JP7199201B2 - Rolled material cooling control method and cooling control device - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cooling control method and a cooling control device for a rolled material for controlling cooling of a steel plate between the end of a rolling mill and a winder in a hot rolling line.

In the hot rolling of steel sheets, it is known that the steel sheet material changes during the process of cooling the steel sheet after rolling (hereinafter referred to as the cooling process). It is necessary to control the cooling process.

Conventionally, the control targets for this cooling process were only the cooling start temperature (finishing outlet temperature) and the cooling end temperature (winding temperature). , or its discrete approximation {(t0, T0), (t1, T1), . In the following description, t represents time and T represents temperature.

For example, in the cooling process of DP steel (Dual Phase steel), which has both high strength and high workability, three-stage cooling of first quenching-slow cooling-second quenching is required. Therefore, the control target of the cooling process of the DP steel must include the finish temperature and the coiling temperature as well as the finish temperature and finish time of the first quenching, and the finish temperature and finish time of slow cooling.

Generally, in hot rolling, the speed of a steel plate repeats acceleration and deceleration during rolling, so-called accelerated rolling. Therefore, in order to realize the same temperature history {(t0, T0), (t1, T1), . It is necessary to obtain the opening/closing setting (hereinafter referred to as cooling setting) of the cooling nozzle in the cooling device that achieves the target temperature history, and to change the cooling setting from time to time according to the speed change of the steel plate.

As a cooling control technique for changing the cooling setting from moment to moment according to the speed change of the steel sheet, the technique disclosed in Patent Document 1 is known. In addition to calculating the header patterns of the upstream cooling equipment and the downstream cooling equipment with the intermediate thermometer interposed therebetween, the technique of Patent Document 1 includes water-cooling prohibition header calculation means for specifying the header near the intermediate thermometer that suppresses the opening operation. In preparation, preset control is performed so that the intermediate air-cooling time falls within the target range, and when the target intermediate air-cooling time is not observed, the water cooling prohibition header and the strip speed are changed. According to Patent Document 1, it is possible to comply with the target intermediate air cooling time in the longitudinal direction of the steel sheet by performing this control.

Further, Patent Literature 2 discloses another technique in which temperature history is used as a control target. The technique of Patent Document 2 calculates the influence coefficient necessary for controlling the temperature change of the rolled material based on a detailed temperature model that describes the temperature change of the rolled material in a predetermined cooling interval by using parameters and formulas, Based on the influence coefficient, a simplified cooling pattern that is a simplified desired detailed cooling pattern required to obtain the desired material quality of the rolled material is calculated, and based on the calculated simplified cooling pattern and the detailed temperature model, a predetermined is to calculate a detailed cooling pattern of the rolled material in the cooling section of , and control the cooling of the rolled material based on the calculated detailed cooling pattern.
According to Patent Document 2, by performing the above control, the calculation load when obtaining a detailed cooling pattern from a detailed temperature model is reduced, optimal cooling control is performed, and the material necessary for manufacturing high-grade steel plate etc. is obtained. It can be controlled efficiently.

The conventional techniques mentioned above are considered to have the following points in common.

In the prior art, first, the steel sheet is divided into a plurality of parts along the longitudinal direction of the steel sheet, and the opening/closing pattern of the cooling header, that is, the cooling pattern is obtained for each divided part. That is, in the technique of Patent Document 1, the parts of the steel plate divided along the longitudinal direction are called "sections", and in the calculation prior to cooling, for each section, a command regarding a water cooling prohibition header and a command regarding opening and closing of the cooling header It is said that the command is calculated. In addition, in Patent Document 2, the part of the steel plate that is divided is called a "cut plate", and while trying to turn on and off the valve in the actual cooling bank for each cut plate, the detailed temperature model is referred to, and simplified cooling is performed. Calculating a detailed cooling pattern using the pattern as a target or initial value.

In the prior art, next, the part (section or cut plate) located in the section in charge of each cooling header is searched from time to time, the opening/closing information of the cooling header is read from the cooling pattern of the part, and the opening/closing of the cooling header is performed. control. The technique of Patent Document 1 extracts the cooling control code of the section reaching the cooling header, and uses this control code and the information stored in the cooling header priority table to open and close the cooling header. It is assumed that the determination process is performed for all cooling headers. Further, in Patent Document 2, a cooling bank control unit calculates each cooling pattern based on a tracking signal indicating the position of a rolled material from a rolled material tracking unit and a cooling pattern of a detailed temperature model calculated by a detailed cooling pattern calculation unit. It is supposed to send an ON/OFF (open/close) operation signal to the valve of the cooling bank.

As described above, all of the conventional techniques that use the temperature history as a control target involve the first step of determining the cooling pattern for each section, and the opening and closing of the cooling header based on the cooling pattern obtained by searching for the corresponding section for each cooling header during rolling. It is a two-stage control consisting of a second stage that reads information and controls the opening and closing of the cooling header.

JP 2015-54322 A WO2011-125221

However, it is considered that the two-step control technology common to the conventional technologies disclosed in Patent Documents 1 and 2 has the following technical problems.

