FR3097794A1 - Containment tool for making a composite body - Google Patents

Abstract

A containment tool for making a composite body A containment tool for making a composite body, a method of making a composite body and a composite body, the containment tool comprising a support (10), having an outer surface (11) having a groove configured to receive at least a portion of an impregnated composite cord (30), and a cover (20), intended to be attached to the support (10) and held against the latter, having an internal surface (21) capable of being be pressed against the outer surface (11) of the support (10) and configured to conform to the contour of the portion of the impregnated composite cord (30) protruding out of the groove (11) of the support (10). Figure for the abstract: Fig. 4.

Description

Containment tool to fabricate a composite body

This presentation concerns a confinement tool for manufacturing a composite body, a process for manufacturing a composite body as well as such a composite body.

Such a method is in particular particularly useful for manufacturing a composite body forming an element for a vehicle suspension, such as a spring for a vehicle suspension or a stabilizer bar for a vehicle suspension.

The automotive industry requires the manufacture of springs of large sizes and high stiffness for the suspension of road vehicles. Historically, these automotive springs are made of metal. However, in recent years, in order in particular to obtain significant weight savings, developments have been carried out to produce such springs in composite materials.

Such composite springs are thus made from a composite cord, formed of a plurality of fibrous layers impregnated with resin, wound around each other, shaped and then solidified by polymerization of the resin. In some processes, the rope passes through a bath of resin after winding each new fibrous layer. In other more recent processes, the fibrous ribbons wound around the rope being manufactured are pre-impregnated with resin.

In the manufacturing processes described above, once the composite rope is formed, it is moved to a shaping station and then to a baking oven. On this occasion, it is useful to confine the composite rope in order to maintain and compress the fibers and the resin during curing: this allows controlled polymerization of the resin and the obtaining of a final composite body having the properties expected physics.

One option proposed to ensure this containment is to place an elastic sheath around the composite rope before it is shaped and cured. This method is effective but requires a step and an additional workstation, which leads to a higher industrial cost.

There is therefore a need for a confinement tool and a method of manufacture making it possible to remedy at least in part the drawbacks inherent in the aforementioned known method.

This disclosure relates to a containment tool for manufacturing a composite body, comprising
a carrier, having an outer surface having a groove configured to receive at least a portion of an impregnated composite string, and
a cover, provided to be attached to the support and held against the latter, having an internal surface capable of being pressed against the external surface of the support and configured to match the contour of the portion of the impregnated composite cord protruding out of the throat of the support.

Thanks to such a tool, it is possible to carry out the confinement and shaping of the composite rope in a single step, using the same tool.

Indeed, it is possible to give the groove of the support the geometry of the final composite body. Thus, the installation of the composite rope in the groove of the support makes it possible to shape it according to the desired geometry for the final composite body, this geometry being frozen after curing of the composite rope.

Once the composite rope is installed in the groove of the support, and therefore shaped, the installation of the cover on the support makes it possible to firmly hold and confine the composite rope. The composite rope is thus enclosed, without play or practically without play, between the walls of the groove of the support on the one hand and the internal surface of the cover coming to marry the contour of the portion of the impregnated composite rope protruding out of the groove of the support . This confinement makes it possible to maintain and compress the fibers and the resin of the composite rope during the solidification of the latter: the network of fibers and/or the reticulated matrix of the composite rope are then less porous and denser, which improves the mechanical properties of the composite body obtained.

The confinement tool enclosing the composite rope can then be heated, in an oven or by intrinsic means for example, in order to carry out the cooking of the composite rope thus shaped and confined: the solidification of the composite rope then leads to the final composite body.

Thus, such a containment tool makes it unnecessary to put in place a containment sheath beforehand, which is often tedious. This containment tool therefore offers savings in terms of cost, cycle time and production line compactness. In addition, in the absence of a sheath, it is possible to obtain a raw composite body whose aesthetics may be preferred to a body covered with a sheath.

Furthermore, such a confinement tool facilitates handling of the composite rope after it has been shaped and before it has been cured. Indeed, thanks to this containment tool, the rope is enclosed in such a way that its geometry is locked: it is therefore possible to freely manipulate the containment tool, to transfer it for example between a shaping station and a cooking station, without the risk of the composite rope slipping out and thus losing its shape.

In certain embodiments, the support is a core and the lid is a shell added around the support. Thus, the shell forms a closed contour once attached around the support. The cover can thus firmly enclose the support. Such a configuration is also useful for fabricating three-dimensional geometries.

