DEVICE, IN PARTICULAR COMPOSITE BEAMS, AND METHOD FOR MANUFACTURING AND DISMOUNTING THE DEVICE

Description

[0001] The invention relates to a device, in particular a composite support, and a method for producing and dismantling the device.

[0002] Beam-like devices or load-bearing elements are designed to absorb loads and are available in various materials in the state of the art. Steel beams, in particular, are used in construction due to their high load-bearing capacity. Timber beams, on the other hand, are also used for construction purposes and are a particularly environmentally friendly material for building projects.

[0003] For the reasons mentioned above, the use of wood as a material would often be desirable, but the durability of wood in outdoor applications has been a major challenge for wood technology and the use of wood in technical elements for decades. Particularly when load-bearing components or beams are subjected to static and dynamic loads, this requirement very quickly becomes a limiting factor, as wood loses strength and stiffness, sometimes dramatically, over longer periods of time due to abiotic and biotic degradation.

[0004] The use of wood in technical applications presents technological and process engineering challenges. This highly anisotropic material and raw material requires precise material knowledge for its application. On the other hand, homogeneous and isotropic materials such as steel and plastic have enabled innovative, efficient, and cost-effective solutions to be realized. While many of these solutions would have been technically feasible with wood, they were economically uncompetitive due to the more complex and labor-intensive shaping required.

[0005] Furthermore, calculations are easier for homogeneous materials such as plastics and metals, making them easier to control. This ability to calculate wood has only been available relatively recently.

[0006] Wood has also been widely used in a wide variety of technical products and devices in the past. An additional disadvantage of wood is its relatively low energy absorption in the event of fracture due to its brittle tensile failure. In tensile failure, sharp-edged fracture surfaces are primarily observed, which can lead to an increased risk of injury to people involved, for example, in accidents.

[0007] Chemical and / or physical wood modification is known to overcome these disadvantages. Various processes are used to completely or partially modify or impregnate wood cross-sections, thereby improving the material's properties. In addition to increased durability and swelling resistance, thermal modification initially results in a slight improvement in mechanical properties (stiffness and strength), a reduction in density, and a reduction in moisture absorption. However, wood modification leads to mechanical changes, such as embrittlement, as well as additional costs.

[0008] Another option for improving the durability of wood is coating it. However, even coatings cannot fully guarantee protection. Impregnation with protective agents incurs additional costs and involves the release of environmentally harmful substances. Plastic coatings, on the other hand, have disadvantages when it comes to disposal and recycling after the component has been used.

[0009] Although wood-metal composites are known to overcome the disadvantages of wood, they represent a group of materials that has so far been rarely used and scientifically and technically investigated.

[0010] Steel is known for its high yield strength and, in contrast to wood, has significantly better, particularly isotropic, strength properties. However, the thermal conductivity of steel is also higher than that of wood, so steel beams are naturally designed to conduct more heat in buildings than wood or similar fibrous materials. Particularly due to weathering, wood's use can be limited compared to other building materials.

[0011] Current considerations involve bonding and screwing together wood and metal components. In some cases, the two materials are joined by a plastic coating. These technical solutions almost always pose significant challenges when it comes to disassembly and recycling.

[0012] The use of additional fasteners, such as holes provided in the beams and the individual components of the composite beam ultimately bolted together, has significant disadvantages. This may require notched cross-sections, which can represent a weak point in a structure's strength, as the required holes for the bolts can lead to the formation of notch cracks. Furthermore, a composite beam formed using fasteners also requires increased manufacturing effort.

[0013] The problem of providing a device that overcomes the disadvantages of the prior art and combines certain advantageous properties of fiber composite materials, in particular wood, and metal can therefore be viewed as a conflict of objectives. It is an object of the present invention to overcome this conflict of objectives. It is a further object of the invention to provide a durable support with improved thermal and strength properties for ecological building and construction projects without forming stress-critical notches that impair the fatigue strength of the support. It is a further object of the invention to create a device, in particular a composite support, that is particularly easy to manufacture, but also disassemble and recycle.

[0014] These and other objects are possibly achieved by a device and the methods having the features of the independent patent claims.

[0015] The present invention is based in particular on the observation that, in particular, hygroscopic fiber composite materials such as wood have the property of strong dimensional change upon absorption of polar fluids, i.e. liquids or gases, in particular upon absorption of water, for example through contact with water or change in air humidity and / or through a change in temperature.

