1. A coiling temperature control apparatus (100) for cooling a rolled strip (151) rolled by a hot rolling mill (152) by using a cooling device (153) set up on an exit side of said hot rolling mill (152), and controlling coiling temperature of said rolled strip (151) into a predetermined target coiling temperature before said rolled strip (151) is coiled by a down coiler (154), comprising: cooling headers priority order calculation means (114) for calculating and outputting a priority relationship among opening sequences of cooling headers (160) set up in said cooling device (153), so that cooling speed of said rolled strip (151) in the course of being cooled satisfies a predetermined target cooling speed,; cooling headers priority order memory means (115) for storing said priority order for each cooling header (160) outputted by said cooling headers priority order calculation means (114); and control command calculation means (111) for predicting said coiling temperature of said rolled strip (151) based on said target coiling temperature, information on speed of said rolled strip (151), and information stored in said cooling headers priority order memory means (115), and by using a strip temperature prediction model (117) for predicting said coiling temperature of said rolled strip (151), and calculating and outputting a header pattern for accomplishing said target coiling temperature by using said prediction result of said coiling temperature, the header pattern being a combination of open/close of each cooling header (160) .

2. A coiling temperature control apparatus (100) for cooling a rolled strip (151) rolled by a hot rolling mill (152) by using a cooling device (153) set up on an exit side of said hot rolling mill (152), and controlling coiling temperature of said rolled strip (151) into a predetermined target coiling temperature before said rolled strip (151) is coiled by a down coiler (154), comprising: cooling headers priority order calculation means (114) for calculating and outputting a priority relationship among opening sequences of cooling headers (160) set up in said cooling device (153), so that cooling speed of said rolled strip (151) in the course of being cooled satisfies a predetermined target cooling speed,; cooling headers priority order memory means (115) for storing said priority order for each cooling header (160) outputted by said cooling headers priority order calculation means (114); control command calculation means (111) for generating a control code by using information stored in said cooling headers priority order memory means (115), said control code corresponding to each header pattern which is a combination of open/close of each cooling header (160), predicting said coiling temperature of said rolled strip (151) based on said target coiling temperature and information on speed of said rolled strip (151), and using a strip temperature prediction model (117) for predicting said coiling temperature of said rolled strip (151), and calculating and outputting said control code for accomplishing said target coiling temperature by using said prediction result of said coiling temperature; and header pattern conversion means (130) for converting said control code to each header pattern, and outputting each header pattern to said cooling device (153), said control code being outputted by said control command calculation means (111) by using information stored into said cooling headers priority order memory means (115) .

3. The coiling temperature control apparatus (100) according to Claim 2, wherein said control code for a state where all of said cooling headers (160) are opened is defined as being its maximum value, and meanwhile, said control code for a state where all of said cooling headers (160) are closed is defined as being its minimum value, said prediction value of said coiling temperature being caused to correspond to said control code such that said prediction value decreases monotonously in accompaniment with an increase in numerical size of said control code.

4. The coiling temperature control apparatus (100) according to Claim 2, wherein said control code for a state where all of said cooling headers (160) are opened is defined as being its minimum value, and meanwhile, said control code for a state where all of said cooling headers (160) are closed is defined as being its maximum value, said prediction value of said coiling temperature being caused to correspond to said control code such that said prediction value increases monotonously in accompaniment with an increase in numerical size of said control code.

5. The coiling temperature control apparatus (100) according to Claim 1, wherein said cooling headers priority order calculation means (114) calculates a temperature drop amount of said rolled strip (151) in said cooling device (153) from a temperature of said rolled strip (151) at the time of entering said cooling device (153) and said target coiling temperature of said rolled strip (151) before being coiled by said down coiler (154), calculates a time from said temperature drop amount and said target cooling speed of said rolled strip (151), said time being needed for said cooling, calculates a distance from information on said time and said speed of said rolled strip (151), said distance being needed for said water cooling, said time being needed for said cooling, classifies and identifies, based on said distance, said cooling headers (160) into a cooling headers (160) group having a possibility of being opened, and a cooling headers (160) group having no possibility of being opened, and allocates said priority order to said cooling headers (160) group having said possibility of being opened, so that said cooling speed of said rolled strip (151) becomes equal to a substantially constant value.

6. The coiling temperature control apparatus (100) according to Claim 1, wherein, when a speed at which said rolled strip (151) is rolled, or a speed at which said rolled strip (151) is coiled by said down coiler (154) changes, said cooling headers priority order calculation means (114) performs said computation in a manner of being caused to correspond to said speed of said rolled strip (151), said computation being intended for allocating said priority order to each cooling header (160), and outputs said priority order for each cooling header (160) to said cooling headers priority order memory means (115), said priority order being caused to correspond to said speed of said rolled strip (151).

7. The coiling temperature control apparatus (100) according to Claim 2, wherein said control command calculation means (111) calculates and outputs said control code in a manner of being caused to correspond to each location of said rolled strip (151) in its longitudinal direction, and said header pattern conversion means (130) extracts said control code corresponding to a location of said rolled strip (151) after having recognized said location in advance, said location being positioned directly below each cooling header (160) in said longitudinal direction, extracts a cooling headers (160) priority order from said cooling headers priority order memory means (115), said cooling headers (160) priority order corresponding to a present speed of said rolled strip (151), and converts said control code to each header pattern in accordance with said cooling headers (160) priority order extracted, and outputs each header pattern to said cooling device (153). 8. The coiling temperature control apparatus (100) according to Claim 2, wherein said control command calculation means (111), after having calculated said control command, judges whether or not said target coiling temperature and said target cooling speed are satisfied under said control command calculated, and, if whatever of said target coiling temperature and said target cooling speed is not satisfied, changes said speed of said rolled strip (151) then to calculate said control command once again, and repeats said change and said calculation until both said target coiling temperature and said target cooling speed are satisfied.

9. The coiling temperature control apparatus (100) according to Claim 1, wherein said control command calculation means (111), after having calculated said control command, performs in advance a processing of judging whether or not said target coiling temperature and said target cooling speed are satisfied under said control command calculated, raising said speed of said rolled strip (151) if said coiling temperature is lower than said target coiling temperature, lowering said speed of said rolled strip (151) if said coiling temperature is higher than said target coiling temperature, and lowering said speed of said rolled strip (151) if said cooling speed is slower than said target cooling speed, and after said processing, calculates said control command once again, and repeats said processing and said calculation until both said target coiling temperature and said target cooling speed are satisfied.

10. A coiling temperature control method for cooling a rolled strip (151) rolled by said hot rolling mill (152) by using a cooling device (153) set up on an exit side of a hot rolling mill (152), and controlling coiling temperature of said rolled strip (151) into a predetermined target coiling temperature before being coiled by a down coiler (154), comprising the steps of: allocating a priority order to opening sequences of cooling headers (160) set up in said cooling device (153), so that cooling speed of said rolled strip (151) satisfies a predetermined target cooling speed; generating a control code by using said priority order, said control code corresponding to each header pattern which is a combination of open/close of each cooling header (160) ; predicting said coiling temperature of said rolled strip (151) based on said control code and information on speed of said rolled strip (151), and by using a strip temperature prediction model; determining and outputting said control code for accomplishing said target coiling temperature by using said prediction result of said coiling temperature; and converting said control code to each header pattern, and outputting each header pattern to said cooling device (153).

11. The coiling temperature control method according to Claim 10, further comprising the steps of: calculating a temperature drop amount of said rolled strip (151) in said cooling device (153) based on a temperature of said rolled strip (151) at the time of entering said cooling device (153) and said target coiling temperature of said rolled strip (151) before being coiled by said down coiler (154); calculating a time from said temperature drop amount and said target cooling speed of said rolled strip (151), said time being needed for said cooling; calculating a distance based on information on said time and said speed of said rolled strip (151), said distance being needed for said water cooling, said time being needed for said cooling; classifying and identifying, based on said distance, said cooling headers (160) into a cooling headers (160) group having a possibility of being opened, and a cooling headers (160) group having no possibility of being opened; and allocating said priority order to said cooling headers (160) group having said possibility of being opened, so that said cooling speed of said rolled strip (151) becomes equal to a substantially constant value; generating said control code by using said priority order, said control code corresponding to each header pattern which is said combination of said open/close of each cooling header (160) ; predicting said coiling temperature of said rolled strip (151) based on said control code and said information on said speed of said rolled strip (151), and by using said strip temperature prediction model; determining and outputting said control code for accomplishing said target coiling temperature by using said prediction result of said coiling temperature; and converting said control code to each header pattern, and outputting each header pattern to said cooling device (153).

12. The coiling temperature control method according to Claim 10, further comprising the steps of: allocating said priority order for said opening sequences with respect to said cooling headers (160) in a manner of being caused to correspond to a speed at which said rolled strip (151) is rolled, or a speed at which said rolled strip (151) is coiled by said down coiler (154), said priority order allowing said cooling speed of said rolled strip (151) to satisfy said predetermined target cooling speed; generating said control code in a manner of being caused to correspond to each location of said rolled strip (151) in its longitudinal direction, said control code corresponding to each header pattern which is said combination of said open/close of each cooling header (160); predicting said coiling temperature of said rolled strip (151) based on said control code and said information on said speed of said rolled strip (151), and by using said strip temperature prediction model; determining and outputting said control code for accomplishing said target coiling temperature using said prediction result of said coiling temperature; extracting said control code corresponding to a location of said rolled strip (151) after having recognized said location in advance, said location being positioned directly below each cooling header (160) in said longitudinal direction; and converting said control code to each header pattern in accordance with a priority order, and outputting each header pattern to said cooling device (153), said priority order being allocated to each cooling header (160) and corresponding to a present speed of said rolled strip (151).

