METHOD OF MANUFACTURING A PART MADE OF COMPOSITE MATERIAL

Abstract

A method for manufacturing a part made of composite material including a thermoplastic or thermosetting matrix reinforced with fibers includes the following steps: winding or depositing pre-impregnated fibers about a mandrel so as to form a preform, the fibers being formed of a thermoplastic or thermosetting material and being pre-impregnated with a thermoplastic or thermosetting matrix; winding a heat-shrinkable film around the preform; polymerizing the intermediate product obtained by winding the film about the preform at a polymerization temperature depending on the composite material used; and removing the heat-shrinkable film from the intermediate product so as to obtain a one-piece part made of composite material and including the mandrel.

Claims

1. A method for manufacturing a part formed of composite material including a thermoplastic or thermosetting matrix reinforced with fibers, the method comprising the steps of: winding or depositing pre-impregnated fibers about a mandrel so as to form a preform, the pre-impregnated fibers being pre-impregnated with a thermoplastic matrix or a thermosetting matrix and the mandrel being formed of a thermoplastic material or a thermosetting material; winding a heat-shrinkable film around the preform; polymerizing an intermediate product including the preform and the heat-shrinkable film at a temperature of polymerization of the thermoplastic material or the thermosetting material of the preform; and removing the heat-shrinkable film from the intermediate product so as to obtain a one-piece part of composite material and including the mandrel.

2. The manufacturing method according to claim 1, wherein the pre-impregnated fibers include carbon fibers and/or glass fibers.

3. The manufacturing method according to claim 2, wherein the thermoplastic matrix or the thermosetting matrix of the pre-impregnated fibers is an epoxy resin.

4. The manufacturing method according to claim 1, wherein the mandrel is formed of a composite material including a thermoplastic matrix reinforced with fibers or a thermosetting matrix reinforced with fibers.

5. The manufacturing method according to claim 1, wherein a pressure is applied inside the mandrel during the step of winding or depositing pre-impregnated fibers about the mandrel, the step of winding a heat-shrinkable film around the preform and/or the step of polymerizing the intermediate product.

6. The manufacturing method according to claim 1, wherein the mandrel includes at least two separate parts assembled together before the step of winding or depositing the pre-impregnated fibers about the mandrel.

7. The manufacturing method according to claim 6, wherein the mandrel includes a main tubular part with a first end and a second end, a first forked part assembled to the first end of the main tubular part and a second forked part assembled to the second end of the main tubular part.

8. The manufacturing method according to claim 1, further comprising a step of adding at least one reinforcement on the mandrel before the step of winding or depositing pre-impregnated fibers around a mandrel.

9. The manufacturing method according to claim 8, wherein the at least one reinforcement is a patch and/or the reinforcement is added to a housing of the mandrel.

10. The manufacturing method according to claim 1, wherein the material of the mandrel includes particles having electrical conductivity properties and/or anti-corrosion properties.

11. The manufacturing method according to claim 1, further comprising a step of at least partially forming the mandrel before the step of winding the fibers about the mandrel by one or more of the following techniques: extrusion, extrusion blow molding, injection molding, injection blow molding, blow molding, rotational molding, thermoforming, 3D printing, pultrusion and filament winding.

12. A connecting rod formed of a composite material and produced by the manufacturing method according to claim 1.

Description

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

[0024] Further aims, advantages and features will become clear from the description set out below, which is provided purely by way of illustration and with reference to the attached drawings, in which:

[0025] FIG. 1 is a flow chart showing the steps of a method for manufacturing a part made of composite material according to an exemplary embodiment of the invention,

[0026] FIG. 2 shows a connecting rod according to another embodiment of the invention,

[0027] FIGS. 3a-3c are each a schematic view in longitudinal section of a connecting rod in various steps of its manufacture according to an exemplary embodiment of the manufacturing method of the invention;

[0028] FIG. 4 is a schematic view in longitudinal section of a mandrel according to another embodiment of the invention; and

[0029] FIG. 5 shows patches being put in place during a method for manufacturing a connecting rod according to another exemplary embodiment of the invention.

DETAILED DESCRIPTION OF THE INVENTION

[0030] With reference to FIG. 1, the invention relates to a method for manufacturing a part made of composite material.

[0031] In the example shown in FIG. 2, the part made of composite material produced according to an exemplary embodiment of the manufacturing method according to the invention is a connecting rod 1. Alternatively, the method may be applied to the manufacture of other types of parts.

[0032] The connecting rod 1 shown includes a main tubular portion 2 having a first end 2a and an opposing, second end 2b, a first forked portion 3 extending from the first end 2a and a second forked portion 4 extending from the second end 2b.

[0033] The first and second forked portions 3, 4, respectively, are preferably yokes, each forked portion 3, 4 being intended to be attached to a separate tenon (not shown). Alternatively, the connecting rod 1 may have only a single forked portion.

