JP2574623B2 - 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 a log material (log) with a bark of cedar or cypress, for example.

[0002]

2. Description of the Related Art Generally, when wood is used as a lumber product such as a pillar without drying, the product may be cracked or warped due to a difference in moisture content between the sapwood and the core material or a growth stress. Otherwise, a problem such as twisting occurs. For this reason, it is necessary to dry wood to a certain moisture content and then finish grind it into a finished product.Conventionally, to dry wood, for example, pile the wood outdoors and dry naturally. Or, they are housed in a drying room and dried with hot air.

However, conventionally, it is almost impossible to dry wood as it is with a bark, so that it is usually necessary to peel off the bark, further split the spine, and remove the inner portion from the split portion. Had released moisture. This is because the water inside the wood does not pass through the bark and is released from the side (the circumference of the log), and even if the bark is peeled off, there is a winter eye (the hard part of the annual rings). This is because the inside water cannot be released from the side unless the back is split.

[0004]

As described above, conventionally, it was not possible to cut a raw wood and then dry it as it was. Therefore, it was necessary to dry the raw wood after passing through a process such as rough grinding for stripping bark and splitting of the back. Therefore, time and labor for this, and various equipment and the like were required. Concretely, chemicals (preservatives, anti-cracking agents, etc.) to prevent mold and cracks before transporting wood and transport equipment such as vehicles required for each process, or drying process. A large amount of equipment investment such as labor for applying the coating, rough grinding equipment and its installation space, and the accompanying personnel are required.

[0005] In addition, since the bark is peeled off or the back is split for drying, the wood cannot be effectively used without any excess, and there is a problem that the yield of the product is not good.

[0006] The present invention has been made in view of these conventional problems, and can efficiently dry raw wood,
The object of the present invention is to provide a method for drying wood, which eliminates processes such as rough grinding or splitting of the spine, reduces costs, does not require extra fleshing for finish grinding, and can improve the yield of products. And

[0007] Therefore, the present invention provides a drying chamber capable of controlling the temperature and humidity after performing pretreatment for irradiating microwaves to the center of wood to increase the temperature and pressure inside the wood. And dried.

[0008]

According to the above arrangement, when the wood is irradiated with microwaves, the water molecules inside the wood are activated by the characteristics of the microwaves, so that the temperature and pressure inside the wood rise. When the temperature and pressure inside the wood rise, the cell valve of the wood is opened, so that the water inside the wood flows out of the cell valve and joins together, and the joined water joins in a state where it is further connected to the kiguchi. After all, inside the wood,
A water channel is formed from the center to the mouth. Then, after performing such a pretreatment, when the wood is heated by blowing hot air or the like in a drying room in which the temperature and the humidity can be controlled, the moisture in the inside easily moves toward the kiguchi, and passes through the kiguchi. It is discharged outside.

[0009] When the microwave is strongly applied to the center of the wood, the center is heated the most, and a temperature gradient is generated inside the wood such that the temperature becomes lower toward the tip of the wood. Since a pressure gradient with a higher pressure is generated, the formation of the water channel is further promoted, which is more preferable.

[0010] As described above, by increasing the temperature and pressure inside the wood to form a water channel for guiding the moisture inside the wood to the mouth, and then drying the wood, the conventional method is used. There is no need to perform bark stripping or spine splitting, and efficient drying can be achieved even with a bark-attached log.

[0011]

Next, an embodiment of the present invention will be described with reference to FIGS. FIG. 1 shows a schematic configuration of a drying apparatus D used in the drying method of the present example. This drying device D
As shown in FIGS. 1 and 2, a wood storage room 1 for storing wood W, and a wood W carried out of the wood storage room 1
And a drying chamber for drying a large amount of wood W at a time by blowing hot air onto the wood W that has been subjected to a predetermined pretreatment in the pretreatment chamber 2. 4 is provided.

A large number of woods W as a material to be dried are stored in the wood storage room 1 (not shown in the figure), and a transfer device (not shown) provided in the wood storage room 1 transports the wood 5 one by one. And supplied to the pretreatment chamber 2. The wood W is in a state in which the raw wood is simply cut to a certain length, and is stored without any processing such as bark stripping or spine splitting.

The interior of the storage room 1 and the interior of a drying room 4 described later are connected by a duct 7, and the hot air in the drying room 4 flows into the storage room 1. Thereby, the inside of the storage room 1 is maintained at a constant temperature, and the stored wood W is preheated.

The transport conveyor 5 is arranged from the storage room 1 to the inside of the drying chamber 4, and the pre-processing chamber 2 is provided in the middle of the transport conveyor 5.

The pretreatment chamber 2 is provided for performing the following pretreatment on the wood W prior to drying in the drying chamber 4. For this purpose, the pretreatment chamber 2 is provided with a predetermined microwave heating device. (Not shown) is provided. That is, the pre-treatment means that the wood W is irradiated with microwaves to make the inside thereof a constant state described later. This pre-processing will be described in further detail.

The microwave heating device may be a device generally used in the related art, and thus will not be described in detail. The microwave heating device is constituted by a microwave oscillator, a load circuit, a controller for controlling the operation of these devices, and the like. I have.

