JP2557858B2 - Meandering control method in steel plate rolling mill - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a meandering control method for a steel plate rolling mill that suppresses and controls meandering of a material to be rolled.

[Conventional technology]

As a conventionally known control method, a method of directly detecting and controlling the amount of meandering of a plate material by a measuring instrument and information corresponding to the amount of meandering include a load difference between the rolling roll left and right or a load difference between the roll left and right and a gap between the roll left and right. There is an example of using the sum of the differences. For example, Japanese Patent Laid-Open No. 55-88914 discloses a control system configuration shown in FIGS. 2 and 3.

FIG. 2 shows the meandering control by the meandering amount detector, in which the position and meandering amount of the rolled material (1) rolled by the rolling roll (2) are detected by the detectors (17), (18). Then, by the processing decision made by the meandering control calculation unit (16), the roll-down position controllers (11), (12) on the left and right sides of the roll.
The meandering of the rolled material is controlled by adjusting the rolling position difference (also referred to as the leveling amount) between the right and left portions of the roll. In FIG. 3, the detection values Pw and Pd from the rolling load detectors (5) and (6) on the left and right of the rolling roll and the outputs Sw and Sd from the reduction position detectors (7) and (8) are used to determine the device. (13),
And (14), load difference signal δp, reduction position difference signal δs
After calculating Is shown to adjust the roll roll position difference.

In any of the above methods, the control calculation for improving the control effect is the meandering amount yc or the meandering amount. The rolling position difference adjustment amount δs ^* is determined by the proportional amount and the time derivative amount. That is, (proportional + derivative) control calculation is performed.

[Problems to be solved by the invention]

However, in the control method using the meandering amount detector, since the detector is installed at a point separated from the rolling mill by a certain distance or more, it is impossible to detect the amount of meandering just below the roll, and it is installed on the downstream side. In this case, there is a time delay until the meandering of the leading end of the plate material is detected. In addition, if it is installed on the upstream side of the rolling mill, there will be a portion where the meandering phenomenon cannot be observed at the tail end of the material. Moreover, considering that the frequency of meandering in the normal rolling operation is almost at the leading and trailing ends, it may be impossible to sufficiently control the meandering in this detector.

In the method of determining the control operation as the material meandering equivalent amount based on the value obtained by adding the load difference detector δp at the left and right ends of the rolling roll and the roll rolling position difference detection value δs, the change in the inlet plate thickness difference at the left and right ends of the material If cannot be ignored, an error is unavoidable in the meandering amount calculation by adding the above load difference detection value δp and the reduction position difference detection value δs.

For example, according to "Theory and Practice of Sheet Rolling" published by the Iron and Steel Institute of Japan on September 1, 1984 (Fig. 9.44) as a model formula for explaining the meandering phenomenon, as a factor that determines the sheet meandering phenomenon. , The reduction position leveling δs and the difference between the right and left ends of the inlet side plate thickness change (the amount of the inlet side plate thickness wedge) δH, and as a result, the meandering yc of the plate material occurs and the rolling load difference δp between the left and right rolls is induced. It is described as a structure. (Citation in this application as FIG. 4) Based on the principle of occurrence of meandering, the amount of meandering cannot be estimated by adding the rolling position difference detection value δs and the rolling load difference detection value δp or by any combination. is there.

Due to the two input factors {δs, δH}, two results {yc,
One input factor {δ
Knowing the other result {yc} from s} and one result {δp} would logically reveal the contradiction.

In the meandering equivalent amount calculation by adding the load difference detection value δp and the rolling position difference detection value δs, it is determined that an error is included in a situation where there is a change in the amount of wedges on the inlet side plate thickness. The main cause of the meandering of the plate material is the difference in plate thickness at the left and right edges of the entrance side plate, and some fact must be resolved.

The present invention has been made in order to solve the above-mentioned problems, and a conventionally used rolling-down position difference detection value δ
s and rolling load difference detection value δp, and by using the knowledge of the linear model that describes the meandering phenomenon, the meandering detector is not installed, and even when the wedge amount of the incoming side plate thickness changes, it is always under the roll. It is an object of the present invention to provide a method of knowing an accurate amount of meandering of a vehicle and reliably suppressing and controlling the meandering.

[Means for solving problems]

In the meandering control method according to the present invention, the left and right rolling reduction position difference values δs and rolling load difference values δ that can be detected in a normal rolling mill.
By performing the calculation of the meandering phenomenon state estimation using a model expression describing the meandering phenomenon in addition to p, it is possible to accurately estimate the meandering amount and realize a highly accurate meandering control.

[Action]

In the meandering amount estimation calculation in this invention, the detection signal Δp,
In addition to δs, it is possible to estimate all state variables that govern and determine the meandering phenomenon by using the structure of the model equation describing the meandering phenomenon and the coefficient value.

By inputting the rolling position difference value δs and the load difference value δp, the meandering amount yc immediately below the roll and the time derivative of the meandering amount Further, it also estimates and outputs the entrance side plate thickness wedge amount δH.

