JPH08166191A - Shelf plate for baking ceramic product - Google Patents

Abstract

PURPOSE: To improve the spalling resistance without decreasing mechanical load strength as much as possible by branching the end of a slit for improving the resistance in a shelf plate for baking a ceramic product formed with the slit. CONSTITUTION: A slit (cutout) 2 for lessening a thermal stress is formed at the end side of a shelf plate 1 used in the case of baking various ceramic product such as a tile, a pottery, etc., to improve the spalling resistance. In this case, the end of a slit where a thermal stress is mostly concentrated is branched in T, Y or arrow shape. Thus, when the end is branched in a forked shape, the angle θ1 between the extended part of the slit 2 from the end side of the plate 1 and the branched part is set to 45 to 135 deg., and then the stress applied to the end of the slit can be effectively dispersed. The number of the branches is not particularly limited, and may be three or more.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a shelf board used for firing various ceramic products such as tiles, ceramics, sanitary ware, and grindstones.

[0002]

2. Description of the Related Art In recent years, in the firing of various ceramic products such as tiles and ceramics, the firing has been accelerating from the viewpoints of energy saving and improvement of productivity. The shelves used to mount the products are placed in a severe environment due to thermal stress.
That is, in such rapid firing, a temperature difference is likely to occur between the end portion and the central portion of the shelf plate during temperature rise or cooling,
Due to the thermal stress caused by this temperature difference, spalling such as cracks and cracks is likely to occur on the shelf plate. Therefore, conventionally, as shown in FIG. 4, a shelf plate 1 in which a slit (cut) 2 for relaxing thermal stress is formed on an end side to improve spalling resistance is used.

[0003]

By the way, in the above-mentioned conventional shelf plate having slits, the longer the slit length is, the more effective it is in alleviating the thermal stress. However, it is difficult to satisfy both the spalling resistance and the mechanical load strength at a sufficiently satisfactory level. The present invention has been made for the purpose of improving a conventional shelf plate with slits and improving spalling resistance without reducing mechanical load strength as much as possible.

[0004]

According to the present invention, in a shelf board for firing ceramic products in which a slit for improving spalling resistance is formed, the tip of the slit is branched. A shelf board for firing ceramic products (first invention) is provided.

Further, according to the present invention, in a ceramic product baking shelf having slits for improving spalling resistance, the tip of the slits is bent. A baking shelf (second invention) is provided. In the present invention,
The term "slit" refers to a concept including not only a groove penetrating in the thickness direction of the shelf plate but also a groove having a depth of at least half of the thickness of the shelf plate, preferably 75% or more. And

[0006]

The present invention is constructed as described above. First, in the first aspect of the invention, the slit tip portion where the thermal stress is most concentrated is branched in the slitted shelf plate, so that the thermal stress is dispersed and the resistance to the stress is reduced. The polling property is improved. Further, as described above, the longer the slit length is, the more effective it is in relaxing the thermal stress. However, in the case where the slit length (the length including the branched portion) is increased by branching the tip end portion in this way, The degree of decrease in the mechanical load strength of the shelf plate can be suppressed to a smaller extent than in the case where a slit having a length similar to this is formed in a straight shape without branching.

Also in the second invention, similarly, by bending the tip portion, it is possible to increase the slit length and suppress the spalling resistance while suppressing the degree of decrease in the mechanical load strength to be small. As described above, in the shelf plate of the first invention and the second invention, the spalling resistance is improved without lowering the mechanical load strength as much as possible, and cracks are generated at the time of temperature rise or cooling in rapid firing. Occurrence and progress are suppressed.

FIG. 1 is an explanatory view showing an example of the first aspect of the invention, in which a shelf 2 is formed with a slit 2 having a tip end branched into a T shape on each end side. The branch part of the slit 2 is
In addition to this, various forms can be adopted, for example, as shown in FIG.
The preferred forms are those shown in (a) to (e). When the tip portion is branched into two forks such as the T-shape, Y-shape, and arrow-shape shown in FIGS. 2 (a) to (c), the slit extension from each end of the shelf board and the branching portion The angle θ ₁ formed by is 4
It is preferable that the angle be in the range of 5 ° to 135 ° so that the stress applied to the tip of the slit can be effectively dispersed. Also,
The number of branches is not particularly limited, and is three or more, for example, FIG. 2 (d).
It may be branched into four as follows. The lengths and thicknesses (widths) of the respective branched portions do not necessarily have to be the same, and can be appropriately selected according to the shape, size, etc. of the shelf board.
In addition, the tip of the branch part has a rounded corner,
It is also preferable to make the branch point circular as shown in FIG. 2E in order to relieve the stress in these portions.

FIG. 3 is an explanatory view showing an example of the second invention, in which a slit 2 having a bent front end is formed at each end of the shelf 1. The angle θ ₂ formed by the bent portion and the portion from the open end of the slit 2 to the bent point is preferably about 45 ° to 135 °. If this angle is less than 45 °, the stress generated will concentrate on the tip of the slit, and
If it is larger than 35 °, the thermal stress is relieved, but the stress is generated toward the center of the shelf plate, which is not preferable.

In the present invention, the length of the slit cannot be unconditionally determined because its preferable value varies depending on the material and size of the shelf plate, the number and arrangement of the slits, the weight of the article to be placed and the like. First, a tentative guide will be described taking the shelf board according to the first invention of FIG. 1 as an example. FIG. 1 shows a T-shaped slit 2 formed on each end of a rectangular shelf 1 such that four slits 2 are formed in total, and each slit 2 has a slit from its open end to a branch point. The formed side is formed in a direction perpendicular to the side and the branched portion is formed in parallel with the side. In this case, the length C from the open end of the slit 2 to the branch point is defined as the length A of the side parallel to this.
0.2 to 0.6 times, and the length D of the branched portion is 0.01 to 0.3 times the length B of the side parallel to this, the spalling resistance and mechanical load of the shelf board. Balanced strength.

