EP2347874A1 - Method and device for mixing a particle mixture with an adhesive - Google Patents

Abstract

The method involves feeding a stream of different sized wooden particles in a mixing device (2), and applying adhesive on the wooden particles, where the amount of adhesive is adjusted according to the size of the wooden particles. The adhesive coated particles are mixed with each other, and a stream of the adhesive coated particles is discharged from the mixing device. The wooden particles are conveyed from a particle introduction device (8) to a particle discharge device (12) along a conveying path, where the amount of adhesive applied in the mixing device varies along the conveying path. The particle has density of about 100 to 800 kg per cubic-millimeter. An independent claim is also included for a device for mixing a different sized wooden particle mixture with an adhesive.

Description

The invention relates to a method for mixing a mixture of particles of different sizes of wood material with an adhesive.

The invention also relates to an apparatus for mixing a particle mixture of particles of different sizes with an adhesive having a mixing device, a particle introduction device for introducing the particles of different sizes into the mixing device and an adhesive introduction device.

In the production of wood-based materials wood is comminuted depending on the desired application and connected by means of an adhesive in a hot pressing process, for example, to an MDF or HDF, chipboard or OSB board. For this, the chips or fibers must be coated with the adhesive. Particles which are not made of wood, for example plastic particles, may also be added.

The amount of adhesive used is one of the critical process and cost factors and therefore requires permanent optimization.

Conventionally, the particles to be glued are introduced on one side by a particle introduction device in a mixing device. With the help of so-called mixing tools, the introduced particles pass through the mixing device as far as a particle discharge device, where they leave the mixing device again. Along this path, adhesive is introduced into the mixing device at different points within the mixing device via an adhesive introduction device, for example via nozzles.

In this case, it is basically possible to provide individual layers of the wood-based panels to be produced in separate mixing devices with an adhesive. For example, it is customary to make the top layer of a chipboard of finer chips than the middle layer in order to improve both the surface appearance and the surface roughness of the then finished plate.

Even in this case, however, a particle stream is mixed with the adhesive stream, which does not consist of particles of uniform size. The particle flow has within a certain range a characteristic size distribution, which adversely affects the gluing of the individual particles.

The amount of adhesive that glues a single particle depends on its surface area. In order to achieve the important mechanical properties of the later wood-based panels, such as the transverse tensile strength, bending strength or lift-off, in particular the large chips and fibers are needed. However, since these have a significantly larger volume in relation to their surface than small particles, such as fibers or dusts, the later wood-based panel or already from the particles scattered before compression cake at the points where the stability important large particles, a much smaller amount of adhesive than at the points where the less contributing to the stability of small particles are present. Due to the ratio of the volume of the particles to their surface, small particles are glued with comparatively more adhesive than large ones. As a result, the large particles are subjected to significantly less adhesive, in particular the fine fraction and the dust, however, provided with excessive amounts of adhesive.

The adhesive used, however, is not only disadvantageous to large and small Particles are dispersed, too much glue is used overall. The adhesive used is thus not handled economically and the properties of the pressed particles from the coated particles never reach the technically conceivable optimum.

The invention is therefore based on the object, so to develop a method and apparatus for mixing a mixture of particles of different sizes of wood material with an adhesive that a better distribution of the adhesive is ensured on the particles of different sizes.

1. (a) Zuführen der Partikel unterschiedlicher Größe in einem Strom in eine Mischvorrichtung,
2. (b) Beleimen der Partikel unterschiedlicher Größe mit dem Klebstoff, wobei die Menge des Klebstoffs auf die Größe des jeweiligen Partikels abgestimmt ist,
3. (c) Vermischen der beleimten Partikel unterschiedlicher Größe
4. (d) Abführen der vermischten beleimten Partikel unterschiedlicher Größe in einem Strom aus der Mischvorrichtung.

