JP2692544B2 - Method and device for controlling temperature of hot rolling mill - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a temperature control method and apparatus for a hot rolling mill which makes the temperature on the delivery side of the hot finishing mill uniform.

[0002]

2. Description of the Related Art The outlet temperature of a hot continuous rolling mill, for example, a hot continuous finishing mill, generally fluctuates in the longitudinal direction from the top to the bottom of the strip. Various methods have heretofore been disclosed for temperature control for making the exit side temperature of the finish rolling mill uniform.

Japanese Unexamined Patent Publication (Kokai) No. 58-181407 discloses a temperature control method in which the water injection amount is changed by using a thermometer on the delivery side of the finishing rolling mill and the rolling pressure of each finishing rolling mill.
That is, the present method, the hot strip in the finish rolling mill, in association with the temperature distribution in the longitudinal direction or the rolling pressure distribution corresponding thereto, the amount of water injection between the stands of the finishing rolling mill at a high temperature portion or a low rolling pressure portion corresponding thereto. This is a hot rolling finish temperature control method in which the temperature fluctuation width in the longitudinal direction of the hot strip is reduced to a large extent.

In this publication, the water injection amount between the stands of the finish rolling mill is changed based on the temperature on the delivery side of the finish rolling mill as described above, but the cooling device between the rolling stands occurs on the surface of the steel sheet. Since it has a function to remove iron oxide, the sprays that can be used are limited.In addition, the plate thickness is thin in the latter stand, and the plate thickness fluctuates greatly by turning the spray between the stands on and off. Often limited to stands. However, even if a water injection command is output from the rolling mill exit side to the upstream stand, there is a problem in that it takes a long time from the water injection until the temperature measurement and good temperature control cannot be obtained.

In Japanese Patent Laid-Open No. 58-23509, the third
There has been proposed a temperature control method and apparatus for a hot rolling mill, which measures the temperature of the rolled material on the stand exit side and changes the rolling speed. That is, in the temperature control method of the hot rolling mill that controls the rolling temperature of the hot rolling mill by operating the rolling temperature of the hot rolling mill that rolls the heated rolling material, A temperature control means for operating the rolling speed depending on the temperature deviation between the target temperature of the rolled material and the temperature of the outgoing rolled material is provided, and the transfer function from the change of the rolling speed to the change of the outgoing rolled material temperature is delayed by a first order. As a system, the loop gain of the temperature control system becomes constant with the amplification factor of the temperature control means depending on the inlet side rolling material temperature of the hot rolling mill and the roll peripheral speed of the rolling stand or the rolling speed of the rolling material. Is a method for controlling the temperature of a hot rolling mill configured to correct the

In the temperature control device of the hot rolling mill for controlling the temperature of the outgoing rolling material of the hot rolling mill by controlling the rolling temperature of the hot rolling mill for rolling the heated rolled material, A temperature control circuit for operating the rolling speed according to a temperature deviation signal between the target temperature signal of the side rolled material temperature and the output side rolled material temperature detection signal is provided, and the incoming side rolled material temperature detection signal and rolling of the hot rolling mill are provided. Hot rolling comprising an operation control circuit that corrects the time constant of the temperature control circuit so that the loop gain of the temperature control system becomes constant by the roll peripheral speed detection signal of the stand or the rolling speed detection signal of the rolled material. It is the temperature control device of the machine.

[0007] In this publication, the temperature is measured on the outlet side of the third stand and the rolling speed is changed. However, the temperature at the completion of rolling is important in order to secure a good material in the finish rolling mill. Therefore, it may not be possible to obtain a sufficient material only by measuring the temperature on the outlet side of the third stand. Further, the rolling speed has a great influence on the material thickness and the cooling device after the finish rolling mill in the hot rolling line, and it is not realistic to change the rolling speed.

Further, Japanese Patent Laid-Open No. 62-6713 discloses that
When controlling the temperature of the rolled material immediately after hot rolling, the rolling position obtained from each rolling stand, the rolling load, and the rolling data of the inlet side plate thickness are used to determine the temperature change amount of the rolled material of each stand, and the temperature change The amount of cooling water between the stands is determined based on the amount, and the cooling device between the stands is controlled according to the amount of cooling water to make the temperature of the rolled material uniform in the longitudinal direction. A material exit temperature method is disclosed.

In this publication, the material temperature is calculated from the rolling position, rolling load, etc., but in the rolling phenomenon, the material temperature greatly differs due to external factors such as material composition, roll temperature, roll material, etc. It is difficult to accurately estimate the best temperature with the formula described in (3). Further, since the method is described in the form of deviation from the reference value, it is possible to eliminate the temperature variation in the material due to the material skid or the like, but there is no guarantee that the resulting temperature is the target value.

