JP2002086406A - Method and apparatus for drying and reforming of lumber by injection of steam - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method and an apparatus for drying and reforming lumber wherein time for drying and reforming is short, and a dry crack owing to occurrence of stress is not generated. SOLUTION: Through holes 10 are provided in a specific density into lumber by laser incising, and the lumber is dried by allowing high temperature steam to flow through the through holes 10.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

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

[0002]

2. Description of the Related Art When wood is left in the air, the moisture content of the wood increases and decreases with changes in the temperature and humidity of the air. This phenomenon always occurs during the period when the finished wooden product is used for a purpose. Whenever the moisture content increases or decreases, the material undergoes dimensional changes, ie, expansion and contraction.
The expansion and shrinkage of the wood results in deformation, loosening of the joint, peeling of the adhesive layer, step of the joint caused by a difference in shrinkage, cracking of the coating film and various other defects in the product. However, if the product is made of a material that has been dried to a moisture content suitable for the air conditions at the place of use, the occurrence of expansion and contraction defects during use can be minimized. For this reason, wood drying is extremely important.

[0003] In the conventional method of artificially drying wood, the wood is heated by heat conduction from the surface of the wood to evaporate the internal moisture only from the surface. Since wood has low thermal conductivity and does not easily transfer water, it takes more than one week to heat and dry the pillars. There is dielectric heating drying to shorten the drying time, but since there is no escape for high pressure steam generated inside the wood, internal cracks occur due to stress generated in the wood and carbonization occurs due to excessive concentration of energy . As a method for smoothly releasing high-temperature and high-pressure steam generated by dielectric heating and drying of wood to the outside, for example, there is a method described in Japanese Patent Publication No. 7-115326. This method is called laser insizing, in which a plurality of non-penetrating insizing micro holes are made in wood with a CO ₂ laser beam, a wood modifying solution is injected and impregnated into the holes, and then dielectric heating and drying are performed. Is the way. In this method, when the inside of the wood is heated using dielectric heating, the drying efficiency is increased and the distribution of moisture in the wood is compared to that without the insizing because the insizing hole functions as a hole for discharging moisture in the material. Although it is uniform, there is a problem that it still takes 100 hours or more to dry, including other high-temperature drying methods that are artificial drying methods.

[0004]

Accordingly, the present invention has been made in view of the above-mentioned problems, and does not cause dry cracking due to stress.
An object of the present invention is to provide a method and an apparatus for drying and modifying wood, which can significantly reduce the drying time.

[0005]

SUMMARY OF THE INVENTION In order to achieve the above object, a method for drying and modifying wood according to the present invention is to provide a method for drying wood by providing through holes at a predetermined density in wood and allowing high-temperature steam to flow through the through holes. Is performed. In the method for drying and reforming wood of the present invention, a chemical for wood reforming may be further mixed into the steam to modify the wood simultaneously with the drying of the wood. According to these configurations, high-temperature steam flows through the through-holes of the wood, and at that time, the wood is rapidly dried by the heating effect of the steam and the water-sucking effect of the wood due to a decrease in air pressure due to the flowing steam flow. In addition, since uniform heating and moisture removal can be achieved, the occurrence of stress is small,
No internal cracks or surface cracks occur in the wood. Furthermore, when chemical vapor is used, the whole wood can be subjected to a preservation treatment and a high-performance treatment simultaneously with drying.

