1. A hot-rolling finishing mill delivery temperature controller used for controlling a temperature of a steel sheet to be rolled in a hot-rolling finishing mill inclusive of: a plurality of rolling stands for continuously rolling a steel sheet; and a plurality of between-stands cooling devices for cooling the steel sheet, 5 each being arranged between two rolling stands which are adjacent to each other, on a delivery side of the hot-rolling finishing mill, the controller comprising: a sheet-temperature estimation model storage that stores sheet-temperature 10 estimation models for estimating the temperature of a steel sheet to be rolled; an amount-of-cooling-water presetter that estimates the temperature of the steel sheet on the delivery side of the hot-rolling finishing mill, before rolling the steel sheet, based on a preset rolling speed of the steel sheet, 15 amount of cooling water to be injected from the plurality of betweenstands cooling devices, the temperature of the steel sheet on an entry side of the hot-rolling finishing mill, and the sheet-temperature estimation model, and then presets the amount of cooling water on the basis of an estimated result so that the temperature of the steel sheet on the delivery 20 side coincides with a target temperature predetermined in advance; a target-temperature correction amount calculator that obtains a variation in the rolling speed to be detected by the rolling stands during the rolling of the steel sheet from the preset rolling speed, and calculates a correction amount for the target temperature on the delivery side of the steel sheet 25 for reducing influence from the variation in the rolling speed on the material property values of the steel sheet; and an amount-of-cooling-water commander that calculates a variation in the amount of cooling water according to the correction amount for the target temperature of the steel sheet on the delivery side, and outputs the 30 amount of cooling water, which has been preset in the amount-ofcooling- water presetter and then corrected with the variation in the amount of cooling water calculated, to the between-stands cooling device. 24

2. The hot-rolling finishing mill delivery temperature controller according to claim 1, further comprising: a material-property predictor that calculates at least one of an austenite grain size and a dislocation density as material properties of the steel sheet on the delivery side of the 5 hot-rolling finishing mill, on the basis of information obtained from a host computer on the steel sheet, inclusive of chemical composition, heating history, and rolling history, as well as the temperature of the steel sheet on the delivery side, which has been estimated in the amount-of-cooling-water presetter, 10 and the rolling speed; and an influence-coefficient calculator that calculates influence of a variation in the rolling speed to the material property values as a first influence coefficient, on the basis of differences in the material property values which the material-property predictor has calculated by varying the 15 rolling speed of the steel sheet, and calculates influence of a variation in the temperature of the steel sheet on the delivery side to the material property values as a second influence coefficient, on the basis of differences in the material property values which the material property predictor has calculated by varying the temperature of the 20 steel sheet on the delivery side, wherein the target-temperature correction amount calculator calculates a correction amount for the target temperature of the steel sheet on the delivery side, on the basis of the variation in the rolling speed and at least one of the first and second influence coefficients. 25 3. The hot-rolling finishing mill delivery temperature controller according to claim 1, further comprising: a feedforward controller that calculates a variation in the amount of cooling water for reducing the correction amount for the target temperature of the steel sheet on the delivery side, which has been 30 calculated by the target-temperature correction amount calculator, wherein the variation in the amount of cooling water calculated by the feedforward controller is used as the variation in the amount of cooling water according to the 25 correction amount for the target temperature of the steel sheet on the delivery side calculated by the amount-of-cooling-water commander.

4. The hot-rolling finishing mill delivery temperature controller according to claim 1, further comprising: a temperature-for-control-command 5 calculator that calculates a target temperature of the steel sheet on the delivery side to be used for actual control, on the basis of the correction amount for the target temperature of the steel sheet on the delivery side calculated by the targettemperature correction amount calculator and the target temperature of 10 the steel sheet on the delivery side used by the amount-of-cooling-water presetter; and a feedback controller that calculates a variation in the amount of cooling water to reduce a difference between the target temperature of the steel sheet on the delivery side calculated by the temperature-for-control15 command calculator and a temperature of the steel sheet measured on the delivery side of the hot-rolling finishing mill, wherein the variation in the amount of cooling water calculated by the feedback controller is used as the variation in the amount of cooling water according to the correction amount for the target temperature of the steel sheet on the delivery side 20 calculated by the amount-of-cooling-water commander.

5. The hot-rolling finishing mill delivery temperature controller according to claim 1, further comprising: a feedforward controller that calculates a first variation in the amount of cooling water for reducing the correction amount for the target 25 temperature of the steel sheet on the delivery side, which has been calculated by the target-temperature correction amount calculator; a temperature-for-control-command calculator that calculates a target temperature of the steel sheet on the delivery side to be used for actual control, on the basis of the correction amount for the target temperature 30 of the steel sheet on the delivery side calculated by the targettemperature correction amount calculator and the target temperature of the steel sheet on the delivery side used by the amount-of-cooling-water presetter; and 26 a feedback controller that calculates a second variation in the amount of cooling water to reduce a difference between the target temperature of the steel sheet on the delivery side calculated by the temperature-forcontrol- command calculator and a temperature of the steel sheet measured on the delivery side of 5 the hot-rolling finishing mill, wherein an amount obtained by adding the first and second variations, which are respectively given weight, is used as the variation in the amount of cooling water according to the correction amount for the target temperature of the steel sheet on the delivery side calculated by the amount-of-cooling-water commander. 10 6. A control method of hot-rolling finishing mill delivery temperature, for use in a device which controls a temperature of a steel sheet to be rolled in a hot-rolling finishing mill inclusive of: a plurality of rolling stands for continuously rolling a steel sheet; and a plurality of between-stands cooling devices for cooling the steel sheet, each being arranged between two rolling stands which are adjacent to each other, on 15 a delivery side of the hot-rolling finishing mill, and stores sheet-temperature estimation models for estimating a temperature of a steel sheet to be rolled, the control method comprising: estimating, as an amount-of-cooling-water presetting process, the temperature of the steel sheet on the delivery side of the hot-rolling 20 finishing mill, before rolling the steel sheet, based on a preset rolling speed of the steel sheet, amount of cooling water to be injected from the plurality of between-stands cooling devices, the temperature of the steel sheet on an entry side of the hot-rolling finishing mill, and the sheettemperature estimation model, to preset the amount of cooling water on 25 the basis of the estimated results so that the temperature of the steel sheet on the delivery side coincides with a target temperature predetermined in advance; obtaining, as a target-temperature correction amount calculation process, a variation in the rolling speed to be detected by the rolling stands during 30 the rolling of the steel sheet from the preset rolling speed, to calculate a correction amount for the target temperature on the delivery side of the steel sheet for reducing influence from the variation in the rolling speed on the material property values of the steel sheet; and 27 calculating, as an amount-of- cooling-water command process, a variation in the amount of cooling water according to the correction amount for the target temperature of the steel sheet on the delivery side, to output the amount of cooling water, which has been preset in the amount-ofcooling- water presetting process and then corrected 5 with the variation in the amount of cooling water calculated, to the between-stands cooling device.

7. The control method of hot-rolling finishing mill delivery temperature according to claim 6, further comprising: 10 calculating, as a material-property prediction process, at least one of an austenite grain size and a dislocation density as material properties of the steel sheet on the delivery side of the hot-rolling finishing mill, on the basis of information obtained from a host computer on the steel sheet, inclusive of chemical composition, heating history, and 15 rolling history, as well as the temperature of the steel sheet on the delivery side, which has been estimated in the amount-of-coolingwater presetting process, and the rolling speed; and calculating, as an influence-coefficient calculation process, influence of a variation in the rolling speed to the material property values as a first 20 influence coefficient, on the basis of differences in the material property values which has been calculated in the material-property prediction process by varying the rolling speed of the steel sheet, and calculating influence of a variation in the temperature of the steel sheet on the delivery side to the material property values as a 25 second influence coefficient, on the basis of differences in the material property values which has been calculated in the material property prediction process by varying the temperature of the steel sheet on the delivery side, wherein in the target-temperature correction amount calculation process, a 30 correction amount for the target temperature of the steel sheet on the delivery side is calculated on the basis of the variation in the rolling speed and at least one of the first and second influence coefficients. 28

8. The control method of hot-rolling finishing mill delivery temperature according to claim 6, further comprising: calculating, as a feedforward control process, a variation in the amount of cooling water for reducing the correction amount for the target temperature of the steel sheet on the 5 delivery side, which has been calculated in the target-temperature correction amount calculation process, wherein the variation in the amount of cooling water calculated in the feedforward control process is used as the variation in the amount of cooling water according to 10 the correction amount for the target temperature of the steel sheet on the delivery side calculated in the amount-of-cooling-water command process.

