The present invention relates to a composite panel, that can notably be used in the production of large surfaces, for example with a length greater than 10 m and a width of between 1 m and 3 m or between 1 m and 10 m, for a thickness of up to 10 or so centimeters.
It also relates to a composite panel that can easily be used in producing three-dimensional objects, having folding or curving or bending zones.
It also relates to a method for producing a composite panel.
It also relates to novel individual panel structures. These individual panels can, for example, be used in the context of the composite panel structure according to the invention, or in the context of a method for producing a composite panel according to the invention.
A panel structure is known, illustrated in
There are techniques for joining such panels, for producing large surfaces, but these do not give satisfaction, whether for esthetic reasons, because of the coupling zones between the adjacent panels, or because of the difficulty in producing three-dimensional shapes with such panels resulting from the joining of individual composite panels.
One example of application of this type of panel relates to the production of bodywork elements, for example the body of a trailer or of a truck.
It will be understood that this type of joining takes a long time to produce and entails steps of aligning large surfaces such as the surfaces 12 and 14, which are, by their size, not easy to handle.
There is therefore the problem of finding a novel technique for producing composite panels, in particular suitable for producing large surfaces, which does not present the drawbacks explained above.
A structure that makes it possible to produce three-dimensional surfaces simply, without using additional parts such as the angle brackets commonly used in the known structures, is particularly sought.
A novel composite panel structure is also sought that is reinforced and more solid than the panels of known type, in order to withstand compression and extension stresses, notably when the panels are joined to form large surfaces.
The present application describes such a composite panel structure, comprising:
Such a composite panel may also comprise one or more notches, each being positioned in any direction relative to said strips of material, for example parallel or perpendicular thereto, one or more notches forming one or more folding zone(s) and making it possible to fold the panel according to the direction of this or these notches.
A method for manufacturing a composite panel is also described, comprising:
a)—joining a plurality of individual composite panels, each comprising at least one core and two surface skins, each panel being joined with at least one adjacent individual panel by one of its sides,
b)—fixing a strip of reinforcing material on each joining zone or line joining a panel with the adjacent panel or panels, in a corresponding indented, or thinned, or recessed, zone, on either side of the joining zone or line and along the latter.
Each strip is fixed by heat, without adding glue or adhesive material.
Each strip is preferably made of a textile material, even more preferably of the same nature as that of the skins. Each strip is uniform, and does not entail any injection operation.
An indented, or thinned, or recessed, zone can be obtained by forming a groove in the skin, by eliminating material therefrom, over a part of its thickness. In this case, the core of each of the panels remains of substantially constant thickness.
According to another embodiment, an indented, or thinned, or recessed, zone can be obtained by exercising a pressure, on each of the panels to be joined, for example in a heating operation, the thickness of the corresponding portion of the core in, or under, this zone being reduced relative to the adjacent zones not having been subjected to said pressure. In this case, there is no removal of material from the skin.
Such a method can also comprise the formation of at least one notch, or of a zone in which material has been eliminated, in at least one of the panels, in any direction relative to said strips of material, for example parallel or perpendicular thereto, this notch making it possible to fold the panel according to its direction. This notch zone or zone of elimination of material can penetrate into the core of the panel or panels.
A method is also described for producing a three-dimensional shape comprising a plurality of composite panels, comprising the implementation of the above method and described in the present application, followed by a step of folding along at least one of said notches; generally, a fold will be made along one or more notch zones. It is also possible to join together a number of duly produced three-dimensional shapes.
A method for manufacturing a composite panel or for producing a three-dimensional shape may also comprise the elimination of a zone of material, for example by cutting, in at least one of the individual panels, before folding.
A flash elimination can be performed after the panels have been joined.
After fixing the strips of reinforcing materials, it is also possible to cover the assembly with, on each side of the duly produced structure, at least one external sheet, for example of polypropylene.
In a method and/or a device according to the invention, a composite panel as described above can have:
Furthermore, a method and/or a device as described above can comprise one or more of the following features.
The core of such an individual composite panel can comprise at least one honeycomb layer and/or layer of polypropylene foam.
The surface walls or skins are, for example, of polypropylene, possibly reinforced by glass or any other type of reinforcement.
As a variant, the structure of an individual panel can comprise a textile layer, positioned on either side of the core of the panel, and an external layer of polypropylene, each textile layer being positioned between the core of the panel and an external layer.
The core of such an individual composite panel can be hybrid, comprising at least two layers of different natures, for example comprising a first layer of foam, a second honeycomb layer, and a third layer of foam.
Such a composite panel can also comprise external sheets, for example of polypropylene, covering the skins and the strips of reinforcing material.
The external surface of the reinforcing strips can be flush with the external surface of the adjacent panels, or protrude from or be raised relative to this surface.
