EP2121255B1 - Method for the production of flat wood chips - Google Patents

Abstract

The method involves producing a preliminary product from a cellulose containing material, where the preliminary product exhibits a length between 20 and 200 millimeters. The preliminary product is subjected to a hydrothermal treatment. The exposure time of the hydrothermal treatment amounts to three minutes, where the exposure temperature amounts to 40 degree Celsius. The preliminary product is subjected to chipping or splitting.

Description

The invention relates to a method for producing flat chips made of wood, also called "OS chips" ("Oriented Strand").

Structure-oriented wood-based materials are special lignocellulose-containing plates or molded parts with directed mechanical and hygric properties. For these wood materials LSL, PSL and especially OSB are expected. OSB is the structure-oriented wood-based material with the greatest economic importance. Due to the shape and size of the beaches, the corresponding wood-based materials have high mechanical properties. They are therefore particularly useful as construction elements in construction.

Out US 2,874,909 A a method for producing chips for the production of plates with the following method steps is known: it is produced from fresh wood or recycled wood, a precursor, the precursor is substantially rod-shaped, the precursor is fed to a chipper, comprising a plurality of knives, the a blade ring are arranged whose cutting edges extend at least approximately parallel to the ring axis, and which enclose a working space; the precursor is set in rotation about the knife ring axis, in this case aligned so that it is substantially parallel to the ring axis and is pressed by centrifugal force against the cutting edges of the knife; the precursor has a length of several centimeters.

DE 11 71 143 B shows and describes the influence of heat, moisture and pressure in the production of chips to improve their quality.

A successful method of producing OS chips is described in US Patent No. 5,348,855 EP 1 335 818 B1 , There, the shape of the precursor is defined more precisely.

The method is, however, capable of improvement. This concerns above all the quality of the individual Flachspanes. This should be even higher quality if possible in terms of its shape and its surface. Also, when machining a maximum of high-quality flat chips are created, but only a minimum of fines content. Finally, the energy requirement should be minimized.

The invention has for its object to provide a method by which a beach material from lumpy pieces of wood (precursors such as Maxichips and flat chips) can be produced, which contains high shares of pronounced flat strands and low fines. Furthermore, the demand for cutting energy should be minimal.

This object is solved by the features of claim 1.

The essential ideas of the invention relate to the shape of the precursor and the provision of a further treatment step: namely, the precursor is subjected to an intermediate treatment with the action of heat and moisture before it is further treated mechanically.

The mentioned treatment with moisture and heat is applied to the precursor (Maxichip) after chopping. It can be combined with the application of superatmospheric pressure.

For heat treatment, any heat sources may be used, such as microwave or infrared devices. Also, a hot water treatment or steam treatment is considered.

The entire process can be carried out batchwise or continuously. When working continuously, the use of screw conveyors is conceivable. The screws can be fed with a woodchip-water mixture. The pressure can be generated by a butterfly valve at the end of the screw conveyor having a limited outlet gap releases, and thus builds up a pressure in the screw conveyor. In the auger also a steam treatment can take place. Also, the application of negative pressure or pressure is applicable.

• der Zerspanungsprozess liefert einen hohen Anteil an Flachspänen, und einen minimalen Anteil an unerwünschtem Feinstoff;
• die Qualität der Flachspäne ist besser, als die bisher erzeugten: die Späne sind von tadelloser Oberfläche, geeignet zum Erzeugen von OS-Platten; die Späne sind weiterhin von höherer Festigkeit, als bisher;
• die Strands zeigen darüber hinaus aufgrund der hydrothermalen Behandlung und der schonenden Zerspanung weniger Risse, die Gefahr einer Nachzerkleinerung durch nachfolgende Prozesse bei der Herstellung von OSB ist hierdurch geringer;
• der spezifische Energieaufwand in kWh, bezogen auf die Mengeneinheit erzeugter OS-Späne, ist wesentlich geringer als bei bekannten Verfahren;
• als Ausgangsmaterial kommen jegliche lignozellulosehaltigen Materialien in Betracht, somit Holz, Abfallholz, geschreddertes Holz, Recyclingholz, aber auch exotische Materialien wie Bambus, Palme.

