EP1537968B1 - Method and system for glueing fibres, and fibre glueing apparatus - Google Patents

Abstract

Fibers are transported from a bunker (3) through an outlet (4) with belt weigher (7), and a duct (5) and housing (6), to a discharge head (14). The fibers fall through locks formed by guide plates and a grate aperture (9), and are coated with small adhesive droplets by spray nozzles (12) located on the ends of the plates. The aperture is 50 to 1999mm long and 200 - 4000mm wide. The fibers are separated by several cylinders (8) positioned above each other in the bunker outlet. The fiber volume is weighed before or after adhesive application, and the adhesive volume is proportioned accordingly. After adhesive application, the fibers drop to a conveyor belt (7) positioned at least 1,5m lower down, and the belt speed is adjusted so that the fiber level on the belt is less than 300mm, and the fibers drop into a spray head. The adhesive is high-reaction adhesive. The adhesive applicator (2) is positioned directly above a fiber mat forming belt, and the grate aperture size corresponds to max. mat width.

Description

The invention relates to a process for the gluing of fibers according to the preamble of patent claim 1, a plant for carrying out the process and a fiber gluing device.

Typically, the fibers are glued in a blowpipe, the connecting tube from the refiner to the dryer, or adhesives using various combinations of dry gluing techniques. Fiberboard-coated fibers are dried with a one-stage or two-stage dryer from a starting moisture of 30-110% to a target moisture of 5-15%. The glued fibers are placed in an air stream of a tube dryer and transported in about 3 seconds to the separator (cyclone) at a speed of 30-80 m / sec, where they are separated from the dryer air in about 3 seconds and from a rotary valve be removed. In a two-stage dryer, the fibers are added twice to the hot air stream and separated twice from the hot air with a separator. Because the fibers are carried in the hot air, Dryer inlet temperature cf. Table 1, the adhesive partially hardens during drying. Furthermore, before the adhesive is injected into the blowpipe line, the fiber has a temperature above 120 ° C. Even with a short residence time of about one second in the Blasrohrlinie this leads to a pre-curing of the adhesive. Furthermore, in the case of an unoptimized transport or a non-optimized drying, there is an increase in caking in the blowpipe line or the dryer, as a result of which the adhesive in these caking almost completely cures and thus the adhesive consumption and the formaldehyde emissions in the dryer rise. Table 1 shows the possible adhesive savings by known tube or mixer sizing procedures, which are arranged after the first or second dryer stage. The adhesive saving is about the same size in the industrially carried out pipe and mixer gluing process, since the adhesive saving is essentially due to the avoidance of the pre-hardening due to the high dryer inlet temperature. Table 1: Adhesive consumption [%] UF and MUF for various gluing methods with the same transverse tensile strength and bending strength of the MDF boards. Adhesive insert Blowpipe line 1st stage dryer Adhesive insert Blowpipe line 2nd stage dryer Adhesive insert Mixer or raw gluing of known methods Dryer inlet temperature of the air [° C] 180 (exhaust air dryer) 140 (1st level) 135 (2nd level) 50 fiber temperature before gluing Dew point temperature at the end of the dryer [° C] 46 50 (1st level) MDF standard 10-13 8th 7 (some glue spots) MDF deep tilling quality 12 11 Not possible to disturb glue spots

Various pipe adhesions have been described in the patent literature and tested at the experimental stage. In principle, a distinction can be made between spraying the ascending and descending fibers. Industrially, only the Rohrbeleimung with ascending fibers, similar to in DD 78 881 A or DE 41 22 842 A1 described been carried out. A disadvantage of these methods is the complex air technology.

In the DE 16 53 223 A There is described a method and apparatus for gluing falling fibers. This method describes the separation of the fibers before spraying, the spraying of the fibers in free fall from the side and a dissolution of the fibers or of fiber agglomerations after the spraying. Before spraying, the fibers should be separated by means of rotation and transferred into free space via a circular movement. This method with device could not prevail because the fiber singling by rotation within a stirrer tends to blockages, the throughputs are too low and above all the lateral spraying leads to an uneven gluing.

Another method to glue down falling fibers is in the DE 197 40 676 A1 described. Fibers should fall in a cylindrical tower with a diameter of 1.5 m and a length of 4 m and at Fall off the side with adhesive droplets to be sprayed. In doing so, fiber agglomerates - ie over-gluing - are deliberately accepted. After gluing, the agglomerates are redissolved in refines or mills. With this device could be saved in comparison to Blasrohrlinienbeleimung no adhesive because the fiber distribution over the cross section of the tower and the glue distribution on the fibers in a spraying from the edge is much too uneven. Fibers that are in the middle of the tower receive very little glue.

