Method for manufacturing osb or waferboard, apparatus for manufacturing osb or waferboard and osb or waferboard

Abstract

The invention relates to a method for manufacturing OSB or waferboard from wood chips having a length of 1 to 60 mm, comprising the following steps: a) comminuting the wood into fines (12), useful material (11) and coarse material (13), wherein the useful material has at least the greater part of the wood chips, b) sorting the fines, the useful material and the coarse material according to size, c) drying at least the useful material, d) gluing at least a part of the useful material, e) spreading at least the useful material into a loose material mat (9), and f) pressing the OSB or waferboard (10) from the loose material mat. In order to make the manufacturing method for the same quality or even higher quality of chipboard more resource-saving and less costly, it is provided that the wood used also includes small-diameter wood having a diameter of less than 0.08 m and at least one knife shaft cutter is used for comminution.

Description

Technical Field

[0001] This invention relates to a method for manufacturing oriented strand board (OSB) or waffle board from wood chips, wherein at least 50% of the wood chips have a length of 35 to 180 mm, and the method comprises the following steps.

[0002] a) Shredding the wood into fine material, usable material, and coarse material, wherein the usable material comprises at least a majority of sawdust.

[0003] b) Sort the fine materials, useful materials, and coarse materials according to their size.

[0004] c) At least the useful materials should be dried.

[0005] d) Glue together at least a portion of the material.

[0006] e) At least the useful material should be spread into a mat, and

[0007] f) Press the pad into oriented strand board or waffle board.

[0008] Furthermore, the present invention relates to an oriented strand board or waffle board manufactured according to the method of the present invention. Background Technology

[0009] Numerous published documents and patent applications exist regarding the manufacture of oriented strand board (OSB) or waffle board. Features a) through f) used in the manufacture of OSB or waffle board are present in almost all manufacturing methods and can be used in some different ways. The given order of a) through f) can also vary. In particular, sorting can be performed after drying or both before and after drying.

[0010] The process of pulverizing timber into sawdust typically involves first debarking the tree trunk and then using a ring cutter or disc cutter to produce the aforementioned board-type sawdust. In both cases, debarking is necessary to achieve economical tool life. Based on this cutting method, timber with small diameters (<100mm) can only be used in small quantities or is completely unusable, as it otherwise results in a small timber yield with a high proportion of fines. An alternative cutting method exists in which sawdust is produced in two stages: first, wood chips are produced, which are then pulverized into sawdust in a subsequent step using a ring cutter. The disadvantages of both processes are high machine costs, leading to high investment and energy costs (space requirements, foundations, buildings, electricity consumption). Furthermore, the tool life in a ring cutter is typically only a few hours, resulting in frequent downtime for maintenance.

[0011] Typically, the wood chips obtained after drying are sorted, for example, in a drum dryer. For this purpose, a disc sieve is used, for example. The material is separated into different wood chip portions. Different wood chip sizes are allocated to subsequent board layers and are distributed accordingly. For example, it can be specified that smaller wood chips are placed in the inner, so-called intermediate layer, and larger wood chip sizes are placed in the outer, i.e., the cover layer. Thus, OSB or waffle boards achieve relatively high bending strength. Summary of the Invention

[0012] Therefore, the object of this invention is to design a method for manufacturing particleboard of the same or even higher quality in a resource-saving and cost-effective manner. Its significance lies primarily in mechanical properties, especially bending strength, screw tensile strength, and modulus of elasticity.

[0013] Regarding the manufacturing method, this objective is achieved by a method for manufacturing oriented strand board or waffle board from wood chips with a length of 1 to 60 mm, and in particular by the following: the wood used also includes small-diameter wood with a diameter of less than 0.08 m, and at least one cutter shaft cutting machine is used for the crushing.

[0014] The inventors recognized that small-diameter timber could be used to produce high-quality OSB or waffle boards simply by using a cutter shaft cutter instead of a shredder and a cutter ring cutter for pulverization. The space requirements and maintenance costs are significantly lower when using a cutter shaft cutter. The new implementation makes a huge difference, requiring only about half the energy of a shredder and a cutter ring cutter, and virtually only one-tenth the space.

