SANDWICH ELEMENT FOR LIGHT CONSTRUCTIONS, IN PARTICULAR FOR BUILDING PURPOSES, AND METHOD FOR MANUFACTURING SAME

Abstract: A method for producing a sandwich panel (1) for light structures, especially for building purposes, consisting of an insulating core (2) of a mineral wool board having monodirectional fibres oriented transverse to the extent of the board, covered on each side with a reinforced, impervious outer layer (3), wherein the core (2) is convected to the outer layer (3) in that the fibres of the core (2) at the ends thereof which face towards the outer layer (3) are enveloped by the mass of the outer layer (3).

Description: SANDWICH ELEMENT FOR LIGHT CONSTRUCTIONS, IN PARTICULAR FOR BUILDING PURPOSES, AND METHOD FOR MANUFACTURING SAME, The present invention relates to a sandwich panel for light structures, especially for building purposes, consisting of an insulating core covered on each side by a reinforced, resistant plastic layer, as is disclosed in the preamble in 10 independent claim 1 below. The invention also relates to a method for producing same according to the preamble in claim 3. DE-33 15 901 and DE 35 13 918 make known a self-supporting 15 panel comprising at least two outer layers and an inner layer, which inner layer consists of a mineral wool board and where the outer layers may consist of sheets of, e.g., a glass-fibre reinforced magnesium cement suspension. The mineral wool board is affixed to the outer layers by means of an adhesive 20 and the fibres thereof are substantially at right angles to the outer layers. The objective of the present invention is to provide a sandwich panel based on the state of the art, but where the 25 insulating core exhibits great mechanical resistance to compression transverse to the sandwich panel, is highly resistant to damp and rot, and at the same time is considerably cheaper and more efficient to manufacture. 30 According to the present invention, this is achieved with the aid of the features which are disclosed in the characterising clause of independent device claim 1 and the characterising clause of independent method claim 3 hereinbelow. 35 Thus, a sandwich panel is produced which is highly resistant to compression and bending forces, and where as the core a mineral wool board is used that has mono-directional fibres oriented transverse to the extent of the sheet, and where furthermore outer layers and core are joined to each other in that the material of the outer layer is melted around the fibres of the core layer at the ends thereof. The plastic layers may to advantage consist of polyester sheets bonded to the core 2 without the use of a bonding agent other than the polyester sheet itself. To join the aforementioned sandwich panels, a profile is provided which is discussed in detail in the Applicant's previous Norwegian Patent Application No. P930533. By means of said sandwich panel and profile for joining such sandwich panels, structures of varying sizes can be erected in a very quick and easy manner, especially building structures of very different design forms, and which, because of the said bonding/welding of profiles and sandwich panels to one another by means of an appropriate bonding agent, will be highly resistant to mechanical stress such as, e.g., tremors in connection with earthquakes. Thus, smaller buildings, such as houses or huts, will stand being knocked off their foundation walls or other substructure without sustaining damage, and can thereafter be hoisted or jacked into place. The invention will now be described in more detail with reference to the embodiments of sandwich panels and method steps for the manufacture thereof respectively, which are schematically illustrated in the drawings. Figure 1 is a perspective view of a part of a sandwich panel wherein the different layers and bonding zones are disclosed. Figures 2 to 7 illustrate the manufacture of the panel in steps, wherein: Figure 2 illustrates the outer layer lying on a conveyor belt; Figure 3 illustrates the supply of core members; Figure 4 shows a detail of the sandwich panel at this point in its manufacture; Figure 5 shows the cutting of the panel; Figure 6 is a illustration of the panel immediately prior to it being brought together with the second outer layer; Figure 7 shows a section of the completed panel. Figure 8 illustrates the production of mineral wool strips, and Figure 9 shows how the mineral wool strips are positioned in order to form a wide sanwich panel, seen from above. Figure 10 is a schematic illustration of how the individual fibres are anchored in the outer layer, and Figure 11 shows two sandwich panels, each with its profile mounted in place for joining said panels. Figure 1 illustrates a sandwich panel 1 consisting of an insulating core 2 covered on each side with a reinforced impervious plastic layer 3. The core 2 comprises a mineral wool board having mono-directional fibres oriented transverse to the extent of the board. The outer layers 3,3 and the core 2 are joined to one another in that the outer layers are set around the fibre ends of the core layer in the zone 4, 4. It would be expedient for the plastic layers 3, 3 to consist of polyester sheets. The mineral wool board constituting the core 2 is made of strips 8 cut out of a mineral wool board 9 having a fibre direction extending in the longitudinal direction (Figure 8) . The thickness t of the strips 8 defines the thickness of the core layer 2, whilst the thickness of the mineral wool board 9 defines the width w of the strips. Several strips 8 may be assembled in order to form a sandwich panel of a greater width W (Figure 9) . By bonding the outer layers and the core layer together without the use of a special bonding agent, a simple and rapid production of the sandwich panel will be