RU2588188C2 - Device for percussion grinding and producing materials, in particular, wood, in several fractions - Google Patents

Abstract

FIELD: disintegrators and devices for crushing.

SUBSTANCE: device (1) comprises an impact reactor (2) with a cylindrical main body (4). Rotor (8) having at least one impact element (10) that contacts the material rotates in the closed interior (6). Impact element produces a high momentum transfer to crush the material into partial components. Ejector box (14) is connected to the interior of the main body by means of an ejection opening (16). First conveying screw (24a) is arranged inside the ejection box under the ejection opening for conveying the crushed material. First screen (20a) having a first mesh width is arranged under the ejection opening. First screen extends from the ejection opening to the first conveying screw at an angle with respect to the horizontal. Under the first screen there is a sliding surface (22) arranged at an angle with respect to the horizontal or a second screen (20b) arranged at an angle with respect to the horizontal and having a smaller mesh width. Second screen extends from the cylindrical main body to a second conveying screw (24b) arranged under the first conveyor (24a).

EFFECT: present invention relates to a device for crushing materials in several fractions.

19 cl, 3 dwg

Description

The invention relates to a device for impact grinding and obtaining materials, in particular wood, in several fractions according to the restrictive part of paragraph 1 of the claims.

The prior art is the processing of building elements consisting of various materials, such as: metal parts, glass, rubber, wood, polymers, fibrous materials, composite materials, aluminum profiles with a powder or plastic coating or the like, using turbo mixers, in which building elements are crushed as a result of the impact of impact elements mounted on a rotor rotating at a high speed on a cylindrical base.

In this regard, from European patent EP 0859695 B1 there is known a method and apparatus for processing building elements from a mixture of materials, in particular from mixed plastics, when a turbo mixer mounted on a cylindrical base comprises a rotor rotating in a cylindrical base using a drive motor. The rotor, height-adjustable at the base, consists of wear-resistant steel and contains shock elements installed at its ends with the possibility of removal, crushing the loaded building elements by impact impact arising from a collision into fragments of various sizes, which can subsequently be separated from each other. This publication does not give any guidance regarding the receipt of several fractions with different particle sizes using connected grids for crushed particles mounted on top of each other directly behind the remote opening of the turbo mixer.

Accordingly, it is an object of the present invention to provide a compact device with which a wide variety of materials can be ground and pulled out in various fractions as a result of impact.

This task according to the invention is solved using a device with the characteristics of paragraph 1 of the claims.

Other features of the invention are described in the dependent claims.

According to the invention, a device for grinding a material, in particular wood, comprises a turbo mixer having a substantially cylindrical base, in the closed interior of which an engine-driven rotor rotates with at least one impact element, which is in contact with the material and generates a powerful impulse. its component parts. In addition, the device comprises an external tray connected through an external opening to the inner space of the cylindrical base, as well as a first screw conveyor installed in the external tray under the external opening for dispensing crushed material from the external tray.

The device according to the invention is characterized in that a first mesh with a first hole size is installed under the outlet, extending, when viewed from the side of the outlet, in the direction of the first screw conveyor with an inclination relative to the horizontal and a sliding surface inclined relative to the horizontal or inclined relative to the horizontal a second mesh having a second reduced hole size compared to the first hole size. The sliding surface or the second mesh extends from the cylindrical base to the second screw conveyor mounted under the first screw conveyor.

The invention provides the advantage that the bypass tray of the device according to the invention can be relatively compact in size because the main surface required by the meshes, determined by the vertical projection of the meshes, is advantageously reduced due to their inclined installation relative to their effective screening surface.

An additional advantage follows from the inclination of the first mesh, namely that the particles remaining on it, which do not pass down through the screening holes, slide down in the direction of the screw conveyor under the influence of their own weight and thereby free the surface of the mesh in the area of the remote opening for the next mixture particles protruding from the remote hole. Due to this, a blockage of the mesh surface is favorably rendered. The aforementioned advantage also extends to a second screen mounted under the first screen, preferably with the same angle as the first screen, in a plane extending substantially parallel to the screening surface of the first screen.

In addition, in particular, from equipping the bypass tray with a second grid, the advantage follows that, if desired, careful fractionation of the crushed material leaving the turbo mixer can be directly carried out without requiring, as in the prior art, screening devices that are remote from the impact grinding mill actions on which the material would have to be fed with great difficulty, for example, using conveyor belts.

