RU1827304C - Device for automatic regulation of strip thickness in continuous cold rolling mill - Google Patents

Abstract

Usage: control of strip thickness on rolling mills Summary of the invention: compensation of errors in calculating the mill pre-setting parameters by correcting roll stand speed tasks from the results of estimating the average deviation of the strip thickness from a predetermined value at the mill exit. 1 ill.

Description

The invention relates to automation of rolling production, and in particular to systems for automatically controlling the thickness of a strip, mainly on five- or six-gauge cold rolling mills.

The purpose of the invention is to improve the accuracy of cold rolled strips by compensating for deviations of strip thickness from a predetermined one.

At the suggestion of the authors, the average value of the deviations of the strip thickness from a predetermined value at the mill exit is estimated and an additional correction of the stand speed settings of the stands is carried out based on the evaluation result. Thus, the inventive device allows for the correction of the presetting of the mill not only depending on the thickness of the strips entering the cold rolling mill, but also on the thickness of the strip obtained at the outlet of the mill.

The drawing shows a structural diagram of the proposed device.

The circuit includes a meter 1 deviation of the strip thickness from a predetermined value, installed behind the last stand, a meter 2 deviation of the thickness of a strip from a predetermined value, installed in front of the first stand, a mill presetting system 3, adjusters 4 of the position of the press mechanisms of the stands, adjusters 5 of the drive speed motors for stand stands, a system 6 for controlling the mill speed modes, a strip thickness regulator connected in series, and a first 8 adder, the output of which is connected to the first input of the system 6 systematic way modes mill speed, the filter unit 9 is higher frequencies, the filter unit 10. low frequencies, first 11, second 12 and third 13 variable delay units, second 14, third 15 and fourth 16 adders; a fourth 17 adjustable delay unit and a fifth 18 adder connected in series; tasks 19 for meters 1 and 2 deviations of the strip thickness, tasks 20 for regulators 4 of the position of the pressure mechanisms

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stands and job 21 for mill speed control system 6; in addition, the sixth 22, seventh 23 and eighth 24 adders, the first 25, the second 26 and the third 27 are roll speed setting correction units, a dead zone unit 28 and an average deviation estimating unit 29.

The device operates as follows. The system 3 of presetting the mill for a given value of the thickness of the strip at the exit of the mill and a given value of the thickness of the strip at the inlet of the mill generates tasks 19, 20 and 21 for meters 1 and 2 of the deviation of the strip thickness, the regulators 4 of the position of the press mechanisms of the stands and the system b control of mill speed modes.

The mill speed control system 6 allows coordinated acceleration of the drive motors D of the stand rolls to the rolling speed operating value Vp, as well as coordinated braking from the operating value Vp to zero speed.

If there is a change in the thickness of the strip entering the cold rolling mill, the output signal of the meter 2 will be different from zero. The output signal of the meter 2 is fed to the input of the filter blocks 9 and 10. Block 9 emits high-frequency oscillations (for example, F Ј 1 Hz). The signal allocated by block 9 by the adjustable delay unit 17 is delayed by the time the strip is transported from the meter 2 to the yaw of the rolls the first stand minus the inverse delay in the position adjuster 4 of the stand press mechanism. Under the action of the output signal of block 17, the position of the pressing mechanism of the first stand changes and the high-frequency vibrations of the thickness of the rolled strip are compensated in the rolls of this stand.

Block 10 extracts the low-frequency (for example, f 0.1 Hz) component of the output signal of meter 2. Block 11 of the adjustable delay delays the selected signal for the duration of the transportation of the strip from meter 2 to the throat of the rolls of the second stand minus the inertial delay of the speed controller 5 neither the drive motor of the roll stands, Block 12 further delays this signal during the transportation of the strip from the rolls of the second stand to the rolls of the third stand, and the block 13 - during the transportation from the rolls of the third to the rolls of the fourth to hildren.