[0015] Axle cutters also allow for cutting smaller trunk diameters. Ring cutters can only handle debarked wood with trunk diameters typically well over 0.08m to a less than satisfactory degree. Here, diameter is defined as the circumference divided by the quantity Pi (π = 3.14). So-called "shavings" are frequently generated when using axle cutters. These shavings are wood cutting residues that are difficult to classify using traditional screening techniques. They can partially enter the press and cause damage, especially in continuous presses. Shavings also reduce the quality and appearance of the produced OSB or waffle boards.

[0016] However, the increased possibility of using so-called small-diameter timber or industrial waste wood with a diameter less than 0.08m is also significantly more cost-effective, as these types of timber have lower procurement costs. There have even been positive results testing timber with diameters starting from 0.04m.

[0017] Preferably, the proportion of wood chips made from small-diameter wood in the OSB or waffle board is at least 30%, preferably at least 50%.

[0018] From this size range onwards, the manufacturing process becomes particularly economical. The total proportion of wood chips used in the spindle cutting machine for OSB or waffle boards should be between 30% and 100%. Of course, multiple spindle cutting machines can also be used. For example, in many cases, it is also meaningful to use two spindle cutting machines with different configurations, one producing wood chips for the intermediate layer and the other for the cover layer.

[0019] It is particularly advantageous that unpeeled wood is also used as timber.

[0020] Here we can also see the advantageous use of the cutter shaft cutting machine, which can better cut unpeeled wood into high-quality wood chips, specifically in the way that the bark can be introduced into OSB or waffle board, or easily sorted as explained later.

[0021] Preferably, the cutter shaft cutting machine produces wood chips with a thickness of 0.1 to 0.8 mm.

[0022] The shape of the wood chips is crucial for the final quality of OSB or waffle boards. It affects glue usage, specific gravity, and mechanical properties. Therefore, it is possible to produce high-quality wood chips from small-diameter timber or industrial waste wood using a cutter-axis cutting machine, as this method is more likely to produce very flat sheets. These sheets have a higher slenderness (the ratio of chip length to chip thickness), making them easier to wet with glue and form a strong bond.

[0023] This is also considered the reason why this method of processing is preferred, namely, to achieve the bending strength corresponding to the value of EN300.

[0024] However, the situation is such that conventionally used screening techniques can only sort debris, bark, and other coarse materials to a limited extent. Therefore, it was proposed by the inventors, optionally but advantageously, that sorting be performed, at least in part, using a drum screen or a star screen. Surprisingly, it was discovered that the drum screen could sort debris, bark, and other coarse materials.

[0025] For example, a drum screen can be obtained in DE3836608A1, and a star screen can be obtained in DE4415815A1. However, the screening device located downstream of the crushing device is preferably a drum screen with internal feeding, which has been tested and should be cleaned, in particular, with a rotating brush. It can occupy, for example, 30% to 70% of the drum length. The drum conveying the shredded material is preferably slightly inclined in the through-passing direction. The drum has an inner wall configured as a screen.

[0026] A particular advantage is that the mesh size of the sieve increases in the direction of travel, so that fine material is discharged from the drum first, useful material is discharged at the next position in the direction of travel, and coarse material is discharged at the rear end in the direction of penetration, and preferably removed before applying adhesive.

[0027] In alternative or additional preferred embodiments of the invention, sorting (preferably using a drum screen or star screen) is performed before drying.

[0028] Technicians differentiate between "wet zones" and "dry zones" based on their degree of dryness. In the "wet zone," the percentage of water content in the wood to its dry weight, i.e., the wood moisture content, is approximately 60% to 180%, while in the "dry zone," the wood moisture content is generally between 1.5% and 10%. In existing equipment, sorting always takes place in the dry zone. However, the inventors have recognized the advantages of wet sorting, as it significantly reduces energy consumption.

