WO2003106127A1 - Method and device for applying a material to dried fibers that are used for producing fiber plates - Google Patents

Abstract

The invention relates to a method and a device for applying a material to dried fibers which are delivered in a metered manner to a rotating fiber roller (15) and are redirected and accelerated by means of said fiber roller (15). The invention is characterized by the fact that the fibers are then directed into a transport shaft (11) which is provided with a winding sector (24) comprising a first bent section (25) and a second section (26) that is bent in the opposite direction, are pressed against an outer wall section (54), are directed to an opposite wall section (54a) of the transport shaft (11) in a transition area between the first (25) and the second bent section (26), one side of the fibers being provided with the material by means of a first nozzle (28), whereupon the fibers are once again directed to an opposite wall section of the transport shaft (11) and the other side thereof is provided with the material by means of a second nozzle (28a).

Description

 DESCRIPTION

Method and device for applying a substance to dried fibers intended for the production of fiberboard

The invention relates to a method and an apparatus for applying a substance to dried fibers provided for the production of fiberboard according to the preamble of claim 1 and claim 14. The fibers are preferably made of lignocellulosic and / or cellulosic materials. The fiberboard is light, medium-density or high-density fiberboard.

It is customary to glue fibers which are intended for the production of MDF or HDF boards in the wet state. With this so-called blow-line gluing, the binder is sprayed into a blowing tube ending in the entrance area of the tube dryer behind a refiner onto the wet, still hot fibers. The fibers are then dried. Blow-line gluing enables uniform fiber gluing and thus prevents clumping by fibers and glue. A major disadvantage of blow-line gluing is, however, a relatively high glue consumption (see, for example: Buchholzer, P., "Glue losses on the track", pp. 22-24, MDF magazine 1999). The increased consumption Glue is caused by the fact that part of the reactivity of the glue is lost during the drying process of the fibers due to the high temperatures, so that in the dryer system the emission of formaldehyde resulting from the glue is considerable, which requires complex pollutant minimization.

The disadvantages of blow-line gluing can be avoided by gluing the fibers in the dry state. It is known to glue dried fibers in a mixer. However, the dry gluing of fibers in mixers has the disadvantage that fiber agglomerates and matting occur, which lead to uneven fiber gluing and an un- desired formation of glue stains in the board surfaces (see loc. cit.). A dry gluing machine, in which mixing tools can be provided, is described, for example, in EP 0 744 259 B1.

From EP 0 728 562 A2 a process for dry gluing of fibers is known, in which the flow of fibers is loosened in a pneumatic conveying line by generating high turbulence due to reduced flow velocity and the fibers in this loosening zone are wetted by spraying.

DE 199 30 800 A1 describes a process for the dry gluing of fibers, in which the gluing takes place in an end section of a tube dryer. We believe that this procedure no experience from industrial testing yet. A disadvantage of this process is that a very high proportion of hot gas and water vapor must pass through the gluing zone together with the fibers, since it is imperative that the glue is atomized into the smallest particles when it is injected into the gluing zone. With this high proportion of hot gas and water vapor, which is separated from the fibers by means of a cyclone in the process immediately after the gluing process, it can be assumed that part of the glue with the hot gas and water vapor escapes from the fiber mixture into the atmosphere. Furthermore, with this known method there may be problems with regard to the uniformity of the gluing in view of the random air turbulence generated. It also appears difficult with this process to keep the drying moisture of the fibers under control within the tolerances of +/- 0.5% of the sol value which are very important for the further process.

From DE 29 13 081 A1 a method and a device for gluing wood chips are known, the gluing taking place in two stages when the chips are passed through a shaft-like shaft. The chips to be glued, however, are flat chips with two main surfaces to be glued. The shaft curve-like shaft serves to turn the chips so that both main surfaces can be glued. NEN. The chips move through the shaft relatively slowly. A disadvantage of the known device is that the gliding surfaces of the device are also glued by penetration of the glue through the wood chips and, furthermore, in the second gluing step the glued upper side of the chips becomes the underside of the flow of chips and thus also the sliding surfaces of the device Glue come into contact. In this way, the lubricity of the chips on the sliding surfaces of the device can be severely restricted due to contamination.

It should also be mentioned that gluing devices of the so-called "roller blender" type have been known for some time, in which glue is applied to wood particles by means of rollers (Maloney, Thomas M., "Modern Particleboard & Dry-Process Fiberboard Manufacturing", p 439 f, Miller Freeman Publ. 1977, San Francisco, Ca., USA).

From WO 02/14038 a generic method and a generic device are known. The fibers are glued in the area of the outlet opening of the shaft section, with which good results are achieved. In particular, as much surface of the fibers as possible is wetted with binder with high uniformity.

The invention has for its object to avoid internal contamination of a pneumatic transport shaft, in which the fibers get from the outlet opening of the shaft section.

