WO2001089783A1

WO2001089783A1 - Method and device for disintegrating irregularities in streams of wood fibres

Info

Publication number: WO2001089783A1
Application number: PCT/EP2001/005729
Authority: WO
Inventors: Fritz Schneider
Original assignee: Flakeboard Company Limited
Priority date: 2000-05-24
Filing date: 2001-05-18
Publication date: 2001-11-29
Also published as: DE10025177A1; DE10025177B4; CA2411051A1; CA2411051C; EP1283766B1; AU2001267458A1; DE50106979D1; PL365953A1; ATE301029T1; EP1283766A1

Abstract

Wood fibres (2) which are used in the production of fibreboard are supplied from a metering device (1) through a supply chute (7) to a disintegration roller (12) comprising a large number of spikes (13) on its surface. The disintegration roller (12) rotates at high speed, in such a way that the spikes (13) deflect the fibres (6) hitting the disintegration roller (12). The fibres are entrained (6) by the spikes (13) and fed through a chute section (17) formed by a subsection (15) of the roller periphery and a wall (16) lying opposite the latter, to an outlet opening (18) of the chute section. Either a moulding belt (19) of a moulding machine is located beneath the outlet opening (18), or the fibres (6) pass from the outlet opening (18) into the air channel of an air fibre-separator. The disintegration roller (12) disintegrates irregularities in a fibre stream (6), e.g. fibre bundles, or drops of condensed water.

Description

DESCRIPTION

Method and device for resolving non-uniformities in wood fiber streams

The invention relates to methods and devices for resolving non-uniformities in a stream of wood fibers discharged from a metering device provided for the production of fiberboard.

If the gluing of the fibers takes place in the wet state of the fibers in the production of MDF or HDF boards, the consumption of glue is relatively high because part of the reactivity of the glue is lost during the drying process of the fibers due to the high temperatures. For example, in the dryer system, the emission of formaldehyde resulting from the glue is considerable, which means that it is necessary to minimize pollutants.

If the fibers are glued only after the drying process in gluing machines, the glue consumption and the emission of formaldehyde can be reduced, but this so-called "dry gluing" or "mechanical gluing" results in fiber bundles, condensation water drops or glue lumps in the fiber stream. These non-uniformities in the fiber flow, which also occur to a lesser extent with wet gluing, lead to defects in the finished board and can therefore lead to rejects.

In order to cover up these defects, it is known to glue the fibers of outer layers of fiberboard to be produced in the wet state and fibers of the inner layers in the dry state. However, this makes the production of fiberboard expensive.

Furthermore, it is known from practice to use a hammer mill in order to form lumps of fiber which are formed, for example, due to condensed water have to dissolve. However, such a hammer mill gets dirty quickly and is not very effective.

Rollers which can serve to resolve irregularities in a fiber stream are known per se from DE 38 18 117 A1, DE 44 39 653 A1 and WO 99/11441. However, the effectiveness of these rollers in resolving non-uniformities is limited.

EP 0 800 901 A1 describes a device for producing a nonwoven from, in particular, chips, in which rollers are provided which, in conjunction with a downstream air classifier, serve to separate the chips depending on their size in order to provide a size distribution over the thickness of the nonwoven achieve. In the case of grit in the form of fibers, such rolls cannot achieve a satisfactory dissolving effect. A separation of the fibers into different particle sizes is not at all desirable in fiber boards because of the desired homogeneity in the structure.

DE 43 02 850 C2 describes a generic method or a generic device. Spreading material compaction is resolved by two rollers rotating in opposite directions at different speeds, which have interlocking teeth that form a meandering gap. A plurality of downstream spreader rollers are provided for scattering the fibers. However, this process is very complex.

The invention has for its object to provide a generic method that is very effective and inexpensive. Furthermore, the invention has for its object to provide a generic device with which such a method can be carried out.

With regard to the method, the object is achieved by the features of claim 1. The fibers, which can be dry-glued fibers in particular, are fed by the metering device, which in particular which can be a dosing hopper, fed through a feed shaft to an opening roller, which is provided with a large number of pins on its surface and rotates so that the fibers are deflected by the pins. As a result, the fibers are guided essentially along a shaft section delimited by a partial section of the circumference of the opening roller and an opposite wall, before they exit at an outlet opening of the shaft section. After exiting the outlet opening of the shaft section, the fibers arrive on a forming belt of a molding machine, in which the fibers are formed into a nonwoven. The forming belt is a wire belt through which the fibers are sucked in towards the surface of the forming belt.

The opening roller rotates at high speed. Due to its shape, shaft depth and shaft length, the shaft section is preferably suitable for bringing the fiber flow to approximately the circumferential speed of the opening roller after an initial action of the pins on the fibers in the further course before reaching the outlet opening by the air flow generated in the shaft section, the Fibers lie against the wall of the shaft section. The dissolved fibers emerge from the shaft section in the form of a thin fiber stream, preferably pulled apart to form a millimeter-thin film, and then reach a scattering space, where they are built up with elements of the molding machine to form a litter mat or a fleece.

