JPH0957317A - Method and device for controlling plate thickness of tandem rolling mill - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a plate thickness controller for a tandem rolling mill whose plate speed accuracy in a whole speed area including that at the time of low speed rolling is improved. SOLUTION: By using the integrated value of rolling distance actual results detected by range finders 50 to 54 installed on the outlet side and the inlet side of each stand of a tandem rolling mill and on the outlet side of bridle rolls and plate thickness actual result values detected by plate thickness meters 60 to 64, a mass flow operation is performed. A plate thickness actual result value just under the roll of a stand, which has been found by the operation, and the deviation in a target plate thickness, are set as the speed correction quantities of each stand. And, they are added to the speed command values of each stand, which are the outputs of speed command devices 30 to 34, are sent to motor controllers 20 to 24, and make motors 10 to 14 revolve.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a plate thickness control method and apparatus for 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 plate produced in a tandem rolling mill depends on whether a desired plate thickness can be obtained. Then, various control methods have been proposed in order to obtain a desired plate thickness.

Among them, in the tandem rolling mill, there is a plate thickness control method utilizing a constant law of mass flow. The constant mass flow law is given by the following equation: H · V _E = h · V _D (H: rolling mill entrance side plate thickness, V _E : rolling mill entrance side plate thickness, h: rolling mill exit side plate thickness, V _D : rolling machine Outlet speed) From the actual values of the plate thickness and plate speed detected by the plate speed meter and the plate thickness gauge provided on the exit side and the entrance side of the rolling mill, respectively, the plate thickness h _m immediately below the roll is h _m = V _E / V _D · H _X. Assuming that the target plate thickness on the stand exit side is h _ref , an integrated value Σ (h _ref −h _m of the deviation between the plate thickness h _m immediately below the roll of the stand and the target plate thickness h _ref on the stand exit side. )
Can be obtained as a speed correction amount by adding to the speed command of the stand in the preceding stage to obtain a desired plate thickness. In this way, from the plate speed actual value before and after the rolling mill and the plate thickness actual value on the inlet side of the rolling mill, calculate the plate thickness immediately below and on the roll side of the rolling mill using the mass flow formula, and calculate this plate thickness in advance. The conventional mass flow plate thickness control device adjusts the speed of the rolling mill in the preceding stage of this rolling mill so as to reduce the deviation from the target plate thickness obtained from the rolling schedule.

Regarding the above-mentioned conventional technique, "Theory and practice of sheet rolling" (edited by Japan Iron and Steel Institute), page 301, JP-A-4-52016
No., published in Japanese Unexamined Patent Publication No.

[0005]

However, as described in the prior art, it is extremely difficult to detect the plate speed on the input side and the plate speed on the output side and calculate V _E / V _D based on the detected values. The accuracy was poor. That is, since V _E and V _D each have a small value during low-speed operation, the value of V _E / V _D greatly changes even with a slight change in V _E and V _D , and h
There is a drawback that the value of _m cannot be calculated accurately.

On the other hand, in order to prevent this, when the values of V _E and V _D are fetched and calculated through a filter, the detection of the mass flow plate thickness is delayed, and the control can be made highly responsive. There is a problem that cannot be done. 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.

The present invention has been made in view of the above problems, and provides a plate thickness control method and device for a tandem rolling mill capable of maintaining a highly accurate plate thickness in the entire speed range including low speed rolling. It is an object of the invention to provide.

[0008]

[Means for Solving the Problems] The above object is to provide a measurement result from a range finder for measuring the moving distance of a plate installed on the entrance side and the exit side of each rolling stand of a tandem rolling mill and the entrance side of the rolling stand. By determining the strip thickness on the delivery side of the rolling stand based on the measurement result of the strip thickness gauge, and controlling the roll speed of the rolling stand arranged on the entry side of the rolling stand based on the determined strip thickness. Can be achieved.

Further, in the above method, a correction amount is determined from the determined output side plate thickness of the rolling stand and a measurement result of a plate thickness gauge installed on the output side of the rolling stand, and the correction amount and the rolling stand The roll speed of the rolling stand located on the inlet side of the rolling stand is controlled based on the measurement value of the distance meter provided on the inlet side and the outlet side and the measurement result of the plate thickness gauge provided on the inlet side of the rolling stand. It is preferable to achieve the above object.

Further, the above object is to arrange a distance meter for measuring the moving distance of the plate and a plate thickness meter for measuring the plate thickness on the inlet side and the outlet side of each rolling stand of the tandem rolling mill, and to install the rolling stand on the rolling stand. Side and exit side thickness of the rolling stand is determined by a predetermined method from the measurement results of the distance gauge installed on the exit side and the strip thickness gauge provided on the entrance side of the rolling stand, and the determined rolling stand It can be achieved by generating a roll speed command for the rolling stand based on the exit strip thickness.