9. The control method of hot-rolling finishing mill delivery temperature according to claim 6, further comprising further comprising: 15 calculating, as a temperature-for-control-command calculation process, a target temperature of the steel sheet on the delivery side to be used for actual control, on the basis of the correction amount for the target temperature of the steel sheet on the delivery side calculated in the target-temperature correction amount calculation process and the target 20 temperature of the steel sheet on the delivery side used in the amount-ofcooling- water presetting process; and calculating, as a feedback control process, a variation in the amount of cooling water to reduce a difference between the target temperature of the steel sheet on the delivery side calculated in the temperature-for25 control-command calculation process and a temperature of the steel sheet measured on the delivery side of the hot-rolling finishing mill, wherein the variation in the amount of cooling water calculated in the feedback control process is used as the variation in the amount of cooling water according to the correction amount for the target temperature of the steel sheet on the delivery 30 side calculated in the amount-of-cooling-water command process.

10. The control method of hot-rolling finishing mill delivery temperature according to claim 6, further comprising: 29 calculating, as a feedforward control process, a first variation in the amount of cooling water for reducing the correction amount for the target temperature of the steel sheet on the delivery side, which has been calculated in the target-temperature correction amount calculation 5 process; calculating, as a temperature-for-control-command calculation process, a target temperature of the steel sheet on the delivery side to be used for actual control, on the basis of the correction amount for the target temperature of the steel sheet on the delivery side calculated in the 10 target-temperature correction amount calculation process and the target temperature of the steel sheet on the delivery side used in the amount-ofcooling- water presetting process; and calculating, as a feedback control process, a second variation in the amount of cooling water to reduce a difference between the target temperature of 15 the steel sheet on the delivery side calculated in the temperature-forcontrol- command calculation process and a temperature of the steel sheet measured on the delivery side of the hot-rolling finishing mill, wherein an amount obtained by adding the first and second variations, which are respectively given weight, is used as the variation in the amount of cooling water 20 according to the correction amount for the target temperature of the steel sheet on the delivery side calculated in the amount-of-cooling-water command process.

HOT-ROLLING FINISHING MILL DELIVERY TEMPERATURE CONTROLLER AND
CONTROL METHOD OF THE SAME
TECHNICAL FIELD
[0001] The present invention relates to a hot-5 rolling finishing mill delivery
temperature controller that is suitable for obtaining a uniform material property of a
steel sheet in a longitudinal direction, and its control method.
BACKGROUND ART
[0002] A conventional method of controlling a delivery temperature of a hot-rolling
10 finishing mill determines a rolling speed and amount of cooling water between stands
so as to achieve a target value of the finishing mill delivery temperature associated
with a steel sheet (coil), which has been received from a host computer, and corrects
the rolling speed or the amount of cooling water between stands so that a finishing
mill delivery temperature measured by a thermometer is equal to the target
15 temperature value of the steel sheet on a delivery side of the finishing mill in a
longitudinal direction. With such kind of control, as the rolling progresses, the rolling
speed is gradually increased because a temperature of the steel sheet on an entry
side of the hot-rolling finishing mill decreases with the lapse of time. On the other
hand, material property of the steel sheet depends on a temperature and a strain rate
20 during the rolling, and therefore controlling the steel sheet so as to have a uniform
temperature in the longitudinal direction causes the rolling speed to be changed and
then the strain rate of each stand to be changed, resulting in a problem that the
material property of the steel sheet varies in the longitudinal direction.
[0003] As a conventional technique of modifying the target temperature of the steel
25 sheet on the delivery side of the finishing mill in accordance with the rolling speed,
Patent Document 1, for example, discloses a technique of correcting the target
temperature, which is set as the delivery temperature of the steel sheet being
continuously hot- rolled by the finishing mill, in accordance with the variation in the
rolling speed of the steel sheet. Specifically, ∂Tf / ∂Va (Tf: finishing mill delivery
30 temperature, Va: rolling speed) is used to predict the variation in the finishing mill
delivery temperature with the variation in the rolling speed. Then, if the rolling speed
varies, the predicted variation in the finishing mill delivery temperature is added to the
target value of the finishing mill delivery temperature to obtained a finishing mill
3
delivery temperature to be used as a target value for control. As a result, the
uniformity of the temperature of the steel sheet can be enhanced in the longitudinal
direction, according to the document.
PRIOR ART DOCUMENT
5 Patent Document
[0004] Patent Document 1: Japanese Patent Application Publication No. H08-
252624
SUMMARY OF THE INVENTION
Problems to be solved
10 [0005] However, the technique disclosed in Patent Document 1 is intended to
enhance the uniformity of the temperature of the steel sheet in the longitudinal
direction, and therefore uniformity of material properties of the steel sheet in the
longitudinal direction is not taken into account. That is, a strain rate is varied due to
variation in a rolling speed when the steel sheet is rolled at each stand, however the
15 influence on the material properties by the variation in the strain rate is not taken into
account.
[0006] The present invention has been made to solve the conventional problems
as described above, and is intended to provide a hot-rolling finishing mill delivery
temperature controller that is capable of uniforming material properties of a steel
20 sheet in the longitudinal direction, and a control method of the same.
Solution to Problems
[0007] The present invention provides a hot-rolling finishing mill delivery
temperature controller used for controlling a temperature of a steel sheet to be rolled
in a hot-rolling finishing mill inclusive of: a plurality of rolling stands for continuously
25 rolling a steel sheet; and a plurality of between-stands cooling devices for cooling the
steel sheet, each being arranged between two rolling stands which are adjacent to
each other, on a delivery side of the hot-rolling finishing mill, and the controller
includes: a sheet-temperature estimation model storage that stores sheettemperature
estimation models for estimating the temperature of a steel sheet to be
30 rolled; an amount-of-cooling-water presetter that estimates the temperature of the
steel sheet on the delivery side of the hot-rolling finishing mill, before rolling the steel
sheet, based on a preset rolling speed of the steel sheet, amount of cooling water to
be injected from the plurality of between-stands cooling devices, the temperature of
the steel sheet on an entry side of the hot-rolling finishing mill, and the sheet4
temperature estimation model, and then presets the amount of cooling water on the
basis of an estimated result so that the temperature of the steel sheet on the delivery
side coincides with a target temperature predetermined in advance; a targettemperature
correction amount calculator that obtains a variation in the rolling speed
to be detected by the rolling stands during the rolling 5 of the steel sheet from the
preset rolling speed, and calculates a correction amount for the target temperature
on the delivery side of the steel sheet for reducing influence from the variation in the
rolling speed on the material property values of the steel sheet; and an amount-ofcooling-
water commander that calculates a variation in the amount of cooling water
10 according to the correction amount for the target temperature of the steel sheet on
the delivery side, and outputs the amount of cooling water, which has been preset by
the amount-of-cooling-water presetter and then corrected with the variation in the
amount of cooling water calculated, to the between-stands cooling device.
Advantageous Effects of the Invention
15 [0008] According to the present invention, a hot-rolling finishing mill delivery
temperature controller that is capable of uniforming material properties of a steel
sheet in the longitudinal direction and a control method thereof are provided.
