Device and method for producing a mat from free-flowing material on an air-impermeable conveyor belt and system for pressing such a mat

Abstract

Device for producing a mat (1) from free-flowing material (14) on an air-impermeable conveyor belt (2), preferably from chips, fibers and / or chips from biomass, optionally with the addition of binder and / or plastics, comprising: at least one device (3) for producing a mat (1) from material (14) on an air-impermeable conveyor belt (2); an adjusting device (4) for adjusting the surface weight of the mat (1) by means of at least one mat-side removal roller (5) and actuators (9) arranged on the opposite side of the conveyor belt (2), with which the conveyor belt (2) can be displaced relative to the removal roller (5), a measuring device (6) for determining at least one measured value of the mat (1) and a control or regulating device for controlling or regulating the adjusting device (4), wherein at least one actuator (9) is arranged in a vacuum chamber (10) and the vacuum in the vacuum chamber (10) is suitable for exerting a force on the air-impermeable conveyor belt (2) which is directed away from the removal roller (5) and / or at least partially in the direction of gravity.

Description

[0001] The invention relates to a device for producing a mat on an air-impermeable conveyor belt according to the preamble of patent claim 1, a method for producing a mat on a conveyor belt according to the preamble of patent claim 9 and a plant for producing material boards according to claim 8.

[0002] In the production of material boards from spreadable materials, a material, usually a mixture of particles or fibrous substances and a binding agent, is spread onto a forming or conveyor belt to form a mat of spreadable material. The mat is then subjected to any necessary pretreatment and finally to pressing. Pressing can be carried out continuously or discontinuously using pressure and heat. These are usually particleboard, fiberboard, or chipboard. The spreading takes place in one or more layers, as required, although the need for multiple layers usually arises in the production of thicker boards. However, different layers may also be desired in the production of thin boards, especially if there are specifically differentiated requirements between the middle layer and the cover layers.

[0003] Due to the increasing demand for raw materials on the global market in general, and for wood in particular, raw material costs are a significant factor. Producers are forced to compete to make their production processes more cost-effective. This requires a production facility today to demonstrate a high degree of flexibility in the following key areas in order to be able to handle orders at full capacity in the long term: - Processing of the widest possible range of raw materials, preferably from the immediate vicinity of the plant (wood, waste, etc.), - Production of small batches, niche products and special density profiles requested by the customer and thus a quick and easy online conversion of the product range, - Ensuring optimal basis weight distribution across the length and width of the product and - optimal thickness tolerance to avoid unnecessary sanding during final production.

[0004] Not only are the material costs themselves significant, but the investment and processing costs of wood material into powdered chips include not only the very expensive drying process (which requires energy), but also the use of expensive glue. Furthermore, the buyer of the produced boards receives material that is too dense, which can potentially cause problems later in logistics or sales.

[0005] It is already known from DE 10 2008 027 708 A1 that a measuring device is arranged between the spreading device and the press to measure the actual value of the basis weight profile, and thus the relative basis weight, of a pressed material mat, that a control device for comparing the actual value with the target value of the basis weight profile and for determining control variables is arranged on at least one setting device within the spreading device and that the measuring device and at least one setting device are arranged within a distance of less than 5 m based on the length of the pressed material mat.

[0006] From DE 10 2008 030 417 or DE 10 2013 002 259 A1 a further device is known in which, after a pre-compaction of the pressed material mat, an adjustment device for the basis weight by means of a removal unit and a measuring device for determining the basis weight or the density of the pressed material mat are arranged.

[0007] From DE 10 2011 016 343 B4 a method for adjusting the basis weight of a bulk material mat spread on a conveyor belt is also known, wherein the basis weight of the bulk material mat is again measured by an independent device in front of a removal roller.

[0008] Finally, DE 10 2017 111 178 proposes further improving the accuracy of leveling a mat on a conveyor belt by increasing the complexity of the measurement technology. However, it has been shown that the implementation of the now advantageous measurement results encounters mechanically adjustable limits with the existing manufacturing devices.

[0009] DE 20 2004 004 037 U1 shows a plant for the production of chipboard and fiberboard in which the mat is compressed by negative pressure through an air-permeable forming belt before pressing.

