Method for manufacturing a part from composite material

Abstract

A method for manufacturing a part from composite material comprising a thermoplastic or thermoset matrix reinforced with fibers, characterized in that it comprises the following successive steps: a) Winding or laying pre-impregnated fibers to form a preform (P) around a mandrel (M) comprising a thermoplastic or thermoset material, wherein the fibers are pre-impregnated with a thermoplastic or thermoset matrix, b) Wrapping a heat-shrinkable film (F) around the preform (P), c) Polymerizing the intermediate obtained at the end of step b) at a polymerization temperature that depends on the composite material used, and d) Removing the heat-shrinkable film (F) from the intermediate product to obtain the composite part in one piece, encompassing the mandrel (M).

Description

Technical field of the invention

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

[0002] In particular, the invention relates to a method for manufacturing a part from composite material, which in particular comprises a thermoplastic or thermoset matrix reinforced with fibers. State of the art

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

[0004] Document FR 3 053 622, for example, describes a method for manufacturing a connecting rod. The preform is produced by precision winding pre-impregnated fibers around the mandrel before being cut to remove it. The preform is then placed in a die to be shaped and subsequently tensioned with a bladder placed inside the preform. The connecting rod is then obtained at the end of a polymerization step.

[0005] The use of tools such as mandrels or molds requires one or more steps for their removal. In particular, due to the shape of the connecting rod, the mandrel often remains stuck in the preform. The number and nature of the steps resulting from the use of such a tool make this manufacturing process especially difficult and expensive. Summary of the invention

[0006] The invention therefore aims to overcome these disadvantages and to propose a simple and cost-effective means of manufacturing a part from composite material, such as a connecting rod.

[0007] She therefore proposes a method for manufacturing a part from composite material comprising a fiber-reinforced thermoplastic or thermoset matrix.

[0008] The procedure further comprises the following successive steps: a) Winding or laying pre-impregnated fibers to form a preform around a mandrel comprising a thermoplastic or thermoset material, wherein the fibers are pre-impregnated with a thermoplastic or thermoset matrix, b) Wrapping a heat-shrinkable film around the preform, c) Polymerizing the intermediate obtained at the end of step b) at a polymerization temperature that depends on the composite material used, and d) Removing the heat-shrinkable film from the intermediate product to obtain the composite part in one piece that includes the mandrel.

[0009] The composite part is thus obtained through a manufacturing process that is simple, involves a limited number of steps and is cost-effective, without the need for tools that have to be removed.

[0010] To be precise, the resulting part is made of composite material and is formed directly from the mandrel and the preform.

[0011] 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.

[0012] Advantageously, the material of the mandrel can be a composite material comprising a thermoplastic or thermoset matrix reinforced with fibers.

[0013] According to one characteristic, pressure can be exerted inside the mandrel during one or more of steps a), b) and c).

[0014] In one embodiment, the mandrel may comprise at least two independent parts which are assembled prior to step a).

[0015] For example, the mandrel can comprise first and second forked parts, each of which is mounted to the first and second ends of a tubular main part.

[0016] The manufacturing process may further include the addition of at least one reinforcement, such as a patch, before step a) on the mandrel, preferably in a recess of the mandrel.

[0017] Preferably, a notch, like a wing, is formed on the mandrel to make it easier to put the reinforcement, like a patch, in place.

[0018] Advantageously, the mandrel material can include particles, such as fibers, that have electrically conductive and / or anti-corrosion properties.

[0019] Advantageously, the manufacturing process prior to step a) may include at least the partial manufacture of 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 precision winding.

[0020] The invention also relates to a connecting rod made of composite material, characterized in that it is manufactured by applying the manufacturing process described above. Brief description of the characters

[0021] Further objectives, advantages and features will become clear from the description below, which is provided for illustrative purposes only and with reference to the accompanying drawings, in which: [ Fig. 1] is a flowchart showing the steps of a method for manufacturing a part from composite material according to an exemplary embodiment of the invention, [ Fig. 2] a connecting rod according to another embodiment of the invention, [ Fig. 3a] [ Fig. 3b] and [ Fig. 3c] Schematic views in longitudinal section of a connecting rod in various steps of its manufacture according to an exemplary embodiment of the manufacturing process of the invention are, [ Fig. 4] a schematic view of a mandrel in longitudinal section according to another embodiment of the invention, and [ Fig. 5] shows patches that are applied during a method for manufacturing a connecting rod according to another exemplary embodiment of the invention. Detailed description of the invention

[0022] With reference to Fig. 1 The invention relates to a method for manufacturing a part from composite material.

[0023] In the Fig. The example shown in Figure 2 is a composite part, a connecting rod 1, which was produced according to an exemplary embodiment of the manufacturing process according to the invention. Alternatively, the process can be applied to the production of other types of parts.

[0024] The connecting rod 1 shown comprises a tubular main section 2 with first and second opposite ends 2a and 2b, from which first and second forked sections 3 and 4 extend.

[0025] The first and second forked sections 3 and 4 are advantageously forks, each intended to be attached to a pin.

