EP1149671B1 - Device for distributing granular material onto a continously travelling support - Google Patents

Description

The invention relates to a device for scattering grit on a continuously moving pad according to the preamble of claim 1. Such a device is, for example US-A-3,252,186 known.

In the manufacture of wood-based panels, especially wood fiber panels in a system with a continuous steel belt press, there is the problem that it may come to Streugutverdichtungen that can lead to local damage to the steel bands of steel belt presses especially at high densities of 800 to 1100 N / mm ² . Furthermore, in devices in which a stream of glued wood particles or fibers moves, caking and deposits occur, which are then suddenly detached by vibrations or other forces and entrained with the material flow. These deposits usually consist of a fiber-glue mixture which has already been fully cured by the long laytime. These deposits are referred to below as Leimknoten. In addition, there may also be sand inclusions or small stones in the stream, which were not eliminated before spreading. If such foreign bodies enter the steel belt press, this likewise leads to damage to the steel belts of the press.

To avoid such damage to the steel belts by Streugutverdichtungen, glue nodes or other foreign bodies various devices are known. These are usually arranged between the Austragswalzenanordnung the Dosierbunkers and the scattering head assembly.

From the DE-AS 11 74 058 In opposite directions rotating disk rollers or spiked rollers are known, which have rows arranged on the circumference spike, which engage between the spiked rows of the opposite roller.

Furthermore, from the DE 43 02 850 Fiber bale opening rollers are known, which are driven in opposite directions rotating. The rollers are designed as disc shafts with attached toothed disks. These toothed disks have so-called Auflösezähne, which are set counter to the direction of rotation sawtooth-like, wherein the opening teeth of the rollers mesh and form a meandering gap. By the known opening rollers described above, a resolution of Streugutverdichtungen can be achieved.

From the DE 25 35 461 Furthermore, a device for spreading matte grit on a moving surface is known, in which an arrangement of disk rolls is provided. These disk rollers are all driven in the same direction rotating and form scattering chambers for grit of different grain size. In addition to the classification of the components of the grit, foreign bodies such as glue lumps, splinters and so forth are discharged behind the disk roller and collected in a gutter.

Furthermore, from the DE 42 12 017 a cover layer spreading device is known, which has a screening device below a blow register, which comprises a vibration drive. By this screening device also foreign bodies such as glue nodes can be eliminated.

Object of the present invention is therefore to develop a device for spreading of grit in such a way that a high quality wood-based material board can be produced.

This object is solved by the characterizing features specified in claim 1.

By the formation of the first roller, which rotates slowly and has large recesses between the teeth, a good entrainment of the material to be dissolved, is achieved. The second roller, which has approximately twice as many teeth and rotates much faster, now pulls the fibers entrained by the first roller through the dissolving gap during rotation. Due to the large number of teeth and the fast rotation, a good fiber resolution is achieved. Since the rollers are subject to high wear during operation, it is easily possible to replace the worn toothed disks by the toothed disks arranged at a distance from the rollers.

In a development of the invention, it is provided that the rear side of the tooth flanks can be inclined in the direction of rotation. This has the advantage that the material after it has been combed through by the rollers, can easily escape from the pockets.

In a particularly preferred embodiment of the invention it is provided that the toothed discs are radially extending outwardly pointed or slightly rounded and the rollers are arranged such that between the toothed discs of the adjacent rollers, a zigzag gap with the same gap spacing is formed. By this configuration, an adjustment of the gap distance between the toothed disks by changing the distance of the rollers to each other is possible.

