METHOD FOR PRODUCING A LAMINATED VENEER LUMBER BOARD

Abstract

A method for producing a laminated veneer lumber board adapted to be used for curved modules in which a plurality of laminated veneer lumber boards are laminated to each other to form a curved laminated wood module, where the method includes the steps of: cutting a plurality of veneer plies, placing a first part of a first set of plies in a mould with the wood grain directed in a first direction, placing a second set of plies including one or two plies with the wood grain directed to be perpendicular to the first direction on the first part, placing a second part of the first set of plies with the wood grain directed in the first direction on the second set of plies, and gluing and pressing the plies to each other to form the laminated veneer lumber board.

Claims

1. A method for producing a laminated veneer lumber board adapted to be used for curved laminated wood modules in which a plurality of laminated veneer lumber boards are laminated to each other to form a curved laminated wood module, where the laminated veneer lumber board comprises a single position having a veneer ply with the wood grain directed in a cross direction which allows the laminated veneer lumber board to be bent, where the method comprises the steps of: cutting a plurality of veneer plies, placing a first part of a first set of veneer plies in a mould with the wood grain directed in a first direction, where the first part comprises at least two veneer plies, placing a second set of veneer plies comprising a single veneer ply or two veneer plies arranged adjacent each other with the wood grain directed in a direction that is perpendicular to the first direction on the first part, placing a second part of the first set of veneer plies with the wood grain directed in the first direction on the second set of veneer plies, and gluing and pressing the veneer plies to each other to form the laminated veneer lumber board.

2. The method according to claim 1, wherein the second part comprises the same number of veneer plies as the first part.

3. The method according to claim 1, wherein the first set of veneer plies comprises at least six veneer plies.

4. The method according to claim 1, wherein the first set of veneer plies comprises eight veneer plies and the second set of veneer plies comprises a single veneer ply.

5. The method according to claim 1, wherein the thickness of a veneer ply is between 1-5 mm.

6. The method according to claim 1, wherein the laminated lumber board further comprises an outer layer of a different material.

7. The method according to claim 6, wherein the outer layer is applied after the first set of veneer plies and the second set of veneer plies have been pressed and glued together.

8. The method according to claim 6, wherein the outer layer is applied before the first set of veneer plies and the second set of veneer plies have been pressed and glued together.

9. A laminated veneer lumber board comprising: a first set of veneer plies; and a second set of veneer plies, wherein the wood grain direction of the first set of veneer plies is directed in a first direction and the wood grain direction of the second set of veneer plies is directed in a direction perpendicular to the first direction, where a first part of the first set of veneer plies is placed on one side of the second set of veneer plies and where a second part of the first set of veneer plies is placed on the other side of the second set of veneer plies, where the first part comprises at least two veneer plies, where the second set of veneer plies comprises a single veneer ply or two veneer plies arranged adjacent each other, where the laminated veneer lumber board is produced by a method according to claim 1.

10. The laminated veneer lumber board according to claim 9, wherein the second part comprises the same number of veneer plies as the first part.

11. The laminated veneer lumber board according to claim 9, wherein the first set of veneer plies comprises eight veneer plies and the second set of veneer plies comprises a single veneer ply.

12. A curved laminated wood module, wherein the curved laminated wood module comprises a plurality of laminated veneer lumber boards according to claim 9, wherein the plurality of laminated veneer lumber boards are glued and pressed together.

13. The curved laminated wood module according to claim 12, wherein the curved laminated wood module comprises at least seven laminated veneer lumber boards.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0020] The invention will be described in greater detail in the following, with reference to the embodiments that are shown in the attached drawings, in which

[0021] FIG. 1 shows an example of a laminated veneer lumber board produced by the method according to the invention,

[0022] FIG. 2a-b show examples of veneer layouts for a laminated veneer lumber board according to the invention, and

[0023] FIG. 3 shows an example of a curved laminated wood module comprising a plurality of laminated veneer lumber boards.

DETAILED DESCRIPTION OF THE DRAWINGS

[0024] The embodiments of the invention with further developments described in the following are to be regarded only as examples and are in no way to limit the scope of the protection provided by the patent claims.

