FIELD ACCORDING TO THE INVENTION

The present invention concerns a composite panel used for the manufacture of furnishing articles, such as doors, panels, parts of furniture, shelves or suchlike.

In particular, the invention concerns a composite panel in which the succession of superimposed layers of different structure guarantees excellent properties of lightness and strength, such as to make it suitable for the production of various furnishing components.

BACKGROUND ACCORDING TO THE INVENTION

It is known that many furnishing components for homes, such as furniture and doors, can be made starting from panels of wood material which is much less valuable than solid wood.

WO-A-90/04515 describes a method for the production of structural elements, in particular furnishing components, such as table legs and table frames, in which a semi-finished product is obtained by positioning slats of wood or chipboard parallel to each other, on a flat surface of a first panel previously coated with glue. The spaces between the slats are filled with cardboard, plastic or suchlike having a honeycomb conformation, or alternatively with plastic foams. Subsequently, a second panel, provided with glue on one of its surfaces, is positioned on the slats and the filling material, and the semi-finished product thus produced is subjected to pressure and glued together.

The semi-finished product thus obtained is then possibly cut along the slats to obtain a certain number of pieces with an elongated shape and a rectangular cross-section. This solution, however, requires a prior knowledge of the final destination of the semi-finished product, or of its use, in order to allow the correct positioning of the slats. This therefore makes the semi-finished product suitable for use only for particular specific applications.

Among panels of wood material, panels of chipboard or medium-density fiberboard (MDF) are also known, which are particularly convenient from an economic point of view.

By chipboard material, or chipboard, we mean panels of wood-fiber consisting of chips resulting from the waste of normal woodworking: the chips are mixed with binder materials and then pressed to produce chipboard.

On the contrary, panels of medium density fiberboard (MDF) are obtained by grinding wood fragments, which are transformed into a fiber paste by breaking the existing bonds in the wood. This transformation is facilitated by immersion in water of the fragments of wood, with possible aid of steam and heat, or with chemical treatments based on alkaline substances, which weaken the bonds of lignin.

The chipboard or MDF panels described above can also constitute individual layers inside panels comprising several superimposed layers of different structure and composition. For example, the so-called hollow core panels, widely used in the furniture sector, comprise two external layers of wood material (chipboard or MDF) distanced from each other by an intermediate layer of lighter material, with the function of lightening the overall structure of the panel. In this way, a hollow core panel is suitable for specific applications, such as for example for the production of panels for wardrobes.

In a hollow core panel the external layers based on wood material are generally covering elements and are attached, generally by gluing, on a frame also made of solid wood, chipboard or MDF. The frame is formed by a series of perimeter strips and internal strips, it can also be made in a single piece and empty lightening sectors are created between the perimeter and internal strips.

To increase the resistance of the hollow core panel, a filling material can be added in the empty sectors of the frame, for example, impregnated paper structured in honeycombs. The hollow core panel is therefore also referred to as a honeycomb panel. To further increase strength, the paper, where required, is replaced with panels of expanded polyurethane or polystyrene or plastic honeycomb or aluminum honeycomb.

As mentioned, given the reduced specific weight, the hollow core panel is frequently used to make doors and panels for wardrobes that would be too heavy if made, for example, of chipboard or MDF. Other applications in the furniture sector are shelves, living room shelves and in general any application that requires lightness, non-deformability and robustness.

It is obvious that, according to the different requirements of size of the furnishing article to be made, it is necessary to provide a considerable series of hollow core panels with different sizes.

To obviate the need to produce a varied number of hollow core panels of different sizes, it is normally provided to produce standard sized hollow core panels, which are then cut to obtain the various panels of the desired sizes.

To this purpose, certain preventive design considerations are necessary, insofar as the cuts, the hardware, the hinges and the screws can be applied only on the frame of the panel, hence on the internal and/or perimeter strips, and not in correspondence with the lightening sectors.

In the production of furnishing articles, therefore, these hollow core panels must necessarily be cut in correspondence with the strips that make up the internal frame, so as to obtain the desired sizes. The cutting, especially on an industrial level, of these hollow core panels to obtain panels of specific and precise sizes, presents considerable difficulties.

