KR20150014031A - Continuous casting methods - Google Patents

Continuous casting methods Download PDF

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Publication number
KR20150014031A
KR20150014031A KR1020130088683A KR20130088683A KR20150014031A KR 20150014031 A KR20150014031 A KR 20150014031A KR 1020130088683 A KR1020130088683 A KR 1020130088683A KR 20130088683 A KR20130088683 A KR 20130088683A KR 20150014031 A KR20150014031 A KR 20150014031A
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South Korea
Prior art keywords
molten steel
tundish
temperature
ladle
discharge
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KR1020130088683A
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Korean (ko)
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김경수
배정운
안재환
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현대제철 주식회사
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Priority to KR1020130088683A priority Critical patent/KR20150014031A/en
Publication of KR20150014031A publication Critical patent/KR20150014031A/en

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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B22—CASTING; POWDER METALLURGY
    • B22D—CASTING OF METALS; CASTING OF OTHER SUBSTANCES BY THE SAME PROCESSES OR DEVICES
    • B22D11/00—Continuous casting of metals, i.e. casting in indefinite lengths
    • B22D11/16—Controlling or regulating processes or operations

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  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Continuous Casting (AREA)

Abstract

In the present invention, disclosed is a continuous casting method which can set a discharge amount of molten steel more appropriately by calculating a discharge temperature of the molten steel discharged to a continuous casting mold from a tundish. According to an embodiment of the present invention, the continuous casting method comprises the steps of: measuring an initial injection temperature of the molten steel injected into the tundish from a ladle; calculating an injection temperature (T1) of the molten steel injected into the tundish from the ladle using a function with regard to operation time (t) based on the initial injection temperature and an energy change rate of the molten steel inside the ladle; calculating a discharge temperature (T2) of the molten steel discharged to the continuous casting mold from a tundish using a function with regard to the operation time (t) based on the initial injection temperature, the injection temperature (T1), and an energy change rate of the molten steel inside the tundish; and setting a discharge amount of the molten steel discharged to the continuous casting mold from the tundish depending on whether a preset value of the discharge temperature is satisfied.

Description

Continuous Casting Methods {CONTINUOUS CASTING METHODS}

The present invention relates to a continuous casting method.

The molten iron produced in the blast furnace is subjected to a steelmaking process. The steelmaking process produces molten steel through pre-treatment of molten iron, conversion steelmaking, and secondary refining. Molten steel that has undergone steelmaking process is formed into a steel semi-finished product through continuous casting process. In the continuous casting process, molten steel continuously injected into the performance mold is cooled in the performance mold, thereby forming a steel semi-finished product such as a slab. The slab is rolled and formed into a final product such as a rolling coil.

The background art of the present invention is disclosed in Korean Patent Laid-Open Publication No. 10-2012-0074370 (2012.07.06, Continuous Casting Method and Apparatus).

It is an object of the present invention to provide a continuous casting method capable of more appropriately setting the discharge amount of molten steel by calculating the discharge temperature of molten steel discharged from the tundish to the performance mold.

According to an embodiment of the present invention, there is provided a method of manufacturing a tundish, comprising: measuring an initial injection temperature of molten steel injected into a tundish in a ladle; Calculating an injection temperature (T 1 ) of the molten steel injected into the tundish in the ladle as a function of the operating time (t) based on the initial injection temperature and the rate of energy change of the molten steel in the ladle; The discharge temperature (T 2 ) of the molten steel discharged from the tundish to the performance mold is calculated as the operating time t (t) based on the initial injection temperature, the injection temperature (T 1 ), and the energy change rate of the molten steel in the tundish ); And setting a discharge amount of molten steel discharged from the tundish to the performance mold according to whether the discharge temperature satisfies a predetermined value.

The injection temperature T 1 is calculated by satisfying the following equation 1 with respect to the rate of energy change of the molten steel in the ladle, and the initial injection temperature may be the injection temperature T 1 at t = 0.

(1)

Figure pat00001

(ρ: density of molten steel, C p: specific heat of molten steel, V 1: ladle molten steel volume within, α 1: copy in the ladle heat loss constant, A 1: bath surface area of the molten steel in the ladle, T ∞: ambient temperature (atmosphere temperature), β 1: ladle convection in the heat dissipation constant, q 1: per unit time through a unit area of the ladle wall by convection heat of the molten steel in the ladle delivery amount, B 1: the ladle within Γ: constant amount of tundish molten steel injection quantity, Q 1 : amount of molten steel injected per unit time of the tundish)

The discharge temperature (T 2 ) is calculated by satisfying the following equation ( 2 ) with respect to the rate of energy change of molten steel in the tundish, and the initial injection temperature may be equal to the discharge temperature (T 2 ) at t = 0 have.