First, when cooling control is performed with a plurality of temperature and time targets (hereinafter referred to as {t, T} targets) like the three-stage cooling for DP steel, cooling control is performed by accelerated rolling in which the steel plate speed changes. If the number of sections is increased to achieve high accuracy, the calculation of the first step processing to determine the cooling pattern by trying to turn on and off the valves in each cooling bank in the cooling equipment while performing temperature analysis for each section. load increases.

On the other hand, if the number of sections is not increased, the error in the steel plate speed in each section increases during accelerated rolling in which the steel plate speed changes.

In addition, since the opening and closing of the plurality of cooling headers are determined one by one in the second step during rolling, there is a time lag in the opening and closing operations of the cooling headers. Under rolling conditions in which the steel plate moves at a high speed, the time difference between the opening and closing operations of the cooling header may also reduce the control accuracy of the temperature history and cause variations in the quality of the steel plate.

In view of the above, the problem to be solved by the present invention is that it is possible to perform cooling control with high accuracy even in accelerated rolling in which the steel plate speed changes without increasing the calculation load of the cooling pattern, and further, during rolling It is an object of the present invention to provide a cooling control method and a cooling control device for a rolled material, which can simultaneously decide whether to open or close a cooling header, and whose control target is the temperature history.

Based on the above, in the present invention, "a cooling control method for a rolled strip that controls the cooling device so that the temperature of the rolled strip from the finishing delivery side of the hot rolling mill to the coiler matches the target temperature history. The cooling header in the cooling device is variably divided into a plurality of control groups at each operation time of the cooling device based on the target temperature history, and the control group in the target temperature history for each divided control group A cooling control method for a rolled material characterized by determining an open/close pattern of a cooling header that achieves a temperature history in a time zone corresponding to ".

Further, in the present invention, there is provided a "rolling material cooling control method for controlling a cooling device so that the temperature of the rolled material from the finishing delivery side of the hot rolling mill to the coiler matches a target temperature history, comprising: The moving speed of the rolled material is variably controlled from the finishing delivery side of the hot rolling mill to the coiler. A cooling control method for rolled material, characterized in that the number of cooling headers belonging to a control group controlled based on the temperature history is increased as the moving speed of the rolled material is faster, and is decreased as the moving speed is slower. is.

Further, in the present invention, "a cooling control device for a rolled strip that controls a cooling device so that the temperature of the rolled strip from the finishing delivery side of the hot rolling mill to the coiler matches a target temperature history, A target temperature history is obtained, the cooling header in the cooling device is variably divided into a plurality of control groups at each operating time of the cooling device based on the target temperature history, and the target temperature history is divided for each divided control group. A cooling control device for a rolled material characterized by determining an open/close pattern of a cooling header that achieves a temperature history in a time period corresponding to the control group.

Further, in the present invention, "a cooling control device for a rolled strip that controls a cooling device so that the temperature of the rolled strip from the finishing delivery side of the hot rolling mill to the coiler matches a target temperature history, Elapsed time distribution update unit that obtains an elapsed time vector that updates the distribution of the time that has elapsed since each part of the steel plate at each position in the cooling device passed the finishing outlet thermometer, using the steel plate speed data of the rolled material. , a target cooling density determination unit that determines a period division vector and a target cooling density matrix from the target temperature history, an elapsed time vector, and a period division vector, all the cooling headers provided in the cooling device are divided into a plurality of Using the cooling control group dividing unit for dividing into cooling control groups and obtaining a header control group matrix recording the cooling headers belonging to each cooling control group, the header control group matrix, and the target cooling density matrix, the cooling device is equipped with A cooling control device for a rolled material, characterized by comprising a snapshot determination unit that determines the opening degree of all cooling headers.

According to the present invention, in the cooling control of a steel sheet whose control target is the temperature history, it is possible to perform cooling control with high accuracy even in accelerated rolling in which the steel sheet speed changes without increasing the calculation load of the cooling pattern. , it is possible to simultaneously decide to open or close the cooling headers during rolling.

The figure which showed the example of schematic structure of the cooling control apparatus 20 which concerns on Example 1 of this invention with the example of schematic structure of the hot-rolling equipment 150. FIG. 4 is a diagram showing an example of a target temperature history given by a host computer 10; FIG. The figure which shows the numerical value example of target temperature history. FIG. 10 is a diagram showing an example of a period division vector TD obtained when dividing into three periods; The figure which shows the temperature change of enthalpy. The figure which shows the example of a target cooling density matrix. 4 is a flowchart showing the operation of a preset control section 40; FIG. 11 is a diagram showing details of an elapsed time vector update process (processing step S60) performed by an elapsed time distribution update unit 60; FIG. 10 is a diagram showing details of a cooling control group dividing process (processing step S70) performed by a cooling control group dividing unit 70; FIG. 8 is a diagram showing details of a cooling snapshot pattern determination process (processing step S80) performed by a snapshot determination unit 80; FIG. 4 is a diagram showing an example of a header priority matrix; FIG. 5 is a diagram showing an example of temporal change in the winding speed of the winding machine 154; FIG. 4 is a diagram showing the content of header combination processing in the present invention;

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In addition, in each drawing, the same code|symbol is attached|subjected to the common component, and the overlapping description is abbreviate|omitted.