In the DE 19 04 856 A from which the invention proceeds or the GB-A-1 251 753 , an apparatus for gluing descending fibers is described. This device provides a gluing in which the gluing nozzles are installed inside the descending fiber and the glue is sprayed towards the falling fibers - a so-called internal gluing. The advantages of an internal spraying of the fiber stream with regard to a better uniformity of the adhesive application are recognized. The fibers are transported by means of transport air to a discharge head. In the discharge head rise from the wall sheets to about the middle of the head into it. In these sheets nozzles are installed, which spray the adhesive down. The device described therein does not solve the problem of clogging by fibers that settle over the protruding sheets. Especially with already glued fibers it comes within a short time to significant blockages on the sheets. With this device could Also, the adhesive consumption can not be reduced because a uniform fiber flow over the length and width of the discharge head can not be generated. Also, a fiber dissolution is not provided immediately before entering the discharge head.

The invention has for its object to provide a method by which it is possible to glue glued fibers in the blowpipe without precuring the adhesive and to provide a device for carrying out the method.

This object of the above-mentioned problems and devices are achieved by the method according to the invention according to claim 1.

A plant for carrying out the method comprises a blowpipe and a pre-gluing tube dryer, a transfer device for the fibers in a fiber bunker, a conduit and a housing for transferring the fibers into a bunker discharge and therein the arrangement of a fiber applicator with discharge head for the introduction of the glued fibers in a classifier or directly into a scattered bunker.

The Faserbeleimungsvorrichtung for the inventive method and the system according to the invention is characterized by the arrangement of several opening rollers on several axes of rotation in Bunkeraustrag as a conveying device of the fibers formed by guide plates and baffles locks to a grid opening, wherein the grid opening through the horizontally disposed ends of the guide plates is formed and wherein at the end of each guide plate a plurality of glue nozzles are housed, from.

The fibers are separated in the Bunkeraustrag by opening rollers and fall through guide plates led to a grid opening down, at the end of the guide plates glue nozzles are mounted, which spray in the direction of the falling fiber. By means of the method according to the invention, it is ensured at the time of the adhesive application that a uniform distribution of the fibers over the full spray surface is present in the discharge head and that the fibers enter the spray zone of the lattice opening in dissolved form. The fact that the opening rollers at a much higher speed promote the fibers from the Bunkeraustrag than in the conventional bunkers, a part of the fibers is conveyed horizontally up to a distance of 2 m. That is, the fibers from upper opening rollers are conveyed almost to the opposite wall while the fibers from the lower opening rollers are transported less widely. By a different setting of the speed the opening rollers and baffles, the distribution over the length of the opening can also be influenced.

Furthermore, blockages are avoided by fiber accumulations above the spraying and below the spraying. Above the spraying the blockages are avoided, since the guide plates ranging from the opening rollers to the glue nozzles. The guide plates can begin even in a width of 20 mm, ie the width of a nozzle including supply lines of the adhesive to the opening rollers or they expand only on the glue nozzles. Below the glue nozzles no guide plates or only a short distance are installed, so that the fibers can fall freely after entering the spray curtain of the discharge head.

The fiber throughput should not exceed 30 t, and preferably 2 - 20 t per hour and per m ² spray surface, so that the fibers do not form a too dense curtain. This ensures that also the fibers, which are located in the middle between two guide plates, are glued. The spray cone of the glue nozzles is adjusted so that only a slight overlap of two adjacent spray cone occurs. Similarly, the guide plate spacing is chosen so that the distance from the glue nozzle to the point in the middle of two guide plates is not so great.

The operating costs of the device are significantly lower than in the conventional mixer or Rohrbeleimungsverfahren because additional air transport must not be performed. Likewise, the investment costs are significantly lower than in the conventional method. If the integration into an existing spreading bunker takes place no additional machines are necessary. There are also no disturbing formaldehyde emissions in the exhaust air. Surprisingly, it has been found that the glue stains as good as no longer exist when a part of the adhesive is previously applied in the Blasrohrlinie on the fibers. In a combined gluing of blowpipe line and dry gluing the fibers should not be dried at temperatures above 110 ° C for further adhesive reduction. For this purpose, a 3- or multi-stage dryer can be used to reduce the inlet temperatures.

The device according to the invention can be installed directly as spreading hopper over the spreading head or over a conveyor belt, which leads the fibers to the spreading head, or in front of the classifier or before the scattering bin. If the fibers are not yet to be sifted and re-dried, they are installed in front of the sifter.