[0025] FIG. 1 shows a first example of a laminated veneer lumber board, FIGS. 2a and 2b show examples of the layout of a laminated veneer lumber board, and FIG. 3 shows an example of a curved laminated wood module.

[0026] FIG. 1 shows a first example of a laminated veneer lumber (LVL) board 1 produced by the method. The LVL board comprises two sets of veneer plies 3, a first set 10 of veneer plies and a second set 13 of veneer plies. In the first set 10 of veneer plies, the direction of the wood fibres of all the veneer plies 3 are directed in the same direction. The first set 10 of veneer plies contain most of the plies, and preferably at least 80% of the number of plies. The second set 13 of veneer plies comprises in the shown example two veneer plies arranged adjacent each other with the direction of the wood fibres directed in a perpendicular direction when compared to the first set of veneer plies. In the shown example, the LVL board comprises eight veneer plies. A typical LVL board is between 2-5 meters wide and between 10-30 meters long.

[0027] The second set 13 of veneer plies may comprise a single veneer ply or two veneer plies arranged adjacent each other, or may comprise a single thicker veneer ply. The second set of veneer plies may comprise one veneer ply arranged with the wood grain direction perpendicular to the first direction, i.e., to the wood grain direction of the first set of veneer plies. The second set of veneer plies may also comprise two veneer plies arranged with the wood grain direction in the same direction and where the wood grain direction of the two veneer plies is perpendicular to the first direction, i.e., to the wood grain direction of the first set of veneer plies.

[0028] The second set 13 of veneer plies, i.e., the set of veneer plies having a wood grain direction that differs from the direction of the wood grains of the first set 10 of veneer plies of the laminated veneer lumber board, is in one example arranged in the middle of the laminated veneer lumber board. The laminated veneer lumber board in this example thus comprises a first part 11 of the first set 10 of veneer plies having three veneer plies with the wood grain direction arranged in a first direction, a second set 13 of veneer plies having two veneer plies with the wood grain direction arranged in a cross direction, perpendicular to the first direction, and a second part 12 of the first set 10 of veneer plies having three veneer plies with the wood grain direction arranged in the first direction.

[0029] The number of veneer plies in an LVL board may vary. A suitable number of veneer plies in an LVL board may e.g., be in the range between 7 to 15 veneer plies and may depend on the required thickness of the LVL board and on the production process. It is important that there is only one position in which one or more plies are arranged with the wood grain direction having a direction that differs from the first direction. If two or more plies are used, they must be arranged adjacent each other. Using a single set of plies arranged in a direction that differs from the first direction will strengthen the laminated veneer lumber board and will still allow the laminated veneer lumber board to be bent to a curved shape. A regular board having every other ply arranged crosswise will not be possible to bend without breaking at least some of the veneer plies or the complete board.

[0030] FIGS. 2a and 2b show examples of a laminated veneer lumber board adapted to be used for curved laminated wood modules comprising a plurality of laminated veneer lumber boards. The laminated veneer lumber board in FIG. 2a comprises eight veneer plies, and the second set of plies 13 comprises two veneer plies. In FIG. 2a, the first part 11 of the first set of veneer plies 10 comprises three veneer plies, and the second part 12 of the first set of veneer plies 10 also comprises three veneer plies.

[0031] The laminated veneer lumber board shown in FIG. 2b comprises seven veneer plies, and the second set of veneer plies 13 comprises a single veneer ply. In FIG. 2b, the first part 11 of the first set of veneer plies 10 comprises three veneer plies, and the second part 12 of the first set of veneer plies 10 also comprises three veneer plies. These shown laminated veneer lumber boards are symmetrical, which may be of advantage when producing a laminated veneer lumber board. Here, laminated veneer lumber boards comprising seven or eight veneer plies are shown, but other numbers of veneer plies are plausible.

