METHOD FOR FOAMING TUBE CHIPBOARD AND A TUBE CHIPBOARD

Description

[0001] The invention relates to a method for foaming tubular chipboard, as well as a tubular chipboard with at least partially foamed tubes.

[0002] Tubular particleboard with a filled tube is known, for example, from DE 28 23 053. These consist essentially of a middle layer of lignocellulosic particles, usually wood chips, mixed with a binder. This layer is extruded into beam form and finally covered with an outer layer of, for example, natural wood boards. The patent also discloses the possibility of creating a continuous cavity in the middle layer. Furthermore, it shows the possibility of filling this cavity with an insulating material or foam. Tubular particleboard without an outer layer and foam-filled tubes are used, for example, in the manufacture of wall elements or doors, usually as the core of the door leaf. This core can then be covered with veneers or decorative papers on the visible surfaces to, for example, create a natural wood look or imitate a wood grain.

[0003] From EP 0 141 368 A2, a door leaf comprising a tubular particleboard with substantially horizontal tubes is further disclosed. The door leaf is intended to be particularly burglar-resistant and fire-resistant. Therefore, metal rods are embedded in at least some of the tubes. The metal rods have a smaller diameter than the tubes themselves. It is thus taught that the remaining cavity of each tube is filled with a material possessing fire-retardant properties. In this context, the fire-retardant agent can be a material that foams up when exposed to heat. Furthermore, the tubes are to be closed at their open ends by means of a metal frame surrounding the door leaf. Hardboard layers are applied to the visible surfaces of the tubular particleboard.

[0004] Tubular particleboard of the previously known type has a thin wall thickness and therefore low strength in the area of ​​the tubes. If, for example, profiles are incorporated into the surface of the tubular particleboard, such as for country-style door leaves, or if cutouts through the tubular particleboard are used to design a door leaf or wall element, stability problems can sometimes occur on the surface of the tubular particleboard or at the edge of such a cutout. The cutout often cuts through one or more tubes at the edge, exposing concave cavities or cutting into the tubes. The wall sections at these edges are thin and correspondingly unstable. The same applies to profiling the surface in the thin wall sections above a tube. Therefore, such processing of tubular particleboard has not been economically feasible until now.

[0005] The invention is therefore based on the objective of proposing a method and a tubular particleboard with which the possibilities of surface treatments can be improved in a cost-effective manner.

[0006] The invention solves the problem with a method according to claim 1 and a tubular particleboard according to claim 9. The dependent claims relate to advantageous embodiments.

[0007] The method according to the invention is defined in claim 1. In one step of the method according to the invention, a tubular particleboard is provided. Various manufacturing processes for producing such tubular particleboards can be found in the prior art, such as the Okal process and / or the Globiboard process.

[0008] In a further step, one or more machining areas are defined on the top and / or bottom surface of the tubular particleboard. Within the scope of the invention, defining a machining area means specifying a region of the tubular particleboard in which machining is to take place. Such specification can be achieved either by a temporary surface marking or, optionally in addition to the aforementioned marking, by setting up a piece of equipment in a work system, such as a machine or other tool. Depending on the machine class, setup can also include, for example, CNC programming. The machining can then involve, for example, the creation of a topology or surface profile, a decorative pattern, or a cutout.Within the scope of the invention, it is also possible to define several machining areas on a tubular particleboard, e.g., at different locations on the top and / or bottom surface. The user is free to decide whether these machining areas are strictly separated from one another or even overlap. Machining can be understood to mean, in particular, processes that relate to the processing of the surface, i.e., the top and / or bottom surface of the board. Such processes can be, for example, material-removing, such as milling, planing, grinding, filing, cutting, or sawing, etc.