Agglomerations are formed after gluing by moving the fibers among each other and in contact with the walls (tubes mainly at the Transport in pipelines and warehouses in the bunker (in the bunker only on the outer wall). The agglomerations are later seen as glue spots in the plates. These agglomerations are particularly intense immediately in the first 2-10 seconds after gluing, when the glue on the fibers is not yet dried.

If gluing is done directly above the spreading head, the width of the dispensing head should correspond to the opening of the maximum spreading width. Due to the arrangement of the gluing over the spreading head, fiber agglomerations after gluing can hardly be formed any more, since the fibers are no longer transported and have no contact with the walls except for the scattering wall. The fibers have only contact with the lateral scattering wall, where agglomeration and thus glue spots could form. However, several measures can minimize agglomeration: If the fibers fall on a conveyor belt, the mat height on the conveyor belt to the spreading head must be set as low as possible. The feed speed of the conveyor belt is adjusted so that the fiber height on the belt is less than 300 mm. Furthermore, the wall of the conveyor belt and the scattering wall can be cooled before the scattering and / or vibrated and / or provided with an air jacket or on the inside of the wall, a band can run along with about the transport speed. Also, the discharge rollers can be operated in the spreading head with higher speed, and with a higher number of the same length (6-10 pieces per 1 m length) and a narrower clear width are provided so that agglomerations no longer get through the scattering head on the forming belt. Even if small agglomerations still form on the edge of the mat despite these measures, this is of no significance for the later plate, since this mat edge piece is first removed via the mat trimming and / or trimmed afterwards as a plate edge piece.

The material recirculation of the mat edge trimming, the scalper and the mat return can be passed through a separate fiber disengaging roller and passed to the fibers on the conveyor belt. Then the conveyor belt can be equipped with recoil rollers.

In the conveyor belt to the spreading head, a mat scales can be integrated, which can be used for dosing the adhesive and for controlling the Bunkeraustrages.

A highly reactive adhesive can be used since the time from gluing to hot pressing is less than 2 minutes for this gluing, which can shorten the pressing time.

If the gluing is installed in front of the sifter or in front of the spreading bunker, the fibers should be at least approx. 6 m clear immediately after gluing fall and then into a hot air stream (60 - 80 ° C) are passed. During the fall and in the hot air stream, a final drying of the freshly glued fibers takes place, as a result of which the glue dries somewhat and is therefore less sticky, and the moisture possibly introduced by the glue is reduced. In this arrangement, the device may consist of only a discharge head and a belt conveyor, the execution as a bunker is not necessary. The width across the conveying direction may correspond to the classifier width, so that the fibers are transported into the classifier after gluing.

Further advantageous measures and embodiments of the subject matter of the invention will become apparent from the dependent claims and the following description with the drawing.

Figur 1

eine Anlage zur Durchführung des Verfahrens,

Figur 2

die Faserbeleimungsvorrichtung in einem Ausschnitt der Anlage aus Figur 1 in einem größeren Maßstab,

Figur 3

einen Schnitt A-A aus Figur 2 in Vorderansicht,

Figur 4

einen Ausschnitt aus Figur 3 mit Darstellung der Führungs- und Seitenbleche in Schnitt B-B,

Figur 5

eine Draufsicht auf die Faserbeleimungsvorrichtung aus Figur 2,

Figur 6

in einer Seitenansicht zwei Auflösungswalzen und

Figur 7

eine Draufsicht auf die Auflösungswalzen nach Figur 6.

Show it:

FIG. 1

an installation for carrying out the process,

FIG. 2

the Faserbeleimungsvorrichtung in a section of the system FIG. 1 on a larger scale,

FIG. 3

a section AA FIG. 2 in front view,

FIG. 4

a section from FIG. 3 with representation of the guide and side panels in section BB,

FIG. 5

a plan view of the Faserbeleimungsvorrichtung from FIG. 2 .

