SU1710158A1 - Device for automatically controlling strip thickness in a rolling mill - Google Patents

Abstract

The automatic thickness control device on a rolling mill relates to the automation of cold and hot rolling mills. The purpose of the invention is to reduce the thickness variation of the rolled strip by eliminating the effect on the output signal of the pulsation device of the input signal. It is achieved by introducing into the forward channel the devices of the serially connected integrative memory element and deadband unit covered by negative feedback. The size of the dead zone is chosen to be equal to a'm-width of the pulsations of the input signal. Due to the additionally introduced elements, the output signal of the device (the output of the integrating memory element) at the appearance of a constant component of the input signal changes by the value of this constant component. At the same time, the pulsations at the exit do not pass, remain inside the dead zone. As a result, while maintaining the highest possible speed for the “deviation” controllers, the effect of input signal ripples is eliminated. on the thickness of the strip. 1 ill. whereby the regulating influence of the regulator is fed to the input of the regulator simultaneously with the change of the controlled parameter caused by this regulating influence. The control action received over the positive feedback circuit replaces the eliminated deviation of the controlled parameter? As a result, the output of the controller after the perturbation has not been changed and remains equal to that required for compensation

Description

Disturbance caused by the initial declination of the controlled parameter.

The Resvik regulator does not contribute its own delay, so its speed is the maximum possible.

The disadvantage of the Reswick controller is the limitation of its scope by such objects, V of which the adjustable parameter does not contain high frequency ripples, i.e. such a frequency that cannot be worked by this object due to its inertia. It is these pulsations that exist in the output signal of the thickness gauge in the cold rolling mill; therefore, the device that implements the Resvik controller in its pure form cannot be used to control the thickness in the cold rolling mill.

If there are higher frequency pulsations in the input signal of the Reswick controller, these pulsations are repeated at the controller output, then through a chain of delayed positive feedback arrive at the controller input, where they accumulate with the current pulses and pass to the controller output. As a result of the circulation of the pulsations, deviations of the controlled T1 parameter from the reference occur.

Closest to the proposed technical entity is a device for automatically controlling the thickness of a strip in a continuous cold rolling mill, which includes a gauge of relative thickness deviation, an adder, a roll speed control system, an adjustable lag unit, we take the meter output connected to the first input of the adder, the output the adder is connected to the input of the speed control system of the rolls, the output of which is connected to the input of the adjustable delay unit, the output of which is connected the second input of the adder. In this device, a roll speed control system with a transfer coefficient equal to one is included in the device, its output signal, which is an unequivocal change in the roll speed, is delayed in the adjustable delay unit for the control object retardation time and as a positive feedback goes to the second adder input.

The device pa, as described, does not, however, provide for a reduction in the thickness variation of the rolled strip, because under the rolling mill conditions, the output of the roll curvature control system, besides the change in speed, which serves to eliminate the deviation of the strip thickness, contains components for measuring

speed from other systems, regulating {for example, limiting tension, redistributing the load of the stands) that do not affect the thickness of the strip

and should not be memorized with a thickness control device. These components, through the variable lag unit at the entrance of the roll speed control system, create on the strip

0 additional thickness deviations.

The aim of the invention is to reduce the thickness variation of the rolled strip.

This goal is achieved by the fact that a dead zone unit and an integro-blocking element, the output of the RELATIVE thickness gauge, are connected to the first input of the adder, the device containing the relative thickness deviation meter, the adder, the roll speed control system, the second input of which is connected to the output of the adjustable lag unit, the output

5 of the adder is connected to the input of the dead zone unit, the output of which is connected to the input of the integral memory element, the output of which is connected to the input of the roll speed control system,

0 an input of the adjustable lag unit and with a third (inverse) input of the adder. The drawing shows a block diagram of the proposed device.

The output of the relative thickness deviation meter 1 is connected to the first input of the adder 2, the second input of which is connected to the output of the adjustable lag unit 3, the output of the adder 2 is connected to the input of the dead zone unit 4,

0, the output of which is connected to the input of the integrate memory element 5, the output of which is connected to the input of the roll speed control system 6, to the input of the adjustable delay unit 3 and to the third (inverse) input of the adder 2.

In view of the fact that in order to eliminate the relative deviation of thickness from the task on a continuous cold rolling mill, the same magnitude and

0 sign is the relative change in the current speed of the rolls of the output stand, and modern roll speed control systems calculate the speed correction signals as a value of the relative change in the current speed, in the proposed device the transfer coefficients of all elements are equal to one and both feedbacks are single

The device works as follows.