[0026] Alternatively, the connecting rod 1 can have a single forked section.

[0027] With reference to Fig. 3a The manufacturing process according to the invention advantageously comprises providing a mandrel M comprising a thermoplastic or thermosetting material.

[0028] The thermoplastic or thermosetting material of mandrel M is, for example, a resin.

[0029] The material of the mandrel M can be a composite material comprising a thermoplastic or thermoset matrix reinforced with fibers, for example glass and / or carbon fibers.

[0030] The mandrel M advantageously has at least a partially similar shape to the shape of the connecting rod 1 to be manufactured.

[0031] In the example shown, the mandrel M comprises a tubular section 5 with first and second opposite ends 5a and 5b, from which first and second forked sections 6 and 7 extend.

[0032] Naturally, the shape of the mandrel M can be adapted to the desired shape of the connecting rod 1. The mandrel M can, for example, have a single forked section.

[0033] In step a) and as in Fig. As shown in 3b, pre-impregnated fibers are then wound or laid down to form a preform P around the mandrel M.

[0034] Preferably, the preform P covers the entire outer surface of the mandrel M.

[0035] Pre-impregnated fibers are fibers that have been pre-impregnated using a thermoplastic or thermosetting matrix, for example an epoxy resin.

[0036] The preform P can be formed by depositing pre-impregnated fibers in the form of a pre-impregnated sheet, referred to as a "prepreg", or in the form of a cut pre-impregnated sheet, referred to as a "slit tape".

[0037] According to another alternative, the preform P can be formed by winding a pre-impregnated fiber called a "towpreg".

[0038] With reference to Fig. 3c the manufacturing process then includes in one step b) the wrapping of a heat-shrinkable film F around the preform, in contact with the preform P.

[0039] Preferably, the heat-shrinkable film F covers the entire outer surface of the preform P.

[0040] A heat-shrinkable film is a film that can shrink under the influence of heat.

[0041] In a subsequent step c), the thermoplastic or thermoset matrix of the pre-impregnated fibers is polymerized.

[0042] For this purpose, the arrangement or intermediate product obtained at the end of step b) and produced from 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 type of thermoplastic or thermoset matrix of the pre-impregnated fibers to be polymerized.

[0043] The heat-shrinkable film F, which shrinks under the influence of the heat applied during polymerization, creates pressure on the preform P and presses it against the mandrel M.

[0044] The material of the heat-shrinkable film F is advantageously adapted depending on the type of thermoplastic or thermoset matrix of the pre-impregnated fibers and in particular adapted so that it can withstand the polymerization temperature of the thermoplastic or thermoset matrix of the pre-impregnated fibers.

[0045] The heat-shrinkable film F is a plastic film, for example made of polyester.

[0046] After polymerization, the heat-shrinkable film F is removed in step d) and the connecting rod 1 made of composite material is obtained.

[0047] The composite part is thus obtained through a manufacturing process that is simple and fast and does not require the removal of any tools.

[0048] The mandrel M, made of thermoplastic or thermoset material, whether fiber-reinforced or not, forms an integral part of the resulting connecting rod 1, making it possible to produce the preform P without removing the mandrel M. The composite connecting rod 1 consists of the mandrel M and the preform P, which form a single piece after polymerization step c).

[0049] Advantageously, the manufacturing process according to the invention can include a step of applying pressure within the mandrel M. The pressure can be applied during one or more of steps a), b), and c). Such a pressure, for example between 3 and 6 bar, makes it possible to increase the compaction of the preform P.

[0050] Such pressure also makes it possible to optimize the tension of the preform P, thus preventing the preform P from being squeezed or deformed under the effect of the tension due to precision winding.

[0051] In one embodiment, the material of the mandrel M can comprise particles, such as fibers, that have electrical conductivity properties and / or corrosion protection properties.

[0052] For example, the mandrel M can be made of a composite material comprising a thermoplastic or thermoset matrix containing carbon or metal fibers, for example copper fibers, for electrical conductivity or glass fibers for corrosion protection, especially against galvanic corrosion.

[0053] According to one feature, the manufacturing process according to the invention can, prior to step a), include at least the partial manufacture of the mandrel M.

[0054] The mandrel M can 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 precision winding.

[0055] “At least partially” means the production of a section or part of the mandrel M or the entire mandrel M by one of these processes: extrusion, extrusion blow molding, injection molding, injection blow molding, blow molding, rotational molding, thermoforming, 3D printing, pultrusion or precision winding.

[0056] Preferably, the mandrel M provided for step a) has a shape that closely resembles or is similar to the shape of the connecting rod 1 to be produced, in order to avoid having to machine the resulting part to obtain the final shape of the connecting rod 1.

[0057] In the Fig. In the embodiment shown in 3a, the mandrel M is a single piece.

[0058] Alternatively, the mandrel M can be manufactured from two or more independent parts that are assembled.

[0059] In the Fig. In the example shown in Figure 4, the mandrel M comprises a tubular part 8 having a first and a second end 8a and 8b, which are opposite each other. The mandrel M also comprises a first and a second forked part 9 and 10, respectively, which are attached to the first and second ends 8a and 8b of the tubular part 8.

