SU1507481A1 - Sensitive element for indicating the presence of metal in rolling stand - Google Patents

Abstract

The invention relates to rolling production, in particular, to control and regulating devices of rolling mills, and can be used in automation systems and control of these mills. The purpose of the invention is to increase the reliability of operation by eliminating false positives. The metal presence sensor in the rolling stand contains a current meter 1, an adder 2, a threshold element 3, a trigger 4, and a digital-to-analog converter (DAC) 5. The current meter 1 produces a signal proportional to the current of the rolling motor core. The digital-to-analog converter 5 generates a correction signal proportional to the reference voltage applied to the DAC 5 from the inverse output of the trigger 4, and the binary number specified on the digital input of the DAC 5 by the rolling mill operator before starting work. Binary numbers correspond to certain modes of operation of the stand and grades of rolled metal. They are selected in advance when setting up the sensor. Switching trigger 4 causes a change in the correction signal of the DAC 5. The device works more reliably by taking into account changes in the operating modes of the rolling stand and the grade of rolled products, as well as the absence of false alarms from impulse noise. 2 Il.

Description

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The invention relates to rolling, production, in particular to control and regulating devices of rolling mills, and can be used in automation systems and control of these mills.

The purpose of the invention is to increase the reliability of operation by eliminating false positives.

FIG. 1 shows a functional diagram of the sensor for the presence of metal in the rolling stand; in fig. 2 - timing diagram of the sensor.

The metal presence sensor in the rolling stand (Fig. 1) contains a current meter 1, an adder 2, a threshold element 3, a trigger 4 and a digital-analog converter 5, while the output of the current meter 1 is connected to the first input of the adder 2, the second input of which is connected to the output of the digital-to-analog converter 5, the ext-sum sum-curtain 2 through the threshold element 3 is connected to the trigger input 4, the direct output of which is the output of the metal presence sensor in the roll stand, and the inverse output is connected to the first input of the digital-analog converter 5, the second the input of which is the output of a correction unit (not shown). The device works as follows.

Power is applied to the device. At the digital input of the digital-to-analog converter 5, which is the output of the correction unit, a binary number is set that corresponds to a given mode of operation of the stand and the type of rolled metal. This binary number is entered by the mill operator.

In the absence of a billet in the rolls of the rolling stand, the voltage at the direct output of flip-flop 4 corresponds to the voltage log. A. The magnitude of the correction voltage, which is fed from the output of the digital-to-analog converter 5 to the second input of the adder 2, is determined by the binary number specified on the digital input of the digital-analog converter 5, and the reference voltage, which is removed from the inverse output of trigger A and in the absence of a blank rolling stand is equal to voltage log. one.

A current meter 1 produces a signal (FIG. 2a), proportional to

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current core rolling motor (not shown). At the same time, the output signal of the current meter 1 contains pulse noise proportional to the pulse noise existing in the core of the rolling motor. The output signal of the current meter 1 is fed to the first input of the adder 2 and is summed with the correction signal of the digital-to-analog converter 5 supplied to the second input of the adder 2. In view of the fact that the correction voltage of the digital-analog converter 5 has a polarity opposite to the polarity of the output signal of the current meter 1, the level of the output voltage of the adder 2 (Fig. 2b) is lower than the level of the output signal of the current meter 1 by the amount of the correction voltage from the output of the digital-to-analog converter 5. At that The impulse noise existing in the output signal of the adder 2 cannot exceed the threshold voltage level of the threshold element 3 and cause false detection of the metal presence sensor in the rolling stand.

When the billet is seized by the rolls of the rolling stand, the current of the rolling motor core increases. The output signal of the current meter 1 and the output signal of the adder 2 proportionally increase. The correction signal of the digital-to-analog converter 5 is a constant-magnitude signal, it does not change until the set binary number on the digital input of the digital-analog converter 5 or the reference voltage changes The output from the inverse output of the trigger 4. The output signal of the adder 2 increases in proportion to the signal of the current meter 1, i.e. proportional to the current of the rolling motor core. At the moment when the output signal of the adder 2 becomes greater than the threshold voltage of the threshold element 3, the latter switches, the voltage at its output increases sharply. The output signal of the threshold element 3 is fed to the input of the trigger 4. At the moment when the output voltage of the threshold element 3 becomes greater than the trigger threshold of the trigger 4, the latter switches. Voltage at its direct output (Figure 2d)

becomes equal to the voltage log. 1 voltage at the inverse output - voltage log. A. At the same time, the input voltage of the digital-to-analog converter 5 is also supplied with a voltage. A. The output voltage of the D / A converter 5 decreases sharply (Fig. 2c), this decrease causes the voltage of the output signal of the adder 2 to increase. A voltage output of the output signal of the adder 2 arises with respect to the threshold voltage level of the threshold element 3. This prevents false alarms sensor of the presence of metal in the rolling stand with a decrease in current of the core of the rolling motor when rolling the billet near its end. In this state, the sensor for the presence of metal in the rolling stand is located until the ejection of the workpiece from the rolls of the roll stand of the rolling mill.

When the workpiece is ejected from the rolls of the rolling mill stand, the current of the rolling motor core decreases. The signal of the current meter 1 and the signal of the adder 2 are also reduced. When the output voltage of the adder 2 becomes less than the threshold voltage, the threshold element 3 switches, the voltage at its output decreases, which causes the switching of the trigger 4. At the same time, the output voltage of the trigger 4 appears in the log. Oh, and on the inverse - voltage log. 1, which is fed to the input voltage of the reference voltage of the digital-analog converter 5. An increase in the reference voltage causes an increase in the output voltage of the digital-analog converter 5, which causes a simultaneous decrease in the output signal of the adder 2. The metal presence sensor in the rolling stand is in the standby mode described above which lasts until the roll is seized by the rolling stand of the next billet. After the rollers grab the next billet, the sensor

continues to work as described.

Thus, the capture of the workpiece rolls causes the appearance of a log. 1 at the direct output of the trigger 4, and the ejection of the workpiece from the rolls - log. About at the direct output of the trigger 4. The switching times of the trigger 4 correspond to the moments of capture and release of the workpiece from the cage.

The operation of the metal presence sensor in the rolling stand is illustrated by the timing diagrams shown in FIG. 2, which shows the output signals of the current meter 1, the total

and digital to analog 5 in a single scale

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The binary number, which determines the magnitude of the correction signal of the D / A converter 5, is selected in the process of setting up the sensor for the presence of metal in the rolling stand experimentally separately for each mode of operation of the stand and the grade of rolled metal.

The proposed sensor makes it possible to increase the reliability of fixing the moment when the metal enters and leaves the cage.

Claims (1)

Invention Formula A metal presence sensor in the rolling stand, containing a current meter, a threshold element and a trigger, which is due to the fact that, in order to increase operational reliability by eliminating false alarms, an adder and a digital-analog converter are entered into it, and the current meter output is connected to the first input of the adder, the second input of which is connected to the output of the digital-to-analog converter, and the output of the adder is connected via a threshold element to the trigger input, the direct output of which is the output of the metal presence sensor in okatnoy stand and inverse output is connected to a first input of a digital to analog converter, the second input of which is the output correction unit.