Bar for a framework and production method

Abstract

The invention relates to a bar (3) for a framework (2), in particular a framework (2) for a wind turbine, comprising at least two wooden trusses (10) which are connected via a block joint (12), in particular a block glue joint (13), and which each have at least three longitudinally integrally bonded wood layers (14), in particular wood lamellae (15), wherein the at least two wooden trusses (10) connected via the block joint (12) form a core (8) of the bar (3), to the outside of which a weather protection layer (7), which contains a wood-based material, is applied. The invention further relates to a bar construction, to a wind turbine, and to a method for producing a bar of the type described above.

Description

[0001] Bar for a truss and manufacturing process

[0002] The invention relates to a truss for a truss, in particular a truss for a wind turbine, with at least two wooden trusses connected via a block joint, in particular a block glue joint, each having at least three longitudinally bonded layers of wood, in particular wooden lamellae.

[0003] Furthermore, the invention relates to a truss structure, a wind turbine and a method for manufacturing a rod for a truss structure.

[0004] Truss structures, such as frame structures, are structures or structural components that typically consist of numerous interconnected members. Due to their relatively low weight combined with high stability, frame structures are used in many applications. Truss structures transfer their own loads and, where applicable, external loads, as is the case, for example, with truss bridges.

[0005] Many timber-framed structures stand exposed to the elements and are therefore directly subject to the weather. Water, for example in the form of rain, snow, or ice, as well as animals such as insects or fungi, affect the timbers and can weaken or damage them. To prevent this, the timbers must be protected. This is essential for both metal and wooden timbers. Particularly vulnerable areas, such as glue joints in wooden timbers, can be weakened by moisture and ice formation and therefore require protection. The protection of timbers in timber-framed structures is also mandated by building codes and standards.

[0006] It is known from the prior art to protect the members of frame structures by means of a protective coating or coverings. It is also known to provide the members with protective films for their protection. Furthermore, it is known from the prior art – not only in connection with frame structures – to use ventilated facades. In this case, a facade is placed a few centimeters in front of the structure to be protected, thereby creating a cavity and thus enabling ventilation behind the facade. The chimney effect that typically occurs results in the permanent drying of the parts located behind the facade. A ventilated facade is shown, for example, in DE 20 2008 005 153 Ul.

[0007] However, a disadvantage is that protective coatings and films do not offer long-lasting protection against water and animals and must be renewed from time to time. Furthermore, protective films are usually only applied on-site, which represents an additional expense, and from an ecological perspective, they burden the environment, especially if they detach from the slats over time and fragments are scattered around. Ventilated facades also do not offer sufficient protection against animals, particularly insects, and can only be implemented with significant additional construction effort. Moreover, ventilated facades must be installed on-site and cannot be pre-attached to the slats at the factory, as they are fragile components and could easily be damaged during transport.

[0008] In light of these considerations, the object of the present invention is to at least partially alleviate or even completely eliminate the disadvantages of the prior art. Preferably, the object of the present invention is to provide a rod of the type mentioned above, the supporting components of which are protected in a simple and improved manner from external influences such as water in all states of matter and / or animals.

[0009] This problem is solved by a rod according to claim 1 and by a method for manufacturing such a rod. A rod structure is specified in claim 11. A wind turbine is specified in claim 13.

