JPS5976831A - Finish annealing furnace for steel sheet coil - Google Patents

Abstract

PURPOSE:To reduce the weight of a moving hearth in a finish annealing furnace for a coil of a directional electrical steel sheet or the like and to prevent the failure thereof owing to the deformation by the effect of heat by using lightweight refractories in constituting the part of the hearth except the part supporting heavy load. CONSTITUTION:The support leg parts 3a which support a receiving base 3 for a coil C of a directional steel sheet or the like in the stage of subjecting the coil C to finish annealing in a moving type finish annealing furnace are supported with refractory bricks 2a which are stacked in a cylindrical shape. The part supporting the load of an unner case 4 enclosing the coil C is supported with heat insulating bricks 2b which are stacked into a cylindrical shape. The other part 2g is constituted of a ligthweight refractory material such as ceramic fiber. A moving hearth 2 of the above-mentioned constitution is used. Since the part except the part where the heavy load is supported is constituted of the material 2g, the weight of the hearth 2 is reduced and even if a sealing member 2f enters the lower part, the deformation by the intrusion of the member 2f is absorbed by the deformation of the material 2g itself, whereby the failure of the hearth 2 by the effect of a thermal deformation is prevented.

Description

[Detailed description of the invention] The present invention relates to a steel sheet coil finishing annealing furnace.

For example, in the production of grain-oriented electrical steel sheets, carbon t
A hot rolled steel sheet whose composition has been adjusted to contain 0.085% or less, silicon t-4% or less, sulfur, aluminum, etc., and 0.07% or less of elements for promoting secondary recrystallization is annealed. After performing cold rolling at least once, continuous decarburization annealing is performed, and then an annealing separator, such as a slurry exclusively for Magnesia, is applied, dried, wound into a coil, and final annealed.

The purpose of this final annealing is to induce secondary recrystallization of the steel sheet, to generate a surface film, and to remove impurities in the steel.
After annealing (soaking at 100C or more for 10 hours or more), 450
t: Cool to below.

Figure 1 shows a general mobile finishing annealing furnace 1 for coils to be annealed.
FIG. 2 is an enlarged sectional view taken along the line A-A in FIG. 1, and as shown in FIG. It is placed and covered with an inner case 4, and is sequentially moved through a heating zone inside the furnace 1, a cooling zone inside the furnace 1, and a cooling zone outside the furnace 1 for final annealing.

In this case, the temperature of the moving hearth 2 is also increased from 450 to 1100 C,
As the cooling thermal cycle is repeated, thermal energy is consumed to raise the temperature of the moving hearth 2.

FIG. 3 shows an example of the conventional structure of the movable hearth 2, in which the entire movable hearth 2 supports the load of the coil holder 3, the coil C1 to be annealed, and the inner case 4.

That is, the load applied to the support legs 3a of the coil receiver stand 3 is supported by the refractory bricks 2a stacked in a pyramid shape in the movable hearth 2, and the load of the inner case 4 is
It is supported by insulating bricks 2b stacked on the outer periphery of the refractory bricks 2a, and refractory casters 2c are provided on the outer periphery of the insulating bricks 2b.

A stopper 2d is provided on the side of the insulating brick 2b to receive the lateral expansion of the insulating brick 2b due to thermal expansion at D', and the entire movable hearth 2 is connected to the hearth hardware 2.
It is incorporated into e.

Furthermore, a sealing material 2f such as mullite sand is filled between the lower part of the inner case 4 and the insulating bricks 2b for sealing atmospheric gas. Bulk specific gravity if 2.0 and thermal conductivity (1000C
) is 2゜4 Kca number 4^C1 The bulk specific gravity of the insulation brick 2b is 0.7, and the thermal conductivity (at 1000C) is 0.
．． 55 KeyaJ3/mh C, fireproof casters 2c
The bulk specific gravity of is l. 5. Thermal conductivity (at 1000 C) is 1.4 Kcap/rnh C, and the moving hearth 2 is strong but heavy, and the overall thermal conductivity of the moving hearth 2 is 0.8 Kcal/rnh C. mh C(IQQQ'l::
), and the heat loss was extremely large.

Moreover, when the movable hearth 2 becomes high temperature and expands, the sealing material 2f enters the joints of the insulating bricks 2b, and when the movable hearth 2 cools down, it pushes the insulating bricks 2b horizontally and gradually expands. The insulating bricks 2b expand and eventually form the movable hearth 2
There were problems such as damage.

The present invention has been made to solve the problems of the conventional moving hearth in such a finishing annealing furnace, and an example of its implementation will be described below with reference to FIG. The hearth 2 is formed by stacking refractory bricks 2at in a cylindrical shape, and a stopper 2d is provided on the outer periphery of the lower part.

In addition, as a part of the movable hearth 2 that supports the load of the inner case 4, insulation bricks 2b are stacked in a cylindrical shape, and
A stopper 2d is provided on the outer periphery of the lower part.