BACKGROUND OF THE INVENTION
The present invention relates to coiling temperature control on a hot rolling line. More particularly, it relates to a coiling temperature control apparatus and its control method for causing the coiling temperature to coincide with a target coiling temperature, and in addition, causing the cooling speed of a rolled strip such as a steel strip to coincide with a target cooling speed.
Conventionally, methods for executing the coiling temperature control have been disclosed in JP-A-2007-118027 (paragraphs 0025 to 0028, 0030, Fig. 4, and Fig. 4, etc.) and JP-A-9-216011 (paragraphs 0010 to 0013, and Fig. 1, etc.).
For example, in JP-A-2007-118027, the disclosure has been made concerning a coiling temperature control method of setting open/close patterns of cooling headers. In this method, priority order for the open/close patterns of the cooling headers for ejecting a cooling water of a cooling device and the like is summarized in advance onto a table, depending on the steel type, steel thickness, and the like. Then, the target coiling temperature is accomplished using the information on this priority order. Also, the disclosure has been made regarding a

methodology for simplifying the setting of the open/close patterns of the cooling headers by coding the cooling headers open/close patterns, i.e., by representing each cooling header open/close pattern with a control code corresponding thereto.
Also, as a conventional technology for controlling not only the coiling temperature but also cooling temperature pattern of the steel strip, in, e.g., JP-A-9-216011, the disclosure has been made concerning the following methodology: Namely, in this methodology, an intermediate temperature between a finishing rolling mill and a down coiler, and the coiling temperature in proximity to the down coiler are controlled with high accuracies implemented with respect to their target values, respectively.
SUMMARY OF THE INVENTION
By the way, it is known that metallurgical properties (such as, e.g., ferrite grain diameter of metallic crystal) and mechanical properties (such as, e.g., tensile strength and hardness) of a steel strip whose cooling is over depend significantly on the cooling speed (i.e., temperature drop per unit time) of the steel strip. In the conventional methodologies, however, the following problems exist from the viewpoint of controlling the cooling speed of the steel strip into a predetermined target value.
In JP-A-2007-118027, the setting of the

priority order for the open/close patterns of the cooling headers makes it possible to control the cooling speed of the steel strip indirectly. Namely, changing the setting of the cooling headers priority order allows the execution of the relative control over the steel-strip cooling speed, i.e., speeding up or slowing down the steel-strip cooling speed. Nevertheless, it is not clear in what manner the cooling headers priority order should be set with respect to a desired steel-strip cooling speed. This is because the cooling headers priority order and the steel-strip cooling speed are not in a direct correspondence relationship with each other, i.e., the cooling headers priority order and the steel-strip cooling speed are not made related with each other.
Also, since the cooling headers priority order is defined in the fixed manner, it is impossible to address a situation where, if the steel-strip speed changes, the steel-strip cooling speed will also change. Accordingly, there exists a drawback that it is impossible to execute the absolute control over the steel-strip cooling speed.
In the control method disclosed in JP-A-9-216011, it is possible to control not only the coiling temperature, but also the temperature at the intermediate position of the steel strip between the finishing rolling mill and the down coiler. As a result, it is possible to substantially control the

cooling temperature pattern of the steel strip via the intermediate temperature. Similarly, however, the steel-strip cooling speed will change if the steel-strip speed changes. This phenomenon occurs even if the cooling temperature pattern of the steel strip remains the same. For example, if the steel-strip speed becomes faster, the steel-strip cooling speed becomes slower. Meanwhile, if the steel-strip speed becomes slower, the steel-strip cooling speed becomes faster.
In the passing of the steel strip through the hot rolling line, the following change in the steel-strip speed is caused to occur artificially: Namely, after the steel strip is delivered from the finishing rolling mill at a low speed usually, the steel-strip speed is increased gradually. Then, after the steel-strip speed reaches its maximum speed, the steel-strip speed is decreased steeply at a stroke in order to suppress the tail end of the steel strip from fluttering. This is executed immediately before the steel-strip tail end passes through the finishing rolling mill.
In the control method disclosed in JP-A-9-216011 and controlling the intermediate temperature and the cooling temperature pattern of the steel strip, there exists a problem that the steel-strip cooling speed cannot be maintained at a constant value with respect to the change in the steel-strip speed like

this.
In view of the above-described circumstances, an object of the present invention is to provide a coiling temperature control apparatus and its control method for making it possible to control the coiling temperature of a rolled strip such as a steel strip into a target coiling temperature, and to control the cooling speed of the rolled strip into a desired value.
In order to accomplish the above-described object, according to one aspect of the present invention, there is provided a coiling temperature control apparatus for cooling a rolled strip using a cooling device set up on an exit side of a hot rolling mill, and controlling coiling temperature of the rolled strip into a predetermined target coiling temperature, the rolled strip having been rolled by the hot rolling mill, and being the rolled strip before being coiled by a down coiler, the coiling temperature control apparatus, including a cooling headers priority order calculation unit for calculating and outputting a priority relationship among opening sequences of a large number of cooling headers, so that cooling speed of the rolled strip in the course of being cooled will satisfy a target value for the cooling speed, the cooling headers being set up in the cooling device, a cooling headers priority order memory unit for storing the priority order for each cooling header outputted by the cooling headers priority order calculation unit,

and a control command calculation unit for predicting the coiling temperature of the rolled strip from the target coiling temperature, information on speed of the rolled strip, and the information stored into the cooling headers priority order memory unit, and using a strip temperature prediction model for predicting the coiling temperature of the rolled strip, and calculating and outputting each header pattern for accomplishing the target coiling temperature using the prediction result of the coiling temperature, each header pattern being a combination of the open/close of each cooling header.
According to another aspect of the present invention, there is provided a coiling temperature control apparatus for cooling a rolled strip using a cooling device set up on an exit side of a hot rolling mill, and controlling coiling temperature of the rolled strip into a predetermined target coiling temperature, the rolled strip having been rolled by the hot rolling mill, and being the rolled strip before being coiled by a down coiler, the coiling temperature control apparatus, including a cooling headers priority order calculation unit for calculating and outputting a priority relationship among opening sequences of a large number of cooling headers, so that cooling speed of the rolled strip in the course of being cooled will satisfy a target value for the cooling speed, the cooling headers being set up in the cooling device, a

cooling headers priority order memory unit for storing the priority order for each cooling header outputted by the cooling headers priority order calculation unit, a control command calculation unit for generating a control code using the information stored into the cooling headers priority order memory unit, the control code corresponding to each header pattern which is a combination of the open/close of each cooling header, predicting the coiling temperature of the rolled strip from the target coiling temperature and information on speed of the rolled strip, and using a strip temperature prediction model for predicting the coiling temperature of the rolled strip, and calculating and outputting the control code for accomplishing the target coiling temperature using the prediction result of the coiling temperature, and a header pattern conversion unit for converting the control code to each header pattern, and outputting each header pattern to the cooling device, the control code being outputted by the control command calculation unit using the information stored into the cooling headers priority order memory unit.
According to further aspect of the present invention, there is provided a coiling temperature control method for cooling a rolled strip using a cooling device set up on an exit side of a hot rolling mill, and controlling coiling temperature of the rolled strip into a predetermined target coiling temperature,

the rolled strip having been rolled by the hot rolling mill, and being the rolled strip before being coiled by a down coiler, the coiling temperature control method, including the steps of allocating a priority order to opening sequences of a large number of cooling headers, so that cooling speed of the rolled strip will satisfy a target value for the cooling speed, the cooling headers being set up in the cooling device, generating a control code using the priority order, the control code corresponding to each header pattern which is a combination of the open/close of each cooling header, predicting the coiling temperature of the rolled strip from the control code and information on speed of the rolled strip, and using a strip temperature prediction model, determining and outputting the control code for accomplishing the target coiling temperature using the prediction result of the coiling temperature, and converting the control code to each header pattern, and outputting each header pattern to the cooling device.
According to the present invention, it becomes possible to implement the coiling temperature control apparatus and its control method for making it possible to control the coiling temperature of a rolled strip such as a steel strip into a target coiling temperature, and to control the cooling speed of the rolled strip into a desired value.
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 conceptual diagram for illustrating a control system S including a coiling temperature control apparatus 100 and a control target 150 of a first embodiment according to the present invention;
Fig. 2 is a diagram for illustrating the configuration of a target cooling speed table of the first embodiment;
Fig. 3 is a diagram for illustrating the configuration of a speed pattern table of the first embodiment;
Fig. 4 is a diagram for illustrating the configuration of a target coiling temperature table of the first embodiment;
Fig. 5 is a flowchart for illustrating a processing executed by a cooling headers priority order calculation unit of the first embodiment;
Fig. 6 is an explanatory diagram for explaining a processing of allocating a priority order to cooling headers of the first embodiment;
Fig. 7 is a flowchart for illustrating the processing of allocating the priority order to the cooling headers of the first embodiment;
Fig. 8 is a diagram for illustrating the

configuration of a cooling headers priority order memory unit of the first embodiment;
Fig. 9 is a configuration diagram for illustrating a correspondence table between open/close patterns of the cooling headers of the first embodiment and control codes corresponding thereto;
Fig. 10 is a flowchart for illustrating a processing executed by a control command calculation unit of the first embodiment;
Fig. 11 is a flowchart for illustrating the details of a coiling temperature prediction computation processing of the first embodiment;
Fig. 12A and Fig. 12B are diagrams for illustrating an example at the time when the control codes allocated to respective locations of a steel strip of the first embodiment are varied by an optimization processing of the control command calculation unit;
Fig. 13 is a configuration diagram for illustrating a correspondence table between the locations of the steel strip and the control codes of the first embodiment;
Fig. 14 is a flowchart for illustrating a processing based on which the open/close of each cooling header is determined from each control code by a header pattern conversion unit of the first embodiment;
Fig. 15 is a flowchart for illustrating a

processing executed by a cooling headers priority order calculation unit of a second embodiment;
Fig. 16 is a diagram for illustrating the configuration of a cooling headers priority order memory unit to which the output is performed by the cooling headers priority order calculation unit of the second embodiment;
Fig. 17 is a flowchart for illustrating the details of a coiling temperature prediction computation processing executed by a control command calculation unit of the second embodiment;
Fig. 18 is a flowchart for illustrating a processing algorithm based on which the open/close of each cooling header is determined from each control code by a header pattern conversion unit of the second embodiment; and
Fig. 19 is a flowchart for illustrating a processing executed by a control command calculation unit of a second embodiment.
DESCRIPTION OF THE INVENTION
Hereinafter, referring to the accompanying drawings, the explanation will be given below concerning embodiments of the present invention.
Fig. 1 is a conceptual diagram for illustrating a control system S including a coiling temperature control apparatus 100 and a control target 150 of a first embodiment according to the present

invention.
«lst embodiment»

