JP3129162B2 - Method and apparatus for controlling thickness of tandem rolling mill - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and an apparatus for controlling the thickness of a tandem rolling mill in which a plurality of rolling mills are continuously arranged, and more particularly to a highly accurate control method and apparatus.

[0002]

2. Description of the Related Art The quality of a sheet material produced in a tandem rolling mill depends on obtaining a desired sheet thickness. Various control methods have been proposed to obtain a desired plate thickness.

[0003] Among them, in a tandem rolling mill, there is a sheet thickness control method utilizing a constant law of mass flow. The constant law of mass flow is given by the following equation: H · V _E = h · V _D (H: Thickness of rolling mill entrance side, V _E : Speed of rolling mill entrance side, h: Thickness of rolling mill exit side, V _D : Rolling mill than the actual value of the output-side speed) each rolling mill exit side and plate thickness are detected by the plate speedometer and a plate thickness meter provided on the inlet side and the plate speed, plate thickness h _m of the exit side just below roll, h _m = V _E / V _D · H _X Here, when the target thickness of the stand delivery side is h _ref, the integral value of the deviation between the target thickness h _ref plate thickness h _m and stand delivery side of the roll immediately below the delivery side of the stand Σ (h _ref -h _m )
Is added to the speed command of the stand at the preceding stage as a speed correction amount, a desired plate thickness can be obtained. In this way, from the actual sheet speed values before and after the rolling mill and the actual sheet thickness values on the entry side of the rolling mill, the sheet thickness immediately below the roll of the rolling mill is calculated using a mass flow method, and this sheet thickness and the Conventional mass flow thickness control devices adjust the speed of the rolling mill in front of the rolling mill so as to reduce the deviation from the target thickness determined by the rolling schedule.

[0004] The above prior art is described in "Theory and Practice of Sheet Rolling" (edited by the Iron and Steel Institute of Japan), page 301, JP-A-4-52016.
No., published in Japanese Unexamined Patent Publication No.

[0005]

[SUMMARY OF THE INVENTION However, a plate speed of the entry side as described in the prior art, even if the operation of the V _E / V _D on the basis of the detected value detects a plate speed of the outlet side very Accuracy was poor. That is, during low-speed operation, V _E and V _D each have a small value, so that the value of V _E / V _D greatly changes even with subtle changes in V _E and V _D , and h
There was a disadvantage that the value of _m could not be calculated accurately.

On the other hand, in order to prevent this, when V _E, the value of V _D so as to capture operation via a filter, be delayed mass flow thickness detection is controlled with high response A problem arises when you cannot. As described above, the conventional technique has a problem that it is very difficult to obtain a highly accurate plate thickness when the plate speed is low.

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and provides a method and an apparatus for controlling a thickness of a tandem rolling mill capable of maintaining a high-precision thickness in all speed ranges including low-speed rolling. It is an object of the present invention to provide.

[0008]

SUMMARY OF THE INVENTION The object of the present invention is to provide a measurement result from a distance meter for measuring a moving distance of a plate installed on an entrance side and an exit side of each rolling stand of a tandem rolling mill, and a measurement result provided on an entrance side of the rolling stand. The thickness of the exit side of the rolling stand is determined based on the measurement result of the thickness gauge, and the roll speed of the rolling stand disposed on the entrance side of the rolling stand is controlled based on the determined thickness. Can be achieved.

Further, in the above method, a correction amount is determined from the determined sheet thickness of the rolling stand at the delivery side and a measurement result of a thickness gauge installed on the delivery side of the rolling stand, and the correction amount and the height of the rolling stand are determined. The roll speed of the rolling stand positioned on the entry side of the rolling stand is controlled based on the measurement value of the distance meter provided on the entry side and the exit side and the measurement result of the thickness gauge provided on the entry side of the rolling stand. It is preferable to achieve the above object.

Another object of the present invention is to dispose a distance meter for measuring a moving distance of a sheet and a thickness gauge for measuring a sheet thickness on an entrance side and an exit side of each rolling stand of a tandem rolling mill. The exit side thickness of the rolling stand is determined by a predetermined method from the measurement results of the distance meter installed on the side and the exit side and the thickness gauge provided on the entrance side of the rolling stand, and the determined rolling stand of the rolling stand is determined. This can be achieved by generating a roll speed command for the rolling stand based on the exit plate thickness.

