] The compression and heat treatment for polymerization of the thermosetting material are carried out under temperature and pressure conditions dependent on the thermosetting material.

[0106] The filling material is also heated during the compression and polymerization step 510 so that it bonds to the first and second preforms 22 and 23.

[0107] After compression and polymerization, each of the second ferrule 18 obtained is extracted from its mold in a step 610.

[0108] According to embodiments, the extraction step 610 can be followed by optional finishing steps 710 of the second fitting 18, for example machining and / or polishing and / or surface treatment and application of a coating.

[0109] According to an alternative, the fibers wound around the mandrel M to form the drape 21 in step 110 can be dry fibers, i.e. fibers not impregnated with thermosetting material.

[0110] In this case, the thermosetting material, which is not added in the winding step 100, is added to the first and second preforms 22 and 23 in a subsequent step. Preferably, the thermosetting material is injected into the mold before the polymerization step 510.

[0111] In another embodiment, the manufacturing process may comprise a plurality of winding steps 100, 110, each comprising winding one or more fibers pre-impregnated with a thermosetting material around the mandrel M. The drape 8, 21 formed at the end of each winding step is cut and removed from the mandrel M to obtain several preforms. Alternatively, the plurality of winding steps 100, 110 may be carried out on several separate mandrels.

[0112] The manufacturing process also includes a step of layering several of the preforms obtained after different winding steps. The polymerization step 500, 510 is thus carried out on the layered preforms obtained, inside the mold 15.

[0113] The first and second fittings 1,18 obtained according to the first and second modes of implementation are only possible examples of part to be manufactured according to the manufacturing process according to the invention, and other forms or configurations are possible without going out of the scope of the invention.

Claims

Demands

1. A method for manufacturing at least one part (1; 18) comprising at least locally a rounded shape and / or an angle and formed from fiber-reinforced thermosetting material, characterized in that it comprises the following successive steps: - at least one step (100; 110) of winding at least one fiber pre-impregnated with a thermosetting material, or at least one fiber not impregnated with a thermosetting material, around a mandrel (M) to form on the mandrel a drape (8; 21) comprising one layer of wound fibers or several layers of wound and superimposed fibers, - at least one step (200; 210) of cutting the drape (8; 21) formed, - at least one step (300; 310) of removing one or more preforms (11, 12; 22, 23) of said part to be manufactured (1; 18) from the drape (8; 21) cut, - optionally a step (400; 410) of adding thermosetting material to the preform (11, 12;22, 23) when the fiber wound around the mandrel (M) is a fiber not impregnated with a thermosetting material, - a step (500; 510) of polymerization inside a mold (15) of at least one of the preforms (11, 12; 22, 23) obtained, and - a step (600; 610) of extraction from the mold (15) of the part obtained (1; 18).;

2. A manufacturing method according to claim 1, wherein a filler material (16) is added to the mold (15) before the compression and polymerization step.

3. A manufacturing method according to claim 1 or 2, wherein the step (100; 110) of winding the fiber around the mandrel (M) is computer-controlled.

4. A manufacturing method according to any one of the preceding claims, wherein the fiber is wound around the mandrel (M) so as to form a plurality of angles with respect to the axis (X) of the mandrel (M).

5. A manufacturing method according to any one of the preceding claims, wherein the step (310) of cutting the drape (21) leads to obtaining two identical preforms (22, 23) during the step (300; 310) of removing the mandrel (M).

6. A manufacturing method according to any one of the preceding claims, wherein the material of the fibers wound around the mandrel (M) is selected from: carbon, glass, Kevlar®, or a mixture thereof.

7. A manufacturing process according to any one of the preceding claims, wherein the polymerization step (500; 510) includes a compression of the preforms (11, 12; 22, 23) obtained inside the mold (15).

8. A manufacturing process according to any one of the preceding claims, comprising a plurality of winding steps (100; 110), a plurality of cutting steps (200; 210) of the formed drapes (8; 21), a plurality of mandrel (M) removal steps (300; 310) of one or more preforms (11, 12; 22, 23) of said part to be manufactured (1; 18) from each cut drape (8; 21), the manufacturing process further comprising a superposition step of a plurality of the obtained preforms, said polymerization step (500; 510) being carried out on said superposition of preforms (11, 12; 22, 23).

9. Fitting made of composite material, characterized in that it is manufactured by implementing the manufacturing process according to any one of the preceding claims.

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