Method for producing part made of composite material

Abstract

A method for manufacturing a part made of a composite material comprising a thermoplastic or thermoset matrix reinforced with fibers, characterized in that it comprises the following successive steps: a) winding or depositing pre-impregnated fibers in order to form a preform (P) around a mandrel (M) comprising a thermoplastic or thermoset material, the invention relates to a method for producing a part made of a composite material, comprising the steps of: a) forming a preform (P), said fibres being pre-impregnated with a thermoplastic or thermoset matrix, b) winding a heat-shrinkable film (F) around the preform (P), c) polymerizing an 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, in order to obtain said part made of a composite material in one piece comprising a mandrel (M).

Description

Technical Field

[0001] The present invention generally relates to components, such as connecting rods, made from composite materials.

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

[0003] The conventional method of manufacturing connecting rods made of composite materials is based on the manufacture of a preform with the aid of one or more tools such as a metal mandrel and / or a mould.

[0004] For example, document FR 3 053 622 describes a method for manufacturing a connecting rod. A preform is produced by filament winding preimpregnated fibers around a mandrel before being cut to be removed from the mandrel. Next, the preform is placed in a female mold for shaping and then tensioned using a bladder placed inside the preform. A connecting rod is then obtained at the end of the polymerization step.

[0005] The use of tools such as mandrels or molds requires one or more steps to remove them. In particular, given the shape of the connecting rod, the mandrel is ultimately constrained within the preform. The number and nature of the steps generated by the use of tools makes this manufacturing method particularly difficult and expensive. Summary of the invention

[0006] The present invention therefore aims to overcome these drawbacks and to propose a simple and inexpensive means for manufacturing components made of composite materials, such as connecting rods.

[0007] The invention thus proposes a method for manufacturing a component made of a composite material comprising a thermoplastic or thermosetting matrix reinforced with fibers.

[0008] The method further comprises the following consecutive steps:

[0009] a) winding or depositing preimpregnated fibers, which are preimpregnated with a thermoplastic or thermosetting matrix, so as to form a preform around a mandrel comprising a thermoplastic or thermosetting material,

[0010] b) wrapping a heat shrink film around the preform,

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

[0012] d) Removing the heat shrink film from the intermediate product to obtain said component made in one piece of composite material including the mandrel.

[0013] Thus, a part made of composite material is obtained by a simple manufacturing method comprising a limited number of steps and being inexpensive, not involving the use of tools that need to be removed.

[0014] In particular, the component made of composite material obtained is formed directly from the mandrel and the preform.

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

[0016] Advantageously, the material of the mandrel may be a composite material comprising a thermoplastic or thermosetting matrix reinforced with fibres.

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

[0018] In an embodiment, the mandrel may comprise at least two separate parts that are assembled together prior to step a).

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

[0020] The manufacturing method may further comprise, before step a), adding at least one reinforcement element, such as a lining plate, onto the mandrel, preferably in the shell of the mandrel.

[0021] Preferably, recesses, such as wings, are formed in the mandrel to make it easier to place reinforcements, such as lining plates, into place.

[0022] Advantageously, the material of the mandrel may comprise particles, such as fibers, having electrical conductivity and / or corrosion resistance.

[0023] Advantageously, the manufacturing method may comprise, prior to step a), at least partially manufacturing the mandrel using 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.

[0024] The present invention also relates to a connecting rod made of a composite material, characterized in that it is produced by implementing the above-mentioned manufacturing method. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Further objects, advantages and features will become apparent from the description set forth below, which is provided purely by way of illustration and with reference to the accompanying drawings, in which:

[0026] Figure 1 is a flow chart showing the steps of a method for manufacturing a component made of a composite material according to an exemplary embodiment of the present invention,

[0027] Figure 2 FIG. 2 shows a connecting rod according to another embodiment of the present invention.

[0028] Figure 3a , Figure 3b and Figure 3c is a schematic longitudinal cross-sectional view of a connecting rod according to an exemplary embodiment of a manufacturing method of the present invention in various steps of its manufacturing,

[0029] Figure 4 is a schematic longitudinal cross-sectional view of a mandrel according to another embodiment of the present invention, and

[0030] Figure 5 A lining plate is shown being put into place during a method of manufacturing a connecting rod according to another exemplary embodiment of the present invention. DETAILED DESCRIPTION

[0031] refer to Figure 1 , the present invention relates to a method for manufacturing a component made of composite material.