With regard to the method, this object is achieved by the features of claim 1. The fibers, which can be glued or unglued, are fed from a metering device through a feed shaft to which a vacuum is applied to a fiber roller which is provided on its surface with a large number of pins which preferably taper conically in the radial direction. The fiber roller rotates in such a way that the fibers are deflected by the pins and guided along a shaft section which is delimited by a partial section of the circumference of the fiber roller and by an opposite wall. The fibers are held by the pins and accelerated to approximately the circumferential speed of the fiber roller by an air flow generated thereby. The fibers are preferably removed from the fiber roller by the centrifugal force and lie against a section of the wall, the fibers no longer coming into contact with the pins.

The fibers leave the feed chute in a fiber stream and hit the fiber roller. Due to the action of the pins arranged on the rapidly rotating fiber roller, the fibers are not only deflected, but also greatly accelerated, as a result of which irregularities such as fiber agglomerates are eliminated. Furthermore, the fiber flow is stretched by the acceleration of the fibers in the direction of flow by a multiple compared to the fibers in the feed shaft. At the same time, the pressure with which the fibers are pressed against the wall during transport through the shaft section increases the bulk density of the fibers, for example to three times the bulk density of the fibers within the feed shaft. Accordingly, the fiber flow height is reduced with increased bulk density.

In this form, the fibers enter a pneumatic transport shaft with a wave-like section. The wave curve-like section has a first arc section and an oppositely curved second arc section. The second arch section can directly adjoin the first arch section, so that the wave-curve-like section consists of the two arch sections. However, a straight section, which is part of a transition region from the first to the second curved section, can also extend between the two curved sections. The wave curve-like section can be a wave-shaped section, in particular a sinus curve-like section, ie a section which essentially has the shape of a sine curve. It can also be provided that the two arc sections, or at least one of the two arc sections, are essentially semicircular. According to the invention, the possibility is also included that the two arc sections are not configured symmetrically to one another. The air flow transporting the fibers through the pneumatic transport shaft has such a speed that the fibers are pressed against an outer wall section of the first sheet section due to the centrifugal force. The outer wall section is understood to mean that part of the wall of the transport shaft which has the larger radius compared to an inner wall section. The fibers are directed through a first guide plate, which is arranged approximately in the transition area from the first to the second curved section and inclined like a ramp, to an opposite wall section of the transport shaft. The transition area can extend between the two arc sections. However, it can also contain an end region of the first arch section and / or an initial region of the second arch section or can be composed of the two regions. The first guide plate can preferably be arranged after a curvature of 180 ° in the transport shaft, in particular where the direction of curvature changes, ie at a turning point of the wave-curve-like section or the wave curve. However, the first guide plate can also be arranged somewhat in front of or behind the turning point, namely in such a way that the fibers are directed to the opposite wall section and initially remain there due to the centrifugal force.

The fibers preferably reach the first baffle in a millimeter-thin fiber film which is closed in the surface and leave the first baffle in this form. The first guide plate is preferably adjustable at an angle to the direction of flow of the fibers, so that the fibers can be optimally directed to the opposite wall section of the transport shaft, namely the outer wall section of the second curved section of the transport shaft. Shortly after the fibers have left the first guide plate, that is to say they have been lifted from the shaft wall and float freely, they are provided with the material to be applied from one side (hereinafter referred to as "treated"). This is done by means of at least one first nozzle, which is preferably a nozzle is a spray nozzle which is arranged in the transport direction adjacent to the first baffle.

The fiber stream thus provided with the fabric on one side then enters the second curved section of the transport shaft, or after passing through the possible straight section. As a result of the centrifugal force, the process in the first arc section is repeated in the second arc section. The fiber stream is pressed, preferably again in a millimeter-thin fiber film, against the outer wall section of the second arc section. The fibers or the fiber stream lie with the side not yet provided with the fabric, that is to say untreated, against the outer wall section of the second arch section. The fibers are then directed through a second guide plate, which is arranged on the outer wall section of the second curved section, to the opposite wall section of the transport shaft. After leaving the second baffle, the fibers are subjected to a treatment step again, the side of the fibers or the fiber stream which has not yet been treated now being provided with the substance. Again, this is preferably done via at least one spray nozzle. The nozzles can in particular be multi-component atomizing nozzles in which air or another gas is used as the atomizing gas.

The substance to be applied can be, in particular, glue, a hardener (accelerator), dye or water vapor. Dyes are commercially available in powder form.

With the method according to the invention, in addition to avoiding internal contamination of a pneumatic transport shaft, it can also be achieved that a proportionately small volume of the substance to be applied can be uniformly distributed over a proportionately large fiber volume. This applies both to liquids and to solid substances, such as dyes in powder form. Thus, according to the invention, the problem is also solved, Distribute substances that are already applied to glued fibers and therefore separately from the glue evenly over the fibers.

