JP2808444B1 - Wood drying equipment - Google Patents

Abstract

An object of the present invention is to dry large wood uniformly and efficiently in a short time using a microwave power source having a small microwave output. A wood drying apparatus includes a plurality of microwave power supplies, a plurality of antennas for emitting microwaves to a shield case, and a transfer conveyor for loading and unloading the wood. The shield case 2 is an elongated hollow cylindrical shape, and is made of a metal shield material so that microwaves do not leak. At the end of the shield case 2, an entrance 8 for the wood 1 is opened, and is closed by an opening / closing door 9 that does not leak microwaves. A plurality of antennas 4 are arranged on the upper part of the shield case 2 at a distance from each other in the direction in which the wood 1 is transported. The elongated wood 1 is heated and dried by microwaves radiated from each antenna 4. The transfer conveyor 6 is disposed at the bottom in the shield case 2 and floats the wood 1 from the bottom surface of the shield case 2 and scatters microwaves to uniformly heat the wood 1.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus for drying pillars and logs using microwaves.

[0002]

2. Description of the Related Art When wood is used in an undried state,
Various adverse effects such as a large deformation with time or a contraction to form a gap occur. This adverse effect can be effectively prevented by drying and using the wood. The most common method of drying wood is to leave the wood unattended, but this method has the disadvantage of being extremely time consuming. As a method of drying wood in a single time, a method of heating wood with steam or high frequency has been put to practical use. In the method of heating with steam, the wood is heated to 100 ° C. or more in order to boil and remove moisture contained in the wood in a short time. For this purpose, wood is put into a pressure tank and steam at 100 ° C. or higher is supplied. This method requires a pressure vessel in order to heat the wood to 100 ° C. or higher, and has a drawback that the equipment cost is extremely high. In addition, since the method of heating wood with steam conducts heat from the surface of the wood and heats it, it takes a considerable time to heat the wood to the inside, and it is difficult to dry the wood efficiently in a short time . In particular, pillars and logs are
It takes a long time to heat the central part and cannot be dried in a short time. Furthermore, this method also has the disadvantage that the surface shrinks and breaks easily because the wood is dried from the surface.

[0003] As a device for heating wood from the inside, wood is heated by sandwiching it between electrodes connected to a high-frequency electrode.
Drying equipment has been put to practical use. This device heats the wood with the high frequency loss of the wood placed between the electrodes. This apparatus can dry thin wood such as a plate material relatively efficiently, but has a drawback that it cannot efficiently heat wood such as pillars that are thicker in terms of surface area or round wood such as raw wood. This is because pillars and the like cannot be sandwiched between wide electrodes, and if a log is sandwiched between planar electrodes, wood cannot efficiently absorb high frequencies. Further, this device has a drawback that the ideal electrode shape and size differ depending on the shape and size of the wood to be dried, and it is difficult to dry various woods with the same device. In addition, there is also a problem that high-frequency waves are radiated to the surroundings between the electrodes as radio waves.

[0004] An apparatus for drying wood by irradiating it with microwaves has excellent features not found in an apparatus sandwiched between electrodes. In particular, this drying device has a feature that the wood is heated from the inside because the wood is heated and dried by absorbing the microwaves into the wood. Wood heated from the inside shrinks from the inside, so that cracks on the surface can be reduced. Further, since the inside which is difficult to heat is efficiently heated, there is a feature that the time for heating and drying can be remarkably reduced.

[0005] A drying apparatus using microwaves is described, for example, in Japanese Patent Application Laid-Open No. 60-178282. In the apparatus described in this publication, as shown in FIG. A part of the conveyor 3 is disposed in the shield case 2, and the shield case 2 irradiates microwaves to dry the wood 1.

[0006]

The wood drying apparatus shown in FIG. 1 can continuously dry wood by microwaves. This type of apparatus can also efficiently dry thin wood such as boards, but it is difficult to efficiently dry wood such as pillars and raw wood.
This is because, if the output of the microwave irradiating the shield case is increased, the radio wave leakage increases, resulting in an environment unfavorable for the operator.

