JP5725414B2 - Firing method for batch firing furnace - Google Patents

Description

  The present invention relates to a method for firing a batch firing furnace for rapidly heating a treated product to a high temperature of 1000 ° C. or higher and firing it uniformly in a batch firing furnace.

  Conventionally, in a high-temperature batch-type baking furnace that is heated to a temperature of 1000 ° C. or higher, a heater for heating is disposed along the furnace wall of the baking furnace, and processed products loaded on a setter (or tray) are vertically or horizontally or A method of heating from the front-rear direction has been performed.

  In this method, the heating heater and the processed product are separated as much as possible to equalize the temperature, but the temperature rises quickly at a location close to the heating heater (for example, the end of the setter), and the heating heater The temperature rises slowly at locations far from the center (for example, the center of the setter), and the way the temperature rises depends on the position of the setter where the processed products are loaded (the upper, middle, and lower tiers on which the setter is placed) There were difficulties, and the temperature was not uniform, adversely affecting the quality of the processed product.

  In order to solve this difficulty, the present applicant, as shown in FIG. 3, as a firing method of a batch-type firing furnace for rapidly heating a treated product to a high temperature of 1000 ° C. or higher and uniformly firing it, (The furnace is not shown in the figure.) A shelf structure 8 in which rod-shaped or pipe-shaped heaters 1 are juxtaposed is arranged in a plurality of stages (10 stages in the case of FIG. 3) in the vertical direction, and near the inner wall surface of the furnace A method was proposed in which the auxiliary heater 2 is disposed on the shelf structure 7 and a setter 7 on which a processed product (not shown) is loaded is placed on the shelf structure 8 to heat and fire the processed product.

JP 2010-133591 A

  However, even in the above-described proposed firing method, when the batch-type firing furnace is used as an actual machine and the interior dimensions of the furnace are economical, the temperature in the setter loaded with the treated products is not uniform, and the quality of the treated products varies. I found out that there was something.

  In order to solve this problem, the present invention was made as a result of repeated tests and examinations on the relationship between various factors and temperature distribution in the firing method of a batch-type firing furnace. To provide a baking method for a batch-type baking furnace that makes it possible to obtain a processed product with excellent quality by uniformizing the temperature distribution in a setter placed on a shelf structure in which heaters are arranged in parallel. .

  The firing method of the batch-type firing furnace according to claim 1 for achieving the above object comprises arranging a plurality of stages in a vertical direction in a shelf structure in which rod-like or pipe-like heaters are juxtaposed in the furnace, In a batch-type firing furnace in which an auxiliary heater is disposed on the inner wall surface of the furnace or in the vicinity of the inner wall surface, a setter loaded with processed products is placed on the shelf structure to heat and fire the processed products. Use a heater with a non-heat generating part 10-25% of the length of the heat generating part at the center, and heat the auxiliary heater and setter at a distance of 3d to 10d (where d is the diameter of the auxiliary heater). And firing.

  The method for firing a batch-type firing furnace according to claim 2 is the heater according to claim 1, wherein the rod-shaped or pipe-shaped heater is provided with a non-heat generating portion having a length of 10 to 25% of a heat generating portion length at a central portion. It is characterized by using.

  A baking method for a batch-type baking furnace according to claim 3 is the heating method according to claim 1 or 2, wherein, in the batch-type baking furnace, the processed product loaded on the setter is heated to a predetermined heating temperature and fired. After the temperature is raised to the temperature, the predetermined heating temperature is maintained by controlling the output of the auxiliary heater while maintaining the output of the heater for heating at 10% or less of the maximum output.

  According to the present invention, there is provided a batch-type firing furnace capable of mass production capable of rapidly and uniformly heating a processed product to a high temperature of 1000 ° C. or higher. It can be effectively applied to firing MLCC molded products such as capacitors having a high dielectric layer such as a thin dielectric layer of 0.5 microns or less and a nickel internal electrode.

In the batch-type firing furnace applied to the present invention, the heating heaters arranged in parallel in each stage of the shelf structure, the auxiliary heater disposed on the inner wall surface of the furnace, and the treatment placed on the shelf structure It is a top view which shows the setter which loaded goods. In FIG. 1, it is a top view which further shows arrangement | positioning of the preheating heater for preheating atmospheric gas supply pipe | tube and atmospheric gas. The baking method for a batch-type firing furnace, which is the premise of the present invention, is shown by arranging a plurality of shelves in a vertical direction with heaters arranged side by side, and an auxiliary heater near the inner wall of the furnace. FIG. 5 is a side view showing a configuration in a furnace in which a setter loaded with processed products is placed on a shelf structure and the processed products are fired.

