1. A coiling temperature control apparatus (100) which cools a strip (151), rolled by a hot rolling mill (158), by a cooling unit (153) disposed on a delivery side of the mill to control a coiling temperature of the strip before the strip is coiled by a down coiler (154) as well as an intermediate temperature of the strip when the strip passes a beforehand determined intermediate position of the cooling unit to predetermined target temperatures, comprising: a strip temperature prediction model (114) which predicts the intermediate temperature of the strip based on information of a first-half cooling header pattern as a combination of open/close of cooling headers disposed in a cooling unit between the mill and the intermediate position and which predicts the coiling temperature of the strip based on information of a second-half cooling header pattern as a combination of open/close of cooling headers disposed in a cooling unit between the intermediate position and the down coiler; a preset control unit (110) which predicts, before cooling control, the intermediate temperature and the coiling temperature using the strip temperature prediction model to calculate, using results of the prediction, the first-half cooling header pattern to realize a target intermediate temperature and the second-half cooling header pattern to realize a target coiling temperature; a first-half cooling dynamic control unit (121) which observes a state of the strip during the cooling control to calculate and to output a change quantity of the first-half cooling header pattern to adjust an observed intermediate temperature to the target intermediate temperature; and a second-half cooling dynamic control unit (122) which observes a state of the strip during the cooling control to calculate and to output a change quantity of the second-half cooling header pattern to adjust an observed coiling temperature to the target coiling temperature.

2. A coiling temperature control apparatus according to claim 1, wherein the first-half cooling dynamic control unit comprises: an intermediate temperature difference correction unit (123) which calculates a change quantity of the first-half cooling header pattern to compensate a difference between the target intermediate temperature and an intermediate temperature of the strip measured during the cooling control; a mill delivery temperature difference compensation unit (124) which calculates a change quantity of the first-half cooling header pattern to compensate a difference between a mill delivery temperature of the strip assumed in the preset control and a mill delivery temperature of the strip measured during the cooling control; a first-half cooling speed difference compensation unit (125) which calculates a change quantity of the first-half cooling header pattern to compensate a difference between a strip speed assumed in the preset control and a strip speed measured during the cooling control; and a first-half cooling operation quantity mixing unit (126) which mixes with each other outputs from the intermediate temperature difference correction unit, the mill delivery temperature difference compensation unit, and the first-half cooling speed difference compensation unit for each position of the strip in a longitudinal direction thereof to calculate a change quantity of the first-half cooling header pattern.

3. A coiling temperature control apparatus according to claim 1, wherein the second-half cooling dynamic control unit comprises: a coiling temperature difference correction unit (127) which calculates a change quantity of the second-half cooling header pattern to compensate a difference between the target coiling temperature and a coiling temperature of the strip measured during the cooling control; an intermediate temperature difference correction unit (127) which calculates a change quantity of the second-half cooling header pattern to compensate a difference between the target intermediate temperature and an intermediate temperature of the strip measured during the cooling control; a second-half cooling speed difference compensation unit (129) which calculates a change quantity of the second-half cooling header pattern to compensate a difference between a strip speed assumed in the preset control and a strip speed during the cooling control; and a second-half cooling operation quantity mixing unit (130) which mixes with each other outputs from the coiling temperature difference correction unit, the intermediate temperature difference correction unit, and the second-half cooling speed difference compensation unit for each position of the strip in a longitudinal direction thereof to calculate a change quantity of the second-half cooling header pattern.

4. A coiling temperature control apparatus according to claim 1, wherein the preset control unit comprises: a first-half cooling header priority level table (401) storing therein a priority relationship of an opening sequence of cooling headers disposed between the hot rolling mill and the intermediate position; a second-half cooling priority level table (402) storing therein a priority relationship of an opening sequence of cooling headers disposed between the intermediate position and the down coiler; a first-half cooling control code calculation unit (116) which establishes a correspondence between the first-half cooling header pattern (FIG. 5) and control codes(FIG. 5) created using information of the first-half cooling header priority level table to predict an intermediate temperature using the strip temperature prediction model and which calculates, using results of the prediction, control codes to realize the target intermediate temperature; and a second-half cooling control code calculation unit (117) which establishes a correspondence between the second-half cooling header pattern and control codes created using information of the second-half cooling header priority level table to predict a coiling temperature using the strip temperature prediction model and which calculates, using results of the prediction, control codes to realize the target coiling temperature.

5. A coiling temperature control apparatus according to claim 4, wherein the control codes are assigned with a maximum value in a state in which the headers are opened and with a minimum value in a state in which the headers are closed, and the control codes have a correspondence such that with an increase in the control codes, the intermediate or coiling temperature uniformly goes down (FIG. 5).

6. A coiling temperature control apparatus according to claim 4, wherein the control codes are assigned with a maximum value in a state in which the headers are opened and with a minimum value in a state in which the headers are closed, and the control codes have a correspondence such that with an increase in the control codes, the intermediate or coiling temperature uniformly goes up (FIG. 5) .

7. A coiling temperature control apparatus according to claim 4, wherein the first-half cooling dynamic control unit comprises: an intermediate temperature difference correction unit (123) which calculates, as a control code modification quantity, a change quantity of the first-half cooling header pattern to compensate a difference between the target intermediate temperature and a temperature at the intermediate position of the strip measured during the cooling control; a mill delivery temperature difference compensation unit (124) which calculates, as a control code modification quantity, a change quantity of the first-half cooling header pattern to compensate a difference between a mill delivery temperature of the strip assumed in the preset control and a mill delivery temperature of the strip measured during the cooling control; a first-half cooling speed difference compensation unit (125) which calculates, as a control code modification quantity, a change quantity of the first-half cooling header pattern to compensate a difference between a strip speed assumed in the preset control and a strip speed during the cooling control; and a first-half cooling operation quantity mixing unit (126) which mixes with each other outputs from the intermediate temperature difference correction unit, the mill delivery temperature difference compensation unit, and the first-half cooling speed difference compensation unit for each position of the strip in a longitudinal direction thereof to calculate a control code modification quantity, the coiling temperature control apparatus comprising a first-half cooling header pattern conversion unit (141) which recognizes a position of the strip in a longitudinal direction thereof just beneath each of the headers and which converts a result obtained through an operation into a first-half cooling header pattern to output the pattern to the cooling unit, the operation being conducted to correct the first-half cooling control codes, which are calculated by and are outputted from the first-half cooling control code calculation unit by establishing a correspondence to each position of the strip in a longitudinal direction thereof, by use of the control codes outputted from the first-half cooling dynamic control unit. 8. A coiling temperature control apparatus according to claim 4, wherein the second-half cooling dynamic control unit comprises: a coiling temperature difference correction unit (127) which calculates, as a control code modification quantity, a change quantity of the second-half cooling header pattern to compensate a difference between the a target coiling temperature and a coiling temperature of the strip measured during the cooling control; an intermediate temperature difference compensation unit (128) which calculates, as a control code modification quantity, a change quantity of the second-half cooling header pattern to compensate a difference between the target intermediate temperature and a temperature at the intermediate position of the strip measured during the cooling control; a second-half cooling speed difference compensation unit (129) which calculates, as a control code modification quantity, a change quantity of the second-half cooling header pattern to compensate a difference between the strip speed assumed in the preset control and the strip speed measured during the cooling control; and a second-half cooling operation quantity mixing unit (130) which mixes with each other outputs from coiling temperature difference correction unit, the intermediate temperature difference correction unit, and the second-half cooling speed difference compensation unit for each position of the strip in a longitudinal direction thereof to calculate a control code modification quantity, the coiling temperature control apparatus comprising a second-half cooling header pattern conversion unit (142) which recognizes a position of the strip in a longitudinal direction thereof just beneath each of the headers and which converts a result obtained through an operation into a second-half cooling header pattern to output the pattern to the cooling unit, the operation being conducted to correct the second-half cooling control codes, which are calculated by and are outputted from the second-half cooling control code calculation unit by establishing a correspondence to each position of the strip in a longitudinal direction thereof, by use of the control codes outputted from the second-half cooling dynamic control unit.

9. A coiling temperature control apparatus according to claim 4, wherein: the first-half cooling dynamic control unit comprises a first influence coefficient table (1001) storing therein an influence of a change in the control codes upon the intermediate temperature, a second influence coefficient table (1002) storing therein an influence of a change in the mill delivery temperature upon the intermediate temperature, and a third influence coefficient table (1003) storing therein an influence of a change in the strip speed upon the intermediate temperature; the intermediate temperature difference compensation unit calculates the modification quantity of the first-half cooling control codes based on the difference between the target intermediate temperature and the intermediate temperature of the strip measured during the cooling control and a coefficient obtained from the first influence coefficient table; the before-cooling temperature difference compensation unit calculates a modification quantity of the first-half cooling control code based on the difference between the mill delivery temperature of the strip assumed in the preset control and the mill delivery temperature of the strip measured during the cooling control, a coefficient obtained from the first influence coefficient table, and a coefficient obtained from the second influence coefficient table; and the first-half cooling speed difference compensation unit calculates a modification quantity of the first-half cooling control codes based on the difference between the strip speed assumed in the preset control and the strip speed during the cooling control, a coefficient obtained from the first influence coefficient table, and a coefficient obtained from the third influence coefficient table. 10. A coiling temperature control apparatus according to claim 4, wherein: the second-half cooling dynamic control unit comprises a fourth influence coefficient table (1801) storing therein an influence of a change in the control codes upon the coiling temperature, a fifth influence coefficient table (1802) storing therein an influence of a change in the intermediate temperature with respect to the target intermediate temperature upon the coiling temperature, and a sixth influence coefficient table (1803) storing therein an influence of a change in the strip speed upon the coiling temperature; the coiling temperature difference correction unit calculates a modification quantity of the control codes based on the difference between the target coiling temperature and the coiling temperature of the strip detected during the cooling control, and a coefficient obtained from the fourth influence coefficient table; the intermediate temperature difference compensation unit calculates the modification quantity of the control codes based on the difference between the before-cooling temperature assumed in the preset control and the before-cooling temperature of the strip detected during the cooling control, a coefficient obtained from the fourth influence coefficient table, and a coefficient obtained from the fifth influence coefficient table; and the second-half cooling speed difference compensation unit calculates a modification quantity of the control codes based on the difference between the strip speed assumed in the preset control and the strip speed during the cooling control, a coefficient obtained from the fourth influence coefficient table, and a coefficient obtained from the fifth influence coefficient table.

11. A coiling temperature control apparatus according to claim 4, comprising: an intermediate temperature keeping time calculation unit (2701) which identifies an air-cooling range near the intermediate position based on the first-half cooling header pattern and the second-half cooling header pattern outputted from the preset control unit to calculate a period of time in which the strip is kept at the intermediate temperature, based on the identified air-cooling range and the strip speed; and a speed pattern change unit (2702) which executes processing to lower a maximum speed of the strip if the calculated intermediate temperature keeping time does not satisfy a predetermined required keeping time.

12. A coiling temperature control apparatus according to claim 4, comprising a stabilized control unit (3001) which obtains the change quantity of the first-half cooling header pattern calculated by the first cooling dynamic control unit and which stabilizes the output from the second-half cooling dynamic control unit by setting a dead zone to the change quantity of the intermediate temperature during a period of time from timing when the correction quantity of the first-half cooling control codes is changed to an end point of a period of time in which the first-half cooling dynamic control unit cannot suppress the intermediate temperature change due to a response delay of the cooling header.

13. A coiling temperature control apparatus according to claim 4, comprising a stabilized control unit (3001) which obtains the correction quantity of the first-half cooling control codes calculated by the first cooling dynamic control unit and which stabilizes the output from the second-half cooling dynamic control unit by setting a dead zone to the change quantity of the intermediate temperature during a period of time from timing when the correction quantity of the first-half cooling control codes is changed to an end point of a period of time in which the first-half cooling dynamic control unit cannot control the intermediate temperature change due to a response delay of the cooling header.

