JPH0852702A - Plywood and manufacture thereof - Google Patents

Abstract

PURPOSE:To provide a plywood which hardly warps by layering and attaching with pressure a plurality of veneers arranged on both sides of a core veneer such that the heart-sides are opposed to the core veneer. CONSTITUTION:On one side of a core veneer 40, a face veneer 20 and a crossband veneer 30 are layered such that respective heart-sides 24 and 34 are opposed to the core veneer 40. On other side of the core veneer 40, a back veneer 60 and a crossband veneer 50 are layered such that respective heart-sides 64 and 54 are opposed to the core veneer 40. The layered five veneers are joined by pressing with an adhesive so as to obtain a plywood 10. That is, the face veneer 20 and the back veneer 60 to be arranged on the surfaces of the plywood are layered such that respective sap-sides 22 and 62 face the surface sides. As a result, forces in warping direction of the veneers to warp toward the sap-sides and the recesses directed inward can be relaxed each other at both sides of the core veneer with center at the core veneer 40, so that the plywood hardly warps.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of manufacturing plywood and plywood.

[0002]

2. Description of the Related Art So-called plywood, which is formed by laminating and pressing a plurality of single plates so that their fiber directions are orthogonal to each other, is widely used as a building material. Conventionally, the following method is known as a method for manufacturing plywood.

First, as shown in FIG. 3, a raw wood 80 is cut into a thickness of about 1 to 3 mm by using a rotary lace 90 or the like. Next, the cut plate is cut into a predetermined size, and a single layer of veneer is manufactured through a drying process.

Then, a plurality of manufactured veneers are laminated and pressure-bonded with an adhesive to manufacture one plywood. As shown in FIG. 4, the veneers are laminated so that the fiber directions of the veneers 82, 84 and 86 are orthogonal to each other. The number of stacked layers is usually an odd number.
There are 7 plywood boards.

The surface of the veneer made from raw wood is
It is divided into a wood surface that is closer to the bark and a wood surface that is closer to the tree heart.When manufacturing plywood, make sure that both surfaces of the plywood are the front surface of the plywood. Except for stacking so-called face veneer and back veneer with the wood surface facing the front side, the veneer placed in the intermediate layer between the face veneer and the back veneer is a wood table (back of wood). Are stacked in the same direction.

[0006]

However, as a property of a normal plate material, since the wood surface shrinks more than the wood back, the wood surface tends to warp in a concave shape with the wood surface facing inward. In the conventional plywood manufacturing method in which the front (wooden backs) are laminated in the same direction, the warping force acts in the same direction, so that there is a problem that the finished plywood tends to warp. Especially, the ratio of swelling and contraction with respect to increase / decrease in water content was large, and the warp was likely to occur in the plywood made of coniferous veneer, which is easily warped.

The present invention has been made in view of the above problems, and an object thereof is to provide a plywood manufacturing method and a plywood which are less likely to warp.

[0008]

In order to achieve the above-mentioned object, the invention according to claim 1 has a plurality of veneers arranged on both sides of a core veneer, and the veneer of the surface layer has a wooden surface. In the method for manufacturing a plywood which is arranged on the surface and laminated and pressure-bonded, each of the plurality of veneers arranged on both sides of the core veneer is laminated and pressure-bonded with the underside of the core veneer facing. It has a feature.

According to a second aspect of the present invention, in the method for manufacturing plywood, a plurality of veneers are arranged on both sides of a core veneer, and the surface veneers are laminated and pressure-bonded with a wooden surface on the surface. Each of the plurality of veneers arranged on both sides of the core veneer is characterized in that the veneers are laminated and pressure-bonded such that the wood backs face each other or the wood fronts face each other.

According to a third aspect of the present invention, a plurality of veneers are arranged on both sides of the core veneer, and the veneer of the surface layer is a plywood laminated and pressure-bonded with a wood surface on the surface. Each of the plurality of veneers arranged on both sides of the veneer is characterized by being laminated and pressure-bonded with the back of the core facing the veneer.

[0011]

According to the inventions of claims 1 and 3, a plurality of single plates arranged on both sides of the core single plate respectively,
The force that tends to warp in a concave shape with the wooden surface facing inward can be mitigated on both sides of the core veneer centering on the core veneer, and a plywood that does not easily warp can be obtained.

According to the second aspect of the present invention, in the plurality of veneers arranged on both sides of the core veneer, the force for bending the veneer of each veneer inwardly toward the concave shape. Can be relaxed with each other by laminating the single boards laminated with the backs of the trees or the fronts of the trees facing each other, and it is possible to obtain a plywood that is less likely to warp.

According to the inventions of claims 1 to 3, the proportion of swelling and shrinking with respect to the increase or decrease of the water content is large,
Even if a softwood veneer that tends to warp is used, the force in the warp direction of the veneer can be alleviated, and plywood that does not easily warp can be obtained.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT A preferred embodiment of the present invention will now be described in detail with reference to the drawings.

FIG. 1 shows a plywood 10 according to an embodiment of the present invention.
FIG.

The plywood 10 is a face single plate 20 forming a surface layer.
And the core veneer 40 that forms an intermediate layer between the back veneer 60
And a five-layer structure in which the cross band single plates 30 and 50 arranged on both sides of the core single plate 40 are laminated and pressure-bonded,
All the veneers that make up the plywood 10 are softwood veneers.

The plywood 10 is manufactured by laminating the individual veneers manufactured from softwood logs in the following method and press-bonding them with an adhesive.

The face single plate 20 is provided on one side of the core single plate 40.
And the cross band veneer 30 are laminated with the backs 24 and 34 of the core veneer 40 facing each other, and
On the other side of the core single plate 40, a back single plate 60 and a cross band single plate 50 are laminated with the wood backs 64 and 54 facing the core single plate 40.