The control system S of the first embodiment controls the cooling speed of a rolled-strip steel strip 151 after being hot-rolled by a hot rolling mill 152, and the coiling temperature of the steel strip 151 in the course of being coiled by a down coiler 154. This control makes it possible to acquire uniform metallurgical properties and desired mechanical properties.
The coiling temperature control apparatus 100 in the control system S includes a cooling headers priority order calculation unit 114. The cooling headers priority order calculation unit 114 fetches a preset steel-strip target cooling speed of the after-hot-rolled steel strip 151, then calculating a necessary water cooling distance from this target cooling speed and a steel-strip (151) speed. Moreover, the calculation unit 114 opens, with the highest or higher priority, cooling headers 160 (160a, 160b) which are included within this necessary water cooling distance. Simultaneously, the calculation unit 114 allocates a priority order to each cooling header 160 so that the target cooling speed will be satisfied, then outputting this priority order to a cooling headers priority order memory unit 115.
Furthermore, a control command calculation

unit 111 included in the coiling temperature control apparatus 100 calculates a header pattern with respect to each location of the steel strip 151 in its longitudinal direction, while making reference to the contents (information) outputted by the cooling headers priority order calculation unit 114 and stored into the cooling headers priority order memory unit 115. Here, the header pattern is the open/close pattern of each cooling header 160 for accomplishing the target coiling temperature of the steel strip 151 in the course of being coiled by the down coiler 154.
As a result of the above-described set-up calculation, if either of the target coiling temperature/target cooling speed is not satisfied, the set-up calculation is executed once again in such a manner that the steel-strip (151) speed is increased/decreased.
In this way, at the coiling step for the after-hot-rolled steel strip 151, the cooling speed and the coiling temperature of the steel strip 151 can be controlled into the target values in its longitudinal direction. This feature makes it possible to acquire the uniform metallurgical properties (such as, e.g., ferrite grain diameter of metallic crystal) and the desired mechanical properties (such as, e.g., tensile strength and hardness).
Accordingly, it becomes possible to enhance composition quality of the steel strip 151 (rolled

product), and to acquire a steel-strip configuration which is close to a flat configuration.
Hereinafter, the detailed explanation will be given below concerning the control system S of the first embodiment.
The control system S illustrated in Fig. 1 includes the control target 150, and the coiling temperature control apparatus 100 for receiving various signals from the control target 150 and outputting the control signal to the control target 150. In the control target 150, the steel strip 151 after being hot-rolled by the hot rolling mill 152 is cooled by upper and lower cooling devices 158 and 159 of a strip cooling device 153. Moreover, the steel strip 151 cooled is coiled by the down coiler 154.
The control target 150 in the control system S is a coiling temperature control line of the after-hot-rolled steel strip 151. Namely, the steel strip 151, whose temperature is made equal to about 900°C after it is hot-rolled by a mill 157 of the hot rolling mill 152, is cooled down to about 600°C by the strip cooling device 153. Moreover, the steel strip 151 cooled down is coiled by the down coiler 154.
The strip cooling device 153 includes the upper cooling device 158 for water cooling the steel strip 151 by showering water w over the steel strip 151

from the upper side thereof, and the lower cooling device 159 for water cooling the steel strip 151 by showering water w over the steel strip 151 from the lower side thereof.
Each of the upper and lower cooling devices 158 and 159 includes a plurality of water cooling banks 161. Each water cooling bank 161 is configured such that the cooling headers 160 (i.e., upper cooling headers 160a and lower cooling headers 160b), each of which ejects water, are combined with each other in a constant number. In the present first embodiment, the explanation will be given selecting an example where operation commands for each cooling header 160 are "open" and "close".
A mill-delivery pyrometer 155 set up directly after the mill 157 of the hot rolling mill 152 measures the temperature of the steel strip 151 immediately after being hot-rolled by the hot rolling mill 152. Meanwhile, a coiling pyrometer 156 set up directly before the down coiler 154 measures the temperature of the steel strip 151 immediately before being coiled by the down coiler 154.
Here, an object of the coiling temperature control is to cause the temperature of the steel strip 151 immediately before being coiled by the down coiler 154, which is measured by the coiling pyrometer 156, to coincide with the target temperature (i.e., target coiling temperature). This target temperature (target

coiling temperature) may also be set as being a constant value at each location of the steel strip 151 in its longitudinal direction. Otherwise, a different value can also be set depending on each location, such that the target temperatures at the front-end and tail-end of the steel strip 151 are set at somewhat higher values. This is performed as a result of considering the winding property and the coiling property of the steel strip 151 around the down coiler 154.
For example, the front-end of the steel strip 151 becomes a core of the winding of the steel strip 151 around the down coiler 154. Accordingly, the front-end is required to be wound neatly. In view of this requirement, for example, the target temperature is set at 640°C, which is a somewhat higher value as compared with 600°C in the stationary state. This is because the winding property becomes better as the steel strip 151 becomes softer.
The coiling temperature control apparatus 100 illustrated in Fig. 1 includes a set-up control unit 110. Before the after-hot-rolled steel strip 151 is cooled down by the strip cooling device 153, the set-up control unit 110 calculates and outputs a control code corresponding to the open/close pattern of each cooling header 160, and the priority order for the open/close of each cooling header 160. Incidentally, referring to Fig. 9, the detailed explanation will be given later

regarding the control code.
Also, the coiling temperature control apparatus 100 includes a dynamic control unit 120, and a header pattern conversion unit 130 for converting the control code to the open/close pattern of each cooling header 160. While the steel strip 151 is being cooled down by the strip cooling device 153, the dynamic control unit 120 changes the control code by fetching, in real time, the achievements such as the detection temperature detected by the coiling pyrometer 156.
Incidentally, hereinafter, a set of the open/close patterns indicating the open/close states of each cooling header 160 will be referred to as "header patterns".
Here, the set-up control unit 110, the dynamic control unit 120, and the header pattern conversion unit 130 in the coiling temperature control apparatus 100 (refer to Fig. 1) are described using, e.g., C language or the like, are stored into a process computer, and are embodied by being executed by its CPU (Central Processing Unit).
Incidentally, the implementation method for the set-up control unit 110, the dynamic control unit 120, and the header pattern conversion unit 130 is not limited to this implementation method, of course.
Moreover, the control target 150 is controlled by this process computer via a PLC (Programmable Logic Controller).

The set-up control unit 110 includes the cooling headers priority order calculation unit 114 and the control command calculation unit 111.
The cooling headers priority order calculation unit 114 fetches contents of a target cooling speed table 112 and a speed pattern table 113, thereby calculating the priority order in accordance which the cooling headers 160 will be opened during the cooling of the steel strip 151.
The control command calculation unit 111 performs the computation using a strip temperature prediction model 117, thereby calculating the above-described header patterns as the control codes. At this time, the calculation unit 111 fetches the information from the cooling headers priority order memory unit 115 for storing the priority order for the cooling headers 160 outputted by the cooling headers priority order calculation unit 114, a target coiling temperature table 116, the target cooling speed table 112, and the speed pattern table 113.
The dynamic control unit 120 includes a strip temperature deviation correction unit 121, a mill-delivery-temperature deviation correction unit 122, and a speed deviation correction unit 123. Using the detection temperature detected by the coiling pyrometer 156, the trip temperature deviation correction unit 121

changes the control code into a direction which allows a reduction in the deviation between this detection temperature and the target temperature (i.e., target coiling temperature). Using the detection temperature detected by the mill-delivery pyrometer 155, the mill-delivery-temperature deviation correction unit 122 changes the control code into a direction which allows a compensation for the deviation between this detection temperature and the mill-delivery-temperature assumed at the time of the set-up control computation. Calculating the steel-strip (151) speed from rotation speeds of the mill 157 and the down coiler 154, the speed deviation correction unit 123 changes the control code into a direction which allows a reduction in the influence exerted onto the coiling temperature by the deviation between this calculation result and the steel-strip (151) speed assumed at the time of the setup control computation.
Fig. 2 is a diagram for illustrating the configuration of the target cooling speed table 112 (refer to Fig. 1).
The target cooling speed table 112 illustrated in Fig. 2 stores therein the target cooling speeds, i.e., optimum cooling speeds corresponding to respective steel types.
Making reference to the target cooling speed table 112 in accordance with the respective steel types

shows the following optimum operations, for example: The control should be executed such that the rolled steel strip 151 is caused to pass through the cooling device 153 (refer to Fig. 1) with the target cooling speed of 30°C/s (second) in the case of SUS 304 which is a stainless strip, and the target cooling speed of 51°C/s (second) in the case of SS 400 which is a low-carbon steel.
Fig. 3 is a diagram for illustrating the configuration of the speed pattern table 113 (refer to Fig. 1) .
Fig. 3 illustrates an example of the speed pattern in the case of a tandem mill where a plurality of rolling mills 152 are set up.
The speed pattern table 113 accumulates therein the following data on each clustering basis: With respect to the steel type, strip thickness, and strip width of the rolled steel strip 151, a speed (initial speed) at the time when the front-end of the after-hot-rolled steel strip 151 is delivered out of the mill 157 (refer to Fig. 1), after that, an acceleration (first acceleration) until the front-end of the steel strip 151 is coiled by the down coiler 154, after that, an acceleration (second acceleration) until the speed reaches its maximum speed, the maximum speed, a deceleration (negative acceleration) at the time when the speed is decreased from the maximum speed

to a terminal speed at which the tail-end of the after-hot-rolled steel strip 151 is delivered out of the mill 157, and the terminal speed.
The control command calculation unit 111 illustrated in Fig. 1 judges the steel type, strip thickness, and strip width of the coil (steel strip 151), thereby extracting the corresponding speed pattern from the speed pattern table 113.
For example, the speed pattern table 113 shows that, when the steel type is SUS 304, the strip thickness is equal to 2.0 to 3.0 mm, and the strip width is equal to 1200 mm, the 650 mpm (meter/minute) initial speed, 2 mpm/s (second) first acceleration, 12 mpm/s second acceleration, 1050 mpm maximum speed (stationary speed), 6 mpm/s deceleration, and 900 mpm terminal speed are set.
Fig. 4 is a diagram for illustrating the configuration of the target coiling temperature table 116 (refer to Fig. 1).
Fig. 4 illustrates an example where the target coiling temperatures are accumulated on each clustering basis in correspondence with the types (steel types) of the steel strip 151.
The target coiling temperature table 116 stores therein the target coiling temperatures which are the optimum target coiling temperatures at the time when the steel strip 151 is coiled by the down coiler

154 in correspondence with the types (steel types) of the steel strip 151.
The set-up control unit 110 illustrated in Fig. 1 judges the steel type of the coil (steel strip 151), thereby extracting the corresponding target coiling temperature from the target coiling temperature table 116.

