EP1623807B1 - Method and device for producing a wood-based object - Google Patents

Abstract

The method involves chipping timber into wood chips, breaking up thread-like fiber material into individual fibres, and distributing the fibers in the wood chips. A binder is applied at least to the wood chips, and a chip cake is formed. The cake is pressed to form a wooden body or part of a wooden body. The fiber is typically glass, carbon, plastics, metal, cellulose, hemp, flax, jute, coconut fiber etc. (not claimed). An independent claim is included for the use of a fiber spray head with a cutting device for breaking up fiber material.

Description

The present invention relates to a method for producing a wooden material body, wherein the wood material is cut into wood chips. Furthermore, the invention relates to a corresponding device for producing a wooden material body with a means for cutting wood material into wood chips.

In the following, the term wood material body means a body made of pressed wood particles, for example a plate-shaped body, in particular a wood-based panel. By a wood-based panel according to the invention is meant any form of particle or fiberboard such as medium density fiberboard (MDF), high density fiberboard (HDF) or very low density fiberboard (LDF). Chipboard or OSB boards (Oriented Strands Board) also fall under the term wood-based board. It is also conceivable to provide a wood-based panel of several, glued together individual plates.

For the purposes of the invention, the term shavings means chips, shavings or comparable particles produced by machining of any shape and size.

It is known from the prior art to produce wood-based panels, for example chipboard, from one or more layers of wood chips provided with a binder and pressed. An essential criterion for the quality of particular plate-shaped wood material bodies are their strength properties. These depend essentially on the used Spangeometrie and the amount and type of binder used. It is obvious that larger chips lead to a better cohesion, while small and micro chips can less intimately mesh. Furthermore, small chips imply a larger chip surface to be glued than large chips, which is why the same proportion of binder relative to the chip weight here entails substantially poorer strength properties of the finished board.

In order to improve the strength properties of a chip made of chips, it is known from the prior art, for example WO 99/32285 A1 It is known to provide a fabric, scrim or web of natural fibers which is incorporated within a layer or between individual layers of wood chips provided with binder. Similarly, the GB 2 248 256 A the addition of fiberglass or carbon fiber material in the form of woven mats or strips. Also threads of glass fibers or other materials can be placed on the chip cake, as for example in the US 4,514,258 is described. However, the problem here is the relatively high expenditure on equipment, which is why the application of this technology could not prevail until today.

From the EP 0 771 259 B1 It is known to use for producing only fiber-reinforced plastic parts, a device or a fiber spray head for the provision of fibers. Also a fiber spray head describes the GB 1 360 803 A but for the exclusive addition of the reinforcing material to liquid or viscous cement applied to a concrete floor.

The DE 1 653 161 discloses a method of the type mentioned, namely for the production of a wooden material body, in which wood material is cut into wood chips. To improve the strength properties of the wood-based material body produced according to this document ribbons or strips of fibers are placed on the chip cake formed to a chip mat. The wood-based material body is then produced from the chips cake reinforced in this way. The problem, however, is that the reinforcement in the later wood material body is not optimal, especially not in all levels, distributed and in this way the strength properties are not improved at least for a load in the direction of the plate longitudinal plane of a corresponding wood-based panel to any appreciable extent.

The invention is based on the last-mentioned document, the technical problem of providing a method and an apparatus for producing a wood material body, whereby the strength properties are further improved.

The above-indicated technical problem is solved according to a first teaching of the present invention in a method of the type mentioned by the features of the characterizing part of claim 1.

The above-indicated technical problem is further solved according to a second teaching of the present invention in a device of the type mentioned by the features of the characterizing part of claim 14.

Advantageous embodiments are the subject of the dependent claims and will be described in more detail below.

According to a preferred embodiment, a material of artificial raw materials such as glass, carbon, plastic, metal, etc., or a material of natural raw material such as cellulose, hemp, flax, jute, coconut, etc. is used as a thread-like fiber material. Mixtures of these materials are conceivable as fiber material.

According to a further preferred embodiment, such a thread consists of a plurality of parallel individual fibers or fiber parts.

According to a further preferred embodiment, the threads, ie the filamentary fiber material, are delivered in the form of one or more coils, onto which one or more threads are wound. It is also conceivable that the threads of several coils are connected to each other, so that there is a continuous thread for continuous production, which runs over a plurality of coils.