In practice it has been shown that the fibers after they hit the opening roller are already out of the effective range of the pins after a quarter of the roller circumference due to the radial force which acts on the fibers due to the rotation, and then contact the wall of the shaft section invest. For the remaining distance of the shaft section, the fibers are transported by the air stream, which is also rotated by the roller and moved to the outlet opening of the shaft section. The wall of the shaft section preferably has a smooth surface on its side opposite the opening roller. Fiber bundles and drops of condensed water are very effectively dissolved in the fiber stream by the deflection of the fiber stream or the contact with the rapidly rotating pins. Even the very hard lumps of glue are dissolved to a certain extent. At the outlet of the

A homogenized fiber stream therefore emerges through the shaft section, through which the fibers are scattered onto the forming belt. With the very effectively reduced number of non-uniformities in the fiber stream and the associated avoidance of streaks and stains of different bulk density in fiber boards produced from the fiber stream, the waste of fiber boards is also considerably reduced and the technological properties of the end product, in particular the surface quality, are improved. In particular, the above-mentioned disadvantages of the glue-saving and low-emission dry gluing in the production of fiberboard can be eliminated or reduced with respect to the glue lumps with the method according to the invention. Furthermore, as described, the method also serves in particular to scatter the fibers into a fleece on the forming belt of the molding machine.

An exit direction of the fiber stream can be provided which is horizontal or is inclined somewhat upwards, that is to say in the direction of the metering device.

When exiting the shaft section, the fibers can be passed through a profile with nail-like elevations, which is arranged across the width of the outlet opening. In the following, the profile with nail-like elevations is referred to as a comb strip. The comb strip causes a further resolution of irregularities in the fiber material and thus an increased degree of fineness of the fiber material in accordance with the respective structure of the comb strip. After passing through the comb bar, which represents the second stage of fiber dissolution, an even better homogenized fiber stream emerges from the shaft section.

The nail-like elevations of the comb strip are preferably adjustable at an angle to the direction of flow of the fibers. In particular, there has been an angle of 135 ° between the nail-like elevations and the flow direction of the impinging fibers proved to be very advantageous. However, it is also possible, for example, to arrange the elevations perpendicular to the direction of flow.

In particular in the preferred angular position of 135 ° of the comb strip, the fibers are directed obliquely upwards in the direction of the pins of the opening roller. In this way, the fibers reach the area of action of the pins again and are therefore subjected to a further process for resolving non-uniformities.

Basically, the fibers are braked when they hit the nail-like elevations, as a result of which, even when the comb strip is arranged vertically, swirling takes place, which can bring the fibers back into the effective range of the pins of the dissolving roller. The nail-like elevations can be arranged in several rows, also offset from one another.

The weight distribution of the fibers can be adjusted over the width by means of a suction strength that can be adjusted over the width of the belt. The suction process also accelerates the fibers discharged from the metering device in addition to the gravitational force in the direction of the opening roller. This increases the effectiveness of the opening roller with regard to the resolution of irregularities in the fiber stream. The speed at which the fibers move in the feed shaft towards the opening roller can preferably be adjusted by changing the cross section of the feed shaft and the suction strength.

Underneath the outlet opening of the shaft section, an air flow generated by the suction process with a speed component directed parallel to the forming belt can be provided, which ensures that the fibers roll as little as possible when they hit the forming belt, ie assume the speed of the forming belt as quickly as possible. This can help to arrange the outlet opening of the shaft section in such a way that it ejects the fibers essentially parallel to the forming belt.

With regard to the method, the object is also achieved by the features of claim 8, the fibers being fed from the outlet opening of the shaft section to an air-fiber sifting. The fibers exit the chute section substantially horizontally and enter an upward air flow generated by negative pressure. The air flow entrains fibers that are isolated as desired and thus have a relatively low weight as particles, while impurities in the form of coarse material are fed to a coarse material discharge by the force of gravity. The coarse material can be directed vertically downwards to the coarse material discharge by means of an angle-adjustable flap. According to claim 10, instead of the upward airflow, a downward airflow can be provided, which is directed against the direction of rotation of the opening roller. In this case, an adjustable deflector can be arranged so that the coarse material is rejected into the coarse material discharge shaft.

Fibers which have an above-average weight and are not removed directly by the upward air flow are preferably lifted into the air flow in a post-sifter upstream of the coarse material discharge by an additional upward post-air flow generated by negative pressure.

