FR3053624A1 - PROCESS FOR MANUFACTURING A PIECE OF COMPOSITE MATERIAL - Google Patents

Abstract

A method of manufacturing a composite material part, comprising a thermoplastic or thermosetting matrix reinforced with fibers. It comprises successively: - a phase of making a preform (P) by winding pre-impregnated fibers (F) around at least two distant axes, - a compaction phase of the preform (P), performed at the level of at least one of the remote axes, and direction parallel to the at least one axis, and - a molding and polymerization phase under particular conditions of temperature and pressure adapted to the composite material used. The compaction phase is carried out while the preform (P) is maintained on the winding axes or on a tool (20) which materializes them.

Description

© Publication number: 3,053,624 (use only for reproduction orders)

©) National registration number: 16 61625 ® FRENCH REPUBLIC

NATIONAL INSTITUTE OF INDUSTRIAL PROPERTY

COURBEVOIE

©) Int Cl ⁸ : B 29 C 70/34 (2017.01), B 29 C 70/56

A1 PATENT APPLICATION

(22) Date of filing: 29.11.16. © Applicant (s): ADVICE AND TECHNIQUE Company at (30) Priority: 07.07.16 FR 1656533. limited liability - FR. (72) Inventor (s): VALEMBOIS GUY. ©) Date of public availability of the request: 12.01.18 Bulletin 18/02. ©) List of documents cited in the report preliminary research: Refer to end of present booklet (© References to other national documents ©) Holder (s): ADVICE AND TECHNIQUE Company at related: limited liability. ©) Extension request (s): @) Agent (s): CABINET BLEGER-RHEIN-POUPON.

PROCESS FOR MANUFACTURING A PART IN COMPOSITE MATERIAL.

FR 3 053 624 - A1

Method for manufacturing a part made of composite material, comprising a thermoplastic or thermosetting matrix reinforced with fibers.

It successively includes:

a phase for producing a preform (P) by winding prepreg fibers (F) around at least two distant axes,

a phase of compacting the preform (P), carried out at the level of at least one of the distant axes, and of direction parallel to at least one axis, and

- a molding and polymerization phase under specific temperature and pressure conditions adapted to the composite material used.

The compaction phase is carried out while the preform (P) is maintained on the winding axes or else on a tool (20) which materializes them.

i

The subject of the present invention is a method of manufacturing a part made of composite material, comprising a thermoplastic or thermosetting matrix reinforced with fibers, for example fittings.

We know that the weak point of a composite material part is the matrix, thermoplastic or thermosetting, in which the reinforcing fibers are embedded, and which generally consists of a resin, because it has a specific resistance much lower than that of the fibers. . The failure mode of a composite part is generally a rupture of the resin binding the fibers.

A good design of a composite part takes this phenomenon into account and favors a transmission of forces by putting in tension or pure compression of the fibers which has the effect of not stressing the resin. Thus, the composite material consists of layers of fibers oriented in the direction of said forces or in close directions.

In order to optimize the mechanical strength of the part to be produced, it is also necessary to avoid having the pleated or non-rectilinear composite fibers.

It is also known to manufacture parts from composite material such as fittings, by a draping operation of semi-products in the form of fabrics or tablecloths. It is also known, in particular from document EP 2 379 313, to use non-planar geometric shapes to give strength and rigidity to the part. The disadvantage of the joint use of non-planar forms and semi-finished products of tablecloths or fabrics is that it is difficult to force these semi-finished products to take these forms while guaranteeing the homogeneity of the final result. More particularly, the three-dimensional shaping of the sheets or fabrics causes the pleating of the fibers, which is detrimental to good resistance of the final part.

Furthermore, the composite parts manufactured according to this process are mainly of generally planar shapes, or more exactly of constant thickness, and they can hardly be of complex geometric shape while respecting control of the orientation and quality of the fiber drawing, and this while remaining economically attractive manufacturing.

We also know how to make composite parts by filament winding on a fusible or removable mandrel for example. One of the peculiarities of this embodiment is that it leads to an identical fiber removal whatever the winding section. Therefore, the machining of the ends of the rough obtained by filament winding leads to a reduction in the resistant section of the ends.

