JPH11267730A - Device for controlling temperature of hot rolled sheet and its method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a technology for controlling temperature of hot rolled sheet with high accuracy. SOLUTION: A thermometer 8 to measure the temperature of a sheet 2 is arranged between stands 1d and 1e of a tandem finishing mill 1, and based on measured values of the thermometer 8, each of cooling water amounts supplied to the sheet 2 respectively from cooling devices 4a, 4b on the upstream side of the location of the thermometer 8 in the direction of transportation is adjusted by feed back control At the same time, each of cooling water amounts supplied to the sheet 2 respectively from a cooling devices 4e, 4f between stands on the downstream side of the location of the thermometer 8 and from a cooling device 7 located along a hot run table is adjusted by feed forward control.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an apparatus and a method for controlling the temperature of a hot-rolled steel sheet.

[0002]

2. Description of the Related Art In determining the mechanical properties and quality of a product material of a hot-rolled steel sheet, the temperature immediately after finishing rolling of the steel sheet and the temperature immediately before winding are important factors. It is important to control.

Here, in the hot finishing rolling line, for example, as shown in FIG. 2, a finishing tandem rolling mill 1, a hot run table, and a winding device 3 are arranged in this order along a pass line.

[0004] Cooling of hot-rolled steel sheet 2 (temperature control)
Is performed by the cooling devices 4a to 4f installed between the stands 1a to 1g of the finishing mill 1 and the cooling equipment 7 installed at the hot run table (not shown) after the finish rolling. I have.

[0005] The controller 51 controls the temperature of the exit position of the finishing tandem rolling mill by using, for example, information measured or predicted by a thermometer 50 installed on the entrance side of the finishing tandem rolling mill or information on a conveying speed pattern. By controlling the valve opening of each of the cooling devices 4a to 4f via the valve opening adjusting device 52, feedforward control for increasing or decreasing the amount of cooling water supplied to the steel plate 2 from each of the cooling devices 4a to 4f, The cooling is performed by adjusting the amount of cooling water supplied to the steel plate 2 from each of the cooling devices 4a to 4f by feedback control based on the measurement value of the thermometer 54 installed on the exit side of the finishing mill 1.

Here, conventionally, the stand 1
The cooling devices 4a to 4f arranged between a to 1g are used only when the adjacent stand is used for rolling. That is, cooling after the finish rolling is not performed between the stands.

The temperature control immediately before winding is performed by the controller 51 by the controller 51 based on the measurement value measured by the thermometer 54 disposed on the exit side of the finishing mill 1.
3, feed-forward control for adjusting the amount of cooling water by the cooling equipment 7 installed at the hot run table position, and a winding thermometer 5 installed in front of the winding device 3.
Based on the measurement of No. 5, feedback control is performed to adjust the amount of cooling water.

[0008]

In the hot finish rolling line, for example, when manufacturing a steel plate 2 called an extremely thick material having a product plate thickness of 15 mm or more, the stands 1a to 1g of the finish rolling mill 1 are required. Of these, the first stand, for example, 1a to 1c up to the third stand, is used for rolling, and the fourth and subsequent stands, 1d to 1g, are not used for rolling.

In such a case, in the conventional temperature control based on the measured value of the thermometer 54 on the exit side of the finishing mill 1,
For example, as shown in FIG. 3, since cooling water is not supplied from the cooling devices 4c to 4f arranged between the stands 1d to 1g that are not used for rolling, finishing is performed from the finishing pre-stand (for example, the third stand 1c). There is a delay in response until the position of the output thermometer 54 of the rolling mill 1 is reached.

That is, the temperature is measured on the exit side of the finishing mill 1 and the cooling device 4 between the stands 1a to 1c during the finish rolling is performed.
When the increase and decrease of the cooling water due to a and 4b are adjusted by the feedback control, the dead time of the control is long. Therefore, for example, when feedback control is started, control is not applied to the steel plate 2 located on the thermometer 54 from the third stand 1c exit side to the finishing mill 1 exit side, and the accuracy cannot be improved. There is.

In the conventional temperature control, since the steel sheet 2 is rolled at the third stand 1c and cooled after finishing rolling is completed again after the steel sheet 2 reaches the hot run table position, the cooling from the third stand 1c exit side. Until it reaches the hot run table position, it is in an air-cooled state (non-cooled state).
There is also a problem that the strength of the steel is reduced.

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and has as its object to provide a highly accurate temperature control technique for a hot-rolled steel sheet.

