JPH04200915A - Method for controlling plate thickness in rolling mill - Google Patents

Abstract

PURPOSE:To control plate thickness with high accuracy by operating controlling device for disturbance due to the eccentricity of a roll in addition to plate thickness controlling method by thickness indicators and rolling load meters on the outlet side and on the inlet side. CONSTITUTION:When disturbances given to a rolling mill are corrected, a rolling roll gap is not only adjusted but the disturbances are classified into a disturbance by the essentrically of the roll and a disturbance by thermal expansion and friction, etc., of the roll and a rolling roll gap adjusting device and a rolling roll or payoff reel speed adjusting device are operated respectively in accordance with the estimate of each those disturbance values and controlled to constrain the variation of plate thickness. Not only the plate thickness on the inlet side, the plate thickness on the outlet side, the tension, the rolling load which are conventionally signals for estimating and detecting the disturbances but the variation of the plate thickness by the eccentricity of the roll can be controlled. Consequently, high accuracy rolling of the plate thickness can be executed.

Description

Detailed Description of the Invention (Technical Field) The present invention relates to an improvement in a method for controlling plate thickness in a rolling mill.
In particular, the present invention relates to a method that can suppress periodic plate thickness fluctuations and obtain higher plate thickness accuracy.

(Background technology) Traditionally, the rolling mill roll gap has been changed to control the plate thickness of a rolling mill, but if you try to control the plate thickness only by operating the rolling roll gap, it will be difficult to control the plate thickness due to the change in the roll gap. Due to tension changes, especially rear tension changes,
Since the desired plate thickness accuracy could not be obtained, when considering plate thickness control, it was necessary to also perform tension control at the same time.

For this reason, several methods have been proposed in the past to perform both thickness control and tension control, and the inventors have previously proposed patent application No. 61-6014/I and In Japanese Patent Application No. 62-2532/19, we proposed a method in which rolling roll gap control and rolling roll speed control are connected and performed simultaneously to achieve highly accurate plate thickness control.

Among them, the plate thickness control method disclosed by the present inventors in Japanese Patent Application No. 62-253249 is based on changes in rolling load,
Adjust the rolling roll speed (or adjust the payoff reel current, in other words, adjust the payoff reel speed by controlling the payoff reel current) to adjust the disturbance applied to the rolling mill based on the detected values of the change in the thickness of the inlet side, the change in the outlet side, and the tension change. Disturbances that should be corrected only by adjusting the rolling roll gap, disturbances that should be corrected only by adjusting the rolling roll gap, and disturbances that should be corrected by both of them are estimated. Since the gap and rolling roll speed or payoff reel current (speed) adjustment devices are operated to suppress plate thickness fluctuations, unnecessary commands are less likely to be given to each control device. Therefore, in addition to reducing the variation in plate thickness tension when a disturbance is applied, there are four types of detection signals used for disturbance estimation: inlet side plate thickness, outlet side plate thickness, tension, and rolling load. Since it uses a rolling mill, it is possible to more accurately estimate the disturbances applied to the rolling mill, and it is also possible to perform disturbance compensation suitable for those disturbances, which allows for more accurate plate thickness measurement. It shows the characteristics that can be obtained.

However, even with plate thickness control methods that exhibit such excellent characteristics, they are completely powerless in terms of suppressing periodic plate thickness fluctuations caused by roll eccentricity during rolling. There it was. In other words, the center of rotation of the rolling mill rolls, especially the backup roll, is misaligned with the roll axis, and when the rolls are rotated under such roll eccentricity, periodic sheet thickness fluctuations are caused. However, in the plate thickness control method disclosed in the above-mentioned Japanese Patent Application No. 62-253249, no consideration was given to such periodic variations in plate thickness.

(Problem to be solved) Here, the present invention has been made against the background of the above-mentioned circumstances, and the problem and problem lies in the plate thickness of the rolling mill disclosed in the earlier Japanese Patent Application No. 62-253249. By improving the control method, estimating the disturbances applied to the rolling mill more accurately, and performing disturbance compensation suitable for those disturbances, we can suppress plate thickness fluctuations caused by roll eccentricity that occur periodically, and improve This is done to ensure that highly accurate plate thickness can be obtained.

