JP5732655B2 - Batch type firing furnace - Google Patents

Description

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

  Conventionally, in a high-temperature batch-type firing furnace that is heated to a temperature of 1000 ° C. or higher, as shown in FIGS. ) Heat the treated product from 4 left and right and front and rear directions (FIG. 8), or heat the treated product from the vertical direction of the tray (FIG. 9), or arrange the heater 3 to change the heating direction. The method of heating was performed. 8 and 9, 3 is a heater terminal, and 5 is a tray support.

  In the above conventional method, it is common to heat the heater and the processed product as far as possible to equalize the temperature, so that the volume in the furnace needs 6 to 10 times the volume of the processed product. It was.

  Further, since the distance between the heater and the processed product is far, the temperature rises quickly at a place close to the heater (for example, the end portion 9 of the tray), and the temperature rise becomes slow at a place far from the heater (for example, the central portion 8 of the tray). The temperature rise differs depending on the position of the tray on which the processed product is loaded (the upper stage 11 of the tray, the middle stage 10 of the tray, and the lower stage 12 of the tray). Therefore, the temperature is not uniform and the quality of the processed product is adversely affected. .

  In the conventional batch-type firing furnace, in consideration of this influence, a temperature keeping region is provided at a predetermined temperature as shown in FIG. 10 for soaking, and the tray is kept for several tens of minutes to several hours. The waiting time to wait until the temperature of the processed products becomes uniform is necessary, and this waiting time causes waste in energy consumption, resulting in differences in the thermal history of each processed product, resulting in product variation It was.

  Furthermore, as described above, a temperature difference occurs in the tray (or setter) during heating, so if the temperature rises rapidly, the tray (or setter) will be damaged due to the difference in thermal expansion due to the temperature difference in the tray (or setter). Therefore, 1000 ° C./h was the limit for rapid temperature rise.

  As a method of rapidly heating the processed product, there is a roller hearth type furnace (for example, refer to Patent Document 1) other than the batch type furnace, but when the setter loaded with the processed product enters the high temperature zone, There are problems such as a sudden temperature difference and setter breakage, the setter area cannot be increased, and it is not suitable for mass production of processed products. There is a disadvantage that it will adversely affect.

In addition, in the case of heat treatment of metals, there is also a method of providing a preheating chamber and a heating chamber separately and rapidly moving the preheated processed product to the heating chamber, but the structure of the furnace is complicated and equipment is installed. Cost is enormous. Furthermore, the moment of moving from the preheating chamber to the heating chamber is exposed to a high temperature atmosphere, but there is also a problem that the temperature rise after that moment can be processed only at a normal rate of temperature rise.
JP 2008-37736 A

The present invention has been made in order to solve the above-mentioned conventional problems in a batch-type firing furnace, and its purpose is to rapidly heat a treated product to a high temperature of 1000 ° C. or higher and to uniformly fire the processed product. It is to provide a firing furnace .

Batch firing furnace according to claim 1 for achieving the above object, a plurality juxtaposed over between the inner wall surface of the opposing furnace, the shelf structure comprising a plurality of rod-like or pipe-like heater in the vertical direction The relationship between the distance h between the upper surface of the stacking plate of the processed products placed in stages and placed directly on the shelf structure and the lower surface of the heater of the shelf structure disposed above the stacking plate and the diameter D of the heater is h. <4 × D is characterized in that the processed product on the loading plate is heated.

Batch firing furnace according to claim 2, in claim 1, characterized in that disposed an auxiliary heater near the inner wall surface of the furnace.

Batch firing furnace according to claim 3, in claim 1 or 2, in the range of the diameter D of the rod-like or pipe-shaped heater 6～16Mm, the number n of the juxtaposed heater, parallel heater The heater is arranged in parallel with the length L of the stacking plate in the installation direction so that L <(D + 20) × n.

Batch firing furnace according to claim 4, in any one of claims 1 to 3, as the rod-like or pipe-shaped heaters, the heater consists of silicon carbide or graphite or further insulating the heater made of the silicon carbide or graphite, A heater covered with a pipe is used.

