DE102020005512A1 - Process for the production of an OSB or wafer board, plant for the production of OSB or wafer boards and OSB or wafer boards - Google Patents

Abstract

The invention relates to a method for producing an OSB or wafer board from chips with a length of 1 to 60 mm, comprising the following steps: a) comminution of wood into fines (12), useful material (11) and coarse material (13), the useful material has at least most of the chips,b) fractionation of fines, useful material and coarse material according to sizec) drying at least the useful material,d) gluing of at least part of the useful material,e) scattering at least the useful material to form a grit mat (9) andf) pressing the Grit mat to an OSB or wafer panel (10). In order to make the manufacturing process for OSB or wafer panels of the same or even higher quality resource-saving and cheaper, it is planned that the wood used also includes small wood with diameters of less than 0.08 m and for Crushing at least one knife shaft shredder is used.

Description

1. a) Zerkleinerung von Holz zu Feingut, Nutzgut und Grobgut, wobei das Nutzgut zumindest den größten Teil der Späne aufweist,
2. b) Fraktionierung von Feingut, Nutzgut und Grobgut nach Größe
3. c) Trocknung wenigstens des Nutzgutes,
4. d) Beleimung wenigstens eines Teils des Nutzgutes,
5. e) Streuung wenigstens des Nutzgutes zu einer Matte und
6. f) Verpressen der Matte zu einer OSB- oder Waferplatte.

The invention relates to a method for producing an OSB or wafer board from chips, which have a length of at least more than 50% of the total mass of 35 to 180 mm, comprising the following steps,

1. a) Crushing of wood into fines, useful material and coarse material, whereby the useful material contains at least the largest part of the chips,
2. b) Fractionation of fines, usable material and coarse material according to size
3. c) drying at least the useful material,
4. d) gluing of at least part of the useful goods,
5. e) scattering at least the useful material to form a mat and
6. f) Pressing the mat to form an OSB or wafer board.

Furthermore, the invention relates to an OSB or wafer board produced by the method according to the invention.

There are numerous publications and patent applications on the production of an OSB or wafer board. The features a) to f) for the production of an OSB or wafer board are provided in almost all production processes and can sometimes be used in different ways. The specified order a) to f) can also differ. In particular, the fractionation can also take place after drying or before and after.

As a rule, the wood intended for use is chopped up into chips first by debarking logs and then the chips of the above-mentioned board types are made from debarked wood with knife ring direct chippers or disc chippers. In both cases, the wood must be debarked to achieve economical tool life. Due to the chipping process of the chipping machines mentioned above, wood with a small (<100 mm) diameter can only be used in small quantities or not at all, since otherwise there is a low wood yield with a high proportion of fines. There is an alternative chipping process in which the chips are produced in two stages, i.e. first wood chips are produced which are broken down into chips in a subsequent work step with the help of knife ring flakers. The disadvantage of both methods is the high outlay on machinery, which leads to high investment and energy costs (space requirements, foundations, buildings, electricity consumption). In addition, the service life of the knives in a knife ring flaker is often only a few hours, which leads to frequent maintenance failures.

The chips obtained are usually fractionated after drying, for example in a drum dryer. For this purpose, disc screens are used, for example. The material is divided into different chip fractions. The different chip sizes are assigned to the subsequent board layers and scattered accordingly. Provision can be made, for example, for smaller chips to be provided on the inside, the so-called middle layer, and larger chip sizes on the outside, ie the cover layers. This gives the OSB or wafer board a relatively high flexural strength.

It is therefore the object of the invention to design the manufacturing process for OSB or wafer boards of the same or even higher quality in a way that saves resources and is cheaper. The value is primarily based on the mechanical properties, in particular flexural strength, screw pull-out strength and modulus of elasticity.

The object is achieved with regard to the production process with the features of claim 1 and in particular in that the wood used also includes small wood with diameters of less than 0.08 m and at least one knife shaft shredder is used for shredding.

The inventors have recognized that small wood can also be used for high-quality OSB or wafer boards if a knife shaft flaker is used for shredding instead of chippers and knife ring flakers. The space and energy requirements are significantly lower for knife shaft flakers. The new embodiment makes the tremendous difference of using only about half the energy required with choppers and knife ring flakers, and in fact only a tenth of the space required.

Knife shaft flakers also allow smaller log diameters to be chipped. This is only possible to an unsatisfactory extent with knife ring flakers with trunk diameters of often well over 0.08 m with debarked wood. The diameter is defined as the circumference divided by the number Pi (π= 3.14). So-called splinters often occur when using knife shaft flakers. These are woodcut remnants that are very difficult to sort out using conventional screening technology. The splinters can thus partly get into the press, especially in the case of continuous presses lead to damage. Splinters also reduce the quality and appearance of the produced OSB or wafer board.

However, the improved possibility of using so-called small wood or residual industrial wood with a diameter of less than 0.08 m is also significantly more cost-effective, since these types of wood are cheaper to procure. Even logs with a diameter of 0.04 m and more were tested with positive results.

It is preferred that the proportion of chips made from small wood in the OSB or wafer board is at least 30%, preferably at least 50%.

