JPS63123977A - Method of drying wood - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

Detailed Description of the Invention (Industrial Application Field) The present invention relates to a method for drying wood, and more specifically, for drying a long cored wood suitable for use as a decorative pillar such as a floor pillar or a decorative pillar. It's about how to do it.

(Prior art) Decorative pillars such as toko pillars and decorative pillars used in tokonoma in Japanese-style buildings are used so that the outer shape and pattern of the wood are preserved as they are. So-called core mochi wood, which is used as is, is generally used.

The wood with a core is subjected to a drying process in advance, and this drying method includes a natural drying method and an artificial drying method.

Although the natural drying method is the most ideal drying method, it has the drawbacks of being easily influenced by the weather and requiring an extremely long drying time, so that the artificial drying method is currently the mainstream.

As the artificial drying method, a hot air drying method is generally used. In this method, wood is placed in a drying chamber, and dried heated air is forcibly supplied into the drying chamber to sequentially dry the wood from the surface toward the inside.

(Problems to be Solved by the Invention) However, such a drying method has the following problems.

(1) When wood is dried from the surface to the inside, the moisture contained in the wood is removed sequentially from the surface to the inside.

In other words, the moisture inside the wood gradually moves toward the surface, but this takes a considerable amount of time to dry the inside of the wood, that is, the core material, to a predetermined moisture content.

(2) There is a large moisture gradient from the surface to the interior of the wood (see the broken line in Figure 5), which tends to cause distortion.

(3) In addition to the moisture gradient characteristics mentioned above, in the case of wood with a core, the so-called same material on the outer periphery has a large shrinkage rate due to drying, while the so-called core material on the axis has a low shrinkage rate due to drying. Due to differences in shrinkage rates, cracks are likely to occur on the wood surface. As a result, about 30% of the products are defective, and the product yield is extremely low.

(4) Due to the long drying time and poor yield,
This results in an increase in product costs.

(5) In the case of artificial drying at high temperatures, the surface of the wood will discolor and cracks may occur on the wood. If the drying conditions are moderate, blue mold will form on the surface of the wood, reducing its commercial value. In order to correct this problem, the surface of the wood has traditionally been bleached using acidic chemicals, but this has caused a significant loss of the original strength and flavor of the wood.

(Means for Solving the Problems) The present invention has been made in view of the above conventional problems, and the method for drying wood of the present invention is to arrange the gas flow grooves approximately centrally on the circumferential surface of the cored wood. Provided over the entire length until reaching
The drying gas is forcibly supplied to the gas flow groove.

It is preferable that a back groove is used as the gas flow groove, and the depth is greater than the center.

To forcefully supply drying gas to the gas distribution groove, use methods such as spraying the drying gas into the gas distribution groove with a nozzle, or aligning the gas distribution groove with the hole from which the drying gas blows out. .

For example, by tilting the core holding wood and making the gas distribution groove face downward, supplying drying gas to the lower end of the gas distribution groove,
Allow it to flow to the top.

Dry heated air is preferably used as the drying gas.

(Function) By forcibly supplying drying gas to the gas circulation grooves provided on the circumferential surface of the core-holding wood, the drying gas is sequentially applied from the core material with a small shrinkage rate due to drying to the core material with a high shrinkage rate due to drying. dried.

(Example) Embodiments of the present invention will be described below with reference to the drawings.

An artificial drying device used in the wood drying method according to the present invention is shown in FIG. The main parts include a feeder 2.2, an air dryer 3, and a blower 4. Moreover, the wood 5 to be dried by this drying device is preliminarily provided with gas circulation grooves 6 along its entire length in a part of its outer periphery.

The drying chamber 1 is a closed type having a rectangular parallelepiped shape, and the dry air supply device 2.2 is installed at the bottom of the drying chamber 1.
is installed, and an exhaust duct 7.7 is installed in the ceiling.
... is provided.

The dry air supply device 2 is for supplying dry and heated air to the wood 5. The nozzle 2a... is provided. By tilting the wood 5 so that the gas flow grooves 6 face downward, the wood 5
The dry heated air blown to the lower end of the wood 5 flows to the upper end, and the wood 5 can be dried uniformly over its entire length. Four of the injection nozzles 2a are arranged at regular intervals in a straight line in the vertical direction at positions corresponding to the lower end portions of the gas flow grooves 6 of each piece of wood 5.

The exhaust ducts 7.7 are arranged corresponding to the upper end portions of the timbers 5, respectively, and these exhaust ducts 7.7 communicate with the air dryer 3 via piping 8. has been done.