14. A coiling temperature control method which cools a strip rolled by a hot rolling mill by a cooling unit disposed on a delivery side of the mill to control a coiling temperature of the strip before the strip is coiled by a down coiler as well as a strip temperature of the strip when the strip passes a beforehand determined intermediate position of the cooling unit to predetermined target temperatures, comprising: predicting an intermediate temperature of the strip based on information to determine a first-half cooling header pattern as a combination of open/close of cooling headers disposed in a cooling unit between the mill and the intermediate position, predicting the coiling temperature of the strip based on information of a second-half cooling header pattern as a combination of open/close of cooling headers disposed in a cooling unit between the intermediate position and the down coiler, and determining, using results of the prediction, the first-half cooling header pattern to realize the target intermediate temperature and the second-half cooling header pattern to realize the target coiling temperature; observing a state of the strip during the cooling control; correcting the first-half cooling header pattern to remove a difference between the target intermediate temperature and an intermediate temperature of the strip detected during the cooling control, correcting the first-half cooling header pattern to compensate a difference between the strip temperature on the mill delivery side assumed in the preset control and the strip temperature measured on the strip, and correcting the first-half cooling header pattern to compensate an influence, upon the intermediate temperature, of a difference between the strip speed assumed in the preset control and an actual strip speed; correcting the second-half cooling header pattern to remove a difference between the target coiling temperature and a coiling temperature of the strip detected during the cooling control, correcting the second-half cooling header pattern to compensate an influence, upon the coiling temperature, of a difference between the target value of the intermediate temperature of the strip and an intermediate temperature of the strip measured on the strip, and correcting the second-half cooling header pattern to compensate an influence, upon the coiling temperature, of a difference between the strip speed assumed in the preset control and an actual strip speed. 15. A coiling temperature control method according to claim 14, comprising: assigning respectively priority levels of opening sequence to first-half cooling headers disposed in a cooling unit between a hot rolling mill and the intermediate position and priority levels of opening sequence to second-half cooling headers disposed in a cooling unit between the intermediate position and the down coiler; establishing a correspondence between a first-half cooling header pattern as a combination of open/close of the first-half cooling headers and first-half control control codes created using information of the priority levels assigned to the first-half cooling headers, predicting an intermediate temperature of the strip using a strip temperature prediction model based on the first-half control control codes and information regarding the speed of the strip, and determining, using results of the prediction, the first-half cooling control codes to realize the target intermediate temperature; establishing a correspondence between a second-half cooling header pattern as a combination of open/close of the second-half cooling headers and second-half control control codes created using information of the priority levels assigned to the second-half cooling headers, predicting a coiling temperature of the strip using a strip temperature prediction model based on the second-half control control codes and information regarding the speed of the strip, and determining, using results of the prediction, the second-half cooling control codes to realize the target coiling temperature; and during the cooling control, calculating, as a correction quantity of the first-half cooling control codes, open/close of headers to remove the difference between the target intermediate temperature and the intermediate temperature detected on the strip, calculating, as a correction quantity of the first-half cooling control codes, open/close of headers to compensate the difference between the strip temperature on the mill delivery side assumed in the preset control and the strip temperature measured on the strip, and calculating, as a correction quantity of the first-half cooling control codes, open/close of headers to compensate an influence, upon the intermediate temperature, of a difference between the strip speed assumed in the preset control and an actual strip speed; calculating, as a correction quantity of the second-half cooling control codes, open/close of headers to remove a difference between the target coiling temperature and a coiling temperature of the strip detected during the cooling control, calculating, as a correction quantity of the second-half cooling control codes, open/close of headers to compensate an influence, upon the coiling temperature, of a difference between the target value of the intermediate temperature of the strip and an intermediate temperature of the strip measured on the strip, and calculating, as a correction quantity of the second-half cooling control codes, open/close of headers to compensate an influence, upon the coiling temperature, of a difference between the strip speed assumed in the preset control and an actual strip speed; and converting, into a first-half cooling header pattern, a value obtained by correcting, based on a total of the correction quantities of the first-half cooling control codes thus calculated, the first-half cooling control codes determined before the cooling control of the strip and outputting the pattern to the cooling unit, and converting, into a second-half cooling header pattern, a value obtained by correcting, based on a total of the correction quantities of the second-half cooling control codes thus calculated, the second-half cooling control codes and outputting the pattern to the cooling unit.

16. A coiling temperature control method which cools a strip rolled by a hot rolling mill by a cooling unit disposed on a delivery side of the mill to control a coiling temperature of the strip before the strip is coiled by a down coiler as well as a strip temperature of the strip when the strip passes a beforehand determined intermediate position of the cooling unit to predetermined target temperatures, comprising: before the cooling control of the strip, predicting an intermediate temperature of the strip based on information to determine a first-half cooling header pattern as a combination of open/close of cooling headers disposed in a cooling unit between the mill and the intermediate position, predicting the coiling temperature of the strip based on information of a second-half cooling header pattern as a combination of open/close of cooling headers disposed in a cooling unit between the intermediate position and the down coiler, and calculating, using results of the prediction, the first-half cooling header pattern to realize the target intermediate temperature and the second-half cooling header pattern to realize the target coiling temperature; and during the cooling control, measuring a temperature of the strip at the intermediate position to calculate a difference between the temperature and the target intermediate temperature, correcting the first-half cooling header pattern to remove the difference, and correcting the second-half cooling header pattern to remove an influence of the difference upon the coiling temperature.

17. A coiling temperature control method according to claim 14, comprising: determining header patterns to realize the target intermediate temperature and the target coiling temperature, identifying an air-cooling range near the intermediate position based on the header patterns thus determined, making a check to determine whether or not an intermediate temperature keeping time satisfies a required keeping time; lowering, if the intermediate temperature keeping time does not satisfy the required keeping time, a maximum speed of the strip and determining again header patterns to realize the target intermediate temperature and the target coiling temperature; making a check to determine, based on the header patterns again determined, whether or not the intermediate temperature keeping time satisfies the required keeping time; lowering, if the intermediate temperature keeping time does not satisfy the required keeping time, the maximum speed of the strip and determining again header patterns to realize the target intermediate temperature and the target coiling temperature; and repeatedly conducting this operation until the intermediate temperature keeping time satisfies the required keeping time.

18. A coiling temperature control method which cools a strip rolled by a hot rolling mill by a cooling unit disposed on a delivery side of the mill to control a coiling temperature of the strip before the strip is coiled by a down coiler as well as a strip temperature of the strip when the strip passes a beforehand determined intermediate position of the cooling unit to predetermined target temperatures, comprising: before the control of the strip, predicting an intermediate temperature of the strip at the intermediate position using a strip temperature prediction model based on a header pattern as a combination of open/close of cooling headers, information regarding a speed of the strip, and a prediction value of the strip temperature on the mill delivery side; and determining, based on results of the prediction, a first-half cooling header pattern to realize the target intermediate temperature; and adjusting the prediction value of the intermediate temperature to the target intermediate temperature, predicting a coiling temperature of the strip using a strip temperature prediction model based on the header pattern, the information regarding the speed of the strip, and the prediction value of the intermediate temperature; and determining, based on results of the prediction, a second-half cooling header pattern to realize a target coiling temperature. 19. A coiling temperature control method according to claim 18, comprising recognizing, by obtaining the first-half cooling header pattern, that the first-half cooling header pattern has been corrected; setting a dead zone to a change guantity of the measured intermediate temperature during a period from the correction timing to an end point of a period of time in which the intermediate temperature change cannot be suppressed due to a response delay of the cooling header; and releasing the dead zone after the intermediate temperature change is suppressed due to the correction of the first-half cooling header pattern.