[0013]

According to a first aspect of the present invention, there is provided a temperature control apparatus for a hot-rolled steel sheet, comprising a finishing tandem rolling mill along a pass line through which the steel sheet is conveyed. , A hot run table, and a winding device are arranged, a cooling device is disposed between the stands of the rolling mill, and a cooling device is disposed at the hot run table position, between the stands of the tandem rolling mill. A thermometer disposed at at least one location to measure the temperature of the steel sheet, and cooling supplied to the steel sheet from a cooling device on the upstream side in the transport direction from the position of the thermometer based on the measurement value of the thermometer. The amount of water is adjusted by feedback control, and at least one of the cooling devices between the stands on the downstream side in the transport direction from the position where the thermometer is arranged and the cooling device at the hot run table position is used. A controller for adjusting the amount of cooling water supplied from the cooling device to the steel plate between the command feedforward control and is characterized in that it comprises.

Next, a temperature control method for a hot-rolled steel sheet according to a second aspect of the present invention measures the temperature of the steel sheet at at least one position between a plurality of stands of a finishing tandem rolling mill for manufacturing a hot-rolled steel sheet, and measures the temperature. Based on the value, feedback control for adjusting the amount of cooling water supplied to the steel sheet on the upstream side in the traveling direction from the temperature measurement position, and a cooling device between stands and the hot run table position on the downstream side in the traveling direction from the temperature measurement position And at least one of feed-forward control for adjusting the amount of cooling water supplied to the steel sheet from the cooling device between the stands is performed.

According to the present invention, the temperature of a steel sheet is measured between stands of a finishing tandem rolling mill for producing a hot-rolled steel sheet, and cooling supplied to the steel sheet on the upstream side in the traveling direction by feedback control based on the measured value. Since the amount of water is changed, even when the stand used for rolling is only the preceding stand, control with a small dead time can be performed, and the accuracy of controlling the temperature of the steel sheet immediately after finish rolling can be increased.

Further, since the amount of cooling water supplied to the steel sheet on the downstream side in the transport direction is changed by feedforward control based on the measured value of the thermometer, even if the stand used for rolling is only the preceding stand, Since the water cooling is performed during the transportation to the hot run table, the non-water-cooled area is reduced to prevent the steel sheet from becoming recrystallized and grain enlarged, and the steel sheet can have a predetermined strength required as a product.

[0017]

Next, embodiments of the present invention will be described with reference to the drawings. The basic configuration of the hot finish rolling line of the present embodiment is almost the same as the conventional one, and as shown in FIG. 1, a finishing tandem rolling mill 1, a hot run table, and a winding machine are arranged along a pass line for conveying a steel sheet 2. The devices 3 are arranged in this order.

The finishing tandem rolling mill 1 is a finishing rolling facility in which a plurality of stands 1a to 1g (seven stages are illustrated in FIG. 1) are arranged in parallel.
Between g, cooling water headers 4a to 4f constituting the cooling devices are arranged, and cooling water can be supplied toward the steel plate 2 from nozzles provided in the headers 4a to 4f.

The amount of cooling water supplied to each of the headers 4a to 4f is changed by adjusting the opening of a valve (not shown), and the opening of the valve is adjusted based on signals from the opening adjusting devices 5 and 6, respectively. Is being done.

Further, a cooling device 7 is arranged also at the hot run table position on the exit side of the rolling mill 1, and the amount of cooling water is changed based on a signal from the opening adjustment device 6.

A thermometer 8 is arranged between the fourth stand 1d and the fifth stand 1e in the rolling mill 1. The thermometer 8 measures the temperature of the steel plate 2 and supplies a measurement signal to the controller 9.

The controller 9 is supplied in advance with a target temperature on the exit side of the finishing tandem rolling mill and a target temperature for winding in accordance with the quality of the product and the like. The controller 9
The cooling water amount supplied from the cooling water headers 4a and 4b upstream of the thermometer 8 based on the measurement value of the thermometer 8 so that the target temperature on the exit side of the finishing tandem rolling mill is obtained. The adjustment is performed by feedback control via the opening adjustment device 5. At the same time, the cooling water is supplied from the headers 4e and 4f for the cooling water between the stands 1e to 1g on the downstream side of the thermometer 8 based on the measurement value of the thermometer 8 so that the target temperature at the time of the winding is attained. The amount of cooling water and the amount of cooling water supplied from the cooling device 7 at the position of the hot run table are adjusted by feedforward control via the opening degree adjusting device 6.

In the finishing line equipped with the temperature control device having the above-described configuration, for example, when manufacturing an extremely thick steel plate 2 having a thickness of 15 mm, etc.
Rolling is performed only on the three stands 1a to 1c,
The exit side of the stand 1c is the actual exit side of finish rolling.

