WO2015099213A1 - 이강종의 연속주조 방법 - Google Patents
이강종의 연속주조 방법 Download PDFInfo
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- WO2015099213A1 WO2015099213A1 PCT/KR2013/012130 KR2013012130W WO2015099213A1 WO 2015099213 A1 WO2015099213 A1 WO 2015099213A1 KR 2013012130 W KR2013012130 W KR 2013012130W WO 2015099213 A1 WO2015099213 A1 WO 2015099213A1
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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
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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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- B—PERFORMING OPERATIONS; TRANSPORTING
- B22—CASTING; POWDER METALLURGY
- B22D—CASTING OF METALS; CASTING OF OTHER SUBSTANCES BY THE SAME PROCESSES OR DEVICES
- B22D19/00—Casting in, on, or around objects which form part of the product
- B22D19/16—Casting in, on, or around objects which form part of the product for making compound objects cast of two or more different metals, e.g. for making rolls for rolling mills
Definitions
- the present invention relates to a continuous casting method of two steel grades, and more particularly, in a continuous casting method of different steel grades, two steel grades that can be automatically cut by foreseeing a mixing portion of a strand prepared by mixing a previous steel grade and a subsequent steel grade. It relates to a continuous casting method of.
- Continuous casting operation of different steel grades is a continuous casting operation using molten steel of a new steel grade (hereinafter, referred to as a subsequent steel grade) having a different component from the molten steel (hereinafter, referred to as a previous steel grade) of the steel grade currently being processed.
- a subsequent steel grade molten steel of a new steel grade
- a previous steel grade molten steel of a previous steel grade
- the molten steel of subsequent steel grades contained in subsequent ladles is supplied to the tundish at the end of the previous steel grade operation.
- the molten steel of the previous steel grade and the molten steel of the subsequent steel grade are mixed, and the mixed molten steel is injected into the mold through a submerged entry nozzle.
- a mixed part produced by mixing two kinds of steels is indispensable in some regions of the cast strand, and the mixed part is cut and reused as scrap metal because most of them do not satisfy the component specifications of the product for sale.
- the length of the mixing section according to the type and combination of the previous steel grade and subsequent steel grades to make a table, and when the operation of the two steel grades, the cut according to the type and combination of the previous steel grade and subsequent steel grades Cutting to length was carried out.
- the mixing part is excessively cut and the area that satisfies the design specification is cut off like the mixing part and discarded, or the mixing part is not cut off and some parts still mix in the product.
- the present invention provides a continuous casting method of two different steel species in the method of continuously casting different steel grades, which can automatically cut by foreseeing the mixing portion of the strand prepared by mixing the previous steel species and the subsequent steel species.
- the present invention provides a continuous casting method that can calculate the position of the mixing portion of the strand, improve the accuracy of the prediction of the position and length of the mixing portion, to prevent product defects due to the mixing portion according to the two kinds of continuous casting.
- the present invention provides a continuous casting method for two steel grades, the method comprising: acquiring in real time the dimensionless relative concentrations of subsequent steel grades with respect to the previous steel grade in the inner and surface portions of the strand to be continuously cast; Calculating positions in the longitudinal direction of the strands having dimensionless relative concentrations of the inner and surface portions obtained in real time; Predicting the mixing portion in the strand by comparing the obtained inner and surface portion dimensionless relative concentrations with reference concentrations, respectively; And cutting the foreseen mixture. It includes.
- the positions of the strands for obtaining the dimensionless relative concentration are the central portion and the surface portion in the height direction of the strands.
- the present invention is a continuous casting method of two steel grades, the height of the strand solidified and continuously cast from the mold by using the relative amount of the previous steel and subsequent steel in the tundish, and the relative amount of the previous steel and the subsequent steel in the mold Acquiring in real time a dimensionless relative concentration of subsequent steel grades relative to the previous steel grade at multiple locations in the direction; Calculating a position in the longitudinal direction of the strand having the dimensionless relative concentration obtained in real time; Predicting a mixing unit in the strand by comparing the obtained dimensionless relative concentrations with reference concentrations, respectively; And cutting the foreseen mixture. It includes.
- the plurality of positions in the height direction of the strand for obtaining the dimensionless relative concentration include a central portion and a surface portion of the strand.
- the step of setting the reference concentration Before the process of obtaining in real time the dimensionless relative concentration of the subsequent steel grade to the previous steel grade in the continuous cast strand, the step of setting the reference concentration, the process of setting the reference concentration, the previous Setting the lowest concentration among the upper limit concentrations for each component of the steel grade as the first reference concentration; Setting the highest concentration among the lower concentrations for each component of the subsequent steel grade as a second reference concentration; It includes.
- the step of calculating the component concentration of the previous steel grade as a lower limit dimensionless concentration and an upper limit dimensionless concentration the step of calculating the component concentration of the previous steel grade as a lower limit dimensionless concentration and an upper limit dimensionless concentration; Setting a minimum dimensionless concentration as a first reference concentration among upper limit dimensionless concentrations for each component of the previous steel grade; Calculating a component concentration of the subsequent steel grade as a lower limit dimensionless concentration and an upper limit dimensionless concentration; And setting the best dimensionless concentration as the second reference concentration among the lower limit dimensionless concentrations for the respective components of the subsequent steel grade.
- the lower limit dimensionless concentration value of the previous steel grade Replacing the upper limit dimensionless concentration value of the previous steel grade, and the upper limit dimensionless concentration value of the previous steel grade is replaced with the lower limit dimensionless concentration value of the previous steel grade;
- calculating each component concentration of the subsequent steel grade as the lower limit dimensionless concentration and the upper limit dimensionless concentration when the lower limit dimensionless concentration of the subsequent steel grade is greater than the upper limit dimensionless concentration of the subsequent steel grade, The dimensionless concentration value is replaced with the upper limit dimensionless concentration value of the subsequent steel grade, the upper limit dimensionless concentration of the subsequent steel grade is replaced with the lower limit dimensionless concentration of the subsequent steel grade; includes.
- At least one of the dimensionless relative concentrations of the obtained central portion and the surface portion is out of the reference concentration, it is determined as a mixed state, and at least one of the dimensionless relative concentrations of the obtained central portion and the surface portion is dimensionless
- the position in the longitudinal direction of the strand having the dimensionless relative concentration at which the relative concentration is out of the reference concentration is determined as the mixing unit.
- the position in the longitudinal direction of the strand where the dimensionless relative concentration of the obtained central portion reaches the reference concentration is determined as a starting point, and the position in the longitudinal direction of the strand where the dimensionless relative concentration of the obtained surface portion reaches the reference concentration. Determine as the end point of the mixing section.
- the dimensionless relative concentration of each of the central portion and the surface portion of the strand is obtained in real time, and the time period from which the opening signal of the subsequent ladle is detected is counted to obtain a reference value. Comparing time and real time; When the dimensionless concentration acquisition time is less than or equal to the reference time, comparing the dimensionless relative concentration of the obtained central portion with a first reference concentration, and comparing the dimensionless relative concentration of the obtained surface portion with a second reference concentration; And when the concentration acquisition time exceeds a reference time, terminating dimensionless relative concentration acquisition of each of the central portion and the surface portion of the strand.
- the detecting of the subsequent ladle opening signal transmitting a virtual ladle opening signal; Detecting a weight of a tundish in real time in millisecond (ms) time from the time point at which the virtual ladle opening signal is sent; Calculating the weight of the tundish detected in millisecond (ms) as the average tundish weight in a predetermined time interval in second (s: second); And setting a subsequent ladle opening time point through a time point at which the average tundish weight continues to rise.
- W td (t) is the weight of the remaining amount of tundish at present
- W td (t- ⁇ t) is the weight of the amount of tungsten remaining at the previous time
- W td (t)-W td (t- ⁇ t) are all greater than or equal to '0'
- t-2 * ⁇ t is determined as the opening time of the subsequent ladle
- Obtaining a dimensionless relative concentration of subsequent steel grades relative to previous steel grades at the center and surface portions of the strand may include calculating an inflow volume flow rate Q td-in of subsequent molten steel in the tundish; Calculating an average dimensionless relative concentration (C td -ave (t + ⁇ t)) of the molten steel in the tundish at this point in time using the inflow volume flow rate Q td-in of the subsequent molten steel in the tundish; By using the mean dimensionless relative concentration (C td-ave (t + ⁇ t)) of the molten steel in the tundish at this time, the dimensionless relative concentration (C td-out (t +) of the molten steel discharged from the tundish at this time Calculating ⁇ t)); Using the dimensionless relative concentration (C td -out (t + ⁇ t)) of the molten steel discharged from the present tundish, the average dimensionless relative concentration of the molten steel in the mold
- W td (t) is the total weight of molten steel in the tundish at the previous time
- W td (t + ⁇ t) is the total weight of the molten steel in the tundish at the present time
- Q td-out is the volumetric flow rate of the molten steel discharged from the tundish
- ⁇ ) L is the density of liquid molten steel
- C td_ave (t) is the mean dimensionless relative concentration of molten steel in the tundish at the previous time
- Q td-in (t) is the inflow volume flow rate of the molten steel flowing into the tundish at the previous time
- C td-in (t) Is the inflow concentration of the subsequent molten steel in the tundish at the previous point in time
- QDd-out (t) the volume of the molten steel discharged from the tundish at the previous point in time
- C td-out (t) is the Molten steel concentration (dimensionless relative concentration) discharged from tundish
- ⁇ L is density of liquid molten steel
- W md (t) is the total weight of molten steel in the mold at the previous time point
- C md-ave (t) is the average dimensionless relative concentration of the molten steel in the mold at the previous time point
- Q md-in (t) is the Inflow volume flow rate of molten steel
- C md-in (t) is the inflow concentration of molten steel in the mold (dimensionless relative concentration) at the previous point
- W md (t + ⁇ t) is the total weight of molten steel in the mold at this point
- Q md -out (t) is the molten volume flow rate discharged from the mold
- C md-out (t) is the dimensionless relative concentration of the strand discharged from the mold at the previous point
- ⁇ L is the density of the liquid molten steel
- the interpolation coefficient f td of Equation 7 is applied to 2.2 ⁇ 0.6, and 0.5 ⁇ 0.2 is applied to the interpolation coefficient f md of Equation 9 above. Apply to calculate the dimensionless relative concentration (C md-out-surface ) of the strand surface.
