JPH0513732B2 - - Google Patents

Description

Detailed Description of the Invention <Industrial Application Field> The present invention is directed to roll eccentricity control for preventing plate thickness variations due to roll eccentricity in plate thickness control of hot or cold hydraulic rolling mills. In the control device,
This automatically corrects phase lag.

<Prior Art> In general, no matter how carefully a rolling roll is manufactured to be perfectly round, there is always roll eccentricity such as poor roundness or misalignment of the center between the body and the bearing. The amount of roll eccentricity is usually a value of several tens of micrometers. Therefore, a plate rolled using eccentric rolls has periodic thickness fluctuations in the length direction of the plate. Roll eccentricity control attempts to compensate for variations in plate thickness due to such roll eccentricity.

In order to effectively control roll eccentricity, it is necessary to detect the amount of roll eccentricity as accurately as possible, and to correctly detect and correct the phase delay of the rolling control system when a control signal is generated.

In the conventional phase lag correction of roll eccentricity control, first, the optimum phase correction amount for an appropriate rolling speed is determined in advance by measuring the control effect off-line. A linear or curved approximation formula is created for the optimal phase correction amount at several points for the rolling speed obtained in this way, and the phase correction amount is calculated and corrected for any rolling speed during control. was.

<Problems to be solved by the invention> However, the amount of correction for phase lag depends on fluctuations in rolling speed,
It changes irregularly during rolling due to fluctuations in various parameters, but in the conventional method described above, the phase delay is corrected based on data measured offline in advance under specific conditions, so the following (1)
There were problems in terms of controllability and stability as shown in (3).

(1) It is difficult to take an accurate response to the correction of the phase correction amount due to fluctuations in rolling speed, and control errors occur particularly in the low speed region.

(2) It is powerless against long-term changes in pressure response and requires re-measurement and readjustment.

(3) Confirming and adjusting the effect of phase lag correction takes time and tends to be complicated.

In view of the above-mentioned prior art, the present invention is capable of accurately grasping the phase lag each time there is a change in rolling conditions such as rolling speed, automatically responding to changes in rolling response characteristics over time, and It is an object of the present invention to provide a phase lag correction method for roll eccentricity control that is relatively easy to detect and easy to implement.

<Means for Solving the Problems> The method of the present invention for achieving the above-mentioned object includes the following steps in a roll eccentricity control device of a hydraulic rolling mill: A displacement command signal to a rolling cylinder and an actual displacement of the rolling cylinder. The present invention is characterized in that the difference between the phase values of the two signals is calculated by performing Fourier analysis on each of the signals, and the difference between the calculated phase values is used as a phase delay correction amount for roll eccentricity control.

<Effect> Change the phase of the displacement command signal to the rolling cylinder to _S ,
If the phase of the actual displacement signal of the rolling cylinder is _R , then the difference φ= _R − _S corresponds to the phase delay of the rolling system. Therefore, since each phase value of the displacement command signal and the actual displacement signal is determined by Fourier analysis, the phase difference φ is determined from these values and the phase of the roll eccentricity control signal is corrected by that value in advance. Moreover, the phase delay is corrected accurately.

<Embodiment> Generally, the ram of the rolling cylinder is displaced not only by the roll eccentricity control signal but also by a signal that is the sum of various control signals such as BISRA AGC. Furthermore, when a displacement command signal S(t) of the rolling cylinder including a roll eccentricity control signal is applied to the rolling control system, an output corresponding to this displacement command signal S(t), that is, a ram position displacement signal R(t ) reacts with a delay of a certain value. The ram position displacement signal R(t) represents the actual displacement of the rolling cylinder.

Therefore, let's consider a case where phase lag is detected using Fourier analysis.

First, when the displacement command signal S(t) is approximated by an n-th order Fourier series, the following equation (1) is obtained.

S(t)≒ _o 〓 ⁱ⁼¹ a _si sin (iωt+ _si ) ...Equation (1) where, a _si =√ ² _si + ² _si (amplitude of i-th component) _si = tan ^-1 B _si / A _si (phase of i-th component) However, A _si = 2/T∫ ^T ₀ a _si sin (iωt + _si ) siniωt dt B _si = 2/T∫ ^T ₀ a _si sin (iωt + _si ) cosiωt dt On the other hand , ram position displacement signal R(t) of the reduction cylinder
Similarly, when expanded into an n-th Fourier series, we get the following equation
It becomes like (2).

