JPH0455012A - Plate thickness control method for rolling mill - Google Patents

Abstract

PURPOSE:To roll the material to be rolled with stable plate thickness by inputting directly a signal to a BISRA AGC, in the case the corresponding substantial frequency is approximate to the frequency corresponding to a periodical load fluctuation caused by eccentricity of a backup roll, and also, a plate thickness fluctuation has amplitude exceeding a reference value. CONSTITUTION:With regard to a steel plate S which is run in the direction as indicated with an arrow, plate thickness is detected by a plate thickness gauge 26 of the entry of a rolling mill, its detecting signal is inputted to a frequency analysing device 28, and whether there is specific periodicity in a fluctuation of plate thickness detected by the analysing device concerned 28 or not is analysed. As a result of analysis by the analysing device 28, in the case specific periodicity is recognized in a fluctuation of plate thickness of the steel plate S, a changeover switch 18 is switched automatically to a (b) side, a rolling load signal is allowed to make a detour from a band pass filter, inputted directly to a BISRA AGC 22, and in the same way, the roll rolling reduction is adjusted, and rolling of the steel plate S is executed.

Description

[Detailed description of the invention] [Industrial application field]

The present invention relates to a method for controlling a plate thickness in a rolling mill, and particularly to a method for controlling a plate thickness in a rolling mill, which allows rolling with a stable plate thickness at all times even when a backup roll is eccentric.

[Conventional technology]

BISRA A is usually used as a method for controlling plate thickness in rolling mills.
GC (Autonat+c Gauge Cont.
A method called ``roll'' that controls the rolling position using rolling load deviation is generally used. The above BISRA AGC is a feedback AGC installed on the exit side of the rolling mill and controlled using the detected value of the plate thickness gauge.
It has the advantage of faster response than . However, if there is eccentricity in the backup roll of the rolling mill, rolling load fluctuations due to the eccentricity will cause BISRA AG
This has the disadvantage that the plate thickness control performance deteriorates because it causes a disturbance of C. As a countermeasure, the rolling load signal is corrected to remove the periodic load fluctuation caused by the eccentricity of the backup roll from the actually measured rolling load.
A method has been adopted in which the thickness of the material to be rolled is controlled to be constant by using it as an input signal to ISRA AGC.

[Problem to be achieved by the invention]

However, BISRA uses a corrected rolling load signal that removes the load fluctuation caused by the eccentricity of the backup roll.
In the above-mentioned method used as an input signal for AGC, the thickness fluctuation of the rolled material at the entrance side of the rolling mill changes substantially periodically, and the frequency is close to the frequency corresponding to the load fluctuation caused by the trust of the backup roll. In case, B'l
There is a problem that the 5RA AGC does not function effectively against changes in plate thickness on the entry side of the rolling mill, resulting in a decrease in plate thickness accuracy. The present invention was made to solve the above problems, and
It is an object of the present invention to provide a method for controlling plate thickness in a rolling mill that can always perform rolling with a stable plate thickness even when a backup roll is damaged.

[Means to achieve the task]

The present invention provides a rolling load signal based on the actually measured rolling load,
BIS through a bandpass filter to remove periodic load fluctuation components caused by eccentricity of the backup roll.
In a rolling mill plate thickness control method in which the thickness of the rolled material is controlled by inputting it to the RA AGC, frequency analysis is performed on the variation in the thickness of the rolled material at the entry side of the rolling mill, and from the analysis results,
The plate thickness of the material to be rolled varies substantially periodically, and the substantial frequency corresponding to the plate thickness variation is close to the frequency corresponding to the periodic load variation due to the eccentricity of the backup roll, and The above problem is achieved by directly inputting a signal to the BISRA AGC when the plate thickness variation has an amplitude exceeding the reference value.