According to a further preferred embodiment, a comminution of the filamentary fiber material takes place transversely to the longitudinal direction of the thread.

According to a further preferred embodiment, the sprinkling of the fibers takes place with a fiber spray head, in particular with a fiber spray head provided with a cutting device. With such a fiber spray head, which in particular has a cutting device, the comminution to individual fibers can also take place.

According to a further preferred embodiment, a binder is applied to the fibers immediately before the comminution and / or spreading. The application of the binder, which is preferably the same binder as is used for application to the wood chips, is preferably carried out with a fiber spray head, in particular a fiber spray head provided with a cutting device.

According to a further preferred embodiment, the fibers are directly after the comminution of the filamentary fiber material in particular individually in the Wood chips sprinkled or sprinkled on the wood chips. It is also conceivable to collect the fibers first and then to mix with the wood chips.

According to a further preferred embodiment, the fibers are pretreated chemically, for example by impregnation, or mechanically, for example by stretching.

According to a further preferred embodiment, an impregnation and / or stretching of the fibers takes place in a fiber spray head of the aforementioned type or immediately before or after. The same applies to the application of the binder to the fibers.

According to a further preferred embodiment, the fibers are at least partially interspersed in a predetermined direction. It is also conceivable to scatter the fibers in certain places in greater quantity than in other places.

According to a further preferred embodiment, a plurality of scattering heads, in particular a plurality of fiber spraying heads of the type described above, are used.

According to a further preferred embodiment, the fibers are interspersed in a predetermined length, in particular in a length of 10 to 50 mm. It is also conceivable to co-effect fibers of different lengths at the same time. For example, using multiple litter or fiber spray heads, each head can incorporate fibers of a different length.

• Variable Platzierung im Plattenaufbau: Durch die verhältnismäßig geringen apparativen Kosten und geringen Baugrößen können mehrere Streuköpfe vorgesehen sein, die eine im Schichtaufbau des Holzwerkstoffkörpers bzw. der Holzwerkstoffplatte variable Einbringung und damit Lage der Fasern ermöglicht. Es kann für die Bildung des Spänekuchens immer mindestens ein Streuaggregat für die beleimten Späne vorgesehen sein, in oder zwischen die ein Fasersprühkopf, auch Faserstreukopf genannt, integriert werden kann. Das Integrieren kann auch nachträglich in bestehende Vorrichtungen erfolgen. Für Verlegplatten, die ungeschliffen weiterverarbeitet werden, können die Fasern an den Oberflächen liegen, da so die Auswirkung auf die Biegefestigkeit optimiert ist. Zwischen Deckschicht und Mittelschicht können die Fasern vorgesehen werden, wenn eine geschliffene Oberfläche ermöglicht sein soll. Denkbar ist auch, die Fasern innerhalb einer evtl. mehrschichtigen Mittelschicht einzubringen.
• Variable Faserlänge:
  • Durch die Verwendung von Fäden als Ausgangsprodukt für die Fasern ist eine große Bandbreite von Faserlängen denkbar. Sinnvolle Bereiche sind 10 bis 50 mm. Auch andere Längen sind denkbar, abhängig von der Art der Faser und abhängig von den gewünschten Eigenschaften, insbesondere Festigkeitseigenschaften.
• Variable Vorbehandlung:
  Eine Vorbehandlung der Fäden könnte chemisch, zum Beispiel durch Imprägnierung, oder mechanisch, zum Beispiel durch Streckung, geschehen. Im Zuge der Verarbeitung wäre aber ebenso eine andere Behandlung denkbar, insbesondere eine Beleimung, das heißt zum Beispiel ein Aufbringen von Bindemittel.
• Variabler Rohstoff:
  Je nach gewünschten Eigenschaften der fertigen Platte können verschiedene Faserarten verarbeitet werden. Neben den erwähnten Rohstoffen sind insbesondere dünne Metalldrähte denkbar.