BACKGROUND OF THE INVENTION
The present invention relates to a coiling temperature apparatus and a control method thereof in a hot rolling line, and in particular, to a coiling temperature control apparatus and a control method thereof suitable for temperature control of Dual Phase (DP) steel for which it is required, for high quality of a strip thereof, to adjust not only a coiling temperature, but also an intermediate temperature to a target temperature and to keep the temperature for a fixed period of time.
To control the cooling temperature, there exists a method of controlling not only the coiling temperature, namely, the temperature is additionally controlled in consideration of the intermediate temperature, a cooling pattern, and a cooling speed. For example, JP-A-6-24 6320 describes a method in which a cooling pattern is controlled by conducting cooling control such that a target temperature of a strip to pass each of positions in a cooling unit is determined to adjust prediction of the strip temperature to the target temperature. Also, JP-A-2006-193759 describes, as a scheme to make the dynamic specific heat accurate based on metallurgical knowledge, a method to accurately control a temperature history of a strip by
improving accuracy of prediction of the strip temperature. Furthermore, JP-A-6-238312 describes a method in which a cooling zone is subdivided into a first-half zone and a second-half zone such that the temperature history is controlled up to the completion of Y→α phase transformation in the first-half zone to determine an open/close pattern of a cooling unit to adjust a predicted coiling temperature to a target coiling temperature in the second-half zone.
SUMMARY OF THE INVENTION
The above conventional techniques are capable of conducting the control in consideration of the cooling temperature pattern and the intermediate temperature of the strip. However, from a point of view of improvement of temperature control accuracy, there exist problems as follows. In JP-A-6-246320, accuracy of the strip temperature prediction directly affects accuracy of the temperature control, but description has not been given of a method to increase the accuracy of strip temperature prediction. Hence, there exists a fear of reduction in the control accuracy due to insufficient accuracy of the strip temperature prediction. On the other hand, JP-A-2006-193759 describes a method of increasing the strip temperature prediction accuracy by using a more accurate model for the strip temperature prediction. However, description has not been given of a method of
coping with reduction in the control accuracy due to model errors remaining as a result of the increase in the prediction accuracy. JP-A-6-238312 describes a method of conducting the control by assuming a strip temperature pattern and an intermediate temperature keeping time in the first-half cooling. However, description has not been given of a method of measuring the intermediate temperature to improve the control accuracy using results of the measurement, and there hence exists a fear that the control cannot be actually conducted according to the assumption.
Additionally, in none of the conventional techniques, description has been given of dispersion of temperature of the strip entering the cooling unit, a speed change not assumed for the cooling control, a method of compensating influence of the difference of the intermediate temperature from the target value upon the coiling temperature, and the like. There hence exists a fear that the intermediate temperature and the coiling temperature as targets of the techniques cannot be realized and the required intermediate temperature keeping time cannot be observed.
It is therefore an object of the present invention to provide a coiling temperature control apparatus capable of realizing the intermediate temperature and the coiling temperature as targets and observing the required intermediate temperature keeping
time in consideration of the problems of the conventional techniques.
To solve the problems according to the present invention, there is provided a coiling temperature control apparatus including a first-half cooling dynamic control unit which includes, on assumption that an intermediate temperature pyrometer is installed to measure an intermediate temperature, a preset control unit to calculate, for a first-half cooling unit existing in an upstream position in a strip proceeding direction of the intermediate temperature pyrometer and a second-half cooling unit existing in a downstream position of the intermediate temperature pyrometer, an open/close pattern of a header of each cooling unit for each portion in a longitudinal direction of a strip before a cooling process; an intermediate temperature difference correction unit to solve the difference between a intermediate temperature measured during the cooling and a target intermediate temperature, a mill delivery temperature difference compensation unit to reduce influence, upon the intermediate temperature, of the difference between a mill delivery temperature assumed at preset calculation and an actually detected mill delivery temperature, and a first-half cooling speed difference compensation unit to reduce influence, upon the intermediate temperature, of the difference between a strip temperature assumed at preset calculation and
an actual strip speed. Moreover, the coiling temperature control apparatus includes a second-half cooling speed difference compensation unit which includes a coiling temperature difference correction unit to solve the difference between a coiling temperature measured during the cooling and a target coiling temperature, an intermediate temperature difference compensation unit to reduce influence, upon the coiling temperature, of the difference between an intermediate temperature target value and a measured value of the intermediate pyrometer, and a strip cooling speed difference compensation unit to reduce influence, upon the coiling temperature, of the difference between a strip temperature assumed at preset calculation and an actual strip speed.
The header open/close pattern is represented using control codes. A desired header open/close pattern is obtained by use of a simple linear optimization method, which hence remarkably reduces the amount of operation required for preset control.
The apparatus additionally includes an intermediate temperature keeping time calculation unit to calculate a period of time to keep the strip at the intermediate temperature based on the header pattern obtained as a result of the preset control and the strip speed, and a speed pattern change unit to execute speed pattern change processing if the intermediate temperature keeping time is insufficient.
Furthermore, the apparatus includes a stabilized control unit which suppresses influence of the dynamic control for the first-half cooling unit to adjust the intermediate temperature to the target value, upon an unstable operation and the coiling temperature control accuracy in the second-half cooling unit.
According to the present invention, there is provided a coiling temperature control method which cools a strip rolled by a hot rolling mill by a cooling unit disposed on a delivery side of the mill to control a coiling temperature of the strip before the strip is coiled by a down coiler as well as a strip temperature of the strip when the strip passes a beforehand determined intermediate position of the cooling unit to adjust these temperatures to predetermined target temperatures. The method includes predicting, prior to cooling control for the strip, an intermediate temperature at the intermediate point of the strip using a strip temperature prediction model based on a header pattern as a combination of open/close of cooling headers, information regarding a strip speed, and a prediction value of the strip temperature on the mill delivery side; determining a first-half cooling header pattern to realize the target intermediate temperature using results of the prediction; adjusting the prediction value of the intermediate temperature to the target intermediate temperature and then predicting
a strip coiling temperature by use of a strip temperature prediction model on the basis of the header pattern, the information regarding the strip speed, and the prediction value of the intermediate temperature; and determining a second-half cooling header pattern to realize the target coiling temperature using results of the prediction.
The apparatus acquires the first-half cooling header pattern to thereby recognize correction of the pattern, sets a dead zone of a quantity of change in the measured intermediate temperature during a period of time from correction timing to an end point of a period of time in which the intermediate temperature change cannot be suppressed due to a response delay of the cooling header, and releases the dead zone after the intermediate temperature change is suppressed through the correction of the first-half cooling header pattern.
According to the present invention, in a situation wherein the control of the strip coiling temperature and the intermediate temperature to adjust the temperatures to the target values is carried out during the coiling/cooling process in hot rolling, since there is disposed the first-half cooling dynamic control unit, even if a strip speed changes, dispersion of the mill delivery temperature takes place, or a mismatch between the intermediate temperature and the target temperature occurs during the cooling control,
influence thereof upon the intermediate temperature and be minimized. It is hence possible to control the intermediate temperature in the longitudinal direction of the strip with high accuracy.
Similarly, since the second-half cooling dynamic control unit is arranged, even if a strip speed changes, a mismatch takes place between the intermediate temperature and the target temperature, or a mismatch occurs between the coiling temperature and the target temperature during the cooling control, the influence thereof upon the intermediate temperature can be minimized. Therefore, it is hence possible to control the intermediate temperature in the longitudinal direction of the strip with high accuracy.
Since the intermediate temperature keeping time calculation unit is disposed, it is possible to predict the keeping time at the intermediate temperature on the basis of the header pattern and the strip speed obtained as a result of the preset control. In addition, since the speed pattern change unit executes processing to lower the maximum speed if the keeping time is insufficient, it is possible to perform the cooling control by securing the intermediate temperature keeping time.
As above, it is possible to improve quality of a strip conforming to a particular cooling specification such as a Dual Phase (DP) steel. While the first-half cooling dynamic control unit causes the
intermediate temperature to complicatedly change, the stabilized control unit can suppress unnecessary operation of the first-half cooling dynamic control unit in association therewith to thereby operate the second-half cooling unit in a stable state.
Other objects, features and advantages of the invention will become apparent from the following description of the embodiments of the invention taken in conjunction with the accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
Fig. 1 is a configuration diagram of a coiling temperature control system in a first embodiment of the present invention;
FIG. 2 is an explanatory diagram showing structure of a speed pattern table;
FIG. 3 is an explanatory diagram showing structure of a target temperature table;
FIG. 4 is an explanatory diagram showing structure of a cooling header priority level table;
FIG. 5 is an explanatory diagram showing an example of a correspondence between cooling header open/close patterns and control codes;
FIG. 6 is a flowchart showing first-half and second-half cooling control code calculation processing;
FIG. 7 is a flowchart showing processing of coiling temperature prediction calculation in the
first-half cooling control code calculation processing;
FIG. 8 is a flowchart showing processing of coiling temperature prediction calculation in the second-half cooling control code calculation processing.
FIGS. 9A and 9B are an explanatory diagram showing transitions of control codes during a control code calculation;
Fig. 10 is a configuration diagram of a first-half cooling dynamic control unit;
FIG. 11 is an explanatory diagram showing structure of a first influence coefficient table;
FIG. 12 is an explanatory diagram showing structure of a second influence coefficient table;
FIG. 13 is an explanatory diagram showing structure of a third influence coefficient table;
FIG. 14 is a flowchart showing processing of an application position identification unit in a mill delivery temperature difference compensation unit.
FIG. 15 is an explanatory diagram of division of sections of a strip in a longitudinal direction;
FIG. 16 is a flowchart showing processing of an application position identification unit in a first-half cooling speed change compensation unit;
FIG. 17 is an explanatory diagram of control code correction processing by the first-half cooling dynamic control unit;
Fig. 18 is a configuration diagram of a
second-half cooling dynamic control unit;
FIG. 19 is an explanatory diagram showing structure of a fourth influence coefficient table;
FIG. 20 is an explanatory diagram showing structure of a fifth influence coefficient table;
FIG. 21 is an explanatory diagram showing structure of a sixth influence coefficient table;
FIG. 22 is a flowchart showing processing of an application position identification unit in the intermediate temperature difference compensation unit;
FIG. 23 is a flowchart showing processing of an application position identification unit in a second-half cooling speed change compensation unit;
FIG. 24 is an explanatory diagram of control code correction processing by the second-half cooling dynamic control unit;
FIG. 25 is a flowchart showing processing of a first-half cooling header pattern change unit;
FIG. 26 is a flowchart showing processing of a second-half cooling header pattern change unit;
Fig. 27 is a configuration diagram of a coiling temperature control system in a second embodiment of the present invention;
FIG. 28 is a flowchart showing processing of an intermediate temperature keeping time calculation unit;
FIG. 29 is a flowchart showing processing of a speed pattern change unit;
Fig. 30 is a configuration diagram of a coiling temperature control system in a third embodiment of the present invention; and
FIG. 31 is a flowchart showing processing of a stabilized control unit.
DESCRIPTION OF THE EMBODIMENTS
A best mode for carrying out the invention is a coiling temperature control apparatus in which a strip 151 rolled by a hot rolling mill 152 is cooled by cooling units 170 and 171 disposed on a delivery side of the mill and which performs control to adjust a coiling temperature of the strip before the strip is coiled by a down coiler 154 to a predetermined target temperature as well as to adjust an intermediate temperature of the strip when the strip passes a beforehand determined intermediate position of the cooling unit to a predetermined target temperature.
There is disposed a strip temperature prediction model 114 for predicting an intermediate temperature of the strip based on information of a first-half cooling header pattern which is a combination of open/close of cooling headers 162 disposed in a cooling unit between the hot rolling mill and the intermediate position and for predicting a coiling temperature of the strip based on information of a second-half cooling header pattern which is a combination of open/close of cooling headers disposed
in a cooling unit between the intermediate position and the down coiler.
There is disposed a preset control unit 110 for predicting, before conducting cooling control, the intermediate temperature and the coiling temperature using the strip temperature prediction model 114 and calculating, by use of results of the prediction, a first-half cooling header pattern to realize the target intermediate temperature and a second-half cooling header pattern to realize the target coiling temperature.
Also, there are disposed a first-half cooling dynamic control unit 121 to observe a state of the strip during the cooling control to calculate and to output a quantity of change in the first-half cooling header pattern to adjust an observed intermediate temperature to the target intermediate temperature and a second-half cooling dynamic control unit 122 to observe a state of the strip during the cooling control to calculate and to output a change quantity of the second-half cooling header pattern to adjust an coiling temperature to the target coiling temperature.
The first-half cooling dynamic control unit 121 includes an intermediate temperature difference correction unit 123 to calculate a change quantity of the first-half cooling header pattern to compensate the difference between the target intermediate temperature and the intermediate temperature of the strip measured
during the cooling control, a mill delivery temperature difference compensation unit 124 to calculate a change quantity of the first-half cooling header pattern to compensate the difference between the mill delivery temperature of the strip assumed in the preset control and the mill delivery temperature thereof measured during the cooling control, a first-half cooling speed difference compensation unit 125 to calculate a change quantity of the first-half cooling header pattern to compensate the difference between the strip speed assumed in the preset control and the strip speed during the cooling control, and a first-half cooling operation quantity mixing unit to mix the outputs from the constituent components above for each position in the strip longitudinal direction to calculate a change quantity of the first-half cooling header pattern.
The second-half cooling dynamic control unit 122 includes a coiling temperature difference correction unit 127 to calculate a change quantity of the second-half cooling header pattern to compensate the difference between the target coiling temperature and the coiling temperature of the strip measured during the cooling control, an intermediate temperature difference compensation unit 128 to calculate a change quantity of the second-half cooling header pattern to compensate the difference between the target intermediate temperature and the intermediate temperature of the strip measured during the cooling