- the liquid molten steel density is used as the density ( ⁇ L ) value in each of Equations 5, 6, and 8, and 7000 to 7400 kg / m 3 is applied as the molten steel density.
- the strand position at the subsequent ladle opening time is set to the position where the dimensionless relative concentration acquisition of the strand surface portion starts, and the -4 ⁇ 4 m position at the strand position at the subsequent ladle opening time is the dimensionless relative of the center of the strand. Set to the position where concentration acquisition starts.
- the area A md of the cross section of the strand is divided by the solid phase density ( ⁇ s ) of the molten steel. It is calculated by Equation 10 dividing the discharged molten steel volume flow rate (Q md-out ).
- Q md_out is the molten steel volumetric flow rate discharged from the mold, A md is the area of the cross section of the strand, ⁇ s is the solid-state molten steel density, 7600 to 8000 kg / m 3 applied)
- the process of predicting the mixing portion of the strand and the cutting process of the foreseen mixing portion are performed by an online process.
- the dimensionless concentrations of each of the center and surface portions of the strand were obtained and used to derive the length and position of the mixing portion. That is, as in the prior art, without cutting to a constant length irrespective of the operating conditions of the two kinds of steel, the dimensionless concentration of each of the center portion and the surface portion of the strand is obtained each time the two kinds of steel working, and the strand position having the obtained dimensionless concentration is set. Foresee the location and length of the mixing section. Therefore, as the position and length prediction accuracy of the mixing portion is improved, it is possible to prevent a decrease in profitability due to excessive cutting of the mixing portion, and to prevent a problem in which defective products due to undercutting of the mixing portion are shipped to the customer.
- Figure 2 is a view showing the main parts of a typical continuous casting equipment for explaining the process of manufacturing a strand or cast steel through the supply and solidification process of molten steel
- Figure 3 is a flow chart showing a method for predicting two kinds of mixed steel portion of the strand according to an embodiment of the present invention and a method for cutting the mixed portion using the same
- FIG. 6 is a flowchart specifically illustrating a subsequent ladle opening signal detection process according to an embodiment of the present invention.
- FIG. 7 is a flowchart illustrating a method of setting a first reference concentration and a second reference concentration for predicting a mixture of two kinds of strands by a method according to an embodiment of the present invention.
- Figure 8 is a graph showing the dimensionless concentration for each component of the previous grade and subsequent grades, obtained by the method according to an embodiment of the present invention
- FIG. 9 is a graph showing the dimensionless distribution of Cr in the vertical direction (section thickness) and casting direction (length direction) of strands produced by continuous casting of different steel grades.
- FIG. 12 is a flowchart illustrating a method of obtaining strand center and surface dimensionless concentrations according to an embodiment of the present invention.
- FIG. 13 is a graph comparing data obtained by obtaining dimensionless concentrations of a central portion and a surface portion of a strand by a method according to an exemplary embodiment of the present invention, and a result of measuring actual components in the longitudinal direction with respect to the cast strand.
- FIG. 14 is a graph comparing data obtained by predicting a mixing unit by using a prognostic method according to an embodiment of the present invention, and measuring the concentration by taking a foreseen mixing unit.
- 15 is a graph analyzing the length of the mixing unit for one year through the mixing unit predicting method according to an embodiment of the present invention.
- the solidified product which is solidified in the mold and withdrawn or discharged to the outside of the mold and formed in the casting direction is called 'strand' before being cut and 'cut' is called a 'cut'. .
- FIG. 1 is a view showing a general continuous casting equipment.
- Figure 2 is a view showing the main part of the general continuous casting equipment for explaining the process of manufacturing the strand or cast steel through the supply and solidification process of the molten steel.
- the continuous casting facility accommodates refined molten steel and a tundish 200 for receiving molten steel supplied from the movable ladles 100 and 110 and 120 and the ladles 100 and 110 and 120.
- the mold 300 receives molten steel from the tundish 200 and solidifies it to form a strand S having a predetermined shape, and one end is connected to the tundish 200 and at least a portion of the lower part is inserted into the mold 300.
- the nozzle 400 for injecting the molten steel in the tundish 200 into the mold the plurality of rollers 500 for transferring the strands (S) drawn out from the mold 300 in the casting direction, a plurality of rollers 500 Manufactured as a cast steel 700 having a predetermined shape by cutting a plurality of segments 600, the strands (S) continuously produced from the mold 300 to a certain size to spray cooling water to the strands (S) being transported by It includes a cutting machine (800).
- the cutting machine 800 may be a gas torch or a hydraulic shear.
- the tundish 200 has an outlet for supplying molten steel to the mold 300, and a plurality of outlets may be provided according to the continuous casting facility, and the mold 300 is provided in a number corresponding to the number of outlets. Therefore, in the case of a continuous casting facility having a plurality of molds 300, there are a plurality of strands S solidified and drawn out of the mold 300.
- molten steel of different component steel species is accommodated in the first ladle 110 and the second ladle 120, and either ladle 110 or 120 supplies molten steel to the tundish 200.
- the ladle turret (not shown) rotates 180 ° to alternate positions with the other ladle 110 or 120.
- molten steel of different steel grades can be alternately supplied in tundish.
- the molten steel contained in the first ladle 110 is supplied to the tundish 200 to cast first, and at the end of the casting, the molten steel of the second ladle 120 is supplied to the tundish 200 to be cast.
- molten steel hereinafter, referred to as a previous steel grade
- molten steel hereinafter, referred to as a subsequent steel grade
- the previous steel species and the subsequent steel species are mixed to produce a solidified mixing section.
- the concentration of the strand S is obtained in real time by an online system, the position of the strand S having the obtained concentration is calculated, and through this, the mixing unit By predicting the position in real time, it is possible to improve the accuracy of mixing part prediction, and to provide a continuous casting method of two kinds of steel which can automatically cut the mixing part.
- Figure 3 is a flow chart illustrating a method for predicting two kinds of mixed steel portion of the strand according to an embodiment of the present invention and a method for cutting the mixed portion using the same.
- 4 and 5 are flow charts specifically showing the mixing section cutting method in the continuous casting method according to an embodiment of the present invention, and includes the mixing section prediction method and the mixing section cutting method of FIG.
- each strand is supplied with uniform molten steel by a flow control device, such as a dam or a weir, inside the tundish. Therefore, the mixing section cutting method in each strand is applied in the same way. Therefore, only the case of applying one strand will be described.
- the method for predicting two kinds of steel mixture mixture includes storing process variables or process data for continuous casting of different steel species (S100), and ladles (hereinafter, referred to as ladles) in which subsequent steel species are accommodated.
- S100 steel species
- ladles ladles
- the inner and surface portions of the strands are the inner and surface portions in the longitudinal direction (that is, the left and right direction) of the strand or the up and down direction (or the height direction) of the strand which intersects the casting direction, and the inside is the strand. It is a center (center) in the vertical direction (or height direction) of the surface portion may be any one of the upper surface and the lower surface of the strand.
- the dimensionless relative concentration of subsequent grades relative to previous grades is, in other words, the degree or amount of subsequent grades mixed with respect to the previous grades, in other words, the degree to which the previous grades and subsequent grades are mixed, It can be said.
- concentration shows a general density value by dimensionless ratio or dimensionless, and is a density represented by the value of 0 or more and 1 or less. Accordingly, the dimensionless relative concentration of subsequent steel grades relative to the previous steel grades may also be represented by a value of 0 or more and 1 or less.
- the dimensionless concentration of the previous steel grade is zero and the dimensionless concentration of the subsequent steel grade is defined as 1. For example, when the dimensionless relative concentration is 1, it means a case in which the subsequent steel grade is 0% in molten steel or strand, that is, there is no inflow of the subsequent steel grade. Conversely, when the dimensionless relative concentration is 1, the subsequent steel grade is 100% in molten steel or strand. For example, when the dimensionless relative concentration is 0.4, it means that 60% of the previous steel species and 40% of the subsequent steel species are mixed in the molten steel or the strand.
- the first reference concentration and the second reference concentration compared to the dimensionless relative concentrations of each of the central and surface portions of the strand obtained in real time are dimensionless concentration values.
- the mixed steel mixed mixture predicted as described in FIG. 3 according to the dimensionless relative concentration acquisition time of each of the central portion and the surface portion of the strand calculated from a subsequent ladle opening time. And a method of trimming, or not.
- the concentration acquisition time for acquiring the dimensionless relative concentration of each of the center and surface portions of the strand is less than or equal to the reference time
- the dimensionless concentration of each of the obtained central and surface portions is compared with the first and second reference concentrations. Proceeds to the next step to predict the mixing section.
- the concentration acquisition elapsed time of the central portion and the surface portion of the strand passes the reference time
- the concentration acquisition step of each of the central portion and the surface portion is completed.
