Composite beam, composite beam structure and method for producing a beam structure

Abstract

The invention relates to a composite beam (1) consisting of at least one first sub-element (2) and at least one second sub-element (3), wherein the first sub-element (2) surrounds the second sub-element (3) in an encasing manner, and the first sub-element (2) is made of at least one metallic material and is joined by an integral joining method, in particular a welding method, to an encasing covering surrounding the second sub-element, and the second sub-element is made of a wood material and / or a wood-based material.

Description

[0001] Composite beam, composite beam structure and method for manufacturing a composite beam

[0002] The invention relates to a composite beam and a method for manufacturing a composite beam, as well as a composite beam structure.

[0003] Composite beams are beam-like elements used in a wide variety of designs in engineering to transfer loads. Composite beams, which consist of different materials, can better utilize the different properties of these materials through combination. A distinction is made between different load cases. Loads that occur during operation, i.e., in the use of the composite beam, in the linear-elastic range, are transferred permanently or at least over a certain period, without the composite beam undergoing significant changes. Loads acting on the composite beam through impact or overload lead to plastic deformation and fracture. Under such loads, energy absorption by the composite beam, made possible by the formation of yield zones and fracture zones, is advantageous.

[0004] Therefore, composite beams are dimensioned for their intended use and for potential damage. In addition to lightweight construction, i.e., minimizing the weight of the composite beam, the CO2 footprint and the sustainability of the materials are also economically important. Therefore, materials that are particularly environmentally friendly are advantageous.

[0005] WO2023 / 201379A1 describes such a composite beam consisting of a metal tube and wood-based material and discloses a method for its manufacture. A disadvantage here is the limitation to swellable materials necessary for joining the composite beam.

[0006] JP2938066B1 discloses a manufacturing process for upsetting a metal tube onto a wood-based material in order to utilize the properties of the different materials in a composite beam. Disadvantages of the prior art include the limitation to usable wood-based materials and their geometries, as well as the restriction to the profile shape. Furthermore, the use of only one metallic material and its properties is a disadvantage. The high costs of the manufacturing machinery are also a drawback.

[0007] The object of the present invention was to overcome the disadvantages of the prior art and to provide a composite beam and a method for its manufacture by means of which a user is able to carry out a simple design and manufacture of a composite beam that can be adapted to the application.

[0008] This problem is solved by a device and a method according to the independent claims. The sheath formed by the first sub-element, which at least partially surrounds the second sub-element, need not be completely closed, but a mechanical connection between the open ends is desirable. Furthermore, a combination of both joining methods is conceivable (material-bonded and / or forming).

[0009] The invention comprises a composite beam, in particular a lightweight profile, consisting of two sub-elements. The composite beam consists of at least one first sub-element and at least one second sub-element. The second sub-element is enclosed by the first sub-element in a sheath-like manner. The first sub-element, consisting of at least one metallic material, is joined by a material-bonded process, in particular a welding process, to form a sheath-like shell enclosing the second sub-element. The second sub-element consists of a wood-based material and / or a wood-based material.

[0010] The advantage of this design is its high energy absorption capacity combined with relatively low mass. This beneficial property is made possible by the well-coordinated interaction of the first and second sub-elements. The second sub-element forms a supporting core for the relatively lightweight and thin-walled first sub-element. For example, the second sub-element can be made of wood. Tests have shown exceptionally good properties when using birch for this sub-element. As the diagram shows, other wood species are also conceivable, such as poplar and paulownia, which are very lightweight. Furthermore, it is conceivable that various wood-based materials could be used in addition to solid wood. These include, for example, boards, veneers, particleboard, and fiber-based materials, such as those used in glued laminated timber, plywood, OSB panels, or MDF panels.It is also conceivable that materials such as cardboard or paperboard could be used. Under load, the porous wooden structure of the second component allows the first component to collapse gradually without failing. This enables the absorption of large amounts of energy. The first metallic component preferably has a high elongation at break in order to absorb energy over large areas through plastic deformation.

[0011] The first component can be easily welded together from flat sheet metal blanks to form a rectangular shell that encloses the second component. A particular advantage is that this results in the second component being enclosed by the first with virtually no play. This is also the case if the second component has different geometries or a curved profile along its longitudinal cross-section.

[0012] The following diagram shows various composite beam designs with a rectangular cross-section of 30x90 mm as tested in three point bending tests with a beam length of 600 mm, compared to a pure steel profile as a reference. The beams are loaded horizontally (around their weak axis) with a support spacing of 400 mm. The sheet thickness of the first element is 0.8 mm. The gray areas overlaid on the curves show the variation between multiple samples in the tests. The diagram clearly demonstrates the benefit of the composite action between element one and element two in terms of increasing the maximum force and energy absorption capacity compared to the reference beam.

[0013] Diagram of force-deformation of composite beams and steel reference profile:

[0014] 0 20 40 60 80 100 120 140

[0015] Deformation [mm]

[0016] Another advantageous embodiment is when the first component is formed from two half-shells, which are joined along their longitudinal length using a welding process. In this case, the second component, made of a wood-based material, is inserted between the half-shells.

[0017] An advantage of this design is that different materials are used for the two half-shells. For example, one half-shell could be made of fine-grained steel and have a higher tensile strength than the other. It is also conceivable that the half-shells are of different thicknesses, allowing the composite beam to bear higher loads in certain areas. Another advantageous design is that the first element has different properties along at least one longitudinal section of the composite beam. For instance, half-shells could be made of at least two different metallic materials. These are referred to as tailored blanks, meaning custom-made sheet metal blanks made of different material grades and / or thicknesses.Composite beams, which for example have to withstand shear bending, can have different material grades and / or sheet thicknesses in the area of ​​the greatest bending moment than in the ends of the composite beam where the bending moment is lower.

[0018] It is particularly advantageous if the second component has different materials along its longitudinal extent. This allows the formation of plastic hinges to be influenced by the load. Likewise, the energy absorption area of ​​the composite beam can be controlled.

[0019] Another advantageous embodiment of the composite beam is that the second component consists of at least two different wood-based materials and / or wood-based materials.

