CN1128030C - Device for obtaining slag outflow signal during ladle pouring - Google Patents

Abstract

The invention discloses a device for obtaining slag outflow signals during ladle pouring, which comprises a sine wave oscillator, a transconductance amplifier circuit, a peak detection circuit, a digitally controlled resistor network voltage divider, a filter amplifier circuit, a voltage comparison circuit, Bistable flip-flops, monostable flip-flops, RS flip-flops, and relays. The excitation source automatically adjusted by the numerical control resistance network voltage divider is adopted to adapt to the sensor in different steel flow paths, that is, as the bag order increases, the erosion of the nozzle brick path at the concentric position of the sensor and its replacement can be detected normally; various Filter circuit and shielding protection to increase the anti-interference performance of the device; set the threshold voltage of the voltage comparator to obtain immediate slag outflow response. Therefore, it has the advantages of good reliability and high accuracy, so that each ladle pouring steel can achieve the purpose of maximum steel output and minimum slag flowing into the tundish. The invention can be applied to the automatic detection and control of tapping and slag blocking of all metallurgical vessels.

Description

Device for obtaining slag outflow signal during ladle pouring

technical field

The invention relates to a non-electricity detection technology, in particular to a device for acquiring molten slag outflow signals during ladle pouring.

Background technique

The present invention applies the non-electrical measurement technology to establish an automatic detection device for the non-oxidation continuous casting production line. When the pouring of the ladle is nearing the end, once the slag flows out, the sensor installed at the tap hole of the device will feel the transformation of the steel slag. And convert this conversion into electric signal, after circuit processing and amplification, it becomes the driving signal for slag lowering alarm and closing ladle sliding nozzle, so as to realize automatic ladle closing with maximum steel output and minimum slag outflow effect.

In the prior art field, the published application date is February 22, 1986, and the application number is the "slag detection device" of 86100811. This device uses a simple constant current source to excite the sensor; uses the middle tap of the sensor to connect the temperature compensation circuit (anti-interference circuit) to overcome the interference caused by a wide range of temperature changes; uses a pulse width discriminator and a delay circuit to judge the outflow of slag . The device based on the above structure has the following disadvantages: 1. The simple excitation source has no automatic adjustment function, which cannot adapt to the fact that the replacement sensor has manufacturing errors and the diameter of the ladle expands after multiple pouring operations; 2. Due to the fact that the ladle With a large heat capacity, the temperature change speed of the sensor part is much slower than the slag outflow speed, and the slag outflow only occurs at the end of pouring steel. In fact, the extremely slow temperature change will not cause interference, but in the ladle During the steel pouring process, the anti-interference circuit failed to suppress the powerful mechanical and electrical interference existing in the steel plant environment; 3. The result of using the pulse width discriminator and delay circuit is that the inherent time between the slag flowing out and the closing bag is increased Delay, causing excessive slag to flow into the tundish, affecting the detection effect of the entire device.

Contents of the invention

The purpose of the present invention is to design a ladle pouring system that adopts a digitally controlled resistor network voltage divider to automatically adjust the excitation source, adopts various filter circuits and shielding protection to increase anti-interference performance, and sets the threshold voltage of the voltage comparator to obtain immediate slag outflow response. A device for obtaining slag outflow signals in the steel process.

The technical solution of the present invention is that it comprises: a sine wave oscillator, a transconductance amplifier circuit, a peak detection circuit, a digitally controlled resistor network voltage divider, a filter amplifier circuit, a voltage comparison circuit, a bistable trigger, a monostable trigger, RS flip flops, relays. The output of the sine wave oscillator is connected to the sensor through a transconductance amplifier circuit, a two-core cable, and a high-temperature connector. The output of the transconductance amplifier circuit is connected to a voltage comparison circuit through a peak detection circuit, a filter amplifier circuit, and the other input terminal of the voltage comparison circuit The adjustable positive potential is connected, and the output terminal is connected to the negative potential and the bistable trigger through the button. The input of the digitally controlled resistor network voltage divider is respectively connected to the output terminal of the peak detection circuit, the fixed voltage regulator, and the output terminal of the bistable trigger, and the output terminal of the digitally controlled resistor network voltage divider is connected to the input terminal of the transconductance amplifier circuit. The bistable trigger is respectively connected to the monostable trigger and the RS trigger, and the triode is connected to the relay, and the monostable trigger is respectively connected to the RS trigger and another relay via another triode.