It is thus known to make a winding of prepreg fibers around two distant axes, to make a skein. However, the fibers do not wind in an orderly manner, because the proliferation of fibers leads to an increase in thickness at the axes, a transverse swelling in the middle part, and a filling of the space between the axes, associated to a creasing of the fibers in this area, which is very far from the desired result.

One of the aims of the present invention is to propose a method of manufacturing a part made of composite material, comprising a thermoplastic or thermosetting matrix reinforced with fibers, which makes it possible to overcome the aforementioned drawbacks, by optimizing the orientation and the placing straightness of the fibers within said part.

Furthermore, in the field of manufacturing parts made of composite material, “patches” are used, either for the purpose of repairing a damaged part, or as is apparent from document WO 2012032049 for example, in order to produce extra thicknesses at precise locations which require it, on a piece of composite material produced by braiding on a mandrel.

These patches organize the local orientation of the fibers of a part to be added to the main part in order to improve local mechanical performance. This type of patch is generally produced on sophisticated machines with low productivity. On the other hand they are often defined for a capacity of homogeneous resistance in all the plane directions.

Another object of the present invention is therefore to propose a technical solution to the production of patches for composite parts with the aim of saving production and optimizing the resistance in a preferred direction and for both directions.

The process for manufacturing a part made of composite material, comprising a thermoplastic or thermosetting matrix reinforced with fibers according to the invention, is characterized in that it successively comprises:

a phase of making a preform by winding prepreg fibers around at least two distant axes, a phase of compacting said preform, carried out at at least one of said distant axes, and in parallel direction audit at least one axis, and a phase of molding and polymerization under specific conditions of temperature and pressure adapted to the composite material used.

The compacting operation reduces the thickness of the preform in favor of the dimensions in the other two directions perpendicular to the winding axes.

In the winding zone around the axes, the compaction leads to an increase in the outside diameter of the preform and therefore, as an indirect consequence, to the tensioning of the rectilinear zone which needs to be realigned.

According to an additional characteristic of the method according to the invention, the compacting phase is carried out while the preform is maintained on the winding axes, or else on a tool which materializes them.

According to another additional characteristic of the method according to the invention, the compacting phase is carried out by bringing together two flanges between which the winding is produced.

According to another additional characteristic of the method according to the invention, the winding is carried out between two flanges which have facing faces shaped to generate variable spacings, so that the compacting phase is obtained by the forced placement of the fibers between said fibers flaccid.

Thus, winding supports are used which make it possible to direct the overall shape of the preform resulting from the winding.

According to another additional characteristic of the method according to the invention, the compacting phase is preceded by a phase of tensioning the fibers through at least one pressure operation exerted on the fibers in a direction perpendicular to the direction of said said fibers and at least one winding axis.

The present invention is not limited to the production of preforms obtained by winding.

It therefore also relates to a process for manufacturing a part made of composite material, comprising a thermoplastic or thermosetting matrix reinforced with fibers, which is characterized in that it successively comprises:

a phase of producing a preform by superimposition and / or juxtaposition of unidirectional prepreg fibers, a phase of compacting said preform, in a direction perpendicular to the direction of alignment of the fibers, and a phase of molding and polymerization under conditions particular temperature and pressure adapted to the composite material used.

According to another additional characteristic of the process according to the invention, the compacting phase is followed:

- a preform cutting phase, then

- a phase of shaping said cut preform, or one or more parts from said phase of cutting the preform,

- A phase of tensioning said cut preform or one or more parts from said phase of cutting the preform, at least in the areas bordered by the cutting lines.

According to another additional characteristic of the method according to the invention, it further comprises, simultaneously with the shaping phase of the cut preform or parts of said cut preform, a phase of covering, at least partially, of the parts of said preform or parts of said cut preform, at least in the areas bordered by the cutting lines, and at these cutting lines.

According to another additional characteristic of the method according to the invention, the phase of shaping the cut preform or parts of said cut preform, is carried out in a mold, while the tensioning phase is carried out by pressurizing of said cut preform or parts of said cut preform against the mold through a body expanded inside said cut preform and shaped.