BRIEF DESCRIPTION OF DRAWINGS
[0009] FIG. 1 is a diagram showing an exemplary configuration of a hot-rolling
20 finishing mill delivery temperature controller and a controlled object;
FIG. 2 is a diagram showing an exemplary configuration of a target temperature table
that is stored in a target-temperature table storage;
FIG. 3 is a diagram showing an exemplary configuration of a rolling speed table that
is stored in a rolling-speed table storage;
25 FIG. 4 is a diagram showing an exemplary configuration of a standard-amount-ofwater
pattern table that is stored in a standard-amount-of-water pattern storage 23;
FIG. 5 is a diagram showing an exemplary flow of an amount-of-cooling-water
presetting process to be executed by an amount-of-cooling-water presetter;
FIG. 6 is a diagram showing an exemplary flow of an influence-coefficient calculation
30 process to be executed by an influence-coefficient calculator;
FIG. 7 is a diagram showing an exemplary flow of a material-property prediction
process to be executed by a material-property predictor;
5
FIG. 8 is a diagram showing an exemplary flow of a target-temperature-correctionamount
calculation process to be executed by a target-temperature-correctionamount
calculator;
FIG. 9 is a diagram showing an exemplary flow of a temperature-for-controlcommand
calculation process to be executed by a temperature-5 for-control-command
calculator; and
FIG. 10 is a diagram showing an exemplary flow of an amount-of-cooling-water
command process to be executed by an amount-of-cooling-water commander.
DETAILED DESCRIPTION
10 [0010] Hereinafter, a description will be given in detail of embodiments according to
the present invention, with reference to the accompanying drawings.
[0011] FIG. 1 is a diagram showing an exemplary configuration of a hot-rolling
finishing mill delivery temperature controller 100 and a controlled object 50. Here, a
host computer 40 sends information (such as a steel grade of the steel sheet 53, a
15 chemical composition, a thickness of the sheet, a rolling speed, and a target
temperature), which is required for controlling a steel sheet 53 to be rolled next time,
to the hot-rolling finishing mill delivery temperature controller 100. The hot-rolling
finishing mill delivery temperature controller 100 is adapted to receive such material
information and rolling-instruction information on the steel sheet 53 being sent from
20 the host computer 40, and to output a control signal for implementing the rollinginstruction
information to the controlled object 50, in response to various signals sent
from the controlled object 50,.
[0012] First, a description will be given of a configuration of the controlled object 50.
In the present embodiment, the controlled object 50 is a hot-rolling facility that is
25 configured here to include a hot-rolling finishing mill 51 for finish-rolling the steel
sheet 53, and a finishing-mill delivery temperature meter 60 for measuring a
temperature (delivery temperature) of the steel sheet 53 immediately after the rolling.
The hot-rolling finishing mill 51 includes, for example, six rolling stands F1 to F6 for
rolling the steel sheet 53 with respective mill rolls 59. The steel sheet 53 is moved
30 from the rolling stand F1 toward the rolling stand F6 (from left to right in the figure),
while being rolled by the respective mill rolls 59 of the rolling stands F1 to F6.
[0013] Between-stands cooling devices 54 to 58 are arranged between the
respective rolling stands F1 to F6, i.e., between the rolling stands F1 and F2, F2 and
6
F3, F3 and F4, F4 and F5, and F5 and F6. Each of the between-stands cooling
devices 54 to 58 injects cooling water to the steel sheet 53 for cooling the steel sheet
53 in accordance with a between-stands amount-of-cooling-water command from the
hot-rolling finishing mill delivery temperature controller 100.
[0014] Next, a description will be given of a configuration 5 of the hot-rolling finishing
mill delivery temperature controller 100. As shown in FIG. 1, the hot-rolling finishing
mill delivery temperature controller 100 is mainly divided into two functional blocks: a
preset controller 10 and a dynamic controller 30. The preset controller 10 presets the
amount of cooling water to be injected from the between-stands cooling devices 54 to
10 58 before the steel sheet 53 being rolled by the hot-rolling finishing mill 51. In
addition, the dynamic controller 30 appropriately modifies the amount of cooling
water to be injected from the between-stands cooling devices 54 to 58, which is
preset by the preset controller 10, while the steel sheet 53 to be rolled is actually
being rolled, in accordance with the rolling speed, which is detected by the mill rollers
15 59, and the temperature on the delivery side, which is detected by the finishing-mill
delivery temperature meter 60.
[0015] The preset controller 10 is configured to include an amount-of-cooling-water
presetter 11, an influence-coefficient calculator 12, a material-property predictor 13, a
target-temperature table storage 21, a speed table storage 22, a standard-amount-of20
water pattern storage 23, and a sheet-temperature estimation model storage 24. In
addition, the dynamic controller 30 is configured to include a target-temperature
correction amount calculator 31, a feedforward controller 32, a temperature-forcontrol-
command calculator 33, a feedback controller 34, and an amount-of-coolingwater
commander 35.
25 [0016] The target-temperature table storage 21, the speed table storage 22, and
the standard-amount-of-water pattern storage 23 in the preset controller 10 are
stored with information required for controlling the steel sheet 53, which is sent from
the host computer 40. In addition, the sheet-temperature estimation model storage
24 is stored with various model formulas for estimating the delivery temperature of
30 the steel sheet 53 from the hot-rolling finishing mill 51.
[0017] The amount-of-cooling-water presetter 11 retrieves data of standard amount
of water from the standard-amount-of-water pattern storage 23, before rolling the
steel sheet 53, and executes operation using the sheet-temperature estimation
7
model stored in the sheet-temperature estimation model storage 24 to estimate the
delivery temperature of the steel sheet 53 from the hot-rolling finishing mill 51. Then,
it calculates the amount of cooling water to be injected from the between-stands
cooling devices 54 to 58 based on the delivery temperature to output the calculated
amount of cooling water to the amount-of-cooling-water 5 commander 35 as a preset
amount of cooling water.
[0018] The material-property predictor 13 predicts material properties of the steel
sheet 53 on the delivery side of the hot-rolling finishing mill 51 based on chemical
composition and a rolling schedule of the steel sheet 53, which have been sent from
10 the host computer 40 and stored in the target-temperature table storage 21, the
roling-speed table storage 22, and the standard-amount-of-water pattern storage 23,
and rolling reductions at the rolling stands F1 to F6 and temperature variation of the
steel sheet 53, which are calculated using the rolling schedule. In addition, the
influence-coefficient calculator 12 calculates, as an influence coefficient, the
15 relationship between a variation in the rolling speed or the finishing-mill delivery
temperature and a variation in the material properties, based on the calculation result
by the material-property predictor 13.
[0019] The target-temperature correction amount calculator 31 obtains a variation
in the rolling speed from the mill roller 59, and uses the influence coefficient
20 calculated by the influence-coefficient calculator 12 to calculate a correction amount
for the target temperature of the finishing-mill delivery temperature for keeping the
material properties at a constant level. The feedforward controller 32 uses the
correction amount for the target temperature calculated by the target-temperature
correction amount calculator 31 to calculate the correction amount for cooling water
25 by the between-stands cooling devices 54 to 58. The temperature-for-controlcommand
calculator 33 uses the correction amount for the target temperature
calculated by the target-temperature correction amount calculator 31 to calculate a
temperature on the delivery side of the hot-rolling finishing mill 51 for a command,
which is used for actual control.
30 [0020] Further, the feedback controller 34 modifies the respective amounts of
cooling water by the between-stands cooling devices 54 to 58 to reduce the deviation
between the temperature for a command calculated by the temperature-for-controlcommand
calculator 33 and the finishing-mill delivery temperature detected by the
8
finishing-mill delivery temperature meter 60. The amount-of-cooling-water
commander 35 calculates the amount of cooling water to be finally outputted for each
of the between-stands cooling devices 54 to 58, based on the preset amount of
cooling water outputted from the amount-of-cooling-water presetter 11, the correction
amount for cooling water calculated by the feedforward 5 controller 32, and the
modified amount of cooling water calculated by the feedback controller 34.
[0021] The hot-rolling finishing mill delivery temperature controller 100 configured
as above is implemented, as a concrete hardware, by a computer or a workstation,
not shown, having an arithmetic processing unit and a storage device. Then,
10 functional blocks such as the amount-of-cooling-water presetter 11, the influencecoefficient
calculator 12, and the material-property predictor 13 in the preset
controller 10, as well as the target-temperature correction amount calculator 31, the
feedforward controller 32, the temperature-for-control-command calculator 33, the
feedback controller 34, and the amount-of-cooling-water commander 35 in the
15 dynamic controller 30 are implemented by the arithmetic processing unit executing
predetermined programs stored in the storage device consisting of a semiconductor
memory or a hard disk device. In addition, the target-temperature table storage 21,
the speed table storage 22, the standard-amount-of-water storage 23, and the sheettemperature
estimation model storage 24 in the preset controller 10 are implemented
20 by predetermined data being stored in a region allocated in the storage device.
