JPH0570843A - Method for controlling tension of steel sheet - Google Patents

Abstract

PURPOSE:To increase the performance of controlling tension in a steel sheet even when the noise of the actual result value of tension is high and to control tension with high response and high accuracy for a facility requiring the control of the tension of a steel sheet. CONSTITUTION:As a tension controller, a circuit in which a proportional gain 14b is multiplied by tension set value 11 into control output and a circuit in which a deviation between the tension set value 11 and actual result value is multiplied by a proportional grain 14a through a low-pass filter with noise frequency or below into control output are added to the conventional proportional-plus-integral control, and tension control is executed.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a method of controlling the tension of a steel sheet.

[0002]

2. Description of the Related Art In equipment for conveying steel sheets, for example, continuous annealing equipment, it is a work or heat buckle (wrinkle of the steel sheet) that the steel sheet is processed while being applied with appropriate tension.
It is important to prevent the occurrence of heat generation and to carry out appropriate processing.

Generally, in tension control in continuous annealing equipment,
As disclosed in JP-A-59-126715 and the like,
With the tensiometer attached to the bearing of the transport roll,
The actual tension of the steel sheet is measured, and the tension control is performed to adjust the speed of the transport roll in the set section based on the difference between the actual tension and the set tension. The configuration of this tension control system is shown in FIG. That is, the steel plate 1 is passed through the carrying roll 2. Reference numeral 3 is an electric motor for driving the carrying roll 2, 4 is a speed control device for supplying electric power to the electric motor 3 to control the plate passing speed, and 5 is a steel plate tension detector. A tension controller 6 controls the tension of the steel sheet 1 to a set tension. Reference numeral 7 is a steel plate passing speed reference generator, and 8 is a tension setting device. The operation of this control system is as follows.

The tension of the steel plate 1 is detected by the tension detector 5, and the detected tension value is compared with the set tension value. If there is a difference between the two, the tension control device 6 outputs a control signal corresponding to the difference. Is output. This control signal is added to the speed reference generated by the strip passing speed reference generator 7 and output to the speed controller 4 as a speed command for each tension control section. By this speed command, the conveyor roll connected to the electric motor 3 rotates, and by applying a threading force to the steel plate 1, the actual tension of the steel plate 1 is corrected and the steel plate detected by the tension detector 5. The tension is controlled to match the set value.

[0005]

Since the transfer roll is installed in a high-temperature furnace, expansion and deformation due to heat causes eccentricity, which causes a large noise in the tensiometer installed in the bearing. Let Moreover, noise may be generated in the tensiometer due to vibration of the steel sheet being conveyed. In this way, when trying to perform tension control using the actual tension value that contains a large amount of noise, the proportional-plus-integral control conventionally used amplifies the noise component when the proportional gain is increased, and control Is unstable, the proportional gain cannot be increased, and as a result, the response time of the tension control system becomes very long, from tens to hundreds of seconds, and the tension value of the steel sheet cannot be controlled properly. Is.

Therefore, according to the present invention, even when the actual tension value obtained by the tensiometer contains a large amount of noise, the response to the change in the tension setting and the response to the change in the tension are accelerated, and the tension can be adjusted with high accuracy. It is an object to stabilize the threading by controlling the tension of the steel sheet to an appropriate value by making control possible.

[0007]

In order to solve the above-mentioned problems, in the present invention, in addition to the conventional proportional-integral control, a control in which a tension set value is multiplied by a proportional gain is used as a control output, and a tension set value is set. The difference between the actual tension value and the actual tension value is passed through a low-pass filter, and the control output is obtained by applying a proportional gain, and the tension is controlled by the result of adding the control outputs.

[0008]

When the tension set value is changed, the control output changes in proportion to the setting change amount, so that the trackability of the actual value to the set value is improved. Further, when a tension fluctuation occurs, the proportional gain of the control of the proportional-plus-integral control can be equivalently increased, so that the tension fluctuation can be corrected quickly.

[0009]

EXAMPLE FIG. 1 shows the configuration of a tension control system of an example. 1
1 is a tension set value, 12 is a proportional-plus-integral control device, 13 is a proportional gain by which the tension set value is multiplied, 14a is a low-pass filter, 14b is a proportional gain, 15 is a tension actual value obtained from a tensiometer, and 16 is a tension setting. Deviation between actual value and actual tension value, 1
7 is a control output of the tension control system, 18 is a speed control device including a power supply for driving a roll for controlling the tension,
Reference numeral 19 is a driving motor, and 20 is a roll. The proportional-plus-integral control device 12 has the same configuration as that used in the conventional control system, and operates similarly to the conventional control system.

