EP0799947B1 - Wooden beams and method for their manufacture - Google Patents

Abstract

The beam comprises right-angled cuboids (4) which are glued together, and which are each formed from two right angled triangular segments which are also glued together. The segments are formed be making radial cuts into a tree trunk. The cuboids are glued together so that the growth rings in the grain of the wood extend in a roughly longitudinal direction of the beam. The trunk may first be moulded into the shape of an octagon, before the radial cuts are made. Both longitudinal sides of the triangular segments may also be in the radial direction.

Description

The invention relates to a wooden beam and method for its manufacture.

Conventional glued wood binders e.g. B. in the form of bars have been manufactured for several decades and in a constructive way Timber construction used. They are made up of so-called Slats together, which are glued together, and have three decisive ones compared to the usual solid wood Advantages: first, they can be of any length and Dimension can be produced, with lengths up to about 40 m are common today, secondly they are because of previous drying of the individual lamellae almost cracked and torsion-free and thirdly because of their Structure and the glue joints are loaded 10% higher.

A disadvantage of corresponding conventional beams is however, in the fact that, due to the complex process compared to solid wood is more expensive. In addition, there is an enormous loss of material from logs to finished beams, whereby the cubic meter price of the bar increases again and finally is several times the solid wood beam.

Another problem in the production of glulam the selection of the individual lamellas is the starting product. Wood is present due to its structure natural defects (knots, cracks, growth, reaction wood etc.) not always equally resilient, which is an extreme careful pre-selection is necessary. Depending on the quality the source material is again considerable Record loss when requested The quality of the finished product should be guaranteed.

A crucial point here is the so-called Annual rings. One speaks of standing or lying Annual rings, with every conceivable intermediate angle possible is. The higher the proportion of standing annual rings, the more The wood is of higher quality because, on the one hand, the resilience larger and secondly the so-called swelling / shrinking behavior the slat is cheaper. Wood swells or radially shrinks only about half as much when the humidity changes how tangential, which leads to the fact that wood Drying warps.

In WO 8904747 A the sawing of tree trunks in long wedge-shaped elements described either individually or are laminated together such that the Growth rings in the respective elements in general run perpendicular to the cutting surface and the Growth rings of all elements are generally parallel to each other run when the elements are laminated together become. The production of high quality beams not addressed.

The object of the invention is a to provide higher quality beams, the described, known from the prior art Does not have disadvantages.

This task is accomplished by a bar according to claims 1 to 3 solved, the star or triangular lamella is built up and due to its more favorable annual ring location can be statically significantly higher than a conventional bar. The bar according to the invention can also with significantly lower costs than the known ones Glulam truss beams are produced.

Another embodiment of the invention is in Claim 4 described method for producing a bar according to the invention.

The invention is illustrated by the following figures explained.

Figure 1 shows schematically the conventional incision method for the generation of rectangular slats.

Figure 2 shows schematically the star incision method to produce the star or triangular lamellae, which are used to manufacture of the bar according to the invention can be used.

Figure 3 shows schematically a conventional one Rectangular slats built beams.

Figure 4 shows schematically the invention Star or triangular lamellar beams.

Figure 5 shows schematically the manufacturing process of the bar according to the invention.

The one used to make the triangular slats Incision method (Figure 2) differs from that conventional (Figure 1) in that there are no rectangular Cross sections generated, but after z. B. with help a profile cutter, for example, and preferably one Milled octagon from the round trunk with a so-called Star cut into triangular lamella 1 (Figure 2). In this way, sixteen triangular blades 1 generated with a rectangular cross section, the long sides 2/3 are radial (Figures 2 and 4).

An advantage of this method is that none Changes to the incision machine are made must, because the log used, regardless of its Diameter, always cut at the same angle becomes. The slats generated then differ only in their width or height. So there is one in production System can be used, firstly, no complex control and secondly, no set-up times apart from resharpening of sawing, requires.

The second advantage of this procedure is the essential one higher yield of sawn timber. So with the conventional Incision (Figure 1) the yield of the main product in the range of 45 - 50%, plus 10 - 15% side goods. In contrast, the star incision (Figure 2) yields up to 73%; in addition, the lumber is here completely Main product available. The average yield is thus around 25% higher in the star incision process than with conventional incisions.

Before gluing the individual lamella 1, they must be dried and planed (Figure 5), which is the conventional Slats means another loss of 30-35% because of the warping of the wood mentioned above Drying provided a very large excess of the raw lamellae must be in order after the dressing and planing process to get a full slat. Reduce these losses with triangular slats due to the cheaper Swelling / shrinking behavior to 15 - 25%, i.e. around half.

Overall, due to the star incision process the material losses from logs to glulam are not more than previously 60 - 70%, but only 40 - 60%. During a cubic meter of conventional finished slats Star slats can cost from 600, - to 650, - DM for 400, - to 450, - DM, about 2/3 of the previous one Costs.

In the manufacture of the beam according to the invention (Fig. 5) the cut triangular lamella 1 after drying and planing glued together. Doing so first two of the triangular lamellae 1 joined together to form a cuboid 4 and glued together at an angle. In dependency of Dimensioning of the triangular slats used 1 receive appropriately dimensioned cuboids. After that the cuboids 4 together to form a bar of any length and / or width and / or height glued.

In a conventional, made up of rectangular slats Bar (Fig. 3) is the annual ring position mentioned above usually in such a way that there are mainly lying growth rings, which leads, depending on the content of horizontal growth rings, the swelling / shrinkage behavior of the bar is unfavorable and the Resilience is limited.

In the manufacture of the beam according to the invention applied star incision methods (Fig. 2) are inevitable only slats 1 with standing tree rings produced. On beams composed of these triangular lamellae 1 (Fig. 4) therefore has a much more favorable swelling / shrinking behavior and is above all structurally much stronger resilient than a comparable conventional beam.

Claims (4)

1. A beam comprised of rectangular cuboids (4) glued one on top of the other, which are each formed out of two glued together rectangular triangular lamellae (1) comprised of radial sections from a log, wherein the cuboids (4) are glued one on top of the other in such a way that the standing annual rings essentially extend in the longitudinal direction of the beam.
2. The beam according to claim 1, characterized in that the triangular lamellae (1) are radial sections from a log milled into an octagon.
3. The beam according to claim 1 and/or 2, characterized in that both longitudinal sides of the rectangular triangular lamellae (1) are radials.
4. A procedure for manufacturing the beam according to one of claims 1 to 3, characterized in that a log is milled into an octagon, rectangular triangular lamellae (1) are generated out of this octagon in the star incision procedure, the lamellae (1) are dried, planed and glued together into rectangular cuboids (4), and the cuboids (4) are glued one on top of the other in such a way that the standing annual rings essentially extend in the longitudinal direction of the beam.

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