(2)

Figure pat00002

(ρ: density of molten steel, C p: specific heat of molten steel, V 2: molten steel volume in the tundish, α 2: radiative heat loss in the tundish constant, A 2: bath surface of the molten steel in the tundish area, T ∞: ambient temperature (atmosphere temperature), β 2: convection heat loss in the tundish constant, q 2: unit delivery amount column per hour through unit area of the ladle wall by molten steel convection within the tundish, B 2 : contact area between molten steel and ladle in tundish, γ: constant amount of tundish molten steel injection quantity, Q 1 : injection amount of molten steel injected into tundish per unit time, ω: tundish molten steel discharge constant, Q 2 : The discharge amount per unit time of molten steel discharged from the dish)

The step of setting the discharge amount of the molten steel may include the step of increasing the discharge amount of molten steel discharged from the tundish to the performance mold when the discharge temperature is lower than the lower limit temperature of the preset value.

The lower limit temperature may be set to be higher than the theoretical solidification temperature of molten steel.

The step of setting the discharge amount of the molten steel may include a step of reducing the discharge amount of molten steel discharged from the tundish to the performance mold when the discharge temperature is equal to or higher than the upper limit temperature of the preset value.

The step of setting the discharge amount of the molten steel may include maintaining the discharge amount of molten steel discharged from the tundish to the performance mold when the discharge temperature is equal to or higher than the lower limit temperature and lower than the upper limit temperature have.

According to the embodiments of the present invention, the discharge temperature of molten steel discharged from the tundish to the performance mold can be calculated, and the discharge amount of molten steel can be set more appropriately.

1 is a view showing a continuous casting apparatus;
2 is a flowchart showing a continuous casting method according to an embodiment of the present invention;
3 is a graph showing the temperature change of molten steel in a tundish during one heat.

BRIEF DESCRIPTION OF THE DRAWINGS The present invention is capable of various modifications and various embodiments, and specific embodiments are illustrated in the drawings and described in detail in the detailed description. It is to be understood, however, that the invention is not to be limited to the specific embodiments, but includes all modifications, equivalents, and alternatives falling within the spirit and scope of the invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described in detail with reference to the accompanying drawings.

The terms first, second, etc. may be used to describe various components, but the components should not be limited by the terms. The terms are used only for the purpose of distinguishing one component from another.

The terminology used in this application is used only to describe a specific embodiment and is not intended to limit the invention. The singular expressions include plural expressions unless the context clearly dictates otherwise. In the present application, the terms "comprises" or "having" and the like are used to specify that there is a feature, a number, a step, an operation, an element, a component or a combination thereof described in the specification, But do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, or combinations thereof.

Hereinafter, various embodiments of a continuous casting method according to the present invention will be described in detail with reference to the accompanying drawings. In the following description with reference to the accompanying drawings, the same or corresponding components are denoted by the same reference numerals, The description will be omitted.

1 is a view showing a continuous casting apparatus.

1, the continuous casting apparatus includes a ladle 100, a shroud nozzle 110, a slide gate 120, a tundish 130, an immersion nozzle 140, a stopper 150, and a performance mold 160 .

The ladle 100 receives the molten steel 10 in the inner space and supplies the molten steel 10 to the tundish 130 through the shroud nozzle 110. The ladle 100 may be composed of two or more ladles 100. When the molten steel 10 accommodated in one ladle 100 is completely injected into the tundish 130, 10 are injected into the tundish 130. The operating time required until all the molten steel 10 accommodated in one ladle 100 is injected into the tundish 130 is generally referred to as heat. The amount of molten steel 10 injected through the shroud nozzle 110 can be controlled by the slide gate 120.

The tundish 130 temporarily stores the molten steel 10 injected from the ladle 100 into the internal space so that the molten steel 10 can be continuously discharged to the performance mold 160 even when the ladle 100 is replaced, And supplies it to the performance mold 160 through the nozzle 140. The discharge amount of the molten steel (10) through the immersion nozzle (140) can be controlled by the stopper (150).