Alternatively, instead of the second grid, a sliding surface may be provided to prevent particles passing through the first grid from falling down from the bypass tray, which are hereinafter also referred to as screening. Since the sliding surface, which in this case dust-tightly covers the collector, preferably from below, directs all particles passing through the first mesh to the second screw conveyor, in this embodiment pushes all the screening into the screw conveyor, resulting in the occurrence of dust compared to using an open a collector mounted immediately below the first screening surface is significantly reduced.

In a preferred embodiment of the device according to the invention, the remote opening is closed by a third mesh having an enlarged hole size compared to the opening size of the first mesh.

The advantage of using a third mesh with an enlarged hole size in comparison with the first mesh that covers the remote opening results in the fact that during a continuous process through the third mesh, only particles of material that are crushed by the size of the openings of the third mesh to a predetermined maximum value fall into the external tray as described above. At the same time, the rest of the still insufficiently crushed material remains in the crushing space of the turbo mixer and continues to grind there during this time until it also reaches a diameter smaller than the holes of the third grid.

Alternatively or simultaneously with the use of the third mesh, it can also be provided that the remote opening is closed with a shutter or a latch, which advantageously creates the possibility of discrete transfer of the crushed material from the crushing space to the external tray. This alternative embodiment has the advantage that the feed amount of ground material in the bypass tray can be controlled so that, if desired, the amount of ground material on the first and / or second grid can be adjusted. Thanks to this, it is possible to effectively prevent overfilling of the nets or their filling over the edge and clogging of screw conveyors. In addition, from this effective embodiment, there is an additional advantage that the grinding of the crushed material from the crushing space can be carried out on the basis of control using other parameters, for example, based on the moisture content in the crushed particles or in the crushing space, which is associated with this mesh clogging should not be too much.

In addition, it turned out to be particularly preferable that a combination of a third mesh and a shutter or shutter is used to provide discrete removal of material from the crushing space into the bypass tray.

In addition, in one preferred embodiment of the device according to the invention, it can be provided that under the second grid there is a sliding surface inclined relative to the horizontal, or one or more additional grids inclined relative to the horizontal, which have a smaller hole size compared to the size holes of the second grid. The mesh or additional mesh extend respectively from a cylindrical base with the same angle of inclination as that of the first and second mesh to the corresponding additional screw conveyor, preferably mounted directly below the second screw conveyor. The screw conveyors preferably extend in the same vertical plane, in particular extending parallel to the axis of rotation of the rotor outside the crushing space.

This gives the advantage that in one single compact device, thorough fractionation of the crushed material can be carried out without additional connected separating devices, as is desirable, for example, when grinding the starting material for further direct processing of individual fractions of the crushed material. Thus, when grinding wood for the manufacture of chipboards, fed into the crushing space in the form of pre-coarsely chopped pieces of wood with a diameter of, for example, 20-50 cm, three size fractions with a size are produced during sieving in the same compact device during sieving particles in the range, for example, 20-15 mm, 15-5 mm and 5-0 mm, for one production operation. In the process of manufacturing chipboards, these three fractions can be directly supplied as starting material for different layers of chipboard, which significantly reduces the cost of the device and thereby production costs.

As already mentioned, in connection with the first mesh, a sliding surface extending from the cylindrical base to the corresponding additional screw conveyor is located under the second or lowest additional mesh with a slope relative to the horizontal. As a result of this, closing of the bypass tray from below is advantageously achieved. This embodiment has, in particular, the additional advantage that all sifting past the above meshes is passed along an inclined sliding surface into the auger groove in which the lowest auger conveyor rotates, so that dust formation continues to be further reduced.

According to one of the further embodiments of the invention, the first and / or second screw conveyors are mounted rotatably in the openings of the auger tubular groove open on the upper side, in which sieving holes are made having a hole size corresponding to the hole size of the corresponding adjacent mesh. The use of a screw chute equipped with sieving holes has the advantage that particles with a smaller diameter compared to the size of the mesh holes mistakenly falling into the screw chute attached to the mesh, as a result of overfilling of the corresponding mesh, nevertheless fall through the sieving holes in the screw chute to the downstream sect or in the auger groove located below it, and thus are carried out in the desired fraction in accordance with their size. This is facilitated by the rotational movement of the auger feed in the auger trough and the resulting mixing and rolling of particles in the auger trough.