R(t)≒ _o 〓 ^j=1 a _Rj sin(jωt+ _Rj ) ...Equation (2) Here, a _Rj =√ ² _Rj + ² _Rj (amplitude of j-th component) _Rj = tan ^-1 B _Rj / A _Rj (phase of j-th component) However, A _Rj = 2/T∫ ^T ₀ a _Rj sin (jωt + _Rj ) sinjωt dt B _Rj = 2/T∫ ^T ₀ a _Rj sin (jωt + _Rj ) cosjωt dt Roll Phase delay detection for eccentricity control may be performed for any order of the Fourier series, but 1
The following is sufficient, so here we will use Backup Prowl 1.
Treating only the period i=1, j=1, S(t) and R(t)
Let's find out. Then, S(t)≒a _S1 sin(ωt+ _S1 )...Equation (3) R(t)≒a _R1 sin(ωt+ _R1 )...Equation (4). Therefore, the phase difference φ ₁ between S(t) and R(t) is calculated using the formula (5): φ ₁ = _R1 − _S1 .

φ ₁ in Equation (5) is a phase lag of the first-order component, and corresponds to a phase lag of the output signal with respect to the input signal of the rolling control system. Therefore, the phase delay of the roll-down control system is detected by the calculations of equations (3) to (5). By performing roll eccentricity control while continuously or periodically performing this detection calculation operation during rolling, roll eccentricity control can be performed reliably.

<Specific Device Example> Hereinafter, an embodiment of a roll eccentricity control device to which the phase lag correction method according to the present invention is applied will be described with reference to the drawings. In Fig. 1, 1 is a work roll of a rolling mill, 2 is a back-up roll, 3 is a rolling mill, and 4 is a rolling mill work roll.
5 is a rolling force detector, 5 is a pulse oscillator as a rotational position detector of the backup roll 2, 6 is a rolling position detector, 8 and 21 are samplers, 9 is a calculator, 1
0 is a counter, 11 is a roll eccentricity waveform detection/control calculator, 12 and 20 are converters, 13 and 22 are A/
D converter, 14 is a comparator, 15 is a servo amplifier, 16 is a servo valve, 17 is a reduction cylinder,
18 is a D/A converter, 19 is an arithmetic unit, and 23 is a phase lag detection calculator.

Prior to phase delay correction, a position control system,
The BISRA automatic plate thickness control system will be briefly explained.
The reduction cylinder 17 is provided with a reduction position detector 6, which detects the displacement amount of the ram position of the reduction cylinder 17. A position control system is constructed by feeding back this ram position displacement detection signal 6a to the lowering cylinder 17 via a comparator 14, a servo amplifier 15, and a servo valve 16. On the other hand, the rolling force detection signal 4a from the rolling force detector 4 passes through the calculator 19 and the converter 20 and enters the comparator 14, thereby forming a so-called BISRA type automatic plate thickness control system. Arithmetic unit 1
In addition to the rolling force detection signal 4a, a roll eccentricity control signal 18a is input to 9, and the calculation output is converted by a converter 20 into a displacement command signal S(t) representing the rolling position.

Next, roll eccentricity control and phase delay correction will be explained. A pulse oscillator 5 outputs a pulse signal 5a in synchronization with the rotational position of the backup roll 2, and determines a sample width for detecting the amount of roll eccentricity and performing Fourier analysis. The sampler 8 uses the pulse signal 5a from the pulse oscillator 5 to generate the output signal 9a of the arithmetic unit 9.
to sample. The sampler 21 receives the ram position displacement detection signal 6a output from the reduction position detector 6,
Similarly, sampling is performed using a pulse signal 5a from a pulse oscillator 5. A counter 10 counts pulse signals 5a from the pulse oscillator 5, and is reset by a signal 11a from a roll eccentricity waveform detection/control calculator 11. However, the calculator 9 calculates the difference between the output signal 12a of the converter 12 from the rolling force detection signal 4a and outputs the difference. The converter 12 converts the ram position displacement detection signal 6a into a rolling force signal 12a.