2 is a flowchart illustrating a continuous casting method according to an embodiment of the present invention.

Referring to FIG. 2, a continuous casting method according to an embodiment of the present invention includes a step S100 of measuring an initial injection temperature of a molten steel, a step S200 of calculating an injection temperature of the molten steel, A step S300, and a step S400 of setting the discharge amount of the molten steel.

First, the initial injection temperature of the molten steel injected into the ladle is measured (S100).

The initial injection temperature of the molten steel 10 means the temperature of the molten steel 10 stored in the ladle 100 immediately before the molten steel 10 is injected into the tundish 130 from the ladle 100. [

Next, the injection temperature T 1 of the molten steel injected into the tundish from the ladle is calculated (S200).

The injection temperature T 1 of the molten steel 10 can be calculated from the following equation ( 1 ).

[Equation 1]

Figure pat00003

Here, ρ is the density, C p is the volume, t is the operating time, α 1 is a ladle 100 in the molten steel 10 in the specific heat, V 1 of the molten steel 10 is ladle 100 of the molten steel (10) A 1 is the bath surface area of the molten steel 10 in the ladle 100, T ∞ is the atmospheric temperature, β 1 is the convection heat loss constant in the ladle 100, , q 1 is a heat transfer amount per unit time through a unit area of the wall surface of the ladle 100 due to the convection of the molten steel 10 in the ladle 100, B 1 is the heat transfer amount per unit time of the molten steel 10 and ladle 100 in the ladle 100, (T) is the contact area between the tundish (100),? Is the tundish molten steel injection quantity constant, and Q 1 is the injection amount per unit time of molten steel (10) injected into the tundish (130).

The left term in Equation 1 means the rate of energy change of the molten steel 10 in the ladle 100 and the first term in the right side means the radiant energy radiated per unit time from the molten steel 10 in the ladle 100 The second term is the thermal energy released per unit time through the ladle 100 wall surface by the convection of the molten steel 10 in the ladle 100 and the third term is the thermal energy emitted from the ladle 100 to the tundish 130 per unit time Means the heat energy released due to molten steel 10 to be injected. From equation (1), the injection temperature (T 1 ) of the molten steel (10) injected from the ladle (100) to the tundish (130) can be calculated. The injection temperature T 1 of the molten steel 10 may be expressed as a function of the operating time t.

Since the initial injection temperature of molten steel 10 is the injection temperature T 1 at t = 0, the initial injection temperature of molten steel 10 can be used as the initial value of injection temperature T 1 .

Next, the discharge temperature (T 2 ) of the molten steel discharged from the tundish to the performance mold is calculated (S300).

The discharge temperature (T 2 ) of the molten steel 10 can be calculated from the following equation ( 2 ).

&Quot; (2) "

Figure pat00004

Here, ρ is the density, C p is the operating time, α 2 is a tundish volume, t of molten steel 10 in the specific heat, V 2 of the molten steel 10 is the tundish 130 of the molten steel (10) ( A 2 is the bath surface area of the molten steel 10 in the tundish 130, T ∞ is the atmospheric temperature and β 2 is the radiant heat loss constant in the tundish 130 Q 2 is the heat transfer amount per unit time through the unit area of the wall surface of the tundish 130 due to the convection of the molten steel 10 in the tundish 130 and B 2 is the heat transfer amount per unit time in the tundish 130 the contact area between the molten steel 10 and the tundish (130), γ is a tundish molten steel injection amount constant, Q 1 is turned per unit dose of the dish molten steel 10 to be injected into (130), ω is a tundish molten steel flow rate And Q 2 is a discharge amount per unit time of the molten steel 10 discharged from the tundish 130.

In Equation 2, the left side represents the rate of energy change of the molten steel 10 in the tundish 130, and the first term of the right side is emitted per unit time from the bath surface of the molten steel 10 in the tundish 130 The second term is the thermal energy emitted per unit time through the wall surface of the tundish 130 by convection of the molten steel 10 in the tundish 130 and the third term is the radiant energy emitted from the ladle 100 to the tundish 130 And the fourth term means the heat energy discharged due to the molten steel 10 discharged from the tundish 130 to the performance mold 160 per unit time. The discharge temperature T 2 of the molten steel 10 to be injected from the tundish 130 into the playing mold 160 can be calculated from the equation ( 2 ). The discharge temperature T 2 of the molten steel 10 can be expressed as a function of the injection temperature T 1 and the operating time t and the injection temperature T 1 is also a function of the operating time t, The temperature (T 2 ) can be expressed as a function of the operating time t.

