SU659220A1 - Rolling mill braking automatic control - Google Patents

Description

The thickness of the strip is determined by the difference in lengths n in series of coils wound up from the unwinder according to the formula h where n is the number of wound coils; li, In - the length of the first and ln-wound coils. The thickness of the strip found by formula (3) long before the start of deceleration is assumed to be a constant in subsequent calculations. In this case, the longitudinal thickness variation, which is especially sharply manifested by the caudal thickening of the strip, i.e., in the braking section, is not taken into account. Therefore, re-calculating the remainder of the strip during deceleration at a constant value of the strip thickness, as is customary in the specified prototype, while the strip thickness actually increases, leads to an increase in the calculation error towards an increase in the length of the strip remainder. In addition, the length of the remainder of the strip on the decoiler, calculated by formula (1), is overestimated by the length of the last rolled up coil, since the value of Ri in the formula can be found only after winding a coil of length k. Repeated calculations of the length of the remainder of the strip with the determination of the thickness after rolling up the turns of the washer (usually 8-10-10 turns) exclude the possibility of tracking the length of the remainder of the strip during braking and promptly making corrections to the deceleration rate, since the length of the turns may turn out to be commensurate with the length of the track braking. The need for rolls is caused by the desire to reduce the error in calculating the strip thickness, which arises due to the low resolution of the length sensor of the strip entering the mill, which is used to measure the length of coiled windings. Calculations show that an acceptable calculation accuracy after each coiled coil is provided if the coil length is measured to the nearest hundredths of a millimeter. The use of high-precision sensors is hampered by a number of technical difficulties, for example, due to the need to dock a precision instrument with a coarse mechanism, such as a mill bending wheel, and the requirements for ensuring the necessary reliability. The indicated computation errors, leading to an overestimation of the lengths of the remainder of the strip on the decoiler versus the actual remainder, can cause an emergency situation in the mill with equipment damage and long periods of time. The aim of the invention is to improve the accuracy of calculating the length of the remainder of the strip and to improve the quality of braking control of the rolling mill. This goal is achieved by the fact that the proposed device calculates the length of the coiled windings and the remainder of the strip on the uncoiler with high accuracy without taking into account the length of the coiled for calculating turns and re-calculates the remainder of the strip after winding from the decoiler of each coil. In this case, the length of the coiled windings is measured with an accuracy of hundredths and more of the resolution of the length sensor of the incoming strip in the mill using auxiliary standard high-frequency pulses. Improved control quality is achieved by re-calculating the remainder of the band, the braking process is corrected, i.e., the process is monitored, and also shortly before the end of the deceleration, the deactivator corrects the braking mode but the actual length of the remainder of the band. The length of the entire remaining strip on the mill inlet in the proposed device is found by the expression + L6, (4) where LG is the known length of the strip that is between the unwinder and the rolled to-aunt; LP is the estimated length of the remainder of the strip on the drum of the uncoiler. The latter is calculated from the representation that the unwinder mounted on the reel is a spiral of Archimedes. The lengths of the turns in the helix differ from each other by a strictly defined value, i.e. they form an arithmetic progression for which the sum length i of the first turns of the rabb f li + li .. L, i -, - i. 2 where / 1 is the known length of the first (inner) coil of the roll on the drum of the unwinder; / g - the length of the i-ro (last) turn of the spiral. From the formula for any member of the arithmetic progression / J / 1 + c (t-) jd Ink - the difference in the lengths of the two neighbors, turns; h is the thickness of the strip / is an expression for the number of turns in the helix, having the form The thickness of the stripe h, expressed in terms of two adjacent turns, is ii-li-i de / g -1 - the length of the penultimate turn of the helix. Substituting (7) and (6) to equation (5) gives an expression of the length of the strip located on the unwinding roll li) (fi + fi} I li + li 2 (// - /,) From equation (St it is clear that The length of a strip in a roll can be calculated if the lengths of two (t-ro and d-1) turns are known. Therefore, the calculated length of the remainder of the nose on the unwinder drum, calculated after winding and measuring the lengths of these turns, will be + And - (( /, + // - 1). (9) (li-li) (fi + li) 2 (f / - /, i) In formula (9), in contrast to equality (1), only the lengths of the winding windings are involved, which simplifies computations. Accuracy is inferred by the fact that The wound coils of /, - and /;.-t are subtracted. Fig. 1 shows a functional diagram of the proposed device, and Fig. 2 shows a diagram explaining the principle of measuring the length of coils with high accuracy using auxiliary standard high frequency pulses. The PULSES, shown in the diagram, are output by the sensor of the angular velocity of the unwinder at each revolution of the latter. The intervals between them correspond to the length of one reeled up coil. Pulses K. having a known discreteness are output by a length sensor of the strip entering the mill. The diagram also shows the standard pulses f, which follow with a constant frequency. An increase in the accuracy of measuring the length of the winding turns (for example, length I, -) is achieved by the fact that the length of the turn is represented as the sum of the individual segments l..a, + Ai + -b, (10) i.e., the intervals between impulses / C, as well as between g n K, which form the fractions of the discreteness of the PULSES K. Segment A: is determined by the number of integer intervals between the pulses K, the number of which per unit is less than the number of PULS K A ./- Ü, where t is the number pulses K in the interval between pulses and /: / - 1, 2,. .., t; g is the resolution of the length sensor, millimeter per pulse. The segment a: in the fraction of the length sensor’s resolution is 0-1. Where rti.o is the number of standard pulses in the interval between the pulses r-Ы and / С, -,), / г, -, 1 is the number of standard pulses between adjacent ones impulses Ki, and / Cr, 2Slot 5, - represents in the form b, gl-fl, -, (13) where n ,,, о is the number of standard impulses enclosed between impulses i and / Cj-ii; n, -., | - the number of standard impulses enclosed between pulses / Cr s and Ki-, Z. Expression (10), in view of (11), (12) and (13), is reduced to the form V A-L- .g, A /, U + I-I. Expression (14) is obtained from the assumption that the length intervals between adjacent the pulses K from the length sensor are rather small, and that during the course of two adjacent pulses K, the rolling speed remains almost unchanged. From consideration of FIG. 1 and formulas (14), that the measurement of the length of the turns is carried out by the same type calculations of the segments Ai,, .... as well as the calculations of the segments, - immediately following the signals i from the ANGLE speed sensor of the unwinder. Moreover, the sign of the segments a, -. a, alternately changes to an obatny, for example, segment o, - (when calculating /, has a negative sign, and following the calculation of the length /, is positive. The actual length of the non-rolled strip used in the device for addition, correction after the end of braking is determined at the time of the tail of the strip from the unwinder, which is fixed by the disappearance of tension. The length of the strip at this moment is determined by the length of the strip from the mill rolls to the axis of the unwinder and the length of the first (internal) coil on the drum Experience shows that the error in measuring the length in this way does not exceed 20 cm. The proposed device for automatic control of rolling mill braking includes a sensor 1 for the length of the H1 input to the strip mill, a generator of 2 standard pulses, a sensor 3 for the angular velocity of the unwinder, a block 4 of standard PULSE counters , block 5 - calculating up to,; 1and discreteness of the length sensor of the strip entering the mill, block 6 calculating the length-integer discretes of the sensor of the length of the strip entering the mill, block 7 calculating the length of a turn, block 8 calculating the length s strips residue unit 9 vychiSuChenich Putz,