[0010] The invention is therefore based on the object of creating a method and a device with which the accuracy during leveling or setting of the predetermined basis weight of the material lying on an endlessly circulating conveyor belt can be improved.

[0011] It is a further object of the invention to produce a mat of the material with predetermined properties independent of the fluctuations in the upstream processes.

[0012] The invention is based on a device for producing a mat from free-flowing material on a conveyor belt, wherein the material preferably consists of chips, fibers and / or chips from biomass, optionally with the addition of binder and / or plastics, comprising: at least one device for producing a mat of free-flowing material on an air-impermeable conveyor belt; an adjusting device for adjusting the surface weight of the mat by means of at least one mat-side removal roller and actuators arranged on the opposite side of the conveyor belt, with which the conveyor belt can be displaced relative to the removal roller, a measuring device for determining at least one measured value of the mat and a control device for controlling or regulating the adjustment device, wherein at least one actuator is arranged in a vacuum chamber and wherein the vacuum in the vacuum chamber is suitable for exerting a force on the conveyor belt which is directed away from the removal roller and / or in the direction of gravity.

[0013] Advantageously, when adjusting an actuator, the conveyor belt can now better follow the shape of the conveyor, thus significantly improving the adjustment accuracy of the adjustment device. This is particularly advantageous when adjacent actuators have a large adjustment gradient relative to each other.

[0014] Another advantage is that the negative pressure expands the adjustment options, because not only can the belt be moved relative to the removal roller using the actuators, but the negative pressure can also increase the distance between the conveyor belt and the mat lying on it and the removal roller. Thinking in the opposite direction, the stroke and thus the complexity of the actuators can be reduced while maintaining the same travel ranges / options.

[0015] The invention can also be used advantageously in a dosing bunker, which has been disclosed in DE 10 2006 012 430 A1.

[0016] Preferably, the vacuum chamber can be designed essentially as a box open on one side, preferably U- or V-shaped, with the conveyor belt guided along the open side of the vacuum chamber. The vacuum chamber can be connected to a vacuum source. Preferably, the vacuum source can be adjustable at least with respect to the strength or the volume flow per t.

[0017] Alternatively or additionally, a seal and / or a plain bearing are arranged between the edges of the vacuum chamber and the conveyor belt. This has the advantage of reducing friction between the conveyor belt and the vacuum chamber, thus reducing wear.

[0018] Alternatively or cumulatively, several vacuum chambers can be arranged across the width of the conveyor belt, preferably corresponding to the number of actuators or according to a group-wise arrangement of the actuators per vacuum chamber. This allows for more refined control during adjustment.

[0019] Alternatively or additionally, the vacuum chamber or the associated adjustment device can be connected to a control or regulating device, which is preferably suitable for controlling or regulating the force of the vacuum chamber on the conveyor belt. Preferably, a controllable vacuum source can be provided, or a valve for the targeted introduction of secondary air into the vacuum chamber can control the vacuum accordingly.

[0020] Alternatively or cumulatively, the removal rollers, the positioning tables, and / or the actuators can be individually controllable and have a height adjustment. Height adjustment means that the actuators / positioning tables are designed, for example, as actuators, pressure or hydraulic cylinders, spindle drives, or the like, or are operatively connected to them. These can preferably be designed to be height-adjustable individually or in groups.

[0021] The invention is advantageously used in a plant for producing material plates, comprising a device according to the above-mentioned features with a press, preferably a continuously operating press, for pressing the mat into a material plate.

[0022] The invention of a method for producing a mat from free-flowing material on a conveyor belt, preferably from chips, fibers and / or chips from biomass, optionally with the addition of binder and / or plastics, preferably during the pressing of the mat into a material plate, uses the following process steps: - producing a mat of free-flowing material on the airtight conveyor belt by means of a device; - adjusting the surface weight of the mat with an adjusting device, whereby the material is levelled and / or removed by means of at least one mat-side removal roller, whereby the distance between the conveyor belt and the removal roller can be adjusted by means of adjusting elements arranged on the opposite side of the conveyor belt, - measure at least one measurement value of the mat, - controlling or regulating the setting device based on a specified value and / or the measured value, - wherein at least in the region of an actuator, a force is applied to the conveyor belt by means of a vacuum chamber, which force is directed away from the removal roller and / or at least partially in the direction of gravity.

