JPS6345664Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Field of Application] This invention relates to a press dryer for board materials that can dry the board materials in a stacked state.

[Conventional technology and its issues] Conventional wood dryers, in which wood is carried into a drying chamber and stacked with a certain gap between them, or dryers in which the wood is moved within the drying chamber using a conveyor, require a large space; Moreover, a large amount of thermal energy is consumed to heat materials other than wood, resulting in a large amount of energy loss. Furthermore, in the dryer currently most commonly used in plywood manufacturing factories, loaded veneers are inserted one by one into the dryer, and then stacked again after drying. This dryer dries the wood by heating it from the surface with infrared rays or hot air. The veneer dried by this device has significant drying spots at the edges and center, which causes distortion of the veneer. Furthermore, it had the disadvantage of shrinking somewhat after drying and causing loss of weight. This drawback can be overcome by sandwiching the veneer between a plurality of hot plates and drying it.

However, since the hot plate dryer inserts the veneer between the hot plates of each stage, it takes time and effort to put in and take out the plates, resulting in poor productivity. Furthermore, when increasing the number of stacked hot plates in order to increase productivity, the veneers stacked on the lower level were pressed strongly by the weight of the upper hot plate, resulting in loss of thickness and uneven thickness after drying. .

By the way, by sandwiching multiple plates between plate-shaped electrodes,
A device for heating and drying a plate by radiating high frequency power between electrodes has already been developed (Japanese Patent Publication No. 1834/1983). Devices with this structure have the advantage of being able to heat wood from the inside, and are often used for wood drying.

However, in a drying device with this structure, there is a gap between the electrodes.
Since the wood is usually heated by applying alternating current of 5 to 30 MHz (wavelength: 10 to 60 meters), electrodes are required to sandwich the wood and apply a high-frequency electric field. The electrodes do not simply sandwich the wood mechanically, but because high-frequency power is applied between the two electrodes, they must be insulated from each other. Further, a feeder line for supplying high frequency power is connected to the electrode. The feeder wire that supplies high-power high-frequency power to the electrodes is thick and cannot be easily connected to the electrodes that move up and down. Further, the connection portion between the electrode and the feeder wire must be connected in such a manner that their impedances are matched in order to increase power transfer efficiency. Therefore, the electrode mounting structure and the structure of the power supply part become complicated. Furthermore, in order to efficiently radiate radio waves between the electrodes, it is necessary to match the impedance between the electrodes sandwiching the wood to the high frequency power source. However, the impedance between the electrodes varies depending on the moisture content of the wood sandwiched between the electrodes, the number of stacked wood layers, and the total thickness of the stacked wood. Therefore, it is necessary to constantly adjust the impedance between the electrodes so that the high-frequency power is efficiently radiated, and the adjustment is extremely time-consuming. It is also necessary to adjust the matching circuit as the wood dries. In actual use, the electrodes are not always aligned. Therefore, the mismatching of the electrodes reduces the efficiency of electric power use, making it impossible to heat and dry wood efficiently at all times.

A device for drying wood by irradiating microwaves inside a pressure-resistant container has been developed (Japanese Patent Laid-Open Publication No. 77361/1983). Although this device can simply dry wood, it cannot dry planks without distortion.

[Purpose of this invention] This invention was developed with the aim of eliminating these drawbacks of conventional drying equipment.
The important purpose of this invention is that even though it is possible to dry a large amount of wood at once by stacking it, the lower veneer is not pressed too hard and wears out, and the wood can be kept under pressure while being stacked. Work efficiency is high as it can be carried into the board and taken out as it is after drying.Furthermore, since the wood is dried in a laminated press state, it is possible to minimize distortions, cracks, and loss of area after drying. Since the air inside the closed casing is exhausted and dried, the moisture in the wood is smoothly evaporated, and the moisture in the wood is selectively heated and other parts are not dried as much, resulting in high energy usage efficiency. Can dry quickly
Furthermore, it is an object of the present invention to provide a press dryer for board materials that can efficiently dry a large amount of wood with a small device by drying the wood in a dense manner while stacking the wood.

[Means for achieving the object] The board press dryer of this invention includes a platform 3 on which a plurality of stacked boards 1 are placed, and a pressurizer that presses the boards 1 on this platform 3 from above. Surface plate 4
, a cylinder 5 whose lower end is connected to this pressure surface plate 4 and drives the pressure surface plate 4, and this cylinder 5.
A closed chamber 14 is formed which surrounds the plate material 1 sandwiched between the upper frame 9 to which is fixed, the mounting table 3 and the pressure platen 4 in a sealed or almost sealed state, and
A casing 2 that partially can be opened and closed, an exhaust means 6 for exhausting the air inside the casing 2, and a microwave means 7 for irradiating the inside of the casing 2 with microwaves.
It is equipped with

The lower end of the casing 2 is connected to the platform 3, and the upper end is connected to the upper frame 9. The platform 3 and the upper frame 9 are used together as a part of the casing 2,
A closed chamber 14 is formed by the casing 2, the platform 3, and the upper frame 9.