[Action and effect]

In the present invention, frequency analysis is performed on plate thickness variations of the rolled material at the entrance side of the rolling mill, and the actual frequency corresponding to the plate thickness variations is approximated to the frequency corresponding to load variations due to eccentricity of the backup roll. , and if the plate thickness fluctuation has an amplitude above a certain level, the function to remove the fluctuation component caused by the eccentricity of the backup roll from the rolling load signal based on the actually measured rolling load fluctuation is not used, and the original rolling load is BISRA rolling load signal based on fluctuations
The thickness of the material to be rolled is controlled by inputting it to the AGC. As a result, the above-mentioned drawbacks caused by using a band-pass filter can be eliminated, and even if the material to be rolled has thickness fluctuations that change substantially periodically as described above, the material to be rolled can be kept at a stable thickness. It became possible to roll it.

【Example】

Embodiments of the present invention will be described in detail below with reference to the drawings. FIG. 1 is a schematic configuration diagram showing a rolling mill applied to an embodiment of the present invention. The rolling mill is equipped with a pair of upper and lower work rolls 1o for rolling a steel plate (material to be rolled) indicated by S in the figure, and a backup roll 12 in contact with each of the work rolls 10. Also, in the upper position! A rolling load meter 14 is attached to the backup roll 12 positioned below, and a hydraulic cylinder 16 is attached to the backup roll 12 positioned below to adjust the amount of roll reduction. has been done. From the rolling load cell 14, measurement signals can be sequentially input to the band pass filter 20, the B I 5RAAGC 22, and the hydraulic pressure reduction control system 24 via the normal changeover switch 18 (the changeover switch 18 is connected to the a side). Further, the hydraulic pressure reduction control system 24 outputs a signal to the hydraulic cylinder 16 to control the roll reduction amount. The above-mentioned band pass filter 20 is based on the rolling FIf! actually measured by the above-mentioned rolling load meter 14 and based on the rolling load (variation). The function of removing frequency components corresponding to periodic load fluctuations caused by damage to the backup roll 12 from the signal is reduced. Moreover, when the changeover switch 18 is switched to b, the measurement signal from the rolling load meter 14 is transmitted to the IE connection B I5RAAGC22 without passing through the bandpass filter 20.
It has been made possible to input. Further, a plate thickness gauge 26 is disposed on the inlet side of the rolling mill, and a detection signal from the plate thickness gauge 26 is input to a frequency analyzer 28, and the changeover switch 18 is switched based on the analysis result. It is being done as it should be done. In this embodiment, regarding the steel plate S traveling in the direction of the arrow,
The plate thickness is detected by the plate thickness gauge 26 on the entrance side of the rolling mill, and the detected signal is input to the frequency analyzer 28, and it is determined whether or not the plate thickness variation detected by the analyzer 228 has a specific periodicity. To analyze. That is, the detected plate thickness variation has substantially periodicity, the plate thickness variation has a frequency that approximates the periodic rolling load variation caused by the reliability of the backup roll 12, and the amplitude thereof is equal to the reference value. Cases are divided into cases in which the amount exceeds the above limit and cases in which the amount exceeds the specified limit. As a result of the above analysis, if the plate thickness fluctuation does not have the above-mentioned specific periodicity, the changeover switch 18 is set to the a side, and the rolling load system 14
The rolling load signal output from the band pass filter 2
0 to remove the influence of the broken heart of the backup roll 12, the corrected signal is sent to BISRA.
0 input to the AGC 22 Next, based on this input signal, a roll reduction 1 command signal is input from the BISRA AGC 22 to the hydraulic pressure reduction control system 24 to drive and control the hydraulic cylinder 16, thereby appropriately controlling the roll reduction amount. Adjust and roll the steel plate S. On the other hand, if the above-mentioned specific periodicity is recognized in the thickness variation of the steel plate S as a result of analysis by the analysis device 28, the changeover switch 18 is automatically switched to side b, and the rolling load signal is , bypassing the band-pass filter 20, the BI