An important substance that has to be applied after gluing the fibers is a hardener, which accelerates the reactivity of the glue. If possible, the hardener is brought into contact with the glued fibers at the end of the process preceding the formation of a nonwoven in order to avoid pre-hardening of the glue and at the same time to make the glue as aggressive as possible. The method according to the invention, which can be used for this after the glued fibers have been sifted, offers an ideal possibility for this.

The application of water vapor to glued fibers can be advantageous in order to keep the fibers as warm as possible by such conditioning before they are pressed into a plate in a press. In this way, the fibers can be conditioned, which can bring advantages by shortening the pressing times. The moisture content of the fibers can be adjusted very precisely using the method according to the invention. For this purpose, multi-substance atomizing nozzles can be used, in which water vapor is used as the atomizing gas. In this way, water vapor and another substance to be applied can be applied to the fibers simultaneously. If only water vapor is to be applied to the fibers, a single-component nozzle is sufficient.

If the process according to the invention is used to glue the fibers, the application of a very thin glue film to the fibers is sufficient because the fibers are pulled apart to form a preferably millimeter-thin fiber film. This thin glue film dries in a fraction of a second during pneumatic transport through the transport shaft, so that the glue applied in the first gluing step is largely or completely dried when the fibers with the glued side follow the second gluing step against the opposite wall section of the transport shaft issue. That way soiling of the wall of the transport shaft is prevented by glue attachments.

According to the invention, the flow pattern of the treated fibers is oriented due to the baffles and the alternating centrifugal force such that immediately after the application of the material there is no contact of the treated fiber surface with the wall of the transport shaft. In this way, a preferably micrometer-thin glue film has the opportunity to dry through the transport air before the glued side of the fibers comes into contact with the wall of the transport shaft.

The area of the transport shaft in which glued fibers are transported is preferably completely covered with a water-cooled cooling jacket. The cooling jacket has the task of bringing the inner surfaces of the transport shaft to a temperature which triggers condensation of the moisture in the transport air. The resulting condensation film on the inner surfaces prevents caking of glue. This is an additional measure that counteracts internal contamination of the pneumatic transport shaft.

It can be provided that the fibers emerge essentially horizontally at the outlet opening of the shaft section and are subsequently sighted. This sighting occurs because the air flow of the pneumatic transport shaft is generated by negative pressure and acts downwards or upwards on the fibers. Fibers, which represent normal goods, are deflected in this way into the transport shaft, while impurities in the form of coarse goods are fed to a coarse goods discharge which has an inlet lying in the direction of throw of the fiber roller or opposite the outlet opening of the shaft section. When the air flow is directed downwards, the coarse material is deflected less than the normal material. When the air flow is directed upwards, the normal goods are deflected upwards, while the coarse goods are deflected downwards. When the gluing process is applied, the fibers are at the time of this Sifting not yet glued, so that internal contamination of the classifier used or an inlet opening of the transport shaft is avoided.

When exiting the shaft section delimited by the fiber roller and an opposite wall, the fibers are preferably introduced into the air flow of the transport shaft in such a way that they run into the first curved section along the outer wall section of the transport shaft. This can be achieved, for example, by an adjustable flap arranged at the end of the shaft section.

The air speed in the transport shaft is preferably selected such that the fibers press themselves against the outer wall section substantially in the form of a fiber film, approximately from the center of the first arc section. The air speed can be adjusted by an adjustable slide in the transport shaft.

It is further preferred that the second guide plate is arranged approximately at the end of the second curved section.

The transport shaft is preferably rectangular in cross section.

It is preferably provided that the width of the transport shaft increases after each treatment step in order to prevent sidewall regions of the transport shaft from coming into contact with the fiber material immediately after the substance has been applied. Alternatively, it can also be provided that the fiber stream is constricted laterally shortly before each treatment step by means of corresponding guide plates.

Warm air can be used as transport air in the transport shaft. This warm air can be partly exhaust air recirculated from a cyclone and partly preferably fresh air that is heated. The warm air prevents the fibers from cooling down. This is desirable because warm fibers shorten the process in the plate press. In the closed air circulation system consisting of return air and fresh air, the fresh air replaces Ventilation air, which is required to remove residual moisture, which is dried out of the fiber material on the transport path from drying to the formation of a nonwoven fabric. The fresh air is preferably blown through openings arranged in the transport shaft in such a way that the fresh air helps to guide the fiber stream to the opposite wall section of the transport shaft. This means that the fresh air openings are arranged adjacent to the at least one first and the at least one second nozzle in the transport direction.

The throughput of fibers through the transport shaft depends on the operating conditions of the plate production and is subject to fluctuations. The demand for the substance to be applied fluctuates accordingly. In order to ensure a constant ratio of the two contact surfaces of the material or the fibers at any given throughput, the aforementioned adjustable slide is preferably provided on the suction side of a fan. The air volume and thus the flow velocity and speed of the fibers in the pneumatic transport shaft can be determined via this slide. With regard to glue, the contact area results from the glue throughput, the mean drop size of the glue spray generated by the glue spray nozzles remaining constant. The fiber throughput determined gravimetrically by a weighing device of the metering device is preferably used as the guide variable for the transport air control.