[0023] The following features are suitable for further improving the invention listed above and can be used alone or in various combinations with the above-mentioned features: Preferably, a measuring device is arranged to determine the relative scattering distribution of the mat transverse to the production direction and a further measuring device is arranged to determine the absolute basis weight of the mat.

[0024] By arranging two measuring devices for measuring the measured values ​​of the mat, it is now possible to eliminate fluctuations in the production process and to achieve a desired profile or profile of the pressed material mat without compromising on the absolute basis weight of the mat.

[0025] A preferred embodiment is characterized in that the first measuring device is a transmission device comprising a radiation source and a sensor. The radiation source is preferably an X-ray source or a gamma radiation source. The transmission device is particularly suitable for determining the scattering density or the relative basis weight of the mat transverse to the production direction. In particular, a transmission device can enable the measurement of the relative basis weight in tracks. The relative basis weight indicates how much material is arranged in one track in relation to the material in another track and is a measure of the weight distribution. For example, tracks with more material can be present in the mat at locations where fastening elements will later be inserted.

[0026] Alternatively, or in combination, the second measuring device is a mechanical basis weight scale. The basis weight scale allows for the simple measurement of the absolute basis weight. The absolute basis weight across the entire width is also an important measurement value for verifying the suitability of the produced board for specific applications.

[0027] Preferably, the first measuring device is arranged followed by the second measuring device, or vice versa. Preferably, the relative basis weight is determined first, followed by the absolute basis weight. This allows the appropriate profile to be set, and then the total weight of the mat to be adjusted accordingly. If the total weight is too low, the desired absolute basis weight can be achieved by evenly spreading more material or adjusting the height of the removal unit.

[0028] An alternative embodiment is characterized in that the adjustment device comprises at least one removal roller, preferably a plurality of removal rollers arranged across the width transverse to the production direction, and more preferably one or more adjusting tables with adjusting elements, which are arranged below the removal roller under the conveyor belt for lifting the mat. By arranging a plurality of removal rollers, tracks can be created in the mat or local fluctuations in the dispersion of the mat can be removed in a targeted manner. Accordingly, the adjusting tables / actuators can be designed with the same width as the removal rollers, so that each removal roller can be assigned an adjusting table / actuator. The adjusting tables / actuators below the conveyor belt can lift the mat, thus achieving improved removal with the removal roller opposite the adjusting table. In addition, the removal depth can be increased.

[0029] Preferably, the removal rollers and / or the adjustment tables / actuators are individually controllable and / or the removal roller and / or the adjustment tables / actuators are individually height-adjustable. This allows tracks to be created in the mat, local fluctuations to be removed in a targeted manner, and, in particular, a relative basis weight to be adjusted.

[0030] Preferably, a control unit is provided for controlling or regulating the input of material into the spreading station and / or the removal unit and / or the removal rollers depending on the measured values ​​of the first measuring device and the second measuring device. The measured values ​​obtained by the first and second measuring devices can be compared with a predetermined target value, and appropriate action can be taken in the event of deviations. For example, an increased absolute basis weight can be measured due to the addition of a different type with a slightly different density to the material, so that either more material should now be removed by the removal unit or less material is fed to the spreading device.

[0031] Further advantageous measures and embodiments of the subject matter of the invention will become apparent from the following description and the drawing.

[0032] The drawing shows a system in a side view in the upper area and a corresponding plan view from above of the system in the lower area. In addition to a press 12 and a pre-press 11 for pressing a spread mat 1, the system comprises a device 3 for producing this same mat 1. A material 14, which comprises, for example, wood fibers or chips, is fed to the device 3, which applies the material 14 to a mat 1, also referred to as a fleece, on a preferably endlessly circulating conveyor belt 2. Adjacent to the device 3 is an adjusting device 4 for leveling and / or removing excess spread material 14 from the mat 1 or for creating a desired profile of the mat 1 transversely to the production direction 13. The adjusting device 4 comprises a removal roller 5, which is arranged transversely to the production direction 13.Alternatively, several removal rollers can be arranged adjacent to each other or offset from each other across the width.