The beneficial effects that the present invention has are:

1) The excitation source automatically adjusted by the numerical control resistance network voltage divider is adopted to adapt the sensor to different steel flow paths, that is, as the bag age increases, the erosion of the nozzle brick path at the concentric position of the sensor and its replacement can be detected normally;

2) Various filter circuits and shielding protection are used to increase the anti-interference performance of the device;

3) Set the threshold voltage of the voltage comparator circuit to obtain immediate slag outflow response.

Therefore, the new device has the advantages of high reliability and high accuracy, so that the maximum steel output can be achieved and the minimum slag can flow into the tundish every time the ladle is poured. The invention can be applied to the automatic detection and control of all metallurgical containers for tapping and slag blocking.

Description of drawings

Fig. 1 is a block diagram of the present invention;

Fig. 2 is a schematic diagram of a transconductance amplifier circuit;

Fig. 3 is a schematic diagram of a peak detection circuit;

Fig. 4 is the schematic diagram of the digitally controlled resistor network voltage divider circuit;

Fig. 5 is a schematic diagram of the filter amplifier circuit;

Fig. 6 is a schematic diagram of a voltage comparison circuit;

Fig. 7 is a record curve diagram of slag outflow signal.

Detailed ways

Structural block diagram of the present invention as shown in Figure 1, it comprises sine wave oscillator 1, transconductance amplifying circuit 2, peak detection circuit 6, digitally controlled resistance network voltage divider 7, filter amplifying circuit 8, voltage comparison circuit 9, bistable State flip-flop 10, monostable flip-flop 11, RS flip-flop 12, relay. The output of the sine wave oscillator 1 is connected to the sensor 5 through the transconductance amplifier circuit 2 , the twin-core cable 3 and the high temperature connector 4 . The output of the transconductance amplifier circuit 2 is connected to the voltage comparison circuit 9 through the peak detection circuit 6 and the filter amplifier circuit 8 . The other input terminal of the voltage comparator circuit 9 is connected with an adjustable positive potential, and the output terminal is connected with a negative potential and a bistable trigger 10 through a button. The input of the digitally controlled resistor network voltage divider 7 is respectively connected to the output terminal of the peak detection circuit 6 , the fixed voltage regulator terminal Z1 , and the output terminal of the bistable flip-flop 10 . The output terminal of the digitally controlled resistor network voltage divider 7 is connected to the input terminal of the transconductance amplifier circuit 2, the bistable trigger 10 is respectively connected to the monostable trigger 11 and the RS trigger, and the transistor T2 is connected to the relay Js, and the monostable trigger Devices 1 and 1 are respectively connected to RS flip-flop 12 and connected to another relay Ja through another triode T1.

According to the principle of eddy current detection, the center of the sensor coil passes through different media, such as molten steel or slag, and its impedance will change. When a sinusoidal current with a stable amplitude flows through the sensor coil, its terminal voltage will change accordingly. In Fig. 1, the sinusoidal voltage generated by the sine wave oscillator 1 outputs a sinusoidal current through the transconductance amplifier circuit 2, and flows into the sensor 5 through the shielded twin-core cable 3 and high-temperature connector 4 of tens of meters (normally closed contact Js when the sensor is working) in the "on" state). The voltage at point b in the figure is the sensor terminal voltage, and the output of the peak detection circuit 6 is the envelope of its input amplitude modulation voltage. Since the change of the envelope voltage is extremely small during the normal steel pouring period of the sensor, it can be roughly regarded as constant. The digitally controlled resistor network voltage divider 7 accepts the control from d, e voltage and j pulse, and outputs the control voltage at f point to control the output current amplitude of 2, so that the d point voltage is approximately equal to the regulated voltage value of the Zener tube Z1. The voltage at point d is filtered and amplified by circuit 8 to suppress the DC component and various electromechanical interferences in the envelope voltage. Therefore, during the normal pouring period, its output becomes a voltage signal with weak fluctuations around zero level. At the end of pouring steel, once the slag is dropped, the voltage at point d increases the changing voltage at the moment of steel slag transformation. Due to the high gain characteristic of the filter amplifier circuit 8, an accurate slag outflow signal is obtained, and its amplitude will exceed that from the potentiometer W1 The threshold voltage of point h of the set voltage comparator circuit 9 results in that the voltage comparator circuit 9 immediately outputs a slag lowering pulse. The i-point pulse triggers the bistable flip-flop 10 , and its output m-point pulse triggers the monostable flip-flop 11 . Then, 11 outputs k-point pulse to saturate transistor T1, relay Ja is energized, normally open contact Ja is closed, and the connector 13 is connected to the electric bell to alarm, and the connector 14 is connected to the sliding nozzle to automatically close the bag, and the alarm time is equal to the monostable pulse width. The k-point pulse also triggers the RS flip-flop 12 to cut off the transistor T2, the relay Js is powered off, and the normally closed contact Js is closed. go. One end of the button K1 is connected to the negative power supply VEE1. After each ladle is poured, first plug in the plug of the connector 4 of the sensor 5, and then press K1 to generate a negative pulse at point i, which is used to trigger the bistable circuit 10. Its One output of point j triggers the RS flip-flop 12 to saturate the transistor T2, the relay Js is energized, the normally closed contact Js is opened, and the sensor is normally connected to the device. The other output of point j triggers the digitally controlled resistor network voltage divider 7 to automatically adjust the output current amplitude of the transconductance amplifier circuit 2 . When the adjustment reaches the set value, the device enters the normal detection state.