(Solution Means) In order to solve the above problems, the present invention provides a method for controlling plate thickness in a rolling mill equipped with a roll gap adjustment device and a roll or payoff reel speed adjustment device. , detect changes in rolling load, inlet side plate thickness, outlet side plate thickness changes, and rear tension changes in a predetermined rolling stand, and based on these detected values, correct disturbances applied to the rolling mill only by adjusting the rolling roll speed. Disturbances that should be corrected only by adjusting the roll gap, disturbances that should be corrected by adjusting the roll or payoff reel speed, and disturbances that should be corrected by adjusting the roll gap only. The disturbance is further classified into disturbance due to roll eccentricity and disturbance due to roll thermal expansion, roll wear, etc. other than roll eccentricity, and the value of each of these disturbances is estimated.
The plate thickness in the rolling mill is characterized in that the rolling roll gap adjusting device and the rolling roll or payoff reel speed adjusting device are respectively operated according to the estimated value to suppress plate thickness variation in the rolling mill. The gist is the control method.

In short, the present invention provides a method for controlling a plate thickness according to Japanese Patent Application No. 62-253249, which uses a rolling mill equipped with an inlet plate thickness gauge, an outlet plate thickness a1, a rolling load meter, and an inlet tension gauge as sensors. Disturbances applied to the machine are classified into three types, and among these, disturbances that cannot be compensated for only by adjusting the rolling head and leg gap are classified into disturbances caused by roll eccentricity, and disturbances caused by roll thermal expansion, roll wear, etc. other than roll eccentricity. 4), and compared to the prior patented method, the disturbance due to roll eccentricity that periodically causes plate thickness fluctuations is estimated,
By operating a predetermined adjustment device based on this, such periodic plate thickness fluctuations can be suppressed, and it is therefore possible to realize a plate thickness with higher layer accuracy.

(Specific Configuration/Examples) The present invention will be explained in more detail below.

First, the mathematical model of the cold rolling mill is expressed by the following equations (1) to (5).
It is expressed as Note that here, the rolling mill of the jingle stand is targeted, and therefore the rolling roll gap change command: u9 and the payoff reel (rewinding reel) current change command: I, oR1 In other words, the payoff reel speed change command is It will be required.

・ ・ ・(3) h−ε,・σ,moε,・(S0ds)”−ε1.・H-
1-dl.

・ ・ ・(4) Po−ε,・σ, +(εs−1)(S + ds)+
εo' H+ d h... (5) In these equations, the meaning of each symbol is as follows, and each variable is a non-dimensional value obtained by making a slight deviation from a steady-state value into a steady-state value. be.

σb = Entrance side tension H: Entrance side plate thickness PH: Mill elongation (-rolling load/mill constant) h: Output side plate thickness S: Roll gap us: Roll gap change command N,. □: Payoff reel rotation speed ■1. , l: Payoff reel current (change command) d
s, d N, d h: Disturbance M1. M.N., M.S.
MH, Qe, Q+, ε1. ε8. ε□: Coefficient determined by rolling conditions, etc. Also, the purpose of controlling the rolling mill can be expressed mathematically as follows.

h-σ, -0 (6) Here, in order to adjust the responsiveness from IPOR to NPOR and from U to S, the following operations are performed.

I POR-ω+ NPOR+ Ll +'
...(7) us = ωsS 1-us'
...18) However, ωI, ωS: feed hack gain, u, I, usl, new manipulated variables.

Then, by the feedback of equations (7) and (8), the poles of the system are approximately adjusted as follows from (9).

Here, the feedforward control that compensates for the disturbance and achieves the control objective (6) is as follows.

・ ・ ・02) Here, consider the following disturbances that should be dealt with.

ds = dsC4-d, S ---(+
3)...θat-acosωL...(15')-
-d, -0...06) at dN =0 ・ ・ ・(17
)L In this equation 03), dsC represents a disturbance other than roll eccentricity due to roll thermal expansion, roll wear, deformation resistance change of the rolled material, etc., and dSs represents a disturbance due to roll eccentricity, and ω is the eccentric angular frequency.