[0060] Alternatively, the mandrel M can be manufactured from a single forked part attached to the tubular section 8.

[0061] The arrangement of several parts to form the mandrel M allows the use of several manufacturing techniques depending on the shape and type of material of each part of the mandrel M.

[0062] This arrangement allows the type of material for each part to be adapted according to its position on the mandrel M and the mechanical properties it must possess. This reduces the manufacturing costs of the mandrel M and its overall weight.

[0063] Furthermore, the arrangement also allows for the direct production of complex parts, such as the forked parts 9 and 10, without the need for machining.

[0064] Furthermore, a special tubular part 8 can be attached to various forked parts and vice versa.

[0065] In the Fig. In the example shown in Figure 4, the two forked parts 9 and 10 can be manufactured, for example, by injection molding due to their complex shape, while the tubular part 8 can be manufactured, for example, by extrusion, pultrusion or precision winding.

[0066] Preferably the mandrel M is manufactured in one piece, as in Fig. 3a shown, produced by blow molding, which is a simple and cost-effective process and enables the easy production of the mandrel M on an industrial scale.

[0067] The manufacturing process according to the invention can, in one embodiment, include adding at least one reinforcement, such as a patch, to the mandrel M.

[0068] Advantageously, one or more reinforcements can be added to different areas of the mandrel M before the pre-impregnated fibers are wound or applied to the mandrel M or to the preform P.

[0069] The position of the reinforcements on the mandrel M can be determined by the desired advantage. In particular, these local reinforcements can be placed directly on the mandrel M and / or on the preform P while the preform P is wound onto the mandrel M. A mechanical reinforcement function can be achieved by alternately winding the preform P and placing the reinforcement.

[0070] The reinforcements enable, in particular mechanically, local strengthening of certain areas of the mandrel M, which may need to have better mechanical properties, such as higher compressive strength.

[0071] According to another example, a function for controlling galvanic corrosion can be obtained by directly depositing reinforcements with antigalvanic corrosion properties on the mandrel M.

[0072] Preferably, the reinforcements are made of a material identical to that of the preform P. A reinforcement can be made from a stack of such material to form a patch.

[0073] The preform P can be positioned so that it overlaps at least one end of the reinforcement.

[0074] Advantageously, the mandrel M can include one or more receptacles designed 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 shape and machine the part obtained at the end of step d).

[0075] In the Fig. In the example shown in Figure 5, the first and second patches 11 and 12 are positioned on the forked sections 3 and 4 respectively of a one-piece manufactured mandrel M.

[0076] Preferably and as in Fig. As shown in Figure 5, the first and second wings 13 and 14 are formed on the forked sections 7 and 8 of the mandrel M, respectively, thereby creating two receptacles for attaching the patches 11 and 12.

[0077] By applying local reinforcements to the mandrel M before steps b) and c), complex sections of the mandrel M can be produced and the machining steps of the part after polymerization can be eliminated. QUOTES INCLUDED IN THE DESCRIPTION

[0000] This list of documents cited by the applicant was automatically generated and is included solely for the reader's convenience. The list is not part of the German patent or utility model application. The DPMA accepts no liability for any errors or omissions. Cited patent literature

[0000] FR 3 053 622

[0004]

Claims

[1] Process for producing a part from a composite material comprising a fibre-reinforced thermoplastic or thermosetting matrix, characterized by that it includes the following sequential steps: a) winding or depositing pre-impregnated fibres to form a preform (P) around a mandrel (M) comprising thermoplastic or thermosetting material, the fibres being pre-impregnated with a thermoplastic or thermosetting matrix, b) wrapping a heat-shrinkable film (F) around the preform (P), c) polymerising the intermediate obtained at the end of step b) at a polymerisation temperature which depends on the composite material used, and d) removing the heat-shrinkable film (F) from the intermediate product to obtain the composite material part in one piece comprising the mandrel (M). [2] Manufacturing process 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] 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] Manufacturing method according to one of the preceding claims, wherein a pressure is applied within the mandrel (M) during one or more of steps a), b) and c). [5] Manufacturing method according to one of the preceding claims, wherein the mandrel (M) comprises at least two independent parts (8, 9, 10) which are assembled before step a). [6] A manufacturing method according to claim 5, wherein the mandrel comprises first and second forked parts (9, 10) arranged respectively at the first and second ends (8a, 8b) of a tubular main part (8). [7] Manufacturing method according to one of the preceding claims, comprising adding at least one reinforcement (11, 12), such as a patch, before step a) to the mandrel (M), preferably in a receptacle of the mandrel (M). [8] Manufacturing method according to one of the preceding claims, wherein the material of the mandrel (M) comprises particles, such as fibers, having electrical conductivity properties and / or anti-corrosion properties. [9] Manufacturing method according to one of the preceding claims, comprising, 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 precision winding. [10] Composite connecting rod, characterized by that it is produced by applying the manufacturing method according to one of the preceding claims.

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