SU1128996A1 - Method of automatic control of hot-rolled sheet thickness - Google Patents

Abstract

METHOD OF ADVANCED REGULATION OF TOLTS OF A HOTLEDATED SHEET, which consists of measuring the deviation of sheet thickness in each cell from a given value, comparing it with the threshold value as a function of rolling force, and if the deviation of the sheet thickness exceeds the threshold effect on the pressing device, ich and u so that, in order to increase the productivity of the equipment by reducing downtime due to the change of the damaged parts of the pressure devices, the temperature of the electrical pressure device engines, calculate the change in the dispersion of sheet thickness at the output of each cell and at the output of the mill and the threshold value is calculated by the formula with and. P at and, p - r PI.J, mn R - HD,. . + a (,. dB) i.lHl V. K, J lJi: / iLldrW 2 where Uc,. - set the threshold value for the i-stand. when rolling j-rb sheet; Up is the calculated threshold value for the j i -th stand when rolling the j-ro sheet; Uc. - the minimum value of the threshold of the i-and stand; K, Kj, Kj are the proportionality coefficients determined experimentally by Q mentally for each type in size; oi is the weight coefficient for the i-th stand, defined by the formula ..). where io,% is the initial value of the weight coefficient proportional to the strip elongation beyond the i-th stand; n is the number of cases of overheating; .- - temperature deviation of the electrolyte - (J – Rothvigatel from the th rolling stand (jl) –ro sheet; LI (J-1I deviation value dipler to the thickness of the (j-1) th sheet; when rolling in i- th cage.

Description

The invention relates to the automation of rolling production and can be used on sheet mills for hot rolling.

There is a known method for automatically adjusting the thickness of rolled products, including measurements of the gap between the rollers and rolling force, calculating the thickness of the rolling stock and thickness deviation from a predetermined value in each of the stands, direct measurement of the thickness at the exit of the finishing stand group and the effect on the electric drive of the stand stand 13.

The disadvantage of this method lies in the lower frequency of switching on the electric drives of the pressing devices, which causes accelerated wear of the pressing mechanism and overheating of the electric motors.

There is a method of adjusting the rolling stock, including measuring the deviation of the thickness of the car from a predetermined value, comparing the magnitude of this deviation with the predetermined threshold value and the effect of the stand 23 on the electric drive.

However, the use of this method in the systems of automatic control of the thickness of the car also causes an increased number of actuators of the pressure devices, wear of the pressure mechanisms and overheating of the pressure motors

devices.

The closest to the proposed technical essence and achieves my result is a method of automatically adjusting the thickness of the hot rolled sheet, which consists in measuring the deviation of the sheet thickness from the specified value in each stand, rolling force, comparing the deviation of the sheet thickness from the set value with the set threshold value, changing as a function of the force of the coil, and in the case that the deviation of the sheet thickness is exceeded by a predetermined threshold value, the electric pressure of the pressing device C3i is affected.

A disadvantage of the known method is the change of the trigger threshold without taking into account the temperature of the engines of the pressing devices, which does not allow to reduce the threshold of operation to a permissible value that prevents overheating of the electric motors of the pressing devices.

The purpose of the invention is to increase equipment productivity by reducing downtime due to the change of worn parts of pressure devices.

The goal is achieved by the fact that according to the method of automatic thickness control I conclude in measuring the deviation of sheet thickness in each cell from a given value, comparing it with the threshold value changed in the rolling force function, and in case of exceeding the thickness deviation of the sheet the device additionally measures the temperature of the electric motor of the pressure device, calculates the change in the dispersion of the sheet thickness at the output of each stand and at the output of the mill and set the values on the threshold of the formula

i / .. ..UC. j, j

min

i np "and iU

"Im M min

.,., .and-h 1; ° ... (n, /,. 1M / H "-., dn /

2dT, g

, U1)

dets. - the specified threshold value J for the i-stand when rolling the j-ro sheet;

Up .. is the calculated threshold for the i-stand when rolling the j-th sheet; Up. - the minimum threshold value of the threshold of the i-th stand; proportionality coefficients determined experimentally for each size;

otj is the weight coefficient for the i-th stand, defined by the formula cip (j (l +), where 6L.