Next, in accordance with Fig. 5, the explanation will be given below concerning the processing executed by the cooling headers priority order calculation unit 114 (refer to Fig. 1).
Incidentally, Fig. 5 is a flowchart for illustrating the processing executed by the cooling headers priority order calculation unit 114.
In the present embodiment, the illustration will be given to an example where the header pattern is determined so that the steel strip 151 will satisfy its target cooling speed at the time of its maximum speed.
First, at S51 in Fig. 5, based on the steel type of the steel strip 151 to be rolled, the cooling headers priority order calculation unit 114 fetches the target cooling speed from the target cooling speed table 112 (refer to Fig. 2 and Fig. 1). Simultaneously, based on the steel type, strip thickness, and strip width of the steel strip 151 to be rolled, the calculation unit 114 fetches the speed

pattern of the steel strip 151 from the speed pattern table 113 (refer to Fig. 3 and Fig. 1).
Subsequently, at S52 in Fig. 5, the calculation unit 114 calculates a cooling time tn (s (second)) for the after-rolled steel strip 151.
The cooling time tn (s) is calculated using, e.g., the following Expression (1), and from the data such as the mill-delivery-temperature Tm (°C) assumed at the time of the set-up computation (i.e., the temperature detected by the mill-delivery pyrometer 155 (refer to Fig. 1)), the target value Tc (°C) for the coiling temperature (i.e., the temperature detected by the coiling pyrometer 156 (refer to Fig. 1)), and the target cooling speed Tv (°C/s (second)):
tn = (Tm - Tc) /Tv (1)
When the steel type is SUS 304, the strip thickness is equal to 2.5 mm, the strip width is equal to 1200 mm, and the mill-delivery-temperature assumed value Tm is equal to 880°C, the target coiling temperature Tc becomes equal to 7 50°C from the target coiling temperature table 116 (Fig. 4). As a result, from the Expression (1), the cooling time tn (s) is calculated as follows:
(cooling time) tn = (880 - 750)/30 = 4.3 s.
Subsequently, at S53 in Fig. 5, the calculation unit 114 calculates the necessary water cooling distance Lw (m) using the maximum speed Vmax (mpm (meter/minute)), thereby identifying the water

cooling banks 161 and the cooling headers 160 which are included within this necessary water cooling distance Lw.
The necessary water cooling distance Lw is calculated using, e.g., the following Expression (2):
Lw = (Vmax x tn)/60 (2)
Incidentally, here, since the maximum speed Vmax is of the minute unit, the second unit of the cooling time tn is converted into the minute unit.
In the above-described example, Lw is calculated as follows:
Lw = (1050 x 4.3)/60 = 75.25 m
Consequently, the water cooling banks 161 included within the necessary water cooling distance Lw of 75.25 m from the water cooling bank 161 at the exit of the strip cooling device 153 (refer to Fig. 1) (i.e., the water cooling bank 161 nearest to the rolling mill 152), and the cooling headers 160 corresponding to these water cooling banks 161 turn out to become the identified water cooling banks 161 and cooling headers 160.
Finally, at S54 in Fig. 5, the calculation unit 114 calculates the priority order for the cooling headers 160 using a methodology illustrated in Fig. 6 and Fig. 7 (which will be described later), then outputting the priority order to the cooling headers priority order memory unit 115 (refer to Fig. 1).
Next, referring to Fig. 6 and Fig. 7, the explanation will be given below concerning the processing of allocating the priority order to the cooling headers 160 (i.e., S54 in Fig. 5), which is executed by the cooling headers priority order calculation unit 114 (refer to Fig. 1) .
Incidentally, Fig. 6 is an explanatory diagram for explaining the processing of allocating the priority order to the cooling headers 160 (refer to Fig. 7). Fig. 7 is a flowchart for illustrating the processing of allocating the priority order to the cooling headers 160 (1 to n) (refer to Fig. 6) .
Referring to Fig. 6, the explanation will be given below regarding the basic concept of the calculation method for the cooling headers priority order.
As illustrated in Fig. 6, the steel strip 151 is cooled down to the target cooling speed within the necessary water cooling distance Lw. Accordingly, a group of the n units of cooling headers 160 included within the necessary water cooling distance Lw has a possibility of being switched into the "open" state.
Here, for convenience, the water cooling banks 161 are neglected, and numbers 1 to n are allocated to the cooling headers 160 themselves sequentially from the exit side of the mill 157.

Moreover, of them all, the priority order is allocated to the cooling headers 160 in a necessary number, so that they are switched into the "open" state with an equal possible spacing implementable, and so that the quality of the steel strip 151 becomes equivalent and uniform.
Hereinafter, referring to Fig. 7, the explanation will be given below concerning the processing of allocating the priority order to the cooling headers 160 (1 to n) illustrated in Fig. 6.
First, at S71 in Fig. 7, the cooling headers priority order calculation unit 114 allocates a priority order 1 to the cooling header 1, allocates a priority order 2 to the cooling header n, and further, allocates a priority order 3 to the cooling header (1/2)xn. Incidentally, this processing is a processing of m = 1.
Furthermore, after this processing of m = 1, the unit 114 sets m at 2, i.e., sets m = 2.
Subsequently, at S72 in Fig. 7, the unit 114 creates a priority order progression with 2m set as its denominator.
Since the denominator is 4 because of m = 2, the unit 114 allocates priority orders 4 and 5 to the cooling headers (1/4)xn and (3/4)xn, excluding the cooling headers 1, (2/4)xn, and (4/4)xn to which the priority orders have been already allocated.
Subsequently, at S73 in Fig. 7, the unit 114

judges termination of the priority order progression creation processing.
Namely, when 2m is not larger than n, the allocation of the priority orders with respect to all of the cooling headers has not been completed. Accordingly, the unit 114 judges whether or not n < 2m holds.
If 2m is not larger than n (i.e., No at S73 in Fig. 7), the unit 114 transfers to S74 in Fig. 7 to add 1 to m, then repeating the processings at S72 and S73 in Fig. 7.
As a result, the unit 114 acquires a priority order progression which complies with a binomial distribution of the following Expression (3):
(1, n, (l/2)n, (l/4)n, (3/4)n, (l/8)n,
(7/8)n, (3/8)n, (5/8)n, ... ) (3)
Subsequently, if, at S73 in Fig. 7, 2m is larger than n (i.e., Yes at S73 in Fig. 7), the unit 114 terminates the priority order progression creation processing, then transferring to S75 in Fig. 7.
At S75 in Fig. 7, the unit 114 performs a processing of converting each value of the priority order progression into an integer by rounding up or down the decimal point of each value, and excluding a value which is duplicated as a result of this integer conversion.
The unit 114 applies basically the same processing to the cooling headers 160 which are not

included within the necessary water cooling distance Lw after the cooling header n up to the down coiler 154 illustrated in Fig. 6. In this way, the unit 114 allocates the priority orders after (n + 1) to these cooling headers 160 so that the cooling headers 160 are switched into the "open" state with an equal possible spacing implementable.
In the present embodiment, the cooling speed at the time when the coiling temperature becomes equal to the target coiling temperature on the exit side of the cooling header n has been caused to correspond to and has been set at the target cooling speed. After that, however, the temperature of the steel strip 151 drops in the air cooling section up to the down coiler 154 as is illustrated in Fig. 6. Accordingly, under the control command of trying to satisfy the target value for the coiling temperature, the steel-strip temperature is caused to correspond to and is set at a temperature which is somewhat higher than the target coiling temperature on the exit side of the cooling header n.
Consequently, strictly speaking, the cooling speed becomes equal to a value which is somewhat slower than the target value (target cooling speed). In the present embodiment, however, in order to simplify the set-up computation, the cooling speed at the time when the coiling temperature becomes equal to the target coiling temperature on the exit side of the cooling

header n (refer to Fig. 6) will be dealt with as the target cooling speed.
Otherwise, high accuracy implementation of the cooling speed is made possible by adding a processing of correcting the temperature drop in the above-described air cooling section to the processing executed by the cooling headers priority order calculation unit 114 (refer to Fig. 1).
Also, in the present embodiment, as is illustrated in Fig. 6, the necessary water cooling distance Lw has been defined based on the group of the cooling headers 160 which are nearer to the rolling mill 152. The distance Lw, however, may also be defined based on the group of the cooling headers 160 which are nearer to the down coiler 154. Similarly, the necessary water cooling distance Lw can also be defined after excluding the cooling headers 160 nearer to the rolling mill 152 or the rolling mill 152 in a constant number.
Furthermore, the manner like this of defining the group of the cooling headers 160 included within the necessary water cooling distance Lw can also be switched by clustering the group on each clustering basis using the steel type such as SUS 304 and SS400 or the like.
Hereinafter, the explanation will be given below selecting as the example a case where the total

number of the cooling headers 160 is equal to 100.
Fig. 8 is a diagram for illustrating the configuration of the cooling headers priority order memory unit 115 into which the information outputted by the cooling headers priority order calculation unit 114 (refer to Fig. 1) is stored.
Fig. 8 illustrates the stored priority order information that, using the method illustrated in Fig. 6 and Fig. 7, the priority orders of 1 to 100 are allocated to the opening sequences of the 100 units of cooling headers 160. Namely, Fig. 8 illustrates the stored sequences of the cooling headers 160 which should be opened with the highest or higher priority,
The numbers are allocated to the cooling headers 160 sequentially from the side nearest to the mill 157 (refer to Fig. 1) in the anew manner. For example, (1, 1) indicates the first cooling header 160 of the first water cooling bank 161 nearest to the mill 157 (refer to Fig. 1). In the example illustrated in Fig. 8, the 100 units of cooling headers 160 are opened in the priority order ranging from (1, 1), (10, 10),
(5, 10), (3, 5), (8, 5), (2, 2), , (11, 9) to (11,
10) with the highest or higher priority.
In the present embodiment (the present invention), the header patterns are represented by the control codes corresponding thereto.
Fig. 9 illustrates a correspondence between

the control codes outputted by the set-up control unit 110 and the header (open/close) patterns. Incidentally, Fig. 9 is a configuration diagram for illustrating a correspondence table between the open/close patterns of the cooling headers and the control codes corresponding thereto.
In Fig. 9, the control code 0 indicates a header pattern that all of the cooling headers are opened, and the control code 100 indicates a header pattern that all of the cooling headers are closed.
Hereinafter, a header pattern that only the cooling header of the priority order 1 is opened is control-coded as being 99. Also, a header pattern that only the two cooling headers of the priority orders 1 and 2 are opened is control-coded as being 98.
The set-up control unit 110 outputs the control codes corresponding to the cooling headers open/close patterns like this to the header pattern conversion unit 130 (refer to Fig. 1).
Namely, the control code for the state where all of the cooling headers 160 are opened is set at 0, and the control code for the state where all of the cooling headers 160 are closed is set at 100.
Moreover, in correspondence with the contents in the cooling headers priority order memory unit 115, the control codes are allocated to the open/close patterns of the cooling headers 160 in the following manner: The control coded 99 is allocated to the state

where only (1, 1) is opened, the control coded 98 is allocated to the state where only (1, 1) and (10, 10) are opened, a control coded 97 is allocated to a state where only (1, 1), (10, 10), and (5, 10) are opened, and in this way, the control coded 0 is finally allocated to the state where all of the cooling headers 160 are opened.

Next, referring to Fig. 10, the explanation will be given below regarding the processing executed by the control command calculation unit 111 (refer to Fig. 1) .
Fig. 10 is a flowchart for illustrating the processing algorithm executed by the control command calculation unit 111.
First, at S101 in Fig. 10, the control command calculation unit 111 calculates a speed pattern ranging from the start of the delivery of the steel strip 151 out of the mill 157 (refer to Fig. 1) to the completion of the coiling of the steel strip 151 by the down coiler 154. The unit 111 makes this calculation by calculating a first acceleration start position SLls at the time of the delivery of the steel strip 151 out of the mill 157, a second acceleration start position SL2s, a stationary speed start position SLcs, and a deceleration start position SLds for transferring the steel strip 151 from the stationary speed to the

terminal speed on the basis of the values fetched from the speed pattern table 113 (refer to Fig. 3) and clustered on each clustering basis in correspondence with the steel type of the steel strip 151.
Here, the first acceleration start position SLls, the second acceleration start position SL2s, the stationary speed start position SLcs, the deceleration start position SLds, and a deceleration completion position SLde can be calculated using the following Expressions (4) to (8), respectively:
(first acceleration start position) SLls = Lsc
(4)
, where Lsc: constant.
Lsc is determined appropriately by taking the following conditions into considerations:
For example, if the initial pass-through speed is fast, the front-end of the steel strip 151 may not be normally engaged into the mill 157, and thus an engagement failure may occur. Meanwhile, if the initial pass-through speed is slow, the productivity will not enhance. Otherwise, if the steel strip 151 is a thick strip, the initial pass-through speed is not fast, and thus the steel strip 151 may be accelerated somewhat earlier. Meanwhile, if the steel strip 151 is a thin strip, the initial pass-through speed is fast, and thus the steel strip 151 may be accelerated somewhat later.