By the way, if it is considered that the differential value of the equations 03) to 0'7) and the entrance side plate thickness variation (H) is "0", the feedforward control can be simplified as follows.

us' = -Tsωd,'10(1-ω)...08) Therefore, (7), (8), 08) and 09 of ``2''
), the manipulated variable is given as follows.

us = ω5S-TSωds'+(1-us) -...
・C! ([1 u + = ω+ (NllOR+ d N)・・
(211) In order to realize this QO and Equation 09, a method of estimating disturbance using an observer will be described below.

1i]" 1-□JijoobjunjiL "&ss, "l, f;:ds3. Assuming that the estimated value of dh is a known function, the above (3), (4),
04), From the Ci1 formula, the ds'+S estimation observer is given as follows.

・ ・ ・t22) y, -g+Ksc+';JS" 10-ghε S ・ ・ ・@ ε 3 ε S
ε S・・・Q41 U, −us Tsω'iss +(1−ωS)・・
・(2) However, g, KsC are estimated values of S, dsc. 3'
h? h is the estimation error and k is the observer gain.

From the above equations t22) to I2ω, the d, c, and S estimation observers are as follows. Note that the estimation error (yh'
S'h), only h has a slight time delay (material transfer time between roll stand and plate thickness gauge), but (
Since the target is the disturbance d/d t)・g,'=o, there is no problem. Also, it is the outlet side plate thickness detected by the hX No. J plate thickness gauge.

・　・　・(26) However, a, - (ω, -1,) /Ts a2--- is 5.

b dss-U knee estimation-observer (4) above,
From (5) and Equation 09, the d sS and a sS estimation observers are given as follows.

ys(-τ) = h, P+4(t-τ)
--・Q81'Si', (t-τ)-Moya (-τ)-
l-'JsS(t-τ)+fsc(t,-τ)...e8) In the above formula, τ is the material transfer time between the roll stand and the plate thickness gauge, and if the time is shifted by τ, What I'm thinking is
This is to adjust the time to hX (the thickness of the exit side plate detected by the plate thickness gauge). Also, from the above equations (4) and (5), hX=S(t-r) +ds"(t-r) +ds'(
t-T) 10P. (−τ) ...(30) Therefore, (yS(t-τ) -ys(t-τ)] is the estimation error of d sS, d 5s (7). However, K SS+ , , s are estimated values, k El, k
E2 is an observer gain.

Further, from equations (5) to (29), the following equation is obtained.

-g(t-r)-'Jsc(t--r) 1...(3
D Note that fss(t-τ) = a sin (ω(-τ))=
a sin ωt −cos ωτ −a cos 6) t °sin ωτ=cos ω
τ・dsS(t) 'iss(t-τ) = a cos (ω(t-τ)
)=a cos ωt ゝcos ω τ+a
sin O)t ・sin ω τ=cos
ωr ・4 ss(t)+sin ωr ・ds
”(t), so the following formula ((goods) and 03 hold true.

・ ・ ・(((goods) ・ ・ ・ 33 And from these (to) and (31 formula), the above (3D formula) is transformed as follows.

- Miya(t-τ)-lsC(t-τ)) -a3C(-τ))...G4 However, 1. cosωτ−kE2sinωτa
a = kE + sinωr k): 2 cO
The equation 0 that takes 5ωr is the one that gives the estimated values of d, , S, a, and S.

■1 View Observer From the above (5) and formula 00, the dh estimation observer is obtained as follows.

+kp(yp Vp) ・ ・ 4Vp -PM ・・・(30yP-
ε, σ5+ (ε, -1) (Miya+Kori S'+KS”) 1ε+
+ H + K h ... (b) It takes (scream) Substituting the @ expression into the 09 expression and rearranging it, we get the following.

-kP (εs-1,)(g+1s'+]ss)-9-
1 kP (Pε, σ5 + εHH) ・ ・ ・ (38)
From equations C(2) and (+7), dN, :! : Even if you try to configure an estimation observer for NPoR, it becomes unobservable and estimation cannot be performed. However, as understood from the above (2++ formula), since it is only necessary to know (N r. □ - 1 - dN), an estimation observer of (NPOR + d N ) is constructed. The above (]), (2) and From formula 07), the (NPOR+dN) estimation observer is as follows.

