State of the art [0002] The strength of a flat steel plate is determined by the kind of steel and the thickness of the plate. A thicker plate has a greater strength.

[0003] Metal front, roof or sandwich panels are made of plates, usually of steel, with a thickness varying from 0.4 mm to 1.25 mm. Steel roof or front panels, consisting of a single thin plate, cannot be realised as flat. This is because they possess insufficient strength to be able to be used as roof or façade element. These panels have to be profiled longitudinally in order to provide them with sufficient strength. Steel sandwich panels have a very limited strength if they are realised with flat plates.

Here, in order to obtain sufficient strength, they too have to be profiled longitudinally. However, profiling detracts immensely from the aesthetic aspect of such panels.

[0004] Therefore, manufacturers of steel roof or front panels and steel sandwich panels continuously have to balance the strength of the panel on the one hand and the aesthetic aspect of a. panel on the other hand.

[0005] Additional strength, both for steel roof or front panels and steel sandwich panels, is, as mentioned before, obtained by profiling them longitudinally. The deeper the profiling, the stronger the panel, but the less aesthetically attractive. A larger number of profiles in a panel results in additional strength as well, but again this is at the cost of the aesthetic aspect.

[0006] On the site of Insulated Panel Systems (www. insulated-panels. com) steel profiled plates and steel sandwich panels are mentioned with a granulate on them (Rockwall Coating'). These granulates are applied to the plates by the dry shake technique. Figure 1 illustrates the attachment method in the dry shake technique. The carrier that is to be covered is first given a thick layer of adhesive. Subsequently the dry granulates are sprinkled in abundance over the carrier. After hardening of the adhesive layer the excess granulates, that have not contacted the adhesive layer, are removed from the carrier. This may be effected by sucking them up. Any residue may be removed afterwards with pressurized air or with a high-pressure cleaner. A drawback of this method is that it is not possible to obtain a flat plate at its upper side and simultaneously retain full profiling freedom under the composite layer. The granulate layer will always follow the profiling. In addition, with the dry shake technique the granulates are only attached to the carrier. The granulates do not adhere amongst themselves. The additional strength supplied to the carrier in this way is negligible.

[0007] Patent application WO 02/096824 discloses a non-profiled wall element in the form of a plate shaped covering, that substantially consists of a layer of granulate-shaped particles kept together with a hardened synthetic material. The covering may be provided on an existing support surface. The wall element may also

comprise a (non-profiled) base plate. The structure of covering and base plate is typically not self-supporting : the plate cannot fulfil a carrying support function for a wall; the structure is intended to be attached against a support structure, for example, in or at a framework or against a wall. An important feature of all embodiments of the invention to which WO 02/096824 relates, is that the support surface remains in contact with the ambient air in order to avoid vapour-tension problems.

[0008] Document FR 2686362 relates to a prefabricated cladding for covering an elevator cabin. The cladding comprises a non-profiled support plate made of rigid material covered on one side with a layer of granules of hard material, these granules being agglomerated to each other by means of a curable bonding material. The support plate may be of metal. However, the whole is not self- supporting in the sense that it should be placed against a support structure to give it enough strength.

[0009] Materials that typically are used for covering walls or roofs, like cement fibre boards, plates in natural stone or in artificial natural stone, all need a support structure providing the plates with additional strength. Depending on the material used the support structures can be very expensive, which eventually may result in a very poor installation efficiency. This is for instance the case with natural stone and artificial granite of artificial marble, which all have a high specific weight.

Aims of the invention [0010] The present invention aims to provide profiled metal and synthetic material plates with additional strength, without detracting from the aesthetic

aspect. The invention also aims to provide a method for producing such plates.

Summary of the invention [0011] The present invention relates to'a wall, roof or façade element comprising a profiled element of metal or of synthetic material, said wall, roof or façade element further comprising a covering applied on one surface of said profiled element in metal or in synthetic material, characterized in that said covering is composed of at least a composite layer comprising mutually adhering granulates and in that said covering is flat at one side.

[0012] The profiled element in metal or synthetic material is preferably realized as a single flat plate or a sandwich panel.

[0013] The profiled element is typically realized in steel.

[0014] Preferably the composite layer has a thickness of at least twice the average granulate diameter.