(second acceleration start position) SL2s = Lmd
(5)
, where Lmd: the distance from the mill 157 to the down coiler 154.
(V1a)2 = Lmd x 2 x Accl + Vmax x Vmax (stationary speed start position) SLcs = {Lmd + (Vmax - V1a)/Acc2 x (Vmax +
Vla)/2} (6)
, where V1a: first acceleration termination speed, Accl: first acceleration, Acc2: second acceleration, Vmax: maximum speed.
(deceleration start position) SLds = {Striplen - (Vmax - Vf)/Dcc x
(Vmax + Vf)/2 - dccmargin} (7)
, where Striplen: steel-strip length, Vf: terminal speed, Dec: deceleration speed, dccmargin: margin indicating about how much margin remains when the deceleration of the steel strip 151 has been completed before the tail-end delivery of the steel strip 151 out of the mill 157 (refer to Fig. 1).
(deceleration completion position) SLde =
{Striplen - dccmargin} (8)
At S102 or thereinafter in Fig. 10, the control command calculation unit 111 calculates the header patterns for accomplishing the target coiling temperature by taking advantage of the computation using the strip temperature prediction model 117 and in accordance with the speed pattern calculated at S101.

In the present embodiment, the illustration will be given to the following example: Namely, sections are defined which are obtained by separating the steel strip 151 in the longitudinal direction. Then, with respect to each section of the steel strip 151, the header pattern is calculated in accordance with the following linear inverse interpolation method:
At S102 in Fig. 10, with respect to each section of the steel strip 151, the unit 111 defines two control codes nL and nH whose spacing is large enough to sandwich a control code for the solution therebetween.
Here, the solution exists between the all cooling headers opened state and the all cooling headers closed state with respect to the total number 100 of the cooling headers 160. Accordingly, the unit 111 sets nL and nH at 0 andlOO, respectively, i.e., sets nL = 0 and nH = 100. Here, in accompaniment with the increase in the control codes, the number of the cooling headers 160 opened decreases monotonously. Consequently, when nl < n2 holds, Tcl < Tc2 holds with respect to the target coiling temperatures Tcl and Tc2 corresponding to these header patterns nl and n2.
Subsequently, at S103 in Fig. 10, the unit 111 sets the average between nL and nH at nO.
Moreover, at S104 in Fig. 10, with respect to the control code allocated to each section, the unit 111 predicts, on each section basis, an intermediate

temperature or coiling temperature corresponding to this control code by taking advantage of the computation using the strip temperature prediction model 117. Namely, the unit 111 predicts the intermediate/coiling temperature of each section, using the control code allocated thereto on each section basis.
The control code is allocated on each section basis, and the influence of the speed exerted onto the intermediate/coiling temperature differs for each section. Accordingly, this computation is performed on each section basis.
Incidentally, the coiling temperature prediction computation using the strip temperature prediction model 117 at S104 in Fig. 10 will be described later referring to Fig. 11.
Furthermore, at S105 in Fig. 10, the unit 111 judges the sign of the predicted coiling temperature TcO for the target coiling temperature Ttarget on each section basis. Then, in the case of TcO > Ttarget, the solution exists between nL and nO, and thus the unit 111 sets nO at nH newly.
Conversely, in the case of TcO < Ttarget, the solution exists between nO and nH, and thus the unit 111 sets nO at nL newly.
At S106 in Fig. 10, the unit 111 judges whether or not a termination condition for the algorithm is satisfied.

Incidentally, the termination of the algorithm is judged employing, as the termination condition, the establishment of whatever of "repetition of S103 to S105 in Fig. 10 whose number of times is larger than a constant number of times is completed", "deviation between the predicted coiling temperature TcO and the target coiling temperature Ttarget is smaller than a constant value", or "nO coincides with either of nH and nL".
If the termination condition at S106 in Fig. 10 is not satisfied (i.e., No at S106 in Fig. 10), the unit 111 repeats the execution of S103 to S105. Meanwhile, if the termination condition at S106 in Fig. 10 is satisfied (i.e., Yes at S106 in Fig. 10), the unit 111 terminates the processing.
Additionally, contrary to the present embodiment, the method for allocating the control codes to the cooling headers open/close patterns is also implementable as follows: Namely, the control code for the state where all of the cooling headers 160 are closed is set at 0, and the control code for the state where all of the cooling headers 160 are opened is set at 100, then allocating the other control codes in correspondence this implementation.
As described above, the introduction of the control codes makes it possible to calculate the control command values by taking advantage of the simple and plain computation.

Next, the explanation will be given below concerning the coiling temperature prediction computation using the strip temperature prediction model 117 at S104 in Fig. 10.
Fig. 11 illustrates the detailed processing of the coiling temperature prediction computation corresponding to S104 in Fig. 10. Additionally, Fig. 11 is a flowchart for illustrating the detailed processing of the coiling temperature prediction computation using the strip temperature prediction model.
As the coiling temperature prediction computation method for the steel strip 151, the explanation will be given regarding the following example: Differential calculation on the cooling behavior of the steel strip 151 is made by dividing, in the longitudinal direction, the steel strip 151 from the delivery start of the steel strip 151 out of the mill 157 until the tail-end of the steel strip 151 passes through the coiling pyrometer 156 (refer to Fig. 1), and by advancing the point-in-time into the future with a constant time interval A.
First, at S111 in Fig. 11, the control command calculation unit 111 updates the point-in-time, and further, calculates the steel-strip speed Vt at the updated point-in-time from the speed pattern generated

at S101 in Fig. 10.
Subsequently, at S112 in Fig. 11, using the steel-strip speed Vt calculated, the unit 111 calculates a delivery length Ln in the mill 157 (refer to Fig. 1) at the present point-in-time.
Additionally, the delivery length Ln, which is the length of the steel strip 151 delivered out of the mill 157 after it is hot-rolled thereby, can be calculated using the following Expression (9):
Ln = Ln-1 + Δ•Vt (9)
, where Ln-1 is a delivery length Ln at the previous calculation point-in-time (i.e., the point-in-time at A-time earlier).
At S113 in Fig. 11, the unit 111 judges whether or not the computation has been completed.
Here, when the delivery length Ln out of the mill 157 (refer to Fig. 1) becomes larger than a value obtained by adding the distance from the mill 157 to the coiling pyrometer 156 to the total length of the steel strip 151, the entire coiling temperature prediction computation has been terminated. Accordingly, the unit 111 judges that the computation has been completed.
If the computation has been not completed (i.e., No at S113 in Fig. 11), the unit 111 performs a temperature tracking for the steel strip 151 at S114 in Fig. 11.
Namely, it is recognized from the

relationship between Ln and Ln-1 how far the steel strip 151 advances forward with reference to the position of the steel strip 151 at the previous point-in-time after the time has elapsed by the time interval A. Consequently, the unit 111 performs a processing of displacing the temperature distribution of the steel strip 151 by the distance corresponding thereto.
At S115 in Fig. 11, the unit 111 sets the mill-(157)-exit-side temperature to the portion of the steel strip 151 ejected out of the mill 157 (refer to Fig. 1) during the time interval A.
At S116 in Fig. 11, with respect to each cooling header 160, the unit 111 identifies the section corresponding thereto, then determining the open/close of each cooling header 160 from the value of the control code allocated to each section and the cooling headers priority order fetched from the cooling headers priority order memory unit 115 (refer to Fig. 1). Moreover, from this information on the open/close, the unit 111 judges whether the boundary condition on each location of the steel strip 151 is a water cooling or air cooling boundary condition. Incidentally, the location of the steel strip 151 over which water w of each cooling header 160 is showered is the water cooling, and the location of the steel strip 151 over which water w of each cooling header 160 is not showered is the air cooling.
Namely, the section of the steel strip 151

corresponding to each cooling header 160 is, basically, the steel-strip location positioned directly below or directly above each cooling header 160. Actually, however, an about 2 seconds delay time exists from a point-in-time when the coiling temperature control apparatus 100 (refer to Fig. 1) had transmitted the open/close command to each cooling header 160 to a point-in-time when the surface state of the steel strip 151 has changed.
On account of this situation, actually, the section of the steel strip 151 corresponding to each cooling header 160 is determined such that this delay time is taken into consideration in advance.
If the boundary condition on each location of the steel strip 151 is the water cooling boundary condition, at S117 in Fig. 11, the unit 111 calculates a heat transmission coefficient hw in accordance with, e.g., the following Expression (10):
hw=9.72*105*ω°-355*{ (2.5-1.15*logTw) *D/
(pl*pc) }0-646/ (Tsu-Tw) (10)
, where ω: water amount density, Tw: water temperature, D: nozzle diameter of cooling header 160, pl: nozzle pitch of cooling header 160 in line direction (i.e., right-and-left direction of control target 150 in Fig. 1), pc: nozzle pitch of cooling header 160 in direction perpendicular to line direction, Tsu: surface temperature of steel strip 151.
Expression (10) is the heat transmission

coefficient in the case of the so-called laminar cooling.
As the other water cooling methods, there exist various methods such as the spray cooling, and there have been known several calculation expressions on the heat transmission coefficient. Also, even if the cooling method is the same, the expression corresponding thereto comes to differ in some cases. This is because, e.g., the most update experimental finding is reflected thereon.
Meanwhile, if the boundary condition is the air cooling boundary condition, at S118 in Fig. 11, the unit 111 calculates a heat transmission coefficient hr from a heat amount derived by the radiation and in accordance with, e.g., the following Expression (11):
hr = σ•ε [{(273 + Tsu)/100}4 -
{(273 + Ta)/100}4]/(Tsu-Ta) (11)
, where σ: Stephan-Boltzmann constant (= 4. 88), ε: radiativity, Ta: air temperature (°C), Tsu: surface temperature of steel strip 151.
The heat transmission coefficients, the representatives of which are Expression (10) and Expression (11), are calculated with respect to the surface and rear surface of the steel strip 151 and in accordance with their cooling states. These calculations allow quantification of the respective heat displacement amounts on the surface of the steel strip 151.