- the mixing section is cut according to the data table having the preset mixing section cutting length according to the previous steel type and the subsequent steel type, or cut to a predetermined length regardless of the type between the previous steel type and the subsequent steel type.
- the continuous casting method of the steel sheet according to an embodiment of the present invention, the process of storing the process data according to the continuous steel casting (S100), the process of detecting the opening signal of the subsequent ladle (S200), The process of setting the first reference concentration and the second reference concentration for predicting the two kinds of mixed steels of the strand solidified and drawn out from the mold (S300), by obtaining the dimensionless relative concentration of each of the central portion and the surface portion of the strand in real time, Computing a strand position having a dimensionless relative concentration of each of the central portion and the surface portion obtained at the time point (S400), Comparing the non-dimensional relative concentration acquisition time of the central portion and the surface portion of the strand with a reference time (S500) do.
- the step (S300) of setting the first reference concentration and the second reference concentration for the prediction of the mixture of the two kinds of strands solidified and drawn out from the mold was performed. But not limited to this The order of detecting the opening signal of the subsequent ladle (S200) and setting the first reference concentration and the second reference concentration for predicting the two kinds of mixed steel of the strand solidified and drawn out from the mold (S300) may be changed.
- the obtained strand center dimensionless relative concentration and the first reference concentration is compared, and the strand surface portion non-dimensional relative concentration and the second A process of comparing the reference concentration in real time (S600), the process of predicting and determining the position of the mixed portion of the strand according to the comparison result between the obtained central and surface portion dimensionless relative concentration and the first and second reference concentration (S700), And cutting the foreseen mixing part (S1100).
- the process of terminating the dimensionless relative concentration acquisition of each of the central portion and the surface portion of the strand is a type included in the preset cut length table.
- a process corresponding to the combination of the previous steel grade and the subsequent steel grade in operation is found in the mixing section cut length table, and the process is cut to the length (S1200). If the type is not in the cut length table (NO), the process includes cutting to a predetermined length, for example, a maximum length (S1300).
- FIG. 6 is a flowchart specifically illustrating a subsequent ladle opening signal detection process according to an embodiment of the present invention.
- FIG. 7 is a flowchart illustrating a method of setting a first reference concentration and a second reference concentration for predicting a mixture of two kinds of strands by a method according to an exemplary embodiment of the present invention.
- FIG. 8 is a graph showing dimensionless concentrations of components of previous steel grades and subsequent steel grades obtained by the method according to an exemplary embodiment of the present invention.
- 9 is a graph showing a dimensionless concentration distribution of Cr in the vertical direction (section thickness) and the casting direction (length direction) of the cast steel produced by two kinds of continuous casting.
- 10 is a photograph showing the change in concentration in the mold over time during the continuous operation of two steel species.
- FIG. 11 is a result of concentration distribution calculation for the longitudinal direction and the cross section of strands in which final solidification is completed, in consideration of the influence of a mold, not considering the influence of the tundish, in the continuous casting operation of two steel types.
- 12 is a flowchart illustrating a method of obtaining strand center and surface concentrations according to an exemplary embodiment of the present invention.
- FIG. 13 is a graph comparing data obtained from concentrations of central and surface portions of a strand by a method according to an exemplary embodiment of the present invention, and results of measuring actual components in the length direction of the cast strand.
- FIG. 14 is a graph comparing data obtained by predicting a mixing unit by using a prognosis method according to an embodiment of the present invention, and measuring the concentration by taking a foreseen mixing unit.
- step S100 of storing the different steel type continuous casting process data information such as casting conditions, components of the different steel types, and the like, which is variable data for predicting the strand mixing unit in the different steel type operations, is stored. That is, the molten steel residue amount of the tundish, the casting speed, the component concentration of the molten steel (hereinafter referred to as the previous steel grade) of the steel grade currently in operation, and the component concentration of the molten steel of the steel grade subsequently supplied to the tundish (hereinafter referred to as the following steel grade) do.
- Such process data storage is preferably initialized and newly set up and stored at every operation of the steel.
- the casting speed for each strand is stored.
- the dimensionless relative concentration of the strand is obtained from the subsequent ladle opening time. Therefore, it is necessary to accurately detect the signal in which the ladle in which subsequent steel grades are stored is opened.
- the subsequent ladle opening signal detection process S200
- transmitting a virtual opening signal of a subsequent ladle S210
- weighing the tundish in real time from the time when the virtual opening signal of the subsequent ladle is sent.
- the PLC programmable logic system
- the data for 10 minutes from the time when the tundish weight at the time of continuous rise is redetected, and the time when the tundish weight is the lowest is set as a subsequent ladle opening signal.
- this method is a post-action method, and there is a problem in that the opening signal of the subsequent ladle cannot be detected in real time. Therefore, the opening signal of the subsequent ladle is still delayed or an incorrect problem occurs, which becomes a factor of reducing the mixing part prediction accuracy.
- the casting speed and the molten steel remaining amount are lowered according to the two steel operating conditions, and the casting speed and the tundish residual water amount are constant values.
- the PLC programmable logic system
- the tundish weight is measured in millisecond (ms) units, for example, 200 ms units, from the time point at which the subsequent ladle virtual opening signal is transmitted (S220).
- the average tundish weight is calculated based on the tundish weight detected in milliseconds (ms) at regular intervals in units of second (s), for example, one second or two seconds (S230), and the calculated average tundish.
- ms milliseconds
- S230 one second or two seconds
- the dimensionless relative concentrations of the center and surface portions of the strand are calculated from the time point t-2 * ⁇ t, and for this purpose, the residual amount and casting speed of the tundish are stored from the time point t-4 * ⁇ t and mixed in real time. Allow foretelling of wealth.
- the first and second reference concentrations which are compared with the dimensionless relative concentration at the center of the strand and the dimensionless relative concentration at the surface portion of the strand for predicting the mixing portion of the Lijiang species, are dimensionless concentration values.
- a method of calculating first and second reference concentrations according to an embodiment of the present invention will be described with reference to FIG. 7.
- a method of setting a first reference concentration and a second reference concentration for predicting a mixture of two kinds of strands may include receiving concentration data of all components of each of the previous steel grade and the subsequent steel grade.
- Process (S310a, S310b) and calculates the lower limit dimensionless concentration and the upper limit dimensionless concentration for each component of the previous steel grade (S320a), and calculates the lower limit dimensionless concentration and the upper limit dimensionless concentration for each component of the subsequent steel grade.
- the lower limit dimensionless concentration for each component of the previous steel grade is calculated by Equation 1
- the upper limit dimensionless concentration for each component of the previous steel grade is calculated by Equation 2.
- the lower limit dimensionless concentration for each component of the steel grade is then calculated by Equation 3
- the upper limit dimensionless concentration for each component of the steel grade is then calculated by Equation 4.
- the lower limit dimensionless concentration value of the previous grade is The upper limit dimensionless concentration value of the steel grade is replaced by the upper limit dimensionless concentration value of the previous grade.
- the lower limit dimensionless concentration value of the subsequent grades is the upper limit dimensionless concentration value of the subsequent grades, in the same manner.
- the concentration value is replaced with the lower limit dimensionless concentration value of the subsequent steel grade. This applies when the component concentration of the previous grade is higher than the component concentration of the subsequent grade.
- the C concentration of the previous steel grade is 0.4 wt% (0.38 ⁇ 0.42 wt%), and then the C concentration of the steel grade is 0.2 wt% (0.18 ⁇ 0.22 wt%), when the dimensionless conversion, The C dimensionless concentration of the previous steel grade is 0 (0.1 to -0.1). That is, since the upper limit dimensionless concentration of the previous steel grade becomes -0.1 and the lower limit dimensionless concentration of the previous steel grade becomes 0.1, it is changed.
- each component of the previous steel grade has a design specification concentration range
- each component of the subsequent steel grade has a design specification concentration range.
- the concentration of each component of the previous steel grade is the concentration of each component of the molten steel that is first cast in the current steel grade operation, which is a concentration determined through the refining process before the molten steel is supplied to the tundish, It is concentration value included in design standard concentration range of steel grade.
- the concentration of each component of the subsequent steel grade is the concentration of each component of the subsequently supplied molten steel, which is also the concentration determined through the refining process before being supplied to the tundish, and is included in the design specification concentration range of the subsequent steel grade. Concentration value.
- the previous steel grade design specification lower limit concentration, the previous steel grade design specification upper limit concentration, the subsequent steel grade design specification lower limit concentration, the subsequent steel grade design specification upper limit concentration, the previous steel grade concentration and the subsequent steel grade concentration as described above Apply to calculate the lower and upper dimensionless concentrations of the previous steel grades and the lower and upper dimensionless concentrations of subsequent steel grades.
- the lowest dimensionless concentration value among the dimensionless upper limit concentration values for each component of the previous steel grade is set as the first reference concentration, and the highest value among the lower limit dimensionless concentration values for each component of the subsequent steel grade is set.
- the dimensionless concentration value is set as the second reference concentration.
- the first reference concentration is a value compared with the dimensionless relative concentration of the center portion of the strand calculated in real time
- the second reference concentration is a value compared with the dimensionless relative concentration of the surface portion of the strand calculated in real time.
- FIG. 8 is a graph showing dimensionless concentrations of components of previous grades and subsequent grades, calculated by the method according to an embodiment of the present invention.
- C, Mn, Cr are contained in each of the previous steel grades and subsequent steel grades, and the lower limit dimensionless for the C, Mn, Cr components of each of the previous steel grades and the subsequent steel grades according to Equations 1 to 4 described above.