Due to the movement of the feed and mixing of the material in the augers of the screws, at least partially provided with holes on their lower side, there is an additional advantage that the particles are only slightly adhering to each other or connected to each other in only one relatively narrow connection point, in as a result of the feed movement and the mechanical friction accompanying it, they are separated from each other, and then, in accordance with their size, they pass through the sieving holes to the downstream nets or screw trans Orter.

According to a further embodiment of the device according to the invention, it may be preferable that the third mesh has a hole size within 20 mm, the first mesh has a hole size within 15 mm, and the second mesh has a hole size within 5 mm. The result is a favorable way to achieve uniform fractionation with the appropriate size ranges, which are required, for example, in the woodworking industry for the manufacture of chipboard materials, such as, for example, boards from high-quality pressed cardboard. At the same time, particles of wood of different sizes must be present in order to, on the one hand, give the chipboard a smoother surface and, on the other hand, a high load capacity. To do this, in the middle layer, perceiving the load, larger and flatter particles are used, providing a more uniform planar distribution of forces acting on the plate. At the same time, to obtain a smooth surface layer from the upper and lower sides of particle boards, fine particles are used to the extent possible.

Alternatively, a different ordering of the sizes of the openings of the grids can also be carried out, so that, for example, as a result of the approximation of the sizes of the openings of the first and second grids with the resulting reduction in the statistical fraction of unnecessarily large or too small particles, the purity of the grades of material particles favorably increases . In addition, as a result of the reduction and, therefore, convergence of the size of the holes of the third mesh with the size of the holes of the first mesh, the number of particles in excess of the desired range also decreases, since, on the one hand, the particles stay in the crushing space for longer grinding, and, on the other hand, due to a larger narrowing of the range between the hole sizes of the first and third grids, the proportion of too large particles in the mixture of particles passing through the third grid decreases.

According to another idea underlying the invention, horizontally arranged barrier strips can be installed on the first mesh to reduce the speed of the crushed material emerging from the remote opening as it moves along the inclined mesh. The advantage resulting from this is that the remaining fraction of smaller particles in the particle mixture carried by the first screw conveyor is minimized, since the length of stay on the first grid is increased by the barrier bars. This generally ensures a qualitatively more accurate separation of particles by the first grid, since the risk of overflowing the grid as a result of an increase in the length of stay is reduced.

In a preferred embodiment, the first and / or second meshes have a corresponding mesh bottom, or a corresponding effective screening surface, inclined relative to the horizontal by an angle in the range between 20 ° and 70 °, in particular in the range of 30 ° -40 °, which is favorable may vary within these limits.

This opens up the possibility that the high velocity of the ejection of particles falling through the outflow hole to the first grid, which might be required, for example, to separate the mixture of materials due to the corresponding peripheral rotor speed, could be compensated by the appropriate choice of the slope of the mesh bottom of the first grid. Under certain conditions, for this it may even be necessary for the first grid to be installed at a negative angle relative to other grids, so that particles exiting through the remote outlet fall directly onto the first grid installed with an inclination at an angle of, for example, 45 °, and then slide off in the direction of the outside of the turbo mixer on the first mesh bottom. The first screw conveyor in this case is installed under the remote opening in the area near the outer wall of the turbo mixer, and the second grid with the same or opposite direction of inclination is described above under the first grid.

In addition, it may be provided that the first and / or second mesh and / or, if necessary, the next mesh contain one or more motors with an unbalanced rotor so that the corresponding mesh can be swung. In this case, the first and second grids, preferably with the help of elastic damping suspensions or buffers, are fixed on the circumferential surfaces and swing, for example, by means of an eccentrically installed flywheel connected to the corresponding grid and driven by the motor to rotate.

The consequence of the swaying of the first and second mesh is favorable that the mixture of particles is fluidized on the corresponding mesh, as a result of which, with the appropriate choice of frequency and type of vibrations, larger particles migrate upward on the mesh and smaller ones migrate downward, which additionally supports the screening process and improves the quality fractions obtained.

The invention is described below with reference to the drawings based on a preferred embodiment.

In the drawings depict:

figure 1 is a schematic side view of a device according to the invention,

figure 2 - device without wall sections of the remote duct in perspective and

figure 3 is a schematic top view of the device according to the invention.