[0010] According to the invention, in a rod of the type mentioned above, the at least two timber beams connected via the block joint form a core of the rod, on the outside of which a weathering protection layer comprising a wood material is applied. The weathering protection layer advantageously protects the core of the rod, which constitutes the load-bearing and thus statically relevant component of the rod, from both moisture and animals, in particular insects and birds. In particular, the weathering protection layer can conceal the block joint, or at least the section of it running along a surface of the core. A further advantage of the invention is that the weathering protection layer can be applied to the core during the manufacturing process at the factory.A particular advantage is that the weathering protection layer can be applied, at least partially, in a single step during the production of the rod's core, especially during the joining and pressing process. This weathering protection layer allows for the creation of a rod whose core can be classified according to service class GK1 (dry, potential insect infestation) or, preferably, even according to service class GKO (permanently dry) as defined by DIN 68800-2 (2 / 2022) and DIN 68800-1 (6 / 2019). In other words, a rod can be created whose load-bearing components can be classified according to service class GK1 (dry, potential insect infestation) or, preferably, even according to service class GKO (permanently dry) as defined by DIN 68800-2 (2 / 2022) and DIN 68800-1 (6 / 2019). According to the invention, the weathering protection layer comprises a wood material.In a preferred embodiment, the weather protection layer consists of glued, bonded layers of wood, in particular wood lamellae. This allows the weather protection layer to be structured similarly to the core timbers. The type of wood material used in the weather protection layer can be the same or a different type of wood as that used in the core timbers. In particular, the same or different types of wood can be used for the core and the weather protection layer. In a preferred embodiment, the wood material of the layers of the at least two core timbers can be, for example, spruce, pine, or birch. Accordingly, in one embodiment of the invention, the weather protection layer can also be made of spruce, pine, or birch.It is preferred, however, that the wood material of the wood layers of the at least two timber trusses is different from that used in the weatherproofing layer. Preferably, spruce wood is used for the timber trusses of the core. The weatherproofing layer preferably consists of pine wood. The wood layers or lamellae of the at least two timber trusses of the core are elongated and extend parallel to a longitudinal axis of the core or the member. Accordingly, the at least two timber trusses of the core also extend parallel to the longitudinal axis of the member. Heartwood or sapwood can be used for the wood layers of the timber trusses of the core. Preferably, only heartwood is used for the weatherproofing layer. The weatherproofing layer preferably constitutes a structurally insignificant layer on the core of the member.Damage to the weathering protection layer preferably does not affect the statics of the core. When designing and dimensioning the bars according to the invention for a truss structure, the weathering protection layer is not included in calculations and simulations, particularly with regard to dynamic and / or static load transfer – preferably with the exception of considering the self-weight of the weathering protection layer. In other words, the weathering protection layer is disregarded when dimensioning the bars for load transfer within the truss structure. Preferably, the core has a substantially rectangular, and in particular square, cross-sectional shape. The bar with the weathering protection layer can also have a substantially rectangular, and in particular square, cross-sectional shape. The bar can be...

[0011] According to the invention, the timber trusses have a length between 8 m and 40 m, in particular between 10 m and 25 m. To achieve this length, the at least two timber trusses can have composite layers or lamellae of wood, which are composed of shorter layers of wood joined at their ends by connections, for example, finger joints. The shorter layers of wood, which are joined together to form a composite timber truss, can, for example, have a length between 3.5 m and 4.5 m. The at least two timber trusses each have at least three parallel, connected layers of wood. The at least three layers of wood of a timber truss are joined longitudinally, i.e., on their side surfaces, by a material bond, in particular by gluing. Preferably, at least four, at least six, at least eight, at least ten, or at least twelve parallel layers of wood are provided for a timber truss.Adhesive joints form between the wood layers of the timber trusses. These joints contain a bonding agent, in particular an adhesive, and can have an average thickness of between 0.1 mm and 0.8 mm over their entire length. In other words, the thickness of the adhesive joints can vary along their length. However, the average thickness is preferably between 0.1 mm and 0.8 mm. A melamine resin adhesive or a resorcinol resin adhesive, for example, can be used to bond the wood layers. To form the core, the at least two timber trusses are arranged parallel to each other and joined longitudinally with a material bond. Preferably, at least three, at least four, at least five, or at least six timber trusses are joined together. The timber trusses can be arranged and joined one above the other and / or side by side.Block joints are formed between the timber beams. These joints are filled with a bonding agent, particularly an adhesive, and have an average thickness of between 0.5 mm and 4 mm, particularly between 1 mm and 4 mm, over their entire length. In other words, the thickness of the block joints can vary along their length. However, the average thickness is preferably between 0.5 mm and 4 mm. The average thickness of the block joints along their length is preferably greater than the thickness of the adhesive joints along their length. For example, a melamine resin adhesive or a resorcinol resin adhesive can be used as the bonding agent for the timber beams. In the case of adhesive as the bonding agent, the block joint is referred to as a block-glue joint. The thickness of the weatherproofing layer, viewed in cross-section, is preferably at least 1 cm, particularly at least 2 cm, at least 3 cm, at least 4 cm, at least 6 cm, or at least 8 cm.The weathering protection layer can be applied directly to the core using the bonding agent, particularly the adhesive. "Applied directly" means that, apart from the bonding agent, there is no intermediate layer between the core and the weathering protection layer, and preferably no cavity is formed between the core and the weathering protection layer. In a broader sense, the weathering protection layer can also be considered a sacrificial layer, because damage to or weathering of this layer does not negatively affect the structural integrity of the structure in which the bars with the weathering protection layer are used. Only the underlying core is relevant for structural and load-bearing purposes.

