KR20150040541A

KR20150040541A - Heating and drying method of veneer using microwave

Info

Publication number: KR20150040541A
Application number: KR20130119178A
Authority: KR
Inventors: 서진석; 박상범; 임남기; 박철우
Original assignee: 대한민국(산림청 국립산림과학원장)
Priority date: 2013-10-07
Filing date: 2013-10-07
Publication date: 2015-04-15

Abstract

The present invention relates to a heating and drying method of a veneer using microwave capable of securing a functional wood material and a functional construction material within a short time by rapidly heating and drying the veneer in the shape of a flat plate or a roll using the microwave. According to the present invention, the heating and drying method of a veneer using microwave comprises: a chamber containing the veneer; a magnetron generating the microwave to dry the veneer contained in the chamber; and a control portion to entirely control a heating and drying apparatus. A heating and drying method using the apparatus comprises: a step of setting a heating temperature of the veneer and water content after heating; a step of heating and drying the veneer inside the chamber by generating the microwave in the magnetron; a step of measuring a water content reduction ratio of the veneer; and a step of measuring a surface temperature distribution through a thermal image.

Description

TECHNICAL FIELD [0001] The present invention relates to a heating and drying method of a veneer using microwave,

The present invention relates to a method of heating and drying a veneer using a microwave, and more particularly, to a method of heating and drying a veneer using a microwave, The present invention relates to a method of heating and drying a single plate using a microwave capable of securing a functional wood material and a building material.

In order to process the wood for industrial use, it is necessary to dry the wood. At this time, depending on the drying method and management, the quality of the wood is greatly affected. Defects and deterioration of the wood are mostly related to drying. In case of using improperly dried wood, damage due to stress and difficulty in processing are accompanied. After installation, defects such as dimensional change, rippling, and distortion due to drying and shrinkage will occur due to the influence of outside air. Drying should be done at moisture content below the fiber saturation point, and the processed wood to be applied to the inside and outside needs to be adjusted to the equilibrium moisture content.

Typical wood drying methods can be divided into natural drying and artificial drying. The natural drying is to follow the action to prevent the direct sunlight and to ensure good ventilation between the residues after the wood or the timber has been removed at regular intervals. Although it is possible to reduce the occurrence of dry defects by shortening the period of time only by surface drying, there is a problem that it takes a very long time to dry to below the fiber saturation point.

In case of artificial drying, there are various methods such as a steam method, an open method, a fuming method, a vacuum method and a high-frequency method, and they are forced to be dried by heat or hot air. The drying process is mostly used. However, when the wood is dried by heat or hot air, there is a high possibility that quality defect of the dried product occurs due to the color change of the wood and the stress due to the difference in temperature between the inside and the outside .

Recently, a microwave drying method has been developed, in which microwaves irradiated inside wood are reacted with water molecules having asymmetric charges and converted into rotational kinetic energy and rotation-induced intermolecular frictional heat energy, As the vapor pressure inside the wood is increased, the steam from the inside is diffused to the surface and dried. Microwave heating can raise the temperature of the whole material constantly because the surface and the inside of the object are heated almost simultaneously, and when the inside of the material is sufficiently heated, the moisture is moved to the outside to induce quick drying and uniform drying There is an advantage.

Patent No. 678975 entitled " Control Method of Heating and Drying Characteristics Measurement System Using Microwave Energy ", Japanese Laid-Open Patent Application No. 2009-100928 "Wood Drying Device Having Controllable Efficient Control of Microwave" , But they are related to an apparatus or a method for drying a log, and it can be used to rapidly dry wood without damaging a wood with a thin layer of a thickness of about 2 to 3 mm, such as a single plate. There is no problem.

The present applicant (National Forestry Academy of Forest Service) is a national research institute that conducts research on forestry, forestry, and the wood industry, and has developed and distributed many technologies related to timber for the development of the wood industry. On the other hand, the present applicant has applied for and registered a large number of patents on a single-plate laminated material using a single-cut laminated wood having a thickness of about 2 to 3 mm and a device for molding the laminated wood, The inventors of the present invention have conducted much research and development with respect to the apparatus and method for drying the veneer sheet without defects in a short time, and have developed the heating and drying method of the present invention.

