JP2012011448A - Cooling control method of rolled material, and continuous rolling mill to which the cooling control method is applied - Google Patents

Abstract

PROBLEM TO BE SOLVED: To construct a transformation heating prediction model and temperature prediction model by which a transformation heating amount in cooling a rolled material is precisely predicted, and to provide a cooling control method of the rolled material using the prediction model.SOLUTION: In the cooling control method, the transformation heating prediction model in which the transformation heating amount generated in the rolled material W in cooling is predicted by using a ferrite transformation rate, and the temperature prediction model for predicting a sheet temperature by using the predicted transformation heating amount are prepared. The ferrite transformation rate is obtained by using an acquired intermediate temperature actual value. The transformation heating amount generated in a downstream side from a position where the intermediate temperature actual value is acquired is predicted by the transformation heating prediction model using the obtained ferrite transformation rate, and a prediction value of a winding temperature is obtained by the temperature prediction model using the predicted transformation heating amount. A cooling means 3 is controlled so that a difference between the prediction value of the winding temperature and a target value becomes a predetermined value or less.

Description

  The present invention relates to a rolling material cooling control method suitable for cooling a rolled material after hot finish rolling, and a continuous rolling machine to which the cooling control method is applied.

Conventionally, a rolled material such as a thin steel plate has been manufactured by continuously rolling a heated slab with a plurality of rolling stands, and winding the rolled material on the downstream side of the final rolling stand. A machine is provided. Further, a cooling means for cooling while controlling the temperature of the rolled material is provided between the final rolling stand and the winder.
The cooling means is configured by a plurality of cooling banks provided with a plurality of valves that make the supply amount of cooling water variable. The cooling means, that is, the cooling bank, adjusts the temperature of the rolled material and controls the cooling by changing the number of open valves, which is the number of valves in the open state, in order to make the plate temperature of the rolled material coincide with the target temperature.

By the way, in order to keep the material properties such as strength and toughness of the rolled material within a predetermined range, it is important to control the winding temperature immediately before winding. For this reason, it is necessary to increase the accuracy of the temperature prediction model and improve the accuracy of predicting the winding temperature. As one method for improving the accuracy of the temperature prediction model, taking into account the amount of transformation heat generated in the rolled material during cooling.
The transformation calorific value referred to here is the sum of the calorific value associated with the change in structure and the calorific value associated with the change in magnetic state. The calorific value associated with the structural change is the amount of heat generated during the transformation of the steel material immediately after the final rolling, which is in the austenitic state, but transforms into a structure such as ferrite and pearlite as the rolled material (steel plate) is cooled. is there. The calorific value associated with the change in the magnetic state is the amount of heat generated at the time when a magnetic transformation that changes from a paramagnetic material to a ferromagnetic material occurs as the rolled material (steel plate) is cooled.

  Equation (1) is often used as a temperature prediction model in consideration of such transformation heat generation.

Patent Document 1 and Patent Document 2 disclose techniques for specifically predicting the transformation calorific value Q included in Equation (1).
Patent Document 1 is a method for manufacturing a steel material, which is manufactured through a step of cooling a steel plate processed by a finish rolling mill with a cooling unit, and measures the temperature of the steel plate before being cooled by the cooling unit. Calculating a total calorific value released from the surface of the steel sheet, calculating a calorific value of the steel sheet using a calorific value calculating step and an isothermal transformation diagram. Using the step, the temperature measured by the first temperature measurement step, the calorific value calculated by the calorific value calculation step, and the transformation calorific value calculated by the transformation calorific value calculation step, Predicting the temperature of the steel sheet cooled by the cooling means, predicting the temperature of the steel sheet cooled by the cooling means, measuring the cooling temperature of the steel sheet cooled by the cooling means, and predicting the temperature. And wherein the temperature, such that the second temperature measurement step and the cooling temperature measured by match, and controls the operation of the cooling means, discloses a method of making steel comprising a motion control step.

