JP2004025822A - Method for drying log - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a dried log which has a less deterioration of a strength-nature and a less unbalance of a dimensional change by reducing the generation of a cracking-by-drying as far as possible and dispersing its generation by reducing the drying rate for preventing the generation of the cracking-by-drying always caused by drying a log as it is. <P>SOLUTION: A wet timber log is shaved cylindrically and dried in atmosphere to get a moisture content of about 20 to 25%. After that, a woody veneer dried sufficiently or a web-like material consisting of a fibrous material sheet is coated with an adhesive. The coated material is wound up helically while making its fiber direction crossed and pressed for producing a cylindrical compound material. Thereby, even if the cylindrical compound material is used as a pole as it is, there is neither deflection-deviation nor generation of a big cracking-by-drying. Therefore, it can be gradually dried while using it for construction for a long time. A compound pole which may not suffer the damage by an external fire, rot bacillis and vermins can be obtained by subjecting the winding up web-like material with a chemical treatment if required at this time. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a method for drying wooden round pillars used for, for example, wooden buildings.
[0002]
[Prior Art and Problems to be Solved by the Invention]
Timber logs are used as pillars for large structures such as temples and shrines and event halls, and as main pillars in the entrance and lobby of ordinary houses. In these applications, it is necessary to pre-dry the logs in order to stably secure the strength of the logs in use, especially the bonding strength with other members, and to avoid the occurrence of bending or twisting during use. is there. However, since the shrinkage in the tangential direction of the log due to drying is about twice the shrinkage in the radial direction, it is difficult to avoid the occurrence of dry cracks in the radial direction. Conventionally, various methods have been used to minimize this cracking. For example, underwater storage and shade drying have been devised to dry over a long period of time while maintaining a gentle water gradient, to alleviate the internal water stress, and to prevent large cracks from occurring. However, this method requires a great deal of time and effort, and has a problem that it is difficult to meet social demands. Recently, a method has been adopted in which a spine is placed on one side of a pillar to relieve the stress caused by short-term drying by deforming the spine and prevent the other surface from drying. ing. In this case, there is a problem that the strength is inevitably reduced due to the split of the spine, and the treatment of the split of the spine is difficult in the case of a round pillar visible from all sides.
[0003]
In addition, a large container and a large amount of a chemical solution are required to impart fire resistance, antiseptic properties and insect repellency to logs by chemical treatment. There are problems such as the necessity of large-scale equipment such as the use of a decompression / pressurization tank, the use of an extra chemical solution, and the enormous amount of time and labor required for drying logs after treatment.
[0004]
[Means for Solving the Problems]
As a method of solving such a problem, the following method has been devised and found to be effective.
[0005]
First, a wooden veneer or a fibrous material sheet is processed into an endless band (hereinafter referred to as a veneer such as a veneer) by sewing or bonding with a fiber or the like. Prepare what has been subjected to the processing of. The veneer such as a single plate is sufficiently dried in advance.
[0006]
On the other hand, wood logs are rounded in the dry state, processed into a cylindrical body, air-dried in a well-ventilated state, and waited until the water content on the surface is reduced to about 20 to 25% and bonding is possible. .
[0007]
Then
[0005] A single-plate or the like strip-shaped body coated with an adhesive is spirally wound on the surface of the wood log in at least two or more layers, with the winding direction being changed for each layer, and a cosmetic simple sheet is placed thereon. The plates are overlaid, clamped externally with a belt or airbag, and consolidated by curing the adhesive to obtain a cylindrical composite.
[0008]
If this columnar composite is left in the air as it is, the moisture contained in the internal log will be removed from the ring-shaped part (hereinafter abbreviated as a single-plate laminated ring) consisting of a stack of single-plate equal band-shaped members wound around it. To expand the veneer laminate ring. On the other hand, when the water content in the log portion of the core gradually decreases and becomes lower than the water content of the fiber saturation point (about 28%), the log portion starts to contract in volume. However, since the laminated veneer ring and the core log are firmly adhered to each other, their contraction and expansion are restrained by each other, and a radial force acts on the veneer laminated ring at the interface with the log and is drawn into the log side. , Thereby generating a compressive stress in the circumferential direction. Therefore, no cracking occurs on the decorative veneer on the surface.
[0009]
On the other hand, since the internal log is gradually dried while receiving a radial pulling force at the interface with the veneer laminated ring, two-dimensional tensile stress is gradually generated in the log as the water content decreases. . However, the internal stress that occurs during the slow drying process is remarkably easier to relieve than the saturated stress, generally known as stress relaxation in the unsteady state of moisture. No cracking occurs until the stress state. The limit depends on the material of the log and the presence of internal defects, but in the latter half of drying, the stress state in the log exceeds the limit, and fine cracks often occur. The log cracks thus generated are very fine and dispersive compared to the dry cracks generated by ordinary drying, and are small that do not affect the practical strength.
[0010]