Therefore, even for disturbances due to changes in the amount of wedges on the inlet side,
The meandering amount can be accurately estimated.

〔Example〕

 An embodiment of the present invention will be described with reference to the drawings.

In FIG. 1, (1) is the material to be rolled, and the load detectors (5) and (6) detect the amount of rolling load at the left and right portions of the roll. (7) and (8) are roll pressure reduction position detectors on the right and left sides of the roll.
The (9) and (10) pressure reduction position controllers (11) and (12) respectively constitute two sets of closed servomechanisms as pressure reduction position control systems.

The rolling load amounts Pd, Pw on the left and right parts of the roll detected by the detectors (5), (6) are calculated by the load difference value δP in the load difference value calculating device (13), and the rolling positions on the left and right parts of the roll are calculated. The signals Sd and Sw are guided to the reduction position difference amount calculation device (14), calculated as the reduction position difference value δs, and input to the state amount estimation calculation unit (15). In this part, by performing the estimation operation detailed below with the already known coefficient data, after a very short time from any estimated state quantity initial value, all internal state quantities related to the meandering phenomenon are calculated. It is calculated as an estimated value.

Details of the state quantity estimation calculation will be described below. First, the model of the meandering phenomenon (FIG. 4) quoted from a known document is transformed into a completely equivalent block diagram and shown in FIG. 5 for the sake of simplicity of explanation. Here, the symbol S means the Laplace operator and therefore 1 / s means the integration mechanism.

The transformation from FIG. 4 to FIG. 5 is obtained by repeatedly executing the “block diagram equivalent conversion procedure”.

 Since the transformation is performed regardless of the term of the equivalent conversion, the procedure will be described as follows: i) Drawing of relational expression from FIG.

Focusing on υ in FIG. 4, Focusing on δh, Focusing on ω, Focusing on y _C , Focusing on δP, Is made from Fig. 4. here, Then, the above equation (1) becomes Becomes From the above formula (3), further, And the left-hand side coefficient is simple, If you say, Becomes By substituting equation (6) into equation (3), In order to eliminate the variable υ from this expression, equation (6),
Substituting equation (1) 'into equation (7).

From equation (6), From equation (7), Substituting equation (10) into equation (5) eliminates ω.

Summarizing with δP, here, Then Next, by substituting δh in the equation (9) into the equation (4),
The δh term is deleted.

When the equation (13) is substituted into the equation (15), the δP term is deleted.

Therefore, the expressions in FIG. 4 and FIG. 5 are equivalent expressions of the same phenomenon, and the expression expression based on FIG. 5 also only expresses the same thing as the original expression FIG.

Next, the mutual conversion between the coefficient values used in the above equation (16) and the coefficient values used in the explanation of FIG. 5 can be summarized as follows.

Next, regarding the mechanism of the meandering phenomenon shown in FIG. 5, the meandering amount just below the roll is changed to the state variable according to the teaching of the logic about the linear control system. And its time derivative is the state variable Is expressed by the following differential equation.

Here, δH and δs mean the change in the amount of wedges on the inlet side plate and the amount of reduction position leveling, respectively.

Further, as shown in FIG. 5, the rolling load difference amount δP is related to the above variables as follows.

δP = KPy · X ₁ + K _PH · δH + K _PS · δs (2) This load difference δP can be regarded as an output amount detectable by a load meter.

The rolling position leveling amount δ _S can also be detected.

The load difference δP and the rolling position leveling amount δ _S can be regarded as inputs to the phenomenon.

If the entrance side thickness wedge amount δH is undetectable and is replaced with the state variable X ₃ , the differential equation system describing the mechanism of meandering can be arranged as follows.

As The above equations (4) and (5) are model equations for estimating the entrance side plate thickness wedge, and are generally expressed as follows.

The variables y and u can be detected as described above. According to the technology of the state observer, the state variables that cannot be directly detected in equation (4) Can obtain an estimated value by executing the following calculation.

State variable vector An estimate of Then, the following formula is the state quantity Generate

Here, the coefficients A, b, c, d are the same as those used in the equations (4) ′ and (5) ′, and are the same as the coefficient array in the equations (4) and (5). Further, the gain constants {g ₁ , g ₂ , g ₃ } in the equation (6) can be set appropriately based on the following principle.

The calculation shown in equation (6) is an arbitrary initial estimated value It is explained as follows that the estimated value of the change of the true state quantity shown in the equations (4) and (5) can be obtained by starting from.

That is, the true state quantity of the target And its estimated state quantity Then, using equations (4), (5), and (6), As already mentioned, the coefficients A and C are known,
Gain constants {g ₁ , g ₂ , g ₃ } in the estimated arithmetic expression of equation (6)
It is possible to make the estimated error amount zero from any initial estimated error amount within an arbitrary time by properly selecting. More specifically, if the gain constants {g ₁ , g ₂ , g ₃ } are chosen so that all the eigenvalues of the coefficient matrix in the lowermost equation of Eq. The estimated error amount within a certain time from It is known that B converges to zero as a basic matter of linear ordinary differential equations.

