JPH09286668A - Batch heat treatment furnace - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent binder components from being accumulated in the space between the furnace body and the table, etc., by forming a gas introducing passage for introducing a gas into a heating chamber, in the space between a furnace body and the periphery of a table on which an object to be treated is placed. SOLUTION: In this furnace, plural spiral heaters 4 are concentric-circularly arranged in a heating chamber 3 formed inside a furnace body 1 having an open bottom and atmospheric gas supply pipes 6 are arranged concentrically with the heaters 4. A table 10 which has a step section 11 in the peripheral part and is vertically movable, is placed at the bottom of the heating chamber 3 and a ceramic plate 12 for supporting a case in which an object to be treated is received, is horizontally supported on the table 10 through a support 13. Also, a gas introducing passage 18 for introducing the same kind of gas as the atmospheric gas is formed in the space C between the furnace body 1 and each of the horizontal surface 11a and vertical surface 11b of the step section 11. Further, the outer peripheral surface of the furnace body 1 is covered with an inside frame 20 and an outside frame 21 and an air chamber 22 having a discharge port 22a in the upper part and an air supply section 23 in the lower part is formed in the space between the inside frame 20 and the outside frame 21.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a batch type heat treatment furnace suitable for heat treatment (degreasing, main firing, etc.) of ceramic products such as ceramic capacitors.

[0002]

2. Description of the Related Art Conventionally, a batch type heat treatment furnace has a heating chamber formed by arranging a rod-shaped or U-shaped heater inside a box-shaped or cylindrical furnace body, and the heating chamber is lifted to the bottom of the heating chamber. Possible tables are arranged. The box containing the ceramic product is placed on this table, and the table is raised to house the box in the heating chamber. Heat treatment in this state,
When the treatment is completed, the table can be lowered and the box can be taken out of the heat treatment furnace.

[0003]

By the way, when the degreasing and the main firing of the ceramic product are continuously performed by using the batch type heat treatment furnace as described above, the treatment of the organic binder generated during the degreasing becomes a problem. In particular, since the binder decomposition gas is heavier than air, it flows to the lower part of the heating chamber. Although there is a narrow gap between the outer periphery of the table and the furnace body, the temperature of this gap is 100 ° C. or less even during the main firing.
The binder decomposition gas that once flowed into the gap was liquefied or solidified and accumulated in the form of tar, which was the source of the bad odor. The furnace wall and table are made of felt-like heat insulating material.Binder decomposition gas penetrates into this heat insulating material, and the infiltrated binder component is carbonized by thermal decomposition etc., resulting in deterioration of heat insulation performance and leakage of electricity. There was a risk that problems such as

Accordingly, an object of the present invention is to provide a batch type heat treatment furnace which can prevent the binder component from accumulating in a gap or the like between a table and a furnace body.

[0005]

In order to achieve the above object, the present invention has a heating chamber in which a heater is arranged inside a furnace body, and an object to be processed is placed on the bottom of the heating chamber. In a batch type heat treatment furnace in which a table capable of moving up and down is arranged, a gas introduction passage for introducing a gas of the same kind as the atmosphere gas in the furnace is provided in the heating chamber through a gap between the outer peripheral portion of the table and the furnace body. .

[0006] The binder decomposition gas generated in the heating chamber flows downward and tries to flow into the gap between the table and the furnace body. However, since a gas of the same kind as the furnace atmosphere gas is introduced from this gap toward the heating chamber, this gas prevents the binder decomposition gas from flowing into the gap and prevents the binder component from accumulating in the gap. . Further, since the binder decomposition gas near the inner wall of the heating chamber is stirred by the flow of the inflow gas, it is possible to suppress the binder component from adhering to and penetrating into the heat insulator of the furnace body and the table.

Since the introduced gas is the same kind of gas as the atmosphere gas in the furnace, there is no fear of disturbing the atmosphere in the furnace. In addition,
In the case of a batch type heat treatment furnace in which the degreasing step and the main firing step are continuously performed, the introduction of the gas is only the degreasing step, and the introduction of the gas may be stopped in the main firing step.