The transconductance amplifier circuit is shown in Figure 2, including a voltage-controlled amplifier composed of operational amplifier A1 and field effect transistors T3 and T4, a transconductance amplifier composed of operational amplifiers A2 and A3 and transistors T5-T8, and a transconductance amplifier composed of operational amplifier A4. The difference amplifier composed of phase amplifier and operational amplifier A5.

In the figure, op amp A1 forms a voltage-controlled amplifier. Here, FET T3 is a voltage-controlled variable resistor controlled by the negative level output by op amp A5. The change of the output level of op amp A5 will control the The gain of the composed voltage controlled amplifier. The transconductance amplifier composed of operational amplifiers A2, A3 and transistors T5-T8 converts the sinusoidal voltage into a sinusoidal current, which flows to the sensor 5 and the sampling resistor R1 in Figure 1 through the output terminal b. Since the resistance R1 remains unchanged, the voltage amplitude at point c of the input terminal of the inverting amplifier composed of op amp A4 is proportional to the output current at point b. After being amplified by op amp A4 and peak detection by diode D1, it is input into the op amp simultaneously with the DC voltage at point f. The amplifier A5 performs their difference amplification, and the operational amplifier A5 outputs a negative level to adjust the drain-source resistance of the field effect transistor T3, thereby adjusting the current amplitude output at point b. Therefore, when the circuit components are timed, the output current amplitude at point b depends on the input level at point f.

The peak detection circuit is shown in Figure 3, including a voltage follower composed of operational amplifier A6, a frequency selective amplifier composed of operational amplifier A7, inductor L1, and capacitor C1, a peak detector composed of diode D2, capacitor C2, and resistor R2, and an operational amplifier. Put the voltage follower composed of A8.

In the figure, the operational amplifier A6 is a voltage follower, and the input terminal b is the voltage of the sensor terminal, and its characteristic is the amplitude modulation wave modulated by the slag signal detected by the sensor. The operational amplifier A7 forms a frequency-selective amplifier, which suppresses the interference outside the passband while passing the carrier signal. After peak detection by the diode D2, the envelope voltage of the amplitude modulation wave is output by the voltage follower A8. During normal pouring, this voltage is basically stable.

The digitally controlled resistive network voltage divider is shown in Figure 4, including a voltage comparator composed of an operational amplifier A9, a two-stage NAND gate N1 and a differential circuit, an RS flip-flop composed of an NOR gate O1, and an optional NAND gate N2. Controlling the start/stop oscillator, the binary addition counter COUN1 and its output are connected to the four-way bidirectional switch SW1, and the other is connected to the four-way bidirectional switch SW2 through the four-NAND gate N3.