control, a second-half cooling speed difference compensation unit 129 to calculate a change quantity of the second-half cooling header pattern to compensate the strip speed assumed in the preset control and the strip speed during the cooling control, and a second-half cooling operation quantity mixing unit 130 to mix the outputs from the constituent components above for each position in the strip longitudinal direction to calculate a change quantity of the second-half cooling header pattern.
The preset control unit 110 includes a first-half cooling header priority level table 401 storing a priority relationship of opening sequence of cooling headers disposed between the hot strip mill and the intermediate position, a second-half cooling header priority level table 402 storing a priority relationship of opening sequence of cooling headers disposed between the intermediate position and the down coiler, and a first-half cooling control code calculation unit 116 which establishes a correspondence between the first-half cooling header pattern and control codes generated using information of the first-half cooling header priority level table 401 to predict the intermediate temperature by use of the strip temperature prediction model 114 and which then calculates and outputs, by using results of the prediction, control codes to realize the target intermediate temperature. Also, the preset control
unit 110 includes a second-half cooling control code calculation unit 117 which establishes a correspondence between the second-half cooling header pattern and control codes generated using information of the second-half cooling header priority level table 402 to predict the coiling temperature by use of the strip temperature prediction model 114 and which then calculates and outputs, by using results of the prediction, control codes to realize the target coiling temperature.
According to the embodiment, in the strip coiling control after the hot rolling, it is possible, even for a particular strip grade requiring that a strip thereof is kept for a fixed period of time at the intermediate temperature, that the intermediate temperature is kept for a sufficient period of time with high accuracy in a wide range of positions in the strip longitudinal direction, and a highly-accurate coiling temperature is obtained. Resultantly, it is possible to improve quality of composition of a high-class strip represented by the DP steel requiring the keeping of the intermediate temperature during the cooling, and a favorable strip contour is obtainable. Next, referring to drawings, description will be given in detail of a plurality of embodiments of the present invention. [First embodiment]
FIG. 1 shows a configuration diagram of a
coiling temperature control apparatus according to a first embodiment of the present invention. The apparatus 1 receives various signals from a control object 150 and outputs control signals to the control object 150. First, description will be given of structure of the control object 150.
In the embodiment, the control object 150 is coiling/cooling equipment for hot rolling in which a strip 151 having a temperature ranging from about 850°C to about 1000°C rolled by a mill 158 of a rolling mill 152 is cooled by a cooling unit 153 and is coiled by a down coiler 154. The cooling unit 153 includes upper cooling equipment 160 to water-cool the strip 151 from an upper side and lower cooling equipment 161 to water-cool the strip 151 from a lower side. The respective cooling units include respectively a plurality of banks 163 including a fixed number of cooling headers 162 to eject water therefrom. In the embodiment, description will be given of an example in which "open" or "close" is selected as an operation command for each cooling header 162.
A mill delivery side pyrometer 155 measures the temperature of a strip immediately after it is rolled by the rolling mill 152. An intermediate pyrometer 156 disposed near a central section of the cooling unit 153 measures the temperature of the strip passing the pyrometer setting position. A coiling pyrometer 157 measures the temperature immediately
before the strip is coiled by the down coiler 154. An object of the coiling temperature control of the embodiment is to adjust the temperatures measured by the intermediate pyrometer 156 and the coiling pyrometer 157 to target temperatures and to keep the strip temperature near the intermediate temperature for a fixed period of time. In the embodiment, as FIG. 1 shows, a cooling unit ranging from the delivery side of the rolling mill 152 to the intermediate pyrometer 156 is referred to as a first-half cooling unit 170 and a cooling unit ranging from the intermediate pyrometer 156 to the coiling pyrometer 157 is referred to as a second-half cooling unit 171. The target temperature may be fixed for each position in the strip longitudinal direction or a different value may be set according to each position.
Next, description will be given of structure of the coiling temperature control apparatus 100. Hereinbelow, a set of open/close patterns of the cooling headers 162 are collectively called a header pattern. The apparatus 100 includes a preset control unit 110 to calculate a control command corresponding to the open/close pattern of each cooling header 162 before the strip 151 is cooled by the coiling/cooling unit or section 153, a dynamic control unit 120 which acquires, when the strip 151 is being cooled by the cooling section 153, actual results of measured temperatures and the like from the mill delivery side
pyrometer 155, the intermediate pyrometer 156, and the coiling pyrometer 157 in a realtime fashion to change the control command, and a header pattern conversion unit 140 to convert the control command into an open/close pattern of each cooling header 162.
As in the disclosure of Japanese Patent Application 2005-311367 (JP-A-2007-118027) as an earlier application, description will be given of the present embodiment based on an example in which the control command is described by use of a control code uniquely corresponding to a header pattern. However, as a method of describing the head pattern, there may be considered other methods to represent the control command such as a method to represent the command employing a bit pattern.
The preset control unit 110 includes a speed pattern table 111, a target temperature table 112, and a cooling header priority level table 113. The unit 110 includes a control code calculation unit 115 which acquires information for each class corresponding to a strip to be next cooled and which conducts an arithmetic operation using the strip temperature prediction model 114 to calculate a header pattern to realize desired cooling of the strip 151. Furthermore, the control code calculation unit 115 includes a first-half cooling control code calculation unit 116 to calculate a control code for the first-half cooling unit 170 and a second-half cooling control code
calculation unit 117 to calculate a control code for the second-half cooling unit 171.
The dynamic control unit 120 includes a first-half cooling dynamic control unit 121 to calculate, during the cooling control, a quantity of modification of the header pattern to perform control for the first-half cooling unit 170 to adjust the intermediate temperature to the target value and a second-half cooling dynamic control unit 122 to calculate a header pattern modification quantity to control the second-half cooling unit 171 to adjust the coiling temperature to the target value.
The first-half cooling dynamic control unit 121 includes an intermediate temperature difference correction unit 123 to calculate, using a detected temperature from the intermediate pyrometer 156, a control code modification quantity to correct the difference between the detected temperature and the target intermediate temperature; a mill delivery temperature difference compensation unit 124 to calculate, using a detected temperature from the mill delivery side pyrometer 155, a control code modification quantity to compensate the difference between the detected temperature and the mill delivery temperature assumed in the preset control operation; and a first-half cooling speed difference compensation unit 125 which obtains a speed of the strip 151 using rotary speeds of the mill 158 and the down coiler 154
to calculate a control code modification quantity to compensate the difference between the obtained speed and the strip speed assumed in the preset control operation.
The first-half cooling dynamic control unit 121 includes a first-half cooling operation quantity mixing unit 126 which mixes, paying attention to each position of the strip longitudinal direction, the calculation results from the intermediate temperature difference correction unit 123, the mill delivery temperature difference compensation unit 124, and the first-half cooling speed difference compensation unit 125 to calculate an output from the first-half cooling dynamic control unit 121.
On the other hand, the second-half cooling dynamic control unit 122 includes a coiling temperature difference correction unit 127 to calculate, using a detected temperature from the coiling pyrometer 157, a control code modification quantity to correct the difference between the detected temperature and the target coiling temperature; an intermediate temperature difference compensation unit 128 to calculate a control code modification quantity to compensate the difference between the detected temperature from the intermediate pyrometer 156 and the target intermediate temperature, and a second-half cooling speed difference compensation unit 129 which obtains a speed of the strip 151 using rotary speeds of the mill 158 and the down coiler 154
to calculate a control code modification quantity to compensate the difference between the obtained speed and the strip speed assumed in the preset control operation. Moreover, the second-half cooling dynamic control unit 122 includes a second-half cooling operation quantity mixing unit 130 which mixes, paying attention to each position of the strip longitudinal direction, the calculation results from the coiling temperature difference correction unit 127, the intermediate temperature difference compensation unit 128, and the second-half cooling speed difference compensation unit 129 to calculate an output from the second-half cooling dynamic control unit 122.
The header pattern conversion unit 140 includes a first-half cooling header pattern conversion unit 142 which receives control codes from the second-half cooling dynamic control unit 122 during the cooling control to convert the control codes into a header pattern to control the first-half cooling unit 170 and a second-half cooling header pattern conversion unit 142 which receives control codes from the second-half cooling dynamic control unit 122 to convert the control codes into a header pattern to control the second-half cooling unit 171.
FIG. 2 shows a configuration of the speed pattern table 111. FIG. 2 shows an example of a speed pattern when the rolling mill 152 is a tandem mill. For a class or a combination of a type of strip (strip
grade), strip thickness, and strip width, there are accumulated a speed (initial speed) when the top end of a strip 151 is delivered from the mill 158, an acceleration (first acceleration) until the top end of the strip 151 is coiled up by the down coiler 154 thereafter, an acceleration (second acceleration) until a maximum speed is reached thereafter, a maximum speed, a deceleration until the maximum speed is reduced down to a terminal speed, and a terminal speed.
The control code calculation unit 115 determines the grade, the thickness, and the width of the pertinent strip to extract a corresponding speed pattern from the speed pattern table 111. In FIG. 2, mpm is m/minute and indicates a distance which the strip travels in one minute. According to FIG. 2, in a situation wherein, for example, the grade is DPI, the thickness ranges from 3.0 mm to 4.0 mm, and the width is 1200 mm, there are extracted an initial speed of 525 mpm, a first acceleration of 2 mpm/s, a second acceleration of 9 mpm/s, a maximum speed of 1000 mpm, a deceleration of 6 mpm/s, and a terminal speed of 850 mpm.
FIG. 3 shows structure of the target coiling temperature table 112. For each strip grade, the target values of the intermediate temperature and the coiling temperature are stored for each class. The control code calculation unit 115 determines the grade of the pertinent strip to extract a corresponding
target intermediate temperature and a corresponding target coiling temperature from the table 112 and conducts an arithmetic operation to calculate a control code using the temperatures.
FIG. 4 shows a configuration of the cooling header priority level table 113. Next, description will be given of an example in which each of the first-half cooling unit 170 and the second-half cooling unit 171 includes five banks and each bank includes eight headers. The total number of the headers is 40 for each of the units 170 and 171. The priority level table 113 includes a first-half cooling header priority level table 401 and a second-half cooling header priority level table 402, each thereof assigning one to 40 priority levels to an opening order or sequence of 4 0 headers.
The priority level field stores, for a combination of the strip grade, the width, and the header type (upper or lower header), an order of cooling headers to be preferentially opened. For example, (1,1) below priority level 1 of the first-half cooling header priority level table 401 indicates that the first header of the first bank is opened with a highest priority level. When the strip grade indicates DP steel (dual-phase steel) or the like, due to necessity of control of the intermediate temperature and necessity of securing the keeping time at the intermediate temperature, the first-half cooling unit
170 preferentially opens headers near the mill 158 and the second-half cooling unit 171 preferentially opens headers near the down coiler 154 to secure a sufficient air-cooling area near the intermediate pyrometer 156. In FIG. 4, the class in which the grade is DPI and the thickness ranges from 2.0 mm to 4.0 mm indicates an example of the case described above. That is, the first-half headers are opened in a descending priority level sequence beginning at the first header
(nearest to the mill 158) of the first bank and the second-half headers are opened in a descending priority level sequence beginning at the eighth header (nearest to the down coiler 154) of the eighth bank. Is indicated that in the first-half cooling unit 170, the headers are preferentially opened in an order of (1,1),
(1,2), (1,3), (1,4), (1,5), ...., (5,7), (5,8). Also,
it is indicated that in the second-half cooling unit 171, the headers are preferentially opened in an order of (10,8), (10,7), (10,6), (10,5), (10,4), ...., (6,2),
(6,1) .
On the other hand, in relation to the measurement of the mill delivery temperature and the coiling temperature, the cooling headers near the mill 158 and the down coiler 154 are not preferentially opened depending on cases. In FIG. 4, the class in which the grade is DPI and the thickness ranges from 6.0 mm to 8.0 mm indicates an example of such case. Two cooling headers near the mill 158 and four cooling
headers near the down coiler 154 are assigned with a priority level having a low value.
In addition, there is a case wherein various priority levels are assigned to the headers due to the production type of material of the strip 151, the securing of control margin in the dynamic control. However, either cases may be coped with by changing the contents of the tables of FIG. 4. Although the class items are the grade and the thickness in the embodiment, it is also possible to add the width and the like thereto. Although the upper and lower headers are of the same priority level, different priority levels may also be assigned thereto.
In the embodiment, the header patterns are represented using corresponding control codes. FIG. 5 shows a correspondence between the control codes and the cooling header open/close patterns. A control code of 40 indicates "close all headers". Control codes are assigned thereafter as "39" for a header open/close pattern indicating that merely the cooling header of priority level 1 is opened and "38" for a header open/close pattern indicating that two cooling headers of priority levels 1 and 2 are opened. That is, a control code of 0 represents a state in which all cooling headers are opened and a control code of 40 (total number of cooling headers of each of the first-half and second-half cooling units 170 and 171) represents a state in which all cooling headers are
closed. For example, for the headers for which the grade is DP, the thickness ranges from 2.0 mm to 3.0 mm, and the cooling header category is a first-half header,
a control code of 49 is assigned to a state in which only (1,1) is opened, a control code of 48 is assigned to a state in which (1,1) and (1,2) are opened, and a control code of 47 is assigned to a state in which (1,1), (1,2), and (1,3) are opened according to the header priority levels of FIG. 4. In this fashion, the control codes are thereafter assigned to the header open/close patterns up to the code of 0 indicating the state in which all headers are opened.
FIG. 6 shows an algorithm to be employed by the first-half and second-half cooling control code calculation units 116 and 117. Since the cooling units 17 0 and 171 include an equal number of cooling headers, the same algorithm is similarly used. Hereinbelow, the target temperature and the predicted temperature are the intermediate temperature for the first-half cooling control code 116 and are the coiling temperature for the second-half cooling control code 116.
In S6-1, based on the value of each class corresponding to the strip to be cooled, the value being obtained from the speed pattern table 111, there are calculated a first acceleration start position, a second acceleration start position, a stabilized speed start position, and a deceleration start position for a
transition from the stabilized speed to a terminal speed at delivery of the strip 151 from the mill 158, to calculate the speed pattern in a range from the delivery start of the strip 151 from the mill 158 to the coiling completion thereof in the down coiler 154. First acceleration start position SLls, second acceleration start position SL2a, stabilized speed start position SLcs, and deceleration start position SLde can be derived using expression (1) to (6) below.
SL1S=LSC ... (1)
wherein Lsc is a constant.
SL2s=Lmd ... (2)
wherein Lmd is distance from the mill 158 to the clown coiler 154.
(Vla)2=Lmd*2*Accl+Vraax*Vmax ... (3)
SLcs={Lmd+(Vmax-Vla)/Acc2*(Vmax+Vla)/2} ... (4)
wherein, Via is the first acceleration end speed, Accl is a first acceleration, Acc2 is a second acceleration, and Vmax is a maximum speed.
SLds={Striplen- (Vmax-Vf) /Dcc* (Vmax+Vf) /2-dccmargin} ... (5)

