Wind scattering device and scattering method

Abstract

The invention relates to a wind scattering device and a method for scattering scatter material onto a scatter material conveyor (4), comprising at least one wind scattering chamber (2), which has an upper scatter material opening (6), via which scatter material is introduced into the wind scattering chamber, and at least one fan (7) for generating at least one air flow (L) for separating the scatter material in the wind scattering chamber (2), wherein the air flow (L) generated by the at least one fan (7) enters the wind scattering chamber (2) via an inflow surface (F) which extends along the height and optionally the width of the wind scattering chamber (2), wherein a first grid (8) having profiles (15, 15.1, 15.2) connected in a first frame (13) and arranged next to one another is provided between the at least one fan (7) and the inflow surface (F), wherein first through-flow openings (19) are located between the profiles (15, 15.1, 15.2). In order to create a wind scattering device and a scattering method using such a wind scattering device, by means of which high-quality scatter material mats can be produced in an economical manner and which are characterised by an air flow distribution that is particularly easy to adjust and a more compact and more economical design, according to the invention a second grid (9) having profiles (16, 16.1, 16.2) connected in the first frame (13) or a second frame (14) and arranged next to one another is provided adjacently, wherein second through-flow openings (20) are located between the profiles (16, 16.1, 16.2) and a plurality of the profiles (15, 15.1, 15.2) of the first grid (8) run parallel to the profiles (16, 16.1, 16.2) of the second grid (9) and are arranged offset in a projection plane at right angles to the air flow direction (L), and a plurality of the profiles (15, 15.1, 15.2) of the first grid (8) can be moved towards one another or away from one another relative to the profiles (16, 16.1, 16.2) of the second grid

Description

[0001] Wind spreading device and method for spreading

[0002] The invention relates to a wind-dispersing device for spreading material onto a spreading material conveyor, comprising at least one wind-dispersing chamber which has an upper opening for the spreading material, through which the spreading material is introduced into the wind-dispersing chamber, and at least one fan for generating at least one airflow (L) for separating the spreading material in the wind-dispersing chamber, wherein the airflow (L) generated by the at least one fan enters the wind-dispersing chamber via an inlet surface (F) which extends along the height and optionally the width of the wind-dispersing chamber, wherein a first grid with profiles connected in a first frame and arranged side by side is provided between the at least one fan and the inlet surface (F), wherein first flow openings are located between the profiles.

[0003] The invention further relates to a method for spreading material onto a spreading material conveyor with such a wind spreading device.

[0004] Such a (wind-)spreading device is typically integrated into a spreading system for the production of spreading mats for the manufacture of engineered panels, particularly wood-based panels. Wood-based panels refer specifically to particleboard made from wood chips or, alternatively, fiberboard made from wood fibers. However, the invention also encompasses other engineered panels. The spreading mats, which are spread onto the spreading conveyor (e.g., a belt conveyor), are pressed into engineered panels, such as wood-based panels, using pressure and / or heat in a press, for example, a continuous press or a batch press. The quality of the manufactured panels, e.g., wood-based panels, depends significantly on the quality and properties of the spreading mats produced by the spreading device. The spreading material is typically adhesive, e.g.,Glued shavings or alternatively glued fibers, which can be fed to the spreading device from a spreading material hopper or metering hopper, for example.

[0005] A spreading system can have several spreading devices, also called spreading heads, for example, when multi-layered spreading mats consisting of (two) top layers (e.g., of fine material) and, for example, a middle layer (e.g., of coarse material) are to be produced. In the production of multi-layered mats, the individual spreading devices are arranged one after the other along the conveying direction of the spreading belt conveyor, so that first a first top layer is spread onto the spreading belt conveyor, then one or more middle layers onto this first top layer, and then a second top layer onto the middle layer(s). The wind-driven spreading device according to the invention can, for example, be used to produce top layers within such a spreading system.The airflow generated in the air separator chamber separates the chips, with coarser chips falling near the inlet and finer chips falling towards the rear, i.e., in the area of ​​the chamber furthest from the inlet. In this way, depending on the orientation of the separator relative to the direction of travel of the conveyor belt, layers, such as top layers, can be produced whose chip size varies towards the surface of the material, becoming finer, for example. Optionally, one or more screens can be arranged in the air separator chamber to optimize the separation. In practice, air separators of the type described above are used, in which the flow or airflow necessary for air separation is generated by a common air generation system with one or more high-performance fans.The airflow generated by the fan(s) is directed into a pre-chamber where dynamic pressure is created. From this dynamic pressure chamber, individual discharge pipes carry the airflow into the actual wind scattering chamber. The number of discharge pipes can be regulated by baffles. This allows for the most homogeneous possible distribution of wind speeds across the entire cross-section of the wind scattering chamber.

