FR2610437A1 - Magnetic sandwich panels - Google Patents

Abstract

The present invention relates to sandwich panels in which one side (or both sides) is made magnetic either by interposing a magnetic layer 12 under a non-magnetic skin 10, or by magnetization of a normally non-magnetic skin. These panels may be used, preferably, as lettering and/or display panels or as decorative and magnetic separation partitions. The other face, totally independent of the first, may be constituted by a projection screen, a drawing or a decorative image.

Description

 The object of the present invention is. as a new industrial product, magnetic sandwich panels, flat or curved, essentially used as a writing board and (out) display.

 Currently there are three families on the market on the market: the first is the most versatile and consists of tables: in enamelled or lacquered steel (therefore magnetic) serving both as magnetic display boards and as whiteboards. writing. the second is made up of writing tables: the writing surface of which is made up of non-magnetic products but well suited to the various writing means existing on the market, the third family is made up of tables: display whose display surface is made up of tackable products (cork, etc.). There are no very light paintings on the market, possibly including accessories integrated in their thickness and greater versatility than paintings from the first family.

 The present invention aims to allow the production of sandwich panels having one or two magnetic, light faces, which may include accessories integrated in their thickness essentially usable as writing and / or display boards. . Two cases can arise, that is, the external surface of tr-avail is constituted by a non-metallic and capable product, trace to an underlayer metal league. to hold a magnet pressed against it. or the external working surface is made up of a normally non-magnetic product which may be magnetized by the integration of particles or wire mesh during its production.

 The invention will be better understood thanks to the appended diagrammatic drawings given by way of nonlimiting examples.

 Beforehand, a sandwich panel and its main characteristics will be defined: FIGS. 1 to 7 relate more particularly to: sandwich panels in general, FIGS. B to 16 more particularly illustrate the invention.

Figure 1 shows the section of a sandwich panel;
FIG. r schematically represents the elevation view of a sandwich panel (from which a shell has been removed) comprising a pipe or a cable embedded in the core;
Figure 3 shows section AA of Figure 2. it shows the principle of embedding a pipe or cable;
FIG. 4 represents the elevation view of a sandwich panel (from which a skin has been removed) comprising an invisible accessory embedded in the core;
5 shows the section AA of Figure 4. it shows the principle of embedding an invisible accessory;
FIG. 6 represents the elevation view of a sandwich panel comprising an accessory visible from the outside and partially embedded in the panel;
FIG. 7 represents the section AA of FIG. 6, it shows the principle of embedding of an accessory visible from the outside and partially embedded. "
FIG. 8 represents the section of a magnetic sandwich panel comprising a thin metallic film placed between the core and the external working surface;
Figure 9 shows the elevational view of a piece of a wire mesh;
FIG. 10 represents the section of a magnetic sandwich panel comprising a wire mesh placed between the core and the external working skin:
FIG. 11 represents the elevation view of a sandwich panel (of which a skin has been removed) comprising two local inserts usable as solid attachment points;
FIG. 12 represents the elevation view of a sandwich panel (from which a skin has been removed) and comprising an insert completely covering one side of the panel and making it possible to securely fix the latter to a vertical axis of rotation:
FIG. 1 represents the elevation view of a sandwich panel comprising two accessories allowing the solid fi at i on of a lighting system on the table;
FIG. 14 represents the colitis AA of FIG. 13 and shows the principle of installation of the fixing accessories;
FIG. 15 represents the elevation view of a sandwich panel (from which a skin has been removed) comprising, embedded in its thickness, grooves housing an electric cable and accessories such as sockets and electrical switches:
FIG. 16 represents the section AA of FIG. 15 and shows the principle of embedding of the sockets and switches
The principle of the sandwich panel is represented in FIG. 1, a reference core, preferably light, makes it possible to maintain constant the spacing of two working skin marks 1 and
The 2 skin>: are attached to the core by bonding (bonding planes represented according to references 4) or by direct stratification of a resin reinforced with glass fibers or the like. The whole core, skin and bonding planes constitutes the sandwich panel, each of the constituent elements has first a structural role. The skin placed on the side of the load works in compression, the other skin works in traction ; they must have mechanical characteristics and a thickness sufficient to withstand the mechanical stresses to which they are subjected.