According to the present invention, a batch-type firing furnace capable of being rapidly and uniformly heated to a high temperature of 1000 ° C. or higher is provided , and the batch-type firing furnace is particularly a thin dielectric having a thickness of 0.5 μm or less. MLCC molded products such as capacitors having a high stack of layers and nickel internal electrodes, etc. are rapidly heated at a temperature of 3000 ° C./h or more, and the tensile and compressive forces of the dielectric layer and the electrode layer in this temperature range are alleviated, It can be effectively applied for the purpose of preventing cracking of the thin film and preventing the delamination phenomenon between layers.

  In the present invention, rod-shaped or pipe-shaped heaters are juxtaposed in the furnace, and the processed products are placed on the arranged heaters, and the processed products are heated to perform rapid and uniform heating. Can do. Placement of processed products on the heaters arranged side by side is usually performed by placing a loading plate (tray, setter, etc.) on the heater and placing the processed products on the loading plate.

  As an embodiment, as shown in FIG. 1, for example, eight rigid rod-like or pipe-like heaters 2 having a diameter of 10 mm are arranged side by side in a furnace (furnace illustration is omitted). The shelf structure is arranged in a plurality of stages in the vertical direction in the furnace, and on these shelf structures, as shown in FIG. 2, a loading plate (setter) 13 of the processed product 14 is directly placed, The processed product 14 on the setter 13 is heated.

  FIG. 3 is a diagram in which 10 stages of shelf structures configured by arranging eight heaters 2 shown in FIG. 1 are arranged above and below the furnace, and setters 13 are placed on each stage. The relationship between the distance h between the upper surface of the setter 13 and the lower surface of the heater disposed above the setter 13 and the diameter D of the heater 2 is preferably h <4 × D.

  FIG. 7 is a diagram showing the inside of a firing furnace in which a shelf structure in which two setters 13 are arranged is arranged in five stages. For mass production, a shelf structure in which heaters 2 are arranged side by side is arranged in the furnace. It is desirable to arrange several tens of stages in the vertical direction.

  It is desirable to arrange the heaters 2 as densely as possible, but the number of the heaters 2 arranged in parallel is a rod-shaped or pipe-shaped heater in order to optimize the temperature distribution of the processed product 14 loaded on the setter 13. When the diameter D of 2 is in the range of 6 to 16 mm, the number n of the heaters arranged side by side is L <(D + 20) × n with respect to the length L of the stacking plate (setter) 13 in the heater arrangement direction. It is desirable to arrange the heaters side by side.

FIG. 4 shows an embodiment in which auxiliary heaters 6 and 6 are attached to the basic structure of the above-described batch-type firing furnace according to the present invention in the longitudinal direction of the heater 2 and the inner wall surface made of the heat insulating material of the furnace. . By attaching the auxiliary heaters 6 and 6, it is possible to provide a firing furnace that enables a temperature compensation function in the furnace.

5 and 6 show the configuration of the batch type firing furnace of the present invention with furnace atmosphere control. As shown in FIG. 6, the atmosphere gas supply pipes 7 are arranged in each stage of the heater (shelf structure) arranged in parallel, and the atmosphere gas is sprayed in the direction of arrow A toward the processed product loaded on the setter 13. As shown in FIG. 5, several atmosphere gas supply pipes 7 are arranged in the vertical direction of the furnace so as to be orthogonal to the heater (shelf structure) arranged in parallel, and the supply pipe 7 is rotated to bring the atmosphere There is a method in which gas is blown in the direction of arrow B toward the processed product loaded on the setter 13. In the method shown in FIG. 5, a method of moving the atmosphere gas supply pipe 7 in the vertical direction of the furnace can be used in combination. Which of these methods is adopted is selected according to the size of the furnace and the properties of the processed product.

  In the batch-type firing furnace according to the present invention, it is preferable to use a heater made of silicon carbide or graphite, or a heater in which the heater is further covered with an insulating pipe.

  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
Eight heaters having a diameter of 10 mm were arranged side by side in the furnace to form a shelf structure, and this shelf structure was arranged in five stages in the vertical direction of the furnace. The heater interval was 25 mm, and the heater interval of each stage (distance between the upper surface of the heaters arranged side by side and the lower surface of the heater arranged thereon) was 30 mm.