[0016] The incorporation of polar fluids into the fiber composite structure causes the material to increase in volume. In the context of the present invention, this volume increase may also be referred to as swelling. These swelling phenomena can be achieved not only with water but also with various polar liquids and substances, such as salt solutions, alcohols, ammonia, etc. The removal of the fluids from the fiber composite material, in turn, causes a volume reduction, also referred to as shrinkage.

[0017] The volume change occurs only marginally in the longitudinal direction, i.e., in the fiber direction of the fiber composite material, but primarily transversely to the fiber direction. In particular, a swellable fiber composite material, such as wood, within the meaning of the present invention has a main fiber extension direction. The swelling occurs particularly transversely to the main fiber extension direction.

[0018] Swelling and shrinkage are typically considered a major technical disadvantage in wood technology. Thus, prior art often attempts to counteract the volume changes of wood. However, within the scope of the present invention, it has surprisingly been possible to advantageously utilize the swelling properties of fiber composite materials to achieve at least one of the aforementioned objectives.

[0019] Wood composite materials of the type mentioned above are generally known in the prior art. For example, JPH1054108A describes a wood-reinforced tube, but the wood does not swell. JP2000064503A describes a metal rod containing wood, where the wood can be swollen by heating or soaking in water. Finally, JP2019127087A describes wood surrounded by a woven fiber material.

[0020] A device according to the invention comprises a hollow profile-shaped outer body with an interior space and a core arranged in the interior space, wherein the core comprises or is formed from a fiber composite material that swells upon contact with fluid, namely wood. It is provided that the core is swollen in the interior space by a fluid and exerts pressure on the outer body generated by the swelling.

[0021] The core is made of wood or it contains wood.

[0022] The swelling properties, and in particular the hygroscopic properties, of the core enable a permanent bond between the core and the outer body. In particular, this allows at least a frictional connection, in particular a positive and frictional connection, between the core and the outer body, in particular the inner surface of the outer body, to be achieved.

[0023] The volume change of the core due to its swelling subsequently leads to plastic deformation of the core in the area of ​​the contact surfaces between the outer body and the core. This compression zone adjacent to the contact surfaces can also be referred to as the compaction zone. In particular, the resulting compaction of the core transverse to the fiber leads to a significant increase in strength and stiffness along the fiber.

[0024] In addition to wood, fiber composite materials such as nanocellulose can also be used. If necessary, the core can comprise a compressed veneer material.

[0025] Depending on the curvature of the contact surfaces, the maximum equivalent stress in the core acts close to the outer surface of the core, potentially causing compression deformations in the compression zone, resulting in an outward force directed against the outer body. This force, in particular, leads to a normal force at the contact surfaces, forming a frictional connection in the transverse direction of the beam.

[0026] In the context of the present invention, a carrier can be understood as any elongated element or component which is used in particular in

[0027] The longitudinal direction of the beam has a larger dimension than the largest dimension transverse to the longitudinal direction of the beam. A composite beam within the meaning of the present invention can, for example, be a load-bearing composite element. Such a beam can be used, for example, as a beam for building structures, as a pillar of an automobile chassis or body, as a load-bearing element of a lightweight construction, as a beam of a mechanical engineering structure, or the like.

[0028] Optionally, form-locking elements can be provided to achieve an additional form-locking connection between the outer body and the core. Such form-locking elements can be designed in different ways. For example, at least one form-locking extension, for example in the form of a rib, can be arranged on the inner surface of the outer body. The form-locking extension can press into a section of the core when the device is in operation, thereby achieving a form-locking connection. Optionally, the core can also have a form-locking recess into which the form-locking extension engages. The form-locking recess can, for example, be a groove.

[0029] The core and the outer body optionally extend along a common main extension direction, and the hollow outer body preferably encloses the core at least laterally, so that a lateral connection may exist between the outer body and the core. The main extension direction is thus to be regarded in particular as the direction corresponding to the greatest spatial extent of the device. A lateral direction is to be regarded in particular as a direction orthogonal to the main extension direction. The swelling of the core can occur in particular in the radial and tangential directions.

[0030] The cross-section of the support is understood to be, in particular, the surface section that runs transversely to the longitudinal direction. For example, the outer body can be a tube, in which case the cross-section of the outer body is circular and, in particular, closed. The term "closed cross-section" therefore refers, in particular, to a continuous cross-section without interruption, as is the case with a tube cross-section.