An individual panel structure is also described in the present application that can be used notably in combination with a method, or with a composite panel structure, which has just been described.
Such an individual panel comprises at least one core and two surface walls or skins.
The core can comprise at least one honeycomb layer and/or layer of polypropylene foam.
The surface walls or skins are, for example, of polypropylene, possibly reinforced by glass or any other type of reinforcement.
As a variant, the structure of an individual panel can comprise a textile layer, positioned on either side of the core of the panel, and an external layer, for example of polypropylene, each textile layer being positioned between the core of the panel and an external layer.
The core of such an individual panel can be hybrid, comprising at least two layers of different natures, for example comprising a first layer of foam, a second honeycomb layer, and a third layer of foam.
Such a composite panel can also comprise external sheets, for example of polypropylene, covering the skins.
The present invention will be better understood on reading the description of exemplary embodiments given below, in a purely indicative and nonlimiting manner, by referring to the appended drawings in which:
Examples of novel structures resulting from the joining of individual panels are illustrated in
In the different figures, an orthogonal reference frame Oijk is used.
Moreover, given the dimensions obtained by a plurality of joined panels, the expression “plane of the panel or panels” will be used to denote a plan extending on one of the external surfaces of the assembly obtained. This is the plane Oij or a plane parallel thereto. The sides of the panel extend in a plane perpendicular to Oij; in particular, the sides that are joined at the joining zone 28 are in the plane Oik.
The structure of
The core consists, for example, of a honeycomb structure, the cells of which extend in a direction substantially perpendicular to each of the planes defined by the plane of the panels or the lateral skins 24, 26. Examples of materials that can form the core of each of the panels will be seen later.
It can also be seen that, in each of the skins 24, 26, a notch, or a groove, 31, 33, has been formed in a zone which overlaps the joining zone 28. The depth ε of each of the notches is less than the thickness e of each of the skins. e is, for example, between 0.3 mm and 5 mm. ε can be between 0.1 e and 0.7 e, and is preferably roughly equal, or equal, to 0.5 e.
Each notch has a width λ substantially between 10 mm and 100 mm, for example 40 mm, and is positioned substantially symmetrically on either side of a plane P defined by the joining zone 28 of the two panels. Each notch being in a direction perpendicular to each of
In the embodiments described above, notably in conjunction with
Let Ea be the thickness of the core in the zones in which no reinforcing strip is positioned. Unlike the case of
If the reinforcing strips 32, 34, of thickness c, have an external surface which is flush with the external surface of the corresponding skin 24, 26, then the following substantially applies: 2ε+E′a≈Ea. As a variant, the external surface of each reinforcing strip extends above the external surface of the corresponding skin 24, 26. According to one example, if e is the thickness of the skin, then, in each reinforcing block, the thickness of the material, on either side of the core, is approximately e+ε. It is possible to have, for example, e=ε, that is to say that the thickness of the reinforcing strip is substantially equal to the thickness of the skin. According to one example, if the latter is approximately equal to 0.7 mm, then, in each reinforcing zone, the thickness of the skin and of the reinforcing strip reaches approximately 1.4 mm.
In all cases, each strip will make it possible to reinforce the structure when a tension, as schematically represented in
Similarly, there could be an assembly of n panels (n>3 or n>4, for example n=10, or 20, or n>20) with reinforcing strips 32, 34 positioned as indicated in
These slots or notches have a depth, under the external surface defined by the skin 24, which can be variable, but which can be sufficient to end in the core 22 of the panels.
These slots or notches will make it possible to fold the panel, after assembly, along an axis, parallel to the axis Oi and situated along the joining zone 28.
After folding, the structure has roughly the form represented in
The number, the width, the depth and the form of these notches (in a plane jk substantially perpendicular to the plane defined by the structure as a whole) depend on the folding flexibility that is desired, and on the angle α that is desired between the two faces defined by the different panels situated on either side of the set of notches. This angle α can range between a few degrees, for example 10° and 90°. It can be greater than 90°, and, for example, less than 160°, for applications in which a support surface S is required, as illustrated in
The notches 41 are represented in
Different techniques can be used to eliminate skin on one of the surfaces to allow folding on a panel:
The forms 51-54 shown by broken lines represented in
It is then possible to produce a folded structure 100 such as that of
It is also possible, as represented in
There is then obtained what is called a closed-edge panel. This structure, in which the core-forming material 22 is clad by walls, makes it possible to provide an increase in rigidity compared to the open-edged structure of
Examples of panel structures that can be implemented in the context of the technique explained in the present application will now be given. However, these structures can also be used independently of the methods and of the composite panel structures (with reinforcing zones) which are described in the present application.