In the above structure, preferably, the determined thickness of the delivery side of the rolling stand is corrected by a value measured by a thickness gauge installed on the delivery side of the rolling stand. It is preferable to generate the roll speed command for the rolling stand based on the thickness of the exit side of the rolling stand to achieve the above object.

[0012]

[Effect] The measurement result from the distance meter that measures the moving distance of the plate installed on the entrance side and the exit side of each rolling stand of the tandem rolling mill can take a large value even when rolling is performed at a low speed. Since it is possible to reduce the calculation error when determining the thickness of the exit side of the rolling stand based on this and the measurement result of the thickness gauge provided on the entrance side of the rolling stand, it is possible to reduce the calculation error based on the determined thickness. Thus, by controlling the roll speed of the rolling stand arranged on the entry side of the rolling stand, highly accurate control can be performed.

Further, a distance meter for measuring the moving distance of the sheet and a thickness gauge for measuring the sheet thickness are arranged on the entrance and exit of each rolling stand of the tandem rolling mill, and the entrance and exit of the rolling stand are arranged. Since the measurement result of the distance meter installed on the side can be a large value even when rolling is performed at a low speed, it is determined in advance from this and the measurement result of the thickness gauge provided on the entrance side of the rolling stand. If the exit side thickness of the rolling stand is determined by the method described above, the calculation error can be reduced, and the accuracy is high by generating the roll speed command of the rolling stand based on the determined exit side thickness of the rolling stand. Control can be performed.

[0014]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 shows a sheet thickness control apparatus according to the present invention and a sheet thickness control apparatus applied to a tandem rolling mill.

As shown in FIG. 1, the sheet material 100 is sequentially rolled by each rolling stand via bridle rolls 80, and has a desired thickness at the exit side of the final rolling stand. Each rolling stand is provided with speed command devices 31 to 34 for constantly giving a constant speed command to a motor for driving the rolls, and thickness control devices 90 to 93 for correcting a speed command value sent from the speed command device. Motor control devices 21 to 24 for controlling the electric motor based on the speed command value obtained, distance meters 50 to 54 installed on the entrance and exit sides of the rolling stand, thickness gauges 60 to 63, and distance meters 50 to 54. The rolling distance integrating devices 70 to 74 accumulate the calculated values.

Here, the outline of the second rolling stand 2 will be described as an example of the operation.

The rolling stand 2 adds the speed command value sent from the speed command device 32 and the sheet thickness deviation from the sheet thickness control device 92, and controls the motor 12 by the motor control device 22 based on the added value. Rolling is performed. Here, the thickness deviation as the correction amount of the speed command value is determined by the rolling stand 3 at the next stage. That is, the sheet thickness control device 92 takes in the actually measured values measured by the distance meters 52 and 53 and the thickness gauges 62 and 63 installed on the entrance side and the exit side of the rolling stand 3, and based on the acquired actual measurement values. Thus, the exit side thickness of the rolling stand 3 is determined, and the deviation between the determined exit side thickness and the target thickness is output as a correction amount.

As described above, the electric motor of each rolling stand is controlled by the speed command value and the correction amount. In addition, the electric motor 10 that drives the bridle roller disposed on the entrance side of the first rolling stand is similarly controlled by the speed command value and the correction amount.

Next, a description will be given of a sheet thickness control device arranged in each rolling stand with reference to FIG.

FIG. 2 shows the i-th rolling stand of the tandem rolling mill. Assuming that the tandem rolling mill is constantly rolling, the constant law of mass flow between the rolling mills can be expressed by the following equation.

[0022]

[Number 1] _{h im · V iD = H i} · V iE ... ( number 1) _{Here, H i, h im, V} iE, V iD the thickness at entrance side of the i stand, respectively, out of the side plate thickness, entry side speed , The exit side plate speed. Therefore, the exit side thickness h _im of the i-stand is expressed by the following equation.