A cylinder 5 is vertically connected below the upper frame 9.

The cylinder 5 and the pressure platen 4 are disposed within the closed chamber 14, and the pressure platen 4 is disposed so as to be vertically movable within the closed chamber 14.

[Preferred Embodiment] Hereinafter, an embodiment of this invention will be described based on the drawings.

The dryer shown in the figure includes a casing 2 that can be opened and closed so that board materials 1 can be carried in and out while stacked, and inside this casing 2,
A platform 3 on which the stacked plate materials 1 are placed, a pressure surface plate 4 that presses the plate materials 1 on this platform 3, a cylinder 5 that presses the pressure surface plate 4, and a casing 2.
It consists of an exhaust means 6 that exhausts moisture vaporized inside the casing 2 together with air, and a microwave means 7 that irradiates microwaves into the casing 2 to heat the plate material.

The casing 2 is provided with an opening/closing door 8 below the elevated pressure platen 4 at a position where the stacked plates 1 can be taken in and out.When the opening/closing door 8 is closed, the inside of the casing 2 is lowered from atmospheric pressure. The pressure is also reduced so that the moisture in the plate material 1 can evaporate smoothly.
Can be sealed or almost completely sealed.

This casing 2 prevents microwaves from leaking out of the casing. Therefore, a metal plate that can block the transmission of microwaves is used.

The casing 2 in the figure has its lower end on the outer periphery of the platform 3,
The upper end is fixed to the upper frame 9, and the platform 3, the upper frame 9, and the casing 2 form a closed chamber.

The pressure surface plate 4 is horizontally connected to the lower end of a rod of a cylinder 5 vertically fixed to the lower end of the upper frame 9, and both the pressure surface plate 4 and the cylinder 5 are arranged in a closed chamber. .

The upper surface of the mounting table 3 and the lower surface of the pressure surface plate 4 are provided with microwave interference prevention plates to prevent microwaves from being reflected there and causing radio waves to interfere in the vicinity and cause heating spots on the plate material 1. 10 are stretched.

For the interference prevention plate 10, a plate material such as a synthetic resin plate can be used, which has heat resistance and pressure resistance, does not reflect microwaves on its surface, and preferably does not itself absorb microwaves. Interference prevention plate 1
The thickness of 0 is preferably formed to be thicker than the wavelength of the microwave.

The cylinder 5 pushes down the pressing surface plate 4 and presses the laminated plate materials 1. The pressing pressure is preferably about 0.5 to 3 kg/cm ² so that the plate material 1 does not go awry during drying and its area is small and does not shrink. The press pressure is adjusted depending on the thickness of the plate 1, and the thinner the plate 1, the lower the pressure.

The exhaust means 6 exhausts the humid air inside the casing 2, and the inside of the casing 2 is, for example, 300 to 740 mm.
Hold at a pressure of Hg. A pressurized fan or vacuum pump can be used for this.

The microwave means 7 uniformly irradiates the inside of the casing 2 with microwaves. The microwave means are connected to the casing 2 via a waveguide 11, the waveguide 1
1 has a rotating blade 12 for radio wave diffusion.
is provided. Further, the open end of the waveguide 11 is sealed with a synthetic resin plate 13, such as polyethylene or fluororesin, which allows microwaves to pass through but does not allow air to pass through.

The penetration depth of microwaves into wood changes depending on the wavelength. Microwaves with longer wavelengths penetrate deeper into wood. Therefore, when the plate material is thick and the number of layers is large, microwaves with a long wavelength are optimal.

Microwaves selectively heat the moisture in the wood. The heated moisture is vaporized and removed from the wood. Microwave transmission loss decreases in the portion from which water is removed. Therefore, as moisture is removed from the surface of the board, the microwave is transmitted to the interior with a small amount of attenuation, penetrates deep into the wood, and heats the wood inside the board.

