EP3269521B1 - Method for manufacturing wood panels - Google Patents

Description

• eine dosierverstellbare Streueinrichtung zur Aufgabe von Holzwerkstoff auf ein Transportband zur Bildung einer Holzwerkstoffmatte,
• wenigstens eine kontinuierliche oder diskontinuierliche Presse, um die Holzwerkstoffmatte mit Druckbeaufschlagung zu verdichten,
• wenigstens eine Trenneinrichtung zur Separierung der gepressten Holzwerkstoffmatte in einzelne, aufeinanderfolgende Platten,
• eine Messstation zur Ermittlung von geometrischen Plattendaten und
• ein Kühl- oder Reifelager, in dem die Platten unter vorgegebenen atmosphärischen Bedingungen gelagert werden, bevor sie zu einer Endverarbeitung oder einem Versand transportiert werden.

The invention relates to a method for producing wood-based panels, in which the following stations are run through:

• a metering-adjustable spreading device for depositing wood material onto a conveyor belt to form a wood-based material mat,
• at least one continuous or discontinuous press to compress the wood-base mat with pressurization,
• at least one separating device for separating the pressed wood-based material mat into individual, successive plates,
• a measuring station for the determination of geometric plate data and
• a refrigerated or maturing warehouse where the plates are stored under predetermined atmospheric conditions before being transported for final processing or shipment.

The mentioned stations are known in the production process of wood-based panels. Particle boards, OSB boards, lightweight boards, multi-layer boards, HDF or MDF boards are mentioned by way of example.

The scatterable good scattered on the conveyor belt (essentially glued wood chips) will be referred to below as wood-based material mat. These wood-based material mats can have thicknesses of a few millimeters up to one meter. The scattering stations are now able both in the conveying direction of the conveyor belt and in the transverse direction, the spread rate to vary over one or more in-line metered adjustable scattering stations. Several successive scattering stations allow the formation of different layers, such as cover and middle layers.

The conveyor belt forwards the wood-based mat to a press. In the invention, this press is realized for applying the supplied via the conveyor belt in a conveying direction wood mat material with pressure and heat usually by a double belt press. Such devices are often used for two purposes. Once they are made by solid products of pressed chips or fibers. The invention focuses on the production of particleboard or fiberboard, as for example from the EP 1 236 552 B1 is known. About the pressure and possibly a distance setting, the grit mat is thus compressed and pressed. On the other hand, the heat supply allows to liquefy binder or to allow moisture to evaporate.

After the press, the produced relatively compacted mat is cut into sheets. These are often measured with regard to their geometric data and, for example, the density in order to intervene directly in terms of control technology in the spreader or the press.

Thereafter, the sheets produced are cooled and / or stored in a known manner before they are treated in a final processing, for example, ground. The manufacturer understandably wants little scrap to be scraped. It would be welcome if the grinding was only used to level the surface quality and no longer had to influence the desired geometric end plate dimensions.

However, this is not possible with today's facilities. The plates are stored after the wood material plant in defined stacks in a maturing storage for a certain period of time. During this period, the plates mature and shrink by a fraction dependent on many boundary conditions. These conditions include, for example, the humidity and temperature in the warehouse, but also at what point in the stack, the respective plate, because the lower plates undergo a significant pressure, while the overhead plates are rather unloaded. This means that the thicknesses of the individual plates in the stack are actually different.

To make matters worse, the plate manufacturer usually wants to vary the dimensions of the product to be produced from time to time. In particular, different plate thicknesses are produced, but also the dimensions in length and width can vary.

DE10005251A1 discloses a method of producing wood-based panels according to the preamble of claim 1.

The object of the invention is therefore to reduce the effort in the final production of the wood-based panels. It is also the object of the invention to obtain the production accuracy in format changes.
With regard to the method, the object with the features of claim 1 is achieved in particular by carrying out at least one further measurement of geometrical dimensions of the plate after the maturing process in the maturing store and by means of the difference of the measured values, a manipulated variable for the metering-adjustable spreading device and / or a setting for the press and / or a setting of the separator is determined and adjusted.
In this way, the plate changes in terms of their geometric and physical data during cooling and / or maturation storage occur at the manipulated variables in the area of the spreading device and the press and the separating device are taken into account. In this context, a setting for the press means either the pressure setting in the press or the temperature setting in the press or the distance setting in the press. These can vary in the longitudinal and transverse directions.

It has been shown in tests that the part of the plate still to be abraded or cut in the finishing process for the completion of the plates could be reduced by at least 50%. Without the final measurement after the cooling or maturing warehouse, the safety reserves for material addition had to be set significantly higher for format changes.

