JP2853075B2 - Method for controlling elongation of steel sheet in temper 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 method for controlling the elongation of a steel sheet in a temper rolling mill.

[0002]

2. Description of the Related Art Conventionally, a method for controlling the elongation of a temper rolling mill is as follows.
A pulse generator is installed on the entrance and exit bridle rolls of the temper rolling mill, and the feed length of the steel sheet on the entrance side and the advance length of the steel sheet on the exit side are counted at a constant or variable sampling cycle. This measures the elongation of the steel sheet.

[0003] Fig. 7 shows an example of a general elongation rate control method in a temper rolling mill and an example of countermeasures for an elongation rate measurement error. In a general elongation rate control method, a steel sheet 1 is temper-rolled by a temper rolling mill 3 through an inlet bridle roll 2 and is discharged through an outlet bridle roll. The elongation rate is determined by the number of pulses of the pulse generators 4 and 5 attached to the entrance side and exit side rolls, and the entrance side length LE and the exit side length L
D is calculated, and is calculated by the following formula in the elongation percentage calculating device 6.

Εsfbk = ((LD−LE) / LE) × 100 (%) In the elongation percentage calculator 6, the correction amount is set so that the actual elongation percentage εsfbk becomes the value εref set by the elongation percentage setting device 8. It is controlled by the draft adjustment mechanism 9. As described above, it has been general to control the elongation of the steel sheet by feeding back the deviation from the set value of the elongation to the rolling-down device or the tension controller at the entrance side or the exit side.

The accuracy of elongation measurement is one of the pulse generators.
It largely depends on the feed length (hereinafter referred to as increment) represented by the pulse, the sampling period, and the like.
The pulse generators on the input and output sides are incremented by 0.
Assuming that 2 mm / pulse and the sampling period are equivalent to 3 m, the quantization error due to the counting of one pulse is as follows. Error = ((input pulse increment + output pulse increment) / sampling length) × 100 (%) = 0.
013 (%)

[0006] In addition to the above error, the control accuracy of the speed control device is generally ± 0.02%, so that the elongation percentage is about ± 0.02 to 0.04% even under the constant operating conditions. Periodic fluctuation (measurement error) occurs.

As a prior art, as shown in FIG. 7, in order to improve the measurement error of the elongation rate, as shown in FIG. Feedback method (Japanese Patent Laid-Open No.
713), (2) a method of calculating an elongation rate from a moving average of a sampling pulse (Japanese Patent Application Laid-Open No. 3-86321), and (3) a method of providing a dead band for controlling the elongation rate without lengthening the sampling period. In the case where the actual elongation rate is such a large elongation rate deviation value that causes a response delay, measures such as a method of stopping the control (Japanese Patent Application Laid-Open No. 3-66407) have been taken.

[0008]

The above-mentioned countermeasures for the measurement error of the elongation rate cannot satisfy all of control accuracy, stability and responsiveness. In the cases (1) and (2), the stability and the control accuracy in the steady state are excellent.
Even if the elongation rate greatly changes, the response is deteriorated because it is controlled by the average value of the past several cycles, and in the case of (3), the responsiveness is good. If it is, the control is stopped, and the control accuracy is deteriorated.

[0009] The proportional gain and the like have properties whose proper values should be originally changed according to the state of the steel sheet.
However, since it is relatively difficult to always give an appropriate gain according to the characteristics of the steel sheet and other operating conditions,
Usually, a lower gain is given to prevent the control system from becoming unstable. For this reason, when there is a rapid processing change such as a change in the steel sheet in the case where the steel sheets are connected and the continuous processing is performed, the elongation rate largely changes and it takes time to converge. For this reason, if the convergence time is long, the strength of the rolled material during that time is poor due to the response delay, and the portion has to be cut down, causing a decrease in yield.

In temper rolling, it is important in terms of material to precisely control the elongation value, and it is necessary to accurately measure and control the elongation ratio in the steady rolling section. The problem to be solved by the present invention is to return to the set elongation rate as soon as possible when the elongation rate deviates from the set value, for example, when there is a rapid processing change such as a change in the steel sheet.

