Manufacturing process for a part made of composite material

Abstract

[Title] Method for manufacturing a part of composite material. A method for manufacturing a part of composite material comprising a fiber-reinforced thermoplastic or thermosetting matrix, characterized in that it comprises the following successive steps: a) winding or depositing pre-impregnated fibers to form a preform (P) around a mandrel (M) comprising a thermoplastic or thermosetting material, said fibers being pre-impregnated with a thermoplastic or thermosetting matrix, b) winding a heat-shrinkable film (F) around the preform (P), c) polymerization of the intermediate product obtained at the end of step b) at a polymerization temperature dependent on the composite material used, and d) removal of the heat-shrinkable film (F) from the intermediate product to obtain said one-piece composite material part comprising the mandrel (M).

Description

Title of the invention: Method for manufacturing a part from composite material. Technical field of the invention

[0001] The present invention relates, in general, to parts made of composite material, such as a connecting rod.

[0002] More specifically, the invention relates to a method for manufacturing a part made of composite material, in particular, comprising a thermoplastic or thermosetting matrix reinforced with fibers. Prior art

[0003] A conventional way of manufacturing a connecting rod from composite material is based on the manufacture of a preform using one or more tools, such as a metal mandrel and / or a mold.

[0004] Document FR 3 053 622 describes, for example, a method for manufacturing a connecting rod. The preform is produced by filament winding pre-impregnated fibers around the mandrel, then it is cut to be removed from the mandrel. The preform is then placed in a female mold to be shaped, and then tensioned using a bladder positioned inside the preform. The connecting rod is then obtained after a polymerization step.

[0005] The use of tooling such as a mandrel or mold requires one or more steps for its extraction. In particular, given the shape of the connecting rod, the mandrel becomes trapped inside the preform. The number and nature of the steps involved in using tooling make such a manufacturing process particularly complex and costly. Summary of the invention

[0006] The invention therefore aims to remedy these drawbacks and to offer a simple and inexpensive means of manufacturing a part in composite material, such as a connecting rod.

[0007] A method for manufacturing a part made of composite material comprising a thermoplastic or thermosetting matrix reinforced with fibers is therefore proposed.

[0008] Furthermore, the process comprises the following successive steps:

[0009] a) winding or laying of pre-impregnated fibers, to form a preform around a mandrel comprising a thermoplastic or thermosetting material, said fibers being pre-impregnated with a thermoplastic or thermosetting matrix,

[0010] b) winding a heat-shrinkable film around the preform,

[0011] c) polymerization of the intermediate product obtained at the end of step b) at a temp- polymerization temperature dependent on the composite material used, and

[0012] d) removal of the heat-shrink film from the intermediate product to obtain said part in one-piece composite material which includes the mandrel.

[0013] The part made of composite material is thus obtained by a simple manufacturing process, comprising a limited number of steps, and inexpensive, not involving the use of tooling which needs to be removed.

[0014] Indeed, the composite material part obtained is directly formed from the mandrel and the preform.

[0015] Advantageously, the pre-impregnated fibers can be impregnated with a thermoplastic or thermosetting matrix, such as an epoxy resin, comprising carbon and / or glass fibers.

[0016] Advantageously, the mandrel material can be a composite material comprising a fiber-reinforced thermoplastic or thermosetting matrix.

[0017] According to one feature, pressure can be applied inside the chuck during one or more of the steps a), b) and c).

[0018] In one embodiment, the chuck may comprise at least two independent parts assembled before step a).

[0019] For example, the mandrel may include first and second forked parts assembled respectively to the first and second ends of a main tubular part.

[0020] The manufacturing process may also include adding at least one reinforcement, such as a patch, before step a), on the mandrel, preferably in a mandrel housing.

[0021] Preferably, a notch, such as a fin, is provided on the mandrel to facilitate the placement of the reinforcement, such as a patch.

[0022] Advantageously, the mandrel material may include particles, such as fibers, possessing electrical conductivity and / or anti-corrosion properties.

[0023] Advantageously, the manufacturing process may include, prior to step a), at least partial manufacturing of the mandrel according to one or more of the following techniques: extrusion, extrusion blow molding, injection molding, injection blow molding, blow molding, rotomolding, thermoforming, 3D printing, pultrusion or filament winding.

