JP2511781B2 - Method of manufacturing compressed wood - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing compressed wood.

[0002]

2. Description of the Related Art Generally, softwood materials are softer than hardwood materials, have less dimensional stability, and have a large difference in specific gravity and surface hardness between the spring wood part and the summer wood part. It is necessary to improve these properties before using it as a material for interiors and interiors.

Therefore, it is common practice to compress the wood between the platens of the press to improve the above properties. This is because the Brinell hardness is 2.0 kg / by compressing the softwood to a thickness of about half, for example.
It is a compressed wood having properties close to those of hardwood, such as around mm ² and a specific gravity of 0.6 to 0.8.

Further, in order to prevent the compressed wood from being restored due to moisture absorption and to improve its dimensional stability, the wood is impregnated with a thermosetting resin such as phenol and then heated by heat conduction from the platen surface. However, it is also common to perform compression processing.

In addition to the general platen having a smooth platen surface, the compression processing as described above is performed by the method described in JP-A-58-893.
It may be performed using a platen having a large number of fine irregularities formed on the platen surface, as described in Japanese Patent Publication No. 03-2003.

[0006]

However, the above-mentioned conventional techniques have the following problems. That is, when compressed using a general platen having a smooth platen surface, because the platen surface and the wood surface are slippery,
With the compression, the wood expanded mainly in the direction perpendicular to the compression direction and perpendicular to the fiber direction of the wood (that is, the width direction of the wood). Then, during such elongation, tensile stress in the elongation direction is generated inside the wood, which sometimes breaks the wood.

[0007] In particular, wood whose grain is symmetrical on the left and right often breaks along the fiber direction at the central portion in the width direction due to the annual ring structure. Further, in the wood with the knots, stress concentrates on the knots, so that cracks are likely to occur in these parts. Furthermore, in wood that has minute cracks that cannot be visually identified, stress concentrates on the cracks and the cracks spread during compression.

Furthermore, when the wood impregnated with the thermosetting resin is compressed while being heated, the hardening of the thermosetting resin proceeds from the surface layer of the wood toward the inside, so that the surface layer of the wood is With respect to the above, the thermosetting resin was cured to a certain extent and was allowed to be stretched in a state where the plasticity was lowered, which sometimes caused cracks in the surface layer portion.

For the above reasons, cracking during compression frequently occurs, so that the product yield of compressed wood is low.

On the other hand, when compression is performed using the platen described in Japanese Patent Application Laid-Open No. 58-89303, in which a large number of fine irregularities are formed on the platen surface, the surface of the wood is affected by the irregularities of the platen surface during compression. The wood is stuck to the surface of the platen due to the high friction coefficient of the platen surface due to the unevenness, though the above-mentioned elongation is suppressed and the cracking of the wood is prevented because of the restraint. was there.

In particular, when the wood impregnated with the thermosetting resin in advance is compressed while being heated, the thermosetting resin of the surface layer of the wood which has been hardened by heating plays the role of an adhesive, so that the wood is pressed. It will be firmly attached to the board. Therefore, it takes a lot of time and labor to remove the compressed wood from the platen surface, resulting in low work efficiency.

Further, if the compressed wood stuck firmly is attempted to be forcibly removed from the platen surface, the surface layer portion in contact with the platen surface of the compressed wood may peel off, resulting in a product yield of the compressed wood. It was supposed to drop.

The present invention has been made in view of the problems of the prior art as described above, and it is possible to prevent damage to wood such as cracks and peeling of the surface layer portion and to increase the product yield, and It is an object of the present invention to provide a method for producing compressed wood that can prevent sticking of wood to the platen surface and improve work efficiency.

[0014]

In order to achieve the above object, the method for producing a compressed wood according to the present invention comprises forming a large number of fine irregularities on at least one of a pair of platens facing each other of a press, The present invention is characterized in that the release member is arranged in the recess, and the wood is compressed while suppressing the expansion of the wood due to the unevenness.

[0015]

According to the method for producing a compressed wood according to the present invention, the surface of the wood is restrained by the unevenness formed on the platen at the time of compression, and the expansion of the wood is suppressed. The stress is also reduced, and cracking of the wood is prevented, and sticking of the wood to the platen surface is prevented by the release member disposed in the recess of the platen surface.