The invention achieves the stated object by a generic method which comprises the following steps:

1. (a) feeding the particles of different size in a stream into a mixing device,
2. (b) gluing the particles of different size with the adhesive, wherein the amount of the adhesive is adapted to the size of the respective particle,
3. (c) mixing the glued particles of different sizes
4. (d) discharging the mixed glued particles of different size in a stream from the mixing device.

The fact that all particles are glued regardless of their size in the same mixing device, the equipment cost of the process is significantly reduced. Due to the fact that the amount of adhesive attributable to the respective particles depends on the size of the particle, optimum distribution of the adhesive is ensured. The two steps (b) and (c) can in particular also be carried out jointly by mixing the particles with one another, for example in the mixing device, while adhesive is introduced into the mixing device. The particles are different Size both mixed with each other and with the adhesive and thereby glued.

Preferably, the particles of different size, depending on their size, are glued for different lengths of time in the mixing device. In particular, small particles are mixed with the adhesive for less than large particles. Due to the long residence time of the large particles in the mixing device, it is ensured that they are adequately glued in order later to ensure sufficient stability for a plate pressed from the particles. At the same time, the smaller particles, which are less important for these stability characteristics, are less glued in their shorter time that they are in the mixing device. This results in an optimized gluing and approximately in the way, as if all particle sizes would have been provided separately with adhesive. It is possible to achieve a uniform gluing of all particles or a gluing factor dependent on the particle size and, for example, to glaze large particles more strongly than small particles. This in turn is followed by significantly improved plate properties with simultaneously reduced amount of adhesive used, since the mechanically-technologically important particles have a good bond quality and not, as in conventional methods, clearly contain too little adhesive.

The particles of different size are conveyed during mixing in the mixing device, in particular from a particle introduction device to a particle discharge device along a conveying path. Advantageously, small particles are introduced in the conveying direction behind large particles in the mixing device. In particular, the adhesive is introduced into the mixing device along the entire conveying path. In this way it is ensured that small particles have to travel a shorter distance within the mixing device along the conveying path than larger particles. If the adhesive is introduced along the entire conveying path, for example via nozzles, The small particles pass less of these nozzles through the shorter distance they travel, so they can also absorb less adhesive. The large particles that cover the entire conveying path within the mixing device, however, come in all places where adhesive is introduced into the mixing device over, and can be optimally glued. The amount of adhesive that is applied to a portion of the conveying path is completely freely adjustable, which also size-dependent gluing factors of the particles can be achieved. The density of the particles of different sizes is preferably between 100 kg / m ³ and 800 kg / m ³ .

A device according to the invention for mixing a particle mixture of particles of different sizes with an adhesive is a generic device, which is characterized in that a fractionating device is provided, through which the particles of different size dwell in the mixing device for different lengths of time during operation of the device.

As already explained above, the differently long residence time of the particles in the mixing device ensures an optimized distribution of the adhesive between large and small particles.

Within the mixing device, a conveying device is provided, by means of which the particles of different size introduced into the particle introduction device can be conveyed to a particle discharge device along a conveying path. The adhesive introduction device is designed in particular as distribution nozzles distributed along the conveying path. This ensures that along the entire conveying path a uniform amount of adhesive is introduced into the mixing device. Alternatively, the amount of adhesive introduced can also vary along the conveying path.

The fractionating device is preferably in or in the processing direction the particle introduction device arranged. This can ensure that particles of different sizes are introduced at different points of the conveying path in the mixing device. Due to the fact that small particles are introduced into the mixing device later in the conveying direction than large particles, they do not pass through the entire conveying path and, accordingly, do not pass through all the injection nozzles of the adhesive introduction device. You can thus absorb less adhesive than the large particles that go through the entire conveyor.

The fractionating device can also be arranged downstream of the particle introduction device in the processing direction. In this case, the particles of any size enter the mixing device at the same location. In this case, the fractionator is designed to impart different speeds to particles of different sizes along the conveying path. The fact that in this case smaller particles move faster along the conveying path, their residence time is also reduced in the mixing device and thus ensured that they can not absorb too much adhesive.

