EP2621694B1 - Device for the production of macro-fibres from wood trunks and method for the production of a wood composite material by means of such a device - Google Patents

Description

The invention relates to a device for extracting macro fibers from logs and a method for producing a wood composite material by means of such a device.

State of the art

There are numerous wood materials known that are based on wood (fibers) in various crushing stages and each have special properties that maintain the properties of the starting product, namely wood, to varying degrees. For the material wood, the pronounced anisotropy must always be taken into account. In particular, wood in the fiber direction exhibits high tensile strength and rigidity. Rigidity and strength drop considerably across the fiber. Consequently, even a small fiber deviation has significant effects. Furthermore, defects are to be considered, for example due to branches that also affect the structural behavior of wood.

In practice, wood is used on the one hand as lumber, ie in the form of essentially prismatic beams. Through a variety of wood-based materials, the heterogeneous material wood can increase with an increasing degree of fragmentation be homogenized. However, this is accompanied by a loss of strength. As known wood materials are chipboard, OSB (Oriented Strand Board), "veneer strip materials", such as Parallel Strand Lumber (PSL), Veneer Strip Lumber (VSL) and Veneer Strip Panel (VSP), plywood, fiberboard, wood plastic composites and the comparatively new material called scrimber. In contrast to the other known wood-based materials, the wood is not cut in the latter group of wood-based materials but, as far as possible, is separated parallel to the fiber orientation. This is done essentially by squeezing between profiled rollers, in which essentially pressure, transverse tensile and shear forces are applied.

A corresponding method is for example in the US 3,674,219 described. Similar devices and associated methods are disclosed in U.S. Patent No. 5,376,837 WO 89/11383 A1 , of the EP 0 414 758 A1 , of the EP 0 666 155 A1 , of the US 4,122,236 , of the US 4,232,067 , of the US 5,279,691 and the US 4,711,689 described. However, the wood materials hitherto known from this group have a comparatively high density and thus a high weight with regard to the components produced therefrom. Furthermore, the process for producing the so-called macrofibers, ie bundles of wood fibers, has proven to be in need of improvement.

Presentation of the invention

The invention is therefore an object of the invention to provide an improved device for dissolving macro fibers of logs and a method for producing a wood composite material by means of the device.

The solution to this problem is achieved by the device described in claim 1.

As a result, the device according to the invention has at least one pair of rollers with mutually directed, largely circumferentially extending cutting webs whose distance from the roller axis to the edge increases and decreases towards the axial center of the roller. In other words, the tips of the cutting ribs are spaced from the roller axis such that they are farther from the roller axis at the edges of the roller than at the center. As a result, an adaptation to a "half" of a cross-section usually largely round of the construction trunk takes place in an advantageous manner. By two opposite and the tree trunk between them receiving roles with cutting webs with the described contour can be done a particularly good unlocking a tree trunk. Furthermore, results from the provided with (in cross section as peaks recognizable) cutting webs the introduction of shear and compressive forces, which cause a corresponding splitting effect in the wood.

The resulting so-called macrofibres have a thickness of 0.5 mm to 3.0 mm, preferably 1.5 mm to 2.5 mm and a width of 2 mm to 6 mm, preferably 3 mm to 5 mm. The maximum length of the macrofibres is essentially determined by the length of the worked sections of logs. In that regard, macrofibres can be achieved from a few centimeters to several decimeters, depending on the length of the processed stem sections.

Due to the described squeezing method and the following described method for releasing the squeezed macrofibers from the stem portion, the longitudinal axis of the wood fibers contained in the macrofiber substantially follows the longitudinal axis of the macrofibers, so that the latter are characterized by very high strength and stiffness values nearly equal to those of reach perfect wood. It should be noted that the cutting webs may themselves have different (radial) heights, and may be provided on a roller with a constant over the axial length diameter, that results in the different distance from the roller axis by the different height of the cutting webs. However, the differential removal of the (for the action on the wood) crucial tips of the cutting webs from the roll axis can also be formed in that the cutting webs have a substantially constant height, but are provided on a roller, which in diameter towards the edges increases.

Preferred developments are described in the further claims.

