KR101529283B1 - Methods for manufacturing coil - Google Patents
Methods for manufacturing coil Download PDFInfo
- Publication number
- KR101529283B1 KR101529283B1 KR1020130165720A KR20130165720A KR101529283B1 KR 101529283 B1 KR101529283 B1 KR 101529283B1 KR 1020130165720 A KR1020130165720 A KR 1020130165720A KR 20130165720 A KR20130165720 A KR 20130165720A KR 101529283 B1 KR101529283 B1 KR 101529283B1
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- KR
- South Korea
- Prior art keywords
- slab
- rolling
- less
- intervening material
- casting speed
- Prior art date
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Classifications
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
- B21B—ROLLING OF METAL
- B21B1/00—Metal-rolling methods or mills for making semi-finished products of solid or profiled cross-section; Sequence of operations in milling trains; Layout of rolling-mill plant, e.g. grouping of stands; Succession of passes or of sectional pass alternations
- B21B1/46—Metal-rolling methods or mills for making semi-finished products of solid or profiled cross-section; Sequence of operations in milling trains; Layout of rolling-mill plant, e.g. grouping of stands; Succession of passes or of sectional pass alternations for rolling metal immediately subsequent to continuous casting
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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
- B22D11/10—Supplying or treating molten metal
- B22D11/11—Treating the molten metal
-
- 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
Abstract
A coil manufacturing method is disclosed. According to an aspect of the present invention, there is provided a method of manufacturing a slab, comprising: guiding a molten steel into a performance mold to produce a slab; A measuring step of measuring the level of the molten steel in the performance mold at a predetermined time interval; And a casting speed variation amount which is a difference between a maximum value and a minimum value of the casting speed of the slab and a casting speed variation amount which is a difference between the total number of times of measurement of the casting surface level and the number of times of the casting surface level being within a predetermined first range, A calculating step of calculating an interposed material defect index defined as a function of the bath surface level hit rate and the casting speed variation amount; And a determination step of comparing the intervening material defect index with a preset value to determine whether a ratio at which a intervening physical surface defect can occur in a rolling coil manufactured from the slab to a value less than the first rolling thickness is within an allowable range A method for manufacturing a coil is provided.
Description
The present invention relates to a coil manufacturing 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. 10-2011-0109200 (October 10, 2011, continuous casting method).
It is an object of the present invention to provide a coil manufacturing method capable of calculating an interfacial material defect index based on a bath surface level hit ratio and a casting speed fluctuation amount of a slab manufacturing process.
According to an aspect of the present invention, there is provided a method of manufacturing a slab, comprising: guiding a molten steel into a performance mold to produce a slab; A measuring step of measuring the level of the molten steel in the performance mold at a predetermined time interval; And a casting speed variation amount which is a difference between a maximum value and a minimum value of the casting speed of the slab and a casting speed variation amount which is a difference between the total number of times of measurement of the casting surface level and the number of times of the casting surface level being within a predetermined first range, A calculating step of calculating an interposed material defect index defined as a function of the bath surface level hit rate and the casting speed variation amount; And a determination step of comparing the intervening material defect index with a preset value to determine whether a ratio at which a intervening physical surface defect can occur in a rolling coil manufactured from the slab to a value less than the first rolling thickness is within an allowable range A method for manufacturing a coil is provided.
Wherein the molten steel contains 0.01 to 0.08 parts by weight of carbon (C), less than 1.5 parts by weight of manganese (Mn), less than 0.05 parts by weight of silicon (Si), less than 0.02 parts by weight of phosphorus (P) ) Of less than 0.02 parts by weight of iron (Fe) and other inevitable impurities, and the performance mold is formed by continuously casting a slab having a width of 900 mm to 1600 mm and a thickness of 225 mm And may be made of a parallel mold.
The intervening material defect index can be calculated from the following equation (1).
(1)
X = - 0.18 x X1 + 11.1 x X2
X2: casting speed variation (m / min)) (X: interfacial defectiveness index, X1: hot water level hit ratio (%) when the first range is 3 mm above and below the predetermined standard hot water level,
The ratio at which the intervening physical surface defects can occur in the rolling coil manufactured to be less than the first rolling thickness can be calculated from the following equation (2).
(2)
Y = 0.9 x exp (0.2251 x X)
(Y: percentage (%) in which intervening physical surface defects can occur in rolling coils manufactured to be less than the first rolling thickness, and X: interposed physical defect index)
The preset value may be 0.47.
In the determining step, when the intervening material defect index is equal to or larger than the predetermined value, it is determined that the ratio at which the intervening material surface defects can occur in the rolling coil manufactured from the slab to less than the first rolling thickness is determined to be out of the allowable range have.
And rolling the slab to the first rolled thickness or more when the intervening material defect index is equal to or larger than the predetermined value.
According to the embodiments of the present invention, by calculating interposed material defect indexes based on the bath surface level hit ratio and the casting speed fluctuation amount of the slab manufacturing process, intervening physical surface defects are generated in the rolling coils manufactured in the slab less than the first rolling thickness It is possible to judge whether or not the rate at which the user can be located is within the allowable range.