[0012] In one embodiment of the invention, the at least two timber beams may be glulam beams, cross-laminated timber beams, and / or laminated veneer lumber beams. In glulam beams, the wood fibers of the timber layers or lamellae used in a timber beam predominantly, preferably at least 80%, 90%, or 100%, point in essentially the same direction. In cross-laminated timber beams, the wood fibers of the timber layers point in different directions. In laminated veneer lumber beams, the wood fibers of the timber layers used in a timber beam also predominantly, preferably at least 80%, 90%, or 100%, point in essentially the same direction. In laminated veneer lumber, the fibers may also be cut due to the manufacturing process.

[0013] Preferably, the core has a surface that is at least partially, and in particular completely, covered by the weathering protection layer. The weathering protection layer can completely surround the core, i.e., around a longitudinal axis of the rod. The weathering protection layer can preferably cover the core on all sides along its entire length. This ensures that the surface of the core is completely covered and protected by the weathering protection layer. However, the end faces of the core can remain free of the protective layer.

[0014] It is particularly advantageous if the portion of the block joint that runs along the outer surface of the core is concealed by the weathering protection layer. This protects the visible part of the block joint from the elements. Naturally, multiple block joints can also be provided and concealed in this way.

[0015] To bond the weathering protection layer to the core, it can be provided that the weathering protection layer is materially bonded to the core, in particular by gluing. A melamine resin glue or a resorcinol resin glue, for example, can be used as the adhesive. The materially bonded connection can be applied section by section, at specific points, or across the entire surface between the weathering protection layer and the core.

[0016] In one embodiment, the core has a substantially rectangular cross-sectional shape and four outer surfaces. The weathering protection layer consists of at least four layers, with one layer attached to each of the four outer surfaces. The layers can be connected to each other along their longitudinal edges, for example, by a material bond. The layers can, for example, each be formed by layers or lamellae of wood that are materially bonded to one another.

[0017] It is preferred that the layer regions each have a thickness between 1 cm and 10 cm, preferably between 3 cm and 8 cm, and particularly between 4 cm and 6 cm. The thickness of the layer regions, viewed in cross-section of the rod, refers to the distance between the inner surface facing the core and the outer surface facing away from the core. The thickness of the layer regions can be less than the width of one of the at least two timber beams of the core. A particularly advantageous embodiment of the invention is achieved when the weathering protection layer comprises at least one weathering timber beam with at least three weathering timber layers bonded together, in particular glued. The weathering timber beams are preferably connected to each other longitudinally, i.e., along the side surfaces.Tests have shown that weatherproofing layers containing timber ties exhibit particularly good properties and bond well with cores that also contain timber ties. In contrast, timber panels tend to detach from the core more easily. This is primarily due to environmental and aging influences, which affect timber panels differently than timber ties. In particular, the timber ties of the core and the timber panels used as weatherproofing layers can expand and contract to different degrees as a result of weathering, potentially creating mechanical stresses that can lead to the detachment of the timber panels. Glulam beams, cross-laminated timber beams, and / or laminated veneer lumber beams can be used as weatherproofing timber ties. At least one weatherproofing timber tie and the timber ties of the core can all be of the same length.

[0018] In a preferred embodiment of the invention, the layered areas can each be formed by at least one weathered wood truss with at least three weathered wood layers connected longitudinally by a material bond, in particular by glue. The weathered wood layers can be formed by weathered wood lamellae.

[0019] It has proven advantageous if the weatherproofing layer comprises a softwood material, in particular spruce, pine, fir, larch, and / or Douglas fir. The weatherproofing wood layers can consist essentially entirely of the aforementioned wood material, with the exception of any connecting elements at the ends for finger joints. Pine wood is preferred. Pine heartwood is particularly preferred. The wood layers of the core timbers can also comprise the aforementioned wood species, and in particular consist essentially of them. Preferably, the wood species of the core timber layers is different from that of the weatherproofing layer. In one embodiment of the invention, pine wood is used for the weatherproofing layer and spruce wood is used for the core timber layers.Heartwood is preferably used as the wood material for the weathering protection layer. Sapwood and heartwood can be used as the wood material for the core.

