SU882675A1 - Strip thickness automatic control system - Google Patents

Description

The device relates to the technique of automatically controlling the thickness of the strip, for example in the stand of the cold rolling mill, by controlling the pressure mechanism.

A known system for adjusting the thickness of the strip, comprising a successive gauge for measuring the thickness of the roll-up from the average, a first delay unit, a control unit for the pressure mechanism and a pressure mechanism, as well as a measure for the deviation of the thickness of the rolled metal from the average. In this device, the errors of the stiffness information embedded in the gain of the control units K are corrected by using the rolling force sensor signal; the delay unit is controlled by the speed sensor signal C.

The disadvantage of this system is that its implementation requires rather complicated technical means, such as force mesdoses,

acting as sensors for rolling force, tachogenerator, performing speed sensor, necessary electronic processing units. In addition, this system is not sufficiently stable due to the fact that one of the components of the signal acting on the pressure mechanism is a bare signal from the gauge of the thickness deviation of the rental (t), whose control action is delayed by the transit time nor from the roll gap to the gauge, creating unnecessary regulation.

The purpose of the invention is to simplify the system and stabilize the regulation.

This goal is achieved by the fact that the system for automatically adjusting the thickness of the strip, containing in series a measurer of the deviation of the sub-roll thickness from the average, the first unit. delays, a push mechanism control unit, a push mechanism and a rolling thickness deviation meter from an average value, further comprise a second delay unit and a first correlator comprising a multiply connected unit and integrator in series, the input of the delay unit connected to the output of the first delay unit, and output - to the first input of the multiplication unit, the second input of which is connected to the gauge of the deviation of the thickness of the car from the average value, and the output of the integrator is connected to the second input of the control unit Moreover, the first delay unit is controllable and the system also additionally contains a differentiating link and a second correlation block, the input of the differentiating link is connected to the output of the delay block, and the output of the differentiating link is connected to the first input of the second correlator, whose second input connected to the gauge of the deviation of the thickness of the car from an average value, and the output of the second correlator is connected to the input of the first delay unit. The proposed device does not need sensors for rolling force and rolling speed, but uses current information from the gauge of thickness of the rolled strip k ;, (t) and rolled h (i) from the specified value. For automatic adjustment of the transmission coefficient K and the delay X in the control mechanism of the pressing mechanism, the fact is used that if they are incorrectly set, random deviations of the roll-up li (t) thickness are not fully compensated, but appear in random variations of the rolled-thickness lf (i} - This relationship between the signals and tig (t) is quantitatively characterized by the so-called correlation function R (ST) y li (t T) 2 (t) dt. (It depends on the delay (. Between the measurement points h (il} and d (t)) and can be obtained using a correlator, which is a signal multiplier h ;, (t T) and hg (t) and the integrator which averages the value of their product over time T. At the same time, R (1) is maximum, if the delay is T, in the signal chain l (i) exactly coincides with the time T of the distance between measuring the deviation of the rolled and rolled stock. increasing the difference (1-1,), the value of R (L) is gradually decreasing. In FIG. 1, a block diagram of an automatic device is shown the thickness of the strip; FIG. 2 is a typical view of the correlation function P {C); FIG. 3 is its derivative 1 (L); The device includes a gauge 1 deviation of the sub-roll thickness from the average value, the first delay unit 2, the control unit 3 the pressure mechanism, the pressure mechanism 4 connected in series, the second delay unit 5, the output of which is connected to the input of the first delay unit 2, the first correlator 6, which is a multiplication unit 7 and an integrator 8 connected in series, the first and second inputs of the multiplication unit are connected respectively, with the outputs of the second delay unit 5 and the meter 9, the deviation of the thickness of the rolled product from the average value, and the output of the first correlator b to the second input of the control unit 3 for automatic adjustment of its transmission coefficient K, for the automatic adjustment of the delay L, to the output of the second delay unit 5 parallel to the first the correlator to the torus 6 is connected to the differentiating link 1O and the second correlator 11, similar to the first, and the output of the second correlator 11 is connected to the second input of the delay unit 2 for its adjustment. The device works as follows. The signal (t) of the gauge 1 deviation of the rolling thickness is delayed in block 2 of the delay by time T, the strip passes from gauge 1 to the roll gap, From the output of block 2 of the delay 2, the signal b (t-T) is fed to the block 3 of the pressure mechanism control, which has a transmission coefficient K, The pressure mechanism 4 moves the rolls of the stand (or changes the rolling force) in proportion to the magnitude of the effect K And, | (t - C) so as to compensate for the deviation of the thickness of the section of rolled b (t - T ,,), which by this time falls into the roll gap. After a time T, this section of the rental enters the gauge 9 of the thickness thickness deviation, the signal bg (t) from the output of which goes to the multiplier 7 of the correlator 6, At the same time the signal 1 (t -) from the output of the delay block 2 is delayed in the second block 5 delay time Lj n is fed to the first input of the multiplication unit 7. At the output of multiplication unit 7, it forms a product signal, t, e. H / t-t) b, {0, T 7 7 I where L i - C 1-J is the total signal delay in blocks 2 and 5 of the delay. The integrator 8 averages over time T the signal received from multiplication unit 7, i.e. T f Jb, (bt) h2Ct) dt R (t) thereby forming the correlation function R (t) by formula (1). If the output signal of the integrator 8 R (l) is positive, this indicates that the deviations of the sub-roll thickness li (-t) are not sufficiently smoothed by the pressure mechanism 4 and they repeat in the variations of the thickness of the rolled j after a time T (required for the passage of a distance between sensors 1 and 9). A positive or negative deviation of the rolled steel thickness b (t) after the time T will lead to the same (by polarity) deviation of the rolled product thickness bjCt), so that on average the product lij (it) lij (ija with it and Р (L) more than zero (curve 12 of Fig. 2). Thus, a signal at the