In order to enable processing of a trunk of several, in particular numerous pages, without having to rotate between individual processing steps, it is advantageous to provide several, in particular two to six pairs of rollers, which are accordingly offset by 90 ° to 30 °. In other words, in the case of two pairs of rollers, the processing takes place first in one direction and subsequently in a direction perpendicular thereto. For example, six pairs of rollers, the processing takes place successively in directions that are offset by 30 ° to other directions. Due to the uniformity can be provided, the processing in a first direction first in a second, this offset by 90 ° direction and then to the latter direction by 30 °, 60 ° or another Offset the number of degrees. Alternatively, the logs may be rotated after each pass through a suitable angle, for example 90 °, 45 ° or 30 °, and subsequently machined at a different angle. The detachment of the macrofibres from the root surface as described below can be done after each pass, after a few passes or after all passages or after one, several or all roller pairs.

When using low-cost small logs with diameters up to, for example, 15 cm, a number of 12 to 16 has proven to be advantageous for the number of cutting webs on a roll in the first tests. As a result, tree trunk sections can be processed in conventional processing sizes in an advantageous manner. For larger diameters, the number is increased accordingly.

The height of the cutting webs, in other words the distance of the tip of the respective cutting web from the surface of a roll, which in this case has a substantially constant cross-section, have been found to be advantageous for small wood 10 mm to 30 mm. It should be noted in particular that the cutting webs penetrate to some extent in the processed tree trunk section, but macrofibers that jam between individual cutting bars must be removed from these.

For the arrangement of the cutting ribs, a design has proven to be favorable, in which the tips of the cutting ribs are arranged substantially arcuate. In extreme cases, this arc can correspond to a semicircle. However, also by other "flatter" bow shapes can be processed advantageously a large part of the tree section.

For the opening angle of the wedge at the top of the cutting ribs, an order of magnitude of 40 ° to 90 ° is currently preferred.

In first experiments with small wood, a diameter of the rolls of 150 mm to 300 mm and an axial length of 100 mm to 150 mm has also been found to be favorable. For production facilities with high capacity and / or larger wood diameters significantly larger role dimensions are estimated as favorable. For example, roll diameters of up to about 500 mm and roll lengths of up to about 400 mm are conceivable.

In order to apply the necessary forces for squeezing the logs to be processed, it is further preferred to form at least one roller of a respective pair of rollers in the radial direction movable and pressurizable.

In order to remove the triggered macrofibers in a simple manner between the respective cutting webs, a so-called wiper is arranged between at least two cutting webs of at least one roller, which may be advantageously wedge-shaped in order to guide the macrofibres over the wedge surface. Alternatively, a circumferential eccentric disk may be provided substantially at the base of the profile between at least two cutting webs, as shown in FIG US 4,364,423 , which is made in this regard the subject of the present application is disclosed. Another alternative is provided instead of the eccentric disc provided cable, ropes or wires.

Although individual macrofibers can become trapped between the cutting webs, other macrofibres, in particular deeper ones, are merely separated, but not completely detached from the processed root section. To solve these fibers, the inventive Apparatus preferably has a cutting drum arranged in the machining direction after at least one pair of rollers, which has at least one largely axially extending cutting edge on the outer side and cooperates with at least one pressing and rotating element for rotating and pressing wood logs against the cutting drum. As can be seen, the pressing and rotating element presses the log against the cutting drum and rotates the latter, so that the cutting edge arranged on the outside of the cutting drum can engage in the partially released fibers and completely loosen them. It is particularly advantageous in this connection if the engagement with the partially released macrofibres takes place over a considerable, in particular the entire axial length of the processed trunk section, so that the macrofibers advantageously remain substantially intact. This is ensured by the described, axially extending cutting edge. It should be noted that several pressing and rotating elements, in particular rollers, with or without pressurization, can be used. For example, such an element can largely provide pressure on the side while another element supports the processed log from the underside.

For the effect of the pressing and rotating element, it has been found to be advantageous if this with Mitnehmer, such as. axially extending webs is provided to improve in particular the rotation of the stem portion. As a driver, for example, spines and / or teeth can be used.

In order to further improve the function of the pressing and rotating element, it has been proven to store this movable, in particular slidable or pivotable and to apply pressure in the direction of the cutting drum. This allows a log to be processed always reliable to the Cutting drum are pressed, which reliably dissolves the macrofibres from the log.