The molten steel 10 is injected into the tundish 130 from the ladle 100 and is discharged to the performance mold 160 from the tundish 130 or to the performance mold 160 from the tundish 130 Assuming that the amount of heat loss in the tundish 130 is negligibly small, the initial injection temperature of the molten steel 10 may be used as the initial value of the discharge temperature T 2 .

3 is a graph showing the temperature change of the molten steel in the tundish during one heat.

Referring to FIG. 3, it can be confirmed that the predicted temperature of the molten steel 10 in the tundish 130 calculated by Equation (2) is formed to be similar to the actually measured actual temperature. In this example,? 2 ,? 2 ,? And? May be one.

Next, the discharge amount of the molten steel 10 discharged from the tundish 130 to the performance mold 160 is set according to whether the discharge temperature T 2 of the molten steel satisfies the predetermined value (S400). Here, the preset value refers to a temperature estimated to be suitable for the performance process in advance through experiment or statistical data, and can be appropriately selected according to quality control standards and the like.

If the discharge temperature T 2 of the molten steel is excessively low, a freezing phenomenon may occur in the molten steel bath surface of the tundish 130 or the performance mold 160, leading to a business accident. On the other hand, if the discharge temperature (T 2 ) of the molten steel is too high, a solidified shell with a certain thickness may not be formed, which may cause problems in the performance process.

Therefore, the continuous casting method according to the present embodiment is a method of continuously casting molten steel discharged from the tundish 130 to the performance mold 160 by calculating the discharge temperature T 2 of the molten steel as described above, .

In the continuous casting method according to the present embodiment, when the discharge temperature T 2 of the molten steel is lower than the lower limit temperature of the preset value, the discharge amount of the molten steel 10 discharged from the tundish 130 to the performance mold 160 (S420).

That is, if the discharge temperature T 2 of the molten steel is less than the lower limit of the predetermined value as described above, freezing may occur on the molten steel bath surface of the tundish 130 or the performance mold 160, It is possible to minimize the loss heat quantity by increasing the discharge amount of the molten steel (10).

In this case, in step S420, a tundish preheater (not shown) may be operated to supplement the tundish 130 with appropriate heat.

Here, the lower limit temperature may be set to be higher than the theoretical solidification temperature of the molten steel 10. For example, 10 占 폚 higher than the theoretical solidification temperature of molten steel 10. Here, the theoretical solidification temperature refers to the temperature at which solidification proceeds on the physical properties of the molten steel (10).

As described above, when the discharge temperature of the molten steel 10 is lower than the theoretical solidification temperature, freezing phenomenon may occur on the molten steel bath surface of the tundish 130 or the performance mold 160, leading to a business accident.

Therefore, the lower limit temperature is set to be higher than the theoretical solidification temperature of the molten steel 10, thereby minimizing the freezing phenomenon on the molten steel bath surface of the tundish 130 or the performance mold 160.

In the continuous casting method according to the present embodiment, when the discharge temperature T 2 of the molten steel is equal to or higher than the upper limit temperature of the molten steel, the discharge amount of the molten steel 10 discharged from the tundish 130 to the performance mold 160 (S440).

That is, if the discharge temperature T 2 of molten steel is equal to or higher than the upper limit temperature of the molten steel as described above, the solidified shell having a constant thickness may not be formed. Therefore, .

In this case, it is possible to set the molten steel temperature of the ladle, which is next to be put into the performance process,

In the continuous casting method according to the present embodiment, the molten steel discharged from the tundish 130 to the performance mold 160 may be discharged from the molten steel discharging port (not shown) when the discharge temperature T 2 of the molten steel is equal to or lower than the lower limit temperature 10) (S450).

That is, as described above, if the discharge temperature T 2 of the molten steel is equal to or higher than the lower limit temperature and lower than the upper limit temperature of the predetermined value, it is estimated that the temperature of the molten steel 10 is appropriate for proceeding with the performance process. The discharge amount can be maintained without changing.

As described above, in the continuous casting method according to the present embodiment, it is possible to compare the discharge temperature (T 2 ) of the molten steel with the lower limit temperature and the upper limit temperature among the preset values and set the discharge amount of the molten steel 10 accordingly , More accurate and easy quality control can be achieved.