In Fig. 1 1 schematically shows a forming station 1 with dosing bunker 2, an opening roller arrangement 3, a dosing belt weigher 4, a spreading head arrangement 5 and a forming belt 6, onto which the material web 7 is sprinkled from glued fibers. In the dosing bunker 2, the material flow, preferably consists of glued fibers, cached and distributed to an intended discharge width. As a stream lignocellulosic particles of different sizes are provided in the first place. The glued fibers are fed via a Austragswalzenanordnung 8 of the dosing bunker 2 on the opening roller assembly 3, which consists of two oppositely rotating rollers 9, 9 '. The rollers 9, 9 'are, as is known from the Fig. 2 can be seen, arranged parallel to the axis in a horizontal plane next to each other. Further details of the execution of the rollers 9, 9 'are based on the FIGS. 2 to 5 described. Below the opening roller assembly 3, an additional conveying device is provided, which supplies the material stream of glued fibers to a spreading head arrangement 5. The additional conveying device is designed as a feeder belt balance 4, which continuously conveys a controllable flow rate in the spreading head assembly 5, so that depending on the plate thickness and width of the scattering head assembly 5 a predetermined amount is strewn to the forming belt 6. The conveying direction of the forming belt 6 is shown here by the arrow 10.

In a further arrangement, not shown, the fiber opening roller arrangement 3 could also be arranged between the conveying device 4 and the spreading head arrangement 5. Furthermore, it would also be possible to use a forming station which does not contain any additional conveying device 4, so that the fiber opening roller arrangement 3 is arranged between the metering hopper 2 and the spreading head arrangement.

In the Figures 2 and 3 an embodiment of the invention an opening roller assembly 3 is shown, which consists of two axially parallel rollers 9, 9 '. The opening roller assembly 3 described below is as already to Fig. 1 described preferably used for the production of fiberboard, wherein from a metering hopper glued fibers as Material flow via a Austragswalzenanordnung be placed on the roller 9. The task of material flow on the roller 9 is shown by the arrows 11. The rollers 9, 9 'are provided with toothed discs 12, 13, wherein the toothed discs 12, 13' are arranged axially spaced on the rollers 9, 9. Between the arranged on the rollers adjacent toothed discs 12, 13 each spacer sleeves 14, 15 are inserted.

The toothed discs 12, which are arranged axially spaced on the roller 9, protrude as it is from the Figures 2 and 3 it can be seen in the interstices of the on the roller 9 'axially spaced toothed discs 13. The toothed disc 12 and the toothed disc 13 are provided at its periphery with evenly distributed over the circumference arranged teeth 16, 17. The teeth 16, 17 are formed substantially rectangular and are formed radially extending.

Like it out Fig. 2 when the toothed wheel 13 is visible, the teeth 16, 17 are formed symmetrically with respect to a beam line 18 passing through the center of the roller 9 'and the tooth center.

As it is in Fig. 3 is shown, the teeth 16, 17 formed by the front side of the circumference of the toothed disc 12, 13 recesses 19, 20. The pitch of the toothed discs 13 is larger (substantially twice as large) as the pitch of the toothed discs 12. This results in significantly larger recesses between the teeth 16 of the roller 9 than between the teeth 17 of the roller 9 '. The roller 9 and the roller 9 'are, as indicated by the arrows 21, driven in opposite directions rotating, the rotational speeds of the rollers 9 and 9' are of different sizes. In this case, the roller 9 runs slower than the roller 9 '. In a preferred embodiment the roller 9 runs at 200 to 800 revolutions per minute, preferably 400 to 600, and the roller 9 'at 800 to 2,500 revolutions per minute, preferably 1,000 to 1,400.

As it is in the FIG. 2 is shown by the arrows 11, the fiber flow is applied to the slowly rotating roller 9. In the wide recesses 19, the fibers are taken up and further transported in the direction of rotation, so that the roller 9 has the function of a transport roller. The fast-rotating roller 9 'dips into the fiber-laden roller 9 and pulls the fibers of the fiber stream through the gaps formed between the toothed discs 12, 13. By the above-described embodiment of the roller 9 ', which has a plurality of teeth 17, and which rotates much faster, a resolution of fiber clumps in the fiber stream is achieved. The roller 9 'thus has the function of an opening roller. The fiber stream then passes to a scattering roller arrangement, not shown, and can be scattered as a non-woven fabric or first reaches another conveyor.