It has also been found to be favorable when the cutting edge (s) of the cutting drum impinges on the outside of the trunk at the level of the trunk center axis / impinge. For this purpose, at least one wedge-shaped ramp can advantageously be provided between the cutting drum and the pressing and rotating element, on which the log is always held at a height, on which the cutting edge, due to the decreasing diameter of macro fibers (n) engage the cutting drum approximately at the level of the trunk center axis.

In particular, therefore, an angle of about 45 ° and / or a highest point approximately at the level of the central axis of the cutting drum is preferred for the described ramp. As a result, the desired conditions described above can be achieved particularly reliably.

For the cutting drum so far a diameter of about 250 mm to about 500 mm, in particular about 300 mm has proven to be favorable. For the pressing and rotating element diameter between 100 mm and 200 mm, in particular about 120 mm are preferred for the same reason.

Furthermore, it should be noted that the number of cutting edges on the cutting drum must be adapted to the rotational speed of the cutting drum and / or of the pressing and rotating element. In first attempts, however, a number of two to eight cutting has proven to be favorable.

On the other hand, the solution of the abovementioned object is achieved by the method described in claim 17, and preferred further developments can be found in the following Claims and will be described in part with reference to the following also described, thus produced wood material.

1. a) Herstellen von Makrofasern;
2. b) Ausrichten der Makrofasern;
3. c) Aufbringen des Bindemittels;
4. d) Schließen einer Presse; und
5. e) Aufschäumen des Bindemittels.

Accordingly, the method comprises the following steps, wherein the preparation of the macrofibers may include drying thereof:

1. a) producing macro fibers;
2. b) aligning the macrofibres;
3. c) applying the binder;
4. d) closing a press; and
5. e) foaming the binder.

In the method according to the invention, the binder is applied to the aligned macrofibers (sequence of steps: a, b, c, d and e). Alternatively, the binder may also be applied prior to aligning the macrofibre (sequence of steps: a, c, b, d and e).

The method may advantageously be continuously, e.g. be carried out by means of a belt press.

To make the wood composite of the present invention, the macrofibers are dried and oriented substantially uniaxially (i.e., in parallel) on press sheets or dies. The binder is applied between and / or on the aligned macrofibers. The application of the binder can be carried out by methods established in the wood industry, e.g. Spray or gluing or gluing.

In a preferred embodiment of the method according to the invention, the foaming time of the binder is adjusted so that the foaming process begins predominantly only after the press has been closed. That is, the binder system is chemically adjusted so that the start time for the Foaming is delayed so that the press or mold can be closed before it comes to a significant foam development.

When closing the press or the mold, the macrofibers are preferably only minimally compressed, so that the density of the wood composite material produced does not differ significantly from the density of the wood used. Since the macrofibers are compressed only insignificantly in the process according to the invention, the sources occurring in the event of later contact with water or when stored in water can be minimized or avoided. As a result, swelling values can be obtained which are in the range of the swelling of the used wood or even below. This is a significant advantage over conventional wood-based materials, which have a mostly high density of wood and thus have a significantly higher swelling than the wood used in contact with water.

In the closed mold or press, on the one hand, the externally applied pressing pressure acts, on the other hand, a foaming pressure develops due to the foaming of the binder, so that the binder substantially completely penetrates the network of macro fibers and wets them substantially completely on their surface. The macrofibers are thus surrounded by a binder matrix and are thus well protected against moisture absorption.

Since the binder is introduced by the expansion of the binder in the network of macrofibres, creates a very homogeneous material with uniform density, in which almost all the cavities are filled with the foam structure and the fibers are almost completely surrounded by foam (enveloped).

In addition, the inventive method, in particular when using a two-component

Polyurethane system as a binder, the advantage that only insignificantly heat must be supplied to start the cure. The necessary heat can already be introduced by slight preheating of the macro fibers (for example to 30-90 ° C., preferably 50 ° C.).

Since the binder is brought into contact with the macrofibres only just before it is cured, substantially 100% of the binder is available for bonding and "sheathing" the chips.

If it is possible to adjust the binder system so that it cures completely in the press, then the press can be reopened immediately. Even with incompletely cured panels of the wood composite material according to the invention, however, the panels are not destroyed by so-called splitters in contrast to conventional wood-based panels. Due to a possible post-hardening, the wood composite material according to the invention merely causes attrition.