[0020] The invention also relates to a frame structure, in particular a truss, with several members designed as described above. The frame structure can also include members without a weathering protection layer. Such a frame structure can form part of a building or constitute a building structure itself. The members of the frame structure can be connected to one another, for example, by dowel connections. Covers can be provided on the ends of the members or at the connection points of the members. This allows areas of the members without a weathering protection layer to be protected. Cover plates or sheet metal projections, for example, can be used as covers. The cores of the members are dimensioned such that the cores alone, i.e., disregarding the weathering protection layer, ensure the static and / or dynamic load transfer of the frame structure.In particular, the cores of the bars alone, i.e., without the weathering protection layer, can transfer a predetermined static and / or dynamic design load of the truss structure. The design load can be specified, for example, by norms or standards. The design load can also be chosen to cover certain extreme cases, such as loads from high wind speeds, and the truss structure can then withstand these extreme cases, especially even without a weathering protection layer.

[0021] It is preferred if the members of the truss structure are dimensioned with regard to the statics, load transfer and / or load-bearing capacity of the truss structure, disregarding the weathering protection layer. As already mentioned, the cores of the members can be dimensioned such that they alone, i.e., disregarding the weathering protection layer, can transfer a given static and / or dynamic design load of the truss structure.

[0022] In a preferred embodiment of the invention, the weathering protection layer may be essentially non-load-bearing, and in particular, essentially non-load-bearing. Damage to the weathering protection layer therefore does not impair the statics of the frame structure. The weathering protection layer preferably does not conduct any dynamic or static loads, particularly those introduced into the members of the frame structure in their longitudinal direction. The loads are preferably transferred exclusively through the cores of the members.

[0023] A procedure for planning the frame structure may include the following step:

[0024] - Dimensioning of the bars of the truss structure with regard to the statics, load transfer and / or load-bearing capacity of the truss structure for a static and / or dynamic design load, disregarding the weathering protection layers of the bars.

[0025] In other words, the weathering protection layer is not considered in the design of the truss structure – preferably with the exception of the weathering protection layer's own weight. The static and / or dynamic design load can be specified, for example, by a standard. The static design load can include the weight of the truss structure itself, an extension, a nacelle, a generator, and / or a rotor of a wind turbine. The truss structure can therefore be dimensioned to transfer loads from a wind turbine. The dynamic design load can include dynamic loads generated, for example, by acting wind forces or the operation of the wind turbine.

[0026] The method for planning the truss structure can be used in a method for manufacturing a truss structure, with the steps: - Planning the truss structure using the above method for planning the truss structure;

[0027] - Construction of the planned framework.

[0028] During manufacturing, the rods can be connected, for example, using dowel joints or torque connections.

[0029] Preferably, a truss structure is provided, which is obtained through the process for manufacturing the truss structure.

[0030] The invention also relates to a wind turbine with a tower that is at least partially formed by a framework of trusses, which is designed as described above. The framework of trusses, which is in particular designed as a truss, can in particular form a tower or part of a tower of a wind turbine.

[0031] The invention further relates to a method for producing a rod as described above. The method comprises the following steps: i) producing the at least two wooden trusses by longitudinally bonding, in particular gluing, and pressing together the at least three layers of wood; ii) producing the weathering protection layer, preferably by producing at least one weathering wood trusse by longitudinally bonding, in particular gluing, and pressing together at least three layers of weathering wood; and iii) bonding, in particular gluing, the at least two wooden trusses to each other and to the weathering protection layer, and pressing together the at least two wooden trusses and the weathering protection layer.