[0006] Such a wind scattering device is described, for example, in DE 10 2015 112 013 A1. In the area of ​​the inlet surface to the wind scattering chamber, a nozzle unit is provided, which has a plurality of outlet nozzles arranged in slots and rows, wherein the outlet nozzles each taper in a funnel shape in the direction of flow from a rectangular inlet cross-section to a round or oval outlet cross-section. A register unit can be arranged downstream of the nozzle unit in the direction of flow, which has several register strips side by side, each of which has several openings distributed along its height, corresponding to the outlet nozzles, and is height-adjustable for setting variable outlet cross-sections of the nozzle unit. In the prior art, the register unit has a perforated sheet-like character, which in a more extensive design could perhaps already be described as a grid.This register unit is arranged in front of the nozzles, and by changing its height, the airflow cross-sections to the nozzle inlet are altered. In this embodiment, a few large fans are provided, each generating vertically oriented airflows. The air supply housing is designed as a deflecting housing with at least one vertical housing section, one horizontal housing section, and a deflecting section arranged between them. At least four fans can be provided, of which—each via an interposed deflecting section—two fans are assigned to an upper region of the nozzle unit and two fans to a lower region of the nozzle unit. Such air dispersion devices have generally proven effective in practice, but they are capable of further development—this is where the invention comes in.

[0007] Furthermore, DE 1 205 274 B describes a forming station for the production of grit mats during the manufacture of wood-based panels, in which the grit particles are transported via a conveyor belt to a discharge point, and in the path of the grit particles from this discharge point to the grit conveyor on which the mat is produced, either one or more vibrating frames, one or more special throwing rollers, one or more vortex nozzles, or a combination of these units are provided, over or past which the grit particles coming from the discharge point must pass in essentially different directions for orientation. Wind nozzles may be provided to generate air vortexing.

[0008] The invention is based on the objective of creating a wind spreading device and a spreading method with such a wind spreading device with which high-quality spreading mats can be produced economically and which is characterized at the same time by a particularly easy-to-adjust airflow distribution and a more compact and economical design.

[0009] To solve this problem, the invention teaches, in a generic spreading device of the type described above, that a second grid with profiles connected and arranged side by side in the first frame or a second frame is provided adjacent to the first grid, wherein second flow openings are located between the profiles and a plurality of the profiles of the first grid are arranged parallel to the profiles of the second grid and offset in a projection plane perpendicular to the direction of airflow (L) and a plurality of the profiles of the first grid can be moved relative to each other or away from each other by means of at least one adjustment device.

[0010] The mobility of the profiles of the first grid relative to the profiles of the second grid makes it particularly easy to adjust the air volume flow, any air turbulence, the flow conditions, the air distribution occurring in the wind scattering device in the vertical and / or horizontal profile and many other settings.

[0011] By using predominantly vertical profiles for the grids, one has a particular ability to influence the air profile across the width of the wind dispersal chamber, which in turn can be used to improve the distribution of the material within the dispersed mat. This allows, for example, more or less airflow to be supplied to the edges as needed.

[0012] The frame can be easily constructed using a crossbeam at both the top and bottom of the profiles. This broadens the definition of "frame," allowing for a design with only one crossbeam connecting the profiles. In this description, the term "frame" refers to a type of support for at least one grid.

[0013] Preferably, the first grid or its frame is fixed to the wind deflector, so that only the profiles of the second grid are arranged to be movable, allowing them to change their distance to the first grid. This further simplifies the design.

[0014] Depending on the desired accuracy requirements regarding the flow conditions across the width or height of the wind deflector, either the entire second grid or individual profiles of the second grid can be moved closer to or further away from the first grid within their frame. The latter preferably have a separate adjustment mechanism relative to the frame. This adjustment mechanism can be a manually operated screw connection, for example, in a slotted hole, or it can be a sophisticated system using individual actuators. In any case, it is preferred that the adjustment mechanism has translational guidance. For the purposes of the invention, it is irrelevant whether the movable grid or the movable individual profiles are arranged in front of or behind the fixed elements in the airflow direction L.Either the frame of the first and / or second grille is mounted in a translational guide, or the profiles of the first and / or second grille are mounted within their respective frames. If one of the frames is moved and brought closer to the other, this can also be done asymmetrically, for example, if the airflow on one side of the system needs to be adjusted differently than on the other. In such cases, it can be advantageous, for instance, to provide at least two adjustment mechanisms that allow the second frame to be adjusted to different distances on two opposite outer sides.

