JPH0626938A - Measuring method of molten steel temperature in continuous casting tundish - Google Patents

Abstract

PURPOSE:To measure molten steel temperature in an tundish by inserting a molybdenum electrode in a molten steel in the tundish, forming a thermocouple by the electrode and a iron material a part of which makes contact with the molten steel in the tundish, and measuring its thermoelectromotive force. CONSTITUTION:A molten steel 6 is poured into a tundish 1, and a molybdenum electrode 4 is inserted thereto. When the level of the molten steel 6 rises and reaches to an iron electrode 12 and the molybdenum electrode 4, a hot contact is formed there, and a thermoelectromotive force proportional to the molten steel temperature is induced in a cold contact. This thermoelectromotive power is inputted to a temperature converter 5, and converted into a standard signal, which is used as a temperature signal to conduct temperature measurement. When the molybdenum electrode 4 is continuously fed after the level of the molten steel 6 reaches to a determined level, the temperature measurement can be continuously performed, and when it is intermittently fed, the temperature measurement can be intermittently performed. Further, since both the electrodes 4, 12 are allowed to directly communicate to each other through the molten steel 6, response delay is extremely shortened, and the temperature measurement can be performed with a response delay within about 0.5sec.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for continuously or intermittently measuring the temperature of molten steel in a tundish during continuous casting of steel.

[0002]

2. Description of the Related Art As is well known, continuous casting of steel is performed by melting a molten steel in a converter or an electric furnace and finely adjusting the components and / or degassing the molten steel in a tundish from a ladle. It is carried out by pouring the molten metal into a continuous casting mold via. At that time, the temperature of the molten steel poured into the mold is a very important factor in preventing variations in the quality of the manufactured slabs and troubles in continuous casting due to a temperature drop during casting. For this reason, the temperature of molten steel in the tundish is measured using a thermocouple charged in a refractory protection tube.

Recently, a tundish equipped with a molten steel heating device has been used as a tundish. In this tundish, the amount of electric power input to the heating device is controlled to heat and raise the temperature of the molten steel in the tundish to suppress a decrease in the molten steel temperature. Even in this case,
The molten steel temperature in the tundish has been measured using a thermocouple inserted in a refractory protection tube to control the input power of the heating device.

As described above, conventionally, the temperature of the molten steel in the tundish has been measured by the thermocouple inserted in the refractory protection tube. However, this method of measuring the molten steel temperature has a time constant of about several minutes due to the heat transfer delay in the refractory, and the melting time of the refractory limits the service life. There was.

On the other hand, by solving such a problem, a molybdenum wire or the like is fed into the molten steel in the tundish, an iron-molybdenum thermocouple is formed at the contact point between the molten steel and molybdenum, and the reference potential on the molybdenum side is formed. A continuous temperature measuring method for molten steel in a tundish for continuous casting of steel has been proposed, in which the steel is taken out from the molybdenum that has been fed and the reference potential on the iron side is taken out from the continuous cast piece. (See Japanese Patent Laid-Open No. 2-89548)

[0006]

The above proposed continuous temperature measurement method for molten steel in a tundish solves the problems of the method for measuring molten steel temperature by a thermocouple inserted in the refractory protection tube described above. However, since the iron side reference potential is taken out directly from the continuous cast piece,
In addition to being unable to measure the temperature of molten steel in the tundish at the initial stage of casting, as described below with reference to the drawings, there is a response delay due to disturbance, which is not yet sufficient. In the figure, 1
Is a tundish, 2 is a dipping nozzle, 3 is a mold, 4 is a molybdenum electrode, 5 is a temperature converter, 6 is molten steel, 7 is a continuous cast piece, and 8 is a support roll for the continuous cast piece 7.

The iron-side reference potential extracting method shown in FIG. 3 is a method of extracting the iron-side reference potential by directly pressing the contact 9 against the continuous cast piece 7. In this method, the contact resistance changes depending on the pressing force of the contactor 9, the surface temperature of the continuous cast piece 7 and the thickness of the surface iron oxide layer 7A of the continuous cast piece 7, or the presence or absence thereof, causing disturbance.

The iron side reference potential extracting method shown in FIG. 4 is a method of extracting the iron side reference potential from the bearing 8A of the support roll 8. In this system, in addition to the system shown in FIG. 3, the contact resistance in the rolling bearing 8A is added to further increase the disturbance.

