JP2828625B2 - Wood drying method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a drying method for drying raw materials, and more particularly to a method for drying wood such as building materials which require dimensional accuracy and yield.

[0002]

2. Description of the Related Art Wood used in construction and the like is used after drying raw material wood. Conventionally, as a method for drying raw material wood, generally, a person introduced into a drying room is used. A method has been adopted in which raw wood is forcibly steamed with steam, and then the temperature in the drying chamber is lowered to dehumidify the wood.

[0003] As a method for drying wood and the like, a method of drying wood by heating it with a heater has been widely used. In addition, the applicant of the present invention 4-33775
According to the publication, as a device for drying organisms such as steamed sweet potatoes, wood, cereals, fish and the like using a far-infrared heater, in addition to a heater for heating air circulating in a drying chamber, a material to be dried is provided. A biological drying apparatus provided with a far-infrared heater for irradiating far-infrared rays to a living organism is already known.

[0004]

However, in the above-mentioned conventional method for drying wood, since the drying step is performed after steaming once, it takes a long time to dry the wood, and therefore, the efficiency is extremely low. It was bad.

According to another method of drying wood by heating it with a heater, in this case, the drying temperature between the inside and the surface of the wood is greatly different. The size and shape of the cut wood will change. Also, due to the destruction of the wood cells and components, for example, as shown in the attached FIG. 5, only the central portion of the cross section of the wood W such as square wood contracts and becomes thin, cracked, twisted, or bent or warped in the straight portion. Therefore, there was a problem that the yield of wood was deteriorated.

Further, according to the biological drying apparatus disclosed in Japanese Utility Model Publication No. 4-33757, the biological drying apparatus is heated by a heater and dried by air circulating in a drying chamber. The degree of distortion such as cracking or bending generated in wood is small. However,
In particular, it cannot be said to be suitable for drying wood such as building materials that require dimensional accuracy.

In view of the above problems in the prior art, an object of the present invention is to reduce the degree of distortion generated in wood during drying, and to dry wood that requires dimensional accuracy such as building materials. It is an object of the present invention to provide a method for drying wood suitable for use.

[0008]

In order to achieve the above object, according to the present invention, wood in a drying room is irradiated with far infrared rays,
When drying, the moisture in the wood is evaporated into the drying chamber, and the drying chamber is not ventilated from the beginning, and the moisture evaporated from the wood is filled in the drying chamber, and the drying chamber is brought into a high humidity state. I decided to ventilate. That is, the wood drying method according to the present invention stores the wood in the drying chamber, irradiates the wood in the drying chamber with far-infrared rays while keeping the drying chamber almost non-ventilated, and evaporates the moisture of the wood into the drying chamber, It has a first step of filling the drying chamber with the moisture evaporated from the wood, and a second step of subsequently ventilating the drying chamber.

In the wood drying method of the present invention, in the first step, the wood is heated from the inside by irradiating the wood with far-infrared rays, so that the water contained in the wood evaporates relatively quickly. Not only surface water and free water, but also water that is relatively hard to evaporate and that is bound inside the wood tissue can evaporate at the same time. And in the first step of irradiating the wood with far infrared rays, while evaporating moisture from the wood,
Since the steam is used to keep the drying chamber under high humidity, there is no large difference in the evaporation rates of the surface water, free water and combined water of the wood. In other words, by the irradiation of far infrared rays, the wood is heated from the inside, and not only the surface water and free water of the wood, but also the combined water is simultaneously evaporated, and under the high humidity in the drying room, the surface water of the wood, Rapid evaporation of only free water is suppressed. For this reason, there is no extreme difference in the evaporation rate of the wood as a whole. As a result, there is no distortion of wood or precipitation of tar and the like, and there is little destruction of cells of the wood, deterioration of the wood is minimized, and drying can be performed in a short time. You.