In some embodiments, the outer surface of the support goes around the support. Such a configuration is particularly useful for manufacturing composite bodies having one or more loops winding around a main direction of the support.

In some embodiments, the outer surface of the support is devoid of ridges. In other words, the external surface of the support is differentiable at all points. This makes it possible to obtain for the composite body geometries that are also continuous and differentiable.

However, in other embodiments, the outer surface of the support may have one or more ridges. This makes it possible to obtain a composite body of which certain portions are angular.

In some embodiments, the outer surface of the support is a cylindrical or conical surface. These geometries are particularly useful for manufacturing springs. However, it is preferably a cylindrical surface of revolution.

In some embodiments, the support is an axially symmetric cylindrical mandrel. Such a configuration makes it possible, for example, to manufacture helical springs.

In some embodiments, the support is configured to be able to fade under the composite rope. It is meant here that the outer surface of the support can move back to release the composite body after solidification. It may just as well be a mechanical recoil, using moving parts for example, as a physical recoil by disappearance of all or part of the support, by change of physical state or chemical alteration for example.

In certain embodiments, the support is fusible at a temperature below 180°C, preferably below 150°C. However, preferably, its melting temperature is above 110°C, preferably above 130°C. Thus, the support holds the composite cord at least at the start of the firing of the latter then melts at the end of the firing or after a specific stage of melting the support.

In certain embodiments, the support is made of a eutectic material, for example a tin-bismuth or lead-tin-bismuth mixture.

In certain embodiments, the groove of the support extends according to a left curve, that is to say a curve which is not contained in a plane. It is thus possible to manufacture a composite body extending in space, not limited to a given plane.

In some embodiments, the groove is helical. This makes it possible in particular to manufacture helical springs.

In some embodiments, the support groove has a constant depth.

In some embodiments, the profile of the support groove is constant. We place ourselves here in a plane transverse to the direction, possibly curvilinear, of extension of the throat.

In some embodiments, the profile of the support groove is semi-circular. The throat thus receives the inner half of the composite string.

In certain embodiments, the profile of the groove of the support is U-shaped. The composite rope thus sinks deeper into the groove: the portion of the composite rope protruding out of the groove is thus smaller than its half external.

In some embodiments, the profile of the support groove has a non-circular elliptical portion. An elliptical section of the composite body gives better mechanical properties for certain applications, in particular for coil springs.

In certain embodiments, the groove of the support has a depth comprised between 50% and 90% of its width, preferably comprised between 60% and 80% of its width. A depth of 50% is preferable when the geometry of the inner surface of the cover is fixed. On the other hand, a greater depth is possible, and possibly preferred depending on the applications, when the geometry of the internal surface of the cover is variable.

In some embodiments, the space defined between the groove of the support and the internal surface of the cover is hermetic once the cover is attached to the support. In other words, this space in which the composite rope is enclosed does not lead outside the confinement tool.

In some embodiments, the inner surface and/or the outer surface is coated with a powder, preferably talc. This dusting reduces the risk of the composite rope sticking to the inner surface and/or the outer surface and therefore reduces the risk of fibers or resin fragments being torn from the composite rope. This also facilitates the cleaning of the containment tool between two manufacturing cycles, or even makes this cleaning superfluous.

In certain embodiments, the lid comprises at least two parts, preferably exactly two parts, which can be assembled.

In some embodiments, the cover portions butt together at a non-linear, preferably castellated interface. Such a non-linear interface facilitates and ensures the alignment of the different parts of the cover.

In certain embodiments, the inner surface of the cover has a groove extending opposite the groove of the support. In such a case, the groove of the cover and the groove of the support complement each other to form a space with the dimensions of the composite rope and having the desired geometry for shaping the composite rope. The shaping of the composite rope can thus be controlled very precisely.

In some embodiments, the lid groove has a constant depth.

In some embodiments, the lid groove has a depth substantially equal to the depth of the support groove. By substantially equal is meant that the difference in depth is less than 5% of the greater of the depths. Thus, each groove cooperates with one half of the composite rope.

In some embodiments, the cover includes a resilient gasket defining the inner surface of the cover. In such a case, the internal surface of the cover is elastic and can thus deform to match the contour of the composite rope, even in the absence of a groove on the internal surface. Thanks to such a configuration, it is possible to use the same cover for several diameters of composite ropes or for several geometries of composite bodies.

In some embodiments, the resilient gasket is made of elastomer.

In some embodiments, the resilient gasket has surface roughness.