SUMMARY OF THE INVENTION An object of the present invention is to provide a method of producing a functional wood material and a building material which are not discolored and which are not discolored or cracked during rapid heating and drying of a plate material or a rolled single- The present invention provides a method of heating and drying a single plate using a microwave, which is capable of securing a desired quality by measuring a water content reduction rate and a surface temperature distribution through a thermal image.

According to an aspect of the present invention, there is provided an apparatus for heating and drying a single plate using a microwave, the apparatus comprising: a chamber accommodating a single plate; a magnetron generating a microwave for drying the single plate accommodated in the chamber; Wherein the heating and drying method of the single plate using the apparatus comprises: setting the heating temperature of the single plate and the water content after heating; Generating microwaves in the magnetron to heat and dry the single plate inside the chamber; Measuring a water reduction rate of the single plate; And measuring the surface temperature distribution through the thermal image.

Preferably, when the single plate is accommodated in a chamber of a flat plate having a thickness of 2 to 3 mm, it is heated for 20 to 25 minutes at an output of 3 kW magnetron, the heating temperature of the single plate is 90 to 100 캜, 50 to 60%, and the water content after heating is 10 to 15%.

Preferably, when the single plate having a thickness of 2 to 3 mm is put in a roll state and is accommodated in the chamber, the heating is carried out for 60 to 70 minutes at an output of 3 kW magnetron, the heating temperature of the single plate is 90 to 100 캜, The reduction rate is 50 to 60% by weight and the water content after heating is 10 to 15%.

Preferably, the surface temperature distribution of the single plate, which is measured through thermal imaging after heating, is 90 to 100 캜.

The heating and drying method of the single plate according to the present invention having the above characteristics is characterized in that the heating temperature and the optimum moisture content are set according to the shape of the tree and the shape of the single plate (flat plate or roll) Since it controls the surface temperature distribution through the thermal image, it is dried from the inside of the wood unlike the case of heating and drying by using the general hot air, so that defects such as cracks, warping or discoloration can be prevented during the drying process, Can be remarkably shortened.

The method of heating and drying a single plate using microwave according to the present invention is a method for heating and drying a single plate by immersing a green veneer in a preservative treatment such as various liquid dyes and refractory / It is possible to develop a large variety of single-plate products by adopting an efficient process by microwave drying after re-construction of the car by the massive penetration by the car, and it is possible to develop the indoor and outdoor finishing materials, the theater, the observation hall, the school, the gymnasium, It is possible to utilize the woody material utilizing veneer veneer lamination in all parts such as facilities and department stores.

1 is a view schematically showing a heating and drying apparatus according to the present invention.
2 is a flow chart showing a heating and drying method according to the present invention.
3 is a surface thermal distribution photograph taken by a thermal imaging camera after microwave heating of a veneer single plate.

The most significant technical feature of the heating and drying method of the single plate using microwave according to the present invention is that the heating temperature and the optimum moisture content are set according to the shape of the tree and the shape of the single plate (flat plate or roll) Since microwaves are used as a heat source, defects such as cracks, warping or discoloration are minimized during the drying process and the production time of the product is remarkably shortened.

In the specification of the present invention, "veneer" refers to a wood plate thinly cut to a thickness of 7 mm or less as defined in KSF 1555 (Wood Standard Terminology-Wood Adhesion and Plywood).

The apparatus for heating and drying a single plate includes a chamber for accommodating a single plate, a magnetron for generating a microwave for drying the single plate accommodated in the chamber, and a control unit for controlling the entire heating and drying apparatus. The apparatus preferably includes a temperature sensor and a thermal imaging camera.

In the thermal distribution image shown in FIG. 2, the temperature range is from 30 to 100 DEG C, and the lower the color is, the higher the temperature is. The specimens with a lot of bright parts (veneer veneer) are close to the temperature distribution and the target temperature. That is, the more the bright part (yellow) is distributed in the flat plate and the roll type veneer, the better the heating.

In the heating and drying method, the heating step and the moisture content after heating are set (S1), and then the heating step and the quality confirmation step are carried out. In the heating step, the microwaves are generated in the magnetron, (S2). In the step of confirming the quality, step (S3) of measuring the decreasing rate of the function of the heated and dried veneer, and step (S4) of measuring the surface temperature distribution through the thermal image are performed.