  Patent Document 2 describes a rolled material obtained by cooling a metal rolled material rolled by a hot rolling mill with a cooling means installed on a conveying table on the delivery side of the rolling mill and measuring with a winding thermometer before the winding machine. In the coiling temperature control device that controls the coiling temperature to a predetermined temperature target value, while predicting the amount of transformation heat generated when the rolled material undergoes phase transformation, and compensating the amount of transformation heat generation Discloses a winding temperature control device provided with a transformation heat generation model learning means for controlling the winding temperature to coincide with a predetermined temperature target value and learning a transformation heat generation model for predicting the amount of transformation heat generation. To do.

In addition, as in Patent Document 3, for the purpose of improving the accuracy of the coiling temperature, an approach using the actual temperature value of the intermediate thermometer is also performed.
That is, Patent Document 3 is directed to a plurality of water-cooling devices arranged in parallel in the conveyance direction of the steel sheet toward the steel sheet conveyed by the conveyance table after being hot-rolled by a hot rolling mill. The steel sheet is cooled by injecting cooling water under a predetermined cooling condition by predicting the coiling temperature of the steel sheet by calculation based on a predetermined hot rolling condition, and then applied to the coil by a winder. When producing a hot-rolled steel sheet by winding, in the course of the hot rolling, when the hot rolling is continued by changing to another hot rolling condition different from the predetermined hot rolling condition In addition, based on the other hot rolling conditions and the measured value of the temperature of the steel plate on the inlet side of the water cooling device located on the most upstream side of the plurality of water cooling devices, the coiling temperature of the steel plate is targeted Value One or two or more water cooling devices other than the water cooling device located on the most upstream side among the other hot rolling conditions and the plurality of water cooling devices are obtained. A method for manufacturing a hot-rolled steel sheet is disclosed in which the set value of the cooling condition determined for at least one or more of the water cooling devices is corrected and set based on the measured value of the temperature of the steel sheet on the inlet side.

JP 2008-161924 JP 2005-297015 A JP 2009-56504 A

  Patent Document 1 described above performs transformation heat generation prediction with high accuracy without preparing enormous parameters by using a transformation heat generation behavior prediction model using an isothermal transformation diagram (TTT curve diagram). Yes. Specifically, by transforming a TTT curve diagram uniquely determined by the composition of the steel sheet according to the composition of the steel sheet to be cooled, even a steel sheet having a composition different from the composition in which the TTT curve diagram exists can be transformed with high accuracy. It is possible to predict.

However, in the technique of Patent Document 1, the method of modifying the four parameters (ΔT _s , ΔT _f , Δt _s , Δt _f ) of the TTT curve is not sufficient only by the disclosure in the specification, and a specific derivation is made. Equivalent to no explanation of the method. In addition, it is described that the four parameters (ΔT _s , ΔT _f , Δt _s , Δt _f ) can be expressed as Equations (1) to (8) in the literature. However, it is unclear whether the transformation heat value can be accurately predicted, and many verifications are required when applying it to actual on-site equipment. Technology.

On the other hand, the technique of Patent Document 2 uses a steel plate data in at least two different cooling situations (one completes transformation during winding and the other during transformation), A learning method is used.
In the transformation heat generation model of this method, the transformation heat generation amount is composed of the product of `` adjustment gain '', `` ferrite volume fraction '', `` latent heat accompanying transformation '', winding temperature, actual data of time required for winding, An adjustment gain is determined using a time-dependent ferrite volume fraction model or the like, and a transformation heat generation model is constructed.

However, in the technique of Patent Document 2, Expressions (3) and (4) in the document are used as mathematical expressions representing the temporal transition of the ferrite fraction, and these expressions are approximate expressions, It is unclear how accurately the accuracy can be predicted. Therefore, there is a possibility that the increase amount (ΔF _ij ) of the ferrite volume fraction calculated by the equation (6) in the document may not be an accurate value, and the calorific value obtained by the equation (10) in the document including ΔF _ij The actual value is that the value of K _QT , which is the adjustment gain, is not an accurate value, and as a result, it is not known to what degree the transformation calorific value can be predicted.