With the method according to the invention it is now possible to set the scattered quantity on the conveyor belt much more accurately and in a predetermined manner for the current plate thickness. Similarly, one knows more exactly about the results that result from the press pressure and the press temperature.

In many cases, no second measuring station must be set up for the further measurement. In order to register the change of the plate in a cooling or maturing storage process, it is sufficient in some cases to determine the change value once, using the same measuring station as in the first measurement. For a specific desired format, therefore, a significantly more accurate control value for the metering-adjustable spreading device and / or the setting in the press and / or the setting of the separating device can be determined. The use of measuring equipment does not have to be increased.

On the exact manipulated variables in the area of the spreading device (for example by means of dosing valves or wheels), the pressurization in the press (For example, via pressure cylinder to press plates) or the separator (for example, the saw cut angle) will not be discussed here, because these possibilities are known in the art.

It is advantageous if both the measured measured data before as well as those stored after cooling or maturing storage in at least one data store and compared and evaluated by a central computer.

This gives the geometric change of a particular format, which occurs during the cooling or maturing storage. These can be stored in the data memory and be used directly with a recurring same format setting.

Preferably, the central computer is also supplied with the parameters product type and / or storage time and / or ambient temperature and humidity in the warehouse.

It is equally preferable if, in addition to the product type, the relationship with all determined production parameters and the environmental influences as well as the ambient temperature or the air humidity in the areas of production in the central computer is taken into account.

These parameters have an influence on the plate change and can thus be taken into account by the central computer for evaluation of the manipulated variables of the spreading device or the press or the separating device.

It is advantageous if control values are forwarded from the central computer to the spreading device or the press or the separating device.

The central computer, which has determined the actual change of a particular format that occurs during the cooling or maturing storage, can allocate manipulated variable changes to the spreading device or the press or the separating device in the fastest way which minimizes the oversize to be abraded or cut off in the production process.

Preferably, the plates supplied to the cooling or maturing storage are identified.

The identification makes it possible with great certainty to be able to unambiguously assign the dimensions before and after the cooling or maturing storage of each plate. Identifications may be by markings such as color markings, bar code imprints, numbering, or even RFID chips. In addition, all produced plates can be verified with their associated measurement data.

Preferably, in plates before and after the cooling or maturing storage in the same places their thickness is measured.

The measurement effort is considerably reduced if, for example, the thickness or its difference in the ripening process is determined exactly at the same point on a plate. The number of measuring points, however, depends on different production parameters.

In order to obtain a good accuracy over the entire length and width of the plates, it is preferably provided that each plate is subjected to a predefined measuring grid in both measurements.

It is advantageously provided that the plates supplied to the maturing warehouse are assigned to the mat section corresponding to the preceding production process.

In this way, the setting potential is again increased significantly. If, for example, the mat thickness is already additionally determined in the method according to the scattering device, the plate measurement can be used to identify how the spreading device must be corrected, for example in the transverse profile, so that the accuracy of the plate thickness across the width is particularly good after passing through the press.

It is particularly advantageous if, due to the difference measurements, manipulated variable characteristics are applied for each format and / or each product.

These characteristics can be stored in the data memories or in the central computer. For a desired format or product conversion can be made to the stored characteristics and the throughput of the spreader or the pressures in the press, preferably longitudinally, but also cross profile controlled from the outset to be set. This considerably reduces the otherwise resulting rejects during format or product changes.

The invention will be explained in more detail below with reference to the single drawing. This shows a schematic, highly simplified representation of an apparatus for the production of wood-based panels. Based on the individual stations, the manufacturing method according to the invention will be explained.

In three superposed rows aggregates or stations of the apparatus for the production of wood-based panels 1 are outlined, which are in succession from right to left in succession.

In the upper row, a spreader 2 with three scatter stations 3a, 3b, 3c is shown. The scattering station 3a and 3c scatter a lower and an upper cover layer, the station 3b, the middle layer of a wood material mat, not shown on the conveyor belt 4. The flow rate of the material to be spread, ie the wood material is by means of the indicated scattering rollers and possibly by guide and closure plates, preferably also different in the transverse profile, metered.

In the second row, the scattered wood-based material mat is passed on the conveyor belt 4 via the illustrated Fehlschüttungsaufnahme 5 to the continuous double belt press 6. In this, the wood-based mat is compressed under pressure and temperature to a solid wood material. For compression, for example, not shown in detail hydraulic cylinders are used, which are multiple times in the conveying direction and across and act on heatable press plates. Thickness and density profiles in the transverse and longitudinal directions can be influenced by these hydraulic cylinders.