The apparatus for drying and reforming wood by steam injection according to the present invention comprises a high-temperature steam inlet, a first chamber having a surface for spraying high-temperature steam and supporting wood, a high-temperature steam collecting and wood-recovering apparatus. And a second chamber having an exhaust port for exhausting the collected high-temperature steam, and on each of the two side surfaces or the upper and lower surfaces of the wood block in which the wood provided with the through holes is closely stacked, The first and second chambers are characterized in that the surfaces supporting the wood are brought into close contact with each other to dry and modify the wood by steam injection. According to the wood drying and reforming apparatus of the present invention having this configuration,
High-temperature steam flows through the through-holes of the wood, and the heating effect of the steam and the moisture suction effect of the wood due to the decrease in air pressure due to the flowing steam flow enable rapid drying and reforming of the wood, and a large amount of wood at once. Can be processed.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below in detail with reference to FIGS. As test materials, wood from Iwate cedar (water content: 74 to 167%), 105 mm square, 4 m in length, heart-holding (material including pith), and no split (artificially inserted crack) were used. FIG. 1 shows the test material and the wood removal of the test piece for measuring the moisture content distribution. As shown in FIG. 1A, the test material 1 was 100 mm × 1 from the test material 2.
A piece of wood having a length of 05 mm and a length of 600 mm was cut out. As shown in FIG. 1 (a), a test piece 3 for measuring the water content was cut out from a test piece 2 by cutting a piece of wood having a thickness of 100 mm × 105 mm and a thickness of 30 mm, and as shown in FIG.
The wood pieces 4 were decomposed into small pieces, and the water content of each piece 4 was measured by a total drying method to measure the water content distribution of the wood.

FIG. 2 shows an example of the laser insizing device 5. The laser beam 7 of the CO ₂ laser 6 is condensed by the condenser lens 8 and irradiated on the test material 1 arranged on the processing table 9, and the processing table 9 is moved in the X direction and the Y direction. Also, the insizing hole 10 is formed at an arbitrary density. In this embodiment, for example, 5000 pieces / m ² or 10000 pieces / m ^{2 in} the thickness or width direction of the test material 1.
Insizing holes 10 were drilled at a density of m ² .

FIG. 3 schematically shows the shape of the insizing hole 10 formed in the test material 1.
The diameter 0 is large on the surface a on which the laser beam 6 is incident, thin on the surface b on which the laser beam 6 is emitted, and
Penetrates. The diameter of the insizing hole 10 is about 2 mm on the surface a side where the laser beam 6 is incident.

Next, a method for causing high-temperature steam to flow through the insizing hole 10 of the test material 1 will be described. FIG.
It is a block diagram of the steam injection press type drying device 11 used in the present embodiment. In the method for drying wood of the present invention, high-temperature steam of 100 ° C. or higher is used. That is, since steam at 120 ° C. has about 2 atm and steam at 160 ° C. has about 6.2 atm, the steam injection press type drying apparatus 11 needs a configuration capable of controlling the high pressure of high-temperature steam. Hereinafter, the steam injection press type drying device 11 will be described. The steam injection press type drying device 11 includes a lower hot platen 12 for generating high-temperature steam.
An upper hot platen 13 for collecting or transmitting high-temperature steam and pressing the test material 1 on the lower hot platen 12, a sealing member 14 such as Teflon for sealing the high-temperature steam without leaking, And a spacer 15 which is a stainless steel wire mesh or the like disposed in the steam through hole 14a of the seal member 14. The test material 1 is sandwiched from the side by a pair of dummy materials 16 having no insizing hole 10 for preventing vapor from escaping from the side surface of the test material 1, and the direction of the insizing hole 10 is changed in the direction of the arrow in the figure. The sealing members 14 and the spacers 15 are arranged between the lower hot platen 12 and the upper hot platen 13, and are pressed and held between the lower hot platen 12 and the upper hot platen 13. In this state, high-temperature steam injected from the lower heating plate 12 flows through the penetration insizing hole 10 of the test material 1, and at this time, a heating effect by the steam and a moisture suction effect of the wood due to a decrease in the pressure of the flowing steam flow. Thereby, the wood is rapidly dried. The test material 1 and the tip of the dummy material 16 are sealed with a silicone adhesive or the like so that steam does not escape.

Next, a description will be given of an embodiment of the present invention and the operation and effect thereof. First, the steam temperature is 120 ° C, 140 ° C,
At each of 60 ° C., the time corresponding to 2 to 4 times the time from the start of drying to the time when the test material 1 becomes almost constant 12
The change of the temperature at the center of the test material 1 during the drying for 00 seconds and the relationship between the drying time and the moisture content of the test material 1 are shown. The temperature of the test material 1 was measured using a copper-constantan thermocouple. FIG. 5 is a measurement result showing the relationship between the temperature at the center of the test material 1 and the drying time. In FIG. 5, the dotted line represents the density of the insizing holes 10, that is, the test material 1 having an insizing density of 10,000 / m ² , the solid line represents the test material 1 having an insizing density of 5000 / m ² , The control material for comparison without the insizing hole 10 is shown.