In order to efficiently dry wood such as pillars in a short time, it is necessary to increase the output of microwaves radiated to the shield case. The present inventor has developed a device in which a plurality of antennas are arranged in a shield case and each antenna is connected to a microwave power supply in order to increase the microwave output of the shield case. This drying device
The advantage is that the output of one microwave power supply can be reduced to increase the total microwave output. This means
This is extremely important for microwave drying equipment. This is because the microwave power source generates microwaves in the magnetron. Magnetrons produce low output in large quantities at low cost. This is because it is often used for home microwave ovens and the like. However, if a high-power magnetron that can be used for drying wood is specifically designed, the manufacturing cost will increase dramatically. In particular, since the magnetron has a cavity that resonates at the frequency of the oscillating microwave, a specially designed high-output magnet has a disadvantage that the manufacturing cost is extremely high. Further, since the magnetron is a consumable whose performance deteriorates after being used for a certain period of time, it is very important that maintenance parts can be easily obtained in addition to being able to mass-produce at low cost.

If microwave outputs oscillated by a plurality of magnetrons can be collected by a waveguide, a large output microwave can be generated by using a plurality of small output magnetrons. However, it is extremely difficult to aggregate the outputs of the magnetrons and add the outputs. This is because it is difficult to make the phases of the microwaves oscillated by each magnetron uniform. For this reason, the inventor prototyped a drying device in which an antenna was connected to each magnetron.
This is because a plurality of antennas are arranged in a shield case and wood is heated by microwaves radiated from each antenna. However, this device has a problem that microwaves radiated from an adjacent antenna interfere with each other to make it difficult to uniformly heat the entire wood.

The present invention has been developed with the aim of further solving this drawback. An important object of the present invention is to use a microwave power source having a small microwave output to uniformly and efficiently use large wood. An object of the present invention is to provide a wood drying apparatus which can dry well in a short time.

[0010]

The wood drying apparatus of the present invention has the following unique structure to achieve the above-mentioned object. (A) The drying device includes a plurality of microwave power supplies 5 and a plurality of antennas 4 that are electrically connected to the respective microwave power supplies 5 through the waveguides 13 and emit microwaves to the shield case 2. And a transfer conveyor 6 disposed on the bottom surface of the shield case 2 for carrying the wood 1 into the shield case 2 and discharging the wood 1 from the shield case 2. (B) The shield case 2 is an elongated hollow cylindrical shape extended in the transport direction of the wood so that the wood 1 such as an elongated pillar or a log can be carried in. The shield case 2 is made of a metal shield material so that microwaves do not leak. ing. (C) At the end of the shield case 2, an entrance 8 through which the wood 1 enters and exits is opened. (D) The entrance 8 is closed in a state where it is electromagnetically shielded by a door 9 that does not leak microwaves. (E) A plurality of antennas 4 are disposed on the upper part of the shield case 2 at a distance from each other in the direction in which the wood 1 is transported. It is configured to dry. (F) The transfer conveyor 6 is arranged at the bottom in the shield case 2 and is configured to float the wood 1 from the bottom surface of the shield case 2 and scatter microwaves to uniformly heat the wood 1. I have.

Further, the wood drying apparatus according to the second aspect of the present invention is intended to dry the wood 1 more uniformly and efficiently.
In the state where microwaves are radiated from the antenna 4, the wood 1
The driving mechanism 15 for reciprocating the back and forth of the
Is provided. The transfer conveyor 6 of this structure carries the wood 1 into and out of the shield case 2, irradiates the wood 1 with microwaves more uniformly, and furthermore, irradiates the wood 1 with the microwave. The contact state is changed to dry uniformly.

[0012]

Embodiments of the present invention will be described below with reference to the drawings. However, the following examples illustrate a wood drying apparatus for embodying the technical idea of the present invention, and the present invention does not specify a drying apparatus as follows.