- the concentration and the upper limit dimensionless concentration is calculated as shown in FIG. Referring to FIG. 8, of the upper limit dimensionless concentrations of C, Mn and Cr, the upper limit dimensionless concentration of Cr is smaller than the upper limit dimensionless concentration of C and Mn.
- the upper limit dimensionless concentration of Cr is set to the first reference concentration.
- the lower limit dimensionless concentration of Cr is larger than the upper limit dimensionless concentration of C and Mn.
- the lower limit dimensionless concentration of Cr is set to the second reference concentration. Therefore, according to the example of FIG. 8, the 1st reference density which is the lowest minimum of the dimensionless density
- the dimensionless concentration of the mixing portion is 0.07 or more and 0.95 or less, and the region from the point where the dimensionless relative concentration of the center portion of the strand calculated in real time is 0.07 to the point where the surface portion dimensionless relative concentration is 0.95 is predicted by the mixing portion. .
- the dimensionless concentration of the lowest value among the highest value dimensionless concentrations of each component of the previous steel grade is compared with the dimensionless relative concentration of the central portion calculated in real time, and the lowest value of each component of the subsequent steel grade.
- the reason for comparing the dimensionless concentration of the highest value among the valueless dimensionless concentrations with the dimensionless relative concentration calculated in real time using the second reference concentration as follows will be described.
- the concentration of one end of the mixing portion of the strand where the previous steel grade and the subsequent steel species are mixed and solidified satisfies the design specification concentration of the previous steel grade
- the other end of the mixing portion satisfies the design specification concentration of the subsequent steel grade.
- the region between one end and the other end of the mixing section is outside the design specification concentration range of each of the previous and subsequent grades.
- the concentration varies depending on the vertical direction (cross section thickness direction) and the casting direction (length direction) of the cast steel.
- the up and down position in the strand that is, the dimensionless relative concentration of the central and surface portions, shows a different pattern of tendency. More specifically, after the opening point of the subsequent ladle, a mixture between the previous steel grade and the subsequent steel grade appears on the surface of the strand. However, in the case of the central portion, mixing takes place from the strand position before the opening point of the subsequent ladle. This is because the mixed and remixed molten steel generated through the tundish and the mold is diffused to the center of the unsolidified molten steel layer in the strand. That is, the center portion of the strand starts mixing between the previous steel species and the subsequent steel species from the front point in comparison to the surface portion.
- the dimensionless relative concentration at the center of the strand obtained in real time reaches the lowest dimensionless concentration value (that is, the first reference concentration) among the upper limit dimensionless concentration values for each component of the previous steel grade. Or when it is out of the minimum dimensionless density value (namely, 1st reference density
- the minimum dimensionless density value namely, 1st reference density
- the dimensionless relative concentration of the surface portion in the strand calculated in real time reaches the best dimensionless concentration value (ie, the second reference concentration) among the lower limit dimensionless concentration values for each component of the subsequent steel grade
- the dimensionless concentration value i.e., the second reference concentration
- the strand position is determined as the second cutting position.
- the position in the longitudinal direction of the strand having the lowest dimensionless concentration among the upper limit dimensionless concentration values for each component of the previous steel grade is the starting position of the mixing section, and the dimensionless relative concentration of the center portion is the starting position of the mixing section.
- the longitudinal position of the strand having the highest dimensionless concentration is the end position of the mixing section. Therefore, in the present invention, the lowest dimensionless concentration value among the upper limit dimensionless concentration values for each component of the previous steel grade is called the first reference concentration, and the first reference concentration is compared with the obtained dimensionless relative concentration of the central portion. .
- the best dimensionless concentration is referred to as a second reference concentration, and the second reference concentration is compared with the obtained surface portion dimensionless relative concentration, and thus the Predicted by the mixed portion.
- the length of the strand where the dimensionless relative concentration of the center portion obtained in real time reaches the first reference concentration is the first cut position, and the length of the strand where the dimensionless relative concentration of the surface portion reaches the second reference concentration.
- the mixing part is cut by setting the direction position to the second cutting position.
- the mixing portion is foreseen without regard to the cross-sectional position of the strand, that is, the surface portion and the central portion. That is, conventionally, at one position in the length direction of the strand, the concentration of the center portion and the surface portion was regarded as the same, and the concentration of the strand was obtained. As a result, the location of the mixing section or the accuracy of the prediction of the mixing section is low, so that the mixing section is often mixed with the product and delivered to the customer.
- the concentration of the central portion and the surface portion at one position in the strand length direction is different, and during the continuous casting of two kinds of steel, the non-dimensional relative concentrations of each of the central portion and the surface portion in the strand are respectively obtained to obtain the mixing portion. Foresee.
- the previous steel grades and the subsequent steel grades are mixed in the tundish, wherein some mixed steel grades are discharged while the previous steel grades and the subsequent steel grades are mixed, and the remaining steel grades are discharged.
- the molten steel mixed and remixed in the tundish is discharged into the mold through the immersion nozzle, the molten steel discharged through the immersion nozzle has a turbulent flow.
- the mixed molten steel introduced from the tundish into the mold creates a recirculating flow in the upper region by the molten steel turbulent flow in the mold, thereby repeatedly mixing and remixing in the mold, and the concentration in the mold (See FIG. 10).
- FIG. 11 in the strand solidified and drawn out of the mold, there is a mixing portion in which a previous steel grade and a subsequent steel grade are mixed, and when only the mold thickness is considered without considering the mixing of tundish, when the thickness of the cast steel is 0.4 m, the mixing is performed.
- the length of the part is about 4m.
- the present invention not only the tundish but also the cutting part of the mixing in consideration of the mixing of two kinds of steel in the mold can improve the mixing part cutting accuracy.
- the step (S400) of calculating the longitudinal position of the strand having the corresponding dimensionless relative concentration and the dimensionless relative concentration of each of the central portion and the surface portion in the strand is performed in real time from the time point of the subsequent ladle opening signal detection. Obtaining a dimensionless relative concentration of each of the central portion and the surface portion of (S410) and calculating the position of the strand having the calculated central portion and the surface portion concentration (S420).
- Equation 9 (hereinafter, Equation 9) includes the concentration of steel species discharged from the mold. 'T + ⁇ t' expressed in the following equation refers to the current point and 't' means the previous point.
- the amount of change in molten steel in the tundish may be expressed as the weight change in the tundish divided by the time change ( ⁇ t) and the density of the liquid molten steel.
- the inflow volume flow rate Q td-in of the subsequent molten steel in the tundish is calculated using the concept of the physical tumble inflow variation in the tundish (S411).
- the inflow volume flow rate Q td-in of subsequent molten steel in tundish can be calculated by Equation 5 described below.
- W td (t) is the total weight of the molten steel in the tundish at the previous point
- W td (t + ⁇ t) is the total weight of the molten steel in the tundish at the present time
- Q td-out is the volumetric flow rate of the molten steel discharged from the tundish
- ⁇ L Is the density of the liquid molten steel.
- the total molten steel weight in the tundish at the previous point in time (W td (t)) and the total molten steel weight in the tundish at the present point in time (W td (t + ⁇ t)) are measured in real time from a sensor provided in the lower portion of the tundish,
- the molten steel volume flow rate Q td-out discharged from the tundish is calculated as the sum of the product of the casting speed and the mold cross-sectional size measured from a sensor provided on one side of the strand.
- molten steel is a liquid phase
- a liquid molten steel density of 7000 kg / m 3 to 7400 kg / m 3 is applied, not a solid molten steel density of 7600 kg / m 3 to 8000 kg / m 3 .
- the average dimensionless relative concentration (C td -ave (t + ⁇ t)) of the molten steel in the tundish is calculated using the calculated inflow volume flow rate Q td-in of the subsequent molten steel in the tundish (S412). .
- the molten steel flow generated in tundish can be classified into secondary flow including primary flow and dead zone, and thus the concentration of molten steel according to the molten steel position in tundish. May be different locally.
- the average dimensionless relative concentration of molten steel in tundish is represented by a certain value without considering such a local flow for the purpose of predicting the concentration occurring along the top, bottom, left and right positions of the strand. This is defined as the average dimensionless relative concentration of molten steel in tundish.
- the molten steel mean dimensionless relative concentration (C td -ave (t + ⁇ t)) can be calculated by Equation 6 described below.
- C td-ave (t + ⁇ t) is the average dimensionless relative concentration of molten steel in the tundish at this point
- W td (t) is the total weight of molten steel in the tundish at the previous point
- C td_ave (t) is the turn of the previous point.
- Q td-in (t) is the inflow volume flow rate of molten steel flowing into the tundish at the previous time point
- C td-in (t) is the inflow of subsequent molten steel in the tundish at the previous time point.
- the concentration (dimensionless relative concentration), Q td-out (t) is the molten steel volume flow rate discharged from the tundish at the previous point in time, and C td-out (t) is the molten steel concentration discharged from the tundish at the previous point in time (dimensionless relative).
- Concentration), ⁇ L is the density of the liquid molten steel.
- the inflow volume flow rate Q td-in of subsequent molten steel in tundish applies the value calculated by Equation 5 as described above, and the total weight of molten steel in tundish at the previous time point (W td (t)) .
- the total molten steel weight in the tundish at the present time is a value measured in real time at a certain time interval from the sensor provided in the tundish
- the volume flow rate of the molten steel discharged from the tundish at this time (Q) td-out (t + ⁇ t) can be calculated as the sum of the product of the casting cross-section and the mold cross-sectional size measured from a sensor provided on one side of the strand
- ⁇ L is the liquid molten steel density of 7000 kg / m 3 to 7400 kg / m 3 More specifically, about 7200kg / m 3 applies.