In particular, it can be provided that the transport shaft has a plurality of sections arranged in series, similar to wave curves. The wave curve-like sections can serve to carry out several identical treatment stages in succession. Since only a small percentage of the ultimately desired material application is carried out at each treatment stage, in particular a very rapid drying of an applied liquid, in particular a glue film, can be guaranteed and thus internal contamination of the transport shaft or a classifier can be avoided particularly safely. The other wave curve-like sections can, however, also be used, via others, accordingly arranged nozzles to wet the fibers by spraying with another substance, such as other additives or water vapor.

The process is characterized by a high degree of uniformity in the distribution of substances. This uniformity is ensured by the fact that very large contact surfaces are provided both with respect to the fibers by means of the fiber roller and with respect to the material by atomization, which are brought together in a uniform manner. In particular, over-gluing of fibers can thereby be avoided.

The above object is achieved with regard to the device by the features of claim 14. Essentially the same advantages result here as were previously mentioned in connection with claim 1. Preferred embodiments of the device are listed in claims 15 to 26. In particular, the substance to be applied can be a hardener, but also one of the other substances mentioned above. The device can thus also be a device for gluing, in which case the nozzles are glue nozzles.

The invention is explained in more detail below on the basis of two exemplary embodiments, reference being made to the figures. Show it:

1 schematically shows a gluing device with a wave-curve-like section and a fiber sifter unit,

Fig. 2 shows a gluing device with two gluing stages, and

Fig. 3 shows a device for applying a hardener.

1 has a metering bunker 1. The dosing bunker 1 has an inlet 2 for filling with dried wood fibers 3. The wood fibers 3 are fed to a dosing bunker discharge with discharge rollers 5 by means of a base belt 4. Larger clumps of the fibers 3 are dissolved by the discharge rollers 5. The bottom band 4 runs on a belt scale 6, which continuously records the running fiber throughput weight (weight per unit of time).

From the dosing bunker discharge 5, the fibers 3 enter a feed shaft 9 made of two molded walls 7 and 8, which has an air supply 10 at an upper end. A mixture of fibers and air is sucked into the feed shaft 9 by means of a pneumatic transport device which has a feed shaft 11 which is rectangular in cross section and a fan 12, the fibers moving in a fiber stream 13 along the mold wall 8 to an outlet opening 14 of the feed shaft 9 , In the area of the outlet opening 14 of the feed chute 9, the fiber stream 13 encounters a fiber roller 15 which serves to resolve irregularities in the fiber stream 13 and to accelerate the fibers in the fiber stream 13. A plurality of pins 16 are arranged on the surface of the fiber roller 15, which taper conically to a tip as the distance from the axis of rotation of the fiber roller 15 increases. The fiber roll 15 rotates at high speed in the direction of rotation indicated by the arrow 17. The peripheral speed of the fiber roller 15 is variable and can be 20 to 100 m / sec. The diameter of the fiber roller 15 can be, for example, 1000 mm and the length of the fiber roller 15 can be, for example, 1800 mm. In this case, the conical pins 16 are approximately 10,000 pieces.

A section 18 of the fiber roll circumference and a wall 19 opposite the fiber roll 15 delimit a shaft section 20 which extends approximately from an inlet opening 22 at the outlet opening 14 of the feed shaft 9 to the lowest point of the fiber roller 15 and has an outlet opening 21 there.

The outlet opening 21 of the shaft section 20 is delimited by a flap 23 which is adjustable in angle.

The transport shaft 11 adjoins this at approximately a right angle to the outlet opening 21 of the shaft section 20. The transport shaft 11 has a corrugated section 24, which consists of a first Semicircular section 25 and a second semicircular section 26 is composed. A first guide plate 27 is arranged in the wall of the transport shaft 11 approximately at the turning point of the wave-shaped section 24. The first guide plate 27 is inclined like a ramp in the transport direction of the transport shaft 11. This inclination is adjustable.

In the transport direction adjacent to the first guide plate 27, a row of first glue spray nozzles 28 (only one is shown) is arranged across the width of the transport shaft 11 in a wall opening. Adjacent to the first glue spray nozzles 28 is an opening 29, which extends over the width of the transport shaft 11, for the supply of fresh air. The fresh air supply is indicated by arrow 30.

Approximately at the end of the second semicircular section 26, in turn, as in the first semicircular section 25, there is a second guide plate 27a which can be set at an angle, a row of second glue spray nozzles 28a and a second fresh air opening 29a for supplying fresh air 30a.

On the suction side of the fan 12, a controllable slide 31 is arranged in the transport shaft 11 for setting the flow speed of the air flow indicated by the arrow 32. A fiber transport line 33 leads from the fan 12 to a cyclone 34.