Further, in this specification, in order to make it easy to understand the claims, the numbers corresponding to the members shown in the embodiments will be referred to as “claims” and “ In the column of “means”. However, the members described in the claims are not limited to the members of the embodiments.

The wood drying apparatus shown in FIG. 2 includes a shield case 2 for carrying wood 1, an antenna 4 for irradiating the wood 1 in the shield case 2 with microwaves, and a microwave for supplying microwaves to the antenna 4. It has a power supply 5 and a transfer conveyor 6 arranged at the bottom of the shield case 2 for loading and unloading the wood 1.

The shield case 2 has an elongated hollow cylindrical shape extending in the transport direction of the wood 1 so that the elongated wood 1 such as a pillar or a raw wood can be carried in. Made of shield material. The shield case 2 shown in the figure has an elongated tubular shape by connecting a plurality of case units 7 in series. Case unit 7
Is a rectangular cylindrical shape having both ends open, and is connected so that microwaves do not leak, thereby forming a shield case 2. The shield case 2 having this structure includes a case unit 7
The total length can be easily changed by adjusting the number of connected. The total length of the pillars and logs to be dried is 3-8m. A device for drying short wood reduces the number of connected case units, and a device for drying long wood increases the number of connected case units.

The shield case 2 shown in FIG. The shield case 2 of this structure
The timber 1 is carried in from the entrance 8 at one end and the entrance 8 at the other end.
Since the wood 1 can be discharged from the container, the loading and discharging of the wood 1 can be performed efficiently. However, the shield case has an entrance only at one end, carries wood from one entrance,
Can also be discharged.

The shield case 2 is closed with an opening / closing door 9 for preventing microwaves from leaking to the outside in a state where the wood 1 is put in and microwaves are applied. The opening and closing door 9 is made of a metal plate such as a porous iron plate having a number of holes, which does not leak microwaves but is sufficiently smaller than the wavelength of the microwaves so that the state of the wood 1 inside can be observed. is there. A large number of small holes through which microwaves do not leak can also be provided on the side surface of the shield case in order to check the dry state of the wood from the outside. Shield case 2 manufactured by connecting a plurality of case units 7
At the entrance 8 of the case unit 7 connected to both ends,
The door 9 is connected.

The antenna 4 and the microwave power supply 5 are arranged above each case unit 7. The case unit 7 has a power supply room 10 in which the antenna 4 and the microwave power supply 5 are housed. Power supply room 10
The microwave power supply 5 housed in the power supply comprises a magnetron 11 for generating a microwave, and a power supply circuit 12 for supplying the magnetron 11 with a high-voltage direct current and an alternating current for heating the heater. The magnetron 11 is connected to the antenna 4 via the waveguide 13 and supplies a microwave to the antenna 4. The antenna 4 is opened downward in the power supply chamber 6 so as to irradiate the wood 1 in the shield case 2 with microwaves from above.

The antennas 4 provided in each case unit 2 irradiate the wood 1 with microwaves at regular intervals. Antenna 4 provided in each case unit 7
Although the microwaves radiated from are interfered with each other, they are reflected and diffused in the transfer conveyor 6 and the shield case 2, and
The long wood 1 is heated uniformly. The distance between the adjacent antennas 4 provided in the shield case 2 is determined in consideration of the output of the microwave radiated from the antenna 4, the thickness of the wood 1, and the required drying time. When the antenna output is increased by reducing the distance between the antennas, thick wood can be heated and dried in a short time. For example, an antenna that outputs a microwave of 500 W can dry wood having a size of 10 cm square by several tens of minutes with an interval between adjacent antennas being 30 to 50 cm.