The following advantages are achieved with the method according to the invention and the device according to the invention:

• Variable placement in the plate structure: Due to the relatively low equipment costs and small sizes several scattering heads can be provided, which allows a variable in the layer structure of the wood material body or the wood-based panel introduction and thus position of the fibers. It can always be provided for the formation of the chip cake at least one scattering unit for the glued chips, in or between which a Fasersprühkopf, also called Faserstreukopf, can be integrated. The integration can also be done later in existing devices. For slabs that are processed unpolished, the fibers can be on the surfaces, as this optimizes the effect on the flexural strength. Between the cover layer and the middle layer, the fibers can be provided, if a ground surface is to be made possible. It is also conceivable to introduce the fibers within a possibly multi-layered middle layer.
• Variable fiber length:
  • By using filaments as the starting material for the fibers, a wide range of fiber lengths is conceivable. Sensible areas are 10 to 50 mm. Other lengths are conceivable, depending on the type of fiber and depending on the desired properties, in particular strength properties.
• Variable pretreatment:
  A pretreatment of the threads could be done chemically, for example by impregnation, or mechanically, for example by stretching. In the course of processing, however, another treatment would also be conceivable, in particular a gluing, that is, for example, applying a binder.
• Variable resource:
  Depending on the desired properties of the finished plate different types of fibers can be processed. In addition to the above-mentioned raw materials, in particular thin metal wires are conceivable.

Finally, a particularly preferred embodiment for a fiber spray head will be described below, as it can be used and designed according to the invention. It will be described below by way of example with reference to a mixing head for use in the production of plastic parts. In other words, although the following description refers to an application for the production of plastic parts, according to the present invention, it can be correspondingly applied to the production of wood-based material articles:

Device for producing reinforced plastics with reinforcing fibers with a mixing chamber for producing a mixture of chemically reactive plastic components, with a mixing chamber downstream cylindrical outlet chamber (7, 70) in which a tubular extension (11,81) is located, whose outer diameter is less than the inner diameter of the outlet chamber (7; 70) and with the inner wall of the outlet chamber (7,70) includes an annular flow channel for the mixture of the chemically reactive plastic components, wherein in the tubular extension (11,81) into the outlet chamber (7, 70) opening fiber feed channel is arranged, wherein the tubular projection (11,81) on the end face (8,80 ') of a reversibly guided in the outlet chamber (7,70) cleaning piston (8,80) is arranged and that the fiber Conveyor channel conveyor rollers (140, 150) are associated with a cutter (160) for supplying fibers.

When using flowable plastic in the form of molten thermoplastic plastic so far was also only the opportunity to introduce long reinforcing fibers in the form of the above-described fiber mats in separate steps in the plastic part.

In a preferred embodiment, the flowable plastic is a mixture of chemically reactive plastic components in a cylindrical Outflow chamber passed, in which a cleaning piston is reversibly guided and extends through the center region of a fiber feed channel. As a result of a arranged on the front side of the cleaning piston tubular neck an annular flow channel is created in the outlet chamber through which forms a tubular mixture flow, in the center region of the fiber feed channel opens, whereby the possibility exists to introduce long reinforcing fibers in the flowable plastic. The fiber conveying channel, preferably arranged in pairs at its inlet opening arranged conveying rollers which pull an endless fiber strand from a spool and shoot at high speed through the fiber conveying channel. These conveyor rollers are provided with cutting means, whereby the Verstärkungsfasem can be divided into sections of a certain length. If a plurality of conveyor roller pairs with different diameters for producing fiber sections of different lengths arranged side by side and these conveyor rollers can be positioned in any order to the inlet opening of the fiber conveyor channel, then the flow of flowable plastic in time sequence reinforcing fibers can be added in different lengths. This is particularly advantageous when the device for generating the two streams of flowable plastic and long reinforcing fibers is passed over the surface of a plastic molding tool to a flat, with long reinforcing fibers interspersed plastic part to create. By varying the length of the fiber sections by Zupositionierung the corresponding conveyor rollers on the inlet opening of the fiber conveying channel, a plastic part can be created, which, depending on the strength requirements and shape, fibers of different lengths. Thus, it may be advantageous, for example, to cover strongly inclined surface areas of the molding tool with flowable plastic which contains particularly long reinforcing fibers. Likewise, it can be ensured by different speed of the conveyor rollers that the plastic part is traversed in certain areas with fibers in higher or lower density. The reinforcing fibers are completely encased in flowable plastic.