wherein, Striplen is a strip length, Vf is a terminal speed, Dec is a deceleration, and decmargin is a margin for a position before the tail end of the strip 151 from the mill 158 to complete deceleration.
SLde-{Striplen-dccmargin} ... (6)
In S6-2 and thereafter, according to the calculated speed pattern, a header pattern to realize the target temperature is calculated through the arithmetic operation employed in the strip temperature prediction model 117. In the embodiment, there is shown an example in which the strip is subdivided in the longitudinal direction into sections to define the sections and the header pattern is calculated using the linear interpolation method for each section.
In S6-2, for each section of the strip 151, two control codes nL and nH sandwiching a control code of the solution are defined. In this situation, since the solution exists between "open all headers" and "close all headers" for the cooling headers, nL = 0 and nH = 40 are set uniformly. The number of open cooling headers simply lowers with increase in the value of the control code. Hence, if nl < n2, Tel < Tc2 holds for the target temperatures Tel and Tc2 corresponding to these header patterns. In S6-3, the mean value of nL and nH is set as nO. In S6-4, the intermediate or coiling temperature TcO of each section corresponding
to control code nO is predicted through an arithmetic operation using the strip prediction model 114.
In S6-5, the sign of the predicted temperature TcO of the target temperature Ttarget is determined for each section. If TcO > Ttarget, the solution exists between nO and nL, and hence nO is set to nH. Contrarily, if TcO < Ttarget, the solution exists between nO and nH, and hence nO is set to nL.
In S6-6, the end condition of the algorithm is checked. If the condition is not satisfied, S6-3 to S6-5 are repeatedly executed. The end of the algorithm need only be determined when either one of the conditions "S6-3 to S6-5 are completely executed at least a fixed number of times", "the difference between predicted temperature Tc and target temperature Ttarget is equal to or less than a fixed value", and "nO is either one of nH and nL" is satisfied. The control code assigning method may be contrary to that of the embodiment. A control code of 0 is assigned to a state in which all cooling headers are closed and a control code of 40 is assigned to a state in which all cooling headers are open, and other control codes are assigned in association therewith.
FIG. 7 shows in detail the processing of the arithmetic operation of the temperature prediction corresponding to S6-4 of FIG. 6 in the first-half cooling control code calculation unit 116. Description will be given of an example of the method for the
arithmetic operation of the temperature prediction. In the example, the strip 151 is subdivided in the longitudinal direction to conduct a difference calculation for a cooling behavior of the strip 151 by increasing the time by a step of fixed interval A during a period of time from the delivery start of the mill 158 to when the strip tail end passes the intermediate pyrometer 156.
In S7-1, the calculation time is updated, and then strip speed Vt at the pertinent time is calculated using the speed pattern created in S6-1 of FIG. 6. In S7-2, by uses of the calculated strip speed, delivery length Ln from the mill 158 at the present time is calculated. Delivery length Ln is a length of the strip delivered from the mill after it is rolled and can be calculated using expression (7). Incidentally, Ln-1 is a delivery length at the previous calculation time.
Ln=Ln-i+.Vt ... (7)
In S7-3, a check is made for completion of the arithmetic operation. If the delivery length from mill Ln is more than a value obtained by adding the distance from the mill 158 to the intermediate pyrometer 156 to the total length of the strip 151, the intermediate temperature prediction calculation corresponding to one strip has been entirely completed.
Therefore, the completion of arithmetic operation is assumed. If the arithmetic operation has not been completed, temperature tracking is carried out in S7-4. That is, since the length which the strip travels in a lapse of time A from the strip position of the previous time can be derived from the relationship between Ln and Ln-1, there is executed processing to move the strip by a distance corresponding to the temperature distribution of the strip. In S7-5, the mill delivery temperature is set to the strip 151 ejected from the mill during time A. In S7-6, on the basis of open/close information of headers existing above/below each position of the strip 151 at the pertinent time, a check is made to determine whether the position is to be water-cooled or air-cooled. For the water-cooling, a heat transfer coefficient is calculated according to, for example, expression (8).
hw=9.72*105*,J'355*
{ (2.5-1.15*log(Tw) ) *D/ (pl*pc) }0.646/Tsu-Tw)
... (8)
wherein, o is a water flow rate, Tw is a water temperature, D is a nozzle diameter, pi is a nozzle pitch in the line direction, pc is a nozzle pitch in the direction vertical to the line direction, and Tsu is a surface temperature of the strip 151.
Expression (8) is a heat transfer coefficient
in the case of, so-called, laminar cooling. In addition, there are various water-cooling methods such as spray cooling, and several heat transfer coefficient calculation expressions are known. Even if the same cooling method is employed, different expressions may be used depending on cases due to, for example, reflection of latest experimental knowledge. On the other side, in the case of the air-cooling, the heat transfer coefficient is calculated according to, for example, expression (9).
Hr=a • c * [{ (27 3+Tsu) /100}4-{ (27 3+Ta)/100}4]/(Tsu-Ta)
... (9)
wherein, o is Stefan-Boltzmann's constant (=4.88), e is a header radiation ratio, Ta is an air temperature (°C), and Tsu is a surface temperature of the strip 151.
Using the heat transfer coefficient expressions represented by expressions (8) and (9), there is conducted a calculation for the cooling states of the front surface and the rear surface of the strip 151 to quantify the heat transfer rate on the respective strip surfaces. In S7-9, the temperature of each position is calculated by adding or subtracting a quantity of heat transferred during time A based on the previous temperature before the lapse of A, to thereby
calculate the temperature distribution of the strip between the mill 158 and the intermediate pyrometer 156. As a result, there is obtained the strip temperature at the position at which the intermediate pyrometer 156 is attached. The strip temperature at an upstream position relative to the intermediate pyrometer 156 attaching position is employed in the subsequent calculations. If the transfer of heat in the thickness direction of the strip 151 is to be ignored, the calculation can be carried out for each position in the longitudinal direction of the strip 151 by using expression (10).
Tn=T„_i- (ht+hb) *A/ (p*C*B) ... (10)
wherein, Tn is a current strip temperature, Tn-1 is a strip temperature A before the current time, ht is a heat transfer coefficient of a strip front surface, hb is a heat transfer coefficient of a strip rear surface, p is a strip density, C is specific heat of the strip, and B is a strip thickness.
If it is required to take the heat transfer in the thickness direction of the strip 151 into consideration, the calculation can be performed by solving a well known heat equation. The heat equation is represented by expression (11). For the expression, various articles describe a method of conducting a difference calculation by a computer by subdividing the
strip 151 in the thickness direction.
(Formula Removed)...(11)
wherein, A is heat conductivity, x is position of thickness direction, and T is a material temperature.
In S7-10, processing of S7-6 to S7-9 are repeatedly executed until the required calculation is completed in the strip longitudinal direction in the line ranging from the mill 158 to the intermediate pyrometer 156. Also, S7-1 to S7-10 are repeatedly executed until the end of the arithmetic operation is determined in S7-3.
FIG. 8 shows in detail the processing of the arithmetic operation of the temperature prediction corresponding to S6-4 in the second-half cooling control code calculation unit 117. The entire processing is almost similar to that of FIG. 7. However, since the calculation object of FIG. 8 is the strip in a range from the position of the intermediate pyrometer 156 to the down coiler 154, the position of the strip passing the intermediate pyrometer 156 is identified in S8-5. The target intermediate temperature is set to the identified position to calculate, in S8-6 and S8-9, the strip temperature of the strip from the position of the intermediate pyrometer 156 to the down coiler 154. In S8-9, there is calculated the temperature of the strip 151 from the
intermediate pyrometer 156 to the down coiler 154. In S8-10, at the pertinent time, a check is made to determine completion of the calculation for the strip existing between the intermediate pyrometer 156 and the down coiler 154.
FIG. 9A shows an example of a change in the control code due to optimization of the speed pattern. Since the first processing is processing for the same initial value (nL=0, nH-40) at each position, the control code is updated to 20 for the entire area of the strip 151. In the second processing, depending on whether the temperature prediction result for each position of the strip 151 is more or less than Ttarget, the updated control code differs from the control code "20".
FIG. 9B shows an example in which when the strip speed is low, for portions of the strip 151 near the top end or the tail end thereof, the control code is updated to a control code to close the header. When the strip speed is high, for a central portion of the strip 151, the control code is updated to a control code to open the header. Specifically, as shown in the second processing of FIG. 9B, for the top end and the tail end, the control codes are updated as nL = 20 and nH = 40 by the first processing in S6-5. Hence, the control codes are updated to the mean value thereof, i.e., 30. On the other hand, for the central portion, since the control codes are updated as nL = 0 and nH =
20 by the first processing in S6-5, the control code is updated to 10. In this way, for each of the first-half and second-half cooling control code calculation units 116 and 117, processing of S6-3 to S6-6 of FIG. 6 is repeatedly executed to sequentially update the control codes.
FIG. 10 shows in detail a configuration of the first-half cooling dynamic control unit 121 and processing in each section thereof. The control code outputted from the first-half cooling control code calculation unit 116 is corrected in a realtime fashion by the dynamic control unit 121 during the cooling control of the strip 151. The dynamic control unit 121 includes the intermediate temperature difference correction unit 123, the mill delivery temperature difference compensation unit 124, the first-half cooling speed difference compensation unit 125, and the first-half cooling operation quantity mixing unit 126 which are described in conjunction with FIG. 1. In addition, the control unit 121 includes a first influence coefficient table 1001, a second influence coefficient table 1002, and a third influence coefficient table 1003 which are used to calculate a correction quantity. A control code calculated by adding the control code outputted from the first-half cooling control code calculation unit 116 to the control code change quantity calculated for each position in the strip longitudinal direction by the
first-half cooling operation quantity mixing unit 126 of the first-half cooling dynamic control unit 121 is fed to a first-half cooling header pattern conversion unit 141.
FIG. 11 shows structure of the first influence coefficient table 1001. The table 1001 stores therein a quantity of change 3Tm/nA (°C) in the intermediate temperature with respect to a change in the control code, namely, a numeric value corresponding to a change quantity of intermediate temperature Tm when one of the cooling headers 162 is opened or closed. 3Tm/nA is stored for each class categorized according to a combination of the strip thickness, the strip speed, and the first-half cooling control code. FIG. 11 shows an example in which OTm/nA) = 3.0°C holds when the strip thickness is 3 mm or less, the speed of the strip 151 is 450 mpm or less, and the first-half cooling control code is 9 or less. If one cooling header 162 is opened or closed, intermediate temperature Tm measured by the intermediate pyrometer 156 goes down or up 3.0°C.
FIG. 12 shows a configuration of the second influence coefficient table 1002. The table 1002 stores therein a quantity of change <9Tm/3V (°C/mpm) in the intermediate temperature with respect to a change in the strip speed. The value is a change quantity of intermediate temperature Tm when the speed of the strip 151 is increased or decreased 1 mpm. 3Tm/dV is stored
for each class categorized according to the strip thickness, the strip speed, and the first-half cooling control code. In the example of FIG. 12, there is shown an event in which (əTm/əV) = 2.2°C holds when the strip thickness is 3 mm or less, the speed of the strip 151 is 450 mpm or less, and control code n is 9 or less. If the speed of the strip 151 is increased or decreased 1 mpm, intermediate temperature Tm measured by the intermediate pyrometer 156 goes down or up 2.2°C.
FIG. 13 shows a configuration of the third influence coefficient table 1003. The table 1003 stores therein a quantity of change dTm/dTf in the intermediate temperature with respect to a change in the mill delivery temperature. This is a numeric value corresponding to a change quantity of intermediate temperature Tm when the strip temperature at the position of the mill delivery side pyrometer is increased or decreased 1°C. əTm/əTf is stored for each class categorized according to the strip thickness, the strip speed, and the first-half cooling control code. FIG. 13 shows an example in which ə9Tm/əTf) = 0.9°C holds when the strip thickness is 3 mm or less, the speed of the strip 151 is 450 mpm or less, and control code n is 9 or less. If the measured value of the mill delivery temperature becomes 1°C higher or lower, intermediate temperature Tm measured by the intermediate pyrometer 156 goes up or down 0.9°C.
In FIGS. 11 to 13, the items by class may be similarly reduced or may be increased by adding a mill delivery temperature and the like.
Next, description will be given of processing of the intermediate temperature difference correction unit 123. The correction unit 123 is activated at a fixed cycle to detect an intermediate temperature to perform feedback (FD) control. The correction unit 123 includes an intermediate temperature difference calculation unit 1004 to calculate, for the difference between the measured intermediate temperature and the target temperature, a change quantity of a first-half cooling control code appropriate to suppress the difference. That is, the calculation unit 1004 acquires the difference between the target intermediate temperature and the measured value measured by the intermediate pyrometer 156 as well as influence coefficient (əTm/An) corresponding to a class associated with the current state from the first influence coefficient table 1001 to calculate the change quantity of the control code through an arithmetic operation of expression (12).
(Formula Removed)...(12)
wherein, Anl is a change quantity of a control code due to intermediate temperature FB control, Gl is a constant (intermediate temperature FB control gain),
(əTm/An) is an influence coefficient by class extracted from the first influence coefficient table 1101, and ATm is an intermediate temperature difference. On the other hand, the mill delivery temperature difference compensation unit 124 is similarly activated at a fixed cycle to carry out mill delivery temperature difference Feed-Forward (FF) control. The compensation unit 124 includes a mill delivery temperature difference correction quantity calculation unit 1005 to calculate a change quantity of a control code appropriate for the difference between the mill delivery temperature assumed in the preset calculation and the actual result temperature detected by the mill delivery side pyrometer 155, and an application position identification unit 1008 to determine a position in the longitudinal direction of the strip 151 to apply a result of the calculation. The calculation unit 1005 obtains difference vTf between Tf assumed in the setup calculation and Tf measured by the mill delivery side pyrometer 155. Furthermore, the calculation unit 1005 obtains the influence coefficients by class (dTm/An) and (dTm/dTf) associated with the current cooling state from the first and third influence coefficient tables 1001 and 1003 to calculate the change quantity of the first-half cooling control codes through an arithmetic operation using expression (13).
(Formula Removed) . . . (13)
wherein, An2 is a change quantity in the first-half cooling control codes due to mill delivery temperature difference FF control, G2 is a constant (mill delivery temperature difference FF control gain), (3Tm/3Tf) is an influence coefficient by class extracted from the third influence coefficient table 1003, and ATf is a mill delivery temperature difference. The calculated An2 is fed to the application position identification unit 1008.
FIG. 14 shows processing of the application position identification unit 1008. For the strip 151, sections 1501 are defined in the longitudinal direction as shown in FIG. 15. In the example of FIG. 14, n sections are defined in a range from the strip top end to the strip tail end to be assigned respectively with section numbers. That is 1 is assigned to the section of the strip top end and n is assigned to the section of the strip tail end.
In S14-1, the application position identification unit 1008 obtains the section number of the strip passing just beneath the installation position of the mill delivery side pyrometer 155. The obtained section number is assumed as i. Ordinarily, a controller to control a mill in a steelmaking system calculates information of a tracking position of the
strip 151. That is, the top position (the delivery length from the mill 158), the tail end position, and the like of the strip 151 are periodically calculated using the rotary speed of the mill 157 and that of the down coiler 154 as well as signals obtained from position sensors such as a Hot Metal Detector (HMD) and a Cold Metal Detector (CMD) details of which will not be described. On the basis of the relationship between the information above and the attaching position of the mill delivery side pyrometer 155, it is possible to identify the section number of the strip passing the installation position of the mill delivery side pyrometer.
In S14-2, the identification unit 1008 obtains output An2 from the mill delivery temperature difference correction quantity calculation unit 1005. In S14-3, the identification unit 1008 registers An2 to section number i of the installation position of the mill delivery side pyrometer 155 obtained in S14-1. This value is referred to as (An2)i hereinbelow.
The first-half cooling speed difference compensation unit 125 is similarly activated at a fixed cycle to conduct speed difference feed-forward control. The compensation unit 12 5 includes a speed difference correction quantity calculation unit 1006 to calculate a change quantity of a first-half cooling control code appropriate for the difference between the strip speed at the pertinent time assumed in the preset calculation
and the actual strip speed, and an application position identification unit 1009 to determine a position in the longitudinal direction of the strip 151 to which the the calculation result is applied.
The speed difference correction quantity calculation unit 1006 obtains difference Av between the strip speed assumed in the setup and the actual result speed as well as the influence coefficients by class (dTm/An) and (3Tm/3V) associated with the current cooling state from the first and second influence coefficient tables 1001 and 1002 to calculate a change quantity of the control code through an arithmetic operation using expression (14).
(Formula Removed)...(14)
wherein, An3 is a change quantity of a first-half cooling control code due to strip speed difference FF control, G3 is a constant (strip speed difference FF control gain), (3Tm/3V) is an influence coefficient by the pertinent class extracted from the second influence coefficient table 1002, and Av is a strip speed difference.
The calculated An3 is fed to the application position identification unit 1009. FIG. 16 shows processing of the identification unit 1009. In S16-1, the unit 1009 obtains, from the tracking information of
the strip 151, the section numbers of the strip at the entry position and the discharge position of the first-half cooling unit 170. In S16-2, the identification unit 1009 determines, using the obtained section numbers, sections for which a control code correction is required and calculates a correction ratio for each section. Correction ratio Ri for strip section number i can be calculated using expression (15).
(Formula Removed)...(15)
wherein, II is the section number of the strip at the delivery position of the first-half cooling unit and 12 is the section number of the strip at the entry position of the first-half cooling unit.
In S16-3, the application position identification unit 1009 obtains output An3 from the speed difference correction quantity calculation unit 1006. In S16-4, the unit 1009 calculates the control code correction quantity for each section using An3 and the calculated correction ratio Ri to register the correction quantity to the pertinent section number. The correction quantity (An3) for strip section number i can be calculated using expression (16).
(Formula Removed)
Next, description will be given of processing of the
first-half cooling operation quantity mixing unit 126. The unit 126 adds Anl, (An2)i, and (An3)i to each other to calculate the operation quantity for each strip section. Specifically, the quantity mixing unit 126 calculates output Ndi from the first-half cooling dynamic control unit 121 for strip section i using expression (17).
(Formula Removed)
The control unit 121 outputs Ndi of each section to correct, according to this value, the control code outputted from the first-half cooling control code calculation unit 116 and delivers the resultant code to the first-half cooling header pattern conversion unit 141.
FIG. 17 shows a correction result obtained when the dynamic control unit 121 corrects the first-half cooling control codes outputted from the code calculation unit 116. In FIG. 17, while the first-half cooling control codes are kept retained for the strip positions "500 m to 520 m", the first-half cooling control code for the position ranging from 520 m to 525 m is corrected from 12 to 14.
Although the respective correction quantity calculation units 1004 to 1006 are activated at a fixed cycle in the embodiment, there may be employed various activation methods such as a method of activating the
unit at each timing when a fixed length of the strip 151 is delivered from the mill 158 and a method of activating the unit when the difference in each of the mill delivery temperature, the intermediate temperature, and the strip speed is equal to or more than a fixed value.
FIG. 18 shows a configuration and processing of each section of the second-half cooling dynamic control unit 122. A control code outputted from the second-half cooling control code calculation unit 117 is corrected in a realtime fashion by the dynamic control unit 122 during the cooling control of the strip 151.
The dynamic control unit 122 includes the coiling temperature difference correction unit 127, the intermediate temperature difference compensation unit 128, the second-half cooling speed difference compensation unit 129, and the second-half cooling operation quantity mixing unit 130 which are described in conjunction with FIG. 1. The control unit 122 also includes a fourth influence coefficient table 1801, a fifth influence coefficient table 1802, and a sixth influence coefficient table 1803 which are used to calculate a correction quantity. A control code change quantity calculated for each position in the strip longitudinal direction by the second-half cooling operation quantity mixing unit 130 of the second-half cooling dynamic control unit 122 is fed to second-half
cooling header pattern conversion unit 142.
FIG. 19 shows structure of the fourth influence coefficient table 1801. The table 1801 stores therein a quantity of change 3Tc/An (°C) in the coiling temperature with respect to a change in the control code. This value corresponds to a change quantity of coiling temperature Tc when one of the cooling headers 162 is opened or closed. 3Tc/An is stored for each class categorized according to the strip thickness, the strip speed, and the second-half cooling control code. In the example of FIG. 19, , (3Tc/nA) = 4.0°C holds when the strip thickness is 3 mm or less, the speed of the strip 151 is 450 mpm or less, and the second-half cooling control code is 9 or less. If one cooling header 162 is opened or closed, coiling temperature Tc measured by the coiling pyrometer 157 goes down or up 4.0°C.
FIG. 20 shows a configuration of the fifth influence coefficient table 1802. The table 1002 stores therein a quantity of change əTc/əV (°C/mpm) in the coiling temperature with respect to a change in the strip speed. The value is a change quantity of coiling temperature Tc when the speed of the strip 151 is increased or decreased 1 mpm. əTc/əV is stored for each class categorized according to the strip thickness, the strip speed, and the second-half cooling control code. In the example of FIG. 20, (əTc/əV) = 3.2°C holds when the strip thickness is 3 mm or less,
the speed of the strip 151 is 450 mpm or less, and control code n is 9 or less. If the speed of the strip 151 is increased or decreased 1 mpm, coiling temperature Tc measured by the coiling pyrometer 157 goes down or up 3.2°C.
FIG. 21 shows a configuration of the sixth influence coefficient table 1803. The table 1803 stores therein a quantity of change <9Tc/3Tm in the mill delivery temperature with respect to a change in the intermediate temperature. This is a numeric value corresponding to a change quantity of mill delivery temperature Tc when the strip temperature at the position of the intermediate pyrometer is increased or decreased 1°C. əTc/əTm is stored for each class categorized according to the strip thickness, the strip speed, and the second-half cooling control code. In the example of FIG. 21, , (3Tc/3Tm) = 0.9°C holds when the strip thickness is 3 mm or less, the speed of the strip 151 is 450 mpm or less, and control code n is 9 or less. If the measured value of the intermediate temperature becomes 1°C higher or lower, coiling temperature Tc measured by the coiling pyrometer 157 goes up or down 0.9°C.
In FIGS. 19 to 21, the items by class may be similarly reduced or may be increased by adding an intermediate temperature and the like.
Next, description will be given of processing of the coiling temperature difference correction unit
127. The correction unit 127 is activated at a fixed cycle to detect a coiling temperature to perform feedback (FD) control. The correction unit 127 includes a coiling temperature difference correction quantity calculation unit 1804 to calculate a change quantity of a second-half cooling control code appropriate for the difference between the coiling temperature and the target temperature. The calculation unit 1804 acquires the difference between the target coiling temperature and the measured value measured by the coiling pyrometer 157 as well as influence coefficient (dTc/An) corresponding to a class associated with the current state from the fourth influence coefficient table 1801 to calculate the change quantity of the control code through an arithmetic operation of expression (18).
(Formula Removed)
wherein, An4 is a change quantity of the second-half cooling control code due to coiling temperature FB control, G4 is a constant (coiling temperature FB control gain), (dTc/An) is an influence coefficient by pertinent class extracted from the fourth influence coefficient table, and ATc is a coiling temperature difference.
Similarly, the intermediate temperature difference compensation unit 128 is activated at a
fixed cycle to carry out intermediate temperature difference Feed-Forward (FF) control. The compensation unit 128 includes an intermediate temperature difference correction quantity calculation unit 1805 to calculate a change quantity of a second-half cooling control code appropriate for the difference between the target value of the intermediate temperature and the actual result temperature detected by intermediate pyrometer 155 and an application position identification unit 1808 to determine a position in the longitudinal direction of the strip 151 to apply a result of the calculation. The calculation unit 1805 obtains difference ATm between the intermediate temperature target value and Tm measured by the intermediate pyrometer 156 as well as the influence coefficients by class (3Tc/An) and (3Tc/3Tm) associated with the current cooling state from the fourth and sixth influence coefficient tables 1801 and 1803 to calculate the change quantity of the second-half cooling control code through an arithmetic operation using expression (19).
(Formula Removed)
wherein, An5 is a change quantity in the second-half cooling control code due to intermediate temperature difference FF control, G5 is a constant (intermediate
temperature difference FF control gain), (dTc/STm) is an influence coefficient by pertinent class extracted from the sixth influence coefficient table, and ATm is a mill delivery temperature difference.
The calculated An2 is delivered to the application position identification unit 1808. FIG. 22 shows processing of the identification unit 1808. Similarly, for the strip 151, sections 1501 are defined in the longitudinal direction as shown in FIG. 15. In S22-1, the identification unit 1808 obtains the section number of the installation position of the intermediate pyrometer 156. The obtained section number is assumed as i. In S22-2, the identification unit 1808 obtains output An5 from the intermediate temperature difference correction quantity calculation unit 1805. In S22-3, the identification unit 1808 registers An5 to section number i of the intermediate pyrometer 156 installation position obtained in S22-1. This value is referred to as (An5)i hereinbelow.
The second-half cooling speed difference compensation unit 129 is similarly activated at a fixed cycle to conduct speed difference feed-forward control. The compensation unit 129 includes a speed difference correction quantity calculation unit 1806 to calculate a change quantity of a second-half cooling control code appropriate for the difference between the strip speed at the pertinent time assumed in the preset calculation and the actual strip speed, and an application position
identification unit 1809 to determine a position in the longitudinal direction of the strip 151 to which the calculation result is applied. The speed difference correction quantity calculation unit 1806 obtains difference Av between the strip speed assumed in the setup and the actual result speed as well as the influence coefficients by class (əT/n) and (əTc/əV) associated with the current cooling state from the fourth and fifth influence coefficient tables 1801 and 1802 to calculate the change quantity in the control code through an arithmetic operation using expression (20) .
(Formula Removed)
wherein, An6 is a second-half cooling control code change quantity due to strip speed difference FF control, G6 is a constant (strip speed difference FF control gain) , (əTc/əV) is an influence coefficient by the pertinent class extracted from the fifth influence coefficient table, and Av is a strip speed difference.
The calculated An6 is outputted to the application position identification unit 1809. FIG. 23 shows processing of the identification unit 1809. In S23-1, the unit 1809 obtains, from the tracking information of the strip 151, the strip section numbers of the strip at the entry position and the discharge

