RU2362650C2 - Method for control of ingot speed in roller of continuous casting machine - Google Patents

Abstract

FIELD: technological processes.

SUBSTANCE: invention is related to the field of continuous casting machines. When controlling ingot speed by control of rotation speed of electric motors of roller device rolls and calculation of their rotation speed setting in accordance with specified ingot speed, average value of average calculated rotation speed of all roller electric motors per every roller rotation with speed detector and average value of measured ingot speed for the same time. Ratio of these values is calculated, and by multiplication of this ratio by specified speed of ingot, setting is calculated for regulators of electric motor rotation speed. Invention increases accuracy of ingot speed control due to elimination of effect of rotation pulsations of speed detector signal caused by distortion of geometry of roller with speed detector due to its uneven heating and wear in process of operation. Pulsations of electric motor current are reduced, and errors in calculation of electric motor rotation speed and those caused by variation of driving roller diametre due to wear (apart from roller with speed detector) are compensated.

EFFECT: provision of possibility to use rotation speed calculated in every electric drive as regulator feedback signal and not to use it for drives of rollers of individual speed detectors; increased accuracy of control.

Description

The invention relates to the field of continuous casting machines, and more particularly to controlling the speed of an ingot in a roller apparatus of a continuous casting machine by changing the rotation speed of the drive rollers of the apparatus.

There is a method of controlling the speed of an ingot in a roller apparatus of a continuous casting machine, in which the rotation speed of the electric motors of the rollers of the apparatus is changed, using the speed feedback of one of the drive rollers, with the shaft of which a speed sensor is kinematically coupled - a tachogenerator or a pulse sensor (Margolin Sh.M Electric drive of continuous casting machines. M., Metallurgy, 1987, pp. 84 ... 86, pp. 99-106).

However, this method has a significant drawback, namely, that if the geometry of the roller articulated with the speed sensor is distorted due to uneven heating and wear occurring during operation of the continuous casting machine, its rotation speed changes during each revolution. This leads to the occurrence of reverse pulsations in the signal of the speed sensor and causes phase pulsations of all electric motors of the roller apparatus coinciding in phase, as a result of which large pulsations of the ingot speed appear, which reduces the accuracy of its speed regulation and impairs the quality of the ingot, and the pulsations of the motor currents increase their heating.

The known solution to eliminate the influence of reverse pulsations in the speed sensor signal by introducing a filter into the feedback channel cannot be used in the speed control systems of the rollers of the roller apparatus of a continuous casting machine due to the low frequency of these pulsations, which is determined by the time of one revolution of the roller at the operating speed 30 ... 60 s and is not more than 0.03 Hz. Entering a filter would lead to an unacceptable decrease in speed and accuracy of speed control.

The problem solved by the invention is to eliminate the influence of reverse pulsations of the ingot speed sensor by adjusting the speed of rotation of the electric motors of the rollers of the roller apparatus and thereby increase the accuracy of regulating the speed of the ingot in the continuous casting machine.

This problem is solved as follows.

In the known method for controlling the speed of an ingot in a roller apparatus of a continuous casting machine, including measuring the speed of an ingot by a speed sensor coupled to one of the rollers, and subsequently adjusting the speed of rotation of the electric motors of the rollers in accordance with the given speed of the ingot, the average for each revolution of the roller with the sensor is calculated, ACCORDING TO THE INVENTION the velocity value of the average calculated rotation speed of all roller motors and the average value of the measured ingot speed for the same time, is calculated elations calculated average rotation speed of the rollers to the secondary motors in the same time the value of the measured speed of the ingot, this ratio is multiplied value by a predetermined rate of the ingot and uses this value as the reference roller motor speed.

The use of the measured ingot speed averaged over a revolution of a roller with a sensor virtually eliminates pulsations in the rotation speed of the electric motors of the rollers of the apparatus, caused by distortion of the geometry of this roller, and thereby eliminates the indicated pulsations of the ingot speed.