- the concentration of the subsequent molten steel (C td-in (t)) at the previous time point into the tundish is always '1'.
- the initial value of the mean dimensionless relative concentration (C td-ave (t)) of the molten steel in the tundish at the previous time and the initial value of the dimensionless relative concentration (C td-out (t)) of the molten steel discharged from the tundish Is set to '0'.
- the average dimensionless relative concentration C td-ave (t + ⁇ t) of the molten steel in the tundish at this time is calculated based on the initial values set as described above.
- the average dimensionless relative concentration (C td-ave (t + ⁇ t)) of the molten steel in the tundish at this time is applied to the value calculated by Equation 6, and the molten steel discharged from the tundish at this time.
- the value calculated at the present time is applied to the dimensionless relative concentration (C td -out (t + ⁇ t)) of Equation 7 to be described later.
- the present invention calculates the dimensionless relative concentration (C td -out (t + ⁇ t)) of the molten steel discharged from the tundish using the following equation (7).
- C td-out (t + ⁇ t) is the dimensionless relative concentration of molten steel discharged from tundish at this point
- C td _ ave (t + ⁇ t) is the average dimensionless relative concentration of molten steel in tundish at this point
- C td-in (t + ⁇ t) is the dimensionless relative concentration of molten steel flowing into the tundish at this point.
- the average dimensionless relative concentration (C td -out (t + ⁇ t)) of the molten steel in the tundish at this point is calculated and applied by Equation 6 as described above, and the subsequent steel species flowing into the tundish at this point are The dimensionless relative concentration (C td-in ) is 1.
- F td is a tundish interpolation coefficient, and different interpolation coefficients are applied to calculate the dimensionless relative concentration of the strand center and the dimensionless relative concentration of the strand surface. That is, the interpolation coefficient f td_center used for calculating the strand center concentration is 4 ⁇ 2, and the interpolation coefficient f td_surface used for calculating the strand surface portion concentration is 2.2 ⁇ 0.6.
- W md (t) is the total weight of molten steel in the mold at the previous point
- C md-ave (t) is the average dimensionless relative concentration of the molten steel in the mold at the previous point
- Q md-in (t) is the molten steel in the mold at the previous point.
- the flow volume flow rate of C md-in (t) is the inlet concentration of molten steel in the mold (dimensionless relative concentration) at the previous point
- W md (t + ⁇ t) is the total weight of molten steel in the mold at this point
- Q md- out (t) is the molten volume flow rate discharged from the mold
- C md-out (t) is the dimensionless relative concentration of the steel species (ie strands) discharged from the mold at the previous time point
- ⁇ L is the density of the liquid molten steel, a kg / m 3 to 7400 kg / m 3, more specifically, for example, of about 7200kg / m 3.
- the cross section inside the mold is equal to the cross section of the strand.
- the flow rate of the strand (or steel grade) discharged from the mold can be calculated as the sum of the product of the address velocity measured by the sensor located on one side of the strand and the cross-sectional area of the mold.
- the dimensionless relative concentration (C md-in (t)) of the subsequent molten steel at the previous point entering the mold is always equal to the dimensionless relative concentration (C td-out (t)) of the subsequent molten steel from the tundish always exiting the tundish. same.
- the initial value of the mean dimensionless relative concentration (C md-ave (t)) of the molten steel in the mold at the previous point and the initial value of the dimensionless relative concentration (Cmd-out (t)) of the molten steel discharged from the mold is' 0. Is set to '.
- the average dimensionless relative concentration C md-ave (t) of the molten steel in the mold at the present time is calculated.
- the average dimensionless relative concentration (C md-ave (t + ⁇ t)) of the molten steel in the mold at the present time is applied to the value calculated by Equation 8, and the molten steel discharged from the mold at the present time.
- C md-out ( t + ⁇ t) a value calculated at the present time by Equation 9 to be described below is applied.
- the dimensionless relative concentration (C md-out (t + ⁇ t)) of the steel species (ie, strands) discharged from the mold at this point is calculated (S415).
- the dimensionless relative concentration (C md-out (t + ⁇ t)) of the steel species (ie, strands) discharged from the mold at the present time is calculated by the following equation (9).
- C md-out (t + ⁇ t) is the dimensionless relative concentration of the steel species (ie strands) discharged from the mold at this point
- C md _ ave (t + ⁇ t) is the average dimensionless relative of the molten steel in the mold at this point.
- the concentration, C md-in (t + ⁇ t) is the dimensionless relative concentration of molten steel flowing into the mold at this point.
- the dimensionless relative concentration (C md-out (t + ⁇ t)) of the steel species discharged from the mold at this point is a dimensionless relative concentration of the strand solidified and discharged or drawn out of the mold at this point. The value to be calculated through.
- the average dimensionless relative concentration (C md_ave (t + ⁇ t)) of the molten steel in the mold is applied to the value calculated by Equation 8, and f md is an interpolation coefficient, Different interpolation coefficients are applied to calculate the dimensional relative concentration and the dimensionless relative concentration of the surface. That is, the interpolation coefficient f md_center used for calculating the dimensionless relative concentration at the center is 0.7 ⁇ 0.4, and the interpolation coefficient f md_surface used for calculating the dimensionless relative concentration at the strand surface is 0.5 ⁇ 0.2. to be.
- the dimensionless relative concentration (C md-in (t + ⁇ t)) of the molten steel flowing into the mold at the present time is the dimensionless relative concentration (C td-out (t +) of the molten steel discharged from the tundish at this time. ⁇ t)), the value calculated by the above expression (7) is applied.
- mainly liquid molten steel is mainly 7000 kg / m 3 to 7400 kg / m 3 , more preferably about 7200 kg / m 3 is applied to the density value of the liquid molten steel.
- the length direction of the strands having the dimensionless relative concentrations of each of the central and surface portions obtained in real time is calculated (S420).
- the process of setting the position where the dimensionless relative concentration acquisition of the surface portion of the strand starts and the position where the dimensionless relative concentration acquisition of the central portion begins is preceded.
- the mixing portion between the previous steel grade and the mixed steel grade appears on the surface of the strand after the opening point of the subsequent ladle, but in the case of the center, from the strand before the opening point of the subsequent ladle. This is because mixing occurs. That is, the concentration and diffusion of the mixed and remixed molten steel generated through the tundish and the mold to the center of the unsolidified molten steel layer in the strand occurs.
- the center of the strand is mixed between the previous steel and the subsequent steel from the front point in time compared with the surface portion, and the center is mixed at the position of -4 ⁇ 4 m from the strand position at the time of detecting the subsequent ladle opening signal. .
- the position of the strand at the time when the subsequent ladle opening signal is detected is set to the position where the dimensionless relative concentration measurement of the strand surface starts. Then, the position of -4 ⁇ 4m at the strand position at the time of the subsequent ladle opening is set to the position where the dimensionless relative concentration acquisition of the strand center starts.
- the strand having the dimensionless relative concentration of the calculated strand center portion at the present point in time and the strand having the dimensionless relative concentration of the calculated strand surface portion at the present point in time The position is calculated (S420).
- the position of the strand having the dimensionless relative concentration of the calculated surface portion is the product of the mold discharge volume flow rate (Q md-out ) and the liquid molten steel density in the strand, and the area (A md ) of the cross section of the strand and the solid phase density of the molten steel.
- the application of the solid-state density (7600 kg / m 3 to 8000 kg / m 3 ) of molten steel as the density value here is because the longitudinal shrinkage due to solidification of the liquid molten steel is considered.
- the value calculated by the above equation (10) is a length value, and the position of the point moved by the calculated length value based on the meniscus position of the strand is the position of the strand having the surface portion concentration.
- the position of the strand having the calculated central concentration is -4 ⁇ 4 m from the position of the strand having the surface portion concentration obtained at the same time point above.
- the dimensionless relative concentration of the central portion of the strand and the dimensionless relative concentration of the surface portion are obtained in real time, and the longitudinal position of the strand having the dimensionless relative concentration of each of the obtained central portion and the surface portion is obtained.
- the calculation time is counted from the time point at which the dimensionless relative concentrations of the center and surface portions of the strand are calculated, and are compared with the reference time in real time (S500).
- the strands drawn from the mold are transferred in the casting direction, that is, the direction in which the cutting machine is located, as the casting time elapses.
- the mixing portion generated in the strands are gradually closer to the cutting machine as the operation time elapses, and the prediction of the mixing portion must be completed before the mixing portion is located under the cutting machine.
- the calculated dimensionless relative concentration of the center portion reaches the first reference concentration, and the calculated dimensionless relative concentration of the surface portion must reach the second reference concentration.
- a reference drawing time is set in consideration of the casting speed of two kinds of steel, and the reference time is counted from the start point of calculating the dimensionless relative concentration of each of the central portion and the surface portion, so that the mixing portion does not go through the cutting machine. It is time to reach a certain position in front of the cutting machine.
- the predetermined position may vary depending on the location of the cutting machine, the operation equipment or the operating conditions, and the time taken to arrive at the predetermined position at the casting speed in the normal two-steel operation can be estimated.
- This reference time can be obtained through the casting speed, and vary according to the operating equipment or operating conditions as described above.
- the acquisition time is counted in real time, and compared with the reference time in real time (S500), if the acquisition time is within the reference time (yes), the acquired center Compare the dimensionless relative concentration of the first reference concentration and the dimensionless relative concentration and the second reference concentration of the obtained surface portion (S600).