FIG. 6

in a side view two dissolving rollers and

FIG. 7

a plan view of the dissolution rollers after FIG. 6 ,

Annex 1 for carrying out the method is in FIG. 1 and the fiber sizing device 2 in FIGS FIGS. 2 to 7 shown. It comprises a blower tube 17 and a tube flow dryer 20 for pre-gluing, a transfer device for the fibers in a fiber bunker 3, a conduit 5 and a housing 6 for transferring the fibers into a Bunkeraustrag 4. The Faserbeleimungsvorrichtung 2 consists of a discharge head 14 for the entry of glued fibers in a classifier 16 or directly on the scattering head 19 in a scattering hopper (not shown) and the arrangement of several opening rollers 8 on top of each other on several axes of rotation in Bunkeraustrag 4. Next from a conveying device of the fibers formed by guide plates 11 locks 10 in a grid opening 9. The grid opening 9 is formed by horizontally arranged ends of the guide plates 11 and each end of each guide plate 11 more glue nozzles 12 are housed. In Bunkeraustrag 4 at least three, preferably eight opening rollers 8 are provided for separating the fibers in an oblique arrangement one above the other, wherein the fibers are conveyed from the fiber bunker 3 in the Faserbeleimungsvorrichtung 2 via a belt weigher 7 continuously. The glue nozzles 12 are arranged at the end of the guide plates 11 and optionally provided with widenings 24. The guide plates 11 are to form locks 10 of the Opening rollers 8 performed to the glue nozzles 12, wherein adjustable baffles 13 are mounted between the sluices 10. The air flow can be influenced by the discharge head 14 with an exhaust 18.
The opening rollers 8 exist after the FIGS. 6 and 7 each from a torsion bar 25 with it, spaced from spacers 23 slices 21 and therefrom zahnradmäßig protruding release elements 22. For post-drying of the fibers after gluing a hot air supply 15 is provided in the separator 16.

List of Reference Numerals: DP 1298 EP

1

investment

2

Faserbeleimungsvorrichtung

3

fiber bunker

4

Bin discharge

5

management

6

casing

7

Belt scale and conveyor belt

8th

opening rollers

9

grid opening

10

smuggle

11

guide plates

12

glue nozzles

13

baffle

14

discharge head

15

Hot air supply

16

sifter

17

blowpipe

18

suction

19

Spreading head line

20

Pipe flow dryer

21

dissolving discs

22

opening elements

23

spacers

24

widening

25

torsion bar

Claims (29)

