JP2011240357A - Device and method for tracking strip on hot run table - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide technology for tracking a strip on a hot run table, by which the error of positional information occurring when a short strip is passed through the hot run table can be reduced and the error of strip information occurring by slip in a pinch roll just before a coiler can be eliminated.SOLUTION: In a tracking device for the hot run table in a rolling line including cooling equipment 15 on the hot run table 12 in a hot finish rolling line, a plurality of non-contact type plate speedometers 1-N installed along the plate passing direction are provided at an interval shorter than the length of the shortest strip of the strips which are likely to be passed between a final stand F of the hot finish rolling line and the coiler 13, and tracking control of cooling equipment 16 or the like is performed by properly switching and inputting the plate speed signals to be output from the plate speedometer having newly detected the passage of a strip, among the plurality of the plate speedometers 1-N.

Description

  The present invention relates to a strip tracking device and a tracking method on a hot run table installed between a final stand and a coiler of a finishing mill in a hot rolling line.

  FIG. 8 shows a schematic configuration of the hot rolling line, and is composed of a first rolling stand F1 to a seventh rolling stand F7 (only the sixth rolling stand F6 and the seventh rolling stand F7 are shown in the figure). A finish rolling mill 1, a hot run table 2, and a coiler 3 are provided. A pinch roll 5 is provided immediately before the coiler 3, and a cooling facility 6 is installed on the hot run table 2. In the hot rolling line, the heated steel slab is rolled by a roughing mill (not shown) and then rolled by a finishing mill 1 to finish a thin plate (strip) having a predetermined thickness. Is taken up by the coiler 3.

  The strip after completion of rolling by the finish rolling mill 1 is cooled to a set winding temperature by a cooling facility 6 in which a number of nozzles are installed on the hot run table 2. At that time, it is required to keep the winding temperature constant over the entire length of the strip and to ensure a stable material. For this purpose, it is necessary to perform cooling control in accordance with changes in the temperature on the delivery side of the finishing mill 1 and the rolling speed.

  In general winding temperature control, the rotational speed of the work roll of the last stand (seventh rolling stand) F7 or the pinch roll 5 installed immediately before the coiler 3 is in contact with the strip. The position information (longitudinal distance, plate passing speed, acceleration) of the strip is calculated, and cooling according to the temperature and speed of each longitudinal position is performed.

  In Patent Document 1, data such as a steel plate temperature and a steel plate moving speed measured by a thermometer and a sheet-feeding speed meter arranged immediately after the finishing final rolling mill are fed forward to a microcomputer for cooling control, and a necessary amount of cooling water and It is disclosed that the position and the like are calculated and an instruction is given to the cooling control device, and that the cooling length is adjusted with the increase and decrease of the sheet passing speed during accelerated rolling using a sheet passing speed meter. As a result, the cooling rate in the hot strip longitudinal direction can be kept constant regardless of fluctuations in the plate passing speed, and a hot strip made of a homogeneous material can be manufactured.

JP-A-2-197519

In the prior art described above, the work roll of the final stand F7 and the pinch roll 5 immediately before the coiler 3 are used as equipment for measuring strip position information in general winding temperature control. However, in recent years, the strip length is shortened when the plate thickness is thick, such as a steel plate for a line pipe, and the strip length is shorter than the distance (for example, 150 m to 200 m) between the work roll of the final stand F7 and the pinch roll 5 (short strip). ) There are cases. In such a short strip, there is a state in which neither of the facilities is in contact with the strip until the end of the strip passes through the final stand F7 and the tip of the strip reaches the pinch roll 5. Arise. In such a case, the coiling temperature control is performed on the assumption that the tail end of the strip travels in the hot run table 2 at the rotation speed of the work roll at the moment when it passes the final stand F7.
However, since the strip transport speed varies depending on the advance rate of the final rolling final stand and the slip between the strip and the roll of the hot run table 2, the strip position information and error obtained by calculation are generated, and high-precision winding is performed. Temperature control cannot be performed.

  In the winding temperature control, the work roll of the final stand F7 and the rotation speed of the pinch roll 5 are used to calculate the position information of the strip. However, an error in the calculated position information occurs due to a change in the advanced rate that occurs in the final stand F7, slip, and slip between the strip and the pinch roll 5, making it difficult to perform highly accurate winding temperature control.

  The present invention can reduce the error of the strip position information that occurs when the short strip is passed through the hot run table, and can eliminate the error of the strip position information caused by the slip on the pinch roll immediately before the coiler. An object of the present invention is to provide a strip tracking device and a tracking method on a hot run table.