[0023]

H _im = (V _iE / V _iD ) · H _i (Equation 2) Further, in the present embodiment, the exit side plate thickness of the i-stand determined by Expression 2 is compared with the actual exit side plate thickness, and correction is made. Do. That is,
H _im of Equation 2 is determined by the following equation.

[0024]

H _im = (V _iE / V _iD ) · H _i · (1 + η _im ) (Equation 3) However, based on Eq.
_When determining _im , there is no problem in the case where rolling is performed at high speed so that the plate speed detected by the speedometer increases, but in the case where rolling is performed at low speed, the entrance and exit plate speeds of the i-stand are determined. Since the values V _iE and V _iD decrease, the calculation error increases.

Therefore, in the present invention, the exit side thickness h _im of the i-stand is determined based on the moving distance of the plate so that a calculation error does not occur even at a low speed rolling. That is,
The exit side thickness h _im is determined based on the following equation.

[0026]

[Number 4] _{h im = (L iE / L} iD) · (V VRi / V VRi-1) · (V Ri / V Ri-1) · H ix _{· (1 + η im) ...} ( Equation 4) where, L _iE, L _iD delivery side and moving distance of the plate in the inlet side of each i stand, V _Ri, V _VRi is i roll peripheral speed as the average value of the stand , V _VRi-1 and V _Ri-1 are i−
It is the roll peripheral speed of one stand and its average value.

As shown in _Expression 4, (L _iE / L _iD ) · (V _VRi
/ V _VRi-1 ) has a long cycle, and has poor response characteristics in performing control. Therefore, in the present invention, the calculation can be performed in the control cycle by (V _Ri / V _Ri-1 ) to improve the response characteristic.

Next, the operation of the sheet thickness control device will be described with reference to FIG.

FIG. 2 shows an i-th rolling stand, which will be described below as an i-stand. As shown in this figure, a distance meter and a thickness gauge are provided on the entrance side and the exit side of the i-stand, respectively. thickness H _x detected by the entrance side of the i stand is adapted to be tracked to just below the i stands rolls.

Distance meter 50 installed on the entrance side of the i-stand
The actually measured value of i is taken into the rolling distance integrating device 70i and integrated. Similarly, the measured values of the distance meter 51i installed on the exit side of the i-stand are sequentially taken into the rolling distance integrating device 71i and integrated.

Here, when the integrated value of the distance meter 50i installed on the entrance side of the i-stand becomes a predetermined value, the exit-side plate thickness _im immediately below the roll of the i-stand is determined. In other words, the roll peripheral speed V _Ri, the roll peripheral speed V _Ri-1 of i-1 stand i stand when the integrated value L _iE rangefinder 50i installed in inlet side becomes a predetermined value, the roll immediately below thickness H _ix, integrated value L _iD distance meter integrated value L _iE of the installed rangefinder is installed in i stand delivery side until the predetermined value in the entry side, i stand being tracked in The average _thickness V _im of the roll peripheral speed of the i-1 stand and the average value V _VRi-1 of the roll peripheral speeds of the i-1 stand determine the exit side plate thickness h _im immediately below the roll.

Next, the adaptive correction value η _im for correcting the difference between the calculated output side plate thickness h _im just below the roll and the actually measured output side plate thickness will be described.

As shown in FIG. 2, the thickness h _im immediately below the roll of the i-stand is determined from the relationship between the front and rear mass flows of the i-stand.
Compared with plate thickness performance value h _ix detected by, for correcting the h _im by the integration value of the deviation is adaptive correction of h _im. Here, since _im is the thickness just below the roll of the stand, when comparing with the actual thickness of the exit side detected by the exit thickness gauge 61i, the _im is tracked from immediately below the roll to the exit thickness gauge. Features are provided.

Then, an adaptive correction value η _im is determined based on the following equation based on the exit side sheet thickness h _im immediately below the roll tracked to the sheet thickness gauge 61i and the sheet thickness h _ix measured by the sheet thickness gauge 61i.