[0009] In a further step, the inventive method provides for the introduction of a foaming material into at least one of the aforementioned tubes in the processing area to locally reduce the density difference between the tubes and the board body. Thus, if, for example, an area has been marked on the surface in which processing is to take place, then, according to the invention, the tubes located in this area are at least partially filled with the foaming material in this step. Small-pore rigid foams are particularly suitable as such a material, as they serve precisely to increase the density and thus the strength of the board body in the areas weakened by the tubes. Typical foams suitable for carrying out the invention can have a pore diameter of 150 µm to 300 µm. The density of the tubular particleboard is increased by 15 wt.% to 35 wt.% by the introduction of foam.The bending strength can be increased by a factor of -% relative to the tubular particleboard without foam, whereby the bending strength perpendicular to the plane of the board is at least twice as high for the tubular particleboard filled with foam-forming material in the processing area compared to the initial bending strength of the unfilled tubular particleboard. The tensile strength parallel to the tubes can be increased at least fourfold by filling with foam-forming material. The mechanical properties are measured in accordance with EN 14755.

[0010] In a further step, the machining areas are processed. With regard to the aforementioned definition of several separate machining areas, it is also entirely possible within the scope of the invention that different machining operations or even a combination of different machining operations are possible in each machining area. The machining process itself can, in turn, comprise several sub-steps to achieve a machining goal, e.g., the creation of a cutout in conjunction with a profile in the surface of the tubular chipboard in the edge region of the cutout.

[0011] The inventive method for foaming tubular particleboard exhibits high efficiency and product quality. The targeted introduction of density- and thus strength-enhancing foam leads to a significant increase in stability, particularly the tensile and flexural strength of the product. This improved stability makes it possible to process the surface of a tubular particleboard or to cut out a section of it in a simple and economical manner.

[0012] A tubular particleboard can be provided from a stock for further processing according to the above method. However, the tubular particleboard can also be taken directly from a continuous manufacturing process. For example, it is possible to remove a tubular particleboard cut to length on a cutting tray from a continuous process. According to a preferred embodiment, the tubular particleboards provided were previously produced by an extrusion process.

[0013] In such a continuous process, sawmill residues, in the form of classified and prepared lignocellulosic materials bonded with binder, particularly wood chips, are spread into a mostly vertical press chamber with heated lateral guide plates and compressed in a ramming motion by a press ram while the resulting tubular particleboard is pressed or conveyed downwards. During the pressing process, heat can also be introduced into the material, causing the binder to harden. Once hardened, the mixture of, for example, wood chips and binder is permanently bonded together. Cylindrical rods or mandrels can also be arranged in the press chamber. These guide the press ram and, at the same time, create the tubes in the particleboard, eliminating the need for subsequent drilling.In such a stuffing method, the orientation of the chip surfaces of the wood chips is preferably transverse to the stuffing direction.

[0014] The tubes within the core of the board offer particular advantages in terms of weight. Raw material is also saved. However, as previously described, a disadvantage is that, especially during machining operations where material is removed from the top and / or bottom surface, surface sections can be exposed or created that are either only thinly separated from one or more tubes, and / or even partially intersect at least one tube, thus exposing a cavity as described earlier. The more material is removed from the top and / or bottom surface during machining, the thinner the gap between the top and / or bottom surface and the tubes becomes. Therefore, machining weakens the surface of the board in the machined area due to material removal.The machining process completely removes the wall section above a tube within the machining area. As the machining progresses, the strength of the machined area decreases. Depending on the degree of machining, the plate then becomes increasingly prone to breakage. Furthermore, a clean cut edge is often impossible to achieve in a thin-walled section.

[0015] If, during machining of the wall section of a tube, so much material is lost that a cut or even a complete cut involving one or more tubes occurs, it is advantageous for at least the affected tubes to be filled with foam in the cut area to increase strength. Many machining processes, especially those where the machining is carried out uniformly across the machining area, result in such cuts or complete cuts essentially at the edge of the respective machining area. According to a further preferred embodiment, the foaming material is therefore introduced into corresponding tubes at the edge of the machining area, possibly exclusively at the edge of the machining area.

[0016] In one possible form of processing, material is removed, but the process does not penetrate the panel body so deeply that it directly intersects the tubes. According to another preferred embodiment, a topology, in particular a decorative pattern or profile, is created in at least one processing area. Such a topology can be created, for example, by milling, planing, filing, sawing, cutting, or another material removal process, both mechanically and manually. Surface decorations, for example, in the production of country-style doors with profiled surfaces, are particularly suitable. As mentioned above, the problem can also arise that the distance between a tube and the top or bottom surface is so small that the thin wall section in the area above the respective tube remains delicate and unstable.This area was previously described as having low compressive strength. It is particularly preferred that the tubes throughout the entire processing area, including those not located at the edges, be filled with foam to provide stability to the resulting topology.