  In the present invention, a shelf structure in which rod-shaped or pipe-shaped heaters are juxtaposed in a batch-type firing furnace is arranged in a plurality of stages in the vertical direction, and an auxiliary heater is disposed on the inner wall surface of the furnace or in the vicinity of the inner wall surface. The setter with the processed products loaded thereon is placed on the shelf structure, and the processed products are heated and fired. FIG. 1 shows a shelf structure at each stage. For example, eight heating heaters 1 are arranged side by side to form a shelf structure 8, and an auxiliary heater 2 is arranged on the inner wall surface W of the furnace. A setter 7 loaded with processed products is placed thereon, and the processed products are heated and fired.

  In the present invention, in this case, as the auxiliary heater 2, a heater provided with a non-heat generating portion 4 having a length of 10 to 25% of the heat generating portion length of the auxiliary heater 2 is used as the auxiliary heater 2. 3d to 10d (where d is the diameter of the auxiliary heater 5) (5d in FIG. 1) and heated and fired. In FIG. 1, 3 is a heating part of the auxiliary heater, and 5 and 6 are a terminal of the heater 1 and a terminal of the auxiliary heater 2, respectively.

  When a heater having a heat generating part length is used as the auxiliary heater 2, the temperature at both ends of the setter 7 on which a processed product is loaded is increased by the radiant heat from the auxiliary heater 2 during heating and firing. Reduce product quality. By using a heater provided with a non-heat generating part 4 in the center as the auxiliary heater 2, the temperature distribution of the setter 7 can be made uniform, and 10-25% of the length of the heat generating part in the center, more preferably heat is generated. It is effective to provide the non-heat generating portion 4 having a length of 20 to 25% of the length.

  The auxiliary heater 2 and the setter 7 are preferably heated and fired at a distance of 3d to 10d (d is the diameter of the auxiliary heater 5), more preferably 5d to 7d. The distance between the auxiliary heater 2 and the setter 7 If it is less than 3d, the temperature at both ends of the setter 7 tends to be high during heating and firing by the radiant heat of the auxiliary heater 2. The upper limit is 10d in relation to the furnace dimensions.

  In order to more effectively prevent the quality of the processed product from being deteriorated due to the large temperature difference in the setter 7 on which the processed product is loaded during heating and firing, not only the auxiliary heater 2 but also As the rod-shaped or pipe-shaped heater 1, it is preferable to use a heater provided with a non-heat generating part having a length of 10 to 25% of the heat generating part length of the heater 1 at the center.

  In order to make the temperature distribution of the setter 7 more uniform during heating and firing, the processed products loaded on the setter 7 are heated to a predetermined heating temperature (set temperature in the furnace) and fired in a batch-type firing furnace. In this case, after the temperature is raised to the predetermined heating temperature, the predetermined heating temperature is maintained by maintaining the output of the heater 1 for heating to 10% or less of the maximum output and controlling the output of only the auxiliary heater 2. Is desirable. At the time of temperature increase, heating is performed with the outputs of the heater 1 and the auxiliary heater 2 being maximized, that is, the temperature is controlled using the heater 1 as a main heater. The output of 1 is maintained at 10% or less of the maximum output, and the auxiliary heater 2 is switched to the main heater to control the temperature. For this purpose, the heater 1 and the auxiliary heater 2 are configured to be controlled separately.

  2 further shows an atmosphere gas supply pipe 9 arranged in the vicinity of the furnace wall for the atmosphere control of the batch-type firing furnace in FIG. 1, and is arranged between the inner wall surface W of the furnace and the atmosphere gas supply pipe 9. 2 shows a preheating heater 11 for preheating the generated atmospheric gas. In particular, if the amount of atmospheric gas sprayed is increased, the temperature of the setter 7 at the atmospheric gas spray position is likely to decrease, so that the preheated heater 11 treats the atmospheric gas in order to uniformly heat the processed product. It is preferable to spray the setter (processed product) after preheating to a temperature 50 ° C to 20 ° C lower than the heating temperature (set temperature in the furnace) T ° C of the product, that is, (T-50 to 20) ° C. In FIG. 2, 10 is an atmospheric gas discharge pipe disposed on the opposite side of the atmospheric gas supply pipe 9 across the setter 7, and an arrow A indicates the flow of the atmospheric gas.