In the above heat treatment furnace, a step portion is formed on the outer peripheral portion of the table, a gas of the same kind as the atmospheric gas is introduced from the outside to the inside along the horizontal surface of the step portion, and then along the vertical surface of the step portion. It is desirable to let it flow upward and introduce it into the heating chamber. In this case, since the gas introduction passage is bent, it is possible to reduce the escape of heat in the heating chamber, and it is less likely that the gas is preheated while passing through this passage and the temperature inside the furnace is lowered.

An annular gas introduction chamber having a plurality of blow-out openings in the inner circumference is formed on the outer peripheral portion of the furnace body, and the gas flowing into the gas introduction chamber is laid along the horizontal surface of the step portion from the blow-out opening. It is desirable to blow it out almost uniformly toward the inside. In this case, after the gas blown out from the outlet flows evenly along the horizontal surface of the step,
Since gas blows out from the gap between the outer peripheral portion of the table and the furnace body like an air curtain, uneven distribution of binder components can be eliminated.

[0010]

1 to 3 show an example of a batch heat treatment furnace according to the present invention. This heat treatment furnace includes a cylindrical furnace body 1 having an open bottom, and the furnace body 1 is composed of a heat insulating material 2 made of ceramic brick, felt or the like. A heating chamber 3 is formed inside the furnace body 1, and a plurality of spiral heaters 4 are concentrically arranged in the heating chamber 3. The spiral heater 4 penetrates the ceiling portion of the furnace body 1 and is inserted into the heating chamber 3 from above. The outer periphery of the spiral heater 4 is covered with a heat resistant insulating tube 5 except for the terminal portion 4a. The material of the tube 5 is preferably a dense alumina-based or silica-based ceramic that does not penetrate the binder component. Tube 5
Since the lower end opening is closed at the bottom of the furnace body 1, binder decomposition gas generated in the heating chamber 3 does not flow into the inside thereof.

A gas supply pipe 6 is arranged in the heating chamber 3 concentrically with the spiral heater 4, and the supply pipe 6 also penetrates the ceiling portion of the furnace body 1 and is inserted into the heating chamber 3. An atmosphere gas suitable for the degreasing process and the main firing process is supplied to the supply pipe 6 from a gas supply source (not shown), and the atmosphere gas is blown out from the outlet 6a toward the center of the heating chamber 3. An exhaust pipe 7 for exhausting the gas in the heating chamber 3 is attached to the top of the furnace body 1, and the exhaust pipe 7 is connected to an exhaust gas treatment device (not shown).

At the bottom of the heating chamber 3, a table 10 having a step portion 11 on the outer circumference is arranged. The table 10 is made of the same heat insulating material as the furnace body 1. Table 10
A ceramic plate 12 for supporting a box 19 containing an object to be processed such as a ceramic molded body
Are horizontally supported by the columns 13 while being floated from the upper surface of the table 10. A rotary shaft 15 of a motor 14 is connected to the center of the lower surface of the table 10, and a mounting plate 16 of the motor 14 is driven up and down by a lifting device 17 such as a hydraulic cylinder. Therefore, the table 10 is
The motor 14 is driven to rotate, and the lifting device 17 drives it up and down. Table 1
The reason why 0 is rotated is to heat the object to be processed uniformly by the heaters 4 arranged around it and to allow the object to be processed to come into contact with the atmospheric gas evenly.

The step portion 11 provided on the outer peripheral portion of the table 10 has a horizontal surface 11a and a vertical surface 11b. These surfaces 11a and 11b are close to the furnace body 1 and the step portion 11 and the furnace body 1 are provided. A gas introduction passage 18 (see FIG. 3) is formed between the and. Then, a gap C for blowing gas into the heating chamber 3 is formed between the vertical surface 11b and the furnace body 1.