[0031] If necessary, the core exerts an internal pressure on the outer body during operation. A pressure that is distributed as evenly as possible allows for the extensive formation of the compression zone, where the compression deformations occur.

[0032] The outer body can also be provided with a closed cross-section. This ensures that deformation of the cross-section is largely avoided when the composite beam is subjected to load. Furthermore, the closed cross-section ensures even pressure distribution between the core and the inner surface of the outer body.

[0033] In particular, it is intended that the pressure exerted by the core on the outer body during operation be at least 3 N / mm 2 , in particular at least 5 N / mm 2 or at least 10 N / mm 2 . Thus, under normal friction conditions between wood and steel, a sufficiently large normal force can be generated so that the core is held in the outer body.

[0034] If necessary, the core is braced within the interior during operation. This allows the core to be held rigidly and, above all, stably within the outer body even under particularly high loads on the composite beam, without causing relative movement at the contact surfaces during beam deformation.

[0035] Preferably, the outer body is designed as a metal profile, in particular a steel profile. This makes it possible to provide an outer body that is particularly well-suited for construction or other structures, for example, automotive, mechanical, or plant engineering. If necessary, the device can be used as an overlay, thus replacing, for example, brick or steel overlays.

[0036] Optionally, it is provided that the core can be inserted and / or removed from the interior in a joined state, wherein the core is more swollen in the operating state due to fluid absorption than in the joined state and / or wherein the core has a higher fluid content in the operating state than in the joined state. In the joined state, the core is, in particular, loosely contained in the outer body, and there is, in particular, no frictional connection between the core and the inner surface of the outer body.

[0037] In particular, the dimensions of the core are selected so that they can be inserted or inserted into the interior of the outer body, such as a shaped tube, an extruded profile, etc., when joined. If necessary, the shape of the core is selected so that the desired cross-section is produced with the material shrinkage during the reduction of the fluid content.

[0038] Optionally, the core and interior can be provided with a clearance fit in the joined state, with the core possibly being undersized relative to the interior. This allows the degree of frictional engagement between the core and outer body in the swollen state to be determined during production. Furthermore, the core can be easily removed from the interior of the outer body in the joined state.

[0039] The core can be designed to completely fill the interior of the outer body during operation. This allows the outer surface of the core to be completely enclosed by the outer body, creating a strong connection between the two bodies.

[0040] The core is intended to be enclosed in a fluid-tight manner during operation. This protects the core from fluid loss and shrinkage in the swollen state. In particular, this ensures the long-term stability of the device.

[0041] Preferably, the core is enclosed in a fluid-tight manner by the outer body and by at least one closure arranged on the outer body. This allows a further measure to be taken to prevent fluid loss. Alternatively or additionally, the core can be enclosed in a fluid-tight manner with a coating. In the context of the present invention, fluid-tight refers in particular to the property of a material to be substantially impermeable to a fluid, in particular the fluid that causes the core to swell. For example, in the case where the fluid is water, fluid-tight means in particular that the material is substantially impermeable to water in liquid and gaseous form.

[0042] Optionally, the fluid is selected from one or more of the following: water, saline solution, alcohols, ammonia. A preferred fluid is water. This allows the hygroscopic effect of wood to be utilized.

[0043] In particular, the core is provided with a compression zone along its outer circumference. This allows the normal force for the frictional connection to be generated as a result of the core's deformation. In addition, the mechanical properties of the core material are further improved in the compression zone.

[0044] If necessary, the pressure generated by the swelling increases the stress along the circumference of the profile cross-section of the outer body. This allows a prestressed device to be formed.

[0045] It can be provided that an outer surface of the core is at least partially in direct contact with the inner side of the outer body, and / or that a connecting layer, for example an adhesive layer, is arranged between the outer surface of the core and the inner side of the outer body. This can provide a further measure to prevent relative movement between the core and outer body at the contact surfaces. Optionally, it can also be provided that the surface of the core is treated to improve the frictional connection. For example, the surface of the core can be roughened.

[0046] A frictional connection between the outer body and core can also be improved by coating the wood surface with substances that increase the coefficient of friction or the adhesion properties to the inner surface of the outer body. Substances that increase the coefficient of friction can be, for example, coatings containing corundum. Substances that increase the adhesion properties can be, for example, contact adhesives.