Thereby, a novel composite wood material can be produced which has a density of 200-550 kg / m ³ and a stiffness measured in the 4-point bending test according to EN 789 of 4,000-12,000 MPa, wherein the wood composite macrofibers with a degree of slimming (ratio of length to Thickness of the fibers) greater than 20 and comprises a binder, and the binder has a foam structure.

The wood composite according to the invention has a density of 200-550 kg / m ³ , preferably 300-550 kg / m ³ . The stiffness measured in the 4-point bending test according to EN 789 is 4,000-12,000 MPa, preferably 5,000-12,000 MPa, particularly preferably 6,000-12,000 MPa. In a particularly preferred embodiment, the wood composite material has a density of 300-550 kg / m ³ and a rigidity of 6,000-12,000 MPa.

The wood composite according to the invention comprises macrofibres made of wood with a degree of slimming (ratio of length to thickness of the fibers) greater than 20.

Preferably, the macrofibers used have a length of 100-400 mm, more preferably 150-300 mm. It is obvious to the person skilled in the art that it can not be ruled out in terms of production technology that the fibers used always comprise a certain proportion of shorter fibers.

The wood composite according to the invention further comprises a binder, which has a foam structure in the cured state. The binder preferably has a predominantly fine-pored foam structure. Particularly preferably, the binder has a foam structure in such a way that 90-95% of the pores have a pore size in the range of 30-500 .mu.m, preferably 50-300 .mu.m, measured by means of a microscope at a section through the material.

In a preferred embodiment, a binder is used for the wood composite according to the invention, which forms a foam having a density of 30-300 kg / m ³ , preferably 80-200 kg / m ³ , with free foaming.

To determine the density with free foaming, the unreacted binder is poured into an open-topped vessel. Due to the chemical reaction, the binder foams up and can expand freely through the opening. After curing, the over-swollen foam is cleanly separated with a knife. The density of the free-foamed binder can be calculated from the previously determined volume and weight of the vessel and the weight of the foam-filled vessel.

Preferably, in the present invention, a binder is used which forms a closed-cell foam structure. Since the fiber in the wood composite according to the invention are almost completely sheathed by the foam and almost all voids between the fibers are foam-filled, the penetration of moisture is reduced or even completely prevented by a closed-pore structure of the foam, resulting in an advantageous behavior of the wood composite material under the action of moisture , such as a low swelling leads.

The wood composite according to the invention thereby has a significantly lower swelling when exposed to moisture compared to conventional wood materials. This is in the range of solid wood or even lower, while conventional wood-based materials usually have a relation to the swelling of the raw wood used significantly increased swelling. For example, when using macrofibres made of spruce wood, thickness swelling dimensions according to DIN 52364 between 2.7% and 6% can be achieved, according to EN 317 between 1.5 and 5%. The spring size for solid spruce according to DIN 52364 is also about 4 to 6% in comparison. In contrast, corresponding chipboard or OSB show swelling dimensions of 7% to 30%.

In order to further reduce the swelling of the wood composite material, the macro fibers used may be modified by suitable measures before further processing. Such measures are, for example, acetylation or impregnation with suitable resins or chemicals such as melamine resin or DMDHEU, thermal modification or other known swell-compensating measures. As a result, the swelling of the fibers is reduced in moisture absorption and the total swelling of the wood composite material particularly low. This allows swelling values of less than 2% to 4% to be achieved. Due to their small thicknesses, the macrofibres used in the wood composite according to the invention can be impregnated very easily. In contrast, the modification of solid wood fails in many cases due to the lack of impregnability of the wood.

In addition, chemical treatment often requires thermal treatment after impregnation of the wood. Here too, the small dimensions of the macrofibers used according to the invention over solid wood prove to be an advantage since the heat more quickly covers the entire wood. The thermal treatment required for such a modification can advantageously be partially or even completely integrated into the subsequent process of producing the wood composite according to the invention.

The binder used according to the invention is preferably a polymer-based binder. For example, epoxy resin, isocyanate (including polyurethane), melamine, urea, phenolic foams or mixtures thereof can be used. More preferably, a polyurethane system is used, such as e.g. a one- or multi-component polyurethane system, in particular a two-component polyurethane system. However, thermoplastic foams such as polystyrene (e.g., EPS or EPX) may also be used.