One disadvantage of this cutting procedure is the objective difficulty of identifying precise points of reference on the hollow core panel before and after cutting. Substantially, therefore, the problems related to cutting arise from the difficult identification of the strips, especially the internal strips, along which to make the cut. In particular, this disadvantage is accentuated after the first cut of the hollow core panel along a given strip. Following the first cut, in fact, the areas of the panel where the other strips are positioned and, thus, where to make the subsequent cuts are generally hidden.

A consequent problem therefore derives from the fact that, in conventional hollow core panels, there is a concrete risk of cutting the panel that affects the filling material of the empty lightening sectors and not a cut correctly made along the internal or perimeter strips of the frame.

Another disadvantage of all conventional panels comprising lightening sectors is connected to the fact that the smaller size panels obtained after cutting the starting panel must be subjected to edging operations, and if the cut is made in correspondence with the honeycomb lightening sector, it is difficult to cover the edges of the panel obtained due to the poor consistency of the material in correspondence with the edges: in fact, the application of the covering (for example laminates, polymer sheets) involves the use of high pressures, so that the material in correspondence with the edge could yield. Another disadvantage of conventional hollow core panels is correlated to the fact that even the operations to assemble the panel and fix it to a wall are made difficult by the presence of the lightening sector, since the hinges, screws, and other hardware elements for the attachment cannot be applied in correspondence with these sectors of the panel, since the latter do not guarantee an adequate mechanical grip for the screws and dowels that are used.

There is therefore a need to obtain a specific panel for furnishing elements, such as furniture or doors, which is able to overcome the disadvantages described above of the hollow core panels that are generally used.

A first purpose of the present invention is therefore to make available to persons of skill a panel for furnishing elements having a particular structure, such that it can be cut without inconvenience in its longitudinal and/or transverse direction in order to create panels of smaller sizes according to the needs of use. Another purpose of the present invention is to provide a panel with a particular structure, such as to allow and facilitate the operations of covering the edges (edging) of smaller panels, obtained by cutting the starting panel into several portions.

Another purpose of the invention is to provide a panel with a particular structure in which the operations of assembling the original panel and attaching it to a wall are facilitated, as well as the smaller panels which are obtained from the original panel by cutting.

The Applicant has devised, tested and embodied the present invention to overcome the shortcomings of the state of the art and to obtain these and other purposes and advantages.

SUMMARY ACCORDING TO THE INVENTION

The present invention is set forth and characterized in the independent claims, while the dependent claims describe other characteristics according to the invention or variants to the main inventive idea.

In accordance with the above purposes, the invention describes a composite panel to make furnishing elements comprising:

- at least one structural layer based on wood material;

- at least two lightening layers each provided with empty spaces and filling elements; - two external covering layers.

According to one aspect of the present invention, the structural layer based on wood material is interposed between two of the lightening layers. Moreover, each of the external covering layers is superimposed over one of the lightening layers and defines a respective flat external surface of the panel.

Therefore, the composite panel according to the invention has a particular structure with superimposed layers, in which every structural layer (wood material) of the composite panel is interposed between a lower lightening layer and an upper lightening layer.

The presence in an intermediate position inside the composite panel of one or more structural layers based on wood material guarantees strength and, in general, good mechanical properties of the composite panel according to the present invention. At the same time, the presence of two lightening layers above and below each structural layer guarantees a lightening of the overall structure, so that the composite panel can also be used to make furnishing components with a certain thickness but not too heavy.

Furthermore, compared with a conventional hollow core panel, in which the cutting operations can be carried out only in correspondence with the frame, and not in correspondence with the empty lightening sectors, in the composite panel according to the present invention the cutting operations can be carried out in its longitudinal and/or transverse direction without particular disadvantages, thanks to the support and mechanical resistance given by the at least one intermediate structural layer based on wood material.

Another advantage of the particular structure of the composite panel according to the invention is that the smaller panels obtained by cutting the starting panel can have their edges covered (edging) without disadvantages. In fact, the edge covers not only anchor themselves on the thickness of the external covering layers but can also anchor themselves on the thickness of the structural layer, preventing it from bulging toward the inside of the lightening layers themselves. According to a variant embodiment of the present invention, in the specific case where the composite panel is intended to obtain furnishing elements with particular mechanical resistance, the lightening layers of the panel can be made more resistant and structurally more solid by disposing, for example in a longitudinal and/or transverse direction of the panel, a sequence of reinforcement inserts at a predetermined distance.