position of the second-half cooling unit 171. In S23-2, the identification unit 1809 determines, using the obtained section numbers, sections for which a control code correction is required and calculates a correction ratio for each section. Correction ratio Ri for strip section number i can be calculated using expression
(21) .
(Formula Removed)
wherein, II is the section number of the strip at the second-half cooling unit discharge position and 12 is the section number of the strip at the second-half cooling unit entry position.
In S23-3, the application position identification unit 1809 obtains output An6 from the speed difference correction quantity calculation unit 1806. In S23-4, the unit 1809 calculates the control code correction quantity for each section using An6 and the correction ratio calculated in S23-2 to register the correction quantity to the pertinent section number. The correction quantity (An6) for strip section number i can be calculated using expression
(22) .
(Formula Removed)
Next, description will be given of processing
of the second-half cooling operation quantity mixing unit 130. The unit 130 adds Anl, (An2)i, and (An3)i to each other to calculate the operation quantity for each strip section. Specifically, the quantity mixing unit 130 calculates output Ndi from the second-half cooling dynamic control unit 122 for strip section i using expression (23).
(Formula Removed)
The control unit 122 outputs Ndi of each section. According to this value, the control code outputted from the second-half cooling control code calculation unit 117 is modified to be fed to the second-half cooling header pattern conversion unit 142.
FIG. 24 shows correction results obtained when the dynamic control unit 122 corrects the second-half cooling control codes outputted from the code calculation unit 117. In FIG. 24, while the second-half cooling control codes are kept retained for the strip positions ranging from 500 m to 510 m, the second-half cooling control codes for the positions ranging from 510 m to 525 m are corrected from 24 to 22.
Although the respective correction quantity calculation units 1804 to 1806 are activated at a fixed cycle in the embodiment, there may be employed various activation methods, for example, a method of activating
the unit each timie a fixed length of the strip 151 is delivered from the mill 158 and a method of activating the unit at timing when the difference in each of the intermediate temperature, the coiling temperature, and the strip speed is equal to or more than a fixed value. FIG. 25 shows an algorithm for the first-half cooling header pattern conversion unit 141. In S25-1, the conversion unit 141 calculates distance Lh of the strip 151 passing just beneath the cooling header relative to the top end thereof. In S25-2, the conversion unit 141 makes a check to determine whether or not Lh is less than 0. If Lh is less than 0, the strip 151 has not reached the pertinent cooling header, and control goes to S25-5. If Lh is more than 0, the strip 151 has reached the pertinent cooling header. Therefore, in S25-3, the conversion unit 141 extracts a first-half cooling control code corresponding to distance Lh. That is, the conversion unit 141 collates Lh with the strip position of FIG. 15 to extract a first-half cooling control code of the position corresponding to distance Lh. In S25-4, since it is possible to determine, by use of the first-half cooling control code of the pertinent position, a priority level up to which cooling headers can be opened, the conversion unit 141 determines the open/close of the pertinent cooling headers by using the above information and the information stored in the first-half cooling header priority level table 402. In S25-5, the conversion unit 141 determines whether or not the operation has been finished for all cooling headers. If the operation has not been finished, the conversion unit 141 repeatedly executes processing of S25-1 to S25-4 until the operation is completely finished.
FIG. 26 shows an algorithm to be used by the second-half cooling header pattern conversion unit 142. In S26-1, the conversion unit 142 calculates distance Lh of the strip 151 passing just beneath the cooling header relative to the top end thereof. In S26-2, the conversion unit 142 makes a check to determine whether or not Lh is less than 0. If Lh is less than 0, the strip 151 has not reached the pertinent cooling header, and control proceeds to S26-5. If Lh is more than 0, the strip 151 has reached the pertinent cooling header. Hence, in S26-3, the conversion unit 142 extracts a first-half cooling control code corresponding to distance Lh. That is, the conversion unit 142 collates Lh with the strip position of FIG. 15 to extract a first-half cooling control code of the position corresponding to distance Lh. In S26-4, since it is possible to determine, by use of the first-half cooling control code of the pertinent position, a priority level up to which cooling headers can be opened, the conversion unit 142 determines the open/close of the pertinent cooling headers by using the information described above and the information stored in the
second-half cooling header priority level table 402. In S26-5, the conversion unit 142 determines whether or not the operation has been finished for all cooling headers. if the operation has not been finished, the conversion unit 142 repeatedly executes processing of S26-1 to S26-4 until the operation is completely finished.
In conjunction with this embodiment, description has been given of an example in which the number of cooling headers is 40 for the first-half and second-half cooling units 170 and 171. However, the number of the headers will be changed according to the equipment. [Second Embodiment]
Next, description will be given of a second embodiment implemented by adding, to the first embodiment, processing in which a check is made after execution of the preset operation to determine whether or not the strip 151 has been kept for a fixed period of time at the intermediate temperature, and if the keeping time is insufficient, the speed pattern is changed to secure the keeping time.
FIG. 27 shows the second embodiment in which an intermediate temperature keeping time calculation unit 2701 and a speed pattern change unit 2702 are added to the coiling temperature control apparatus 100 of first embodiment (FIG. 1). The calculation unit 2701 obtains a first-half cooling control code and a
second-half cooling control code calculated by the present control unit 110 as well as maximum speeds categorized by pertinent classes from the speed pattern table 111. Furthermore, the calculation unit 2701 obtains an opening priority level of each header for each pertinent class from the cooling header priority level table 113 to predict, based thereon, for how many minutes the strip 151 has been kept at the intermediate temperature.
FIG. 28 shows processing to be executed by the intermediate temperature keeping time calculation unit 2701. In S28-1, the unit 2701 identifies an open header nearest to the intermediate pyrometer 156 based on the first-half cooling control codes and the priority level of each cooling header of the first-half cooling unit 170. In S28-2, the unit 2701 similarly identifies an open header nearest to the intermediate pyrometer 156 based on the second-half cooling control codes and the priority level of each cooling header of the second-half cooling unit 171. In S28-3, the time calculation unit 2701 extracts from the speed pattern table 111 a maximum speed by a class corresponding to the strip 151 being cooled. In S28-4, based on the information above, the unit 2701 predicts a period of time for which the strip 151 has been kept at the intermediate temperature. Keeping temperature Tk can be calculated using expression (24).
(Formula Removed)
wherein, L is distance between an open header nearest to the intermediate pyrometer 156 of the first-half cooling unit 170 and an open header nearest to the intermediate pyrometer 156 of the second-half cooling unit 171 and Vmx is a maximum speed. If keeping time Tk satisfies a required period of keeping time beforehand determined, the time calculation unit 2701 terminates processing in S28-5. If keeping time Tk is less than the required keeping time, the time calculation unit 2701 transfers control to the speed pattern change unit 2702 to execute processing in which the keeping time is satisfied by lowering the maximum speed.
FIG. 29 shows a sequence of processing steps to change the speed pattern. In S29-1, the pattern change unit 2702 calculates insufficient keeping time ATk and then calculates reduction speed quantity AVs to compensate the time by using expression (25). Insufficient keeping time ATk is a value obtained by subtracting Tk from the required keeping time.
(Formula Removed)………..(25)
Thereafter, the pattern change unit 2702 sets the maximum speed to n-AVs. n is a constant ranging from 0 to 1. In S29-2, the unit 2702 activates the
preset control unit 110 to execute the processing of the first embodiment to calculate a change in the header pattern due to the reduction in the maximum speed. In S29-3, the unit 2702 again activates the intermediate temperature keeping time calculation unit 2701 to calculate the intermediate temperature keeping time of the strip 151. In S29-4, the unit 2702 determines whether or not the keeping time satisfies the required keeping time to repeatedly execute processing of S29-1 to S29-3 until the keeping time satisfies the required keeping time.
If n is set to a value near one, it is possible that the keeping time at the intermediate temperature is satisfied through one arithmetic operation. However, this lowers the maximum speed too much in some cases. On the other hand, if n is set to a value near zero, it is required that the processing of S29-1 to S29-3 is repeatedly executed several times. However, a speed near the maximum speed can be obtained in a range satisfying the keeping time. In consideration of this situation, it is only necessary to determine n, under restrictions of the calculation time and the calculation load.
In conjunction with the second embodiment, description has been given of an example to execute speed reduction processing by strictly considering the change in the header pattern with respect to the reduction in the maximum speed. However, by beforehand
setting n to an appropriate value, the processing may be completed through one re-calculation by omitting the repetitive operation of S29-1 to S29-3. In this case, there is obtained a merit that the maximum value of the calculation time can be determined. [Third embodiment]
Next, description will be given of a third embodiment of the present invention. This is an embodiment to stabilize the cooling control by setting limits on the influence of the control results of the first-half cooling dynamic control unit 121 upon the operation of the second-half cooling dynamic control unit 122.
FIG. 30 shows a third embodiment implemented by adding a stabilized control unit 3001 to the coiling temperature control apparatus 100 of the first embodiment (FIG. 1). The stabilized control unit 3001 additionally disposed in the present embodiment obtains, from the signals of the first-half cooling operation quantity mixing unit 126 of the first-half cooling dynamic control unit 121, signals required for the stabilization processing to perform a stabilized control operation and then outputs results of the operation to the second-half cooling dynamic control unit 122. Various stabilization processing is possible. However, in conjunction with the third embodiment, description will be given of an example to prevent the output from the intermediate temperature
difference compensation unit 128 of the second-half cooling dynamic control unit 122 from becoming unstable because the intermediate temperature excessively alters due to a delay in a response of the cooling header 162 with respect to the speed difference compensation arithmetic operation of the first-half cooling dynamic control unit 121.
FIG. 31 shows operation of the stabilized control unit 3001. In S31-1, the control unit 3001 predicts change quantity Arms of the intermediate temperature corresponding to speed change v. Tms can be calculated using Av and (əTm/əV) of the pertinent class extracted from the second influence coefficient table 1002, by use of expression (26).
(Formula Removed)
In S31-2, the stabilized control unit 3001 outputs Tms to the second-half cooling dynamic control unit 122. Although a change of ATms in the intermediate temperature due to the speed change is predictable from expression (26), this temperature change is suppressed later by the first-half cooling speed difference compensation unit 125.
On the other hand, during a period of time from when the cooling header 162 is opened or closed to when the state of the strip surface changes, about two seconds are ordinarily required due to the response
delay of the cooling header and the like. Therefore, a change in the intermediate temperature corresponding to the speed change is transiently observed in some cases. However, if the intermediate temperature difference compensation unit 128 of the second-half cooling dynamic control unit 122 operates in association therewith, the cooling header opens or closes in a short period of time and the cooling control resultantly becomes unstable. At reception of ATms, the compensation unit 128 executes processing to suppress the header modification quantity associated with the temperature difference equal to or less than ATms during a period of time ATI from the speed change to when the effect of the header operation by the first-half cooling speed compensation unit 125 is observed via the intermediate temperature.
Specifically, according to expression (27), a dead zone is set to a change in temperature from 0 to Tms relative to the current state such that the header modification corresponding thereto is not conducted.
(Formula Removed)…………………(27)
wherein, n5* is a second-half cooling control code change quantity due to intermediate temperature difference FF control immediately before the speed change and Tm' is the difference between the intermediate temperature immediately before the speed change and the intermediate temperature at the time of control; and Tm* and Tm' have a relationship of the following expression.
Tm*=0 (when 0<Tm'<Tms) Tm*=Tm' -Tms (when Tms<Tm') Tm*=Tm' (when Tm<0)
Expression (27) is an example for 0 < Tms (when the speed goes up), but a case of Tms < 0 (when the speed goes down) may also be coped with by similar processing.
After a lapse of T1 relative to the speed change, the processing of expression (27) is released. Control returns to the ordinary processing indicated by expression (19) of the intermediate temperature difference compensation unit 128. Various methods can be considered for the cooling control stabilization processing such as a scheme in which if the intermediate temperature differs from the target value, the operation of the intermediate temperature difference compensation unit 128 is suppressed until the intermediate temperature difference correction unit 123 stabilizes the intermediate temperature.
The present invention is widely applicable to cooling control of the hot rolling line, specifically,
cooling control for a high-class strip for which an intermediate temperature is required to be controlled.
It should be further understood by those skilled in the art that although the foregoing description has been made on embodiments of the invention, the invention is not limited thereto and various changes and modifications may be made without departing from the spirit of the invention and the scope of the appended claims.