In a further preferred embodiment, the wood composite according to the invention further contains particles which can be excited by fields, e.g. Iron oxide particles. When such particles are used, the foaming and curing process of the binder can be initiated (started) and / or accelerated by application of a field (e.g., induction, microwave, radio frequency, radiation, etc.). The particles may conveniently be introduced into the binder prior to the production of the wood composite material, but they may also be used separately.

Alternatively, heat, hot air or steam can be used to initiate or accelerate the foaming and curing process of the binder.

The wood composite according to the invention may further comprise suitable additives, e.g. Foaming agents, fillers, pigments, reinforcing fibers (nano, micro or macro) fire or wood preservatives as well as means for swelling, etc., included. These additives can either be added to the binder or introduced separately into the material. Such additives can impart special properties, such as greater hardness or shear resistance, durability, moisture resistance, etc., to the wood composite in a manner known to those skilled in the art.

The wood composite according to the invention is suitable for all products that are made of solid wood or wood-based materials, such as chipboard or OSB, etc. Due to the lower density of the use of the wood composite material according to the invention leads to a lower weight of the products thus produced.

• Schalungsprodukte, wie Schalungsträger, bzw. Teile davon, wie Gurt oder Steg,
• beschichtete oder unbeschichtete Schalungsplatten bzw. Teile davon, wie Mittelschichten oder Deckschichten,
• Bühnenbeläge für Arbeits- und Schutzgerüste,
• Stab- oder flächenförmige Schalungsprodukte in 1-, 2- oder dreidimensionaler Form zur Bildung oder Unterstützung der Schalhaut, und
• verlorene Schalungen oder Teile davon, welche im Bauwerk verbleiben.

Particularly advantageous is the use of the wood composite material according to the invention for products in which it depends not only on the weight on the dimensional stability in moisture exposure and the maintenance of strength or rigidity. Such products include, due to the unprotected use outdoors:

• Formwork products, such as formwork beams, or parts thereof, such as belt or web,
• Coated or uncoated shuttering panels or parts thereof, such as middle or outer layers,
• Stage coverings for working and protective scaffolding,
• Bar or sheet-like formwork products in 1-, 2- or 3-dimensional form to form or support the formwork, and
• lost formwork or parts of it, which remain in the building.

• Holzbauträger aus Vollmaterial oder mit Hohlräumen oder Teile davon, wie Gurte oder Stege (Vorteil: geringes Gewicht, homogene Eigenschaften ohne Schwachstellen wie Äste in Massivholz; Möglichkeit der Herstellung eines Profils (I-Profil oder anderer optimierter Querschnitt ähnlich Metallträgern)),
• Holzbauplatten und Möbelbauplatten (Vorteil: Eigenschaften wie Sperrholz in Bezug auf Statik, Quellung, Feuchtebeständigkeit bei gleichzeitig sehr niedrigem Gewicht und wirtschaftlicher Herstellbarkeit),
• Teile von Holzbauplatten (Deckschichten, Mittelschichten),
• Mittelschichten mit weitgehend stehender Faserrichtung, die aus Blöcken mit paralleler Faserrichtung durch Schneiden quer zur Faser hergestellt werden (Vorteil: Geringes Gewicht, praktisch keine Dickenquellung, wirtschaftliche Herstellung (zB. Substitution Balsastirnholz)),
• Sandwichplatten aus besonders leichter Makrofaser-Mittellage mit tragenden Deckschichten aus geeigneten Materialien wie Furnier, Sperrholz oder auch Kunststoffplatten mit stehender oder liegender Mittelschicht,
• "Dickholzplatten" - homogene Plattenwerkstoffe für Wände und Decken mit Dicken von 5 cm bis >20 cm. (Vorteil: Gewicht, Wärmedämmung, Statik, Feuchtebeständigkeit),
• Dickholzplatte mit Hohlräumen (Vorteil: siehe oben, noch geringeres Gewicht, Materialeinsparung)
• Profile aus Vollmaterial oder mit Hohlräumen verschiedenster Art für Bauteile, Fenster-, Türen und Möbel (Vorteil: Profil ohne Materialverlust herstellbar, Statik, Gewicht)
• Platten, Träger und Profile für den Fahrzeugbau (Vorteil: Gewicht, Statik, Feuchtebeständigkeit)
• Stab- und flächenförmige 2D und 3D Formteile für Holzbau-Fahrzeugbau, Innenausbau und Möbelbau (Vorteil: Herstellbarkeit nahezu beliebiger Formen, Statik, Gewicht)