[0015] By arranging the profiles of the first grid perpendicular to the airflow direction in a projection plane relative to the profiles of the second grid, the advantage arises that adjusting the distance between them changes the cross-sectional area of ​​the flow openings. This, in turn, allows for very easy modification of volume flows and flow velocities. It has been shown that this method significantly improves the homogenization of the scattered cross-sectional profile, for example, with regard to the thickness or density of the scattered mat.

[0016] The offset of the profiles makes it possible, in a preferred configuration, to position one profile of the second grille precisely between two profiles of the first grille. In extreme cases, this completely closes the airflow opening, defining a distance of 0 mm. This can be advantageous, for example, when the mat width changes and no airflow is desired at the edge. Since the profiles have a cross-sectional diameter or diagonal of approximately 10 to 40 mm, it is perfectly sufficient if the adjustable distance between the profiles of the first grille and the profiles of the second grille is between 0 and 50 mm, or even less if necessary.

[0017] There are various options for selecting the profile cross-section, with the shape influencing the flow behavior. The air passage area at the airflow inlet (L) between two profiles of the first grid is also typically tapered conically, convexly, or hyperbolically.

[0018] Profile cross-sections with a round, rectangular, triangular, teardrop, or diamond shape have proven to be preferred. Regarding the method for spreading material onto a spreading material conveyor with a described wind spreading device, the objective is achieved by the features of claim 20, and in particular by the fact that a plurality of the profiles of the second grid, which are arranged parallel to the profiles of the first grid and offset in the direction of airflow (L), are moved relative to or away from each other relative to the profiles of the first grid by means of at least one adjustment device in order to control the airflow entering the wind spreading chamber with respect to its flow behavior for the purpose of wind classification.

[0019] As already described, it is advantageous if the movement of at least one of the profiles of the first or second grille is carried out in such a way that at least one flow opening is reduced in cross-section. Or even better, if the movement of at least one of the profiles of the first or second grille is carried out in such a way that it dips into the area between two profiles of the first or second grille in the direction of airflow.

[0020] The invention will now be explained in more detail with reference to the drawings, which merely represent an exemplary embodiment. They show

[0021] • Fig. 1 : a spreading material system according to the invention in a simplified side view,

[0022] • Fig. 2: a top view of a grid arrangement with individually adjustable profiles,

[0023] • Fig. 3 to Fig. 5: schematically represented different grid profiles at at least two different distances (a and b in each case) and

[0024] • Fig. 6: a schematically represented possible guide for adjusting grids according to Fig. 3

[0025] Figure 1 shows a spreading material system for producing spreading material mats for the manufacture of wood-based panels, e.g., particleboard or fiberboard. This spreading material system has a spreading material hopper 3, which is designed as a metering hopper and dispenses the spreading material, e.g., via spreading rollers or metering rollers 5, to a spreading device 1. The spreading device 1 spreads the spreading material onto the spreading belt conveyor 4, where a spreading material mat forms. This mat is then pressed in a press under pressure and heat to form a wood-based panel, e.g., particleboard or fiberboard. Such a spreading material system typically has several spreading devices for producing multi-layered spreading material mats or spreading material mats with multiple layers, where, for example, top layers and one or more middle layers are spread. Figure 1 shows, by way of example, only one section with a spreading device 1 for producing a single layer, e.g.,The device is depicted as having a top layer of relatively fine shavings. This spreading device 1 is designed as an air-driven spreading device. It has an air-driven spreading chamber 2, which has an upper spreading material opening 6 through which the spreading material, e.g., from the spreading material hopper 3, enters the air-driven spreading chamber 2, in this exemplary embodiment from top to bottom. Furthermore, the spreading device 1 has several fans 7 for generating an airflow L for separating the spreading material in the air-driven spreading chamber 5. The fans 7 are arranged in a fan array, which comprises several fans 7 distributed over the height and width, generating individual streams oriented parallel to each other, in this exemplary embodiment in a horizontal direction. The invention also includes embodiments of a spreading device that has only one fan, which would, however, occupy a larger installation space.The air scattering chamber 2 has at least one inlet opening 12, which forms a vertical or substantially vertical inlet surface F through which the airflow L generated by the fans 7 enters the air scattering chamber 2. The inlet surface F therefore extends in the vertical direction, i.e., along the height of the air scattering chamber. The airflow L, which in the exemplary embodiment enters the air scattering chamber 2 in a substantially horizontal direction through the inlet opening 12 and consequently through the inlet surface F, separates the particles, e.g., chips, whereby coarser particles fall into the area of ​​the air scattering chamber facing the inlet opening 12, and finer chips reach the rear area of ​​the air scattering chamber 2, facing away from the inlet surface 12, and fall there. Additionally, sieves 25, e.g.,Optionally, chip screens can be arranged transversely to the flow direction to ensure, for example, optimal chip distribution and precise granulometric separation. A roller screen 10 with a discharge screw 11 can be provided below the trajectory for coarse material discharge. Alternatively, a vibrating screen can be provided instead of the roller screen. For example, glue lumps can be retained by the roller screen 10 or a corresponding vibrating screen and then removed by a discharge screw 11. Additionally, a dust extraction system 24 can be arranged in the rear area of ​​the air scattering chamber 2, away from the inlet area 12, to extract, for example, silicate particles that could cause damage in the subsequent process.