[0020] This design allows the properties of the second component to be particularly advantageous in combination with the first component. For example, structural properties can be controlled, weight can be reduced, or the formation of a plastic hinge in the event of failure can be determined.

[0021] Another advantageous embodiment is that the first component is formed from a sheet of metal using a roll forming process, and the second component is enclosed by the first. Along the longitudinal extent of the composite beam, at least partial material bonding can be achieved using a joining process, in particular welding. An advantageous method for producing a composite beam from at least one first component and at least one second component, wherein the first component encloses the second component in a shell-like manner, is to join free end sections of the first component together to form a closed shell.

[0022] This design enables the economical production of the composite beam as a semi-finished product and reduces the joining length. This allows the first component, for example, to be manufactured with only one joint along its length. The free end sections can be butted and welded together centrally on a side surface. The joint can be interrupted along its length. For instance, the first component could be joined with a stitched weld, i.e., with intermittent welds. This reduces manufacturing time. Furthermore, the end-face joint can also be made via the second component, for example, using a finger-joint connection. An advantage of this variant is that the entire cross-sectional area of ​​the second component also contributes to load transfer at the joint.

[0023] It is also advantageous if the joint is executed as a continuous weld. This offers the benefit that, for composite beam structures and components, such as those created by welding connecting elements via continuously welded joints, the encased second component is tightly enclosed. This prevents the penetration of substances such as liquids. Furthermore, it ensures that the properties of the second component remain constant over a certain period. For example, the moisture content of a wood-based material remains consistent. Another advantage is the reduction of biotic pathogens such as fungal growth and abiotic processes. Tests have also shown that the component constructed in this way is suitable for e-coating (cathodic dip coating) at higher temperatures.A very advantageous embodiment of the composite beam is that the second sub-element has at least one recess along a longitudinal extent that releases the first sub-element along the joining connection.

[0024] When creating a joint, especially through welding, a gap in the joint area is highly advantageous. In fusion welding processes, this prevents the local molten area of ​​the weld pool from direct contact with the second component. Welding tests have shown that this gap allows for a particularly favorable weld formation. For example, the weld bead shape on the side facing the second component is improved. Furthermore, shielding gas can be supplied to the welding zone via the gap and the resulting cavity, thus facilitating formation during the joining process. Surprisingly, the outgassing caused by the heat input in the second component has little influence on the weld bead formation.Likewise, the heat input in the second sub-element results in negligible changes to the properties of the second sub-element.

[0025] Joining processes include not only welding but also soldering processes, which do not melt the base material but rather wet the base material with a molten solder bath. The invention is also advantageous for soldering processes.

[0026] Another advantageous embodiment of the composite beam, consisting of at least one first sub-element and at least one second sub-element, wherein the first sub-element forms a cladding around the second sub-element, is characterized by the first sub-element being made of at least one metallic material and being joined by a forming process prior to the material-joining process, in particular flanging to form a cladding shell enclosing the second sub-element, and the second sub-element being made of a wood-based material and / or a wood-based material. Depending on the application, a subsequent material-joining process may be omitted. In this embodiment, the joint is produced along a longitudinal extent by forming, in particular by a roll forming process. This joining process is particularly advantageous for forming a connecting flange. A combination with welding or brazing processes is also advantageous.It is also conceivable to combine the components with sealants or adhesives to create a durable, tight joint. For example, a sealant can ensure that the second component remains tightly encased by the first, even if the connecting tab is penetrated by a fastener such as a screw or rivet.

[0027] Another advantageous embodiment is achieved when a connecting tab is formed by free end sections, and the joining connection is not made directly at the free end sections but at a distance from them, so that parts of the first component are present across the joining connection, thus forming, for example, a connecting tab. The advantage here is that these parts of the first component projecting beyond the joining connection can be penetrated by connecting elements without breaking the tight encapsulation of the first component.

[0028] An advantageous embodiment of the composite carrier is that the first and second sub-elements are bonded at at least one contact surface using an adhesive and / or sealant. This bonding can, for example, positively influence the carrier's vibration behavior (NVH - Noise, Vibration, Harshness). Bio-epoxy can generally be used as the adhesive.

[0029] This design allows for the integration of joining elements into the composite beam. These joining elements, for example, penetrate the first sub-element and extend into the second sub-element. The use of adhesive and / or sealant in the contact surface, at least in the area of ​​the joining element, offers the advantage of ensuring the tightness of the encapsulation. A further advantageous embodiment of the composite beam is that the first sub-element and the second sub-element each have a joining element, in particular a nail, on at least one contact surface.

[0030] This joining element can locally improve the combination of properties of the individual components. For example, load transfer via a joining element such as a screw is particularly advantageous. Introducing a tensile load onto the composite beam via a joining element such as a ring bolt is especially beneficial.

[0031] Another advantageous embodiment of the composite beam is that the first sub-element consists of at least one metallic material and surrounds the second sub-element by means of a joining process, in particular a welding process, forming an enclosing dense shell.

[0032] This design is particularly advantageous because the dense shell creates consistently stable conditions for the second component.

[0033] An advantageous further development of the invention of composite beams to a composite beam structure is that at least one composite beam is welded to a structure with at least one further metallic component, in particular a connecting element.

[0034] An advantage of this is that a closed shell consisting of a semi-finished product completely encloses the composite beam and additional elements such as connection elements, for example flanges or connection plates. Furthermore, additional functions such as fastening options via the connection elements, for example through bores, are advantageous. An advantageous further development of the invention from composite beams to a composite beam structure is that a first composite beam is joined with a second composite beam to form a composite beam structure.

[0035] The advantage here is that a composite beam structure is created from semi-finished composite beams, with the second component completely enclosing it with a closed shell. For example, it is conceivable that composite beams are mitered and joined to form a frame. A further advantageous development is to not saw through the semi-finished product completely, but rather to create a recess in the profile, which is then formed into a profile corner. The advantage here is that the composite beam or composite beam components remain connected via a portion of the first component. This significantly reduces the joining length, for example, when welding. It is also advantageous because positioning is simplified. For example, a rectangular frame element can be manufactured as a composite beam structure from a single composite beam.This beam features miter cuts at each end and machining in the form of cutouts at three points to bend the composite beam and join it at the ends to form a frame. By joining the ends and the three machined cutouts, a closed shell is created around the second element after bending.