  The heating length of the heater was 200 mm and the furnace volume was 11.3 liters. The setters were 150 mm square and 3 mm thick made of alumina, one for each stage, a total of five.

  Using the firing furnace configured as described above, the temperature was raised from 20 ° C. to 1300 ° C. at a heating rate of 80 ° C./min (4800 ° C./h). Although the temperature was raised to 1300 ° C. in 16 minutes, no abnormalities such as cracks were found in the setter.

As the temperature on the setter at the time of temperature rise, the temperature (b) at the center of the setter and the temperature (c) at the end of the setter were measured and compared with the program temperature (a). The temperature difference between a, b and c was 3 It was within ℃. On the other hand, in a conventional batch type firing furnace having a furnace internal volume of 42 liters capable of processing five setters of the same size as above, it takes 78 minutes (984 ° C./h) to increase the temperature to 1300 ° C. The maximum temperature difference between a, b, and c was 230 ° C. for (ab) and 230 ° C. for (ac).

  The temperature distribution within 10 mm above the setter (made of alumina of 150 mm square and 3 mm thickness) was ± 1 ° C. or less, and no phenomenon such as mutual damage or welding due to contact between the setter and the heater was observed.

It is a top view which shows the Example of the heater arranged in parallel in the batch type baking furnace of this invention. It is a top view which shows the state which mounted the setter and the processed goods on the heater arranged in parallel of FIG. In the batch type firing furnace of the present invention, it is a side view showing an embodiment in a state where a plurality of shelves arranged in a heater are arranged in the vertical direction of the furnace and setters are placed on the shelf structure. In FIG. 3, it is a side view which shows the Example which has arrange | positioned the auxiliary heater. In the batch-type firing furnace of the present invention, it is a plan view showing an embodiment of the arrangement and gas supply state of the atmosphere gas supply pipe for spraying the atmosphere gas to the processed product on the shelf structure in which the heaters are juxtaposed. In the batch-type firing furnace of the present invention, it is a plan view showing another embodiment of the arrangement and gas supply state of the atmosphere gas supply pipe for blowing the atmosphere gas to the processed product on the shelf structure in which the heater is arranged in parallel . It is a figure which shows the Example inside the furnace in the batch type baking furnace of this invention. It is a figure which shows what provided the heater in the side surface in a furnace in the conventional batch type baking furnace. It is a figure which shows what provided the heater in the upper and lower surfaces in the furnace in the conventional batch type baking furnace. It is a graph which shows the temperature rising pattern in the conventional batch type baking furnace.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Furnace 2 Heater 3 Heater terminal 4 Tray 5 Tray support stand 6 Auxiliary heater 7 Atmospheric gas supply pipe 8 Tray center part 9 Tray edge part 10 Tray middle stage 11 Tray upper stage 12 Tray lower stage 13 Setter 14 Processed goods

Claims (4)

Juxtaposed over between the inner wall surface of the opposing furnace, the shelf structure comprising a plurality of rod-like or pipe-shaped heater, a plurality of stages arranged in a vertical direction, the stacking plate of the treated product directly placed on the shelf structure The relationship between the distance h between the upper surface of the heater and the lower surface of the heater of the shelf structure disposed above the loading plate and the diameter D of the heater is set to h <4 × D, and the processed product on the loading plate is heated. A batch-type firing furnace characterized by that. The batch-type firing furnace according to claim 1, wherein an auxiliary heater is disposed in the vicinity of the inner wall surface of the furnace. In the range of the diameter D of the rod-like or pipe-shaped heater 6～16Mm, the number n of the juxtaposed heater, to the length L of the stacking plate in the arrangement direction of the heater, L <(D + 20) The batch-type firing furnace according to claim 1 or 2, wherein heaters are arranged side by side so as to have a relationship of xn. As the rod-like or pipe-shaped heater, any of claims 1 to 3, characterized in that a heater made of silicon carbide or graphite or a heater which is further coated with an insulating pipe heater made of the silicon carbide or graphite, A batch-type firing furnace according to claim 1.

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