JP2007196507A - Butt end crack inhibition method of wood - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a butt end crack inhibition method of a wood by which the butt end crack can be prevented during drying and the strength and the appearance of the wood are not deteriorated and a method of producing dry woods by which the dry woods by which the butt end crack can be prevented during drying and which has good strength and appearance can be efficiently produced. <P>SOLUTION: The butt end crack inhibition method of the woods according to the present invention is has holes 12 in parts other than a material center part 13 in a butt end face 11 of the wood 1A. The method of producing the dry woods according to the present invention enables the wood 1A which has the holes 12 the parts other than the material center part 13 in the butt end face 11 to be dried at high temperature. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a method for preventing cracks in a timber and a method for producing dry timber.

In the drying of wood, cracks that occur in the mouth of the wood often become a problem. In particular, when a cored square member of a building structural material such as cedar, cypress, beech, or bay pine is dried at a high temperature, an internal crack as shown in FIG.
Such a crack in the neck causes a loss of a tenon when the tenon is formed by pre-cutting, and there is a concern about a problem such as a decrease in bonding strength due to a crack in the cross section.
It is considered that cracks at the end of the neck occur when the end of the wood is at both ends of the wood and the drying operation is faster than the other parts, so that the vicinity of the mouth is dry-shrinked and the tensile stress at this part increases.

Conventionally, as a method of preventing cracks at the end of the mouth, a method of applying a dry cracking preventive agent to the surface of the mouth and the vicinity thereof (see Patent Document 1) to prevent cracking of the surface near the mouth of the natural drying, or dry at both ends of the mouth. A method for mounting a crack cap (see Patent Document 2) has been proposed. However, these methods are intended to prevent or reduce cracking during natural drying, and exhibit an effect during natural drying.
In order to prevent surface cracks and lip cracks that occur during artificial drying using these conventional techniques, it is conceivable to increase the application amount of the anti-drying agent or slow down the drying speed. However, slowing the drying speed and extending the drying time increases the cost of drying and worsens the profitability of management. In addition, applying the anti-drying agent to hundreds or thousands of wood tips at once is a tremendous work, and increasing the amount of application is combined with an increase in drying time. This increases costs and is not realistic.
Further, in recent years, drying of building materials is required to further shorten the drying time and reduce the cost, and more efficient methods for preventing cracks at the end of the tree are required. Therefore, it is difficult to meet these requirements by applying these conventional techniques.

  Moreover, as a crack prevention during drying, a method for preventing a dry crack by providing a slit on the material surface has been proposed (see Patent Document 3). However, since slits such as cracks are formed in advance on the material surface, this does not lead to a method for preventing cracks, and there are restrictions in using the dried wood as a building construction material such as a pillar.

JP 2005-297208 A JP 2001-071306 A JP 2004-122595 A

Accordingly, it is an object of the present invention to provide a method for preventing cracks in wood that can prevent cracks during drying and that does not deteriorate the strength and appearance of the wood.
Another object of the present invention is to provide a dry wood production method that can prevent cracks in the mouth during drying and can efficiently produce dry wood with good strength and appearance.

The present invention achieves the above object by providing a method for preventing cracking of a wood mouth, characterized in that a hole is made in a portion of the wood mouth surface other than the central portion of the material.
This invention achieves the said objective by providing the manufacturing method of dry wood characterized by drying at high temperature the wood which pierced holes in parts other than the material center part in a mouth end surface.

According to the method for preventing cracks in the wood of the present invention, cracks in the mouth during drying can be prevented, and the strength and appearance of the wood are not deteriorated.
According to the method for producing dry wood of the present invention, it is possible to prevent cracking during drying, and it is possible to efficiently produce dry wood having good strength and appearance.

Hereinafter, the present invention will be described based on preferred embodiments thereof.
Examples of the wood used in the present invention (the method for preventing the crack at the end of the neck and the method for producing dry wood) include a square member having a square cross section (regular square member), a square member having a rectangular cross section (flat square member), and the like.
In the following, an embodiment of the method for producing dry wood according to the present invention will be mainly described. However, the steps up to the stage of making a hole are an embodiment of the method for preventing cracks at the end of the present invention.