[0036] The composite beam's design can be engineered to allow for easy disassembly and repair. The optional use of detachable connections, such as plug-in connectors with locking elements (like cotter pins, screws, or locking tabs), enables non-destructive separation of individual components. In particular, this allows for residue-free separation between metallic and wood-based materials, thus promoting reusability and single-material recycling. Furthermore, the use of standardized profiles and modular connectors can simplify maintenance and modifications. Such a design is especially advantageous in applications with frequent maintenance or in modular structures.

[0037] Composite beam technology can be used for a wide variety of applications. It is particularly suitable for areas where weight, strength, energy absorption, or sustainability play a crucial role.

[0038] Examples of possible uses include:

[0039] - vehicle construction, for example for roof frames, battery trays or body structures,

[0040] - mechanical engineering, for example in the form of racks, frames or modular machine components,

[0041] - the logistics sector, for example for load carriers, parcel stations or high-bay warehouse systems,

[0042] - the construction of elevators and gondolas, especially for load-bearing frame structures with high strength requirements,

[0043] - as well as furniture and interior design, for example for the production of picture frames or modular furniture elements.

[0044] Especially when the second sub-element is tightly encased by the first, applications are conceivable in scaffolding, shipbuilding, nacelles (the tight seal with the outer metal shell prevents the wood from molding or otherwise weathering), rotor blades for wind turbines, etc. The use of, for example, a rubber or self-healing shell is also conceivable, which can further reduce vibrations and noise. This refers to a rubber shell or a shell made of another material that lies between the wooden core and the metal casing. This additional layer can selectively influence certain physical properties—especially through the partial decoupling of the wooden core from the metal shell. This allows, for example, vibration transmission, electrical conductivity, or other interactions to be specifically modified or reduced. Furthermore, the intermediate layer can be designed in such a way as to...

[0045] - for example, made of thermoplastic polyurethanes, other thermoplastic plastics or rubber - that it assumes a self-closing function in the event of damage to the metal casing (whether intentional or unintentional).

[0046] This self-locking can occur in two ways:

[0047] - Passive, solely through the elastic recovery behavior of the material, i.e., without additional energy input.

[0048] - Active, through the targeted application of physical energy such as heat, vibrations or pressure, which stimulates or activates the material to seal.

[0049] An example of this would be a borehole that is no longer needed, which can be permanently sealed by this intelligent intermediate layer.

[0050] For use in corrosive environments, the first metallic component can be pre-galvanized. Since hot-dip galvanizing can require temperatures of around 450 °C, galvanizing is preferably carried out before joining. After the metal-bonded connection, particularly by welding, the weld seam can be treated, for example by flame spraying, to ensure continuous corrosion protection.

[0051] For visual enhancement, the outer surface of the metallic component can be additionally provided with a veneer layer. Such a coating allows for a high-quality, attractive design, for example in visible applications or in furniture construction, without impairing the structural functionality of the composite beam. Furthermore, the invention includes a method for manufacturing the composite beam.

[0052] Method for producing a composite beam from at least one first sub-element and at least one second sub-element, wherein the first sub-element encloses the second sub-element in a shell-like manner and free end sections of the first sub-element are connected together to form a closed shell.

[0053] An advantage of this method is the production of a composite beam that consists of at least two different sub-elements enclosed in a shell-like structure. The flexibility of the manufacturing process is particularly beneficial. Various geometries of the second sub-element can thus be easily enveloped by a first sub-element. The simplest implementation involves joining flat first sub-elements at their free ends around a second sub-element. For example, a rectangular sheet metal shell can be formed from four flat sheet metal strips and wrapped around a rectangular second sub-element, such as a wooden core.

[0054] Another advantageous development of the process is:

[0055] Method for producing a composite beam wherein the second sub-element is completely enclosed by the first sub-element and all free end sections of the first sub-element are connected together and the second sub-element is completely tightly encased.

[0056] The advantage of this method is that a second component can be very easily and completely encased by a first component. This makes composite beams produced using this method suitable for exposure to various environments without exposing the second component to those environments. For example, humid or aqueous environments, which could cause biotic and abiotic changes in wood-based materials, are thus prevented. The second component can be designed to have at least one recess along its longitudinal axis, exposing the first component along a joint created by the joining process. This recess in the second component forms a cavity through which shielding gas is introduced into the welding zone during the manufacturing of the composite beam to facilitate the formation of the joint.

[0057] The composite beam can be designed so that its thermal insulation properties are optimized for use in thermally sensitive components such as window construction, caravan ceilings, etc.

[0058] It is also conceivable that the first component rests directly on the second component and is joined by welding, without any recess. Studies have shown that outgassing from the wood-based second component during welding does not negatively affect the weld quality. Despite the heat input, the second component remains structurally stable without any significant changes in its mechanical or geometric properties. Birch wood, for example, was used.

[0059] A metallurgical bond between the first and second sub-elements can also be created by soldering, whereby the solder wets the metallic material of the first sub-element in a molten state. The connection can be made exclusively by soldering or in combination with the other joining methods mentioned.

[0060] To better understand the invention, it is explained in more detail with reference to the following figures. These are presented in the form of highly simplified illustrations. It should be noted at the outset that in the differently described embodiments, identical parts are provided with the same reference numerals or component designations, and the disclosures contained in the entire description can be applied analogously to identical parts with the same reference numerals or component designations. Furthermore, the positional designations chosen in the description, such as top, bottom, side, etc., refer to the figure directly described and illustrated. These positional designations are to be applied analogously to any change in position.

[0061] FIGURE DESCRIPTION

[0062] They each show, in a highly simplified, schematic representation:

[0063] Fig. 1 shows part of a cross-section of an embodiment of the composite beam in simplified form.

[0064] Figures 2 a) to f) show simplified cross-sections, possible arrangements of joints, and machining of the core. Any shaped half-shells or sheet metal blanks can enclose the core.

