JP2014117837A - Method for manufacturing dried lumber piece - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for manufacturing dried lumber pieces having no torsion or lower degree of torsion with high productivity and high yield.SOLUTION: The method for manufacturing dried lumber pieces includes the steps of: arranging a plurality of lumber pieces 1 to be dried in a direction Y crossing the longitudinal direction so as to form a lumber layer 2 to be dried; and stacking the lumber layers 2 to be dried such that the hot blast circulation spaces B and A are formed above and below each of the stacked layers for drying. The thickness Tb and Ta of the respective upper and lower hot blast circulation spaces for the lumber layers 2 to be dried are different, or alternatively the hot blast circulation spaces are formed only either above or below the lumber layers 2 to be dried. Preferably the thickness Tb and Ta of the respective upper and lower hot blast circulation spaces B and A for the lumber layers 2 to be dried are made different by arranging crosspieces 5 having a different thickness above and below the lumber layers 2 to be dried.

Description

  The present invention relates to a method for producing dry wood.

When raw wood made from raw wood is dried, the wood may be twisted due to deformation or shrinkage caused by drying.
In particular, tree species such as larch, todomatsu, and chestnut have a swivel structure in which stem cells are arranged spirally with respect to the axis of the tree, so that when the fiber contracts during the drying process, a large twist is generated especially near the core. Is generated, and a large twist is likely to occur in the dry wood.
When such twisting occurs, the dried wood is supplied as a product after correction grinding for the column material, and is supplied as a product after being cut to a short length for the plate material and then through a finger joint process. .
However, in the method of removing twist by post-processing after the drying step, the yield is greatly reduced, and the number of steps is increased, so that productivity is lowered.

  Various techniques have been proposed to reduce the deviations (twisting, bending, warping, etc.) that occur in dried wood by means of drying. For example, (1) a method using a heating plate (see Non-Patent Document 1), (2) a method using a drying correction jig (see Non-Patent Document 2, Patent Documents 1 and 2), (3) At the time of drying In addition, a method using a crosspiece provided with protrusions that are difficult to dry (see Non-Patent Document 3), a method of devising hot air blowing conditions (see Patent Document 3), and the like have been proposed.

  However, the method (1) requires a new investment in the equipment, and the productivity is reduced due to the hot platen. In the method (2), a new investment is required for the equipment, and a work process is often added. The method (3) is effective for bending and warping by suppressing horizontal bending, but is not so effective for twisting.

Atsushi Nakajima, Emiko Kajitani, “Examination of dimensional stabilization technology for flooring materials—absorption and desorption characteristics of hot plate drying material and hot air drying material”, Forestry Experiment Station Bulletin No. 464, March 1994 Yukio Oyama and 4 others, “Study on drying of larch thinned wood (2nd report) -Preventing board and horn misalignment-”, Forest Products Laboratory Report No. 248, September 1972 Japanese Patent No. 4331354 JP 2007-101046 A Motoyoshi Ikeda, “Development of a pier with an effect of reducing drying costs”, No. 51 (March 2007) JP 2004-324933 A

  Accordingly, an object of the present invention is to provide a dry wood production method capable of producing dry wood with no yield or high degree of twist with high yield.

  The present invention forms a to-be-dried wood layer by arranging a plurality of to-be-dried woods in a direction intersecting the longitudinal direction, and the to-be-dried wood layers are arranged so that a hot air circulation space is formed above and below them. A method for producing dry wood in which layers are stacked and dried, wherein the thickness of hot air flow space above and below the dry wood layer is different or the hot air flow space is provided only on one of the upper and lower sides of the dry wood layer The above-mentioned object is achieved by providing a method for producing dry wood, characterized in that the material is dried after being formed.

  According to the dry wood manufacturing method of the present invention, dry wood that is free of twisting or has a reduced degree of twisting can be manufactured with high yield and high productivity.

It is a perspective view which shows an example of the to-be-dried wood dried in one embodiment of this invention. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic cross-sectional view showing a wood drying apparatus that can be preferably used in the practice of the present invention and an embodiment using the same. It is a side view which shows the state which piled up to-be-dried wood. It is a graph which shows an example of a drying schedule. It is explanatory drawing of the measuring method of torsion arrow height.