output of the correlator O indicates that the transmission coefficient of control block 3 is insufficient (,). If the transfer ratio of the control unit 3 is too large (), the pressure mechanism 4 over-compensates for the thickness of the sub-roll b (0 so that a positive thickness deviation of the sub-roll h;, (- t - L) O will correspond to a negative deviation of the sub-roll thickness Ch, (t) СГ) and out of town-. Then, on average, the product of h (t-Lph Ci), and with it, 1 (T /) will be negative (curve 13 in Fig. 2). The signal I (T) from the output of the correlator 6 is fed to the second input of the control unit 3 to adjust the transmission coefficient K, and a positive signal I (L) should lead to an increase in K and a decrease otherwise. The absence of a correlating modulus P (T) 0 indicates that the transmission coefficient of block 3 is optimal: K K ,. Errors in adjusting the thickness of the rolled stock also arise due to the incorrect setting of the time shift T in block 2 delays. If the delay T is longer than the travel time from the gauge 1 to the roll gap, then the response of the pressing mechanism 4 to the deviation of the rolled steel will be delayed and vice versa in the previous case. To eliminate such errors, there is a delay control loop consisting of a differentiating link 1O and a second correlator 11, similar to the first one. The signal b (t-L /) from the output of the second delay unit 5 is fed to the input of the four link unit 1O. The signal l. (The output of the differentiating link (the prime means differentiation) is fed to the first input of the multiplier unit of the correlator 11, the second input of which supplies the signal t (t) from the meter 9 to the rental thickness deviation. After averaging over time T in the integrator, the output is a correl of torus 11 a signal is generated f jh; (tT) h, (t) (r) (2) This signal equal to the derivative of the correlation function (1) has the form shown in Fig. 3. It changes sign depending on the sign the difference (I - C) between the time T of the distance between the meter 1 and the meter 9 and the sum of the delay L set in delay blocks 2 and 5. The signal - P (T) at the output of the correlator 11 serves as a measure of the delay mismatch. It is applied to the second (regulating) delay block 2 and adjusts the delay I, so that in case of a positive The signal R (L) at the output of the second correlator of the delay 11 Q should increase and vice versa in the npoTiffHOM case. At the same time, the inversion corresponding to the minus sign before the integral in expression (2) is taken into account. The proposed device makes it possible to significantly simplify the device according to method (2), since it does not use power mesos and tachogenerators, which are force and speed sensors, and obtains the necessary information through the processing of electrical signals H2 (1) and) the gauges of the thickness of rolled and rolled metal. For this purpose, such blocks as correlators, consisting of a multiplier and an integrator, switched on in a consistent manner, and a de- firing link, which can be made in the form of simple electronic circuits, are used. In the presence of analog digital converters, these operations can be performed by the simplest computer hardware. The stability of the operation of the proposed device is guaranteed by the fact that the control rings operate at different time scales and therefore do not influence each other. The control ring with anticipation is fast, its speed is limited only by the speed of the pressure mechanism At, then Kaii the speed of unrelated to each other transfer rings of the transmission coefficient K and the delay Tc is determined by the time T of the integrators of the correlators 6 and 11. Constant time integrators can to be different, but they are always much longer than the constant time of the pressure device. The economic effect from the implementation of the invention on one rolling mill will be 50 thousand rubles per year. The inventive formula 1, the system for automatically controlling the thickness of the strip, coherently connected in series to measure the rollout of roll-up thickness from the average value, the first delay unit, the pressure mechanism control unit 58 and the pressing mechanism, as well as the rolling thickness deviation measurer from the average value differing from that, in order to simplify the system and increase the stability of the regulation, it further comprises a second delay unit and a first correlator containing an integrator, the input of the second delay unit is connected to the output of the first delay unit, and the output is connected to the first input of the multiplication unit, the second input of which is connected to the gauge of the thickness variation of the car from the average value, and the integrator output is connected to the second input of the control unit. 2. The system for automatically adjusting the strip thickness in accordance with claim 1, 1, and T is characterized in that the first delay unit is controllable and contains a differentiating element and a second correlator, the input of the differentiating element being connected to the output of the second delay unit, and the output of the differentiating element connected to the first input of the second correlator, the second input of which is connected to the gauge of the deviation of the thickness of the car from the average value, and the output of the second correlator to the torus is connected to the input of the first delay unit. Sources of information taken into account during the examination 1. USSR Author's Certificate No. 593760, cl. B 21 B 37 / GS, 1978.

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Claims (2)

Claim 1 "A system for automatically controlling the thickness of a strip, comprising in series a meter for measuring the deviation of the rolled thickness from the average value, a first delay unit, a control unit for the push mechanism and a push mechanism, and a meter for deviating the thickness of the rolled metal from the average value, characterized in that 5, for the sake of simplification system and increase the stability of regulation, it additionally contains a second delay unit and a first correlator, containing in series a knife unit 10 and an integrator, moreover stroke of the second block bottom er um and connected to the output of the first delay unit and output - with a first input of the multiplication unit, a second input coupled to a measurer 15 deflection strip thickness from the middle 'value, and the output of the integrator is connected to the second input of the pressure mechanism control unit. 2. The system of automatic control of strip thickness by z. 1, characterized in that the first delay unit is controllable and contains a differentiating link and a second correlator, the input of the differentiating link being connected to the output of the second delay unit, and the output of the differentiating link being connected to the first input of the second correlator, the second input of which is connected to a gauge of deviation of the thickness of the rental from the average value, and the output of the second correlator is connected to the input of the first delay unit.