Further, in JP-A-4-13414, when a material to be rolled is passed through a hot continuous rolling mill having a plurality of stands, the strip is controlled in the hot continuous rolling mill to control the thickness of the material to be rolled. In the plate thickness control method at this time, a thickness gauge and a thermometer are installed between at least two stands, and when the tip of the rolled material passes, the plate thickness and surface temperature of the rolled material are detected, and this temperature is detected. The rolling temperature of the material to be rolled in the next stand roll bite is predicted from the detected value, and the deviation between the predicted value of the rolling temperature of the material to be rolled and the preset target value is preset as the detected value of the plate thickness. When it is predicted that the shape of the material to be rolled will be disturbed when the rolling position of the next stand is corrected based on the deviation from the target value, it is necessary to continuously limit the rolling position correction amount. Characteristic of continuous hot rolling mill The thickness control method is disclosed. However, although this publication proposes to install a thermometer between the stands, this method is a method for controlling the plate thickness at the time of passing the plate, and does not mention the temperature control.

[0011]

DISCLOSURE OF THE INVENTION The present invention provides a temperature control method and apparatus for a hot rolling mill capable of solving the above problems of the prior art and controlling the temperature so as to quickly obtain a required finishing target temperature. The purpose is to do.

[0012]

According to a first aspect of the present invention, in a temperature control method for a hot rolling mill, a thermometer is provided inside and outside the continuous finishing mill, and a cooling device is provided inside the finishing mill.
As the temperature target value in the finish rolling mill, a linear expression of the finish rolling mill output side target temperature, the finish actual measurement temperature, and the strip passing target temperature and the strip passing actual velocity is given as follows, and the target value and the temperature measurement value are It is a temperature control method for a hot rolling mill, characterized in that the water injection amount of the cooling device is changed according to the deviation.

[0013]

(Equation 3)

A second aspect of the present invention is, in a temperature control device for a hot rolling mill, a thermometer is provided inside and outside the continuous finishing rolling mill, and a cooling device is provided inside the finishing rolling mill. The value calculated by the calculation device shown below and the calculation device for calculating the linear expressions of the target temperature of the finishing rolling mill, the measured actual temperature of the finishing mill, and the target temperature of the strip and the actual measured speed of the strip. An arithmetic and control unit for arithmetically controlling the deviation by means of the above, and a control amount arithmetic unit for arithmetically operating the deviation between the finish rolling mill outlet side measured temperature and the target value are provided, and by the deviation between the target value and the temperature measured value, It is a temperature control device for a hot rolling mill, which is characterized by controlling a water injection amount of a cooling device.

[0015]

(Equation 4)

[0016]

According to the present invention, in order to solve the above-mentioned problems, one or more temperature measuring devices are provided in the finishing rolling mill, and the target value at which the finishing outlet temperature is optimal for the material is expressed by the following formula. To give to.

[0017]

(Equation 5)

[0018]

(Equation 6)

The control device and the detection device are obtained by obtaining the deviation from the temperature actually measured by the thermometer with respect to this target value and changing the water injection amount of the cooling device close to the thermometer by the output of the control amount calculation device (PID calculation). It is possible to reduce the delay time of, the temperature control can be performed with high accuracy, and the temperature of the steel strip on the delivery side of the rolling mill can be kept constant.

[0020]

EXAMPLE Next, an example of the present invention will be described with reference to FIG. FIG. 1 is an explanatory diagram of a configuration of a temperature control device according to an embodiment of the present invention, and FIG.
In the figure, 1 is a thermometer on the exit side of the finish rolling mill, 2 is a thermometer inside the finish rolling mill, 3 to 6 are cooling devices between the stands of the finish rolling mill, and 7 is a computing device for computing a target temperature inside the finishing rolling mill. , 8 is a control amount calculation device for calculating and controlling the deviation based on the target value given by 7 and the finish rolling mill outlet side temperature measured by the finish rolling mill internal temperature meter 2, and 9 is a finish rolling mill outlet side thermometer 1. Control quantity computing devices for computing the deviation between the measured finish outlet temperature and the target value, and 10-12 are finish rolling mills.

Next, the control amount computing device 8 computes a deviation based on the value given by the rolling mill internal temperature target value computing device 7 and the temperature calculated by the finishing rolling mill thermometer 2, and a control computing device such as a PID controller, for example. The control amount is calculated and a command is output to the sprays 3 to 6 between the stands. Further, the control amount computing device 9 from the finish rolling mill outlet side thermometer 1 is a device for computing the deviation between the finish rolling mill outlet side temperature measured by the finish rolling mill outlet side thermometer 1 and the target value. Arithmetic device 7
This is a device that gives a correction term for the target value of the intermediate temperature of.

Conventionally, a plurality of hot rolling mills 10, 11, 12 are arranged so that the temperature of the exit side thermometer 1 of the finish rolling mill reaches a target value.
Was controlling. In the present invention, the thermometer 2 installed in the finish rolling mill is installed in one or more places between the stands of the rolling mill. The thermometer 2 in the finish rolling mill measures from the upper surface or the lower surface of the steel plate.