[0016]

Embodiments of the present invention will be described below. The press used here is, for example, as shown in FIG. That is, four vertical divers 3 are erected on the base 2 of the press 1, and the upper fixed platen 4 is provided on the vertical divers 3.
Is fixed. A movable plate 5 is provided below the upper fixed plate 4.
Is provided so as to be vertically movable by the ram cylinder 6 while being guided by the vertical diver 3. The upper fixed platen 4 has an upper platen 7, and the movable platen 5 has a lower platen 8.
Are mounted so that they face each other. Reference numeral 9 is an operating valve for expanding and contracting the ram cylinder 6 by hydraulic pressure to move the movable platen 5 up and down, and 10 is a pressurizing operating handle 10 for opening and closing the operating valve 9.

The lower platen 8 has a large number of fine irregularities formed on the platen surface. As shown in FIG.
Is formed in a substantially conical shape having a height h of 0.5 mm, and such a convex portion 11 has a distance d between the tip portions of 1.0.
A large number are provided on the entire surface of the platen with a density of mm. The upper platen 7 is a general platen having a smooth platen surface.

The wood to be compressed is, for example, as shown in FIG.
Is like. That is, tree species of wood Hinoki wood shape and dimensions Semi-circular wood W 90-100 mm L 50 mm H 40-50 mm Water-containing state Saturated water-absorption state (state in which raw wood after sawing is soaked in water) Wood temperature approximately 20 ° C (Without heating)

Further, in the following description, the "extension rate" of wood means the extension rate (%) when the dimension before compression processing in the direction of extension of the wood is a and the dimension after compression processing is b. = (B−a) ÷ a × 100, and the “compression set ratio” means that when the thickness of wood before compression processing is A and the thickness after compression processing is B, It is a value calculated by the compression set rate (%) = (A−B) ÷ A × 100.

Next, an example in which the wood shown in FIG. 3 is compressed by using the press 1 will be described. First of all,
The reverse side of the tree (center side of the tree) was placed on the platen 8 and the compression process was performed while changing the compression set rate in the range of 7% to 55%. For comparison, the platen 8 was replaced with a general platen having a smooth platen surface, and the same compression treatment was performed under the same conditions.

As a result, when a general platen is used, the elongation ratio in the direction perpendicular to the wood fibers (direction of width W shown in FIG. 3) is as shown in the graph of FIG. It increased almost directly. Then, when the compression set rate reached 21% (extension rate about 2%), cracks were found on the back side of the wood, and thereafter the cracks became larger as the compression set rate increased. In contrast,
When the platen 8 having the platen surface with irregularities is used, the extension rate is 0.3% at the compression set rate of 21%, and is 1.5% even at the compression set rate of 55%. No cracks were found in the wood at any time.

Then, using the platen 8 in which the platen surface has irregularities as described above, the wood having small knots and the wood having extremely fine cracks were compressed, but the frequency of occurrence of new cracks was high. Since the cracks were low and the original cracks were slightly expanded, a compressed wood that could withstand practical use was obtained.

Further, similarly to the above, a platen 8 having irregularities formed on the platen surface is used, and a Teflon sheet 12 made of Teflon (trademark of DuPont) resin having a thickness of 0.05 mm is used as a releasing member on the platen surface. It was spread, and unnecessary wood was placed on it and pressed. As a result, as shown in FIG. 5, a hole is formed in the Teflon sheet 12 by the convex portion 11, and the tip of the convex portion 11 projects from this hole, and the Teflon sheet 12
Since it became a state of being fitted into the concave portion 13, the temperature of the platen was raised and the wood impregnated with the phenol resin in advance was compressed while being heated by heat conduction from the platen surface.

According to this, since the timber is directly restrained by the tip of the convex portion 11 protruding from the Teflon sheet 12 during compression, the restraining force on the timber is lower than that in the case without the Teflon sheet 12. In the same manner as above, the elongation of the wood was suppressed. Therefore, no cracks were observed in the wood surface layer portion when the phenol resin was hardened and stretched in a state where the plasticity was lowered.
Also, if the wood impregnated with the phenol resin expands unevenly in parts, hardness and color unevenness may occur on the surface of the compressed wood due to residual unevenness of the resin. No unevenness was observed.