Moreover, at S119 in Fig. 11, the unit 111 calculates the temperature of each location of the steel strip 151 by adding/decreasing the displacement of the heat amount during the time interval A on the basis of the temperature before the time interval A has elapsed. This calculation allows the calculation of the temperature distribution of the steel strip 151 between the mill 157 and the coiling pyrometer 156.
As a result, it becomes possible to acquire the temperature of the steel strip 151 at the set-up position of the coiling pyrometer 156. Also, the temperature of the steel strip 151 in the upstream as compared with the set-up position of the coiling pyrometer 156 will be used for the calculation of the next time or thereafter.
In a case where the heat displacement in the thickness direction of the steel strip 151 is neglected, the present steel-strip temperature can be calculated with respect to each location of the steel strip 151 in the longitudinal direction, using the following Expression (12):
Tn = Tn-1 - (ht + hb) * Δ/(ρ * C * B)
(12)
, where Tn: present steel-strip temperature, Tn-1: steel-strip temperature before Δ, ht: heat transmission coefficient on steel-strip surface, hb: heat transmission coefficient on steel-strip rear surface, ρ: steel-strip density, C: steel-strip specific heat,

B: steel-strip thickness.
Incidentally, if the width of the steel strip 151 is narrow, the narrow portion is cooled down by the cooling headers 160. Meanwhile, if the width of the steel strip 151 is wide, the wide portion is cooled down by the cooling headers 160. Consequently, the consideration is given in such a manner that the implementation of the dimensionless is accomplished in the width direction of the steel strip 151.
In a case where the heat conductance in the thickness direction of the steel strip 151 needs to be considered, the steel-strip temperature can be calculated by solving the well-known heat equation. The heat equation is given by the following Expression (13): The method whereby, based on Expression (13) and using a computer, the differential calculation is made by dividing the steel strip 151 in the thickness direction has been publicized in various documents.
∂T/∂t = {λ/(ρ * C) } (∂2T/∂2x) (13)
, where λ: heat conductivity, T: material temperature, t: time, x: thickness direction coordinate.
Furthermore, at S1110 in Fig. 11, the unit 111 judges whether or not the necessary calculation has been completed in the longitudinal direction of the steel strip 151 within the line ranging from the mill 157 (refer to Fig. 1) to the coiling pyrometer 156.
If the necessary calculation has been not completed in the longitudinal direction of the steel

strip 151 within the line (i.e., No at S1110 in Fig. 11), the unit 111 repeats the execution of S116 to S119 in Fig. 11.
Meanwhile, if the necessary calculation has been completed in the longitudinal direction of the steel strip 151 within the line (i.e., Yes at S1110 in Fig. 11), the unit 111 repeats the execution of S111 to S1110 in Fig. 11 until, at S113 in Fig. 11, the unit 111 judges that the computation has been completed.
Additionally, the above-described coiling temperature prediction computation using the strip temperature prediction model 117 is only explained as one example. Accordingly, an amendment can be made to this example when required based on a new finding or the like. Consequently, the present invention is not limited thereto, of course.

Fig. 12A and Fig. 12B are diagrams for illustrating an example at the time when the control codes allocated to the respective locations of the steel strip 151 (refer to Fig. 1) are varied by the optimization processing executed by the control command calculation unit 111 illustrated in Fig. 10.
As illustrated in Fig. 12A, in the 1st processing, this processing is a one for the same initial values (i.e., nL =0, nH = 100) at the respective locations, a control code 50 is allocated to

the respective locations in the entire area of the steel strip 151.
In the 2nd processing illustrated inl2B, control codes to be allocated to the respective locations of the steel strip 151 differ depending on whether the prediction results of the predicted coiling temperatures Tc0 at the respective locations of the steel strip 151 are larger or smaller than the target coiling temperatures Ttarget.
In the present embodiment, the following example is indicated: The control codes for the portions nearer to the front-end and the tail-end of the steel strip 151 where the steel-strip (151) speed is lower are updated to control codes in a direction of closing the cooling headers 160. Meanwhile, the control codes for the central portions of the steel strip 151 where the steel-strip (151) speed is faster are updated to control codes in a direction of opening the cooling headers 160.
Concretely, like the 2nd processing illustrated inl2B, as a result of the update of the control codes to nL = 50 and nH = 100 performed at S105 in Fig. 10 in the 1st processing, the control codes for the front-end and the tail-end of the steel strip 151 are updated to a control code 75, which is an average value therebetween.
Meanwhile, as a result of the update of the control codes to nL = 0 and nH = 50 performed at S105

in Fig. 10 in the 1st processing, the control codes for the central portions of the steel strip 151 are updated to a control code 25.
Repeating S103 to S106 in Fig. 10 in this way allows the control codes to be updated in the sequential manner.
Fig. 13 illustrates an example of the control codes which are finally outputted by the set-up control unit 110 (refer to Fig. 1). Incidentally, Fig. 13 is a configuration diagram for illustrating a correspondence table between the respective steel-strip locations and the control codes.
In the example illustrated in Fig. 13, the steel strip 151 is divided into meshes in a 1 meter unit in correspondence with the distances from the front-end. Accordingly, the control codes are allocated to the steel-strip locations in correspondence with the meshes.
As illustrated in Fig. 1, as the cooling device, the upper cooling device 158 and the lower cooling device 159 exist in correspondence with the surface and rear surface of the steel strip 151. Consequently, the control codes are outputted in correspondence with the upper cooling headers 160a and the lower cooling headers 160b separately.
Fig. 13 shows the following situation of the control codes in the longitudinal direction of the steel strip 151: The control code for the upper

cooling header 160a which is 1 m away from the front-end is set at 95, and the control code for the lower cooling header 160b corresponding thereto is also set at 95. Also, the control code for the upper cooling header 160a which is positioned between 500 m to 501 m is set at 14, and the control code for the lower cooling header 160b corresponding thereto is also set at 14.
Additionally, in Fig. 13, the control codes for the upper cooling headers 160a and the lower cooling headers 160b corresponding to one and the same location of the steel strip 151 are made equal to each other. Setting different control codes, however, is also implementable.
The control codes outputted by the set-up control unit 110 are corrected in real time by the dynamic control unit 120 while the steel strip 151 is being actually cooled down by the upper and the lower cooling devices 158 and 159.
The dynamic control unit 120 includes the strip temperature deviation correction unit 121, the mill-delivery-temperature deviation correction unit 122, and the speed deviation correction unit 123. Using the detection temperature from the coiling pyrometer 156, the unit 121 corrects the deviation between this detection temperature and the target temperature. Using the detection temperature from the deviation between this detection temperature and the mill-delivery-temperature assumed at the time of the set-up control computation. Calculating the steel-strip speed from the rotation speeds of the mill 157 and the down coiler 154, the unit 123 corrects the deviation between this calculation result and the steel-strip speed assumed at the time of the set-up control computation. The dynamic control unit 120 multiplies a sum total ΔTc of these correction amounts by an influence coefficient (∂n/∂Tc) , thereby converting the sum total ΔTc to a variation amount Δn (= (∂n/∂Tc) • ΔTc) of the control codes. Moreover, the dynamic control unit 120 outputs the variation amount Δn as a correction amount calculated thereby.
The calculation of the correction amount can be implemented by application of the proportional integral (PI) or the like.
As illustrated in Fig. 1, the control codes outputted by the set-up control unit 110 are corrected in accordance with the correction amount Δn outputted by the dynamic control unit 120.
Next, the explanation will be given below regarding the header pattern conversion unit 130 (refer to Fig. 1) .
Fig. 14 illustrates an algorithm executed by the header pattern conversion unit 130. Fig. 14 is the flowchart for illustrating the processing of

determining the open/close of each cooling header 160 from the control codes, which is executed by the header pattern conversion unit 130.
At S141 in Fig. 14, the header pattern conversion unit 130 calculates a distance Lh from the front-end of the steel strip 151 which is passing through directly below a cooling header 160. Usually, the coiling temperature control apparatus 100 (refer to Fig. 1) calculates distance information like this with a short period in order to use the distance information for various purposes, and memorizes the distance information into a memory unit (not illustrated) of the coiling temperature control apparatus 100.
At S142 in Fig. 14, the unit 130 judges whether or not the distance Lh is shorter than 0.
If the distance Lh is shorter than 0 (i.e., Yes at S142 in Fig. 14), the steel strip 151 has not reached the cooling header 160 yet. Accordingly, the unit 130 leaves the processing, then transferring to S145 in Fig. 14.
Meanwhile, if the distance Lh is longer than 0 (i.e., No at S142 in Fig. 14), the steel strip 151 has reached the cooling header 160 already. Consequently, at S143 in Fig. 14, the unit 130 extracts a control code corresponding to the distance Lh. Namely, the unit 130 makes a comparison between the distance Lh and the steel-strip (151) locations cooling header 160a and a lower cooling header 160b at a location corresponding to the distance Lh. Next, the unit 130 extracts the control code for this upper cooling header 160a and the control code for this lower cooling header 160b.
At S144 in Fig. 14, the unit 130 extracts the cooling headers (160) open/close pattern from the control code. Namely, the unit 130 determines until what priority order of cooling header 160 should be opened, using the information on the priority orders for the cooling headers 160 received from the set-up control unit 110, and the correspondence between the control codes and the header patterns illustrated in Fig. 9.
Namely, using the information stored into the cooling headers priority order memory unit 115, the unit 130 identifies the cooling headers 160 which should be opened concretely. In this way, finally, the unit 130 determines the sequence of the open/close of the cooling header 160.
At S145 in Fig. 14, the unit 130 judges whether or not the computations on all of the cooling headers 160 have been terminated.
If the computations have been not terminated (i.e., No at S145 in Fig. 14), the unit 130 transfers to S141 in Fig. 14, then repeating the processings at S141 to S145 in Fig. 14 until the computations have been terminated.

Additionally, in the present embodiment, the explanation has been given selecting as the example the case where the number of each of the upper and lower cooling headers 160 is equal to 100. As the number of the cooling headers 160, however, various kinds of numbers are appropriately selectable depending on the facilities. «2nd embodiment»
In the first embodiment, the case has been exemplified where the priority order for each cooling header 160 is determined in the manner of being caused to correspond to the maximum speed of the steel strip 151. In this method, however, there occurs a phenomenon that, when the steel-strip (151) speed is not the maximum speed, the cooling speed to be implemented becomes faster than the target cooling speed depending on the steel-strip (151) speed.
The second embodiment is about the following case: With respect to the various steel-strip (151) speeds which are implemented in accordance with the speed pattern, the priority order for each cooling header 160 is switched depending on the various steel-strip (151) speeds. This switching is performed in order to implement the target cooling speed with a high accuracy.
Fig. 15 is a flowchart for illustrating the processing executed by the cooling headers priority order calculation unit 114 in the second embodiment.

