METHOD FOR PRODUCING OSB PANELS AND OSB PANEL PRODUCTION DEVICE

Abstract

The disclosure relates to a method for producing OSB panels which includes: producing coarse chips, applying a flame-retardant solution to the coarse chips, subsequently removing flame-retardant solution from the coarse chips, in particular by applying a pressure difference, resulting in coarse chips containing flame retardant, then applying glue to the coarse chips containing flame retardant, thus obtaining glued coarse chips, and pressing the coarse chips, thus obtaining the OSB panel.

Claims

1. A method for producing OSB panels comprising: (a) producing coarse chips, (b) applying a flame-retardant solution to the coarse chips, (c) subsequently removing the flame-retardant solution from the coarse chips, by applying a pressure difference, resulting in coarse chips containing flame retardant, (d) applying glue to the coarse chips containing the flame retardant, thereby obtaining glued coarse chips, and (e) pressing the coarse chips, thereby obtaining the OSB panel.

2. The method according to claim 1, further comprising: (a) arranging the coarse chips on a transport belt, resulting in a coarse chip layer, (b) applying a the flame-retardant solution to the coarse chips on the transport belt, and (c) applying a pressure difference to the coarse chips webbed by the flame-retardant solution by applying a negative pressure to a lower side of the transport belt and/or an overpressure to an upper side of the coarse chip layer.

3. The method according to claim 1, wherein the production of the coarse chips includes drying the coarse chips, wherein the drying is performed prior to applying the flame-retardant solution.

4. The method according to claim 1, wherein a chipboard layer thickness of a coarse chip layer corresponds at most to four times a coarse chipboard layer thickness of the coarse chipboard layer.

5. The method according to claim 1, further comprising removing any flame retardant solution present on the coarse chips.

6. The method according to claim 5, wherein the removal of any flame-retardant solution present on the coarse chips comprises: (a) blowing off and/or sucking off by applying the pressure difference, and/or (b) spinning it off.

7. The method according to claim 1, further comprising drying the coarse chips containing the flame retardant, following the removal of the flame-retardant solution present on the coarse chips.

8. The method according to claim 1, wherein the flame-retardant solution (a) has a temperature of at least 50 C. when being applied to the coarse chip layer. and/or (b) contains a viscosity reducer comprising a surfactant.

9. The method according to claim 1 further comprising: (a) producing coarse and middle layer chips, (b) joint drying of the coarse chips and the middle layer chips, (c) separating the coarse chips and the middle layer chips, (d) applying the flame-retardant solution to the coarse chips, thereby obtaining coarse chips that contain the flame retardant, (e) producing a first surface layer and a second surface layer from the coarse chips containing the flame retardant and a middle layer at least from the middle layer chips, and (f) pressing the first surface layer, the second surface layer and the middle layer to form the OSB panel.

10. The method according to claim 2, wherein: (a) the flame-retardant solution contains a coloring agent, that is colorless and that absorbs or fluoresces in a UV range, and (b) the method further comprises: (i) depth-dependent; optical detection of a coloring agent concentration of the coarse chipboard layer and/or the OSB panel, thereby obtaining a coloring agent depth profile, and (ii) controlling a transport belt speed, the pressure difference and/or an area-specific application amount of flame-retardant solution using the coloring agent depth profile.

11. An OSB panel production device comprising: (a) a coarse chip production device which produces coarse chips from wood, (b) a dryer which dries the coarse chips and that is connected to the coarse chip production device, (c) a distribution device which distributes the course chips, thereby obtaining a coarse chip layer, and (d) a belt conveyor, arranged downstream of the dryer in a direction of material flow, and which transports the coarse chipboard layer, (e) a flame-retardant solution application device configured to apply a flame-retardant solution to the coarse chip layer, and (f) a pressure difference generator which applies to the coarse chip layer at a pressure difference.

12. The OSB panel production device according to claim 11, further comprising an inspection system which detects a flame retardant distribution of the flame retardant in the coarse chip layer and/or in the OSB panel, the inspection system comprises: (a) a UV light source, and (b) a camera which detects reflected UV light and/or fluorescent light.