[0010]

Embodiments of the present invention will be described below in detail with reference to the accompanying drawings. FIG. 2 shows an external configuration of a wood drying apparatus which is an apparatus for performing the wood drying method of the present invention. In this figure, a wood drying apparatus 1 is composed of a housing 2 for forming a space to be a drying chamber partitioned from the outside world. Specifically, the housing 2 is built in a box shape as illustrated in, for example, a prefabricated structure. The shape of the housing 2 is not limited to the above-described box shape, and may be, for example, a house shape or a hut shape having a roof at an upper portion, and the building material is also limited to a prefabricated one. Needless to say, it is not a thing. Further, even if this housing 2 is arranged in a building, it can be arranged outside as it is.

As is apparent from FIG. 2, a so-called shutter 3 is mounted on the front of the housing 2. When the shutters 3 and 3 are opened,
Raw wood, which is an object to be dried, is carried into the drying chamber inside the housing 2, and thereafter, the shutters 3, 3 are closed to make the inside of the housing 2 a drying chamber that is shielded from the outside (outside air). Further, a rail 5 extending from the outside into a drying chamber in the housing 2 is provided on a concrete base 4 on which the housing 2 is erected, at a position where the shutter 3 is disposed in front of the housing 2. . That is, a carriage (not shown) is movably mounted on the rails 5, 5,..., And is used to carry wood to be dried into the housing 2 or to carry wood after drying.
In the apparatus according to the illustrated embodiment, a plurality of shutters 3 are provided, but a single shutter may be used. Also,
The arrangement of the shutters may be multiplexed in consideration of blocking from the outside of the drying chamber (outside air) inside the housing 2 or may be single.

Further, as is apparent from the sectional view of FIG. 3, a plurality of far-infrared heaters are provided inside the housing 2 in the apparatus according to this embodiment, for example, on the inner wall around the housing 2. Along the periphery, 24 panel-shaped far-infrared heaters 6, 6,... Are arranged. Also,
As shown in FIGS. 4 (a) and 4 (b), air supply fans 7, 7 are provided on a part of the wall surface constituting the housing 2, for example, at a plurality of locations on both upper sides of the front wall surface. However, the exhaust fans 8, 8,...
Further, inside the wall constituting the ceiling of the housing 2, a plurality of circulation fans 9 are arranged in a line in the longitudinal direction of the ceiling surface. In the configuration of the above-described embodiment, both the air supply fan 7 and the exhaust fan 8 are provided, but only one of the air supply fan 7 and the exhaust fan 8 is provided instead. It is also possible to use

Next, the wood drying method of the present invention executed by the wood drying apparatus having the above-described structure will be described in detail. First, according to the wood drying method of the present invention, FIG.
, First, the wood W to be dried is mounted on, for example, the carriage on the rails 5, 5,..., The shutters 3, 3 are opened, and the wood W is moved into the drying chamber in the housing 2. 3 is closed, and the wood is stored in a drying room shielded from the outside (step 11). Next, power is supplied to the far-infrared heaters 10, 10,... To irradiate far-infrared rays to the wood W stored in the drying chamber (step 12:
Evaporation step). At this time, the air supply fan 7 and the exhaust fan 8 (or ventilation fan) are stopped or operated with a reduced amount of exhaust so that the drying chamber in the housing 2 is substantially non-ventilated or slightly ventilated. Keep in ventilation. Thereby, the wood W in the drying chamber is supplied to the far-infrared heaters 10, 10
Are heated by the far infrared rays emitted from the... Evaporate the moisture contained in the wood, discharge the steam into the drying chamber, and fill the drying chamber with the moisture evaporated from the wood. That is, the moisture of the wood is evaporated into the drying chamber, and the moisture evaporated from the wood is filled in the drying chamber. Therefore, the inside of the drying chamber is in a high humidity environment with a substantially saturated vapor pressure.