[0065] Fig. 3 a) Shows possible embodiments for the joint for an overlap joint, b) an embodiment with a flange, c) an embodiment with a connecting tab

[0066] Fig. 4 shows the cross-section through a possible core which may have different machining processes and may be made of different materials.

[0067] Fig. 5 shows an embodiment consisting of two cores that are individually and together encased.

[0068] Fig. 6 shows an assembly of a composite beam with a possible connection of a component. Fig. 7 shows a composite beam structure consisting of a composite beam with end-face connection elements.

[0069] Fig. 8 shows part of a composite beam structure with a machining process, in this case a cutout for forming a miter joint.

[0070] Fig. 9 shows a schematic setup in which an intermediate layer in the form of an adhesive or sealant is arranged between the first and second sub-elements.

[0071] Fig. 10 a and b show a multi-layered structure with thermal decoupling,

[0072] Figs. 11 a to d show variants comprising source bodies,

[0073] Figs. 12 a and b show variants in which the joining connection was produced by forming,

[0074] Figs. 13 a and b show a composite beam with a wide and a narrow side, and

[0075] Fig. 14 shows a cross-sectional view of a composite beam with an integrated pipe.

[0076] Figure 1 shows a simplified cross-section of a composite beam 1. A rectangular cross-section of a second sub-element 3, which in the simplest case is a wood-based material and is also referred to as the core, is encased by a first sub-element 2, which is formed from flat sheet metal blanks joined by connections 4. For the sake of simplicity, only the upper part of the cross-section is shown. A possible symmetry is indicated by the dotted-dashed line; thus, in the simplest case, a rectangular cross-section of a second sub-element 3 is enclosed by four sheet metal blanks that form a encasement via connections 4. The second sub-element 3 can have four recesses 5 that form the connection.

[0077] 4 facilitates the process. The recesses 5 prevent the molten pool of a weld or solder joint from coming into direct contact with the second component 3. Furthermore, the recess 5 forms a cavity that enables the formation of the joining joint 4. Shrinkage of the joining joint 4 results in a tight and nearly play-free fit of the second component 3 by the sheath-like, enveloping first component 2. An adhesive 19 (not shown) can be applied between the first component 2 and the second component 3. This adhesive 19 can hold the sheet metal blanks in position during manufacturing and support the production process. It can also improve the properties of the composite carrier 1 by transferring stresses between the components. The adhesive 19 and / or sealant is also advantageous when attaching joining elements.Compared to an unfilled metallic reference profile, the NVH (Noise, Vibration, Harshness) properties are significantly improved by the wood-based sub-element 2. Adhesives or sealants, if they are highly shear-compliant, may lead to a limited additional improvement.

[0078] Figures 2 a) to f) show further and, where applicable, independent embodiments of the composite beam 1, whereby the same reference numerals or component designations are used for identical parts as in the preceding figures. To avoid unnecessary repetition, reference is made to the detailed description in the preceding figures. Flat sheet metal blanks can also be replaced by half-shells. Figure a) shows a first sub-element 2 formed three times, which can also be produced by roll forming or slide drawing and is most easily created by bending edges. For the sake of simplicity, it is shown with sharp edges. It has a recess 5 on one edge of the second sub-element, and the first sub-element 2 is joined along this longitudinal edge by the joining connection 4.This advantageous embodiment has a reduced number of joining connections, in this embodiment only one. This makes it particularly economical to manufacture. b) shows an embodiment consisting of a first sub-element 2 with large radii, where the joining connection is made on one side of the cross-section and has no recess. c) shows an embodiment where the recess 5 on one side of the second sub-element 3 is in the form of a groove. d) shows an embodiment with a V-shaped groove for the recess 5 on one side of the second sub-element 3. e) shows an embodiment in which the first sub-element 2 is formed from two half-shells and joined to form an enclosing shell via two joining connections 4. The recesses 5 are groove-shaped. f) shows an embodiment with two V-shaped grooves for the recess 5 on two sides of the second sub-element 3 and two half-shells forming the first sub-element 2.For all embodiments, any joining process is conceivable, for example, high-frequency induction (HFI) resistance pressure welding, arc welding processes with and without filler material. Beam welding processes such as laser welding or combined welding processes, for example, laser hybrid welding, are also conceivable. These are particularly advantageous because the high local heat is quickly dissipated via the metallic materials, and wood materials experience little local thermal change, such as charring. FSW, friction stir welding, is also conceivable. Resistance welding processes such as seam welding are also conceivable. It can be provided that the first sub-element 2 is formed from flat sheet metal blanks that are joined to form a rectangular shell by a welding process.It may be provided that the first sub-element 2 is formed from a single piece by a roll forming process or slide drawing process from a metallic sheet and is joined to form a closed shell by a single joining seam.

[0079] Figure 3 shows further embodiments. a) shows an embodiment in which the first sub-element 2 forms an overlap joint, so that the free end sections of the first sub-element lie on top of each other. A joining joint (not shown) can thus be executed as a fillet weld or a butt weld. Furthermore, a friction stir weld or resistance roll weld and other welding processes are conceivable. Each joining process can also be executed as an interrupted weld and be made tight by a sealant as a sealing envelope. Likewise, the overlap joint can be joined by a brazing process. b) shows an embodiment as a roll forming joint. In this joining process, the seal can be achieved by the force-fit forming or by a sealant and / or adhesive. The particularly economical production of the roll forming joint is advantageous here.In combination with sealants, the tab formed in this way can be used as an attachment tab and pierced by connecting elements without compromising the seal. Figure c) shows an embodiment as an attachment tab. A joining connection can be executed as an end weld with an overlap. A flanged end weld is also conceivable. Stitch welds spaced apart from the free end sections are particularly advantageous. The tab formed in this way can be used as an attachment tab and pierced by connecting elements without compromising the seal. The use of sealants and / or adhesives is also conceivable.

