Process and apparatus for adding glue to a flow of loose wood materials

Description

[0001] Loose wood materials used in processes of this type are preferably constituted by wooden chips or fibres which are mixed with glue to be made ready for use as woodchip or fibre panels.

[0002] A process and plant of this type is described in patent WO 02/066214. The plant described consists in a device for feeding loose wood materials to a mixer device, internally of which glue is sprayed onto the wood material flow through nozzles arranged in proximity of the inlet of the mixer device. The mixer device is crossed by a flow of hot air sent by special means and introduced into the mixer device at the section thereof where the glue is sprayed. The wood materials and the glue are united at the inlet of the mixer device and mixed uniformly as they pass through the mixer device, drawn by the hot air flow. The wood material mixed with the glue is thus removed from the mixer and sent on to subsequent work stations.

[0003] The described process and plant exhibit some drawbacks. The breadth of the front across which the glue is sprayed is limited to the inlet zone of the mixer device. This means that not all of the glue enters into immediate contact with the wood material, part of it being drawn by the hot air flow internally of the mixer device, where it partially unites with the wood material by effect of the mixer, but also partially sticks to the walls or the blades of the mixer, and is thus lost. The limited breadth of the front the glue is sprayed across can also lead to the formation of glue clots which do not amalgamate with the wood material. The parts of the glue which do not unite with the wood chips or fibres, drawn by the hot air flow in inlet in the mixer device, can mix up together and form clots which can form marks on the surfaces of the panels and might determine a breakdown of the physical and mechanical qualities of the panels themselves.

[0004] EP 1022103 discloses a gluing apparatus for plants for producing wood fibre panels by a dry method, the apparatus comprising a tubular body and sprayer means to inject a suitable liquid glue into the interior of the tubular body. The cross-section through the tubular body encloses an area which increases in progressing from its open upstream end, into which the wood fibres are fed conveyed by an air stream, to its open downstream end.

[0005] DE 4115047 discloses an applicator for the continuous glueing of wood chips by liquid glue. The applicator comprises a cylindrical mixing chamber supported in a holder, at whose one end is a feeder for the wood chips, and at the other end is an outlet. Axially through the centre of the mixing chamber passes a high speed rotary shaft equipped, in the injection zone, with injector nozzles and, in the mixing zone, with cooling mixer nozzles. The injector nozzles can be cooled, and a glue feeder in the form of jet sprays is directed into the chip feeder opening.

[0006] The main aim of the present invention is to obviate the limitations and drawbacks of the prior art by providing a process according to claim 7 and plant according to claim 1 for adding glue to a flow of loose wood material which obtains a homogeneous mixture and a high degree of amalgamation between the glue and the wood chips or fibres. The invention also considerably limits the loss of glue and prevents the formation of glue clots.

[0007] Further characteristics and advantages of the present invention will better emerge from the detailed description that follows of a preferred but non-exclusive embodiment of a process and plant for adding glue to a flow of loose wood materials, illustrated purely by way of a non-limiting example in the accompanying figure of the drawing, in which:
figure 1 is a schematic view of the plant according to the invention.

[0008] With reference to the figure of the drawing, 1 denotes in its entirety a plant according to the present invention. The plant comprises a device 2 for feeding a mass of loose wood material, in the form of chips or fibres, to a loading conduit 3 of a mixer 4 provided with an inlet 4a for wood material and an outlet 4b. The plant further comprises means 5 for sending a flow of air into the loading conduit 3 and means for injecting 6 glue into the mass of wood material upstream of an entry of the wood material into the mixer 4.

[0009] The loading conduit 3 comprises a hopper 7 which exhibits at least an inlet 7a connected to the device 2 and at least an outlet 7b connected to the inlet 4a of the mixer 4. A lateral wall 7c of the hopper 7 extends partially into the mixer 4 to part the inlet 4a section and to define an internal separating wall in the mixer 4.

[0010] The hopper 7 internally exhibits at least one dividing wall 8, arranged about parallel to the longitudinal axis x of the hopper 7, which defines a channel 9 for entry of the air flow. The channel 9 exhibits an inlet 9a and an outlet 9b which is arranged upstream of the outlet 7b of the hopper 7.