[0033] The removed material 14 is sucked away by means of a suction channel arranged above the removal roller 5 and preferably fed back to the device 3 as material 14. To determine the input height of the mat 1, a sensor (not shown) can be arranged in front of the removal roller 5. The removal roller 5, or preferably each of the removal rollers 5, can be controlled separately and is height-adjustable so that they can penetrate deeper or less deeply into the mat 1 and remove material 14. Preferably, in the case of a removal roller 5, several adjusting tables 15 with adjusting elements 9 are arranged below the conveyor belt 2, which can lift the mat 1 in the direction of the removal roller 5, against the force of gravity, in order to further increase the removal.

[0034] According to the invention, the actuators 9 are located within a vacuum chamber 10, which has an open upper side over which the conveyor belt 2 slides. In order to minimize friction, plain bearings or geometric curves can be provided at the contact points, which minimize the friction between the vacuum chamber 10 and the conveyor belt. The use of a seal 16 is also possible. The conveyor belt is pulled against the force of gravity and away from the removal roller 5 by the vacuum chamber 10. If the adjusting tables 15 and / or the actuators 9 are now moved in the direction of the removal roller by means of a height adjustment 8, in a hypothetically optimal case only the area of ​​the continuous conveyor belt 2 with contact is moved, whereby adjacent areas of the conveyor belt 2 are pulled downwards in the direction of gravity or away from the removal roller 5 by the vacuum in the vacuum chamber.This results in a finer tunability of the conveyor belt 2 across its width compared to the prior art. The vacuum chamber 10 is preferably operatively connected to a variably adjustable vacuum source 18.

[0035] The mat 1 then passes through a first measuring device 6, which in the present embodiment comprises a radiation source at the top and a sensor at the bottom, preferably with evaluation electronics. Such a measuring device 6 can be used in particular to determine the relative basis weight or the profile of the mat 1 transversely to the production direction 13. The radiation source, which can be embodied as an X-ray source or gamma emitter, illuminates the mat 1, whereby the sensor detects the residual radiation and, using the evaluation electronics, can create an image of the profile of the mat 1.

[0036] Further on, a second measuring device is arranged upstream of an optional pre-press 11, which serves to determine a further parameter of the mat 1. In particular, the second measuring device can be designed as a basis weight scale 17 for determining the absolute basis weight of the mat 1. Alternatively, the second measuring device can also be arranged downstream of the pre-press 11. After the mat 1 has now passed through at least the measuring device 6, it is fed to a press 12, which in the present example is designed as a continuously operating press 12, and pressed.

[0037] Both the first measuring device 6 and the optional second measuring device, as well as the adjustment device 4 and their components, are operatively connected to a control or regulating unit (not shown). Using the control or regulating unit, a specific profile and basis weight of the mat 1 can be specified and the input of material 14 into the device 3 can be adjusted accordingly. Using the adjustment device 4, the desired profile can now be created in the mat 1 or the mat 1 can be leveled. Using the first measuring device 6 with the radiation source, an actual value of the profile of the mat 1 can be detected and compared in the control unit with the target value or the target profile.Should deviations in the profile occur, the individual removal rollers 5 or the adjusting tables 15, or the actuators 9, can be controlled accordingly and their height adjusted using the height adjustments 7, 8, so that more or less material is removed from individual tracks of the mat 1 and the corresponding profile is adjusted. In addition to the measures explained so far, the speed of the conveyor belt 2 can of course also be controlled or regulated accordingly. The height adjustments 7, 8 can be implemented as pneumatic or hydraulic cylinders, actuators, or the like.

[0038] The invention has been comprehensively described and explained with reference to the drawings and the description. The description and explanation are to be understood as exemplary and not restrictive. The invention is not limited to the disclosed embodiments. Other embodiments or variations will become apparent to those skilled in the art upon use of the present invention and upon careful analysis of the drawings, the disclosure, and the following claims.