The composite parts produced according to the invention consist of assembling layers of fabrics or layers of fibers and patches, said assembly then being polymerized in a mold allowing pressurization, mechanical by bringing surfaces together in the mold. or in an autoclave. The shaping can be completed by the swelling of a bladder for example.

The advantages and characteristics of the method according to the invention will become more clearly apparent from the description which follows and which relates to the appended drawing, which represents several non-limiting embodiments.

In the attached drawing:

- Figures la, lb and represent schematic views illustrating steps of the method according to the invention.

- Figures 2a and 2b show schematic views illustrating the first stages of manufacturing a connecting rod according to the same process.

- Figures 3a, 3b, 3c, 3d and 3e, show views illustrating the following successive stages of manufacture of the connecting rod.

- Figures 4a and 4b show views, respectively in perspective with partial cutaway and profile, of a tool for implementing the method according to the invention.

- Figure 5 shows a longitudinal sectional view of the same tool in use.

- Figure 6 shows a plan view of the preform obtained with the same tool.

- Figures 7, 8 and 9 show views illustrating successive stages of processing the preform.

- Figures 10a, 10b and 10c show partial perspective views illustrating successive stages of manufacturing a composite part, in this case a connecting rod.

- Figure 12 shows a partial schematic view illustrating a variant of the method as illustrated by Figure 10b.

- the figures 12a, 12b and 12c represent views in perspective illustrating of steps successive of manufacturing c One piece in composite in The occurrence a fitting. In reference to the figures la, lb and the on can see that the initial phase of process according to 1 ' invention consists of a

phase of making a preform by winding pre-impregnated fibers F around at least two distant axes A and B.

During this winding, there is, as shown in FIG. 1b, an expansion of the fibers at the level of the straight parts extending between the two axes A and B.

When pressure is exerted on the winding, at the level of the two axes A and B, as shown in FIG. 1 a, in a direction parallel to these axes, the thickness of the winding is reduced, it is increased the outside diameter at the level of the curved zones, and the rectilinear zones where the fibers are realigned are tensioned.

With reference to FIG. 2a, it can be seen that, according to a variant, for the manufacture of a connecting rod, a strap S is produced by winding a prepreg on a template 1 while being pressed, in a peripheral groove 10 formed between two lateral flanges 11 and 12, by a pressure roller G to allow the cohesion of a preform P to be produced in the concave parts of the template 1.

In FIG. 2b, it can be seen that this preform P is then placed in a tool 2, of which elements 20 and 21 come to bear on the concave zones of the preform P. Compaction has the effect of increasing the dimension convex shapes of the preform P, which leads to the tensioning of the fibers.

Referring now to Figures 3a, 3b, 3c, 3d and 3e, we can see that the preform P thus obtained is, firstly, Figure 3a, associated with another preform P2 produced by stacking plies, mainly unidirectional in the direction of the potential compression force of the part, then completed by layers of layers of fibers superimposed on the assembly to ensure cohesion, disposed internally to the preform, while the elements 20 and 21 of tooling maintain pressure and that compaction is carried out.

It will be noted that the simultaneous compaction of the preform P and of the preform P2 promotes the transverse swelling of the preforms P and P2 and therefore their connection, so as to obtain a set E of preforms P and P2.

In a following step, FIG. 3b, while martyrs M are substituted for the tooling elements 20, several sets E of preforms P and P2 are superimposed, after interleaving of cohesion layers C, the number of these sets E being a function of the desired thickness of the final part.

After polymerization, FIG. 3C, insert surfaces are machined, FIG. 3d, and then inserts I, FIG. 3e, are glued to it to form the eyecups, and thus obtain a connecting rod.

Referring now to FIGS. 4a and 4b, a winding support 3 can be seen comprising two flanges 30 and 31 facing each other, separated by a space 32, and between which two winding axes 33 and 34 extend.