[0011] The dividing wall 8 is positionable with a varying inclination with respect to the longitudinal axis x of the hopper 7 to realise a variable-section channel 9. In the illustrated embodiment there are two dividing walls 8, each of which can be inclined with respect to the longitudinal axis x in such a way that the respective channel 9 exhibits a converging or diverging orientation, according to the fluid-dynamic effect to be obtained at the outlets 9b of the channels.

[0012] The means for injecting 6 comprise at least one injector 12 associated to the hopper 7 for atomizing and injecting the glue internally of the hopper 7 in a section downstream of the outlet 9b of the channel 9 for air inlet. The injector 12 is mounted on an oscillating support so as to be orientable with a variable inclination with respect to a longitudinal axis x of the hopper 7. In the illustrated embodiment the plant comprises a plurality of injectors 12 distributed on the lateral surface of the hopper 7 in predetermined configurations. In the specific case, the injectors 12 are arranged along two parallel and opposite lines, respectively arranged on opposite sides of the hopper 7 at the channel 9 outlets. The injectors 12 are mounted on oscillating supports in order to be orientable with variable inclinations with respect to the longitudinal axis x of the hopper 7.

[0013] The means 5 for sending an air flow into the loading conduit 3 comprise at least one heat-ventilator 10 a delivery of which is connected to an inlet 11a of at least one conveyor conduit 11. The conveyor conduit 11 exhibits an outlet 11b which is connected to the inlet 9a of the channel 9. At least one delivery regulator 13 is located on the conveyor conduit 11, which regulates the inlet air delivery into the hopper 7. Figure 1 illustrates two conveyor conduits 11 with respective delivery regulators 13, each of which leads to a respective channel 9.

[0014] With reference to the described plant, the process of the invention comprises the following stages.

[0015] A mass of loose wood material is fed from the device 2 into the hopper 7 loading the mixer 4, which mixer has an inlet 4a for the wood material and an outlet 4b. Together with the wood material, the hopper 7 receives a hot air flow from the heat-ventilator 10 the delivery of which is connected to the conveyor conduit 11.

[0016] The conveyor conduit 11 opens into the channel 9 which is arranged internally of the hopper 7. The glue is injected and atomised onto the mass of wood material upstream of an entrance of the wood mass into the mixer 4; at least one injector 4 sends the glue onto the wood mass, which injector 12 is associated with the lateral surface of the hopper 7 in a downstream section thereof and on a same side thereof as the outlet 9b of the channel 9. The air flow issuing from the outlet 9b has a containing action on the flow of wood material and realizes a compact front onto which the atomized glue is sprayed. The mass of wood material mixed with the glue passes from the hopper 7 internally of the mixer 4 where a mixer shaft 14 mixes the wood material, homogenising the distribution of the glue. The lateral wall 7c prevents the wood material mixed with the glue, drawn by the air flow, from being moved towards the outlet 4b of the mixer 4 as soon as it enters the inlet 4a, keeping it confined in a limited zone within the mixer 4. The function of the lateral wall 7c is to make the wood-glue mixture distribute uniformly inside the mixer 4, filling the volume of the mixer 4 completely. The wood-glue mixture is then sent on to following work stations, exiting through the outlet 4b of the mixer 4.

[0017] For a better glue distribution, the glue can be injected and atomised through a plurality of injectors 12, distributed over the lateral surface of the hopper 7 in predetermined and orientable configurations with variable inclinations with respect to the longitudinal axis x of the hopper 7. In the illustrated example in figure 1 the injectors 12 are arranged in two parallel rows and are opposite, being respectively aligned in a section downstream of the outlet 9b of a respective channel 9. The glue is sprayed onto the mass of loose wood material on two opposite fronts, increasing the fraction of wood particles that enter directly into contact with the glue.