Other products that can be advantageously prepared from the wood composite according to the invention include:

• Timber contractor made of solid material or with cavities or parts thereof, such as straps or webs (advantage: low weight, homogeneous properties without weak points such as branches in solid wood, possibility of producing a profile (I-profile or other optimized cross-section similar to metal girders)),
• Wooden boards and furniture boards (advantage: properties such as plywood in terms of static, swelling, moisture resistance at the same time very low weight and economic manufacturability),
• Parts of wooden boards (cover layers, middle layers),
• Middle layers with largely stationary fiber direction, which are produced from blocks with parallel fiber direction by cutting transversely to the fiber (advantage: low weight, practically no thickness swelling, economical production (eg substitution balsa end grain)),
• Sandwich panels made of a particularly light macrofiber middle layer with load-bearing cover layers made of suitable materials such as veneer, plywood or plastic panels with a standing or lying middle layer,
• "Thick wood panels" - homogeneous panel materials for walls and ceilings with thicknesses from 5 cm to> 20 cm. (Advantage: weight, thermal insulation, statics, moisture resistance),
• Thick wood panel with cavities (advantage: see above, even lower weight, material savings)
• Profiles made of solid material or cavities of various kinds for components, windows, doors and furniture (advantage: profile can be produced without material loss, statics, weight)
• Panels, beams and profiles for vehicle construction (advantage: weight, statics, moisture resistance)
• Rod and 2D and 3D molded parts for timber construction, interior design and furniture construction (advantage: manufacturability of almost any shape, statics, weight)

In addition, the content of the applicant's application filed on the same day entitled "wood composite material" with regard to all the features of the method for producing the wood composite material and the wood composite material produced thereby is the subject of the present application.

Brief description of the drawings

Fig. 1

eine erfindungsgemäße Vorrichtung in Richtung der Achse eines zu bearbeitenden Holzstammes;

Fig. 2

die in Fig. 1 gezeigte Vorrichtung in Richtung der Rollenachsen;

Fig. 3

einen Abschnitt der erfindungsgemäßen Vorrichtung, bei dem Makrofasern von einem Holzstamm herausgelöst werden, in einer perspektivischen Ansicht;

Fig. 4

eine perspektivische Ansicht eines Teils einer Presse zur Weiterverarbeitung der Makrofasern; und

Fig. 5

einen Querschnitt durch die Presse gemäß Fig. 4 bei der Herstellung eines Holzverbundwerkstoffs aus den Makrofasern.

An exemplary embodiment of the invention illustrated by way of example in the figures will be explained in more detail below. Show it:

Fig. 1

a device according to the invention in the direction of the axis of a log to be processed;

Fig. 2

in the Fig. 1 apparatus shown in the direction of the roller axes;

Fig. 3

a section of the device according to the invention in which macrofibres are detached from a log, in a perspective view;

Fig. 4

a perspective view of a part of a press for further processing of the macro fibers; and

Fig. 5

a cross section through the press according to Fig. 4 in the production of a wood composite material from the macrofibres.

Detailed description of a preferred embodiment of the invention

As in Fig. 1 can be seen, is to be processed log 2 in the direction of its longitudinal extension, ie perpendicular to the plane of Fig. 1 , Passed through the two rollers 1 of a pair of rollers and thereby processed on its outer surface so that liberate first macrofibers, and more macrofibers can be dissolved out in a subsequent processing step in a simple manner. For this purpose, the rollers 1 are provided at their periphery with substantially circumferentially and preferably in a plane substantially perpendicular to the roller axis 22 extending cutting ribs 3, which according to the invention at the edges have a greater distance to the respective roller axis 22, as at the axial center of the respective role 1. In the case shown, the cutting webs 3, as preferred, provided such that their tips are substantially on a sheet, so that this arrangement of the tips is particularly well adapted to the cross-sectionally substantially circular shape of the log 2 to be processed , The webs themselves may be about 5 mm to 10 mm wide (along the axis 22 of the respective roll 1), and the same dimension may exist between two adjacent webs.