[0026] According to the invention, at least two grilles 8, 9 in frames 13, 14 are provided between the fan(s) 7 and the inlet surface F, which may optionally be provided with inlet openings 12. These grilles are adjustable relative to and away from each other via an adjustment device 21. The profiles 15, which will be explained in more detail later,

[0027] The 16 grilles 8 and 9 are arranged offset from each other, so that the flow openings 19 and 20 formed by the profiles 15, 15.1, 15.2 and 16, 16.1, 16.2 can be enlarged or reduced by the grilles 8 and / or 9, which are adjustable in the direction of airflow L. In the illustrated embodiment, grille 8 is fixed to the wind dispersal device 1, while grille 9 is movable in the direction of airflow L by means of at least one adjustment mechanism.

[0028] The invention comprises two possible embodiments. In the first, as shown in Fig. 1, one frame with all its profiles is designed to be movable relative to the other frame. A second embodiment, in which individual profiles are adjustable in the direction of airflow L by means of an adjustment device 21, is also included.

[0029] By adjusting the flow openings 19 between the profiles, it is possible to variably control the flow conditions via the inlet area F. The control can preferably be based on measured values, which, for example, represent the distribution of the spreading material on the spreading material conveyor 4. For this purpose, a measuring device can be installed in the area of ​​the spreading belt conveyor.

[0030] A device 17 is provided with which the distribution of the spreading material on the spreading material conveyor 4 can be analyzed, e.g., a thickness measuring device with which the thickness of the spreading material layer can be analyzed across its width. Depending on these measured values, the distribution of the individual flows E can be manipulated with the aid of a control or regulating device 18 by selectively controlling the fans 7, e.g., via the speed of the drives for the fans. For this purpose, a control or regulating device 18 can be connected to both the measuring device 17 and the fans 7 or their drives.

[0031] By enabling the control of the adjustment device(s) 21 (as well as individual fans 7) based on the measured scattering distribution on the forming belt 4 by feeding back the signal during the running machine, there is the chance to improve the scattering accuracy and consequently optimize the quality of the spreading mat.