- the position in the longitudinal direction of the strand where the dimensionless relative concentration at the center reaches the first reference concentration is mixed with the start position of the mixing section and the position in the longitudinal direction of the strand where the dimensionless relative concentration at the surface portion reaches the second reference concentration.
- the mixing point position is predicted from the start point to the end point of the mixing section (S700). That is, when the dimensionless relative concentration at the center reaches the first reference concentration, the acquisition of the dimensionless relative concentration at the center is repeated or terminated, and the position of the strand where the dimensionless relative concentration at the center reaches the first reference concentration is determined. Set to the starting position, that is, the first trimming position.
- the acquisition of the dimensionless relative concentration of the surface portion is repeated or terminated, and the position of the strand where the dimensionless relative concentration of the surface portion reaches the second reference concentration is determined.
- the end position that is, the second trimming position.
- the cutting machine cuts each of the first cutting position and the second cutting position, thereby cutting the mixing part predicted from the strand (S1100).
- the dimensionless relative concentration of the center portion does not reach the first reference concentration or if the dimensionless relative concentration of the surface portion does not reach the second reference concentration, acquiring the dimensionless relative concentration of each of the center portion and the surface portion of the strand (S410). And the step of calculating the position of the dimensionless relative concentration (S420) is repeated. Further, for example, when the dimensionless relative concentration of the center portion reaches the first reference concentration, but the dimensionless relative concentration of the surface portion does not reach the second reference concentration, acquisition of the dimensionless relative concentration of the center portion is repeated or terminated. Repeat the process of acquiring the dimensionless relative concentration and calculating the position of the surface.
- the acquisition of the dimensionless relative concentration of the surface portion is repeated or terminated, Repeat the process of obtaining dimensional relative concentration and calculating position.
- the acquisition time is counted in real time, and compared with the reference time in real time (S500), the acquisition time exceeds the reference time ( NO), the dimensionless concentration acquisition of each of the central portion and the surface portion of the strand is finished (S800). Then, it is determined whether the combination between the previous steel grade and the subsequent steel grade currently being operated is a kind included in the preset mixing section cut length table (S900).
- the strand is cut by the cutting length in the mixing section cutting length table (S1200).
- the length of the cut may be cut based on the meniscus position of the strand.
- the cut is made to the maximum cut length based on the meniscus position of the strand (S1300).
- the dimensionless concentration acquisition position is not limited to the central portion and the surface portion dimensionless concentration, it is possible to predict the mixing unit by obtaining the dimensionless concentration at a plurality of positions in the height direction of the strand or positions of different heights of the strand.
- the steel grade that is relatively first casting operation is named the previous steel grade
- the steel grade that is subsequently started casting operation is called the subsequent steel grade.
- the content overlapping with the above description will be omitted or briefly described.
- the peripheral speed is lowered at the end of the operation of the previous steel grade, and when the residual amount of the previous steel grade of the tundish is less than a predetermined amount, the PLC (Programmable Logic System) transmits a virtual opening signal of the subsequent ladle (S200).
- the tundish weight is measured in millisecond (ms) units, for example, 200 ms units, from the time point at which the subsequent ladle virtual opening signal is transmitted (S220).
- an average value of the tundish weights is calculated at intervals of the second and second units of the tundish weight detected in millisecond (ms), for example, one second or two seconds (S230), and the calculated average turn.
- the weight of the dish is analyzed in real time, and it is determined whether it continuously rises (S240). That is, when W td (t)-W td (t- ⁇ t) and W td (t)-W td (t-2 * ⁇ t) are both greater than or equal to '0', t-2 * ⁇ Determine t as the opening time of the subsequent ladle to detect the subsequent ladle opening signal (S200).
- data for predicting the strand mixing unit is stored in the controller of the continuous casting facility (S100). That is, it receives the molten steel remaining amount of the tundish, the casting speed, the component concentration of the molten steel (hereinafter referred to as the previous steel grade) of the steel grade currently being operated, and the component concentration of the molten steel (hereinafter referred to as the subsequent steel grade) of the steel grade subsequently supplied to the tundish. , Save. At this time, the remaining amount and casting speed of the tundish from the time point t-4 * ⁇ t is stored, so that the mixing unit can be predicted in real time. In addition, in the case of continuous casting equipment in which several strands are generated, the operation of each strand is determined and the casting speed in each strand is stored.
- the first reference concentration and the second reference concentration are set for predicting the mixture of the different steel types of the strand solidified and drawn out of the mold by using the respective component concentrations of the previous steel grade and each component concentration data of the subsequent steel grade stored above. (S300). More specifically, the lowest dimensionless concentration value among the upper limit dimensionless concentration values for each component of the previous steel grade is set as the first reference concentration. Further, of the lower limit dimensionless concentration values for each component of subsequent steel grades, the best dimensionless concentration value is set as the second reference concentration. When calculating the dimensionless concentration for each component concentration, if the lower limit dimensionless concentration of the previous grade is larger than the upper limit dimensionless concentration of the previous grade, the lower dimensionless concentration value of the previous grade is the upper limit dimensionless concentration value of the previous grade.
- the upper limit dimensionless concentration value of the previous steel grade is replaced by the lower limit dimensionless concentration value of the previous steel grade.
- the lower limit dimensionless concentration value of the subsequent grades is larger than the upper limit dimensionless concentration of the subsequent grades, the lower limit dimensionless concentration value of the subsequent grades is the upper limit dimensionless concentration value of the subsequent grades, in the same manner.
- the concentration value is replaced with the lower limit dimensionless concentration value of the subsequent steel grade. This applies when the component concentration of the previous grade is higher than the component concentration of the subsequent grade.
- the first reference concentration and the second reference concentration are reference values for predicting the mixing part, and are changed according to the type and combination of the previous steel grade and the subsequent steel grade.
- the dimensionless relative concentration of each of the center and surface portions of the strand is measured in real time from the time when the subsequent ladle opening signal is detected, that is, from t-2 * ⁇ t. And calculates the dimensionless relative concentration calculation time from the time point (t-2 * (DELTA) t) at which the next ladle opening signal is detected (S410). Further, the position of the strand at the time when the subsequent ladle opening signal is sent is set to the position where the dimensionless relative concentration measurement of the strand surface portion starts. Then, the position of -4 ⁇ 4m at the strand position at the time of the subsequent ladle opening is set to the position where the dimensionless relative concentration acquisition of the strand center starts.
- the method for obtaining the dimensionless relative concentration of the central portion and the surface portion first calculating the subsequent molten steel inflow volume flow rate Q td-in in tundish using Equation 5 (S411), calculated Applying the subsequent molten steel inflow volume flow rate Q td-in in tundish to Equation 6 to calculate the average dimensionless relative concentration (C ave (t + ⁇ t)) of the molten steel in tundish at this time (S412) ),
- the mean dimensionless relative concentration (C ave ) of the molten steel in the tundish at the present time is calculated (S413), the dimensionless relative concentration of the molten steel discharged from the tundish calculated at the present time is applied to Equation 8 in the mold at the present
- the dimensionless relative concentration (C md-in (t + ⁇ t)) of the molten steel flowing into the mold at the present time in the equation (8) is the dimensionless relative concentration (C td- ) of the molten steel discharged from the tundish at this time out (t + ⁇ t)), the dimensionless relative concentration (C td -out (t + ⁇ t)) of the molten steel discharged from the tundish at the present time calculated by the equation (7) is introduced into the mold of the equation (8). It is applied to the dimensionless relative concentration of molten steel (C md-in (t + ⁇ t)).
- Equation 7 for calculating the dimensionless relative concentration (C td -out (t + ⁇ t)) of molten steel discharged from the tundish at the present time, and the type of steel discharged from the mold at the present time By applying the interpolation coefficient value for the surface portion calculation to the interpolation coefficient f in each of the equations 9 for calculating the dimensionless relative concentration C md-out (t + ⁇ t), the dimensionless relative portion of the strand surface portion The concentration can be calculated.
- the position in the strand length direction having the calculated dimensionless relative concentration of the central portion and the dimensionless relative concentration of the surface portion is calculated (S420).
- the position of the strand having the dimensionless relative concentration of the calculated surface portion is the product of the mold discharge volume flow rate Q md-out and the liquid molten steel density in the strand, as shown in Equation 10, and the area A md of the cross section of the strand. Calculated by dividing by the product of the solid phase density ( ⁇ s ) of the molten steel.
- the position of the strand having the dimensionless relative concentration of the obtained central portion is -4 ⁇ 4m from the position of the strand having the dimensionless relative concentration of the surface portion calculated at the same point in time.
- the concentration calculation time is calculated while calculating the longitudinal position of the strands having the dimensionless relative concentrations of the obtained center and surface portions, respectively.
- the reference time is compared with the real time (S500). If the calculation time is within the reference time (yes), the dimensionless relative concentration of each of the center and the surface portion of the calculated strand is compared with the first and second reference concentration (S600).
- the concentration calculation is terminated and the mixing unit is foreseen (S700). That is, when the dimensionless relative concentration of the central portion obtained in real time reaches the first reference concentration, the calculation of the longitudinal position of the strand having the dimensionless relative concentration of the central portion is terminated, and the dimensionless relative of the central portion that reaches the first reference concentration is finished. Set the strand position of the concentration to the starting position of the mixing section.
- the cutting machine automatically cuts each of the mixing part starting point and the ending point, thereby cutting out the two kinds of mixing parts from the strand (S1100).
- the dimensionless relative concentration of the center portion does not reach the first reference concentration or if the dimensionless relative concentration of the surface portion does not reach the second reference concentration, acquisition of the dimensionless relative concentration of the center portion and the surface portion of the strand (S410) and the corresponding The position calculation step (S420) of the dimensionless relative concentration is repeated.