the initial value of the weight coefficient is proportional to the extension of the strip beyond the 1st stand; n is the number of cases of overheating of the pressure devices; AT - temperature deviation

4 (j-ll electric motor; -and stands: at rolling. (J-l) -ro sheet;

LZ is the deviation of the dispersion of the thickness of the (j-l) -ro sheet when rolling the i and the cells. In the invention, besides the nominal thickness, the necessary dispersion is set by the thickness of the strip at the exit of the finishing group of the stands. In this case, the specified dispersion can be greater than the maximum achievable at maximum sensitivity of the system. Since excessive accuracy is impractical, the triggering threshold of pressure devices is increased.

each of the stands by an amount proportional to the sum of the deviation of the actual dispersion of the strip thickness in this stand from the specified value and the integral of the deviation of the actual dispersion of the strip thickness at the exit from the finishing group of the stands. In addition, the temperature of all pressure motors is monitored. In the case when the temperature of an electric motor exceeds the permissible value, the component by which the threshold changes, and which is a function of the given and actual thickness dispersions, becomes zero, the threshold threshold increases in proportion to the temperature rise and after each strip, until the temperature of the motor becomes lower than acceptable. If, due to the overheating of the electric motors, one or several stands do not work out thickness variations, the actual dispersion through the strip thickness may exceed the specified value; however, the threshold value in the remaining cells due to the component of the integral of the difference between the target and the actual dispersions across the thickness of the strip at the exit of the finishing group of stands decreases until the difference between the target and the actual dispersions becomes zero.

Fig. 1 schematically shows a thickness control device that implements the proposed method; Fig. 2 illustrates the error in the regulation of the number of inclusions; in FIG. 3, the dependence of the motor temperature on the number of inclusions. The method is carried out as follows. With the help of strain gauge or magnetoelastic (mesdose, pressure conductors) transducers, the rolling force P is measured; in each of the stands of the finishing group, where i is the number of the stand. Using analog, digital, pulse or code converters, the position of the pressure devices of the rolling stands 3 in each of the stands of the finishing group is measured. By comparing with predetermined reductions, the position deviation of the pressure devices LE is determined; and effort rolling U stands finishing gruppn. Using the indirect thickness thickness measurements (the Sa-Golovin C method determines the deviations of THICKNESS strips in each of the finishing groups

LR

L1 .. .5 ,. (2 (

Determine the estimated dispersion B; toll strip at the exit of each of the stands

) / (

where T is the duration of the averaging cycle; t TV

A predetermined thickness dispersion is determined for each of the stands of the finishing group.

B5, .y, A

(four)

where is the specified value of the dispersion of the strip thickness at the exit from the finishing group of n cells;

oi, is the weight coefficient initially set by the proportional-to-band relative elongation of the strip in subsequent cells and refined depending on the temperature mode of the electric motors, for example, according to the law of harmonic series

).

l (.d - the initial value of the

coefficient;

P; - the number of cases of overheating of the engines in the process of rolling one batch of lanes. Determine the deviation of the dispersion D from the given value C, j for each of the stands of the finishing group at the time the strip leaves the stand.

 i JWAi- i

;