The core single plate 40 is arranged with the wooden surface facing either direction on either surface side.

The plywood 10 is manufactured by press-bonding the five laminated single plates as described above with an adhesive.

Since both the face veneer 20 and the back veneer 60 arranged on the surface layer of the plywood face the wood tables 22, 62 to the front side, the plywood 10 is used on the front side on any surface. It is possible.

By laminating and crimping each veneer by the above-mentioned method, the warping force of each veneer, which tends to warp the wood surface inwardly toward the concave side, with the core veneer 40 as the center, is applied. It is possible to manufacture the plywood 10 which can be relaxed from each other on both sides and which is less likely to warp.

Next, a test result for verifying that the plywood 10 according to this embodiment has a small deviation (warpage) will be described. Plywood Deflection Test Plywood A and Plywood B (dimensions of A and B: 918 mm × 1) produced by changing the lamination method as follows using a single plate made of radiata pine which is a conifer as a test sample.
834 mm, thickness 12 mm), two types of plywood were manufactured by changing the water content (one that was water-impregnated after crimping and one that was water-tipped twice) to prepare test samples.

Plywood A (manufacturing method according to this embodiment): A plurality of single plates are laminated on both sides of the core single plate and laminated under pressure with the back of the core facing the core single plate. Manufacturing method): The veneers on both surfaces of the plywood (face veneer and back veneer) face the wood side, and the veneers that form the intermediate layer between the face veneer and the back veneer are in the same direction. As a test method, each manufactured plywood was cured, left in a constant temperature and humidity chamber (20 ° C, 85%) for 20 days, then removed from the constant temperature and humidity chamber, and then at room temperature for 7 days. After leaving it, the warp amount (arrow height) at each of eight positions a to h shown in FIG. 2 of each plywood.
Was measured, and the average of 8 points was used as the measured value. Then, the average of the measured values of each test sample was calculated, and the warpage amounts of the plywood A (manufacturing method according to this example) and the plywood B (conventional manufacturing method) were compared.

After the single plate was pressure-bonded, the plywood A and the plywood B, which had been water-washed once, showed that the warp amount of the plywood A was 1.7 mm and the warp amount of the plywood B was 2.3 mm. It can be seen that the plywood manufactured by the manufacturing method according to the example has a smaller amount of warp than the plywood manufactured by the conventional manufacturing method.

Further, the measurement results of the plywood A'and the plywood B'which have been water-washed twice after the single-ply pressure bonding are the plywood A '.
The amount of warp is 2.1 mm, and the amount of warp of plywood B'is 3.7 mm
Therefore, in this case as well, it can be seen that the plywood manufactured by the manufacturing method according to this embodiment has a smaller amount of warp than the plywood manufactured by the conventional manufacturing method.

As described above, according to the manufacturing method of this embodiment, it is possible to obtain the plywood which is less likely to warp. In particular,
The ratio of swelling and contraction is relatively large with respect to the increase or decrease in the water content, and even when a softwood veneer that tends to warp is used, it is possible to obtain a plywood that does not easily warp, which is a great effect.

The present invention is not limited to the above embodiments, and various modifications can be made within the scope of the invention. For example, the veneer stacking method may be any method as long as it can relax the force in the warp direction of each veneer. They may be laminated with each other or with the backs of the trees facing each other. In this case, the warp force of each veneer can be mitigated by the veneers laminated with the front and back sides of the trees facing each other. However, also in the case of this modification, the face veneer and the back veneer arranged on the surface layer face the front side.

The number of plywood to be laminated is not limited to 5, and any number of 5 or more may be used.

Further, as the veneer, various veneers such as lauan wood, hardwood and conifer can be used.

[0031]

As described above, according to the present invention,
It is possible to relieve the forces of the veneer from warping in a concave shape with the wooden surface facing inward, and obtain a plywood that is less likely to warp.

Further, even if a coniferous veneer, which has a large swelling and contracting rate with respect to increase / decrease in water content, and is prone to warping, the force in the warping direction of the veneer can be alleviated, so that plywood that does not easily warp There is an effect that can be obtained.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing a plywood according to this embodiment.

FIG. 2 is a plan view showing measurement points of a plywood deviation test.

FIG. 3 is a diagram showing a cutting process of a single plate.

FIG. 4 is a perspective view showing a stack in which the fiber directions of the single plates are orthogonal to each other.

[Explanation of reference signs] 10 plywood 20 face veneer 30,50 cross band veneer 40 core veneer 60 back veneer 22,62 wood front 24,34,54,64 wood back

Claims (3)

[Claims] 1. A method of manufacturing a plywood in which a plurality of veneers are arranged on both sides of a core veneer, and the surface veneers are laminated and pressure-bonded with a wooden surface on the surface. A method for manufacturing plywood, wherein each of the plurality of veneers arranged in step 1 is laminated and pressure-bonded with the underside of the core facing the veneer. 2. A plurality of veneers on each side of the core veneer,
In the manufacturing method of the plywood in which the surface veneer is arranged by laminating a wooden surface on the surface and laminating and crimping, each of the plurality of veneers arranged on both sides of the core veneer is a wood veneer or a wood veneer. A method for manufacturing plywood, which comprises laminating and press-bonding wooden surfaces so that they face each other. 3. A plurality of veneers are arranged on both sides of the core veneer, and the veneer of the surface layer is a laminated and pressure-bonded plywood with a wooden surface on the surface. The veneers are arranged on both sides of the core veneer. A plywood, wherein each of the plurality of veneers thus produced is laminated and pressure-bonded with the inner side of the core facing the veneer of the core.