At this time, in this embodiment, since the temperature of the steel plate 2 is measured between the fourth stand 1d and the fifth stand 1e, the temperature of the finish rolling side can be measured earlier than before. Since the amount of cooling water from the cooling headers 4a and 4b on the upstream side can be adjusted based on the temperature, the time delay is smaller than in the conventional case, and the control response is improved.

Further, since the cooling water is supplied by the feedforward control from the cooling water headers 4a to 4f disposed between the stands 1d to 1g which are not used for rolling, the hot run is performed after the end of the actual finish rolling. The air cooling holding time until the start of water cooling by the cooling device 7 at the table position was a short time required to pass through one stand, and the state of crystal grains which were relatively small due to the rolling of the steel plate 2 was maintained, and the product was obtained. Sufficient strength is ensured for the coil.

Here, in the description of the above embodiment, the case where the rolling is carried out in the three stands 1a to 1c of the former stage in the rolling mill 1 has been described.
Even when rolling is performed using up to 1b or up to four stands 1a to 1d, the above-described temperature control improves control responsiveness as compared with the conventional case. Further, since the air-cooling holding area is small, sufficient strength is ensured for the product coil.

In the above embodiment, the stands 1a to 1a
Based on the value measured by the thermometer 8 for 1 g, feedback control of water cooling by the cooling device 7 at the position of the hot run table is also performed. It may be performed by feedback control or feedforward control based on the measurement values of the thermometers 21 and 22 installed before.

In the above embodiment, the stands 1d to
The feedback control is performed on the upstream side by the thermometer 8 disposed between 1e and the feedforward control is performed on the downstream side.
The temperature on the entrance side of the finishing tandem rolling mill is measured, and feedforward control based on the measured value is used together. For cooling downstream from the thermometer 8, the temperature on the outlet side of the hot run is measured, and feedback based on the measured value is performed. The control may be used in combination to further improve the accuracy of the temperature control.

Further, based on the measured value of the thermometer 8, only feed-forward control of the amount of cooling water supplied downstream of the thermometer 8 is performed, and cooling via the headers 4a-4b upstream of the thermometer 8 is performed. As for the adjustment of the water amount, the temperature on the entrance side of the finishing tandem rolling mill may be measured by another thermometer 23, and the temperature may be adjusted by feedforward control based on the measured value.

In the same manner as in the prior art, the value measured by the thermometer 21 on the exit side of the finishing tandem mill 1 is transferred to the controller 9.
And based on the measurement values of the thermometer 8 disposed between the stands 1d to 1e, only the feedback adjustment of the amount of cooling water supplied by the headers 4a and 4b upstream of the thermometer 8 is performed. The amount of cooling water supplied from the headers 4e and 4f downstream of the thermometer 8 is feedback-controlled based on the value measured by the outlet thermometer 21 and supplied from the cooling device 7 based on the value measured by the outlet thermometer. The adjustment of the cooling water amount to be performed may be performed by feedforward control.

In the above embodiment, the fourth stand 1
Although the example in which the thermometer 8 is arranged only between the d and the fifth stand 1e is described, the thermometer is individually arranged between the plurality of stands 1a to 1g, and depending on the number of stands used for rolling. The thermometer used for the control may be changed.

[0032]

EXAMPLE In a finishing tandem rolling mill 1 having 7 stands 1a to 1g, a product having a thickness of 15 mm
An example in which temperature control based on the present invention is performed in the case of manufacturing using the third to third stands 1a to 1c will be described.

Here, the strength required for this product is 55
± 5 kgf / mm ² , and the finish output side temperature at this time is 85
The temperature was controlled to 0 ± 40 ° C. and the winding temperature target to 600 ± 40 ° C.

As a conventional example, in the configuration shown in FIG. 3, the controller 52 calculates the amount of correction of the amount of supplied water between the stands 1a and 1b and between the stands 1b and 1c from the value measured by the finishing thermometer 54. Calculate and perform the valve control via the opening adjustment device 52 to perform feedback control,
Similarly, in the cooling of the hot run table position, the controller 51 calculates the correction amount of the cooling water supply and performs a valve operation via the opening degree adjusting device 53 to perform a temperature control method of performing feedforward control for comparison. It was carried out.

When the conventional temperature control is performed,
As shown in FIG. 4, even if the finishing side temperature higher than the target is detected at the tip end of the steel plate 2 and the supply amount of the cooling devices 4 a and 4 b is increased, the increase of the supply amount has already occurred after the third stand 1 c. Was not reflected on the steel plate portion in the above, and the finish-side temperature rose to 900 ° C. at the maximum. Also, the third stand 1
After rolling at c, the cooling equipment 7 at the hot run table position
During a period of 7 seconds until the steel sheet 2 was reached, cooling water was not supplied to the steel sheet 2 and the steel sheet 2 was kept at a high temperature. As a result, the strength of the obtained product is as shown in FIG. 6, and the target strength is 55 ± 5 kgf / mm ^2.
Was not obtained.