[0032] exist Figure 2 In the example shown, the component made of composite material produced according to the exemplary embodiment of the manufacturing method according to the invention is a connecting rod 1. Alternatively, the method can be applied to the manufacture of other types of components.

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

[0034] The first and second fork-shaped portions 3 and 4 are advantageously yokes, each intended to be attached to a tenon.

[0035] Alternatively, the connecting rod 1 may have a single fork-shaped portion.

[0036] Reference Figure 3a , the manufacturing method according to the invention advantageously comprises providing a mandrel M comprising a thermoplastic or thermosetting material.

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

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

[0039] The mandrel M advantageously has, at least partially, a shape substantially similar to that of the connecting rod 1 to be produced.

[0040] In the example shown, the mandrel M comprises a tubular portion 5 having first and second opposite ends 5a and 5b from which extend first and second fork-shaped portions 6 and 7, respectively.

[0041] Naturally, the shape of the spindle M can be adapted to the desired shape of the connecting rod 1. The spindle M can, for example, have a single fork-shaped portion.

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

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

[0044] Preimpregnated fibers are fibers that are pre-impregnated with a thermoplastic or thermosetting matrix such as epoxy resin.

[0045] The preform P may be formed by depositing preimpregnated fibers in the form of preimpregnated sheets, called "prepregs," or in the form of cut preimpregnated sheets, called "slit tapes."

[0046] According to another alternative, the preform P may be formed by winding preimpregnated fibers, known as “tow prepreg”.

[0047] Reference Figure 3c The manufacturing method then comprises, in a step b), winding a heat shrink film F around the preform, in contact with the preform P.

[0048] Preferably, the heat shrink film F covers the entire outer surface of the preform P.

[0049] Heat shrink film refers to a film that shrinks under the action of heat.

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

[0051] To this end, the assembly or intermediate product consisting of mandrel M, preform P and heat shrink film F obtained at the end of step b) is placed in an oven whose pressure and temperature conditions are adapted to the nature of the thermoplastic or thermosetting matrix of the preimpregnated fibers to be polymerized.

[0052] The heat shrinkable film F, which shrinks under the effect of the heat applied during the polymerization process, generates pressure on the preform P and presses it onto the mandrel M.

[0053] The material of the heat shrinkable film F is advantageously adjusted to the properties of the thermoplastic or thermosetting matrix of the preimpregnated fibers, in particular in such a way as to withstand the polymerization temperature of the thermoplastic or thermosetting matrix of the preimpregnated fibers.

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

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

[0056] Thus, a component made of composite material is obtained by a manufacturing method that is simple, rapid and does not involve any tooling that has to be removed.

[0057] Mandrel M made of thermoplastic or thermosetting material, whether reinforced with fibres or not, forms an integral part of the connecting rod 1 obtained, which makes it possible to produce the preform P without having to remove the mandrel M. The connecting rod 1 made of composite material is composed of the mandrel M and the preform P, which form a single-piece part after step c) of polymerisation.

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

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

[0060] In one embodiment, the material of the mandrel M may include particles having electrical conductivity and / or corrosion resistance, such as fibers.

[0061] For example, the mandrel M may be made of a composite material comprising a thermoplastic or thermosetting matrix incorporating carbon or metal fibers, such as copper fibers, for electrical conductivity, or glass fibers for resistance to corrosion, particularly the effects of galvanic corrosion.

[0062] According to one characteristic, the manufacturing method according to the invention may comprise at least partial manufacturing of the mandrel M before step a).

[0063] The mandrel M may be manufactured using 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.

[0064] By "at least partially" it is meant that a portion of the mandrel M or the entire mandrel M is manufactured by one of these techniques: extrusion, extrusion blow molding, injection molding, injection blow molding, blow molding, rotational molding, thermoforming, 3D printing, pultrusion or filament winding.

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

[0066] exist Figure 3a In the embodiment shown, the mandrel M is integral.

[0067] Alternatively, the mandrel M may be constructed from two or more separate parts that are assembled together.

[0068] exist Figure 4 In the example shown, the mandrel M comprises a tubular portion 8 having first and second opposite ends 8a and 8b. The mandrel M also comprises first and second fork-shaped portions 9 and 10, which are assembled to the first and second ends 8a and 8b of the tubular portion 8, respectively.

[0069] As an alternative, the mandrel M may consist of a single fork-shaped portion assembled to the tubular portion 8.

[0070] The assembly of multiple parts to form the mandrel M allows a variety of manufacturing techniques to be used depending on the shape and material properties of each part of the mandrel M.