[0039] In the claims, the words "comprising" and "having" do not exclude the presence of further elements or steps. The undefined article "a" or "an" does not exclude the presence of a plurality. A single element or unit can perform the functions of several of the units recited in the claims. The mere repetition of some measures in several different dependent claims should not be understood to mean that a combination of these measures cannot also be used advantageously. Reference signs in the claims are not to be understood as limiting. Reference symbol list P1581: 1 mat 2 conveyor belt 3 Spreading device 4 Adjustment device 5 removal roller 6 Measuring device 7 Height adjustment 8 Height adjustment 9 actuators 10 vacuum chamber 11 Pre-press 12 Press 13 Production direction 14 Materials 15 Adjustment table 16 Seal 17 Basis weight scale 18 Vacuum source

Claims

[1] Device for producing a mat (1) from free-flowing material (14) on an airtight conveyor belt (2), preferably from chips, fibers and / or shreds of biomass, optionally with admixture of binder and / or plastics, comprising: at least a device (3) for producing a mat (1) from material (14) on an airtight conveyor belt (2); an adjusting device (4) for adjusting the basis weight of the mat (1) by means of at least one mat-side removal roller (5) and adjusting elements (9) arranged on the opposite side of the conveyor belt (2), with which the conveyor belt (2) can be displaced relative to the removal roller (5), a measuring device (6) for determining at least one measured value of the mat (1) and a control or regulating device for controlling or regulating the adjustment device (4), wherein at least one actuator (9) is arranged in a vacuum chamber (10) and the vacuum in the vacuum chamber (10) is suitable to exert a force on the airtight conveyor belt (2) which is directed away from the removal roller (5) and / or at least partially in the direction of gravity. [2] Device according to claim 1, characterized by , that the vacuum chamber (10) is essentially designed as a box open on one side, with the conveyor belt (2) being guided along the open side of the vacuum chamber (10). [3] Device according to any one of the preceding claims, characterized by , that a seal (16) and / or a sliding bearing is arranged between the vacuum chamber (10) and the conveyor belt (2). [4] Device according to any one of the preceding claims, characterized bythat several vacuum chambers (10) are arranged across the width of the conveyor belt (10), preferably corresponding to the number of actuators (9) or corresponding to a group arrangement of the actuators (9) per vacuum chamber (10). [5] Device according to any one of the preceding claims, characterized by , that the vacuum chamber (10) is arranged connected to a vacuum source and preferably the vacuum source is adjustable with respect to the strength or volume flow / t. [6] Device according to any one of the preceding claims, characterized by that the vacuum chamber (10) is connected to a control or regulating device which is preferably suitable to control or regulate the force of the vacuum chamber (10) on the conveyor belt (2). [7] Device according to any one of the preceding claims, characterized bythat the removal rollers (5), the positioning tables (15) and / or the actuating elements (9) can be controlled individually, preferably in height-adjustable versions. [8] Plant for the production of material sheets, comprising a device according to any one of claims 1 to 7; and a press (12), preferably a continuously operating press (12), for pressing the mat (1) into a material sheet. [9] Method for producing a mat (1) from free-flowing material (14) on an airtight conveyor belt (2), preferably from chips, fibers and / or shreds of biomass, optionally with admixture of binder and / or plastics, preferably in the course of pressing the mat into a material sheet, comprising the following process steps: - producing a mat (1) from material (14) on the airtight conveyor belt (2) using a device (3); - adjusting the surface weight of the mat (1) with an adjusting device (4), wherein the material (1) is leveled and / or removed by means of at least one mat-side removal roller (5), wherein the distance between the conveyor belt (2) and the removal roller (5) is adjustable by means of adjusting elements (9) arranged on the opposite side of the conveyor belt (2), - measure at least one measurement of the mat (1) and - control or regulate the adjusting device (4), preferably with a control or regulating device, based on a predetermined value and / or the measured value, wherein at least in the area of ​​an actuator (9) a force is applied to the airtight conveyor belt (2) by means of a vacuum chamber (10), which is directed away from the removal roller (5) and / or at least partially in the direction of gravity. [10] Method according to claim 9, characterized by, that the vacuum chamber (10) is connected to a vacuum source (8) and that the vacuum source is preferably adjustable at least with respect to the strength or volume flow / t. [11] Method according to claim 9 or 10, characterized by , that the vacuum chamber or the adjusting device (4) is connected to the control or regulating device to control or regulate the force of the vacuum chamber on the conveyor belt.

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