Above this size, the manufacturing process becomes particularly economical. The total proportion of the chips used from the knife shaft flaker for the OSB or wafer board should be 30 to 100%. Of course, several knife shaft flakers can also be used. For example, in many cases it makes sense to use two differently adjusted knife shaft flakers, whereby one produces chips for the middle layer and the other chips for the top layers.

It is provided with particular advantage that wood which has not been stripped of bark is also used as the wood.

Here, too, the profitable use of the knife shaft chipper can be seen, which is able to chip wood that has not been debarked into high-quality chips much better, in such a way that the bark parts are either introduced into the OSB or wafer board or into something that will be explained later Away can be easily sorted out.

The knife shaft flaker preferably produces chips with a thickness of 0.1 to 0.8 mm.

The shape of the chips is very important for the subsequent quality of the OSB or wafer board. It influences the glue consumption, the specific weight and the mechanical properties. With a knife shaft flaker, it is possible to produce high-quality chips from small wood or industrial waste wood, since the knife shaft flaker produces rather very flat, thin plates. These have a higher degree of slenderness (chip length to chip thickness), are easier to wet with glue and create a strong bond.

This is also considered to be the reason why the process can preferably be used in such a way that a bending strength that corresponds to the values of EN 300 is achieved.

However, it is the case that with the conventionally most frequently used screening technology, splinters, bark and other coarse material can only be sorted out to a limited extent. Therefore, the inventors propose, optionally but advantageously, that the fractionation takes place at least partially with a drum screen or a star screen. Surprisingly, it turned out that a drum screen can sort out splinters, bark and other coarse material.

A drum screen can be found, for example, in DE3836608A1 and a star screen in the DE4415815A1 . However, the sieve device downstream of the comminution device is preferably designed as a drum sieve fed from the inside, which has been tested in tests and should be cleaned in particular with a rotating brush. This can be 30 to 70% of the drum length, for example. The drum through which the chipped material is sent is preferably slightly inclined in the direction of passage. It has an inner wall of the drum that is designed as a sieve.

With particular advantage, the mesh size of the sieve is now getting larger and larger in the direction of travel, so first the fines are removed from the drum, at a point following in the direction of travel the useful material and at the rear end in the direction of throughput the coarse material exits and can preferably be removed before gluing .

In an optionally alternative or additional preferred inventive embodiment, the fractionation (ie preferably with a drum screen or a star screen) is already carried out before drying.

Experts distinguish between the “wet area”, in which the ratio of the water mass contained in the wood to the dry mass of the wood, referred to as wood moisture content, is around 60 to 180%, and the “dry area” after drying, in which the value is around 60 to 180% usually 1.5 to 10%. In the known plants of the prior art, the fractionation always takes place in the dry area. However, the inventors have recognized the advantages that result from fractionation in the wet area, because the energy consumption is significantly reduced.

The usable material and possibly also the fine material are preferably separated again for different OSB or wafer board layers and fed to different bunkers. From these bunkers, the chips are passed on to the individual scattering heads assigned to the top and middle layers. Of course, the chips must be glued before spreading.

Advantageously, it is ensured that the chips pass through a hot air classifier before drying.

Such a hot air classifier has an omega-like shape, for example. The material is then guided through the omega-shaped tube with hot air and pre-dried before the material is fed into the actual drying process (which takes place in a drying drum, for example). Second, heavyweight debris not carried by the airflow is discharged through an outlet by gravity before it reaches the zenith of the omega-shaped tube. The hot air can be generated, for example, by burning wood dust particles produced during the process. This measure also results in high cost and energy savings.

A portion of bark that remains under the chips is preferably separated during the scattering in such a way that it is scattered in the middle region as seen over the thickness of the OSB or wafer board.

This measure also makes positive use of the process of bark separation. The bark material, which would have a negative impact on the surface of an OSB or wafer board, is not discharged beforehand, but only separated during the spreading process by a sifting process and then scattered by the spreading system in a middle layer of the mat of OSB or wafer board to be pressed. As a result, the bark parts are hidden invisibly in the OSB or wafer board.

In addition, a plant for the production of OSB or wafer panels that works according to the described method is to be protected.

Furthermore, the OSB or wafer board that can be produced by the described method according to one of claims 1 to 13 is to be placed under protection.

• 1 ein Ablaufschema des erfindungsgemäßen Verfahrens,

The invention is explained in more detail below with reference to drawings showing an exemplary embodiment. It shows

• 1 a flow chart of the method according to the invention,

In the 1 an embodiment of the invention is represented by an exemplary flow chart of the manufacturing method for chipboard according to the invention. The system components essential for the process are shown in seven boxes. Also, for most cases, the order presented is the procedure followed when using the units. However, slight changes in the sequence or the addition of further units are possible and should not restrict the idea of the invention.