[0047] Especially when increasing adhesion properties, it may be preferable to apply corresponding coatings to the inside of the outer body as well. The interaction of both coatings can lead to chemical reactions, resulting in higher friction values ​​or adhesion between the two materials.

[0048] If necessary, the connection between the core and the outer body can be improved by oxidizing the outer surface of the core and / or the inner surface of the outer body.

[0049] If necessary, the bond between the core and the outer body can be improved by chemically treating the core surface. The treated core may then react with the inner surface of the outer body.

[0050] If necessary, the connection between the core and the outer body can be improved by mechanical treatment of the outer body, for example by embossing and / or rolling.

[0051] Additional flat or point-acting sensors, in particular pressure sensors, can be attached to the contact surface between the core and the outer body in order to monitor, for example, the swollen state of the core.

[0052] The outer surface of the core can also support conductor tracks for power and signal transmission.

[0053] Optionally, the core is designed as a hollow body, which optionally has a cavity extending substantially in its longitudinal direction, in particular open on at least one side. This allows the fluid for swelling the core to be more easily introduced and removed again as needed. Optionally, the core can be designed as a hollow profile.

[0054] The cavity can also be used, if necessary, to insert pipes for gas or liquid transport or conductor tracks into the device after the swelling process.

[0055] An inner profile body, such as a tube, can be arranged in the cavity. The core may also exert pressure on the inner profile body, generated by swelling.

[0056] Optionally, the fluid may be water, and / or the fluid content of the core in the operating state may be at least 1 wt.%, in particular 5 wt.%, preferably 10 wt.%, higher than in the joined state. This may allow sufficient swelling to be achieved.

[0057] In particular, it is provided that the outer body and the core are frictionally connected to each other.

[0058] If necessary, it is provided that the outer body has at least one form-fitting element, in particular a form-fitting extension, on its inner side for the form-fitting connection between the outer body and the core.

[0059] Optionally, the core may have at least one form-fitting recess for engagement of a form-fitting extension. Optionally, the core may be thermally modified, in particular by heat treatment at at least 120°C, preferably at approximately 200°C. In particular, the core may be thermally modified by heat treatment between 120°C and 250°C. Optionally, the core may be thermally modified by heat treatment for at least 5 minutes, preferably for at least 10 minutes. Optionally, the core may be thermally modified by heat treatment for a maximum of 30 minutes. This may improve the mechanical properties of the core.

[0060] Furthermore, the invention optionally encompasses a method for producing a device, in particular a composite support. The device comprises, in particular, a hollow profile-shaped outer body with an interior space and a core arranged in the interior space, wherein the core comprises or is formed from a fiber composite material that swells upon contact with fluid, namely wood.

[0061] Where appropriate, the procedure includes the following steps: (a) providing the core, wherein the core has a first fluid content, (b) introducing the core into the interior of the outer body, (c) increasing the fluid content of the core such that the core is swollen by the fluid and exerts a compressive force generated by the swelling on the outer body, wherein the core has a second fluid content.

[0062] In this way, a device according to the invention can be formed in an advantageous manner, wherein in particular there is a frictional connection between the outer body and the core.

[0063] Optionally, it is provided that the fluid is water, and / or that the second fluid content is at least 1 wt.%, in particular at least 5 wt.%, preferably at least 10 wt.%, higher than the first fluid content. In this way, sufficient swelling can be achieved, in particular, for the connection between the outer body and the core.

[0064] If necessary, the core and interior space are provided with a clearance fit in step (b). This allows, in particular, the acting normal force for the connection in the operating state to be determined.

[0065] Optionally, it is provided that the fluid is water, and that the first fluid content is at most 10 wt.%, in particular at most 5 wt.%, and / or that the first fluid content is below the equilibrium moisture content of the fiber composite material of the core at a temperature of 20°C and a relative humidity of 50%. In particular, the first fluid content can be at least 5 wt.%, optionally at least 10 wt.%, below the equilibrium moisture content of the fiber composite material of the core at a temperature of 20°C and a relative humidity of 50%.

[0066] If necessary, the moisture is largely or completely removed from the core through drying or other processes. This water removal causes the wood to lose volume. This allows the core to be inserted into the interior of the outer body in the assembled state.

[0067] Optionally, the method further comprises the following step: (d) forming form-locking elements by deforming the outer body. This allows additional constraining forces to be achieved between the outer body and the core, securing the bodies to one another.

[0068] Optionally, the method may further comprise the following step: (d) rolling the device. This allows the core to be densified, further improving the mechanical properties.