This presentation also relates to a method for manufacturing a composite body, in particular an element for a vehicle suspension, the composite body having a given shape, the method comprising the following steps:
providing an impregnated composite rope;
providing a containment tool according to any of the preceding embodiments;
installation of the impregnated composite rope in the groove of the support of the confinement tool so as to obtain said given shape;
placing the cover of the containment tool on the support; and
baking the assembly thus shaped, so as to harden the impregnated composite rope and thus obtain the composite body.

As explained with reference to the containment tool, this manufacturing process offers savings in terms of cost, cycle time and production line compactness. It also benefits from all the other advantages mentioned related to the use of the containment tool according to the presentation.

In some embodiments, the impregnated composite cord includes fibers impregnated with a resin. It may, for example, be glass fibers impregnated with an epoxy resin.

In certain embodiments, the diameter of the groove of the support is strictly less than the diameter of the impregnated composite cord provided. This makes it possible to compress the composite cord within the groove in order to better control its curing and thus obtain better mechanical properties.

This presentation also relates to a composite body obtained by the process according to any one of the preceding embodiments.

Thanks to the use of this process, using in particular the confinement tool according to the presentation, the composite body benefits from a more precise shape and internal structure, which gives it better mechanical properties.

In some embodiments, the composite body has a non-circular, preferably elliptical or near-elliptical cross-section. In particular, the section of the composite body does not necessarily have a central symmetry. However, the outline of this section remains continuous and differentiable at all points.

The aforementioned characteristics and advantages, as well as others, will appear on reading the detailed description which follows, of embodiments of the confinement tool, of the manufacturing process and of the composite body proposed. This detailed description refers to the accompanying drawings.

The attached drawings are schematic and are primarily intended to illustrate the principles of the presentation.

In these drawings, from one figure to another, identical elements (or parts of elements) are identified by the same reference signs. In addition, elements (or parts of elements) belonging to different embodiments but having a similar function are marked in the figures by numerical references incremented by 100, 200, etc.

Figure 1 is a perspective view of a first example of a containment tool.

Figure 2 is a perspective view of the support of the first example of confinement tool.

Figure 3 is a perspective view of the lid of the first example of containment tool.

FIG. 4 is a perspective view of the first example of a containment tool in which a composite rope has been installed.

Figure 5A is a cross-sectional view illustrating the installation of the composite rope in the support of the first example. Figure 5B is a sectional view illustrating the placement of the cover on the support.

Figure 6 is a perspective view of a second example of a containment tool.

Figure 7 is a perspective view of the lid of the second example of containment tool.

Figure 8A is a sectional view illustrating the installation of the composite rope in the support of the second example. Figure 8B is a sectional view illustrating the placement of the cover on the support.

FIG. 9 represents the different steps of an example of a manufacturing method.

Figure 10 is a perspective view of an example of a composite body.

In order to make the presentation more concrete, examples of containment tools, manufacturing process and composite body are described in detail below, with reference to the appended drawings. It is recalled that the invention is not limited to these examples.

Figure 1 illustrates a first example of containment tool 1 according to the presentation. It comprises a support 10 and a cover 20. In this example, the containment tool 1 is designed to manufacture a coil spring 90 of composite material such as that shown in Figure 10.

Figure 2 illustrates support 10 in isolation. Support 10 comprises an outer surface 11 in which a groove 12 is formed. Support 10 is made of a eutectic metallic material, for example a tin-bismuth mixture, giving it a relatively low melting point.

The groove 12 extends in a unidirectional curve, without branching. The groove 12 extends between two ends 12a, 12b closed and contained in the outer surface 11; in other words, the groove 12 does not open out of the outer surface 11.

In this example, the support 10 takes the form of a core, more precisely of a cylindrical mandrel, with a circular base, of main axis A, so that the outer surface 11 is also cylindrical; the groove 12 extends for its part in a spiral around the axis A corresponding to the desired geometry for the spring 90.

The groove 12 has a constant profile; in other words, it has an invariant section from its first end 12a to its second end 12b. As can be seen in Figure 5A, the section of groove 12 is semi-circular.

Figure 3 illustrates cover 20 in isolation. Cover 20 includes an internal surface 21 in which a groove 22 is made. Cover 20 is made of metal.