[0022] FIG. 2 is a diagram showing an exemplary configuration of a targettemperature
table 21T to be stored in the target-temperature table storage 21. As
shown in FIG. 2, the target-temperature table 21T is a table in which each type (steel
grade) of the steel sheet 53 to be rolled is associated with the target temperature
25 thereof on the delivery side of the hot-rolling finishing mill 51. In the exemplary targettemperature
table 21T in FIG. 2, the steel sheet 53 having a steel grade of SS400,
for example, is associated with a target temperature of 900°C.
The amount-of-cooling-water presetter 11 determines the steel grade of the steel
sheet 53 to extract a target temperature associated with the steel grade from the
30 target-temperature table 21T.
[0023] FIG. 3 is a diagram showing an exemplary configuration of a speed table
22T to be stored in the speed table storage 22. As shown in FIG. 3, the speed table
22T is a table in which each combination of the steel grade of the steel sheet 53 to
9
be rolled, a sheet thickness, and a sheet width is associated such as with an initial
speed, a first acceleration, a second acceleration, a steady speed, a deceleration,
and a final speed with respect to the rolling speed of the steel sheet 53 on the
delivery side of the rolling stand F6 at the final stage. Here, the initial speed is a
rolling speed of the steel sheet 53 at a time of a leading 5 edge of the steel sheet 53
being discharged from the roll stand F6, the steady speed is a rolling speed at a time
of the steel sheet 53 being discharged from the rolling stand F6 after the steel sheet
53 is accelerated to have a constant speed, and the final speed is a rolling speed at a
time of a trailing edge of the steel sheet 53 being discharged from the roll stand F6
10 after the steel sheet 53 is decelerated. Note that the steel sheet 53 is assumed here
to be accelerated from the initial speed to the steady speed in two steps of the first
and second accelerations, and decelerated from the steady speed to the final speed
in one step of deceleration.
[0024] In the exemplary speed table 22T in FIG. 3, the steel sheet 53 having a
15 steel grade of SS400, a sheet thickness of 1.4 mm or less, and a sheet width of 1000
to 1400 mm, for example, is associated with an initial speed of 650 mpm (meter per
minute), a first acceleration of 2 mpm/s (meter per minute per second), a second
acceleration of 12 mpm/s, a steady speed of 1050 mpm, a deceleration of 30 mpm/s,
and a final speed of 900 mpm.
20 [0025] It should be noted that once the rolling speed of the steel sheet 53 at a time
of the steel sheet 53 being discharged from the rolling stand F6 is determined, a
rotation speed of the mill roll 59 at the rolling stand F6 can be determined in a
predetermined operation, which in turn allows the rotation speeds of the mill rolls 59
at the remaining rolling stands F1 to F5 to be determined in accordance with the
25 respective rolling reductions (a ratio of an entry-side sheet thickness to a deliveryside
sheet thickness) at the rolling stands F1 to F6.
[0026] FIG. 4 is a diagram showing an exemplary configuration of a standardamount-
of-water pattern table 23T to be stored in the standard-amount-of-water
pattern storage 23. As shown in FIG. 4, the standard-amount-of-water pattern table
30 23T is a table in which each combination of the steel grade, the sheet thickness, and
the sheet width of the steel sheet 53 to be rolled is associated with a standardamount-
of-water pattern, which has initial values of the amount of cooling water to be
injected respectively from the between-stands cooling devices 54 to 58. Note that the
10
initial value of the amount of cooling water described here is assumed to be
represented by the percentage (percent) of the amount of cooling water to the
maximum amount of cooling water from each of the between-stands cooling devices
54 to 58.
[0027] In the exemplary standard-amount-of-5 water pattern table 23T in FIG. 4, the
steel sheet 53 having a steel grade of SS400, a sheet thickness of 3.0 to 4.0 mm,
and a sheet width of 1200 mm, for example, is associated, as the initial values of the
amount of cooling water (i.e., standard-amount-of-water pattern) from the betweenstands
cooling devices 54, 55, 56, 57, 58, with 80 %, 70 %, 50 %, 0 % (no water
10 injection), 0 % (no water injection), respectively.
[0028] It should be noted that the contents of the standard-amount-of-water pattern
table 23T, i.e., the initial values of the amount of cooling water (standard-amount-ofwater
pattern) from the between-stands cooling devices 54, 55, 56, 57, 58, are
determined in advance based on simulation and/or actual rolling performance in
15 accordance with the steel grade, the sheet thickness, and the sheet width of the steel
sheet 53. At this time, the standard-amount-of-water pattern is determined based on
the initial speed of the steel sheet 53 and the temperature of the steel sheet at the
leading edge assumed on the entry side of the hot-rolling finishing mill 51, so as to
substantially satisfy the target temperature of the finishing-mill delivery temperature,
20 and to have a desired pattern of temperature decrease due to the rolling at the
respective rolling stands F1 to F6.
[0029] FIG. 5 is a diagram showing an exemplary flow of the amount-of-coolingwater
presetting process executed by the amount-of-cooling-water presetter 11. As
shown in FIG. 5, the amount-of-cooling-water presetter 11 first refers to the target25
temperature table 21T and the speed table 22T to obtain the target temperature and
the initial speed associated with the steel grade, the sheet thickness, and the sheet
width of the steel sheet 53 to be rolled next time (step S11). In addition, the amountof-
cooling-water presetter 11 refers to the standard-amount-of-water pattern table
23T to obtain the standard-amount-of-water pattern associated with the steel grade,
30 the sheet thickness, and the sheet width of the steel sheet 53 (step S12).
[0030] Subsequently, the amount-of-cooling-water presetter 11calculates a
predictive value of the finishing mill delivery temperature (hereinafter, referred to as
FDT) under the conditions of the target temperature, the initial speed, and the
11
standard-amount-of-water pattern, which have been obtained above (step S13). As
previously described, for the cases where the steel sheet 53 is rolled by the rolling
stands F1 to F6 and cooling water is injected from the between-stands cooling
devices 54 to 58, various calculation formulas required for estimating the temperature
of the steel sheet 53 are stored in the sheet-temperature 5 estimation model storage
24 as sheet-temperature estimation models. Then, the amount-of-cooling-water
presetter 11 calculates a temperature, which will be decreased while the steel sheet
53 is moved from the rolling stand F1 to the rolling stand F6, in accordance with the
sheet-temperature estimation models to obtain the FDT. Note that the initial value of
10 the temperature of the steel sheet 53 at this time is called a finishing mill entry
temperature (hereinafter, referred to as FET).
[0031] The sheet-temperature estimation models include those models for
calculating such as heat radiation from the steel sheet 53, convective heat transfer,
processing heat due to the plastic deformation by the rolling, per-contact conductive
15 heat to be lost when the steel sheet 53 comes in contact with the mill roll 59, and
friction heat generated by the friction of the steel sheet 53 and the mill roll 59. In
addition, a model is included for calculating such as a temperature decrease caused
by water injection from the between-stands cooling devices 54 to 58.
[0032] Various model formulas have been studied as models for calculating the
20 amount of heat generated and the amount of heat discharged as listed above, and
detailed examples thereof are described, for example, in “The Theory and Practice of
the Sheet Rolling” (compiled by Iron and Steel Institute of Japan, 1984).
[0033] Here, an exemplary model formula for calculating a heat transfer coefficient
“hr” due to heat radiation from the steel sheet 53 is presented under Equation (1).
hr = σ * ε * [{(273 + Tsu) / 100} 4 - {(273 + Ta) / 100} 425 ] / (Tsu - Ta) (1),
where σ: Stefan Boltzmann constant (= 4.88),
ε: emissivity,
Ta: air temperature (°C), and
Tsu: surface temperature of the steel sheet (steel sheet temperature).