[0080] Figure 4 shows a possible embodiment of a second component 3 consisting of different materials. For example, a second component 3 can consist of a first wood-based material 6, a second wood-based material 7, and a third wood-based material 8. The different wood-based materials are connected via core joints 20. These core joints can be produced by gluing flat surfaces. It is also conceivable that the core joints are formed by tongue-and-groove elements or finger joints. The use of other components (not shown), such as nails, pins, screws, or staples, is also possible for manufacturing. The second component 3 can also be joined along its longitudinal extent. In this case, identical first wood-based materials 6 can, for example, be joined along their longitudinal extent by core joints.Similarly, second wood-based materials 7 and third wood-based materials 8 can be joined longitudinally from sections via core joints. The advantage here is the economical use of wood-based materials that are joined from sections to form second sub-elements 3. It is also conceivable that the second sub-element

[0081] 3 consists of different wood materials in the longitudinal dimension.

[0082] Figure 5 shows an embodiment in which both sub-element 3 and sub-element 2 are each composed of two elements. A further sub-element 10 is connected to sub-elements 2 and 3 via the joining points 4. Sub-element 10 further subdivides sub-section 3, which can be composed of several wood-based materials 6 and 7. Sub-element 2 and sub-element 10 form sheath-like coverings for sub-elements 3. The second sub-elements can consist of different materials, as indicated by different hatching. A second sub-element 3, as shown in Figure 4, can also consist of different wood-based materials.

[0083] Figure 6 shows an embodiment of a composite beam 1, which is connected to an attachment 12 via a connecting element 14 to the mounting lug 13 formed on the composite beam 1. The composite beam 1 has an additional joining element 11, which can be, for example, a screw or pin. It is also conceivable that the joining element 11 is a rivet nut or a screw, which allows for force transmission or fastening of further attachments. An advantage of the joining element 11 is the use of sealant and / or adhesive to ensure the tightness of the sheath-like enveloping surface. Likewise, it is advantageous to use sealant and / or adhesive in the formation of the mounting lug 13 to ensure tightness through the connecting element 14, for example, a screw.

[0084] Figure 7 shows a composite beam structure 17 consisting of a composite beam 1 and connection elements 15. The connection element 15 can, for example, be a flange plate. The joint of the composite beam 1 and the connection elements 15 encloses a second component, for example, a wood core. This core can consist of a first wood-based material 6 and a second wood-based material 7 and be joined via a core joint 20, as shown in a cutout of the composite beam 1. Advantageously, the enclosure is tightly constructed. Figure 8 shows a composite beam 1 with a machining operation 16, which is joined to form a composite beam structure 17. The use of miter cuts to create a shell-like enclosure is advantageous here.Likewise, it is advantageous if the machining operation 16 does not completely cut through the composite beam 1, but rather a part of the first sub-element is not cut through, but is formed into a composite beam structure by deformation and joined by joints.

[0085] Fig. 9 shows that an adhesive and / or sealant 18 is provided between the first sub-element 2 and the second sub-element 3, wherein the adhesive or sealant is designed in such a way that a tight coating of the second sub-element 3 is ensured, even if a connecting tab is pierced by a connecting element, in particular a screw or rivet.

[0086] Figures 10a and 10b show a multi-layered structure with thermal decoupling between an inner and an outer layer, wherein the first sub-element 2 is separated from the second sub-element 3 by an intermediate layer 19 made of wood or air to avoid thermal bridges and to protect temperature-sensitive components, in particular battery cells, which may be housed in the first sub-element 3, from thermal influences, and wherein the composite support 1 optionally includes reinforcing elements, such as strips or smart materials, in particular expanding polyurethane foam (PU foam), to secure the connection. The outer face layer according to the first sub-element 2 can, for example, consist of steel, specifically of two separate components: steel sheet 1 and steel sheet 2. Such structures are typical for sandwich composites or hybrid materials, for example in tailored blanks or lightweight panels.Between the two steel sheets is the core, which consists of a lighter or functionally adapted material – such as foam, wood, plastic, or fiber-reinforced composites. This core performs structural functions (e.g., stiffness, damping) or contributes thermal properties (e.g., insulation, heat storage). The core material acts as a separating or decoupling layer between steel sheet 1 and steel sheet 2. If, for example, steel sheet 1 heats up as a result of a process, environmental influences, or a malfunction, the resulting heat must be conducted through the core material to affect steel sheet 2. This can enable thermal delays, insulating effects, or targeted temperature gradients – depending on the properties of the core material.

[0087] According to Figs. 11 a and 11 b, it can be provided that the first partial element 2 is joined by forming it into a shell-shaped covering enclosing the second partial element 3, by providing a groove 21 in the second partial element 3 for receiving opposite ends 2a, 2b of the first partial element 2.

[0088] In Fig. 11b, a swelling body 22 was provided with a swelling agent so that it fills the groove 21 and thus tightly seals the ends 2a and 2b. Materials with pronounced swelling and shrinkage behavior, such as certain fiber materials and / or wood, can be used as swelling bodies.

[0089] The groove 21 can be wedge-shaped, widening towards the interior of the second sub-element 3. Further variations are shown in Figures 11c and 11d.

[0090] Figures 12a and 12b show variants in which the joining was produced by forming. The first component 2 has ends 2a and 2b that are bent at an angle of at least 90°, preferably more than 90°, and interlock in a force-fit manner. The connection can be free of material bonding and simply rely on mechanical force. For example, such shaped sheets can be slid onto wooden supports.

[0091] As shown in Fig. 12a, the first sub-element 2 can be made from a single piece, which is closed at its two ends to form a mantle-like shell enclosing the second sub-element 3. As shown in Fig. 12b, the first sub-element 2 can be made from two shells 2' and 2" which extend opposite each other along the longitudinal extent of the second sub-element 3 and each have two ends at which the shells 2' and 2" are connected to each other. The first sub-element 2 can thus be slid onto the second sub-element 3 particularly easily by simply attaching the two shells 2' and 2" to the second sub-element 3 from opposite sides.

[0092] Figures 13a and 13b show a composite beam 1 with a broad side 1a and a narrow side 1b. Figure 13a shows a perspective view and Figure 13b a side view of the beam 1 under load. The load causes the beam to bend, with a neutral fiber defining the area in the beam 1 where the side subjected to compression transitions into the side subjected to tension.