The iron-side reference potential extracting method shown in FIG. 5 is a method of extracting the iron-side reference potential through the molten steel 6, the solidified shell 7B, the molten powder 10 and the mold copper plate 3A. In this method, the solidification shell 7B, the molten powder 10 and the mold copper plate 3A through a plurality of substances, not to mention the change in the contact resistance of each, in particular, the melting state of the molten powder 10, that is, greatly affected by the melting amount. To be done. Molten powder
No. 10 melts in the vicinity of the meniscus and exhibits conductivity, but becomes vitrified and loses conductivity as it moves away from the meniscus in the drawing direction.

The iron-side reference potential extracting method shown in FIG. 6 is a method of extracting the iron-side reference potential by winding a metal strip 11 around the outer peripheral surface of the immersion nozzle 2. In this method, a refractory immersion nozzle 2 is present between the molten steel 6 and the metal strip 11, and a large temperature difference occurs between the inside and outside of the immersion nozzle 2 and a bias electromotive force is generated in the immersion nozzle 2. Occurs and becomes a disturbance factor.

Therefore, the present invention has been made to solve the above problems, and its purpose is to be able to measure the molten steel temperature in the tundish at the initial stage of continuous casting and to cause disturbance factors of the iron-side reference potential. It is to provide a method for measuring the temperature of molten steel in a tundish for continuous casting, in which the response delay due to is further improved.

[0012]

In order to achieve the above object, a method for measuring the temperature of molten steel in a tundish for continuous casting according to the present invention is a method for continuously or continuously forming a linear body of molybdenum in molten steel in a tundish. By infiltrating intermittently, a thermocouple is formed by this molybdenum linear body and the iron material embedded in the refractory of the tundish so that the molten steel in the tundish and a part thereof come into contact. The temperature of molten steel in the tundish is measured by measuring the thermoelectromotive force of the pair.

In this molten steel temperature measuring method, a molybdenum cermet linear body can be used instead of the molybdenum linear body.

[0014]

In the present invention, the iron-side reference potential is measured by the iron material embedded in the refractory of the tundish so that the molten steel in the tundish and a part thereof come into contact with each other. The response delay due to is improved, and the temperature of the molten steel can be measured from the stage where the molten steel is stored in the tundish, which makes it possible to apply the molten steel heating device for the tundish from the pooling stage.

[0015]

Embodiments of the present invention will be described below with reference to the drawings. In the figure, the same parts as those in the conventional technique will be described with the same reference numerals.

[Embodiment 1] FIG. 1 is a schematic diagram of an apparatus to which the method for measuring the temperature of molten steel in a tundish for continuous casting according to the present invention is applied. Tundish 1 for continuous casting is
It is formed by applying a refractory 1B lining on the inside of the tundish iron skin 1A. Inside the refractory 1B, an iron electrode 12 has its tip 13 slightly protruding from the inner bottom of the tundish 1. It is buried under. The other end of the iron electrode 12 is connected to the temperature converter 5. The molybdenum electrode 4 is connected to the temperature converter 5.

With such a structure, the temperature of molten steel in the tundish for continuous casting is measured as follows.
That is, molten steel 6 is placed in the tundish 1 from the ladle (not shown).
While pouring the molten metal, the molybdenum electrode 4 is inserted. Molten steel 6
When it reaches the iron electrode 12 and the molybdenum electrode 4, the hot junction is formed and a thermoelectromotive force proportional to the molten steel temperature is induced in the cold junction. This thermoelectromotive force is input to the temperature converter 5, converted into a standard signal, and the temperature is measured as a temperature signal. After the level of the molten steel 6 reaches a predetermined level, the temperature of the molybdenum electrode 4 can be continuously measured if it is continuously supplied, or intermittently if it is intermittently supplied. Furthermore, since the electrodes 4 and 12 are directly conducted through the molten steel 6, the response delay is extremely short, and the temperature can be measured with the response delay within about 0.5 seconds.

[Embodiment 2] FIG. 2 is another embodiment to which the method of the present invention is applied. Instead of the tundish for continuous casting shown in the above Embodiment 1, fire resistance is applied to the molten metal falling from the ladle. It is a schematic diagram of an apparatus applied to a tundish for continuous casting having a product weir. The tundish 1 in this figure is for 2 strands, and there is a pouring part 14 in the center and pouring parts 1 on the left and right
5 and 16 are provided and a plurality of molten steel outflow holes (for example, 5) 1
The structure is such that refractory weirs 18 and 19 provided with 7 are provided. Then, in this example, the iron electrode 12 is embedded in the refractory of the one weir 18, and the tip 13 is provided so as to project from above into one molten steel outflow hole 17.

