JPH0261845B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a sheet crown control method using adaptive control of a roll bender, and is intended to further improve setting control accuracy in sheet crown control.

[Conventional technology]

In multi-stage continuous rolling equipment, the rolling load distribution, roll gap, and roll speed of each rolling mill are set according to the rolling schedule, and the rolling load required for this setting calculation uses predicted values. However, the predicted value is not necessarily equal to the actual value, so we actually measure the rolling load when the plate is caught in the rolling mill, find the deviation from the predicted value, and use this deviation to adjust the rolling force of the subsequent rolling mill. Adaptive control is provided to modify the reduction and speed settings.

The deviation between the predicted value and the measured value of the rolling load can be determined at one specific stand or at each stand of the finishing rolling equipment. A load correction coefficient is obtained from this, and the predicted load is corrected based on this. In other words, the actual rolling load of i-stand is predicted (calculated) as PMi.
The rolling load is PSi, and the slope of the plasticity curve used in the calculation is
Qi, and the change in plate thickness due to this being actually Q′i is ΔHi (in this method, the deviation between the calculated value and the measured value is considered to be due to a change in the slope of the plasticity curve)
And, as is clear from Figure 2a, Q′i/Qi=
Since the relationship PMi/(PSi+Qi・ΔHi) holds, Ri=Q′i/Qi, the load correction coefficient Ri is set as Ri=PMi/PSi+QiΔHi, and this coefficient Ri is multiplied by the calculated rolling load PSj of the rear stand. That is, the calculated load (corrected calculated load) PS/~j of the stand is corrected as PS~j=Ri×PSj (2).

Incidentally, if the reduction screw is corrected by the operator or the like when the i-stand is engaged, the mill rigidity curve becomes like the points shown in FIG. 2b, and the operating point moves from B to B'. In this case, the plate thickness change ΔHi is the sum of the change in plasticity curve and the change in roll gap (change in mill stiffness curve).
Change in rolling load ΔPi=PSi−PMi, mill rigidity
Mi, and roll gap change amount ΔS _i2 = S _Si −S _Mi
Using ΔHi=ΔS _i1 +ΔS _i2 , where ΔS _i1 =ΔPi/M
It can be expressed as Further, the plate thickness change ΔHi occurring in the i-stand becomes the entry-side plate thickness error of the next i+1 stand, and in this case, the plasticity curve moves in parallel as shown by the dotted line in FIG. 2c. ΔH is the thickness change on the entrance side,
ΔSi is the change in plate thickness on the exit side due to the change in the plasticity curve (change in plate thickness on the input side), and this is the change in rolling load ΔPi=
There is a relationship of ΔP=M·ΔS for PSi−PMi. Also, as is clear from diagram c, ΔS (M+Q)=
Since there is a relationship of QΔH, the rolling load change ΔP is ΔP=
MQΔH/(M+Q). Considering this ΔP, the corrected rolling load PSj of the next stand (stand i + 1, this is j) is PSj = Ri (PSj + ΔP) ...... (3) Figure 3 shows the above control applied to multi-stage continuous rolling equipment. In the explanatory diagram, 10 is a steel plate that is a material to be rolled, 12, 1
4, 16, . . . are the i-th, i+1, i+2, . . . rolling stands, and 18 is a computer (process computer) for setting the rolling reduction in these rolling stands. The corrected screw values S _{i+1 and S i+2} of the i+1 stand and _i+2 stand are the corrected rolling loads.
P〓 _i+1 , P _i+2 to the screw values before correction S _Si+1 , S _Si+2 are used to calculate the following equation.

Performing such adaptive control can further improve plate thickness control accuracy. Note that in consideration of the change in plate thickness on the entrance side, it is necessary to make a correction using equation (3), but since this correction is only necessary for the next stage 14 after the measuring stage 12, the correction using equation (3) is omitted here. .

[Problem that the invention seeks to solve]

The deviation between the calculated value and the measured value of the rolling load is due to temperature estimation and changes in the components of the rolled material (approximately speaking, it is due to a change in the slope of the linearized plasticity curve), but the calculated rolling load can be adjusted by adaptive control. If you modify the roll setting gap, the shape of the plate, especially the crown of the plate, will change. The present invention aims to suppress the crown prediction error caused by such a load prediction error and the fluctuation of the plate crown due to this adaptive plate thickness control, thereby keeping the plate crown setting control accuracy within a desired range.

[Means for solving problems]

The present invention is a multi-stage continuous rolling facility where plate thickness control and crown setting control are performed at the same time.
PMi, and rolling load change ΔPPi due to plate thickness change
a calculation means for calculating a rolling load correction coefficient Ri;
The rolling load correction coefficient Ri is used to correct the roll gap of the stands after the next stage i+1 stand, and the crown change after the next stage i+1 stand is predicted using the correction coefficient Ri and the corrected roll gap S _i+1 . , and has a dynamic setting function, including a correction means for changing the setting value of the roll bender pressure of the stand before the stand is engaged (i+1) so that these become zero.

The crown is related to the rolling load P, roll bending force F, roll flatness Cf, and roll profile _C0 , and the control model equation is expressed as follows.