[0032] The entire described grid arrangement 8, 9 can be retrofitted as a unit. An embodiment is shown in Fig. 2. In the top view, the numerous vertically oriented profiles can be seen, of which only four are designated by reference numerals 15.1, 15.2, 16.1, and 16.2. The 15 series defines a first grid 8, and the 16 series a second grid 9. As an adjustment mechanism, elongated holes are milled into the frame 14 for each profile of the second grid 9. In the illustrated delivery state, the grid profiles are set at equal distances A along their entire length. However, profiles 16.1 and 16.2, for example, can each be moved closer to or further away from the first grid 8 using the adjustment mechanisms 21.This extends to the point where the maximum distance is, for example, 50 mm, while in the next position, profile 16, due to its offset from the profiles of the 15 series, makes contact with two profiles of the 15 series and, due to this distance of 0 mm, closes a flow opening 19. In this case, the first profiles 15, 15.1, 15.2 and the second profiles 16, 16.1, 16.2 overlap in the airflow direction L. This allows the cross-sections of the individual flow openings to be easily adjusted. Depending on the scope of functions, each profile can be manually fixed by screws, or individual actuators can be used on each profile, and the setting can be controlled digitally via a central, image-displaying computer interface. Figures 3 to 6 show schematic representations of various cross-sections of profiles 15, 16 and their position relative to the frames 13 and 14 in a top view (for vertical profiles).Since profiles 15 and 16 could also be horizontally arranged profiles within grids 8 and 9, as also covered by the invention, the figures can also be presented as side views. The depiction of the multitude of profiles forming a grid 8 or 9 is omitted; instead, only two profiles per grid are indicated. Profiles 15.1 and 15.2 are thus components of grid 8, and profiles 16.1 and 16.2 are components of grid 9. Furthermore, in these embodiments, the depiction of individual adjustability of the profiles has been omitted, and only the displacement of the frames 8 and 9 is indicated. A large distance is shown when the figure number has a lowercase "a," and a small distance "A" is shown when the figure designation has a lowercase "b."It should be noted that frames 13, 14 can also be positioned at an angle to each other or even bent to compensate for profile variations in the grit mat.

[0033] The various exemplary profile cross-sections are selected such that an air passage area 22 is created at the inlet of the airflow L between two profiles 15.1, 15.2 of the first grid 8, which tapers conically, convexly, or hyperbolically. In some cases, the profile cross-section of a profile 16.1 "entering" between them is shaped so that its outer contour is adapted to the air passage area 22 between the two profiles 15.1, 15.2 of the first grid 8.

[0034] Suitable cross-sections of profiles include, in particular, round (Fig. 3 and 6), rectangular, triangular (Fig. 4) and teardrop-shaped (Fig. 5).

[0035] Figures 6a and 6b have been supplemented by Figure 6c to show, by means of a side view of the profiles, that a guide 23 of the frames 13 or 14 indicated in Figures 6a and 6b does not necessarily have to engage at the ends of the profiles, but can also, for example, engage in their middle. Reference numeral table

Claims

Patent claims 1. Wind spreading device (1) for spreading material onto a spreading material conveyor (4), comprising at least one wind spreading chamber (2) which has an upper spreading material opening (6) through which the spreading material is introduced into the wind spreading chamber and at least one fan (7) for generating at least one airflow (L) for separating the spreading material in the wind spreading chamber (2), wherein the airflow (L) generated by the at least one fan (7) enters the wind spreading chamber (2) via an inlet area (F) which extends along the height and, if applicable, the width of the wind spreading chamber (2), wherein a first grid (8) with profiles (15, 15.1, 15.2) connected in a first frame (13) and arranged side by side is provided between the at least one fan (7) and the inlet area (F), wherein there is a space between the profiles (15, 15.1, 15.2).2) first flow openings (19) are located, characterized in that a second grille (9) is provided adjacent to it, with profiles (16, 16.1, 16.2) connected in the first frame (13) or a second frame (14) and arranged side by side, wherein second flow openings (20) are located between the profiles (16, 16.1, 16.2) and a plurality of the profiles (15, 15.1, 15.2) of the first grille (8) are arranged parallel to the profiles (16, 16.1, 16.2) of the second grille (9) and offset in a projection plane perpendicular to the direction of airflow (L) and a plurality of the profiles (15, 15.1, 15.2) of the first grille (8) are adjusted relative to the profiles (16, 16.1, 16.2) of the second grille (9) by means of at least one adjustment device (21). 16.2) of the second grid are movable towards each other or away from each other.

2. Wind scattering device (1) according to claim 1 , characterized in that the profiles of the first grid (8) and the second grid (9) run substantially vertically.

3. Wind spreading device (1 ) according to claim 1 or 2, characterized in that the first grid (8) is fixed to the wind spreading device (1 ), while the second grid (9) via which at least one adjustment device (21) can be moved towards or away from the first grid (8).

4. Wind spreading device (1) according to one of claims 1 to 3, characterized in that the adjusting device (21 ) allows at least one profile (15, 16) to be moved within the frame (13, 14).

5. Wind spreading device (1 ) according to claim 4, characterized in that a plurality of profiles (15, 16) have a separate adjustment device (21 ) relative to the frame (13, 14).