[0032] In step i), at least two timber trusses are produced. Of course, more than two timber trusses can also be produced and subsequently joined to form the core of the rod. To produce the timber trusses, at least three layers of wood, in particular wood lamellae, are joined lengthwise, i.e., on their side surfaces, with a butt joint and pressed together by applying a compressive force. The wood layers can, for example, consist essentially of pine or spruce wood – except for a connecting agent such as glue in any finger-jointed connections. The compressive force can, for example, be expressed as pressure, at least 4 kg / cm². 2The process must last for at least 300 minutes, and in particular at least 360 minutes. Preferably, an adhesive is used for the bonding of the wood layers. The wood trusses can be produced sequentially and stored in between. It is also possible for the wood trusses to be produced simultaneously. In step ii), the weathering protection layer is produced. In a preferred embodiment of the invention, at least one weathering wood truss is produced for this purpose. Its production can be analogous to the production of the at least two wood trusses for the core. Preferably, several, for example at least four, weathering wood trusses are produced. The at least one weathering wood truss can, for example, also be produced by bonding at least three weathering wood layers, which can be formed by wood lamellae, longitudinally and pressing them together by applying a compressive force.The weathered wood layers can consist of, for example, pine or spruce wood. The compressive force, expressed as pressure, can be, for example, at least 4 kg / cm². 2 The process must be carried out for at least 300 minutes, and preferably at least 360 minutes. An adhesive is preferably used for the bonding of the weathered wood layers. In step iii), the at least two wooden beams are bonded to the weathering protection layer and then bonded again by applying a compressive force, expressed as pressure, of at least 4 kg / cm². 2The wood trusses are pressed together. The bonded connection between the wood trusses and the weathering protection layer is preferably made with an adhesive. It is particularly preferred if the at least one weathering wood truss is arranged on a side face of a wood truss forming the core of the rod. It is particularly preferred if two weathering wood trusses are simultaneously connected to the core on opposite sides. The weathering wood trusses and the wood trusses of the core are preferably arranged side by side. The weathering wood trusses and the wood trusses can all be of the same length. Steps i)-iii) can, but need not, be carried out in the specified order. The steps can also be carried out in parallel, insofar as technically possible and practical. During steps i)-iii), the temperature and humidity can also be regulated.

[0033] In a particularly preferred embodiment of the invention, the weathering protection layer may consist of at least four layer regions, and in step iii) two first layer regions of the four layer regions are bonded, in particular glued, and pressed onto two first opposing outer surfaces of the core, and in a further step iv) two second layer regions of the four layer regions are bonded, in particular glued, and pressed onto two second opposing outer surfaces of the core, so that a weathering protection layer, in particular a circumferential one, is formed. The timber beams form the core, onto whose outer surfaces the layer regions are applied.

[0034] In an alternative embodiment of the invention, the weathering protection layer may consist of at least four layer regions, and in step iii) the four layer regions are each bonded, in particular glued, and pressed together with a shell surface of the core material. The bonding of the four layer regions to the four shell surfaces can be carried out essentially simultaneously. Additionally or alternatively, the four layer regions can be pressed together with the shell surfaces essentially simultaneously. This can be done, for example, by a block press that can apply a compressive force to the rod to be produced from at least two directions arranged essentially perpendicular to each other.

[0035] The invention is described in more detail below with reference to figures, to which it is not, however, limited.

[0036] They show:

[0037] Fig. 1 a framework; Fig. 2 a rod in a general view;

[0038] Fig. 3 shows a rod with a view of the front side;

[0039] Fig. 4 shows a wooden truss during its manufacture;

[0040] Fig. 5 shows a rod during its manufacture; and

[0041] Fig. 6 shows a rod during manufacturing.

[0042] Fig. 1 shows a framework 1 in the form of a truss 2, comprising a plurality of interconnected members 3 made of a heating material. The truss 2 shown has members 3 that serve as corner posts 4, horizontal beams 5, and cross braces 6. Preferably, the corner posts 4 and the cross braces 6 are made of wood. The horizontal beams 5 can be made of metal or also of wood. The individual members 3 of the framework 1 can, for example, have a length between 5 m and 40 m and can optionally be connected to form longer members 3 by means of dowel joints 52. For example, the corner posts 4 can be composed of several members 3 connected at their ends 9 by means of dowel joints. In this way, corner posts 4 can be created that, for example, have a length of over 50 m.

[0043] Figure 1 shows that the truss structure 1 forms part of a tower 50 of a wind turbine 51. The representation is to be considered schematic with regard to the relative sizes. The extension 53 with the generator 54 and the rotor blades 55 of the wind turbine 51 can, of course, be significantly larger than shown.