The geometry of the groove 22 is provided to correspond exactly to the geometry of the groove 12 of the support 10. Thus, when the cover 20 is attached to the support 10, the groove 22 of the cover 20 extends exactly along and opposite -à-vis the groove 12 of the support 10 from the first end 12a to the second end 12b. In particular, the ends of the groove 22 of the cover 20 coincide with the ends 12a, 12b of the groove 12 of the support 10 and therefore do not open out from the internal surface 21. In addition, the groove 22 also has a constant profile. : as can be seen in FIG. 5B, its section is also semi-circular.

Thus, when the cover 20 is attached to the support 10, the grooves 12 and 22 complement each other to form a closed, airtight space, not opening outside the containment tool 1, intended to receive a composite rope 30 .

In this example, the cover takes the form of a shell comprising two semi-cylindrical parts 20a, 20b capable of being assembled in order to completely surround the support 10. The internal surface 21 of the cover 20 is therefore formed by the assembly internal surfaces of each of the parts 20a, 20b of the cover 20: thus, once the cover 20 is closed, the internal surface 21 is cylindrical. Similarly, the groove 22 of the cover 20 is formed by assembling the groove sections present on each of the parts 20a, 20b of the cover 20: thus, once the cover 20 is closed, the groove 22 is helical.

The internal diameter of the internal surface 21 of the cover 20 corresponds to the external diameter of the external surface 11 of the support 10 such that, when the cover 20 is closed, the internal surface 21 of the cover 20 is pressed against the external surface 11 of the support 10.

Although this is not shown in the figures, it should be noted that it is possible, in other examples, for the two parts 20a, 20b of the cover 20 to be assembled not according to linear interfaces but according to interfaces crenellated, thus allowing their interlocking in a precise position.

Furthermore, it should be noted that the locking of the cover 20 on the support 10 can be achieved in different ways. For example, clamps can be attached around cover 20 once its parts 20a, 20b have been assembled around support 10. According to another example, each part 20a, 20b of cover 20 can include fixing flanges.

An example of a composite body manufacturing process will now be described with reference to Figure 9.

The method 80 first comprises a step of supplying 81 an impregnated composite cord 30. By “impregnated”, it is meant here that the cord 30 comprises a fibrous reinforcement impregnated with an organic resin (or matrix).

The rope 30 can be made by braiding and/or winding pre-impregnated tapes. The methods for carrying out such braiding and/or winding are well known per se and are therefore not described in detail here. Alternatively, the rope 30 can be produced by in-line impregnation, i.e. the resin or organic matrix is added during the braiding and/or winding of the fibrous ribbons of the rope 30.

In one example, the tapes comprise a reinforcement of glass fibers impregnated with an epoxy resin. Each ribbon takes for example the form of a band of constant width and thickness. Alternatively, some or all of the tapes may be of varying width and/or thickness.

The method 80 then comprises an installation step 82 in which the rope 30 is installed in the groove 12 of the support 10 of a confinement tool 1 such as the one described above. On this occasion, the cord 30 is shaped so as to obtain the shape of the final composite body 90. This installation step 82 is shown in Figures 4 and 5A.

The method 80 then comprises a step 83 of closing the containment tool 1 during which the cover 20 is attached to the support 10. Thus, on this occasion, the composite cord 30 is enclosed between the groove 12 of the support 10 and the groove 22 of the lid 20. This closing step is shown in Figure 5B.

The method 80 then comprises a step of curing 84 the assembly formed by the confinement tool 1 and the composite rope 30 enclosed in the latter. In known manner, this cooking step 84 consists in bringing this assembly to a sufficient temperature and for a sufficient time to harden the resin of the rope 30. Of course, said temperature is also low enough not to damage (for example by pyrolysis ) the resin of the rope 30.

At the end of the cooking step 84, the method 80 comprises a step of opening 85 of the confinement tool 1. The cover 20 is thus removed, which reveals the final composite body 90. However, in the case where the support 10 is a core around which the composite body 90 surrounds itself at least partially, which is the case of the helical spring 90, the final composite body 90 remains at this stage prisoner of the groove 12 of the support 10.

Consequently, in such a case, the method 80 further comprises a step 86 for releasing the composite body 90: the latter is carried out by heating the support 10 until its melting point is reached. The support 10 then liquefies, which releases the composite body 90.

However, in other process examples, this liquefaction of the support 10 can take place during the cooking step 84, preferably at the end of the latter. In such a case, the composite body 90 is released from the step of opening 85 of the confinement tool 1.

Figure 6 illustrates a second example of containment tool 101 according to the presentation. It includes a holder 110 and a cover 120. This containment tool 101 is designed to make the same coil spring 90 as the first example.