[0034] With reference to FIG. 3a, the manufacturing method according to the present invention advantageously comprises providing a mandrel M formed of a thermoplastic material or of a thermosetting material. The thermoplastic or thermosetting material of the mandrel M is, for example, a resin. The material of the mandrel M may be a composite material comprising a thermoplastic matrix reinforced with fibers or a thermosetting matrix reinforced with fibers. The fibers reinforcing the thermoplastic or thermosetting matrix may be, for example, glass fibers and/or carbon fibers.

[0035] The mandrel M advantageously has, at least partially, a shape generally similar to the shape of the connecting rod 1 to be produced. In the depicted example, the mandrel M includes a tubular portion 5 having a first end 5a, an opposing second end 5b, a first forked portion 6 extending from the first end 5a and a second forked portion 7 extending from the second end 5b.

[0036] The particular shape of the mandrel M may be adapted to a desired shape of the connecting rod 1. For example, the mandrel M may have only a single forked portion.

[0037] In a first or step a) of the manufacturing method, as shown in FIG. 3b, pre-impregnated fibers are wound or deposited so as to form a preform P around the mandrel M. Preferably, the preform P covers the entire outer surface of the mandrel M.

[0038] Preferably, the pre-impregnated fibers are fibers pre-impregnated using a thermoplastic matrix or a thermosetting matrix, for example an epoxy resin.

[0039] The preform P may be formed by deposition of pre-impregnated fibers in the form of a pre-impregnated sheet, known as a prepreg, or in the form of a cut pre-impregnated sheet, known as a slit tape. According to another alternative, the preform P may be formed by winding of a pre-impregnated fiber, known as a towpreg.

[0040] With reference to FIG. 3c, the manufacturing method then comprises, in a step b), winding a heat-shrinkable film F around the preform P, in contact with the preform P. Preferably, the heat-shrinkable film F covers the entire outer surface of the preform P.

[0041] As used herein, heat-shrinkable film means a film that can shrink under the effect of heat; in other words, a film that shrinks when heat is applied to the film.

[0042] In a subsequent step c), the thermoplastic matrix or the thermosetting matrix of the pre-impregnated fibers is polymerized.

[0043] To achieve polymerization, the assembly or intermediate product obtained at the end of step b), and formed or composed of 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.

[0044] The heat-shrinkable film F, which shrinks under the effect of the heat applied during polymerization, creates a pressure on the preform P and compacts it against the mandrel M.

[0045] The material of the heat-shrinkable film F is preferably adapted as a function of the nature of the thermoplastic matrix or the thermosetting matrix of the pre-impregnated fibers, and in particular is adapted in such a way as to withstand the temperature of polymerization of the thermoplastic or thermosetting matrix of the pre-impregnated fibers. 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 a step d), and the connecting rod 1 made of composite material is obtained.

[0047] The connecting rod 1 or other part made of composite material is thus obtained by a manufacturing method that is simple and quick and does not involve any tools or components that have to be removed.

[0048] The mandrel M made of thermoplastic material or thermosetting material, whether or not reinforced with fibers, forms an integral part of the connecting rod 1 obtained by the present manufacturing method, which makes it possible to produce the preform P without the necessity of removing the mandrel M. The connecting rod I made of composite material is formed of or includes the mandrel M and the preform P which, after the step c) of polymerization, form a one-piece part.

[0049] Preferably, the manufacturing method according to the present invention may comprise a step of applying a pressure inside the mandrel M. The pressure may be applied during one or more of the steps a), b) and c). Such a pressure may be, for example, between 3 bar (300 kilopascals) and 6 bar (600 kilopascals), and makes it possible to reinforce the compacting of the preform P.

[0050] Such a pressure also enables optimization of the tensioning of the preform P, preventing the preform P from being crushed or deformed under the effect of the tension due to the filament winding.

[0051] In one embodiment, the material of the mandrel M may include particles, such as fibers, having electrical conductivity properties and/or anti-corrosion properties.

[0052] For example, the mandrel M may be made of composite material comprising a thermoplastic matrix or a thermosetting matrix incorporating carbon or metal fibers, for example copper fibers for electrical conductivity or glass fibers for an anti-corrosion effect, in particular anti-galvanic corrosion effect.

[0053] According to one feature, the manufacturing method according to the invention may further comprise, prior to step a), a step of at least partially manufacturing or forming the mandrel M. Specifically, the mandrel M may be manufactured/formed 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 and filament winding.

[0054] At least partially means the manufacture or forming of a portion or a 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, rotational molding, thermoforming, 3D printing, pultrusion or filament winding.

[0055] Preferably, the mandrel M provided for use in step a) of the present method has a shape that is close to or similar to the shape of the connecting rod 1 to be produced so as to eliminate the need to machine the part made by the present method in order to attain a desired final shape of the connecting rod 1.