As more accurate in the enlarged view of Fig. 1 can be seen, squeeze and split the cutting webs 3 with their tips the outer regions of the log to be processed 2, so that both shear (arrow 4) and crushing forces (arrow 5) are initiated. As a result, so-called macrofibres with a typical thickness of 1.5 mm to 2 mm (measured in the radial direction of the log 2) and a typical width of 4 mm to 5 mm (measured in the circumferential direction of the log 2) are at least partially removed from the log. As described above, the log to be processed 2, the rollers 1 shown several times, each after a rotation through a suitable angle to pass through its angular axis, or it can be successively provided several pairs rotated by a suitable angle pairs of rollers. The bridge tips can also be slightly rounded.

Fig. 2 shows how it can be prevented in each case that completely detached macrofibers between individual cutting ribs 3 jammed. In the embodiment shown, a wedge-shaped scraper 6 is arranged between two at least two adjacent, preferably between all cutting webs 3, which dissolves the macrofibres of the profiled ground between adjacent cutting webs. The tip of the scraper 6 can also be pulled forward over the upper tangent point of the squeezing rollers to reduce wear and improve the discharge of the microfibers, as with the overall dashed scraper 6 'in FIG Fig. 2 is indicated.

In Fig. 3 an area of the device according to the invention is shown in which macro-fibers, which have not yet completely detached from the surface of the log 2, can be dissolved out. The log 2 is in this case pressed substantially in the radial direction against a cutting drum 7, which is provided in the case shown with two axially extending cutting edges 8. The pressing against the cutting drum is carried out by a pressing and rotating element 10, which is essentially formed by a roller, which is provided in the case shown with axially extending webs. As a result, the engagement with the log to be processed 2 is improved. The pressing and rotating element 10 is pivotably mounted on a so-called traverse 11 and further acted upon by the pressure of a gas spring 13. As a result, the log 2 is independent of the feed movement of the traverse in the direction of arrows 12 with constant pressure against the cutting drum. 7 pressed. The pivotable mounting of the pressing and rotating element 10 on the traverse 11 takes place in the case shown by a pendulum fourteenth

In the example shown, a wedge-shaped ramp 15 is also provided. The surfaces of the ramp can be flat or slightly curved. The ramp may have an angle of approximately 45 ° on the side at which the logs 2 are guided to the cutting drum 7, and / or their highest point may be approximately at the level of the axis of the cutting drum 7. As a result, regardless of the thickness of the log 2, in particular after the partial detachment of macrofibres 16 on the surface, the blades 8 of the cutting drum 7 engage substantially at the level of the center axis of the log 2, which is particularly advantageous for the desired effects. As indicated by the arrows in Fig. 3 is indicated, it is preferred that the pressing and rotating element and the cutting drum 7 rotate in the same direction, so that the log 2 substantially "combs" with both said elements in the same direction. Here, the rotary drive of the log 2 by the drive and rotary member 10, and for the interaction between the log 2 and the cutting drum 7 for dissolving out the macrofibers 16, the described, meshing movement has been found to be favorable.

In Fig. 4 In a perspective view, a part of a mold 17 is shown, in which the macrofibres obtained as described above are further processed. First, they are preferably dried and placed on press plates or in the Fig. 4 The mold 17 shown by way of example is largely parallel to one another, ie oriented uniaxially in the direction 18. Between and / or on the aligned macrofibres a binder with a foam structure is applied. This can be done for example by the device 19 shown, which is on the one hand in the direction 18 moves the fibers, and on the other hand, this is vertically reciprocated. The actual application can be done for example by spraying and for example by means of so-called Beleimanlagen and / or Spanblender. Here, the foaming system is set so that the beginning of the foaming is delayed, so that the press, of which a part 17 in Fig. 4 is shown, can be completely closed. When closing the press or mold, the macrofibers are only minimally compressed, so that the density of the material produced does not differ significantly from the density of the wood used.