As shown in figure 1, the device 1 for grinding various materials, such as: wood, metals, plastics, as well as mixtures and combined materials from these substances, according to the invention contains a turbo mixer 2, comprising a substantially cylindrical base 4, in a closed interior space 6 of which rotor 8 rotates at high speed, on which several preferably interchangeable impact elements 10 of high strength material are mounted. The rotor 8 is driven by an engine 12, preferably an electric motor, but an internal combustion engine or a vehicle engine, such as a tractor, driving the rotor 8 into rotation through a power take-off shaft, and using an angle gear not shown in more detail, are possible.

In addition, the device 1 according to the invention comprises an outwardly extending by-pass tray 14 mounted on the outer wall of the cylindrical base 4 and hydraulically connected to the inner space 6 of the cylindrical base 4 through the out-hole 16. The out-hole 16 comprises, according to a preferred embodiment of the invention, a third passage net 20c the hole size is preferably 20 mm. The net 20c may be covered by a shutter 18a, which can be folded, for example, along a double arrow drawn, or by a shutter 18b so that the remote opening 16 is partially or completely closed and the passage of crushed material is prevented. The third mesh 20c, used in the remote opening 16, fractionates particles flying around in the inner space 6 of the turbo mixer 2, for which it introduces into the external tray 14 such particles smaller than the openings of the third mesh 2, preferably 20 mm, and larger particles and pieces of still insufficiently crushed material in the inner space 6 of the turbo mixer 2 are delayed in order to subject them there to a further grinding process. At the same time, the shutter 18a shown in Fig. 1 controls the influx of crushed particles into the bypass tray 14, for which the shutter 18a or the two-part shutter 18b shown in Fig. 3 are fixed, for example, in a partially open position, and so Thus, the relative passage surface of the remote opening 16 can smoothly decrease. However, alternatively, the bypass tray 14 can also be loaded in batches of shredded material by cyclically opening and closing the shutter 18a or shutter 18b.

In a preferred embodiment of the device 1 according to the invention, inside the bypass tray 14 is a first plane with a first horizontal inclined mesh 20a with a first hole size that extends from the lower end of the bypass hole 16 to the first screw channel 26a located under the bypass hole 16 in which the first screw conveyor 24a for dispensing crushed material from the bypass tray 14. Moreover, the holes of the first mesh 20a are preferably smaller than the holes of the third ki 20c, whereby in this first plane there is a further fractionation of the milled material in accordance with the size of the holes is preferably 15 mm. Particles smaller than 15 mm in size fall through the openings of the first mesh 20a, with particles between 15 and 20 mm remaining on top of the first mesh 20a and, due to the inclination of the first mesh 20a, are directed downward into the screw groove 26a. There they are, with the help of the first screw conveyor 24a, through the hole not shown on the side, removed from the bypass tray 14 to the outside for further processing or storage. In addition, as shown in detail in FIG. 1, the first screw trough 26a has sieving holes 28, the size of which substantially corresponds to the size of the holes of the first mesh 20a. This allows particles that mistakenly enter the first screw groove 26a as a result of the overflow of the first mesh 20a to pass through the sieving holes 28 and still filter out larger particles in accordance with the size of the holes of the first mesh 20a.

In addition, FIG. 1 shows that under the first screening plane including the first screen 20a and the first screw groove 26a, there is a second screening plane, the structure of which is substantially similar to the first screening plane, which includes a second screen 20b inclined relative to the horizontal, and a second screw chute 26b comprising a second screw conveyor 24b. In this case, the second mesh 20b for separating particles in the range of 5-15 mm passing through the first mesh 20a from those components whose size is less than 5 mm has a second hole size of preferably 5 mm, reduced compared to the size of the holes of the first nets 20a in 15 mm. Particles with a diameter in the range of 5-15 mm remaining over the second mesh 20b are guided due to the inclination of the second mesh 20b into the second screw groove 26b and therefrom are removed from the output tray 14 by the second screw conveyor 24b. On the bottom side of the second screw groove 26b, which, by analogy with the first screw groove 26a, can consist of a pipe having, inside the bypass tray 14, in the region adjacent to the screening plane, only one upward facing opening, preferably screening openings with hole sizes are also made substantially corresponding to the size of the holes of the second mesh 20b.