That is, the technique of Patent Document 2 also requires many verifications when applied to actual field equipment.
On the other hand, the technique of Patent Document 3 predicts the temperature drop of the number of cooling devices on the downstream side (winding temperature side) of the cooling device using the actual temperature value of the intermediate thermometer provided in the water cooling device. Based on the formula, it is corrected. However, in this technique, the temperature prediction formula used for correction does not include an expression that expresses the transformation heat generation amount.If transformation heat generation occurs between the intermediate thermometer and the winding, the temperature drop amount is calculated. It cannot be predicted accurately, and there is a high possibility that the accuracy of the winding temperature will greatly deteriorate. In other words, the technique of Patent Document 3 is not a technique that can be used to specifically predict the transformation heat generation amount Q.

  Therefore, in view of the above problems, the present invention constructs a transformation heat generation prediction model and a temperature prediction model that can accurately predict the transformation heat generation amount during cooling of the rolling material, and cools the rolling material using the prediction model. An object is to provide a control method.

In order to achieve the above-described object, the present invention takes the following technical means.
That is, in hot continuous rolling, it is a well-known fact among those skilled in the art that the total amount of transformation heat generation is large between the intermediate thermometer and the winding device. On the other hand, if the amount of change in transformation heat generation is not accurately predicted, it can be easily imagined that a situation occurs in which the accuracy of the winding temperature is greatly deteriorated.

  In particular, since the rolling end of the rolled material is rolled in a tension-free state, the plate shape is more likely to be disturbed compared to other portions (such as the intermediate portion), and hence the plate temperature is disturbed, resulting in an intermediate temperature. In many cases, the actual value deviates from the target value. Therefore, the transformation calorific value from the intermediate thermometer to the winding device predicted at the time of the final rolling stand exit is greatly different from the actual transformation calorific value, and the control accuracy of the coiling temperature is often greatly deteriorated.

In view of the above, the inventors of the present application use a temperature prediction model including a prediction of the transformation heat value and improve the accuracy of the coiling temperature in the hot continuous rolling, Control logic that corrects the valve pattern in the cooling means by predicting the transformation calorific value utilizing the actual value, that is, the following cooling control method for the rolled material was constructed.
The method for controlling cooling of a rolled material according to the present invention uses a cooling means for water-cooling the rolled material, and when cooling so that the winding temperature of the rolled material after rolling becomes a target value, the transformation that occurs in the rolled material during cooling A transformation heat generation prediction model that predicts the heat generation amount using the ferrite transformation rate of the rolled material, and a temperature prediction model that predicts the temperature of the rolling material using the transformation heat generation amount predicted by this transformation heat generation prediction model are prepared. In addition, the temperature of the rolled material in the middle position of the cooling means is acquired as an intermediate temperature actual value, the ferrite transformation rate is obtained using the acquired intermediate temperature actual value, and the transformation heat generation using the obtained ferrite transformation rate is obtained. The prediction model predicts the amount of transformation heat generated downstream from the position where the actual intermediate temperature value was obtained, and rolls up the rolled material using the temperature prediction model that uses the predicted amount of transformation heat generation. It obtains the predicted value of the time difference between the predicted value and the target value of the winding temperature and controlling the cooling means to be equal to or less than a predetermined value.

Preferably, the ferrite transformation rate is calculated by an equation including a time constant of the ferrite transformation rate as a variable, and the time constant of the ferrite transformation rate is expressed as a linear linear expression based on the actual intermediate temperature value. It is good to decide.
The cooling means has a configuration provided with a plurality of cooling banks capable of changing the number of open valves,
The number of open valves of the cooling bank may be changed so that the difference between the predicted value of the coiling temperature and the target value is not more than a predetermined value.

  On the other hand, the continuous rolling mill according to the present invention is provided in a plurality of rolling stands that roll the rolled material, a cooling means that is arranged on the downstream side of the rolling stand and water-cools the rolled material, and is provided in the middle of the cooling means. An intermediate thermometer, a winding device for winding the rolled material cooled by the cooling means, and the above-described cooling control method for the rolled material, and the difference between the predicted value and the target value of the winding temperature is a predetermined value. And a control unit that controls the cooling means so as to be less than or equal to the value.