Suppose that at the moment of switching on the proposed device, the mill is configured according to the rolling program, which ensures that the output of the thickness gauge 1 has a constant signal component equal to zero. Block 4 has a deadband equal to the amplitude of the pulsation of the signal from the meter 1, therefore the pulsations do not pass through block 4 and the input signal at the input of the integro-remembering element 5 is zero. The output signal of the element 5 at the time of inclusion is also zero. When a constant constant component of the thickness deviation appears at the output of the meter 1, the amplitude of the pulsation exceeds the dead band in the corresponding direction by the constant component of the input signal, a signal appears at the input of element 5, which disappears only when the integrating element 5 will produce at the output a signal, a speed correction equal in magnitude to the constant component of the thickness gauge signal, since only in this case the negative feedback signal arriving at the third This input of adder 2 will compensate the constant component of the thickness meter meter and return the pulsations inside the dead zone of block 4, a zero signal will be set at the input of element 5, and a signal equal to the constant component of meter 1 will remain at the element output. from the output, element 5, which has entered the input of the speed control system 6 of the rolls of the output stand of the mill, will cause a change in the constant component of the relative thickness deviation equal in magnitude and inverse to the sign of the original from loneniyu thickness. This thickness deviation over time equal to the mill lag will reach the output of meter 1 and remove the initial constant component in the output signal of meter 1. At the same time, the second input of the adder 2 will receive a positive feedback signal from the adjustable lag unit 3 that was delayed by the same lag value of the mill. This signal is equal in magnitude to the removed constant component of the output signal / a

meter 1 has the same sign, it replaces it with itself. Such a replacement does not change anything at the output of adder 2, since there only remain signal pulsations from meter 1 that do not pass through the dead band of block 4. The negative feedback signal will now balance not the constant component of meter 1, but the signal positive feedback coming from block 3. When subsequent deviations of thickness appear or when the signal of meter 1 changes continuously, the device operates in the same way. Each deviation of the constant component of the signal of the meter 1 causes an increment of the output signal of the element 5. by the magnitude of this deviation, taking into account the sign of the deviation.

The time constant of the intrinsic storage element 5 is minimally small, which ensures the elimination of the deviation of the controlled parameter during the object's lag time, and also ensures that pulsations are almost constantly located within the dead zone, thus eliminating their passage to the output of the element 5 and their effect on the strip thickness . The thickness variation of the strip at the outlet of the steel; as compared with the prototype, is reduced. Ph o rmula and 30 b ate Device for automatic adjustment of the strip thickness at a rolling mill, containing a gauge of thickness relative deviation from the task, which is connected to the first input of the adder, the second input of which is connected to the Output of the adjustable delay unit, the system control the speed of the rolls, which is so that, in order to reduce the thickness variation of the rolled strip by eliminating the influence on the output signal of the device, the input signal ripples integrozapominayuschim connected element and the block dead zone, whose input is connected to the output of the adder and the output integrozapominayuschegb element connected to the input roll speed control systems, with input of an adjustable delay and to a third input of the adder.

ABOUT

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Claims (1)

• Claim A device for automatically controlling the thickness of a strip on a rolling mill, comprising a relative thickness deviation meter from a reference, the output of which is connected to the first input of the adder, the second input of which is connected to the output of the adjustable delay unit, a roll speed control system, etc. I mean that, in order to reduce the thickness of the rolled strip by eliminating the effect on the output signal of the device, ripple of the input signal, the device is equipped with series-connected integros by the memory element and the deadband / input unit, the input of which is connected to the output of su.m. Let's say that at the moment of turning on the proposed device, the mill is configured according to the rolling program ^ which ensures that the output signal of thickness 1 • has a constant signal component equal to 5 zero. Block 4 has a deadband equal to the amplitude of the ripple of the signal of meter 1, so the ripple does not pass through block 4 and the input signal is equal to zero at the input of the integro-memory element 5. The output signal of element 5 at the time of inclusion is also equal to zero. When a relative component of the thickness deviation appears at the output of meter 1, the ripple amplitude exceeds the dead zone by 15 times the dead zone by the value of the constant component of the input signal, a signal appears at input • of element 5, which disappears only when the integro-jamming element 5 generates a signal at the output speed corrections, which is equal in magnitude to the constant component of the signal of the thickness gauge, since only in this case the negative feedback signal arriving at the input of Adder 2 will compensate for the constant component of the signal of the thickness gauge and return the ripple to the dead zone of unit 4. at the same time, a zero signal will be established at the input of element 5, and a signal equal to the constant component of the signal of Meter 1 will remain at the output of element 5. 5, received at the input of the roll speed control system 6 of the mill stand, will cause a change in the constant component of the relative thickness deviation, equal in magnitude and opposite in sign to the initial open Onen thickness. This deviation of the thickness after a time equal to the latency of the mill will reach the output of meter 1 and remove the initial constant component in the output signal of meter 1. At the same time, the second input 45 of adder 2 will receive a positive feedback signal from block 3 of the adjustable mat, and the output of integrally delayed delay which was delayed by the same delay value of the mill. This signal is equal in magnitude to the removed constant 50 component of the output signal r of the element connected to the input of the roll speed control system, to the input of the adjustable delay unit and to the third input of the adder. X.