The temperature of the electric motor 5 gels T "is measured. The pressure devices with an x-ray or radioisotope thickness gauge measure the thickness of the strip t at the exit of the finishing mill group. The dispersion of the thickness at the exit from the finishing group of the stands is determined at the time of the end of the rolling strip: c "A m l de 1 i3" A is the specified value of the thickness of the ribbon at the exit from the finishing group of lete. determine the deviation of the dispersion of the thickness at the outlet of the finishing group of the Due stands and, from the set value I, using thermocouples or resistance thermometers, or by determining the equivalent core currents, also uniquely determining the heating of the electric motors. Determine the temperature of the electric motor T from the set value Tj Mi ae -se, A Determine the threshold value for each of the pressure devices Ujj for the j-th band, part i (° (ir barking, Up for y ch, L) -1) V. ..; /, ,,, 1 j-1, j-numbers of bands in the party; Ue .. is the calculated value of the threshold of the batting period, with the first page%; s; Ue; . - modal permissible threshold value; Cc-C-coefficient is proportional to the PJ-rolling force in the i-th stand on the front line of the lot. The control actions are generated by the input devices of the electric drive and each of the cages, 1-v where m is the rigidity of the stand. Each time the control action uj is exceeded above: the trigger threshold Ucj, the voltage across the electric motors is pressed so that their movement leads to a decrease in the control signals When the control action Uj decreases to a close to k zero stop the electric motor pressure device. On the first lane, the threshold is neither. When rolling the subsequent strip, the response thresholds are calculated using the formula (10). Assume that during the rolling of the first strip it was determined that the dispersions of the thickness at the exit of this stand and the finishing group of the stands are greater than the specified values, i.e. D, -i i "AoSul" lH. Then, when rolling the second band, the response threshold is less than the value r J "(om o6m-- oSu41 - IF in this case the dispersion exceeds the specified one, then during the rolling of the third band the response threshold is further reduced by the value" A eeuv-B j otflDj A o - osu floe z) and so on until the increment of the trigger threshold becomes. equal to zero, or the engine temperature t. does not reach the maximum limit value T5dd. Lowering the trigger threshold always leads to a decrease in dispersion across the strip thickness. On the other hand, this leads to an increase in the frequency of switching on the drive, i.e. to an increase in engine temperature. Suppose that when the third strip is rolled, the pressure device engine is overheated, i.e. L. (A. Then, when the fourth strip is rolled, the response threshold rises by.) -) If, in this case too, the engine temperature exceeds the specified value, then during rolling the next, fifth band, the threshold is still increased by the value (j I and so on until the engine temperature becomes equal to the set value. With a further decrease in the engine temperature, the threshold triggering takes effect to the thickness dispersions. In order to reduce engine overheating, the weighting factor cl-i increases according to the law (5). After rolling several lanes, the weighting coefficients (o) are automatically redistributed, which ensures a given dispersion at the output of the finishing groups of stands. Thus, the use of auto-tuning of the threshold of actuation of the drive of the pressing device according to the procedure laid down in the basis of the proposed method leads to the stabilization of the longitudinal thickness of the strip with a given level of dispersion This, at the exit of the finishing group of the stands, with the underutilized total heat load of the engines involved in the pressure devices, eliminates the deficiencies inherent in the prototype. . The device, which is the first kitsay method, includes rolling force transducers 1 connected to the first inputs of the first comparison elements 2, the second inputs of which are connected to unit 3 of the rolling forces; transducers 4 of the position of the pressure devices 5, acting through the rolls 6 on the strip 7c with the actuators 8, the inputs of which are connected to the outputs of the relay elements 9c of the adjustable deadband; the second comparison elements 10, the first inputs of which are connected to the transducers, the second inputs are connected to the setting devices 11, and the outputs are connected to the second inputs of the control signal generating units 12, the first inputs of which are connected to the rolling force transducers and the second inputs of the blocks 13 determine the dispersion and its deviations, the first inputs of which are also connected to rolling force transducers, the third inputs are connected to the spreader 14 thickness dispersions at the rolling mill outputs and the outputs are connected with the first inputs of the block 15 about / 1 determining the threshold value, the second inputs of which are connected to temperature transducers 16 of the electric drive motors, the third inputs; (s are connected to the minimum 17 threshold values of the response threshold, the fifth inputs are connected to the output of the detection unit 18 dispersion in thickness at the outlet of the mill, the first input of which is connected to the gauge 19 of the thickness at the exit of the finishing group of stands, the second input is connected to the unit 20 of thickness at the exit of the finishing group of stands, the third input is connected to the rear Atch1} com 21 dispersions in thickness at the exit of the finishing mill group. The outputs of the control signal generation units 12 are connected to the first inputs of relay elements 9 with adjustable deadband, and the outputs of the operation threshold determination units 15 are connected to the second inputs of these elements. The device works as follows. From the output of the rolling force transducers 1 and the 4 position transducers, signals corresponding to the current values of the monitored rolling parameters are transmitted to the corresponding inputs of the comparison elements 2 and 10, where they are compared with the specified values 3 and 11. The output signal of the force deviation from the output value element 2 comparison, is fed to the first inputs of blocks 12 and 13, and the signal of deviation of the position from the specified value, taken from the output of element 10 of the comparison, is fed to the second inputs of blocks 12 and 13. At the output of block 1 2, a control signal is generated and, calculated by the formula (11). At the output of block 13, a signal is generated for deviating the thickness dispersion from the setpoint determined by formula (b). The control signal I /, from the output of the block 12 is fed to the input of the relay element 9 with an adjustable response zone. If this signal exceeds the threshold value, the relay element is triggered and a signal and appears at its output. equal to the control signal. This signal is fed to the input of the actuator 8 and sets it in motion so that the movement is on. clamping device 5 was accompanied by a decrease in the control signal U | . When the magnitude of this signal decreases to near zero, the relay element 9 returns to its initial state, the control signal becomes zero, the drive 8 stops-; c and remains until the magnitude of the control signal due to a change in the rolling force increases again to the trigger threshold. With the appearance of the strip at the exit of the finishing group of stands, the signal of the strip thickness meter 19 at the mill outlet is fed to the first input of the dispersion deflection decay unit 18 in thickness at the mill output. The variance deviation is determined by the formula (8). Dispersion deviation signals, received at the output of blocks 13 and 18 by the end of the rolling of the current strip, go to the first and fifth inputs of the block 15 for determining the threshold value. The second input of the nocTsmaeT signal of the motor temperature in the pause after the current strip leaves the cage, the third input receives a signal of rolling force on the head of the first artery band only at the moment the first strip enters the cage, the fourth input receives the minimum threshold value. On the head of the next strip at the output of the block 15, the threshold value of the response is calculated, calculated by the formula (10). When using the base method, the total number of inclusions of the electric pressure device of the whole PURE group is 2x1500 Rstr on the strip, while the regulation error is 0.015 mm. IF, according to the conditions of Delivery, set the prescribed accuracy of regulation of Scha.ksh, R, 025 mm (which meets the requirements of most customers and the accuracy level achieved in world practice), then the number of inclusions (as shown by calculations and figure 2) can be reduced in according to the proposed method to 2. 80. In many cases, even lower accuracy is required, and the number of inclusions can be reduced by a factor of 3-5. When rolling one strip in a basic way, approximately 10-20 kWh of electricity is used to control the pressing devices. Thus, energy savings per lane is at least 5 kWh. Since approximately 100,000 bands are rolled throughout the year, the total energy savings over the period indicated is approximately 500,000 kWh. At the same time, the wear rate of the mechanical equipment is reduced by no less than two times.