[0017] As mentioned above, tubular particleboard is particularly used in the manufacture of doors or wall elements. Wall elements include, for example, mobile partitions or wall panels, especially non-load-bearing wall elements in interior construction. In such cases, it may be necessary, for example for functional and / or aesthetic reasons, to insert structural or decorative components into the finished door or wall element, i.e., into the tubular particleboard. According to a further preferred embodiment, a cutout is therefore created in at least one processing area during machining, which cuts through the top and bottom surfaces of the board or the board as a whole. The edge of the cutout preferably coincides with the edge of the processing area. However, the size of the cutout does not necessarily have to correspond to the size of the defined processing area.As previously explained, further processing can also be carried out in the same processing area, e.g., in the edge region of the cutout. In addition to, for example, creating a cutout, such further processing can include the creation of a decoration or an edge profile. Particularly preferably, in such processing areas, the tubes are partially filled with foam, at least in the edge region of the cutout, so that the weakening of the edge regions caused by the tubes is at least reduced, and ideally eliminated, both dimensionally and statically.

[0018] Cutouts in tubular particleboard are frequently used for the installation of infill panels, such as transparent elements or solid panels made of wood, metal, ceramic, or plastic. Various transparent components are suitable as the aforementioned visible element, such as rectangular windows or round windows like portholes. Semi-transparent or opaque glass components can also be installed in the cutouts, such as frosted glass inserts, which are more translucent than transparent and also serve a decorative function. According to a further preferred embodiment, a frame is arranged at the edge of the cutout to enclose these components. Such a frame serves, in particular, to hold or secure the infill panel to be installed in the cutout. The frame preferably interacts, at least partially, with a foam-filled portion of the tube.The frame often consists of strips and can be glued to the tubular particleboard at these points or attached with other conventional fasteners. In particular, the frame can be attached to the board body or the foam-filled tube at the edge of the cutout with pins (e.g., wooden or metal pins). However, it is also clear that the frame may simply consist of a sealant, gasket, or adhesive to hold the filling material in place.

[0019] As an alternative to such infills, other components with properties or functions can also be arranged in or on a cutout, such as doors for hatches, pass-throughs, animal flaps, or similar components. According to a further preferred embodiment, the cutout is therefore fitted with a door after a frame has been arranged.

[0020] Depending on the dimensions of the machining operation and the number of different machining operations within a machining area, achieving the aforementioned advantages, particularly regarding increased stability, may require foaming several tubes section by section. These tubes are spaced apart by one or more tubes located between them. This is especially true when the tubes to be foamed are located at opposite edges of a larger machining area spanning multiple tubes. According to a further preferred embodiment, the foaming material is therefore introduced section by section into a plurality of tubes, which do not necessarily have to be adjacent. The introduction can be carried out at atmospheric pressure. Preferably, however, it is performed at a pressure between 3 bar and 15 bar.Under increased pressure, a tube is evenly filled with foam, and the foam formation is also uniform.

[0021] The thickness of a tubular particleboard of the type under discussion here is preferably many times smaller than its corresponding width or even length. This is particularly evident when considering the construction of a door or wall element from this type of board. Typically, there are numerous tubes across the width of each tubular particleboard, generally oriented parallel to its longitudinal axis. The diameter of the tubes is naturally limited by the thickness of the board and the thin wall sections that seal each tube at the top and bottom surfaces. As previously explained, depending on the size of the machining area and especially when creating a cutout in the tubular particleboard, it is possible that several tubes will be cut at different angles during machining.With regard to the aforementioned plurality of tubes, which are partially filled with foam-forming material, a further preferred embodiment therefore provides that the plurality of tubes are cut in the area of ​​the tube sections filled with foam-forming material by creating a cutout.