The outer peripheral surface of the furnace body 1 is covered with an inner frame 20 made of metal, and the outer periphery of the inner frame 20 is covered with an outer frame 21 at regular intervals (for example, 20 to 30 cm). Therefore, both frames 20, 21
A cylindrical air chamber 22 is formed between them. A discharge port 22a opening upward from the furnace body 1 is formed in the upper part of the air chamber 22, and an annular air supply part 23 is provided in the lower part.
The air inlet 2 is supplied to the supply unit 23 from an air supply source (not shown).
Air is supplied via 3a, and the air is supplied to the air chamber 22 from a plurality of outlets 23b formed on the upper wall of the supply unit 23 at equal pitch intervals. Therefore, the air that has entered the air chamber 22 flows from the lower side to the upper side, and the outlet 22a
Emitted from.

An annular gas introduction chamber 24 is formed in the lower part of the air supply unit 23.
The gas introduction chamber 24 and the gas introduction chamber 24 are partitioned by a partition plate 25 that also serves as a support plate that supports the bottom surface of the furnace body 1. The same gas as the atmospheric gas supplied to the gas supply pipe 6 is supplied to the gas introduction chamber 24 from the inflow port 24a, and is blown toward the inner center direction from a plurality of outlets 24b formed at equal intervals on the inner wall. It This gas is used in the gas introduction passage 1
It is introduced into the heating chamber 3 through 8. That is, as shown in FIG. 3, the gas is the horizontal surface 11 of the step portion 11 of the table 10.
After being introduced from the outer side to the inner side along a, it flows upward along the vertical surface 11b of the stepped portion 11 and blows upward into the heating chamber 3 in a cylindrical shape and uniformly. The hole diameter and number of the blowout ports 24b vary depending on the volume inside the furnace and the amount of gas input, but the flow velocity of the gas flowing through the gas introduction passage 18 is 50 cm.
It is sufficient to select it to be about 1 m / sec.

Next, the operation of the heat treatment furnace having the above structure will be described. First, the table 10 is lowered by the elevating device 17, a plurality of boxes 19 are stacked and placed on the table 10, and then the table 10 is raised to house the boxes 19 in the heating chamber 3.

Next, the table 10 is rotated in a fixed direction by the motor 14, the heater 4 is energized to heat the heating chamber 3 to a predetermined temperature, and at the same time, the atmospheric gas is supplied to the heating chamber 3 from the gas supply pipe 6. Degrease. In this degreasing step, the decomposition gas of the organic binder is generated from the ceramic molded body which is the object to be treated, and this gas is heavier than the atmospheric gas, and therefore tends to accumulate at the bottom of the heating chamber 3. At this time, by introducing the same gas as the atmospheric gas into the heating chamber 3 from the gas introduction chamber 24 through the gas introduction passage 18,
Gas can be evenly blown out through the gap C between the table 10 and the furnace body 1, and the binder decomposition gas can be prevented from flowing into the gap C. Moreover, since this gas generates an air flow near the inner wall of the heating chamber 3 and around the table 10, it is possible to prevent the binder decomposition gas from penetrating into the heat insulating material of the furnace body 1 and the table 10. The exhaust gas generated in the heating chamber 3 is discharged from the exhaust pipe 7 at the top.

After the degreasing treatment is completed, a main firing treatment is subsequently performed. That is, the supply of the atmospheric gas from the gas supply pipe 6 and the gas introduction passage 18 is stopped, the temperature of the heater 4 is raised, and the object to be measured is main-baked. At this time, the binder component remaining in the heating chamber 3 is completely decomposed by heat.
Since the amount of the binder component adhering to the clearance C between 0 and the furnace body 1 or the inner wall of the furnace body 1 is small, it is possible to prevent deterioration of the heat insulating material and suppress contamination of the furnace body 1.

By the way, an air chamber 22 is provided in the outer peripheral portion of the furnace body 1.
Are formed. In the temperature raising process, the air chamber 22 is used as a kind of heat insulating layer by stopping the supply of air to the air chamber 22. Thereby, the thickness of the heat insulating material 2 can be reduced, and the furnace body 1 can be downsized. In the cooling process, air is supplied from the outlet 23b of the air supply unit 23 to the air chamber 22 and discharged from the outlet 22a, so that the heat stored in the air chamber 22 can be removed at once.
The cooling time of the furnace body 1 can be shortened.