1 is a view illustrating a method of manufacturing a coil according to an embodiment of the present invention.
2 is a view showing a coil manufacturing apparatus.
3 is a view showing the result of measuring the melt surface level of molten steel in the performance mold at predetermined time intervals.
Fig. 4 is a graph showing the correlation between the bake surface level hit ratio and the rate at which intervening material surface defects can occur in rolling coils manufactured below the first rolling thickness.
Figure 5 is a graph showing the correlation between the casting speed variation and the rate at which intervening material surface defects can occur in rolling coils produced below the first rolling thickness.
6 is a graph showing the casting speed of the slab.
Figure 7 is a graph showing the correlation between intervening material defect index and the rate at which intervening material surface defects can occur in rolling coils produced below the first rolling thickness.
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.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, preferred embodiments of a coil manufacturing method according to the present invention will be described in detail with reference to the accompanying drawings, wherein like reference numerals are used to designate identical or corresponding components, The description will be omitted.
1 is a view illustrating a method of manufacturing a coil according to an embodiment of the present invention.
1, a method of manufacturing a coil according to an embodiment of the present invention includes a lecturing step S100, a measuring step S110, a calculating step S120, a determining step S130, and a rolling step S140 .
First, molten steel is poured into a performance mold to manufacture a slab (S100).
2 is a view showing a coil manufacturing apparatus.
2, the
The
The playing
The playing
In the
On the other hand, the upper surface of the
Next, the melt level of the molten steel in the performance mold is measured at a predetermined time interval (S110).
3 is a view showing the result of measuring the melt surface level of molten steel in the performance mold at predetermined time intervals.
Referring to FIG. 3, it can be seen that the level of the melt surface of the
That is, the molten steel level of the
The standard bath surface level of the
The time interval for measuring the level of the melt surface of the
The
That is, the bath surface level of the
Next, a bath surface level hit rate, a casting speed variation, and an interposed material defect index are calculated from the bath surface level measurement data of the molten steel (S120).
Fig. 4 is a graph showing the correlation between the melt surface level hit rate and the rate at which intervening material surface defects can occur in rolling coils produced below the first rolling thickness; Fig. 5 is a graph showing the relationship between the casting speed fluctuation amount and the rolling And the rate at which intervening material surface defects can occur in the coil.
Referring to FIGS. 4 and 5, the fact that the bath surface level hit ratio and the casting speed variation amount are correlated with the ratio at which the intervening material surface defects can occur in the rolling coils manufactured below the first rolling thickness are confirmed by regression analysis .
Inclusion Induced Surface Defect Index is an index of the inclination of the
Therefore, the interfacial defect index can be defined as a function of the bath surface level hit ratio and the casting speed variation amount.
The bake level level hit rate is calculated as a ratio of the number of times that the hot water level is located within the predetermined first range in terms of the total number of times of hot water level, and the unit of the hot water level hit rate is%. In the present embodiment, the first range is set to 3 mm above and below the standard hot-dip level, respectively.
For example, when the total number of bath surface level measurement data obtained during the manufacture of one
The casting speed variation refers to the difference between the maximum value and the minimum value of the casting speed of the
6 is a graph showing the casting speed of the slab.
Referring to FIG. 6, the casting speed of the
Therefore, if the casting speed of the
The intervening material defect index can be calculated from the following equation (1).
(1)
X = - 0.18 x X1 + 11.1 x X2
X1 is the hot water level hit ratio (%) when the first range is 3 mm above and below the standard hot water level, and X2 is the casting speed variation (m / min) do.
Figure 7 is a graph showing the correlation between intervening material defect index and the rate at which intervening material surface defects can occur in rolling coils produced below the first rolling thickness.
Referring to FIG. 7, it is confirmed through a regression analysis that the inter-material defect index calculated from the equation (1) has a correlation with the ratio at which the intervening material surface defects can occur in the rolling coil manufactured at less than the first rolling thickness .
The ratio at which the intervening physical surface defects can occur in the rolling coil can be calculated from the following equation (2).
(2)
Y = 0.9 x exp (0.2251 x X)
In the above formula (2), Y represents a percentage (%) in which intervening physical surface defects can occur in a rolling coil manufactured to be less than the first rolling thickness, and X represents interposed defect index.
Next, the intervening material defect index is compared with a preset value to determine whether the ratio at which the intervening material surface defects can occur in the rolling coil manufactured from the slabs to less than the first rolling thickness is within the allowable range (S130) .
The preset value is set to the minimum value of the intervening material defect index such that the ratio at which the intervening material surface defects can occur in the rolling coil manufactured from the
The allowable range of the rate at which intervening material surface defects can occur depends on the operating conditions. For example, in the case of a hot-rolled coil for a cold rolled steel sheet for automobiles, irregularities in surface defects may occur if irregular surface defects occur irrespective of the degree of the surface defects, but the rate at which intervening physical surface defects can occur depends on the degree of hot- The allowable range of the rate at which intervening material surface defects can occur is required to be controlled to be less than 1%.
