EP1201381B1 - Apparatus for distributing loose material on a continuously travelling support - Google Patents

Description

The invention relates to a device for spreading spreading material on a continuously moving base according to the preamble of patent claim 1.

In the production of wood-based panels, especially wood fiber boards, there is the problem that form so-called fiber bales by the transport of the fibers. This is usually caused by wall friction, back combing, etc. cause the material recirculation and combine the fibers into spherical fiber agglomerates. These fiber bales are very undesirable because they lead in the finished wood fiber board to a cloud-like surface structure and represent a visual quality deficiency.

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.

For dissolving the fiber bales described above, various devices are known. These are usually arranged between the Austragswalzenanordnung the Dosierbunkers and the scattering head assembly.

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

Furthermore, from 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. If, however, other foreign bodies such as stones together with the material flow in the opening rollers, it can cause damage to the rollers. This can lead to deformation or breakout of individual spines or teeth of the rollers.

From DE 25 35 461 a device for scattering matte grit on a moving surface is also 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 DE 42 12 017 a cover layer scattering 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 and damage to device parts of the production plant for the production of wood-based panels are avoided. This object is achieved by the features specified in claim 1.

Due to the formation of the first roller, which rotates slowly and has recesses between the dissolution elements, entrainment of the material to be dissolved is achieved. The second roller, which also has dissolution elements 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 resolution elements and the fast rotation, a good fiber resolution is achieved. If, in the case of the present invention, a stream of material enters the rolls with a foreign body such as a stone, for example, and hits a dissolving disk at a high differential speed, then the resiliently formed dissolving disk is elastically deformed. As a result, the momentum forces are reduced by a multiple. During impingement on the spring-elastic take-up disc, the foreign body is due to the opposite rotation of the rollers through the gap between the slices of adjacent rollers promoted and the foreign body is accelerated to the same speed. In a foreign body, which is larger than the gap of the passage between the slices, the foreign body can be accommodated due to the resiliently formed release disks between the elements, so that there is no damage to the rollers or the elements.

Since the slices are advantageously formed as spring plates with a sheet thickness of 1.5 mm, which have a low air resistance, can avoid or reduce be achieved by air currents and turbulence in the area of the rotating rollers. This has the advantage that no unwanted turbulence of the fibers are produced at the outlet, which would otherwise lead to an undesirable temporal as well as local redistribution of the mass flow. Since the thin spring plates are formed as slices and preferably have a sheet thickness of 1-3 mm, and these are arranged axially spaced on the rollers, the axial distance is preferably 3-5 mm, a high throughput can be achieved due to the large gap passage area , In this case, the axial distance is selected as a function of the size of the smallest fiber bale that is to be dissolved.

In a further development of the invention it is provided that the opening elements have recesses on the front side, so that two tips are formed. This allows an even better resolution of fiber bales can be achieved.

A particularly preferred embodiment of the invention provides that the rollers are arranged mutually adjustable, so that the release elements of the slices from a state in which they cooperate interlocking to a state in which they can not be interacting with each other can be adjusted.

Figur 1 :

eine schematische Darstellung einer Formstation mit Auflösewalzenanordnung;

Figur 2a, 2b:

eine Ausführungsform eines Auflösewalzenpaares in Seitenansicht und ein Teilausschnitt in Draufsicht;

Figur 3 :

eine weitere Ausführungsform einer erfindungsgemäßen Zahnscheibe.

Further advantageous features of the invention will become apparent from the following description of exemplary embodiments with reference to the drawings. It shows:

FIG. 1:

a schematic representation of a forming station with Auflösewalzenanordnung;

FIGS. 2a, 2b:

an embodiment of an opening roller pair in side view and a partial detail in plan view;

FIG. 3:

a further embodiment of a toothed disc according to the invention.

In Fig. 1 is a forming station 1 with dosing bunker 2, an opening roller assembly 3, a feeder 4, a scattering head assembly 5 and a forming belt 6, to which the material web 7 is sprinkled from glued fibers schematically shown. In the dosing bunker 2, the material stream, which preferably consists of glued fibers, is temporarily stored 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 Auflösewaizenanordnung 3, consisting of two oppositely rotating driven rollers 9, 9 '. The rollers 9, 9 'are, as can be seen from FIGS. 2a, 2b, arranged parallel to the axis in a horizontal plane next to one another. Further details on the execution of the rollers 9, 9 'are described with reference to the figures 2a, 2b and 3. 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 another arrangement, not shown, the fiber opening roller assembly 3 could also be between the conveyor 4 and the scattering head assembly 5 may be arranged. 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.

