JPH076740B2 - Firing furnace - Google Patents

Description

TECHNICAL FIELD The present invention relates to a firing furnace used in an experiment or the like for evaluating the firing process and firing conditions of a ceramic object to be fired.

[Prior Art] In general, there are two types of firing furnaces: a tunnel furnace type that continuously processes a ceramic object to be fired and a batch furnace method that batch-processes a ceramic object to be fired.

Conventionally, as an experimental firing furnace for the purpose of evaluating the sintering process and firing conditions of ceramics, a batch furnace whose longitudinal section and transverse section are shown in FIGS. 5 and 6 has been mainly used. It was

The batch furnace 1 is of a so-called hearth elevating type, and a furnace body 2 has an opening 2a for inserting and removing a box set 3 in which a box containing ceramic to-be-fired objects is stacked in multiple stages. Then, the hearth 4 of the furnace body 2 is lifted by an elevator mechanism (not shown) using a hydraulic sprue or a screw, and the burned material in the sack of the sack assembly 3 placed on the slab through the base plate 5 It is inserted into the furnace body 2 through the opening 2a.
A rod-shaped heater 7 made of silicon carbide (SiC) is inserted from the side wall 2b of the furnace main body 2 and combined in a grid pattern, and the rod-shaped heater 7 heats and fires the object to be fired.
A protective atmosphere gas is introduced into the inside of the furnace body 2 through an atmosphere gas introduction hole 8 provided in the side wall 2b of the furnace body 2. In addition, the exhaust gas generated in the furnace body 2 by firing the material to be fired in the box of the box set 3 is discharged to the outside of the furnace body 2 through the exhaust hole 9 formed in the ceiling portion 2c of the furnace body 2. .

[Problems to be Solved by the Invention] By the way, in the above-mentioned conventional firing furnace, since the inner wall of the furnace body 2 and the rod-shaped heater 7 are present outside the object to be fired of ceramic, the rod-shaped heater 7 and the furnace body 2 are thermally insulated. Impurities from materials and the like adhere to the ceramic object to be fired, so that the rod-shaped heater 7 and the furnace body 4 directly affect the ceramic object to be fired. Further, in the above-described conventional firing furnace, when the temperature of the furnace body is raised or lowered, particularly when the temperature is lowered, the cooling speed is limited by the characteristics such as the heat capacity and the thermal conductivity of the heat insulating material of the furnace body 2, and the ceramic coating is cooled. It is not possible to set free heating and cooling curves for the fired product.

Therefore, even if the ceramic is fired in the conventional firing furnace, the evaluation of the sintering of the ceramic is insufficient, and there is a problem that the original sintering process and firing conditions cannot be obtained. .

An object of the present invention is to provide a firing furnace capable of obtaining an arbitrary temperature rising / falling temperature profile.

Another object of the present invention is to cut off the influence of furnace materials such as a heat insulating material and a heater, and to rapidly raise and lower the temperature while maintaining a uniform firing atmosphere for a ceramic object to be fired. It is to provide a firing furnace.

[Means for Solving the Problems] Therefore, according to the first invention of the present application, a furnace body including a high-temperature portion in which a heater is arranged and a low-temperature portion located below the furnace body, and a ceramic object to be fired are loaded. And a furnace floor that moves up and down in the furnace body. By moving up and down the furnace bed in the furnace body, the ceramic object to be fired is moved between the high temperature portion and the low temperature portion of the furnace body to achieve the desired firing. A firing furnace for firing a ceramic object to be fired according to a profile, comprising temperature measuring means provided in the hearth floor for measuring the temperature of the ceramic object, and the object to be output from the temperature measuring means. Is compared with a reference signal determined in correspondence with a desired firing profile, and hearth position control means for controlling the position of the hearth is provided.

The second invention of the present application is characterized in that, in the first invention of the present application, an openable shutter is provided between the high temperature portion and the low temperature portion to block radiant heat from the high temperature portion to the low temperature portion.

