Control system and method for accurate positioning of oxygen lance

Abstract

The invention discloses a control system and method for accurate positioning of an oxygen lance. The control system comprises a PLC control unit, an oxygen lance frequency converter, an oxygen lance variable frequency motor, a speed encoder, a position encoder and a calibration sensor. The PLC control unit converts the feedback code value of the position encoder into the actual position value of the oxygen lance, calculates the deviation between the actual position value and the target position value, processes the deviation, generates a control command and sends the control command to the oxygen lance frequency converter. And the oxygen lance frequency converter directly drives the oxygen lance variable frequency motor to act and receives a feedback signal of the speed encoder. The oxygen lance variable frequency motor serves as an executing mechanism to drag the gun barrel to act. The speed encoder is used for measuring the rotating speed of the oxygen lance variable frequency motor and feeding back to the oxygen lance frequency converter. The position encoder is used for detecting the actual position of the oxygen lance and feeding back a code value. The calibration sensor generates a signal to the PLC control unit, and the actual position value of the oxygen lance is corrected. According to the invention, speed and position double-closed-loop of oxygen lance position control can be realized, and accurate positioning of the oxygen lance position can be achieved.

Description

Technical Field

[0001] The present invention relates to the technical field of converter steelmaking, and in particular to a control system and method for precise positioning of an oxygen lance. Background Art

[0002] The oxygen lance is a core component of the converter. Throughout the converter smelting process, lance position is crucial and crucial for controlling the steelmaking process. Accurate lance position control impacts steelmaking efficiency, molten steel quality, cost and energy consumption, equipment lifespan, and pollutant emissions. Precise lance position control is a fundamental requirement for oxygen step control in the later-developed secondary smelting model.

[0003] The converter oxygen lance positioning control process is complex, involves numerous interlocking protections, and results in crude manual positioning. Lance position is a critical control parameter in the steelmaking and slag-making process. Proper lance position control is crucial for reducing the frequency of molten steel splashing and back-drying, and for improving steel quality. Currently, most oxygen lances are positioned manually using a crank. This involves manual intervention based on lance height feedback from the operator interface, creating uncertainty and making positioning unreliable, unstable, and accurate. Modern converter steelmaking requires the oxygen lance to automatically adjust its position based on the oxygen blow rate. The accuracy of lance position during the blowing process impacts both the smelting cycle and the quality of the finished product. Summary of the Invention

[0004] The purpose of the present invention is to provide a control system and method for precise positioning of an oxygen lance, which can achieve precise positioning of the oxygen lance through perfect hardware design and software processing, so as to solve the problems raised by the above background technology.

[0005] To achieve the above object, the present invention provides the following technical solutions:

[0006] A control system for precise oxygen lance positioning includes a PLC control unit, an oxygen lance frequency converter, an oxygen lance variable frequency motor, a speed encoder, a position encoder, and a calibration sensor. The PLC control unit is installed in a PLC room and is connected to the oxygen lance frequency converter in a low-voltage distribution room and an on-site position encoder via optical fiber. The oxygen lance frequency converter is installed in a low-voltage cabinet in a low-voltage power distribution room and is equipped with an Ethernet adapter module FENA-01 and a pulse encoder interface module FEN-31. The FENA-01 is connected to a Siemens CPU1517PN / DP, and the FEN-31 is connected to a speed encoder module. The oxygen lance variable frequency motor is installed on the highest platform of the steelmaking workshop converter equipment and is driven by a reducer, a drum, a steel wire rope, and a movable pulley to move the oxygen lance barrel. The speed encoder is installed on the drive shaft of the oxygen lance variable frequency motor. The position encoder is installed on the shaft diameter of the oxygen lance drum and is connected to the Siemens CPU1517PN / DP via optical fiber. The calibration sensor is installed at the lance change position.

[0007] The PLC control unit is used to obtain the feedback code value of the position encoder and calculate the actual position value of the oxygen gun. The speed setting value is calculated based on the deviation between the actual position value and the target position value, and the control command is sent to the oxygen gun frequency converter. When the PLC control unit receives the calibration sensor signal, it automatically calibrates the actual position value of the oxygen gun.

