JPH04306481A - Drying method and drying device of lumber - Google Patents

Abstract

PURPOSE:To shorten drying time and prevent cracking upon drying by a method wherein lumbers are heated and softened in a high-temperature high-pressure vessel to squeeze the moisture of the lumbers out by compressing them and, thereafter, the lumbers are restored to a condition of slightly compressed whereby the lumbers are dried. CONSTITUTION:When lumbers 1 are carried into a high-temperature high-pressure vessel 2 to receive them into a receiving mold 10 of a press 3 and a lid 5 is closed to seal the vessel 2, then, high-temperature high-pressure steam is supplied into the vessel 2 through a steam pipeline 6 to heat the lumbers 1, the lumbers 1 absorb the steam and are softened. When the plunger 12 of the press 3 is descended to compress the lumbers 1, moisture in the lumbers is squeezed out and the moisture content of the lumbers l is unified. When the compressing condition is released to bring the lumbers 1 into a condition that a pressure is applied on them slightly and the steam in the vessel 2 is discharged through an exhaust pipeline 8 to reduce the pressure in the vessel, the lumbers are brought into dried condition. The moisture, squeezed out of the lumbers 1, is recovered through a steam drain pipeline 7, then, high-frequency electric current is supplied to the receiving mold 10 and the plunger 12 to dry the lumbers through high-frequency heating whereby the drying of the lumbers 1 is finished.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and apparatus for drying wood.

0002

[Prior Art] In general, wood is easy to process and has good electrical and thermal insulation properties, making it an excellent material. However, it tends to warp due to shrinkage and expansion due to moisture absorption and desorption, so it must be dried before use. There is a need.

[0003] When wood is subjected to chemical processing or chemical modification treatments such as bleaching, coloring, preservatives, insect repellent, termite repellent, flame retardant, resin impregnation, etc., it is necessary to dry the wood before the treatment in order to improve the effect and efficiency of the treatment. There is a need.

[0004] To dry wood, there are two methods: natural drying, in which the wood is left under natural conditions to dry, dehumidifying drying, in which the wood is placed in a drying chamber and dried using a dehumidifier, and high-frequency heating under reduced pressure. There is also artificial drying such as reduced pressure high frequency drying.

[0005]

[Problems to be Solved by the Invention] However, although the above-mentioned natural drying is relatively easy to dry to a certain extent, it takes a very long time (several months) to dry it further. Also, although artificial drying does not take as long as natural drying, it still takes a considerable amount of time (2 to 3 weeks), and during this time dehumidifiers, high-frequency heating equipment, etc. must be operated day and night, which increases running costs and labor costs. The cost is high due to increased costs and management costs, and since the inner heartwood contains more moisture than the outer sapwood, only the sapwood quickly dries and the heartwood deteriorates. The current situation is that the drying of the parts is delayed, resulting in tensile stress in the sapwood part and compressive stress in the heartwood part, resulting in many cracks.

The present invention has been proposed in view of the above points, and an object thereof is to provide a method and apparatus for drying wood that significantly shortens the drying time and prevents cracking during drying. shall be.

[0007]

[Means for Solving the Problems] In order to achieve the above object, the present invention heats and softens wood in a high-temperature, high-pressure container using an appropriate heating means, compresses this wood using an appropriate compression means, and compresses the wood inside the wood. To provide a method for drying wood, in which after forcibly squeezing out the moisture in the cavity, the compressed state of the wood is released to restore the wood to a slightly compressed state than before compression, and then the wood is dried inside or outside a high temperature and high pressure container. do.

[0008] The present invention also provides a high-temperature, high-pressure container provided with an appropriate heating means for heating wood inside or outside, and a high-temperature, high-pressure container provided inside the above-mentioned high-temperature, high-pressure container, in which wood is heated by an appropriate heating means within the high-temperature, high-pressure container. To provide a wood drying device comprising a press machine which compresses wood which has been softened by compressing the wood and releases the compressed state of the wood so that the wood is restored to a state slightly compressed than before compression after the compression.

