JPH0250072A - Drying of lumber and dried lumber employing it - Google Patents

Abstract

PURPOSE:To reduce the difference of changing amount of dimensions due to contraction between the outer peripheral side of a lumber and the inside of the same and permit it to be effected simply without employing any special device by drying the lumber while restraining the outer periphery of the same including the cross sections thereof by a moisture permeable contraction restraining means. CONSTITUTION:A sheet body 2, moisture permeable orthogonally to the direction of the fibers of a lumber 1, is bonded on the whole of the outer peripheral surface excluding the cross sections 1a of the lumber by an adhesive agent. The sheet body 2 is bonded so as to function as a contraction restraining means restraining the contraction of the outer peripheral surface of the lumber, which is larger in the amount of contraction than the same inside of the lumber upon drying the lumber 1. A veneer or the thin sheet of lumber may be employed as the material of the sheet body 2, however, moisture permeable synthetic resin having a tensile strength capable of restraining the contraction of the lumber 1 may also be used with a low cost. The contraction of the outer periphery of the lumber 1, under being dried by natural drying or in a drying facility, is restrained and, therefore, the rate of contraction may be reduced compared with the case of normal non-restraining drying. According to this method, the difference of changing amount of dimensions due to the contraction between the inside and the outer peripheral side of the lumber 1 may be reduced whereby the cracking and/of warping of the lumber, which are generated by drying, may be prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a technique for drying wood, and in particular to a technique that is effective when applied to dry timber without cracking.

[Conventional technology]

For example, when drying wood such as square lumber for construction, annual rings exist in a nearly concentric shape on its cross section, and it retains a lot of moisture immediately after sawing, but as it dries, the moisture is removed. This causes shrinkage of the wood.

During this shrinkage, the degree of shrinkage (shrinkage -) of the wood is significantly different between the parallel direction and the perpendicular direction to the annual rings. In other words, the shrinkage rate in the direction parallel to the growth rings is twice the shrinkage rate in the direction perpendicular to the tree rings, so as the wood dries, there will be a large imbalance in dimensional changes depending on the part, especially on the end surface. Cracks may occur or the wood may become warped. Further, between the outside and inside of the annual ring, the outside has a longer circumference, so the amount of dimensional change is greater, and cracks may occur from the outside to the inside.

Such cracks and distortions tend to occur more easily in wood with a large cross-sectional area, such as columns and beams, than in board materials. If the wood is used as a construction material for visible parts, the cosmetic effect will be lost, and the commercial value of cracked or distorted wood will drop significantly.

Moreover, the living environment has changed significantly due to the improvement of air conditioning equipment such as air conditioning and heating in recent years, and in particular, wood, which is a natural building material, has difficulty adapting to rapid environmental changes. There is a strong demand for a technology that can dry wood used as construction materials such as pillars and beams without cracking or deforming.

Therefore, various countermeasures have been devised to prevent cracking and warping of wood, but none of them have reached the point where a fully satisfactory solution has been obtained.

One example of conventional techniques for preventing wood from cracking is a method of applying so-called back-splitting treatment in which saws are cut down to the core of the wood, thereby releasing stress that occurs due to drying at the back-splitting portion.

Another method of preventing cracking of wood is to apply polyethylene glycol to the surface of the wood and dry it.

[Problem to be solved by the invention]

However, among the conventional techniques mentioned above, in the case of crack prevention technology by back-splitting treatment, serrations remain on the back-splitting surface, so if the wood is used for pillars, for example, the back-splitting surface may be placed on the side hidden by the wall, or it may be placed in an alcove. The use of the back-splitting material is limited, as it must be placed on the back side where it cannot be seen by the public eye. Moreover, splitting treatment alone cannot completely prevent wood from cracking, and problems such as cracking of decorative pillar materials may occur after the house is completed or moved in.

On the other hand, among the conventional techniques mentioned above, in the case of the method of applying polyethylene glycol to the surface of wood and drying it, 1) the price of polyethylene glycol is high, 2) the dried product easily absorbs moisture, and 2) the dried wood may discolor. The inventor has discovered that there are problems such as loss of wood texture.

One object of the present invention is to provide a method for drying wood that can reliably prevent cracking of wood due to drying, and wood dried using the method.

Another object of the present invention is to provide a method for drying wood that can be easily carried out without using special equipment, and wood dried using the method.

Another object of the present invention is to provide a method for drying wood that can be carried out at low cost and wood dried using the method.

Still another object of the present invention is to provide a method for drying wood that can dry wood without causing problems such as discoloration, and wood dried using the method.

[Means to solve the problem]

The method for drying wood according to the present invention is to dry the wood while restraining the outer periphery of the wood, including at least the end of the wood, with a water-permeable contraction restraining means.

As the shrinkage restraining means, a moisture-permeable plate can be used, which plate is glued to the outer periphery of the wood.

Further, the shrinkage restraint means can be disposed on the entire outer periphery of the wood or partially on the outer periphery of the wood including at least a part of the outer periphery of the end portion.