- the concentration acquisition and position calculation time exceed the reference time (NO)
- the concentration acquisition and position calculation of the central and surface portion of the strand is terminated (S800).
- the strand is cut by the cut length in the mixing section cut length table (S1200). In this case, the length of the cut may be cut based on the meniscus position of the strand.
- the cutting is performed at a predetermined cutting length, for example, the maximum length, based on the meniscus position of the strand (S1300). After cutting a certain length, the cast before and after the mixing part is set as an ideal material and the component is verified by the component analyzer.
- 15 is a graph analyzing the length of the mixing unit for one year through the mixing unit predicting method according to an embodiment of the present invention.
- the length of the mixing part varies from 0 to 23 m depending on the real time operation method and the concentration of the steel grade. That is, in the present invention, the cutting section was foreseen and trimmed by calculating the length and position of the mixing section for each of the two steel type operations without cutting to a constant length regardless of the operating conditions, as in the prior art. . More specifically, the dimensionless relative concentrations of each of the center and surface portions of the strand were obtained in real time, and the length and position of the mixing portion were derived using the same. Therefore, the present invention can prevent a decrease in profitability due to overcutting of the mixing part, and prevent a problem in which defective products due to undercutting of the mixing part are shipped to the customer.
- Continuous casting method of two kinds of steel according to the present invention can be cut automatically by predicting the mixing portion of the strand prepared by mixing the previous steel and the subsequent steel. Therefore, as the position and length prediction accuracy of the mixing section is improved, it is possible to prevent a decrease in profitability due to excessive cutting of the mixing section, and to prevent defective products caused by undercutting of the mixing section. There is an effect that the productivity of the cast steel is improved.
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Abstract
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- 이강종의 연속주조 방법으로서,연속주조되는 스트랜드의 내부 및 표면부에서 이전 강종에 대한 후속 강종의 무차원 상대 농도를 각각 실시간으로 획득하는 과정;실시간으로 획득되는 내부 및 표면부의 무차원 상대 농도를 가지는 스트랜드의 길이 방향의 위치를 산출하는 과정;상기 획득되는 내부 및 표면부 무차원 상대 농도들을 기준 농도와 각각 비교하여 상기 스트랜드에서 혼합부를 예지하는 과정; 및상기 예지된 혼합부를 절사하는 과정; 을 포함하는 이강종의 연속주조 방법.
- 청구항 1에 있어서,상기 무차원 상대 농도를 획득하는 상기 스트랜드의 위치는 상기 스트랜드의 높이 방향에서의 중심부 및 표면부인 연속주조 방법.
- 이강종의 연속주조 방법으로서,턴디시에서의 이전 강종과 후속 강종의 상대적 량과, 몰드에서의 이전 강종과 후속 강종의 상대적 량을 이용하여, 상기 몰드로부터 응고되어 연속주조되는 스트랜드의 높이 방향에서의 복수 위치에서 각각 이전 강종에 대한 후속 강종의 무차원 상대 농도를 실시간으로 획득하는 과정;실시간으로 획득되는 상기 무차원 상대 농도를 가지는 스트랜드의 길이 방향의 위치를 산출하는 과정;상기 획득되는 상기 무차원 상대 농도들을 기준 농도와 각각 비교하여 상기 스트랜드에서 혼합부를 예지하는 과정; 및상기 예지된 혼합부를 절사하는 과정; 을 포함하는 이강종의 연속주조 방법.
- 청구항 3에 있어서,상기 무차원 상대 농도를 획득하는 상기 스트랜드의 높이 방향에서의 복수 위치는 상기 스트랜드의 중심부 및 표면부를 포함하는 이강종의 연속주조 방법.
- 청구항 1 또는 청구항 3에 있어서,상기 연속주조되는 스트랜드에서 이전 강종에 대한 후속 강종의 무차원 상대 농도를 실시간으로 획득하는 과정 전에, 상기 기준 농도를 설정하는 과정을 포함하고,상기 기준 농도를 설정하는 과정은,상기 이전(以前) 강종의 각 성분들에 대한 상한 농도들 중에서 최하한 농도를 제 1 기준 농도로 설정하는 과정;상기 후속 강종의 각 성분들에 대한 하한 농도들 중에서 최상한 농도를 제 2 기준 농도로 설정하는 과정;을 포함하는 이강종의 연속주조 방법.
- 청구항 5에 있어서,상기 제 1 기준 농도 및 제 2 기준 농도를 설정하는 과정에 있어서,상기 이전 강종의 성분 농도를 하한 무차원 농도와 상한 무차원 농도로 산출하는 과정;상기 이전 강종의 각 성분들에 대한 상한 무차원 농도 중, 최하한 무차원 농도를 제 1 기준 농도로 설정하는 과정;상기 후속 강종의 성분 농도를 하한 무차원 농도와 상한 무차원 농도로 산출하는 과정;상기 후속 강종의 각 성분들에 대한 하한 무차원 농도 중, 최상한 무차원 농도를 제 2 기준 농도로 설정하는 과정;을 포함하는 이강종의 연속주조 방법.
- 청구항 6에 있어서,상기 이전 강종의 각 성분 농도를 하한 무차원 농도와 상한 무차원 농도로 산출하는데 있어서,상기 이전 강종의 하한 무차원 농도가 이전 강종의 상한 무차원 농도보다 클 경우, 이전 강종의 하한 무차원 농도값은 이전 강종의 상한 무차원 농도값으로 치환하고, 이전 강종의 상한 무차원 농도값은 이전 강종의 하한 무차원 농도값으로 치환하는 과정;을 포함하고,상기 후속 강종의 각 성분 농도를 하한 무차원 농도와 상한 무차원 농도로 산출하는데 있어서,상기 후속 강종의 하한 무차원 농도가 후속 강종의 상한 무차원 농도보다 클 경우, 후속 강종의 하한 무차원 농도값은 후속 강종의 상한 무차원 농도값으로 치환하고, 후속 강종의 상한 무차원 농도는 후속 강종의 하한 무차원 농도로 치환하는 과정;을 포함하는 이강종의 연속주조 방법.
- 청구항 2 또는 청구항 4에 있어서,상기 획득되는 중심부 및 표면부의 무차원 상대 농도 중 적어도 어느 하나의 무차원 상대 농도가 기준 농도를 벗어나면 혼합 상태로 판단하고,상기 획득되는 중심부 및 표면부의 무차원 상대 농도 중 적어도 어느 하나의 무차원 상대 농도가 기준 농도를 벗어나는 무차원 상대 농도를 가지는 스트랜드의 길이 방향의 위치를 혼합부로 판단하는 이강종의 연속주조 방법.
- 청구항 8에 있어서,상기 획득되는 중심부의 무차원 상대 농도가 기준 농도에 도달하는 스트랜드의 길이 방향의 위치를 혼합부의 시작점으로 판단하고,상기 획득되는 표면부의 무차원 상대 농도가 기준 농도에 도달하는 스트랜드의 길이 방향의 위치를 혼합부의 종료점으로 판단하는 이강종의 연속주조 방법.
- 청구항 2 또는 청구항 4에 있어서,상기 이전 강종에 대한 후속 강종의 무차원 상대 농도를 획득하는 과정 전에,턴디시의 용강 잔탕량, 주조 속도, 이전 강종 및 후속 강종 각각의 농도 데이타를 온라인(Online)으로 전송받아, 저장하는 과정; 및후속 래들의 개공 신호를 검출하는 과정을 포함하는 과정;을 포함하는 이강종의 연속주조 방법.
- 청구항 10에 있어서,상기 후속 래들의 개공 신호가 검출되는 시점으로부터 상기 스트랜드의 중심부 및 표면부 각각의 무차원 상대 농도를 실시간으로 획득하고,상기 후속 래들의 개공 신호가 검출되는 시점으로부터 무차원 농도 획득 시간을 카운트하여 기준 시간과 실시간으로 비교하는 과정;상기 무차원 농도 획득 시간이 기준 시간 이하인 경우, 상기 획득된 중심부의 무차원 상대 농도를 제 1 기준 농도와 비교하고, 상기 획득된 표면부의 무차원 상대 농도를 제 2 기준 농도와 비교하는 과정;상기 농도 획득 시간이 기준 시간을 초과하는 경우, 상기 스트랜드의 중심부 및 표면부 각각의 무차원 상대 농도 획득을 종료하는 과정;을 포함하는 이강종의 연속주조 방법.
- 청구항 11에 있어서,상기 스트랜드의 중심부 및 표면부 각각의 무차원 상대 농도 획득을 종료한 후,상기 이전 강종과 후속 강종 간의 종류가 기 설정된 이강종 절사 테이블에 포함된 종류인지 판단하는 과정;현재 조업중인 이전 강종과 후속 강종 간의 종류가 기 설정된 이강종 절사 테이블에 포함된 종류인 경우, 해당 이강종 종류의 절사 길이로 절사하는 과정;현재 조업중인 이전 강종과 후속 강종 간의 종류가 기 설정된 이강종 절사 테이블에 포함되지 않는 경우, 기 설정된 일정한 절사 길이로 절사하는 과정;을 포함하는 이강종의 연속주조 방법.
- 청구항 10에 있어서,상기 후속 래들 개공 신호를 검출하는 과정에 있어서,가상의 래들 개공 신호를 송출하는 과정;상기 가상의 래들 개공 신호가 송출되는 시점으로부터 밀리세컨드(ms) 시간 단위로 턴디시의 무게를 실시간으로 검출하는 과정;상기 밀리세컨드(ms) 단위로 검출된 턴디시의 무게를 세컨드(s: second) 단위의 일정 시간 간격의 평균 턴디시 무게로 산출하는 과정; 및상기 평균 턴디시 무게가 지속 상승하는 시점을 통해 후속 래들 개공 시점을 설정하는 과정;을 포함하는 이강종의 연속주조 방법.