1. A process for gluing fibers in the dry and semi-dry process during fiberboard manufacture in which the fibers are transported out of a fiber hopper (3) through a hopper outfeed (4) and inside a pipeline (5) and housing (6) to an outfeed head (14), in which gluing nozzles (12) spray glue particles in the direction of the falling fibers, characterized in that
   the fibers in the hopper outfeed (4) are singled out by dispersing rolls (8) and are directed downwards by gates (10) formed by guide plates (11) and baffles (13) to a mesh opening (9) formed out of the ends of the gates (10), and in which gluing nozzles (12) are arranged at the ends of the guide plates (11).
2. The process in accordance with Claim 1,
   characterized in that
   the fibers from the fiber hopper (3) are continuously transported over a belt weigher (7) to the hopper outfeed (4), in which case the fibers drop downwards through the mesh opening (9) that is 50 mm to 1000 mm long and 200 mm to 4000 mm wide, and as the fibers drop they are impacted by small droplets of glue in the downwardly vectored flow of air.
3. The process in accordance with Claims 1 and 2,
   characterized in that the fibers are singled out by several dispersing rolls (8) arranged one above the other in the hopper outfeed (4).
4. The process in accordance with one of the Claims 1 to 3,
   characterized in that
   the dispersing rolls (8) arranged close to the mesh opening (9) operate at a slower speed than the dispersing rolls (8) that are located further away.
5. The process in accordance with one of the Claims 1 to 4,
   characterized in that
   the distribution of the fibers through the mesh opening (9) can be influenced by adjusting the setting of the speed of the dispersing rolls (8).
6. The process in accordance with one of the Claims 1 to 5,
   characterized in that the distribution of fibers through the mesh opening (9) is influenced by one or more adjustable baffles (13).
7. The process in accordance with one of the Claims 1 to 6,
   characterized in that
   the fiber flow rate is weighed before or after gluing and the glue dosing is adjusted according to the measured value for the flow rate.
8. The process in accordance with one of the Claims 1 to 7,
   characterized in that the fiber flow rate is 2 to 30 t/h, and in a preferred embodiment 10 t/h, for each square meter of spraying area.
9. The process in accordance with one of the Claims 1 to 8,
   characterized in that the fibers are pre-glued in a blast pipe (17) before dry gluing and are then dried in a multi-stage untreated flow dryer with an inlet temperature below 110 degrees Celsius.
10. The process in accordance with one of the Claims 1 to 8,
    characterized in that
    immediately after gluing, the fibers drop onto a conveyor belt (7) that is located at least 1.5 m further down, in which case the advance speed of the conveyor belt (7) is set so that the height of the material transported on the belt is less than 300 mm and the fibers then drop into a spreading head.
11. The process in accordance with one of the Claims 1 to 9,
    characterized in that
    the conveyor belt and the spreading wall are cooled, vibrated and/or jacketed with air after the gluing section, or that a belt runs along as well on the inside with approximately the same transport speed.
12. The process in accordance with one of the Claims 1 to 11,
    characterized in that the fibers are singled out at the end of the conveyor belt by means of outfeed rolls.
13. The process in accordance with one of the Claims 1 to 12,
    characterized in that directly after gluing, the fibers are transferred to a sifter (16) with approximately the same width and, inside that, they are heated with hot air (15) and are swirled up by the supply of air from the side walls 100 to 400 mm after the gluing stage.
14. The process in accordance with one of the Claims 1 to 13,
    characterized in that after gluing, the fibers drop into a funnel which is arranged at least 6 m further down than the outfeed head (14), in which case the funnel walls are enclosed by a hot air jacket.
15. The process in accordance with one of the Claims 1 to 14,
    characterized in that the gluing nozzles (12) are set in such a way that two adjacent spraying cones only overlap slightly.
16. The process in accordance with one of the Claims 1 to 15,
    characterized in that the fibers are glued directly above the spreading head of the spreading station used to form the fiber mat.
17. The process in accordance with one of the Claims 1 to 16,
    characterized in that a highly reactive glue is used for gluing the fibers.
18. A fiber gluing device (2) for undertaking the process in accordance with Claims 1 to 17, characterized in that
    several dispersing rolls (8) are arranged one above the other on several rotating shafts in the hopper outfeed (4) as a means of transporting the fibers through gates (10) formed by guide plates (11) and baffles (13) to a mesh opening (9), in which case the mesh opening (9) is formed by the horizontally arranged ends of the guide plates (11) and several gluing nozzles (12) are arranged at the end of each guide plate (11).
19. The fiber gluing device in accordance with Claim 18,
    characterized in that
    at least three, but in a preferred embodiment, eight dispersing rolls (8) are provided in an angled arrangement one above the other, and their speed of rotation is 400 to 1000 revolutions per minute.
20. The fiber gluing device in accordance with one of the Claims 18 and 19,
    characterized in that
    the fibers from the fiber hopper (3) can be transported into the fiber gluing device (2) continuously over a belt weigher (7).
21. The fiber gluing device in accordance with one of the Claims 18 to 20,
    characterized in that
    the gluing nozzles (12) are arranged on the end of the guide plates (11) and within the downward stream of fibers/air.
22. The fiber gluing device in accordance with one of the Claims 18 to 21,
    characterized in that
    the arrangement of guide plates (11) forming the gates (10) is configured from the dispersing rolls (8) to the gluing nozzles (12).
23. The fiber gluing device in accordance with one of the Claims 18 to 22,
    characterized in that
    the air flow through the outfeed head (14) can be influenced by an extraction device (18).
24. The fiber gluing device in accordance with one of the Claims 18 to 23,
    characterized in that
    the guide plates (11) are configured with a thickness from 15 mm to 35 mm extending from the dispersing rolls (8) to the gluing nozzles (12).
25. The fiber gluing device in accordance with one of the Claims 18 to 24,
    characterized in that
    the dispersing plates are configured with a thickness of 2 mm to 10 mm and are opened apart at the end for the gluing nozzles by means of a flaring (24).
26. The fiber gluing device in accordance with one of the Claims 18 to 25,
    characterized in that
    a dispersing roll (8) consists of a rotating rod (25) with dispersing disks (21) mounted on it and spaced apart by spacer sleeves (23) as well as by dispersing elements (22) protruding from them like gear teeth.
27. A machine for undertaking the process in accordance with Claims 1 to 17 by using a device in accordance with Claims 18 to 26, comprising a blast pipe (17) and a tubular flow dryer (20) for pre-gluing, a transfer device for transferring the fibers into a fiber hopper (3), a pipeline (5) and a housing (6) for transferring the fibers into a hopper outfeed (4) and, in that, the arrangement of a fiber gluing device (2) with outfeed head (14) for inputting the glued fibers into a sifter (16) or directly into a spreading head hopper.
28. The machine in accordance with Claim 27, characterized in that the fiber gluing device (2) is arranged directly above the spreading head hopper and the fiber mat forming belt.
29. The machine in accordance with Claims 27 and 28,
    characterized in that the width of the mesh opening (9) corresponds to the maximum fiber mat width.

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