  FIG. 2 shows an embodiment in which the atmosphere gas supply pipe 9 and the preheating heater 11 are arranged in each stage of the shelf structure. The furnace is arranged so that the atmosphere gas supply pipe is orthogonal to the shelf structure composed of heaters arranged in parallel. Preferably, a plurality of them may be arranged in the vertical direction, and the blowing port of the atmospheric gas supply pipe may be rotated to blow the atmospheric gas toward the processed product loaded on the setter. Also in this case, the preheater 11 is arranged at each stage of the shelf structure.

  In the present invention, a shelf structure in which rod-shaped or pipe-shaped heaters are arranged side by side in a batch-type firing furnace is arranged in a plurality of stages in the vertical direction, and an auxiliary heater is disposed on or near the inner wall surface of the furnace. In order to improve the temperature distribution in the vertical direction in the furnace, the setter with the processed products loaded on the shelf structure is placed and heated and fired. It is desirable to divide the control circuit for the auxiliary heater and auxiliary heater, and the control circuit for the atmospheric gas preheating heater into a plurality of groups (for example, three groups) in the vertical direction and perform independent temperature control in each group.

  Examples of the present invention will be described below. This example shows one embodiment of the present invention, and the present invention is not limited to this.

Example 1
A heating structure (heat generating part length: 300 mm) with a diameter of 12 mm is juxtaposed in a firing furnace having a width of 300 mm, a height of 310 mm, and a length of 425 mm (furnace volume: 39.5 L) to form a shelf structure. Then, this shelf structure was arranged in five stages in the vertical direction of the furnace. The setter was 150 mm square and made of alumina having a thickness of 3 mm, and was placed on the shelf structure of each stage.

  As shown in FIG. 1, an auxiliary heater (having a non-heat generating part having a heat generation part length of 20% in the central part) is arranged on the inner wall surface of each stage of the shelf structure, and the distance between the auxiliary heater and the setter is 5d ( d: Diameter of auxiliary heater). In addition, as shown in FIG. 2, an atmosphere gas supply pipe and a preheating heater were arranged at each stage of the shelf structure.

  Using the firing furnace configured as described above, the output of the heater and the auxiliary heater is maximized, and the temperature is increased to 1190 ° C. at a heating rate of 80 ° C./min (4800 ° C./h). While maintaining the heater output at 5%, the output of only the auxiliary heater was controlled so as to maintain the temperature of 1190 ° C.

  When the temperature at the four corners and the center of each stage of the shelf structure arranged in five stages was measured, the temperature difference was within 1 ° C. for the first and second stages of the uppermost stage, and 3 ° C. for the third stage. Within 4 ° C, the temperature was within 2 ° C, the bottom 5th was within 4 ° C, and the 5th overall was within 5 ° C, indicating an excellent temperature distribution.

DESCRIPTION OF SYMBOLS 1 Heating heater 2 Auxiliary heater 3 Heating part of auxiliary heater 4 Non-heating part of auxiliary heater 5 Terminal of heating heater 6 Terminal of auxiliary heater 7 Setter 8 Shelf structure 9 Atmospheric gas supply pipe 10 Atmospheric gas discharge pipe 11 Preheating heater W Furnace inner wall A Flow of atmospheric gas

Claims (3)

A batch-type firing furnace in which a plurality of stages of a shelf structure in which bar-shaped or pipe-shaped heaters are arranged in parallel in the furnace are arranged in the vertical direction, and an auxiliary heater is disposed near the inner wall surface or the inner wall surface of the furnace, In the method of heating and baking a processed product by placing a setter loaded with processed products on the shelf structure, a heater provided with a non-heat generating portion having a length of 10 to 25% of the heat generating portion length as an auxiliary heater in the center portion A method of firing a batch-type firing furnace, wherein the auxiliary heater and the setter are heated and fired at a distance of 3d to 10d (where d is the diameter of the auxiliary heater). 2. The batch-type firing furnace according to claim 1, wherein a heater having a non-heat generating part having a length of 10 to 25% of a heat generating part length is used in the central part as the rod-shaped or pipe-shaped heating heater. Firing method. In the batch-type firing furnace, when the processed products loaded on the setter are heated to a predetermined heating temperature and fired, after the temperature is raised to the predetermined heating temperature, the predetermined heating temperature is maintained by the heating heater. The firing method for a batch-type firing furnace according to claim 1 or 2, wherein the output is maintained at 10% or less of the maximum output and the output of the auxiliary heater is controlled.

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