Under the action of the output signal of block 11, the speed of the rolls will change

the stand, under the influence of the output signal of the block 12 - the speed of the rolls of the first and second, and under the action of the output signal of the block 13 - the speed of the rolls of the first, second and third stands of the mill. The transfer coefficient Ki of the adders 14, 15 and 16 at the inputs intended for the output signals of blocks 11,12 and 13 is selected to be equal to 1/3 of the value of the coefficient Kz of the adders for the inputs intended for the signals of the speed settings of the rolls. As a result, the amplitude of the deviations in the thickness of the low-frequency band strip first decreases in the rolls of the second stand, then in the rolls of the third stand, and finally these deviations are compensated in the rolls of the fourth stand.

The thickness controller 7 accounts for the compensation of deviations in the thickness of the mid-frequency band (e.g. 0.1 Hz f 1 Hz) range.

The compensation of deviations in the thickness of the strip of this frequency range is carried out in the rolls of the last stand by affecting the speed of the rolls of this stand.

The mean deviation estimating unit 29, the dead band unit 28, the roll speed setting correction units 25, 26 and 27 and the adders 22, 23 and 24 are used for additional correction of the mill setting, which is carried out as follows.

The output signal of the meter 1 deviation of the strip thickness from a predetermined value at the output of the mill is fed to the input of block 29 estimates the average value of the deviations. Block 29 averages the thickness deviations over a strip length of, for example, 20 m.

As long as the average value of the deviations of the strip thickness at the exit of the mill does not exceed the value set by the dead zone of block 28, roll speed correction does not occur.

If the output signal of block 29 exceeds the deadband of block 28, then the output signals of blocks 25, 26 and 27 will begin to change. Block 25 is an integrator, blocks 26 and 27 have a proportional characteristic. Under the action of the output signal of block 26, an additional change in the speed of the rolls of the first stand takes place, under the action of the output signal of the block 27, the speed of the rolls of the first and second, and under the action of the output signal of the block 25, the speed of the rolls of the first, second and third stands of the mill. Moreover, the transfer coefficient K3 of the adders 22, 23 and 24 at the inputs intended for the output signals of blocks 25,26 and 27 is selected to be equal to 1/3 of the value of the coefficient K4 of these adders for the inputs intended for the signals of the speed settings of the rolls. Due to this, the strip thickness will partially change in the rolls of the second, in the rolls of the third stand and in the rolls of the fourth stand, and the complete change in the strip thickness required to adjust the mill setting will be obtained by the combined action of the output signals of blocks 25, 26 and 27.

The average value of the deviations of the strip thickness from the set value at the output of the mill can be estimated indirectly by the output signal of the strip thickness controller 7. An embodiment of the device using an indirect estimate of the average deviation of the strip thickness comprises a connection (not shown) of the output of the strip thickness controller 7 with the input of the dead band unit 28.

Thus, the device proposed by the authors for automatically adjusting the strip thickness in a continuous cold rolling mill makes it possible to compensate for deviations of the strip thickness from the predetermined one, due to both significant variations in the thickness of the strips entering the cold rolling mill and errors in the mill presetting while having a minimal effect on a given technological mode in each separately taken stand.

The effectiveness of the proposed device is to increase the accuracy of cold-rolled strips and thereby increase the yield of rolled products.

Claims (1)

The claims Device for automatically adjusting the thickness of a strip in a continuous cold rolling mill No. 1775199, characterized in that, in order to increase the accuracy of cold rolled strips by compensating for deviations of the strip thickness from the predetermined one, it is equipped with three adders, three roll speed reference correction units; blocks of the dead zone and estimates the average deviation, the input of which is connected to the input of the thickness controller, and the output through sequentially the dead band unit and the first roll speed reference correction unit are connected to the inputs of the second and third. roll speed reference correction units and to the inputs of the sixth, seventh and eighth adders, the outputs of the second and third roll speed setting correction units are connected to the inputs of the sixth and seventh adders, respectively, the corresponding inputs of the sixth, seventh and eighth adders are connected to the corresponding outputs of the mill presetting system, and the outputs to the inputs of the second, third and fourth adders respectively. th ©