[0024] The invention also relates to a connecting rod made of composite material, characterized in that it is manufactured by implementing the manufacturing process as described above. Brief description of the figures

[0025] Other purposes, advantages and features will become apparent from the following description, given for illustrative purposes only and with reference to the accompanying drawings on which:

[0026] [Fig-1] is a flowchart illustrating the steps of a manufacturing process for a a part made of composite material according to an example of an implementation of the invention,

[0027] [Fig.2] illustrates a connecting rod according to another embodiment of the invention,

[0028] [Fig.3a][Fig.3b] and [Fig.3c] are schematic longitudinal sectional views of a connecting rod at different stages of its manufacture according to an example of the implementation of the manufacturing process of the invention,

[0029] [Fig.4] is a schematic longitudinal cross-sectional view of a chuck according to another embodiment of the invention, and

[0030] [Fig.5] illustrates the application of patches during a manufacturing process of a connecting rod according to another example of implementation of the invention. Detailed description of the invention

[0031] With reference to [Fig.1], the invention relates to a method for manufacturing a part made of composite material.

[0032] In the example illustrated in [Fig.2], the composite material part manufactured according to an example of implementation of the manufacturing process according to the invention is a connecting rod 1. Alternatively, the process can be applied for the manufacture of other types of parts.

[0033] The connecting rod 1 shown comprises a main tubular portion 2 having first and second opposite ends 2a and 2b from which extend, respectively, first and second forked portions 3 and 4.

[0034] The first and second forked portions 3 and 4 are advantageously cleats, each intended to be fixed to a tenon.

[0035] Alternatively, the connecting rod 1 may comprise a single forked portion.

[0036] With reference to [Fig.3a], the manufacturing process according to the invention advantageously includes the provision of a mandrel M comprising a thermoplastic or thermosetting material.

[0037] The thermoplastic or thermosetting material of the mandrel M is, for example, a resin.

[0038] The material of the mandrel M can be a composite material comprising a thermoplastic or thermosetting matrix reinforced with fibers, for example glass and / or carbon fibers.

[0039] The chuck M advantageously comprises, at least partially, a general shape similar to the shape of the connecting rod 1 to be manufactured.

[0040] In the illustrated example, the chuck M comprises a tubular portion 5 comprising the first and second opposite ends 5a and 5b from which extend, respectively, the first and second forked portions 6 and 7.

[0041] Of course, the shape of the mandrel M can be adapted to the desired shape of the connecting rod 1. The mandrel M can, for example, comprise a single forked portion.

[0042] In a step a), and as shown in [Fig.3b], pre-impregnated fibers are then wound or deposited to form a preform P around the mandrel M.

[0043] Preferably, the preform P completely covers the outer surface of the mandrel M.

[0044] Pre-impregnated fibers are fibers pre-impregnated using a thermoplastic or thermosetting matrix, for example an epoxy resin.

[0045] The preform P can be formed by depositing pre-impregnated fibers in the form of a pre-impregnated sheet, known as "prepreg" in English, or in the form of a cut of a pre-impregnated sheet, known as "slit tape" in English.

[0046] According to another alternative, the preform P can be formed by winding a pre-impregnated fiber, known as "towpreg" in English.

[0047] With reference to [Fig.3c], the manufacturing process then includes, in a step b), the winding of a heat-shrinkable film F around the preform, in contact with the preform P.

[0048] Preferably, the heat-shrinkable film F completely covers the outer surface of the preform P.

[0049] Heat shrink film means a film capable of shrinking under the effect of heat.

[0050] In a subsequent step c), the thermoplastic or thermosetting matrix of the pre-impregnated fibers is polymerized.

[0051] For this purpose, the assembly or intermediate product obtained at the end of step b) and formed by the mandrel M, the preform P and the heat-shrinkable film F is placed in an oven, under pressure and temperature conditions adapted to the nature of the thermoplastic or thermosetting matrix of the pre-impregnated fibers to be polymerized.

[0052] The heat-shrinkable film F, which shrinks under the effect of the heat applied during polymerization, applies pressure to the preform P and compacts it against the mandrel M.

