SE434172B - MULTI-LAYER BEAM - Google Patents

Description

lO l5 20 25 30 35 790450? -s 2 In the event of strong heat differences, the metal layer, due to the fact that it has a significantly greater thermal conductivity and expansion as a result, will contribute to a deformation of the beam. In addition, the laminate effect deteriorates. In accordance with German Offenlegungsschrift 2,407,642, no satisfactory strength is achieved, except that the manufacturing process does not allow any economic production or any advantage over "natural growth" beams. P In practice, so far no success has been achieved. The object of the invention is to solve this problem by solving beams of wood particles or similar natural materials, which beams are superior to the naturally grown beams both in terms of cost and resistance to aging, in particular with regard to swelling and shrinkage.

Starting from the aforementioned U.S. Pat. No. 2,717,420, the essence of the present invention is that the middle layer consists of a mixture of larger and smaller sieve chips with a specific gravity of about 450-750 kg / mg, which have a chip or fiber orientation which extends predominantly in the longitudinal direction of the V beam, and that the outer layers consist of sawn or planed natural wood boards, the thickness of which in relation to the thickness extending in the same direction of the middle layer is between 1: 6 to 1: 25. The beams according to the invention have a surprisingly high flexural strength and buckling strength, which was not to be expected in view of the prior art. The prior art (U.S. Pat. No. 2,717,420) gives the impression that the middle layer produced as an extruded body is given the required rigidity by a glued-on metal layer, from which it can be concluded that only a high-strength cover layer is suitable for giving the beam the required rigidity. .

German Offenlegungsschrift 2 407 642 does not provide any information at all with regard to the problem in question 15 20 25 30 7904507-6 3. So much the more surprising is that by gluing or gluing simple wooden boards to the middle layer produced as an extruded body, a significantly higher load-bearing capacity can be achieved than could be assumed with regard to the prior art known. This advantage obviously derives from the extrusion of coarse and fine sieve chips while observing a certain specific weight, the position orientation of the sieve chips being important. Fine sieve shavings have a long-fiber structure with a length of about 3-12 mm. In the case of coarse sieve shavings, the length amounts to approximately 30 mm, without deviating from the long-fiber structure. The known use of flat chips is avoided in the invention. The beams according to the invention are, in contrast to known beams and chipboard, generally homogeneous with respect to the middle layer. This means that despite the desired orientation, a uniform interconnection of the different long chips is present over the entire cross-section. - Examples of the load-bearing forces achievable in practice can be taken from the description.

In addition, the invention utilizes the further advantage that similar materials are glued together and that the extruded body as a middle layer subsequently conveys a significantly higher load-bearing capacity than might be assumed when glued together with sawn or planed boards of natural wood. The dimensional stability of the weather is also considerably higher than that of ordinary wood beams, since the beams according to the invention do not show deformations or cracks during the weather and because the risk of rot can be eliminated by appropriate treatment of the particles before pressing. The beams according to the invention can be layered on top of each other, both for the formation of partitions and other load-bearing walls.

The beams according to the invention are also suitable as supporting beams, main beams and structural elements, etc.

In the invention it has been found advantageous if the cross-section of the middle ski is rectangularly shaped and shows a continuous cavity, the cross-section of which is formed as an elongate hole, the distance from the cavity wall to the adjacent outer surface of the middle layer should be approximately equal in size. Depending on the function of the multilayer beam according to the invention, the outer layers can be arranged both on the narrow side of the middle layer and on its wide side. In particular, it is advisable to form two opposite outer surfaces of the middle layer as grooves and chips and not to provide them with any cover layer. Preferably, these are narrow side surfaces of the middle layer, which are formed with tongue and groove. .

However, if it is desired to provide the middle layer in the groove / chip area with cover layers, it is suitable in the invention to arrange the cover layers in several parts, the individual cover layers having a distance from each other in the transition areas of the side surfaces to the groove and the edges, respectively. this area may be beveled; In this way, the joining of the beams is not affected, but nevertheless a particularly high strength is achieved.

According to the invention, it is further proposed to extrude a rectangular middle layer in a position in which the longer edge lies vertically. Thus, when a multilayer beam with a rectangular cross-section is to be placed on a transverse edge during use, it is nevertheless produced in high format. This method of production has the advantage of an unchanged density over the length and cross section of the wood particles being pressed. If one were to produce such a multilayer beam lying transversely, the particles would need to overcome a greater friction against the fixed mandrel of the press, when the particles would in free fall reach the lower area of the press cylinder. In addition, suction holes could form in the area under the mandrel. A further object of the invention is that all the outer surfaces of the middle layer are provided with cover layers of natural wood boards by gluing. In this case, it is suitable if the vertical cover layers in the load state are clamped between the horizontal cover layers.