[0018] The plant and process described offer two important advantages: the structure of the hopper 7 loading the mixer 4 and in particular the presence of the channel or channels 9, which thanks to the position of the respective outlets, enable the glue to be sprayed on a compact front of wood material. The fraction of glue which does not enter into contact with the chips or fibres is considerably reduced with respect to the prior art, with a consequent saving in glue volume used. As the drops of glue which do not enter into contact with the chips or fibres are limited in number, the risk that glue clots can form internally of the mass of wood materials is considerably reduced.

[0019] Thanks also to the compacting action of the flow of air internally of the hopper 7, the glue is well-distributed throughout the wood material. The panels obtained using the mixture produced by the described plant and process are therefore of a high quality, with obvious production cost savings.

Claims

1. A plant for adding glue to a flow of loose wood materials, comprising: a device (2) for feeding a mass of loose wood material, consisting of particles, to a loading conduit (3) of a mixer (4) provided with an inlet (4a) for the mass of wood material and an outlet (4b), a mixer shaft (14) being located internally of the mixer (4) for mixing and making homogeneous a distribution of the glue, the loading conduit (3) comprising a hopper (7) which exhibits at least an inlet (7a) connected to the device (2) and at least an outlet (7b) connected to the inlet (4a) of the mixer (4); means (5) for sending a flow of hot air into the loading conduit (3) comprising a heat ventilator (10); and means for injecting (6) glue into the mass of wood material upstream of an entry of the wood material into the mixer (4), the means for injecting comprising at least one injector (12), characterised in that a delivery of the heat ventilator (10) is connected to a conveyor conduit (11) opening into a channel (9) arranged internally of the hopper (7), and said at least one injector (12) is associated to a lateral surface of the hopper (7) at a section thereof downstream of and on the same side as an outlet (9b) of the channel (9), so that the flow of hot air exiting from the outlet (9b) of the channel (9) performs a containing action on the mass of wood material, making a compact front onto which the glue is atomised and sprayed.

2. The plant of claim 1, characterised in that the hopper (7) has internally thereof at least one separating wall (8) arranged parallel to a longitudinal axis (x) of the hopper (7), which separating wall (8) defines the channel (9) for entry of the flow of air, which channel (9) has an inlet (9a) and an outlet (9b), the outlet (9b) of the channel (9) being arranged upstream of the outlet (7b) of the hopper (7), a lateral wall (7c) of the hopper (7) extending for a tract thereof internally of the mixer (4) in order to divide a section of the inlet (4a) and to define an internal separating wall internally of the mixer (4).

3. The plant of claim 2, characterised in that the separating wall (8) is positionable with a variable inclination with respect to the longitudinal axis (x) of the hopper (7), realising a channel (9) having a variable section.

4. The plant of claim 3, characterised in that the injector (12) is orientable with a variable inclination with respect to the longitudinal axis (x) of the hopper (7).

5. The plant of claim 4, characterised in that it comprises a plurality of injectors (12) distributed over the lateral surface of the hopper (7) in predetermined configurations, the injectors (12) being orientable with variable inclination with respect to the longitudinal axis (x) of the hopper (7).

6. The plant of claim 1, characterised in that it comprises at least one delivery regulator (13) arranged on the conveyor conduit (11) for regulating the flow of air in inlet to the hopper (7).

7. A process for adding glue to a mass of loose wood material in particle form, comprising the following stages:

feeding a mass of loose wood material in particle form from a device (2) to a loading hopper (7) of a mixer (4) provided with an inlet (4a) for the mass of loose wood material and an outlet (4b);

sending a flow of hot air into the hopper (7) by means of a heat ventilator (10);

atomising and injecting glue into the mass of loose wood material upstream of the inlet (4a) of the wood material into the mixer (4) by means of at least one injector (12);

sending the mass of wood material when mixed with the glue internally of the mixer (4) where a mixer shaft (14) is located for mixing and making homogeneous a distribution of the glue;

sending the mass of wood material mixed with the glue onto subsequent work stations through the outlet (4b) of the mixer (4), characterised in that a delivery of the heat ventilator (10) is connected to a conveyor conduit (11) opening into a channel (9) arranged internally of the hopper (7), and said at least one injector (12) is associated to a lateral surface of the hopper (7) at a section thereof downstream of and on a same side as an outlet (9b) of the channel (9), so that the flow of hot air exiting from the outlet (9b) of the channel (9) performs a containing action on the mass of wood material, making a compact front onto which the glue is atomised and sprayed.