13. The OSB panel production device according to claim 12, further comprising a controller that is configured to automatically control a transport belt speed, the pressure difference and/or an area-specific application amount of the flame-retardant solution using the flame retardant distribution.

14. The OSB panel production device according to claim 11, wherein the pressure difference generator comprises: (a) a negative pressure pump and a plurality of suction chambers, each of which is connected to the negative pressure pump via a valve, the valves having a degree of valve opening that increases as pressure in the suction chambers increases, and/or (b) a pressure pump and a plurality of pressure chambers, each of which is connected to the pressure pump via a valve, the valves having a degree of valve opening that increases as pressure in the suction chambers decreases.

15. The OSB panel production device according to claim 12, further comprising a return device which returns the flame-retardant solution that has been removed from the coarse chips by the pressure difference generator to the flame-retardant solution application device.

Description

DETAILED DESCRIPTION OF DRAWINGS

[0056] In the following, the invention will be explained in more detail with the aid of the accompanying drawings. They show:

[0057] FIG. 1 shows a schematic view of an OSB panel production device according to the invention for carrying out a method according to the invention and

[0058] FIG. 2 shows a schematic detailed view of the OSB panel production device according to FIG. 1.

DETAILED DESCRIPTION

[0059] FIG. 1 schematically depicts an OSB panel production device 10 according to the invention that comprises a coarse chip production device 12. The coarse chip production device 12 comprises a debarking unit 14 for debarking wood 16, a coarse chipper 16 arranged downstream of the debarking unit 14 in the direction of material flow M and a dryer 18 arranged downstream of said chipper in the direction of material flow M. The coarse chip production device 12 thus produces coarse chips 20.i (i=1, 2, 3, . . . ).

[0060] The coarse chips 20.i produced in this manner are scattered onto a belt conveyor 24 by a schematically depicted distribution device 21 to form a coarse chip layer 22 and wetted with a flame-retardant solution 28 by means of a flame-retardant solution application device 26. A pressure difference is subsequently applied to the coarse chip layer 22 by means of a pressure difference generator 30 so that the flame-retardant solution 28 penetrates into the coarse chips 20.i. This results in coarse chips containing flame retardant 32.i, which have less flame retardant on their surface.

[0061] Glue is applied to the coarse chips containing the flame retardant 32.i by means of a glueing device 33. The glueing device 33 may be, for example, a mixer or a coil, i.e.

[0062] a rotating drum.

[0063] The glued coarse chips 31.i are scattered by a first scattering head 34.1 to form a first surface layer 36.1. A middle layer 40 is scattered onto the first surface layer 20.1 by means of a middle layer scatterer 38. A second scattering head 34.2 is used to scatter a second surface layer 36.2 onto the middle layer 40. The layers 36.1, 40, 36.2 are pressed by means of a hot press 42 to form an OSB panel 44.

[0064] The middle layer scatterer 38 scatters middle layer chips 46.i, which are either produced by means of a middle chip production device or separated from the coarse chips 20.i via screening by means of, in this case, a classifier 48. The middle layer chips 46.i are subsequently glued in a second glueing unit 50 and then transported to the middle layer scatterer 38.

[0065] By means of a return device, for example a return line 88, flame-retardant solution 28, which is removed from the coarse chips 20 when the pressure difference is applied to the coarse chips 20, is returned to the reservoir 50. The return line 88 may comprise a filter 90, by means of which wood particles are removed. In addition, the return line preferably comprises a pump for pumping the flame-retardant solution. FIG. 2 shows the distribution device 21, the flame-retardant solution application device 26 and the pressure difference generator 30. The flame-retardant solution application device 26 comprises a reservoir 50 that holds the flame-retardant solution 28. The flame-retardant solution 28 can be brought up to a given temperature T.sub.28 by means of a heater 52, wherein for example 50 C.T.sub.2895 C. The flame-retardant solution 28 is guided to nozzles 56.k by means of a dosing pump 54, said nozzles being arranged next to each other transversely to the direction of material flow M, and from there are sprayed onto the coarse chip layer 22.