[0022] The disclosure further relates to a device used for foaming at least a section of a tubular particleboard tube. This device comprises at least one container for receiving the foaming material or one container for each component of the foamable material. The device further comprises a mixing and metering system comprising a metering device, e.g., one or more flow meters and a mixing head. The container(s) and the components of the mixing and metering system are connected by lines through which the material is conveyed. The material is conveyed by at least one pump. If the foaming material consists of two or more components, it is conveyed from a separate container for each component in a line to the mixing head, the quantity of each component being determined by a metering device.In the mixing head, the two or more components are mixed, and the mixed components are conveyed through a line to a lance. The lance, which is also part of the device, is, in a simple design, the free outlet end of the line. Preferably, however, the lance is connected to the line at its inlet end. During the foaming process, the outlet end of the lance is generally located inside the tube being foamed, particularly in a processing area of ​​the tubular particleboard. The lance is sufficiently rigid to be easily inserted into and removed from the tube being foamed. The device is usually supplemented by a control unit that, firstly, controls the mixing and metering system by specifying the quantity of the foaming material or its individual components to be dispensed. Secondly, the control unit optionally also includes the control of the lance, e.g., by a robot.The control unit specifies, in particular, the penetration depth into the tube to be foamed and the speed of the lance within the tube during the foaming process. Optionally, the control unit also controls the pressure at which the foaming material is introduced into the tube. Foaming can be carried out at atmospheric pressure. Preferably, the container, mixing head, and lance are designed such that the control unit can perform foaming at a pressure of 3 bar to 15 bar.

[0023] The invention also relates to a tubular chipboard according to claim 9, wherein definitions and explanations of terms from the preceding inventive method also apply here.

[0024] According to the invention, the tubular particleboard comprises a board body perforated by tubes, with surfaces namely a top and a bottom, wherein one or more tubes in at least one processing area are partially filled with a foam-forming material, and wherein the processing areas each have a cutout and / or a topology, in particular a decorative profile, on at least one surface. Within the scope of the invention, it is conceivable that a cutout and one or more topologies are arranged in a processing area, e.g., adjacent to the cutout. Likewise, it is possible that two or more independent cutouts are arranged in a processing area, which may also be supplemented by a topology.

[0025] According to a preferred embodiment, in those processing areas that have a cutout, a frame is arranged in the edge region of each cutout, at least partially covering the cut, foam-filled tubes. The frame can be made of strips, but it can also consist of a layer of material, a strip, or a film that covers the cut sections of the tubular particleboard. Optionally, as described above in connection with the method, a filling is arranged in a cutout, which may be framed or fixed by the frame.

[0026] According to another preferred embodiment, a door is inserted into a cutout. This door can be adapted to the specific application, for example, in the medical field as a double-sided airlock for exchanging items with a cleanroom or similar environment. In simpler cases, the door can also be designed as a slot with a flap for a letter slot. The possibility of designing the door as a dog or cat flap has already been mentioned. In all such cases, it can be advantageous if the door is arranged and attached to the edges of the tubular particleboard, particularly to the most stable and rigid sections possible. This demonstrates the significant advantages of foaming tubular particleboard, especially in the edge area of ​​a processing zone.

[0027] To enable these advantages, a further preferred embodiment provides that the foam-forming material contains at least 20 %, bevorzugt The foaming material has a density of 25% of that of the board body. It fills an empty tube, thus offering, for example, the possibility of anchoring a frame of the aforementioned type, located within this tube, to the foaming material. Two-component materials are often used as the foaming material. In these materials, the two components react immediately after mixing, releasing gas and creating a foam that fills the tube of a tubular particleboard. A typical material could consist of a combination of isocyanate and polyol, used in a ratio of 1:1 to 1:2, preferably 1:1.5.

[0028] Particularly with regard to the creation of a specific topology, the strength of the foaming material can be an important factor in addition to its density. For example, in the case of a thin-walled section formed over a tube, as mentioned above, the foaming material is intended to provide support. It is known from a physics perspective that density and strength are not necessarily correlated. According to a further preferred embodiment, the strength in the area of ​​the foamed tube is higher than the strength of the unfoamed tube. For instance, the flexural strength increases by at least a factor of 2, preferably by at least a factor of 3, parallel to the direction of the tube, compared to the unfoamed tube. The tensile strength increases by at least a factor of 4, advantageously by at least a factor of 5, after foaming, relative to the unfoamed tube. The mechanical properties were measured in accordance with DIN 14775.