[0009]

[Operation] According to the present invention, when wood is compressed after being heated and softened, the moisture contained in the wood's inner cavity is forcibly squeezed out. In this way, drying is performed with the moisture squeezed out, so the drying time can be significantly shortened. In addition, heating removes growth distortions from the wood, and compression squeezes out most of the moisture in the sapwood and heartwood, making them uniform, so cracks do not occur during drying.

0010

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be explained below based on embodiments shown in the drawings.

FIGS. 1 and 2 are schematic overall views showing an example of an apparatus for carrying out the method of the present invention, in which 1 represents wood, 2 represents a high-temperature and high-pressure container, and 3 represents a press machine, respectively.

The high-temperature and high-pressure container 2 is made of a container body 4 made of high-strength steel or stainless steel, with a lid 5 attached to the opening of the container so that it can be opened and closed in a sealed manner. A piping 6 and a steam drain piping 7 extending toward the steam supply device are provided, and high temperature (
100~180℃) and high pressure (1.2~25
Kg/cm2) of steam is supplied to the inside, and the steam drain is recovered to the steam supply device through a steam drain pipe 7. Note that 8 is an intake pipe connected to a vacuum device (not shown), and the vacuum device takes in air from inside the high-temperature, high-pressure container 2 through this intake pipe 8, and evacuates the inside of the high-temperature, high-pressure container 2. It looks like this.

As shown in FIGS. 1 and 2, the press 3 includes a mold 10 having a concave cross-section and a groove 9 large enough to accommodate the wood 1, and a plurality of press cylinders 11, 11...
The plunger 12 is fitted into the groove 9 of the receiving mold 10 by the downward movement of the press cylinders 11, 11, . . . The jar 12 is configured to compress the wood 1 stored in the groove 9 of the receiving mold 10. In addition, the receiving mold 10 of the press machine 3
The plunger 12 is a high frequency electrode, and when the wood 1 is sandwiched between the mold 10 and the plunger 12 and a high frequency current is supplied, the wood 1 is heated by high frequency.

Next, the method for drying wood according to the present invention will be explained.

First, the lid 5 of the high-temperature and high-pressure container 2 is opened, and the wood 1 is carried into the high-temperature and high-pressure container 2. As shown in FIG. to store. Next, after closing the lid 5 of the high-temperature and high-pressure container 2 to seal the high-temperature and high-pressure container 2, high-temperature (100 ~
180℃) and high pressure (1.2~25Kg/cm
2) Steam is supplied, and the wood 1 is heated with this high-temperature, high-pressure steam. In this state, wood 1 is held for a predetermined period of time (1~
10 minutes) When heated, the wood 1 absorbs high-temperature, high-pressure steam and its temperature rises, thereby softening the wood 1.

[0016] Then, when the wood 1 becomes soft, the press machine 3
The plunger 12 is lowered by the press cylinders 11, 11... and fitted into the groove 9 of the receiving mold 10, and as shown in FIG. , 11... through the plunger 12 to about 1/2 to 1/3 of the cross-sectional area ratio. In this way, the cross-sectional area ratio of wood 1 is 1/2 with press machine 3.
When compressed to about 1/3, the pits inside the wood 1 will be forcibly destroyed and the flow of moisture will not be obstructed, so most of the moisture in the wood 1 will be squeezed out and each part will be compressed. The moisture content of the mixture becomes uniform.

When most of the moisture in the wood 1 is squeezed out by compression and the moisture content in each part is made uniform, the plunger 12 of the press 3 is moved to the press cylinders 11 and 1.
1... increases the thickness of the wood 1 to around 98% of the thickness before compression. Then, as shown in FIG. 4, the wood 1 is released from its compressed state and gradually expands to restore its cross-sectional area ratio to around 98%, after which it becomes slightly pressurized by the plunger 12. In this state, the inside of the high-temperature, high-pressure container 2 is actively evacuated through the exhaust piping 8 by the exhaust device to exhaust the high-temperature, high-pressure steam inside the high-temperature, high-pressure container 2, and the pressure is reduced by the vacuum device. The wood 1 heated before compression is in a dry state. At the same time, the water squeezed out from the wood 1 is recovered from the high temperature and high pressure container 2 through the steam drain pipe 7. After this, the receiving mold 1 of the press machine 3
0 and the plunger 12 to supply high frequency current to the wood 1.
The wood 1 is dried to a predetermined state by high-frequency heating. Then, the lid 5 of the high-temperature, high-pressure container 2 is opened and the wood 1 is taken out from the high-temperature, high-pressure container 2 to complete drying. In this way, the wood 1 is heated and softened inside the high-temperature, high-pressure container 2, compressed to forcibly squeeze out the moisture, and then dried using high-frequency heating.
could be dried to the desired condition.