As is more particularly visible in FIG. 4b, the space 32 is not of constant width, the opposite faces 35 and 36 of the two flanges respectively 30 and 31 not being parallel, thus the space 32 is narrower in the middle part 37 than in the end parts 38 and 39 comprising the axes 33 and 34, the variation being materialized by an inclination relative to the main plane of the flange concerned.

With reference to FIG. 5, it can be seen that during filament winding the shapes of the faces 35 and 36 of the flanges 30 and 31 force the placement of the fibers, thus the preform produced P3 has a greater thickness at the level of its parts. ends wound on axes 33 and 34, only in its middle part, which is therefore more spread out in width since it has the same number of fibers, as shown in FIG. 6.

Figures 7, 8 and 9 illustrate a variant of the invention, according to which a preform is cut. Thus the preform P3 of FIG. 6 is cut transversely at its median part so as to obtain a preform P4, FIG. 7, which essentially has an end part where the fibers have a curved shape and are concentrated in a reduced space and another extreme part, on the side where the cut is made, where the fibers are straight and spread out transversely over a small height.

In a step following the preform P4 is placed in forming dies, FIG. 8, to be compacted there in order to realign the fibers, FIG. 9.

Referring now to Figures 10a, 10b and 10c, we can see a variant of the method according to the invention, in particular as regards the winding phase.

In FIG. 10a, a winding support 4 can be seen comprising a flange 40 from which two winding axes 41 and 42 protrude, the free ends of which are each intended to receive a counterform 43, allowing control of the shape of winding around axes 41 and 42.

The internal face 44 of the flange 40 has a non-planar profile, adapted to the variations in shape, thickness and distribution of the fibers that is desired, is also comprises removable needles 45, winding 41 and 42, planted in parallel axes and which are intended, during winding, Figure 10b, to condition the concentration of fibers in certain locations, as well as to promote their orientation.

It will be noted that in the embodiment shown, the internal face 44 has in its median zone a recess 46, in which the fibers are forced during the winding operation, in particular under the impact of the positioning of the needles 45.

Note that it is possible to use the needles 45 also as a winding axis in order to organize the bundle of fibers so as to optimize the fiber drawing.

The needles 45 may advantageously be used for producing complementary fiberizing to the main fiberizing of the preform so as to consolidate its cohesion.

The preform obtained P5, has variations in shape and local thickness conditioned by the shapes of the flange 40 and counterforms 43, as well as the arrangement of the needles 45. The robotic winding is done in accordance with the placement of the needles 45.

P5 preform is then compacted to allow realignment of the fibers together with the clamping of the preform in view 1 ^{1 To} increase the fiber content relative to the resin.

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After the molding, tightening, polymerization phases, the part obtained is machined to remove unnecessary parts and create, in this case, insert seats for bonding inserts to form eyelets.

The forcing to wind in hollow shapes of the support or by local fiber stacking can allow the realization of a patch with high inertia of cross section, ensuring control of the bending of said patches, thus participating in the mechanical strength of the parts. in which the patches are inserted. This use of patches of complex shapes and of suitable thickness or cross-section allows the production of pieces of the fitting or connecting rod end type at a reduced cost and with control of the unfolding problems known in composite parts.

In FIG. 10b, it can be seen that during winding, there is created on the inside of axes 41 and 42, a vacuum V, linked to the width of the axis and to the tension exerted on the fiber, and capable of create a weakness of the room. To overcome this drawback, as can be seen in FIG. 11, needles 46 are used which are planted aligned between the two axes 41 and 42, not visible in the figure, and which serve to produce a winding 47, internal to the main external winding 48. In practice, the needles 46 are planted one by one as the winding 47 is carried out, starting with the needle 46 most distant from the axis 41 or 42. The first winding passing over the first needle 46, the second winding over the second needle 46 after putting it in place, the third winding over the third needle 46 after putting it in place, and so on. continue until reaching axis 41 or 42. This gives filling of the spaces V, in compression / traction zones.

With reference now to FIGS. 12a, 12b and 12c, we can see another case, for the production of a fitting in particular, using a winding support 5 comprising three winding axes 50, 51 and 52, not parallel, intended to be associated each with a counterform not shown, as well as removable needles 53.