Preferably, the fractionator is a fan. If this blower is arranged, for example, in the particle introduction device or in the processing direction in front of it, a lateral air flow is directed to the particle flow, which separates the particles based on size and weight, as is the case, for example, in a classic air separation process. Here, the smaller particles and the dust are deflected more than large particles. If the fan is arranged so that the air flow, for example, flows parallel to the conveying direction, smaller particles are fed later in the conveying direction of the mixing device.

However, the blower can also be arranged inside the mixing device, ie in the processing direction after the particle introduction device. Also In this case, a lateral air flow is directed to the particle stream, which preferably accelerates the particles in the conveying direction. Smaller and lighter particles are accelerated faster than large particles. These consequently move faster than large particles in the conveying direction through the mixing device and thus absorb less adhesive.

The fractionating device can also be designed as a rotatably mounted brush. The rotatably mounted brush, which is set in rotation during operation of the device, may also be arranged in the processing direction in front of or behind or directly in the particle introduction device. Also by the rotating brush, the individual particles are preferably accelerated in the conveying direction, with larger particles are less accelerated, so fly less far. Also in this way it can be ensured that smaller particles are introduced into the mixing device so that they no longer pass through the entire conveying path and thus can absorb less adhesive. By means of a throwing device arranged inside the mixing device, in particular a rotating brush, drum or the like, it is ensured, as in the case of the blower, that the particles have a speed which depends on their size in the conveying direction.

The fractionator preferably has a sieve. In particular, this sieve has openings of different sizes. The arrangement of a sieve is particularly advantageous if the fractionating device is arranged inside or in the processing direction in front of the particle introduction device. In this way it can be ensured that large particles, which were too far distracted too far in the conveying direction, are not introduced with the smaller particles in the mixing device, but slide back along the screen preferably inclined and at the intended location for their size in the mixing device be introduced. In this way, it is ensured that in fact all particles of a certain size, the route provided for them along the conveying path within the mixing device return.

The device according to the invention and the method according to the invention consequently provide for an optimized distribution of the amount of adhesive on the individual particles of different sizes and are particularly suitable for all types of wood shredding products, such as fibers, chips or strands and thus also for the production of a wide variety of wood-based materials, such as MDF - or HDF, chipboard or OSB boards. Of course, particles can also be provided with an adhesive which is not made of wood, but for example of a plastic. It is also conceivable to mix particles of different materials.

With the aid of a drawing, various embodiments of a device according to the invention are explained in more detail below. The same components are provided in all figures with the same reference numerals.

Figur 1

eine schematische Darstellung eines ersten Ausführungsbeispiels einer erfindungsgemäßen Vorrichtung;

Figur 2

eine schematische Darstellung eines zweiten Ausführungsbeispiels einer erfindungsgemäßen Vorrichtung;

Figur 3

eine schematische Darstellung eines dritten Ausführungsbeispiels einer erfindungsgemäßen Vorrichtung und

Figur 4

eine schematische Darstellung eines vierten Ausführungsbeispiels einer erfindungsgemäßen Vorrichtung.

Show it:

FIG. 1

a schematic representation of a first embodiment of a device according to the invention;

FIG. 2

a schematic representation of a second embodiment of a device according to the invention;

FIG. 3

a schematic representation of a third embodiment of a device according to the invention and

FIG. 4

a schematic representation of a fourth embodiment of a device according to the invention.

FIG. 1 shows a schematic representation of an apparatus according to a first embodiment of the present invention.

In a mixing device 2 there is a conveying device 4 with a drive unit 6. The conveying device 4 conveys particles introduced from above through a particle introduction device 8 into the mixing device 2 along the conveying direction F. They are mixed by the conveyor 4 and glued from above by a Klebstoffeinbringvorrichtung in the form of evenly distributed along the conveying path controllable Beleimungsdüsen 10 with adhesive. The particles thus glued leave the mixing device 2 via a particle discharge device 12. The glue injection nozzles 10 can also be distributed irregularly or adjusted to different spray strengths.