[0029] Preferably, the useful material for different OSB or waffle layers, and possibly finer material, is further separated and conveyed to different hoppers. From these hoppers, the sawdust is then guided to individual distribution heads belonging to the cover and intermediate layers. Of course, the sawdust must be glued before distribution.

[0030] Advantageously, the sawdust is passed through a hot air separator before drying.

[0031] Such a hot air separator is, for example, shaped like an omega. The useful material is then guided by hot air through the omega-shaped tube and pre-dried on one hand before being guided into the actual drying process (which takes place, for example, in a drying drum). Secondly, before reaching the apex of the omega-shaped tube, the heavier, coarser particles not carried by the airflow are discharged through the exhaust port by gravity. The hot air can be generated, for example, by the combustion of wood dust particles produced in the process. This method also presents high costs and energy savings.

[0032] Preferably, the bark portion remaining in the sawdust is separated during dispersal such that the bark portion is observed to be dispersed in the middle region across the thickness of the OSB or waffle board.

[0033] This measure advantageously utilizes the bark separation process. Instead of pre-extracting the bark material that would otherwise fall unfavorably onto the surface of the OSB or waffle board, the bark material is first separated during the spreading process by a separation process, and then the bark material is spread by a spreading device into the intermediate layer of the spread pad to be pressed into the OSB or waffle board. Thus, the bark portion is invisibly hidden within the OSB or waffle board.

[0034] In addition, protection should be provided for a device used to manufacture OSB or waffle boards that operates in accordance with the described method.

[0035] In addition, the OSB or waffle board, which can be produced according to the method of the present invention, should be protected. Attached Figure Description

[0036] The invention will be further explained below with reference to the accompanying drawings, which illustrate embodiments. In the drawings:

[0037] Figure 1 This is a flowchart of the method according to the present invention. Detailed Implementation

[0038] exist Figure 1 This diagram illustrates an embodiment of the invention through an exemplary flowchart of a method for manufacturing particleboard according to the invention. Here, the equipment components essential to the process are shown in seven boxes. In most cases, the sequence shown is also the process followed when using the equipment units. However, minor variations in this sequence or the addition of other equipment units are possible and should not limit the concept of the invention.

[0039] The cutter shaft cutter (Messerwellenzerspaner) 1 is a crucial component of the equipment. Compared to other shredders and multiple cutter ring cutters (Messerringzerspaner), this cutter shaft cutter ensures a significantly lower cost for the manufacturing process. Such a cutter shaft cutter can provide particleboard with a wood chip ratio of 30% to 100%. Furthermore, because the cutter shaft cutter can use small-diameter wood, whether debarked or undebarked, with a diameter less than 0.08 m, the manufacturing method offers even greater cost-effectiveness. The proportion of small-diameter wood in the new particleboard can be at least 30%, preferably at least 50%.

[0040] A drum screen 2 is provided as another important equipment unit in the particleboard manufacturing process. Using a drum screen is significantly more energy-efficient than, for example, a disc screen. The drum screen can directly separate the generated wood chips into fine particles 12, usable particles 11, and optionally coarse particles 13. The usable particles include wood chips used for particleboard manufacturing. The wood chips can be further separated into wood chips for the intermediate layer of the particleboard and wood chips for the cover layer. In some cases, for example, the fine particles can also be mixed into the cover layer to make the surface particularly smooth.

[0041] Before the material is guided into the rotary drum dryer, at least a portion of the material 11 is preheated in the hot air separator 3 and coarse material is removed simultaneously. In the flow diagram, more equipment components can typically be arranged between various stations important to the invention. For example, silos or storage containers, air handling units, or similar equipment units are not shown.

[0042] The sawdust is then dried in one or more commercially available dryers 4, for example, for specific sizes or spread layers. The bulk material is then fed from a hopper or reservoir to a similarly known gluing device 5. Typically, the sawdust is sprayed with adhesive in a feed trough or large mixing drum thereto ensure strong bonding during subsequent pressing.