In order to solve the above problems, a first configuration of the present invention is a strip tracking device in a hot run table between a final stand of a finishing mill of a hot rolling line and a coiler.
On the hot run table, a non-contact type plate velocimeter installed at a plurality of locations along the plate passing direction at intervals such that the strip to be passed is constantly measured by at least one plate velocimeter,
A strip on a hot run table, characterized by comprising control means for appropriately switching and controlling a plate speed signal that is actually used for tracking control among plate speed signals output from plate speed meters installed at the plurality of locations. It is a tracking device.

The second configuration of the present invention is a strip tracking method on a hot run table provided with a cooling facility on a hot run table between a final stand of a finishing mill of a hot finish rolling line and a coiler.
On the hot run table, it is output from non-contact type plate velocimeters installed at a plurality of locations along the plate passing direction at intervals such that the strips to be passed are constantly measured by at least one plate velocimeter. This is a strip tracking method using a hot run table, in which a plate speed signal that is actually used for tracking control among the plate speed signals is appropriately switched and input for tracking control.

In the first and second configurations, “at an interval at which a strip to be passed on the hot run table is always measured for speed by at least one plate speedometer” means that the final stand of the finishing mill is used. This means the distance on the hot run table between the plate speedometer installed immediately after, the plate speedometer installed immediately before the coiler, and the plate speedometer installed between them.
In the first and second configurations of the present invention, by disposing a plurality of non-contact type plate speedometers in the hot run table at the aforementioned interval, and switching the plate speedometer used according to the transport of the strip, Even when a short strip is passed, it is possible to always measure the position information of the strip using any non-contact type plate speedometer.
Moreover, in the conventional measurement method in which the strip position information is acquired from the rotation speed of the work roll and the pinch roll, a measurement error (advance rate and error due to slip) occurs on the contact surface between the roll and the strip. By installing and measuring a non-contact type plate speedometer immediately after the final stand and immediately before the coiler, it is possible to accurately grasp the position information of the strip and improve the accuracy of the winding temperature control.

In the third configuration of the present invention, the control means in the first configuration has a strip length shorter than a distance between the final stand of the finishing mill and the coiler,
Among the plate speedometers, a plate speedometer installed immediately after the final stand of the finishing mill (hereinafter referred to as “plate speedometer 1”) detects a strip and then detects a plate speedometer installed immediately before the coiler ( Hereinafter, until the “plate speedometer N”) detects the strip, the nth (1 <n <N) plate speedometer closest to the coiler among the plate speedometers currently detecting the strip. (Hereinafter referred to as “plate speed meter n”) a first step of performing tracking control with the speed of the current strip as the speed of the current strip;
When the strip tail end turns off the plate speedometer n-1 immediately before the plate speedometer n currently being tracked, the strip turns on the plate speedometer closer to the coiler than the plate speedometer n. A second step of determining whether or not
A third step of switching to a plate speedometer that is on closest to the coiler if the strip tip is on the plate speedometer closer to the coiler than the plate speedometer n in the second step;
If the plate speedometer closer to the coiler than the plate speedometer n is not turned on in the second step, tracking by the plate speedometer n is continued and switched to the plate speedometer n + 1 at the timing when the plate speedometer n + 1 is turned on. The fourth step;
The plate speed at which the strip tip is provided immediately before the coiler by repeating the second to fourth steps with the new plate speed meter switched in the third step or the fourth step as the new plate speed meter n. A strip tracking device for a hot run table, wherein the fifth step of switching to the plate speed meter N and tracking to the tail end of the strip is performed when the total N is turned on.