The created with the above device annular flow channel can be created instead of a fixedly connected to the cleaning piston tubular approach with the help of a dip tube, which passes through the cleaning piston centrally and forms the fiber feed channel. There is the possibility that the cleaning piston can be moved independently of the dip tube. The dip tube may pass through the cleaning piston and its hydraulic actuators and be secured in the housing of the device. This results in the advantage that the means for generating long reinforcing fibers and for transporting these reinforcing fibers can be fixed to the housing through the fiber conveying channel in the dip tube.

Instead of the above-described devices for generating a tubular flow of flowable plastic and an annular nozzle can be used, in the center region of the fiber conveying channel or channel opens to promote other fillers.

• Fig. 1 in Seitenansicht den Schnitt durch einen Mischkopf zur Erzeugung eines Gemischstromes aus chemisch reaktiven Kunststoffkomponenten mit einer Einrichtung zur zusammenführung des Gemischstromes mit einem Strom aus langen Verstärkungsfasern, und
• Fig. 2 einen Mischkopf nach Fig. 1 mit einer abgewandelten Einrichtung zur Zusammenführung des Gemischstromes mit einem Strom aus langen Verstärkungsfasern.

Embodiments of the Fasersprühkopfes are explained in more detail with reference to the drawing. It shows:

• Fig. 1 in side view the section through a mixing head for generating a mixture stream of chemically reactive plastic components with a means for combining the mixture stream with a stream of long reinforcing fibers, and
• Fig. 2 a mixing head after Fig. 1 with a modified means for merging the mixture stream with a stream of long reinforcing fibers.

The Fig. 1 shows the mixing head of a polyurethane plant in which chemically reactive plastic components, such as polyol and isocyanate are mixed to form a mixture of flowable plastic. According to Fig. 1 a control piston 2 is arranged in a mixing chamber 1, which is guided reversibly in the mixing chamber 1 by means of a hydraulic piston 3. In the mixing chamber 1 lead perpendicular to the drawing plane leading injection ports (not shown) for the chemically reactive plastic components. With the control piston 2, the injection ports are opened and closed at the same time, likewise fulfills the Control piston 2 the function to expel the reaction mixture formed in the mixing chamber 1 from the reactive plastic components from the mixing chamber 1 and to clean the walls of the mixing chamber 1 of the reaction mixture.

At right angles to the mixing chamber 1, a calming chamber 4 is arranged, in which a first cleaning piston 5 is reversibly guided. The first cleaning piston 5 can be actuated by means of a second hydraulic piston 6.

At the settling chamber 4 is followed at right angles to an outlet pipe 7, in which a second cleaning piston 8 is reversibly guided. The second cleaning piston 8 can be actuated by means of a third hydraulic piston 9. The outlet pipe 7 opens with its discharge opening 10 in the mold cavity of an injection mold (not shown).

The second cleaning piston 8 and the third hydraulic piston 9 are centrally penetrated by a dip tube 11 which is fixed in the cylinder cover 12 of the hydraulic cylinder 13.

Through the dip tube 11 fillers are introduced from the outside to directly to the discharge opening 10 in the flowing out of the outlet pipe 7 reaction mixture.

Particularly suitable is the dip tube 11 for the introduction of long fibers, for example for introducing strands of glass fibers or carbon fibers.

The fiber strands are detected by conveyor rollers 14 and 15 and injected through the immersion tube 11 arranged in the central bore 83 'into the reaction mixture.

One of the conveyor rollers 14 may be provided with cutters in the form of four distributed on the roll circumference knives 16, whereby the fiber strand sections can be divided into certain lengths. The length of the sections can be varied as required. In principle, fiber strands previously divided into length sections can also be injected through the dip tube 11 into the reaction mixture via the conveyor rollers 14 and 15. The fiber strand is first detected by the feed roller 17 and the pressure roller 18 after insertion through the insertion opening 17, whereupon the fiber strand passes between the two conveyor rollers 14 and 15 and is shot centrically thereof through the dip tube 11.

Depending on the length of the dip tube 11, the long fiber strands or other fillers in any areas of the outlet pipe 7 can be injected into the reaction mixture. The fibers or other fillers arrive centrally in the reaction mixture flowing through the outlet pipe 7 and are thus uniformly distributed in the casting during the transfer into the mold cavity.