The air dryer 3 consists of a dryer that cools and dries the air from the exhaust duct 7.7, and a heat source such as an electric heater that heats the dried air.
It is connected to the blower 4 via.

The blower 4 is for feeding the air that has been dried and heated by the air dryer 3 to the dry air supply device 2 via the piping 10.

Thus, a sealed dry air circulation circuit 11 is formed which continues from the air dryer 3 to the blower 4, the dry air supply device 2.2, the gas circulation groove 6 and the exhaust duct 7, and then returns to the air dryer 3. be done.

Next, the gas circulation grooves 6 formed in the wood 5 will be explained.

The gas circulation groove 6 is provided in a straight line along the entire length of the wood 5 at the outer circumference thereof. The cross-sectional shape of the gas circulation groove 6 is rectangular toward the axis O of the wood 5, as shown in FIG. The shape and dimensions of the gas flow groove 6 are set taking into consideration the material, thickness, purpose of use, etc. of the wood 5, but the depth is larger than the radius of the wood 5, that is, the axis 0 is It is set to exceed. That is, the depth of the gas circulation groove 6 is set to the radius of the wood 5, which is ten α. For example, in the wood 5 with a diameter of 120B, the above α
is set to about 51, that is, the depth is set to about 65 mm, and for wood 5 with a diameter of 200 to 300 mm, the above α is set to 10.
It is preferable that the depth is set to approximately 110 nm to 160 mm.

Next, a method of drying wood using the drying apparatus configured as described above will be explained.

■ Place the wood 5... in the drying chamber 1 as close as possible to the positions corresponding to the injection nozzles 2a... of each set of the dry air supply device 2.2 so that the dry heated air does not leak to the sides. After placing the dryer in a standing position, the drying device is operated.

(2) The dry heated air from the air dryer 3 is forced to circulate through the dry air circulation circuit 11 by the blower 4.

That is, the dry heated air is sent to the dry air supply device 2 and is injected from each injection nozzle 2a toward the wood 5 (the wind speed at this time is, for example, 14 to 15
m/sec. ). This injected dry heated air flows upward through the gas distribution groove 6 of each wood 5 from its lower end, as shown by the dashed line in FIG. 2, and is forcibly discharged into the exhaust duct 7. .

At this time, the dry heated air supplied into the gas circulation groove 6 is transferred to the inner wall of the gas circulation groove 6, as shown by the arrow in FIG.
A, 6b, and 6C are sprayed on the entire surface, and the moisture inside the wood 5 is taken away from these inner walls, and the moisture taken away is discharged to the exhaust duct 7. As a result, in the wood 5, the core material with a small drying shrinkage rate and the same material with a large shrinkage rate are drying in parallel. While a large movement distance is required for moisture, a small movement distance is required in the center, but according to the drying method of the present invention, efficient drying with good balance can be achieved.

In addition, since the gas distribution grooves 6 cut the annual ring layer of the wood 5 in the radial direction, the dry heated air easily and evenly removes the moisture in each annual ring layer, so that the wood 5 becomes a core material. It has a uniform moisture content from wood to wood, and prevents cracks from forming on the surface of the wood 5.

■ The air discharged from the exhaust duct 7 is sent to the air dryer 3, where it is dehumidified and heated, and then returned to the blower 4.
The dry air is forcibly sent to the dry air supply device 2.2, and this circulation is repeated thereafter.

Next, specific examples of the present invention will be described.

The wood 5 to be dried is cedar wood for floor pillars, and its specific specifications are shown below (see FIG. 3).

Itsutane 1, length of cedar wood 5: 300 cm 2, diameter of cedar wood 5: 120 Dragon 3, width W of gas circulation groove 6: 5 + u4, depth L of gas circulation groove 6: 65 dragon The flow groove 6 is also used as a so-called back line.

The length of the wood is 3QQcm, and the diameter of the end (upper part when standing) and base (foot when standing) is approximately 20cm.
Although there is a difference of about x*, the depth of the above-mentioned backing for both New Year's Day and Tsukuchi is formed by the radius of the wood + 51M.

The thus processed cedar wood 5 is placed in the drying chamber 1 of the drying device.
75 bottles were housed in a propped state, and dry heated air (humidity 50%, temperature 40°C) was supplied for 48 hours from the injection nozzles 2a, 2a, . . . of the dry air supply device 2.2 (drying throughput 150 today).

The cedar wood 5 obtained as described above has a moisture content of 50% and a total dry weight of 34 kg/n? There were no cracks on its outer surface, and it met all the requirements for use as a floor pillar. Furthermore, although the surface of cedar wood used as floor pillars is usually bleached with a bleaching agent, the cedar wood 5 dried by the method of the present invention can be used as a floor pillar as is without bleaching.