The results are amazing. The process according to the invention has the following advantages:

• the machining process provides a high proportion of shavings, and a minimum amount of unwanted fines;
• the quality of the flakes is better than those produced so far: the flakes are of impeccable surface, suitable for the production of OS panels; the chips are still of higher strength than before;
• the strands also show less cracks due to the hydrothermal treatment and the gentle cutting, the risk of subsequent comminution by subsequent processes in the production of OSB is thereby lower;
• the specific energy consumption in kWh, based on the unit of measure generated OS chips, is substantially lower than in known methods;
• starting materials are any lignocellulosic materials, such as wood, waste wood, shredded wood, recycled wood, as well as exotic materials such as bamboo, palm trees.

Figur 1

zeigt in einem Blockschaltbild den Ablauf eines Verfahrens zum Herstellen von OS-Platten.

Figur 2

zeigt einen Zerspaner in einer Ansicht von vom, das heißt in einer Ansicht auf diejenige Seite, auf der sich der Gehäusedeckel mit dem Einsatz für das Vorprodukt befindet.

Figur 3

zeigt in vergrößertem Maßstab einen Axialschnitt des Zerspaners gemäß Figur 2.

Figur 4

zeigt in vergrößerter Darstellung einen Ausschnitt aus Figur 3, nämlich ein Messerpaket.

The invention is explained in more detail with reference to the drawing. The following is shown in detail:

FIG. 1

shows in a block diagram the sequence of a method for producing OS disks.

FIG. 2

shows a chipper in a view from, that is in a view of the side on which the housing cover is located with the insert for the precursor.

FIG. 3

shows in enlarged scale an axial section of the Zerspaners according to FIG. 2 ,

FIG. 4

shows an enlarged view of a section FIG. 3 namely a knife package.

• Das zu verarbeitende Gut wird zunächst in Station 100 gelagert. Dabei handelt es sich im Falle dieses Beispieles um gebrauchte Holzpaletten. Selbstverständlich kommen alle möglichen anderen lignozellulosehaltigen Materialien in Betracht, so wie oben erwähnt.

The block diagram according to FIG. 1 shows the following stations of the process for making OS disks:

• The material to be processed is first stored in station 100. In the case of this example, these are used wooden pallets. Of course, all possible other lignocellulosic materials come into consideration, as mentioned above.

In station 101, a pre-shredding takes place, for example in a shredder.

In station 102 a hacking takes place. Here the precursor is produced. It is at least approximately rod-shaped.

In station 103, treatment with moisture and heat takes place. The treatment may consist in a dip in hot water. The water has a temperature above 50 ° C, for example 60, 70, 80, 90, 100 ° C. The residence time is between 3 and 30 minutes. Even longer periods are possible, for example one hour, two hours and so on.

Instead of dipping in hot water, brewing with superheated steam is also considered.

The wet-hot treatment can also take place under superatmospheric or subatmospheric pressure, thus in a closed vessel. Here, the precursor - thus the chips - completely saturated. There is some plasticizing, possibly also a dissolution of the lignin.

In station 104, the precursor is pre-classified.

In station 105, the cutting takes place. The result is OS chips with a chip thickness of 0.2 to 0.8 mm, preferably 0.2 to 0.6 mm.

The chipping is followed by indulgence in station 106.

This is followed by further processing to OS disks in station 107.

How to get out of the FIGS. 2 and 3 In particular, the chipper comprises a rotor 1 which is driven by a shaft 2. The rotor 1 contains a ring of axially parallel blades 3. A knife basket with likewise axially parallel blades 4 surrounds the rotor 1. Rotor 1 and knife basket are in turn arranged in a housing 5 and jointly enclosed by this. Housing 5 has an inlet 6 for the wood chips to be supplied and an outlet for the finished chip.

FIG. 3 illustrates in two places a rod-shaped precursor 20. This is ordered in the present case as a regular rectangular block. Instead, however, this precursor could also be designed differently, for example, have irregular boundary surfaces. It is only important that this precursor 20 is more or less rod-shaped, that is, has a longitudinal extent that is greater than the transverse extensions in planes perpendicular thereto.