MttnpaBneHue

t POteSfftKU

t200

total i uvecmSo & fflH wi / s / tetfmponffasfmS are pressed) (ycmfot} c / ff6 vifcmo i / grl / ppi cages on one lane

Pui.2

Claims (1)

METHOD FOR AUTOMATIC REGULATION OF THE THICKNESS OF THE HOT-ROLLED SHEET, which consists in measuring the deviation of the sheet thickness in each cell from the specified value, comparing it with the threshold value, which is changed as a function of the rolling force, and if the deviation of the sheet thickness exceeds the threshold value of the action on the pressure device, In this case, in order to increase equipment productivity by reducing downtime due to the change of worn parts of pressure devices, the temperature of the electric motor is additionally measured pressure device, calculate the change in the variance of the sheet thickness at the output of each cell and at the exit of the mill and the threshold value is set by the formula [U. and _c = 7 at 1 / p> and M * min 'min' where U _c j · is the set threshold value for the i-th stand. when rolling the j-ro sheet; Up., Is the calculated threshold value for g ^{1.1 of the} i.th stand when rolling the j-ro® sheet; U _c . -minimum permissible value _{on the} threshold of the клетth stand; ^to h ^{| k} 2 ^'to 5 ^_ proportsioanalnosti coefficients determined experimentally _for each type-mentally in size; -weighing coefficient for the ί-th 'stand, determined by the formula'! 4Ч <ттм. ··· 'where is the initial value of the weight coefficient proportional to the elongation of the strip beyond the ϊ -th stand; n, the number of cases of M overheating; . 4T - temperature deviation of the electric motor from the <-th stand for rolling (j-l) -ro sheet; . (ι-it ^"led Jicin Deviations dysper ^'g these thickness (J-1) th sheet / the rolling in ΐ-th stand. 1 :