In air-fiber sifting, the action of the opening roller, in addition to dissolving impurities, accelerates and thus pulls the fiber stream apart, thereby improving the sifting effect. The fiber stream is drawn apart into a thin film. Furthermore, heavy particles are mechanically pre-separated from the fiber stream before it reaches the air flow of the fiber sifting. The pre-separation takes place due to the different throwing parabolas of heavy and light particles. The heavy particles include in particular also lumps of glue and glue batches that were not broken up by the opening roller due to their great hardness.

In both methods according to the invention, additives can also be supplied to the fibers in the feed shaft via nozzles. The opening roller then has not only the function of opening but also of mixing.

The opening roller, whose speed is preferably adjustable, rotates quickly, e.g. at about 300 to 2000 rpm. It preferably has a diameter of 500 to 600 mm and rotates at 300 to 2000 rpm.

In particular, it can be provided that the fibers are first subjected to a dissolution and air-fiber screening according to claim 8 or 10 using a corresponding dissolving device according to the invention and then after a pneumatic transport according to claim 1 via a metering device for forming a fleece of another corresponding dissolving device according to the invention with integrated Forming machine are fed. The air-fiber screening in particular lumps of glue, glue batches and coarse wood particles (so-called "shiwes"), which arise during fiber production, are pulled out of the fiber stream. A part of the remaining heavy parts that have passed through the air-fiber screening, in particular fiber clumps, which are in transit from the air-fiber sifting to the dosing bunker discharge of the further disintegration device according to the invention with an integrated molding machine, is disintegrated by means of this further disintegration device.

The outlet opening of the shaft section can be arranged in such a way that it ejects the fibers essentially horizontally and thus parallel to the forming belt and further in the direction of movement of the forming belt, and thereby residual heavy parts that have passed through the air-fiber sifting by a mechanical separation effect, which also the Opening roller of the opening Direction with integrated molding machine, are transported in the molding machine in the nonwoven structure in an upper layer of the nonwoven fabric. The upper layer of the nonwoven, approx. 25% of the total nonwoven height, is preferably combed by a scalping roller connected downstream and fed via pneumatic transport to a process at the start of the air-fiber screening, preferably into a dosing hopper within the air-fiber screening. This means that partial rechecking takes place based on the first fiber sifting.

The object is achieved in relation to the device by the features of claim 12. Below a discharge of the metering device, a feed shaft extends from the discharge to an opening roller, which has a large number of pins on its surface and can be rotated in such a way that fibers striking the opening roller are deflected by the pins. A shaft section, which is delimited by a partial section of the roller circumference and an opposite wall, extends from an outlet opening of the feed shaft in the direction of rotation of the opening roller.

A shaping belt is arranged below the outlet opening of the shaft section, preferably at a distance of 200 to 500 mm, in particular of 220 to 280 mm. The forming belt is a sieve belt, under which vacuum boxes are arranged in order to suck in the fibers towards the surface of the forming belt, preferably for influencing the basis weight distribution with adjustable thickness.

The device has essentially the same advantages as previously mentioned in connection with the method according to claim 1. Due to the rotary movement of the opening roller, the fibers are accelerated to a thin, preferably millimeter-thin, fiber stream which moves at high speed towards the outlet opening of the shaft section, the fiber stream being guided through the wall of the shaft section until it is ejected from the outlet opening. A comb strip with at least one row of nail-like elevations is preferably arranged at the outlet opening of the shaft section over the working width of the shaft section. The length of the nail-like elevations is selected such that the entire fiber stream must pass the comb strip before it emerges from the outlet opening of the shaft section. As described above, this causes the fiber material to dissolve further.

The degree of fineness of the comb strip can be varied by an appropriate choice of the thickness of the nail-like elevations and the number of these elevations.

The comb strip can be designed and arranged in such a way that, in addition to the fiber disintegration caused by the impact of the fibers on the nail-like elevations, the direction of the fiber stream is simultaneously changed. This change of direction takes place in such a way that the fibers, which have moved away from the area of action of the pins after a partial distance of the slot section due to the centrifugal force of the rotational movement, are returned to the area of action of the pins.

As a result of the braking effect on the fibers due to the friction on the comb strip, the fibers after the comb strip are caught and overhauled by the pins of the rotating opening roller in the direction of flow and subjected to a further dissolution during the ejection from the outlet opening of the shaft section.

With this opening device, a device is created which, with only a single rotating roller with attached pins and a shaft section with an integrated comb strip at its outlet opening, first dissolves the fiber material in at least two stages of different degrees of fineness, then finely and at the same time has the property in connection with the suction air of the vacuum boxes and the sieve belt to form a homogeneous fiber fleece with a constant basis weight. A supply opening for an air stream with a speed component directed parallel to the forming belt can be provided between the outlet opening of the shaft section and the forming belt. The small distance of the outlet opening of the shaft section from the forming belt and the air flow directed parallel to this prevent the fibers from hitting the forming belt at a relatively high speed.