Fibers separated in the cyclone 34 are transported by the cyclone 34 in the direction of the arrow 35 to a fiber molding machine, not shown. Exhaust air leaves the cyclone 34 partly as ventilation air 36, through which moisture dried out of the fiber material is removed on the way from the drying, not shown, to the cyclone 34. Exhaust air from the cyclone 34 is also used for the air flow 32 via an air supply line 37.

The gluing device also has a fiber sifter unit 40. The shaft section 20 opens directly into an inlet opening 41 of the transport shaft 11. Adjacent to the inlet opening 41 and opposite from the outlet opening 23 is an inlet 42 of a coarse material discharge chute. 43 arranged. The coarse material discharge shaft 43 extends in the vertical direction and has a coarse material discharge 44 having a screw at its lower end. Air supply openings 45 are arranged above the coarse material discharge 44. An adjustment flap 46 delimits the inlet 42 of the coarse material discharge chute 43 on the upper side. Reference number 47 indicates a flange of the fiber sifter unit 40.

1 is based on the following mode of operation: the fact that the fiber stream 13 in the region of the outlet opening 14 of the feed chute 9 meets the fiber roller 15 rotating at high speed and the pins 16 have a speed component perpendicular to the direction of movement of the fiber stream 13, contiguous or clumped fibers are separated from one another, individual fibers being hardly damaged by the fiber roller 15.

Furthermore, the fibers are deflected into the shaft section 20 by the fiber roller 15. In the first part of the shaft section 20, due to the inertia of the fibers, in addition to combing through the fibers and the associated disintegration of fiber lumps, the fibers are accelerated to approximately the peripheral speed of the fiber roller 15. This fiber speed is reached in this gluing device approximately after a quarter of the circumference of the fiber roller 15. In this area of the shaft section 20, the fibers in a fiber stream 50 are stretched to a multiple of the fiber stream 13 in the feed shaft 9. Due to the large number of conical pins 16, an air flow is generated in the shaft section 20 which corresponds approximately to the peripheral speed of the fiber roller 15. Due to the radial forces of air and fibers, the fibers in the shaft section 20 centrifugally outward and lie against an inside of the wall 19 of the shaft section 20, so that the conical pins 16 of the fiber roller 15 to about a quarter of the circumference of the fiber roller 15 are no longer in contact with the fibers in the shaft section 20. The fibers of the fiber stream 50 are directed into the inlet opening 41 of the transport shaft 11 via the flap 23 and the air stream 32, insofar as the fibers are normal material 51. In this case, the fibers enter the transport shaft 11 essentially adjacent to the wall of the transport shaft 11 opposite the fiber classifier unit 40.

Coarse material 52, which is heavier than the normal material 51 consisting of average heavy individual fibers, describes a longer throwing parabola due to the higher kinetic energy and thereby gets into the coarse material discharge shaft 43. Due to a small air flow prevailing in the coarse material discharge shaft 43, fiber particles which are in the Boundary range between light and heavy, lifted back out of the coarse material discharge shaft 43 into the air flow 32. Heavy parts of the coarse material 52, on the other hand, fall into the coarse material discharge 44. The flap 46 is adjustable in its angle and is used to adjust the speed and the direction of the air flow 32 in the area of the inlet opening 41 of the transport shaft 11 or the inlet 42 of the coarse material discharge shaft 43 in this way, the throwing parabola of the fiber stream after exiting the shaft section 20 can be influenced.

The normal material 51 moves as a fiber stream 53 along an outer, larger radius wall section 54 of the first semicircular section 25. Due to the centrifugal force existing in the first semicircular section 25, the fiber stream 53 is compressed into a millimeter-thin fiber film 55 closed in the surface. This condition is reached at the usual air speeds in the gluing device after approximately 90 ° of the first semicircular section 25. After preferably 180 °, the fiber film is guided over the first guide plate 27 and thereby lifted off the outer wall section 54. Immediately after the first guide plate 27, the fibers are glued by means of the first glue spray nozzles 28 before they come with their unglued side to an outer wall section 54a of the second semicircular section 26 and are subsequently pressed against the outer wall section 54a as a fiber film. After approximately 180 ° curvature of the second semicircular section 26, the gluing takes place the other side of the fiber stream by means of the second guide plate 27a and the second glue spray nozzles 28a in a manner corresponding to that previously the gluing of the first side of the fiber stream. The fresh air supply 30 and 30a, on the one hand, ensures the replacement of the vented ventilation air 36 and, on the other hand, supports the baffle 27 or 27a in its effect of guiding the fiber film to the opposite wall section of the transport shaft 11.

The flow rate of the fibers from the discharge of the dosing hopper 1 to the fiber transport line 33 can be adjusted via the adjustable slide 31.

The device according to FIG. 1 is used in the form described for gluing the fibers. However, the device can also be used without or without significant changes, e.g. apply a hardener to dry-glued fibers. Accordingly, the device can also be used to add other additives in liquid or solid form, e.g. Powder-form dye to apply to the fibers. It can also be used to apply water vapor to the fibers for heating or conditioning them. Depending on the substance to be applied, the device may have to be designed accordingly with regard to the type of nozzles through which the substance is applied.