[Effects of this invention] In the press dryer for plate materials according to this invention, the mounting table and the upper frame are used together as a part of the casing, the mounting table, the upper frame, and the casing form a closed chamber, and the closed chamber A cylinder and a pressure surface plate are arranged inside the cylinder. By the way, the casing is provided to exhaust moisture coming out of the plate material and to prevent radio waves from leaking to the outside. Therefore, in the casing, it is usually sufficient to close only the portion where the plate material is sandwiched between the pressurizing surface plate and the mounting table. However, in the press dryer of this invention, the upper frame, mounting base, and casing form a closed chamber that is significantly larger than the sandwiched portion of the plate material, and the cylinder and pressure surface plate are placed inside this closed chamber. Built-in. In a press dryer with this structure, the pressure platen can freely move up and down within the closed chamber without contacting the casing, and even if the pressure platen is in any moving position,
The closed room is radio wave shielded and can reliably prevent radio waves from leaking outside. If a dryer that heats board materials through air has a large closed chamber, the members in this area will be heated, resulting in a significant drop in overall thermal efficiency. However, the advantage of this dryer using microwaves is that even though the closed chamber is extremely large, the microwaves irradiated into the closed chamber can be used efficiently to heat the plate material. . In other words, microwaves are not absorbed by air or metal, but are reflected by metal surfaces.
It is absorbed only by the board material containing moisture, selectively heating and drying the board material. Therefore, no matter how large the closed chamber is, since there is no microwave absorber inside, the irradiated microwaves can be effectively used for heating the plate material.

Furthermore, the upper part of the pressure platen has a complicated shape due to the cylinder and its mounting part, which has the effect of diffusing microwaves. The microwaves diffused above the pressure surface plate are uniformly radiated onto the plate material, and have the effect of uniformly and evenly heating and drying the entire plate material.

The pressurizing surface plate installed in the large closed room has the advantage that by raising it, it is possible to easily and easily carry in and take out plate materials, making it extremely convenient and efficient to use.

In addition, unlike high-frequency heating dryers that sandwich the plate material between electrodes, there is no need for electrodes that sandwich the plate material and emit electromagnetic waves, and the plate material can be irradiated with microwaves with a simple structure of connecting a waveguide to a closed chamber. .

Further, the press dryer for plate materials according to this invention can press and dry a plurality of plate materials while stacking them. For this reason, even though a large amount of wood can be dried at once, and the boards can be dried without cracking, warping, or shrinking, the boards can be directly stacked without being sandwiched between heavy plates such as hot plates. Since it can be dried, the lower board material will not be damaged by being pressed strongly with a heavy hot plate.
Furthermore, since a large number of plates are sandwiched between the pressing surface plate and the mounting table, the mechanism of the press part can be made extremely simple.

Furthermore, the planks were delivered in a stacked state,
Since it can be carried out, the supply and removal of plate materials can be reduced to a fraction of the conventional amount, and the work efficiency of this process can be significantly improved.

Furthermore, since the plate material is heated by microwaves inside the casing, which is closed and air is exhausted,
The moisture in the wood is smoothly evaporated and exhausted, allowing the wood to dry efficiently.Moreover, the moisture in the wood is selectively heated by microwaves, resulting in high energy usage efficiency and rapid drying. Since many plates can be stacked closely between the pressurized surface plates, it has many advantages, such as making the whole compact and increasing processing capacity.

[Brief explanation of the drawing]

The figure is a cross-sectional view of a press drying device for plate material showing an embodiment of this invention. 1... Plate material, 2... Casing, 3... Mounting stand,
4... Pressure surface plate, 5... Cylinder, 6... Exhaust means, 7... Microwave means, 8... Opening/closing door, 9
...Top frame, 10...Interference prevention plate, 11...
Waveguide, 12... Rotating blade, 13... Synthetic resin plate, 14... Closed chamber.

Claims (1)

[Claims for Utility Model Registration] (1) A platform 3 on which a plurality of laminated plates 1 are placed, a pressurizing surface plate 4 that presses the plates 1 on the platform 3 from above, and this pressurizing table 4. A cylinder 5 whose lower end is connected to the surface plate 4 and drives the pressure surface plate 4
A closed chamber 14 is formed which surrounds the plate material 1 sandwiched between the upper frame 9 to which the cylinder 5 is fixed, the platform 3 and the pressure platen 4 in a sealed or almost sealed state, It also includes a casing 2, a part of which can be opened and closed, an exhaust means 6 for exhausting the air inside the casing 2, and a microwave means 7 for irradiating microwaves into the casing 2. Each member is as follows. It is placed in the position of . The lower end of the casing 2 is connected to the platform 3,
The upper end is connected to the upper frame 9. The platform 3 and the upper frame 9 are used together as part of the casing 2, and the casing 2, the platform 3, and the upper frame 9 form a closed chamber 14. A cylinder 5 is vertically connected below the upper frame 9. The cylinder 5 and the pressure platen 4 form a closed chamber 14
The pressurizing surface plate 4 is located inside the closed chamber 1.
It is arranged so that it can freely move up and down within 4. (2) A microwave interference prevention plate 1 that does not reflect microwaves is placed on the bottom surface of the pressure platen 4 and on the top surface of the mounting table 3.
0. A press dryer for plate materials according to claim 1, which has a utility model registration of 0.