= f (P, F, Cf, C ₀ ) When automatically controlling the crown using this crown control model, the predicted load (the above-mentioned calculated load) based on finish setting calculation has conventionally been used. In order to improve crown setting control accuracy, the present invention has the following features:
The crown deviation is predicted from the error between the measured rolling load and the predicted rolling load of the front stage stand, and the work roll bender force of the rear stage stand is adjusted to eliminate crown deviation by adaptive plate thickness control and reduce this to zero. Correct the setting value.

To explain this with reference to FIG. 1, the same parts in this figure as in FIG.
This is the (i+2)th rolling stand. This multi-stage continuous rolling equipment is a finishing rolling stage, and although only three stages are shown in the figure, it generally consists of six, seven, etc. stages. When the plate 10 is caught in the i-stand (here, the first stage stand) 12, the measured rolling load PMi and the calculated rolling load PSi
Calculate the load deviation ΔPi=PMi−PSi and divide this load deviation by the mill constant M to get the mill elongation ΔS _i1 =
Find ΔPi/MMi. Further, the screw deviation ΔS _i2 =S _Si −S _Mi is determined from the difference between S _S and S _M described above, and the rolling load change amount ΔPPi is determined by the following formula.

ΔPPi=Qi×(ΔS _i1 +ΔS _i2 ) ………(6) Actual measurement of rolling load and rolling reduction, and the above ΔPi, ΔS _il ,
ΔS _i2 and ΔPPi are calculated for each stand after the next stand, and the rolling load correction coefficient Ri is determined using the following formula.

Ri=ΣPMi/Σ(PSi−ΔPPi)……(7) Once the rolling load correction coefficient Ri is determined, this is multiplied by the calculated rolling loads PS _i+1 and PS _i+2 , and then the i+1 stand 14 and the next Corrected calculation rolling load of i+2 stand 16 P〓 _i+1 = Ri・PS _i+1 , P〓 _i+2 = Ri・
PS _i+2 is determined, and from this the reduction is corrected as described above, but in the present invention, in addition to this, the roll bender pressure is corrected.

In other words, if such correction is made, the calculated rolling load will have a deviation ΔP〓 _i+1 = P〓 _i+1 −PS _i+1 , ΔP〓 _i+2 = P〓 _i+2 , PS _i+2
This deviation causes a change in the plate crown, and also causes a crown variation ΔC ^* due to adaptive plate thickness control. In order to reduce the sum of these to 0, the bending force must be changed to cause a change in the plate crown in the opposite direction. That's fine. That is, Generate bender force correction values ΔF _i+1 and ΔF _i+2 to be
Work roll bending force setting value of i+1 stand and i+2 stand F〓 _i+1 , F〓 _i+2 as F〓 _i+1 = F _i+1 +ΔF _i+1 ...(9) F〓 _i+2 = Set F _i+2 +ΔF _i+2 . Here, (∂C/∂P) _i+1 , (∂C/∂P) in equation (8)
_i+2 is the crown change due to rolling load change of stands i+1 and i+2, (∂C/∂F) _i+1 , (∂C/∂F) _i
+
2 shows the crown change in response to the change in the roll bending force of stands i+1 and i+2, and also
F _i+1 and F _i+2 indicate the calculated roll bending force of each stand i+1 and i+2, and ΔC ^* _i+1 and ΔC ^* _i+2 are i+
1 and i+2 This is the amount of crown change due to adaptive plate thickness control of each stand.

〔Effect of the invention〕

As explained above, in the present invention, the rolling load correction coefficient Ri is determined from the predicted value PSi of the first stage stand rolling load, the actual value, PMi, and the rolling load change ΔPPi due to the change in plate thickness, and this is used to calculate the rolling load correction coefficient Ri for the next stage stand. Since the rolling reduction of the subsequent rolling mill is corrected, the amount of crown change is predicted, and the setting of the roll bender pressure is corrected so that this amount becomes zero, the plate thickness and plate crown can be accurately controlled, which is extremely effective.

[Brief explanation of drawings]

FIG. 1 is an explanatory diagram of the present invention, FIG. 2 is an explanatory diagram of the operation, and FIG. 3 is an explanatory diagram of adaptive plate thickness control. In the drawing, 10 is a steel plate to be rolled, and 12, 14, . . . are stands of a multi-stage continuous rolling facility.

Claims (1)

[Claims] 1. In a control method for a multi-stage continuous rolling facility in which plate thickness control and crown control are performed simultaneously, the predicted value PSi of the rolling load of the front i-stand, the actual value PMi when the i-stand is bitten, and the plate thickness. Calculate the rolling load correction coefficient Ri from the rolling load change ΔPPi due to the change, use the rolling load correction coefficient Ri to correct the roll gap of the stands after the next stage i+1 stand, and use the correction coefficient Ri to correct the roll gap of the next stage i+1 stand. The subsequent crown change is predicted, and the crown change based on the above adaptive plate thickness control is predicted, and the roll bender pressure of the stands after the (i+1) stand is adjusted before the (i+1) stand bites so that the sum of these changes becomes zero. A plate crown control method using work roll bender adaptive control characterized by changing set values of.