Hereinafter, the present invention will be described based on preferred embodiments thereof.
In the dry wood manufacturing method of the present invention, hot air circulation spaces having different thicknesses are formed above and below the wood to be dried to dry the wood.
In a preferred embodiment of the method of the present invention, as shown in FIG. 1, a to-be-dried wood 1 having a rectangular cross section having a length L, a width W, and a thickness T, as shown in FIG. A plurality of the dried wood layers 2 are formed in a horizontal direction with the side surfaces facing each other, and the same dried wood layer 2 is formed in a plurality of steps in the vertical direction with the pier 5 interposed therebetween.
The to-be-dried wood 1 is preferably a material made from a tree species having a swivel wood. The to-be-dried wood 1 is, for example, a rectangular material or a plate material that is long in one direction X.
Examples of tree species having a swivel tree include larch, todomatsu, spruce, chestnut, itaya maple and the like. According to the present invention, it is possible to produce dry wood without twisting or with reduced degree of twisting with high yield and high productivity even from a tree species having such swivel wood, so that effective utilization of these materials can be achieved. Can be planned.

The to-be-dried wood layer 2 is formed by arranging a plurality of to-be-dried woods 1 in a direction Y orthogonal to the longitudinal direction X thereof. Hereinafter, the direction Y in which the wood to be dried 1 is arranged is also referred to as the width direction Y of the wood to be dried.
The plurality of to-be-dried timbers 1 arranged in the width direction Y of the to-be-dried wood 1 has no gap between adjacent to-be-dried woods 1 or small gaps, which is the amount of hot air flowing above and below the to-be-dried wood layer 2. It is preferable from the viewpoint of forming a difference. For example, the gap in the width direction Y of the wood to be dried at the start of drying is preferably 0 to 15% of the length L2 of the wood 1 to be dried in the same direction, more preferably 0 to 10%, and still more preferably. Is 0 to 5%, particularly preferably 0%.

As shown in FIGS. 2 and 3, the wood to be dried 1 is preferably stacked on a movable base 3 and then moved into the dryer 4 to be dried.
The gantry 3 includes a placement portion 31 for the wood to be dried 1 and a moving means 32 provided below the placement portion 31. As the moving means 32, various known structures can be adopted. As an example, as shown in FIG. 2, a moving means including a rail and a wheel rolling on the rail can be used.

In the present embodiment, since the mounting unit 31 has a planar upper surface as the gantry 3, a plurality of hot air channels are formed on the upper surface so as to form a hot air flow path between the upper surface. After the piers 5C are arranged, the to-be-dried wood 1 is arranged on the piers 5C to form the lowest to-be-dried wood layer 2D. Then, the pier 5A is placed on the bottom dried wood layer 2D, and the dried wood 1 is further arranged thereon to form the next dried wood layer 2. And the pier 5B is mounted on the to-be-dried wood layer 2, and also to-be-dried wood 1 is arranged on it, and the to-be-dried wood layer 2 of the next step is formed. Thereafter, in the same manner, a plurality of to-be-dried wood layers 2 are formed in a state of being separated in the vertical direction by the pier 5A or the pier 5B, and the weight 6 is placed on the to-be-dried wood layer 2U at the uppermost stage.
As shown in FIG. 3, the pier 5 (5 </ b> A to 5 </ b> C) is preferably arranged so as to be in contact with the upper and lower surfaces of both ends in the longitudinal direction of the wood 1 to be dried. Moreover, in addition to the said both ends of the to-be-dried wood 1, the crosspiece 5 (5A-5C) is arrange | positioned so that the upper and lower surfaces in one place or several places spaced apart from this both ends may be touched, as shown in FIG. It is preferable.
And it is preferable to add the load by the weight 6 to the both ends of the longitudinal direction of each to-be-dried timber 1 via the crosspiece 5. FIG. As for the load applied to the both ends of the longitudinal direction of the wood 1 to be dried, the load per one end is preferably 0.5 to 1.5 MPa, and more preferably 1.0 MPa or more.