  By using the rolling material cooling control technology according to the present invention, it is possible to accurately calculate the amount of transformation heat generated when the rolled material is cooled, and to accurately predict the plate temperature (winding temperature) of the rolled material, and as a result. It becomes possible to reliably control the cooling of the rolled material.

It is the figure which showed the apparatus structure of the continuous rolling mill. It is the flowchart which showed the determination method of the valve pattern in a cooling means. It is a figure which shows the intermediate temperature actual value and the optimal time constant of the ferrite transformation rate which were databased. It is the figure which showed the result of having employ | adopted the cooling control method of the rolling material which concerns on this embodiment (The temperature middle rate in the full length of a rolling material). It is the figure which showed the result of having employ | adopted the cooling control method of the rolling material which concerns on this embodiment (The temperature middle rate in the front-end | tip of a rolling material). It is the figure which showed the result which employ | adopted the cooling control method of the rolling material which concerns on this embodiment (temperature distribution in a rolling material longitudinal direction).

An embodiment of the present invention will be described with reference to the drawings. In the following description, the same parts are denoted by the same reference numerals. Their names and functions are also the same. Therefore, detailed description thereof will not be repeated.
Hereinafter, the cooling control method for the rolled material W and the continuous rolling mill 1 according to the present invention will be described by exemplifying the hot continuous rolling mill 1 for thin steel sheets.
[Device configuration]
A rolled material W such as a thin steel plate is produced by introducing a heated base plate or slab into a continuous rolling mill 1 provided with a plurality of rolling stands 2 and continuously rolling it. The rolling stand 2 provided on the upstream side of the continuous rolling mill 1 is a rough rolling stand, and the rolling stand 2 provided on the downstream side is a finishing rolling stand that adjusts the plate thickness and the like.

The rolled material W exiting the rolling stand 2 (that is, the finish rolling stand) provided in the final stage is cooled while passing through the cooling means 3 disposed on the downstream side in the rolling material transfer direction. It is wound up.
FIG. 1 is a diagram illustrating a configuration from a rolling stand 2 provided in the final stage of the continuous rolling mill 1 to a cooling unit 3 and a winding device 4. In the transfer direction of the rolling material W, the side (winding device 4 side) to which it is transferred is called the downstream side, and the opposite side (rolling stand 2 side) is called the upstream side.

The rolling stand 2 includes a pair of work rolls 5 and 5 and a pair of backup rolls 6 and 6 that back up the work rolls 5 and 5. The rotation axis of the work roll 5 is provided with an exit side plate speed detector 7 that measures the number of rotations and measures the plate speed that is the transfer speed of the rolled material W.
On the exit side of the rolling stand 2, an exit side plate thermometer 8 that measures the plate temperature that is the temperature of the rolled material W is disposed. The delivery side plate thermometer 8 is a radiation thermometer that measures the plate temperature based on the amount of heat radiation from the rolled material W. On the downstream side of the delivery side plate thermometer 8, an delivery side thickness meter 12 composed of a γ-ray thickness meter is installed.

Cooling means 3 is provided on the downstream side of the outlet side thickness gauge 12. The cooling means 3 includes a plurality of cooling banks 9 on the upper and lower (front and back) surfaces of the rolled material W, and is arranged such that a plurality (m = 1 to N) of the cooling banks 9 are continuous in the rolling material transfer direction. It has become.
The cooling bank 9 is provided with a plurality of cooling nozzles (not shown) for spraying cooling water (coolant) toward the rolled material W to lower the temperature of the rolled material W, and each cooling nozzle has a flow rate of the coolant. There is provided a valve (not shown) that can be turned on and off. When this valve is opened, the coolant spouts from the cooling nozzle, so changing the number of open valves (number of open valves) changes the total amount of coolant sprayed from the cooling nozzle to the rolled material W. The amount of temperature drop is variable.