[0043] The sawdust is separated into different sizes for each layer and fed to various distributing heads at the distributing station 6. These distributing heads evenly distribute the useful material onto the distributing belt, thus forming a material pad 9. The material pad is then introduced into a continuous press 7 and pressed there under pressure and high temperature. This continuous press is sold by the applicant under the name ContiRoll.

[0044] Because the cutter shaft cutting machine produces very thin wood chips (between 0.1 and 0.8 mm in thickness) rather than the narrow wood chips produced by the cutter ring cutting machine, the bending strength corresponding to the EN300 value can be achieved by means of proper gluing and pressing using the method described above.

[0045] List of reference numerals

[0046] 1-axis cutting machine

[0047] 2 drum screen

[0048] 3. Hot air separator

[0049] 4 Dryer

[0050] 5. Gluing device

[0051] 6. Distribution stations including distribution heads

[0052] 7 Continuous Press

[0053] 8 small paths

[0054] 9 Bulk Pads

[0055] 10 Particleboard

[0056] 11. Contains ingredients

[0057] 12 Fine Materials

[0058] 13 Coarse materials

Claims

1. A method for manufacturing oriented strand board (OSB) or waffle board from wood chips with a length of 1 mm to 60 mm, the method comprising the following steps, a) The wood is crushed into fine material (12), usable material (11), and coarse material (13), wherein, The useful material contains at least a majority of wood chips. b) Sort the fine materials, useful materials, and coarse materials according to their size. c) At least the useful materials should be dried. d) Glue together at least a portion of the material. e) At least the useful material shall be distributed into a bulk pad (9), and f) Press the bulk material pads into oriented strand board or waffle board (10), Its features are, Unpeeled wood was also used as timber, including small-diameter timber (8) with a diameter of less than 0.08 m, and at least one cutter shaft cutter (1) was used for the crushing, which was carried out in a wet area with a wood moisture content of 60% to 180%.

2. The method according to claim 1, characterized in that, The proportion of wood chips made from small-diameter wood (8) in the oriented strand board or waffle board (10) is at least 30%.

3. The method according to claim 1, characterized in that, The cutter shaft cutting machine (1) produces wood chips with a thickness of 0.1 mm to 0.8 mm.

4. The method according to claim 3, characterized in that, The thin wood chips in the oriented strand board or waffle board (10) are ensured by the manufacturing process to have bending strength corresponding to the value of EN300, where standard EN300 defines mechanical properties and relative moisture resistance.

5. The method according to any one of claims 1 to 4, characterized in that, The sorting is performed at least in part using a drum screen (2) or a star screen.

6. The method according to any one of claims 1 to 4, characterized in that, The sorting performed using a drum screen (2) or a star screen includes the removal of coarse material (13).

7. The method according to any one of claims 1 to 4, characterized in that, The coarse material (13) is separated before gluing.

8. The method according to any one of claims 1 to 4, characterized in that, At least a portion of the fine material (12) is used as a coating additive.

9. The method according to any one of claims 1 to 4, characterized in that, The wood chips for the cover and intermediate layers of oriented strand board or waffle board (10) are conveyed to individual bins and then individually applied with adhesive.

10. The method according to any one of claims 1 to 4, characterized in that, The wood chips pass through a hot air separator (3) before drying.

11. The method according to any one of claims 1 to 4, characterized in that, During the dispersal process, the bark portion remaining in the sawdust is separated so that the bark portion is observed to be dispersed in the middle region on the thickness of the oriented strand board or waffle board (10).

12. An apparatus for manufacturing oriented strand board or waffle board according to the method according to any one of claims 1 to 11, said apparatus comprising at least one cutter shaft cutting machine (1), a drum screen (2), a dryer for wood chips (4), a gluing device for wood chips (5), a spreading station (6), and a continuous press (7).

13. The device according to claim 12, characterized in that, The device also includes a hot air separator (3).

14. Oriented strand board or waffle board, said oriented strand board or waffle board being manufactured according to the method according to any one of claims 1 to 11.

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