This is because moisture inside the cedar wood 5 collects in the gas flow grooves, that is, the backing 6, giving the surface of the cedar wood 5 a unique color, eliminating the need for bleaching.

Note that the present invention is not limited to the above-mentioned embodiments.

For example, in order to forcibly supply dry heated air into the gas distribution grooves 6 of the wood 5, the wood 5 is supported in a leaning state and air is fed into the lower end of the gas distribution groove 6, as shown in the illustrated example. Instead, the wood 5 may be supported sideways (in a diagonal state. In particular, if the length of the wood 5 is 400 cm)
In the case of a considerably long length of ~600 cm, the drying chamber 1 can be downsized by arranging the wood 5 sideways in an inclined state, and furthermore, the apparatus itself can be downsized.

Furthermore, if the dry air supply device 2 has a structure as shown in FIG. 4, it is possible to dry wood 5 of different thicknesses, etc.

That is, piping 12 is separately and independently provided for each set of injection nozzles 2a in the longitudinal direction, and heated dry air is supplied to each piping 12 under individually set conditions. Therefore, drying and heating air conditions can be set for each piece of lumber 5, which is suitable for high-mix, low-volume production in response to diversifying demand, and conditions can also be set individually for wood with different degrees of drying.

Furthermore, the method of the present invention can be applied to the cross-sectional shape of the wood 5, which is not limited to the circular shape as shown in the illustrated example, but can also be square or any other arbitrary shape.

Furthermore, the structure of the drying device is not limited to the illustrated example;
Any structure may be used as long as the drying method of the present invention can be carried out.

(Effects of the Invention) As described in detail above, according to the present invention, the gas circulation groove is provided over the entire length of the circumferential surface of the core holding wood until it reaches almost the center, and the drying gas is forced into the gas circulation groove. Since the wood was supplied, the inside and outside of the wood could be dried in parallel, and the occurrence of cracks on the surface of the wood could be prevented, and various other effects were obtained as listed below.

(1) When drying from the surface of the wood as in the conventional method (Fig. 6 (A))
Unlike the previous method (see Figure 6 (B)), the central part and the outer periphery of the wood are dried in parallel, making it possible to dry the entire interior of the wood to a predetermined moisture content in a short period of time (see Figure 6 (B)).
.

(2) In this method, the moisture gradient after drying is very gentle and small from the surface to the interior of the wood, as shown by the solid line in FIG. Therefore, there is not much difference in moisture content from the surface of the wood to the inside, and the quality of the wood inside the wood is uniform.

(3) In addition to the above-mentioned moisture gradient characteristics, not only the same wood, which has a high shrinkage rate due to drying, but also the core, which has a low shrinkage rate due to drying, dries at the same time. Since the wood is cut, the moisture contained in each annual ring layer is released efficiently and evenly, and no cracks occur on the wood surface.Therefore, there are almost no defective products, and the product yield is extremely high. Incidentally, the cracking incidence rate, which was conventionally about 30%, was reduced to about 2% by implementing the present invention.

(4) Due to the above-mentioned shortening of drying time and good yield,
Product costs can be significantly reduced.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram showing an artificial drying device used in the wood drying method according to the present invention, FIG. 2 is a perspective view showing the relationship between the dry air supply device of the drying device and the wood, and FIG. 4 is a cross-sectional view taken along line m-m in the figure, FIG. 4 is a view corresponding to FIG. 2 showing a modified example of the dry air supply device, and FIG. Fig. 6(A) is a cross-sectional view of wood showing the moisture movement by the conventional drying method, and Fig. 6(b) shows the moisture movement by the method of the present invention. FIG. 1... Drying room, 2... Dry air supply device, 2a...
Injection nozzle, 3...Air dryer, 4...Blower, 5
...Wood, 6...Gas circulation groove, 7...Exhaust duct, 11...Dry air circulation circuit

Claims (4)

[Claims] (1) A method for drying wood, which comprises providing a gas circulation groove along the entire length of the circumferential surface of a core-bearing piece of wood until it almost reaches the center, and forcibly supplying drying gas to the gas circulation groove. (2) The method for drying wood according to claim 1, wherein the gas flow groove is a backing. (3) The method for drying wood according to claim 1, in which the core holding wood is inclined and the gas flow grooves are directed downward, and the drying gas is supplied to the lower end of the gas flow grooves. (4) The wood drying method according to claim 1 or 3, wherein the drying gas is dry heated air.