It will be apparent to those skilled in the art that various modifications and variations can be made in the present invention without departing from the spirit of the invention as set forth in the appended claims. The present invention can be variously modified and changed by those skilled in the art, and it is also within the scope of the present invention.

10: molten steel
100: Ladle
110: shroud nozzle
120: Slide gate
130: Tundish
140: immersion nozzle
150: Stopper
160: playing mold

Claims (7)

Measuring an initial injection temperature of molten steel injected into the tundish from the ladle;
Calculating an injection temperature (T 1 ) of the molten steel injected into the tundish in the ladle as a function of the operating time (t) based on the initial injection temperature and the rate of energy change of the molten steel in the ladle;
The discharge temperature (T 2 ) of the molten steel discharged from the tundish to the performance mold is calculated as the operating time t (t) based on the initial injection temperature, the injection temperature (T 1 ), and the energy change rate of the molten steel in the tundish ); And
Setting a discharge amount of molten steel discharged from the tundish to the performance mold according to whether the discharge temperature satisfies a predetermined value;
/ RTI >
The method according to claim 1,
Wherein the injection temperature T 1 is calculated by satisfying the following equation 1 with respect to the rate of energy change of the molten steel in the ladle and the initial injection temperature is the injection temperature T 1 at t = Continuous casting method.
(1)
Figure pat00005

(ρ: density of molten steel, C p: specific heat of molten steel, V 1: ladle molten steel volume within, α 1: copy in the ladle heat loss constant, A 1: bath surface area of the molten steel in the ladle, T ∞: ambient temperature (atmosphere temperature), β 1: ladle convection in the heat dissipation constant, q 1: per unit time through a unit area of the ladle wall by convection heat of the molten steel in the ladle delivery amount, B 1: the ladle within Γ: constant amount of tundish molten steel injection quantity, Q 1 : amount of molten steel injected per unit time of the tundish)
The method according to claim 1,
The discharge temperature (T 2 ) is calculated by satisfying the following equation ( 2 ) with respect to the rate of energy change of molten steel in the tundish, and the initial injection temperature is equal to the discharge temperature (T 2 ) at t = 0 .
(2)
Figure pat00006

(ρ: density of molten steel, C p: specific heat of molten steel, V 2: molten steel volume in the tundish, α 2: radiative heat loss in the tundish constant, A 2: bath surface of the molten steel in the tundish area, T ∞: ambient temperature (atmosphere temperature), β 2: convection heat loss in the tundish constant, q 2: unit delivery amount column per hour through unit area of the ladle wall by molten steel convection within the tundish, B 2 : contact area between molten steel and ladle in tundish, γ: constant amount of tundish molten steel injection quantity, Q 1 : injection amount of molten steel injected into tundish per unit time, ω: tundish molten steel discharge constant, Q 2 : The discharge amount per unit time of molten steel discharged from the dish)
4. The method according to any one of claims 1 to 3,
Wherein the step of setting the discharge amount of the molten steel comprises:
Increasing the discharge amount of molten steel discharged from the tundish to the performance mold when the discharge temperature is lower than the lower limit temperature of the preset value
Wherein the continuous casting method comprises the steps of:
5. The method of claim 4,
Wherein the lower limit temperature is set to be higher than a theoretical solidification temperature of molten steel.
5. The method of claim 4,
Wherein the step of setting the discharge amount of the molten steel comprises:
Decreasing a discharge amount of molten steel discharged from the tundish to the performance mold when the discharge temperature is equal to or higher than an upper limit temperature of the preset value
Wherein the continuous casting method comprises the steps of:
The method according to claim 6,
Wherein the step of setting the discharge amount of the molten steel comprises:
Maintaining the discharge amount of molten steel discharged from the tundish to the performance mold when the discharge temperature is equal to or higher than the lower limit temperature and lower than the upper limit temperature
Wherein the continuous casting method comprises the steps of:
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Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN114619008A (en) * 2022-03-18 2022-06-14 重庆钢铁股份有限公司 Method for continuously casting and quickly changing tundish of continuous casting machine

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN114619008A (en) * 2022-03-18 2022-06-14 重庆钢铁股份有限公司 Method for continuously casting and quickly changing tundish of continuous casting machine

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