Further, the Teflon sheet 1 having a low friction coefficient
Since 2 is arranged in the recessed portion 13, the wood does not stick to the platen surface even though it is impregnated with the phenol resin, and the compressed wood can be easily removed from the platen surface for compression work. Could be done efficiently.

A large amount of wood can be compressed by one Teflon sheet 12, and the Teflon sheet 12 can be easily removed when the sheet is damaged or when the phenol resin protruding from the wood adheres to the sheet surface. It was possible to remove it from the platen surface and replace it with a new sheet.

In order to make the tip of the convex portion 11 project from the Teflon sheet 12 as in the present embodiment, the tip of the convex portion 11 is sharpened to some extent and the thickness of the Teflon sheet 12 is increased. It was preferable to make the shape corresponding to the height and shape of the convex portion 11.

Also, instead of the Teflon sheet 12, a similar effect can be obtained by using a sheet made of polyester resin. Further, instead of disposing such a releasable sheet in the recess 13 of the platen surface, a similar effect can be obtained by forming a coating layer of Teflon resin on the platen surface as a releasable member. In this case, the coating is applied only to the concave portion 13 on the platen surface, and the tip of the convex portion 11 has a releasing member (coating layer) as in the state shown in FIG.
If it was made to project further upward, the binding force on the wood did not decrease.

Further, a substantially conical projection 11 provided on the platen surface
If the height is too low, the effect of restraining the wood will be insufficient, and if it is too high, it will damage the surface layer of the wood.
It is preferable that the height h of the convex portion 11 is in the range of 0.2 to 1.0 mm.

Further, instead of providing a large number of substantially conical projections 11 as described above, a large number of parallel ridges are formed on the platen surface at predetermined intervals, and between these ridges and between the ridges. You may make it uneven | corrugated with the groove part formed in.

Further, instead of directly forming the unevenness on the platen surface as described above, 4 is formed on the entire flat platen surface.
Sandpaper from 0 to 120 (waterproof paper)
Was adhered and the wood grain surface was restrained by the abrasive grain surface of this sandpaper, the same effect as described above was obtained.

Incidentally, cracks due to compression are generally more likely to occur on the wood surface side (bark side) than on the wood back side (tree center side), but the semi-circular shape with a small curvature as shown in FIG. In the case of wood, the back side of the tree is easier to crack. In the above,
It is for this reason that the back side of the wood of FIG. 3 is directed to the platen 8. However, in the present invention, it goes without saying that the upper platen 7 may be formed with the same unevenness as the platen 8 to restrain the wood from both the upper and lower sides.

[0033]

As described above, according to the method for manufacturing a compressed wood according to the present invention, the unevenness of the platen surface suppresses the expansion of the wood during compression and prevents the cracks from occurring. Wood and compressed wood that can be a product from wood with fine cracks can be manufactured, and the surface layer of wood does not crack even when compressed while heating wood impregnated with a thermosetting resin, Moreover, since the release member disposed in the recess of the platen surface prevents the wood from sticking to the platen surface, the compressed wood can be easily removed from the platen surface,
At that time, the surface layer of the compressed wood does not peel off. Therefore, the product yield of the compressed wood can be improved and the work efficiency can be improved.

[Brief description of drawings]

FIG. 1 is a front view of a press used to carry out the present invention.

FIG. 2 is an enlarged cross-sectional view of a main part showing a platen surface on which irregularities are formed.

FIG. 3 is a perspective view showing wood before compression processing.

FIG. 4 is a graph showing a relationship between a compression set rate and an expansion rate.

FIG. 5 is an enlarged sectional view of an essential part showing a platen surface in which a Teflon sheet is arranged in a recess.

[Explanation of symbols]

 1 Press 8 Platen 11 Protrusion 12 Teflon Sheet (Example of Releasing Member) 13 Recess

Claims (1)

(57) [Claims] 1. A press is provided with a large number of fine irregularities formed on at least one of a pair of platens facing each other, and a mold release member is disposed in the concaves while suppressing the elongation of wood by the irregularities. A method for producing compressed wood, characterized in that it is compressed.