Further, according to the fourth configuration of the present invention, when the plate speed meter in the second configuration is switched, the strip length is shorter than the distance between the final stand of the finishing mill and the coiler.
A plate speedometer (hereinafter referred to as “plate speedometer 1”) installed immediately after the final stand of the finishing mill among the plate speedometers detects a strip, and then is installed immediately before the coiler (hereinafter referred to as “plate speedometer 1”). , "Plate speedometer N") until the detection of the strip, the nth (1 <n <N) plate speedometer closest to the coiler among the plate speedometers that are currently detecting the strip ( Hereinafter, the first step of performing tracking control with the speed of “plate speed meter n”) as the current strip speed,
When the strip tail end turns off the plate speedometer n-1 immediately before the plate speedometer n currently being tracked, the strip turns on the plate speedometer closer to the coiler than the plate speedometer n. A second step of determining whether or not
A third step of switching to a plate speedometer that is on closest to the coiler if the strip tip is on the plate speedometer closer to the coiler than the plate speedometer n in the second step;
If the plate speedometer closer to the coiler than the plate speedometer n is not turned on in the second step, tracking by the plate speedometer n is continued and switched to the plate speedometer n + 1 at the timing when the plate speedometer n + 1 is turned on. The fourth step;
The plate speed at which the strip tip is provided immediately before the coiler by repeating the second to fourth steps with the new plate speed meter switched in the third step or the fourth step as the new plate speed meter n. A strip tracking method using a hot run table, comprising: a fifth step of switching to a plate speed meter N when the total N is turned on and tracking to the tail end of the strip.

  In the third and fourth configurations of the present invention, the output status of a plurality of plate speedometers is constantly monitored, and the frequency of switching the plate speedometers is changed when switching the plate speedometer used in accordance with the conveyance of the strip. By controlling so as to reduce as much as possible, a minute pulse generation error generated at the time of switching is reduced.

  According to the present invention, on the hot run table between the final stand of the finishing mill of the hot finishing rolling line and the coiler, the interval at which the strip to be passed is constantly measured with at least one plate speedometer. The non-contact type plate speedometer is installed in multiple locations along the plate direction, and the plate speed signal actually used for tracking control out of the plate speed signals output from the plate speedometer installed in multiple locations By appropriately switching and inputting and performing tracking control, the position information measurement accuracy of the short strip can be improved by optimally arranging the non-contact type plate speed meter, and the non-contact type plate speed meter can be improved. It is possible to measure strip position information that is not affected by the advanced rate and slip used.

It is the schematic which shows the structure of the hot rolling line which concerns on embodiment of this invention. It is a control block diagram of the hot rolling line which concerns on embodiment of this invention. It is a time chart in case the pulse phase of the plate speedometer before and behind switching corresponds in the hot run table tracking method according to the present invention. It is a time chart when the pulse phase of the plate speedometer before and after switching is shifted in the hot run table tracking method according to the present invention. It is a flowchart of the tracking method of the hot run table in the hot rolling line which concerns on embodiment of this invention. It is a flowchart of the tracking method of the hot run table in the hot rolling line which concerns on embodiment of this invention. It is a flowchart of the tracking method of the hot run table in the hot rolling line which concerns on embodiment of this invention. It is the schematic which shows the structure of the conventional hot rolling line.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
As shown in FIG. 1, the hot rolling line according to the embodiment of the present invention includes a first rolling stand F1 to a seventh rolling stand F7 (only the sixth rolling stand F6 and the seventh rolling stand F7 are shown in the figure). A finish rolling mill 11, a hot run table 12, and a coiler 13 are provided. A pinch roll 14 is provided immediately before the coiler 13, and a cooling facility 15 is installed on the hot run table 12. A plurality of plate speedometers (hereinafter referred to as “plate speedometers”) 1 to N are provided along the plate-passing direction of the hot run table 12. The plate speedometer 1 is installed immediately after the work roll of the final stand F7 of the finish rolling mill 11, and the plate speedometer N is installed immediately before the pinch roll 14 immediately before the coiler 13, and the plate speedometer 2 is placed between them. -N-1 is installed.

The distance X1 between the work roll of the final stand F7 and the plate speedometer 1 is set as short as possible in order to remove the roll slip of the hot run table 12 and the disturbance of the advance rate fluctuation, but the distance X2 between the plate speedometers 1 to N ˜X _N is a shorter interval than a short strip (a strip having a length shorter than the distance from the work roll of the final stand F7 to the pinch roll 14) that may be passed. In other words, the same strip to be passed is set to an interval at which at least one plate speedometer sequentially measures the speed.
That is, assuming that Xn is the distance between plate speedometers (n = 1 to N) and Lmin is the shortest strip length, the relationship of Xmax <Lmin is established even with the maximum installation speed Xmax of the plate speedometer.

  In this way, the plate speedometers 1 to N are arranged in the hot run table 12 at shorter intervals than the short strip, and the tracking accuracy of the short strip is improved by switching the plate speedometer according to the progress of the strip. Then, the cooling control by the cooling equipment 15 is executed to improve the strip winding temperature control accuracy.