When the sensor is connected and the button K1 is pressed, the point j rises to a positive level, and after passing through the two-stage NAND gate N1 and the differential circuit, a positive sharp pulse corresponding to the rising edge of the j terminal is obtained, which is triggered by the diode D4 or not. The 1 terminal of the RS flip-flop composed of the gate O1 keeps the output of the NOR gate O1 at a high level, and this high level is added to the control of the controllable start/stop oscillator composed of the NAND gate N2 through the diode D4 terminal to keep it oscillating. The forward sharp pulse corresponding to the rising edge of the terminal j clears the binary addition counter COUN1 through the diode D5, and then starts to count the number of pulses sent from the oscillator N2 input from the CL terminal, counting from binary 0000 to 1111, a total of 16. The counting is output by Q1~Q4 terminals, one way through the four-way switch SW1 to control whether the four series resistors above the point f are short-circuited, and the other way through the four-NAND gate N3 and the four-way switch SW2 to check whether the four series resistors below the point f are short-circuited for the opposite control. There are 10 series resistors in the resistor network, except for the top resistor and the ground resistor at the bottom, there are 8 controlled resistors. The top of the resistor network is added with the stable voltage of the voltage regulator tube Z3, and 16 kinds of voltage division ratios can be obtained at the midpoint f on the resistor network. When the counting state is 0000, the four resistors above point f are all valid, and the four resistors below point f are all short-circuited, and the voltage at point f is the lowest; when the counting state is 1111, the four resistors above point f are all short-circuited , the four resistors below point f are all effective, and the voltage at point f is the highest at this time. Thus, at the midpoint f on the resistor network, 16 step voltages starting from a certain voltage are obtained as the control voltage of the circuit in Figure 2. As the voltage at point f increases, the amplitude of the sensor excitation current increases, and the level at point d increases. When the level at point d is higher than the set level at point e, the voltage comparator A9 outputs a high level, and after the voltage regulator tube Z2 limits, the two-stage NAND gate N1, and the differential circuit, the voltage corresponding to the voltage comparator A9 is obtained. The sharp pulse of the rising edge of the output terminal triggers the 0 terminal of the RS flip-flop composed of the NOR gate O1 through the diode D3, so that the output of the NOR gate O1 is kept at a low level, and this low level makes the diode D6 cut off, and the NAND gate The controllable start/stop oscillator composed of N2 maintains the stop vibration state. Oscillator stops vibrating to indicate that the excitation source adjustment procedure has been completed. In fact, blocks 2, 6, 7 and the attached components in Fig. 1 form a negative feedback loop, which is one of the key technologies of the device of the present invention.

The filter amplifier circuit is shown in Figure 5, including a non-inverting amplifier composed of operational amplifier A10, a two-stage low-pass filter amplifier composed of operational amplifier A11 and operational amplifier A13, and a limiting amplifier composed of operational amplifier A12.

The envelope voltage is input from d, and then input to the non-inverting amplifier composed of operational amplifier A10 after DC blocking by the capacitor. The variation component contained in the envelope voltage is output from the output terminal g after passing through the non-inverting amplifier, the low-pass filter amplifier and the limiting amplifier. Once the slag flows out, a slag outflow signal with a sufficiently large amplitude is obtained at the g end. Connector 15 (see Fig. 1) is also drawn from point g, connected to the microcomputer data acquisition card, and the detected waveform is recorded, stored, historically recalled and printed in real time. The filtering effect of the circuit and the shielding process minimize various interferences, ensuring high reliability of the device.

The voltage comparator circuit is shown in Figure 6, including a voltage follower composed of operational amplifier A14, a voltage comparator composed of operational amplifier A15 and a switch circuit composed of two transistors.

The amplified useful signal, that is, the slag outflow signal, is compared with the set threshold voltage of point h after passing through the voltage follower. When the level at point g is higher than the level at point h, the voltage comparator outputs a high level, and the output terminal i outputs a high level through the two-stage transistor switch circuit, and the rising edge of this high level triggers the bistable state in Figure 1 The circuit 10 then drives the relevant relays to work to realize the logic conversion of the circuit state of the whole device. Obviously, there is no signal delay in this circuit, which ensures the accuracy of the slag signal. Adjusting the potentiometer W1 in Figure 1 to change the potential at point h can adjust the amount of slag flowing out to meet the requirements of steel production.

The operational amplifiers used in this device are all high-impedance operational amplifiers 3140, and the models of other integrated circuits have been marked in the circuit diagrams.

Because it has automatic operation function, the embodiment of the present invention is extremely simple, narrates as follows (referring to Fig. 1):

Power on and warm up for more than half an hour before operation. After the steel ladle equipped with the sensor 5 is in place at the steel pouring position and poured, the plug on the cable 3 is inserted into the high temperature connector 4 on the steel ladle shell. Press the button K1 once, the short-circuit contact Js is disconnected, the sensor is connected to the circuit, and enters the adjustment state, so that the connected sensor and the circuit are coordinated and adapted to each other. After the adjustment is completed, the device enters the normal detection state and operates according to the set current and voltage values. The microcomputer records the signal curve that fluctuates slightly around the zero level, and continues to the end of steel pouring. Once the slag flows out, the computer records the slag outflow signal, the alarm alarms, the sliding nozzle closes the ladle, and the steel pouring ends. At the same time, the contact Js is closed, the cable connector plug is pulled out from the ladle, and the empty ladle leaves. The next test is performed after replacing the ladle to be poured. The device can run continuously without power supply.