In addition, since there is no drying crack on the exterior decorative surface, this cylindrical composite is a material that is extremely excellent in overall design, structural strength, bonding performance with other members, dimensional stability, etc. of the column. It can be used as a pillar of a building as it is. Further, when the veneer laminate ring is being treated with chemicals, it is possible to prevent damage from fire, rot fungi, pests and the like.
【The invention's effect】
[0011]
As described above, according to this method, when a log is dried, a single veneer such as a single plate that has been dried is wound around the log in advance and adhered, and then used directly as a pillar of a structure. It can be air-dried while being dried. Therefore, the advantage of this method of drying logs is that they do not require special energy for drying, they do not require a curing period before they can be used at construction sites, etc., and that there is almost no warping or irregularity due to drying. Further, the entire columnar composite itself is a precious wood building material having both excellent structural strength and designability.
[0012]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described.
[0013]
Embodiment 1
Using a pine veneer of 3.1 mm thickness dried to a moisture content of 7%, the fiber direction is cut to 150 mm, and a # 20 polyester is used to form an endless strip in a direction perpendicular to the fiber. Using a thread, four streaks were stitched at an interval of 30 mm, and then peeled off.
[0014]
Next, a cedar log with a length of 3.65 m is rounded into a cylindrical body having a diameter of 250 mm and air-dried in a room for about 15 days to obtain a state having a surface water content of about 20% and a center water content of about 100%. Was.
[0015]
While holding both ends of this cylindrical body with the chuck of the lathe and giving rotation,
A resorcinol resin adhesive is applied to the back surface of the single-plate band prepared in the above at a coating amount of 200 g / m ² and spirally wound from one end of the cedar column to the other end. After reaching, the sheet was folded and wound to form a state in which the fiber directions of the adjacent two-layer single-plate strips crossed each other about 10 ° to the left and right with respect to the cylindrical axis at a total angle of about 20 °. Thereafter, in the same manner, around the cylindrical body, ten layers of red pine veneer strips having interleaved fibers inclined about 10 ° to the left and right with respect to each other with respect to the main axis of the cylindrical body were wound up. Finally, after applying an adhesive to the surface of the cylindrical body, a single layer of a cedar decorative board having a thickness of 1.5 mm is overlaid, and a hydrostatic pressure of about 0.5 MPa is applied from outside using an airbag, and static pressure is applied at 30 ° C for 10 hours. The adhesive was cured by placing. After the adhesive was cured, the pressure was released to obtain a veneer veneered wood composite cylinder.
[0016]
The wood composite cylinder obtained in the above step was cut into a length of 1 m and dried in a thermostatic oven controlled at 105 ° C. for 7 days. As a result, it was confirmed that no crack was generated on the surface of the cylindrical body which was covered with veneer veneer. In addition, when an arbitrary cross section was cut and observed, a large number of fine cracks having a length of 20 mm or less in the radial direction were generated in the core log portion, and small cracks were also scattered in the tangential direction. Was. However, no abnormality such as cracks or deformation due to drying was observed in the laminated portion of the veneer. No bending in the major axis direction of the material after drying was observed at all, and the diameter was only shrunk by 2 to 2.5% as compared with that before drying, and the cross-sectional shape of the perfect circle was correctly maintained. In addition, both the water content in the central part and the water content in the peripheral part reached a completely dry state.
[0017]
further,
When a composite columnar body manufactured according to the same specifications as described above was constructed as a column of an actual building and put to practical use, there was no problem in the connection to other members.
[0018]
Embodiment 2
A red pine veneer strip similar to that in Example 1 was placed in a decompression tank, immersed in a fire retardant (a commercially available ammonium phosphate-based fire retardant), depressurized to 16 Torr, held for 30 minutes, returned to normal pressure, and left for about 60 minutes. By leaving still, a chemical solution of about 40 to 50% by dry weight ratio could be injected. Using this treated veneer, only a few layers from the surface were used to produce a laminate with the same specifications as in [1], and a fire test was conducted.
[0019]
As a result, it was found that if the single-layer strip from the surface layer was processed, the performance as a quasi-incombustible material was obtained without processing the inner layers. Therefore, if a composite cylinder is manufactured using the above-described fireproofing treatment on a single-plate strip used for at least four layers from the surface layer, a semi-combustible wood composite cylinder can be manufactured relatively easily. Do you get it.
[0020]
[Brief description of the drawings]
FIG. 1 shows a wood veneer strip and a fibrous sheet strip.
FIG. 2 shows the structure of a columnar composite.
FIG. 3 shows a cross section of a columnar composite.
[Explanation of symbols]
(1) Wood veneer (2) Fibrous material (3) Sewing machine (4) Round log (5) Nest plate sperm ring

Claims (3)

After a wooden veneer with a low water content or a fibrous material sheet is wound and adhered to the surface of a log with a high water content, the entire log composite is naturally dried or artificially dried to produce a log. A method of drying logs that reduces cracking and disperses finely. A log and columnar composite dried according to claim 1. A columnar composite obtained by subjecting the wood veneer or the fibrous material sheet according to claim 1 to chemical treatment to impart fire resistance, antiseptic property and insect repellency.

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