[0066] The pressure difference generator 30 has a negative pressure pump 58, which is connected to a plurality of suction chambers 60.j (j=1, 2, . . . ). As a result, a pressure p.sub.j of 100 hPap.sub.j800 hPa, for example, acts on the suction chambers 60.j during operation of the negative pressure pump 58. In this case it is possible that the pressures in the individual suction chambers 60.j differ from one another.

[0067] The suction chambers 60.j rest on a transport belt 62 of the belt conveyor 24, which has openings, for example holes. The pressure pj is thus applied to the coarse chip layer 22.

[0068] It is possible, but not essential, that the differential pressure generator 30 comprises a perforated metal belt 64, as shown in FIG. 2, which presses onto the coarse chip layer 22 from above. Pressure rollers 66.1, 66.2, for example, are provided for this purpose. The suction chambers 60.j rest on the metal belt 64 on the side of the metal belt 64 that faces away from the coarse chip layer 22. As a result, there is an introduction pressure p.sub.22 of, for example, 100 hPap.sub.22800 hPa in the coarse chip layer 22 in the area of the pressure chambers 60.j.

[0069] It is also possible, but not essential, for the differential pressure generator 30 to comprise two sets of suction chamber 60.j and 60.j, as shown in FIG. 2, between which the coarse chip layer 22 is arranged. It is possible, but not essential, that the second set of suction chambers 60.j is connected to a second pump 68. The second pump 68 may be a vacuum pump or a pressure pump.

[0070] It is possible that the pressure pj in the first set of suction chambers 60.j is an overpressure and the pressure p.sub.j in the second set of suction chambers 60.j an overpressure.

[0071] Alternatively, it is possible that the pressure p.sub.j is an overpressure and the pressure pj a negative pressure.

[0072] As a further alternative, it is possible that the pressure p.sub.j is a negative pressure and the pressure p.sub.j a negative pressure.

[0073] As a further alternative, it is possible that the pressure p.sub.j is a negative pressure and the pressure p.sub.j an overpressure.

[0074] An inspection system 70 can be arranged downstream of the pressure difference generator 30 in the direction of material flow M, said system comprising a camera 72. The camera 72 detects light that is emitted or not absorbed by a coloring agent in the flame-retardant solution. Alternatively or additionally, the camera 72 detects fluorescent light. In this way, an actual flame retardant distribution k.sub.ist (x,y) is determined, which denotes a concentration k of flame retardant as a function of the surface coordinates x, y. A controller 74 compares the actual flame retardant distribution K.sub.ist(x,y) with a target flame retardant distribution k.sub.soll(x,y) and controls the nozzles 56.k individually so that a deviation between the actual flame retardant distribution k.sub.ist(x,y) and the target flame retardant distribution k.sub.soll(x,y) is minimized.

[0075] It is possible, but not essential, that the inspection system has a UV light source, which illuminates the coarse chip layer 22 in a field of vision G of the camera 72. Thex field of vision G is the area of the coarse chip layer 22 that is captured using the camera 72. In FIG. 1, the inspection system 70 is not depicted for the sake of clarity.

[0076] FIG. 1 shows that a cutting device 78 can be arranged downstream of the hot press 42 in the direction of material flow, wherein said device cuts the OSB panel 44 into individual panel segments 80.1. In this case, it is advantageous if a second inspection system 82 is arranged, the camera of which 84 captures a cutting surface 86 of the respective panel segment 80.1. This is used to determine a second actual flame retardant distribution K.sub.ist,2 (y,z), which also encodes the depth dependence of the concentration k of flame retardant. In other words, the second actual flame retardant distribution k.sub.ist,2(y,z) encodes a depth gradient of the coloring agent.

[0077] The controller 74 is configured to alter the pressures pj in the at least one suction chamber 60.j and/or of a transport belt speed v.sub.62 of the transport belt 62 so that the second actual flame retardant distribution k.sub.ist,2(y,z) approximates a second target flame retardant distribution k.sub.soll,2(y,z).