[0093] Accordingly, the composite beam 1 can be provided with a rectangular profile cross-section with a broad side 1a and a narrow side 1b, wherein the broad side is, for example, at least 20%, preferably at least 50%, and in particular at least 100% larger than the narrow side, wherein a joining connection 4 produced by the joining method, for example in the form of a weld, is made along the longitudinal extent of the composite beam 1, specifically on the broad side, in the region between 40% and 60% of the height of the broad side, and in particular between 45% and 55%. The neutral axis 23 lies in this region. Ideally, the joining connection 4 is placed directly at the level of the neutral axis 23, so that the mechanical stress on the neutral axis 23 is minimized. Typically, the composite beam 1 is used in such a way that the broad side 1a is oriented so that the load acts on the narrow side and the broad side 1a is supported against bending.When used as a roof beam, the broad side 1 a would be vertically oriented in such a case and the narrow side 1 b would be horizontally oriented.

[0094] The attachment to the neutral fiber 23 can also be carried out independently of the size ratio of the broad side to the narrow side. Independently of or in addition to the aspects of the invention already mentioned, the first sub-element (2) can be profiled and contain structures such as waves, beads, or pockets, which increase the buckling stiffness of the first sub-element 2 and / or are designed to accommodate reinforcing fibers or other reinforcing elements. These are fibers that can act as mechanical reinforcement in a composite material. These can be synthetic fibers such as glass fibers (known from glass fiber reinforced plastics - GFRP), carbon fibers (known from carbon fiber reinforced plastics - CFRP), aramid fibers (e.g., Kevlar), as well as natural or biological fibers, such as hemp, jute, or viscose fibers.

[0095] From a mechanical perspective, these fibers primarily absorb the tensile forces within the composite. They act as reinforcing elements, significantly increasing the strength and stiffness, particularly on the tension side of a component. If the fibers are applied only to one side—the tension side—of the component, the neutral axis within the cross-section shifts. This means that the fibers absorb a greater proportion of the strain, as they are located on the side subjected to tension. Simultaneously, the opposite side experiences greater compressive stress. This redistribution of stresses leads to a higher overall strength of the component—especially with regard to bending stresses.

[0096] Fig. 14 shows a cross-sectional view of a composite beam 1 with an integrated guide element 24, in particular a metal tube 24. The metal tube 24 serves to guide a connecting element (not shown in detail), in particular a screw, through the second sub-element 3. The connecting element can be clamped against the metal tube. This prevents the connection from loosening due to hygroscopically induced expansion or contraction of the second sub-element 3.

[0097] It may be provided that the second sub-element 3 consists of two or more different components, the proportion of which in the cross-section of the second sub-element 3 varies along its longitudinal extent, so that in conjunction with the enclosing first sub-element 1, in the event of an overload, at least one predetermined yield zone is created in which the composite beam 1 first deforms mechanically.

[0098] Energy absorption occurs through flowing deformation, and the flow properties can be specifically varied by filling; for example, different material properties and / or fillings along the longitudinal axis. It is possible, for instance, to create not only a "designed buckling zone" in the middle, but also, or additionally, at the edges. Overloading can be preceded by slow deformation that stops before leading to fracture. Furthermore, it is possible to insert screws or nails to influence the flow properties.

[0099] The wooden core can also be functionally adapted – for example by:

[0100] • Geometric profiles, such as cutouts or cavities for weight reduction,

[0101] • Density profiles, such as targeted combinations of lightweight and dense wood-based materials,

[0102] • Material zones, for example through the use of plywood or fiber-reinforced plywood in high-stress areas and wood foam or honeycomb structures in less stressed zones.

[0103] The first sub-element 2 may have a wall thickness between 0.1 mm and 6 mm. Depending on the application, thinner wall thicknesses, e.g., from 0.1 mm to 1 mm, or thicker wall thicknesses are conceivable. Generally, thicknesses between 1 and 6 mm are possible. Any values ​​in between or other overlap ranges are also conceivable. Thin wall thicknesses are particularly practical in combination with sheet metal screws. The metallic sheathing can be made of various sheet metal-formable materials (e.g., steel, aluminum). The sheathing is applied either on one or both sides and serves to increase dimensional stability and crash safety.

[0104] The exemplary embodiments show possible embodiments, whereby it should be noted at this point that the invention is not limited to the specifically illustrated embodiments of the same, but rather various combinations of the individual embodiments are also possible and this possibility of variation lies within the skill of the person skilled in this technical field due to the teaching for technical action by the present invention.

[0105] The scope of protection is defined by the claims. However, the description and drawings must be consulted for the interpretation of the claims. Individual features or combinations of features from the different embodiments shown and described can, in themselves, represent independent inventive solutions. The problem underlying these independent inventive solutions can be found in the description.

[0106] All references to value ranges in this description are to be understood as encompassing any and all sub-ranges thereof, e.g. the reference 1 to 10 is to be understood as including all sub-ranges, starting from the lower limit 1 and the upper limit 10, i.e. all sub-ranges begin with a lower limit of 1 or greater and end with an upper limit of 10 or less, e.g. 1 to 1.7, or 3.2 to 8.1, or 5.5 to 10.

[0107] For the sake of clarity, it should be noted that, for better understanding of the structure, some elements have been shown not to scale and / or enlarged and / or reduced in size. List of reference symbols

[0108] 1 composite beam (optionally with wide side 1a and narrow side 1b)

[0109] 2 First sub-element (optionally with ends 2a and 2b and shells 2' and 2")

[0110] 3 Second sub-element

[0111] 4 Joining connection

[0112] 5 Exclusion

[0113] 6 First wood-based material

[0114] 7 Second wood-based material

[0115] 8 Third wood-based material

[0116] 9 Roll forming

[0117] 10. Further sub-element

[0118] 11 Joining element

[0119] 12 Attachment part

[0120] 13 Mounting bracket

[0121] 14 Connecting element

[0122] 15 Connection element

[0123] 16 Edit

[0124] 17 Composite girder structure

[0125] 18 Overlap

[0126] 19 Adhesive / Sealant

[0127] 20 Core joining point

[0128] 21 Nut

[0129] 22 source bodies

[0130] 23 Neutral fiber

[0131] 24 guide element

Claims

Patent claims 1. Composite beam (1) comprising at least a first sub-element (2) and at least a second sub-element (3), wherein the first sub-element (2) encloses the second sub-element (3) in a cladding-like manner, characterized in that the first sub-element (2) consists of at least one metallic material and is joined to form a cladding-like shell enclosing the second sub-element (3) by a material-bonding joining process, in particular welding processes, and / or joining processes by forming, in particular flanging, and the second sub-element (3) consists of a wood-based material and / or a wood-based material.