6. Wind scattering device (1) according to one of claims 1 to 5, characterized in that by means of the adjusting device (21) at least the distance (A) between the first grid (8) and the second grid (9) can be adjusted such that the cross-section of the flow openings (19, 20) is changed.

7. Wind spreading device (1) according to claim 6, characterized in that the distance (A) is adjustable between 0 and 50 mm.

8. Wind scattering device (1 ) according to claim 7, characterized in that the first profiles (15, 15.1 , 15.2) and the second profiles (16, 16.1 , 16.2) overlap at least at a distance of 0 mm in the direction of airflow (L).

9. Wind scattering device (1 ) according to one of claims 1 to 8, characterized in that an air passage area (22) at the inlet of the airflow (L) between two profiles (15, 15.1 , 15.2) of the first grid (8) tapers conically, convexly or hyperbolically.

10. Wind scattering device (1) according to claim 9, characterized in that a profile (16, 16.1 , 16.2) in the direction of movement of the second grid (9) is adapted with the outer contour to the air passage area (22) at the inlet of the airflow (L) between two profiles (15, 15.1 , 15.2) of the first grid (8).

11. Wind scattering device (1) according to one of claims 1 to 10, characterized in that the frame (13, 14) of the first and / or second grid (8, 9) is mounted in a translational guide (23).

12. Wind scattering device (1) according to one of claims 1 to 10, characterized in that the profiles (15, 16) of the first and / or second grid (8, 9) are mounted in a translational guide (23).

13. Wind scattering device (1) according to one of claims 1 to 10, characterized in that the profiles of the first and / or second grid have a rectangular cross-section.

14. Wind scattering device (1 ) according to one of claims 1 to 10, characterized in that the profiles of the first and / or second grid have a round cross-section.

15. Wind scattering device (1) according to one of claims 1 to 10, characterized in that the profiles of the first and / or second grid have a teardrop-shaped cross-section.

16. Wind scattering device (1) according to one of claims 1 to 10, characterized in that the profiles of the first and / or second grid have a triangular cross-section.

17. Wind scattering device (1) according to one of claims 1 to 10, characterized in that the profiles of the first and / or second grid have a rhomboid cross-section.

18. Wind spreading device (1) according to one of claims 1 to 17, characterized in that the first and / or second frame (13, 14) is bent.

19. Wind spreading device (1) according to one of claims 1 to 18, characterized in that the second The frame (14) is adjustable to different distances on two opposite outer sides.

20. Method for spreading spreading material onto a spreading material conveyor with a wind spreading device according to any one of claims 1 to 19, comprising at least one wind spreading chamber (2) having an upper spreading material opening (6), the spreading material is introduced into the wind spreading chamber via the spreading material, and at least one fan (7) for generating at least one airflow (L) for separating the spreading material in the wind spreading chamber (2), wherein the airflow (L) generated by the at least one fan (7) enters the wind spreading chamber (2) via an inlet area (F) extending along the height and, if applicable, the width of the wind spreading chamber (2), wherein a first grid (8) with profiles (15, 15.1, 15.2) connected in a first frame (13) and arranged side by side is provided between the at least one fan (7) and the inlet area (F), wherein there is a space between the profiles (15, 15.1, 15.2).2) first flow openings (19) are located, and adjacent to it a second grid (9) with profiles (16, 16.1, 16.2) connected in the first frame (13) or a second frame (14) and arranged side by side, wherein second flow openings (20) are located between the profiles (16, 16.1, 16.2), characterized in that a plurality of the profiles (16, 16.1, 16.2) of the second grid (9), which are arranged parallel to the profiles (15, 15.1, 15.2) of the first grid (8) and offset in the direction of airflow (L), are moved towards or away from each other relative to the profiles (15, 15.1, 15.2) of the first grid (8) by means of at least one adjustment device (21) in order to direct the airflow entering the wind scattering chamber for the purpose of wind classification. to control the flow behavior.

21. Method for spreading material onto a spreading material conveyor according to claim 20, characterized in that the movement of at least one of the profiles (15, 16) of the first and / or second grid (8, 9) is carried out in such a way that at least one flow opening (19, 20) is reduced in cross-section.

22. Method for spreading material onto a spreading material conveyor according to claim 20 or 21, characterized in that the movement of at least one of the profiles (15, 16) of the first or second grid (8, 9) is carried out in such a way that it dips into the area between two profiles (15, 15.1 , 15.2, 16, 16.1 , 16.2) of the first or second grid (8, 9) in airflow directions.

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