The same features are provided with the same reference symbols in all drawing figures. The gluing device according to FIG. 2 is designed for gluing fibers in two stages. For this purpose, the gluing device has a first gluing unit 61 and a second gluing unit 62. The second gluing unit 62 corresponds to the gluing device according to FIG. 1 except for slight differences, e.g. a reversed arrangement of the fiber roller and the fiber sifter unit.

The first gluing unit 61 has a cyclone 63, to which dried fibers, as indicated by the arrow 64, are fed. The cyclone 63 is connected via a fiber transverse distribution device 65 with an inlet of a metering bunkers 66 connected. The dosing hopper 66 has a floor belt 67 with a belt scale 68 and discharge rollers 69.

Wood fibers 70 pass from the dosing hopper 66 into a feed shaft 71, which is part of a pneumatic transport device and has an air feed 72 at an upper end. A mixture of fibers and air is sucked into the feed shaft 71 by means of a fan 73, the fibers meeting in a fiber stream 74 with a fiber roller 75 which is designed and acts in accordance with the fiber roller 15 of the gluing device according to FIG. 1, in the opposite direction of rotation.

Via an angle-adjustable flap 76, the fibers pass from a shaft section 77, which corresponds to the shaft section 20 of the gluing device according to FIG. 1, into a channel section 78 of the pneumatic transport device, in that the fibers are introduced into the channel section 78 according to arrow 79 Airflow can be diverted downwards. In the area of the deflection, the fibers are glued by two rows of glue spray nozzles, one of which is shown and is designated by the reference numerals 80 and 81, respectively. The air flow led into the duct section 78 is recirculated exhaust air from a cyclone 82 of the second gluing unit 62. Ventilation air of the cyclone 82 is indicated by the reference number 84.

The fibers provided with glue reach the cyclone 82 via the channel section 78 of the pneumatic transport device. The glued fibers are separated in the cyclone 82 and fed to a metering bunker 1 via a further fiber transverse distribution device 83.

The fibers 3 arrive as fiber stream 13 from the dosing hopper 1 into a feed shaft 9 and from there onto a fiber roller 15.

As already mentioned, the further features of the second gluing unit 62 correspond to the features of the gluing device according to FIG. 1. Thus, the fibers emerging from the shaft section 20 in the Transport shaft 11 deflected with the wave-shaped section 24, with a sifting of the fibers taking place. A further gluing of the fibers takes place in the wave-shaped section 24, by means of the first guide plate 27 and the first glue spray nozzles 28 as well as the second guide plate 27a and the second glue spray nozzles 28a. Furthermore, openings for supplying heated fresh air (not shown) are also provided in accordance with FIG. 1.

In the gluing device according to FIG. 2, the fibers are glued in two stages, the second gluing stage again being divided into a gluing in the middle and a gluing at the end of the wave-shaped section 24. Such gluing in two gluing stages leads to yet another better glue distribution compared to gluing in a single gluing stage. Furthermore, this two-stage gluing can further reduce the internal contamination of the pneumatic transport device and the fiber sifter unit 40, because in each gluing stage the amount of glue applied can be reduced accordingly, thereby intensifying the drying of the glue film produced after the respective gluing stage, which is achieved again a reduction in the cold stickiness of the glue.

In the following, a calculation example for the contact surfaces of the fiber material and the glue to be applied is given in the gluing device according to FIG. 1:

fiber surface

Working width: 2 x 3 m

Fiber flow speed :: 35 m / sec

Fiber contact area per unit of time: 2 x 3 x 35 = 210 m ² / sec

The factor 2 in the calculation of the working width results from the two gluing steps in the middle and at the end of the undulating section 24. Fiber throughput dry

Fiber contact area per unit of time: 210 m ² / sec

Fiber stream thickness: 1 mm

Fiber flow density: 50 kg / m ³ fiber throughput: 105 x 0.00 '

gluing surface

With 7% solid resin based on the weight of dry fiber, glue concentrate liquid 65%, liquid glue density 1, 28 kg / l are calculated:

5.25 kg fibers x 7%

, = 0.442 I liquid glue / sec. 0.65 x 1.28 kg / 1

The glue liquid is atomized to a mean volumetric drop size of 20 μm.

Liquid glue per unit of time: 0.442 l / sec

Drop diameter: 20 μm

Drop surface: 0.001256 mm ²

Number of drops per unit of time: 105,573,416,518 / sec

Contact area glue per unit time 132 m ² / sec

This calculation example shows that the fiber contact area per unit of time is significantly larger than the glue contact area. This enables the fibers to be glued very evenly, and the glue can also be dried very quickly. In this way, internal contamination of a pneumatic transport unit or a fiber sifter unit is largely reduced.