[0029] Details of the invention are explained below with reference to an exemplary embodiment and the figures. The figures show: Fig. 1 a perspective view of a tubular particleboard with a defined machining area according to one embodiment; Fig. 2 a perspective view of the tubular particleboard made of Fig. 1 with a cutout in the machining area; Fig. 2 a perspective view of a tubular particleboard according to the invention with a cutout and partially foamed tubes; Fig. 3a a normal view along a longitudinal axis of a part of a tubular particleboard before machining; Fig. 3b the tubular particleboard made of Fig. 3a after processing.

[0030] Fig. 1 Figure 1 shows an example of a tubular particleboard 10 with a core 14 perforated by tubes 12. The core 14 consists of chips mixed with binders, which are pressed under pressure and heat in an extrusion process and cut to the specified length. The width of the tubular particleboard 10 is determined by the manufacturing process. Here, the tubular particleboard 10 has, by way of example, a length L, a thickness D, and a width B. The tubes 12 extend along the length L and thus parallel to a longitudinal axis A of the core 14. The core 14 has a top surface 16 and a bottom surface 18, with a machining area 20 defined on the top surface 16.

[0031] Fig. 2a illustrates the design of the tubular chipboard 10 according to Fig. 1 After processing, here the creation of a cutout 26. The cutout 26 extends in a cutting direction S, which here is oriented perpendicular to the top surface 16, and penetrates the tubular particleboard 10 completely, i.e., both the top surface 16 and the bottom surface 18. The cutout 26 cuts through a plurality of tubes 12 both in the direction of the longitudinal axis A and transversely to it. The cutout 26 accordingly has an edge region 22 in which both the board body 14 and the tubes 12 are cut either in the direction of the longitudinal axis or transversely to it. Fig. 2a This illustrates in particular that in those sections of the edge area 22 where the tubes are cut parallel to the longitudinal axis A, a concave recess 24 remains. Those tubes 12 which are cut transversely to the longitudinal axis A by the cutout 26, on the other hand, have essentially the same characteristics as the tubes 12 at the free longitudinal ends of the tubular particleboards 10.

[0032] Fig. 2b shows a tubular chipboard 10, as exemplified in Fig. 2a This was illustrated, in which the disadvantages of the aforementioned recess 24 were improved according to the invention, particularly by means of section-by-section foaming 28. The former recess 24 now has, as shown Fig. 2b Thanks to the foam filling 28, the cut surface is essentially planar and parallel to the longitudinal axis A. Likewise, the tubes 12 that are cut transversely to the longitudinal axis by the cutout 26 are no longer open in the corresponding edge area 22, but are also filled with foam 28. The foam filling 28 was applied there before processing with the cutout 26, specifically when the corresponding processing area was defined. As described above, a mental definition or a visible or tactile marking is sufficient. Fig. 1 is not absolutely necessary.

[0033] Fig. 3a Figure 1 shows an example of a portion of a tubular particleboard 10 with three tubes 12 arranged at a distance X from each other, each with a tube diameter Y. It is evident that only the tube 12 which is located in the area of ​​a cutting edge 30, or is cut by it, has a foam filling 28. If a tube 12 is sufficiently separated from the future edge area 22 ( Fig. 3b ) spaced apart, it does not need to be provided with a foam filling 28.