[0044] The bars 3 of the frame 1 are exposed to external weather conditions such as moisture, ice formation, and temperature fluctuations. Furthermore, animals, especially insects, or fungi can damage the bars 3. To protect the bars 3, many bars 3 of the frame 1, especially those made of wood, such as the corner posts 4 and the cross braces 6, have an external weathering protection layer 7 according to the invention, as shown in Fig. 2. The weathering protection layer 7 comprises a wood material, for example, pine wood, and protects an internal core 8 (see Fig. 3) that transfers the statically and dynamically acting normal loads. The weathering protection layer 7 is a layer that is not statically relevant to the frame 1.This means that the weathering protection layer 7 is not considered in the structural design and dimensioning of frame structures 1, particularly truss structures 2. Therefore, if the weathering protection layer 7 should be damaged, for example by ice formation, this will have no effect on the load-bearing capacity or load transfer of the frame structure 1, because it was dimensioned without taking the weathering protection layer into account.

[0045] Fig. 2 shows a rod 3 according to an embodiment of the invention with the weathering protection layer 7. The rods 3 can be provided with covers (not shown) to protect their end faces 9 within the framework 1. The covers can be made of metal or plastic, for example, and arranged within the framework or on the rods 3 in such a way that rain, snow, and hail do not reach the end faces 9. Furthermore, the rods 3 can be provided with connecting elements (also not shown for the sake of simplicity), such as (rod) dowels, screws, nuts, and connecting plates, to connect the rods to other rods and thereby create a framework.

[0046] Figure 3 shows the end face 9 of a rod 3. It is evident that the core 8 is formed by three adjacent timber trusses 10, which are bonded together, in particular by a glue 11. The timber trusses 10 are designed as laminated timber trusses 10a in the embodiment shown. Block joints 12, in this case so-called block glue joints 13, are formed between the timber trusses 10. The block glue joints 13 typically have a thickness D i2 from 2 mm to 3 mm and are to be protected from external weather influences, which is done by the weathering protection layer 7.

[0047] The timber trusses 10 also preferably consist of pine wood and are formed by a multitude of materially bonded layers of wood 14, between which adhesive joints 22 are formed. The adhesive joints 22 can have an average thickness D over their length. 22 between 0.1 mm and 0.8 mm, they have a lesser thickness than the average thickness D considered over their length. 12The block joints 12, which can be between 1 mm and 4 mm, for example, should be noted. It should be mentioned that the thickness of the joints is not exact due to the nature of the wood and can vary; therefore, the thickness is measured along the length of the respective joint. The wood layers 14, which are in the form of wood lamellae 15 and extend along a longitudinal axis 16 of the rod 3, are bonded together by an adhesive. The wood fibers of the wood lamellae 15 point essentially in the same direction, namely in the direction of the longitudinal axis 16.

[0048] The weathering protection layer 7 is arranged circumferentially around the longitudinal axis 16 of the rod 3. The end faces 9 of the rod are free of the weathering protection layer 7. In the illustration shown, the weathering protection layer covers an entire surface area 17 of the core 8, which, due to the quadrilateral cross-sectional shape of the core 8, is composed of four outer surfaces 17a-d.

[0049] As already mentioned, the timber trusses 10 of the core 8 are connected to each other by a material bond at their respective side surfaces. In the illustration shown, three timber trusses 10 are arranged parallel to each other, with block joints 12 forming between them. The resulting adhesive joints 22 between the wood layers 14 of the timber trusses 10 are arranged perpendicular to the block joints 12 when viewed in the cross-section of the member 3.

[0050] In the illustrated embodiment, the weathering protection layer 7 is formed by four layer regions 18a-d, which are connected to each other at longitudinal edges parallel to the longitudinal axis 16, thus forming a hollow cuboid shell. The layer regions 18a-d are each preferably plate-shaped, in particular cuboid-shaped. Each layer region 18a-d is assigned to an outer surface 17a-d of the shell and is bonded to it. The layer regions 18a-d each have one or more weathering wood ties 20. The weathering wood ties 20 preferably have substantially the same length as the wood ties 10, extend parallel to the longitudinal axis 16 of the rod 3, and are themselves each composed of weathering wood layers 21, which are also oriented parallel to the longitudinal axis 16. The weathering wood layers 21 can, for example, also be present as wood lamellae.The weathered wood layers 21 of the weathered wood binder 20 are bonded together, preferably by gluing. As can be seen in Fig. 5 and Fig. 6, all adhesive joints 22 between the weathered wood layers 21 are arranged essentially perpendicular to the respective adjacent outer surface 17a-d of the cladding. The adhesive joints 22 of the weathered wood layers 21 thus point outwards from the longitudinal axis 16.