The device according to FIG. 3 is very similar to the gluing device according to FIG. 1 and, as the essential difference, has a fiber sifter unit 90 which works with an essentially upward air flow 91. The Fibers of the fiber stream 50, which leave the shaft section 20 via the outlet opening 21, are lifted via the flap 23 and the air stream 91, insofar as the fibers are normal material 51, to an inlet opening 101 of the wavy section 24. Coarse material 52, on the other hand, is directed due to the predominant gravity into the inlet 42 of the coarse material discharge shaft 43 opposite the outlet opening 21. Due to a low air flow prevailing in the coarse material discharge shaft 43, fiber particles which lie in the border area between light and heavy are lifted back out of the coarse material discharge shaft 43 into the air flow 91. Heavy parts of the coarse material 52, on the other hand, fall into the coarse material discharge shaft 44. A cellular wheel lock 92 is arranged below the coarse material discharge shaft 44. The coarse material is discharged via a transport line which has an air supply 94 and a fan 95. Air regulating flaps 96 are attached to the inlet 42 of the coarse material discharge chute 43. Air regulating flaps 97 are likewise arranged at an outlet opening 98 of the air supply line 37.

The fibers 3 enter the metering bunker 1 via a shaft 85 with a fiber transverse distribution device in the form of a cellular wheel sluice 86 and an electromagnet 87, which is used to separate metal parts from the fiber stream indicated by an arrow 88. A stripping rake 89 guides incoming fibers a rear part of the dosing bunker 1. From the discharge rollers 5 arranged at the front end of the dosing bunker 1, the fibers 3 reach a disc separator 105, which separates coarse particles and leads into a further coarse material discharge 106.

A flap 99 is arranged at the entry opening 101 of the wave-shaped section 24, which leads the fibers 51, which reach the transport shaft 11 from the fiber sifter unit 90, to the outer wall section 54 of the first semicircular section 25. The flap 99 also serves to be able to set an opening 100 for the supply of fresh air. The strength of the ascending air flow 91 in the fiber sifter unit 90 can be regulated via this variable fresh air opening 100. A substructure of the device is designated by reference number 107.

The fibers, which are provided with a hardener by means of the device according to FIG. 3, have previously been glued dry in a gluing device. After the hardener has been applied, the fibers can be fed to a molding machine and then to a press.