That is, according to the above-described process, the wood is heated while irradiating far-infrared rays to the wood to evaporate moisture from the wood.
The wood penetrates to the inside, and the wood is heated from the inside. Therefore, of the water contained in the wood, not only the surface water and free water that evaporate relatively quickly, but also the bound water inside the wood tissue that is relatively hard to evaporate can be simultaneously evaporated. Also, since the inside of the drying chamber is in a closed state, the humidity in the drying chamber is increased by the steam from the interior of the timber, so that only surface water and free water that evaporate relatively quickly evaporate rapidly. It is suppressed and evaporates gradually with the bound water inside the wood tissue. Therefore, the rate of evaporation of water from the interior of the wood does not produce an extreme difference between surface water, free water and combined water,
In other words, a uniform water evaporation rate without unevenness can be obtained. In other words, due to the uniform evaporation rate of water from the entire wood, cracks and bends in the above-mentioned wood, etc. It is possible to suppress the occurrence of distortion of wood due to drying, including the phenomenon of forming a concave portion, that is, “tarnish, knot”. In addition, since only irradiation with far infrared rays is sufficient, drying can be performed in a relatively short time.

After that, the air supply fan 7 and the exhaust fan 8 (or ventilation fan) are started to ventilate the air in the drying chamber (step 13: dehumidification step), and at the same time, to the far-infrared heaters 10, 10,. To control the amount of far-infrared radiation on the wood by controlling the power supply of the wood. That is, the drying of the wood is completed by ventilating the humid air in the drying chamber containing the water discharged from the wood by the irradiation of the far infrared rays with the outside air. Further, the dried wood is carried out of the drying chamber (step 14). At this time, the shutters 3 and 3 are opened and the carriages on the rails 5, 5. The dried wood is loaded from the drying room into the housing 2
It will move outside.

[0016] Incidentally, in the step 13 dried in the ventilation process of room air, far-infrared heaters 10, 10 ... to
Continue irradiating far-infrared rays to wood without stopping power supply
You. Thus, by also continuing irradiation of far-infrared to the timber in a ventilated drying steps room air, two steps proceeds simultaneously, there is an effect that it is possible to accelerate the drying rate of the wood as a whole .

Further, in particular, when the far-infrared ray is irradiated on the wood in step 11 described above, for example, the drying chamber is set to 50 ° C., and when the temperature in the drying chamber exceeds the set temperature, there are the above three cases. Exhaust fans 8, 8, ...,
Alternatively, a part thereof (for example, only the central exhaust fan 8) may be operated so that a small amount of air is supplied to and exhausted from the drying chamber, and the temperature in the drying chamber is maintained at a predetermined temperature. It is possible. As described above, by suppressing the temperature rise in the drying chamber at the time of irradiation with far infrared rays to a predetermined set temperature, it becomes possible to obtain more uniform drying of wood regardless of changes in drying conditions.

[0018]

Next, the results obtained by actually drying wood using the above-described apparatus according to the wood drying method of the present invention will be described for each type (wood species, shape) of wood.

First, the size of “Yonematsu” is 369
Sixty (W) x 279 (D) x 48 (L) (mm) plate-like 70 wood (board materials) are arranged in a drying chamber in 5 rows x 15 stages and dried by the method of the present invention. Was. The results are shown in Table 1 below.

[Table 1] As is clear from Table 1, as for the above-mentioned rice pine plate material, the evaporating step was performed for 24 hours, and then the dehumidifying step was performed for 11 hours. It could be dried to 12%.
As a result, no distortion (crack, bend, tar, knot) occurred in the shape of the wood.

Next, "cedar (* 1)" has dimensions,
3030 (W) x 107 (D) x 107 (L) (mm)
These two types of square lumber were used as samples, and these samples, "cedar (* 1) 1" and "cedar (* 1) 2," were also dried in the drying chamber by the method of the present invention, and The results are shown in Table 2 below.

[Table 2] Here, once the evaporation step was performed for 14 hours, the weight, the water content, and the distortion were measured once, and then the dehumidification step was performed for 11 hours (a total of 35 hours). As a result, the water content of 30% or more before drying is reduced to 18% (Japanese cedar (* 1) 1) and 19% (Japanese cedar (* 1) 1) by the evaporation process, and further reduced by 13% by the subsequent dehumidification process. % (Cedar (* 1)
1) It was possible to dry to 14% (cedar (* 1) 1). At that time, the shape of the wood is distorted (cracked, bent, and
Jani, verse) did not occur.