As shown in the figure, a drying apparatus for connecting a plurality of case units 7 each containing an antenna 4 and a microwave power supply 5 to an upper power supply chamber 10 is a case unit for drying long wood. Increase the total microwave output. For this reason, a long wood drying apparatus can increase the microwave output, and a short wood drying apparatus can reduce the microwave. Therefore, there is a feature that the case units having the same structure can be connected to each other to dry in an ideal state from short wood to long wood. An apparatus for drying rectangular or cylindrical wood, such as pillars or raw wood, connects the case units in one vertical line. In a wide wood drying apparatus, case units are connected vertically and horizontally, that is, the case units are arranged in a plurality of rows on the same plane and connected so as to form a wide shield case. The partition wall at the boundary of the case units connected side by side is removed. For example, in a shield case in which case units are arranged side by side in three rows and connected, the partition walls on both sides of the central case unit are removed, and the partition walls inside the case units on both sides are removed. In this state, the case units connected in three rows have a hollow cylindrical shape, and have a shape capable of carrying wide wood.

The transfer conveyor 6 shown in FIGS. 2 and 3 is a roller conveyor, and is provided at the bottom of each case unit 7.
A plurality of rollers 14 are mounted so as to be rotatable via metal bearings. The roller 14 is mounted on the case unit 7 horizontally and in parallel. Roller 1
Reference numeral 4 indicates that the rotating shaft 16 projects outside the case in order to connect to the drive mechanism 15. The drive mechanism 15 that rotates the roller 14 includes a reversible speed reduction motor 17. The reduction motor 17 is connected to the rotation shaft 16 of the roller 14 via a chain 18 and a sprocket 19. The drive mechanism 15 rotates the deceleration motor 17 to rotate all the rollers 14 in the same direction. The deceleration motor 17 is rotated forward when the wood 1 is carried into the shield case 2 and when the wood 1 is discharged from the shield case 2. The deceleration motor 17, which is rotated forward, carries in the wood 1 and
Alternatively, the roller 14 is rotated in the discharging direction.

Further, the deceleration motor 17 closes the shield case 2 and irradiates the wood with microwaves.
The wood is reciprocated by rotating the roller 14 in the forward and reverse directions. The stroke for reciprocating the wood is, for example, in the range of 1/5 to 1 of the interval between adjacent antennas. In addition, the speed at which the wood is reciprocated need not be so high. For example, the wood is reciprocated at a speed in which one stroke of one reciprocation takes 5 seconds to 2 minutes.

In the apparatus shown in the figure, the driving mechanism 15 is connected to the roller conveyor, but the drying apparatus of the present invention does not necessarily need to connect the driving mechanism to the roller conveyor. This is because a roller conveyor without a driving mechanism can push wood into a shield case and push out or pull out dried wood from the shield case.

Further, in the drying apparatus shown in the figure, a roller conveyor is used as a transfer conveyor, but a belt conveyor or a chain conveyor can be used as the transfer conveyor.

[0025]

The wood drying apparatus of the present invention has a feature that large wood can be dried uniformly and efficiently in a short time. That is, the wood drying apparatus of the present invention is provided with a plurality of microwave power supplies and antennas, and a plurality of antennas are arranged in a long and narrow hollow cylindrical shield case, separated in a wood transfer direction, and each of the antennas is provided. This is because the elongated wood is heated and dried by microwaves radiated from the antenna. The wood drying apparatus of this structure uses a plurality of microwave power sources and uniformly irradiates the elongated wood with microwaves from a plurality of antennas arranged apart in the direction of transport of the wood. Therefore, there is a feature that even large wood can be efficiently dried in a short time.

Further, the wood drying apparatus of the present invention has a feature that wood can be dried by using a microwave power source having a small microwave output as a plurality of microwave power sources. As the drying device, a microwave power source having a small microwave output and mass-produced inexpensively can be used. Therefore, this device can reduce the manufacturing cost and
The feature is that maintenance parts can be easily obtained. In addition, this drying apparatus has a feature that, although the output of the microwave radiated from the microwave power source is reduced, the whole microwave output is increased and the long wood can be efficiently dried. This is because when drying long wood, the number of microwave power supplies and antennas can be increased to increase the total microwave output. As described above, the drying apparatus of the present invention that can reduce the microwave output of the microwave power supply also has a feature that the radio wave leakage is reduced and the operator can use it safely.