A thermometer composed of a radiation thermometer is installed in the middle of the cooling means 3 to measure the plate temperature of the rolled material W during cooling. This thermometer is referred to as an intermediate thermometer 10.
A thermometer composed of a radiation thermometer is installed on the downstream side of the cooling bank 9 on the most downstream side of the cooling means 3 and immediately before the winding device 4. The plate temperature is measured. Hereinafter, this thermometer is referred to as a winding thermometer 11.

A winding speed detector 13 for measuring the rotational speed of the shaft is installed on the rotating shaft of the winding device 4.
The above-mentioned measured data of the exit side plate thermometer 8, the exit side plate speed detector 7 and the exit side plate thickness meter 12, that is, the actual values of the plate temperature, plate speed, and plate thickness on the exit side of the rolling stand 2 control the cooling means 3. Is input to the control unit 20. Actual values (winding temperature, winding speed) from the winding thermometer 11 and the winding speed detector 13 are also input to the control unit 20.

The control unit 20 controls the rolling stand 2 and the cooling means 3 and has a valve pattern determination unit 21.
The valve pattern determination unit 21 uses the transformation heat generation prediction model for predicting the transformation heat generation amount generated in the rolled material W by cooling by the cooling means 3 and the temperature of the rolling material W using the transformation heat generation amount predicted by the transformation heat generation prediction model. And a temperature prediction model for predicting. Using information such as the plate temperature, plate thickness, plate speed, etc. immediately after the exit of the rolling stand 2 (finish rolling stand) and these models, the valve pattern determining unit 21 calculates the predicted value and the target value of the winding temperature. Processing (dynamic control) for calculating an appropriate value of the number of open valves in each cooling bank 9 is performed so that the difference is equal to or less than a predetermined value.

Further, the valve pattern determining unit 21 uses the measured value (actual value of the intermediate temperature) of the intermediate thermometer 10, the transformation heat generation prediction model, and the temperature prediction model to calculate the value of the number of opened valves (intermediate thermometer 10 To the outlet side of the cooling means 3) is corrected by dynamic control.
The value of the number of opened valves calculated and corrected by the valve pattern determining unit 21 is sent to the valve opening / closing signal output unit 24. The valve opening / closing signal output unit 24 opens and closes the valves of each cooling bank 9 according to the value of the number of opened valves, and changes the cooling state of the entire cooling means 3.

In the case of the present embodiment, the control unit 20 is configured by a process computer, and the valve opening / closing signal output unit 24 is configured by a sequencer, a PLC, or the like. In addition, various data can be transferred to the control unit 20 from the host computer 25.
[Temperature prediction model]
Next, prediction of the winding temperature of the rolled material W executed by the valve pattern determination unit 21 will be described.

As described above, the valve pattern determination unit 21 calculates a temperature drop from the exit side of the final rolling stand 2 to the winding device 4, and the cooling bank in the cooling means 3 (especially, the downstream side of the intermediate thermometer 10). Change the number and pattern of open valves in 9.
The temperature prediction model used for the temperature drop calculation is as shown in Equation (1).

Based on the equation (1), the temperature drop in the cooling means 3 is calculated for each cooling bank 9.
In this equation (1), the transformation calorific value Q exists as a variable, and this transformation calorific value Q is the sum of the calorific value associated with the change in structure and the calorific value associated with the change in magnetic state. The amount of heat generated by the structural change is the amount of heat generated at the time of transformation, although the steel material immediately after the final rolling is in the austenitic state, but as the rolled material W (steel plate) is cooled, it transforms into a structure such as ferrite or pearlite. It is. The calorific value associated with the change in the magnetic state is the calorific value generated at the time when a magnetic transformation that changes from a paramagnetic material to a ferromagnetic material occurs as the rolled material W (steel plate) is cooled.

The heat transfer coefficient α in the formula (1) may adopt a physical property value or may be obtained from a past actual value. From the temperature T (plate temperature) of the rolled material W and the water density w from the open valve, it can be expressed as α = k · f (T, w) using a functional form, and calculated using this equation. Good.
[Transformation heat generation prediction model]
Next, a method for obtaining the transformation heat generation amount Q existing in the temperature prediction model (formula (1)), that is, the transformation heat generation prediction model will be described.