FIG. 1 is a diagram showing an example of a schematic configuration of a cooling control device 20 according to Example 1 of the present invention together with an example of a schematic configuration of a hot rolling mill 150. As shown in FIG.

First, referring to FIG. 1, a hot rolling facility 150 to be controlled by the present invention will be described. The hot rolling facility 150 is a facility that cools a steel sheet 151 from a hot rolling mill 152 by a cooling device 160 and winds it on a winder 154 . The cooling device 160 includes an upper cooling device 161 that water-cools the steel plate 151 from above and a lower cooling device 162 that water-cools the steel plate 151 from below. According to the hot rolling equipment 150 configured as described above, the steel plate 151 at a temperature of about 850° C. to 900° C. discharged from the mill 153 of the hot rolling mill 152 after rolling is cooled by the cooling device 160 and rolled. It is taken up by the take-up machine 154 .

Here, each of the upper cooling device 161 and the lower cooling device 162 is provided with a plurality of banks 164 along the longitudinal direction of the steel plate 151 . Each of the banks 164 is provided with a certain number of cooling headers 163 along the longitudinal direction of the steel plate 151 . Also, each of the cooling headers 163 has a large number of nozzles (not shown) attached in the width direction of the steel plate 151 . Although only three cooling headers 163 are shown in one bank 164 in FIG. 1, the number is not limited to three.

Further, the hot rolling mill 152 is equipped with a thermometer for controlling the temperature of the steel sheet 151 . In the example of FIG. 1 , the hot rolling mill 150 is provided with a finishing outlet thermometer 170 , an intermediate thermometer 171 and a winding thermometer 172 . The finishing outlet thermometer 170 is provided near the outlet of the hot rolling mill 152, and measures the temperature of the steel sheet 151 immediately after being rolled by the hot rolling mill 152 (finishing outlet temperature, hereinafter, FDT). . An intermediate thermometer 171 is provided near the center of the cooling device 160 and measures the temperature of the steel plate 151 during cooling. In addition, the coiling thermometer 172 is provided at a position immediately before the winder 154, and measures the temperature of the steel plate 151 immediately before being wound by the winder 154 (coiling temperature, hereinafter referred to as CT). .

The hot rolling mill 150 is also equipped with other process variables, such as a steel plate speed measuring instrument, which are used in the control of the cooling control device 20, but are not shown in FIG.

The cooling control device 20 of the present invention controls the opening degrees of all the cooling headers 163 provided in the cooling device 160 of the hot rolling equipment 150, and the temperature history of the steel plate 151 while passing through the cooling device 160 is It is a device for the purpose of matching the target temperature history output from 10.

The cooling control device 20 is composed of a header priority matrix section 21 , a target cooling density determination section 30 and a preset control section 40 . The preset control unit 40 is composed of an elapsed time distribution update unit 60 , a cooling control group division unit 70 , a snapshot determination unit 80 and a snapshot output unit 90 .

According to the control configuration of FIG. 1 , the host computer 10 first transmits the target temperature history to the cooling control device 20 , and the cooling control device 20 inputs the target temperature history to the target cooling density determining section 30 . Note that the target temperature history will be described later with reference to FIG.

The target cooling density determining unit 30 performs a process described later, determines a period division vector and a target cooling density matrix from the target temperature history, and sends the period division vector to the cooling control group division unit 70 in the preset control unit 40 as a target temperature. The cooling density matrix is output to the snapshot determination section 80 in the preset control section 40, respectively.

The preset control unit 40 estimates the position of the tip of the steel plate using the speed and temperature data of the steel plate among the performance data input from the hot rolling equipment 150, and the tip of the steel plate is installed at the finish outlet thermometer 170. Once the position is reached, the processing described below for cooling snapshot output begins. Also, when the tail end of the steel plate passes through the cooling device 153, the processing for outputting the cooling snapshot ends.

When the processing for cooling snapshot output is started, the elapsed time distribution updating unit 60 uses the steel plate speed data to determine whether each part of the steel plate 151 at each position in the cooling device has passed the finishing outlet thermometer 170. After that, the distribution of the elapsed time (hereinafter referred to as elapsed time) is updated, and the updated elapsed time distribution data (hereinafter referred to as elapsed time vector) is output to the cooling control group dividing unit 70 .

The cooling control group division unit 70 divides all the cooling headers 163 provided in the cooling device 160 into a plurality of cooling control groups using the elapsed time vector and the period division vector, and divides each cooling control group into Data recording the belonging cooling header (hereinafter referred to as a header control group matrix) is output to the snapshot determination unit 80 .

The snapshot determination unit 80 uses the header control group matrix, the target cooling density matrix, and the header priority matrix from the header priority matrix unit 21 to open all cooling headers 163 provided in the cooling device 160 . determine the degree.

The opening of all cooling headers 163 determined here directly describes the opening of the cooling headers 163 at the same control point in time t, even without processing corresponding to the second stage processing of the prior art. It can be output as a control signal. In order to clarify this difference and distinguish it from the cooling pattern of the prior art, the opening degree data of all the cooling headers 163 provided in the cooling device 160 determined by the snapshot determination unit 80 is referred to as a cooling snapshot. Snapshot determination unit 80 outputs the determined cooling snapshot to snapshot output unit 90 .