 The friend working mainly in shear must be sufficiently efficient to resist the mechanical stresses to which she is subjected. The bonding planes must ensure the most perfect cohesion between the skins and the core.

A wooden board, for example, whose 2 sides would be lined does not constitute a sandwich panel: bl err that ld constitution appears identical, the coverings and the plans of collage have no structural role but only a decorative role, all -. the efforts are taken up by the wooden board.

 The essential interest of the panel compared to the monolithic plate is justified as explained below. The maximum bending stresses in a sandwich or other panel appear in the extreme fibers, compression (sign +) on the side where the tensile load is applied (sign -) on the other side, the intermediate fibers are less stressed and the neutral fiber, zobne border ol: the sign change constraints are not subject to any constraints. In traditional monolithic construction all the panel fibers are made of the same material, the result is a heavy and oversized construction except for the extreme fibers. The use of the sandwich technique allows, in some way, to select the materials according of the amplitude and the nature of the soil ii citations which they will undergo, the skins taking up most of the traction and compression forces must be mechanically sufficiently efficient, consequently the soul, imbibed with this spot, can be constituted by a mechanically mater much less efficient than the material :: constituting the skins; It is above all requested to take up shear forces: many light materials, possibly excellent thermal insulators which can perfectly fulfill this role; the rigidity of a sandwich panel being proportional to the square of the thickness of the core, it suffices to choose its thickness accordingly.

 A sandwich panel combines the main characteristics of lightness and rigidity.

 Lightness: A so-called light core weighs, generally, between 30 and 100 kg / m, a sandwich panel usually weighs between 15O and 450 Kg / m essentially function of the relative thickness of the core compared to A 'to' total thickness . The sandwich construction is therefore a very light construction.

 Rigidity: By way of example, a sandwich panel made up of 2 aluminum skins one millimeter thick and one core 15 mm thick has a rigidity in bending close to that of a calacue of 10 mm thick aluminum. Doubling the thickness of the core quadruples the rigidity of the panel; this technique makes it possible to obtain extremely rigid panels and the maintenance over time of this rigidity, a flat panel remains flat and does not curl over time, a curved panel retains its ravon of curvature over time.

 Rigidity / Weight: As an example, the sandwich panel described above weighs around 7 kg / m, the monolithic aluminum plate of 10 mm weighs 27 kg / m. This extremely high stiffness / weight ratio is, for many applications. very favorable to the sandwi ch.

In addition to the basic characteristics described above, the sandwich panel offers the following other important characteristics:
Thermal insulation: The core can consist of the best thermal insulators available on the market, (whose thermal conductivity coefficient is close to O. 025
W / m C) provided that they have a minimum of mechanical performance; therefore a sandwich panel can be an excellent thermal insulation panel. If thermal insulation is not required, the thermal insulation used as a core brings lightness anyway, 1 ability to embed very easily accessories or pipes and thermal insulation because this does not add any additional cost and is rarely a bold case
Fitness for mrse in shape: Thin skins are always naturally capable of adopting a radius of curvature mi or matm, various techniques adapted to the products make it possible to descend below this minimum natural radius of curvature; several techniques make it possible to give the different materials used as a core the desired radius of curvature; the bonding of these preformed elements makes it possible to obtain a curved sandwich panel.

 Integrated decoration: The choice of skins is very wide; cardboard, plywood, wood veneer of any kind, prepainted or anodized aluminum, prepainted steel, stainless steel, melamine, polyester, pvc The result is an almost infinite ability to decorate. this yes represents a considerable advantage for all applications where the two sides of the panel are placed in a different environment and all the applications where one face has only a structural role (in this case the aesthetic role of the skin is secondary); with a monolithic plate the choice of the base material is always imposed by 1 most unfavorable environment; of olus this material must almost always be aesthetic and of a reasonable cost this yes limits the choice.