  As is well known, in the classical nucleation theory, the nucleation rate I depends on the temperature T as expressed by the equation (2).

Therefore, the ferrite transformation rate x also depends on the temperature T, and in particular, the time change dx / dt of the ferrite transformation rate from the position of the intermediate thermometer 10 to the winding device 4 is the actual value of the intermediate temperature. It turns out that it depends.
From such knowledge, it is known that the transformation calorific value Q can be expressed as in Equation (3) by using the change rate dx / dt of the ferrite transformation rate, and by using this Equation (3), It is possible to calculate the transformation calorific value Q.

  Although the ferrite transformation rate can be expressed by a complicated expression, in this embodiment, an approximate expression represented by Expression (4) or Expression (5) is adopted.

In summary, the ferrite transformation rate is obtained (formula (4) or formula (5)) using the actual value (intermediate temperature actual value) in the intermediate thermometer 10 provided in the cooling means 3. The transformation heat generation amount Q generated between the intermediate thermometer 10 and the winding device 4 is obtained by using the equation (3) from the ferrite transformation rate, and the temperature prediction model (formula ( According to 1)), a predicted value of the winding temperature of the rolled material W can be obtained.
[How to determine the number of open valves]
Next, a process (dynamic control) for controlling the cooling means 3 so that the deviation between the estimated value of the winding temperature obtained by the equation (1) and the target value of the winding temperature is not more than a predetermined value. explain.

This processing is performed by the valve pattern determination unit 21 based on the flowchart shown in FIG. The rolled material W is divided into virtual short plates (cut plates) in the longitudinal direction, and the following processing is performed on the respective cut plates.
First, in S <b> 1 of FIG. 2, the intermediate temperature actual value of a certain cut plate is detected by the intermediate thermometer 10.

Next, in S2, the time constant _TF of the ferrite transformation rate in the detected intermediate temperature actual value is calculated. For the calculation, a linear linear expression as shown in Expression (6) is used.

As a derivation method of Equation (6), in the case of the present embodiment, first, the time constant T of the ferrite transformation rate that minimizes the prediction error at the coiling temperature using the cooled actual data (past rolling actual data). The value of _F (defined as the optimal time constant) is calculated for each steel plate.
Then, the calculated optimal time constant _TF and the actual intermediate temperature value at that time are stored in a database for each steel type as shown in FIG. This database is stored in the control unit 20. Then, using this database, for each steel type, the relationship between the time constant _TF of the ferrite transformation rate and the intermediate temperature actual value is approximated by a linear linear expression using a regression method or the like. Derived.

Next, in S3, the rolled material W is wound from the intermediate thermometer 10 using the formula (4) or the formula (5) based on the time constant _TF of the ferrite transformation rate calculated by the formula (6). The ferrite transformation rate x up to the temperature is obtained.
In S5, using the ferrite transformation rate x calculated in S4, temperature history prediction from the intermediate temperature to the coiling temperature based on the formula for predicting the temperature drop (formula (1) and formula (3) for the transformation heat generation amount Q) Perform the calculation.

  In S6, based on the obtained estimated value of the winding temperature, the number of opened valves is increased or decreased until the deviation between the predicted value and the target value of the winding temperature is equal to or lower than a certain threshold temperature (for example, 5 ° C.). As a result, the valve opening / closing pattern is determined in S7. The initial value of the valve opening / closing pattern is set in S4. The initial setting pattern of valve opening / closing may be a valve opening / closing pattern set in dynamic control in order to reduce the calculation load.

4 to 6 show the results of rolling by adopting the cooling control method for the rolled material W according to the present invention.
FIG. 4 shows the probability (± 30 ° C. middle rate) that the coiling temperature falls within the range of ± 30 ° C. over the entire length of the steel plate (rolled material W) when rolling high carbon steel. is there. As is apparent from this figure, by using the present invention, the average rate of ± 30 ° C. of the winding temperature was improved from 85% in the conventional control method to 92%.