It is directly input to the SRA AGC 22, the roll reduction amount is adjusted in the same way, and the steel plate S is rolled. As described above, according to this embodiment, the thickness of the steel plate S on the entrance side of the rolling mill is detected, and if the thickness variation does not have the above-mentioned specific periodicity based on the detection result, the rolling load is changed as in the conventional case. The signal is passed through a bandpass filter 20 to BISRA A
Since it is input to the GC 22, the plate thickness can be controlled by removing the influence of the eccentricity of the backup roll 12, and conversely, if the plate thickness fluctuation has the above-mentioned specific periodicity, it is possible to control the plate thickness without going through the band pass filter 20. BISR rolling load signal directly
A Since the signal is input to the AGC 22, the disadvantages of controlling the plate thickness caused by using the bandpass filter 20 can be eliminated. As a result, even if the steel plate S has thickness fluctuations having the above-mentioned specific periodicity that deteriorates the thickness controllability, the deterioration of the thickness controllability can be prevented, so that rolling can always be carried out under good controllability. It becomes possible to do this. The time chart in FIG. 2 shows the results obtained when the method for controlling the thickness of a rolling mill according to this embodiment is applied to actual rolling. Figure 2 (A) shows changes in plate thickness over time at the entry side of the rolling mill, Figure 2 (B) shows changes in rolling load during rolling, and Figure 2 (C) shows changes in plate thickness at the exit side of the rolling mill. The left side of the figure corresponds to when b(I!l) is selected with the changeover switch 18, and the right side corresponds to when side a is selected. From the above and FIG. When there is a plate thickness fluctuation that changes substantially periodically as shown in Fig. 2 (A), compared to the case where the rolling load signal is passed through the band pass filter 20 (on the right side of the figure), the filter 2o It is shown that the variation in plate thickness on the exit side of the rolling mill is smaller when the plate is detoured (1 Ill on the left in the figure).As described above, the variation in plate thickness on the input side of the rolling mill is caused by the eccentricity of the backup roll 12. If the actual frequency is close to the frequency corresponding to the rolling fluctuation and the magnitude exceeds a predetermined reference value, the rolling load signal is bypassed through the bandpass filter 20 to improve plate thickness accuracy. Next, the criteria for switching the changeover switch from the a side to the b side, that is, the specific periodicity of plate thickness fluctuations at the entrance side of the rolling mill, will be explained. (1) Corresponding to plate thickness fluctuations. For example, the fact that the actual frequency corresponding to the rolling load fluctuation due to the eccentricity of the back unroll 12 is approximated is as follows.In other words, if the former frequency is fh, and the latter frequency is 1 day. Then,
If the following equation (1) is satisfied, these frequencies can be considered to be close. (fh - f day) / f81 ≦0.1... (1) (
2) The plate thickness fluctuation has an amplitude exceeding a predetermined reference value when, for example, the following equation (2) is satisfied. Amplitude≧Target thickness x0.02 ・・・・・・・・・(
2) Although the present invention has been specifically described above, it goes without saying that the present invention is not limited to what has been shown in the above embodiments, and can be modified in various ways without departing from the gist thereof.

[Brief explanation of drawings]

FIG. 1 is a schematic configuration diagram showing a rolling mill applied to an embodiment of the present invention, and FIG. 2 is a time chart showing actual measured values for explaining the effects of the above embodiment. 18... Selector switch, 20... Band pass filter, 22... BISRA AGC. 24...Hydraulic reduction control system, 26...Plate thickness gauge, 28...Frequency analysis device, S...Steel plate.

Claims (1)

[Claims] (1) A rolling load signal based on the actually measured rolling load is passed through a bandpass filter to remove periodic load fluctuation components caused by eccentricity of the backup roll.
In a rolling mill thickness control method that inputs data into AGC to control the thickness of the rolled material, frequency analysis is performed on the thickness variation of the rolled material at the entrance side of the rolling mill, and from the analysis results, the thickness of the rolled material is determined. The plate thickness varies substantially periodically, the substantial frequency corresponding to the plate thickness variation is close to the frequency corresponding to the periodic load variation due to the eccentricity of the backup roll, and the plate thickness variation is If the signal has an amplitude exceeding the reference value, the signal is
A method for controlling plate thickness in a rolling mill, characterized by direct input to AGC.