In the present invention, the target temperature value T _{maim in the} finish rolling mill is _set.
The following 1 of the target temperature T _faim of the finishing rolling mill, the actual measurement temperature T _fact of the finish rolling, and the target strip _running temperature T _f and the actual strip _running speed are given below.
The target value T for the thermometer in the finish rolling mill is given by the following equation:
_Maim is given, and control is performed as shown in the explanatory diagram of the control flow of FIG. 2 _according to the deviation between the target value T _maim and the temperature measurement value T _mact to change the water injection amount of the cooling device.

[0024]

(Equation 7)

Further, it is desirable that the temperature gauge 2 in the finish rolling mill has the same positional relationship between the exit thermometer 1 of the finish rolling mill and the rolling mill as much as possible. Since the correction is performed according to the exit temperature, the same effect can be obtained even if it is not necessarily the same. The cooling devices 3, 4, 5, 6 installed between the stands are cooled by a spray method using a cooling medium such as water. FIG. 3 shows a calculation example using the target temperature value calculating device 7 in the rolling mill. At the start of control, T _maim is a _term of T _faim + T _mf only. As the speed increases in the section

[0026]

(Equation 8)

In the section, since the actual value of T _f is _{deviated from the} target value, T _maim is changed by the PID arithmetic unit. FIG. 4 shows the temperature at the exit side of the finishing rolling mill when the control of the present invention is carried out for a general carbon steel material (4.0 mm × 1683 mm). As shown in FIG. 4, in the case of control (off), the temperature rises from the front end to the rear end of the material due to acceleration, whereas when this control is applied, even if the rolling conditions are the same, the target You can see that the value is controlled.

FIG. 5 shows an evaluation based on statistical data when the control according to the present invention is applied to materials under the same rolling conditions. Here, N is the number of tests, X _mean is the average value of the actual temperature-the target temperature over the longitudinal direction, and the on-gauge ratio is the ratio of the part within ± 10 ° C and ± 15 ° C of the target value in the total length. ing. As shown in FIG. 5, by applying the control method of the present invention, the average value X _mean of the actual temperature-the target temperature in the longitudinal direction is lowered by 3.5 ° C., and the on-gauge ratio is ± 10 ° C. and the on-gauge ratio is ± 15 ° C. 52.1% each
To 78.9% and from 82.1% to 94.5%.

[0029]

According to the temperature control method and apparatus of the hot rolling mill of the present invention, a thermometer is provided in the rolling mill so that the finish rolling mill outlet side temperature becomes a predetermined target temperature with respect to this thermometer. Since the setting is provided, the temperature detector to the control device can be controlled in a short time, so that the temperature in the longitudinal direction of the steel strip becomes extremely uniform and the finishing outlet temperature becomes a predetermined target temperature, so that a steel strip of a good material can be obtained. The effect is obtained.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram of a configuration of a temperature control device that is an embodiment example of the present invention.

FIG. 2 is an explanatory diagram of a control flow in the embodiment of the present invention.

FIG. 3 is an explanatory diagram of a calculation example using the target value calculation device according to the embodiment of the present invention.

FIG. 4 is an explanatory diagram of a finish rolling mill outlet temperature in an example of the present invention.

FIG. 5 is an explanatory diagram of statistical results of results when the present invention is used.

[Explanation of symbols]

 1 Rolling Mill Outgoing Side Thermometer 2 Finishing Rolling Inside Thermometer 3 Cooling Device 4 Cooling Device 5 Cooling Device 6 Cooling Device 7 Rolling Mill Inside Temperature Target Value Calculator 8 Controlled Volume Calculator 9 Controlled Volume Calculator from Finishing Side Thermometer 10 Finishing Rolling Machine 11 Finishing Rolling Machine 12 Finishing Rolling Machine

Claims (2)

(57) [Claims] 1. A temperature control method for a hot rolling mill, comprising a thermometer in the continuous finishing rolling mill and at the outlet side and a cooling device in the finishing rolling mill, and the finishing rolling mill output as a target temperature value in the finishing rolling mill. The linear expressions of the side target temperature and the measured finish temperature, and the plate passing target temperature and the plate passing measured speed are given as follows.
A temperature control method for a hot rolling mill, characterized in that a water injection amount of the cooling device is changed according to a deviation between the target value and a temperature measurement value. (Equation 1) 2. A temperature controller for a hot rolling mill, wherein a thermometer is provided inside and on the exit side of the continuous finishing mill and a cooling device is provided inside the finishing mill, and the target temperature value in the finishing rolling mill is set to the exit side of the finishing mill. To calculate and control the deviation based on the target temperature, the actual measurement temperature for finishing, and the primary temperature of the strip running and the linear equation of the strip running speed by the formula shown below, and the temperature calculated by the thermometer inside the rolling mill. Arithmetic control device of
It is characterized in that a control amount calculation device for calculating a deviation between a finish rolling mill outlet side measured temperature and a target value is provided, and the water injection amount of the cooling device is controlled by the deviation between the target value and the temperature measurement value. Temperature controller for hot rolling mill. (Equation 2)