JP3843030B2 - High temperature firing furnace - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a high-temperature firing furnace required for high cleanliness, which is used for firing glass parts, semiconductors, and the like that do not like contamination.
[0002]
[Prior art]
Conventionally, products that require a high degree of cleanness during firing, such as glass parts and semiconductors that do not want to be contaminated, have been fired using a hermetic firing furnace in which the entire inner wall is made of stainless steel such as SUS. It was.
[0003]
[Problems to be solved by the invention]
However, in a high-temperature firing furnace in which the furnace temperature exceeds 700 ° C., there has been a problem that the inner wall made of stainless steel is likely to be distorted due to thermal expansion or the like, and the distortion easily damages the furnace wall. Furthermore, there has been a problem that stainless steel oxidation has an adverse effect on the cleanliness in the furnace.
[0004]
In order to maintain cleanliness in the furnace, in addition to preventing intrusion of dust and the like from outside the furnace, dust generation from the heater used to heat the object to be fired (generated by oxidation of the metal heating element) It is an important issue to prevent in-furnace contamination caused by peeling of the scale.
[0005]
The present invention has been made in view of such circumstances, and its purpose is to prevent distortion due to thermal expansion of the inner wall of the furnace in a high-temperature firing furnace having an airtight structure that requires high cleanliness. In addition, an object of the present invention is to provide a structure that can effectively prevent in-furnace contamination due to oxidation of components and dust generation from a heater.
[0006]
[Means for Solving the Problems]
According to the present invention, a plurality of heat insulating boards formed by covering the surface of a plate-shaped heat insulating material with a stainless steel plate, a structure that is combined in a box shape without bonding them together is installed in a furnace, There is provided a high-temperature firing furnace characterized in that a firing object is fired inside a structure.
[0007]
DETAILED DESCRIPTION OF THE INVENTION
FIG. 1 is an explanatory view showing an example of an embodiment of a high-temperature firing furnace according to the present invention. As described above, in the high-temperature firing furnace 1 of the present invention, a plurality of heat insulating boards 5 in which the surface of the plate-shaped heat insulating material 7 is covered with the stainless steel plate 9 are used, and they are combined in a box shape without being coupled to each other. The structure 11 is installed in the furnace. This structure 11 is included in the inner wall 3 and the outer wall 2 of the furnace, and a water cooling jacket 4 in the gap therebetween.
[0008]
And by baking the to-be-fired material 13 inside the structure 11 comprised from this heat insulation board 5, the heat at the time of baking is shielded moderately by the structure 11. FIG. Therefore, even if the entire inner wall 3 of the furnace is made of stainless steel such as SUS, it is prevented that it is exposed to a high temperature and is distorted or oxidized due to thermal expansion or the like.
[0009]
Note that the structure 11 itself is simply a combination of a plurality of heat insulation boards 5 in a box shape, and is not connected and integrated with each other. Even if they are exposed to a high temperature and thermally expand, there is a slight deviation in the positional relationship between them, and the entire structure 11 is not greatly damaged and damaged.
[0010]
Moreover, since the heat insulation board 5 is comprised by covering the surface of the plate-shaped heat insulating material 7 with the stainless steel board 9, it is friction by thermal expansion etc. on the contact surface of the heat insulation boards 5 when the structure 11 is comprised. Even if this occurs, friction powder is unlikely to be generated, and a clean furnace environment can be maintained. As a specific material of the heat insulating material 7, a fiber board formed of an inorganic binder is preferable.
[0011]
In the present invention, it is important that the heat insulating board 5 has an appropriate thickness. For example, if the thickness of the heat insulating board 5 is increased, the heat shielding property is improved, but the portion of the stainless steel plate 9 facing the structure 11 is heated to the same internal temperature. In this case, even if the structure 11 is composed of a plurality of divided heat insulating boards 5, it is difficult to completely avoid the influence of thermal expansion, and it is difficult to maintain the cleanliness in the furnace by oxidation due to heating. Become.
[0012]
On the other hand, if the thickness of the heat insulation board 5 is reduced, the problems of thermal expansion and oxidation as described above are eliminated. However, since the heat shielding effect is reduced, the heat in the furnace escapes to the water cooling jacket 4 through the inner wall 3, In order to maintain the furnace temperature, an excessive heat generation amount is required, and a heat source having a large heat generation amount corresponding to the heat generation amount is required. The optimum thickness of the heat insulating board 5 depends on the furnace temperature. For example, when the furnace temperature is 700 ° C., the thickness is preferably about 20 mm.
[0013]
As shown in FIG. 1, the high-temperature firing furnace of the present invention includes a metal heating element 15 and Si impregnated SiC that receives heat emitted from the metal heating element 15 and emits far-infrared rays to the object to be fired. It is preferable to use a heater having a structure in which the metal heating element 15 is isolated from the surrounding atmosphere by a muffle plate 17 and a cover 19 made of quartz or the like.
[0014]
Here, Si-impregnated SiC is a refractory material obtained by impregnating SiC with metal Si, and is known to have a high far-infrared emissivity. For this reason, when the heat generated from the metal heating element 15 is received by the muffle plate 17 made of Si-impregnated SiC and far infrared rays are emitted from the muffle plate 17 to the object 13 to be fired, Can be heated.
[0015]
The muffle plate 17 made of Si-impregnated SiC is formed by, for example, forming SiC powder into a predetermined muffle plate shape, and impregnating the obtained molded body with metal Si in a reduced-pressure inert gas atmosphere or vacuum in which metal Si is present. Can be produced by firing. The metal Si melted during firing and impregnated in the molded body binds the SiC particles that are filled in the pores and become the aggregate, and densifies the molded body.
[0016]
The metal heating element 15 as a heating source is isolated from the surrounding atmosphere by the muffle plate 17 and the cover 19. Thereby, the contamination in the furnace by the dust generation from the metal heating element 15 can be effectively prevented. As the metal heating element 15, specifically, an iron chrome aluminum metal wire molded with ceramics can be suitably used.
[0017]
【The invention's effect】
As described above, according to the present invention, distortion and oxidation due to thermal expansion of the inner wall of the furnace can be prevented in a high-temperature firing furnace having an airtight structure that requires a high degree of cleanliness. In addition, it is possible to effectively prevent in-furnace contamination due to dust generation from the heater.
[Brief description of the drawings]
FIG. 1 is an explanatory diagram showing an example of an embodiment of a high-temperature firing furnace according to the present invention.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... High temperature firing furnace, 2 ... Outer wall, 3 ... Inner wall, 4 ... Water cooling jacket, 5 ... Thermal insulation board, 7 ... Thermal insulation material, 9 ... Stainless steel plate, 11 ... Structure, 13 ... Sintered object, 15 ... Metal heating element 17 ... Muffle plate, 19 ... Quartz cover.

Claims (2)

Using a plurality of heat insulation boards that cover the surface of the plate-like heat insulating material with a stainless steel plate, a structure that is combined in a box shape without being bonded to each other is installed in the furnace, and the structure is covered inside the structure. A high-temperature firing furnace characterized in that a fired product is fired. A metal heating element and a muffle plate made of Si-impregnated SiC that receives heat generated from the metal heating element and emits far-infrared rays to the object to be fired, and the metal heating element is surrounded by the muffle plate and the cover. The high-temperature firing furnace according to claim 1, further comprising a heater having a structure isolated from the atmosphere.

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