- 청구항 13에 있어서,Wtd(t)를 현시점의 턴디시 잔탕량 무게, Wtd(t-△t)를 이전 시점의 턴디시 잔탕량 무게라 할 때,Wtd(t) - Wtd(t-△t)와, Wtd(t) - Wtd(t-2*△t)가 모두 '0' 보다 크거나 같을 때, t-2*△t를 후속 래들의 개공 시점으로 판단하고,상기 t-2*△t 시점부터 스트랜드의 중심부 및 표면부 각각의 무차원 상대 농도를 획득하며,t-4*△t 시점부터 턴디시 잔탕량과 주조 속도를 저장하는 이강종의 연속주조 방법.
- 청구항 2 또는 청구항 4에 있어서,상기 스트랜드의 중심부 및 표면부에서 이전 강종에 대한 후속 강종의 무차원 상대 농도를 획득하는 과정은,턴디시 내 후속 용강의 유입 체적 유량(Qtd-in)을 산출하는 과정;상기 턴디시 내 후속 용강의 유입 체적 유량(Qtd-in)을 이용하여 현 시점에서의 턴디시 내 용강의 평균 무차원 상대 농도(Ctd-ave(t+△t))를 산출하는 과정;상기 현 시점의 턴디시 내 용강의 평균 무차원 상대 농도(Ctd-ave(t+△t))를 이용하여, 현 시점에서 턴디시로부터 배출되는 용강의 무차원 상대 농도(Ctd-out(t+△t))를 산출하는 과정;상기 현 시점의 턴디시로부터 배출되는 용강의 무차원 상대 농도(Ctd-out(t+△t))를 이용하여, 현 시점에서 몰드 내 용강의 평균 무차원 상대 농도(Cmd-ave(t+△t))를 산출하는 과정;상기 현 시점의 몰드 내 용강의 평균 무차원 상대 농도(Cmd-ave(t+△t))와 현 시점에서 몰드로 유입되는 용강의 무차원 농도(Cmd-in(t+△t)를 이용하여, 현 시점에서 몰드로부터 배출되는 스트랜드의 무차원 상대 농도(Cmd_out(t+△t))를 산출하는 과정;을 포함하는 이강종의 연속주조 방법.
- 청구항 15에 있어서,상기 턴디시 내 후속 용강의 유입 체적 유량(Qtd-in)은 수학식 5에 의해 산출되고,[수학식 5](Wtd(t)는 이전 시점의 턴디시 내 용강 총무게, Wtd(t+△t)는 현 시점의 턴디시 내 용강 총무게, Qtd-out는 턴디시로부터 배출되는 용강 체적 유량, ρL는 액상 용강의 밀도)상기 현 시점에서의 턴디시 내 용강 평균 농도(Ctd-ave(t+△t))는 수학식 6에 의해 산출되며,[수학식 6](Ctd_ave(t)는 이전 시점의 턴디시 내 용강의 평균 무차원 상대 농도, Qtd-in(t)은 이전 시점에서 턴디시 내로 유입되는 용강의 유입 체적 유량, Ctd-in(t)는 이전 시점의 턴디시 내 후속 용강의 유입 농도(무차원 상대 농도), Qtd-out(t)는 이전 시점의 턴디시로부터 배출되는 용강 체적 유량, Ctd-out(t)은 이전 시점의 턴디시로부터 배출되는 용강 농도(무차원 상대 농도), ρL는 액상 용강의 밀도)상기 현 시점에서 턴디시로부터 배출되는 용강 농도(Ctd-out(t+△t))는 수학식 7에 의해 산출되고;[수학식 7](ftd는 턴디시 내외삽 계수, Ctd_ave(t+△t)는 현 시점에서 턴디시 내 용강의 평균 무차원 상대 농도, Ctd-in(t+△t)은 현 시점에서 턴디시로 유입되는 용강의 무차원 상대 농도)상기 현 시점에서 몰드 내 용강 평균 농도(Cmd-ave(t+△t))는 수학식 8에 의해 산출되며,[수학식 8](Wmd(t)는 이전 시점에서 몰드 내 용강 총 무게, Cmd-ave(t)는 이전 시점에서 몰드 내 용강의 평균 무차원 상대 농도, Qmd-in(t)은 이전 시점에서 몰드 내 용강의 유입 체적 유량, Cmd-in(t)는 이전 시점에서의 몰드 내 용강의 유입 농도(무차원 상대 농도), Wmd(t+△t)는 현 시점에서 몰드 내 용강 총 무게, Qmd-out(t)은 몰드로부터 배출되는 용강 체적 유량, Cmd-out(t)은 이전 시점에서 몰드로부터 배출되는 스트랜드의 무차원 상대 농도, ρL는 액상 용강의 밀도)상기 현 시점에서 몰드로부터 배출되는 스트랜드의 농도(Cmd_out(t+△t))는 수학식 9에 의해 산출되는[수학식 9](fmd는 몰드 내외삽 계수, Cmd_ave(t+△t)는 현 시점에서 몰드 내 용강의 평균 무차원 상대 농도, Cmd-in(t+△t)는 현 시점에서 몰드로 유입되는 용강의 무차원 상대 농도)이강종의 연속주조 방법.
- 청구항 16에 있어서,상기 스트랜드 중심부의 무차원 상대 농도를 산출하는 과정에 있어서,상기 수학식 7의 내외삽 계수(ftd)에 4±2를 적용하고,상기 수학식 9의 내외삽 계수(fmd)에 0.7±0.4를 적용하여 스트랜드 중심부의 무차원 농도(Cmd-out-center)를 산출하는 이강종의 연속주조 방법.
- 청구항 16에 있어서,상기 스트랜드 표면부의 무차원 상대 농도를 산출하는데 있어서,상기 수학식 7의 내외삽 계수(ftd)는 2.2±0.6을 적용하고,상기 수학식 9의 내외삽 계수(fmd)에 0.5±0.2를 적용하여 스트랜드 표면부의 무차원 상대 농도(Cmd-out-surface)를 산출하는 이강종의 연속주조 방법.
- 청구항 16에 있어서,상기 수학식 5, 6, 8 각각에서의 밀도(ρL) 값으로 액상 용강 밀도를 사용하며, 상기 용강 밀도로 7000 내지 7400 kg/m3 값을 적용하는 이강종의 연속주조 방법.
- 청구항 10에 있어서,상기 스트랜드 표면부의 무차원 상대 농도 획득이 시작되는 상기 스트랜드의 위치를 설정하는 과정; 및상기 스트랜드 중심부의 무차원 상대 농도 획득이 시작되는 상기 스트랜드의 위치를 설정하는 과정;을 포함하고,상기 후속 래들 개공 시점에서의 스트랜드 위치를 상기 스트랜드 표면부의 무차원 상대 농도 획득이 시작되는 위치로 설정하고,상기 후속 래들 개공 시점에서의 스트랜드 위치에서 -4±4m 위치를 상기 스트랜드 중심부의 무차원 상대 농도 획득이 시작되는 위치로 설정하는 연속주조 방법.
- 청구항 21에 있어서,상기 획득된 중심부의 무차원 상대 농도를 가지는 상기 스트랜드의 길이 방향 위치를 산출하는 과정에 있어서,상기 획득된 표면부의 무차원 상대 농도를 가지는 위치에서 -4±4m 위치를 중심부의 무차원 상대 농도를 가지는 위치로 설정하는 이강종의 연속주조 방법.
- 청구항 22에 있어서,상기 실시간으로 획득되는 스트랜드 중심부의 무차원 상대 농도가 제 1 기준 농도에 도달하는 스트랜드의 지점으로부터 상기 실시간으로 획득되는 스트랜드 표면부의 무차원 상대 농도가 제 2 기준 농도에 도달하는 스트랜드의 지점까지를 혼합부로 예지하는 이강종의 연속주조 방법.
- 청구항 22에 있어서,상기 실시간으로 획득되는 스트랜드 중심부의 무차원 농도가 제 1 기준 농도에 도달하는 스트랜드의 위치를 제 1 절사 위치로 설정하는 과정;상기 실시간으로 획득되는 스트랜드 표면부의 무차원 농도가 제 2 기준 농도에 도달하는 스트랜드의 위치를 스트랜드의 제 2 절사 위치로 설정하는 과정;상기 제 1 절사 위치와 제 2 절사 위치 각각에서 절사를 실시하여, 상기 혼합부를 절사하는 과정;을 포함하는 이강종의 연속주조 방법.
- 청구항 1 또는 청구항 3에 있어서,상기 스트랜드의 혼합부를 예지하는 과정 및 예지된 혼합부의 절사 과정이 온라인 프로세스(online process)로 이루어지는 이강종의 연속주조 방법.
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EP3088102A1 (en) | 2016-11-02 |
CN105848808A (zh) | 2016-08-10 |
EP3088102B9 (en) | 2018-02-14 |
JP6220457B2 (ja) | 2017-10-25 |
CN105848808B (zh) | 2018-07-20 |
EP3088102A4 (en) | 2016-11-02 |
JP2017500206A (ja) | 2017-01-05 |
KR101485913B1 (ko) | 2015-01-26 |
EP3088102B2 (en) | 2021-01-13 |
EP3088102B1 (en) | 2017-11-08 |
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