Further, a third invention of the present application is a furnace which comprises a high temperature part in which a heater is arranged and a low temperature part which is located under the high temperature part, and a furnace for raising and lowering the inside of the furnace main body on which a ceramic object to be fired is loaded. And a floor, and by moving up and down in the furnace body of the hearth, the ceramic object to be fired is moved between the high temperature portion and the low temperature portion of the furnace body to fire the ceramic object to be fired with a desired firing profile. And a temperature measuring means provided in the hearth for measuring the temperature of the object to be fired of ceramic, and a temperature signal of the object to be fired outputted from the temperature measuring means and a desired firing profile. And the reference signal determined by, the hearth position control means for controlling the position of the hearth, a muffle that covers the ceramic fired object on the hearth, and project from the hearth into the muffle. In this muffle It is characterized by comprising a charging pipe for charging a protective atmosphere gas and an exhaust gas discharging pipe projecting from the furnace floor into the muffle and discharging the exhaust gas generated in the muffle to the outside of the furnace body.

Still further, a fourth invention of the present application is the third invention of the present application, wherein an openable shutter is provided between the high temperature portion and the low temperature portion to block radiant heat from the high temperature portion to the low temperature portion. .

[Operation] The hearth position control means compares the temperature signal of the object to be fired output from the temperature measuring means with a reference signal determined corresponding to a desired firing profile to determine the position of the hearth. Control. As a result, the hearth moves up and down in the furnace body following the reference signal, and the material to be fired of the ceramic loaded on it moves between the high temperature portion and the low temperature portion of the furnace body,
It is fired with a desired firing profile.

In addition, the muffle forms a space in the furnace body that covers the ceramic material to be fired on the hearth. Then, a protective atmosphere is introduced into this space from an injection pipe, and the exhaust gas generated from the ceramic firing target in this space is exhausted from the exhaust gas exhaust pipe.

[Effect of the Invention] According to the first invention of the present application, the hearth moves up and down in the furnace body in accordance with the reference signal, and the ceramic object to be fired placed on the furnace body is at a high temperature. Between the low temperature section and the low temperature section, it follows the reference signal that is arbitrarily set in advance, so the ceramic object to be fired is heated and cooled as the furnace floor of the furnace body moves up and down, and according to the reference signal. According to the second invention of the present application, it is possible to perform firing with a desired firing profile, and according to the second invention of the present application, the shutter provided between the high temperature portion and the low temperature portion of the furnace body is opened and closed to fire the ceramic. Since it is possible to rapidly apply heat to the object or cut off the heat, it becomes possible to achieve a firing profile for rapid heating and rapid cooling of the ceramic object to be fired. Further, according to the third invention of the present application, the space inside the muffle provided in the furnace body to cover the object to be fired of ceramic is cut off from the space outside the muffle, and the atmosphere gas supply pipe is supplied to the space inside the muffle. The atmosphere gas is supplied through the exhaust gas, and the exhaust gas generated in the muffle is exhausted through the exhaust gas exhaust pipe, so the material to be fired of the ceramic in the muffle is affected by the heat insulating material of the furnace body and the heater. Is prevented and
The inside of the muffle can be quickly made into a desired atmosphere.

Furthermore, according to the fourth invention of the present application, in addition to the effect of the third invention of the present application, it becomes possible to provide a firing profile for rapid heating and rapid cooling of a ceramic object to be fired.

Embodiments Embodiments of the present invention will be described below with reference to the accompanying drawings.

A longitudinal sectional view and a lateral sectional view of an embodiment in which the present invention is applied to a batch furnace are shown in FIGS. 1 and 2, respectively.

The batch furnace 12 includes a vertically long furnace body 13 having an aspect ratio of, for example, 2: 1 and a ceramic object to be fired (not shown below).
Described as a unit. ) And a furnace floor (14) for moving up and down in the furnace body (13).