[0069] If necessary, the core is wetted with liquid and / or gaseous water between step (a) and step (b).

[0070] If necessary, the core is chemically treated before step (b), for example with ammonia, to enable better swelling.

[0071] The present invention further relates to a method for dismantling a device, in particular a composite beam. The device optionally comprises a hollow profile-shaped outer body with an interior space and a core arranged in the interior space, wherein the core comprises or is formed from a fiber composite material that swells upon contact with fluid, namely wood.

[0072] Where appropriate, the procedure includes the following steps: (a) providing the device, wherein the core in the interior is swollen by a fluid and exerts a compressive force generated by the swelling on the outer body, wherein the core has a second fluid content, (b) reducing the fluid content of the core so that the core has a first fluid content, (c) removing the core from the outer body.

[0073] This means that a device can be separated again if necessary and its individual parts can be recycled separately.

[0074] Optionally, the reduction of the fluid content of the core in step (b) is achieved by heating the core. This allows the pressure acting between the outer body and the core to be reduced, so that, in particular, there is no longer any frictional and / or positive connection between the outer body and the core.

[0075] Optionally, it is provided that the fluid is water, and / or that the second fluid content is at least 1 wt.%, in particular at least 5 wt.%, preferably at least 10 wt.%, higher than the first fluid content. This, in particular, can achieve the required shrinkage to release the connection.

[0076] Where appropriate, it is intended that the core and interior have a clearance fit in step (c).

[0077] In a device it can also be provided that the fibers of the core run essentially in the main extension direction of the core.

[0078] The cross-section of the core and / or outer body can be quadrangular, in particular rectangular or square, round, polygonal, hyperbolic, convex, concave, trapezoidal, elliptical, hexagonal, manifold, rhomboidal, deltoidal, T-shaped, U-shaped, or even polygonal. This allows a suitable cross-section to be provided for different applications.

[0079] Where appropriate, it is intended that in the operating state the structural mechanical compression energy of the core corresponds to the structural mechanical expansion energy of the outer body.

[0080] Where appropriate, it is provided that the radial cross-section of the device has the same area moment of inertia around both principal stress axes.

[0081] The core may be formed as a single piece or in multiple parts. For example, the core may comprise several separate sections.

[0082] Where appropriate, it is provided that the cross-section of the device has different area moments of inertia around both principal stress axes and / or that the shape of the core is adapted to the shape of the interior.

[0083] If appropriate, the device, in the assembled state, has a dimension that allows the core to be inserted and removed from the interior of the outer body, and, in the operating state, the device has a swollen dimension so that a firm connection exists between the core and the outer body. If appropriate, this dimension is an oversize or undersize of a clearance fit.

[0084] If necessary, it is provided that the enrichment of the core with a fluid is reversible, whereby after a reduction of the fluid content, in particular the wood moisture content, in the core, the core is removed from the outer body again.

[0085] In additional embodiments, the following features may additionally or alternatively be provided in a device and / or method of the invention: Optionally, a recyclable joining technique for wood-metal composites is provided. The core and outer body are joined, in particular, using a hydrothermal process and, if necessary, separated again. Wood, a particularly hygroscopic material, may have the property of changing volume upon moisture absorption through contact with water or changes in air humidity and / or temperature.

[0086] The incorporation of water into the wood structure of a core can cause an increase in volume. This property can be referred to as swelling.

[0087] In the case of water, the volume increase may occur in a wood moisture content range of 0 to approximately 30 wt%, the fiber saturation range. Above this value, no volume changes are usually observed.

[0088] If necessary, the core is or will be pre-compacted to promote subsequent compaction during swelling. Due to the compression force that occurs during wood swelling (theoretical compression force of a lignified cell wall is approximately 500 N / mm²) and the low transverse compressive strength of wood (depending on the wood species, in the range of approximately 1 to 15 N / mm²), the wood material of the core may be compressed by the outer body.

[0089] Plastic deformation of wood in radial or tangential directions can occur more easily at elevated humidity or elevated temperature or after chemical pretreatment.

[0090] If necessary, a multi-layer core can also be constructed from pre-compressed wood layers and other materials, such as ceramics, plastics, metal, metal foams, etc.

[0091] It is also possible to deform the device by applying external pressure. This can be used to change the moment of inertia or to selectively compress the core. Through the swelling process or the additional forming process, the core can be joined to the outer body through positive and frictional engagement. This joint can also be improved by special surface treatments such as roughening or undercuts.