[0015] In an alternate preferable embodiment of the invention the composite layer has a thickness from 1 to 100 mm and preferably from 1 to 30 mm.

[0016] In an advantageous embodiment the profiled element in metal or in synthetic material is a sandwich panel, the heads of which are also clad with said covering.

[0017] In a specific embodiment the composite layer comprises granulates made of a material selected from the group granite, marble, copper, glass, quartz, blue stone, limestone, synthetic material.

[0018] In a second object the invention relates to a method for manufacturing a wall, roof or facade element, comprising the following steps: - providing a profiled element in metal or synthetic material,

- providing the profiled element with a layer of adhesive, - making a mixture of granulates and a resin, - applying the mixture to the profiled, element in a layer, the thickness of which exceeds at least twice that of the average granulate diameter, - compressing the layer onto the profiled element by means of a plate.

[0019] Preferably the resin is W-resistant.

[0020] The mixture is typically applied by means of a funnel or a smoothing plane scraper.

[0021] In a further embodiment, before the step of applying the mixture, the step is performed of providing a boundary element along the side of the profiled element.

[0022] The plate advantageously is resilient. It is preferably at an angle with the plane of the profiled element and attached to a shaft supported by bearings.

Short description of the drawings [0023] Fig. 1 represents the attachment of a composite layer with the dry shake technique.

[0024] Fig. 2 represents several embodiments according to the state of the art: (a) flat sandwich panel, (b) sandwich panel with light profiling, (c) sandwich panel with heavy profiling, (d) flat plate, (e) plate with light profiling, (f) plate with heavy profiling. For the latter three also a cross section is shown.

[0025] Fig. 3 represents the application of the mixture to the plate or panel.

[0026] Fig. 4 represents the step of compressing the layer onto the profiled element.

[0027] Fig. 5 represents a side-view of Fig. 4.

[0028] Fig. 6 represents the attachment of a composite layer without fillers.

[0029] Fig. 7 represents the attachment of a composite layer with fillers.

[0030] Fig. 8 represents (a) flat sandwich panel and compares with two embodiments according to the invention: (b) sandwich panel with light profiling and' (c) sandwich panel with heavy profiling. Fig. 8 (d) represents a flat plate and compares with embodiments according to the invention : (e) plate with light profiling and (f) plate with heavy profiling. For the latter three also a cross section is shown.

Detailed description of the invention [0031] Figure 2 shows a number of embodiments according to the state of the art. As indicated above, a sandwich panel or a flat panel, among others, may be at issue. The figure shows for both cases a realization without profile, with light and with heavy profiling. As the profiling grows heavier, strength increases, but on the other hand the profiling clearly has a negative effect on the esthetic aspect.

[0032] In the invention-additional strength is provided to the plate or to the sandwich panel by applying a profiling and a composite layer on a steel plate or a sandwich panel. Thanks to the added strength, less attachment points are needed according to the span tables.

Very high spans can be realised in this way. The composite layer is more than sufficiently elastic to absorb any tension arising from the mounting of the plate or tension arising due to temperature differences after mounting of the plate. The layer may have a thickness from 1 to 100 mm and preferably from 1 to 30 mm. Consequentially, thanks to the composite layer the steel plate can become more than ten times as thick. The composite layer may be realized in several materials like granite, copper, marble, glass,

quartz, blue stone, limestone, synthetic material,....

Typically the layer is applied in granulate form.

[0033] The carrier that is to be covered is first provided with an adhesive layer that does not necessarily have to be applied thickly. Prior to applying the granulates to the carrier, they are first admixed to a resin. The resin consists of either one or more components.

Preferably an W-resistant resin is used as in most applications the resulting wall or roof elements are exposed to sunlight. Above the carrier (100), being a plate or a (sandwich) panel, is arranged a funnel (1) that is movable over the full length of the plate or panel (see Fig. 3). The funnel (1) is filled with the mixture (2) of granulates and resin. If the funnel (1) is positioned e. g.