Difference signal 9a from calculator 9 (rolling force detection signal 4
The a-rolling force conversion signal 12a) is sampled by the sampler 8 and then stored in the calculator 11 through the A/D converter 13, thereby forming a roll eccentricity control signal. Here, an example of generation of the roll eccentricity control signal will be explained with reference to FIG. 2. This is JP-A-49
-Disclosed in Publication No. 133257. Now, let the rolling force variation be ΔF, of which ΔF _R is the variation due to roll eccentricity, and ΔF _d is the variation due to other disturbances. ΔF=ΔF _R +ΔF _d ...Equation (6). Here, paying attention to the fact that roll eccentricity has periodicity, and expressing the values at the beginning and end of the period with subscripts 0 and 1, respectively, ΔF _R1 = ΔF _R0 , so ΔF ₁ −ΔF ₀ =(ΔF _R1 +ΔF _d1 )−(ΔF _R0 +ΔF _d0 )=Δ
F _d1 −ΔF _d0 ...Equation (7) is obtained. That is, by taking the difference between the rolling force fluctuations detected at the beginning and end of one period of roll eccentricity, the rolling force fluctuation ΔF _d due to disturbance excluding the rolling force fluctuation ΔF _R due to roll eccentricity can be found. However, the rolling force fluctuations due to changes in the entrance plate thickness, temperature fluctuations, etc. other than roll eccentricity have a sufficiently long period compared to that of roll eccentricity, so if the period is as short as the period of roll eccentricity, a linear approximation is possible. . Therefore, the rolling force variation ΔF _R due to roll eccentricity is determined from the total rolling force variation ΔF and the approximate value Δd of the rolling force variation due to disturbances other than roll eccentricity. In a of Figure 2,
ΔF _d is the rolling force variation due to factors other than roll eccentricity, ΔF is the superposition of the rolling force variation due to roll eccentricity on ΔF _d , and T is the period of the roll eccentricity. The beginning and end of the first cycle in FIG. 2a are connected by a straight line, and the rolling force variation deviation from this straight line is shown in FIG. 2b as the rolling force variation due to roll eccentricity. Therefore, in the second cycle of roll eccentricity, roll eccentricity control can be performed by activating the roll-down control system and adjusting the roll gap using a signal based on the rolling-down force fluctuation due to roll eccentricity determined in the first cycle. can. The rolling force fluctuation due to roll eccentricity in the second period is determined in the same way as in the first period, but the error in roll eccentricity due to linear approximation of the rolling force fluctuation due to roll eccentricity other than the roll eccentricity in the first period and the first period. Since the disturbance changes slightly between the second period and the second period, the rolling force fluctuation due to roll eccentricity does not become zero and remains somewhat even in the second period as shown in FIG. 2b. Therefore, in the third cycle, the roll-down control system is corrected and controlled using a signal based on the sum of the roll-down force fluctuations due to roll eccentricity obtained in the first cycle and the second cycle, respectively. The same process is performed for each subsequent cycle. Returning to FIG. 1, a signal corresponding to the fluctuation of the rolling force is obtained from the rolling force detector 4, and a signal corresponding to the rolling force fluctuation is obtained from the rolling position detector 6.
A signal corresponding to the ram position displacement is obtained from . Here, the rolling force fluctuation obtained from the rolling force detector 4 is P, the ram position displacement obtained from the rolling position detector 6 is S, and the value obtained by converting the ram position displacement S into rolling force is P _S
shall be. Arithmetic unit 9 outputs a signal corresponding to P- _PS . Then, the sampler 8 samples the output of the arithmetic unit 9 only when the pulse signal 5a is received.
Now, it is assumed that n pulses are oscillated per one rotation of the back-up roll 2, and the first pulse is the beginning of the first cycle of roll eccentricity. Then, the rolling force fluctuation P becomes 1st, 2nd, ..., (n-1)
P ₁₁ , _{P 12 .} At the end of the first period of roll eccentricity, that is, at the nth pulse, the calculator 11 sets the rolling force variation at that time to _P21 , outputs a signal 11a, and resets the counter 10. Also, calculator 11
The rolling force fluctuations P _R1 , P _R2 , . . . , P _R(o-1) , P _Ro due to roll eccentricity at each sampling point are calculated using the following formula.