From the results shown in FIG. 5, the control material shows almost no temperature rise, but the test material 1 provided with the insizing holes 10 has a rapid temperature rise, and it takes several tens of seconds at 140 ° C. and 160 ° C. steam temperature. The central temperature of the test material 1 can be raised almost to the steam temperature in a few minutes, and the higher the steam temperature and the higher the insizing density, the shorter the time until the center temperature of the test material 1 becomes constant. I understand.

FIG. 6 is a measurement result showing the relationship between the drying time at a steam temperature of 120 ° C. and the water content. The moisture content during drying was determined by a method in which the steam injection was stopped, the mass of the test material 1 was measured, and a back calculation was performed from the total dry mass of a part of the test material 1 after the drying was completed. The water content is defined as water content = (mass in water-containing state−total dry mass) / total dry mass. From the results in FIG.
Approximately 10 hours, a measure of the usable moisture content of wood1
It turns out that it reaches 5%. Further, it can be seen that the higher the insizing density, the sooner and lower the water content. FIG. 7 shows a measurement result of the distribution of the water content of the test material 1 after drying at a steam temperature of 120 ° C. for 10 hours. FIG.
(A) shows the water content distribution in the direction orthogonal to the insizing hole 10, and 0 represents the center of the test material 1. FIG. 7 (b)
Indicates a water content distribution in a direction parallel to the insizing hole 10. In the measurement of the water content distribution, as shown in FIG. 1B, the test piece 3 for measuring the water content is divided into individual wood pieces 4, and the water content of each of the wood pieces 4 is measured.

From the results shown in FIG. 7, it can be seen that the water content is uniformly reduced from the center to the periphery of the test material 1. In addition,
Although two graphs with an insizing density of 5000 pieces / m ² are shown, even if the specimen 2 is the same, the specimen 1
This indicates that the results differ depending on the site from which the is taken out. FIG. 8 is a measurement result showing the relationship between the drying time at a steam temperature of 140 ° C. and the water content of the test material 1. The measuring method is the same as in FIG. Comparing the results of FIGS. 8 and 6, it can be seen that the higher the steam temperature, the more quickly the water content decreases. FIG. 9 is a photograph of the side and cross section of the wood after drying at a steam temperature of 140 ° C. for 5 hours. As is clear from FIG. 9, it can be seen that dry cracking, which has conventionally been a problem in artificial drying, has not occurred.

If a chemical is mixed with the injected steam or the vapor of the chemical is used, it is possible to simultaneously perform the preservation treatment and the high-performance treatment of the wood simultaneously with the drying. Drugs include insect repellents,
Examples include preservatives, termites, flame retardants, wood modifying agents, and chemical processing agents for wood. Further, since the insizing hole of the present invention is a through-hole, even if the concentration of these chemicals is low, the entire wood can be impregnated.

Next, an apparatus for drying and reforming wood by steam injection according to the present invention will be described. FIG. 10 is a perspective view showing the structure of a wood drying and reforming apparatus using steam injection according to the present invention. The apparatus comprises a first chamber 20 having an inlet 18 for introducing high-temperature steam 17, a surface 19 for injecting high-temperature steam 17 and supporting wood, and a surface 21 for collecting high-temperature steam 17 and supporting wood. And a second chamber 23 having an exhaust port 22 for exhausting the collected high-temperature steam 17. The wood 24 provided with the insizing holes at a predetermined density is aligned with the direction of the insizing holes from the first chamber 20 to the second chamber 23, and the two sides of the timber blocks 25 stacked closely together. The first chamber 20 and the second chamber 23 are brought into close contact with each other. Alternatively, when the shapes of the woods 24 are different, the woods 24 are stacked according to the woods 24 having the largest dimensions,
Seal the gap to prevent steam leakage. Further, the timber 24 is stacked so that a slight gap is formed between the surfaces of the timber 24 having the insizing holes.
The high-temperature steam 17 that has flowed through all the insizing holes of the next wood 24 is allowed to flow uniformly.