achieved. The panel is extremely well-suited for mass production and can be manufactured continuously. During production, a layer 3 of liquid or plastic polyester is placed on a conveyor belt 5 which may be of steel or another material having good release properties towards polyester. The conveyor belt may be coated with teflon to further enhance the release properties thereof. The outer layer may be from 4 to 10 mm thick. The outer layer 3 is conducted in a liquid or plastic state to a station for the application of core layer members 2. The core layer members 2 are conducted downwards on an inclined plane 6 which is located above the conveyor belt 5 carrying the liquid outer layer. The core layer members 2 are placed very close to one another on top of the outer layer 3 and the outer layer material penetrates between the fibres in the core layer material and envelops the lowermost ends of the fibres. As shown in Figure 4, the penetration of the outer layer material is about 1 mm, but the penetration may also be as little as 0.5 mm. This depth of penetration constitutes the bonding zone 4. In Figure 10 this anchoring is illustrated schematically and is greatly enlarged. This is the ideal case where the fibres in the fibrous member 2 are exactly at right angles to the outer layer 3 and where all the individual fibres are anchored at the predetermined depth 4 in the outer layer. In reality, this ideal state is virtually impossible to achieve, as the fibres will as a rule be somewhat bent and not all the fibres will be anchored in the outer layer. If the net weight of the core layer member 2 is not sufficient to enable it to penetrate to the necessary depth in the outer layer 3, it is possible to apply an additional compressive force from above with the aid of appropriate means . The half-finished sandwich product is then transported to a cutting station whilst the polyester sets. As soon as the polyester has set the sandwich panel is cut into suitable lengths by means of, e.g., a cutting knife 7 (Figure 5) . The half-finished sandwich panels are then turned 180° about their horizontal axis, e.g., by means of vacuum lifting devices (Figure 6) . Thereafter, the half-finished sandwich panels are conducted towards a further outer layer 3 which is also in a liquid or plastic state on a conveyor belt. The setting and cutting steps are repeated in the same way as described above. The result is finished sandwich panels in accordance with those described above. The method of production is highly economical both in terms of the number of process steps and material consumption. There is no need for any adhesive, and both the adhesive consumption and process steps this would have involved are thus omitted from production. By virtue of the fact that the outer layer is attached directly to the core layer, there is no danger of the core layer and the outer layer becoming detached from one another in the same way as if they had been glued together. The sandwich panel will therefore be highly reliable in use and will be capable of withstanding greater stress than similar panels where the outer layer is glued to the core layer. A desired number of sandwich panels can be assembled side edge to side edge with the aid of the profiles described in Norwegian Patent Application No. P930533, thereby forming a wall in a building structure. Openings can be cut as desired at chosen points in the wall of the sandwich panel 1 for windows and doors respectively, wherein there may be mounted respectively window frames and door frames for windows and doors. By using the sandwich panels described above, one can in a fast and simple manner produce building structures which will be highly resistant to both impact stress and tremors, and will largely maintain their form during intense mechanical stress produced by earthquakes and wind stress respectively, and also to a certain extent stress caused by landslides. The sandwich panels described above can be packed in transportable units, together with the window and door structures required, to be transported to disaster areas for the rapid erection of both temporary and permanent buildings. The sandwich panels according to the invention will also be highly suited for taking on expeditions to, e.g., the polar regions where buildings are to be erected for staff and equipment. The invention may thus be used under extremely different conditions such as under both arctic and tropical conditions. The strength and the insulating properties can be controlled by means of the thickness of the outer layer 3 and the net weight of the mineral wool board, and also because the thickness of the mineral wool board will determine the heat insulating power of the sandwich panel. Figure 11 illustrates an example of a profile 10 especially designed for joining sandwich elements 1 together to form a building structure. The profile 10 is mounted on the end edge of the sandwich panel by means of, e.g., a suitable bonding agent, or optionally by means of assembly with the outer layers at the same time as the core layer member is joined thereto. On the outward facing surface 11 thereof contours are made which form guides and locking devices, and also allow for the injection of a bonding agent. During the joining process, guiding is facilitated by means of a groove 12 and spring 13. When the profiles are joined together, these can be locked to each other in that a locking batten 14 is driven into a dovetail slot 15. Should a more solid and permanent connection be required, a bonding agent can be injected into channels 16 in that a flexible tube (not illustrated) for feeding bonding agent is inserted into the channels 16. The locking batten 14 leaves a space 17 in the dovetail slot 15. A bonding agent may also optionally be injected herein.

Claims: P a t e n t c l a i m s 1. A sandwich panel (1) for light structures, especially for building purposes, consisting of an insulating core (2) of a mineral wool board having mono-directional fibres oriented transverse to the extent of the board, covered on each side with a reinforced, resistant outer layer (3) , characterised in that the core (2) is connected to the outer layer (3) in that the fibres of the core (2) at the ends thereof which face towards the outer layer (3) are enveloped by the mass of the outer layer (3) . 2. A sandwich panel according to Claim 1, characterised in that the plastic layers (3,3) consist of polyester sheets. 3. A sandwich panel according to Claim 1 or 2, characterised in that the panel at one or more of the end edges thereof is equipped with profiles for joining said panel together with other sandwich panels or other building components, said profiles in the latitudinal direction extend at least from one outer layer to another, and comprise at least one locking slot to allow adjacent profiles to be locked to one another. 4. A sandwich panel according to Claim 3, characterised in that the locking slot is an undercut slot and that a locking batten adapted to this slot is used to form the locking connection. 5. A sandwich panel according to Claim 3, characterised in that the profile is equipped with a groove and spring to facilitate the correct joining of the profiles, and that it is equipped with channels for the injection of a bonding agent after the profiles have been joined. 6. A method for producing a sandwich panel (1) for light structures, especially for building purposes, consisting of an insulating core (2) of a mineral wool board having mono¬ directional fibres oriented transverse to the extent of the board, covered on each side with a reinforced, resistant outer layer (3) , characterised in that the outer layer is made from a liquid or plastic state, that the core (2) is brought into contact with the outer layer (3) before said outer layer sets, in such a way that the fibres of the core (2) at the ends thereof which face towards the outer layer (3) are thus enveloped by the mass of the outer layer (3) , such that once said outer layer (3) has set the core (2) is permanently joined to the outer layer (3) . 7. The method according to Claim 6, characterised in that the outer layer (3) is made of liquid or plastic polyester. 8. The method according to Claims 6 - 7, characterised in that the mass which forms the outer layer (3) is fed into a horizontally located mould having an open upper side, and that the material which forms the core is thereafter placed on top of the liquid or plastic outer layer (3) , whereupon the outer layer is allowed to set, the half-finished sandwich panel (1) is turned and the process is repeated for the casting of the outer layer on the other side of the core (2) . 9 . The method according to Claim 8, characterised in that the mould comprises a conveyor belt consisting of a material with good release properties towards the material in the outer layer, e.g., teflon, steel and others. 10. The method according to Claims 8 - 9, characterised in that the core material is conducted towards the outer layer on an inclined plane which is located above the mould for the outer layer.

Inventors: HANSEN JAN HOLM, HANSEN, JAN, HOLM
Applicants: HANSEN JAN HOLM, HANSEN, JAN, HOLM
Application year: 1995
Main classification: E04C2
IPC codes: E04B1, E04C2