Note that although P _R1 =P _Ro =0, generality is not lost by this. In the second period of roll eccentricity, the calculator 11 calculates P ₂₂ ,
P ₂₃ ,... P _2o is memorized, and the rolling force fluctuations P _R1 , P _R2 ,... due to roll eccentricity obtained using the previous equation (8) are
Outputs twice the signal of P _Ro . After the second cycle, calculate the rolling force fluctuation due to roll eccentricity in the second cycle in the same way as the first cycle, and add the calculated value in the first cycle to this to calculate the rolling force due to roll eccentricity. It is assumed to be variable. The same applies to each subsequent cycle.

Although phase correction is not explained in the roll eccentricity control described above, the roll eccentricity control signal from the calculator 11 is converted into an analog signal 18a by the D/A converter 18 and is provided to the calculator 19.
On the other hand, the output 6a of the reduction position detector 6 representing the displacement amount of the ram position of the reduction cylinder 17 is sampled by the sampler 21 synchronized with the sampler 8, and the A/D converter 22 outputs a digital signal 22a.
is converted into and stored in the calculator 11.

The phase lag detection calculator 23 calculates the displacement command signal S(t) to the rolling cylinder 17, which is the output of the converter 20, and the actual displacement of the rolling cylinder 17 that has passed through the sampler 21 and the A/D converter 22. From the represented ram position displacement signal R(t), calculations are performed according to the above-mentioned equations (1) to (5) to detect the phase delay φ ₁ of the reduction control system. The phase delay detection signal 23a calculated here is input to the calculator 11. In the process of generating the roll eccentricity control signal described above, the calculator 11 outputs the roll eccentricity control signal earlier by a time width corresponding to the detected phase delay φ ₁ .

Note that although the above explanation is for the first order of the Fourier series, it is of course possible to obtain phase differences and perform correction for higher orders.

Further, when performing phase lag correction, smoothing with the previous correction amount may be performed in order to avoid sudden changes in the correction value. As a smoothing method, for example, there is the following formula (9).

φ' ₁ , _o = βφ _1,o + (1-β)φ' _1,o-1 ...Formula (9) where, β: Smoothing coefficient (0β1) φ' _1,o : Current correction value φ _{1 ,o} : Current detection value φ' _1,o-1 : Previous correction value Furthermore, the above-described phase lag correction method may be used in combination with various conventionally used correction methods.

<Effects of the Invention> According to the present invention, during continuous roll eccentricity control, the displacement command signal to the rolling cylinder and the actual displacement signal of the rolling cylinder are subjected to Fourier analysis, and each phase of the displacement command signal and the actual displacement signal is analyzed. Since the phase difference is calculated from the value, there are the following effects.

(1) Even if there are changes in rolling conditions such as changes in rolling speed, the phase delay can be accurately determined each time.

(2) It can automatically respond to changes in the rolling response characteristics over time.

(3) Detection is relatively simple, and a detection/correction device can be easily implemented.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing an embodiment of a roll eccentricity control device to which the phase lag correction method according to the present invention is applied, and FIG. 2 is an explanatory diagram of roll eccentricity control. In the drawing, 1 is a work roll of a rolling mill, 2 is a back-up roll, 3 is a rolling machine, 4 is a rolling force detector, 5 is a pulse oscillator as a rotational position detector,
6 is a rolling position detector, 8 and 21 are samplers, 9 is a calculator, 10 is a counter, 11 is a calculator for roll eccentricity waveform detection and control, 12 and 20 are converters, 13 and 22 are A/D converters 14 is a comparator, 15
is a servo amplifier, 16 is a servo valve, 17 is a reduction cylinder, 18 is a D/A converter, 19 is a computing unit,
23 is a phase delay detection calculator.

Claims (1)

[Claims] 1. In a roll eccentricity control device of a hydraulic rolling mill, a displacement command signal to a rolling cylinder and an actual displacement signal of the rolling cylinder are each subjected to Fourier analysis to calculate the difference in phase value between the two signals. A phase lag correction method for roll eccentricity control in which the difference between the phase values obtained is used as a phase lag correction amount for roll eccentricity control.