Other embodiments of the present invention concern a method to produce a composite panel comprising:

- preparing one or more structural layers based on wood material in an intermediate position between two lightening layers provided with empty spaces and filling elements;

- providing a first covering layer above a first of the lightening layers and a second covering layer below a second of the lightening layers;

- gluing and pressing the structural layer, the lightening layers and the covering layers.

BRIEF DESCRIPTION OF THE DRAWINGS

These and other characteristics of the present invention will become apparent from the following description of some embodiments, given as a non-restrictive example with reference to the attached drawings wherein:

- fig. 1 is a perspective view of a sequence of five layers suitable to be glued and subjected to pressing in order to obtain the composite panel according to the present invention;

- fig. 2 is a perspective view of a portion of the composite panel according to the invention after gluing and pressing of the five layers in fig. 1 ;

- fig. 3 is a sequence of five layers suitable to be glued and subjected to pressing in order to obtain a variant embodiment of the present invention, according to which both the lightening layers of the composite panel are equipped with reinforcement inserts in their longitudinal and/or transverse direction;

- fig. 4 is a perspective view of a portion of the composite panel after gluing and pressing of the five layers in fig. 1 ;

- fig. 5 is a schematic perspective view of a possible application of the composite panel according to the present invention.

To facilitate comprehension, the same reference numbers have been used, where possible, to identify identical common elements in the drawings. It is understood that elements and characteristics of one embodiment can conveniently be incorporated into other embodiments without further clarifications.

DETAILED DESCRIPTION OF SOME EMBODIMENTS Fig. 1 shows a perspective view of a possible embodiment of the present invention in which a sequence of five layers are suitable to be glued and subjected to pressing in order to obtain the composite panel 10 according to the present invention.

In particular, a structural layer 11 is shown, based on a wood material disposed in an intermediate position between two lightening layers, upper 12a and lower 12b.

Although the drawings show a panel with a single structural layer 11 interposed between two lightening layers 12a, 12b, it is not excluded that in possible embodiments, not shown, the number of structural layers 1 1 is higher than one, for example two or three, and that each of said structural layers 11 is interposed between two lightening layers. By way of example only, if the panel 10 comprises two structural layers 1 1, it can be provided that one lightening layer is interposed between the two structural layers, and that additional lightening layers are superimposed on each of the latter.

The lightening layers 12a, 12b are provided inside with a sequence of empty spaces 13 and a sequence of filling elements 14. In particular, the filling elements 14 can delimit said sequence of empty spaces 13. By way of example only, the empty spaces 13 can be defined by a plurality of cells having the same shape or size, or different from each other, with the function of lightening the lightening layer 12a, 12b.

In accordance with possible solutions of the present invention, the at least one structural layer 1 1 is made of a wood material selected from solid wood, chipboard, medium density fiber (MDF), plywood.

The lightening layers 12a, 12b have the function of lightening the structure of the composite panel 10, thanks to the presence of the empty spaces 13. The lightening layers 12a, 12b preferably comprise filling elements 14 with a honeycomb structure (fig. 5).

In accordance with possible solutions, the honeycomb structure is defined by a plurality of flat surfaces 18, defining the filling elements 14, connected to each other to define a plurality of cells, defining the empty spaces 13, having polygonal cross section shapes. The flat surfaces 18 are disposed, during use, substantially orthogonal to the flat development of the external covering layers 15, 16 and of the structural layer 1 1. This disposition of the flat surfaces 18 gives the composite panel 10 an adequate resistance even to compression stresses. This prevents, for example, any collapse of the composite panel 10 when orthogonal forces are applied to the flat surface of the composite panel 10, for example due to the anchoring action of threaded elements, or other.

In some embodiments, the filling elements 14 generally consist of a material with a lower density than at least the structural layer 11 and the lightening layers 12a, 12b.

The lightening layers 12a, 12b can be made of a material selected preferably from paper and cardboard.

According to variant embodiments, the lightening layers 12a, 12b are made of panels of expanded polyurethane, polypropylene or polystyrene, or provided with a cellular structure.

According to another variant embodiment, the lightening layers 12a, 12b are made of plastic, or aluminum, provided with a plurality of open cells.

Fig. 1 also shows the provision of an upper covering layer 15 above the lightening layer 12a and the provision of a lower covering layer 16 below the lightening layer 12b.