a comparator unit 10, a mill speed controller 11, a relay element 12, a tension controller 3 of the unwinding device.

Sensor 1 is engaged with the shaft of the measuring roller, which, without slippage, rolls in the strip entering the mill. Sensor 1 outputs a sequence of pulses, the number of which is proportional to the length of the strip passing into the mill, and their frequency to the speed of the strip at the mill input. The generator 2 generates a sequence of standard pulses of a stable frequency, which is at least 100 times higher than the maximum frequency of the signals from sensor 1. Sensor 3 generates a sequence of pulses, the number of which is proportional to the angle of rotation of the unwinder, and the frequency to its angular velocity. Unit 4 counts standard impulses from generator 2 between the first impulse from sensor 3 (at the beginning of the unwinder rotation) and the first impulse from sensor 1, as well as between the first and second impulses from sensor 1, i.e. counts the number of standard impulses

Pg, o Pg, 1, “i-l, o; Lg-1d, Etc. In the remaining spans as superfluous, the calculation of standard impulses by block 4 is not performed. Block 5 calculates the values of the proportional segments ig, a, -, etc., using the expressions

a.-i - g ai

i, i

,

/ CM. formula (14) /. Block 5 provides in the following diagrams information about each segment twice. First with a negative sign, and then with a positive one. Unit 6 counts the number of pulses from sensor 1 for each revolution of the unwinder and calculates the length of the segment corresponding to this number of pulses by the expression

  ,;

/cm. formula (14) /.

Block 7 remembers the information coming from blocks 5 and 6 and calculates the length of the coiled coil according to the formula (14), after the signal about the fractional segment with a negative sign arrives. Block 8, using information from block 7 about the length of the wound coils and data on the length of the first (internal) coil /; and on the length of the metal enclosed between the decoiler and the rolling stand, calculates the length of the remainder of the strip on the decoiler using formula (9) and the entire non-rolled strip using formula (4). According to the signal from the relay element 12, the output signal of the block 8 becomes equal to the sum of the length of the first turn and the length of the metal between the unwinder and the rolling stand. Block 9, using signals from the sensor, calculates the required braking path from the current rolling speed using the expression

V

one,

2o

(/ t is the braking path; V is the rolling speed; and is the specified acceleration). Block 10 according to blocks 8 and 9 compares the value of the length of the remainder of the strip with the required length of the braking path and at the moment of their equality forms a command to the mill speed controller 11 for braking with a given acceleration. In the process of braking after coiling from the unwinder of the canadian coil

block 10 re-compares the values of the specified lengths, the results of which produce a correction signal. Relay element 12 connected by its input to tension regulator 13

an unwinding device generates a control signal to the unit 8 at the time of the disappearance of the tension that occurs when the tail of the strip leaves the unwinder. The device works as follows.