-Qc ・6b + Q+ ・I pot++kr(V
e V, )・・・・(38) ...0...(41) Here, the manipulated variable 2] (rp.R) realized using the estimated value is calculated as follows from the above formula 09. become.

I POR-ω+ (NP, OR+K N)...(
42) Then, by substituting (40) to (42) 2 into the above (39) 2, we get the following.

This equation (43) is (N P., +d, -, □/M, ・
The value of σ, ) will be estimated.

-i→JM-Atonement"Tosuichiko 3As we have discussed above, (26), (34)
, Equations (38) and (43) are observers for estimating the disturbance, and Equations (20) and (21) are control equations that give the manipulated variable based on the estimated disturbance. To summarize, we get the following.

-y, =Ar z 10A, z (t-τ)d 5th + B P 3' + E p V a ...
(44) u-Cpz +Dpy +Fry, + ・
...(15) Z = (g, '1Jsc, ``6s
”, 7s”, Kh.

FJrop +Ks−k T/ MN ・σb)Ty=
(σ-, hx, PM)" yd-(PM(t-τ), Hl" u = (I POR, u s) T Also, Ap, Ad, B p, C2, Dp, EP
, F p are respectively shown as follows.

a,, = (ωS -])/T.

a +4””-ω a15=,1. □／ε5 ezz-kh azs=　　J/ε.

as+=-kp+cos ωr-ktzsin (
z) Ta33° a 3IcO3ω r a 3a= a a+sin ωτ+ωa<+=
kFIS:n ωr ktzcos ωra
43= a a1cO3(t) r-6) aa4=
a 4+sin ω Ta s + −k p
(ε, -I) a s s -k p a b+ = k TMS/ MN ab5-Q+ω+Ms/IVL+/ εsa7.6--
To, +Q, o>.

bz+-khε, /ε3 b2□−kh/ε.

b3□--C3゜ b42- a4+ b, , , --, ε.

bs3=kp bb+-Q-ktM f/MN +kt/MN(kT+Q+ω1) e1□-(ωs 1)/T-・C0,/ε.

ezz−khεH/ε5 e5z= kpεH eb2= Q+ωI(MS/M, ・ε,/ε3MH
/M N) kTMo/MN C+s−−ω+Ms/Ms/ εs C162ωI C21°ω5 C22−ωs1 G C24−−T3ω (zs−(ωS ])/ε3 dll−ωI k T/ M ,.

f12-1ω+(Ms/MN・εu/εs
Mll/MW)r2□−(ω,−1)εH/ε.

A block diagram of the configuration of the compensator expressed by such a formula is shown in FIG. 1.

Further, FIG. 2 schematically shows a model of the plate thickness control method according to the present invention as described above.

That is, in FIG. 2, in a rolling mill that rolls a predetermined material to be rolled (metal plate) 2 while unwinding it from a payoff reel 4 and running it, the rolling stand 6 is equipped with a rolling device such as a hydraulic rolling device. A roll gap control (adjustment) device 8 is provided, and a load cell 10 for detecting the rolling load is also provided. Further, on the exit side of the rolling stand 6, a plate thickness gauge 12 for detecting the thickness deviation on the outlet side is provided, while on the inlet side, a plate thickness gauge 12 for detecting the thickness deviation on the input side is provided. 14 and a tension meter 16 for detecting changes in rear tension. In addition, a payoff reel speed control (adjustment) device 1 is provided on the payoff reel 4 on the rear side of the rolling stand.
8 is provided.

While the rolling load of iJ in the rolling stand roll is detected by the load cell 10, exit side plate thickness information from the exit side plate thickness gauge 12, inlet side plate thickness information from the inlet side plate thickness gauge 14,
Tension information from the tension side 16 is respectively retrieved,
The disturbance is estimated based on the equation (44), and the disturbance compensation operation amount is calculated based on the equation (45), and the operations of the rolling roll gap control device 8 and the payoff reel speed control device 18 are performed based on the calculation. Control will be carried out.