Further, in the above configuration, preferably, the determined outgoing side plate thickness of the rolling stand is corrected by a value measured by a plate thickness gauge installed on the outgoing side of the rolling stand, and the corrected above-mentioned It is preferable to generate the roll speed command of the rolling stand based on the exit side plate thickness of the rolling stand to achieve the above object.

[0012]

[Operation] The measurement result from the range finder for measuring 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 at a low speed. Since it is possible to reduce the calculation error when determining the strip thickness on the outlet side of the rolling stand based on this and the measurement result of the strip thickness gauge provided on the inlet side of the rolling stand, it is possible to reduce the calculation error based on the determined strip thickness. By controlling the roll speed of the rolling stand arranged on the entrance side of the rolling stand, highly precise control can be performed.

Further, a distance meter for measuring the moving distance of the plate and a plate thickness meter for measuring the plate thickness are arranged at 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. Since the measurement result of the distance meter installed on the side can be a large value even when rolling at low speed, it is determined in advance from this and the measurement result of the plate thickness gauge installed on the entrance side of the rolling stand. The calculation error can be reduced by determining the exit side plate thickness of the rolling stand by the above method, and the accuracy is high by generating the roll speed command of the rolling stand based on the determined exit side plate 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 strip thickness control device according to the present invention and the strip thickness control device applied to a tandem rolling mill.

As shown in FIG. 1, the plate material 100 is sequentially rolled by each rolling stand through a bridle roll 80 and has a desired plate thickness on the exit side of the final rolling stand. Each rolling stand is provided with speed command devices 31 to 34 that constantly give a constant speed command to an electric motor that drives a roll, and plate thickness controllers 90 to 93 that modify the speed command value sent from the speed command device. Measured by the electric motor control devices 21 to 24 that control the electric motor based on the speed command value, the distance meters 50 to 54, the plate thickness gauges 60 to 63, and the distance meters 50 to 54 installed on the entrance side and the exit side of the rolling stand. The rolling distance accumulating devices 70 to 74 accumulate the calculated values.

Here, an 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 plate thickness deviation from the plate thickness control device 92, and controls the electric motor 12 by the electric motor control device 22 based on the added value. Then, rolling is performed. Here, the strip thickness deviation as the correction amount of the speed command value is determined by the rolling stand 3 in the next stage. That is, the strip thickness control device 92 takes in the actual measurement values measured by the distance meters 52, 53 and the strip thickness meters 62, 63 installed on the inlet side and the outlet side of the rolling stand 3, and based on the captured actual measurement values. The output side plate thickness of the rolling stand 3 is obtained, and the deviation between the obtained output side plate thickness and the target plate thickness is output as a correction amount.

Thus, the electric motor of each rolling stand is controlled by the speed command value and the correction amount. Further, the electric motor 10 driving the bridle roller arranged on the entrance side of the first rolling stand is also controlled by the speed command value and the correction amount.

Next, the plate thickness control device arranged in each rolling stand will be described with reference to FIG.

FIG. 2 shows the i-th rolling stand of the tandem rolling mill. Assuming that the tandem rolling mill is rolling steadily, 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 ， It is the output plate speed. Therefore, the output side plate thickness h _im of the i stand is as follows.

[0023]

[Number 2] h _im = In _{(V iE / V iD) ·} H i ... ( Equation 2) Further, the present embodiment, the actual delivery side thickness compared to modify the delivery side thickness of the i stand determined by the number 2 To do. That is,
The h _im of the equation 2 is determined by the following equation.

[0024]

[ _Equation 3] h _im = (V _iE / V _iD ) · H _i · (1 + η _im ) ... (Equation 3)
_{When im} is determined, there is no problem when rolling is performed at high speed so that the strip speed detected by the speedometer becomes large, but when rolling at low speed, the i-stand's inlet side and outlet side plate speeds are Since the values V _iE and V _iD are small, the calculation error is large.

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

[0026]

## _EQU00004 ## h _im = (L _iE / L _iD ). (V _VRi / V _VRi-1 ). (V _Ri / V _Ri-1 ) _{.H ix} (1 + η _im ) ( _Equation 4) Here, L _iE and L _iD are the moving distances of the plate material on the exit side and the entrance side of the i stand, respectively, and V _Ri and V _VRi are the roll peripheral speeds of the i stand and their average values. , V _VRi-1 and V _Ri-1 are i-
It is the roll peripheral velocity of one stand and its average value.

As shown in _Equation 4, (L _iE / L _iD ) · (V _VRi
/ V _VRi-1 ) is due to a long cycle, and the response characteristic is poor in controlling. Therefore, in the present invention, the response characteristic is further improved by making it possible to calculate in the control period by (V _Ri / V _Ri-1 ).

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

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

Distance meter 50 installed on the entrance side of the i stand
The measured value of i is successively taken into the rolling distance integration device 70i and integrated. Similarly, the actual measurement value of the distance meter 51i installed on the exit side of the i stand is sequentially taken in by the rolling distance integration device 71i and integrated.