Its support 110 is quite similar to that of the first example except as regards the profile of its groove 112. Indeed, as can be seen in Figure 8A, the groove 112 here has a U-shape having a semi-circular portion. -circular 113 extended by a straight portion 114. More specifically, in this example, the depth of the groove 112 is equal to 75% of its width.

The cover 120, shown in Figure 7, has a general shape similar to that of the first example: in particular, it is here also formed of two parts 120a, 120b that can be assembled with each other.

On the other hand, in this second example, the lid comprises a base 123, rigid, made of metal, and an elastic gasket 124, deformable, made of elastomer. The inner surface 121 of the cover 120 is then formed by the surface of the elastic lining 124. The inner surface 121 here has no groove. Preferably, the inner surface 121 is rough; it is also powdered with talc.

Thus, when the lid 120 is attached to the support 110, as shown in Figure 8B, the pressure exerted slightly deforms the composite rope 130, the latter retaining a certain flexibility before cooking, and then presses the outline of the latter against the walls of the groove 112 of the support 110, forcing its lower portion to match the U-shape of the groove 112. The elastic gasket 124 also deforms to match the shape of the portion of the composite cord 130 protruding out of the groove 112.

In this way, when the cover 120 is firmly held against the support 110, the composite rope 130 is compressed between the groove 112 of the support 110 and the elastic gasket 124 of the cover 120. In such a case, the section of the composite rope 130 is therefore no longer circular: it is deformed, loses its central symmetry and retains only an axial symmetry. The final composite body 90 therefore inherits this particular shape after solidification of the composite rope 130.

The manufacturing process described above can use this second example of confinement tool 101 in the same way.

Although the present invention has been described with reference to specific embodiments, it is obvious that modifications and changes can be made to these examples without departing from the general scope of the invention as defined by the claims. In particular, individual features of the different illustrated/mentioned embodiments can be combined in additional embodiments. Accordingly, the description and the drawings should be considered in an illustrative rather than restrictive sense.

It is also obvious that all the characteristics described with reference to a method can be transposed, alone or in combination, to a device, and conversely, all the characteristics described with reference to a device can be transposed, alone or in combination, to a method.

Claims (13)

Containment tool for fabricating a composite body, comprising
a carrier (10), having an outer surface (11) with a groove (12) configured to receive at least a portion of an impregnated composite cord (30), and
a cover (20), intended to be attached to the support (10) and held against the latter, having an internal surface (21) capable of being pressed against the external surface (11) of the support (10) and configured to match the contour of the portion of the impregnated composite cord (30) projecting out of the groove (11) of the support (10). Containment tool according to Claim 1, in which the support (10) is a core and the cover (20) is a shell attached around the support (10). A containment tool according to claim 1 or 2, wherein the outer surface (11) of the support (10) is a cylindrical surface. A containment tool as claimed in any one of claims 1 to 3, wherein the groove (12) of the holder (10) extends in a left, preferably helical, curve. A containment tool according to any of claims 1 to 4, wherein the profile of the groove (12) of the support (10) has a non-circular elliptical portion. Containment tool according to any one of Claims 1 to 5, in which the groove (12) of the support (10) has a depth of between 50% and 90% of its width, preferably between 60% and 80% of its width. A containment tool according to any one of claims 1 to 6, wherein the space defined between the groove (12) of the support (10) and the inner surface (24) of the lid (20) is sealed once the lid ( 20) reported on the support (10). A containment tool according to any of claims 1 to 7, wherein the inner surface (21) and/or the outer surface (11) is powder coated, preferably talc. Containment tool according to any one of Claims 1 to 8, in which the internal surface (21) of the cover (20) has a groove (22) extending opposite the groove (12) of the support (10). A containment tool according to any of claims 1 to 9, wherein the cover (20) includes a resilient gasket (24) defining the inner surface (22) of the cover (20). A containment tool as claimed in claim 10, wherein the resilient liner (124) has surface roughness. Method of manufacturing a composite body, in particular an element for vehicle suspension, the composite body (90) having a given shape, the method (80) comprising the following steps:
providing (81) an impregnated composite rope (30);
providing a containment tool (1) according to any one of claims 1 to 11;
installation (82) of the impregnated composite rope (30) in the groove (11) of the support (10) of the confinement tool (1) so as to obtain said given shape;
positioning (83) of the cover (20) of the containment tool (1) on the support (10); and
cooking (84) of the assembly thus shaped, so as to harden the impregnated composite rope (30) and thus obtain the composite body (90). Composite body obtained by the process (80) according to claim 12.