Incidentally, in order to confirm the effect of the plate thickness control method in the rolling mill according to the present invention, under the simulation conditions shown in Tables 1 and 2 below, when there is an eccentricity control function (Case 1: Wooden invention) The results of investigating plate thickness fluctuations in the case where there is an eccentricity control function (case 2: comparative example) are shown in FIGS. 3(a) to 4(f) and 4(a) to (f).

Note that Table 1 below shows the oblique gain and feedback gain, and Table 2 shows the parameters of the model. And the values in Table 2 are the rolling speed] 000
This is the value when m /min.

In addition, the disturbances assumed in the simulation are a 1% step-like change in the entrance side plate thickness at time 0 seconds and a 0.5% change in the roll gap due to roll eccentricity. (44)
, The compensator summarized in Equation (45) is
Although the simulation includes a feedforward control function that actually measures and utilizes the change in thickness (I), it was decided that the entrance plate thickness variation (H) could not be actually measured in this simulation.

As is clear from the simulation results shown in Figures 3 and 4, by adding the eccentricity control function according to the present invention, plate thickness fluctuations due to eccentricity are almost 100% removed (see Figure 3), and the eccentricity control function Compared to the case where there is no eccentricity control function (see Fig. 4), superior results are obtained regarding plate thickness variation control, and according to the method of the present invention, mutual interference between the eccentricity control function and other functions is eliminated. Therefore, the control system is stable, and there is no steady deviation between the outlet side plate thickness and the input side tension.

The present invention is applicable not only to the Shingel stand rolling mill used in the explanation described in - but also to a tandem rolling mill, and in that case, the speed change command of the payoff reel This serves as a speed change command to the rolling rolls on the stand. Further, in the case of a tandem rolling mill, it can be applied to any stand.

In addition, although not listed, various changes, modifications, improvements, etc. can be made to the present invention based on the knowledge of those skilled in the art without departing from the spirit of the present invention, and any of these may be made. What is within the scope of the present invention is
should be understood.

(Effects of the Invention) As is clear from the following explanation, according to the plate thickness control method according to the present invention, the previously proposed patent application No. 62-25324
While enjoying the excellent effects that can be achieved by the method No. 9, we also include the disturbance due to roll eccentricity as the disturbance to be corrected, estimate it, and adjust the adjustment device according to the estimated value. Since this method is designed to be operated, it is possible to realize plate thickness control with higher precision than the previously proposed method.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing the configuration of a compensator according to the present invention, FIG. 2 is a schematic system diagram of a rolling mill showing an example of implementation of the rolling control method according to the present invention, and FIG. a)～
(f) and FIGS. 4(a) to 4(f) are graphs showing simulation results of plate thickness control with and without the eccentricity control function, respectively. 2: Rolled material 4: Payoff reel 6: Rolling roll gap control device 10: Load cell 12: Output side plate thickness gauge 14: Inlet side plate thickness gauge 16: Tension gauge 18: Payoff reel speed control device Applicant: Sumitomo Light Metal Industries, Ltd.

Claims (1)

[Claims] A plate thickness control method in a rolling mill equipped with a rolling roll gap adjustment device and a rolling roll or payoff reel speed adjustment device, which includes rolling load changes, entry side plate thickness changes, exit side plate thickness changes, and rear tension changes at a predetermined rolling stand. , and based on these detected values, the disturbances applied to the rolling mill are determined to be a disturbance that should be corrected only by adjusting the rolling roll speed, a disturbance that should be corrected only by adjusting the rolling roll gap,
Disturbances that should be corrected by both rolling roll or payoff reel speed adjustment and rolling roll gap adjustment are classified into disturbances that should be corrected by both rolling roll or payoff reel speed adjustment and rolling roll gap adjustment. Disturbances due to roll thermal expansion, roll wear, etc. are classified, and the values of each of these disturbances are estimated, and the roll gap adjustment device and the roll or payoff reel speed adjustment device are respectively operated according to the estimated values. A method for controlling plate thickness in a rolling mill, characterized in that variation in plate thickness in such a rolling mill is suppressed.