[0034] The inventive method is carried out in a simple embodiment by introducing a foaming material, e.g., a mixture of an isocyanate and a polyol in a ratio of 1:1.5, preferably at temperatures between 10 °C and 40 °C, into a tube 12 of a tubular particleboard 10, e.g., by means of a lance that extends into the tube 12 to or within the processing area 20 to be foamed. At its inlet end, the lance is connected via a fluid line to a mixing and metering system in which the aforementioned two-component mixture of isocyanate and polyol is preferably measured by means of flow meters and mixed in a mixing head for immediate use.The mixing and dosing system typically consists of a tank with an agitator for each component of the foaming agent, pumps, flow meters, a mixing head, and pipes connecting the individual components. The agent, or its components, are pumped from the tanks, according to the flow meters, through the mixing head to the outlet of the lance by one or more pumps. In this simple design, the lance can be operated manually. The lance is approximately 2 to 3 meters long. A typical mixing and dosing system dispenses approximately 20 to 100 grams of foaming agent per second. To continuously produce this dispensing rate, two tanks, each with a capacity of approximately 200 liters, are required for a two-component system, one to hold each component.The agitator ensures a uniform dispensing of each component with consistent quality. Immediately after the two components are mixed in the mixing head, the foaming agent is introduced into the tube 12 to be foamed. Upon exiting the lance, it foams up, filling at least sections of the tube 12 with foam. The foaming agent exits the lance at high pressure. High pressure here refers to outlet pressures between 3 bar and 15 bar. Consequently, the residence time of the foaming agent in the lance before its introduction into the tube 12 is short in this high-pressure process. This is particularly advantageous because, when using a multi-component foaming agent, the device has a longer service life due to reduced cleaning and maintenance requirements.Since only the mixture of the relevant components, i.e., the material, is chemically reactive at a rapid rate, in most cases only the lance needs to be cleaned after a production stoppage. In an alternative design, particularly for processes using a slower-reacting material, it is also conceivable that the material is then introduced from the lance into a tube 12 of a tubular particleboard 10 at a correspondingly lower pressure, i.e., at low pressure.

[0035] For longer tubes 12, e.g., for doors or wall elements, the foaming process is preferably carried out in two steps. In a first step, the lance is inserted from one end of the tube 12, and the tube 12 is foamed at least section by section from the middle to the first end. In a second step, the lance is then inserted from the opposite end of the tube 12, and the foaming process is carried out at least section by section between the middle of the tubular particleboard 10 and the second end. The foaming material, especially when a high-pressure process is used, is usually liquid until it exits the lance and foams up after exiting. Preferably, a foam with a pore size of 150 µm to 300 µm is produced. Filling the tube 12 with foam is usually completed in approximately 15 minutes.

[0036] In an advantageous embodiment of the method, several tubular particleboards 10 are processed simultaneously. Two or more lances can be used at the same time. Preferably, a control unit is employed that controls individual lances or groups of lances so that, even when several tubular particleboards 10 or several tubes 12 within one or more tubular particleboards 10 are being foamed simultaneously, each tube 12 can be foamed individually, at least section by section, according to the specifications of the control unit. The control unit can preferably control or regulate the penetration depth of the lance into the tube and, if necessary, also the amount of foaming material introduced into the tube 12. A robot that handles the lance is also considered a control unit.

[0037] In a further advantageous embodiment of the method, a conveyor belt or a rotary table can be used to foam one or more tubes 12 of a tubular particleboard 10, at least section by section. Particularly when robots are used to guide the lance, it proves advantageous to use a conveyor belt or a rotary table to process the tubular particleboards 10, in which at least one tube 12 is to be foamed at least section by section, quickly. In particular, a conveyor belt or rotary table on which a stack of stacked tubular particleboards 10 is placed has proven effective. One or more tubes 12 of the stacked tubular particleboards 10 can be foamed at least section by section, either sequentially or simultaneously, by a lance or by a group of lances.

[0038] In a further preferred embodiment of the method, the conveyor belt or rotary table is designed so that it can be tilted or inclined, preferably at an angle of up to 10°, more preferably up to 5°, from the horizontal. If a tubular particleboard 10 is inclined during the introduction of foaming material, the distribution of the material in the respective tube 12 to be foamed can be optimized. For example, the lance can be made shorter because the distribution or flow of the material can be used to foam sections of the tube 12 that lie far inside the tubular particleboard 10. This allows the shorter lance to be inserted into and withdrawn from the tube 12 more quickly, resulting in faster processing.

[0039] Optionally, the conveyor belt or turntable can be equipped with a film wrapping device for the tubular chipboard panels 10 with at least partially foamed tubes 12. If the tubular chipboard panels 10 are transported after foaming but before processing, they are thus protected during transport. If the tube(s) 12 are foamed right up to the edge of the tubular chipboard panel 10, wrapping with film prevents foam from escaping. This effectively prevents contamination of the end faces and sticking of the panels 10 together due to any escaping foam.