8. The process of claim 7, characterised in that the glue is injected and atomised by a plurality of injectors (12) distributed on the lateral surface of the hopper (7) in predetermined configurations, the plurality of injectors (12) being orientable with variable inclinations with respect to a longitudinal axis (x) of the hopper (7).

Ansprüche

1. Anlage für die Zugabe von Klebemittel zu einem Strom aus losem Holzmaterial, enthaltend: eine Vorrichtung (2) zum Zuführen einer aus Partikeln bestehenden Masse aus losem Holzmaterial an eine Ladeleitung (3) eines Mischers (4), der mit einem Einlass (4a) für die Masse aus Holzmaterial und einem Auslass (4b) versehen ist, eine Mischwelle (14), die im Inneren des Mischers (4) angeordnet ist, und die zum Mischen und zu einer homogenen Verteilung des Klebemittels dient, wobei die Ladeleitung (3) einen Trichter (7) enthält, welcher wenigstens einen Einlass (7a) aufweist, angeschlossen an die Vorrichtung (2), und wenigstens einen Auslass (7b), angeschlossen an den Einlass (4a) des Mischers (4); Mittel (5) zum Leiten eines Heissluftstromes in die Ladeleitung (3), enthaltend einen Heissluftventilator (10); und Mittel zum Einspritzen (6) von Klebemittel in den Mischer (4), wobei die Einspritzmittel wenigstens eine Spritzdüse (12) enthalten, dadurch gekennzeichnet, dass ein Förderauslass des Heissluftventilators (10) an eine Förderleitung (11) angeschlossen ist, die in einem im Inneren des Trichters (7) angeordneten Kanal (9) mündet, und dass die genannte wenigstens eine Spritzdüse (12) einer seitlichen Oberfläche des Trichters (7) zugeordnet ist, und zwar an einem Abschnitt desselben stromabwärts und auf derselben Seite wie ein Auslass (9b) des Kanals (9), so dass der aus dem Auslass (9b) des Kanals (9) austretende Heissluftstrom eine Haltewirkung auf die Masse aus Holzmaterial ausübt und dabei eine kompakte Fläche bildet, auf welche das Klebemittel zerstäubt und gespritzt wird.

2. Anlage nach Patentanspruch 1, dadurch gekennzeichnet, dass der Trichter (7) in seinem Inneren wenigstens eine Trennwand (8) enthält, angeordnet parallel zu einer Längsachse (x) des Trichters (7), welche Trennwand (8) den Kanal (9) für den Eintritt des Luftstromes beschreibt, welcher Kanal (9) einen Einlass (9a) und einen Auslass (9b) hat, wobei der Auslass (9b) des Kanals (9) stromaufwärts des Auslasses (7b) des Trichters (7) angeordnet ist, und wobei sich eine Seitenwand (7c) des Trichters (7) über eine Strecke desselben im Inneren des Mischers (4) erstreckt, um einen Abschnitt (des Einlasses (4a) abzuteilen und eine interne Trennwand im Inneren des Mischers (4) zu beschreiben.

3. Anlage nach Patentanspruch 2, dadurch gekennzeichnet, dass die Trennwand (8) mit einer veränderbaren Neigung im Verhältnis zu der Längsachse (x) des Trichters (7) positionierbar ist, um einen Kanal (9) mit veränderbarem Querschnitt zu realisieren.

4. Anlage nach Patentanspruch 3, dadurch gekennzeichnet, dass die Spritzdüse (12) mit einer veränderbaren Neigung im Verhältnis zu der Längeachse (x) des Trichters (7) ausrichtbar ist.

5. Anlage nach Patentanspruch 4, dadurch gekennzeichnet, dass sie eine Anzahl von Spritzdüsen (12) enthält, verteilt über die seitliche Oberfläche des Trichters (7) in vorgegebenen Konfigurationen, wobei die Spritzdüsen (12) mit einer veränderbaren Neigung im Verhältnis zu der Längsachse (x) des Trichters (7) ausrichtbar sind.