FIGS. 2 a and 2 b show an embodiment according to the invention of an opening roller arrangement 3 which consists of two rollers 9, 9 'arranged axially parallel to one another. The opening roller arrangement 3 described below is preferably used for the production of fiberboard as already described with reference to FIG. 1, fibers glued from a metering bunker being fed onto the roller 9 as a material stream via a discharge roller arrangement. The task of material flow on the roller 9 is shown by the arrows 11. The rollers 9, 9 'are provided with slices 12, 13, wherein the slices 12, 13 on the rollers 9, 9' are each arranged axially spaced. Spacers 14, 15 are inserted between the adjacent discs 12, 13 arranged on the rollers.

However, a positioning or axial spacing of the slices can also be designed differently. In another embodiment, comb strips can be arranged on the rollers 9, 9 ', which in each case have corresponding grooves for positioning the separating disks at a defined distance. The slices can then be screwed in their predetermined position via a bayonet lock in the comb strips and thus fixed.

The slices 13, which are arranged axially spaced on the roller 9, project centrally, as can be seen from the figure 2b, in the interstices of the on the roller 9 'axially spaced slices 13. The slices 12,13 are made of a resilient material, preferably made of thin spring plate. The sheet thickness of the slices 12,13 in this embodiment is 1.5 mm.

The slices 12 and 13 of the rollers 9 'and 9 are each formed the same.

As can be seen from FIG. 2 a, the dissolving disks have an annular section 16 from which dissolution elements 17 distributed uniformly over the circumference extend radially outward, between which recesses 19 remain. The dissolving elements 17 are formed substantially rectangular. Furthermore, tapered recesses are provided centrally at their ends radially inwardly, so that two ends 18 are formed at each end of the release element.

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 one 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 shown in FIG. 2a by the arrows 11, the fiber flow is applied to the slowly rotating roller 9. In the recesses 19, which are formed between the dissolving elements 17, 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. The gap width through which the fiber flow as well as foreign bodies and fiber bales can pass unhindered is 5 mm, wherein the distance in the axial direction from the release disk to the release wheel of a roller is 11.5 mm. By the above-described embodiment of the roller 9 ', which is also provided with slices, and which rotates much faster, a resolution of fiber bales in the fiber stream is achieved. Due to the elastic design of the slices, damage to the slices on the passage of foreign bodies can be avoided because the slices are elastically deformable and can dodge. 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.

As shown by the double arrow 22 in Fig. 2b, the distance between the rollers 9, 9 'in a range of 50 mm can be changed, whereby a meshing state of the slices 12,13 adjacent rollers 9,9' (Fig Fig. 2a, 2b) and a non-combing state (not shown) can be set. When setting a non-intermeshing state, the spacers are replaced on each roller 9,9 'and further dissolving discs mounted so that the axial distance of the discs on each roller 9,9' 5 mm.

In Fig. 3, a further embodiment of a take-up disk 12/13 is shown, which has substantially the already described to FIGS. 2a, 2b contour, but has no frontally introduced into the opening elements recesses. In a further development, the radially outwardly facing edges of the opening elements could also be rounded.

Claims (10)

1. Device for spreading of spread material onto a continuously moved caul in the production of wood-based panels, having at least two rolls(9, 9') arranged adjacent to each other and rotating in opposite senses, which are provided with dissolving discs (12, 13), characterized in that the dissolving discs (12/13) of the first roll (9) and of the second roll (9') are spring-elastic and are provided with dissolving elements (17) pointing radially outward, said first roll (9) rotating slower than the second roll (9').
2. Device for spreading of material according to claim 1, said dissolving elements (17) having rectangular cross-sections and being evenly distributed around the circumference.
3. Device for spreading of material according to claim 1 or 2, said dissolving discs (12, 13) being axially spaced on the rolls (9, 9') by means of sleeves (14, 15).
4. Device for spreading of material according to claim 3, the thickness of the dissolving discs (12, 13) being many times smaller than the axial distance between the dissolving discs (12, 13).
5. Device for spreading of material according to claim 4, the thickness of the dissolving discs (12,13) being chosen between 1 and 3 mm and the axial distance between 2 and 10 mm, preferably between 3 and 5 mm.
6. Device for spreading of material according to claim 1, said rolls (9, 9') being arranged to be adjustable with respect to each other.
7. Device for spreading of material according to claim 6, said dissolving discs (12, 13) of adjacent rolls (9, 9') co-operating by engaging each other.
8. Device for spreading of material according to claim 6, said dissolving discs of adjacent rolls (9, 9') being arranged in such a way that they do not co-operate by engaging each other.
9. Device for spreading of material according to claim 1, said dissolving elements (17) having recesses on the front which taper radially towards the interior and thus form two tips at the ends.
10. Device for spreading of material according to claim 1, the radially outward-pointing edges of the dissolving elements (17) being rounded off.

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