In the above embodiment, the wood 1 is compressed in the high-temperature, high-pressure container 2 to forcibly squeeze out moisture to dry it, and then further heated with high frequency in the high-temperature, high-pressure container 2 to bring it to a predetermined state. Although the present invention is not limited to this, the wood 1 is dried by compressing it in a high temperature and high pressure container 2 to forcibly squeeze out moisture, and then drying the wood 1 at a high temperature and high pressure. It is also possible to take it out from the container 2 and dry it in a normal dryer to a predetermined state. In this case, the wood 1 could be dried to a predetermined state within one day.

Further, in the above embodiment, the wood 1 is heated with high-temperature, high-pressure steam to soften it, but it is also possible to soften it by heating with a heating means other than high-temperature, high-pressure steam, such as a high-frequency heater. . In particular, high frequency heating is efficient.

Furthermore, although the above embodiment describes the case of drying a square timber, if the receiving mold 10 and plunger 12 of the press machine 3 are changed as shown in FIGS. 5 to 7,
Logs can also be dried, and the mold 1 of the press 3 can also be dried.
0 and the plunger 12 as appropriate, it is possible to dry wood of various shapes.

[0021]

[Effects of the Invention] According to the present invention, as explained above,
To dry the wood to a specified state, the wood is heated in a high-temperature, high-pressure container to soften it, and then compressed to forcefully squeeze out the moisture in the wood cavity before drying, which reduces the drying time. The drying time is significantly reduced from half a day to one day, and the drying cost is greatly reduced. At the same time, the heating removes the growth distortion of the wood, and at the same time, the compression squeezes out most of the moisture in the sapwood and heartwood, reducing the moisture in each part. Since the ratio is uniform, cracking during drying can be prevented,
Moreover, since the pits inside the wood are forcibly damaged by heating and compression, it becomes easier to impregnate the wood with resin, preservatives, etc.

[Brief explanation of drawings]

FIG. 1 is a schematic configuration diagram showing an example of an apparatus for implementing the method of the present invention.

FIG. 2 is a longitudinal cross-sectional view taken along line AA in FIG. 1;

FIG. 3 is a longitudinal sectional view showing a state in which wood is compressed using a press according to the method of the present invention.

FIG. 4 is a longitudinal cross-sectional view showing a state in which the wood has been compressed by the method of the present invention and then restored to a thickness slightly below the thickness before compression.

5 to 7 are diagrams illustrating operating states when drying logs according to the method of the present invention.

[Explanation of symbols]

1 Wood 2 High temperature and high pressure container 3 Press machine 4 Container body 5 Lid 6 Steam piping 7 Steam drain piping 8 Exhaust piping 9 Groove 10　　　　Receiving mold 11 Press cylinder 12 Plunger

Claims (2)

[Claims] Claim 1: Wood is heated and softened in a high-temperature, high-pressure container using an appropriate heating means, and the wood is compressed using an appropriate compression means to forcibly squeeze out the moisture in the inner cavity of the wood, and then the wood is compressed. A method for drying wood, which comprises releasing the wood to restore it to a slightly compressed state than before compression, and drying it inside or outside a high temperature and high pressure container. 2. A high-temperature, high-pressure container provided with an appropriate heating means for heating the wood inside or outside; and a high-temperature, high-pressure container provided inside the high-temperature, high-pressure container, which is heated by an appropriate heating means in the high-temperature, high-pressure container to soften the wood. A method for drying wood, comprising: a press machine which compresses the compressed wood, and releases the compressed state of the wood so that after the compression the wood is restored to a state slightly more compressed than before compression.