6. Anlage nach Patentanspruch 1, dadurch gekennzeichnet, dass sie wenigstens einen Ablassregler (13) enthält, angeordnet an der Förderleitung (11), um den Luftstrom in den Einlass des Trichters (7) zu regulieren.

7. Verfahren für die Zugabe von Klebemittel zu einer Masse aus losem Holzmaterial in Form von Partikeln, enthaltend die folgenden Phasen:

- Zuführen einer Masse aus losem Holzmaterial in Form von Partikeln von einer Vorrichtung (2) zu einem Ladetrichter (7) eines Mischers (4), versehen mit einem Einlass (4a) für die Masse aus losem Holzmaterial und mit einem Auslass (4b);

- Einleiten eines Heissluftstromes in den Trichter (7) mit Hilfe eines Heissluftventilators (10);

- Zerstäuben und Einspritzen von Klebemittel in die Masse aus losem Holzmaterial stromaufwärts des Einlasses (4a) für das Holzmaterial in den Mischer (4) mit Hilfe von wenigstens einer Spritzdüse (12);

- Einleiten der mit dem Klebemittel vermischten Masse aus Holzmaterial in das Innere des Mischers (4), wo eine Mischwelle (14) zum Mischen und zur homogenen Verteilung des Klebemittels angeordnet ist;

- Weiterleiten der mit dem Klebemittel vermischten Masse aus Holzmaterial durch den Auslass (4b) des Mischers (4) an anschliessende Verarbeitungsstationen, dadurch gekennzeichnet, dass ein Förderauslass des Heissluftventilators (10) an eine Förderleitung (11) angeschlossen ist, die in einem im Inneren des Trichters (7) angeordneten Kanal (9) mündet, und dass wenigstens eine Spritzdüse (12) einer Seitenwand des Trichters (7) zugeordnet ist, und zwar an einem Abschnitt desselben stromabwärts und auf derselben Seite wie ein Auslass (9b) des Kanals (9), so dass der aus dem Auslass (9b) des Kanals (9) austretende Heissluftstrom eine Haltewirkung auf die Masse aus Holzmaterial ausübt und dabei eine kompakte Fläche bildet, auf welche das Klebemittel zerstäubt und gespritzt wird.

8. Verfahren nach Patentanspruch 7, dadurch gekennzeichnet, dass das Klebemittel durch eine Anzahl von Spritzdüsen (12) eingespritzt und zerstäubt wird, verteilt an der seitlichen Oberfläche des Trichters (7) in vorgegebenen Konfigurationen, wobei die Anzahl von Spritzdüsen (12) mit veränderbaren Neigungen im Verhältnis zu einer Längsachse (x) des Trichters (7) ausrichtbar sind.

Revendications

1. Installation pour ajouter de la colle à un écoulement de matériaux ligneux en vrac, comprenant: un dispositif (2) pour fournir une masse de matériau ligneux en vrac, constitué de particules, à un conduit de chargement (3) d'un mélangeur (4) pourvu d'une entrée (4a) pour la masse de matériau ligneux et d'une sortie (4b), un arbre mélangeur (14) étant localisé intérieurement au mélangeur (4) pour mélanger et rendre homogène la distribution de la colle, le conduit de chargement (3) comprenant une trémie (7) qui présente au moins une entrée (7a) connectée au dispositif (2) et au moins une sortie (7b) connectée à l'entrée (4a) du mélangeur (4); des moyens (5) pour envoyer un flux d'air chaud dans le conduit de chargement (3) comprenant un thermo-ventilateur (10); et des moyens d'injection (6) de la colle dans la masse de matériau ligneux en amont d'une entrée du matériau ligneux dans la mélangeur (4), les moyens d'injection comprenant au moins un injecteur (12), caractérisé en ce que la bouche de sortie du thermo-ventilateur (10) est reliée à un conduit convoyeur (11) débouchant dans un canal (9) disposé intérieurement à la trémie (7), et ledit au moins un injecteur (12) est associé à une surface latérale de la trémie (7) en correspondance d'une de ses sections se trouvant en aval d'une sortie (9b) du canal (9) et du même côté que cette dernière, de sorte que le flux d'air chaud sortant de la sortie (9b) du canal (9) effectue une action de retenue sur la masse de matériau ligneux, en constituant ainsi un front compact sur lequel la colle est nébulisée.