In particular, during use, each of the external covering layers 15, 16 is superimposed on one of the lightening layers 12a, 12b and defines a respective flat external surface 19 of the composite panel 10.

In accordance with some embodiments of the present invention, the structural layer 1 1, the lightening layers 12a, 12b, and the external covering layers 15, 16 have a flat shape and substantially have the same surface sizes, so as to allow their reciprocal superimposition. In this way it is possible to obtain a composite panel 10 with a mainly flat shape, that is, in which its thickness is much smaller than the surface development sizes. By way of example only, the sizes of the panel width and surface length are at least 20 times greater than the thickness of the panel itself.

According to another embodiment of the invention, the structural layer, the lightening layers, and the external covering layers are glued together, one superimposed over the other.

According to possible solutions, the lightening layers 12a, 12b have a lower density than that of the external covering layers 15, 16 and of the structural layer 11.

By way of example only, it can be provided that the lightening layers 12a, 12b have a density lower by at least about 0.5 times, preferably lower than at least about 0.8 times, than the density of the external covering layers 15, 16 and the structural layer 1 1.

According to another solution of the invention, the external covering layers 15, 16 and the structural layer 11 have substantially the same structural mechanical properties.

According to possible solutions, the external covering layers 15, 16 and the structural layer 1 1 have a thickness S comprised between 2mm and 8mm, preferably between 4mm and 6mm. These values of thickness allow both the external covering layers 15, 16 and the structural layer 1 1 to have sufficient structural resistance to anchor the attachment elements.

According to other embodiments of the invention, the lightening layers 12a, 12b have a thickness H comprised between 1 and 5, preferably between 1 and 3 times the thickness S of the external covering layers 15, 16 or of the structural layer 1 1. This condition allows to obtain a composite panel with a great thickness but with a limited overall weight.

In accordance with possible solutions of the present invention, the external covering layers 15, 16 are made of the same material with which the structural layers 1 1 are made.

In particular, it can be provided that the external covering layers 15, 16 are generally made of a wood material selected from solid wood, chipboard, medium density fiber (MDF) or plywood. Furthermore, depending on the final use of the composite panel 10 according to the present invention, it is advisable to cover the external surfaces of the covering layers 15, 16 to make them appreciated from the aesthetic point of view.

For this purpose, at least the external surfaces 19 of the external covering layers 15, 16 are covered by an enhancing layer. The enhancing layer can have a thickness of less than 1.5mm.

For example, if the composite panel 10 according to the invention is intended to constitute an interior door, the surfaces of the covering layers 15, 16 can be enhanced by coatings provided with decorative elements (not shown in Fig. 1). The coatings, or enhancing layers, can be made of veneer, cellulose material impregnated with resins in laminated and/or painted form. Alternatively, as coatings of the covering layers 15, 16, it is possible to use films with a base of thermoplastic polymers selected from polypropylene (PP), polyvinyl chloride (PVC), polyethylene terephthalate (PET) and acrylonitrile-butadiene-styrene (ABS).

Fig. 2 is a perspective view of a portion of the composite panel 10 according to the invention after gluing and pressing the five superimposed layers indicated in fig. 1. Starting from top to bottom, the cross sections of the following layers are shown in sequence: covering layer 15, upper lightening layer 12a, structural layer 11 based on wood material, lower lightening layer 12b and covering layer 16. According to possible solutions, the composite panel 10 can consist of the structural layer 1 1, the two lightening layers 12a, 12b between which the structural layer 11 is interposed and put in contact, and the two external covering layers 15, 16, each of which is superimposed over and in contact with one of the two lightening layers 12a, 12b.

It is important to note that the structural layer 11 consisting of wood material is in an intermediate position inside the composite panel 10 to guarantee maximum support for the overall structure of the panel 10, in case it is subjected to cutting operations to cut it into smaller panels and consequent edging of the panels obtained.

The same reasoning also applies if the composite panel 10 according to the present invention is subjected to assembly operations: the screws, hinges and other pieces of hardware can be suitably applied both to the structural layer 11 and to one of the external layers 15 or 16, which are both made of wood material, able to resist the mechanical stresses induced.