In the particle introduction device 8, a fractionating device 14 is provided, which in FIG. 1 only indicated as a schematic box. The fractionator 14 is in FIG. 1 designed as a blower, which blows along the air flow direction L an air flow in the particle introduction device 8. The particles falling from above into the particle introduction device 8 are deflected by this air flow in the direction of air flow L, which is indicated by different arrows.

This will be light particles in FIG. 1 The light particles fall through the funnel-shaped widened particle introduction device 8 behind the first Beleimungsdüsen 10 seen in the conveying direction F. By the conveyor 4 are all incident in the mixing device 2 Particles along the conveying direction F in the direction of the Partikelaustragsvorrichtung 12 promoted, wherein the light particles are guided past fewer Beleimungsdüsen 10. Therefore, the light particles can only absorb a smaller amount of the adhesive introduced into the mixer 2 by the gluing nozzles 10. The heavy particles, which are hardly or not deflected by the air flow in the direction of air flow L, on the other hand, pass all or most of the envisaged gluing nozzles 10 on their way to the particle discharge device 12 and are therefore provided with more adhesive than the light particles.

FIG. 2 shows a second embodiment of the present invention.

For the same components, the same reference numerals as in FIG. 1 used. Again, the particles are introduced via a particle introduction device 8 in a mixing device 2, in which they are conveyed by a conveyor 4 along the conveying direction F in the direction of the particle discharge device 12, being guided past Beleimungsdüsen 10, is introduced by the adhesive into the mixing device 2.

In FIG. 2 is on the right edge of the mixing device 2, a fractionating device 14 is provided, which is designed as a fan. The fractionator 14 is in FIG. 2 Consequently, disposed within the mixing device 2 and thus in the processing direction after the particle introduction device 8.

Unlike in FIG. 1 Here, all the particles pass through the particle introduction device 8 at the same location in the mixing device 2. They are deflected by the introduced through the fractionator 14 along an air flow direction L air flow in the conveying direction F. Again, the light particles are accelerated more in the conveying direction F, as the heavy particles. This ensures that the light particles, at least at the first gluing nozzles 10, pass much faster than if they were moved only by the conveyor 4 in the conveying direction F. As a result, the absorption of adhesive from these first gluing nozzles 10 is extremely small. This also ensures that the large particles are optimally wetted with adhesive since they are guided past all Beleimungsdüsen 10 with the predetermined speed of the conveyor 4. Since she, as in FIG. 1 Also, while being mixed by the conveyor 4, an all-round homogeneous gluing of all particles is ensured with adhesive.

FIG. 3 shows a device according to a third embodiment of the present invention. Again, the same reference numerals have been used for the same components. In FIG. 3 is a fractionator 14 as in FIG. 1 provided in the processing direction before the mixing device 2. As in FIG. 2 the fractionating device 14 consists of a fan, which is operated via a fan drive unit 16. By the fractionator 14 in FIG. 3 an air flow is blown into a particle introduction device 8 along an air flow direction L. As in FIG. 1 become the particle introduction device 8 introduced particles of this air flow in the air flow direction L deflected. Again, the light particles are deflected more than the heavy ones. Within the particle introduction device 8, a screen 18 is arranged, through which the deflected particles must pass in order to get into the mixing device 2. In this case, the sieve 18 has different sized sieve openings (not shown). In FIG. 3 the sieve 18 has the smaller sieve openings to the left and the larger sieve openings to the right. By the air flow in the air flow direction L, the light particles are deflected more to the left and meet there on the part of the screen 18, which has the smaller screen openings. The large particles are deflected by the air flow barely or not at all and hit the right part of the screen 18, which has the larger screen openings.

If a relatively large particle is deflected so far to the left due to improper littering or due to collisions between the individual particles, that it is too large for the sieve openings present in the sieve 18, it slides downwards along the sieve 18 and thus reaches the right part of the screen 18, where the screen openings are large enough. For this, the sieve is 18 in FIG. 3 arranged inclined.