The snapshot output section 90 outputs the cooling snapshot to the cooling device 160 in the hot rolling equipment 150 in accordance with the control cycle of the cooling device 160 . Details of each of the above processes will be described later.

The operation command to the nozzle of the cooling header 163 can include not only the opening and closing of the nozzle but also the amount of water to be sprayed. do. It is assumed that the nozzle open/close command data for each cooling header 163 in the upper cooling device 161 and the lower cooling device 162 is the cooling snapshot described above.

Next, the concept of temperature calculation or temperature estimation when controlling the temperature of a steel plate using the equipment shown in FIG. 1 will be explained using mathematical formulas.

First, the steel sheet 151 discharged from the mill 153 of the hot rolling mill 152 is cooled by water jetted from the cooling header 163 when passing through the cooling device 160 (water cooling operation). Moreover, even when water is not jetted from the cooling header 163, the steel plate 151 is cooled by the surrounding air (air cooling operation).

That is, when the control command for the cooling header 163 is "open", water cooling is performed, and the heat flux on the surface of the steel plate 151 is given by the following equation (1), for example.

However, in equation (1), qW is the surface heat flux by water cooling (W/cm ² ), ω is the water volume density (L/m ² /s), TW is the water temperature (°C), D is the nozzle diameter (m), pl is the nozzle pitch (m) in the line direction, and pc is the nozzle pitch (m) in the direction perpendicular to the line.

Further, when the control command for the cooling header 163 is "closed", air cooling is performed, and the heat flux on the surface of the steel plate 151 is given by the following equation (2), for example.

However, in equation (2), qr is the surface heat flux due to radiation (W/cm ² ), σ is the Stefan Boltzmann constant (W/cm ² /K ⁴ ), ε is the emissivity, Ta is the air temperature (°C), Tsu is the surface temperature (° C.) of the steel plate 151 .

Moreover, if the steel plate 151 is a thin plate, the heat transfer in the thickness direction of the steel plate 151 can be ignored, so the temperature of the steel plate 151 changes as shown in the following equation (3).

However, in equation (3), _Tn is the current steel plate temperature (°C), Tn _-1 is the steel plate temperature before time Δ (°C), qt is the heat flux from the upper surface of the steel plate (W/cm ² ), qb is the heat flux from the bottom surface of the steel plate (W/cm ² ), ρ is the density of the steel plate (g/cm ³ ), C is the specific heat of the steel plate (J/g/K), and B is the thickness of the steel plate (cm). .

On the other hand, if it is necessary to consider the heat transfer in the thickness direction of the steel plate 151, the temperature of the steel plate 151 changes according to the well-known heat transfer equation (4) below.

However, in equation (4), λ is the thermal conductivity and T is the internal temperature of the steel plate 151 .

When calculating the temperature of the steel plate 151 according to the above equations (1) to (4), in addition to the above, the water volume density of the nozzles of the cooling header 163 determined depending on the cooling device 160, , physical property values such as specific heat depending on the steel plate 151 to be rolled are preferably used, but further detailed explanation is omitted here.

The operation of the cooling control device 20 will be described below using a specific example.

FIG. 2 shows an example of the target temperature history given by the host computer 10. As shown in FIG. The horizontal axis represents the time from the start of cooling, and the vertical axis represents the temperature at a certain position within the steel plate 151 . The temperature at a given location within the steel plate 151 moving through the cooling device 160 is hereinafter referred to as the Lagrangian temperature of the steel plate, as it is similar to the fluid temperature described by the Lagrangian representation of fluid mechanics. The temperature at the start of cooling is the finish outlet temperature FDT, and the temperature at the end of cooling is the winding temperature CT.

In the example of the target temperature history shown in FIG. 2, the initial point of time when control is started is t0, and the subsequent points of time when temperature changes start are t1, t2, and t3. Between t0 and t1, the temperature is lowered from the finish outlet temperature FDT, the temperature is kept constant between t1 and t2, and the temperature is lowered again between t3 and t4 to finally reach the winding temperature CT. . These are the four time points after the start of cooling that are the starting points of the temperature change.

FIG. 3 shows a table of specific numerical examples of the target temperature history. In the example of FIG. 3, the four time points after the start of cooling are t0 = 0 seconds, t1 = 3 seconds, t2 = 7 seconds, and t4 = 9 seconds. entered as a target for each According to this case, for example, the tip portion (Header) of the steel plate is 870° C., 670° C., 670° C., and 400° C. The temperature of the middle part of the steel plate (Middle) was controlled to 870 ° C., 670 ° C., 670 ° C., and 300 ° C. at four time points (t = 0 seconds, 3 seconds, 7 seconds, 9 seconds) after the start of cooling. The temperature was controlled, and the tail end portion (Tail) of the steel plate was 870 ° C., 670 ° C., 670 ° C., and 400 ° C. at four time points (t = 0 seconds, 3 seconds, 7 seconds, 9 seconds) after the start of cooling. Temperature controlled.

In order to make the material uniform, it is desirable to have one target temperature history over the entire length of the steel plate. The target temperature history may differ for each part of the steel sheet, such as when a so-called U pattern is used in which the winding temperature of the steel sheet is higher than that of the central part. Hereinafter, the time and temperature given as the target temperature history will be referred to as target time and target temperature, respectively.