  FIG. 2 is a block diagram for executing tracking control according to the embodiment of the present invention. In FIG. 2, a plurality (N pieces) of plate speedometers 1 to N are installed on the hot run table 12 between the final stand F7 of the finishing mill 11 including the rolling stands F1 to F7 and the coiler 13. Yes.

  Speed data and a pulse having a period of f (m) are transmitted from a plate speedometer (plate speedometer n in FIG. 2) that is measuring the strip. Based on the pulse of f (m) period transmitted from the plate speedometer, the pulse conversion means 21 converts it into a pulse of f ′ (m) period used as tracking (position) data for each control. As an example, in the winding temperature control, based on the f ′ (m) period pulse converted by the pulse conversion means 21, the periodic data sampling means 22 records the actual data (temperature data, plate thickness) for each f ′ (m). Data, water injection number data). Using this record data and the plate speed data transmitted from the plate speed meter, the controller 23 calculates the amount of water injected for each f ′ (m), and performs the coiling temperature control of the entire coil length. Therefore, in order to perform highly accurate coiling temperature control, improvement in tracking accuracy is an important factor.

  Here, since the transmission timing of the pulse of f ′ (m) is different for each plate speedometer, a tracking error as shown in FIG. 3 may occur when switching the plate speedometer. Tracking error accumulates with the number of times, and tracking accuracy deteriorates. In order to avoid this error accumulation and improve the tracking accuracy, it is necessary to reduce the number of plate speedometer switching as much as possible.

The algorithm for minimizing the number of times the plate speedometer is switched is as follows.
Condition 1: When the strip length is longer than the distance between the final stand F7 and the coiler 13 (long material)
(1) The measurement is started by the plate speedometer 1 with the plate speedometer 1 on the strip front end provided immediately after the final stand F7.
(2) The strip tip is switched to the plate speed meter N with the plate speed meter N ON provided immediately before the coiler 13, and the strip end is measured.
In this condition 1, since only the plate speedometer 1 and the plate speedometer N are used and the intermediate plate speedometers 2 to N-1 are not used, the number of times of switching is one.
Condition 2: When the strip length is shorter than the distance between the final stand F7 and the coiler 13 (short material)
(1) The measurement is started by the plate speedometer 1 with the plate speedometer 1 on the strip front end provided immediately after the final stand F7.
(2) The strip tail end is switched to the plate speed meter n (see FIG. 1) that is turned on on the side closest to the coiler 13 at the timing when the final stand F7 is turned off.
(3a) At the timing when the strip tail end turns off the plate speedometer n-1 immediately before the plate speedometer n being tracked, the strip speedometer is turned on to the plate speedometer closer to the coiler 13 than the plate speedometer n. If so, switch to the plate speedometer that is on the side closest to the coiler 13.
(3b) At the timing when the strip tail end turns off the plate speedometer n-1 immediately before the plate speedometer n being tracked, the strip speedometer turns on the plate speedometer closer to the coiler 13 than the plate speedometer n. If not, tracking with the plate speedometer n is continued, and the speed is switched to the plate speedometer n + 1 at the timing when the plate speedometer n + 1 is turned on.
(4) The strip tip is switched to the plate speed meter N with the plate speed meter N ON provided immediately before the coiler 13, and the strip end is measured.

FIG. 4 is a flowchart showing logic for implementing this, and will be described in order.
Step S100: It is determined whether or not the leading end of the strip has exited the final stand F7 and the plate speedometer 1 has detected a plate passing. If detected, proceed to the next step.
Step S110: Tracking by the plate speedometer 1 is started.
Step S120: While the strip is passing the work roll of the final stand F7 and the final plate speed meter N is still off, tracking is continued by the plate speed meter 1.
Step S130: It is determined whether or not the final stand F7 is passing and the final plate speed meter N is turned on. Since YES is a case of a long strip, the process proceeds to step S140. In the case of NO, since it is a short strip, the process proceeds to step S150.
Step S140: Switch to the plate speed meter N to perform tracking, and track to the end of the strip.

Step S150: When the strip comes off from the final stand F7, the plate speed meter 1 which is on the most DC (coiler) side is switched to the nth plate speed meter n (n <N).
Step S160: When the tail end of the strip has passed through the immediately preceding plate speed meter n-1, it is determined whether or not the plate speed meter on the DC side of the plate speed meter n is turned on. If yes, then continue with S170, otherwise continue with S180.
Step S170: Switch to the plate speedometer that is on most DC side.
Step S180: The tracking with the plate speedometer n is continued, and at the timing when the next plate speedometer n + 1 is turned on, the speed is switched to the plate speedometer n + 1.
Step S190: It is determined whether or not the final plate speed meter N is turned on. If NO, the process returns to step S160. In the case of YES, the process proceeds to step S140, and tracking is performed by switching to the plate speed meter N.