In accordance with another idea underlying the invention, the first and second grids 20a, 20b, as shown in FIG. 1, comprise, on their lower side, an unbalanced rotor motor 32, preferably in mechanical connection with the side walls of the bypass tray 14, not images shown for technical reasons, due to which the meshes sway. The vibration dampers or buffers 34 shown below, by which the first and second nets 20a, 20b are preferably supported on the side walls of the bypass tray 14, are preferably mounted in the edge region facing the corresponding first and second screw channels 26a, 26b so as to locate mesh with the possibility of oscillation and at the same time reduce the amplitude of the oscillations in the region of the first and second troughs 26a, 26b of the screw. Thus, the vibrations of the grids are disconnected relative to each other and the body of the bypass tray 14, which is closed to the outside, as well as relative to the screw conveyors 24a, 24b, so that the vibration modes and amplitudes for the respective grid can be adjusted to the material being ground. In addition, other structural elements, such as, for example, screw conveyors, do not suffer from fluctuations, so that their service life is favorably increased.

As can be seen in FIG. 1, in a preferred embodiment of the invention, a sliding surface 22, inclined relative to the horizontal, is provided under the second grid 20b, preferably extending also substantially parallel to the first and second grids 20a, 20b from the cylindrical base 4 to the third one installed under the second screw conveyor 24b a screw conveyor 24c installed in the third screw trough 26c closed from the bottom, i.e. in the trough of the screw, which, in contrast to the troughs 26a and 26b, has no mesh openings 28. On the closed sliding surface 22 in combination with the third screw chute 26c closed on the lower side, the smallest component parts of the material passing through the first and second grids 20a, 20b are transported from the bypass tray 14 to a collection not shown in more detail.

The second grid 24b preferably has the same angle of inclination relative to the horizontal as the first grid 24a, which is preferably varied, for example, in the range of 30 ° -50 °.

Figure 2 schematically in perspective shows a side view of a turbo mixer with an external tray 14, where for a better image of the sifting planes the side walls are not shown, and different sizes of the holes should be indicated with different images of the first, second and third grids 20a, 20b, 20c. Similarly, in this image it is seen that the barrier strips 30 extend over the entire width of the first mesh 20a.

In addition, figure 3 schematically shows a top view of the device 1 according to the invention. This detailed image shows that the remote opening 16 can be closed by a valve 18b, consisting of two parts and shown in a partially open position, for which the parts of the valve are moved in the direction of both double arrows. However, it is also possible for the gate valve 18b to be made of one single gate plate, which, for opening the remote opening 16, can be slid or pivoted by a vertical shift directed, for example, upward. However, the valve 18b may have an arcuate shape adapted to round off the outer surface of the impact breaking reactor 2 and moved to release the remote opening 16 in the circumferential or vertical direction.

The intermediate region 21, formed due to the curvature of the outer wall of the turbo mixer 2 and preferably the rectilinear connecting edge of the first mesh 20a, is preferably made in the form of a closed and inclined sliding surface along which the ground material can slide out of the remote outlet 16 at a low speed along the first mesh which does not first hit the screening surface of the first mesh 20a.

In addition, Fig. 3 shows, by way of example, an axial extension of the first screw conveyor 24a, a conveyor pipe 38 is mounted that is installed on the outside of the output tray 14 for further feeding material transported by the first screw conveyor 24a, for example, to a collector not shown in more detail. For this, the screw conveyor 24a, like the rest of the aforementioned screw conveyors, is driven by the screw motor 36, shown as an example in this image.

List of items

1 device

2 turbo mixer

4 base

6 interior / crushing space

8 pipe

10 percussion element

12 engine

14 bypass tray

16 remote hole

18a damper

18b gate valve

20a first grid

20b second grid

20s third grid

intermediate area

sliding surface

24a first screw conveyor

24b second screw conveyor

24c third auger conveyor

26a first auger trough

26b second auger trough

26c third auger trough

sifting holes

barrier strips

unbalanced rotor motor

vibration damper

36 auger motor

38 transport pipe

Claims (19)

