FI80114C - ANORDINATION WITH A CLAIM. - Google Patents

Description

1 80114

An arrangement related to a building element

The invention relates to an arrangement associated with a building element for improving the fastening of screws and thus for increasing the detachment resistance, which arrangement comprises at least one element, preferably of the hard type fibreboard, with chipboard elements attached to both sides with at least local adhesive joints between the elements.

10 Particleboard is widely used in the construction industry for lining floors, ceilings and walls, but also for furniture such as cabinets, furniture, etc. It is also known that particleboard provides a relatively poor fastening base for screws subjected to tensioning. This problem is usually solved with special chipboard screws or expansion sleeves to which the screws are fitted. Even with such expansion sleeves, it happens that when high loads are applied to the screw and the sleeve, the fastening in the chipboard fails so that the screw 20 and the sleeve are pulled out of the chipboard. For this reason, there has long been a need to improve the known chipboards in an advantageous manner in order to increase their screw-holding strength, the fastening then taking place by screwing the screw directly onto the board or via said expansion sleeve.

An example of the use of the building elements described in the introduction is known from Norwegian patent application 81 25 86. It describes a door panel which is primarily intended to provide low sound transmission and good fire resistance. Sound insulation is provided when the door panel consists of a plurality of panels spaced a short distance apart and of different material, with a fiberboard in the middle and a plurality of fiberboards on both sides. Of course, from the point of view of sound insulation, it is important that the panels be at a short distance from each other, but on the other hand there must be a joint between the middle panels so that they do not come off the frame in the event of fire. For this reason, the middle three sheets are joined by relatively narrow adhesive seams. However, these three boards do not have a substantial load-bearing or supporting effect, which in turn is provided by the wooden frames of the door and the outer cover plates, preferably the fibreboard. This structure has a weak screw grip and is therefore provided with 10 wooden frames for attaching hinges, among other things.

It has been common to use solid wood when making door frames, because these types of frames have good screw-holding strength. However, such door frames often become relatively expensive, especially if the door and 15 door frame have to be made of expensive types of wood. The shape stiffness of some types of wood is relatively poor when exposed to changes in temperature and humidity, and there is a risk that the door leaf will stick to the door frame due to the latter deformations. Laminate structures known from conventional furniture panels are not particularly suitable for door frames, especially due to their complex and expensive structure. Also, cross plywood is not suitable for door frames because of the relatively high manufacturing costs and because the processed plywood may be unpleasant in appearance. In addition, plywood is not always easy to work with because it wants splits. Known particle boards are also not suitable for door frames because the material is too brittle for use in door frames where the load may be high. Particleboard also provides poor screw retention for new hinges.

The use of chipboards in the door frame, in turn, has been considered in Norwegian patent application 84 05 10. Here, the frame structure comprises a core of double chipboard 35 provided on the outside with a stiffener. 3 80114 with wool, hardboard coverings. This seems to give a relatively sturdy structure, but on the other hand the detachment resistance of the hinge screws is low. The screws only attach to the particleboard when the hinge plate is embedded in the fibreboard, reducing its strength. Tests according to the Norwegian door load standard NS 3147 "Be-stemmelse af d $ rers bsreevne ved vertikal last pä drrla-det" have shown that door frames made of chipboard do not withstand the use of ordinary hinges, as the doors are regularly torn from the frame. The object of the present invention is to provide a building element which consists largely of chipboards, but in which the resistance to the removal of screws is nevertheless high enough to be used in door frames. This is achieved according to the invention in that in the building element shown in the introduction, the adhesive seams completely cover the elements and in that the building element forms part of the door frame.

It has surprisingly been found that the gluing of a fibreboard between the particleboards gives a multiple screw release resistance compared to the particleboard alone and which is also considerably higher than for ordinary whole wood, for example pine. Since the fibreboards themselves do not have a high peel resistance, this is apparently a synergistic effect, which is difficult to explain afterwards. Possibly, the effect is based in part on the fact that the particle boards rest on the fibreboard, preventing it from cracking when the screws attached to it are loaded.

The unusually good properties of the door frame material according to the invention make it possible to make the door frame relatively thin, for example not more than 20 mm thick, when the strength of a conventional door made of solid wood, for example pine or spruce, is 30 mm.

4,80114

The building element according to a preferred embodiment of the invention comprises only one element made of fibreboard. This makes the building element as simple as possible, consisting of only three parts, so that the screws are well fastened regardless of which side they are fastened to. The most suitable combination of durability and rigidity is achieved when the strength of the fiberboard element is about half the strength of the particleboard element.

The invention will be described in more detail with reference to the accompanying drawing.

Figure 1 shows a building board according to the invention.

Figure 2 shows a door frame made of a building board according to the invention.

Figure 3 shows a variation of a door frame according to the invention.

Figure 1 shows a building board consisting of two chipboards 1,2, between which a fibreboard 3 is arranged and glued to them, whereby the fiber-20 board is preferably of the hard type. A coating, preferably plywood 4, can be provided on the outer surface of the chipboards. As can be seen from Figure 2, a piece corresponding to the depth of the door frame and also to its height and width is cut from the building board 1 according to Figure 1. The putty edges of the door frame pit-25 are covered with a strip 5, which is of the same type of wood as the plywood covering 4. A groove is further milled in the chipboard part 1, to which the door plate support strip 6 is attached. This support strip should be made of solid wood and wood similar to plywood cladding 4 or strip 5. The door frame 30 thus has a uniform appearance. Of course, there is no reason why said plywood coverings 4,5 could not be omitted in certain cases, e.g. when the door frame is to be painted.

Fig. 3 shows a car-35 min variant of the door according to Fig. 2, in which instead of a plywood or paint coating li 5 80114 a plastic coating 7 is used, which is shaped so that it can be locked in place in the groove 8.

It should be noted that the invention is not limited to the use of two particle boards and one fibreboard between them, as shown in Figure 1, but several chipboards and a corresponding number of fibreboards can be used in the production of the building board according to the invention.

Claims (3)

6 80114 An arrangement associated with a building element for improving the fastening of screws and thus for increasing the detachment resistance, which arrangement comprises at least one element (3), preferably of the hard type fibreboard, with chipboard elements (1, 2) attached to both sides of the adhesive joints between the elements. being at least local, characterized in that the adhesive joints completely cover the elements and that the building element forms part of the door frame. Arrangement according to Claim 1, characterized in that the building element comprises only one element (3) consisting of fibreboard. An arrangement according to claim 2, characterized in that the strength of the fiberboard element (3) is about half the strength of the chipboard elements (1, 2). 20 II 7 80114