30 [0034] The steel sheet 53 loses heat according to the heat transfer coefficient “hr”
in Equation (1), even for simply being moved between rolling stands F1 to F6. In
addition, if the steel sheet 53 is cooled by the between-stands cooling devices 54 to
58, heat is lost in accordance with the amount of cooling water to be injected. A
12
model formula in this case is also described in “The Theory and Practice of the Sheet
Rolling” (compiled by Iron and Steel Institute of Japan, 1984) cited above, and then it
will not be inserted here.
[0035] Further, the sum of heat lost or given due to individual factors is here
substituted collectively with a heat transfer coefficient, to calculate 5 the amount of heat
to be lost or given from/to the steel sheet 53 during a certain time Δ. Based on the
temperature of the steel sheet 53 before the time Δ elapses, the movement of heat
during the time Δ is added or subtracted by the following Equation (2).
Tn = Tn−1 − (ht + hb) * Δ / (ρ * C * B) (2),
10 where Tn: current sheet temperature,
Tn−1: sheet temperature (steel sheet temperature) before time Δ,
ht: heat transfer coefficient of face side of steel sheet,
hb: heat transfer coefficient of reverse side of steel sheet,
ρ: density of steel sheet,
15 C: specific heat of steel sheet, and
B: thickness of steel sheet.
[0036] Furthermore, if thermal conductivity of the steel sheet 53 in the thickness
direction needs to be taken into account, a well-known heat equation may be solved
for the calculation. The heat equation, for example, is represented by the following
20 Equation (3), and techniques of difference calculation using a computer have been
published in various technical documents.
∂T / ∂t = {λ / (ρ * C)} * (∂2T / ∂x2) (3),
where λ: thermal conductivity,
T: steel sheet temperature,
25 x: position in thickness direction, and
t: time.
[0037] Now, a description will return to the amount-of-cooling-water presetting
process in FIG. 5. In step S13, the amount-of-cooling-water presetter 11 calculates
above Equations (1) and (2) by advancing the time from a time when a portion of the
30 steel sheet 53 is drawn into the rolling stand F1 until a time when it exits the rolling
stand F6, to predict the FDT for the portion of the steel sheet 53.
13
[0038] Next, the amount-of-cooling-water presetter 11 determines whether the FDT
predicted in step S13 falls within a predetermined range (± α: “α” is a positive
temperature value set in advance, such as 1°C) for the target temperature (step S14).
As a result of the determination, if the predicted FDT is within the predetermined
range (± α) for the target temperature (“Yes” in step S14), 5 the amount-of-coolingwater
presetter 11 maintains the current amount of cooling water from the betweenstands
cooling devices 54 to 58 (step S15).
[0039] On the other hand, if the predicted FDT is not within the predetermined
range (± α) for the target temperature (“No” in step S14), the amount-of-cooling-water
10 presetter 11 increases the amount of cooling water from the between-stands cooling
devices 54 to 58 on the condition that the FDT is larger than [the target temperature
+ α], and decreases the amount of cooling water on the condition that the FDT is
smaller than [the target temperature – α] (step S16). Here, when the amount of
cooling water is increased or decreased, the amount of cooling water may be
15 increased or decreased from all the between-stands cooling devices 54 to 58 or
some of the between-stands cooling device 54 to 58, which is/are selected therefrom.
[0040] Next, the amount-of-cooling-water presetter 11 determines whether an
ending condition is satisfied (step S17), and if the ending condition is not satisfied
(“No” in step S17), it returns to step S13 to repeatedly execute step S13 and beyond.
20 The ending condition described here is such that whether the number of times to
repeat steps S13, S14, and S16 has exceeded a predetermined upper limit value.
Normally, repeating steps S13, S14, and S16 is cancelled by the determination in
step S14 that the FDT has fallen within the predetermined range (± α) for the target
temperature, however if this is not the case, the repeating is determined to be
25 cancelled in step S17.
[0041] The amount-of-cooling-water presetter 11 determines the speed pattern of
the steel sheet 53, after step S15 or if it is determined in step S17 that the ending
condition is satisfied (“Yes” in step S17), in accordance such as with acceleration
rates (the first and second accelerations) and the steady speed as determined in the
30 speed table 22T (step S18).
[0042] With above processing, the amount-of-cooling-water presetter 11 has
determined the respective amounts of cooling water from the between-stands cooling
devices 54 to 58 for the steel sheet 53 to be rolled next time, and therefore it outputs
14
the determined amount of cooling water to the amount-of-cooling-water commander
35 as the preset amount of cooling water (step S19) to end the amount-of-coolingwater
presetting process.
[0043] It should be noted that such a technique has been used in the processing
flow shown in FIG. 5, in which the initial speed of the steel sh 5 eet 53 is made constant
and the amounts of cooling water to be injected from the between-stands cooling
devices 54 to 58 are varied for predicting the FDT, but there is another technique as
follows. That is, the acceleration “Vr” of the steel sheet 53 can be calculated using
the following Equation (4) in accordance with a decreasing rate of FET, which is
10 referred to as ΔFETr, at the leading edge of the steel sheet 53.
Vr = (∂V / ∂FDT) * (∂FDT / ∂FET) * ΔFETr (4),
where (∂V / ∂FDT), (∂FDT / ∂FET): influence coefficient (a constant of influence
coefficient will be described later in detail).
[0044] That is, the amount-of-cooling-water presetter 11 may make the amount-of15
cooling-water command to the between-stands cooling devices 54 to 58 constant and
increase or decrease the initial speed of the steel sheet 53, to obtain an initial speed
command for a target FDT. In that case, if the processing in step S16 is replaced with
such processing of increasing the initial speed on the condition that the FDT is lower
than [the target temperature – α], and decreasing the initial speed on the condition
20 that the FDT is higher than [the target temperature + α], the flow in FIG. 5 can be
used as it is.
[0045] FIG. 6 is a diagram showing an exemplary flow of an influence-coefficient
calculation process executed by the influence-coefficient calculator 12. As shown in
FIG. 6, the influence-coefficient calculator 12 first specifies an FDTt, which is a target
25 temperature of a portion of the steel sheet 53 at a predetermined calculation point on
the delivery side of the hot-rolling finishing mill 51, and a rolling speed V at a time of
the portion being rolled, to execute a material-property prediction process (step S21).
Here, for the rolling speed V, a rim speed of the mill roll 59 of the rolling stand F6 at
the final stage is used as a representative value, and is called a reference rolling
30 speed. Note that the material-property prediction process is executed by the materialproperty
predictor 13, which will be separately described in detail with reference to
FIG. 7.
15
[0046] Next, the influence-coefficient calculator 12 obtains, as a result of executing
the material-property prediction process, an austenite grain size γ1 and a dislocation
density ρ1 of the steel sheet 53 in accordance with the rolling speed V (step S22).
[0047] Next, the influence-coefficient calculator 12 increases the reference rolling
speed V by ΔV, that is, increases the rolling speed from 5 V to [V + ΔV] to execute the
material-property prediction process (step S23). Then, as a result of the processing,
it obtains an austenite grain size γ2 and a dislocation density ρ2 of the steel sheet 53
in accordance with the rolling speed [V + ΔV] (step S24).
[0048] Next, the influence-coefficient calculator 12 calculates first influence
10 coefficients defined with the following Equations (5-1) and (5-2). In other words, it
calculates a variation in the austenite grain size γ (∂γ / ∂V) and a variation in the
dislocation density (∂ρ / ∂V) with respect to the variation ΔV of the rolling speed (step
S25).
(∂γ / ∂V) = (γ2 – γ1) / ΔV (5-1), and
15 (∂ρ / ∂V) = (ρ2 – ρ1) / ΔV (5-2).
[0049] In addition, the influence-coefficient calculator 12 increases the FDTt by
ΔFDTt to be set as the delivery temperature of the hot-rolling finishing mill 51, that is,
increases the temperature from FDTt to [FDTt + ΔFDTt] to execute the materialproperty
predictor 13 (step S26). Then, as a result of the processing, it obtains an
20 austenite grain size γ3 and a dislocation density ρ3 of the steel sheet 53 in
accordance with[FDTt + ΔFDTt] (step S27).