2. Composite beam (1) according to claim 1, wherein the second sub-element (3) has a longitudinal extent and the first sub-element (2) surrounds the second sub-element (3) in a shell-like manner along its entire longitudinal extent, wherein it is particularly provided that the first sub-element (2) is joined along its longitudinal extent by means of a welding process to form a self-contained shell.

3. Composite beam (1 ) according to claim 1 or 2, wherein the first sub-element (2) is formed from a metallic sheet by means of a roll forming process and the second sub-element (3) is enclosed by the first sub-element (2) and is at least partially joined by means of a joining process, in particular a welding process, along a longitudinal extent of the composite beam (1 ).

4. Composite beam (1 ) according to one of the preceding claims, wherein the second sub-element (3) has at least one recess (5) along a longitudinal extent which exposes the first sub-element (2) along a joining connection produced by the joining method.

5. Composite beam (1 ) according to one of the preceding claims, wherein the second sub-element (3) consists of at least two different wood-based materials and / or wood-based materials.

6. Composite carrier (1 ) according to one of the preceding claims, wherein the first sub-element (2) and the second sub-element (3) are joined at at least one contact surface by an adhesive and / or sealant (19).

7. Composite beam (1 ) according to one of the preceding claims, wherein the first sub-element (2) and the second sub-element (3) have an additional joining element (11) on at least one contact surface, in particular a nail, pin or screw, which additional joining element (11 ) additionally connects the first sub-element (2) to the second sub-element (3).

8. Composite beam (1 ) according to one of the preceding claims, wherein the first part element (2) forms a shell around the second part element (3) in a mantle-like manner, which encloses the second part element (3) in a way that is airtight and moisture-proof, in particular completely airtight.

9. Composite beam (1 ) according to one of the preceding claims, wherein the first sub-element (2) and the second sub-element (3) are designed such that the composite beam (1 ) has different cross-sections in a longitudinal extent, in particular a pyramidal shape and / or cross-sections are not arranged in a straight line in a longitudinal extent, in particular in a curved arrangement.

10. Composite beam (1 ) according to one of claims 1 to 8, wherein the first sub-element (2) is formed from flat sheet metal blanks which are joined to form a rectangular shell by a welding process.

11. Composite beam (1) according to one of the preceding claims, wherein the first sub-element (2) is formed from a single piece by a roll forming process or slide drawing process from a metallic sheet and is joined to form a closed shell by a single joining seam.

12. Composite beam (1 ) according to one of the preceding claims, wherein the first sub-element (2) consists of two half-shells, wherein the second sub-element (3) is inserted between the half-shells, wherein it is particularly provided that the two half-shells are joined together in their longitudinal extent by a welding process.

13. Composite beam (1 ) according to claim 12, wherein the two half-shells of the first sub-element (2) are made of different metallic materials and / or have different wall thicknesses, wherein it is preferably provided that at least one half-shell is made of a fine-grained steel with increased tensile strength.

14. Composite beam (1 ) according to one of the preceding claims, wherein the first sub-element (2) has different material properties along its longitudinal extent, in particular by using sheet metal parts which are joined together from several individual sheets with different material properties - such as thickness, strength, coating or alloy - to form a single, functionally optimized component, sheet metal stacks with different material grades and / or sheet thicknesses.

15. Composite beam (1 ) according to one of the preceding claims, wherein the first sub-element (2) rests directly on the second sub-element (3) and is connected by means of a welding process without a recess (5) being provided.

16. Composite beam (1 ) according to one of the preceding claims, wherein a material-bonded connection between the first sub-element (2) and the second sub-element (3) is produced by a soldering process, wherein the solder wets the metallic material of the first sub-element (2) in a molten state.

17. Composite beam (1 ) according to one of the preceding claims, wherein a joining connection (4) produced by the joining process is supported by a combination of a welding or soldering process with an adhesive and / or sealant (18), wherein the adhesive or sealant is designed such that a tight covering of the second sub-element (3) is ensured even if a connecting tab is pierced by a connecting element, in particular a screw or rivet.

18. Composite beam (1 ) according to one of the preceding claims, wherein a connecting tab is formed by free end sections of the first sub-element (2) and the joining connection (4) is arranged spaced apart from these free end sections, so that the connecting tab projects beyond the joining connection and can be penetrated by connecting elements without impairing the tightness of the shell enclosing the second sub-element (3).

19. Composite beam (1 ) according to one of the preceding claims, wherein the composite beam (1 ) has a joining element (11 ), in particular a screw, a pin or a ring screw, for introducing a tensile load, which joining element (11 ) engages through the first sub-element (2) into the second sub-element (3).

20. Composite beam (1) according to one of the preceding claims, wherein a joining connection (4) produced by the joining process is produced by one of the following processes: high-frequency induction (HFI) resistance pressure welding, arc welding with or without filler material, beam welding, in particular laser welding or laser hybrid welding, friction stir welding (FSW) or resistance roll seam welding.

21. Composite beam (1 ) according to one of the preceding claims, wherein the second sub-element (3) consists of a first wood-based material (6), a second wood-based material (7) and a third wood-based material (8), wherein these are connected to each other via core joints (20), in particular by gluing, tongue and groove jointing, finger jointing or additional mechanical form elements such as nails, pins, screws or staples.

22. Composite beam (1 ) according to claim 21 , wherein the wood materials (6, 7, 8) of the second sub-element (3) are arranged segmented in longitudinal extension and are connected via core joints (20), thereby achieving a targeted gradation of the mechanical properties along the longitudinal axis of the composite beam (1 ).