[0008] When the oxygen gun inverter receives the control command from the PLC control unit, it drives the oxygen gun variable frequency motor to operate and monitors the operating status of the oxygen gun variable frequency motor according to the feedback value of the speed encoder;

[0009] The oxygen gun frequency conversion motor is used as the actuator to drag the gun barrel up and down through the reducer, drum and wire rope, and a speed encoder is installed on the transmission shaft;

[0010] The speed encoder uses an incremental encoder as a detection device for the speed of the oxygen gun frequency conversion motor, and feeds back the code value to the oxygen gun frequency converter;

[0011] The position encoder uses a multi-turn absolute encoder to detect the actual position of the oxygen gun and feed back the code value to the PLC control unit;

[0012] The calibration sensor serves as the base point of the relative position of the oxygen lance and is used to correct the deviation of the actual position value of the oxygen lance.

[0013] Furthermore, the position encoder feeds back a code value to the PLC control unit via the Profinet network.

[0014] Furthermore, each time the calibration sensor receives a calibration signal, the PLC control unit sets the oxygen gun position value to the highest point H0 and records the code value M0 of the current position encoder.

[0015] Furthermore, the PLC control unit calculates the actual position H of the oxygen lance according to the linear ratio of the code value increment to the oxygen lance position increment, and the formula is as follows:

[0016] H=H0-π*(2*r1+r2)*(M0-M1) / 2 N

[0017] Among them: r1 is the drum radius, r2 is the wire rope radius, M1 is the current feedback code value of the position encoder, and N is the number of bits of single-turn accuracy of the position encoder.

[0018] Furthermore, the PLC control unit sends a control command to the oxygen lance frequency converter via the Profinet network. The control command adopts a standard message including a control word and a speed setting.

[0019] Furthermore, the speed encoder is used to monitor the actual speed of the oxygen lance variable frequency motor and feed it back to the oxygen lance frequency converter. The oxygen lance frequency converter compares the speed feedback value with the set value to diagnose the operating status of the oxygen lance variable frequency motor.

[0020] Furthermore, the speed setting means being limited within the maximum speed of the oxygen lance variable frequency motor, and adopting segmented control according to the deviation between the actual value and the target value of the oxygen lance position.

[0021] Furthermore, the segmented control method is as follows: when the deviation value is greater than the set threshold, the oxygen gun motor runs at the highest speed; when the deviation value is less than the set threshold and greater than the set dead zone, the speed setting adopts proportional control, and the speed setting is calculated by multiplying a certain coefficient by the deviation value; when the deviation value is less than the set dead zone value, the oxygen gun motor stops running.

[0022] The present invention provides another technical solution: a control method for precise positioning of an oxygen lance, comprising the following steps:

[0023] S1: The operator sets a target value for the oxygen gun position on the operation interface of the PLC control unit and sends a start command to the PLC control unit;

[0024] S2: The PLC control unit calculates the real-time position value of the oxygen gun according to the calculation formula, compares the real-time position value with the target value, and calculates the deviation value;

[0025] S3: The PLC control unit sends the control word and speed setting word to the oxygen gun inverter through the standard message ST1, and receives the status word and speed feedback word fed back by the oxygen gun inverter at the same time;

[0026] S4: When the deviation value is greater than the set threshold, the oxygen gun variable frequency motor runs at the highest speed. When the deviation value is less than the set threshold and greater than the set dead zone, the speed setting adopts proportional control, and the speed setting is calculated by multiplying the deviation value by a certain coefficient; when the deviation value is less than the set dead zone value, the oxygen gun variable frequency motor stops running.

[0027] Furthermore, during the operation of the oxygen lance variable frequency motor, the actual speed of the oxygen lance variable frequency motor is monitored by the speed encoder and fed back to the oxygen lance frequency converter. The oxygen lance frequency converter compares the speed feedback value with the set value to diagnose the operating status of the oxygen lance variable frequency motor. When the difference is greater than the threshold, an error signal is fed back to the PLC control unit.