The furnace body 13 has a high temperature part 16 in which a rod-shaped heater 15 is arranged.
And a low temperature part 17 located below the high temperature part.
A shutter 18 made of ceramics is arranged between the low temperature portion 16 and the low temperature portion 17 to shut off the gap.

In the high temperature part 16 above the furnace body 13, silicon carbide (SiC)
A rod-shaped heater 15 made of metal is inserted from the side wall 13a of the furnace body 13 and is combined in a grid pattern. Then, the rod-shaped heater 15 heats the unit. The heat generation temperature of the rod-shaped heater 15 is the ceiling part 13b of the high temperature part 16 of the furnace body 13.
Further, the temperature is detected by the thermocouple 19 inserted in the high temperature section 16, and the temperature is controlled by the temperature controller 21 to a constant temperature.

The rod-shaped heater 15 has a narrower interval as the distance between the high-temperature parts 16 of the furnace body 13 increases, and
The lower it is, the wider the space is. As a result, the inside of the high temperature portion 16 of the furnace body 13 has a slight temperature distribution. This is because the amount of radiant heat varies depending on the position of the unit from the hearth 14.

The low temperature part 17 at the bottom of the furnace body 13 is for preventing the unit from directly contacting the outside air, and is a relatively thin layer of heat insulating material. The hearth 14 moves up and down by the screw jack.

The hearth 14 includes a lower hearth 22 having a size slightly smaller than the cross-sectional size of the low temperature part 17 of the hearth body 13, and the lower hearth 22.
An upper hearth 23 having a projecting dimension that can project from the lower opening 16a of the high temperature part 16 of the furnace body 13 and can advance into the high temperature part 16.
Consists of.

The unit is housed in a box and placed on a base plate 24 arranged on the upper hearth 23, and the upper hearth 23 of the hearth 14 is connected to the high temperature part 16 and the low temperature part 17 of the furnace body 13. To move between. In the process of this movement, the above unit is fired with a desired firing profile by the configuration described below.

That is, the hearth 14 is provided with a temperature measuring sensor 25 such as a thermocouple for measuring the temperature of the ceramic unit. Further, outside the batch furnace 12, a hearth position control device 29 for controlling the hearth lifting device 27 of the hearth 14 is provided. The hearth position control device 29 controls the hearth elevating device 27 by comparing the temperature signal of the unit output from the temperature measurement sensor 25 with a reference signal defined corresponding to a desired firing profile. To do.

As a result, the ceramic unit placed on the upper hearth 23 of the hearth 14 moves between the high temperature part 16 and the low temperature part 17 of the furnace body 13 of the batch furnace 12 according to the reference signal, The ceramic unit is fired with an arbitrary profile defined by the reference signal.

And when the ceramic unit cools down,
14 is lowered and the shutter 18 is closed. As a result, the internal temperature of the high temperature portion 16 of the furnace body 13 of the batch furnace 12 is secured and the radiant heat during cooling is shut off.

In the batch furnace 12 described above, in order to further improve the sintering conditions of the ceramic unit, further,
It has the following configuration.

That is, as shown in FIGS. 3 and 4, the base plate 24 on which the box assembly 3 in which the boxes containing the units are stacked are stacked is placed in a hole (not shown) for the inlet pipe 31 for the protective atmosphere gas. .) Are opened at two positions at both ends of one diagonal line of the base plate 24,
Further, two holes (not shown) for the exhaust gas exhaust pipe 33 are provided at both ends of another diagonal line of the base plate 24. An atmosphere gas input pipe 31 and an exhaust gas exhaust pipe 33 penetrate through these holes from the bottom of the hearth 14.
The injection pipe 31 is an end sealing pipe whose protrusion height from the base plate 24 is higher than that of the case assembly 3, and the exhaust gas discharge pipe 33 has a protrusion height from the base plate 24 higher than that of the base plate 24. It is an open tube with a slightly higher degree. And these boxes 3, the input pipe of the atmospheric gas
A muffle 35 is arranged so as to cover the exhaust gas exhaust pipe 33.