The target cooling density determining unit 30 first divides the cooling time into a plurality of terms using the target time. The simplest method is period division in which two consecutive target times are set at both ends of the period. If the simplest period division method is applied to the example shown in FIG. 3, the cooling time is 0-3 seconds for the first period, 3-7 seconds for the second period, and 7-9 seconds for the third period. is divided into three periods. FIG. 4 shows an example of the period division vector TD obtained when dividing into three periods. In the example of FIG. 4, the period division vector TD={0, 3, 7, 9}. Note that the n-th element of the period division vector TD is expressed as td[n]. In the example of FIG. 2, three periods of 0 to 3 seconds for the first period, 3 to 7 seconds for the second period, and 7 to 9 seconds for the third period correspond to td[1] and td[ 2], td[3].

As another method of dividing the period, a method of fixing the period length (term time) may be used. For example, if the period length is 1 second, the cooling time in the example shown in FIG. 3 is divided into 9 periods such as 0 to 1 second and 1 to 2 seconds. An example using the simplest period division method will be described below, but it can be easily applied to other period division methods.

Next, the target cooling density determination unit 30 uses equation (5), which is a conversion of equation (3), to set a target energy density (hereinafter referred to as cooling density) for cooling the steel plate during each divided period. to decide.

However, in equation (5), Q _i is the target cooling density in period i (J/cm ² ), Δ _i is the length of period i (sec), and T _i,s is the steel plate temperature at the start time of period i (°C ), and T _i,e is the steel plate temperature (° C.) at the end time of period i.

In order to determine the target cooling density for each period by the target cooling density determination unit 30, a method using enthalpy may be used in addition to the method using the above equation (5). The enthalpy H at a certain temperature T is a definite integral of ρ×C with respect to temperature, as shown in equation (6).

The target cooling density during period i can be determined using equation (7) with enthalpy H in place of ρ×C.

However, in equation (7), H _i,s is the steel plate enthalpy (J/cm ³ ) at the start temperature T _i,s of period i, and H _i,e is the steel plate enthalpy at the end temperature T _i,e of period i. (J/cm ³ ).

FIG. 5 is a diagram showing changes in enthalpy with temperature. The specific heat C shows a sharp peak due to the latent heat of transformation at the phase transformation temperature, whereas the enthalpy changes smoothly as shown in FIG. Compared to the method using the specific heat C, there is little decrease in precision even if phase transformation occurs at the steel plate temperature T _i,s at the end time of i and the steel plate temperature T _i,e at the end time of period i. This feature of the enthalpy method is described in the non-patent document "Tomokazu Nakagawa, Yoshiki Takebayashi, "Simulation of Solidification of Light Alloy Casting", Light Metal Vol. there is In addition, FIG. 5 shows the temperature change of the enthalpy of the austenite phase and the ferrite phase, which are representative phases of steel.

Above, as an example of the method of obtaining the target cooling density, the method using the specific heat of formula (5) and the enthalpy method of formula (6) were shown, but these two methods can be applied to obtain the required cooling density from the temperature. It is not limited to one.

The energy density Qenv (J/cm ² ) of environmental cooling other than water cooling, such as radiative cooling and convection cooling, is about 1/100 smaller than the energy density of water cooling, so the calculation load can be reduced by ignoring it. . Alternatively, the accuracy of cooling control can be increased by subtracting the energy density Qenv due to environmental cooling from the target cooling density obtained above and outputting the target cooling density for water cooling.

The target cooling density during each period determined from the target temperature by the target cooling density determination unit 30 is the target cooling density matrix. FIG. 6 shows an example of the target cooling density matrix. According to this case, for example, the tip portion (Header) of the steel plate is the target cooling density matrix (J/cm ² ) are -197, -83, and -221, and the middle portion (Middle) of the steel plate is in the first, second, and third periods td[1], td[2], and td[3], respectively The target cooling density matrix (J/cm ² ) is set to −197, −83, −300, and the tail end portion (Tail) of the steel plate is set to the first, second, and third periods td[1], td[ 2] and td[3], the target cooling density matrices (J/cm ² ) are −197, −83, and −221, respectively.

The target cooling density determination unit 30 outputs the target cooling density matrix created by the above processing to the snapshot determination unit 80 in the preset control unit 40, and also outputs the period division vector to the cooling control group in the preset control unit 40. Output to the dividing unit 70 .

FIG. 7 is a flow chart showing the operation of the preset control section 40. As shown in FIG.

When rolling is started, the preset control unit 40 first initializes internal data of the preset control unit 40, such as an elapsed time vector and a header index matrix (processing step S40). (processing step S41).

When the leading end of the steel plate reaches the installation position of the finishing outlet thermometer by the judgment processing of processing step S41, a series of processing from processing step S60 to processing step S90 is sequentially executed. Specifically, first, using the steel plate speed data, the elapsed time distribution update unit 60 performs update processing of the elapsed time vector (processing step S60, details of which will be described later).

Next, the cooling control group dividing unit 70 performs a cooling control group dividing process (processing step S70, details will be described later) for creating a header control group matrix using the updated elapsed time vector and period dividing vector.