[0092] Furthermore, the device can also be plastically deformed by bending devices, for example a profile rolling machine.

[0093] Pre-compaction of the core can potentially increase stiffness and strength. In particular, the joining process can compact the wood body or core in its edge areas, increasing strength and stiffness and improving the overall mechanical properties of the device. A key advantage of the device is that, if the device is subjected to excessive stress, a ductile fracture occurs with increased energy absorption.

[0094] In particular, the absorbable fracture energy can be further increased by compacting the core. After the increase in volume, the device is sealed on both sides, permanently preserving the swollen state of the wood thanks to the diffusion-tight nature of the metal and the sealing material, such as PU rigid foam or other plastics.

[0095] The end closure of the outer body can be achieved with caps of different shapes and made of different materials. The caps can be connected to the outer body by friction, form, and / or material bonding.

[0096] In case of friction and material adhesion, the caps can be easily removed by turning them down, pulling them off or heating them.

[0097] The device can also be disassembled by removing the fluid-tight enclosure of the core and exposing the device to atmospheric or physical conditions in which the core again loses moisture or other fluids and shrinks. The shrinkage process may continue until the two parts can be separated again.

[0098] A key advantage of the process is that the metal component, or outer body, and the wood component, or core, can potentially be recycled or reused. Furthermore, due to the increased mechanical properties of the composite, the dimensions of the components can be reduced, saving material.

[0099] If the outer shell is made of steel, the recycling process in the blast furnace requires the addition of carbon dioxide and heat. The energy stored in the core and the chemical components can save energy and coal in the recycling process.

[0100] The outer body can also be formed by or comprise another non-swellable and diffusion-tight material such as ceramic, plastic or fiber-reinforced plastic.

[0101] The device of the present invention may provide one or more of the following advantages over conventional geometrically similar steel beams: Improvement in deflection at approximately the same load and mass by at least 2%, if necessary 8%. Reduction in raw material costs at the same mass by up to 40%. Reduction in carbon dioxide emissions during production at the same mass by up to 20%.

[0102] If high cores are used, raw material costs can be reduced by up to 50% and carbon dioxide emissions by up to 40%.

[0103] Further features of the present invention emerge from the description of the embodiments, the figures and the patent claims.

[0104] In the following, the invention is explained in detail using non-exclusive, merely exemplary embodiments. Fig. 1a shows an embodiment of a device according to the invention in a schematic representation in the operating state according to a first embodiment; Fig. 1b shows the device according to the first embodiment in the joining state; Fig. 2a shows an embodiment of a device according to the invention in a schematic representation in the operating state according to a second embodiment; Fig. 2b shows the device according to the second embodiment in the joining state; Fig. 3a shows an embodiment of a device according to the invention in a schematic representation in the operating state according to a third embodiment; Fig. 3b shows the device according to the third embodiment in the joining state Fig. 4a shows an embodiment of a device according to the invention in a schematic representation in the operating state according to a fourth embodiment; Fig. 3b shows the device according to the fourth embodiment in the joining state.

[0105] Unless otherwise stated, the figures show the following features: composite beam 1, outer body 2, core 3, interior space 4, inner surface 5, outer surface 6, form-fitting extension 7, cavity 8, inner profile body 9, outer surface 10.

[0106] Fig. 1a shows an embodiment of a device according to the invention in the operating state according to a first embodiment. Fig. 1a shows the device in a schematic sectional view, wherein the sectional plane is arranged substantially orthogonal to the longitudinal direction of the device.

[0107] The device is designed as a composite beam 1 with a circular cross-section and comprises a hollow profile-shaped outer body 2 with an interior space 4. A core 3 is arranged in the interior space 4. The core 3 swells upon contact with fluid and, in this embodiment, is made of wood. Fig 1a The composite beam is shown in its operating state, meaning the core 3 has swollen. In this state, the core 3 in the interior space 4 has swollen due to water and, as a result of the swelling, exerts pressure on the outer body 2. The outer surface 6 of the core 3 is in direct contact with the inner surface 5 of the outer body 2.

[0108] In other embodiments not shown, a connecting layer, for example an adhesive layer, is arranged between the outer surface 6 of the core 3 and the inner side 5 of the outer body 2.

[0109] In this embodiment, the outer body 2 is designed as a tubular steel profile. The core 3 is an elongated, essentially cylindrical wooden rod.