The present invention is not limited to the above embodiment. For example, the shape of the furnace body of the present invention is not limited to the cylindrical shape.
The table used in the present invention is not limited to a rotating turntable, but may be a table that only moves up and down. Therefore, the shape of the table is not limited to the disk shape. Further, it is not limited to the case where the outer peripheral portion of the table has a step, and a cylindrical table may be used. In this case, the gas supply passage is a passage that extends linearly from below to above.

In the above embodiment, the atmosphere gas supply pipe and the gas introduction passage are provided separately, but it is also possible to omit the supply pipe and substitute the gas introduction passage. However, since the gas introduction passage is for generating a gas flow on the table, it is necessary to provide a gas supply pipe to introduce the atmospheric gas into the box. When a gas supply pipe is used in place of the gas introduction passage, it is desirable to use an object without a box as the object to be treated. Further, although the exhaust pipe for discharging the exhaust gas is provided at the top of the heating chamber, it may be provided at the side.

The heaters are arranged concentrically and vertically with respect to the furnace body, but when the furnace body is quadrangular, they may be arranged horizontally. The heater is not limited to the spiral heater, and may be a rod-shaped heater or a U-shaped heater. In the case of a rod-shaped heater, the terminal portions should come to both ends. Since the spiral heater has a terminal portion on one side and is rod-shaped for the reason that it is necessary to make the shape oval, the cylindrical heater can be used, and therefore the arrangement is simple and the cost is low. As the heat-resistant insulating tube, it is desirable to use a dense, non-conductive, alumina-based or silica-based ceramic tube that does not penetrate the binder component.

[0023]

As is apparent from the above description, according to the present invention, the gas introduction passage for introducing the same kind of gas as the atmosphere gas in the furnace is introduced into the heating chamber through the gap between the outer peripheral portion of the table and the furnace body. Since the gas is blown out from the gas introduction passage, the binder decomposition gas is prevented from flowing into the gap between the table and the furnace body, and the binder component can be prevented from accumulating in the gap. Further, since the binder decomposition gas near the inner wall of the heating chamber is agitated by the flow of the inflowing gas,
It is possible to prevent the binder component from adhering to and permeating into the heat insulating material of the table and the furnace body.

[Brief description of drawings]

FIG. 1 is a sectional view of a batch type heat treatment furnace according to the present invention.

FIG. 2 is a sectional view taken along line AA of FIG.

FIG. 3 is an enlarged view of a portion B in FIG. 1;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 furnace body 3 heating chamber 4 heater 10 table 11 stepped portion 14 motor 17 lifting device 18 gas introduction passage 19 box 24 gas introduction chamber 24b outlet C

Claims (3)

[Claims] 1. A batch type heat treatment furnace having a heating chamber in which a heater is disposed inside a furnace body, and a vertically movable table for placing an object to be processed is disposed at the bottom of the heating chamber. From the gap between the outer periphery of the and the furnace body into the heating chamber,
A batch type heat treatment furnace having a gas introduction passage for introducing the same kind of gas as the atmosphere gas in the furnace. 2. The batch type heat treatment furnace according to claim 1, wherein a step portion is formed on an outer peripheral portion of the table, the furnace body is close to a horizontal surface and a vertical surface of the step portion, and the gas is After being introduced from the outside to the inside along the horizontal surface of the step, it flows upward along the vertical surface of the step,
A batch type heat treatment furnace which is introduced into a heating chamber. 3. The batch type heat treatment furnace according to claim 2, wherein an annular gas introduction chamber having a plurality of blow-out openings on the inner circumference is formed on the outer peripheral portion of the furnace body, and the gas introduction chamber is formed in the gas introduction chamber. The inflowing gas is blown out substantially evenly inward from the outlet along the horizontal surface of the step, and the batch type heat treatment furnace is characterized.