JPH0415483A - Baking furnace - Google Patents

Abstract

PURPOSE:To increase the working ratio by providing reflection plates which are arranged in a space in a furnace, facing outer and inner walls, a vacuum pump which evacuate air, a compressor which introduces low temperature outside air, and a changeover valve. CONSTITUTION:Reflection plates 26 are arranged in a spaces 24 inside a baking furnace 21, facing inner walls 23 and outer walls 25. Crucibles 43 in which ceramic molded pieces to be baked are contained are stacked on a hearth 29 loaded on a lift 31. A pipe P1 is connected to the space 24 and switched either to a vacuum pump 36 or compressor 37 by a three-way changeover valve 35. When the molded pieces are heated up, the air in the space 24 is evacuated by the vacuum pump 36 so that convection heat transfer is diminshed and radiant heat is reflected by the reflection plates 26, resulting in less heat releasing loss. In cooling process, low temperature outside air is sent by the compressor 37 so that cooling time period can be shortened, resulting in an increase of the working ratio.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates primarily to a firing furnace used for manufacturing ceramic electronic components such as ceramic condensers.

(Prior Art) Generally, a continuous type firing furnace or a hatch type firing furnace is used as a firing furnace used for manufacturing ceramic electronic components.

The vertical cross section of an example of a conventional batch-type firing furnace of this type is shown in Figure 3.
A cross section taken along the line 11-■ is shown in FIG.

The above-mentioned conventional firing furnace 1 is of a hearth raising and lowering type, and the lifter 5 moves the lower part of the furnace body 2 [
] It has a hearth 4 that goes up and down with respect to 3.

In order to reduce the amount of heat escaping from the inside of the furnace body 2 to the outside of the furnace body 2 as much as possible, the furnace body 2 and the hearth 4 are usually made of heat insulating material such as fiberglass, Kras wool, or Kao wool.
It has a structure in which it is supported by being stacked in multiple layers.

-1- The hearth 4 is fixed by fitting a link-shaped groove member 11 having a U-shaped cross section into which a sealing material 9 is attached. As a result, when the hearth 4 is moved to a predetermined position, the F edge 8a of the frame 8 of the furnace body 2 comes into pressure contact with the groove member 9 of the groove member 11, and the inside of the furnace body 2 to run.

In the soil of the hearth 4, saggers 6 containing ceramic compacts (not shown) to be fired are stacked. The ceramic molded body is made of silicon carbide (SiC), etc. suspended from the ceiling 2a of the furnace body 2 toward the hearth 4.
It is heated by a letter-shaped heater 7 and fired according to a predetermined firing program consisting of steps such as temperature raising, firing, and cooling.

(Problem to be Solved by the Invention) As mentioned above, in order to reduce the heat escaping from the inside of the furnace body 2 to the outside of the furnace body 2 as much as possible, the furnace body 2 and its hearth 4 are covered with a multilayer insulation material. In the overlapping firing furnace 1, after the temperature inside the furnace body 2 is maintained at a high temperature necessary for firing the ceramic molded body, the power to the heater 7 is turned off and the firing process is shifted to the cooling process. , t! in the furnace body 2! IIX degrees do not fall easily. Therefore, in the conventional firing furnace 1 described above, heat transfer due to air convection in the space between the inner wall and outer wall is suppressed when the temperature falls, and heat is radiated from the inside of the furnace body toward the outside of the furnace body due to the action of the reflector. radiant heat is also reflected. This prevents heat from escaping outside the furnace body during the temperature raising step.

On the other hand, in the cooling process, low-temperature outside air is introduced into the space of the furnace body and flows through the space of the furnace body. Thereby, in the cooling process, the inside of the furnace body is quickly cooled.

(Effects of the Invention) According to the present invention, when the temperature rises, convective heat transfer in the space of the furnace body is suppressed by the deaeration, and heat is radiated from the inside of the furnace body toward the outside of the furnace body due to the action of the reflector. Since the radiant heat is reflected, it is possible to suppress heat escaping outside the furnace body during the temperature raising process, making it possible to obtain a firing furnace with high thermal efficiency.

Further, according to the present invention, since the furnace body is cooled by the low temperature outside air introduced into the space between the inner wall and the outer wall of the furnace body, the temperature drop time inside the furnace body is shortened and the time is increased. There was a problem with low operating rates.

An object of the present invention is to provide a firing furnace with high operating rate and high thermal efficiency.

(Means for Solving the Problems) For this reason, the present invention provides a firing furnace in which an object to be fired is heat-treated through heating, firing, and cooling steps of about 2 F each, with an inner wall made of a heat-resistant steel plate, and a space outside the inner wall. A furnace body consisting of an outer wall disposed at a distance from the inner wall and a heat reflecting plate disposed facing the inner wall and the outer wall in the space described above; a compressor that presses low-temperature outside air into the space of the furnace body; The apparatus is characterized in that it includes a switching valve device for introducing outside air from a compressor into the space of the furnace body during the cooling process of the fired product.

(Function) At the time of rising inside the furnace body, the above deaeration causes the furnace body to
The operating rate of the furnace can be increased, and the cooling rate of the furnace body can also be controlled arbitrarily.