 Rot-proofing: It only depends on the choice of skin and core, for example a sandwich panel made of polvester skins and a core of cellular PVC does not require any maintenance and is completely rot-proof. Any sandwich panel using rot-proof elements is rot-proof.

 Waterproofing: A sandwich panel consists of independent elements (2 skins +1 core) and 2 bonding planes, by playing on these 5 elements, it is always possible to make a waterproof panel, for example the panel described here the top is completely waterproof. Any panel using an impermeable element at the center is impermeable.

 Impact resistance: It depends on the choice of skin: -: matt may be even more on the choice of the core, certain materials transmit impact energy from the upstream skin <side of the impact-- ) towards the downstream skin without absorption or distribution of energy, other products absorb part of the energy and distributed correctly feels the energy not absorbed by interesting a larger surface than that subjected to the impact, these products are best suited for the production of sandwich panels likely to be subjected to impacts.

 Fire classification I1 is almost always possible by playing on the choice of the constituent elements of making panels: sandwiches satisfying the requirements of fire regulations.

Integration of accessories and pipes in the thickness of a sandwich panel case are to be considered
Case 1: pipes hidden from view: Figures 2 represent a pipe or a recessed cable, the core, at the latest before lai lape of the second skin, is grooved according to the desired path of the pipe or cable, the edge thus produced is shown according to item 5, the pipe or cable item 6 is then installed in the trench, optionally the space available between the trench and the pipe or cable can be filled with glue or any other resurfacing product .The pipe reference 6 may have a circular section or not, be full or hollow; the trench mark 5 can have any profile. The realization of a trench in a soft material is an extremely easy and fast operation and does not weaken or very little weakens the resistance of the panel because the friend always plays its main role which is to maintain constant the spacing of the skin> :.

 Case 2: Accessories hidden from view: Figures 4 and 5 represent a reference accessory 7, completely embedded in the thickness of the core of the sandwich panel, the embodiment of a sandwich panel requires that these accessories be installed during of the construction of the sandwich panel, the friend must be cut to allow the best possible adjustment of the accessories and it is not possible to add this after construction of the panel. These accessories can play many roles, for example and that is not limiting: it can be a local reinforcement allowing, by screwing OR nailing. attaching an accessory to the outside of the sandwich panel: this can be a magnet to keep a door closed.

They can have any shape and occupy all or part of the thickness of the core. These accessories will be called inserts in the following description.

 Case 3 Partially or fully embedded accessories not completely hidden from view: Figures 6 and 7 show a reference accessory 9, partially embedded in a reference cavity 8 hollowed out in the thickness of the friend. and opening outwards by cutting the skin: these accessories can have many roles, for example and this is not limiting, it can be a clock, a temperature indicator ... Unlike the inserts the choice their location can be done after or during the realization of the sandwich panel, however if they must be connected to one or more pipes (containing for example an information transmission cable) it is preferable to position them before realization of the panel .

 According to the invention, five main techniques can be used to make a face of a sandwich panel magnetic, the external working skin of which is not magnetic (excluding the simplest solution which consists in using a metallic skin). the first technique a metallic thin film reference 11 continuous or not, is interposed between the friend reference 3 and the non-magnetic skin reference 1C), this technique is represented according to FIG. 8, a metallic film whose thickness is a few tens or hundreds of microns is perfectly suitable. According to the second technique, a wire mesh reference 12 similar to that shown in FIG. 9 having a sufficiently tight mesh is interposed between the core reference 3 and the skin reference 10, this principle is illustrated according to FIG. 10; unlike the thin metallic film glued to the core, the metal mesh is, under the effect of the pressure exerted during the construction of the sandwich panel, embedded in the thickness of the soft friend. According to the third technique, the glue used for make the reference bonding plane 4, located on the side of the face to be magnetized, is added with metallic particles of any shape whose particle size ranges from a few tens of microns to a few millimeters, the homogenized assembly makes it possible to constitute a plan of magnetic bonding continuous or not. According to the fourth techioe the surface of the friend is covered, as regularly as possible with metallic particles (powder, chip ::, flakes ...), the only constraint being that these particles are thin and laid flat, then the skin mark 10 is glued to the assembly The pressure exerted during the production of the panel embeds the particles in the soft friend allowing the skin mark 10 to be r a flat outer surface. Contrary to the first four techniques Where the magnetization of the faces is obtained by interposing metallic elements under a non-magical working skin reference 10, the fifth technique consists in magnetizing the reference skin 10 normally non-magnetic, two methods can be used; according to the first method, the skin is produced either by direct stratification of a resin (polyester, epoxy, etc.) added with metal particles (using a method similar to that described according to the third technique), or by pouring the resin on the friend previously covered with metal particles and / or with a wire mesh (using a method similar to that described according to the second and third techniques) 5 according to the second method it is possible to produce skins industrially ( pvc, impact polystyrene, polyester ...) of which all or part of the thickness is magnetized and then sticking this skin on the friend The different techniques described above can be combined with each other when making a magnetic sandwich panel , for example techniques 3 and 4 can be associated for the realization of a magnetic face, the third technique can be easily associated with the second technique, two different techniques Entes can be used to magnetize two faces of the same sandwich panel ... In addition, without departing from the scope of the invention, the reference skin 10 can be mono or multilayer.