23. Composite beam (1 ) according to one of the preceding claims, wherein the length of the composite beam is at least 1 m, wherein the length of the first sub-element (2) is at least the length of the second sub-element (3), and preferably exceeds this length.

24. Composite beam (1 ) according to one of the preceding claims, wherein the first sub-element (2) substantially surrounds the second sub-element (3) in a form-fitting manner.

25. Composite beam (1 ) according to one of the preceding claims, wherein the second sub-element (3) has a coating on its outside which prevents moisture from entering the second sub-element (3) and is also at least partially encased by the first sub-element (2).

26. Composite beam (1 ) according to one of the preceding claims, wherein the second sub-element (3) consists of two or more different components, the proportion of which to the cross-section of the second sub-element (3) varies along its longitudinal extent, such that in conjunction with the enclosing first sub-element (1 ) at least one predetermined yield zone is created in the event of an overload. is in which the composite beam (1) first deforms mechanically.

27. Composite beam (1 ) according to one of the preceding claims, wherein the first partial element (2) has a wall thickness between 0.1 mm and 6 mm.

28. Composite beam (1 ) according to one of the preceding claims, wherein the first sub-element (2) and the second sub-element (3) are joined by at least one of the following alternative joining methods: - a welding process, in particular Cold Metal Transfer (CMT), - a positive-locking click connection with mechanical barbs or locking lugs, - an adhesive bond using structural adhesive, - a connection using through-hole needle or pin connections, - or a dovetail joint.

29. Composite beam (1 ) according to one of the preceding claims, wherein the first partial element (2) has ends (2a, 2b) which are bent at an angle of at least 90° and interlock forcefully.

30. Composite beam (1 ) according to one of the preceding claims, wherein the first sub-element (2) consists of a single piece which is closed over its two ends to form a mantle-shaped shell enclosing the second sub-element (3).

31. Composite beam (1) according to one of the preceding claims, wherein the first sub-element (2) consists of two shells (2', 2") which extend opposite each other along the longitudinal extent of the second sub-element (3) and which each have two ends via which the shells are connected to each other.

32. Composite beam (1) according to one of the preceding claims, wherein the composite beam (1) has a rectangular profile cross-section with a broad side (1a) and a narrow side (1b), wherein the broad side is at least 20%, preferably at least 50%, in particular at least 100% larger than the narrow side, wherein a joining connection produced by the joining method is made of the first partial element (2) along the longitudinal extent of the composite beam, namely on the broad side, in the area between 40% and 60% of the height of the broad side, in particular between 45% and 55%.

33. Composite beam (1 ) according to one of the preceding claims, wherein the first partial element (2) is joined by forming a shell-shaped covering enclosing the second partial element (3) by providing a groove (21 ) in the second partial element (3) for receiving opposite ends (2a, 2b) of the first partial element (2).

34. Composite beam (1 ) according to claim 33, wherein the groove (21 ) is wedge-shaped and widens towards the interior of the second sub-element (3).

35. Composite beam (1 ) according to claim 33 or 34, wherein the composite beam has a swelling body (22) which is arranged in the groove (21 ) and presses the opposing ends (2a, 2b) against inner sides of the groove (21 ).

36. Composite beam (1 ) according to one of the preceding claims, wherein the first sub-element (2) is profiled and contains structures such as waves, beads or pockets which increase the buckling stiffness of the first sub-element (2) and / or are designed to accommodate fibers or reinforcing elements.

37. Composite beam (1) according to one of the preceding claims, wherein the composite beam (1) comprises a multi-layered structure with thermal decoupling between an inner and an outer layer, wherein the first sub-element (2) is separated from the second sub-element (3) by an intermediate layer (19) of wood or air to avoid thermal bridges and temperature-sensitive to protect components, in particular battery cells, which may be included in the first sub-element (3), from thermal influences, and wherein the composite carrier (1) optionally comprises reinforcing elements, such as strips or smart materials, in particular expanding polyurethane foam (PU foam), to secure the connection.

38. Composite beam (1) according to one of the preceding claims, wherein a metallic guide element, in particular a metal tube, is embedded within the second sub-element (3) for the passage of a connecting element, in particular a screw, wherein the connecting element is clamped against the guide element, so that no loosening of the connection occurs due to hygroscopically induced expansions or shrinkages of the second sub-element (3).

39. Composite beam structure (17) comprising at least one composite beam (1 ) according to one of the preceding claims and at least one further metallic sub-element, wherein the at least one composite beam (1 ) is firmly connected, in particular welded, to at least one further metallic sub-element, in particular a connecting element (15).

40. Composite beam structure (17) according to one of the preceding claims, wherein a first composite beam (1 ) is connected to a second composite beam (1 ).

41. Method for producing a composite beam (1) from at least one first sub-element (2) and at least one second sub-element (3), wherein the first sub-element surrounds the second sub-element in a cladding manner, characterized in that the first sub-element (2) is arranged around the second sub-element (3) so that the second sub-element (3) is encased in a cladding manner, wherein free end sections of the first sub-element (2) are connected together to form a closed cladding.

42. Method according to claim 41, wherein the second sub-element (3) is completely enclosed by the first sub-element (2) and all free end sections of the first sub-element (2) are connected to each other and the second sub-element (3) is completely tightly enclosed. B: Alternatively, partial encasing is also possible - both longitudinally and end-faced 43. Method according to claim 41 or 42, wherein the first sub-element (2) is arranged around the second sub-element (3) so that the second sub-element (3) is enveloped in a mantle-like manner, wherein free end sections of the first sub-element (2) are joined together to form a closed mantle and a forming gas is introduced during the joining process.

44. Method according to one or claims 41 to 43, wherein the second sub-element (3) has at least one recess (5) along a longitudinal extent, whereby the first sub-element (2) is exposed along a joining connection (4) produced by the joining method, and wherein a cavity is formed via the recess (5) provided in the second sub-element (3), through which shielding gas is introduced into the welding zone during the production of the composite beam (1) to enable the formation of the joining connection (4).

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