[0040] According to a further advantageous embodiment, a mixing or dosing system with the associated lance(s) and a control unit can also be arranged with two conveyor belts or rotary tables, since the time for aligning a new stack and, if necessary, wrapping the processed stack with film can then be used to process a stack of tubular chipboard 10 arranged on a second conveyor belt or rotary table.

[0041] In addition, the strength properties of an unfoamed tube 12 (before) and a foamed tube 12 (after) were determined. The following values ​​were determined according to EN 14755: before foaming, the flexural strength in the area of ​​the tube 12 parallel to the tube 12 is 1.48 N / mm², after foaming it is 4.07 N / mm². Before foaming, the tensile strength in the area of ​​the tube 12 is 0.46 N / mm², after foaming it is 2.27 N / mm². By foaming the tube 12, the density of the tubular particleboard 10 increases from an average of 259 kg / m³ to 334 kg / m³. Reference symbol list

[0042] 10 Tubular chipboard 12 Tube 14 Panel body 16 Top side 18 Bottom side 20 Machining area 22 Edge area 24 Recess 26 Cutout 28 Foam filling 30 Cutting start A Longitudinal axis B Width D Thickness L Length S Cutting direction X Spacing of tubes Y Tube diameter

Claims

1. A method for foaming chipboards penetrated with tubes (10) comprising a board body (14) interspersed by tubes (12) and having surfaces, namely an upper and a lower face (16, 18), said method comprising the steps of - providing a chipboard penetrated with tubes (10), - defining one or more machining regions (20) on the upper and / or lower face (16, 18) of the chipboard penetrated with tubes (10), - foaming at least one of the aforementioned tubes (12) in the machining region (20) to locally reduce the difference in density between the tubes (12) and the board body (14) by introducing a foam-forming material into at least one of the above-mentioned tubes (12), - machining the machining regions (20).

2. The method according to claim 1, characterized in that the foam-forming material is introduced into corresponding tubes (12) at least in the edge region (22) of the machining region (20).

3. The method according to any one of the preceding claims, characterized in that a topology, in particular a decorative pattern, is created in at least one machining region (20) during the machining.

4. The method according to any one of the preceding claims, characterized in that a cutout (26) which penetrates the upper and lower face (16, 18) of the board body (14) is produced in at least one machining region (20).

5. The method according to claim 4, characterized in that a frame is arranged in the edge region (22) of the cutouts (26).

6. The method according to claim 5, characterized in that the cutout (26) is filled with an infill after the arrangement of a frame.

7. The method according to any one of the preceding claims, characterized in that the foam-forming material is introduced into a plurality of tubes (12) in each case in sections.

8. The method according to any one of claims 7, characterized in that, on account of the creation of a cutout (26), the plurality of tubes (12) are cut in the region of the sections that are filled with foam-forming material.

9. A chipboard penetrated with tubes, comprising - a board body (14) interspersed by tubes (12) and having surfaces, namely an upper and a lower face (16, 18), wherein - one or more tubes (12) are foamed in portions with a foam-forming material in at least one machining region (20), wherein the density of the tubular particleboard is increased as a result of introducing foam by 15% to 35% by weight relative to the tubular particleboard without foam, and wherein - the machining regions (20) each have a cutout (26) and / or a topology, on at least one surface.

10. The chipboard penetrated with tubes according to claim 9, characterized in that - in the machining regions (20), which have a cutout, a frame is arranged in the edge area (22), and - an infill is arranged in the cutouts (26) framed by the frame, wherein - the frame is in contact, at least in portions, with foamed portions of the tubes (12).

11. The chipboard penetrated with tubes according to any one of claims 9 to 10, characterized in that the cutouts (26) penetrate the chipboard penetrated with tubes (10) completely.

12. The chipboard penetrated with tubes according to any one of claims 9 to 11, characterized in that at least one infill is designed as a closure element.

13. The chipboard penetrated with tubes according to any one of claims 9 to 12, characterized in that the flexural strength of the tube (12) filled with the foam-forming material is greater than the flexural strength of the non-foamed tube at least by a factor of 2 parallel to the direction of the tube.

14. The chipboard penetrated with tubes according to any one of claims 9 to 12, characterized in that the tensile strength of the tube (12) filled with the foam-forming material is greater than the tensile strength of the non-foamed tube at least by a factor of 4.