First, at S151 in Fig. 15, the cooling headers priority order calculation unit 114 fetches the target cooling speed and the speed pattern of the steel strip 151 from the target cooling speed table 112 and the speed pattern table 113, respectively.
Subsequently, at S152 in Fig. 15, the unit 114 calculates the cooling time tn in accordance with the Expression (1) described earlier. When the steel type is SUS 304, the strip thickness is equal to 2. 5 mm, the strip width is equal to 1200 mm, and the mill-delivery-temperature assumed value is equal to 880°C, the target coiling temperature becomes equal to 750°C from the target coiling temperature table 116 (Fig. 4). As a result, the cooling time tn is calculated as follows:
tn = (880 - 750)/30 = 4.3 s (second).
Subsequently, at S153 in Fig. 15, the unit 114 makes reference to the speed pattern table 113 illustrated in Fig. 3, and calculates a necessary water cooling distance Lws using the initial speed Vstart , thereby identifying the water cooling banks 161 and the cooling headers 160 which should perform the cooling.
The necessary water cooling distance Lws is calculated using, e.g., the following Expression (14):
Lws = (Vstart x tn)/60 (14)
In the above-described example, Lws is calculated as follows:
Lws = (650 x 4.3)760 = 46.58 m

Consequently, the water cooling banks 161 included within the necessary water cooling distance Lws of 46.58 m from the water cooling bank 161 at the exit of the strip cooling device 153 (refer to Fig. 1) (i.e., the water cooling bank 161 nearest to the rolling mill 152), and the cooling headers 160 corresponding to these water cooling banks 161 turn out to become the identified water cooling banks 161 and cooling headers 160.
At S154 in Fig. 15, the unit 114 calculates the cooling headers priority orders corresponding to the initial speed Vstart in accordance with processing steps similar to the first embodiment, i.e., the earlier-described processings illustrated in Fig. 6 and Fig. 7.
At S155 in Fig. 15, the unit 114 calculates a necessary water cooling distance Lwm using the maximum speed Vmax, thereby identifying the water cooling banks 161 and the cooling headers 160 which should perform the cooling.
The necessary water cooling distance Lwm is calculated using, e.g., the following Expression (15):
Lwm = (Vmax x tn)/60 (15)
Making reference to the speed pattern table 113 illustrated in Fig. 3 similarly to the first embodiment, the unit 114 calculates Lwm as follows:
Lwm = (1050 x 4.3)/60 = 75.25 m
Consequently, the water cooling banks 161

included within the necessary water cooling distance Lwm of 75. 25 m from the water cooling bank 161 at the exit of the strip cooling device 153 (refer to Fig. 1) (i.e., the water cooling bank 161 nearest to the rolling mill 152), and the cooling headers 160 corresponding to these water cooling banks 161 turn out to become the identified water cooling banks 161 and cooling headers 160.
At S156 in Fig. 15, the unit 114 calculates the cooling headers priority orders corresponding to the maximum speed Vmax in accordance with processing steps similar to the earlier-described processings illustrated in Fig. 6 and Fig. 7.
At S157 in Fig. 15, the unit 114 calculates a necessary water cooling distance Lwe using the terminal speed Vend, thereby identifying the water cooling banks 161 and the cooling headers 160 which should perform the cooling.
The necessary water cooling distance Lwe is calculated using, e.g., the following Expression (16):
Lwe = (Vend x tn)/60 (16)
Making reference to the speed pattern table 113 illustrated in Fig. 3 similarly to the first embodiment, the unit 114 calculates Lwe as follows:
Lwe = (900 x 4.3)/60 = 64.5 m
Consequently, the water cooling banks 161 included within the necessary water cooling distance Lwe of 64.5 m from the water cooling bank 161 at the

exit of the strip cooling device 153 (refer to Fig. 1) (i.e., the water cooling bank 161 nearest to the rolling mill 152), and the cooling headers 160 corresponding to these water cooling banks 161 turn out to become the identified water cooling banks 161 and cooling headers 160.
At S158 in Fig. 15, the unit 114 calculates the cooling headers priority orders corresponding to the terminal speed Vend in accordance with processing steps similar to the earlier-described processings illustrated in Fig. 6 and Fig. 7.
At S159 in Fig. 15, the unit 114 outputs the calculation results corresponding to the initial speed Vstart, the maximum speed Vmax, and the terminal speed Vend to the cooling headers priority order memory unit 115 (refer to Fig. 1).
The contents of the cooling headers priority order memory unit 115 are sent from the set-up control unit 110 illustrated in Fig. 1 to the header pattern conversion unit 130 together with the set-up result of the control codes.
Fig. 16 is a diagram for illustrating the configuration of the cooling headers priority order memory unit 115 into which the information outputted by the cooling headers priority order calculation unit 114 in the second embodiment is stored.
In the present second embodiment, depending on the various steel-strip (151) speeds, the necessary

water cooling distances Lws, Lwm, and Lwe become different from each other in the range of 47.58 m to 76.25 m. Accordingly, the cooling headers priority orders for implementing the distances also become different from each other. As a result, as illustrated in Fig. 16, the cooling headers priority orders corresponding to the initial speed Vstart, the maximum speed Vmax, and the terminal speed Vend are allocated to each cooling header 160.

Fig. 17 is a flowchart for illustrating the detailed processing of the coiling temperature prediction computation executed by the control command calculation unit 111 in the second embodiment.
Although the processing flow executed by the control command calculation unit 111 is the same as the one illustrated in Fig. 11, S176 is added thereto. Namely, in the processing at S176 in Fig. 17, based on the present steel-strip (151) speed, the control command calculation unit 111 selects which of the three types of cooling headers priority orders should be extracted, and extracts the type of cooling headers priority orders selected in this way. Here, the three types of cooling headers priority orders are illustrated in Fig. 16, and are registered into the cooling headers priority order memory unit 115.

At S177 in Fig. 17, with respect to each cooling header 160, the unit 111 identifies the section of the steel strip 151 corresponding thereto, then determining the open/close of each cooling header 160 from the value of the control code allocated to each section and the cooling headers priority order extracted.

Fig. 18 is a flowchart for illustrating the processing algorithm for determining the open/close of each cooling header 160 from the control codes, which is executed by the header pattern conversion unit 130 (refer to Fig. 1) in the second embodiment.
Although the processing flow executed by the header pattern conversion unit 130 is basically the same as the one illustrated in Fig. 14, S184 is added thereto. Namely, in the processing at S184 in Fig. 18, based on the present steel-strip (151) speed, the header pattern conversion unit 130 selects and determines which of the three types of cooling headers priority orders received from the set-up control unit 110 (refer to Fig. 1) should be used.
At S185 in Fig. 18, the unit 130 extracts the cooling headers open/close pattern, using the control code and the cooling headers priority order selected.
Namely, the unit 130 determines until what priority order of cooling header 160 should be opened,

using the information on the selected cooling headers (160) priority order, and the correspondence between the control codes and the cooling headers open/close patterns illustrated in Fig. 9.
According to the above-described second embodiment, the priority order for each cooling header 160 is switched depending on the steel-strip (151) speed. This feature allows the target cooling speed to be implemented with a high accuracy even if the steel-strip (151) speed is changed. «3rd embodiment»
The third embodiment is about a case where a processing which should be performed when the following phenomena occur is added to the algorithm executed by the control command calculation unit 111 illustrated in Fig. 1: The target cooling speed cannot be satisfied due to a limitation in the cooling capability of the strip cooling device 153. Otherwise, when the set-up calculation is made under the condition that the necessary water cooling distance satisfying the target cooling speed is ensured, the coiling temperature cannot achieve the target coiling temperature.
Fig. 19 is a flowchart for illustrating the processing which is executed by the control command calculation unit 111 in the third embodiment, and to which a processing like this is added.
S191 to S196 in Fig. 19 are the same as the processing executed by the control command calculation

unit 111 illustrated in Fig. 10 in the first embodiment. In addition thereto, after terminating the set-up calculation, in the processing at S197 in Fig. 19, the control command calculation unit 111 judges whether or not the target coiling temperature and the target cooling speed have been achieved.
If both the target coiling temperature and the target cooling speed have been achieved (i.e., Yes at S197 in Fig. 19), the unit 111 terminates the processing. Meanwhile, if neither the target coiling temperature nor the target cooling speed has been achieved (i.e., No at S197 in Fig. 19), at S198 in Fig. 19, the unit 111 changes the maximum speed of the steel strip 151.
When the coiling temperature is lower than the target coiling temperature, the unit 111 performs a processing of increasing the maximum speed of the steel strip 151 within a range tolerated by a facility limitation. This processing is performed in order to shorten the time during which the steel strip 151 is cooled down. Conversely, when the coiling temperature is higher than the target coiling temperature, the unit 111 performs a processing of decreasing the maximum speed of the steel strip 151 to lower the coiling temperature. This processing is performed in order to lengthen the time during which the steel strip 151 is cooled down.
Also, when the target cooling speed cannot be

achieved, the unit 111 similarly performs the processing of decreasing the maximum speed of the steel strip 151 to lengthen the time during which the steel strip 151 is cooled down, thereby increasing the cooling speed.
A change amount in the maximum speed in each case may be defined in advance by a table or the like. Otherwise, the value of the change amount in the maximum speed which follows an extent in which the target coiling temperature or the target cooling speed cannot be satisfied may be calculated on each occasion basis.
In the case of calculating the change amount in the maximum speed in each case, when, e.g., the target coiling temperature cannot be achieved, the speed change amount ΔVmax is calculated in accordance with the following Expression (17), thereby changing the maximum speed of the steel strip 151 to achieve the target coiling temperature:
ΔVmax = (∂V/∂Tc) • δTc (17)
, where δTc: target-coiling temperature unachieved amount, (∂V/∂Tc): constant (i.e., influence coefficient) corresponding to influence exerted on coiling temperature by speed change.
Hereinafter, the control command calculation unit 111 repeats the processings at S191 to S198 in Fig. 19 under the changed maximum speed of the steel strip 151.

According to the above-described third embodiment, if it has been found impossible to simultaneously satisfy the two control targets, i.e., the target coiling temperature and the target cooling speed, due to a limitation in the cooling capability, the execution of an increase/decrease in the speed of the steel strip 151 allows the two control targets to be simultaneously satisfied within a facility-based implementable range. «Summary»
The present invention provides the coiling temperature control apparatus 100 which is configured by including
the cooling headers priority order calculation unit 114 for calculating the priority orders for the open/close of the cooling headers 160 corresponding to the steel-strip (151) speed from the target cooling speed and the speed pattern of the steel strip 151,
the cooling headers priority order memory unit 115 for accumulating the cooling headers priority orders calculated,
the control command calculation unit 111 for calculating, as the control codes, the command values for the strip cooling device 153 for accomplishing a desired coiling temperature, using the target coiling temperature, the speed pattern, and the cooling headers priority orders as input information, and taking

advantage of the strip temperature prediction model 117, and
the header pattern conversion unit 130 for converting the control codes to the cooling headers open/close patterns of the strip cooling device 153 using the cooling headers priority orders corresponding to the steel-strip (151) speed.
The cooling headers priority order calculation unit 114 fetches the target cooling speed of the steel strip 151, then calculating a necessary water cooling distance from this target cooling speed and the steel-strip (151) speed. Moreover, the unit 114 opens, with the highest or higher priority, the cooling headers 160 which are included within this distance. Simultaneously, the unit 114 allocates the priority order to each cooling header 160 so that the target cooling speed will be satisfied.
The control command calculation unit 111 calculates the header pattern for accomplishing the target coiling temperature with respect to each location of the steel strip 151 in its longitudinal direction, while making reference to the contents outputted by the cooling headers priority order calculation unit 114 and stored into the cooling headers priority order memory unit 115.
As a result of the above-described set-up calculation, if either of the target coiling temperature/target cooling speed is not satisfied, the

set-up calculation is executed once again in such a manner that the steel-strip (151) speed is increased/decreased. «Effect»
According to the above-described configuration, in the coiling control over the after-hot-rolled steel strip 151, it becomes possible to acquire the uniform cooling speed and coiling temperature at whatever location of the steel strip 151 in its longitudinal direction.
Incidentally, in the above-described embodiments, the explanation has been given exemplifying the steel strip as the rolled strip. It is of course, however, that the present invention is also applicable to rolled strips other than the steel strip.
The present invention is widely applicable to the cooling control on a hot rolling line.
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.