In this embodiment, as shown in FIG. 2, two types of piers 5A and 5B having different thicknesses are used as the piers 5 arranged between the to-be-dried wood layers 2.
Specifically, as shown in FIG. 2, each of the dried wood layers 2 other than the uppermost and lowermost dried wood layers 2U and 2D is arranged on either one of the upper and lower sides. The thickness Ta of the pier 5A is different from the thickness Tb of the pier 5B disposed on the other side.
That is, in this embodiment, the thickness of the hot air circulation spaces A and B formed above and below the to-be-dried wood layer 2 is made different by making the thickness of the crosspieces 5 arranged above and below the to-be-dried wood layer 2 different. It is different. Referring to one dried wood layer 2A in FIG. 2, since there is a thick pier 5B above the dried wood layer 2A, on the upper side of the dried wood layer 2A, A hot air circulation space B having a thickness equal to the thickness Tb of the pier 5B is formed, and a thin pier 5A exists below the to-be-dried wood layer 2A. Therefore, below the to-be-dried wood layer 2A, A hot air circulation space A having a thickness equal to the thickness Ta of the pier 5A is formed.

  And in this state, if it accommodates in the dryer 4 and dries, it will dry the upper and lower surfaces of the to-be-dried wood 1 which comprises the to-be-dried wood layers 2 other than the uppermost and the lowermost to-be-dried wood layers 2U and 2D. The drying of the surface in contact with the thick hot air circulation space B on the thick pier 5B side proceeds relatively faster than the surface in contact with the thin hot air distribution space A on the thin pier 5A side. .

Further, in the uppermost dry wood layer 2U in the present embodiment, the thin pier 5A is in contact with the lower surface side to form a thin hot air circulation space, while the upper surface side has a thickness. A thick hot air circulation space is formed by the contact of the interval holding portions 6C of the weights 6 having a thickness equal to or greater than the thick pier 5B. Further, in the lowermost dried wood layer 2D in the present embodiment, the thin pier 5A is in contact with the upper surface side to form a thin hot air circulation space, while the lower surface side has a thickness of The thick pier 5B is in contact with the pier 5C having the same thickness as that of the thick pier 5B to form a thick hot air circulation space.
Accordingly, similarly to the dried wood layer 2 other than the uppermost and lowermost dried wood layers 2U and 2D, the dried wood 1 constituting the uppermost and lowermost dried wood layers 2U and 2D is also included. The drying of the upper and lower surfaces of the weight 6 or the surface of the gantry 3 side proceeds faster than the surface of the thin pier 5A side in contact with the thin hot air circulation space.

According to this embodiment, the drying speeds of the upper and lower surfaces during drying of all the wood to be dried 1 are thus different.
In the initial stage of drying, if the amount of shrinkage progresses differently on the upper and lower surfaces of the wood 1 to be dried, it is constrained to the slow-shrinking surface by the same effect as the high-temperature setting, so that the shrinkage does not increase even on the fast-shrinking surface. . Further, even in the middle of drying, when the dimensions are almost fixed on the fast-shrinking surface, the slow-shrinking surface does not progress due to the restraint of the fixed surface. Moreover, it progresses in a state with little shrinkage on both sides even in the late stage of drying.
According to the present embodiment, by such an action, the drying can be advanced while suppressing the shrinkage of the upper and lower surfaces, and even if there is a twisted dry wood or a twist, the degree is greatly suppressed. Dry wood is obtained.

Moreover, the method of this embodiment can be implemented by existing facilities that are widely used except for the use of piers having different thicknesses, and the drying time does not increase so much. The processing amount per unit also increases and the productivity is excellent.
In addition, dry wood without twisting, or dry wood with a degree of twisting that is greatly suppressed even if there is twisting is obtained. For example, if the degree of twisting is small, depending on the quality required for the product This eliminates the need for correction grinding and finger joint processes, increasing product acquisition yield and improving productivity.

From the viewpoint of more surely preventing the twisting effect, the hot air circulation spaces A and B formed above and below the to-be-dried wood layer 2 have a thickness Ta that is thinner than the thickness Tb that is thicker. The ratio (Ta / Tb) is preferably 0 to 0.8, more preferably 0.2 to 0.7, and still more preferably 0.25 to 0.55.
From the same point of view, the thickness Tb of the hot air circulation space B having the larger thickness among the hot air circulation spaces A and B formed above and below the dry wood layer 2 is equal to the thickness T of the dry wood layer 2. Preferably it is 50 to 150%, more preferably 70 to 120%. In addition, the thickness Ta of the hot air circulation space A having a smaller thickness among the hot air circulation spaces A and B formed above and below the dried wood layer 2 is preferably 20 to 70 of the thickness T of the dried wood layer 2. %, More preferably 30 to 60%.
Moreover, hot air is introduced into the hot air circulation spaces A and B from one side in the width direction Y of the wood to be dried, and after passing through the hot air circulation spaces A and B, from the other side in the width direction Y. It is preferable to perform drying while controlling the flow of hot air so that the hot air is derived. In FIG. 2, H indicates hot air.
The preferable thickness and thickness ratio of the hot air circulation spaces A and B are the same as the preferable thickness and thickness ratio of the piers 5A and 5B.