On the other hand, when the temperature control of the above embodiment according to the present invention is performed, the cooling after the fifth stand 1e is performed by feedforward control, and as shown in FIG. As soon as the finishing side temperature higher than the target is detected at the tip, the amount of water supplied by the cooling devices 4a and 4b is adjusted to increase while the dead time is short, and the portion where the increase in the amount of supply is not reflected is Because of the slight amount, the maximum value indicated by the thermometer 8 was 865 ° C. In addition, rolling at the first to third stands 1a to 1g,
After the temperature was measured between the 4th and 5th stands, water cooling was performed between the 5th and 6th stands and between the 6th and 7th stands in the cooling device 7 and the hot run cooling equipment. Took two seconds. For this reason, the crystal grains relatively small by the rolling were retained, and sufficient strength was obtained.

That is, the strength of the product is as shown in FIG. 7, and the target strength is 55 ± 5 kgf / mm ² over the entire length of the coil.
A tensile strength of less than or equal to was obtained. As described above, according to the present invention, the temperature at the end of finish rolling is controlled with high accuracy, and water cooling can be performed immediately after the end of finish rolling. Significantly improved. The yield of products having a thickness of 15 mm or more was conventionally about 88%, but has been improved to nearly 100% by the present invention.

[0038]

According to the present invention, the temperature of a steel sheet is measured between stands of a finishing tandem rolling mill for producing a hot-rolled steel sheet, an operation is performed based on the measured value, and feedback control is applied to the steel sheet on the upstream side in the carrying direction. Since the amount of cooling water to be supplied is changed, even when an extremely thick plate is manufactured, control with a small dead time can be performed, and the accuracy of controlling the temperature of the steel sheet immediately after finish rolling can be improved.

Further, since the calculation is performed based on the measured value of the thermometer disposed between the above-mentioned stands and the amount of cooling water supplied to the steel sheet on the downstream side in the transport direction is changed by the feedforward control, only the front stand is used. Even in the case of, water cooling is immediately performed after finishing rolling,
This prevents recrystallization grain enlargement and ensures the strength required as a product.

[Brief description of the drawings]

FIG. 1 is a conceptual diagram for explaining temperature control according to an embodiment of the present invention.

FIG. 2 is a conceptual diagram for explaining conventional temperature control.

FIG. 3 is a conceptual diagram for explaining conventional temperature control.

FIG. 4 is a diagram illustrating an example of conventional temperature control in a coil longitudinal direction.

FIG. 5 is a diagram for explaining an example of temperature control based on the present invention in the coil longitudinal direction.

FIG. 6 is a diagram illustrating an example of a product strength distribution in a coil longitudinal direction when a conventional temperature control is performed.

FIG. 7 is a diagram showing an example of product strength distribution in a coil longitudinal direction when temperature control according to the present invention is performed.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Tandem rolling mill 1a-1g Stand 2 Steel plate 3 Winding device 4a-4f Cooling device 5,6 Openness adjusting device 7 Cooling device 8 Thermometer 9 Controller

Claims (2)

[Claims] 1. A finishing tandem rolling mill, a hot run table, and a winding device are arranged along a pass line through which a steel sheet is conveyed. A cooling device is arranged between stands of the rolling mill, and a cooling device is disposed between the stands of the hot run table. A control device provided with a cooling device, wherein the thermometer is disposed at at least one location between the stands of the tandem rolling mill and measures the temperature of the steel sheet. Based on a measurement value of the thermometer, the thermometer is used. The amount of cooling water supplied to the steel sheet from the cooling device on the upstream side in the transport direction from the arrangement position is adjusted by feedback control, and the cooling device between the stands and the hot run table position on the downstream side in the transport direction from the arrangement position of the thermometer. A controller that adjusts the amount of cooling water supplied to the steel sheet from at least the cooling device between the stands by feedforward control, and A temperature control device for a hot-rolled steel sheet, comprising: 2. The temperature of a steel sheet is measured at at least one point between a plurality of stands of a finishing tandem rolling mill for producing a hot-rolled steel sheet, and based on the measured value, the temperature of the steel sheet is determined on the upstream side of the temperature measurement position in the transport direction. Feedback control for adjusting the amount of cooling water to be supplied to the steel sheet, and the amount of cooling water to be supplied to the steel sheet from at least the cooling device between the stands between the stands and the hot run table position between the stands on the downstream side in the traveling direction from the temperature measurement position. A method of controlling the temperature of a hot-rolled steel sheet, wherein one or both of the feedforward controls to be adjusted are controlled.