By way of example only, fig. 5 describes a possible application of the present invention to a furnishing element 20 which comprises a composite panel 10 in accordance with the present invention, a hardware component 21 positioned resting on the external covering layer 15 and an attachment element 22 configured to attach the hardware component 21 to the external covering layer 15 and to anchor itself at least to the structural layer 1 1. In possible solutions, the hardware component 21 can comprise a plate, a hinge, a bracket or possible combinations thereof. The attachment element 22 can comprise, by way of example only, a screw, a pin, a plug or similar or comparable elements.

According to possible embodiments, the attachment element 22 and the hardware component 21 can be made in a single body.

Fig. 3 is a sequence of five layers suitable to be glued and subjected to pressing in order to obtain a variant embodiment of the present invention.

In particular, fig. 3 shows a structural layer 11 based on wood material disposed in an intermediate position between two lightening layers, upper 12a and lower 12b. The lightening layers 12a, 12b comprise inside them a sequence of empty spaces 13 and a sequence of filling elements 14.

In this case too, the lightening layers 12a, 12b have the function of lightening the structure of the composite panel 10, thanks to the presence of the empty spaces 13. Furthermore, the lightening layers 12a, 12b comprise filling elements 14 having an honeycomb structure (not shown in fig. 3), and consisting of a material preferably selected from paper, cardboard, panels of expanded polyurethane or polystyrene, plastic or aluminum.

Unlike the embodiment shown previously in figs. 1-2, the variant of fig. 3 shows how the lightening layers 12a, 12b can be provided with a sequence of reinforcement inserts 17 inside them. In particular, in a first portion of the lightening layers 12a, 12b, reinforcement inserts 17a are shown to be disposed along the longitudinal axis of the panel at a predetermined distance from each other. In a median portion of the lightening layers 12a, 12b, reinforcement inserts 17b are shown to be disposed along the transverse axis of the panel at a predetermined distance from each other. Finally, in a terminal portion of the layers 12a, 12b, the reinforcement inserts 17a, 17b are shown to be disposed along the longitudinal and transverse axis of the composite panel 10 according to the invention.

As shown in fig. 3, the reinforcement inserts 17a, 17b are oblong elements, that is, they develop in a prevailing direction. According to the variant embodiment shown in fig. 3, the reinforcement inserts 17a, 17b are preferably made of a material selected from chipboard, medium density fiber (MDF), plywood or aluminum. Fig. 3 also shows the provision of an upper covering layer 15 above the lightening layer 12a and the provision of a lower covering layer 16 below the lightening layer 12b.

Fig. 4 is a perspective view of a portion of the composite panel 10 according to the invention after gluing and pressing the five superimposed layers indicated in fig. 3. Starting from top to bottom, the transverse surfaces of the following layers are shown in sequence: covering layer 15, upper lightening layer 12a, structural layer 11 based on wood material, lower lightening layer 12a and covering layer 15. It should be noted that both the lightening layers 12a, 12b are equipped with reinforcement inserts 17 which extend along the longitudinal direction of the panel 10.

Also in the case of fig. 4, the structural layer 1 1 consisting of wood material occupies the intermediate position inside the composite panel 10 to guarantee maximum support for the overall structure of the panel, in case it is subjected to cutting operations to cut it into panels of a smaller size and consequent edging of the panels obtained.

With reference to the embodiment shown in figs. 1-5, where the composite panel comprises a sequence of five superimposed layers, another aspect of the present invention is a method to produce a composite panel 10 for furnishing elements comprising the following steps:

- preparing a structural layer 11 based on wood material in an intermediate position between two lightening layers 12a, 12b comprising empty spaces 13 and filling elements 14;

- providing a first covering layer 15 above the lightening layer 12a and a second covering layer 16 below the lightening layer 12b;

- subjecting the structural layer 1 1, the lightening layers 12a, 12b and the covering layers 15, 16 to gluing and compression.

In some cases, depending on the final use of the composite panel 10, a sequence of reinforcement inserts 17a, 17b can be provided inside one or both the lightening layers 12a, 12b, before subjecting them to the gluing and pressing step with the remaining layers of the composite panel.

It is also clear that, although the present invention has been described with reference to the specific examples shown in figs. 1-4, a person of skill in the art shall certainly be able to achieve many other equivalent forms of composite panel, having the characteristics as set forth in the claims and hence all coming within the field of protection defined thereby.

In the following claims, the sole purpose of the references in brackets is to facilitate reading and they must not be considered as restrictive factors with regard to the field of protection claimed in the specific claims.