  In the dry wood manufacturing method of the present invention, as shown in FIG. 2, a heating chamber 41 that can accommodate a plurality of dry wood to be dried in a stacked state, and heating that can heat the air in the heating chamber. The dryer 4 provided with the hot air circulation means 43 which distribute | circulates the heated air in the means 42 and the heating chamber 41 so that the hot air H may flow between the to-be-dried wood layers 2 is used preferably.

The heating chamber 41 is preferably one that can store the timber to be dried in a stacked state together with the gantry. As the heating means 42, an electric heater, a heating tube through which a heat medium such as steam circulates, or the like can be used. As the hot air circulating means 43, an electric fan or the like can be used. Moreover, the dryer 4 may be provided with a temperature lowering unit that lowers the temperature in the heating chamber. As the temperature lowering means, for example, a fan that introduces outside air into the heating chamber or a heat exchanger that releases the heat in the heating chamber to the outside can be provided. The dryer 4 is preferably one that can be heated under atmospheric pressure.
In addition, as the pier, a wooden thing, for example, made of a material such as cedar and larch is preferable, but various known ones conventionally used as a pier can be used, instead of a wooden one, steel, A hollow or solid rod-shaped body made of metal such as aluminum can also be used.

The drying schedule in the present invention can be set as appropriate.
FIG. 4 shows an example of a preferable drying schedule.
In the drying schedule shown in FIG. 4, for the purpose of improving the subsequent drying rate, steam is directly injected into the drying chamber, and the dry bulb temperature and wet bulb temperature are set to 90 ° C. or higher at a stretch and maintained for about 6 hours. After performing the vaporization process, both the dry bulb temperature and the wet bulb temperature are lowered to 55 ° C. or lower, and intermediate temperature drying is performed in which drying is performed within a range of 55 to 80 ° C. while gradually increasing the temperature. Drying is completed, for example, when the moisture content falls below 12%.

As mentioned above, although the preferable embodiment of this invention was described, this invention is not restrict | limited to the embodiment mentioned above, It can change suitably.
For example, the hot air circulation space may be formed between the to-be-dried wood layers by a method other than the method of interposing the pier.
Further, as in the above-described embodiment, instead of providing a portion where the wood layer to be dried is stacked via the pier 5A and a portion where the wood layer to be dried is stacked via the pier 5B, the wood layer to be dried is provided. You may provide alternately the site | part which directly overlaps without passing a crosspiece, and the site | part which piles up a to-be-dried wood layer through a crosspiece in the perpendicular direction. In this case, when paying attention to one dried wood layer, drying is performed by forming a hot air circulation space only in one of the upper and lower sides of the dried wood layer. The traveling speed is different, and there is an effect of suppressing twist.

In addition, instead of changing the thickness of the upper and lower hot air circulation spaces for all the dried wood layers of the stacked dried wood layers, only the thickness of the upper and lower hot air circulation spaces for some dried wood layers May be different. However, it is preferable to vary the thickness of the upper and lower hot air circulation spaces for the three or more dried wood layers, including the case where the thickness of the upper and lower hot air circulation spaces is different for all the dried wood layers, It is more preferable to make the thickness of the upper and lower hot air circulation spaces different for the four or more dried wood layers, and it is still more preferable to make the thickness of the upper and lower hot air circulation spaces different for the five or more dried wood layers.
Further, the to-be-dried wood may be a square member instead of the flat member.

EXAMPLES Next, although this invention is demonstrated concretely based on an Example, this invention is not limited at all by the following Examples.
[Example 1]
A dry wood layer was formed by horizontally arranging seven pieces of plate material (average raw material moisture content 76%) made of todomatsu having a thickness of 32 mm, a width of 115 mm, and a length of 3000 mm on a frame on which a 25 mm-thick pier is arranged. . A 10 mm-thick pier was placed thereon, and seven plate members were arranged thereon to form a dry wood layer for the next stage. Thereafter, in the same manner, seven stages of dried wood layers were formed in the vertical direction (total 49 pieces). As the pier, a pier with a thickness of 25 mm and a pier with a thickness of 10 mm were alternately used between the dry wood layers stacked in the vertical direction. Further, a 10 mm-thick pier was placed thereon to form the uppermost dry wood layer. Further, a weight was placed thereon, and a load was applied to the portion shown in FIG.