As in Fig. 5 can be seen acts in the closed press or mold on the one hand, the externally applied pressing pressure 21. On the other hand, by the foaming of the binder inside a pressing pressure, indicated by the arrows 20, whereby the binder component penetrates the network of macrofibers and this almost on their surface completely wetted. Accordingly, the macrofibers are essentially completely surrounded by a plastic matrix. This is done in an advantageous manner by expanding the binder. Due to this closure, the macrofibres are well protected against moisture absorption.

example

Macrofibers are dried by a warm (50 ° C) air stream and several days in a room climate of 20 ° C and 65% rel. Humidity stored, resulting in a wood moisture of about 12%. 210 g of the macrofibers are oriented as exactly as possible parallel to one another. 50% of the fibers are placed in an aluminum mold (30 × 12 cm) heated to 50 ° C. and uniformly wetted with 60 g of two components of polyurethane (from RAMPF No. 80 L86 / 4-1). Subsequently, the remaining 50% of the fibers are placed in the mold and the mold is closed, so that the inserted macrofibres are compressed to a height of 16 mm. Due to the chemical reaction of the two components of the polyurethane with the water available in the wood foams this strong. After 30 min. the foam is completely cured and the wood composite material can be removed from the mold.

Claims (18)

1. Device for extracting macro-fibres from wooden logs (2) having at least one pair of rollers (1) with cutting bars (3) running largely peripherally and directed towards one another, characterised in that the distance of the cutting bars (3) from the roller axis of at least one roller (1) of the roller pair increases towards the edge and decreases towards the axial centre of the roller (1), and in that tips of the cutting bars (3) are arranged to be essentially arc-like.
2. Device according to claim 1, characterised in that two to six roller pairs offset by 90° to 30° are provided.
3. Device according to one of the preceding claims, characterised in that the cutting bars (3) are 10 mm to 30 mm high.
4. Device according to one of the preceding claims, characterised in that tips of the cutting bars (3) have an angle of 40° to 90°.
5. Device according to one of the preceding claims, characterised in that at least one roller has a diameter of 150 mm to 500 mm and/or an axial length of 100 mm to 400 mm.
6. Device according to one of the preceding claims, characterised in that at least one roller (1) of a particular pair can be moved in radial direction and can be exposed to pressure in the direction of the other roller of the roller pair.
7. Device according to one of the preceding claims, further having at least one cutting drum (7) arranged downstream of the roller pairs in processing direction and having at least one cutting edge (8) running largely axially on the outer side and at least one pressing and rotation element (10) for rotating and pressing wooden logs (2) against the cutting drum (7).
8. Device according to claim 7, characterised in that the pressing and rotation element (10) is provided with at least one follower, such as axially running bars.
9. Device according to claim 7 or 8, characterised in that the pressing and rotation element (10) is movable, in particular is mounted to be slidable or pivotable and is exposed to pressure in the direction of the cutting drum (7).
10. Device according to one of claims 7 to 9, characterised in that at least one wedge-shaped ramp, which preferably has an angle of about 45° and/or the highest point is approximately at the level of the central axis of the cutting drum (7), is provided between the cutting drum (7) and the pressing and rotation element (10).
11. Device according to one of claims 6 to 10, characterised in that the cutting drum (7) has a diameter between 250 mm and 500 mm, in particular about 300 mm and/or the pressing and rotation element (10) has a diameter of 100 mm to 200 mm, in particular about 120 mm.
12. Method for producing a wood composite material having the following steps:

    - producing macro-fibres by means of a device according to one of the preceding claims;

    - drying the macro-fibres;

    - aligning the macro-fibres largely in parallel;

    - application of a binder which has a foam structure;

    - closing a press; and

    - foaming the binder.
13. Method according to claim 12, wherein the binder system is set so that the foaming process starts predominantly only after closing the press.
14. Method according to one of claims 12 or 13, wherein the foaming and curing process is initiated and/or accelerated by an electromagnetic field.
15. Method according to claim 14, wherein in addition to the binder, particles are applied which may be excited by fields.
16. Method according to claim 15, wherein the particles are present in the binder.
17. Method according to one of claims 12 or 13, wherein the foaming and curing process is initiated and/or accelerated by heat, hot air or steam.
18. Method according to one of claims 12 to 17, which is carried out as a continuous method, for example by means of a belt press.

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