[0011]

Means and operation of the present invention are as follows. As a first invention, a pulse generator is mounted on the bridle rolls on the inlet and outlet sides of the temper rolling mill. The elongation rate of the steel sheet is measured by counting the feed length of the steel sheet at the entrance side and the advance length of the steel sheet at the exit side at regular intervals, and the deviation from this elongation percentage and the set value is reduced. In the method of controlling the elongation rate of the steel sheet by feeding back to the device, the results of the elongation rate for the past several cycles are stored, and the deviation from the set value of the elongation rate is within the allowable range of the elongation rate for the past several cycles. In the case, the average value of the measured values of the elongation rate in the past several cycles is fed back, and in other cases, the elongation rate control method of the steel sheet of the temper rolling mill is to feed back the instantaneous value of the most recent elongation rate. Is Further, there is provided the elongation rate control method for a steel sheet of a temper rolling mill according to the above, wherein a deviation from the elongation rate and the set value is fed back to a tension control device at an entrance side or an exit side.

As a second invention, a pulse transmitter is provided on the bridle rolls on the inlet side and the outlet side of the temper rolling mill, and the feed length of the steel sheet on the inlet side and the advance length of the steel sheet on the outlet side are determined. In the method of controlling the elongation rate of the steel sheet by measuring the elongation rate of the steel sheet by counting at a fixed cycle and feeding back the deviation from the elongation rate and the set value to the rolling-down device, Except when the deviation is a large elongation percentage deviation value that causes a response delay, the control gain is increased, and the sampling period of the elongation percentage measurement is shortened.
A method for controlling the elongation rate of a steel sheet of a temper rolling mill in which the sampling cycle of elongation rate measurement is lengthened and the control gain and the sampling cycle are switched by an elongation rate determiner having hysteresis characteristics. . Also,
A method for controlling the elongation of a steel sheet of a temper rolling mill according to the above, wherein a deviation from the elongation and a set value is fed back to a tension control device at an entrance side or an exit side.

[0013]

Embodiments of the present invention will be described below. 1 to 7 will be described first. 1 is a steel plate, 2
Is the entrance bridle roll, 3 is the exit bridle roll,
4 is an incoming pulse generator, 5 is an outgoing pulse generator, 6 is an elongation rate operation device, 7 is an elongation rate control operation device, 8 is an elongation rate setting device, 9 is a draft reduction mechanism, and 10 is a temper rolling mill. , 11 is a converter, 12 is an entrance bridle roll drive motor, 13
Is an outgoing bridle roll drive motor, 14 is an elongation rate averaging arithmetic device, 15 is an incoming pulse moving averaging arithmetic device,
Reference numeral 16 denotes an output side pulse moving averaging operation device, reference numeral 17 denotes a proportional integrator, reference numeral 18 denotes a dead zone detector, reference numeral 19 denotes an adjusting means, and reference numeral 20 denotes an elongation ratio judging device.

Next, the first invention will be described with reference to FIGS. FIGS. 1 and 2 show an elongation rate average value calculating device 14 which calculates an average value εafbk of the elongation rate actual values εsfbk in the past several cycles to the elongation rate actual value εsfbk in the block diagram of the conventional example shown in FIG. εafbk and εsf
An elongation rate feedback determiner 20 for switching bk is added.

The average elongation percentage estimating device 14 has an actual elongation epsilon sfb calculated by the elongation estimating device 6.
k is input and the actual growth rate εsfbk for the past several cycles
Is calculated. The elongation rate feedback determiner 20 receives the elongation rate actual value εsfbk calculated by the elongation rate calculator 6 and the elongation rate set value εref set by the elongation rate setter 8. And
If the difference between the elongation rate actual value εsfbk and the elongation rate set value εref for the past several cycles is within the elongation rate allowable range ± α%, the elongation rate feedback εfbk used in the elongation rate operation control device 7 includes the elongation. In this case, the average elongation rate εafbk is used.
The elongation rate feedback is switched so as to use sfbk.