The promotion of fiber strands or other Fillers through the dip tube 11 may be assisted by a fluidizing agent, such as pressurized gas, introduced through the orifice 19. Instead of or in addition to the fluidizing agent, other fluid agents may also be introduced into the reaction mixture. For example, in addition to fiber strands, fillers with a fluidizing gas can additionally be introduced into the reaction mixture.

The invention is explained using the example of a dip tube 11, which passes through the cleaning piston 8 reversibly guided in the outlet pipe 7. However, a dip tube of the type described can also be arranged in the control piston 2 and in the mixing chamber 1 of a simple straight mixing head, the mixing chamber 1 no settling chamber 4 is arranged downstream.

The dip tube 11 can also be arranged in a mixing head, which consists only of a mixing chamber 1 and a settling chamber 4, in the cleaning piston and in the settling chamber.

The Fig. 2 shows one after the mixing head Fig. 1 corresponding mixing head, wherein the same reference numerals 1 to 6 were used for the matching functional elements.

At the calming chamber 4 is followed at right angles to an outlet pipe 70, in which a cleaning piston 80 is reversibly guided. The cleaning piston 80 is by means of a third Hydraulic piston 90 actuated. The outlet pipe 70 opens with its discharge opening 100 in the mold cavity of an injection mold (not shown).

The second cleaning piston 80 has a tubular extension 81 and the third hydraulic piston 90 has a tubular extension 82. Both the tubular extension 81 and the tubular extension 82 are formed by a tube firmly pressed in the cleaning piston 80, so that the cleaning piston 80, the tubular extension 81 and the tubular extension 82 form a unitary component. The tubular extension 81 and the tubular extension 82 may also be integrally connected to the cleaning piston 80, i. All parts can consist of a one-piece turned part. By the cleaning piston 80 and the tubular extension 81 and the tubular extension piece 82 extends a central bore 83 which is surrounded by a dip tube 111.

The cleaning piston 80 and the tubular extension 82 pass through a cylinder cover 120.

Through the central bore 83 from the outside fillers are inserted into the flowing from the outlet pipe 70 reaction mixture. The meeting of the fillers with the reaction mixture can be freely selected depending on the length of the tubular extension 81 or the axial positioning of the cleaning piston 80. For the invention is essential that a tubular flow of reaction mixture is generated by the tubular extension 81, in which the fillers are centrally entered. The Fillers are encased in the reaction mixture and mix due to the fact that the fillers and the reaction mixture are conveyed in the same direction of transport in a particularly gentle manner, The inventive method and the devices specified for this purpose are therefore particularly suitable for the addition of long fibers in the reaction mixture , in particular strands of glass fibers or carbon fibers. However, natural fibers such as hemp fibers may also be used.

The fibers (e.g., fiberglass rovings) wound endlessly on a fiber bobbin are gripped by conveyor rolls 140 and 150 and introduced through the central bore 83 into the tubular reaction mixture.

The conveyor rollers 140 and 150 and their drives are mounted on a housing 84 attached to the tubular extension piece 82 and move together with the cleaning piston 80.

One of the conveyor rollers 140 is provided with cutters in the form of knives 160 distributed on the roll periphery, whereby the fiber strand can be subdivided into specific lengths. The length of the sections can be varied as required, depending on the number of knives and roll circumference. The fiber strand is first detected by the feed roller 170 and the pressure roller 180 after insertion through the insertion opening 170, whereupon the fiber strand passes between the two feed rollers 140 and 150 and is shot centrally from the latter into the bore 83.

In principle, the conveyor rollers 140 and 150 and the housing 84 may be fixed independently of the cleaning piston 80 instead of being attached to the tubular extension 82 or the cleaning piston 80, e.g. on the cylinder cover 120, wherein the transfer of the accelerated from the conveyor rollers 140 and 150 fiber strands can be made in the central bore 83 in the tubular extension piece 82 by interposition of a telescopic tube.

The transport speed at which the fiber strands are shot through the central bore 83 is matched to the flow rate of the tube-like reaction mixture flow according to the proviso that with intensive and homogeneous mixing of the long fiber sections with the reaction mixture fiber breakage can be excluded in any case. The mixing can e.g. At the same transport speeds of the two elements take place, but it can also be increased by low speed differences and thereby caused at the contact areas between fibers and reaction mixture shear flows, the mixing effects.