After filament winding, a preform P6 is obtained, visible in FIG. 12b, which after compacting is intended to constitute a patch allowing for example the manufacture of the fitting 6 in L shown in FIG. 12c.

This fitting 6 thus comprises a core consisting of the patch 60 from the preform P6, covered with two skin, exterior 61 and interior 62. The patch 60 has thicker zones than others at the locations requiring more resistance to folding and / or unfolding.

It will be noted that to compensate for the differences in thickness of the patch 60, in order to facilitate the assemblies, a filling material 63 is placed between the skin or skins 61 and 62 and the patch 60.

It will be understood that such a fitting 6, which has zones of varied thicknesses resulting from a higher concentration of reinforcing fibers, cannot be manufactured with the existing methods, which could not allow the thickness to be varied than by varying the amount of resin which has no effect on the strength of the fitting.

Claims (9)

1) Method for manufacturing a part made of composite material, comprising a thermoplastic or thermosetting matrix reinforced with fibers, characterized in that it successively comprises: a phase of making a preform (P;  Pl; P2; P3; P4 ; P5; P6) by winding of fibers prepregs (F) around at least of them axes remote (A, B ; 33, 34; 41, 42; 50, 51, 52; 45), - a phase of compacting said preform (P; Pl; P2; P3; P4; P5; P6), carried out at at least one of said distant axes (A, B; 33, 34; 41, 42; 50, 51, 52; 45), and in direction parallel to said at least one axis, and - a molding and polymerization phase under specific temperature and pressure conditions adapted to the composite material used. 2) Method according to claim 1, characterized in that the compaction phase is carried out while the preform (P; Pl; P2; P3; P4; P5; P6) is maintained on the winding axes (A, B ; 33, 34; 41, 42; 50, 51, 52; 45), or on a tool (20; M) which materializes them. 3) Method according to claim 1 or claim 2, characterized in that the compacting phase is carried out by bringing together two flanges (11, 12) between which the winding is carried out. 4) Method according to claim 1 or claim 2, characterized in that the winding is carried out between two flanges (30, 31; 40, 43) which have faces (35, 36; 44) opposite shaped to generate variable spacings, so that the compaction phase is obtained by the forced placement of the fibers, between said flanges (30, 31; 40, 43). 5) Method according to any one of claims 1 to 4, characterized in that the compacting phase is preceded by a tensioning phase of the fibers (F) through at least one pressure operation exerted on the fibers (F) in a direction perpendicular to the direction of said fibers (F) and to at least one winding axis (A, B; 33, 34; 41, 42; 50, 51, 52; 45). 6) Method for manufacturing a part made of composite material, comprising a thermoplastic or thermosetting matrix reinforced with fibers, characterized in that it successively comprises: - a phase of producing a preform by superposition and / or juxtaposition of unidirectional prepreg fibers (F), a phase of compacting said preform, in a direction perpendicular to the direction of alignment of the fibers, and - a molding and polymerization phase under specific temperature and pressure conditions adapted to the composite material used. 7) Method according to any one of claims 1 to 6, characterized in that the compacting phase is followed: - a preform cutting phase (P3), then - a phase of shaping said cut preform (P3), or one or more parts (P4) from said phase of cutting the preform (P3), - A phase of tensioning said cut preform (P3) or of one or more parts (P4) from said phase of cutting the preform (P3), at least in the areas bordered by the cutting lines. 8) Method according to claim 7, characterized in that it further comprises, simultaneously with the shaping phase of the preform (P3) cut or parts (P4) of said preform (P3) cut, a phase of overlapping, at least partially, of parts of said cut preform (P3) or parts (P4) of said cut preform (P3), at least in the areas bordered by the cut lines, and at these cut lines. 9) Method according to claim 8, characterized in that the shaping phase of the cut preform (P3) or parts (P4) of said cut preform (P3) is carried out in a mold, while the phase of tensioning is carried out 75 by pressurizing said cut preform (P3) or parts (P4) of said cut preform (P3) against the mold through a body expanded inside said cut and shaped preform. 1/5