  In one embodiment of the dry wood manufacturing method of the present invention, a cored square member (regular square member) 1A as shown in FIG. 1A is used as the wood to be dried. The cored square 1A is made from a log of a tree such as cedar, cypress, beech, bay pine, etc., and the dried timber (dried timber) is particularly preferably used as a building structural material such as a column or a beam.

  In this embodiment, first, as shown to Fig.1 (a), the hole 12 is made in parts other than the material center part 13 in the wood end surface 11 of the cored square material 1A which should be dried. The material center portion 13 means the center of gravity and its vicinity on the mouth end surface 11, and when the wood to be dried is square wood, the material center portion 13 is an intersection P between the diagonal lines of the mouth end surface 11 as shown in FIG. 2. And the vicinity thereof. In the case of a square member, the member central portion 13 is generally a region within a circle whose radius centering on the intersection P between the diagonal lines of the mouth end surface 11 is 1/5 of the length of the diagonal line.

  By drilling holes 12 in the portion other than the material center portion 13 on the end face 11, the tensile stress in the periphery of the wood that occurs during drying of the wood is reduced, thereby preventing (reducing) the cracking of the end of the wood during drying. Can also be included). Moreover, by making the hole 12 in a portion other than the material center portion 13, it is difficult to cause a trouble when performing a squeeze process on the end portion in the longitudinal direction of the dried wood.

In this embodiment, as shown in FIG.1 (c), the tenon 15 is formed as a joint in the edge part of the longitudinal direction of the timber 1 after drying. Thus, when forming the tenon 15 on the dried wood 1, the hole 12 is a portion corresponding to the tenon 15 in the wood 1 </ b> A before drying so that a missing portion or the like does not occur in the formed tenon 15 ( In FIG. 2, it is formed so as not to overlap with a rectangular portion 15A surrounded by a two-dot chain line.
From the viewpoint of preventing the missing portion or the like from being generated in the side wall 15 and effectively preventing the crack at the neck, the hole 12 has a radius centered at the intersection P between the diagonal lines of the mouth surface 11 of the length of the diagonal line. Preferably, it is formed outside the region in the 1/5 circle, and it is preferably formed outside the region M in the circle whose radius around the intersection P is 1/3 of the length of the diagonal line.

  The hole 12 in the present invention is different from the conventional spine that is formed so as to reach the material center 13 from the material surface 14 and the slits that are formed on the material surface of the wood in the technique of the above-mentioned Patent Document 3, so .. That do not open to any of the four material surfaces (referred to as surfaces orthogonal to the end surfaces) 14, 14,. Since the hole 12 does not open in the material surface 14, the dimensional stability is lowered as in the case where the back split is formed, or the design property when used as a column or beam as in the case where the back split or slit is formed is provided. There is no reduction. It is preferable that the shortest distance between the hole 12 and the closest material surface of the four material surfaces 14 of the wood 1 is 1.0 cm or more, and particularly preferably 2.5 cm or more. .

From the standpoint of preventing missing portions or the like from being formed in the side wall 15 and from the standpoint of effectively preventing cracks by forming the holes 12 in the portion where the cracks are likely to occur during drying, the wood to be dried is a square bar as in the present embodiment. In the case of 1A, it is preferable that the hole 12 formed in the end face 11 is formed between the material center portion 13 and each of the four corner portions.
In this embodiment, as shown in FIG. 1A and FIG. 2, four line segments (AB, B) connecting the midpoints of two adjacent sides on the wood end surface 11 of the cored square member 1A. The hole 12 is formed at the position of the midpoint (the point at which each line segment is divided into two equal parts) in each of (-C, CD, DA).
As in the present embodiment, the hole 12 may be formed in the vicinity of the outside or inside of each line segment instead of being formed directly above each of the four line segments. It is preferable that the hole 12 has the center of the hole 12 in a circle whose radius centering on the midpoint of each of the four line segments is 1/3 (particularly 1/5) of each line segment.

If the diameter of the hole 12 formed in the mouth end surface 11 is too large, drying of the end of the mouth may be accelerated and cracking may increase. May not be fully expressed.
From the viewpoint of preventing such inconvenience and obtaining a good cracking prevention effect, the diameter of the hole 12 is preferably 5 to 15 mm, more preferably 5 to 10 mm.