The vertical extent of the air flow supply opening can be changed over the width of the forming belt by several independently height-adjustable sheets in order to be able to set a certain air supply symmetry and in this way to be able to influence the laying height of the fibers across the width of the forming belt.

A guide wall, which adjoins the shaft section opposite the outlet opening of the feed shaft and can extend into a section running parallel to the forming belt, also results in a suction effect of the vacuum below the sieve belt on the fibers located in the feed shaft. It proves to be advantageous for the flow conditions if a nose directed towards the opening roller is formed at the transition point of a feed shaft wall to the guide wall, which nose only forms a narrow passage for the fibers on the section of the opening roller opposite the shaft section. Furthermore, the cross section of the feed chute can be changeable so as to be able to influence the speed of the fibers along the feed chute.

The speed of the fibers in the feed chute in relation to the peripheral speed of the rotating opening roller determines the depth of penetration of the fibers into the opening roller before they are gripped and deflected by the pins. The speed of the fibers in the feed chute thus determines the efficiency of the fiber dissolution and at the same time the fiber acceleration. With regard to the device, the object is also achieved by the features of claims 21 and 23, respectively. Accordingly, a disintegration device with an integrated air-fiber sifter is provided, in which the above-described outlet opening of the shaft section is arranged in such a way that the fibers emerge essentially horizontally into an air channel which passes through

Vacuum generated, upward or downward air flow leads, wherein a coarse material discharge shaft, which has an inlet opposite the outlet opening of the shaft section and a coarse material discharge arranged below the inlet, is connected to the air duct. The fiber flow is caused by the opening roller

Acceleration pulled apart, which improves the visual effect. The speed of the opening roller is preferably adjustable. As a result, the speed at which the fibers are ejected from the shaft section can be varied, which influences the throwing parabola, in particular of the large parts which are to get into the coarse material shaft during the viewing process.

When the air flow is directed upwards, an angle-adjustable flap can be arranged at the inlet of the coarse material discharge shaft in such a way that the coarse material is deflected into the coarse material discharge shaft. When the air flow is directed downwards, an adjustable deflector can be arranged in such a way that the coarse material is deflected into the coarse material discharge shaft.

A comb strip is not provided for the opening devices with an integrated air-fiber sifter, since braking of the fiber stream caused by this is not desired.

The coarse material discharge chute preferably has at least one air supply opening in a lower region, through which an upward air flow is generated by the negative pressure applied to the air duct for indulgence in fibers of above-average weight.

In all of the devices according to the invention, it is preferably provided that the pins of the opening roller move away from the roller with increasing distance. taper the axis of rotation. The wall of the shaft section can in particular be formed by a hood which can be fed to the opening roller, so that the distance of the wall from the outer ends of the pins is variable. The distance is relatively small, so that the fiber stream starting from the outlet opening of the feed shaft in a first section of the

Manhole section is kept in the effective area of the opening roller. In the further course of the shaft section, after the first stage of fiber dissolution has taken place, the fiber stream emerges from the effective area of the dissolving pins due to the centrifugal force of the rotational movement in the shaft section and lies against the wall of the shaft section. To protect the opening roller, electromagnets or permanent magnets for pulling metal parts out of the fiber stream can be installed in the feed shaft.

A series of nozzles can be arranged in the feed chute, via which additives such as e.g. Water, superheated steam, accelerator or retarder are added.

As explained for the method, in particular an opening device with an air fiber classifier and a opening device with a molding machine can be arranged one behind the other.

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 partial view of an opening device with an integrated molding machine,

2a schematically shows a partial view of an opening device for mechanical pre-separation of heavy parts with an integrated air-fiber classifier with an upward air flow, 2b schematically shows a partial view of an opening device for the mechanical pre-separation of heavy parts with an integrated air-fiber sifter with a downward air flow,

3 schematically shows a partial side view of the outlet opening 18 of the opening device according to FIGS. 1 and

FIG. 4 schematically shows a partial view of the outlet opening according to FIG. 3 in a top view.

1 could also be referred to as a molding machine with an integrated opening device and the opening devices according to FIGS. 2a and 2b as an air-fiber classifier with an integrated opening device.

1 has a dosing hopper 1, which contains dry-glued wood fibers 2. In the upper area of the dosing bunker 1 there is a row of feed rollers 3 which serve to distribute the fibers fed through a dosing bunker inlet (not shown) in the dosing bunker 1. The fibers 2 are discharged from the dosing hopper 1 by means of a dosing belt 4 and a row of discharge rollers 5 arranged on the front. At the same time 5 larger clumps of the fibers 2 are dissolved by the discharge rollers.

The fibers 2 fall from the dosing hopper 1 as a fiber stream 6 into a feed shaft 7 which is delimited by two mold walls 8 and 9. At the upper end of the feed shaft 7 there is a first air feed opening 10. Furthermore, a row of nozzles 30 is arranged on the mold wall 9 across the width of the fiber stream 6, via which additives 31 can be sprayed onto the fibers of the fiber stream 6.