When the strip is rolled, the pulses from sensor 1, from generator 2 and sensor 3 are fed to the inputs of block 4, which counts the number of standard pulses between the pulse from sensor 3

and the first impulse from sensor 1 as well

 between the first and second pulses from

sensor 1. This information comes to

input block 5, which calculates the value

fractions of the discreteness of the pulses of sensor 1, which is between the pulse from sensor 3 and the first pulse from sensor 1. At the same time, block 6, counting the number of pulses from sensor 1 for one

The turn of the decoiler, according to the known discreteness of the sensor 1, calculates the length of the strip corresponding to this number of pulses. Information from block 5 on the value of the fractional length segment and from block 6

the value of the segment, measured by integer discretes of sensor 1, is fed to the inputs of block 7. The latter memorizes the incoming information and calculates the length of the coiled coil. Block 8, using information from block 7, using the known data on the length of the first (inner) coil roll and the length of the strip between the unwinder and the mill stand, calculates the value of the total remainder

strip at the entrance of the camp. The signals from block 8 about the calculated length of the non-rolled strip and from block 9 about the required braking path arrive at the inputs of block 10, which compares the values of these signals and at the moment of their equality issues a control to the mill speed and the command to start braking with a given acceleration. In the process of braking according to the calculations after winding with the unwinder each turn

unit 10 performs a re-run.

the results of which, through the controller 11, make a correction to the deceleration rate, providing the required mode of deceleration of the mill. At the final stage of the braking of the mill, the relay element 12 connected with the input to the strip tension regulator 13 fixes the moment when the strip tension disappears, which occurs when the tail of the strip leaves the unwinder drum and issues a control signal to block 8. By this signal, block 8, instead of a signal about the calculated value of the remainder of the strip, gives block 10 a signal about the actual remainder of the non-rolled strip, which is formed from the length of the first (inner) turn and the length of the strip between the unwinder and the roll stand. The unit 10, having received the actual balance signal, if necessary, performs an additional correction of the braking mode so that the tail of the strip enters the rolling mill at the required speed. The ability of the device to calculate the remainder of the strip with high accuracy and correct the deceleration rate, eliminates coast down braking and improves control quality, which ultimately improves the productivity of the rolling mill. Additional corrections to the actual remainder of the band, in addition, increase the reliability of control and reduce the likelihood of emergency situations on the mill, which may be due to computational errors. The use of standard high-frequency pulses leads to the fact that repeated calculations in the process of slowing down the mill are carried out with increasing accuracy. This circumstance makes it possible to use a coarser length sensor in the device without losing accuracy of operation.

Claims (2)

1. An apparatus for automatically controlling braking of a rolling mill equipped with a speed controller and a tension controller of an unwinding device, comprising a length sensor of an incoming strip, an angle decoder for an unwinder, a unit for calculating the length of an entire length sensor of the length of the mill strip, a block calculating the length of the coil, the block for calculating the length of the remainder of the strip, the block for calculating the braking path, and the block 5 of the comparison, characterized in that, in order to improve the accuracy of calculating the length of the remainder of the strip and improve the quality braking control, it additionally contains a generator of standard 0 pulses, a standard pulse counter unit, a discrete fraction calculation unit of the length sensor of the strip entering the mill, with three inputs of the standard pulse counter block respectively connected to the output of the unwinder angular velocity sensor with the output of the length sensor of the incoming strip and the generator output standard pulses, and its output is connected to the output of the computing unit 0 the discrete fraction of the length sensor in the mill strip, the output of which is connected to the first input of the coil length calculation unit, the output of the length calculation block of the length sensor in the mill strip, two inputs of which are respectively connected to the angular sensor output unwinder speed and with the output of the length sensor of the strip entering the mill, 0, the output of the loop length calculation unit is connected to the first input of the strip length calculation unit, connected by its output to the first input of the comparison unit, the second input of which is connected to the output of the braking path calculating unit, connected to the output of the length sensor in the mill strip, the output of the comparator unit is connected to the input of the mill speed controller. 0 2. The device according to claim 1, characterized in that it comprises a relay element, the input of which is connected to the output of the tension regulator of the unwinding device, and the output is connected to the second input of the unit for calculating the length of the remainder of the strip. Sources of information taken into account in the examination 1. USSR author's certificate 0 No. 248035, class At 21B 37/00, 1970.