  It is preferable that the opening shape and the cross-sectional shape of the hole 12 are substantially circular because a good effect of preventing cracking at the end of the neck can be obtained and the processing for forming the hole is easy, but the ratio of the minor axis to the major axis is 1. : Up to about 3 oval or long hole shape may be used. In this case, the substantially circular shape includes an elliptical shape and a long hole shape in which the ratio of the minor axis to the major axis is about 1: 1 to 1: 1.2 in addition to the perfect circle. As for the diameter of the shape or the long hole shape, the average of the short diameter and the long diameter is the diameter of the hole. The elliptical or oblong hole preferably has a major axis of 15 mm or less, particularly 10 mm or less.

As shown in FIG. 4, the depth d of the hole 12 formed in the end face 11 reaches a position deeper than the front end face 15 a of the tenon 15. It is preferable that the depth does not reach 16. By setting the depth as described above, the tenon 15 having high strength can be formed on the dried wood 1, and since the hole 12 does not exist in the joint surface 16, there is no cross-sectional defect.
From such a viewpoint, the depth d of the hole 12 (see FIG. 3A) is preferably 5 to 15 cm, more preferably 5 to 10 cm, and still more preferably 4 to 9 cm.

In the dry wood manufacturing method of the present embodiment, as described above, the cored square member (wood) 1 having holes 12, 12,... After drying, in accordance with a conventional method, a cutting process (see FIG. 3 (b)) of a dry wood with a saw and the like, and a smoothing process on the four surfaces of the wood with a molder are performed. A tenon 15 as shown in FIG. 1C is formed at each of both ends in the longitudinal direction of the wood (core-supported square) 1.
In the present embodiment, since the holes 12 having the depth as shown in FIG. 3 are formed at the positions as shown in FIG. 1A and FIG. 2, both ends in the longitudinal direction of the wood after drying are respectively provided. When forming the tenon 15, as shown in FIG. 1 (c), the portion having the hole 12 at each end of the wood is cut out, and the trace of the hole 12 does not remain on the tenon 15 or the joint surface 16. .

In the above-described cutting process of the longitudinal end portion of the wood, as shown in FIGS. 3A and 3B, the distance L1 from the both mouth end surfaces 11 of the wood 1 is the depth of the hole 12. The wood after drying is cut at a position that is less than d.
The specific method of high temperature drying is not particularly limited as long as it has a drying step at a dry bulb temperature of 110 ° C. or higher, preferably 115 ° C. or higher, and various conventionally known high temperature drying methods can be used. Specific examples of the high-temperature drying include a method described in Japanese Patent No. 3361312.

  According to the dry wood manufacturing method of the present embodiment, a dry wood with little crack at the end can be obtained efficiently and economically by making holes in the end face 11 and drying at high temperature as described above. The obtained dry wood is less likely to cause defects (such as a decrease in strength) due to cracks at the edge when the edge 15 is formed at the end as shown in FIG. In addition, the dimension of the tenon 15 shown in FIG.1 (c) is 45-80% of the length L3 of the one side of the same direction of the wood before drying in the length L2 of the long side of the said front end surface 15a. Yes, the length L4 of the short side of the front end surface 15a is 20 to 30% of the length L5 of one side in the same direction of the wood before drying, and the protrusion height of the tenon 15 from the joint surface 16 H is 30 to 50 mm. As an example of preferable dimensions of the respective parts, L2 = 85 mm, L3 = 115 mm, L4 = 30 mm, L5 = 115 mm, L7 = 15 mm, and H = 45 mm.

As mentioned above, although one Embodiment of the manufacturing method of the dry wood of this invention was mainly demonstrated, in the embodiment mentioned above, it is this invention to the step which forms the holes 12, 12, ... in the cored square 1A before drying. 1 is an embodiment of a method for preventing cracks in wood.
In the above-described embodiment, a total of four holes 12 are formed in one end face 11 of the wood. However, as shown in FIG. 4, the portion corresponding to the tenon 15 (rectangular shape surrounded by a two-dot chain line) Part) One hole 12 may be formed on each side of 15A.
Moreover, although the hole 12 is preferably formed in each of the two end surfaces of the wood 1A to be dried, it can also be formed only in one end surface. Further, the wood to be dried may be a flat square material instead of the regular square material.