For "Yoshino cedar", dimensions, 3
007 (W) × 107 (D) × 107 (L) (mm) were used as samples, and “Yoshino cedar 1” and “Yoshino cedar 2” were also used in the above-mentioned drying chamber in the drying room. Drying was performed by the method, and the results are shown in Table 3 below.

[Table 3] Here, the evaporation step was performed once for 14 hours, and the weight, the water content, and the distortion were measured. Thereafter, the above evaporation step was again performed until 20 hours in total (6 hours), and measurement was performed again. Thereafter, an additional 18 hours of dehumidification was performed (38 hours in total), and the weight, water content, and strain were measured again. As a result, as shown in the table, the water content of the wood before drying was sufficiently reduced (“Yoshino Sugi 1”: 41.5% → 14.23% → 14.14% → 1
3.71%, "Yoshino cedar 2": 58% → 51% → 39.5
% → 19.5%), and no wood shape distortion (crack, bend, tar, knot) was observed.

Further, in another kind of "NZ (New Zealand) pine", the size is 4050 (W) .times.213.
(D) x 15 (L) (mm) and 3630 (W) x 102
(D) x 15 (L) (mm) and two samples ("NZ pine 1" and "NZ pine 2")
Was also dried by the method of the present invention in the same manner as described above, and the water content thereof could be sufficiently reduced. At this time, distortion of the wood shape (crack, bend, tar, knot, ) Was not seen.

In the case of "Akamatsu", all dimensions are 3900.
(W) × 123 (D) × 44 (L) (mm) were used as samples, and dried by the method of the present invention in the same manner as above to sufficiently reduce the water content. At that time, no distortion (crack, bend, tar, knot) of the wood shape was observed.

As is clear from the tables in the above embodiment,
According to the wood drying method of the present invention, it has been experimentally found that a sufficient degree of drying can be obtained in drying various types of wood, and that almost no distortion including cracking and bending that may occur during drying occurs. .

[0025]

As is clear from the above detailed description, according to the wood drying method of the present invention, a sufficient degree of drying can be obtained in the drying of raw wood, and at the same time, the wood can be produced during drying. It is possible to reduce the occurrence of distortions such as cracks and bends, which makes it possible to provide a wood drying method suitable for drying wood requiring dimensional accuracy such as building materials. Demonstrates excellent effects.

[Brief description of the drawings]

FIG. 1 is a flowchart for explaining the steps of a wood drying method of the present invention.

FIG. 2 is a perspective view showing the overall appearance of a wood drying apparatus for carrying out the wood drying method of the present invention.

FIG. 3 is a view showing a cross section taken along line AA of the wood drying apparatus of FIG. 3;

FIG. 4 is a diagram showing the front and back surfaces of the wood drying apparatus.

FIG. 5 is a cross-sectional view illustrating a state of wood after drying, which explains a problem in the related art.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Wood drying apparatus 2 Housing 3 Shutter 4 Concrete base 5 Rail 6 Far infrared heater 7 Air supply fan 8 Exhaust fan 9 Circulation fan Step 12 Evaporation process Step 13 Dehumidification process W Wood

[Table 4]

[Table 5]

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁶ , DB name) B27K 5/00 F26B 9/06

Claims (2)

(57) [Claims] 1. A method for drying wood, wherein the wood is stored in a drying chamber, and the drying chamber is made substantially non-ventilated.
Irradiating far-infrared rays in the drying chamber of wood, the moisture of the wood evaporates drying chamber, a first step of meeting the moisture evaporated from the wood to the drying chamber, far thereafter the drying chamber of a timber
The second step of ventilating the drying room while irradiating infrared rays
And a wood drying method. 2. The method according to claim 1, wherein in the first step of setting the drying chamber in a substantially non-ventilated state, when the temperature of the drying chamber becomes equal to or higher than a preset temperature, a temperature rise in the drying chamber is suppressed. The method for drying wood according to claim 1, wherein air supply and exhaust are performed.