In the region of an outlet opening 11 of the feed shaft 7, the fiber stream 6 meets a disintegration roller 12, on the surface of which a large number of pins 13 are arranged, which become larger as the distance to the axis of rotation increases Taper opening roller 12 to a tip. The opening roller 12 has a diameter of 550 mm and rotates in the direction of rotation indicated by the arrow 14 at about 1000 rpm. The speed of the opening roller 12 can be regulated so that it can adapt to different materials to be opened. A total of approximately 6000 pins are arranged on the opening roller 12, which is designed for a process width of 1500 mm.

A partial section 15 of the opening roller circumference and a wall 16 formed by a hood that can be advanced to the opening roller 12 delimit a shaft section 17 which extends approximately from the outlet opening 11 of the feed shaft 7 to the lowest point of the opening roller 12 and has an outlet opening 18 there. The direction of movement of the hood is indicated by arrow 29.

Arranged at the outlet opening 18 is a comb strip 34 which has conical teeth 53 which can be adjusted at an angle to the direction of flow of the fibers. The teeth 53 are arranged in two mutually offset rows, each over the working width of the shaft section 17, as can be seen in particular from FIGS. 3 and 4. The teeth 53 are oriented perpendicular to the direction of flow of the fibers in FIG. 1 and inclined in FIGS. 3 and 4 such that they form an angle of approximately 135 ° with the impinging fiber stream.

Below the outlet opening 18 of the shaft section 16 there is arranged a forming belt 19 designed as a sieve belt. On the underside of the forming belt 19 there is a row of vacuum boxes 20, via which a negative pressure indicated by the arrow 27 is generated on the forming belt 19. A slide 32 is arranged on each vacuum box 20 for adjusting the amount of air extracted. Between the outlet opening 18 of the shaft section 17 and the forming belt 19 there is a second air supply opening 21. The vertical extension of the second air supply opening 21 is across the width of the forming band 19 by a plurality of independently height-adjustable sheets, one of which is shown in FIG. 1 and with which loading Zugszeichen 35 is provided for changing a certain air supply symmetry. For the sake of simplicity, the sheets 35 are not shown in FIGS. 3 and 4.

A guide wall 22 adjoins the mold wall 8 of the feed chute 7 and approaches the mold belt 19 at a predetermined distance. Where the mold wall 8 merges into the guide wall 22, a nose 23 is designed such that the passage between the mold wall 8 or the guide wall 22 and the opening roller 12 is the least. By means of an adjusting spindle 33, the mold wall 8 can be moved transversely to the feed chute 7 in order to adjust its cross section or the speed of the fiber stream 6 and the air flowing through the feed chute 7.

A scalping roller 24 is arranged above the forming belt 19. The direction of movement of the forming belt 19 is indicated by the arrow 25.

Because the fiber stream 6 meets the opening roller 12 rotating at high speed at the outlet opening 11 of the feed shaft 7 and the pins 13 have a speed component that is perpendicular to the direction of movement of the fiber stream 6, cohesive or clumped fibers are separated from one another and clumps of glue and condensation water are dissolved , Individual fibers are hardly damaged by the opening roller 12. In the shaft section 17, the fibers are initially held in the effective area of the opening roller 12 by the wall 16. Due to its shape, shaft depth and shaft length, the shaft section 17 is suitable for bringing the fiber flow to approximately the circumferential speed of the opening roller 12 in the further course before reaching the outlet opening by the air flow generated in the shaft section 17.

In this way, the fibers are moved to the outlet opening 18, where they are braked by the conical teeth 53 and brought in the direction of the pins 13 and thus again into the effective range of the opening roller 12. Since after the braking of the fibers, the pins 13 move faster than that Fibers, the pins 13 again resolve non-uniformities in the fiber stream.

Due to the arrangement of the outlet opening 18 at the lowest point of the opening roller 12 and the air directed through the second air supply opening 21 parallel to the forming belt 19, the fibers are brought onto the forming belt 19 without a rolling effect due to the fibers hitting the forming belt 19 too large a speed difference between the fibers and the forming belt 19 occurs. The outlet opening 18 of the shaft section 17 is arranged in such a way that, under the action of the air flow described below and indicated by arrow 28, the fibers reach the forming belt essentially with a movement component parallel to the latter. As a result, residual heavy parts that have an upstream air-fiber classifier, e.g. 2a or 2b, have passed through a mechanical separation effect of the opening roller 12 of the molding machine during the nonwoven construction into an upper layer of the nonwoven fabric. The upper layer of the nonwoven, approx. 25% of the total nonwoven height, is combed by the scalping roller 24 connected downstream and can be fed into a dosing hopper of the upstream air-fiber sifter via pneumatic transport. By means of the height-adjustable sheets 35 of the second air supply opening 21, the laying height of the fibers can be influenced over the width of the forming belt 19. The air drawn in through the two air supply openings 10 and 21 can be conditioned and warmed in order to accelerate a later pressing process.