[0053] The heat-shrinkable film material F is advantageously adapted according to the nature of the thermoplastic or thermosetting matrix of the pre-impregnated fibers, and in particular adapted so as to withstand the polymerization temperature of the thermoplastic or thermosetting matrix of the pre-impregnated fibers.

[0054] Heat shrink film F is a plastic film, for example made of polyester.

[0055] After polymerization, the heat-shrinkable film F is removed in a step d), and the connecting rod 1 made of composite material is obtained.

[0056] The part made of composite material is thus obtained by a simple, fast manufacturing process without the need to remove any tooling.

[0057] The mandrel M made of thermoplastic or thermosetting material, reinforced or not with fibers, is an integral part of the connecting rod 1 obtained, which makes it possible to manufacture the preform P without it being necessary to remove the mandrel M. The connecting rod 1 made of composite material is formed from the mandrel M and the preform P which, after step c) of polymerization, form a single piece.

[0058] Advantageously, the manufacturing process according to the invention may include a step of applying pressure inside the mandrel M. The pressure may be applied during one or more of the steps a), b) and c). Such a pressure, for example between 3 and 6 bar, makes it possible to reinforce the compaction of the preform P.

[0059] Such pressure also makes it possible to optimize the tensioning of the preform P, preventing said preform P from being crushed or deformed under the effect of the tension due to the filament winding.

[0060] In one embodiment, the mandrel material M may comprise particles, such as fibers, possessing electrical conductivity properties and / or anti-corrosion properties.

[0061] For example, the mandrel M can be formed from a composite material comprising a thermoplastic or thermosetting matrix incorporating carbon or metallic fibers, for example copper fibers, for electrical conductivity or glass fibers for an anti-corrosion effect, in particular anti-galvanic corrosion.

[0062] According to one feature, the manufacturing process according to the invention may include, prior to step a), the at least partial manufacturing of the mandrel M.

[0063] The manufacture of the mandrel M can be carried out according to one or more of the following techniques: extrusion, extrusion blow molding, injection molding, injection blow molding, blow molding, rotomolding, thermoforming, 3D printing, pultrusion or filament winding.

[0064] By "at least partial" means the manufacture of a portion or part of the mandrel M or of the entire mandrel M by one of these techniques: extrusion, extrusion blow molding, injection molding, injection blow molding, blow molding, rotomolding, thermoforming, 3D printing, pultrusion or filament winding.

[0065] Preferably, the mandrel M made available for step a) has a shape close or similar to the shape of the connecting rod 1 to be manufactured in order to avoid the need to machine the part obtained to obtain the final shape of the connecting rod 1.

[0066] In the embodiment illustrated in [Fig.3a], the chuck M is a single piece.

[0067] Alternatively, the mandrel M can be formed by two or more independent parts assembled together.

[0068] In the example illustrated in [Fig. 4], the mandrel M comprises a tubular portion 8 having opposing first and second ends 8a and 8b. The mandrel M also comprises forked first and second portions 9 and 10 assembled, respectively, on the first and second ends 8a and 8b of the tubular portion 9.

[0069] Alternatively, the mandrel M can be formed from a single forked part assembled on the tubular portion 8.

[0070] Assembling several parts to form the mandrel M allows the use of several manufacturing techniques depending on the shape and nature of the material of each part of the mandrel M.

[0071] The assembly allows the material of each part to be adapted according to its location on the mandrel M and the mechanical properties it requires. This reduces the manufacturing cost of the mandrel M as well as its overall weight.

[0072] In addition, the assembly also makes it possible to directly manufacture complex parts, such as the forked parts 9 and 10, without the need to machine them.

[0073] Furthermore, a specific tubular part 8 can be assembled to various forked parts, and vice versa.

[0074] In the example illustrated in [Fig.4], given their complex shape, the two forked parts 9 and 10 can, for example, be manufactured by injection molding, while the tubular part 8 can, for example, be manufactured by extrusion, pultrusion or filament winding.

[0075] Preferably, the one-piece chuck M, as illustrated in [Fig.3a], is manufactured by blow molding, which is a simple, inexpensive technique and makes the manufacture of the chuck M easily industrializable.

[0076] The manufacturing process according to the invention may include, in one embodiment, the addition of at least one reinforcement, such as a patch, on the mandrel M.