Furthermore, in the present invention, the wood is a polygonal wood that has been split in the back, and the shrinkage restraint means is bonded to at least the outer peripheral surface of the butt end of the outer peripheral surface of the polygonal wood other than the split surface. can do.

Further, the wood of the present invention is obtained by the drying method described above.

[Effect]

According to the above-mentioned method, the wood is dried with its outer periphery, which can cause cracks and warping, being restricted, so the outer periphery of the wood during drying cannot contract freely, which can lead to cracks and warping caused by drying. Madness can be prevented.

That is, as a result of intensive research by the present inventor, wood has the following properties, and by investigating these properties, the present invention was completed by utilizing them. ■If the shrinkage of wood is restrained during drying, the shrinkage rate of the restrained part will be smaller than that of the normal unrestricted case.■Wood has a liquid property during the drying process, and dimensional changes can be suppressed with a small force. Once dried, it exhibits solid rigidity and becomes a stable material against external forces, without cracking or deformation.

[Example 1] FIG. 1 is a perspective view showing an example of wood to which an embodiment of the drying method according to the present invention is applied.

In the present invention, the wood to be dried can be a log sawn into a polygon such as a square, a hexagon, or a hexagon, or other shapes, but in this example, the wood is sawn into a square shape. Wood 1 is used.

A moisture-permeable plate-like body 2 is attached with adhesive on the entire outer peripheral surface of the wood 1 except for the end surface 1a (including the outer peripheral surface of the end portion) in a direction perpendicular to the direction of the fibers of the wood 1. It is glued.

The plate-like body 2 functions as a shrinkage restraining means for restraining and suppressing the shrinkage of the outer circumferential surface of the wood 1, which shrinks more than the inside, when the wood 1 dries. As the material for this plate-like body 2, a wood veneer or a thin plate can be used, but a water-permeable synthetic resin that has a tensile strength that can restrain the shrinkage of the wood 1 can be used at low cost. .

In this embodiment, as described above, the end surface 1a of the wood 1 is
With the moisture-permeable plate-like material 2 adhered to the entire outer circumferential surface excluding the outer circumferential surface (including the outer circumferential surface of the butt end), the wood 1 is naturally dried or dried using a drying equipment (not shown), for example, using a high-frequency vacuum drying method. Dry artificially.

As a result, the shrinkage of the outer circumferential side of the wood 1 during drying is restrained, so that the shrinkage rate becomes smaller than in the case of normal unrestricted wood 1.

Therefore, in this example, the shrinkage rate of the wood 1 near the internal pith, where the shrinkage rate is originally small, and the shrinkage rate of the outer peripheral part, where the shrinkage rate is originally high, are such that the outer circumferential surface is in an unrestricted state. They are closer to each other than when drying is carried out, and the difference in the amount of dimensional change due to shrinkage between the inner side and the outer circumferential side of the wood 1 becomes smaller.

As a result, according to this embodiment, it is possible to prevent cracking and deformation of the wood 1 to be dried.

After the wood 1 has been dried to reach the desired moisture content, the plate-shaped body 2 is removed from the wood 1, thereby obtaining the wood 1 without cracks or distortions as described above.

By the way, Fig. 4 is a diagram showing the drying process of zelkova square lumber (12 cm square) by the high-frequency vacuum drying method that the present inventor experimented with, and Fig. 5 shows the shrinkage rate of each part of the wood during drying in the present invention. It shows.

Wood naturally has a property that the shrinkage rate is smaller in the parallel direction (the outer periphery) than in the direction perpendicular to the growth rings (in the center of the timber), but from the experimental results shown in Figure 5, in the present invention, the It can be seen that this property is reversed by restricting the contraction. In other words, it is understood that this prevents the wood from cracking from the outer periphery toward the pith.

[Embodiment 2] FIG. 2 is a perspective view of wood showing a drying method according to another embodiment of the present invention.

In this embodiment, the plate-shaped body 2 serving as the shrinkage restraining means is not provided over the entire outer circumferential surface of the timber 1, but rather at predetermined intervals in the direction perpendicular to the length direction (fiber direction) of the timber 1. and partially glued.

In the case of this embodiment, the parts to which the plate-like body 2 is not glued will dry faster than other parts, but the plate-like body 2 should always be glued to the outer periphery of the end of the wood 1. By doing so, it is possible to prevent cracks from occurring from the butt end surface 1a where cracks are most likely to occur, so that it is possible to obtain the wood 1 without cracks as a whole.

Moreover, in this embodiment, the material costs for the plate-shaped body 2 and its adhesive can be saved.

[Embodiment 3] FIG. 3 is a perspective view of wood showing a drying method according to still another embodiment of the present invention.

In this embodiment, one of the outer circumferential surfaces of the wood 1 is formed as a so-called back split surface, and the length direction (fiber direction)
Saws 3 for back splitting are cut along the inside of the wood 1 to the pith.