There are high-power steelmaking electric furnaces and various high-power electromechanical equipment near the present invention, so there are powerful mechanical and electrical interference sources. Even so, the present invention has not occurred the malfunction caused by external interference. Due to the rational design of the circuit as mentioned above, the slag signal can be detected accurately, and the steel output and the amount of slag dropped can uniformly meet the production requirements of continuous casting. In particular, the numerical control excitation source is used, and the detection effect has good repeatability when the sensor is replaced or the package age is detected.

The recorded curve is shown in Figure 7, and the pulse signal in the figure shows the slag outflow signal. As soon as this signal appears, the relay contact Js is closed immediately, the sensor circuit is short-circuited, and the level at point g immediately returns to zero level, and then the recorded curve becomes a horizontal line and remains at zero level.

Claims (2)

1. The device for obtaining the slag outflow signal during the ladle pouring process, which is characterized in that it includes: a sine wave oscillator [1], a transconductance amplifier circuit [2], a peak detection circuit [6], and a digitally controlled resistor network voltage divider [7], filter amplifier circuit [8], voltage comparison circuit [9], bistable trigger [10], monostable trigger [11], RS flip-flop [12], relay; sine wave oscillator [ The output of 1] is connected to the sensor [5] through the transconductance amplifier circuit [2], the twin-core cable [3], the high temperature connector [4], and the output of the transconductance amplifier circuit [2] is passed through the peak detection circuit [6], The filter amplifier circuit [8] is connected to the voltage comparison circuit [9], the input terminal of the voltage comparison circuit [9] is also connected to the adjustable positive potential, the output terminal is connected to the negative potential and the bistable trigger [10] through the button, and the numerically controlled resistor The input of the network voltage divider [7] is respectively connected to the output end of the peak detection circuit [6], the fixed voltage regulator end, the output end of the bistable flip-flop [10], and the output end of the digitally controlled resistor network voltage divider [7] Connect the input terminal of the transconductance amplifier circuit [2], the bistable trigger [10] is respectively connected to the monostable trigger [11] and the RS trigger [12], the triode [T2] is connected to the relay [Js]. The steady-state trigger [11] is respectively connected to the RS trigger [12] and connected to another relay [Ja] through another triode [T1]. 2. The device for obtaining the slag outflow signal in the ladle pouring process according to claim 1, characterized in that: 1) The transconductance amplifier circuit [2] includes a voltage-controlled amplifier composed of an operational amplifier [A1] and a field effect transistor [T3, T4], and a transconductance amplifier composed of an operational amplifier [A2, A3] and a transistor [T5-T8] , the inverting amplifier composed of the operational amplifier [A4] and the difference amplifier composed of the operational amplifier [A5]; 2) Peak detection circuit [6]: including voltage follower composed of operational amplifier [A6], frequency selective amplifier composed of operational amplifier [A7], inductor [L1] and capacitor [C1], diode [D2], capacitor [ C2], a peak detector composed of a resistor [R2] and a voltage follower composed of an operational amplifier [A8]; 3) Digitally controlled resistor network voltage divider [7]: including a voltage comparator composed of an operational amplifier [A9], a two-stage NAND gate [N1] and a differential circuit, an RS flip-flop composed of an NOR gate [O1], and A controllable start/stop oscillator composed of a NOT gate [N2], a binary plus counter [COUN1] and its output are connected to a four-way switch [SW1], and the other is connected to a four-way switch [SW1] through a four-NAND gate [N3] SW2]; 4) The filter amplifier circuit [8], including the non-inverting amplifier composed of the operational amplifier [A10], the two-stage low-pass filter amplifier composed of the operational amplifier [A11], the operational amplifier [A13] and the limiter composed of the operational amplifier [A12] amplifier; 5) Voltage comparator circuit [9], including a voltage follower composed of an operational amplifier [A14], a voltage comparator composed of an operational amplifier [A15] and a switch circuit composed of two transistors.

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