Fibers 26 that have reached the forming belt 19 are sucked to the surface of the forming belt 19 by the vacuum generated below the forming belt 19. The nose 23 ensures that only a very small amount of fibers from the fiber stream 6 does not pass through the shaft section 17 but along the mold wall 8 and the guide wall 22 to the mold belt 19. The passage between the nose 23 and the opening roller 12 is large enough, however, as indicated by the arrow 28, to allow air concentrating on the mold wall 8 to pass from the feed shaft 7 to the mold belt 19. sen, whereby the fiber stream 6, in addition to the gravitational force, experiences a suction effect from the vacuum applied below the forming belt 19. In this way, the effectiveness of the opening roller 12 is increased. In order to achieve increased guidance of the air along the mold wall 8 and the fibers 6 along the mold wall 9, the mold walls 8 and 9 can also be slightly inclined, for example by 15 °.

The scalping roller 24 ensures that a nonwoven fabric formed on the forming belt 19 by the fibers 26 is kept constant in a predetermined nonwoven weight, so that a fiberboard with a weight that is as uniform as possible is obtained in the pressing process that follows the shaping. Further tasks of the scalping roller 24 are the production of a flat nonwoven surface and, as already mentioned, the combing of the top layer of the nonwoven which may still have residual impurities.

In the case of the opening devices with an integrated air-fiber classifier according to FIGS. 2a and 2b, components which correspond to components of the opening device according to FIG. 1 are identified by the same reference numerals. The opening device according to FIG. 2a also has a dosing hopper 1 with wood fibers (not shown). The wood fibers have been fed to the dosing hopper 1 either from a dryer (not shown) via a first inlet opening 36 or as return material from a scaling roller (not shown) and a side trimming (not shown) of a molding machine via a second inlet opening 37. Via discharge rollers 5, the fibers are in turn fed as a fiber stream 6 into a feed shaft 7 which is delimited by two mold walls 8 and 9 and at the upper end of which there is a first air feed opening 10.

An outlet opening 18 of a shaft section 17 opens into an air duct 38 of the fiber sifter. The air duct 38 has a lower duct section 39 and an upper duct section 40. Via the lower channel section 39 is used to generate an air flow indicated by the arrows 51 and 52 Air supplied, the amount of which can be regulated via an air supply slide 41. In the lower channel section 39, in the area where the coarse material inspection takes place, an adjustment flap 42 is also arranged, which serves to adjust the direction of flow and at the same time the flow velocity of the supplied air. At an upper end of the upper channel section 40, for example, a negative pressure is generated via a fan, not shown.

An inlet 43 of a coarse material discharge shaft 44 is arranged opposite the outlet opening 18 of the shaft section 17. The coarse material discharge shaft 44 extends in the vertical direction and has a coarse material discharge 45 at its lower end. Third air supply openings 46 are arranged above the coarse material discharge 45. Air regulating flaps 47 are attached over the cross section of the coarse material discharge shaft 44. A coarse material deflector 48 in the form of an adjustment flap is located behind the inlet 43.

The opening device with integrated air fiber classifier is based on the following mode of operation. The fiber stream 6 which is metered in and guided by the opening roller 12 is accelerated by the opening roller 12 and thereby pulled apart. Contaminants are mostly dissolved or crushed. The fibers enter the air channel 38 as an expanded fiber stream. Due to their relatively low kinetic energy, light normal goods 49, that is to say heavy individual fibers, begin to describe a short throwing parabola after which they then move upward in the air channel 38 directed air flow 51, 52 to be taken.

Coarse material 50, which is heavier than the normal material 49, describes a longer throwing parabola due to the higher kinetic energy and thus reaches the coarse material discharge shaft 44 after an impact on the coarse material deflector 48. Due to a small air flow prevailing in the coarse material discharge shaft 44, heavy parts of the coarse material 50 fall out of the air flow 51, 52 into the coarse material discharge 45 38 raised.

The throughput of the air classifier can be about 300 g fibers / m ³ air with an air velocity of 20 m / sec in the classifier.

The fibers discharged through the upper channel section 40 can be fed, for example, via a cyclone to an opening device with an integrated molding machine according to FIG. 1.