[0050] Next, the influence-coefficient calculator 12 calculates second influence
coefficients defined with the following Equations (6-1) and (6-2). In other words, it
calculates a variation in the austenite grain size γ (∂γ / ∂FDT) and a variation in the
25 dislocation density ρ (∂ρ / ∂FDT) with respect to the variation ΔFDT of the FDT (step
S28).
(∂γ / ∂FDT) = (γ3 – γ1) / ΔFDT (6-1), and
(∂ρ / ∂FDT) = (ρ3 – ρ1) / ΔFDT (6-2).
[0051] Next, the influence-coefficient calculator 12 determines whether the
30 calculations of the first and second influence coefficients defined with Equations (5-1),
(5-2), (6-1), (6-2) have been completed for all predetermined calculation points of the
steel sheet 53 in the longitudinal direction (step S29). As a result of the determination,
16
if the calculations of these influence coefficients have not been completed for all
calculation points (“No” in step S29), the module repeatedly executes the processing
in steps S21 to S29 for any uncompleted calculation point. Alternatively, if the
calculations of these first and second influence coefficients have been completed for
all the calculation points (“Yes” in step S29), it ends 5 the influence-coefficient
calculation process.
[0052] It should be noted that three points of the leading edge, the middle, and the
tailing edge may be selected as the calculation points in accordance with a variation
in the speed of the steel sheet 53. Alternatively, for simplicity, only one point
10 representative of the longitudinal direction of the steel sheet 53, such as the center,
may be selected. Still alternatively, the number of calculation points may be
increased for a thin sheet (such as a steel sheet 53 having a thickness of about 1.8
mm or less after the rolling), which has a large variation in the speed, but may be
decreased for a thick sheet.
15 Hereinafter, in the present embodiment, the calculation point is assumed to be set
only at the leading edge of the steel sheet 53, in order to avoid a complicated
description.
[0053] FIG. 7 is a diagram showing an exemplary flow of the material-property
prediction process executed by the material-property predictor 13. The material20
property prediction process is activated in the influence-coefficient calculation
process shown in FIG. 6 to calculate the austenite grain size γ and the dislocation
density ρ of the steel sheet 53 on the delivery side of the hot-rolling finishing mill 51
for reporting the result to the influence-coefficient calculation process.
[0054] As shown in FIG. 7, the material-property predictor 13 first obtains the
25 rolling speed V and FDTt specified by the influence-coefficient calculation process
(see FIG. 6) (step S31). Then, the material-property predictor 13 obtains from the
host computer 40 information such as overheating history and rolling history of the
steel sheet 53, for example, in a rough rolling process which precedes the finish
rolling (step S32). In addition, the material-property predictor 13 obtains information
30 such as a variation in the temperature of the steel sheet 53, which has been
predicted in the amount-of-cooling-water presetting process (see FIG. 5) (step S33).
[0055] Subsequently, the material-property predictor 13 predictively calculates the
austenite grain size γ and the dislocation density ρ on the delivery side of the hot17
rolling finishing mill 51 when the rolling is made under the condition of the specified
rolling speed V and FDTt (step S34). Then, it reports the results of the predictive
calculation to the influence-coefficient calculation process (step S35), and ends the
material-property prediction process.
[0056] It should be noted that the austenite grain 5 size γ and the dislocation density
ρ on the delivery side of the hot-rolling finishing mill 51 can be calculated by using
information such as heating history of not only the finishing process but also the
preceding process, temperature-drop history after heating, a rolling temperature, and
a deformation speed at the time of rolling, in addition to the steel grade and the
10 chemical composition of the steel sheet 53. Details of such a calculation method are
described, for example, in “Report by Study Group on FEM Analysis Technology for
Creating Material Function” (by Study Group on FEM Analysis Technology for
Creating Material Function in Rolling Theory Subcommittee in Production Technology
Division of “Iron and Steel Institute of Japan,” June, 2001).
15 [0057] FIG. 8 is a diagram showing an exemplary flow of a target-temperaturecorrection-
amount calculation process to be executed by a target-temperaturecorrection-
amount calculator 31. As shown in FIG. 8, the target-temperaturecorrection-
amount calculator 31 first obtains the rolling speed of the rolling stand F6
at the final stage of the hot-rolling finishing mill 51 (step S41), and calculates the
20 variation ΔV from the reference rolling speed V for the rolling speed (step S42).
[0058] Subsequently, the target-temperature-correction-amount calculator 31
calculates a correction amount ΔFDTt for the FDTt in accordance with the following
Equation (7) for reducing a variation in material properties due to a variation in the
rolling speed of the steel sheet 53 to equalize the material properties in the
25 longitudinal direction (step S43).
ΔFDTt = {α * (∂γ / ∂V) / (∂γ / ∂FDT) + (1-α) * (∂ρ / ∂V) / (∂ρ / ∂FDT)} * ΔV (7),
where α: constant (0 to 1) .
[0059] It should be noted that the constant α is a constant expressed by a ratio
about how much the austenite grain size γ and the dislocation density ρ are
30 respectively taken into account on the influence of a variation in the rolling speed V
giving the material properties of the steel sheet on the delivery side of the hot-rolling
finishing mill 51. Incidentally, if the constant α is 1, the ΔFDTt is calculated so that the
austenite grain size γ remains constant, and if the constant α is 0, the ΔFDTt is
18
calculated so that the dislocation density ρ remains constant. In addition, if the
constant α has an intermediate value between 0 and 1, both are prorated by the ratio
according to the value of the constant α.
[0060] The target-temperature-correction-amount calculator 31 outputs the
correction amount ΔFDTt for the FDTt calculated in step 5 S43 to the feedforward
controller 32 and the temperature-for-control-command calculator 33 (step S44), and
ends the target-temperature-correction-amount calculation process.
[0061] FIG. 9 is a diagram showing an exemplary flow of the temperature-forcontrol-
command calculation process to be executed by the temperature-for-control10
command calculator 33. As shown in FIG. 9, the temperature-for-control-command
calculator 33 obtains the FDTt as a target temperature from the amount-of-coolingwater
presetter 11 (step S51), and further obtains the correction amount ΔFDTt for
the FDTt, which is outputted from the target-temperature-correction-amount
calculator 31 (step S52).
15 [0062] Subsequently, the temperature-for-control-command calculator 33
calculates an FDTtc, which is a target temperature on the delivery side of the hotrolling
finishing mill 51, to be used for actual control, in real time according to the
following Equation (8) (step S53).
FDTtc = FDTt + β * ΔFDTt (8),
20 where β: correction gain (0 to 1).
[0063] Next, the temperature-for-control-command calculator 33 outputs the target
temperature FDTtc obtained by the calculation to the feedback controller 34 (step
S54), and ends the temperature-for-control-command calculation process.
[0064] The feedforward controller 32 (its flowchart is not shown) receives the
25 correction amount ΔFDTt for the target temperature FDTt from the targettemperature-
correction-amount calculator 31 to calculate a variation in the amount of
cooling water, which causes the finishing-mill delivery temperature of the steel sheet
53 to be varied in accordance with the correction amount. If variations in the amount
of cooling water from the between-stands cooling devices 54 to 58 are assumed to
30 be the same, for the sake of simplicity, a variation ΔQFF of the amount of cooling
water can be calculated, for example, by the following Equation (9).
ΔQFF = a1 * (∂Q / ∂FDT) * ΔFDTt (9),
19
where a1: control gain, and
∂Q / ∂FDT: influence coefficient representing amount of water to cancel
variation in FDT (constant).
[0065] The feedback controller 34 (its flowchart is not shown) obtains a measured
temperature FDTa of the steel sheet 53 from the finishing-5 mill delivery temperature
meter 60, and calculates a variation in the amount of cooling water to cancel a
deviation ΔFDTa of the measured temperature FDTa from the target temperature
FDTtc taken from the temperature-for-control-command calculator 33. Again, if the
variation in the amount of cooling water from the respective between-stands cooling
10 devices 54 to 58 are assumed to be the same, for the sake of simplicity, the variation
ΔQFB of the amount of cooling water can be calculated, for example, by the following
Equation (10).
ΔQFB = a2 * (∂Q / ∂FDT) * (FDTtc – FDTa) (10),
where a2: control gain.