(Example) Below, the present invention will be described in detail with reference to the accompanying drawings.

FIG. 1 shows a longitudinal cross section of an embodiment of a hatch-type firing furnace according to the present invention, and FIG. 2 shows a cross section taken along line IV--IV in FIG. 1.

The firing furnace 21 includes a furnace body 22, an inner wall 23, an outer wall 25 arranged with a space 24 outside the inner wall 23, and the space 24.
It consists of a reflecting plate 26 disposed inside facing the inner wall 23 and outer wall 25. In the case of the firing furnace 21 which is required to have heat resistance of about 1000°C, the inner wall 23 and the outer wall 25 are made of a heat-resistant steel plate such as Inconel or stainless steel.

When the firing furnace 21 is particularly required to have heat resistance, a heat insulating material 27 is attached to the inside of the inner wall 23.

The space 2 between the inner wall 23 and the outer wall 25 of the furnace body 22
4 has an inner wall 23 and an outer wall 25 inside.
A heat reflecting plate 26, 26 is arranged opposite to the heat reflecting plate 26, 26. These reflectors 26.26. Holes 2828 are formed in the holes 2828 in order to circulate the air introduced during cooling of the furnace body 22 within the space 24 of the furnace body 22.

The furnace body 22 has an opening 32 on its lower side into which an elevating hearth 29 is fitted. The first hearth 29 is placed and fixed on the second part of the lid 31 for lifting and lowering.

The hearth 29 constitutes a part of the furnace body 22, -1-
It has the same configuration as the furnace body 22 whose configuration was explained in . -1
- The recording hearth 29 is fitted with a ring-shaped groove member 3/l having a U-shaped cross section and having a sealing material 33 installed therein. - When the hearth 29 is raised to a predetermined position, the lower edge 25a of the outer wall 25 of the furnace body 22 comes into pressure contact with the sealing material 33 of the groove member 34, and the inside of the furnace body 22 is closed.
- to play.

A pipe 1 is connected to each space 24 between the inner wall 23 and outer wall 25 of the furnace body 22 and the hearth 29, and this pipe Pl is connected to the heater 4 of the molded body by a three-way switching valve 35.
] When the temperature is raised by heating and when the high temperature is kept, the air in each space 24 between the inner wall 23 and outer wall 25 of the furnace body 22 and its hearth 29 is pumped by the vacuum pump 36 to, for example, 1O-2
The air is degassed to about Torr. As a result, the furnace body 22
In addition, heat transfer due to air convection within the space 24 between the inner wall 23 and outer wall 25 of the furnace body 22 is almost eliminated, and radiant heat to the outside of the furnace body 22 is absorbed by the reflecting plates 26, 26, . ..., and the heat radiation loss from the furnace body 22 is reduced.

When the high temperature is finished and the temperature is lowered, the operation valve 38 is opened, and the compressor 37 sends low-temperature outside air to the space 24 through the pipe P1, and the outside air flows into the space 24. As a result, the furnace body 22 is cooled by the air, the temperature is lowered, and the temperature lowering time is shortened.

[Brief explanation of the drawing]

FIG. 1 is a longitudinal cross-sectional view of one embodiment of the firing furnace according to the present invention, and FIG. 2 is a cross-sectional view of the firing furnace shown in FIG. 1 taken along line 1V-IV. Can be switched. The inner wall 23 and outer wall 25 of the furnace body 22 and its hearth 29
There is also a pipe P in each space 24 between. or connected. A control valve 38 is connected to this pipe P. This operation valve 28 is closed to the atmosphere by a three-way valve 35 when connected to each space 24 or the vacuum pump 36;
Open to atmosphere when connected to 7. 11-A U-shaped heater 41 made of silicon carbide or the like is suspended from the ceiling 22a of the furnace body 22 toward the hearth 29 along the inner wall 23 of the furnace body 22. . A base plate 42 is placed on the hearth 29, and a ceramic molded body to be fired is placed on the base plate 42 (not shown). )
The stored saggers 43 are stacked. In such a configuration, the ceramiso in the sagger 43 mounted on the hearth 29 which is raised and lowered by the lifter 31 is shown in FIG.
It is a cross-sectional view along the -■ line. 21・Firing furnace, 22・Furnace body, 23 Inner wall 24・Space, 2
5. External wall, 26 Reflector plate 28. Hole, 29. Hearth, 35
...3-way switching valve 36 ・Vacuum pump, 37 Compressor 38 ・Operation valve.

Claims (1)

[Claims] (1) In a firing furnace in which the object to be fired is heat-treated through the steps of temperature raising, firing, and cooling, an inner wall made of heat-resistant steel plate, an outer wall placed with a space outside the inner wall, and an inner wall located within the above space. and a heat reflecting plate disposed opposite the outer wall;
a vacuum pump that deaerates the air in the space of the furnace body;
A compressor that presses low-temperature outside air into the space of the furnace body, a vacuum pump to evacuate the space of the furnace body during the temperature raising and firing process of the object to be fired, and a furnace during the cooling process of the object to be fired. A firing furnace characterized by comprising a switching valve device for introducing outside air from a compressor into the space of the body.