METHOD AND DEVICE FOR PRODUCING A COMPOSITE WOOD BOARD

Abstract

The method relates to a method for producing a wood material panel. The method includes the following steps: (a) scattering a multitude of wood particles to produce a particulate cake, (b) applying an adhesive to at least some of the wood particles during the scattering and/or prior to the scattering, and (c) pressing of the particulate cake under high pressure and at a high temperature, wherein a quantity of adhesive that is applied to the wood particles is varied depending on its anticipated position in the particulate cake.

Claims

1. A method for producing a wood material panel, wherein the method comprises: (a) scattering a multitude of wood particles to produce a particulate cake, (b) applying an adhesive to at least some of the wood particles during the scattering and/or prior to the scattering, and (c) pressing of the particulate cake under high pressure and at a high temperature, wherein a quantity of adhesive that is applied to the wood particles is varied depending on its anticipated position in the particulate cake.

2. The method according to claim 1, further comprising introducing at least one additive into the particulate cake during the scattering.

3. The method according to claim 2, wherein different quantities of the additive are introduced at different positions within the particulate cake.

4. The method according to claim 2, wherein the at least one additive is another adhesive or an adhesive component.

5. The method according to claim 2, wherein the at least one additive contains: at least one filler, including chalk, talcum, quartz powder, glass beads, expanded glass or expanded clay, at least one optical brightener, including titanium dioxide, calcium carbonate or fluorescent organic substances, at least one flame retardant substance, at least one biocidal substance, at least one substance for preventing swelling of wood, at least one foamer, and/or at least one substance that alters a visual and/or haptic and/or physical property of the wood material panel.

6. The method according to claim 2, wherein different additives and/or different quantities of various additives are introduced at different positions within the particulate cake.

7. The method according to claim 2, wherein a quantity of wood particles, which are spread to form the particulate cake, varies depending on their anticipated position in the particulate cake.

8. A device for conducting a method according to claim 1, which comprises an electrical control system that is configured to vary a quantity of the adhesive that is to be applied to the wood particles depending on their anticipated position in the particulate cake.

9. The device according to claim 8, wherein the electrical control system has an electronic data processing device that is configured to access information saved in an electronic memory and, based on the information, to vary the quantity of the adhesive to be applied.

10. The device according to claim 8, wherein the device features at least one glue nozzle, by way of which the adhesive can be applied to the wood particles, wherein the electrical control system is configured to vary a quantity of the adhesive that can be applied by the at least one glue nozzle.

11. The device according to claim 10, wherein the at least one glue nozzle can be moved transversely to a transport direction of a conveyor belt onto which the wood particles are scattered.

12. The method according to claim 5, wherein the physical property of the wood material panel is thermal conductivity.

Description

BRIEF DESCRIPTION OF DRAWINGS

[0043] An embodiment of the present invention will now be described with the aid of figures. They show

[0044] FIG. 1 shows a perspective and schematic sectional view of a wood material panel that can be produced according to an embodiment of the production method according to the invention, and

[0045] FIG. 2 shows a schematic flowchart of the production method.

DETAILED DESCRIPTION

[0046] FIG. 1 is a perspective sectional view of a wood material panel 2 that can be produced according to an embodiment of the production method according to the invention. This type of wood material panel exhibits an expansion in the x, y and z directions. Here, the x direction relates to the expansion of the wood material panel transverse to the longitudinal direction y. The height or thickness of the wood material panel extends in the z direction.

[0047] In FIG. 1, areas 4.1 and 4.2 are depicted with different quantities of applied adhesive. Areas 4.1 are areas with a greater quantity of adhesive. Areas 4.2 are areas with a smaller quantity of adhesive.

[0048] FIG. 2 schematically depicts the production process of a wood material panel; specifically, in this case, a wood fiber panel.

[0049] First, wood 10 is provided. Said wood is preferably forest wood or waste wood that has been de-barked beforehand. It is then processed in a comminution device 12, such as a disc chipper or a drum chipper, to produce wood chips. These wood chips are then fed into a boiler 14. Here, the wood chips are treated and cleaned under the influence of hot steam; if necessary, the wood chips may be pre-heated beforehand. For instance, the wood chips are macerated at a temperature of approximately 170° for around 3-4 minutes.

[0050] The maceration in the boiler 14 is followed by a fiber maceration of the wood chips in a refiner 16, especially in the case of wood fiber boards. In said refiner, the wood chips are ground, for example in a disc mill, a cylinder mill or a roller mill, and processed to produce wood fibers.

[0051] Subsequently, the—in particular still moist—wood fibers are pre-glued in a pre-gluing installation with an adhesive, such as urea formaldehyde resin (UF resin). The wood fibers are preferably separated either before or after this step so they are ready for the scattering heads later, which scatter said fibers in a scattering device 24 during a later step in the method. This has the advantage that the quantity of adhesive that is to be applied later by means of the glue nozzles, wherein said quantity may also be zero, can be adjusted especially easily depending on the anticipated position of the wood fibers.

[0052] The glued wood fibers are subsequently dried in a dryer 20, for instance using hot gas at a temperature of approximately 160°, for example, until a specific residual moisture level of, for example, 10-15% is reached.

[0053] The drying is followed by separation in a separator 22. Here, the fibers are separated according to, for instance, particle size or fiber length, mass or inertia. This is conducted, for example, in a gas flow in a so-called air separator.

[0054] Specifically, this renders it possible to remove any fiber sizes that are not suitable for further processing. In particular, fibers that are too large may be put through the comminution process again; fibers that are too small or pulverized wood particles may be removed from the rest of the process. Alternatively, it is also possible that the separation takes place before the wood fibers are glued.

[0055] Following separation, the wood fibers are fed into the scattering device 24, which specifically comprises a number, for example at least three, glue heads 26 with glue nozzles, not depicted. The scattering device 24 preferably comprises a conveyor belt, which can be moved in a transport direction. In particular, the glue nozzles of the glue heads 26 are arranged transversely to this transport direction. These glue nozzles preferably extend across the entire width of the conveyor belt, transverse to the transport direction. It is especially preferable if they can be swiveled in at least one, in particular in all, spatial directions.

[0056] The glue heads 26 are connected to an electrical control system 28 that is configured to adjust a quantity of adhesive to be applied to the wood particles depending on their position in the particulate cake, for example in a plane parallel to the longitudinal direction and the transverse direction.

[0057] Preferably, a continuous and constant quantity of wood particles is scattered through each glue head 26, wherein said quantity of wood particles may different between the individual glue heads 26. For instance, it is also possible that several glue nozzles of a glue head 26 which are arranged at a distance from one another transversely to the transport direction emit greater quantities of adhesive per time unit than other glue nozzles of this glue head 26.

[0058] The particulate cake produced by the scattering is pre-compacted in one or several pre-compacting steps in a pre-compacter 30. This may occur, for example, on a continuous basis or indeed an intermittent basis, i.e. in several separate steps.

[0059] The pre-compacter is followed by a hot press 32, by means of which the wood material panel 2 is formed from the pre-compacted particulate cake under the influence of heat and pressure. In the present case, this produces, for example, a large high-density fiberboard (HDF) panel or a mid-density fiberboard (MDF) panel.

[0060] Said panel may be produced by sawing the continuously formed wood material panel 2 in the transverse direction to the transport direction. These large panels are further processed to form a multitude of smaller panels, especially by sawing them in the transverse and/or longitudinal direction.