If the allowable range of the rate at which intervening material surface defects can occur is less than 1%, the default value of intervening material defect index can be calculated by substituting 1 into Y in the above formula (2). As a result, the preset value becomes 0.47.
That is, when the intervening material defect index is 0.47 or more, the rate at which intervening material surface defects can occur in the rolling coil manufactured from the
Next, the rolled thickness of the slab is controlled and rolled (S140) according to whether the rate at which intervening material surface defects can occur in the rolling coils manufactured from the slab to less than the first rolling thickness is within an allowable range.
As described above, whether or not the ratio at which the intervening material surface defects can occur in the rolling coils manufactured from the
If the intervening material defect index is less than the preset value, the rate at which the intervening material surface defects can occur in the rolling coil manufactured from the
However, when the intervening material defect index is equal to or larger than the predetermined value, the ratio at which the intervening material surface defects can occur in the rolling coil manufactured from the
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
11: Tang surface
100: Tundish
110: immersion nozzle
120: playing mold
130: pinch roll
Claims (7)
A measuring step of measuring the level of the molten steel in the performance mold at a predetermined time interval;
And a casting speed variation amount which is a difference between a maximum value and a minimum value of the casting speed of the slab and a casting speed variation amount which is a difference between the total number of times of measurement of the casting surface level and the number of times of the casting surface level being within a predetermined first range, A calculating step of calculating an interposed material defect index defined as a function of the bath surface level hit rate and the casting speed variation amount; And
And comparing the intervening material defect index with a predetermined value to judge whether or not the ratio at which the intervening material surface defects can occur in the rolling coils manufactured to be less than the first rolling thickness from the slab is within an allowable range and,
Wherein the intervening material defect index is calculated from the following equation (1).
(1)
X = - 0.18 x X1 + 11.1 x X2
(X: intervening material defect index, X1: hot water level hit ratio (%) when the first range is 3 mm above and below the predetermined standard hot water level, X2: casting speed during the production of one slab Variation (m / min))
Wherein the molten steel contains 0.01 to 0.08 parts by weight of carbon (C), less than 1.5 parts by weight of manganese (Mn), less than 0.05 parts by weight of silicon (Si), less than 0.02 parts by weight of phosphorus (P) ) Of less than 0.02 parts by weight of iron (Fe) and other inevitable impurities, and the performance mold is formed by continuously casting a slab having a width of 900 mm to 1600 mm and a thickness of 225 mm Wherein the coil is made of a parallel mold.
The first rolled thickness is 6 mm,
Wherein a ratio at which an intervening material surface defect can occur in a rolling coil manufactured to be less than the first rolling thickness is calculated from the following equation (2).
(2)
Y = 0.9 x exp (0.2251 x X)
(Y: percentage (%) in which intervening physical surface defects can occur in rolling coils manufactured to be less than the first rolling thickness, and X: interposed physical defect index)
Wherein the predetermined value is 0.47.
In the determination step,
Characterized in that when the intervening material defect index is equal to or greater than the predetermined value, it is judged that the ratio at which the intervening material surface defects can occur in the rolling coil manufactured from the slab to less than the first rolling thickness is out of the allowable range Way.
Further comprising a rolling step of rolling the slab to the first rolling thickness or more when the intervening material defect index is equal to or larger than the predetermined value.
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KR1020130165720A KR101529283B1 (en) | 2013-12-27 | 2013-12-27 | Methods for manufacturing coil |
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Citations (4)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
KR20120087523A (en) * | 2011-01-28 | 2012-08-07 | 현대제철 주식회사 | Method for evaluating steel plate quality using level of molten steel |
KR20120110589A (en) * | 2011-03-30 | 2012-10-10 | 현대제철 주식회사 | Evaluation method for quality of steel plate using level of molten steel |
KR20120110586A (en) * | 2011-03-30 | 2012-10-10 | 현대제철 주식회사 | Method for predicting quality of slab using defect index of impurities comeing off submerged entry nozzle |
KR20130120843A (en) * | 2012-04-26 | 2013-11-05 | 현대제철 주식회사 | Method for producing high quality slab |
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Patent Citations (4)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
KR20120087523A (en) * | 2011-01-28 | 2012-08-07 | 현대제철 주식회사 | Method for evaluating steel plate quality using level of molten steel |
KR20120110589A (en) * | 2011-03-30 | 2012-10-10 | 현대제철 주식회사 | Evaluation method for quality of steel plate using level of molten steel |
KR20120110586A (en) * | 2011-03-30 | 2012-10-10 | 현대제철 주식회사 | Method for predicting quality of slab using defect index of impurities comeing off submerged entry nozzle |
KR20130120843A (en) * | 2012-04-26 | 2013-11-05 | 현대제철 주식회사 | Method for producing high quality slab |
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