In other words, no matter what initial value the state estimation calculation shown in Eq. Is always the true state quantity It means that a constant value can be obtained. The estimated state quantity obtained by this estimation calculation is the estimated quantity corresponding to the meandering amount X ₁ (= yc) of the target meandering phenomenon just below the roll. And the time derivative of the change in meandering amount, And the estimated value for the entrance side plate thickness wedge amount X ₃ (= δH), both of which are extremely important for determining the operation amount for the meandering control.

Since the meandering amount estimate just below the work roll and the time derivative of the meandering amount change are obtained by the estimation calculation,
In the control operation amount determination calculation unit, the same effect as the conventional (proportional + derivative) type control calculation is generated by simply adding the above two estimated amounts.

The state quantity estimated by the state estimation calculation section (15) is guided to the meandering control calculation section (16). The meandering control calculation unit 16 calculates the meandering estimation amount c and the meandering change differential amount supplied from the state amount estimation calculation unit 15. Is multiplied by an appropriate coefficient according to the rolling mill constant and rolling conditions and added to determine a command value δ _S ^* for adjusting the rolling position difference between the right and left portions of the roll to converge the estimated meandering amount to zero. . Then, this command value δ _S ^* is applied to the rolling position control 11,1
The hydraulic cylinder mechanisms 9 and 10 are controlled by the output signals of the pressure reduction position controllers 11 and 12 to reduce the meandering amount.

In the above-described embodiment, the operation adjustment output for meandering control is input to the roll reduction control device that controls the hydraulic reduction, but the same effect can be expected with an electric-type reduction position control device.

In addition to the case where the operation amount adjustment based on the estimation of the meandering amount is performed by the difference between the pressure reduction positions of the left and right portions of the roll, the meandering control device is also effective by adjusting the values at the left and right ends of the work roll bender force.

〔The invention's effect〕

By using the above control method, it is possible to calculate the amount of meandering just below the roll without installing a meandering amount detector. The undetectable section can be overcome. In the present invention, the mechanism of the meandering phenomenon is modeled for the error factor resulting from the change in the amount of wedges on the inlet side thickness that is unavoidable in the calculation of the meandering equivalent amount obtained from the load difference signal δ _P and the rolling position difference signal δ _S that have already been put to practical use. By performing the estimation calculation described above and estimating the entrance side plate thickness wedge amount disturbance as well, it has become possible to accurately perform meander estimation.

Even in a rolling situation in which the amount of wedges on the entry side thickness changes momentarily, it is possible to accurately recognize the amount of meandering of the plate material just below the roll.

Since the time differential value of the change in the meandering amount can be known at the same time as the estimation of the meandering amount just below the roll, it is not necessary to add a device / circuit for the differential control, which is indispensable to the meandering control calculation unit. In the above, there is also an effect that the configuration of the control calculation unit is extremely simplified.

[Brief description of drawings]

FIG. 1 is a block diagram showing a meandering controller according to an embodiment of the present invention, FIG. 2 is a block diagram showing an example of a conventional meandering controller using a meandering detector, and FIG. 3 is a conventional meandering amount. FIG. 4 is a block diagram showing a calculation and control device, FIG. 4 is a known model block diagram for explaining the meandering phenomenon, and FIG. 5 is a block diagram of the occurrence of the meandering phenomenon used in the present invention. In the figure, (1) …… Rolled material (2) …… Rolling rolls (5), (6) …… Rolling load detectors (7), (8) …… Rolling position difference detector (11), ( 12) ...... Roll-down position control system (13) ...... Load difference calculation part (14) ...... Roll-down position difference calculation part (15) ...... State estimation calculation part (18) ...... Meandering control calculation part. The same reference numerals in the drawings indicate the same or corresponding parts.

Continuation of the front page (56) References "Theory and experiment of strip rolling" Published by The Iron and Steel Institute of Japan (September 1, 1984) P. 244 Figure 9.44 Hideki Kimura "Theory of Dynamic Systems" Business Book Co., Ltd. (July 18, 1974) P. 37-P. 44

Claims (1)

(57) [Claims] 1. A left-right load amount difference amount and a left-right reduction position difference amount of a rolling roll of a steel plate rolling machine for rolling a plate material are detected, and the detected load amount difference amount, reduction position difference amount, and meandering phenomenon are detected. Based on the entry side plate thickness wedge estimated using the described model formula, the estimated meandering amount and the meandering change differential value immediately below the rolling roller related to the meandering phenomenon are estimated and calculated, and the estimated meandering amount and the meandering change differential value are estimated. A meandering control method for a steel sheet rolling machine, comprising: determining a command value for adjusting a rolling position difference between the left and right sides of the rolling roller based on the value, and adjusting the difference between the rolling position between the left and right sides of the rolling roller according to the command value.