In the opening device with integrated air-fiber classifier according to FIG. 2b, components which correspond to components of the opening device according to FIG. 2a are designated with the same reference numerals. The dissolving device according to FIG. 2b differs from the dissolving device according to FIG. 2a essentially by a downward directed air flow, which is indicated by the arrows 51a and 52a. The downward air flow flows on the side of the opening roller 12 opposite the shaft section 17 in a direction opposite to the direction of rotation of the opening roller 12. The upward air flow of the opening roller 12 according to FIG. 2a, however, flows in a direction which corresponds to the direction of rotation of the opening roller 12. The flaps 42 and 48 of the opening device according to FIG. 2a are not realized in the opening device according to FIG. 2b. In the opening device according to FIG. 2b, a height-adjustable coarse material deflector 48a is arranged in such a way that the coarse material 50 is rejected into the coarse material discharge shaft 44, the normal material 49 reaching the lower channel section 39. In the upper channel section 38, in the area where the coarse material inspection takes place, an adjustment flap 42a is also arranged, which serves to adjust the direction of flow and at the same time the flow rate of the supplied air. Furthermore, the position of the air supply slide 41 relative to the opening device according to FIG. 2a is changed.

Claims

EXPECTATIONS

1. Method for resolving non-uniformities in a stream of wood fibers (6) discharged from a metering device (1) intended for the production of fiberboard.

characterized in that the fibers (6) are fed from the metering device through a feed shaft (7) to an opening roller (12) which is provided with a plurality of pins (13) on its surface and rotates in such a way that the fibers (6) deflected by the pins (13) and guided essentially along a shaft section (17) delimited by a partial section (15) of the circumference of the opening roller (12) and an opposite wall (16), at an outlet opening (18) of the

Manhole section (17), preferably essentially horizontal, emerge and reach a forming belt (19) of a molding machine from the outlet opening (18) to form a nonwoven, the forming belt (19) being a sieve belt, on the surface of which the fibers (26) be sucked in.

2. The method according to claim 1, characterized in that the fibers are passed through a profile arranged over the width of the outlet opening (18) with nail-like elevations (53) as they emerge from the shaft section (17).

3. The method according to claim 2, characterized in that the nail-like elevations (53) are adjustable at an angle to the direction of flow of the fibers.

4. The method according to claim 2 or 3, characterized in that the nail-like elevations (53) form an angle of 135 ° with the flow direction of the fibers that occur.

5. The method according to any one of claims 2 to 4, characterized in that the nail-like elevations (53) are arranged in a plurality of rows offset from one another.

6. The method according to any one of the preceding claims,

characterized in that below the outlet opening (18) of the shaft section (17) there is an air flow with a speed component directed parallel to the forming belt (19).

7. The method according to any one of the preceding claims,

characterized in that the fibers (6) are ejected essentially parallel to the forming belt (19) and in the direction of movement (25) of the forming belt (19) from the outlet opening (18) of the shaft section (17), heavy residual parts by mechanical separation into an upper one Position of the fleece and this layer is combed off using a scalping roller (24).

8. Method for resolving non-uniformities in a stream of wood fibers (6) discharged from a metering device (1) intended for the production of fiberboard.

characterized in that the fibers (6) are fed from the metering device through a feed shaft (7) to an opening roller (12) which is provided with a plurality of pins (13) on its surface and rotates in such a way that the fibers (6) deflected by the pins (13) and essentially along a shaft section (17) delimited by a partial section (15) of the circumference of the opening roller (12) and an opposite wall (16) while pulling apart the fiber stream to a thin film and on one Exit opening (18) of the shaft section (17) emerge essentially horizontally, and that the fibers (6) are sighted after leaving the shaft section (17). which, by exerting an upward air flow (51, 52) on the fibers (6) generated by negative pressure, entrains the fibers (49), and contaminants in the form of coarse material (50) are fed to a coarse material discharge (45) by the gravitational force become.

9. The method according to claim 8,

characterized in that the coarse material (50) is directed vertically downwards to the coarse material discharge (45) by a flap (48) which is adjustable in angle.

10. Method for resolving non-uniformities in a stream of wood fibers (6) discharged from a metering device (1) intended for the production of fiberboard.

characterized in that the fibers (6) are fed from the metering device through a feed shaft (7) to an opening roller (12) which is provided with a plurality of pins (13) on its surface and rotates in such a way that the fibers (6) are deflected by the pins (13) and are essentially guided along a shaft section (17) delimited by a partial section (15) of the circumference of the opening roller (12) and an opposite wall (16) while pulling the fiber stream apart and emerge essentially horizontally at an outlet opening (18) of the shaft section (17), and that the fibers (6) are sighted after exiting the shaft section (17) by a downward directed air flow (51a, 52a) generated by negative pressure the fibers (6) are exerted, the fibers (49) are carried along, and impurities in the form of coarse material (50) are fed to a coarse material discharge (45) by the force of gravity.

11. The method according to any one of the preceding claims, characterized in that a roller with a diameter of 500 to 600 mm is used as the opening roller (12) and this is operated at 300 to 2000 revolutions per minute.