 In accordance with the invention, the reference skin 1, located on the side opposite the magnetic side, may be either coated (if it is multilayer), or formed (if it is monolayer) by a cinema projection screen film (or slides) or a photo or decorative image; this allows, in a few seconds, by simply inverting the panel to have at its disposal a magnetic writing and / or display table or a projection screen.

 According to the invention and, as shown more particularly in Figures 11 and 12 of the accompanying drawings, inserts can be placed in the thickness of the panel; the marker inserts t: offer solid local attachment points to accessories allowing, for example, to securely hang such a panel on a wall, the insert marker 14 allows the hanging of a panel on a vertical axis of rotation of course without departing from the scope of the invention it is possible to fulfill the hooking functions with discontinuous local inserts (mark 13) or continuous inserts (mark 14). In accordance with the invention and as shown more particularly in FIGS. 13 and 14 of the appended drawings, it is possible to install mark inserts 15 allowing the fixing on the table of the articulated arms supporting the lighting of the panel. These inserts can be installed according to three main techniques, according to the first technique (figures 13 and t4) a traditional insert (similar to inserts 13 and 14) is placed in the thickness of the panel, after completion of the panel it is pierced and fitted a female screw or bayonet socket on which the lighting support arm is screwed or locked; according to) a second technique no insert is previously installed, the finished panel is pierced and stinky case of two pieces connecting sol i dly one on 1 another and resting firmly on 1 es two skins; according to the third technique it is possible to use special accessories, existing on the market and fi fi securely on soft material The first two techniques can allow to fix indifferently the lighting supcirts on any of the two sides of the panel, If the accessories item 15 are accessible by the edges of the panel, nothing is visible to the eye of an observer.

 In accordance with the invention and, as shown more particularly in FIGS. 15 and 16, the reference core 3 can be grooved according to the principle shown according to FIG. 2, in these reference grooves 16 are installed either a hose containing an electric cable supplying one (or more) electrical outlet item 17, a switch item 18 is used to control the power supply to the switchboard, item 19 represents a female electrical outlet placed on the edge of the panel; this socket is connected to the sector by means of a traditional electric cable, after installation of the lighting support arms by fixing in the accessories mark 15, the power supply cabs are connected to the mark sockets 17, these accessories marks 17, 18 and 19 are preferably installed before the panel is produced by local cutting of the core. As a variant, this panel can be supplied like household appliances with an electrical feeder, which can optionally be stored in a hollow cavity in the panel and accessible by the edge. If the electrical supply outlet (s) item 17 opens out by the skin referenced 1, the power cable for the panel can be completely hidden from view by an observer; if, in addition, the reference connector 15 allows, at the same time, to ensure the mechanical and electrical connection functions, the panel can be lit without any electric cable being visible. Alternatively, it is possible to produce panels with an electric circuit hidden from view without having foreseen it at the time of production; it is sufficient, after completion of the panel to cut it to the required dimensions and to groove the edges to accommodate the electric cables there, in this case it is preferable to provide mark accessories 15 accessible by the edge, after completion of the long electrical cones a frame is attached to the perimeter of the table to hide from view the unsightly edges of the sandwich panel.

