JP3076381B2 - Thermal insulation structure of vertical induction heating furnace - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a heat insulating material for a vertical induction heating furnace capable of uniformly heating the lower end portion and both side end portions of a billet in the same manner as a central portion.

[0002]

2. Description of the Related Art When a steel slab is induction-heated by a vertical induction heating furnace, both ends and a lower end of the slab are harder to be heated as compared with a central part and the like. ,
JP-A-49-46237 and JP-A-61-2445.
The means described in Japanese Patent Publication No. 6 and the like exists. The former solves the problem by providing a metal member (dummy member) that promotes induction heating close to both side ends of the billet, and the latter solves the problem by providing a combustion burner in addition to the heating coil. I have to do that.

[0003]

However, in these prior arts, an auxiliary device such as a metal member or a combustion burner is provided in the induction heating furnace in order to uniformly heat the steel slab. There is a problem that replacement due to a long life is troublesome.

The present invention has been made in view of the above problems, and an object of the present invention is to provide an economical induction heating furnace which does not require any such ancillary equipment and thus does not require maintenance and inspection.

Inventing the present invention, the inventor of the present invention considered that a vertical induction heating furnace differs from an atmosphere heating furnace such as a gas heating furnace in that the heat dissipation distribution of the furnace body is directly the temperature of the steel slab (heated material). Through experiments and the like, it was recognized that distribution appears and that the vertical induction heating furnace differs from the atmosphere heating furnace in that uniform heating can be determined depending on how uniform the heat dissipation from the steel slab can be maintained. Based on this recognition, by changing the structure of the furnace body heat insulating material, it is possible to partially increase the heat dissipation difference of the steel slab, which has been caused by applying the heat insulating material uniformly, and to partially improve the heat insulating property of the heat insulating material. Therefore, the heat dissipation of the billet is made uniform, and thereby the whole billet is uniformly heated.

FIGS. 5 and 6 show the ratio of the amount of heat dissipation per unit area radiated from the surface of a steel slab in a conventional vertical induction heating furnace in which the heat insulating material of the induction heating furnace is uniformly provided throughout. Things.

In the vertical direction of the steel slab (in the direction indicated by the arrow A in FIG. 5), the amount of heat dissipated in the lower end portion is the largest, and is about twice that in the upper surface portion. The portion where the heat dissipation is large is in the range of 100 to 400 mm above the lower end of the billet. Also, the left and right direction of the billet (the direction of arrow B in FIG. 6)
, The amount of heat dissipated at both ends is the largest, about 1.5 times that near the center. The range is 100 to 400 mm central portion from both ends.

The present invention has been completed based on the results of such experiments.

[0009]

As a means for solving the above-mentioned problems, a vertical induction heating furnace for induction heating the steel slab 1 is provided at a position separated from the steel slab 1 on the inner periphery of the induction heating coil 2.
Within upright surrounding and heat insulating material 3 which is provided, to increase the thermal insulation of the lower end portion facing located 1.2 to 2.0 times the portion up to at least the upper 100mm from the lower end of the steel piece 1, also Among the heat insulating materials 3 provided on the inner circumference of the induction heating coil 2,
It was decided to increase 1.2-1.5 times the heat insulating property of the side end portion opposite located portions from both side ends of the steel strip 1 at least up to the central portion side of 100 mm.

[0010]

[Example] Thickness: 215 mm, width: 1000 mm, length: 1000
After uniformly heating a 0 mm steel slab 1 to 1000 ° C. in a gas heating furnace, a conventional induction heating furnace in which the thermal conductivity of the heat insulating material 3 is entirely uniform, and the vertical induction heating according to the present invention. Heated to 1300 ° C. in both furnaces. At this time, in the heating furnace according to the present invention, the heat conductivity of the heat insulating material 3 at a portion facing the portion 300 mm above the lower end of the steel slab 1 was set to よ り that of the other portions (see FIG. 1). .

The results are shown in FIG. 3 and FIG. FIG.
Is a graph obtained from the induction heating furnace according to the present invention, and FIG. 4 is a graph obtained from the conventional heating furnace. From this experiment, it was found that the temperature difference between the upper end and the lower end of the billet 1 was 40 ° C. in the conventional induction heating furnace, whereas the difference was only 10 ° C. in the heating furnace according to the present invention. It turned out to be. Therefore, from this experiment, it can be proved that the heating furnace according to the present invention can more uniformly heat the billet 1 as compared with the conventional heating furnace.

In the present embodiment, the range in which the heat insulating property of the heat insulating material 3 is enhanced is a portion opposed to a portion 300 mm above the lower end of the steel slab 1 and the heat insulating property is doubled (heat conduction). Although the rate was set to）), it is not limited to these ranges. Further, in order to enhance the heat insulating property of the heat insulating material 3, it is preferable to increase the thickness of the heat insulating material 3 at that portion or to lower the thermal conductivity of the portion by using a different material.

Further, in order to realize more uniform heating of the steel slab 1, it is conceivable to provide the induction heating furnace according to the present invention with the metal member or the combustion burner disclosed in the prior art.

[0014]

As described above, according to the present invention, it is possible to improve the heat insulating properties of a furnace body heat insulating material located in a portion of a vertical induction heating furnace in which a steel slab is hardly heated (a lower end portion and both end portions of the steel slab). As a result, the heating of that portion is promoted, and the steel slab can be induction-heated more uniformly, and the quality can be improved.

[0015] Further, since the conventional auxiliary members such as a metal member and a combustion burner are not used, maintenance and inspection of those devices are not required, and therefore, economical efficiency is excellent.

[0016]

[Brief description of the drawings]

FIG. 1 is a vertical sectional view of a vertical induction heating furnace showing one embodiment of the present invention.

FIG. 2 is a perspective view showing a vertical induction heating furnace.

FIG. 3 is a graph showing a vertical temperature distribution of a steel slab heated by the vertical induction heating furnace according to the present invention.

FIG. 4 is a graph showing a vertical temperature distribution of a steel slab heated by a conventional vertical induction heating furnace.

FIG. 5 is a graph showing a vertical heat dissipation ratio of a steel slab heated by a conventional vertical induction heating furnace.

FIG. 6 is a graph showing the heat dissipation ratio in the left-right direction of a steel slab heated by a conventional vertical induction heating furnace.

[Explanation of symbols]

 1; billet; 2; heating coil; 3; heat insulating material.

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int. Cl. ⁷ , DB name) F27D 1/00 C21D 1/42 F27D 11/06

Claims (1)

(57) [Claims] 1. A vertical induction heating furnace for induction heating a steel slab (1), wherein the steel slab (1) is separated from the steel slab (1) at the inner periphery of a heating coil (2).
It was among the heat insulating material provided in erected surrounding the position (3), the thermal insulation of the lower end portion facing positioned in a portion of up to at least the upper 100mm from the lower end of the steel piece (1) 1.2 to 2. 0 times enhances the of the heat insulator (3), the heat insulating property of the side end portion opposite located portions from both side edge to at least the central portion side 100mm of the steel strip (1) 1.2 to 1.5 Thermal insulation structure of a vertical induction heating furnace that is twice as high.