In the FIGS. 4 and 5 In each case, a further embodiment of opening cylinder assemblies 3 is shown, which, as described above, likewise consists of two opening rollers 9, 9 'arranged in opposite directions rotating with toothed disks 24, 25 or 26, 27 arranged on the rollers. In contrast to the above-described opening roller assembly according to the Figures 2 and 3 are the toothed discs without spacers on the rollers 9, 9 'mounted.

So that the toothed disks can interact in an intermeshing manner, the toothed disks, as can be seen from the top view of the opening cylinder arrangement 3, extend radially outward (FIG. Fig. 4 ) or radially outwardly extending rounded ( Fig. 5 ). The opposite arranged Rollers 9, 9 'with mounted toothed pulleys 24, 25 and 26, 27 are arranged such that between the toothed pulleys of the adjacent rollers 9, 9', a zigzag-shaped uniform gap 29 is formed.

As shown by the double arrows 28, the zigzag gap 29 can be adjusted by changing the distance of the rollers 9, 9 '. Thus, an adaptation to differently dissolving fibers can be achieved.

In a further, not shown embodiment could also be provided that the rollers 9, 9 'of the opening roller assembly are arranged axially parallel and wherein a through the central axes of the rollers 9, 9' extending plane to a horizontal plane at an angle of 30 ° to 90 ° , preferably from 45 ° to 75 °.

In this arrangement of the rollers 9, 9 ', the material flow emerges from the opening roller arrangement 3 in the horizontal direction. As a result of the gravitational forces acting on the material flow in the vertical direction, the material flow moves in a parabola from the opening roller arrangement 3.

Depending on the kinetic energy of the particles of the material flow, the particles of the material flow move in a different pitch parabola from the opening roller assembly, so that unwanted foreign bodies can be separated from the remaining fiber stream.

The unwanted foreign bodies leaving the opening roller assembly 3 at high speed in a flat parabola can be collected in a separate tray and thus separated from the remainder of the fiber stream. By means of a screw conveyor in the shaft or an obliquely formed bottom plate of the shaft, the foreign body can be removed and be disposed of. In contrast, the fiber stream impinges on the scattering head arrangement or dosing belt scales arranged below the opening roller arrangement 3 and is subsequently scattered to form a fiber web.

Claims (7)

1. Device for scattering spreadable material onto a continuously moving substrate during the manufacture of wood material panels, comprising at least two rollers, which are arranged so as to rotate in opposite directions and are provided with toothed discs, wherein the toothed discs of adjacent rollers interact by meshing with one another, wherein the toothed discs (12) of the first roller (9) project into axial gaps of the toothed discs (13) of the second roller (9') and the teeth (16, 17) of the toothed discs (12, 13) are directed radially outwards, and wherein the first roller (9) rotates more slowly than the second roller (9'), characterized in that the pitch of the toothed disc (13) of the second roller (9') is greater than the pitch of the toothed disc (12) of the first roller (9).
2. Device for scattering spreadable material according to claim 1, wherein the toothed discs (12, 13) are spaced apart axially on the rollers (9, 9') by means of sleeves (14, 15).
3. Device for scattering spreadable material according to claim 1 or 2, wherein the teeth (16, 17) of the toothed discs (12, 13) are of a radially pointed or rounded-off design and the rollers (9, 9') are disposed in such a way that a zigzag gap arises between the toothed discs (12, 13).
4. Device for scattering spreadable material according to claim 3, wherein the rollers (9, 9') are disposed in a mutually adjustable manner.
5. Device for scattering spreadable material according to one of the preceding claims, wherein the teeth (16, 17) of the toothed discs (12, 13) are designed symmetrically in relation to a radial line (18) that extends through the centre of the roller (9, 9') and the tooth centre.
6. Device for scattering spreadable material according to one of the preceding claims, wherein the (viewed in direction of rotation) trailing sides of the tooth flanks defined by the teeth (16) are of a radially outward extending tapering configuration.
7. Device for scattering spreadable material according to one of the preceding claims, wherein the leading sides of the tooth flanks defined by the teeth (16) in direction of rotation are of a forward-sloping design.

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