WE CLAIMS:-
1. A coiling temperature control apparatus (100) which cools a strip (151), rolled by a hot rolling mill
(158), by a cooling unit (153) disposed on a delivery side of the mill to control a coiling temperature of the strip before the strip is coiled by a down coiler
(154) as well as an intermediate temperature of the strip when the strip passes a beforehand determined intermediate position of the cooling unit to predetermined target temperatures, comprising:
a strip temperature prediction model (114) which predicts the intermediate temperature of the strip based on information of a first-half cooling header pattern as a combination of open/close of cooling headers disposed in a cooling unit between the mill and the intermediate position and which predicts the coiling temperature of the strip based on information of a second-half cooling header pattern as a combination of open/close of cooling headers disposed in a cooling unit between the intermediate position and the down coiler;
a preset control unit (110) which predicts, before cooling control, the intermediate temperature and the coiling temperature using the strip temperature prediction model to calculate, using results of the prediction, the first-half cooling header pattern to realize a target intermediate temperature and the second-half cooling header pattern to realize a target
coiling temperature;
a first-half cooling dynamic control unit
(121) which observes a state of the strip during the
cooling control to calculate and to output a change
quantity of the first-half cooling header pattern to
adjust an observed intermediate temperature to the
target intermediate temperature; and
a second-half cooling dynamic control unit
(122) which observes a state of the strip during the
cooling control to calculate and to output a change
quantity of the second-half cooling header pattern to
adjust an observed coiling temperature to the target
coiling temperature.
2. A coiling temperature control apparatus according to claim 1, wherein the first-half cooling dynamic control unit comprises:
an intermediate temperature difference correction unit (123) which calculates a change quantity of the first-half cooling header pattern to compensate a difference between the target intermediate temperature and an intermediate temperature of the strip measured during the cooling control;
a mill delivery temperature difference compensation unit (124) which calculates a change quantity of the first-half cooling header pattern to compensate a difference between a mill delivery temperature of the strip assumed in the preset control and a mill delivery temperature of the strip measured
during the cooling control;
a first-half cooling speed difference compensation unit (125) which calculates a change quantity of the first-half cooling header pattern to compensate a difference between a strip speed assumed in the preset control and a strip speed measured during the cooling control; and
a first-half cooling operation quantity mixing unit (126) which mixes with each other outputs from the intermediate temperature difference correction unit, the mill delivery temperature difference compensation unit, and the first-half cooling speed difference compensation unit for each position of the strip in a longitudinal direction thereof to calculate a change quantity of the first-half cooling header pattern.
3. A coiling temperature control apparatus according to claim 1, wherein the second-half cooling dynamic control unit comprises:
a coiling temperature difference correction unit (127) which calculates a change quantity of the second-half cooling header pattern to compensate a difference between the target coiling temperature and a coiling temperature of the strip measured during the cooling control;
an intermediate temperature difference correction unit (127) which calculates a change quantity of the second-half cooling header pattern to
compensate a difference between the target intermediate temperature and an intermediate temperature of the strip measured during the cooling control;
a second-half cooling speed difference compensation unit (129) which calculates a change quantity of the second-half cooling header pattern to compensate a difference between a strip speed assumed in the preset control and a strip speed during the cooling control; and
a second-half cooling operation quantity mixing unit (130) which mixes with each other outputs from the coiling temperature difference correction unit, the intermediate temperature difference correction unit, and the second-half cooling speed difference compensation unit for each position of the strip in a longitudinal direction thereof to calculate a change quantity of the second-half cooling header pattern.
4. A coiling temperature control apparatus according to claim 1, wherein the preset control unit comprises:
a first-half cooling header priority level table (401) storing therein a priority relationship of an opening sequence of cooling headers disposed between the hot rolling mill and the intermediate position;
a second-half cooling priority level table (402) storing therein a priority relationship of an opening sequence of cooling headers disposed between
the intermediate position and the down coiler;
a first-half cooling control code calculation unit (116) which establishes a correspondence between the first-half cooling header pattern (FIG. 5) and control codes(FIG. 5) created using information of the first-half cooling header priority level table to predict an intermediate temperature using the strip temperature prediction model and which calculates, using results of the prediction, control codes to realize the target intermediate temperature; and
a second-half cooling control code calculation unit (117) which establishes a correspondence between the second-half cooling header pattern and control codes created using information of the second-half cooling header priority level table to predict a coiling temperature using the strip temperature prediction model and which calculates, using results of the prediction, control codes to realize the target coiling temperature.
5. A coiling temperature control apparatus according to claim 4, wherein the control codes are assigned with a maximum value in a state in which the headers are opened and with a minimum value in a state in which the headers are closed, and the control codes have a correspondence such that with an increase in the control codes, the intermediate or coiling temperature uniformly goes down (FIG. 5).
6. A coiling temperature control apparatus
according to claim 4, wherein the control codes are assigned with a maximum value in a state in which the headers are opened and with a minimum value in a state in which the headers are closed, and the control codes have a correspondence such that with an increase in the control codes, the intermediate or coiling temperature uniformly goes up (FIG. 5) .
7. A coiling temperature control apparatus according to claim 4, wherein the first-half cooling dynamic control unit comprises:
an intermediate temperature difference correction unit (123) which calculates, as a control code modification quantity, a change quantity of the first-half cooling header pattern to compensate a difference between the target intermediate temperature and a temperature at the intermediate position of the strip measured during the cooling control;
a mill delivery temperature difference compensation unit (124) which calculates, as a control code modification quantity, a change quantity of the first-half cooling header pattern to compensate a difference between a mill delivery temperature of the strip assumed in the preset control and a mill delivery temperature of the strip measured during the cooling control;
a first-half cooling speed difference compensation unit (125) which calculates, as a control code modification quantity, a change quantity of the
first-half cooling header pattern to compensate a difference between a strip speed assumed in the preset control and a strip speed during the cooling control; and
a first-half cooling operation quantity mixing unit (126) which mixes with each other outputs from the intermediate temperature difference correction unit, the mill delivery temperature difference compensation unit, and the first-half cooling speed difference compensation unit for each position of the strip in a longitudinal direction thereof to calculate a control code modification quantity, the coiling temperature control apparatus comprising
a first-half cooling header pattern conversion unit (141) which recognizes a position of the strip in a longitudinal direction thereof just beneath each of the headers and which converts a result obtained through an operation into a first-half cooling header pattern to output the pattern to the cooling unit, the operation being conducted to correct the first-half cooling control codes, which are calculated by and are outputted from the first-half cooling control code calculation unit by establishing a correspondence to each position of the strip in a longitudinal direction thereof, by use of the control codes outputted from the first-half cooling dynamic control unit. 8. A coiling temperature control apparatus according to claim 4, wherein the second-half cooling dynamic control unit comprises:
a coiling temperature difference correction unit (127) which calculates, as a control code modification quantity, a change quantity of the second-half cooling header pattern to compensate a difference between the a target coiling temperature and a coiling temperature of the strip measured during the cooling control;
an intermediate temperature difference compensation unit (128) which calculates, as a control code modification quantity, a change quantity of the second-half cooling header pattern to compensate a difference between the target intermediate temperature and a temperature at the intermediate position of the strip measured during the cooling control;
a second-half cooling speed difference compensation unit (129) which calculates, as a control code modification quantity, a change quantity of the second-half cooling header pattern to compensate a difference between the strip speed assumed in the preset control and the strip speed measured during the cooling control; and
a second-half cooling operation quantity mixing unit (130) which mixes with each other outputs from coiling temperature difference correction unit, the intermediate temperature difference correction unit, and the second-half cooling speed difference
compensation unit for each position of the strip in a longitudinal direction thereof to calculate a control code modification quantity, the coiling temperature control apparatus comprising
a second-half cooling header pattern conversion unit (142) which recognizes a position of the strip in a longitudinal direction thereof just beneath each of the headers and which converts a result obtained through an operation into a second-half cooling header pattern to output the pattern to the cooling unit, the operation being conducted to correct the second-half cooling control codes, which are calculated by and are outputted from the second-half cooling control code calculation unit by establishing a correspondence to each position of the strip in a longitudinal direction thereof, by use of the control codes outputted from the second-half cooling dynamic control unit.
9. A coiling temperature control apparatus according to claim 4, wherein:
the first-half cooling dynamic control unit comprises a first influence coefficient table (1001) storing therein an influence of a change in the control codes upon the intermediate temperature, a second influence coefficient table (1002) storing therein an influence of a change in the mill delivery temperature upon the intermediate temperature, and a third influence coefficient table (1003) storing therein an
influence of a change in the strip speed upon the intermediate temperature;
the intermediate temperature difference compensation unit calculates the modification quantity of the first-half cooling control codes based on the difference between the target intermediate temperature and the intermediate temperature of the strip measured during the cooling control and a coefficient obtained from the first influence coefficient table;
the before-cooling temperature difference compensation unit calculates a modification quantity of the first-half cooling control code based on the difference between the mill delivery temperature of the strip assumed in the preset control and the mill delivery temperature of the strip measured during the cooling control, a coefficient obtained from the first influence coefficient table, and a coefficient obtained from the second influence coefficient table; and
the first-half cooling speed difference compensation unit calculates a modification quantity of the first-half cooling control codes based on the difference between the strip speed assumed in the preset control and the strip speed during the cooling control, a coefficient obtained from the first influence coefficient table, and a coefficient obtained from the third influence coefficient table. 10. A coiling temperature control apparatus according to claim 4, wherein:
the second-half cooling dynamic control unit comprises a fourth influence coefficient table (1801) storing therein an influence of a change in the control codes upon the coiling temperature, a fifth influence coefficient table (1802) storing therein an influence of a change in the intermediate temperature with respect to the target intermediate temperature upon the coiling temperature, and a sixth influence coefficient table (1803) storing therein an influence of a change in the strip speed upon the coiling temperature;
the coiling temperature difference correction unit calculates a modification quantity of the control codes based on the difference between the target coiling temperature and the coiling temperature of the strip detected during the cooling control, and a coefficient obtained from the fourth influence coefficient table;
the intermediate temperature difference compensation unit calculates the modification quantity of the control codes based on the difference between the before-cooling temperature assumed in the preset control and the before-cooling temperature of the strip detected during the cooling control, a coefficient obtained from the fourth influence coefficient table, and a coefficient obtained from the fifth influence coefficient table; and
the second-half cooling speed difference
compensation unit calculates a modification quantity of the control codes based on the difference between the strip speed assumed in the preset control and the strip speed during the cooling control, a coefficient obtained from the fourth influence coefficient table, and a coefficient obtained from the fifth influence coefficient table.
11. A coiling temperature control apparatus
according to claim 4, comprising:
an intermediate temperature keeping time calculation unit (2701) which identifies an air-cooling range near the intermediate position based on the first-half cooling header pattern and the second-half cooling header pattern outputted from the preset control unit to calculate a period of time in which the strip is kept at the intermediate temperature, based on the identified air-cooling range and the strip speed; and
a speed pattern change unit (2702) which executes processing to lower a maximum speed of the strip if the calculated intermediate temperature keeping time does not satisfy a predetermined required keeping time.
12. A coiling temperature control apparatus
according to claim 4, comprising a stabilized control
unit (3001) which obtains the change quantity of the
first-half cooling header pattern calculated by the
first cooling dynamic control unit and which stabilizes
the output from the second-half cooling dynamic control unit by setting a dead zone to the change quantity of the intermediate temperature during a period of time from timing when the correction quantity of the first-half cooling control codes is changed to an end point of a period of time in which the first-half cooling dynamic control unit cannot suppress the intermediate temperature change due to a response delay of the cooling header.
13. A coiling temperature control apparatus according to claim 4, comprising a stabilized control unit (3001) which obtains the correction quantity of the first-half cooling control codes calculated by the first cooling dynamic control unit and which stabilizes the output from the second-half cooling dynamic control unit by setting a dead zone to the change quantity of the intermediate temperature during a period of time from timing when the correction quantity of the first-half cooling control codes is changed to an end point of a period of time in which the first-half cooling dynamic control unit cannot control the intermediate temperature change due to a response delay of the cooling header.
14. A coiling temperature control method which cools a strip rolled by a hot rolling mill by a cooling unit disposed on a delivery side of the mill to control a coiling temperature of the strip before the strip is coiled by a down coiler as well as a strip temperature
of the strip when the strip passes a beforehand determined intermediate position of the cooling unit to predetermined target temperatures, comprising:
predicting an intermediate temperature of the strip based on information to determine a first-half cooling header pattern as a combination of open/close of cooling headers disposed in a cooling unit between the mill and the intermediate position, predicting the coiling temperature of the strip based on information of a second-half cooling header pattern as a combination of open/close of cooling headers disposed in a cooling unit between the intermediate position and the down coiler, and determining, using results of the prediction, the first-half cooling header pattern to realize the target intermediate temperature and the second-half cooling header pattern to realize the target coiling temperature;
observing a state of the strip during the cooling control;
correcting the first-half cooling header pattern to remove a difference between the target intermediate temperature and an intermediate temperature of the strip detected during the cooling control, correcting the first-half cooling header pattern to compensate a difference between the strip temperature on the mill delivery side assumed in the preset control and the strip temperature measured on the strip, and correcting the first-half cooling header