The muffle 35 and the base plate 24 form a space 36 (see FIGS. 3 and 4) that is not affected by furnace materials such as a heat insulating material and a heater.

Fresh protective atmosphere gas is supplied to each unit of the box set 3 through small-diameter openings (not shown) provided in the atmosphere gas introduction pipe 31 through the atmosphere gas introduction pipe 31, and directly to the unit. Sent. The protective atmosphere gas sent in this way is consumed by the unit during the firing step, at which time the exhaust gas exits each box and flows to the lower layer. Then, the heavier exhaust gas is discharged to the outside of the muffle 35 through the exhaust gas discharge pipe 33. Thus, muffle 35
Thus, in the space 36 surrounding the unit, the gas can be uniformly and quickly exchanged. Also, it is not affected by anything outside the muffle 35.

[Brief description of drawings]

1 is a longitudinal sectional view of an embodiment of the firing furnace according to the present invention, FIG. 2 is a transverse sectional view of the firing furnace of FIG. 1, and FIGS. 3 and 4 are views of the firing furnace of FIG. 1, respectively. FIG. 5 is a vertical cross-sectional view and a horizontal cross-sectional view showing a space inside the muffle, and FIGS. 5 and 6 are a vertical cross-sectional view and a horizontal cross-sectional view of a conventional firing furnace, respectively. 3 ... Tsugumi, 12 ... Batch furnace, 13 ... Furnace body (13a ... Side wall, 13b ...
Ceiling), 14 ... Hearth, 15 ... Rod heater, 16 ... High temperature part, 17 ... Low temperature part, 18 ... Shutter, 19 ... Thermocouple, 21 ... Temperature control device, 25
… Temperature measurement sensor, 29… Hearth position control device, 31… Atmosphere gas input pipe, 33… Exhaust gas discharge pipe, 35… Muffle, 36…
space.

Claims (4)

[Claims] 1. A furnace main body comprising a high temperature part in which a heater is disposed and a low temperature part located below the furnace main body, and a hearth for loading a ceramic object to be fired and raising and lowering the inside of the furnace main body. This is a firing furnace for moving the ceramic object to be burned between the high temperature portion and the low temperature portion of the furnace body by raising and lowering the hearth in the furnace body and firing the ceramic object with a desired firing profile. The temperature measuring means provided in the hearth for measuring the temperature of the ceramic fired object, the temperature signal of the fired object output from the temperature measuring means, and the desired firing profile are determined. A firing furnace comprising: a hearth position control means for controlling the position of the hearth by comparing with a reference signal. 2. The firing furnace according to claim 1, further comprising an opening / closing shutter for blocking radiant heat from the high temperature portion to the low temperature portion between the high temperature portion and the low temperature portion. 3. A furnace main body comprising a high temperature part in which a heater is disposed and a low temperature part located below the furnace main body, and a hearth for loading a ceramic object to be fired and moving up and down in the furnace main body. This is a firing furnace for moving the ceramic object to be burned between the high temperature portion and the low temperature portion of the furnace body by raising and lowering the hearth in the furnace body and firing the ceramic object with a desired firing profile. The temperature measuring means provided in the hearth for measuring the temperature of the ceramic fired object, the temperature signal of the fired object output from the temperature measuring means, and the desired firing profile are determined. Compared with a reference signal, hearth position control means for controlling the position of the hearth, a muffle that covers the ceramic firing object on the hearth, and a muffle projecting from the hearth into the muffle. Protective atmosphere gas A firing furnace provided with a charging pipe for charging and an exhaust gas discharge pipe projecting from the furnace floor into the muffle and discharging the exhaust gas generated in the muffle to the outside of the furnace body. 4. The firing furnace according to claim 3, further comprising an opening / closing shutter for blocking radiant heat from the high temperature portion to the low temperature portion between the high temperature portion and the low temperature portion.