[0051] To achieve the required length of the timber layers 14 and the weathered timber layers 21, timber layers 14 and weathered timber layers 21, respectively, can be joined at their ends. The connection at the ends of the timber layers 14 and weathered timber layers 21 can be designed as wedge-joint connections.

[0052] To protect the block joints 12, first layer areas 18a, 18b of the weathering protection layer 7 are arranged on the opposite outer surfaces 17a, 17b of the first outer shell. The adhesive joints 22 of the first layer areas 18a, 18b run parallel to the block joints 12 in the configuration shown. To protect the core 8 on all sides, second layer areas 18c, 18d of the weathering protection layer 7 are arranged on the opposite outer surfaces 17c, 17d of the second outer shell. The adhesive joints 22 of the second layer areas 18c, 18d run parallel to the adhesive joints of the timber beams 10 of the core 8 in the configuration shown. In order to also achieve protection at the edges parallel to the longitudinal axis 16 of the lateral surface 17 of the core 8, the first layer regions 18a, 18b have a greater width than the core 8. Thus, in the illustration shown, the first layer regions 18a, 18b extend beyond the core 8.The length of these projecting areas 23 corresponds to the thickness D7 of the weathering protection layer 7 in the area of ​​the second outer surface of the mantle 17c, 17d. Alternatively, the second layer areas 18c, 18d can also project beyond the core 8.

[0053] As can be seen in Figures 5 and 6, the weathering protection layer 7 has a thickness D7, which, viewed in the cross-section of the rod 3, is measured outwards from the longitudinal axis 16 between the inner surface of the weathering protection layer 7 facing the core 8 and the outer surface of the weathering protection layer 7 facing away from the core 8. The thickness D7 can be essentially constant over the entire circumference of the surface 17, i.e., around the longitudinal axis 16. The thickness D7 can also vary over the circumference of the surface 17. The thickness D7 of the weathering protection layer 7 is preferably always less than the width of the wooden beam 10, which corresponds to the width B. 44 The wood layers correspond to 14. For example, the thickness D7 can be 4 cm. The thickness D7 of the weathering protection layer 7 is therefore also less than the width B. 44 of the wood layers 14 . The height H 44The wood layers 14 essentially correspond to the height H 24 of the weathering wood layers 21 . The thickness D7 of the weathering protection layer 7 corresponds to the width B2I of the weathering wood layers 21 .

[0054] Fig. 4 shows the production of a timber binder 10. Here, several layers of wood 14, in particular wood lamellae 15, are arranged parallel to each other to form a package, bonded together by applying a bonding agent between the wood layers, for example, a glue 11, and a compressive force F is applied to opposite ends of the package. The wood layers 14 can have a width B 44 for example, between 2 cm and 30 cm. The height H 44The thickness of the wood layers 14 can, for example, be between 1 cm and 6 cm. The production of a weathering-resistant wood truss 20 can be carried out in the same way. Figures 5 and 6 show the cross-section of a rod 3 with a weathering protection layer 7. In a first step (see Figure 5), several wood trusses 10, forming the later core 8, are arranged parallel to each other. A bonding agent, in particular an adhesive 11, is applied between the wood trusses 10. On opposite sides of the core 8, in the embodiment shown on the second outer surfaces 17c, 17d, weathering-resistant wood trusses 20 are arranged parallel to the wood trusses 10. The weathering-resistant wood trusses 20 form the second layer areas 18c, 18d. A bonding agent, in particular an adhesive, is also applied to the second outer surfaces 17c, 17d and / or to the weathered wooden trusses. A compressive force F is then applied.This can be produced using a block press.