A method for controlling the speed of an ingot in a roller apparatus of a continuous casting machine includes measuring the speed of an ingot with a speed sensor coupled to one of the rollers and setting the rotation speed of the roller motors, which is determined as follows:

- in the power converters of the electric motors of the rollers, the rotational speeds n _calc are calculated _. electric motors by the magnitude of their EMF when using DC electric motors or by the frequency of the supply voltage and the magnitude of the active current of electric motors using a mathematical model when using AC electric motors;

- calculate the average rotation speed for all electric motors

n _compute ;

- calculate the average value for each revolution of the roller with the speed sensor, the average value for all electric motors of the rotation speed n _{calculated average / rev.} ;

- calculate the average for each revolution of the roller with the speed sensor, the value of the measured ingot speed V _{rev.mean./about.} ;

- calculate the ratio of the average values of n _{calcul.sr. / rev.} / V _rev. ;

- multiply this ratio by a given ingot speed V _ass. , getting the desired job rotation speed n _subtract. :

n _subtract = V _ass. × (n _{calc. Mean / rev} / V _{meas. Mean / rev.} ).

The obtained value is used to set the rotation speed of the roller motors, which is fed to the input of the speed controllers implemented in the power converters of the electric motors.

Due to this, the influence of reverse pulsations of the speed of rotation of the roller with the speed sensor on the accuracy of maintaining the speed of the ingot is eliminated, while the inaccuracies in calculating the speed of rotation of the electric motors and the change in the diameters of the rollers due to wear are compensated, except for the roller with the speed sensor.

The method is implemented in a control system of a continuous casting machine using a computing device — a programmable controller that calculates, for each revolution of the roller with a speed sensor, the average value of the average rotational speed n calculated in this time, _nfrev. of all electric motors of the rollers and the average value of the speed of the ingot V _{meas. average / rev.} , calculates the ratio of these average values n _{calculated sr / rev.} / V _rev. , remembers it until the next calculation is performed, and calculates the task for the electric motor speed controllers by multiplying the specified ingot speed by the ratio

n _calc. / V _rev. .

The feedback signals of these regulators are calculated in the converters, as described above, the rotation speed of the roller motors.

The speed of the ingot is measured by a speed sensor kinematically connected to one of the rollers of the apparatus.

The controller receives the values of the calculated rotation speeds of the roller electric motors from the converters supplying the electric motors.

The initial value of the ratio

n _calc. / V _rev. determined by calculation using passport values of the diameters of the rollers, gear ratios of gearboxes and rated parameters of electric motors.

In the process of rotation of the rollers, the speed of the ingot is determined taking into account the diameter of the roller with a speed sensor. The speed sensor determines the signal of the end of each revolution of this roller and calculates the average value for the time of revolution of the average calculated rotation speed of all the roller motors, the average value of the speed of the ingot and the ratio of these values. The calculated ratio of the average values is introduced into the multiplication described above by specifying the speed of the ingot instead of the initial value.

Thus, during the operation of the roller drives, the task of the rotation speed of the electric motors is calculated in accordance with the ratio of the average values of the calculated average rotation speed of all electric motors and the measured ingot speed, and the rotation speed is controlled by speed controllers with a speed inherent in such regulation, but without using individual each roller of speed sensors.

Due to such a combination of the speed of rotation of the electric motors of the rollers corrected by the proposed method and fast regulation, the required quality of controlling the speed of the ingot is achieved in the absence of the influence of reverse pulsations in the signal of the speed sensor coupled to one of the rollers of the apparatus. Also, the ripple of the current of the electric motors of the rollers is reduced, the heating of the electric motors is reduced.

Claims (1)

A method for controlling the speed of an ingot in a roller apparatus of a continuous casting machine, comprising measuring the speed of an ingot with a speed sensor coupled to one of the rollers, and then adjusting the speed of rotation of the electric motors of the rollers in accordance with a given speed of the ingot, characterized in that the average for each revolution of the roller is calculated with with a speed sensor, the value of the average calculated rotation speed of all roller motors and the average value of the measured ingot speed at the same time, the rel The ratio of the average calculated rotation speed of all roller motors to the average value of the measured ingot speed at the same time, multiply the ratio by the specified ingot speed and use this value as a reference for the rotation speed of the roller motors.