[0035]

(Equation 5)

Further, the thickness h _im immediately below the roll of the adaptively corrected stand is compared with a target thickness h _ref on the exit side of the stand, and the integrated value of the deviation is used as a speed command for the preceding stand (i-1 stand). By adding the term as a speed correction term, the desired thickness can be approached.

As described above, the actual value of the rolling distance is used in place of the sheet speed, and the actual value of the roll peripheral speed is used to prevent a delay in use in control. The speed of the strip during rolling is improved. In addition, since the calculation of the advanced rate ratio does not require a particularly short calculation cycle, the actual rolling distance values on the entrance and exit sides of the rolling stand are integrated until the plate advances a certain distance, and at every certain distance. The rolling distance integrated value during the mass flow calculation is updated. In addition, the acquisition of the actual thickness value of the inlet side and the actual thickness value of the exit side, the mass flow calculation, the thickness tracking operation, and the mass flow adaptive correction operation are performed in a short cycle as before.

In recent years, since a sheet speedometer has recently come to be able to detect the rolling distance, the distance meter of the present invention can be used in place of the sheet speedometer.

[0039]

As described above, according to the present invention,
By integrating the actual rolling distance values detected by the distance meters installed on the entrance and exit sides of the rolling stand and using it for mass flow calculation, the product thickness accuracy can be significantly improved in all speed ranges including low-speed rolling. It is possible to maintain a highly accurate plate thickness regardless of the rolling speed.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a main configuration of a sheet thickness control device in which the present description is applied to a tandem rolling mill.

FIG. 2 is a detailed block diagram of the thickness control device of the present invention.

[Explanation of symbols]

1,2,3,4 ... rolling stand, 10,11,12,1
3, 14 ... Electric motor, 20, 20i, 21, 22, 23,
24 ... motor control device, 30, 30i, 31, 32, 3
3, 34 ... speed command device, 40, 40i, 41, 41
i, 42, 43... adders, 50, 50i, 51, 51
i, 52, 53, 54 ... distance meter, 60, 60i, 61,
61i, 62, 63, 64 ... thickness gauge, 70, 70i, 7
1,71i, 72,73,74 ... rolling distance integrating device, 80
… Bridle roll, 90, 90i, 91, 91i, 9
2, 93: thickness control device, 100: plate material.

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int. Cl. ⁷ , DB name) B21B 37/00-37/78

Claims (4)

(57) [Claims] 1. A measurement result from a distance meter for measuring a moving distance of a plate installed on an entrance side and an exit side of each rolling stand of a tandem rolling mill and a measurement result of a thickness gauge provided on an entrance side of the rolling stand. The thickness of the exit side of the rolling stand is determined based on the thickness of the rolling stand, and the roll speed of the rolling stand arranged on the entrance side of the rolling stand is controlled based on the determined thickness. Thickness control method. 2. The correction amount according to claim 1, wherein an amount of correction is determined from the determined thickness of the exit side of the rolling stand and a measurement result of a thickness gauge installed on the exit side of the rolling stand. Rolls of the rolling stand positioned on the entry side of the rolling stand based on the measurement values of the distance meter provided on the entry side and the exit side of the rolling stand and the measurement results of the thickness gauge provided on the entry side of the rolling stand. A method for controlling a thickness of a tandem rolling mill, comprising controlling a speed. 3. A distance meter for measuring the moving distance of the sheet and a thickness gauge for measuring the sheet thickness are arranged on the entrance side and the exit side of each rolling stand of the tandem rolling mill, and the entrance side and the exit side of the rolling stand are arranged. The exit side thickness of the rolling stand is determined by a predetermined method from the measurement result of the distance meter installed on the side and the thickness gauge provided on the entrance side of the rolling stand, and the determined exit side thickness of the rolling stand is determined. A control device for a tandem rolling mill, comprising: a sheet thickness control device that generates a roll speed command for a rolling stand based on the control. 4. The rolling stand according to claim 3, wherein the determined sheet thickness at the exit side of the rolling stand is corrected by a value measured by a thickness gauge installed at the exit side of the rolling stand. A control device for a tandem rolling mill, further comprising a plate thickness control device that generates a roll speed command for the rolling stand based on the exit side plate thickness of the rolling stand.