  5-7, when the distance from the work roll of the final stand F7 of the finishing mill to the pinch roll before the coiler is 180 m, and the plate speedometers 1-9 are installed at intervals of 20 m in the meantime. FIG. 5 shows a state in which the plate speedometer is switched as the strip is conveyed. FIG. 5 shows a case where the strip length is 30 m, FIG. 6 shows a case where the strip length is 50 m, and FIG. 7 shows a case where the strip length is 70 m. ing.

  In the case of FIG. 5 where the strip length is 30 m, the plate thickness signal of the plate speed meter 1 is output from the time when the strip speedometer 1 first turns on the plate speed meter 1 (step S110). Next, since the plate speed meter that is turned on most on the coiler side at the timing of the last stand F7 is the plate speed meter 2, it is switched to the plate speed meter 2 (step S150). Next, when the tail end of the strip is off the plate speedometer 1 (n = 2, n-1 = 1), the plate speedometer on the coiler side of the plate speedometer 2 is not on. Is switched to the plate speed meter 3 at the timing when the plate speed meter 3 is turned on (step S180). In this way, since the plate speedometers are switched one by one, the number of times the plate speedometer is switched is not reduced. This is because L <X <2L where L is the distance between plate speedometers and X is the strip length.

  In the case of FIG. 6 in which the strip length is 50 m, the plate thickness signal of the plate speed meter 1 is output from the time when the strip tip is first turned on (step S110). Next, since the plate speedometer that is turned on most on the coiler side at the timing of the final stand F7 is the plate speedometer 3, it is switched to the plate speedometer 3 (step S150). Next, when the plate speed meter 2 (n = 3, n−1 = 2) is off at the tail end of the strip, the plate speed meter 4 on the coiler side from the plate speed meter 3 is on. (Steps S160 and S170). Next, when the plate speedometer 3 (n = 4, n-1 = 3) is off at the tail end portion of the strip, the plate speedometer 5 on the coiler side from the plate speedometer 4 is on. (Steps S160 and S170). Thereafter, similarly, since the plate speedometer is switched one by one, the number of times the plate speedometer is switched is N-1 = 8. This is because if the distance between the plate speedometers is L and the strip length is X, 2L <X <3L, and two or three plate speedometers are always on, and the number of times of switching is only once in step S150. This is because, after that, the tail end of the strip is monitored in step S160, so that the plate speed meters are switched one by one.

  In the case of FIG. 7 in which the strip length is 70 m, the plate thickness signal of the plate speedometer 1 is output from the point when the strip speedometer 1 is first turned on (step S110). Next, the speedometer that is turned on most on the coiler side at the timing of the last stand F7 is the speedometer 4, so that it is switched to the speedometer 4 (step S150). Next, when the plate speedometer 3 (n = 4, n−1 = 3) is off at the tail end of the strip, the plate speedometer 6 on the coiler side with respect to the plate speedometer 4 is on. (Steps S160 and S170). Next, when the plate speedometer 5 (n = 6, n−1 = 5) is off at the tail end portion of the strip, the plate speedometer 8 on the coiler side with respect to the plate speedometer 6 is turned on. (Steps S160 and S170). Next, since the leading end of the strip turns on the plate speedometer 9 (N), switching to the plate speedometer 9 (N) is performed until the strip comes off. In this case, the plate speed meter is switched four times. This is because if the distance between the plate speedometers is L and the strip length is X, 3L <X <4L, and three or four plate speedometers are always turned on, and there are few switchings by step S150. This is because, thereafter, the switching is reduced once by step S160.

  5 to 7 show examples in which the plate speedometers 1 to 9 are installed at equal intervals, but it is not always necessary to install them at equal intervals. In this case, as described above, Xmax < The relationship is Lmin (Xmax: plate speedometer maximum installation interval, Lmin: shortest strip length).

  In this way, by using an algorithm that can be tracked by the plate speedometer closest to the coiler 13, the number of plate speedometer switching is reduced as much as possible to avoid the accumulation of tracking errors and the strip winding temperature control accuracy. Suppresses the decline.