However, this is a tentative guideline, and it is preferable to find a suitable value and use it in consideration of the above-mentioned various conditions. The number and arrangement of the slits are not particularly limited, but it is possible to uniformly form spalling resistance on the entire shelf plate by forming a plurality of slits on opposite edges so as to be point-symmetric with respect to the center of gravity of the shelf plate. It is preferable because it is possible.

The shelf board of the present invention can be obtained by forming a slit having a branched or bent tip as described above on the shelf board base material. Examples of the shelf board base material include oxide-bonded SiC material, nitride-bonded SiC material, alumina material, mullite material, alumina-mullite material, cordierite material, and the like. Further, the shelf plate of the present invention is preferably coated with alumina, mullite or the like on the surface thereof in order to prevent reaction, sticking, etc. with the product to be baked. As a method of forming the slit, a method of press-molding using a mold in which a shape corresponding to the slit is processed so that the slit is formed at the same time when the base material of the shelf board is formed, or after forming the base material of the shelf board Examples include a method of forming slits by mechanical processing using a diamond cutter or the like after calcination or firing. Further, in the present invention, when the shelves are stacked and used, foreign matter such as silica sand scattered on the surface of the shelves is placed on the lower shelves through the slit gaps of the upper shelves. In order to prevent the so-called battering phenomenon of dropping onto the product to be fired, an embedding material such as mullite or alumina may be embedded in the slit gap penetrating in the thickness direction of the shelf plate.

[0013]

The present invention will be described in more detail based on the following examples, but the invention is not intended to be limited to these examples.

(Embodiments 1 to 5) A rectangular shape as shown in FIG. 1 in which the length C from the open end to the branch point and the length D of the branch portion are variously changed at each end side. A 400 mm (= length A) × 350 mm (= length B) × 10 mm (thickness) oxide-bonded silicon carbide based shelf plate 1 in which character-shaped slits 2 were formed was prepared. The slit has a width of 7 mm and penetrates in the thickness direction of the shelf board. In order to evaluate the spalling resistance of these shelves, for each 5 shelves,
After standing still in an electric furnace set at 600 ° C for 30 minutes,
A continuous furnace test of immediately taking out the furnace and naturally cooling it at room temperature was repeated three times, and the number of shelves with cracks or cracks was checked each time. When all five shelf boards were cracked or cracked at the first or second time, the test was terminated at that time. The results are shown in Table 1.

(Embodiment 6) The materials and dimensions are the same as those in Embodiments 1 to 5 except that the slit has a Y-shape (θ ₁ = 45 °) as shown in FIG. 2B. Shelf boards were prepared and the spalling resistance was evaluated in the same manner as in Examples 1-5. The results are shown in Table 1.

(Embodiment 7) A shelf having the same material and size as in Embodiments 1 to 5 except that the slit has an arrow shape (θ ₁ = 135 °) as shown in FIG. 2C. A plate was prepared and the spalling resistance was evaluated in the same manner as in Examples 1-5. The results are shown in Table 1.

(Embodiment 8) The material and dimensions are the same as those in Embodiments 1 to 5 except that the slit is T-shaped as shown in FIG. 2 (e) and the branch point is circular. A certain shelf board was prepared and the spalling resistance was evaluated in the same manner as in Examples 1-5. The results are shown in Table 1.

(Comparative Example 1) A shelf board having the same material and dimensions as in Examples 1 to 5 except that there is no slit was prepared, and the spalling resistance was evaluated in the same manner as in Examples 1 to 5. went. The results are shown in Table 1.

(Comparative Example 2) A shelf board having the same material and size as in Examples 1 to 5 except that the slit has a straight shape without branching as shown in FIG. The spalling resistance was evaluated in the same manner as in Examples 1-5. The results are shown in Table 1.

[0020]

[Table 1]

(Embodiments 9 to 14) A rectangular shape as shown in FIG. 3, each end has a length E from the open end to the bending point, a length F of the bending portion, and an angle θ ₂ formed by these. 400 mm with slit 2 with a bent tip that has various changes
(= Length A) x 350 mm (= Length B) x 10 mm (thickness)
Oxide-bonded silicon carbide based shelf board 1 was prepared. These shelf boards were evaluated for spalling resistance in the same manner as in Examples 1-5. Table 2 shows the results.

[0022]

[Table 2]

[0023]

As described above, according to the present invention, in the shelf for firing ceramic products with slits, the tip end of the slit is branched or bent, so that the mechanical load strength is reduced as much as possible. It has improved spalling properties and can be suitably used as a shelf plate for rapid firing.

[Brief description of drawings]

FIG. 1 is an explanatory diagram showing an embodiment of the first invention.

FIG. 2 is an explanatory view showing an example of a slit form in the first invention.

FIG. 3 is an explanatory diagram showing an embodiment of the second invention.

FIG. 4 is an explanatory view showing a conventional shelf board with slits.

[Explanation of symbols]

 1 ... Shelf board, 2 ... Slit

Claims (2)

[Claims] 1. A shelf plate for burning ceramic products, comprising a slit for forming a slit for improving spalling resistance, wherein a tip portion of the slit is branched. 2. A shelf plate for firing ceramic products, comprising a shelf plate for firing ceramic products in which a slit for improving spalling resistance is formed, wherein a tip portion of the slit is bent.