In addition, it is also suitable to chamfer the corners of the middle layer, whereby the advantage is achieved that a gluing in proper order of the middle layer with the cover layers can take place in the corner area. The mixing ratio between coarse and fine sieve chips is in an exemplary embodiment according to the invention about 50:50. In this case, it is suitable if about 2/3 of the sieve chip is oriented in the longitudinal direction of the beam and the rest transversely in relation thereto. From experience, this achieves a maximum rigidity of the beam thus produced and a homogeneous, as a mutual felting of the sieve chip distinguishable structure over the entire cross-section of the middle layer.

An object of the invention also lies in the possibility of connecting two or more middle layers directly to each other, in particular by gluing or gluing, and to provide only the outer sides of the middle layers with cover layers. In this way, beams can be produced with particularly high load-bearing capacity by means of simple and small and therefore inexpensive presses.

In addition, it may be advantageous to fill, for example by foaming, the cavity present in the middle layer, in particular with insulating materials, such as polyurethane.

However, the same cavities can also be used to advantage for concealed accommodation of installation materials.

Details of the invention are shown schematically and in the form of examples in the drawing. In this, Figures 1-5 show cross-sections in profile of rectangular multilayer beams with two opposite cover layers. Figs. 6-9 show cross-sections through multilayer beams, which are provided with cover layers on all sides. Figures 10 and 11 show cross-sections of further embodiments of beams.

In the exemplary embodiment according to Fig. 1, a multilayer beam according to the invention is shown in cross section, the middle layer 1 of which consists of an extruded body. How to produce such extruders in large dimensions is taught in German Offenlegungsschrift 2 535 989. The middle layer 1 has, along its longer side surfaces, cover layers 2, which are made of natural wood, in particular sawn or planed boards. .

In the middle of the middle layer 1 there is a continuous cavity 3, which in cross section has the shape of an elongated hole. It is then noticed that the distances from the cavity walls 3 to the side surfaces of the middle layer 1 are approximately equal.

At the narrow front sides of the middle layer 1 there are arranged grooves 5 and ridge 4, which are so profiled that the multilayer beams can be laid on top of each other to form a wall, in particular a partition wall and thereby be shear-proofly connected to each other by the groove / frame formation. .

In an exemplary embodiment according to the invention, the total width à of the multilayer beam amounts to approximately 156 mm, the total height b to approximately 200 mm, the thickness c of the cover layers 2 being approximately 8 mm and the width of the middle layer approximately 140 mm. One beam with these dimensions has a bending breaking load of approximately 3020 kg at a clamping length of 3000 mm. This and subsequent values have been determined by state material testing institutes. In the example according to Fig. 2, the ratio between the thickness of the cover layers 2 and the thickness of the middle layer 1 is larger.

In this case (again in the form of exemplary embodiments) the thickness of the cover layer is 20 mm, while the other dimensions are the same. The load-bearing capacity of this beam is correspondingly higher than that of Fig. 1 (assuming the same dimensions of the middle layer 1), without the cost of the beam being correspondingly higher.

In general, it can be assumed that it is convenient to choose the ratio between the thickness of the cover layer 2 and the thickness of the middle layer 1 to about between 1: 6 to 1:25. In special cases, in which other loads can be assumed, these conditions can of course be exceeded or underestimated. Preferably, in the case of particularly loaded beams, it is possible to start from a thickness of the cover layer 2 of the order of 20 mm.

In the embodiments according to Figs. 3 and 4, the narrow sides of the middle layer 1 are covered by cover layer 2. In the drawing, the carrier has always been depicted in the load condition. In the example according to Fig. 3, the cover layer 2 is relatively thin, for example 8 mm thick, while the height of the middle layer 1 amounts to about 200 mm. In the example according to Fig. 4, on the other hand, the cover layer 2 is thicker, eg 20 mm, at the same height of the middle layer 1. The beam shown in Fig. 4 has a bending breaking load of approximately 5200 kg at a clamping length of 3000 mm.

Fig. 5 shows a frame beam for finished construction, in which the cover layers 2 are glued to the wide side surfaces of the middle layer 1, whereby the outer surfaces of the cover layers can also serve as a visible surface or smooth surface for veneer, wallpaper or the like.

In the exemplary embodiments according to Figs. 6-9, it has been assumed that all the outer surfaces of the middle layer 1 are surrounded by cover layers 2, 7. The cover layers 2 cover the narrow area of the middle layer 1 and the cover layers 7 the wide area of the middle layer 1. Also these cover layer 2, 7 consists of boards of natural wood. In the example according to Fig. 6, the thickness of the individual cover layer can amount to 8 mm, while the dimensions of the middle layer 1, as in Fig. 1, amount to 140> <200 mm. In the example according to Fig. 7, the cover layer has a thickness of 20 mm. Such beams are particularly suitable for supporting roofs and the like.

In the example according to Figs. 8 and 9, the starting point has been a middle layer 1 with a square cross-section, in which the through-going cavity 3 has a circular profile.