In the control system of FIG. 1, first, the tension set value 1
A case where 1 changes will be described. As the tension set value 11 is changed, the tension control output 17 is simultaneously changed via the proportional gain 13. This proportional gain 13 is the tension setting value 1
It is necessary that the actual tension value 15 is selected so as to follow the change of 1 most quickly, and the interval between the rolls and the roll,
Although a different gain such as the number of rolls is set for each equipment, the present inventors have used a value of about 0.5 to 1.0 mpm / Kg as the proportional gain 13 based on the result of the test actually performed. The output of this control is given to the speed controller 18,
The speed of the roll 20 is changed by changing the drive speed of the drive motor 19. By this control, the steel plate tension is the tension setting value 1
Follow 1 with good response. FIG. 2 shows a response example of the actual tension when the tension set value 11 changes. In FIG. 2, 31
Indicates a response characteristic when the control by the proportional gain 13 is performed, 32 indicates a response characteristic when the control is not performed, and 33 indicates a change in the set tension value.

Next, the occurrence of tension fluctuation will be described. Here, first, the cutoff frequency of the low-pass filter 14a is set to be smaller than the frequency of the noise component included in the actual tension value 15 obtained from the tensiometer or the like. Usually, the lowest frequency component of noise which is a problem in tension control is several hertz, and if the cutoff frequency is too low, the followability to tension fluctuation is adversely affected. Therefore, in this embodiment, the cutoff frequency is 1 to 2 A Hertz low-pass filter is used.
Further, the proportional gain 14b is set to be several tens to several hundred times larger than the proportional gain of the proportional-plus-integral control device 12. With the conventional PI control alone, it is not possible to effectively suppress the tension fluctuation due to the low control gain, particularly the proportional gain. On the other hand, in the control system that passes the proportional gain 14b, the low frequency noise component included in the actual tension value is removed, so the control stability is improved and a large gain can be obtained.
The gain can be increased with respect to the tension fluctuation at a frequency lower than the cutoff frequency of the low-pass filter 14a, a large control output can be given to the tension control device 18, and the tension fluctuation can be quickly absorbed. FIG. 3 shows an example of the actual tension change when the tension fluctuation (disturbance) occurs. In FIG. 3, reference numeral 41 is the actual tension when the control by the low-pass filter 14a and the proportional gain 14b is performed, 42 is the response characteristic of the actual tension when the control is not performed, and 43 is the time when the tension disturbance occurs. Is shown.

[0012]

According to the control of the present invention, the actual tension value accurately follows the target tension setting value, so that the steel sheet is thin, wide and soft, that is, the work or the work. Even when a steel plate that is prone to buckle is transported, production can be performed very stably.

[Brief description of drawings]

FIG. 1 is a block diagram showing a configuration of a tension control system of an embodiment.

FIG. 2 is a graph showing a response characteristic with respect to a change in target tension.

FIG. 3 is a graph showing response characteristics to disturbance.

FIG. 4 is a block diagram showing a configuration of a conventional steel plate tension control device.

[Explanation of symbols]

11: Tension set value 12: Proportional / integral control device 13: Proportional gain applied to the tension set value 14a: Low-pass filter 14b: Proportional gain 15: Actual tension value obtained from tensiometer 16: Tension set value and actual tension value Deviation 17: Control output of tension control system 18: Speed control device 19: Driving motor 20: Roll 31: Response characteristics when control by proportional gain 13 is performed 32: Control by proportional gain 13 is performed Response characteristics when not performed 33: Set tension value 41: Actual tension when control by 14a and 14b is performed 42: Actual tension when control by 14a and 14b is not performed 43: Tension disturbance occurrence time

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Hideshi Funakata 1-1 No. 1 Tobita-cho, Tobata-ku, Kitakyushu City Nippon Steel Co., Ltd. Yawata Works

Claims (1)

[Claims] 1. A method for controlling the tension of a steel plate of equipment that requires controlling the tension of the steel plate, wherein the actual tension value of the steel plate is detected by a tensiometer, and the tension set value is detected according to a deviation between the detected actual tension value. Proportional-integral control that outputs a first controlled variable, control that outputs a second controlled variable that is obtained by multiplying the tension set value by a proportional gain, and low-pass the deviation between the tension set value and the detected actual tension value. A control is performed to output a third controlled variable obtained by applying a proportional gain to the output through a filter, and according to a result of adding the first controlled variable, the second controlled variable, and the third controlled variable. A steel plate tension control method for controlling the steel plate tension.