12. Device for resolving non-uniformities in a stream of wood fibers (6) discharged from a metering device (1) intended for the production of fiberboard,

characterized in that below a discharge (5) of the metering device (1) a feed shaft (7) extends from the discharge (5) to an opening roller (12) which has a plurality of pins (13) on its surface and is rotatable in such a way that fibers (6) striking the opening roller (12) are deflected by the pins (13), and that a shaft section (17), which is formed by a partial section (15) of the roller circumference and an opposite wall (16) is limited by an outlet opening

(1 1) of the feed shaft (7) extends in the direction of rotation (14) of the opening roller (12) and is provided with a preferably substantially horizontally oriented outlet opening (18) for the fibers and that below the outlet opening (18) of the shaft section (17) a forming belt (19) of a molding machine is arranged, the forming belt (19) being a sieve belt, under which vacuum boxes (20) are arranged in order to suck the fibers (26) towards the surface of the forming belt (19).

13. The apparatus according to claim 12,

characterized in that a profile with nail-like elevations (53) is arranged over the width of the outlet opening (18).

14. The apparatus according to claim 13,

characterized in that the nail-like elevations (53) are adjustable at an angle to the direction of flow of the fibers.

15. The device according to one of claims 13 or 14,

characterized in that the nail-like elevations (53) form an angle of 135 ° with the flow direction of the impinging fibers.

16. The device according to one of claims 13 to 15,

characterized in that the nail-like elevations (53) are arranged in a plurality of rows offset from one another.

17. The device according to one of claims 12 to 16,

characterized in that the distance between the outlet opening

(18) of the shaft section (17) and the forming band (19) is 220 to 280 mm.

18. Device according to one of claims 12 to 17,

characterized in that between the outlet opening (18) of the shaft section (17) and the forming belt (19) there is an air supply opening (21) for an air flow with a speed component directed parallel to the forming belt (19).

19. The apparatus of claim 18,

characterized in that the vertical extension of the air supply opening (21) over the width of the forming belt (19) can be changed by a plurality of independently height-adjustable sheets (35).

20. Device according to one of claims 12 to 19, characterized in that a guide wall (22) adjoins the outlet opening (1 1) of the feed shaft (7) opposite the shaft section (17) and extends into a section running parallel to the forming belt (19), and that at a transition point one

Feed shaft wall (8) to guide wall (22) is formed a nose (23) directed towards the opening roller (12).

21. Device for resolving non-uniformities in a stream of wood fibers (6) discharged from a metering device (1) provided for the production of fiberboard.

characterized in that below a discharge (5) of the metering device (1) a feed shaft (7) extends from the discharge (5) to a dissolving roller (12) which has a plurality of pins (13) on its surface and is rotatable in such a way that fibers (6) striking the opening roller (12) are deflected by the pins (13), and that a shaft section (17), which is formed by a partial section (15) of the roller circumference and an opposite wall (16) is limited, extends from an outlet opening (11) of the feed shaft (7) in the direction of rotation (14) of the opening roller (12) and is provided with an outlet opening (18) for the fibers, which is arranged such that the fibers (6) in the Exiting essentially horizontally in an expanded fiber stream into an air duct (38), which leads an upward directed air stream (51, 52) generated by negative pressure, a coarse material discharge shaft (44), which one of the outlet opening (18) of the Sc has section (17) opposite inlet (43) and a coarse material discharge (45) arranged below the inlet (43), with which the air duct (38) is connected.

22. The apparatus according to claim 21, characterized in that an angle-adjustable flap (48) is arranged at the inlet (43) of the coarse material discharge shaft (44) in such a way that the coarse material (50) is deflected into the coarse material discharge shaft (44).

23. Device for resolving non-uniformities in a stream of wood fibers (6) discharged from a metering device (1) intended for the production of fiberboard.

(11) of the feed shaft (7) extends in the direction of rotation (14) of the opening roller (12) and is provided with an outlet opening (18) for the fibers, which is arranged in such a way that the fibers (6) are essentially horizontal in an expanded fiber stream exit into an air duct (38) which leads to a downward directed air flow (51a, 52a) generated by negative pressure, with a coarse material discharge shaft (44), an inlet (43) opposite the outlet opening (18) of the shaft section (17) and one has coarse material discharge (45) arranged below the inlet (43) and is connected to the air duct (38).

24. The device according to one of claims 12 to 23,

characterized in that the pins (13) of the opening roller (12) taper conically to a tip with increasing distance from the axis of rotation of the opening roller (12).

25. The device according to one of claims 12 to 24, characterized in that the wall (16) of the shaft section (17) is formed by a hood which can be advanced to the opening roller (12).

26. Device according to one of claims 12 to 25,

characterized in that nozzles (30) are arranged in the feed shaft (7) for spraying the fibers (6) discharged from the metering device (1) with additives (31).