A first example relates to a panel with cellular core, for example, honeycombed, the structure of which is illustrated in
The dimensions can, for example, be as follows (the same notations are adopted in this example and in the subsequent examples as in
A second example relates to a panel with polypropylene foam core (structure illustrated in
The dimensions of this panel can, for example, be as follows:
A third example relates to a panel with a monolithic polypropylene coating, the structure of which is illustrated in
The role of each sheet is to provide a weight supplement for welding, and/or an improved seal-tightness and/or a non-skid external surface . . . .
It is in the textile skins 24, 26 that, if necessary, the notches or grooves 31, 33 are produced, into each of said notches or grooves it will then be possible to insert a reinforcing strip 32, 34, as explained above in conjunction with
The dimensions of this panel can be as follows:
A fourth example relates to a panel with mixed or hybrid or complex core (for example: polypropylene honeycomb+polypropylene foam), the structure of which is illustrated in
Such a structure exhibits very good mechanical and thermal properties. Each of the cores 122, 222 has a thickness which can be, for example, between 3 mm and 5 mm. These two parts of the core contribute to enhanced thermal efficiency, the mechanical strength of the assembly being mainly provided by the central core 22, but also by the reinforcing strips 32, 34, which can be positioned in optional notches or grooves 31, 33. The latter will be produced in the textile skins 24, 26. Into each of these notches, it will then be possible to insert a reinforcing strip 32, 34, as explained above in conjunction with
The dimensions of this panel can be as follows:
Each of above panel examples can be manufactured either with so-called “open” edges or with so-called “closed” edges, as already explained above in conjunction with
An example is given below of how to carry out a method for joining composite panels.
The following steps are carried out:
If notches such as the notches 41 of
The description begins with an explanation of how two panels can be welded, in conjunction with
For this, two panels 21, 23 are welded together, by their two sides, edge to edge, with no intermediate element between two adjacent edges to be joined, by raising the temperature of each edge of the panels to be welded: for example, a lateral portion of each of the panels 21, 23 is placed in contact with a heating element 50 (
They can be panels of any of the types explained above, in conjunction with
An operation of deflashing of the welds can then be carried out (
A reinforcing of the welds can be obtained using one or more strips (preferably: one on each face) of textile, as illustrated in
In
Similarly, the heating elements are placed in contact with reinforcing strips 32, 34, intended to be inserted into the grooves 31, 33. Preferably, the heating element simultaneously heats a groove 31 (respectively 33) and the strip of material 32 (respectively 34) intended to be inserted therein.
The heating elements are then moved away, and the strips of material 32, 34 are positioned facing the groove 31, 33 into which each has to be inserted.
Means or elements 60, 60′ can then be brought close in order to cool the material of these strips 32, 34 (
Another implementation of a method according to the invention is explained in conjunction with
This implementation starts with an assembled structure, such as that of
In
Similarly, the heating elements are placed in contact with these reinforcing strips 32, 34. Preferably, the heating element simultaneously heats the reinforcing strip 32, 34 and the part of the surface of one of the skins on which this same strip of reinforcing material 32, 34 has to be positioned. During this step, a pressure can be exerted to begin to “indent” the corresponding zones of the skins toward the interior of the panels.
The heating elements are then moved away, and the strips of materials 32, 34 are positioned on the zones of the skins on which, or in which, these strips have to be inserted.
Means or elements 60, 60′ can then be close in order to cool the material of these strips 32, 34 (
In this embodiment, the flush positioning of each strip with the panels is produced by applying a pressure during the phase of heating and cooling of the surfaces.
An implementation using a technology of heating by contact with the strips and the panels has been described above, but there are other possible heating techniques.
It is notably possible to implement a heating technique which does not involve any contact, for example using infrared lamps.
The method described above in conjunction with
The methods described above in conjunction with
In the case of the structure of
Mechanical tests were carried out, these tests were conducted with the measurements given in table I below.
The first features involve comparing the flexural behavior of specimens taken during standard manufacture and specimens of panels joined according to the method detailed previously.
The single-panel structure is a structure of the type of
The structure of the panels joined according to the invention is identical.
Table I highlights the fact that the panel joining technology described above considerably enhances the flexural characteristics of the thermoplastic composite panels.
The teaching of the present application, regarding both the production method and the panels themselves, therefore makes it possible to achieve a significant reinforcement of the panels, as well as a much more flexible use than the panels currently known.
Number | Date | Country | Kind |
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1154083 | May 2011 | FR | national |
This application is a continuation of International Patent Application Number PCT/EP2012/058828 filed on 11 May 2012 which claims priority to French Patent Application Number 1154083 filed on 11 May 2011, both of said applications being herein incorporated by reference in their entirety.
Number | Date | Country | |
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Parent | PCT/EP2012/058828 | May 2012 | US |
Child | 14077466 | US |