[0110] The core 3 is enclosed in a fluid-tight manner within the interior space 4 of the outer body 2, with plastic closures (not shown) provided at the two open ends of the outer body 2. This allows the fluid content of the core 3 to be kept essentially constant even under changing external conditions.

[0111] Fig. 1b shows an embodiment of a device according to the invention in the joined state. The outer surface 6 of the core 3 is spaced from the inner side 5 of the outer body 2 in this state, thus there is in particular a clearance fit between the core 3 and the inner surface 5 of the outer body 2. Regarding the further features, please refer to the description of Fig. 1a referred to.

[0112] The device can assume the joined state particularly during the manufacture of the device or the composite beam 1. In the joined state, the core 3 can be introduced into the interior 4 of the outer body 2. By increasing the water content, the composite beam 1 is brought into the operating state, so that the core 3 presses with its outer surface 6 against the inner surface 5 of the outer body 2.

[0113] In this embodiment, the water content of the core 3 is approximately 25 wt.% in the operating state and approximately 10 wt.% in the joined state.

[0114] If the composite beam is to be disassembled, at least one closure is removed. This allows excess moisture to escape, causing shrinkage of the core 3, which in turn results in a jointed state in which the core 3 can be removed from the interior space 4 of the outer body 2. The escape of moisture can be facilitated by heating the device.

[0115] Fig. 2a shows an embodiment of a device according to the invention in a schematic representation in the operating state according to a second embodiment. Fig. 2b shows the device according to the second embodiment in the joining state. Fig, 2a und 2b each show the device in a schematic sectional view, wherein the sectional plane is arranged substantially orthogonal to the longitudinal direction of the device.

[0116] The composite beam 1 according to the second embodiment largely corresponds to that according to the first embodiment described in detail.

[0117] In contrast to the first embodiment, the core 3 and the outer body 2 in the second embodiment have a square cross-section.

[0118] Furthermore, form-locking extensions 7 in the form of ribs are arranged on the inner surface 5 of the outer body 2. The form-locking extensions 7 press into the surface of the core 3 during operation, thereby additionally achieving a form-locking connection between the core and the outer body. The ribs are arranged at regular intervals along the longitudinal direction of the composite beam 1.

[0119] Furthermore, in contrast to the first embodiment, there is no fluid-tight enclosure of the core 3 within the interior space 4 of the outer body 2. In this embodiment, the outer body 2 is open on both sides. The frictional connection between the core 3 and the outer body 2 is achieved in this embodiment by reducing the water content of the core 3 in the joined state below the water content that corresponds to the equilibrium moisture content of the core material at a temperature of 20°C and a relative humidity of 50%. The core is thus dried so that its water content is, in particular, below 5% by weight.

[0120] In the joined state, there is no longer any form-fitting connection between the form-fitting elements 7 and the core 3.

[0121] In this joined state, the core 3 can be inserted into the interior space 4 of the outer body. The composite beam 1 then remains at ambient conditions, and the water content of the core 3 will gradually increase until it reaches equilibrium moisture content. The device is then in the operating state, achieving a similar effect to the first embodiment. However, a fluid-tight seal is not required, further simplifying the design.

[0122] To disassemble the device, the composite carrier 1 can be heated so that the fluid content of the core 3 is reduced.

[0123] Fig. 3a shows an embodiment of a device according to the invention in a schematic representation in the operating state according to a third embodiment. Fig. 3b shows the device according to the third embodiment in the joining state. Fig. 3a und 3b each show the device in a schematic sectional view, wherein the sectional plane is arranged substantially orthogonal to the longitudinal direction of the device.

[0124] The third embodiment essentially corresponds to the second embodiment, with the difference that the core 3 is designed as a hollow body with a cavity 8. This promotes the change in water content, with the larger free surface area enabling a more rapid change in water content. In this embodiment, the core 3 is designed as a box profile. The cavity 8 can be used for pipes, lines, cabling, and the like.

[0125] In an embodiment not shown, form-fitting extensions can also be provided in this embodiment.

[0126] In addition, in contrast to the second embodiment, no form-fitting extensions 7 are provided.

[0127] Fig. 4a shows an embodiment of a device according to the invention in a schematic representation in the operating state according to a fourth embodiment. Fig. 4b shows the device according to the fourth embodiment in the joining state. Fig. 4a und 4b each show the device in a schematic sectional view, wherein the sectional plane is arranged substantially orthogonal to the longitudinal direction of the device.