Next, the snapshot determination unit 80 uses the target cooling density to determine the number of headers to be opened in each header control group, and then uses the header priority matrix to A cooling snapshot pattern determination process (processing step S80, details will be described later) for determining opening/closing (cooling snapshot pattern) is performed.

Next, the snapshot output unit 90 outputs a cooling snapshot pattern to the cooling device 160 in the hot rolling mill 150 in accordance with the control cycle of the cooling device 160 (processing step S90).

Next, it is checked whether the tail end of the steel plate has come out of the cooling device 160 (processing step S42). If the tail end has not come out, the above series of processes are repeated.

The internal data used in the preset control unit 40 and the initialization process thereof in processing step S40 will be specifically described.

In the cooling control device 160 of the present invention, the section from the finishing outlet thermometer 170 to the winding machine 154 side outlet of the cooling device 160 is divided into L sections. In the prior art, the steel plate is divided into a plurality of sections, but in the present invention, the space from the finishing outlet thermometer 170 to the winding machine 154 side outlet of the cooling device 160 is divided instead of the steel plate.

On this premise, the first internal data to be initialized is the section center coordinate vector X={x[1], x[2], . . . , x[L]}. The initialization in processing step S40 initializes x[n] of the section center coordinate vector X to the distance from the finish outlet thermometer 170 of the center point of the section n.

The second internal data to be initialized is an interval vector ΔX={Δx[0], Δx[1], Δx[2], . The initialization in processing step S40 is Δx[0]=0, Δx[1]=x[1], and when n≧2, Δx[n]=x[n]−x[n−1]. .

The third to sixth internal data to be initialized are data relating to the correspondence between the L divided sections and the positions of the cooling headers 163 in the cooling device 160 . The third and fourth internal data are IHT={{iht[1,1], iht[1,2], . , kmax]}, {iht[2,1],iht[2,2],...,iht[2,kmax]},...,{iht[Mt,1],iht[Mt,2],...,iht [Mt, kmax]}} and IHB={{ihb[1,1],ihb[1,2],...,ihb[1,kmax]},{ihb[2,1],ihb[2,2 ], . Here, Mt and Mb are the number of controlled cooling headers located in the upper cooling unit 161 and the lower cooling unit 162 of the cooling unit 160, respectively.

The initialization in processing step S40 is to set {iht[i, 1], iht[i, 2], . Initialize with the interval index corresponding to the location of the cooling header. If the number of corresponding intervals is less than kmax, the remaining iht[i,j] are initialized to zero. For example, if the position of the 12th cooling header among the L sections corresponds to 5 sections from the 97th to the 101st, the 12th row of the upper header index matrix IHT matrix is {iht[12 ,1]=97,iht[12,2]=98,...,iht[12,5]=101,iht[12,6]=0,...,iht[12,kmax]=0} .

The lower header index matrix IHB is initialized similarly to the upper header index matrix IHT. The fifth and sixth internal data are upper and lower header corresponding section number vectors KT={kt[1], kt[2], . . . , kt[Mt]} and KB={kb[1], kb[ 2], . For the example above, it is initialized to kt[12]=5.

The seventh internal data is the elapsed time vector PT={pt[0], pt[1], . . . , pt[L]}. In the initialization in processing step S40, pt[n]=0 for all n.

The eighth and ninth internal data are an upper header control group matrix HCGT that divides the cooling headers of the upper cooling device 161 into upper header control groups, and also divides the cooling headers of the lower cooling device 162 into lower header control groups. is a bottom header control group matrix HCGB. All elements of the upper header control group matrix HCGT and the lower header control group matrix HCGB are initialized to zero.

FIG. 8 shows details of the elapsed time vector updating process (processing step S60) performed by the elapsed time distribution update unit 60. As shown in FIG. When the steel plate speed v is input, the elapsed time distribution updating unit 60 substitutes =ΔX/v for the elapsed time increment vector ΔPT={Δpt[0], Δpt[1], . . . , Δpt[L]} ( processing step S61). where ΔX is the spacing vector. ΔPT is local data used only inside the elapsed time distribution update unit 60 . Next, the elapsed time vector PT is updated by the processing of (Equation 8) (processing step S62).

Here, shift is an array operation, and shift(PT)={0, pt[0], pt[1], pt[2], . . . , pt[L−1]}. As a result of the above processing, pt[n] stores the elapsed time from when the steel plate portion in the n-th section left the finish outlet thermometer 170 .

In the above, an example of performing update processing with one data of the steel plate speed v is shown, but averaging processing, low-pass filter processing, interpolation processing, etc. are added to the series of steel plate speed data received from the hot rolling mill 150. may be used as the steel plate speed v.

Also, if the change in the steel plate speed v with time is small, PT=X/v may be approximated. Since there is no x[0] in X, pt[0]=0.

FIG. 9 shows details of the cooling control group dividing process (processing step S70) performed by the cooling control group dividing unit 70. As shown in FIG. First, the header elapsed time vectors HTT and HTB, which are the elapsed times up to the section corresponding to the upper and lower cooling headers, are obtained by equation (9) (processing step S71).

Here, the header elapsed time vectors HTT and HTB, which are elapsed times up to the section corresponding to the upper and lower cooling headers, are local data used only inside the cooling control group dividing unit 70 .