15 [0066] FIG. 10 is a diagram showing an exemplary flow of the amount-of-coolingwater
command process to be executed by the amount-of-cooling-water commander
35. As shown in FIG. 10, the amount-of-cooling-water commander 35 first obtains
from the amount-of-cooling-water presetter 11 the amount of cooling water which has
been set in advance in the amount-of-cooling-water presetting process (see FIG. 5)
20 for the respective between-stands cooling devices 54 to 58 (step S61). Here, it is
assumed that amounts of cooling water q1, q2, q3, q4, q5 have been set for the
between-stands cooling devices 54 to 58, respectively, and a set of the the amounts
of cooling water Qset is represented by the following Equation (11).
Qset = (q1, q2, q3, q4, q5) (11).
[0067] Next, the amount-of-cooling-water commander 35 obtains the variation ΔQFF 25
in the amount of cooling water which has been calculated by the feedforward
controller 32 (step S62), and further obtains a variation ΔQFB in the amount of cooling
water calculated by the feedback controller 34 (step S63).
[0068] Subsequently, the amount-of-cooling-water commander 35 corrects the
30 amounts of cooling water q1, q2, q3, q4, q5 (Qset) set in advance by using the
variation ΔQFF in the amount of cooling water calculated by the feedforward controller
32 and the variation ΔQFB in the amount of cooling water calculated by the feedback
20
controller 34 (step S64). Then, the amount-of-cooling-water commander 35 outputs
the corrected amounts of cooling water to the between-stands cooling devices 54 to
58 as a cooling command Qcont for the between-stands cooling devices 54 to 58.
That is, the cooling command Qcont is expressed, for example, in the following
5 Equation (12).
Qcont = (q1 + ΔQFF + ΔQFB, q2 + ΔQFF + ΔQFB, q3 + ΔQFF + ΔQFB,
q4 + ΔQFF + ΔQFB, q5 + ΔQFF + ΔQFB) (12).
[0069] As described above, in Equation (12), the cooling command Qcont is
calculated by simply adding [ΔQFF + ΔQFB] to the amounts of cooling water q1, q2, q3,
10 q4, q5 set in advance. This is a case in which the feedforward control amount and
the feedback control amount are equally weighted, however they may not always be
equally weighted. That is, for the calculation of the cooling command Qcont in
Equation (11), the ΔQFF and ΔQFB may appropriately be given weight of different
values, or one of the ΔQFF and ΔQFB may be given 0 (zero). In addition, each of the
15 variations ΔQFF, ΔQFB in the amount of cooling water is here assumed to be all the
same for the respective between-stands cooling devices 54 to 58, but may be
different.
[0070] As described above, in the present embodiment, the correction amount
ΔFDTt for the target temperature FDTt on the delivery side of the finishing-mill is
20 calculated so as to reduce a variation in material properties due to a variation in the
rolling speed of the steel sheet 53. Then, in accordance with the correction amount
ΔFDTt, the amount of cooling water from the between-stands cooling devices 54 to
58, which has been set in advance, is corrected. Therefore, the hot-rolling finishing
mill delivery temperature controller 100 according to the present embodiment has an
25 advantageous effect of being capable of making the material properties of the steel
sheet 53 to be rolled uniform in the longitudinal direction.
[0071] It should be noted that in the embodiment described above, it is assumed
that the material-property prediction process and the influence-coefficient calculation
process are executed for every steel sheet 53 to be rolled next time, however, once
30 calculated, the influence-coefficient may be stored in the storage device in
association with conditions at that time such as the steel grade, the sheet thickness,
the sheet width, the target temperature, the pattern of the rolling speed, and the
heating history. Then, when a different steel sheet 53 is to be rolled, if an influence
21
coefficient having matching conditions is stored in the storage device, the stored
influence coefficient may be used without executing the material-property prediction
process and the influence-coefficient calculation process.
[0072] The present invention is not limited to the embodiments described above
and will include various modifications. The above-5 mentioned embodiments are
described in detail in order to better illustrate the present invention and are not
necessarily limited to those including all the configurations as described above. In
addition, a part of the configuration of an embodiment may be replaced by a part of
the configuration of another embodiment, and further the configuration of an
10 embodiment may be added with the configuration of another embodiment partly or as
a whole.
LEGEND FOR REFERENCE NUMERALS
[0073] 10 Preset controller
11 Amount-of-cooling-water presetter
15 12 Influence-coefficient calculator
13 Material-property predictor
21 Target-temperature-table storage
21T Target temperature table
22 Speed table storage
20 22T Speed table
23 Standard-amount-of-water pattern storage
23T Standard-amount-of-water pattern table
24 Sheet-temperature estimation model storage
30 Dynamic controller
25 31 Target-temperature correction amount calculator
32 Feedforward controller
33 Temperature-for-control-command calculator
34 Feedback controller
35 Amount-of-cooling-water commander
30 40 Host computer
50 Controlled object
51 Hot-rolling finishing mill
53 Steel sheet
22
54 to 58 Between-stands cooling device
59 Mill roll
60 Finishing mill delivery temperature meter
100 Hot-rolling finishing mill delivery temperature controller
5 F1 to F6 Rolling stand
23

WE CLAIM:
1. A hot-rolling finishing mill delivery temperature controller used for controlling a
temperature of a steel sheet to be rolled in a hot-rolling finishing mill inclusive of: a
plurality of rolling stands for continuously rolling a steel sheet; and a plurality of
between-stands cooling devices for cooling the steel sheet, 5 each being arranged
between two rolling stands which are adjacent to each other, on a delivery side of the
hot-rolling finishing mill,
the controller comprising:
a sheet-temperature estimation model storage that stores sheet-temperature
10 estimation models for estimating the temperature of a steel sheet to be
rolled;
an amount-of-cooling-water presetter that estimates the temperature of the
steel sheet on the delivery side of the hot-rolling finishing mill, before
rolling the steel sheet, based on a preset rolling speed of the steel sheet,
15 amount of cooling water to be injected from the plurality of betweenstands
cooling devices, the temperature of the steel sheet on an entry
side of the hot-rolling finishing mill, and the sheet-temperature estimation
model, and then presets the amount of cooling water on the basis of an
estimated result so that the temperature of the steel sheet on the delivery
20 side coincides with a target temperature predetermined in advance;
a target-temperature correction amount calculator that obtains a variation in
the rolling speed to be detected by the rolling stands during the rolling of
the steel sheet from the preset rolling speed, and calculates a correction
amount for the target temperature on the delivery side of the steel sheet
25 for reducing influence from the variation in the rolling speed on the
material property values of the steel sheet; and
an amount-of-cooling-water commander that calculates a variation in the
amount of cooling water according to the correction amount for the target
temperature of the steel sheet on the delivery side, and outputs the
30 amount of cooling water, which has been preset in the amount-ofcooling-
water presetter and then corrected with the variation in the
amount of cooling water calculated, to the between-stands cooling device.
24
2. The hot-rolling finishing mill delivery temperature controller according to claim 1,
further comprising:
a material-property predictor that calculates at least one of an austenite
grain size and a dislocation density as material properties of the steel
sheet on the delivery side of the 5 hot-rolling finishing mill, on the basis
of information obtained from a host computer on the steel sheet,
inclusive of chemical composition, heating history, and rolling history,
as well as the temperature of the steel sheet on the delivery side,
which has been estimated in the amount-of-cooling-water presetter,
10 and the rolling speed; and
an influence-coefficient calculator that calculates influence of a variation
in the rolling speed to the material property values as a first influence
coefficient, on the basis of differences in the material property values
which the material-property predictor has calculated by varying the
15 rolling speed of the steel sheet, and calculates influence of a
variation in the temperature of the steel sheet on the delivery side to
the material property values as a second influence coefficient, on the
basis of differences in the material property values which the material
property predictor has calculated by varying the temperature of the
20 steel sheet on the delivery side,
wherein the target-temperature correction amount calculator calculates a
correction amount for the target temperature of the steel sheet on the delivery side,
on the basis of the variation in the rolling speed and at least one of the first and
second influence coefficients.