In the step (S1) of setting the heating temperature of the single plate and the water content after heating, the heating temperature of the single plate is preferably 90 to 100 deg. C, and the water content after heating is suitably about 10 to 15%. The wood generally starts pyrolysis at about 100 ° C to 120 ° C, and then goes to carbonization as the internal fiber properties of the wood change. In general, heat drying is accompanied by an operation of raising the temperature of the interior of the wood up to 100 ° C to 200 ° C. Since a thin plate such as a single plate is very vulnerable to stress due to temperature rise, The temperature range was set at 90 ~ 100 ℃ so as not to damage the fiber as much as possible by raising the temperature only at the minimum temperature and before the pyrolysis stage of the wood.

In addition, the wood for industrial use must reach the equilibrium moisture content at or below the fiber saturation point, and the microwave heated wood can be adjusted within a short time to the desired water content by adjusting the output and heating time. On the other hand, the target value of the water content range after heating should be set so that the single plate which is in a state of fiber saturation or more in a functional state can be heated and dried in the shortest time without changing the quality. In order to ensure the initial quality of heating and drying, In the present invention, the water content after heating is set at 10 to 15%, and if the setting range is not reached or higher, the desired quality can not be secured. Therefore, the water content should be adjusted through additional heating.

A single plate having a thickness of 2 to 3 mm may be put into the chamber in the form of a flat plate or may be put into a chamber in the form of a roll. In the step (S2) of heating and drying the single piece, when the single piece is put into a flat state, it is most preferable to heat for 20 to 25 minutes at an output of 3 kW magnetron. It is most preferable to heat the single plate in a roll shape for 60 to 70 minutes at an output of 3 kW magnetron when the single plate is placed in the chamber.

In the step (S3) of measuring the decreasing rate of the function of the heated and dried veneer, the decreasing rate of the function is suitably about 50 to 60% by weight, and in the step (S4) of measuring the surface temperature distribution through the thermal image, A surface temperature distribution is preferably about 90 to 100 占 폚.

On the other hand, if the single plate is immersed in a liquid pigment or a preservative for refractory / antifouling after rapid heating by microwave, a large amount of chemical infiltration can be naturally accomplished. In recent years, there has been a demand for easier maintenance of wood products, which have been pointed out as problems in the past, by securing new functionality rather than requiring only basic functions of wood. For example, after immersing heated wood in a liquid flame retardant and drying it, it is easier and more efficient to maintain and maintain than the existing flame retardant. It minimizes damage by naturally permeating liquid pigment into the single plate, It is possible to develop a wide variety of products in color selection. It is possible to produce wood with various characteristics by immersing the wood in a hot state in liquid pigments and preservatives for a certain period of time.

It will be apparent to those skilled in the art that various modifications and variations can be made in the present invention without departing from the spirit or scope of the present invention. Various modifications and variations will be possible without departing from the spirit of the invention. Therefore, the scope of the present invention should be construed as being covered by the scope of the appended claims, and technical scope within the scope of equivalents thereof should be construed as being included in the scope of the present invention.

Claims

There is provided a method for heating and drying a single plate using microwave, the method comprising: a chamber accommodating a single plate; a magnetron generating a microwave for drying the single plate accommodated in the chamber; and a controller for controlling the entire heating and drying apparatus ,
In the drying and heating method,
Setting the heating temperature of the single plate and the water content after heating;
Generating microwaves in the magnetron to heat and dry the single plate inside the chamber;
Measuring a decreasing rate of the function of the end plate;
Measuring a surface temperature distribution through the thermal image;
And heating and drying the single plate using a microwave.

The method according to claim 1,
Wherein the end plate having a thickness of 2 to 3 mm is accommodated in the chamber in the form of a flat plate, the output of the magnetron is 3 kW, and the heating time is 20 to 25 minutes.

The method according to claim 1,
Wherein the end plate having a thickness of 2 to 3 mm is rolled into a chamber and the output of the magnetron is 3 kW and the heating time is 60 to 70 minutes.

The method according to claim 1,
Wherein the function decreasing rate is 50 to 60% by weight and the surface temperature distribution measured through thermal imaging is 90 to 100 占 폚.

The method according to claim 1,
Wherein the heating temperature of the single plate is from 90 to 100 캜 and the water content after heating is from 10 to 15%.

The method according to claim 1,
Heating the single plate, heating the single plate, and immersing the single plate in a liquid pigment or a preservative for refractory / antifouling.