The knife shaft flaker 1 is an important part of the system, which, in contrast to the choppers and several knife ring flakers otherwise used, ensures a significantly cheaper manufacturing process. Such a knife shaft chipper can definitely provide a proportion of 30 to 100% of the chopped wood for the chipboard. In addition, the manufacturing process is cheaper because the knife shaft flaker can use small pieces of wood with a diameter of less than 0.08 m that have been stripped or not stripped of bark. The proportion of small wood in the new chipboard can be at least 30%, preferably at least 50%.

A drum screen 2 is provided as another important unit in the chipboard manufacturing process. This is much more energy-efficient to use than disc screens, for example. The drum screen is able to fractionate the chips produced directly into fines 12, usable material 11 and, if necessary, coarse material 13 to be sorted out. The usable material includes the chips that are used for chipboard production. These can be separated again into the chips for the middle layer of a chipboard and the chips for the top layers. Under certain circumstances, for example, fines can also be added to the top layer in order to make the surface particularly smooth.

At least part of the usable material 11 is preheated in a hot air classifier 3 and at the same time freed from coarse material before the material is fed into the drum dryer. In general, it applies to the flow chart that further parts of the system can be arranged between the individual stations that are important for the invention. For example, bunkers or reservoirs, air treatment or similar aggregates are not shown.

The chips are then dried in one or more commercially available dryers 4, for example one each for a specific size or scatter layer. The grit can then be fed from bunkers or stores to a gluing device 5, which is also known. As usual, the chips are sprayed with binding agents in a chute or a large mixer drum so that they can be firmly bonded in the later pressing process.

The chips are separated into different sizes for the individual layers and fed to a scattering station 6 individual scattering heads, which scatter the material evenly distributed on a scattering belt and thus form a scattering material mat 9 . This grit mat is then in the continuous Press 7 spent and pressed there under pressure and higher temperature. Such a continuous press is marketed by the applicant under the name ContiRoll.

Due to the fact that the knife shaft flaker produces very thin (thickness from 0.1 to 0.8 mm) and not as narrow chips as a knife ring flaker, the bending strength can also be achieved with the process through suitable gluing and pressing, which corresponds to the values of the conforms to EN300.

Reference List

1

knife shaft flaker

2

drum screen

3

hot air classifier

4

dryer

5

gluing device

6

Spreading station with spreading heads

7

Continuous press

8th

weakwood

9

grit mat

10

chipboard

11

utility

12

fines

13

coarse material

QUOTES INCLUDED IN DESCRIPTION

This list of documents cited by the applicant was generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Patent Literature Cited

• DE 3836608 A1 [0019]
• DE 4415815 A1 [0019]

Claims (16)

Process for the production of an OSB or wafer board from chips with a length of 1 to 60 mm, comprising the following steps, a) comminution of wood into fines (12), useful material (11) and coarse material (13), the useful material comprising at least most of the has chips, b) fractionation of fine material, useful material and coarse material according to size c) drying of at least the useful material, d) gluing of at least part of the useful material, e) scattering of at least the useful material to form a grit mat (9) and f) pressing the grit mat to form one OSB or wafer board (10), characterized in that the wood used also includes small wood (8) with diameters of less than 0.08 m and at least one knife-shaft shredder (1) is used for comminution. procedure after claim 1 , characterized in that the proportion of chips made from small wood (8) in the OSB or wafer board (10) is at least 30%, preferably at least 50%. procedure after claim 1 or 2 , characterized in that not debarked wood is used as wood. Procedure according to one of Claims 1 until 3 , characterized in that the knife shaft chipper (1) produces chips with a thickness of 0.1 to 0.8 mm. procedure according to claim 4 , characterized in that the thin chips in the OSB or wafer board (10) ensure a bending strength due to the manufacturing process that corresponds to the values of EN 300. The EN 300 standard defines the mechanical properties and the relative humidity resistance. Procedure according to one of Claims 1 until 5 , characterized in that the fractionation takes place at least partially with a drum screen (2) or a star screen. Procedure according to one of Claims 1 until 6 , characterized in that the fractionation is carried out before drying (4). Procedure according to one of Claims 1 until 7 , characterized in that the fractionation with a drum screen (2) or a star screen includes the disposal of coarse material (13). Procedure according to one of Claims 1 until 8th , characterized in that coarse material (13) is sorted out before gluing. Procedure according to one of Claims 1 until 9 , characterized in that at least part of the fines (12) is used as a top layer additive. Procedure according to one of Claims 1 until 10 , characterized in that the chips for a top layer and a middle layer of the OSB or wafer board (10) are supplied to separate bunkers and then separately provided with glue. Procedure according to one of Claims 1 until 11 , characterized in that the chips pass through a hot air classifier (3) before drying. Procedure according to one of Claims 1 until 11 , characterized in that a remaining part of the bark under the chips is separated during the scattering in such a way that it is scattered over the thickness of the OSB or wafer board (10) in the middle area. Plant for the production of OSB or wafer panels according to the method of one of Claims 1 until 13 , comprising at least one knife shaft chipper (1), a drum screen (2), a dryer (4) for chips, a gluing device (5) for chips, a scattering station (6) and a continuous press (7). plant after Claim 14 , characterized in that it also comprises a hot air classifier (3). OSB or wafer board, manufactured according to one of Claims 1 until 13 .

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