25 3. The hot-rolling finishing mill delivery temperature controller according to claim 1,
further comprising:
a feedforward controller that calculates a variation in the amount of
cooling water for reducing the correction amount for the target
temperature of the steel sheet on the delivery side, which has been
30 calculated by the target-temperature correction amount calculator,
wherein the variation in the amount of cooling water calculated by the feedforward
controller is used as the variation in the amount of cooling water according to the
25
correction amount for the target temperature of the steel sheet on the delivery side
calculated by the amount-of-cooling-water commander.
4. The hot-rolling finishing mill delivery temperature controller according to claim 1,
further comprising:
a temperature-for-control-command 5 calculator that calculates a target
temperature of the steel sheet on the delivery side to be used for actual
control, on the basis of the correction amount for the target temperature
of the steel sheet on the delivery side calculated by the targettemperature
correction amount calculator and the target temperature of
10 the steel sheet on the delivery side used by the amount-of-cooling-water
presetter; and
a feedback controller that calculates a variation in the amount of cooling
water to reduce a difference between the target temperature of the steel
sheet on the delivery side calculated by the temperature-for-control15
command calculator and a temperature of the steel sheet measured on
the delivery side of the hot-rolling finishing mill,
wherein the variation in the amount of cooling water calculated by the feedback
controller is used as the variation in the amount of cooling water according to the
correction amount for the target temperature of the steel sheet on the delivery side
20 calculated by the amount-of-cooling-water commander.
5. The hot-rolling finishing mill delivery temperature controller according to claim 1,
further comprising:
a feedforward controller that calculates a first variation in the amount of
cooling water for reducing the correction amount for the target
25 temperature of the steel sheet on the delivery side, which has been
calculated by the target-temperature correction amount calculator;
a temperature-for-control-command calculator that calculates a target
temperature of the steel sheet on the delivery side to be used for actual
control, on the basis of the correction amount for the target temperature
30 of the steel sheet on the delivery side calculated by the targettemperature
correction amount calculator and the target temperature of
the steel sheet on the delivery side used by the amount-of-cooling-water
presetter; and
26
a feedback controller that calculates a second variation in the amount of
cooling water to reduce a difference between the target temperature of
the steel sheet on the delivery side calculated by the temperature-forcontrol-
command calculator and a temperature of the steel sheet
measured on the delivery side of 5 the hot-rolling finishing mill,
wherein an amount obtained by adding the first and second variations, which are
respectively given weight, is used as the variation in the amount of cooling water
according to the correction amount for the target temperature of the steel sheet on
the delivery side calculated by the amount-of-cooling-water commander.
10 6. A control method of hot-rolling finishing mill delivery temperature, for use in a
device which controls a temperature of a steel sheet to be rolled in a hot-rolling
finishing mill inclusive of: a plurality of rolling stands for continuously rolling a steel
sheet; and a plurality of between-stands cooling devices for cooling the steel sheet,
each being arranged between two rolling stands which are adjacent to each other, on
15 a delivery side of the hot-rolling finishing mill, and stores sheet-temperature
estimation models for estimating a temperature of a steel sheet to be rolled,
the control method comprising:
estimating, as an amount-of-cooling-water presetting process, the
temperature of the steel sheet on the delivery side of the hot-rolling
20 finishing mill, before rolling the steel sheet, based on a preset rolling
speed of the steel sheet, amount of cooling water to be injected from the
plurality of between-stands cooling devices, the temperature of the steel
sheet on an entry side of the hot-rolling finishing mill, and the sheettemperature
estimation model, to preset the amount of cooling water on
25 the basis of the estimated results so that the temperature of the steel
sheet on the delivery side coincides with a target temperature
predetermined in advance;
obtaining, as a target-temperature correction amount calculation process, a
variation in the rolling speed to be detected by the rolling stands during
30 the rolling of the steel sheet from the preset rolling speed, to calculate a
correction amount for the target temperature on the delivery side of the
steel sheet for reducing influence from the variation in the rolling speed
on the material property values of the steel sheet; and
27
calculating, as an amount-of- cooling-water command process, a variation in
the amount of cooling water according to the correction amount for the
target temperature of the steel sheet on the delivery side, to output the
amount of cooling water, which has been preset in the amount-ofcooling-
water presetting process and then corrected 5 with the variation in
the amount of cooling water calculated, to the between-stands cooling
device.
7. The control method of hot-rolling finishing mill delivery temperature according to
claim 6, further comprising:
10 calculating, as a material-property prediction process, at least one of an
austenite grain size and a dislocation density as material properties
of the steel sheet on the delivery side of the hot-rolling finishing mill,
on the basis of information obtained from a host computer on the
steel sheet, inclusive of chemical composition, heating history, and
15 rolling history, as well as the temperature of the steel sheet on the
delivery side, which has been estimated in the amount-of-coolingwater
presetting process, and the rolling speed; and
calculating, as an influence-coefficient calculation process, influence of a
variation in the rolling speed to the material property values as a first
20 influence coefficient, on the basis of differences in the material
property values which has been calculated in the material-property
prediction process by varying the rolling speed of the steel sheet, and
calculating influence of a variation in the temperature of the steel
sheet on the delivery side to the material property values as a
25 second influence coefficient, on the basis of differences in the
material property values which has been calculated in the material
property prediction process by varying the temperature of the steel
sheet on the delivery side,
wherein in the target-temperature correction amount calculation process, a
30 correction amount for the target temperature of the steel sheet on the delivery side is
calculated on the basis of the variation in the rolling speed and at least one of the first
and second influence coefficients.
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8. The control method of hot-rolling finishing mill delivery temperature according to
claim 6, further comprising:
calculating, as a feedforward control process, a variation in the amount of
cooling water for reducing the correction amount for the target
temperature of the steel sheet on the 5 delivery side, which has been
calculated in the target-temperature correction amount calculation
process,
wherein the variation in the amount of cooling water calculated in the feedforward
control process is used as the variation in the amount of cooling water according to
10 the correction amount for the target temperature of the steel sheet on the delivery
side calculated in the amount-of-cooling-water command process.
9. The control method of hot-rolling finishing mill delivery temperature according to
claim 6, further comprising
further comprising:
15 calculating, as a temperature-for-control-command calculation process, a
target temperature of the steel sheet on the delivery side to be used for
actual control, on the basis of the correction amount for the target
temperature of the steel sheet on the delivery side calculated in the
target-temperature correction amount calculation process and the target
20 temperature of the steel sheet on the delivery side used in the amount-ofcooling-
water presetting process; and
calculating, as a feedback control process, a variation in the amount of
cooling water to reduce a difference between the target temperature of
the steel sheet on the delivery side calculated in the temperature-for25
control-command calculation process and a temperature of the steel
sheet measured on the delivery side of the hot-rolling finishing mill,
wherein the variation in the amount of cooling water calculated in the feedback
control process is used as the variation in the amount of cooling water according to
the correction amount for the target temperature of the steel sheet on the delivery
30 side calculated in the amount-of-cooling-water command process.
10. The control method of hot-rolling finishing mill delivery temperature according
to claim 6, further comprising:
29
calculating, as a feedforward control process, a first variation in the amount
of cooling water for reducing the correction amount for the target
temperature of the steel sheet on the delivery side, which has been
calculated in the target-temperature correction amount calculation
5 process;
calculating, as a temperature-for-control-command calculation process, a
target temperature of the steel sheet on the delivery side to be used for
actual control, on the basis of the correction amount for the target
temperature of the steel sheet on the delivery side calculated in the
10 target-temperature correction amount calculation process and the target
temperature of the steel sheet on the delivery side used in the amount-ofcooling-
water presetting process; and
calculating, as a feedback control process, a second variation in the amount
of cooling water to reduce a difference between the target temperature of
15 the steel sheet on the delivery side calculated in the temperature-forcontrol-
command calculation process and a temperature of the steel
sheet measured on the delivery side of the hot-rolling finishing mill,
wherein an amount obtained by adding the first and second variations, which are
respectively given weight, is used as the variation in the amount of cooling water
20 according to the correction amount for the target temperature of the steel sheet on
the delivery side calculated in the amount-of-cooling-water command process.