The high-temperature steam 17 is introduced into the first chamber 20 through the inlet 18, and the high-temperature steam 17 is jetted from the surface 21 for supporting the wood. Through. The high-temperature steam 17 that has flowed through is collected into the second chamber 23 via the wood supporting surface 21 of the second chamber 23, and is exhausted from the exhaust port 22. According to this apparatus, a large amount of wood can be dried and modified at once. In FIG. 10, the horizontal type configuration in which the first and second chambers are arranged on both side surfaces of the wood block is shown, but the vertical type configuration in which the first and second chambers are arranged on the upper and lower surfaces of the wood block. It may be a configuration.

[0018]

As will be understood from the above description, according to the drying and reforming apparatus for wood and the apparatus according to the present invention, the drying time and the reforming time according to the conventional method can be reduced without causing dry cracking. It can be dried and modified in a much shorter time. The present invention is a structural member used in the wooden frame method of drying, storage treatment, members that require chemical treatment, and,
It is useful for drying and preserving exterior members used in parks, field athletics, and the like, and is also useful for processing wood for high functionality.

[Brief description of the drawings]

BRIEF DESCRIPTION OF DRAWINGS FIG. 1 is a view showing a test material and a wood sample of a test piece for measuring a moisture content distribution.

FIG. 2 is a diagram illustrating an example of a laser insizing device.

FIG. 3 is a diagram schematically showing a shape of an insizing hole formed in a test material.

FIG. 4 is a diagram showing a configuration of a steam injection press type drying apparatus used in the present embodiment.

FIG. 5 is a graph showing the measurement results of the relationship between the temperature at the center of the test material and the drying time in the method for drying and modifying wood by steam injection according to the present invention.

FIG. 6 is a graph showing a measurement result of a relationship between a drying time at a steam temperature of 120 ° C. and a moisture content of a test material in a method for drying and modifying wood by steam injection according to the present invention.

FIG. 7 is a graph showing a measurement result of a water content distribution of a test material after drying at a steam temperature of 120 ° C. for 10 hours in the method of drying and modifying wood by steam injection according to the present invention.

FIG. 8 is a graph showing a measurement result of a relationship between a drying time at a steam temperature of 140 ° C. and a moisture content of a test material in the method of drying and modifying wood by steam injection according to the present invention.

FIG. 9 is a side view and a cross-sectional view showing photographs of a side surface and a cross-section of wood after drying at a steam temperature of 140 ° C. for 5 hours in the method of drying and reforming wood by steam injection according to the present invention.

FIG. 10 is a perspective view showing the structure of a device for drying and reforming wood by steam injection according to the present invention.

[Explanation of symbols]

REFERENCE SIGNS LIST 1 Test material 2 Test material 3 Test piece for measuring water content 4 Wood piece 5 Laser insizing device 6 CO ₂ laser 7 Laser beam 8 Condensing lens 9 Processing table 10 Insizing hole 11 Steam injection press type drying device 12 Lower heat Board 13 Upper heating plate 14 Seal member 15 Spacer 16 Dummy material 17 High-temperature steam 18 Inlet 19 Wood supporting surface 20 First chamber 22 Exhaust port 23 Second chamber 24 Wood 25 Wood block

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 2B230 AA15 BA01 BA16 EA21 EB12 3L113 AA01 AB03 AC05 BA05 CB25 CB26 DA10 DA24

Claims (3)

[Claims] 1. A method for drying and modifying wood by steam injection, characterized in that a through hole is provided in the wood at a predetermined density, and the wood is dried by passing high-temperature steam through the through hole. 2. The drying and drying of wood by steam injection according to claim 1, wherein a wood-modifying agent is mixed into the steam, and the wood is modified simultaneously with the drying of the wood. Reforming method. 3. A high temperature steam inlet, a first chamber having a surface for injecting the high temperature steam and supporting the wood, a surface for collecting the high temperature steam and supporting the wood, And a second chamber having an exhaust port for exhausting steam, on both sides or upper and lower surfaces of a wood block in which wood with a through hole is closely stacked, respectively, the first and second chambers are provided. An apparatus for drying and reforming wood by steam injection, wherein drying and reforming of wood by steam injection are performed by bringing the surface supporting the wood into close contact.