pattern to compensate an influence, upon the intermediate temperature, of a difference between the strip speed assumed in the preset control and an actual strip speed;
correcting the second-half cooling header pattern to remove a difference between the target coiling temperature and a coiling temperature of the strip detected during the cooling control, correcting the second-half cooling header pattern to compensate an influence, upon the coiling temperature, of a difference between the target value of the intermediate temperature of the strip and an intermediate temperature of the strip measured on the strip, and correcting the second-half cooling header pattern to compensate an influence, upon the coiling temperature, of a difference between the strip speed assumed in the preset control and an actual strip speed. 15. A coiling temperature control method according to claim 14, comprising:
assigning respectively priority levels of opening sequence to first-half cooling headers disposed in a cooling unit between a hot rolling mill and the intermediate position and priority levels of opening sequence to second-half cooling headers disposed in a cooling unit between the intermediate position and the down coiler;
establishing a correspondence between a first-half cooling header pattern as a combination of
open/close of the first-half cooling headers and first-half control control codes created using information of the priority levels assigned to the first-half cooling headers, predicting an intermediate temperature of the strip using a strip temperature prediction model based on the first-half control control codes and information regarding the speed of the strip, and determining, using results of the prediction, the first-half cooling control codes to realize the target intermediate temperature;
establishing a correspondence between a second-half cooling header pattern as a combination of open/close of the second-half cooling headers and second-half control control codes created using information of the priority levels assigned to the second-half cooling headers, predicting a coiling temperature of the strip using a strip temperature prediction model based on the second-half control control codes and information regarding the speed of the strip, and determining, using results of the prediction, the second-half cooling control codes to realize the target coiling temperature; and
during the cooling control,
calculating, as a correction quantity of the first-half cooling control codes, open/close of headers to remove the difference between the target intermediate temperature and the intermediate temperature detected on the strip, calculating, as a
correction quantity of the first-half cooling control codes, open/close of headers to compensate the difference between the strip temperature on the mill delivery side assumed in the preset control and the strip temperature measured on the strip, and calculating, as a correction quantity of the first-half cooling control codes, open/close of headers to compensate an influence, upon the intermediate temperature, of a difference between the strip speed assumed in the preset control and an actual strip speed;
calculating, as a correction quantity of the second-half cooling control codes, open/close of headers to remove a difference between the target coiling temperature and a coiling temperature of the strip detected during the cooling control, calculating, as a correction quantity of the second-half cooling control codes, open/close of headers to compensate an influence, upon the coiling temperature, of a difference between the target value of the intermediate temperature of the strip and an intermediate temperature of the strip measured on the strip, and calculating, as a correction quantity of the second-half cooling control codes, open/close of headers to compensate an influence, upon the coiling temperature, of a difference between the strip speed assumed in the preset control and an actual strip speed; and
converting, into a first-half cooling header
pattern, a value obtained by correcting, based on a total of the correction quantities of the first-half cooling control codes thus calculated, the first-half cooling control codes determined before the cooling control of the strip and outputting the pattern to the cooling unit, and converting, into a second-half cooling header pattern, a value obtained by correcting, based on a total of the correction quantities of the second-half cooling control codes thus calculated, the second-half cooling control codes and outputting the pattern to the cooling unit.
16. A coiling temperature control method which cools a strip rolled by a hot rolling mill by a cooling unit disposed on a delivery side of the mill to control a coiling temperature of the strip before the strip is coiled by a down coiler as well as a strip temperature of the strip when the strip passes a beforehand determined intermediate position of the cooling unit to predetermined target temperatures, comprising:
before the cooling control of the strip, predicting an intermediate temperature of the strip based on information to determine a first-half cooling header pattern as a combination of open/close of cooling headers disposed in a cooling unit between the mill and the intermediate position, predicting the coiling temperature of the strip based on information of a second-half cooling header pattern as a combination of open/close of cooling headers disposed
in a cooling unit between the intermediate position and the down coiler, and calculating, using results of the prediction, the first-half cooling header pattern to realize the target intermediate temperature and the second-half cooling header pattern to realize the target coiling temperature; and
during the cooling control, measuring a temperature of the strip at the intermediate position to calculate a difference between the temperature and the target intermediate temperature, correcting the first-half cooling header pattern to remove the difference, and correcting the second-half cooling header pattern to remove an influence of the difference upon the coiling temperature.
17. A coiling temperature control method according to claim 14, comprising:
determining header patterns to realize the target intermediate temperature and the target coiling temperature, identifying an air-cooling range near the intermediate position based on the header patterns thus determined, making a check to determine whether or not an intermediate temperature keeping time satisfies a required keeping time; lowering, if the intermediate temperature keeping time does not satisfy the required keeping time, a maximum speed of the strip and determining again header patterns to realize the target intermediate temperature and the target coiling temperature; making a check to determine, based on the
header patterns again determined, whether or not the intermediate temperature keeping time satisfies the required keeping time; lowering, if the intermediate temperature keeping time does not satisfy the required keeping time, the maximum speed of the strip and determining again header patterns to realize the target intermediate temperature and the target coiling temperature; and repeatedly conducting this operation until the intermediate temperature keeping time satisfies the required keeping time.
18. A coiling temperature control method which cools a strip rolled by a hot rolling mill by a cooling unit disposed on a delivery side of the mill to control a coiling temperature of the strip before the strip is coiled by a down coiler as well as a strip temperature of the strip when the strip passes a beforehand determined intermediate position of the cooling unit to predetermined target temperatures, comprising:
before the control of the strip, predicting an intermediate temperature of the strip at the intermediate position using a strip temperature prediction model based on a header pattern as a combination of open/close of cooling headers, information regarding a speed of the strip, and a prediction value of the strip temperature on the mill delivery side; and determining, based on results of the prediction, a first-half cooling header pattern to realize the target intermediate temperature; and adjusting the prediction value of the intermediate temperature to the target intermediate temperature, predicting a coiling temperature of the strip using a strip temperature prediction model based on the header pattern, the information regarding the speed of the strip, and the prediction value of the intermediate temperature; and determining, based on results of the prediction, a second-half cooling header pattern to realize a target coiling temperature. 19. A coiling temperature control method according to claim 18, comprising recognizing, by obtaining the first-half cooling header pattern, that the first-half cooling header pattern has been corrected; setting a dead zone to a change guantity of the measured intermediate temperature during a period from the correction timing to an end point of a period of time in which the intermediate temperature change cannot be suppressed due to a response delay of the cooling header; and releasing the dead zone after the intermediate temperature change is suppressed due to the correction of the first-half cooling header pattern.