As in the embodiment according to FIG. 1 are also in the embodiment FIG. 3 Consequently, the small particles are deflected further to the left in the direction of the air flow direction L and thus also fall further to the left in the mixing device 2. There, they are conveyed further by a conveyor 4 in the conveying direction F and thereby guided past Beleimungsdüsen 10. Due to the fact that the small particles are guided past fewer gluing nozzles 10 than the larger ones, an optimized gluing is ensured here as well.

In the FIG. 4 A device according to a fourth embodiment of the present invention differs from that shown in FIG FIG. 1 shown device in that the fractionator 14 not as a fan, but is designed as a rotating brush, drum or the like. The direction of rotation is indicated by the curved arrow.

The brush, which rotates in the direction of the arrow, of the fractionating device 14 deflects the particles introduced into the particle introduction device 8 to the left. Again, it holds that light particles continue to fly as heavy, so that they are also introduced farther left into the mixing device 2 and are guided by the conveyor 4 to less glueing nozzles 10.

In all in the FIGS. 1 to 4 In the embodiment shown, it is thus ensured that small particles are mixed with adhesive introduced via the gluing nozzles 10 for less than the large particles.

By means of devices according to the invention, it is thus ensured that the gluing factor of particles of different sizes can be controlled depending on their size. All that is needed is a gluing device, which saves time, space and costs.

LIST OF REFERENCE NUMBERS

F

conveying direction

L

Airflow direction

2

mixing device

4

Conveyor

6

drive unit

8th

Partikeleinbringvorrichtung

10

Beleimungsdüsen

12

Partikelaustragsvorrichtung

14

fractionator

16

Fan drive unit

18

screen

Claims (15)

Method for mixing a mixture of particles of different size of wood material with an adhesive, comprising the following steps: (a) feeding the particles of different size in a stream into a mixing device (2), (b) gluing the particles of different size with an adhesive, wherein the amount of the adhesive is adapted to the size of the respective particle, (c) mixing the glued particles of different sizes, (D) discharging the mixed glued particles of different sizes in a stream from the mixing device (2). A method according to claim 1 , characterized in that the particles of different size depending on their size for different lengths of time in the mixing device (2) are glued. A method according to claim 1 or 2, characterized in that the particles of different size are conveyed in the mixing device (2) from a particle introduction device (8) to a particle discharge device (12) along a conveying path. Method according to one of claims 1, 2 or 3, characterized in that small particles are introduced in the conveying direction (F) behind large particles in the mixing device (2). Method according to one or more of the preceding claims, characterized in that the adhesive along the conveying path in the mixing device (2) is introduced. A method according to claim 5, characterized in that in the mixing device (2) introduced adhesive varies along the conveying path. Method according to one or more of the preceding claims, characterized in that the density of the particles between 100 kg / m ³ and 800 kg / m ³ . Device for mixing a particle mixture of particles of different sizes with an adhesive, with a) a mixing device (2), b) a particle introduction device (8) for introducing the particles of different sizes into the mixing device (2), c) an adhesive introduction device (10),
characterized in that a fractionating device (14) is provided, through which the particles of different size dwell in the mixing device for different lengths of time during operation of the device. Apparatus according to claim 8, characterized in that a conveying device (4) within the mixing device (2) is provided, through which the introduced particles of different size to a particle discharge device (12) along a conveying path can be conveyed. Apparatus according to claim 9, characterized in that the Klebstoffeinbringvorrichtung is formed as distributed over the conveying Einbringdüsen 10. Apparatus according to claim 9 or 10, characterized in that the fractionating device (14) is arranged in or in the processing direction in front of the particle introduction device (8). Apparatus according to claim 9 or 10, characterized in that the fractionating device (14) is arranged downstream of the particle introduction device (8) in the processing direction. Device according to one of claims 8 to 12, characterized in that the fractionating device (14) is a fan. Device according to one of claims 8 to 12, characterized in that the fractionating device (14) is a throwing device, in particular a rotatably mounted brush, drum or the like. Device according to one of claims 8 to 14, characterized in that the fractionating device (14) comprises a sieve (18) having different sized openings.

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