Next, using the period division vector TD input from the target cooling density determination unit 30 and the header elapsed time vectors HTT and HTB, the upper header control group is obtained by dividing the cooling header of the upper cooling device into upper header control groups. A matrix HCGT and a lower header control group matrix HCGB obtained by dividing the cooling headers of the lower cooling device into lower header control groups are created (processing step S72). As a specific example, for the period division of the period division vector TD={0, 3, 7, 9}, the value of the element of the upper header elapsed time vector HTT at a certain time is htt[24]≦3<htt [25], htt[72]≤7<htt[73], htt[96]≤9<htt[97] then HCGT = {{1,...,24}, {25,...,72} , {73, . . . , 96}}. Since the period division vector TD and the upper and lower header elapsed time vectors HTT and HTB are created so that the elements are arranged in ascending order, this division processing can be executed at high speed.

FIG. 10 shows details of the cooling snapshot pattern determination process (processing step S80) performed by the snapshot determination unit 80. As shown in FIG.

The snapshot determination unit 80 first uses the header priority matrix 21 to arrange the rows of the header control group matrices HCGT and HCGB in ascending order of priority (processing step S81).

A detailed description will be given using an example where HCGT={{1,...,24}, {25,...,72}, {73,...,96}}. Assume that a 2.0 mm thick DP1 steel is being rolled and the header priority matrix 21 has the values shown in FIG.

Specifically, the priority of the 1st to 24th top headers belonging to the first control group is {1, 66, 34, 67, 18, 68, 35, 10, 69, 36, 19, 70, 37, 6 , 71, 38, 20, 72, 39, 11, 73, 40, 21, 74, 41}, arrange the first row {1, . . . , 24} of the HCGT matrix in ascending order of priority, to {1, 14, 8, 20, 5, 11, 17, 23, 3, 7, 10, 13, 16, 19, 22, 2, 4, 6, 9, 12, 15, 18, 21, 24} change.

Next, using the target cooling density matrix, the cooling headers to be opened in each header control group are determined (processing step S82). First, determine the number of headers to open. The cooling density QH obtained with one open cooling header can be calculated by equation (10).

Here, qW is the heat flux (W/cm ² ) during water cooling by the cooling header, which can be calculated, for example, by Equation (1). Also, pl represents the nozzle pitch (m) in the line direction, and v represents the steel plate speed (m/s).

Find the number of open headers for which the sum of the cooling densities QH is the target cooling density for the period. For example, the target cooling density is -197 J/cm ² in the case of the first period of the middle part of the latter half shown in FIG. Since the cooling density QH = 8.47 J/cm ² when v = 10 m/s in a chiller with pl = 0.7 m and qW = 121 W/cm ² , to obtain the target −197 J/cm ² The number of headers to be opened is determined as 197/8.47≈23. Here, "≈" represents rounding to the nearest natural number. Next, from the corresponding rows of the header control group matrices HCGT and HCGB aligned in the above processing step S81, a determined number of headers with high priority are selected.

Using the example so far, in the case of setting to open the same number of headers at the top and bottom, {1, 14, 8, 20, 5, 11, 17, 23, 3, 7, 10, 13} Open 12 cooling headers and lower 11 cooling headers numbered {1, 14, 8, 20, 5, 11, 17, 23, 3, 7, 10}. The number of open headers at the top and bottom may be input by the user through the host computer 10, or the target cooling densities may be set separately for the top and bottom. Anything can be easily achieved.

By performing the processing shown in the above example for each of the upper and lower cooling control groups, the cooling headers to be opened in each header control group are determined. The determined open cooling header numbers are stored in the upper and lower open header number matrices OHT and OHB, respectively. The upper and lower open header number matrices OHT and OHB are local data used only inside the snapshot determination unit 80 .

Next, using the upper and lower open header number matrices OHT and OHB, for the upper and lower cooling snapshot patterns, the upper and lower cooling snapshot patterns CSPT={cspt[1],..., cspt[Mt]} and the lower A cooling snapshot pattern CSPB={cspb[1], . . . , cspb[Mb]} is created (processing step S83). The elements corresponding to the headers stored in the upper and lower open header number matrices OHT and OHB are set to 1, and the other elements are set to 0.

With reference to FIGS. 12 and 13, it will be described how the header control groups are combined and controlled over time by the temperature history control according to the present invention.

First, FIG. 12 shows an example of the change in the winding speed of the winder 154 over time. After execution of the speed control stage, deceleration control is executed from an appropriate time when the tail end approaches.

FIG. 13 is a diagram showing the content of header combination processing in the present invention. The lower portion of FIG. 13 shows the path from the exit of the hot rolling mill 152 on the left to the entrance of the winder 154 on the right, and a plurality of upper and lower banks 164 arranged therebetween. The path length between them is, for example, 100 m, and 12 banks 164 are arranged at equal distances. Each bank 164 includes a plurality of cooling headers 163 (three each in the example of FIG. 1).

In the upper part of FIG. 13 are shown two times t1 and t2 in the acceleration control stage of FIG. 12, one time t3 in the constant speed control stage of FIG. 12, and two times t4 and t5 in the deceleration control stage. , thus indicating the grouping extent of the cooling headers 163 .