CLAIMS:
1. A coiling temperature control apparatus (100) for cooling a rolled strip (151) rolled by a hot rolling mill (152) by using a cooling device (153) set up on an exit side of said hot rolling mill (152), and controlling coiling temperature of said rolled strip (151) into a predetermined target coiling temperature before said rolled strip (151) is coiled by a down coiler (154), comprising:
cooling headers priority order calculation means (114) for calculating and outputting a priority relationship among opening sequences of cooling headers (160) set up in said cooling device (153), so that cooling speed of said rolled strip (151) in the course of being cooled satisfies a predetermined target cooling speed,;
cooling headers priority order memory means (115) for storing said priority order for each cooling header (160) outputted by said cooling headers priority order calculation means (114); and
control command calculation means (111) for predicting said coiling temperature of said rolled strip (151) based on said target coiling temperature, information on speed of said rolled strip (151), and information stored in said cooling headers priority order memory means (115), and by using a strip temperature prediction model (117) for predicting said coiling temperature of said rolled strip (151), and
calculating and outputting a header pattern for accomplishing said target coiling temperature by using said prediction result of said coiling temperature, the header pattern being a combination of open/close of each cooling header (160) .
2. A coiling temperature control apparatus (100) for cooling a rolled strip (151) rolled by a hot rolling mill (152) by using a cooling device (153) set up on an exit side of said hot rolling mill (152), and controlling coiling temperature of said rolled strip (151) into a predetermined target coiling temperature before said rolled strip (151) is coiled by a down coiler (154), comprising:
cooling headers priority order calculation means (114) for calculating and outputting a priority relationship among opening sequences of cooling headers (160) set up in said cooling device (153), so that cooling speed of said rolled strip (151) in the course of being cooled satisfies a predetermined target cooling speed,;
cooling headers priority order memory means (115) for storing said priority order for each cooling header (160) outputted by said cooling headers priority order calculation means (114);
control command calculation means (111) for generating a control code by using information stored in said cooling headers priority order memory means (115), said control code corresponding to each header
pattern which is a combination of open/close of each cooling header (160), predicting said coiling temperature of said rolled strip (151) based on said target coiling temperature and information on speed of said rolled strip (151), and using a strip temperature prediction model (117) for predicting said coiling temperature of said rolled strip (151), and calculating and outputting said control code for accomplishing said target coiling temperature by using said prediction result of said coiling temperature; and
header pattern conversion means (130) for converting said control code to each header pattern, and outputting each header pattern to said cooling device (153), said control code being outputted by said control command calculation means (111) by using information stored into said cooling headers priority order memory means (115) .
3. The coiling temperature control apparatus (100) according to Claim 2, wherein
said control code for a state where all of said cooling headers (160) are opened is defined as being its maximum value, and meanwhile, said control code for a state where all of said cooling headers (160) are closed is defined as being its minimum value,
said prediction value of said coiling temperature being caused to correspond to said control code such that said prediction value decreases monotonously in accompaniment with an increase in

numerical size of said control code.
4. The coiling temperature control apparatus
(100) according to Claim 2, wherein
said control code for a state where all of said cooling headers (160) are opened is defined as being its minimum value, and meanwhile, said control code for a state where all of said cooling headers (160) are closed is defined as being its maximum value,
said prediction value of said coiling temperature being caused to correspond to said control code such that said prediction value increases monotonously in accompaniment with an increase in numerical size of said control code.
5. The coiling temperature control apparatus
(100) according to Claim 1, wherein
said cooling headers priority order calculation means (114)
calculates a temperature drop amount of said rolled strip (151) in said cooling device (153) from a temperature of said rolled strip (151) at the time of entering said cooling device (153) and said target coiling temperature of said rolled strip (151) before being coiled by said down coiler (154),
calculates a time from said temperature drop amount and said target cooling speed of said rolled strip (151), said time being needed for said cooling,
calculates a distance from information on said time and said speed of said rolled strip (151),
said distance being needed for said water cooling, said time being needed for said cooling,
classifies and identifies, based on said distance, said cooling headers (160) into a cooling headers (160) group having a possibility of being opened, and a cooling headers (160) group having no possibility of being opened, and
allocates said priority order to said cooling headers (160) group having said possibility of being opened, so that said cooling speed of said rolled strip (151) becomes equal to a substantially constant value.
6. The coiling temperature control apparatus
(100) according to Claim 1, wherein,
when a speed at which said rolled strip (151) is rolled, or a speed at which said rolled strip (151) is coiled by said down coiler (154) changes,
said cooling headers priority order calculation means (114)
performs said computation in a manner of being caused to correspond to said speed of said rolled strip (151), said computation being intended for allocating said priority order to each cooling header (160), and
outputs said priority order for each cooling header (160) to said cooling headers priority order memory means (115), said priority order being caused to correspond to said speed of said rolled strip (151).
7. The coiling temperature control apparatus
(100) according to Claim 2, wherein
said control command calculation means (111)
calculates and outputs said control code in a manner of being caused to correspond to each location of said rolled strip (151) in its longitudinal direction, and
said header pattern conversion means (130)
extracts said control code corresponding to a location of said rolled strip (151) after having recognized said location in advance, said location being positioned directly below each cooling header (160) in said longitudinal direction,
extracts a cooling headers (160) priority order from said cooling headers priority order memory means (115), said cooling headers (160) priority order corresponding to a present speed of said rolled strip (151), and
converts said control code to each header pattern in accordance with said cooling headers (160) priority order extracted, and outputs each header pattern to said cooling device (153). 8. The coiling temperature control apparatus (100) according to Claim 2, wherein
said control command calculation means (111), after having calculated said control command,
judges whether or not said target coiling temperature and said target cooling speed are satisfied under said control command calculated, and, if whatever
of said target coiling temperature and said target cooling speed is not satisfied,
changes said speed of said rolled strip (151) then to calculate said control command once again, and
repeats said change and said calculation until both said target coiling temperature and said target cooling speed are satisfied.
9. The coiling temperature control apparatus (100) according to Claim 1, wherein
said control command calculation means (111), after having calculated said control command,
performs in advance a processing of
judging whether or not said target coiling temperature and said target cooling speed are satisfied under said control command calculated,
raising said speed of said rolled strip (151) if said coiling temperature is lower than said target coiling temperature, lowering said speed of said rolled strip (151) if said coiling temperature is higher than said target coiling temperature, and
lowering said speed of said rolled strip (151) if said cooling speed is slower than said target cooling speed, and after said processing,
calculates said control command once again, and
repeats said processing and said calculation until both said target coiling temperature and said target cooling speed are satisfied.
10. A coiling temperature control method for
cooling a rolled strip (151) rolled by said hot rolling
mill (152) by using a cooling device (153) set up on an
exit side of a hot rolling mill (152), and controlling
coiling temperature of said rolled strip (151) into a
predetermined target coiling temperature before being
coiled by a down coiler (154), comprising the steps of:
allocating a priority order to opening sequences of cooling headers (160) set up in said cooling device (153), so that cooling speed of said rolled strip (151) satisfies a predetermined target cooling speed;
generating a control code by using said priority order, said control code corresponding to each header pattern which is a combination of open/close of each cooling header (160) ;
predicting said coiling temperature of said rolled strip (151) based on said control code and information on speed of said rolled strip (151), and by using a strip temperature prediction model;
determining and outputting said control code for accomplishing said target coiling temperature by using said prediction result of said coiling temperature; and
converting said control code to each header pattern, and outputting each header pattern to said cooling device (153).
11. The coiling temperature control method
according to Claim 10, further comprising the steps of:
calculating a temperature drop amount of said rolled strip (151) in said cooling device (153) based on a temperature of said rolled strip (151) at the time of entering said cooling device (153) and said target coiling temperature of said rolled strip (151) before being coiled by said down coiler (154);
calculating a time from said temperature drop amount and said target cooling speed of said rolled strip (151), said time being needed for said cooling;
calculating a distance based on information on said time and said speed of said rolled strip (151), said distance being needed for said water cooling, said time being needed for said cooling;
classifying and identifying, based on said distance, said cooling headers (160) into a cooling headers (160) group having a possibility of being opened, and a cooling headers (160) group having no possibility of being opened; and
allocating said priority order to said cooling headers (160) group having said possibility of being opened, so that said cooling speed of said rolled strip (151) becomes equal to a substantially constant value;
generating said control code by using said priority order, said control code corresponding to each header pattern which is said combination of said open/close of each cooling header (160) ;
predicting said coiling temperature of said rolled strip (151) based on said control code and said information on said speed of said rolled strip (151), and by using said strip temperature prediction model;
determining and outputting said control code for accomplishing said target coiling temperature by using said prediction result of said coiling temperature; and
converting said control code to each header pattern, and outputting each header pattern to said cooling device (153).
12. The coiling temperature control method according to Claim 10, further comprising the steps of:
allocating said priority order for said opening sequences with respect to said cooling headers (160) in a manner of being caused to correspond to a speed at which said rolled strip (151) is rolled, or a speed at which said rolled strip (151) is coiled by said down coiler (154), said priority order allowing said cooling speed of said rolled strip (151) to satisfy said predetermined target cooling speed;
generating said control code in a manner of being caused to correspond to each location of said rolled strip (151) in its longitudinal direction, said control code corresponding to each header pattern which is said combination of said open/close of each cooling header (160);
predicting said coiling temperature of said
rolled strip (151) based on said control code and said information on said speed of said rolled strip (151), and by using said strip temperature prediction model;
determining and outputting said control code for accomplishing said target coiling temperature using said prediction result of said coiling temperature;
extracting said control code corresponding to a location of said rolled strip (151) after having recognized said location in advance, said location being positioned directly below each cooling header (160) in said longitudinal direction; and
converting said control code to each header pattern in accordance with a priority order, and outputting each header pattern to said cooling device (153), said priority order being allocated to each cooling header (160) and corresponding to a present speed of said rolled strip (151).