JPH0145959B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to the structure of an electrode for electrical heating that uniformly heats steel materials such as slabs, billets, blooms, etc. in an electrical heating furnace.

(Prior Art) A slab manufactured by continuous casting or blooming, for example, is heated to a predetermined temperature in a heating furnace and then hot rolled. Heating furnaces are often used to heat slabs using fuel such as LNG, coke oven gas, or kerosene as a heat source, but this causes temperature deviations in the heated slab, for example, temperature differences between the surface layer and the center of the slab. Make a difference. For this reason, a predetermined heating temperature is maintained for a long time to eliminate or reduce temperature deviation. But high temperature, for example 1200
When kept at temperatures above ℃ for a long period of time, steel materials such as slabs become significantly oxidized by oxygen in the furnace, and there is a problem that slag generation increases.

Other heating methods include electric heating furnaces;
There is an energization heating furnace whose heat source is an energization heating device that heats steel materials such as slabs by directly applying electricity to them. This allows heating with less temperature deviation than in a heating furnace that uses fuel as a heating source, and the retention time at a predetermined heating temperature can be shortened.

By the way, in an electric heating device, electric heating electrodes are crimped to both ends of the steel material to be heated, and electricity is applied directly to heat the steel material. However, in electric heating, the electric heating electrodes greatly affect the uniformity of heating. .

As a conventional electrode structure for direct current heating of steel materials, etc., there is one in which a radiant heat absorbing member, such as a cooling channel, is formed integrally with the electrode, as proposed in JP-A-50-106261. Electrodes are crimped onto both ends of the material to absorb local heating at both ends of the material when electrically heated.

(Problem to be Solved by the Invention) However, although this may have certain effects, since the electrode is constantly cooled by the refrigerant flowing through the cooling channel provided integrally inside the electrode,
Both ends of the material to be heated that are in contact with the electrodes are also subjected to the cooling action. For this reason, there is a problem with the temperature distribution in the longitudinal direction of the heated material, such as the temperature at both end surfaces being lower than the central portion of the heated material, resulting in a temperature deviation.

An object of the present invention is to provide an electrode that can uniformly heat a material to be heated without causing temperature deviation when it is heated by directly applying current to the material.

(Means for Solving the Problems) The present invention provides an electrode for an electrical heating device that heats a material to be heated by applying current to both ends of the material. There is provided an electrode for energization heating, characterized in that a cooling device with an attached device is provided so as to be able to move forward and backward.

The present invention will be described in detail below based on one embodiment with reference to the drawings.

In the drawings, reference numeral 1 indicates a material to be heated, for example, a steel material. Reference numeral 2 denotes an electrode, in which a hollow portion 3 is formed, serving as a hollow electrode, and the electrode 2 is in contact with both ends of the material to be heated 1 . The drawings of this embodiment show that the electrode 2 is in contact with one end of the material 1 to be heated.

Reference numeral 4 denotes a cooling device, for example, a cooling header 5, which cools down local heating on the contact surface and its vicinity to equalize the temperature when the electrode 2 is brought into contact with the material to be heated 1 and heated by electricity. be. The cooling device 4 is provided in the hollow portion 3 of the electrode 2 so as to be able to move forward and backward. Further, a heating device, for example a burner 6, can also be provided alongside the cooling device 4. 7 is a refrigerant flow pipe;
8 is a fuel flow pipe.

The cooling device 4 operates as follows.

That is, when heating the heated material 1 with the electrodes 2 in contact with both ends of the heated material 1, the heated material 1 is heated especially in the initial stage of heating.
The joint surface between the electrode 2 and the electrode 2 generates heat due to contact resistance, and the joint becomes locally hotter than other parts. Therefore, the cooling header 5 is moved forward and close to the joint surface to provide a cooling effect and equalize the temperature. do. Further, when it is necessary to preheat the electrode 2 when starting up the energized heating furnace or restarting operation, the cooling device 4 equipped with a burner 6 is used to activate the burner 6 to preheat it. When the electrode 2 is heated in advance and electrical heating is performed in this way, for example, heat transfer from the material to be heated to the electrode 2 is reduced, and the material to be heated 1 can be heated uniformly. The combustion heat from the burner 6 also preheats an energized heating furnace (not shown).

Reference numeral 9 denotes a forward/backward drive device, such as a cylinder, which moves the cooling device 4 forward/backward. Reference numeral 10 denotes an advancement/retraction transmission member that transmits the drive of the advancement/retraction drive device 9 to the cooling device 4 . Reference numeral 11 denotes a temperature measuring device that measures the temperature of the contact portion between the heated material 1 and the electrode 2. 11
-1 is a temperature measuring device that measures the temperature of the intermediate portion of the material to be heated 1. Both temperature measuring devices 11,
The temperature measured in 11-1 is determined by temperature control calculation device 12.
For example, if the temperature difference is larger than a predetermined allowable temperature difference and the temperature of the contact part is high, the advance/retreat drive device 9 is operated to bring the cooling device 4 close to the contact part to cool it. do.

(Effects of the Invention) In the present invention, the electrode 2 is a hollow electrode, and the cooling device 4 through which a refrigerant is passed is provided in the hollow part 3 of the hollow electrode so as to be able to move forward and backward, so that local turbulence of the contact part is caused by electrical heating. Heating is prevented. In addition, the temperature of the contact part between the electrode 2 and the heated material 1 and the temperature of the intermediate part of the heated material 1 are measured, and when the temperature difference is greater than a predetermined allowable temperature difference, for example, the contact part is Figure 3A
As shown in , if the temperature is locally high, the cooling header 5 of the cooling device 4 approaches the contact area and cools it.
As shown in FIG. 3B, the temperature is made uniform to be equal to the intermediate temperature. At that point, the cooling header 5 is retreated from the contact area. Since the material is heated in this manner, there are effects such as uniform heating of the material to be heated without overheating the contact portion with the electrode. When starting up the energized heating furnace, the cooling device 4 equipped with the burner 6 is used to activate the burner 6, so that it can be used to preheat the electrode 2 and the energized heating furnace.

[Brief explanation of drawings]

FIG. 1 is a diagram showing an embodiment of the present invention, FIG. 2 is a diagram showing a case where the cooling device is retracted in an embodiment of the present invention, and FIGS. 3A and B are diagrams showing an embodiment of the present invention. FIG. 3 is a diagram for explaining the effect. 1... Material to be heated, 2... Electrode, 3... Hollow part,
4... Cooling device, 5... Cooling header, 6... Burner, 9... Advance/retreat drive device.

Claims (1)

[Scope of Claims] 1. In an electrode for current heating of a current heating device that heats a material to be heated by applying current by contacting both ends of the material with the electrodes,
An electrode for electrical heating, characterized in that the electrode is provided with a hollow part, and a cooling device is provided in the hollow part so as to be movable forward and backward. 2. The electrical heating electrode according to claim 1, wherein the cooling device is also equipped with a heating device.