[0032] When producing a curved laminated wood module 2 of a plurality of laminated veneer lumber boards, the laminated veneer lumber boards are pressed together in a glue press, where the final shape of the curved laminated wood module is obtained. When a curved laminated wood module has been glued together and the glue has cured, the edges of the curved laminated wood module may thereafter be shaped to the desired shape, e.g., to plane surfaces, by a precision router or a saw, such that relatively small tolerances are obtained. Other shapes such as rabbets or other joints are conceivable. The small tolerances help to improve the stiffness and rigidity of an assembled product. By precision routing the joint surfaces, the end surfaces of each layer can also be used to strengthen the joint.

[0033] FIG. 3 shows a curved laminated wood module 2 comprising five laminated veneer lumber boards 1 laminated to each other to form the curved laminated wood module 2. The curved laminated wood module is provided with an upper edge 4, a lower edge 5, a first side edge 6, a second side edge 7, an inner surface 8 and an outer surface 9. The shown curved laminated wood module is curved in a radial direction and straight in a longitudinal direction. A projection of a curved laminated wood module from the outer surface will resemble a rectangle where the long sides are either parallel or somewhat inclined. Curved laminated wood modules may be used for straight wooden assemblies, such as storage tanks or tubes, or for a laminated wood tower having a shape of a truncated cone. The radius of a curved laminated wood module is larger than 1 meter.

[0034] The laminated wood modules may be joined with different kinds of joints. The side edges may e.g., be provided with a tongue or a groove, such that a tongue and groove joint is obtained between two adjacent curved laminated wood modules. It is e.g., possible to provide the side edges with a double or stepped rabbet, such that a rabbet is provided with two rabbet edges provided at different heights, and two rabbet bottoms provided at different widths. Glue and screws may be used to connect two curved laminated wood modules to each other.

[0035] A curved laminated wood module will comprise wooden LVL boards where a single set of veneer plies is oriented in a different direction, i.e., where the wood fibres are directed in a different direction. This is often referred to as cross lamination. In cross lamination, one veneer ply or more veneer plies will be directed in another direction, normally 90 degrees when flat boards are manufactured. The longitudinal veneer plies, i.e., the plies having the wood grains oriented in a first direction, may e.g. mainly handle vertical loads, both pushing and pulling loads. The cross-veneer ply or plies will help to handle twisting loads acting e.g. on a tower. Since all veneer plies are securely attached to each other, the wooden sections will be able to handle high loads in different directions.

[0036] A laminated veneer lumber board is made from several veneer plies of thin wood. A veneer ply may be e.g., 3 mm thick, and with eight veneer plies a 24 mm thick LVL board is obtained. By using nine LVL boards, a curved laminated wood module being 216 mm thick can be obtained. The number of used laminated veneer lumber boards and the number of veneer plies in a laminated veneer lumber board depends on the forces that the final construction must handle. A typical laminated wood module may e.g., be 20-40 cm thick or more.

[0037] Curved laminated wood modules 2 may be mounted to each other to form a circular section. Circular sections may be mounted to each other to form a laminated wood tower. The horizontal joints between two circular sections may also be made in different ways, e.g., by offsetting the layers of the curved laminated wood modules. The joints may be glued and screwed together, e.g., by using metal plates.

[0038] It is also possible to provide a laminated veneer lumber board with an additional outer layer, e.g., another fibre composite material such as a glass fibre or carbon fibre ply or a surface treatment material. This may be of advantage if the laminated veneer lumber board will be the outermost layer in a curved laminated wood module. In one example, one of the veneer plies of the laminated veneer lumber board is replaced with a layer of another material, e.g., another fibre composite material such as a glass fibre or carbon fibre ply. This may increase the stiffness or the load carrying properties of a laminated veneer lumber board. The additional layer may be applied before or after a laminated veneer lumber board has cured.

[0039] Wood, and especially spruce, pine or birch, is a cheap and strong material suitable to be used for laminating boards from thin veneer plies. Other fibres may also be used, such as bamboo fibres, which may be laminated into boards with the fibres in a desired direction.

[0040] The invention is not to be regarded as being limited to the embodiments described above, a number of additional variants and modifications being possible within the scope of the subsequent patent claims.