In this way, the piled Todomatsu plates (wood to be dried) were accommodated in the dryer having the configuration shown in FIG. 2 and dried according to the drying schedule shown in FIG. Drying was performed by carrying out a vaporization treatment at a dry bulb temperature of 95 ° C. and a wet bulb temperature of 93 ° C. for 6 hours, followed by intermediate temperature drying in the range of 55-80 ° C. for 90 hours. After confirming that the moisture content meter inserted in the material was 12% or less, drying was completed. The finished moisture content was 11.0%.
The twisted arrow heights of the dried timber (dried timber, 49 pieces) included in the dried timber layers from the bottom to the seventh tier were measured, and the results are shown in Table 1.
In Table 1, the plate materials are classified into the following three types, and the results for each classification are shown.
Double-core plate: A plate that has a wood core on both ends.
Single-core plate: A plate with a tree core on one side.
Core removal board: A board that does not have a wood core on both ends.
In addition, the pass rate in Table 1 is a ratio of a pass product when the twist arrow height is 4 mm or less.

<Measuring method of twisted arrow height>
As shown in FIG. 5, in a state where the two corners P1, P2 of one end in the longitudinal direction of the dry wood are pressed against the horizontal plane 7, one corner P3 of the other end is brought into contact with the same horizontal plane 7, In the state, the distance from the horizontal plane 7 to the end 71 of the remaining corner is defined as a twist arrow height t1.

[Comparative Example 1]
Implemented except that a board made of todomatsu with a thickness of 32 mm, a width of 115 mm, and a length of 3000 mm (average raw material moisture content 72%) was used, and the berths arranged above and below the dried wood layer were all 25 mm thick. In the same manner as in Example 1, seven stages of dried wood layers were formed in the vertical direction (total 49 pieces), and the uppermost stage dried wood layer was formed. In addition, a weight was put on the same portion as in Example 1 and a load was applied.

In this way, the stacked Todomatsu plates (wood to be dried) were accommodated in the dryer having the configuration shown in FIG. 2 and dried according to the drying schedule shown in FIG. Drying was performed by performing a steaming process at a dry bulb temperature of 95 ° C. and a wet bulb temperature of 93 ° C. for 6 hours, followed by intermediate temperature drying in the range of 55 to 80 ° C. for 90 hours. After confirming that the moisture content meter inserted in the material was 12% or less, drying was completed. The finished moisture content was 11.4%.
The twist arrow height of the dried wood (dried wood, 49 pieces) contained in the dried wood layer from the bottom to the seventh to the bottom was measured, and the results are shown in Table 1 in the same manner as in Example 1. .

  From the results shown in Table 1, it can be seen that according to the method of the example, it is possible to effectively prevent twisting of the dry wood as compared with the method of the comparative example.

DESCRIPTION OF SYMBOLS 1 Wood to be dried 2 Wood layer to be dried 3 Base 31 Placement part 32 Moving means 4 Dryer 41 Heating chamber 42 Heating means 43 Hot air circulation means 5, 5A-5C Jetty 6 Weight 6C Spacing part H Hot air

Claims (4)

A state in which a plurality of to-be-dried timbers are arranged in a direction intersecting the longitudinal direction to form a to-be-dried wood layer, and the to-be-dried wood layers are stacked so that a hot air circulation space is formed above and below A method for producing dry wood for drying,
A method for producing dry wood, characterized in that the thickness of hot air circulation space above and below the dried wood layer is made different, or drying is performed by forming a hot air circulation space only on one of the upper and lower sides of the dried wood layer. .   The method for producing dry wood according to claim 1, wherein the thickness of the upper and lower hot air circulation spaces is made different for three or more layers to be dried.   The dry wood production according to claim 1 or 2, wherein the thickness of the hot air circulation space formed above and below the to-be-dried wood layer is made different by changing the thickness of the piers arranged above and below the to-be-dried wood layer. Method.   The dry wood production method according to any one of claims 1 to 3, wherein the dry wood is a material obtained from a tree species having a swivel wood.

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