  Hereinafter, the present invention will be described in more detail based on examples. However, the present invention is not limited to the following examples.

(Test Example 1)
15 cored squares (cross-sectional dimensions 115 mm × 115 mm, length 300 mm) immediately after sawing from cedar logs were used as test materials.
About five test materials (Example 1), the hole of 9 mm in diameter was drilled with the drill in each of the front end and the open end of both ends. As shown in FIG. 2, the hole formation position was set at the midpoint of the line segment connecting the midpoints of two adjacent sides, and the hole depth d was 9 cm. For the remaining 10 specimens (Comparative Example 1), no holes were made in any of the end surfaces.

About 15 said test materials, high temperature drying was performed on the schedule shown in FIG. In the schedule shown in FIG. 5, the conditions of the dry bulb temperature of 105 ° C. and the wet bulb temperature of 78 ° C. are made comparatively long so that cracks are likely to occur at the end of the wood, and the dried wood is slightly overdried. .
The degree of cracking in the wood after drying was evaluated as follows.
That is, each test material after drying was cut at a position of 9 cm from both ends of the both ends, and it was visually observed whether or not the cut surface was cracked. If there is a crack in the cut surface, 5 points are given when there is a medium crack with a maximum width of less than 2 mm and a length of less than 50 mm, and a large crack with a maximum width of 2 mm or more or a length of 50 mm or more. When there was, 10 points were awarded.
As shown in Table 1, for each of the example and the comparative example, the number of points given to each test material was totaled separately at the source and the end, and the total number of points was used. The defect rate was calculated by dividing the test material by 10 points. The results are shown in Table 1.

(Test Example 2)
Twenty core squares (cross-sectional dimensions 130 mm × 130 mm, length 300 mm) immediately after lumbering from cedar logs were used as test materials.
Among these test materials, about 5 (Example 2) and the other 5 (Example 3), a hole having a diameter of 9 mm was formed by drilling on both the front end and the front end of both ends. As shown in FIG. 2, the formation position of the hole is the midpoint position of the line segment connecting the midpoints of the two adjacent sides of the mouth end surface, as shown in FIG. Was 5 cm for Example 2 and 10 cm for Example 3. For the remaining 10 (Comparative Example 2), no hole was made in any of the end surfaces.

  About 20 said test materials, high temperature drying was performed with the schedule shown in FIG. The degree of cracking of the dried wood (dry wood) was evaluated in the same manner as in Test Example 1. The results are shown in Table 2.

  From the results of Test Examples 1 and 2, it can be seen that, according to the present invention, it is possible to prevent (reduce) the occurrence of cracks in the wood during drying by making holes other than the center part of the material of the mouth.

FIG. 1 (a) is a perspective view showing the wood with a hole in the end, FIG. 1 (b) is a perspective view showing the wood after the molder treatment, and FIG. 1 (c) It is a perspective view which shows the wood after drying which formed the tenon. FIG. 2 is a longitudinal end view of the wood showing the details of the hole formation position on the mouth end surface. FIG. 3A is a schematic diagram showing the wood with a hole in the end, and FIG. 3B is a schematic diagram showing the dried wood after cutting the end, and FIG. FIG. 3 is a schematic diagram showing the dried wood that forms a tenon. FIG. 4 is a diagram showing another embodiment of the present invention. FIG. 5 is a graph showing a drying schedule in Test Example 1. FIG. 6 is a graph showing a drying schedule in Test Example 2. FIG. 7 is a perspective view showing a piece of wood that has been cracked by drying.

Explanation of symbols

1A Wood (before drying)
1 Dried wood (wood after drying)
11 Kiguchi surface 12 Hole 13 Material center portion 14 Material surface 15 Relief 15a Relief tip surface 16 Joint surface

Claims (4)

  A method for preventing cracks in a timber, wherein a hole is made in a portion of the timber surface other than the center portion of the wood.   A method for producing dry wood, comprising drying wood at a high temperature at a portion other than the center of the wood on the end of the wood.   The method for producing dried wood according to claim 2, wherein a tenon is formed at an end portion in the longitudinal direction of the wood after high-temperature drying so that the portion having the hole is cut out. The method for producing dry wood according to claim 2 or 3, wherein the wood is square wood, and the holes are formed between a center portion and four corner portions of the wood end of the square wood.

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