Here, when the integrated value of the distance meter 50i installed on the entrance side of the i stand reaches a predetermined value, the exit side plate thickness h _im just 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 I-stand until the plate thickness H _ix that is tracked on the side and the integrated value L _iE of the range finder installed on the entrance side reach a predetermined value. The integrated value L _iD of the range finder installed on the exit side, i stand The average value V _VRi of the roll peripheral speed and the average value V _VRi-1 of the roll peripheral speed of the i-1 stand determine the _delivery side plate thickness h _im immediately below the roll.

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

As shown in FIG. 2, the plate thickness h _im immediately below the roll of the i stand is obtained from the relationship between the front and rear mass flows of the i stand.
The adaptive correction of h _im is to compare h _im with the actual thickness value h _ix detected by and to correct h _im with the integrated value of the deviation. Here, since h _im is the plate thickness just below the roll of the stand, when comparing with the actual output side plate thickness value detected by the output side plate thickness meter 61i, h _im is tracked from immediately below the roll to the output side plate thickness meter. It has a function.

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

[0035]

(Equation 5)

Further, the plate thickness h _im just below the roll of the adaptively corrected stand is compared with the target plate thickness h _ref on the stand outlet side, and the integrated value of the deviation is compared with the speed command of the preceding stand (i-1 stand). By adding as a speed correction term to, it is possible to approach the desired plate thickness.

As described above, the actual rolling distance value is used instead of the strip speed, and the actual roll peripheral speed value is used in order to prevent a delay in use for control, thereby eliminating the calculation error of this term and reducing the low speed. Improves plate speed accuracy during rolling. In addition, since the calculation of the advanced ratio does not require a particularly short calculation cycle, the actual rolling distance values on the entrance side and exit side of the rolling stand are integrated until the plate advances by a certain distance, and at every constant distance. In addition, the rolling distance integrated value during mass flow calculation is updated. Further, the input side actual thickness value and the output side actual thickness value are fetched, and the mass flow calculation, the thickness tracking calculation, and the mass flow thickness adaptive correction calculation are performed in a short cycle as before.

Further, recently, a strip speed meter has come to be able to detect the rolling distance, and thus the strip speed meter of the present invention can be substituted.

[0039]

As described above, according to the present invention,
By using the mass flow calculation by accumulating the actual values of rolling distances detected by distance meters installed on the inlet side and the outlet side of the rolling stand, it is possible to significantly improve the product thickness accuracy in the entire speed range including low speed rolling. It is improved, and it becomes possible to always maintain a highly accurate strip thickness regardless of the rolling speed.

[Brief description of drawings]

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

FIG. 2 is a detailed block diagram of the plate 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 ... Adder, 50, 50i, 51, 51
i, 52, 53, 54 ... Distance meter, 60, 60i, 61,
61i, 62, 63, 64 ... Plate thickness gauge, 70, 70i, 7
1,71i, 72, 73, 74 ... Rolling distance integrating device, 80
… Bridle rolls, 90, 90i, 91, 91i, 9
2, 93 ... Plate thickness control device, 100 ... Plate material.

Claims (4)

[Claims] 1. A measurement result from a range finder for measuring a moving distance of a plate installed at an entrance side and an exit side of each rolling stand of a tandem rolling mill and a measurement result of a plate thickness gauge provided at an entrance side of the rolling stand. A plate for a tandem rolling mill, characterized in that the plate thickness on the exit side of the rolling stand is determined based on the plate thickness, and the roll speed of the rolling stand arranged on the entrance side of the rolling stand is controlled based on the determined plate thickness. Thickness control method. 2. The correction amount according to claim 1, wherein a correction amount is determined based on the determined output side plate thickness of the rolling stand and a measurement result of a plate thickness gauge installed on the output side of the rolling stand. Roll of the rolling stand located on the inlet side of the rolling stand based on the measurement value of the distance meter provided on the inlet side and the outlet side of the rolling stand and the measurement result of the plate thickness gauge provided on the inlet side of the rolling stand. A plate thickness control method for a tandem rolling mill, characterized by controlling the speed. 3. A distance meter for measuring the moving distance of the plate and a plate thickness meter for measuring the plate 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. Determining the exit side plate thickness of the rolling stand by a predetermined method from the measurement result of the distance meter installed on the side and the plate thickness gauge provided on the entrance side of the rolling stand, and the determined exit side plate thickness of the rolling stand. A controller for a tandem rolling mill, comprising a plate thickness controller that generates a roll speed command for a rolling stand based on the above. 4. The exit side plate thickness of the rolling stand according to claim 3, is corrected by a value measured by a plate thickness gauge installed on the exit side of the rolling stand, and is corrected. A controller for a tandem rolling mill, comprising: a plate thickness controller that generates a roll speed command for the rolling stand based on the exit side plate thickness of the rolling stand.