The wood W, which has been subjected to a predetermined pretreatment described later in the pretreatment chamber 2 thus configured, is carried into the drying chamber 4 by the conveyor 5. A stacking device 3 is installed near the entrance in the drying chamber 4, and the wood W carried in by the stacking device 3 is sequentially stacked on the stocker pallet P. The stocker pallets P filled with timber W are sequentially placed in the drying room 4
It is designed to be moved to the back.

The drying chamber 4 is of a type generally used in the past, which is configured so that a large amount of wood W can be dried at a time by blowing hot air onto the wood W. A temperature and humidity control system and the like are provided. As shown by the dashed line in FIG. 1, the drying chamber may be expanded in the width direction (right direction in the figure) so that a plurality of rows of the stocker pallets P can be packed at a time.

The wood W dried in the drying chamber 4 is separated into a wood W dried to a predetermined moisture content and a wood W not dried by measuring its weight, and the wood W dried to a predetermined moisture content is measured. Is taken out of the drying device D as the drying is completed, and the other wood W is returned to the wood storage room 1 and dried again by the above-described steps.

The drying apparatus D constructed as described above
According to the above, the wood W is irradiated with microwaves in the pretreatment chamber 2 as pretreatment before drying. This pretreatment utilizes the characteristics of microwaves. Specifically, when microwaves are irradiated on wood W containing water therein, water molecules are activated and collide with each other. In this case, a phenomenon that generates heat is used.

It is more effective to irradiate the microwaves around the center of the wood W, which is more effective for thick wood and wood with a large amount of water, whereby the moisture inside the wood W is heated. As a result, the wood W is gradually heated to a state where a temperature gradient is generated as shown in FIG. That is, the temperature of the water at the central portion in the longitudinal direction of the wood W increases (about 100 ° C.), and the water near the edge of the wood at the end has a lower temperature (about 7 ° C.).
(About 0 ° C.). By heating the water inside the wood W in a state where a temperature gradient is generated in this way, the pressure (water pressure) inside the wood W is increased, and a gradient corresponding to the temperature gradient is generated also in this pressure increase. . That is, the pressure near the tip of the wood W becomes higher than the atmospheric pressure, and the internal pressure becomes higher toward the center.

A microwave irradiation time of about 3 to 15 minutes is sufficient, so that the inside of the wood W becomes high temperature and high pressure,
In addition, a pressure gradient is generated such that the pressure becomes lower as approaching the kiguchi. Then, when this pressure gradient occurs, a water channel leading to the mouth is formed inside the wood W. That is, when the internal pressure (water pressure) rises, the water scattered up to that time breaks the cell membrane and joins each other, finally forming a large number of water passages passing between the cells, and this water passage is formed by the above-mentioned pressure gradient. Is formed toward the mouth.

After performing such a pretreatment, the wood W is carried into the drying chamber 4 and blown with hot air, and is left in this state for several days. During this hot-air drying, the moisture inside the wood W moves toward the wick in the above-mentioned waterway and is discharged outside through the wick.

As described above, according to the drying method of the present embodiment, the wood W is subjected to a pretreatment utilizing the characteristics of microwaves before the actual drying. In 2, the wood W is irradiated with microwaves to make the inside thereof a high temperature and a high pressure, whereby the cell valve of the wood W is opened to form a water channel leading to the mouth.

In an actual drying step performed in the drying chamber 4, hot wood is blown under the temperature and humidity control on the wood in a state where a water passage leading to the mouth is formed, so that the moisture inside the wood is directed toward the mouth. To be dried, and then discharged to the outside through the opening for drying. Therefore, drying can be performed efficiently even in the state of the raw wood with bark, so that there is no need to perform operations such as bark stripping or splitting that had been performed prior to drying. The step of drying W can be greatly simplified, and the cost can be greatly reduced.

Further, since the raw wood can be dried without bark peeling or splitting, the wood W can be effectively used without any excess, and therefore, the yield of lumber products can be improved. Further, conventionally, it is possible to reduce the number of workers or equipment and the space required for bark peeling or back splitting work, and the like,
In this respect, the cost can be increased.

Furthermore, since the raw wood can be dried and stored, there is no need to apply chemicals such as preservatives, and the labor and cost of chemicals can be reduced, and the wood can be dried as it is. It can be stored and stored, so that the shipment can be adjusted, and as a result, timber can be supplied at a stable price.

Further, since the wood can be transported in a state where it is dried at the time of the raw wood and its weight is reduced to almost half, the transportation cost can be reduced.

[0029]

According to the present invention, wood can be dried as it is, eliminating the need for conventional bark peeling or splitting. Therefore, the process of drying wood is greatly simplified and cost is reduced. In addition, since it can be transported in a state where it is dried and its weight is reduced to almost half, the transportation cost can be reduced.

[Brief description of the drawings]

FIG. 1 shows an embodiment of the present invention and is an overall plan view of a drying apparatus.

FIG. 2 is a partially transparent side view of a drying device.

FIG. 3 is a perspective view of a log cut to a certain length.

FIG. 4 is a graph showing a temperature gradient inside wood.

[Explanation of symbols]

 D: Drying device W: Wood 1: Storage room 2: Pretreatment room 3: Stacking room 4: Drying room 5: Conveyor 7: Duct

Claims (1)

(57) [Claims] 1. A method for drying a wood in a drying chamber in which temperature and humidity can be controlled after performing a pretreatment for irradiating a microwave to a central portion of the wood to increase the temperature and pressure inside the wood. Characteristic wood drying method.