On the double belt press follows the separator 7 in the form of a sawing station. There, the pressed wood material is cut into slabs both in the longitudinal and in the transverse direction. The (circle) saws are motor-adjustable, both in their distance and in their cutting angle setting. As a result, the cutting of the plates in the 1/10 mm range can be set exactly. Optionally, after the separating device 7, an identification point 16 follows, in which the plates are made unambiguously assignable for later purposes, and a plate scale 8.

In the third row, the first measuring station 9.1 follows on the right. In it at least geometrical data of the plate can be detected. These include length, width and thickness. The acquired data is sent via a data line 14.1 to a data memory 11.1, stored there and / or forwarded to a central computer 12.

Following the plate is spent according to the method of the invention in a cooling and / or maturing 10. In the storage areas, the plates are often stacked on top of each other so that the lower plates are subjected to a greater load. After maturation, the plates may thus have a very different thickness, for example.

In a second measuring process of the geometric data after the maturing process, which can take place on a second measuring station 9.2 with separate data memory 11.2 or else on the first measuring station 9.1, the geometric data are again recorded. The identified plate is measured by means of a predefined measuring grid in the same places as in the first measuring process. These data are also supplied to the central computer via data lines 14.1, 14.2. In the central computer, the measured data are compared and evaluated. In addition, other variables, such as the product type and / or the storage time and / or the ambient temperature and humidity in the warehouse can be included in calculations. The central computer determines characteristic curves for specific products or formats and can change control variables on the spreader 2, the double-belt press 6 or the separating device 7 via control lines 13.1, 13.2, 13.3.

With high efficiency, the plates supplied to the maturing storage can be assigned to the corresponding in the previous manufacturing process mat section. That means the ones in the stack below and those in the stack overhead plates already scattered or pressed in the manufacturing process. This results in the entirety that, for example, all plates have the predetermined same thickness.

All these measures cause that in the finishing station, in this one grinding system 15, no significant oversizes must be sanded more. Rather, the surface is only equalized because the geometric dimensions of the plate with the method according to the invention have been set very accurately in advance.

LIST OF REFERENCE NUMBERS

1

Apparatus for producing wood-based panels

2

scattering device

3a, 3b, 3c

spreading station

4

conveyor belt

5

Reject material recording

6

Press, continuous double belt press

7

Separating device, sawing station

8th

Libra

9.1, 9.2

Observed

10

Cooling and / or maturing warehouse

11.1, 11.2

data storage

12

mainframe

13.1, 13.2, 13.3

control lines

14, 1, 14.2

data line

15

Finishing station, grinding plant

16

identification point

17

campsite

Claims (10)

1. Method of manufacturing wood based boards in which the following stations are passed through:

   - a dose-adjustable spreading device (2) for applying wood material onto a conveyor belt (4) to form a wood material mat,

   - at least one continuous or discontinuous press (6) for compressing the wood material mat through the application of pressure,

   - at least one partitioning device (7) for separating the pressed wood material mat into successive individual boards,

   - a measuring station (9.1) for determining geometric board data and a

   - a cooling or ageing store (10) in which the boards are stored under predetermined atmospheric conditions before they are transported to a final treatment station (15) or despatched,

   characterised in that at least one further measurement of geometric dimensions of the board takes place after the ageing process in the cooling or ageing store (10) and in that by means of the difference in measurements a control variable for the dose-adjustable spreading device (2) and/or a setting for the press (6) and/or a setting of the partitioning device (7) is determined and set.
2. Method according to claim 1 characterised in that both the data measured before and the data measured after the cooling or ageing storage are stored in at least one data memory (11.1, 11.2) and are compared and evaluated by a central computer (12).
3. Method according to claim 2 characterised in that the central computer (12) is also supplied with the parameters product type and/or storage time and/or ambient temperature and relative humidity in the cooling and/or ageing store (10).
4. Method according to claim 2 or 3 characterised in that the connection with production parameters, such as the ambient temperature and relative humidity, is taken into consideration in the central computer (12).
5. Method according to any one of claims 2 to 4 characterised in that from the central computer (12) control variable s are forwarded to the spreading device (2) or the press (6) or the partitioning device (7) .
6. Method according to any one of claims 1 to 5 characterised in that the boards supplied to the cooling or ageing store are identified.
7. Method according to any one of claims 1 to 6 characterised in that the thickness of boards is measured at the same points before and after the cooling or ageing storage.
8. Method according to any one of claims 1 to 7 characterised in that in both measurements a predefined measuring grid is applied to every board.
9. Method according to any one of claims 1 to 8 characterised in that the boards supplied to the cooling or ageing store (10) are assigned to the corresponding mat section in the preceding manufacturing process.
10. Method according to any one of claims 1 to 9 characterised in that on the basis of the difference measurements control variable characteristics for each format and/or every product are created.

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