  The present invention reduces an error in position information that occurs when a short strip is passed through a hot run table, and also eliminates an error in strip information caused by a slip on a pinch roll immediately before a coiler. As table tracking, it can be suitably used for a rolling line that can roll both long strips and short strips.

DESCRIPTION OF SYMBOLS 11 Finishing mill 12 Hot run table 13 Coiler 14 Pinch roll 15 Cooling equipment 21 Pulse conversion means 22 Fixed period sampling means 23 Control part

Claims (4)

In the strip tracking device on the hot run table between the final stand of the finishing mill of the hot rolling line and the coiler,
On the hot run table, a non-contact type plate velocimeter installed at a plurality of locations along the plate passing direction at intervals such that the strip to be passed is constantly measured by at least one plate velocimeter,
A strip on a hot run table, characterized by comprising control means for appropriately switching and controlling a plate speed signal that is actually used for tracking control among plate speed signals output from plate speed meters installed at the plurality of locations. Tracking device. The control means, when the strip length is shorter than the distance between the final stand of the finishing mill and the coiler,
Among the plate speedometers, a plate speedometer installed immediately after the final stand of the finishing mill (hereinafter referred to as “plate speedometer 1”) detects a strip and then detects a plate speedometer installed immediately before the coiler ( Hereinafter, until the “plate speedometer N”) detects the strip, the nth (1 <n <N) plate speedometer closest to the coiler among the plate speedometers currently detecting the strip. (Hereinafter referred to as “plate speed meter n”) a first step of performing tracking control with the speed of the current strip as the speed of the current strip;
When the strip tail end turns off the plate speedometer n-1 immediately before the plate speedometer n currently being tracked, the strip turns on the plate speedometer closer to the coiler than the plate speedometer n. A second step of determining whether or not
A third step of switching to a plate speedometer that is on closest to the coiler if the strip tip is on the plate speedometer closer to the coiler than the plate speedometer n in the second step;
If the plate speedometer closer to the coiler than the plate speedometer n is not turned on in the second step, tracking by the plate speedometer n is continued and switched to the plate speedometer n + 1 at the timing when the plate speedometer n + 1 is turned on. The fourth step;
The plate speed at which the strip tip is provided immediately before the coiler by repeating the second to fourth steps with the new plate speed meter switched in the third step or the fourth step as the new plate speed meter n. The strip tracking device for a hot run table according to claim 1, wherein the fifth step of switching to the plate speed meter N and tracking to the strip tail end is executed when the total N is turned on. In the strip tracking method on the hot run table with the cooling equipment on the hot run table between the final stand of the finishing mill of the hot finish rolling line and the coiler,
On the hot run table, it is output from non-contact type plate velocimeters installed at a plurality of locations along the plate passing direction at intervals such that the strips to be passed are constantly measured by at least one plate velocimeter. A strip tracking method using a hot run table, wherein a plate speed signal that is actually used for tracking control among the plate speed signals to be switched is appropriately input to perform tracking control. The plate speedometer is switched when the strip length is shorter than the distance between the final stand of the finishing mill and the coiler.
A plate speedometer (hereinafter referred to as “plate speedometer 1”) installed immediately after the final stand of the finishing mill among the plate speedometers detects a strip, and then is installed immediately before the coiler (hereinafter referred to as “plate speedometer 1”). , "Plate speedometer N") until the detection of the strip, the nth (1 <n <N) plate speedometer closest to the coiler among the plate speedometers that are currently detecting the strip ( Hereinafter, the first step of performing tracking control with the speed of “plate speed meter n”) as the current strip speed,
When the strip tail end turns off the plate speedometer n-1 immediately before the plate speedometer n currently being tracked, the strip turns on the plate speedometer closer to the coiler than the plate speedometer n. A second step of determining whether or not
A third step of switching to a plate speedometer that is on closest to the coiler if the strip tip is on the plate speedometer closer to the coiler than the plate speedometer n in the second step;
If the plate speedometer closer to the coiler than the plate speedometer n is not turned on in the second step, tracking by the plate speedometer n is continued and switched to the plate speedometer n + 1 at the timing when the plate speedometer n + 1 is turned on. The fourth step;
The plate speed at which the strip tip is provided immediately before the coiler by repeating the second to fourth steps with the new plate speed meter switched in the third step or the fourth step as the new plate speed meter n. 5. A strip tracking method for a hot run table according to claim 3, further comprising a fifth step of switching to a plate speed meter N when the total number N is turned on and tracking to the tail end of the strip.

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