[0055] To fully protect the outer surface 17 of the core 8, a further step (see Fig. 6) involves adding additional weathering timber trusses 20 to the first outer surfaces 17a, 17b, forming the first layer areas 18a, 18b. For this purpose, a bonding agent, in particular glue, is applied to the first outer surfaces 17a, 17b and / or to the additional weathering timber trusses 20, and the additional weathering timber trusses 20 are attached. A compressive force F is then applied. This can be generated using a block press.

Claims

Patent claims:

1. Bar (3) for a truss (2), in particular a truss for a wind turbine, with at least two timber trusses (10) connected via a block joint (12), in particular a block glue joint (13), each having at least three longitudinally bonded layers of wood (14), in particular wood lamellae (15), characterized in that the at least two timber trusses (10) connected via the block joint (12) form a core (8) of the bar (3), on the outside of which a weather protection layer (7) comprising a wood material is attached.

2. Rod (3) according to claim 1, characterized in that the core (8) has a lateral surface (17) which is at least partially, in particular completely, separated from the weathering protection layer (7) is concealed.

3. Rod (3) according to claim 2, characterized in that that part of the block joint (12) which is attached to the outer surface (17) of the core (8) runs through which the weathering protection layer (7) is covered.

4. Rod (3) according to one of claims 1 to 3, characterized in that the weathering protection layer (7) is bonded to the core (8), in particular glued.

5. Rod (3) according to one of claims 1 to 4, characterized in that the core (8) has a substantially quadrilateral cross-sectional shape and has four outer surfaces (17a-d) and the weathering protection layer (7) consists of at least four layer regions (18a-d), wherein on each of the four outer surfaces (17a-d) there is a layer region (18a-d) is attached.

6. Rod (3) according to claim 5, characterized in that the layer regions (18a-d) each have a thickness (D7) between 1 cm and 10 cm, preferably between 3 cm and 8 cm, in particular between 4 cm and 6 cm.

7. Rod (3) according to claim 5 or 6, characterized in that the layer areas (18a-d) each have a lesser thickness (D7) than a width (Bi0) of the at least two timber trusses (10) of the core ( 8 ).

8. Rod (3) according to one of claims 1 to 7, characterized in that the weathering protection layer (7) has at least one weathering wood binder (20) with at least three weathering wood layers (21) that are bonded together, in particular glued.

9. Rod according to claim 9 and one of claims 5 to 7, characterized in that the layer areas (18a-d) are each formed by at least one weathering wood truss (20) with at least three longitudinally bonded, in particular glued, weathering wood layers (21).

10. Rod according to one of claims 1 to 9, characterized in that the weathering protection layer (7) comprises a softwood material, in particular a spruce wood, a pine wood, a fir wood, a larch wood and / or a Douglas fir wood material.

11. Truss structure (1), in particular a truss (2), with several members (3), characterized in that the members (3) are arranged according to one of the Claims 1 to 10 have been developed.

12. Truss structure (1) according to claim 11, characterized in that the bars (3) were dimensioned with regard to the statics, load transfer and / or load-bearing capacity of the truss structure (1) neglecting the weathering protection layer (7).

13. Wind turbine (51) with a tower (50) which is at least partially formed by a framework (1), characterized in that the framework (1) is designed according to claim 11 or 12.

14. Method for producing a rod (3) according to any one of claims 1 to 10 comprising the following steps: i) Producing the at least two wooden beams (10) by longitudinally joining them materially, in particular by lamination- ii) producing the weathering protection layer (7), preferably by producing at least one weathering wood truss (20) by longitudinally bonding, in particular gluing, and compressing at least three weathering wood layers (21); and iii) bonding, in particular gluing, the at least two wood trusses (10) to each other and to the weathering protection layer (7) and compressing the at least two wood trusses (10) and the weathering protection layer (7).

15. Method according to claim 14, characterized in that the weathering protection layer (7) consists of at least four layer regions (18a-d) and in step iii) two first layer regions (18a, 18b) of the four layer regions (18a-d) are bonded, in particular glued, and pressed onto two first opposing outer surfaces (17a, 17b) of the core (8) and in a further step iv) two second layer regions (18c, 18d) of the four layer regions (18a-d) are bonded, in particular glued, and pressed onto two second opposing outer surfaces (17c, 17d) of the core (8), so that a weathering protection layer (7) is formed, in particular a circumferential one.

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