According to this figure, the upper header control group TG and the lower header control group BG are sequentially grouped from the exit of the hot rolling mill 152 on the left side. The control groups in this case are divided into a control group 1 consisting of TG1 and BG1, a control group 2 consisting of TG2 and BG2, a control group 3 consisting of TG3 and BG3, and a control group 4 consisting of TG4 and BG4. Moreover, from time t1 to t3, the faster the winding speed, the more cooling headers 163 belong to control group 1, control group 2, and control group 3. FIG. Conversely, the number of cooling headers 163 belonging to control group 1, control group 2, and control group 3 decreases as the winding speed decreases from time t3 to t5.

Here, the cooling headers 163 belonging to control group 1 perform temperature control in period td[1] in FIG. 6, and the cooling headers 163 belonging to control group 2 perform temperature control in period td[2] in FIG. , the cooling headers 163 belonging to the control group 3 perform temperature control in the period td[3] of FIG. That is, in the control group 1, the head, middle, and tail of the rolled material are all controlled by −197 (J/cm ² ), which is the same target cooling density matrix, by the group of cooling headers 163 that increase or decrease according to the winding speed. In control group 2, the head, middle, and tail of the rolled material are controlled by −83 (J / cm ² ), which is the same target cooling density matrix, and in control group 3, the head of the rolled material , middle, and tail are controlled to be -221, -300, and -221 (J/cm ² ) as the target cooling density matrix. The cooling header 163 belonging to control group 4 does not contribute to temperature control of the rolled material (temperature control for temperature reduction or retention), and is subject to temperature control only when it is classified into control group 3 or control group 2. It is said that

Thus, according to the present invention, there is provided a cooling control method for a rolled strip that controls the cooling device so that the temperature of the rolled strip from the finishing delivery side of the hot rolling mill to the coiler matches the target temperature history. , based on the target temperature history, the cooling header in the cooling device is variably divided into a plurality of control groups at each operation time of the cooling device, and each divided control group corresponds to the control group in the target temperature history. The opening/closing pattern of the cooling header that achieves the temperature history of the time period to be determined is determined.

In this embodiment, by using the configuration and processing of the cooling control device described above, in the cooling control of the steel sheet with the temperature history as the control target, accelerated rolling in which the steel sheet speed changes without increasing the calculation load of the cooling pattern Also, it is possible to control the cooling with high precision, and it is possible to simultaneously decide whether to open or close the cooling header during rolling.

10: Host computer 20: Cooling control device 21: Header priority matrix 30: Target cooling density determination unit 40: Preset control unit 60: Elapsed time distribution update unit 70: Cooling control group division unit 80: Snapshot determination unit 90: Snap Shot output unit 150: hot rolling equipment 151: steel plate 152: hot rolling mill 153: mill 154: winder 160: cooling device 161: upper cooling device 162: lower cooling device 163: cooling header 164: bank 170: finishing Outlet thermometer 171: Intermediate thermometer 172: Winding thermometer

Claims (4)

A cooling control method for a rolled strip that uses a computer device to control a cooling device so that the temperature of the rolled strip from the finishing delivery side of a hot rolling mill to a coiler matches a target temperature history, comprising:
Using the steel plate speed data of the rolled material, the elapsed time vector updated the distribution of the time elapsed after each part of the steel plate at each position in the cooling device passed the finishing outlet thermometer, and from the target temperature history A period division vector and a target cooling density matrix are determined, and all cooling headers provided in the cooling device are divided into a plurality of cooling control groups using the elapsed time vector and the period division vector, and each Obtaining a header control group matrix that records cooling headers belonging to a cooling control group, and using the header control group matrix and the target cooling density matrix to determine the opening degrees of all cooling headers provided in the cooling device. Cooling control method for rolled material. A cooling control method for a rolled material according to claim 1,
The moving speed of the rolled material is variably controlled from the finishing delivery side of the hot rolling mill to the winding machine, and the cooling headers in the cooling device are divided into a plurality of control groups based on the target temperature history. , the number of cooling headers belonging to the control group controlled based on the target temperature history is increased as the moving speed of the rolled material is faster and is decreased as the moving speed is slower. . A cooling control device for a rolled material that controls a cooling device so that the temperature of the rolled material between the finish delivery side of the hot rolling mill and the coiler matches a target temperature history,
Elapsed time distribution update unit that obtains an elapsed time vector that updates the distribution of the time that has elapsed since each part of the steel plate at each position in the cooling device passed the finishing outlet thermometer, using the steel plate speed data of the rolled material. a target cooling density determination unit that determines a period division vector and a target cooling density matrix from the target temperature history; and all cooling headers provided in the cooling device using the elapsed time vector and the period division vector. a cooling control group dividing unit that divides into a plurality of cooling control groups and obtains a header control group matrix that records the cooling headers belonging to each cooling control group; and the header control group matrix and the target cooling density matrix. 1. A cooling control device for a rolled material, characterized by comprising a snapshot determining section for determining opening degrees of all cooling headers provided in the cooling device. A cooling control device for a rolled material according to claim 3,
A cooling control device for a rolled material, wherein a section from a finish outlet thermometer on the finish delivery side of the hot rolling mill to a winder side outlet is divided into a plurality of sections determined by the target temperature history. .

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