Claims

EXPECTATIONS Method for applying a substance to dried fibers intended for the production of fiberboard, comprising the following steps: (a) The fibers are fed from a metering device (1) through a feed shaft (9) pressurized with vacuum to a fiber roller (15) which is provided with a plurality of pins (16) on its surface and rotates in such a way that (b) the fibers are deflected by the pins (16), guided along a shaft section (20) delimited by a partial section (18) of the circumference of the fiber roller (15) and an opposite wall (19) and by the pins (16 ) and an air flow generated by this is accelerated to approximately the peripheral speed of the fiber roller (15), (c) and the fibers emerge at an outlet opening (21) of the shaft section (20), characterized by the steps: (d) the fibers pass from the outlet opening (21) of the shaft section (20) in a pneumatic transport shaft (11) with a wave-curve-like section (24), which has a first curved section (25) and an oppositely curved second curved section (26), (e) the fibers are pressed against an outer wall section (54) of the first arc section (25) due to the centrifugal force, (f) the fibers are passed through a first guide plate (27) which is in a transition area from the first (25) to the second arc section (26) arranged and inclined like a ramp, directed to an opposite wall section (54a) of the transport shaft (11), (g) the fibers are provided with the material after leaving the first guide plate (27) by means of at least one first nozzle (28), (h) the fibers are pressed against an outer wall section (54a) of the second arch section (26), (i) the fibers are directed through a second guide plate (27a) to an opposite wall section of the transport shaft (11), (j) the fibers are provided with the material after leaving the second guide plate (27a) by means of at least one second nozzle (28a). 2. The method according to claim 1, characterized in that the substance is one or more substances from the group of glue, hardener, dye and water vapor. 3. The method according to claim 1 or 2, characterized in that the wave curve-like section (24) is composed of the first curved section (25) and the second curved section (26) adjoining it. 4. The method according to any one of the preceding claims, characterized in that the wave curve-like section (24) is shaped like a sine curve. 5. The method according to any one of claims 1 to 3, characterized in that the two arc sections (25, 26) are essentially semicircular. 6. The method according to any one of the preceding claims, characterized in that the fibers at the outlet opening (21) of the shaft section (20) emerge essentially horizontally and the fibers are subsequently sifted by a downward or upward air flow (32) of the pneumatic transport shaft generated by the vacuum onto the fibers is exercised, the normal good (51) Fibers are deflected into the transport shaft (11), while impurities in the form of coarse material (52) are deflected into a coarse material discharge (44). 7. The method according to any one of the preceding claims, characterized in that the air speed in the transport shaft (1 1) is selected such that the fibers, approximately in the form of a fiber film (55), essentially against the outer wall section (54) of the first sheet section, in the form of a fiber film (55) (25) press. 8. The method according to any one of the preceding claims, characterized in that the second guide plate (27a) is arranged in the region of the end of the second curved section (26). 9. The method according to any one of the preceding claims, characterized in that the nozzles are spray nozzles (28, 28a). 10. The method according to any one of the preceding claims, characterized in that warm air is used as the transport air in the transport shaft (11), which is partly exhaust air (37) recirculated from a cyclone (34) and partly fresh air (30, 30a), which is preferably heated. 11. The method according to claim 10, characterized in that the fresh air (30, 30a) is blown in through openings (29, 29a) of the transport shaft (11) which are arranged in the transport direction adjacent to the at least one first (28) and the at least one second nozzle (28a) are. 12. The method according to any one of the preceding claims, characterized in that the flow speed of the transport air in the transport shaft (11) is set as a function of a gravimetric fiber throughput determination. 13. The method according to any one of the preceding claims, characterized in that the transport shaft (11) has a plurality of successively arranged wave curve-like sections (24) and the fibers in each of the wave curve-like sections (24) are partially provided with the fabric. 14. Device for applying a substance to dried fibers intended for the production of fiberboard, in which, below a discharge (5) of a fiber metering device (1), a feed shaft (9) which can be subjected to negative pressure extends from the discharge (5) to a fiber roller (15) which has a plurality of pins (16) on its surface and so rotatable that fibers striking the fiber roller (15) are deflected by the pins (16), are guided along a shaft section (20) delimited by a partial section (18) of the circumference of the fiber roll (15) and an opposite wall (19), which section extends from an outlet opening (14) of the feed shaft (9) in the direction of rotation (17) of the fiber roll (15) extends and is provided with an outlet opening (21) for the fibers, and are accelerated to approximately the peripheral speed of the fiber roller (15) by the pins (16) and an air flow generated thereby, characterized in that a pneumatic transport shaft (11) with a wave-curve-like section (24), which has a first curved section (25) and an oppositely curved second curved section (26), is arranged such that the fibers extend from the outlet opening (21) of the Shaft section (20) get into the wave curve-like section (24), wherein an air flow generated by negative pressure is provided in the pneumatic transport shaft (11) and acts on the fibers in such a way that they are pressed against an outer wall section (54) of the first curved section (25), a first guide plate (27) inclined like a ramp is arranged in a transition region from the first (25) to the second curved section (26) in such a way that it guides the fibers to an opposite wall section (54a) of the transport shaft (11), at least one first nozzle (28) is arranged adjacent to the first guide plate (27) in the transport direction, a second guide plate (27a) is arranged on an outer wall section (54a) of the second arch section (26) in such a way that it directs the fibers pressed against the outer wall section (54a) to an opposite wall section of the transport shaft (11), and at least one second nozzle (28a) is arranged adjacent to the second guide plate (27a) in the transport direction. 15. The apparatus according to claim 14, characterized in that the substance is one or more substances from the group of glue, hardener, dye and water vapor. 16. The apparatus of claim 14 or 15, characterized in that the wave curve-like section (24) is composed of the first arc section (25) and the second arc section (26) adjoining this. 17. The device according to one of claims 14 to 16, characterized in that the wave curve-like section (24) is shaped like a sine curve. 18. Device according to one of claims 14 to 16, characterized in that the two arc sections (25, 26) are essentially semicircular. 19. Device according to one of claims 14 to 18, characterized in that the outlet opening (21) of the shaft section (20) is arranged such that the fibers are substantially horizontal in a downward or upward direction generated by negative pressure Air flow from the pneumatic transport shaft (11) emerges, a coarse material discharge shaft (43) having an inlet (42) lying in the direction of throw of the fiber roller (15) and a coarse material discharge (44) arranged below the inlet (42) with the transport shaft (11 ) connected is. 20. Device according to one of claims 14 to 19, characterized in that the second guide plate (27a) is arranged in the region of the end of the second curved section (26). 21. The device according to one of claims 14 to 20, characterized in that the first (27) and the second guide plate (27a) are adjustable in angle. 22. The device according to one of claims 14 to 21, characterized in that the transport shaft (11) is rectangular in cross section. 23. The device according to one of claims 14 to 22, characterized in that the nozzles are spray nozzles (28, 28a). 24. The device according to one of claims 14 to 23, characterized in that an opening (29, 29a) for introducing fresh air is arranged adjacent to the at least one first (28) and the at least one second nozzle (28a) in the transport direction. 25. The device according to one of claims 14 to 24, characterized in that the transport shaft (11) for generating the negative pressure is connected to a fan (12) and in the transport shaft (11) a controllable slide (31) is arranged, by means of which the flow velocity of the fibers in the transport shaft (11) is adjusted can be. 26. The device according to one of claims 14 to 25, characterized in that the wave-curve-like section (24) of the transport shaft (11) is followed by at least one further wave-curve-like section which has further means for gluing and / or means for spraying additives and / or water vapor onto the fibers.