FIG. 1 shows the elongation rate feedback ε.
fbk is transmitted to the rolling reduction mechanism 9 by the elongation rate calculation control device 7, and FIG. 2 shows the elongation rate feedback εfbk by the elongation rate calculation control device 7 for driving the entrance side bridle roll drive motor 12 or the exit side bridle roll drive. This shows an example of transmission to the motor 13.

FIG. 3 shows a change in the elongation feedback value according to the present method. (A) is the actual growth rate εsfbk,
(B) shows each signal of the average elongation rate εafbk, and (c) shows the signal of the elongation feedback value εfbk. in this way,
In a steady state (a state in which control is performed at a value close to the target), the use of the average elongation rate εafbk can prevent an error in elongation rate measurement from affecting control. When the elongation percentage deviates from the set value to some extent, the responsiveness can be improved by using the latest elongation percentage actual value εsfbk. According to this method, since the steady state is more stable, the control gain can be increased, and the responsiveness can be improved. Therefore, it is possible to realize the feedback control of the elongation rate having both stability and responsiveness. It became.

Next, the second invention will be described with reference to FIGS. 4, 5 and 6. FIG. 4 and 5 are obtained by adding an elongation rate feedback determiner 20 to the actual elongation rate value ssfbk in the block diagram of the conventional example of FIG.
In addition, the elongation rate feedback determiner 20 includes the elongation rate actual value εsfbk calculated by the elongation rate calculator 6.
And the elongation percentage set value εref set by the elongation percentage setter 8
Is input.

As in the example shown in FIG. 6, hysteresis is provided for the determination switching of the elongation rate feedback determiner 20. Elongation set value εref and actual elongation εs
If the difference Δε from fbk is within ± α%, which is the elongation percentage allowable range, the gain used in the elongation percentage control arithmetic unit 7 is reduced,
The elongation rate sampling cycle of the elongation rate calculator 6 is lengthened. Even if Δε is other than ± α%, if the elongation ratio deviation value is large enough to cause a response delay and is within ± β%, the gain and elongation ratio sampling cycle are the same as those within ± α%. Next, in cases other than ± β%, the gain is increased and the elongation rate sampling cycle of the elongation rate calculator 6 is shortened, and Δ
Until ε is within ± α%, the same gain and elongation rate sampling period as those other than ± β% are used. This is shown in Table 1 below.

[0020]

[Table 1]

FIG. 4 shows the elongation rate feedback ε.
The fbk is transmitted to the rolling adjustment mechanism 9 by the elongation rate operation control device 7, and FIG. 5 shows the elongation rate feedback εfbk by the elongation rate operation control device 7 for driving the entrance side bridle roll drive motor 12 or the exit side bridle roll drive. This shows an example of transmission to the motor 13.

As described above, in a steady state (a state in which control is performed at a value close to the target), the stability is improved by lowering the gain and lengthening the elongation rate sampling cycle, and the error of the elongation rate measurement is reduced. Prevent affecting control. If the elongation ratio deviates from the set value to the extent that the responsiveness becomes a problem rather than the elongation ratio measurement error, the gain is increased and the elongation ratio sampling cycle is shortened to provide a responsive elongation ratio feedback control. Can be performed. Further, since the elongation rate feedback determiner has a hysteresis characteristic, the elongation rate feedback control with better responsiveness and stability can be performed as compared with a case where the hysteresis characteristic is not provided.

[0023]

As described above, in the first invention, in the steady state (state in which the control is performed at a value close to the target), the average value of the elongation is used to measure the elongation. It is possible to prevent the error from affecting the control. When the elongation rate deviates from the set value to some extent, the responsiveness can be improved by using the latest elongation rate actual value. Furthermore, according to this method, since the steady state is more stable, the control gain can be increased, and the responsiveness can be improved. Therefore, the feedback control of the elongation rate having both stability and responsiveness can be realized. Became possible.