[0071] The assembly makes it possible to adapt the material properties of each part according to its position on the mandrel M and the mechanical characteristics it must have. This makes it possible to reduce the costs of manufacturing the mandrel M and its overall weight.

[0072] Furthermore, assembly also allows complex parts, such as the fork-shaped parts 9 and 10 , to be manufactured directly without the need to machine them.

[0073] Furthermore, a specific tubular portion 8 can be assembled to each fork-shaped portion and vice versa.

[0074] exist Figure 4 In the example shown, the two fork-shaped portions 9 and 10 may be produced, for example, by injection molding, whereas the tubular portion 8 may be produced, for example, by extrusion, pultrusion or filament winding, in view of their complex shape.

[0075] Preferably, if Figure 3a As shown, the one-piece mandrel M is produced by blow molding, which is a simple and inexpensive technique and allows the mandrel M to be easily manufactured on an industrial scale.

[0076] In one embodiment, the manufacturing method according to the invention may comprise adding at least one reinforcement member, such as a lining plate, to the mandrel M.

[0077] Advantageously, before the preimpregnated fibers are wound or deposited on the mandrel M or on the preform P, one or more reinforcements may be added to different regions of the mandrel M.

[0078] The position of the reinforcements on the mandrel M may be determined by the desired advantages. In particular, these local reinforcements may be deposited directly on the mandrel M and / or on the preform P when the preform P is wound on the mandrel M. The function of mechanical reinforcement may be achieved by alternating winding of the preform P and deposition of reinforcements.

[0079] The reinforcement elements allow local reinforcement, in particular mechanical reinforcement, of certain areas of the mandrel M which may require superior mechanical properties, such as a higher compressive strength.

[0080] According to another example, by depositing a reinforcing member having galvanic corrosion resistance directly on the mandrel M, the control function of galvanic corrosion can be obtained.

[0081] Preferably, the reinforcement is made of the same material as that constituting the preform P. The reinforcement may be constituted by a stack of such materials, forming a lining panel.

[0082] The preform P may be positioned to overlap at least one end of the reinforcement member.

[0083] Advantageously, the mandrel M may comprise one or more shells intended to receive 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 having to shape and machine the part obtained at the end of step d).

[0084] exist Figure 5 In the example shown, the first and second lining plates 11 and 12 are located on the forked parts 3 and 4 of the mandrel M, respectively, which are made in one piece.

[0085] Preferably, if Figure 5 As shown, first and second wings 13 and 14 are formed respectively on the forked portions 7 and 8 of the mandrel M, forming two housings for placing the lining plates 11 and 12 in place.

[0086] Placing local reinforcements on the mandrel M before steps b) and c) makes it possible to produce complex parts of the mandrel M and to dispense with the step of machining the part after polymerization.

Claims

1. A method for producing a component made of a composite material comprising a thermoplastic or thermosetting matrix reinforced with fibers, characterized in that The method comprises the following consecutive steps: a) winding or depositing preimpregnated fibers, said fibers being preimpregnated with a thermoplastic or thermosetting matrix, so as to form a preform (P) around a mandrel (M) comprising a thermoplastic or thermosetting material, b) wrapping a heat shrink film (F) around the preform (P), c) polymerizing the intermediate product obtained at the end of step b) at a polymerization temperature depending on the composite material used, and d) Removing the heat shrink film (F) from the intermediate product to obtain said component made in one piece of composite material including the mandrel (M).

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

3. The manufacturing method according to claim 1 or 2, wherein: The material of the mandrel (M) is a composite material comprising a thermoplastic or thermosetting matrix reinforced with fibers.

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

5. The manufacturing method according to any one of the preceding claims, wherein: The mandrel (M) comprises at least two separate parts (8, 9, 10) which are assembled together prior to step a).

6. The manufacturing method according to claim 5, wherein: The mandrel comprises first and second fork-shaped portions (9, 10) respectively assembled to first and second ends (8a, 8b) of a main tubular portion (8).

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

8. A method of production according to any one of the preceding claims, wherein: The material of the mandrel (M) comprises particles, such as fibers, having electrical conductivity and / or corrosion resistance.

9. The manufacturing method according to any of the preceding claims comprises, before step a), at least partially manufacturing the mandrel (M) using 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 fiber winding.

10. A connecting rod made of a composite material, characterized in that: It is produced by carrying out the manufacturing method according to any one of the preceding claims.

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