The precursor 20 is fed to the shaft-shaped inlet 6 - see arrow. It then passes into the space enclosed by the rotor 1 interior. In this case, the precursor 20 - automatically or by a corresponding orientation device - such that it extends mainly to the longitudinal axis of the rotor shaft 2, and thus more or less parallel to the blades 4. The precursor has a considerable size, in particular a considerable length compared with those wood chips that are supplied to the usual knife ring chipper.

In FIG. 4 is shown in an axis-perpendicular section a knife package. This knife package is part of the knife ring of the machine.

Each knife package is constructed as follows: A support block 10 carries a cutting blade 11 which is fixed by means of a clamping plate 12 and a screw 13 on the support block 10.

Each support block 10 has a wear surface 10.1. The decisive factor is that these wearing surfaces 10.1 facing the machine axis are approximately flat and thus not concentric as in the prior art.

The wear surface is 10.1 as in the case of FIG. 4 formed from a wear plate 10.2, which in turn is attached to the rest of the support block 10. The wear surface can also be formed from a wear layer that has been produced by applying a wear layer, preferably by build-up welding or spraying and subsequent grinding.

In the embodiment according to FIG. 4 a razor 14 is provided which is fixed on the side opposite the cutting blade 11 side of the supporting block 10, and which cooperates with the cutting blade of the adjacent blade package. Also, a wear plate is conceivable in which the hanger is integrated and takes over its function.

LIST OF REFERENCE NUMBERS

1

rotor

2

wave

3

wing

4

knife

5

casing

6

inlet

10

support block

10.1

wearing surface

10.2

wear plate

11

cutting blade

12

chipboard

13

screw

14

stock knife

20

precursor

100

Storage station for waste wood

101

Vorzerkleinerungsstation

102

Hack station

103

Hot water station

104

Caution station

105

Zerspanstation

106

indulgence station

107

processing

Claims (7)

1. A method for producing flat chips for structure-oriented wood materials, having the following method steps:

   1.1 a pre-product is generated from material containing lignocellulose;

   1.2 the pre-product has a length of between 20 and 200 mm;

   1.3 the pre-product is subjected to a hydrothermal treatment, comprising a heat treatment and a moisture treatment;

   1.4 the exposure duration is at least three minutes, and the exposure temperature is at least 40°C;

   1.5 the pre-product is subjected to cutting or splitting.
2. The method according to Claim 1, characterized in that, during the hydrothermal treatment, dry heat or steam or hot water or a water bath or a microwave treatment or a high-frequency treatment is applied.
3. The method according to Claim 1 or 2, characterized in that the hydrothermal treatment of the pre-product occurs before the cutting or splitting or during the cutting or splitting.
4. The method according to one of Claims 1 to 3, characterized in that the pre-product has a moisture content of greater than 35% atro after the hydrothermal treatment.
5. The method according to one of Claims 1 to 4, characterized in that the hydrothermal treatment is performed at super-atmospheric or subatmospheric pressure.
6. The method according to one of Claims 1 to 5, characterized in that the cutting of the pre-product is performed in blade ring cutters, blade shaft cutters, or disc cutters.
7. The method according to Claim 6, characterized by the following features:

   7.1 the pre-product (20) is supplied to a cutter, comprising a plurality of blades (4), which are situated on a blade ring, whose cutting edges run at least approximately parallel to the ring axis, and which enclose a working space;

   7.2 the pre-product (20) is set into revolution around the blade ring axis, oriented for this purpose in such a manner that it is essentially parallel to the ring axis and is pressed against the cutting edges of the blades (4) by centrifugal force;

   7.3 the operating parameters such as the blade design and the blade angle are selected in such a manner that flat chips having a chip thickness of 0.2 to 0.8 mm, preferably from 0.2 to 0.6 mm result;

   7.4 a sifter step is placed upstream from the cutting, in order to only let through pre-products of established dimensions;

   7.5 a classification step is placed downstream from the cutting, in order to classify the chips according to criteria of their design or their dimensions or their weight.

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