[0128] The fourth embodiment essentially corresponds to the third embodiment, with the difference that the outer body 2 and the core 3 are hollow cylindrical. An inner profile body 9, which in this embodiment is a steel tube, is arranged in the cavity 8 of the core 3.

[0129] In operating condition, as in Fig. 4aAs shown, the core 3 presses on the inner surface 5 of the outer body 2 as well as on the outer surface 10 of the inner profile body 9 due to the swelling.

[0130] In this embodiment, the device can be used as a load-bearing component and at the same time as a pipe for conveying liquids or gases, for example as a water pipe.

Claims

1. A device, in particular a composite beam (1), comprising a hollow profile-shaped outer body (2) having an interior space (4) and a core (3) arranged in the interior space (4), wherein the core (3) comprises or is formed from a fibre composite material, namely wood, that is swellable upon contact with a fluid, wherein the core (3) in the interior space (4) is swollen by a fluid and exerts a pressure on the outer body (2) generated by the swelling, such that the core (3) is braced in the interior space (4), characterized in that the core is fluid-tightly enclosed by the outer body (2) and by at least one closure arranged on the outer body (2).

2. The device according to claim 1, characterized in that the outer body (2) has a closed cross-section.

3. The device (1) according to one of claims 1 or 2, characterized in that the outer body (2) is designed as a metal profile, in particular as a steel profile.

4. The device according to one of claims 1 to 3, characterized in that the fluid is selected from one or more of the following fluids: water, saline solution, alcohol, ammonia.

5. The device according to one of claims 1 to 4, characterized in that the core (2) has a compaction area along its outer circumference, and / or in that the stress along the circumference of the profile cross-section of the outer body (2) is increased by the pressure generated by the swelling.

6. The device (1) according to one of claims 1 to 5, characterized in that an outer surface (6) of the core (3) is at least partially in direct contact with the inner side (5) of the outer body (2), and / or in that a connecting layer, for example an adhesive layer, is arranged between the outer surface (6) of the core (3) and the inner side (5) of the outer body (2).

7. The device (1) according to one of claims 1 to 6, characterized in that the core (3) is designed as a hollow body which optionally has a cavity (8) running substantially in its longitudinal extension direction, which is in particular open on at least one side.

8. The device (1) according to claim 7, characterized in that an inner profile body (9) is arranged in the cavity (8), wherein the core (3) exerts a pressure on the inner profile body (9) generated by its swelling.

9. The device according to one of claims 1 to 8, characterized in that the outer body (2) and the core (3) are frictionally engaged with each other.

10. The device according to one of claims 1 to 9, characterized in that the outer body (2) has at least one positive-locking element on its inner side (5), in particular a positive-locking extension (7), for the positive connection between the outer body (2) and the core (3), wherein the core (3) optionally has at least one positive-locking recess for engagement of the positive-locking extension (7).

11. A method for manufacturing a device (1), in particular a composite beam, comprising a hollow profile-shaped outer body (2) having an interior space (4) and a core (3) arranged in the interior space (4), wherein the core (3) comprises or is formed from a fibre composite material, namely wood, that is swellable upon contact with a fluid, wherein the method comprises the following steps: (a) providing the core (3), wherein the core (3) has a first fluid content, (b) inserting the core (3) into the interior space (4) of the outer body (2), (c) increasing the fluid content of the core (3) such that the core (3) is swollen by the fluid and exerts a compressive force on the outer body (2) generated by the swelling, wherein the core has a second fluid content, (d) fluid-tightly enclosing the core (3) by the outer body (2) and by at least one closure arranged on the outer body (2).

12. The method according to claim 11, characterized in that the fluid is water, and / or in that the second fluid content is at least 1 wt.%, in particular at least 2 wt.%, above the first fluid content.

13. The method according to claim 11 or 12, characterized in that the core (3) and interior space (4) in step (b) have a clearance fit.

14. The method according to one of claims 11 to 13, characterized in that the fluid is water, and in that the first fluid content is at most 10 wt.%, in particular at most 5 wt.%, and / or in that the first fluid content is below the equilibrium moisture content of the fibre composite material of the core at a temperature of 20°C and a relative humidity of 50%.

15. The method according to one of claims 11 to 14, characterized in that the method further comprises the following step: (d) forming positive-locking elements by deforming the outer body (2).