Even in such a structure, the temperature of the molten steel in the tundish for continuous casting is measured in the same manner as in the first embodiment. That is, the molten steel 6 is poured from the ladle (not shown) into the molten metal drop portion 14 of the tundish 1, while the molten metal drop portion 14 is poured.
The molybdenum electrode 4 is inserted into 14 from above. When the level of the molten steel 6 rises and reaches the iron electrode 13 and the molybdenum electrode 4, the temperature of the molten steel 6 is measured by the temperature converter 5 from this point.

In the above embodiment, the tip 13 of the iron electrode 12 is
Although the example of burying the inside of the refractory of the weir 18 has been described, it goes without saying that it may be provided inside the refractory of the tundish 1 as in the case of the first embodiment.

Although the tip 13 of the iron electrode 12 is provided so as to project from above into the molten steel outflow hole 17 of the weir 18, it may be provided so as to project from below.

Furthermore, the above-described first and second embodiments.
In the above, an example of inserting the molybdenum electrode 4 from above the tundish 1 has been described.
Like twelve, it may be provided inside the refractory lining of the tundish 1. In this case, the spot temperature can be measured by reducing the distance between the electrodes 4 and 12.

[0023]

As described above, according to the method for measuring the temperature of molten steel in the tundish for continuous casting according to the present invention, the molybdenum electrode and the iron electrode are directly connected to each other through the molten steel in the tundish. The response delay can be shortened, and the temperature of molten steel can be measured from the stage of storing molten steel in the tundish. Further, this makes it possible to apply the molten steel heating device provided in the tundish from the hot water storage stage. Furthermore, if the molybdenum electrode is fed continuously, the temperature can be continuously measured, and if it is intermittently supplied, the temperature can be intermittently measured.

[Brief description of drawings]

FIG. 1 is a schematic view of an apparatus to which a method for measuring molten steel temperature in a tundish for continuous casting according to the present invention is applied.

FIG. 2 is a schematic view of an apparatus of another embodiment to which the method for measuring molten steel temperature in a tundish for continuous casting according to the present invention is applied, (a) is a front sectional view, and (b) is (a). ) X
It is a -X sectional view.

3A and 3B are explanatory views of an apparatus to which a conventional molten steel temperature measuring method in a tundish for continuous casting is applied, in which FIG. 3A is a front sectional view and FIG. 3B is an enlarged view of a Y portion in FIG. 3A. .

4A and 4B are explanatory views of an apparatus to which a conventional molten steel temperature measuring method in a tundish for continuous casting is applied, in which FIG. 4A is a front sectional view and FIG. 4B is an enlarged ZZ sectional view of FIG. 4A. Is.

5A and 5B are explanatory views of an apparatus to which a molten steel temperature measuring method in a conventional continuous casting tundish is applied, in which FIG. 5A is a front sectional view and FIG. 5B is an enlarged view of a portion P of FIG. .

6A and 6B are explanatory views of an apparatus to which a molten steel temperature measuring method in a conventional continuous casting tundish is applied, in which FIG. 6A is a front sectional view and FIG. 6B is an enlarged view of a Q portion of FIG. .

[Explanation of symbols]

1: Tundish 1A: Tundish iron skin 1
B: refractory lining 2: dipping nozzle 3: mold
4: Molybdenum electrode 5: Temperature converter 6: Molten steel
7: Continuous cast piece 8: Support roll 12: Iron electrode 1
3: Tip of iron electrode 14: Molten part 15, 16: Pouring part 1
7: Molten steel outflow holes 18, 19: Refractory weir

Claims (2)

[Claims] 1. In continuous casting of steel, a linear body of molybdenum is continuously or intermittently infiltrated into molten steel in a tundish, and the linear body of molybdenum and the refractory of the tundish are filled with tantalum. A thermocouple is formed by the molten steel in the dish and the iron material buried so that a part of it contacts.
A method for measuring the temperature of molten steel in a tundish for continuous casting, comprising measuring the temperature of molten steel in the tundish by measuring the thermoelectromotive force of the thermocouple. 2. The method for measuring the temperature of molten steel in a tundish for continuous casting according to claim 1, wherein a molybdenum cermet linear body is used instead of the molybdenum linear body.