[0027] Further, the wood drying apparatus of the present invention comprises:
The feature is that microwaves can be diffused and the whole wood can be heated uniformly. This is because the drying apparatus of the present invention holds the wood so as to float from the bottom by the transfer conveyor disposed at the bottom of the shield case. In the wood held in this state, the irradiated microwave is reflected and diffused on the inner surface of the shield case and the transfer conveyor, and is irradiated on the entire surface including the bottom surface. Moreover, the emitted microwaves interfere with each other, but are reflected and diffused, so that the wood is uniformly irradiated. Therefore, the drying device of the present invention has a feature that the whole long wood can be uniformly heated and dried.

Further, the wood drying apparatus according to the second aspect has a feature that the wood can be carried in and out of the shield case, and the wood can be uniformly irradiated with microwaves and dried. That is, the transfer conveyor of the drying device has a drive mechanism for transporting wood, and with this drive mechanism,
This is because the wood can reciprocate back and forth. This device is
In the state where microwaves are radiated from the antenna, the wood that is carried in is reciprocated by the drive mechanism, so that the microwaves can be uniformly radiated on the surface of the wood without unevenness. In addition, the reciprocating wood changes its contact state with the transfer conveyor, so that the bottom surface of the wood can be evenly irradiated with the microwave without unevenness. Therefore, the wood drying apparatus of the present invention can realize the feature that the wood can be heated and dried efficiently in a short time and efficiently.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of a conventional drying apparatus using microwaves.

FIG. 2 is a schematic sectional view of an apparatus for drying wood according to an embodiment of the present invention.

FIG. 3 is a plan view of a transfer conveyor of the wood drying apparatus shown in FIG. 2;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Wood 2 ... Shield case 3 ... Conveyor 4 ... Antenna 5 ... Microwave power supply 6 ... Transfer conveyor 7 ... Case unit 8 ... Doorway 9 ... Opening / closing door 10 ... Power supply room 11 ... Magnetron 12 ... Power supply circuit 13 ... Waveguide 14 ... Roller 15 ... Drive mechanism 16 ... Rotating shaft 17 ... Deceleration motor 18 ... Chain 19 ... Sprocket

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-2-49120 (JP, A) JP-A-50-22342 (JP, A) JP-A-1-212886 (JP, A) JP-A-2- 89986 (JP, A) JP-A-59-125374 (JP, A) JP-A-49-45451 (JP, A) JP-A-4-100592 (JP, U) JP-A-2-44689 (JP, U) 48-103942 (JP, U) (58) Field surveyed (Int. Cl. ⁶ , DB name) F26B 3/347 F26B 9/06 F26B 15/12

Claims (2)

(57) [Claims] An apparatus for drying wood having all of the following configurations. (A) Wood drying equipment is equipped with multiple microwave power sources (5)
And a plurality of antennas (4) that are electrically connected to the respective microwave power supplies (5) and emit microwaves to the shield case (2), and are disposed on the bottom surface of the shield case (2), Transfer conveyor (6) for loading and unloading wood (1)
And (B) The shield case (2) is an elongated hollow cylinder extending in the transport direction of the elongated wood (1), and is made of a metal shield material so that microwaves do not leak. (C) At the end of the shield case (2), an entrance (8) through which wood (1) enters and exits is opened. (D) The doorway (8) is a microwave-tight door (9)
To close the electromagnetic shield. (E) In the shield case (2), a plurality of antennas (4) are arranged on the upper part of the shield case (2) apart from each other in the transport direction of the wood (1), and the microwaves radiated from each antenna (4) are used. It is configured to heat and dry the elongated wood (1). (F) The transfer conveyor (6) is disposed at the bottom inside the shield case (2), and floats the wood (1) from the bottom surface of the shield case (2) and scatters microwaves to remove the wood.
(1) is configured to be uniformly heated. 2. A driving mechanism (1) for reciprocating wood (1) back and forth in a state where microwaves are emitted from an antenna (4).
The wood drying apparatus according to claim 1, wherein the transfer conveyor (6) includes the step (5).