In operation, the reaction mixture emerging from the settling chamber 4 is deflected in the outlet chamber 70 and formed by the annular channel, which is formed by the outlet pipe 70 and the tubular extension 81, into a tubular flow stream, in the centric opening of the fillers are entered. The fillers are characterized not brought directly into contact with the reaction mixture but only in the course of a rectified with the reaction mixture transport phase.

Instead of in the embodiments of the Fig. 1 and 2 illustrated mixing heads (reference numerals 1 to 6), which provide flowable plastic in the form of a reaction mixture, the outlet tube 7 and 70 can also be connected to a plasticizing unit, as used in a plastic injection molding machine for the production of plastic parts made of thermoplastic material. Also, a connection to an extruder is possible. Both devices provide flowable plastic in the form of a thermoplastic plastic melt.

Claims (14)

1. A method for producing an engineered wood body wherein wood material is milled into chips, characterized in that further the following steps are performed:

   - disintegrating filamentous fiber material into individual fibers,

   - spreading the fibers in the wood chips,

   - depositing a binder at least on the chips,

   - forming a chip cake using the wood chips and the fibers, and

   - pressing the cake into an engineered wood body or a part of an engineered wood body.
2. The method according to claim 1, characterized in that the filamentous fiber material is a material made of synthetic raw materials, such as glass, carbon, plastics, or metal, or a material made of natural raw materials, such as cellulose, hemp, flax, jute, or coconut, or a mixture of these materials.
3. The method according to claim 1 or 2, characterized in that the filamentous fiber material consists of multiple parallel individual fibers or fiber parts.
4. The method according to one of the preceding claims, characterized in that the filamentous fiber material is provided in form of one or multiple bobbins onto which one or multiple filaments are wound, wherein in particular multiple bobbins are connected to each other in such a way that a continous filament for a continuous production process involving a plurality of bobbins is formed.
5. The method according to one of the preceding claims, characterized in that the disintegration of the filamentous fiber material is performed across the longitudinal direction of the filament.
6. The method according to one of the preceding claims, characterized in that spreading the fibers is performed with a fiber spray head, in particular with a fiber spray head provided with a cutting device (14, 15, 16, 140, 150, 160), wherein in particular the disintegration into individual fibers is performed by the fiber spray head.
7. The method according to one of the preceding claims, characterized in that immediately before disintegration and/or spreading a binder is deposited on the fibers preferably with a fiber spray head, in particular with a fiber spray head provided with a cutting device (14, 15, 16, 140, 150, 160), wherein the binder preferably is the same binder which is deposited at least on the chips after spreading the fibers.
8. The method according to one of the preceding claims, characterized in that the fibers, in particular individually, are spread into and/or onto the wood chips immediately after disintegrating the filamentous fiber material.
9. The method according to one of the preceding claims, characterized in that the fibers are pre-treated chemically, for example by impregnating, or mechanically, for example by stretching.
10. The method according to one of the preceding claims, characterized in that impregnating and/or stretching of the fibers is performed in a fiber spray head, in particular in a fiber spray head provided with a cutting device (14, 15, 16, 140, 150, 160).
11. The method according to one of the preceding claims, characterized in that the fibers at least partially are spread in a predetermined direction and/or at certain places in a greater amount than at other places.
12. The method according to one of the preceding claims, characterized in that multiple spreading heads, preferably multiple fiber spray heads, in particular fiber spray heads provided with a cutting device (14, 15, 16, 140, 150, 160) are used.
13. The method according to one of the preceding claims, characterized in that the fibers are spread in a predetermined length, in particular in a length of 10 - 50 mm and/or in different lengths, preferably by using multiple spreading or fiber spray heads, each head spreading fibers of a different length.
14. A device for producing an engineered wood body, in particular for performing a method according to one of claims 1 to 13, comprising means for milling wood material into wood chips, characterized in that the device further comprises:

    - a cutting device (14, 15, 16, 140, 150, 160) for disintegrating filamentous fiber material into individual cut fibers,

    - means (10, 11, 100, 81) for spreading the fibers in the wood chips,

    - means for depositing a binder at least on the chips,

    - means for forming a chip cake using the wood chips and the fibers, and

    - means for pressing the cake into an engineered wood body or a part of an engineered wood body.

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