In the example according to Fig. 8, the thickness of the cover layers is shown as 8 mm, while the side surfaces of the middle layer 1 have a width of approximately 145 mm. With the corresponding internal dimensions in the example according to Fig. 9, the thickness of the cover layers 2 is 20 mm. The beam shown in Fig. 9 has a clamping breaking load of 7300 kg and a breaking breaking load of 32000 kg at a clamping length of 3000 mm.

In the exemplary embodiments according to Figs. 6-9, the beam is shown in the position of use so that the load acts in the vertical direction.

The lateral cover layers 7 are clamped between the upper and the lower cover layer 2 in these exemplary embodiments.

In addition, the corners 6 of the middle layer 1 are chamfered in the example, according to Figs. . 7 In the beams shown in all the figures, the middle layer 1 is composed of sieve shavings mixed with binder, which may, for example, consist of 50% coarse shavings and 50% fine shavings. The strength of the beam is optimal when the sieve chip during the extrusion to approximately 2/3 is oriented in the longitudinal direction of the beam, which can be achieved by the method of chip mixing, the insertion into the press chamber and the pressure determination in a manner known per se. It must be observed that the proportion of other forms of chip, such as flat chips, is reduced to an unavoidable minimum.

The example according to Fig. 10 shows a beam with groove 5 and chip 4, the cover layers 2a, 2b and 2c having spaces 8 between each other and possibly being provided with chamfers 9. In this way high-load-bearing walls can be established.

Fig. 11 shows a direct connection of two middle layers 1, "whose free outer surfaces have glued and glued cover layers 2, respectively. Such a multiple laminate beam can be produced with a small press insert to obtain a particularly high load-bearing capacity. It goes without saying that the dimensions of the beam can be changed The invention is thus not focused on the concrete embodiments, but encompasses all variants within the scope of the patent claims.

Claims (13)

10 15 20 25 30 35 790115074 PATENT CLAIMS A multilayer beam, in which a middle layer, which occupies a substantial volume of the beam, consists of binder-mixed, extruded small parts of natural material, such as wood, straw, bagasse, cotton straw, agave fibers, waste fibers or the like, and optionally has a continuous cavity and the outer layers are glued together with the middle layer, due to the fact that the middle layer consists of a mixture of coarser characterized and finer sieve chips with a specific weight of about 450-750 kg / m3 and has a predominantly extending part in the longitudinal direction of the beam chip or fiber orientation, and that the outer layers (2,7) consist of sawn or planed boards of natural wood, the thickness of which in relation to the thickness extending in the same direction of the middle layer, amounts to about 1: 6 to 1 : 25. _ Beam according to claim 1, characterized in that the middle layer (1) is formed with a rectangular cross-section and has a continuous cavity, which in cross-section is formed as an elongated hole (3). Beam according to claim 1 or 2, characterized in that the distances from the cavity wall (3) to the adjacent outer surfaces of the middle layer (1) are approximately equal. '' n n e t e c k n a d k ä n n e - Beam according to one of Claims 1 to 3, characterized in that two opposite outer sides of the middle layer (1) are formed as grooves (5) and frame (4) and have no cover layers. Beam according to one of Claims 1 to 3, characterized in that a middle layer (1) provided with groove (5) and chipboard (4) is provided with cover layers (2a, 2b,, 2c) at the sides comprising the groove (5) and the ridge (4), which cover layers in the transition area of the side surfaces to the groove (5) and the ridge (4) respectively have a distance (8) to each other and possibly have bevelled edges (9}. 30, 7904507-6 10 Beam according to one of Claims 1 to 5, characterized in that a rectangular middle layer (1) is extruded in a position in which the longer edge lies vertically. _ I Beam according to one of Claims 1 to 6, characterized in that all the outer surfaces of the middle layer (1) are glued together with cover layers (2, 7) of boards made of natural wood. Beam according to Claim 7, characterized in that the vertical cover layers (7) in the load condition are clamped between the horizontal cover layers (2). Beam according to Claim 7 or 8, characterized in that the corners (6) of the middle layer (1) are chamfered. I ' Beam according to one of Claims 1 to 9, characterized in that the mixing ratio between coarse and fine sieve chips amounts to approximately 50:50. 11. ll. Beam according to one of Claims 1 to 10, characterized in that approximately 2/3 of the sieve chips are oriented in the longitudinal direction of the beam, while the rest are oriented transversely thereto. Beam according to one of Claims 1 to 11, characterized in that two or more middle layers (1) are directly connected to one another, in particular by gluing or gluing, and that the cover layers (2) are arranged only on the outer sides of the middle layer (l). Beam according to one of Claims 1 to 12, characterized in that the cavity (3) in the middle layer (1) is filled, such as by foaming, in particular insulating materials, such as polyurethane.