Further, other parts of the movable hearth 2 other than the refractory bricks 2a and the heat insulating bricks 2b are made of a large material (2g) with low strength, such as ceramic fiber.

In addition, with respect to the entire cross-sectional area of the movable hearth 2, from the viewpoint of load-bearing strength and energy saving, the total cross-sectional area of the refractory bricks 2a and the heat insulating bricks 2b is approximately 35 meters, and the lightweight refractory (
It is desirable that the iFr area of 2g) be approximately 65%.

Further, when the refractory bricks 2a and the insulation bricks 2b are stacked in a cylindrical shape, it is preferable to provide a fitting stepped portion or a fitting uneven portion so that the upper and lower refractory bricks 2a and the upper and lower insulation bricks 2b fit together with each other.

Now, for example, ceramic fiber as the lightweight refractory (2 g) has a bulk specific gravity of 0.2 and a thermal conductivity (1000
C) is 0.3 K ca-e /mh Cte, the bulk specific gravity is less than 21% of the insulating brick 2b of the refractory brick 2a, and the thermal conductivity is less than that of the refractory brick 2a! B. Since the cross-sectional area of the lightweight refractory material (2 g) is about 65 inches compared to the entire cross-sectional area of the movable hearth 2, the total cross-sectional area of the movable hearth 2 The weight can be reduced to approximately % of the conventional value, and the overall thermal conductivity of the movable hearth 2 can be reduced to approximately % of the conventional value, and therefore heat loss can be significantly reduced, making a significant contribution to energy saving.

Moreover, since the lightweight refractory (2g) has low strength, even if the sealing material 2f enters the joints of the lightweight refractory (2g), it can be absorbed by the deformation of the lightweight refractory (2g) itself, and therefore the movable hearth 2 It will not be damaged.

Incidentally, a coil holder of a grain-oriented electromagnetic steel sheet coil to be finish annealed with plate JlO, 35mm, plate width 1000xi, outer diameter 168021N, inner diameter 500mm, weight 14 tons, in the conventional moving hearth of the finish annealing furnace shown in Fig. 3 is as follows. The same steel plate coils were placed on the stand and the same steel plate coils were heated to 1170 C over 70 hours by placing the coil holders in the moving hearth of the present invention in the finish annealing furnace shown in Fig. 4. When the temperature was raised and cooled to 450 °C over 60 hours, the heat storage in a conventional moving hearth was 9,000 °C per ton of steel plate coil.
0 Kca (3), but the heat storage of the moving hearth of the present invention was able to achieve significant energy savings of 20,000 KCLL-e and 70,000 KCa per ton of steel plate coil.

[Brief explanation of the drawing]

FIG. 1 is a schematic plan view of a mobile finishing annealing furnace, FIG. 2 is an enlarged sectional view taken along line A-A in FIG. 1, FIG. 3 is a sectional view showing an example of a conventional moving hearth, and FIG. The figure is an ffr plan view showing an example of the implementation of the moving hearth of the present invention. Applicant Kawasaki Steel Co., Ltd. Procedural amendment (method) March 1980/Yuhi 1, Case description Japanese Patent Application No. 188850/1982 2, Title of the invention Steel plate coil finishing annealing furnace 3, Person making the amendment 4, Agent Address Kawagishi Building 2, Shinjuku 2-14-61r, Shinjuku-ku, Tokyo
01 'jFebruary 2, 1980 (shipment date 58-2-22)
) Write the procedural amendment as attached.
Name of the invention: Steel plate coil finishing annealing furnace 3, corrector Yasu Hiro Representative: Hiroshi Yagi Hata 4, agent address: 20 P Kawaya Building, 2-14-6' Shinjuku, Shinjuku-ku, Tokyo
No. 1 Name: BR (6815)
Now Ryo Oka Sen 4 de 5, correction order 1 car j
Contents of spontaneous amendment (1) In the specification, from page 2, line 7 to page 2, line 13 r
Correct like a cocoon. 1 is a schematic plan view of a general mobile finishing annealing furnace l for coils to be annealed, and FIG. 2 is an enlarged sectional view taken along line A-A in FIG. are loading and unloading zones, 1
b is a heating zone in the furnace 1, 1c is a cooling zone in the furnace 1, 1d
is a cooling zone outside the furnace 1, and as shown in FIG. In FIG. 1, the heating zone 1b inside the furnace 1, the cooling zone 10% inside the furnace 1, and the cooling zone 1dt outside the furnace 1 are sequentially moved to perform finish annealing. "that's all

Claims (1)

[Claims] In a finishing annealing furnace in which a steel plate coil to be annealed is placed on a coil support stand, covered with an inner case, and annealed in an arbitrary annealing cycle, the parts that support the load such as the coil support stand are made of high-strength refractories. This is a steel plate coil finish annealing furnace, which is characterized by using a light refractory material with low strength for the other hearth parts.