[0056] In the embodiment shown in FIG. 3a, the mandrel M is of one piece. Alternatively, the mandrel M may be formed of two or more separate parts that are assembled together.

[0057] In the example shown in FIG. 4, the mandrel M includes a tubular part 8 having first end 8a and an opposing second end 8b. The mandrel M also includes a first forked part 9 assembled to the first end 8 of the tubular part 8 and a second forked part 9 assembled to the second end 8b of the tubular part 8.

[0058] As an alternative, the mandrel M may include only a single forked part assembled to the tubular portion 8 (alternative not shown).

[0059] The assembly of several parts so as to form the mandrel M makes it possible to use several manufacturing techniques depending on the shape and the nature of the material of each part of the mandrel M.

[0060] The assembly enables adaptation of the nature of the material of each part according to its location on the mandrel M and the mechanical properties it must have. This makes it possible to reduce the cost of manufacturing the mandrel M and to reduce its overall weight.

[0061] Furthermore, assembly also allows direct manufacture of complex parts, such as the forked parts 9 and 10, without the necessity of machining these parts.

[0062] Moreover, a specific tubular part 8 may be assembled to various different forked parts, and vice versa.

[0063] In the example shown in FIG. 4, due to their complex shape, the two forked parts 9, 10 may be produced, for example, by injection molding, whereas the tubular part 8 may be produced, for example, by extrusion, pultrusion or filament winding.

[0064] Preferably, a one-piece mandrel M, such as shown in FIG. 3a, 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.

[0065] The manufacturing method according to the invention may comprise, in one embodiment, the addition of at least one reinforcement, such as a patch, on the mandrel M.

[0066] Preferably, one or more reinforcements may be added onto various areas of the mandrel M, before the winding or the deposition of the pre-impregnated fibers on the mandrel M, or on the preform P.

[0067] The position or location of the reinforcements on the mandrel M may be determined by the desired advantage to be achieved. In particular, these local reinforcements may be deposited directly on the mandrel M and/or on the preform P as the preform P is wound on the mandrel M. A function of mechanical reinforcement may be achieved by alternating winding of the preform P and deposition of the reinforcement.

[0068] The reinforcements allow local reinforcement, in particular mechanical, of certain areas of the mandrel M which may need to have greater mechanical properties, such as higher compressive strength.

[0069] According to another example, a function of control over galvanic corrosion may be obtained by directly depositing reinforcements with anti-galvanic corrosion properties on the mandrel M.

[0070] Preferably, the reinforcements are made of a material that is identical to that constituting the preform P. A reinforcement may be made up of a stack of such material so as to form a patch.

[0071] The preform P may be positioned in such a way as to overlap at least one end of the reinforcement.

[0072] Preferably, the mandrel M may include one or more housing(s) intended to receive the reinforcements, such that the shape of the mandrel M used in step a) is advantageously appropriate for forming complex areas and such that it can be functionalized without it being necessary to carry out shaping and machining of the part obtained at the end of step d).

[0073] In the example shown in FIG. 5, a first patch 11 is positioned on a forked portion 6 and a second patch 12 is positioned on a forked portion 7 of a one-piece mandrel M.

[0074] Preferably, and as also shown in FIG. 5, a first wing 13 is formed on the forked portion 6 of the mandrel M and a second wing 14 is formed on the forked portion 7 of the mandrel M, the wings 13, 14 forming two housings for retaining in place the patches 11, 12, respectively.

[0075] Placing such local reinforcements on the mandrel M before steps b) and c) enables the production of complex portions of the mandrel M and to eliminate the need to machine the part after polymerization.

[0076] Representative, non-limiting examples of the present invention were described above in detail with reference to the attached drawings. This detailed description is merely intended to teach a person of skill in the art further details for practicing preferred aspects of the present teachings and is not intended to limit the scope of the invention.

[0077] Moreover, combinations of features and steps disclosed in the above detailed description may not be necessary to practice the invention in the broadest sense, and are instead taught merely to particularly describe representative examples of the invention. Furthermore, various features of the above-described representative examples, as well as the various independent and dependent claims below, may be combined in ways that are not specifically and explicitly enumerated in order to provide additional useful embodiments of the present teachings.

[0078] All features disclosed in the description and/or the claims are intended to be disclosed separately and independently from each other for the purpose of original written disclosure, as well as for the purpose of restricting the claimed subject matter, independent of the compositions of the features in the embodiments and/or the claims. In addition, all value ranges or indications of groups of entities are intended to disclose every possible intermediate value or intermediate entity for the purpose of original written disclosure, as well as for the purpose of restricting the claimed subject matter. The invention is not restricted to the above-described embodiments, and may be varied within the scope of the following claims.