  FIG. 5 shows that when rolling high carbon steel, the coiling temperature falls within a range of ± 30 ° C. with respect to the tip of the steel plate (rolled material W) (the portion from the most advanced portion of the rolled material W to about 200 m). The probability (± 30 ° C mean) is shown. As is apparent from this figure, by using the present invention, the mean ratio of the winding temperature of ± 30 ° C. was greatly improved from 75% in the conventional control method to 88%.

  FIG. 6 shows the temperature distribution in the longitudinal direction of the steel plate (rolled material W) when rolling high carbon steel. In the conventional cooling control, a situation has occurred in which the actual value of the winding temperature deviates from the allowable temperature tolerance at the front end of the steel plate. However, by applying the cooling control method of the present invention, the actual value of the coiling temperature is surely within the allowable temperature tolerance at the tip of the steel sheet, and the tolerance median of the coiling temperature is reduced. You can see that it is improving.

By using the cooling control method for the rolled material W described above, it is possible to accurately calculate the amount of transformation heat generated when the rolled material W is cooled, and to accurately predict the plate temperature (winding temperature) of the rolled material W. As a result, the cooling control of the rolled material W can be reliably performed.
The embodiment disclosed this time should be considered as illustrative in all points and not restrictive. In particular, in the embodiment disclosed this time, matters that are not explicitly disclosed, for example, operating conditions and operating conditions, various parameters, dimensions, weights, volumes, and the like of a component deviate from a range that a person skilled in the art normally performs. Instead, values that can be easily assumed by those skilled in the art are employed.

DESCRIPTION OF SYMBOLS 1 Continuous rolling mill 2 Rolling stand 3 Cooling means 4 Winding device 5 Work roll 6 Backup roll 7 Delivery side plate speed detector 8 Delivery side thermometer 9 Cooling bank 10 Intermediate thermometer 11 Winding thermometer 12 Delivery side thickness gauge 13 Winding Take-off speed detector 20 Control unit 21 Valve pattern determination unit 24 Valve open / close signal output unit 25 Host computer W Rolled material

Claims (4)

Using a cooling means for water-cooling the rolled material, when cooling so that the winding temperature of the rolled material after rolling becomes a target value,
The transformation heat generation prediction model that predicts the transformation calorific value that occurs in the rolled material during cooling using the ferrite transformation rate of the rolling material, and the temperature that predicts the temperature of the rolling material using the transformation calorific value predicted by this transformation heat generation prediction model Prepare a prediction model,
Obtain the temperature of the rolled material in the middle position of the cooling means as an intermediate temperature actual value,
Using the acquired intermediate temperature actual value to determine the ferrite transformation rate,
The transformation heat generation prediction model using the obtained ferrite transformation rate predicts the transformation heat generation occurring downstream from the position where the intermediate temperature actual value was obtained, and rolling by the temperature prediction model using the predicted transformation heat generation amount Obtain the predicted value of the material winding temperature,
A rolling material cooling control method, wherein the cooling means is controlled so that a difference between a predicted value and a target value of the winding temperature is equal to or less than a predetermined value. The ferrite transformation rate is calculated by an equation including a time constant of the ferrite transformation rate as a variable,
The method for controlling cooling of a rolled material according to claim 1, wherein the time constant of the ferrite transformation rate is determined using an expression expressed as a linear linear expression based on actual intermediate temperature values. The cooling means has a configuration provided with a plurality of cooling banks capable of changing the number of open valves,
The cooling of the rolling material according to claim 1 or 2, wherein the number of open valves of the cooling bank is changed so that a difference between a predicted value of the coiling temperature and a target value is not more than a predetermined value. Control method. A plurality of rolling stands for rolling the rolled material;
A cooling means arranged on the downstream side of the rolling stand to cool the rolled material with water;
An intermediate thermometer provided in the middle of the cooling means;
A winding device for winding the rolled material cooled by the cooling means;
Control for controlling the cooling means by performing the cooling control method for a rolled material according to any one of claims 1 to 3 so that a difference between a predicted value of a coiling temperature and a target value is not more than a predetermined value. And
A continuous rolling mill characterized by comprising: