Abstract:
A longitudinal laminate board of mineral wool and method of making the board are disclosed. The laminate board consists of adjacently disposed pieces at least some of which are shorter than the length of the board and whose fibre plane form an essentially right angle to the plane of the laminate board. The pieces are jointed within the laminate board.

Description:
FIELD OF THE INVENTION 
     The invention relates to a construction board, in particular to a longitudinal laminate board of mineral wool, which is appropriate as a core of a sandwich element having a surface layer e.g. of sheet metal on each side. The laminate board consists of adjacently disposed rods, whose fibre plane forms essentially a right angle to that of the laminate board and at least a number of the rods being shorter than the laminate board. 
     The invention also relates to a method for manufacturing the laminate board, in which rods are cut out from a mineral wool sheet with a length different from the one of the laminate board, are rotated 90° about their longitudinal axes and are assembled into a laminate board. 
     BACKGROUND OF THE INVENTION 
     Laminate boards of this type are prior known and have been implemented for instance in naval industry as insulating walls of various spaces. 
     Sandwich elements of mineral wool have been utilized to some extent in naval industry. So far long supporting elements have not however, been available, neither as ceiling, floor nor wall elements. 
     Finished sandwich elements of mineral wool with the fibres oriented perpendicularly to the surface plane of the element would, owing to its resistance properties, be usable as supporting roof, floor and wall elements and would thus simplify building operations greatly. 
     SUMMARY OF THE INVENTION 
     The object of the present invention is thus to provide longitudinal laminate boards usable as a core of supporting sandwich elements for roof, floor and wall constructions as well as a method for manufacturing such laminate boards. 
     According to the invention, this object has been achieved by matching the opposite end surfaces of two aligned rods and connecting them and further by providing a method in which the rods are assembled with end surfaces facing into longitudinal rods, from which rods equalling the length of the laminate boards are cut off and connected laterally to form the laminate board. 
     Thus, the laminate board of the invention is longitudinal, it is made of binder fixed mineral wool and is appropriate for use as a core of a sandwich element, whereby it is combined with surface layers, of sheet metal for instance, on each side. The laminate core is formed of adjacent rods whose fibre plane is perpendicularly oriented to the plane of the laminate board and at least a number of the rods being shorter than the laminate board. According to the invention, the opposite end surfaces of two aligned rods are matched and interconnected. At least some of the rods being shorter than the laminate board, such rods consist of jointed rods. In this case it is essential that the end surface be connected so that the resistance of the laminate board is not deteriorated. 
     According to a preferred embodiment of the laminate board, the end surfaces are glued against each other. According to another embodiment, the end surfaces are pressed against each other forming border layer in which fibres from both surfaces are in contact with each other, engaging into each other. 
     According to a preferred embodiment, the matching end surfaces can be inclined so as not to form a right angle to the longitudinal axis of the rods. According to a further developed embodiment, the end surfaces form a right angle to the plane of the laminate board, being simultaneously and preferably tilted towards the longitudinal axis of the rods. 
     According to a further embodiment of the laminate board, the end surfaces form a so-called finger joint, the fingers forming projections and grooves parallel to the plane of the laminate board. 
     A laminate board according to the invention is produced in a known manner by cutting rods in a mineral wool board having a length different from the one of the laminate board, are rotated 90° about their longitudinal axes and are assembled to form a laminate board. 
     According to the invention, the rods are connected with end surfaces facing each other into longitudinal rods, in which rods having the length of the laminate board are cut off and interconnected laterally to form the laminate board. The connecting of the rods that are cut from the mineral wool board and rotated can take place in various manners. One preferred manner is to assemble cut off and rotated rods successively into a rod, from which rods of the desired length are cut and connected into a laminate board. The joints of the rods will then have a random distribution over the laminate board. 
     Another preferred embodiment is cutting several rods in the mineral wool board and turning them and subsequently phase displacing them axially. The phase displacement is essential considering that the joints must not be transversely aligned in the finished laminate board. By means of the phase displacement, a diffusion of the joints is provided. The phase displaced rods are then connected with end surfaces facing each other with the preceding flow of correspondingly cut and phase displaced rods forming a flow of longitudinal rods, in which a length equal to the one of the laminate board is cut in order to form the laminate board. 
     According to a preferred embodiment of the process, the rods are connected with a glue joint by applying glue to the end surfaces before connecting and fixing e.g. by drying subsequent to the forming of the laminate board. The glue application is appropriately performed before the phase displacement of the rod flow. 
     According to another preferred embodiment of the process, the end surfaces of the rods are face milled or prepared so as to match the surfaces well, before a possible glue application. 
     According to another preferred embodiment, the future lateral surfaces of the rods are face milled or prepared so that the rods will fit tightly to each other. 
     According to another embodiment, traces are made in the end faces of the rods, parallel to the plane of the laminate board or perpendicular to these, so as to provide a finger joint between the rods. 
     According to a further embodiment, the rods are pressed together during the connecting moment at a pressure exceeding 100 Pa, preferably 500 Pa. 
     The mineral wool mat used as starting material consists of a binder fixed mineral wool, which may be a rock wool or a glass wool, forming essentially plane parallel layers consisting of vitreous fibres more or less in disorder. By rotating the rods cut from the mat, rods having vertically oriented fibres are obtained, which is valuable for the resistance requirements of the laminate board when used as a construction element. This fibre orientation, allowing shearing forces to be transferred between the surface planes of the board, enables the use of very long boards, of the size order of 9-10 m, for construction purposes. 
     The manufacture of ribs or a laminate mat of that length by means of conventional methods is difficult and would require complicated transport mechanisms. With the process according to our invention, again, no complicated equipment is needed and the space requirement can also be considered moderate. By starting from shorter mineral wool webs when manufacturing the said long elements, i.e. laminate boards, and by cutting rods in these which together with other shorter rods are assembled into &#34;longitudinal rods&#34; and by cutting rods of the desired length in these long rods, i.e. of the length of the laminate board, a process has been achieved that is easy to accomplish and results in a laminate board of the desired length. 
     Due to the fact that the long rods composed of shorter rods are interconnected in an appropriate manner, such as compressing with interlocking fibres, glueing, engaging end surfaces like finger joint locking, etc. the laminate board has the resistance provided by the mineral wool together with the sandwich surface elements. On the other hand, the weakening influence of the joints has been eliminated. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The various manufacturing steps are simple and can be varied in different ways. A preferred embodiment of the laminate board of the invention and its manufacture will be described below with reference to the enclosed figures, in which 
     FIG. 1 shows a perspective of a laminate board, 
     FIG. 2a shows an individual rod in perspective and on a larger scale, 
     FIG. 2b shows an individual rod with a joint, 
     FIG. 2c shows an individual rod with a joint as an embodiment different from the preceding figure, 
     FIG. 3 shows a rod with a finger joint, 
     FIG. 4 shows a detail enlargement of a joint produced by compressing, 
     FIG. 5 shows an embodiment of the manufacture of a laminate board as a flow chart, and 
     FIG. 6 shows another embodiment of the manufacture of a laminate board as a flow chart. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     FIG. 1 shows a laminate board consisting of seven laminates 2, each consisting of two jointed rods. The joint is marked with 3. The FIGS. 2a show a jointless rod in which the fibre plane and the fibre orientation are indicated by the thin lines. The joint 3a of FIG. 2b is an inclined joint in which the end surfaces do not form a right angle to the axis of the rod, but form a right angle to the lateral plane of the rod. The joint 3b in FIG. 2c is also an inclined joint, in which the end surfaces do not either form a right angle to the axis of the joint, but again, form a right angle to the plane of the laminate board. 
     FIG. 3 shows a rod with a finger joint and FIG. 4 shows an enlargement of a joint produced by compressing the end surfaces. In FIGS. 3 and 4, the end surfaces are perpendicular to the axis of the rod. The joint 3d in FIG. 4 indicates how the fibres in each end surface penetrate into the opposite end surface. 
     FIG. 5 shows an embodiment of the manufacture of a laminate board according to the invention. 
     Step 1a indicates the feeding of mineral wool boards produced by oscillating output, one at a time. Owing to the oscillating output, the fibre orientation is essentially perpendicular to the longitudinal axis of the web. In the step IIa the board is cut into rods rotated 90° about their axes, thus yielding an essentially vertical fibre orientation in the formed sandwich element. A possible mechanical treatment of the end surfaces and a possible glue application is carried out just before or after the rotation, in step IIIa. The grinding of the future lateral surfaces of the rods is appropriately done in this step. Step IVa relates to the feeding of a rod in its longitudinal direction towards preceding rods, disposed with ends facing each other and being aligned. The first rod is in contact with an edge at the height of the point where the rods are assembled into a laminate board. Step Va indicates the connecting of the end surfaces of the rods, where a rod is pressed against the preceding rod and the end surfaces are fixed VIa against each other. In step VIIa the front end of the longitudinal rod is cut off to a length equalling the one of the laminate board, after which the cut off rod is pushed laterally towards the collecting spot VIIIa and from there further to the spot IXa where the laminate board is formed and compressed laterally. Synchronically with the feeding of surface layer, the finished laminate core is fed in the step X to the spot where the one surface layer and subsequently the second surface layer are to be applied. Finally the sandwich element is subject to a heat and pressure treatment for final drying and curing. 
     FIG. 6 shows another embodiment of the manufacture of a laminate board according to the invention. Steps IVb-VIb are in reality subsequently aligned with steps Ib-IIIb. Because of lacking space on the paper, the figure has been split longitudinally. 
     Step Ib indicates the input of material sheets one at a time. The manufacture is continuous in the longitudinal direction of the material sheet. The material sheet is fed and cut longitudinally in step IIb into the desired number of rods. The future lateral surfaces of the rods are here subject to mechanical preparation, normally grinding. The cut material board is fed and the rods are rotated 90° about their longitudinal axis in step III. 
     Here the possible mechanical preparation of the ends of the rods and/or the glue application appropriately takes place. The rotated rods are pushed towards the preceding flow of rods in step IVb while the rods are being mutually phase diplaced in order to diffuse the joints longitudinally on the laminate board being prepared. When forwarding the rods a pressure is applied in the longitudinal direction of the board in order to press the ends of the rods against each other and to join them well. In step Vb the laminate board consisting of longitudinal rods is cut to the desired length. In step VIb the laminate board having the final dimensions is fed to the spot where the surface layers are applied under lateral pressure, first the one and the other. The surface layers are usually of thin sheet metal, but can also be construction boards like minerite boards, moulded beton layers. Finally the sandwich element obtained is subject to drying and curing. 
     The processes of manufacturing the laminate board described above are merely two preferred embodiments. Besides these, there are alternative processes for manufacturing the board. Essential for them all is that the starting material is a mineral wool sheet of a length different from the one of the laminate board, normally an essentially shorter wool sheet, in which rods are cut, are rotated and connected longitudinally and assembled into a laminate board.