15 mm higher than the upper side of the carrier (100), the mixture (2) will be spread over the carrier in a 15 mm layer when the carrier is moved. At this stage the layer is not compact yet. In an alternative embodiment the funnel can be substituted by a smoothing plane scraper that pushes the mixture ahead and leaves behind a layer of a certain thickness. Preferably a longitudinal boundary element (6) is used along the side of the carrier in order to keep the mixture on the carrier. Alternatively the funnel stands still and the carrier is moved in longitudinal direction, which of course yields the same result. A combination of both approaches (both funnel and carrier moving) is possible as well. The height at which the funnel or smoothing plane scraper is to be placed depends on the average granulate thickness.

[0034] After applying the mixture (2) to the carrier (100) the mixture is compressed by means of a preferably resilient plate (3) positioned at an angle with the carrier plane (see Fig. 4 and Fig. 5). The resilient plate (3) is movable in the longitudinal direction of the carrier (100).

As in the previous step the resilient plate (3) can stand still and the carrier can be moving instead. The finishing of the panel or plate is determined by the angle (5) between the resilient plate and the panel or plate (see Fig. 5) and by the pressure the resilient plate'exerts. This pressure is preferably exerted by attaching the resilient plate to a shaft (4) supported by bearings. The shaft (4) can then be turned towards the surface of the panel or plate. The height of the shaft (4) compared to the panel or plate is determined by the angle (5). The mixture (2) will be compressed and the granulates will be oriented more or less parallel to the visible surface. This allows to obtain a flat covering. This means that the top surface of the covering is essentially parallel to the plane of the profiled element. The surface of the covering does not follow the profiles of the element.

[0035] The resulting whole of carrier with a granulate layer is much stronger than a carrier covered by the above mentioned dry shake technique. The granulates are such that the smallest grains are big enough to retain an open space between the granulates after compacting of the layer. This has the advantage that the specific weight can be kept limited with respect to an embodiment with a composite layer with fillers. Fig. 6 shows an embodiment where the composite layer is attached without fillers. In a composite layer with fillers (see Fig. 7) the pores between the granulates are filled with very fine fillers so that the latter is substantially waterproof. Of course the whole of carrier + granulate layer is heavier than a carrier with a layer without fillers. An example of a composite layer with fillers is"artificial granite"or"artificial marble".

[00361 Thanks to the profiling the steel plate or the sandwich panel possesses a kind of built-in structure.

Therefore it can immediately be placed against the steel or concrete structure of the carcass of the building, which yields an enormous gain in installation efficiency and in weight. A further gain in installation efficiency is obtained with the steel sandwich panels provided with a composite layer according to the present invention, when the panel's heads are covered with said composite layer as well. This yields the additional advantage that the finishing of both windows and doors and that of the building's corners does not have to be performed at the building site. When working with uncovered sandwich panels one still has to apply corner profiles after having installed the sandwich panels, which takes considerably more time.

[0037] Apart from the extra strength which is provided to the profiled metal element, the biggest advantage of the invention is that under the composite layer a metal element with any profiling can be used.

Thanks to the composite layer the aesthetic effect of the panel is always retained. The result is an essentially flat panel, which is the most interesting form from a commercial point of view. With essentially flat is meant that some light unevenness may occur. One may proceed with a maximum number of profilings and with a maximum depth of the profilings, thus giving the wall, roof or façade element maximal strength without their external aspect esthetically changing.

[0038] When using a composite layer of natural stone the layer can be calibrated and polished, thus obtaining artificial granite or artificial marble. This implies these panels in artificial granite or artificial marble do not need any additional support structure. The panels can be as long as 10 m, whereas the plates in other materials that

are commonly applied for cladding walls have a maximum length of 3 m.

[0039] In Figure 8 several embodiments according to the invention are shown, both for some flat plates and sandwich panels. The examples illustrate again that whatever the used profiling, a substantially flat surface is retained at the upper side.

[0040] A wall being clad with artificial stone only has an aestethic function. One still needs a separate outer wall, provided with a support structure for holding the panels. Also the isolation has to be provided separately.

When using the steel sandwich panel of this invention no separate outer wall, isolation or extra support structure is required anymore.

[0041] It is pointed out that reinforcing the steel plate or a steel sandwich panel by means of applying a composite layer, as described above, may also be applied if an element with for example a curved form is at issue.

[0042] These wall, roof of façade elements can primarily find application in the market of industrial construction, but thanks to the aesthetic advantages resulting from the invention they become applicable in house-construction.