In the second invention, in a steady state, the gain is reduced, the elongation rate sampling period is lengthened, the stability is improved, and the error of the elongation rate measurement can be prevented from affecting the control. If the elongation rate deviates from the set value to the extent that the responsiveness becomes a problem rather than the elongation rate measurement error, the gain is increased and the elongation rate sampling cycle is shortened to obtain an elongation rate with good responsiveness. Feedback control can be performed. Furthermore, since the elongation rate feedback determination switching is provided with a hysteresis characteristic, the responsiveness and stability can be improved as compared with a case where the hysteresis characteristic is not provided.

[Brief description of the drawings]

FIG. 1 is a basic configuration diagram of the first invention.

FIG. 2 is another example of the basic configuration diagram of the first invention.

FIG. 3 is a diagram showing a change in an elongation rate feedback value according to the first invention.

FIG. 4 is a basic configuration diagram of the second invention.

FIG. 5 is another example of the basic configuration diagram of the second invention.

FIG. 6 is a hysteresis characteristic diagram of the second invention.

FIG. 7 is a diagram showing a conventional control method.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Steel plate 2 Inlet bridle roll 3 Outlet bridle roll 4 Inlet pulse generator 5 Outlet pulse generator 6 Elongation rate calculation device 7 Elongation rate control calculation device 8 Elongation rate setting device 9 Roll-down adjustment mechanism 10 Temper rolling mill 11 Converter 12 Inlet bridle roll drive motor 13 Outlet bridle roll drive motor 14 Elongation rate averaging device 15 Incoming pulse moving averaging device 16 Outgoing pulse moving averaging device 17 Proportional integrator 18 Dead zone detection Instrument 19 Adjusting means 20 Elongation rate judgment device

Continued on the front page (72) Inventor Noboru Taguchi 1-2-1, Marunouchi, Chiyoda-ku, Tokyo Nippon Kokan Co., Ltd. Examiner Takeshi Suzuki (58) Field surveyed (Int. Cl. ⁶ , DB name) B21B 37 / 56

Claims (4)

(57) [Claims] 1. A pulse transmitter is provided on the entrance and exit bridle rolls of a temper rolling mill, and the feed length of the steel sheet on the entrance side and the advance length of the steel sheet on the exit side are counted at a constant cycle. In the method of measuring the elongation of the steel sheet by controlling the elongation of the steel sheet by feeding back the deviation from the elongation and the set value to the rolling down device, the results of the elongation of the past several cycles are stored. In addition, if the deviation from the set value of the elongation rate is within the allowable range of the elongation rate over the past several cycles, the average value of the measured values of the elongation rate in the past several cycles is fed back. A method for controlling the elongation of a steel sheet of a temper rolling mill, wherein an instantaneous value of the elongation of the steel sheet is fed back. 2. The method according to claim 1, wherein a deviation from the elongation percentage and the set value is fed back to a tension control device at an entrance side or an exit side. . 3. A pulse transmitter is provided on the entrance and exit bridle rolls of the temper rolling mill, and the feed length of the steel sheet on the entrance side and the advance length of the steel sheet on the exit side are counted at regular intervals. In the method of controlling the elongation of the steel sheet by measuring the elongation of the steel sheet and feeding back the deviation from the elongation and the set value to the rolling-down device, the deviation of the elongation from the set value causes a response delay. If the elongation rate deviation value is not large enough to cause the elongation rate, increase the control gain and shorten the sampling cycle of elongation rate measurement.If it is within the allowable range of elongation rate, decrease the control gain and measure the elongation rate. Characterized in that the control gain and the sampling period are switched by an elongation ratio determiner having a longer sampling period and a hysteresis characteristic. Your way. 4. The method for controlling the elongation of a steel sheet in a temper rolling mill according to claim 1, wherein a deviation from the elongation and a set value is fed back to a tension control device at an inlet or an outlet. .