1. A device (1) for grinding a material, in particular wood, containing a turbo mixer (2) having a substantially cylindrical base (4), in a closed interior space (6) of which a rotor (8) rotates with at least one element (10 ) shock, which is in contact with the material and creating a powerful impulse, crushes it into its component parts, as well as with the bypass tray (14) connected through the bypass hole (16) with the inner space (6) of the cylindrical base (4), as well as with the installed in the bypass tray (14) under you an axial hole (16) by the first screw conveyor (24a) for dispensing crushed material from the bypass tray (14), characterized in that under the bypass hole (16) a first mesh (20a) is installed with a first hole size extending from the bypass hole (16) to the first auger conveyor (24a) with a horizontal inclination, and under the first mesh (20a) there is a sliding surface (22) inclined relative to the horizontal or a second mesh inclined relative to the horizontal (20b) with the second hole size reduced in comparison with the first hole size extending from the cylindrical base (4) to the second screw conveyor (24b) mounted under the first screw conveyor (24a). 2. The device according to claim 1, characterized in that the remote hole (16) is closed by a third mesh (20c) with a hole size larger than the size of the holes of the first mesh (20a), and / or a shutter (18a), and / or gate valve (18b). 3. The device according to claim 1 or 2, characterized in that under the second grid (20b) there is a sliding surface (22) inclined relative to the horizontal, or one or more additional grids inclined relative to the horizontal, with a hole size smaller than the second size of the holes that extend, respectively, from the cylindrical base (4) to the corresponding additional screw conveyors installed under the second screw conveyor (24b). 4. The device according to claim 1 or 2, characterized in that the first and / or second screw conveyors (24a, 24b) rotate in the open on the upper side of the tubular groove (26a, 26b) of the screw in which the sifting holes (28) are made, having a value corresponding to the size of the holes of the adjacent mesh (20a, 20b). 5. The device according to claim 3, characterized in that the first and / or second screw conveyors (24a, 24b) rotate in the open on the upper side of the tubular groove (26a, 26b) of the screw, in which sifting holes (28) are made, having a value corresponding to the size of the holes of the adjacent mesh (20a, 20b). 6. The device according to claim 1 or 2, characterized in that the third mesh has a hole size within 20 mm, the first mesh has a hole size of 15 mm, and the second mesh has a hole size of 5 mm. 7. The device according to claim 3, characterized in that the third mesh has a hole size within 20 mm, the first mesh has a hole size of 15 mm, and the second mesh has a hole size of 5 mm. 8. The device according to claim 4, characterized in that the third mesh has a hole size within 20 mm, the first mesh has a hole size of 15 mm, and the second mesh has a hole size of 5 mm. 9. The device according to claims 1, 2 or 5, characterized in that horizontally arranged barrier strips (30) are installed on the first grid (20a), which reduce the speed of the crushed material emerging from the remote opening (16) when it moves along the inclined grid ( 20a). 10. The device according to claim 3, characterized in that horizontally arranged barrier strips (30) are installed on the first grid (20a), which reduce the speed of the crushed material emerging from the extension hole (16) when it moves along the inclined grid (20a). 11. The device according to claim 4, characterized in that horizontally arranged barrier strips (30) are installed on the first grid (20a), which reduce the speed of the crushed material emerging from the remote opening (16) when it moves along the inclined grid (20a). 12. The device according to claims 1, 2 or 5, characterized in that the first and / or second mesh (20b, 20c) have a corresponding mesh bottom installed with an inclination relative to the horizontal by an angle in the range between 20 ° and 70 °, in particular in the range of 30 ° -40 °. 13. The device according to claim 3, characterized in that the first and / or second mesh (20b, 20c) have a corresponding mesh bottom installed with an inclination relative to the horizontal by an angle in the range between 20 ° and 70 °, in particular in the range of 30 ° -40 °. 14. The device according to claim 4, characterized in that the first and / or second mesh (20b, 20c) have a corresponding mesh bottom installed with an inclination relative to the horizontal by an angle in the range between 20 ° and 70 °, in particular in the range of 30 ° -40 °. 15. The device according to claim 6, characterized in that the first and / or second mesh (20b, 20c) have a corresponding mesh bottom installed with an inclination relative to the horizontal by an angle in the range between 20 ° and 70 °, in particular in the range of 30 ° -40 °. 16. The device according to claims 1, 2, 5, 7 or 8, characterized in that the first and / or second grid (20a, 20b) and / or the next grid contain motors (32) with an unbalanced rotor for swinging the corresponding grid. 17. The device according to claim 3, characterized in that the first and / or second grid (20a, 20b) and / or the next grid contain motors (32) with an unbalanced rotor for swinging the corresponding grid. 18. The device according to claim 4, characterized in that the first and / or second grid (20a, 20b) and / or the next grid contain motors (32) with an unbalanced rotor for swinging the corresponding grid. 19. The device according to claim 6, characterized in that the first and / or second grid (20a, 20b) and / or the next grid contain motors (32) with an unbalanced rotor for swinging the corresponding grid.

Images