[0077] Advantageously, one or more reinforcements can be added to various areas of the mandrel M, before the winding or deposition of the pre-impregnated fibers on the mandrel M, or on the preform P.

[0078] The position of the reinforcements on the mandrel M can be determined by the expected benefit. In particular, these local reinforcements can be deposited directly onto the mandrel M and / or onto the preform P as the preform P is wound onto the mandrel M. A mechanical reinforcement function can be obtained by alternating winding the preform P and depositing the reinforcement.

[0079] The reinforcements make it possible to strengthen locally, in particular mechanically, certain areas of the mandrel M which may require superior mechanical properties, such as higher compressive strength.

[0080] According to another example, a galvanic corrosion control function can be achieved by directly depositing reinforcements with anti-galvanic corrosion properties onto the mandrel M.

[0081] Preferably, the reinforcements are formed from a material identical to that of the preform P. A reinforcement can be formed by stacking such a material to form a patch.

[0082] The preform P can be positioned so as to overlap at least one end of the reinforcement.

[0083] Advantageously, the mandrel M can include one or more housing(s) intended to receive the reinforcements, so that the shape of the mandrel M used in step a) is advantageously suitable for forming complex areas and so that it can be functionalized without the need to provide for shaping and machining operations of the part obtained at the end of step d).

[0084] In the example illustrated in [Fig.5], first and second patches 11 and 12 are positioned, respectively, on the forked portions 3 and 4 of a one-piece mandrel M.

[0085] Preferably, and as shown in [Fig.5], first and second fins 13 and 14 are provided respectively on the forked portions 7 and 8 of the mandrel M, forming two housings for the placement of patches 11 and 12.

[0086] The placement of local reinforcements on the mandrel M before steps b) and c) makes it possible to manufacture complex portions of the mandrel M and to eliminate machining steps of the part after polymerization.

Claims

Claims

1. A method of manufacturing a part made of composite material comprising a fiber-reinforced thermoplastic or thermosetting matrix, characterized in that it comprises the following successive steps: a) winding or depositing pre-impregnated fibers, to form a preform (P) around a mandrel (M) comprising a thermoplastic or thermosetting material, said fibers being pre-impregnated with a thermoplastic or thermosetting matrix, b) winding a heat-shrinkable film (F) around the preform (P), c) polymerizing the intermediate product obtained at the end of step b) at a polymerization temperature dependent on the composite material used, and d) removing the heat-shrinkable film (F) from the intermediate product to obtain said part made of a single-piece composite material which comprises the mandrel (M).

2. A manufacturing method according to claim 1, wherein the pre-impregnated fibers are impregnated with a thermoplastic or thermosetting matrix, such as an epoxy resin, comprising carbon and / or glass fibers.

3. A manufacturing method according to claim 1 or 2, wherein the mandrel material (M) is a composite material comprising a fiber-reinforced thermoplastic or thermosetting matrix.

4. A manufacturing method according to any one of the preceding claims, wherein pressure is applied inside the mandrel (M) during one or more of steps a), b) and c).

5. Manufacturing method according to any one of the preceding claims, in which the mandrel (M) comprises at least two independent parts (8, 9, 10) assembled before step a).

6. A manufacturing method according to claim 5, wherein the mandrel comprises first and second forked parts (9, 10) assembled respectively to the first and second ends (8a, 8b) of a main tubular part (8).

7. Manufacturing method according to any one of the preceding claims, comprising adding at least one reinforcement (11, 12), such as a patch, before step a), on the mandrel (M), preferably in a housing of the mandrel (M).

8. A manufacturing method according to any one of the preceding claims, wherein the mandrel material (M) comprises particles, such as fibers, having electrical conduction properties and / or anti-corrosion properties.

9. Manufacturing method according to any one of the preceding claims, comprising, prior to step a), at least partial manufacturing of the mandrel (M) according to one or more of the following techniques: extrusion, extrusion blow molding, injection molding, injection blow molding, blow molding, rotational molding, thermoforming, 3D printing, pultrusion or filament winding.

10. 0 Connecting rod made of composite material, characterized in that it is manufactured by implementing the manufacturing method according to any one of the preceding claims.

Images