The plates 2 are also partially glued in a direction perpendicular to the length of the wood 1, as in Example 2, but at smaller intervals. However, the plate-like body 2 is not adhered to the split surface of the wood 1.

Therefore, in this embodiment, the cracking prevention effect due to the shrinkage restraint effect of the plate-shaped body 2 and the cracking prevention effect due to the stress release effect due to back splitting are synergistically exhibited, so that the wood 1 can be prevented from cracking more reliably. It is possible to prevent deviations.

Note that the present invention is not limited to the embodiments 1, 2, and 3, and various other modifications are possible.

For example, in Examples 1 and 2.3, the wood 1 is made of a hardwood, but the wood 1 is not limited to this. The present invention can be widely applied to drying of the highest quality wood, etc., which is difficult to dry.

Further, when artificial drying is performed as a drying method for the wood 1, an appropriate method other than the high frequency vacuum drying method can be selectively used.

Further, the material and shape of the plate-like body 2 as the contraction restraining means can be arbitrarily selected, and for example, a self-adhesive adhesive-coated band-like body can be used.

Further, the present invention can be applied to wood other than square timber.

〔Effect of the invention〕

(1) 1 According to the wood drying method of the present invention, wood is dried by natural drying or artificial drying, comprising:
By drying while restraining the outer periphery of the wood, including at least the end of the wood, with moisture-permeable shrinkage restraining means, the difference in dimensional change due to shrinkage between the outer periphery and the inner side of the wood can be reduced, and the Cracks and distortion can be reliably prevented.

(2) 1 The wood drying method of the present invention does not require the use of special equipment and can be easily carried out.

(3) 1 The wood drying method of the present invention can be implemented at low cost.

(4) 1 According to the wood drying method of the present invention, wood can be dried without causing problems such as discoloration of the wood.

(5) By partially arranging the contraction restraint means on the outer periphery of the wood, including at least a part of the outer periphery of the butt end,
Material costs and labor for shrinkage restraint means and the like can be saved.

(6) The wood is a polygonal piece of wood with a spine split, and a shrinkage restraint means is bonded to at least the outer circumferential surface of the butt end of the outer peripheral surface of the polygonal wood other than the side where the spine has been split. As a result, the effect of preventing wood from cracking due to the shrinkage restraint substitution of the shrinkage restraint means and the effect of preventing wood from cracking due to the stress release effect of the back splitting are synergistically exhibited, making it possible to more reliably prevent wood from cracking and warping. It can be realized.

(7) By using a water-permeable synthetic resin as the shrinkage restraining means, cost reduction can be achieved.

(8) 8 Wood dried using the drying method of the present invention is
It is possible to prevent cracking, distortion, and even discoloration, resulting in high commercial value.

(9), According to (8) above, the wood of the present invention can be used in places where the outer periphery is visible from the outside, making it possible to expand the uses of wood and improve its utility value. Unique advantages such as texture can be effectively utilized.

αO1 According to the above (8), the wood of the present invention can be sufficiently and easily applied as pillars, beams, etc. of buildings equipped with air conditioning equipment such as air conditioning and heating in recent years.

[Brief Description of the Drawings] Fig. 1 is a perspective view showing an example of wood to which an embodiment of the drying method according to the present invention is applied, and Fig. 2 is a perspective view of wood showing an example of the drying method according to another embodiment of the present invention. 3 is a perspective view of lumber showing a drying method according to still another embodiment of the present invention, and FIG. FIG. 5 is a diagram showing the shrinkage rate of each part of the wood upon drying in the present invention. 1...Wood, 1a...Butt end surface, 2...Plate body (shrinkage restraint means), 3...Saws for back splitting. Patent applicant Asahi Mokuzai Co., Ltd. Agent Patent attorney Dai Tsutsui Sodo Patent attorney Hide Matsukura Mima Patent attorney Toshio Nakano (%)

Claims (1)

[Claims] 1. A method for drying wood by natural drying or artificial drying, characterized in that the outer periphery of the wood, including at least the end of the wood, is dried while being restrained by moisture-permeable contraction restraint means. How to dry wood. 2. The method for drying wood according to claim 1, characterized in that a moisture-permeable plate-like body is used as the shrinkage restraining means, and this plate-like body is adhered to the outer periphery of the wood. 3. The method for drying wood according to claim 1 or 2, characterized in that the shrinkage restraining means is arranged around the entire outer periphery of the wood. 4. The method for drying wood according to claim 1 or 2, characterized in that the shrinkage restraining means is partially disposed on the outer periphery of the wood including at least a part of the outer periphery of the end of the wood. 5. The wood is a polygonal wood that has been split along the back, and the shrinkage restraining means is attached to at least the outer peripheral surface of the end of the outer peripheral surface of the polygonal wood other than the split surface. The method for drying wood according to claim 4, characterized in that: 6. Wood dried by the drying method according to claim 1, 2, 3, 4 or 5.