2. Installation selon la revendication 1, caractérisée en ce que la trémie (7) présente en son intérieur au moins une paroi de séparation (8) disposée parallèlement à un axe longitudinal (x) de la trémie (7), laquelle paroi de séparation (8) définit le canal (9) pour l'entrée du flux d'air, lequel canal (9) présente une entrée (9a) et une sortie (9b), la sortie (9b) du canal (9) étant disposée en amont de la sortie (7b) de la trémie (7), une paroi latérale (7c) de la trémie (7) s'étendant sur une de ses parties intérieurement au mélangeur (4) de manière à diviser une section de l'entrée (4a) et à définir une paroi interne de séparation à l'intérieur du mélangeur (4).

3. Installation selon la revendication 2, caractérisée en ce que la paroi de séparation (8) est positionnable avec une inclinaison variable par rapport à l'axe longitudinal (x) de la trémie (7), en formant un canal (9) de section variable.

4. Installation selon la revendication 3, caractérisée en ce que l'injecteur (12) est orientable avec une inclinaison variable par rapport à l'axe longitudinal (x) de la trémie (7).

5. Installation selon la revendication 4, caractérisée en ce qu'elle comprend une pluralité d'injecteurs (12) distribués sur la surface latérale de la trémie (7) dans des configurations prédéterminées, les injecteurs (12) étant orientables avec des inclinaisons variables par rapport à l'axe longitudinal (x) de la trémie (7).

6. Installation selon la revendication 1, caractérisée en ce qu'elle comprend au moins un régulateur de débit (13) disposé sur le conduit convoyeur (11) pour réguler le flux d'air en entrée de la trémie (7).

7. Procédé pour ajouter de la colle à une masse de matériau ligneux en vrac sous forme de particules, comprenant les phases suivantes:

fournir une masse de matériau ligneux en vrac sous forme de particules d'un dispositif (2) à une trémie de chargement (7) d'un mélangeur (4) pourvu d'une entrée (4a) pour la masse de matériau ligneux en vrac et d'une sortie (4b);

envoyer un flux d'air chaud dans la trémie (7) au moyen d'un thermo-ventilateur (10);

nébuliser et injecter de la colle dans la masse de matériau ligneux en vrac en amont de l'entrée (4a) du matériau ligneux dans le mélangeur (4) au moyen d'au moins un injecteur (12);

envoyer la masse de matériau ligneux une fois mélangé à la colle à l'intérieur du mélangeur (4) où un arbre mélangeur (14) est disposé pour mélanger et rendre homogène la distribution de la colle;

envoyer la masse de matériau ligneux mélangé à la colle sur de successives stations de travail au travers de la sortie (4b) du mélangeur (4), caractérisé en ce qu'une bouche de sortie du thermo-ventilateur (10) est reliée à un conduit convoyeur (11) débouchant dans un canal (9) disposé intérieurement à la trémie (7), et ledit au moins un injecteur (12) est associé à une surface latérale de la trémie (7) en correspondance d'une de ses parties en aval d'une sortie (9b) du canal (9) et

du même côté que cette dernière, de sorte que le flux d'air chaud sortant de la sortie (9b) du canal (9) effectue une action de retenue sur la masse de matériau ligneux, en formant un front compact sur lequel la colle est nébulisée.

8. Procédé selon la revendication 7, caractérisé en ce que la colle est injectée et nébulisée par une pluralité d'injecteurs (12) distribués sur la surface latérale de la trémie (7) dans des configurations prédéterminées, la pluralité d'injecteurs (12) étant orientable avec des inclinaisons variables par rapport à un axe longitudinal (x) de la trémie (7).

Drawing