 The most interesting markets for the magnetic sandwich panels object of the scient invention: the Turkish screen and / or magnetic display board and the partitions; removable magneti pues of landscaped offices, the major interests of the invention are to provide an external work surface perfectly suited to the end use or decorative, this normally non-magnetic external surface is either magnetized by interposition of a magnetic under layer, that is to say magnetise-during its realization, in addition to this essential advantage) the technique used brings lightness the possibility of embedding in the thickness of the panel all kinds of accessories and pipes: the two sides of the panel being absolutely independent it is possible to fully use the other side by transforming it into a projection screen cinema, in a decorative painting or quite ... simply in another writing and / or magnetic display board or not.

 In the building, under renovation or new, if thermal insulation is brought in from the inside, the panels which are the subject of the invention make it possible to provide thermal insulation, a magnetic surface and, possibly, decoration in these cases. skin item 1 is not necessary, it can be replaced by the wall on which the panel is attached. Without departing from the scope of the invention, it is quite possible for other applications to produce half sandwich panels (without the skin item 1) which will be brought back, by the end user, to any medium at his convenience. .

Claims (9)

 1) Magnetic sandwich panels, flat or curved, characterized in that they consist of a light core (3) and two skins (1, 10) compatible with the ambient environment and the final bed of which, at minus, ure of both sides aci. t magnetic; the magnetization of the magnetic face is obtained either by interposition of a metallic element, continuous or not, between the non-magnetic outer skin (10) and the core (3), or by magnetizing all or part of the skin (10) normally non-magnetic; the said skins (1, 10) being able to be monolayer or multilayer and being of minimum resistance for resisting to the sol li mechanical limitations undergone by the panel.  2) magnetic sandwich panels, according to claim 1, characterized in that the magnetization of a face can be obtained by interposing a film rr, étal l i c? Ue continuous on nuri (11); he said f i lin metal 1 i that having characteristics adapted to obtain sufficient magnetization of the finished product.  3) magnetic sandwishes panels, according to claim 1, characterized in that the magnetization of a face can be obtained by interposing a frame i i is metal 1 i that (12) between 1 '(3) and the skin (10); said metal mesh having characteristics suitable for obtaining sufficient magnetization of the finished product.  4) Magnetic sandwich panels, according to claim 1, characterized in that the magnetization of a face can be obtained thanks to a gluing plane (4) made magnetic by incorporation of metallic particles in the glue; the dimensions and the geometry of said particles being adapted to obtaining sufficient magnetization of the finished product.  5) Magnetic sandwich panel according to claim 1, characterized in that the magnetization of a face can be obtained by interposing between the core (13) and the skin (10) a carpet, continuous or not, of metallic particles partially or tota-. Lely embedded in the bonding plane (4); the dimensions and the geometry of said particles being adapted to obtaining sufficient magnetization of the finished product.  6) Magnetic sandwich panels, according to claim 1, characterized in that the working skin (10), normally non-magnetic, is magnetized, in all or part of its thickness, by incorporation of metallic particles: said particles being introduced during of the production of the skin and / or of the sandwich panel, the dimensions and the geometry of said particles being adapted to obtaining a sufficient magnetization of the finished product.  7) Magnetic sandwich panels, according to one of the above claims, characterized in that the core (3) comprises a plurality of grooves (16), allowing the accommodation of electrical cables and (or) one or more cavities receiving diveers control devices (18), local reinforcements (13, 14) or others (17, 19).  89 Magnetic sandwich panels according to any one of the above claims, characterized in that the core (3) consists of a thermal insulating product.  9) Magnetic sandwich panel according to any one of the above claims, characterized in that a skin or a part thereof consists of a product fulfilling the role of projection screen.  10) Magnetic panels, salt on which one conch dEC claims above, whose skin (1) located on the side opposite to the magnetic element has been removed.