[0028] Compared with the prior art, the present invention has the following beneficial effects:

[0029] The control system and method for precise positioning of the oxygen lance of the present invention realizes closed-loop speed control of the oxygen lance variable frequency motor through a speed encoder, and realizes closed-loop control of the actual position of the oxygen lance through a position encoder. The perfect hardware design and software processing can realize precise positioning of the oxygen lance gun position. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 This is a block diagram of the system unit module of the present invention. DETAILED DESCRIPTION

[0031] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0032] See also Figure 1In an embodiment of the present invention, a control system for precise positioning of an oxygen lance is provided, comprising a PLC control unit, an oxygen lance frequency converter, an oxygen lance frequency conversion motor, a speed encoder, a position encoder, and a calibration sensor; the PLC control unit is a Siemens CPU1517 PN / DP and ET200MP slave station, which is installed in the PLC room and connected to the oxygen lance frequency converter in the low-voltage distribution room and the on-site position encoder via an optical fiber; the oxygen lance frequency converter adopts an ABB ACS880 series frequency converter and is equipped with an Ethernet adapter module FENA-01 and a pulse encoder interface module FEN-31, which is installed in the low-voltage cabinet of the low-voltage distribution room, wherein FENA-01 is connected to the Siemens CPU1517 PN / DP, FEN-31 connected to the speed encoder module; the oxygen lance variable frequency motor is selected by the converter process designer based on the converter capacity and is installed on the highest platform of the converter equipment in the steelmaking workshop. It drags the oxygen lance barrel through a reducer, reel, wire rope, and movable pulley; the speed encoder uses the Pepperl+Fuchs ENI58IL series incremental encoder, which is installed on the drive shaft of the oxygen lance variable frequency motor; the position encoder uses the Pepperl+Fuchs ENA58IL series multi-turn absolute encoder, with a single-turn accuracy of 12 bits and a multi-turn bit number of 13 bits, supporting the Profinet network, installed on the shaft diameter of the oxygen lance reel, and connected to the Siemens CPU1517 PN / DP via optical fiber; the calibration sensor uses a high-temperature resistant Turck proximity switch, which feeds back digital signals to the digital DI module of the ET200MP, which is installed at the gun change position of the oxygen lance.

[0033] In an embodiment of the present invention, a PLC control unit is used to obtain the feedback code value of the position encoder, calculate the actual position value of the oxygen gun, calculate the speed given value based on the deviation between the actual position value and the target position value, and send a control command to the oxygen gun frequency converter. When the PLC control unit receives the calibration sensor signal, it automatically calibrates the actual position value of the oxygen gun; when the oxygen gun frequency converter receives the control command of the PLC control unit, it drives the oxygen gun frequency converter motor to operate and monitors the operating state of the oxygen gun frequency converter motor based on the feedback value of the speed encoder; the oxygen gun frequency converter motor serves as an actuator to drag the gun barrel up and down through a reducer, a drum, and a wire rope, and a speed encoder is installed on the transmission shaft; the speed encoder adopts an incremental encoder, As a device for detecting the speed of the oxygen lance variable frequency motor, it feeds back the code value to the oxygen lance frequency converter. Specifically, the speed encoder is used to monitor the actual speed of the oxygen lance variable frequency motor and feed it back to the oxygen lance frequency converter. The oxygen lance frequency converter compares the speed feedback value with the set value to diagnose the operating status of the oxygen lance variable frequency motor. The position encoder uses a multi-turn absolute encoder to detect the actual position of the oxygen lance and feeds back the code value to the PLC control unit through the Profinet network. The calibration sensor serves as the base point of the relative position of the oxygen lance and is used to correct the deviation of the actual position value of the oxygen lance. Each time the calibration sensor receives a calibration signal, the PLC control unit sets the oxygen lance position value to the highest point H0 and records the code value M0 of the current position encoder.

[0034] Specifically, the PLC control unit calculates the actual position H of the oxygen lance based on the linear ratio of the code value increment to the oxygen lance position increment. The calculation formula is as follows:

[0035] H=H0-π*(2*r1+r2)*(M0-M1) / 2 N

[0036] Among them: r1 is the drum radius, r2 is the wire rope radius, M1 is the current feedback code value of the position encoder, and N is the number of bits of single-turn accuracy of the position encoder.

[0037] In the above embodiment, the PLC control unit sends a control command to the oxygen lance frequency converter via the Profinet network. The control command adopts a standard message, including a control word and a speed setting. The speed setting refers to limiting the maximum speed of the oxygen lance frequency converter motor, and adopts segmented control according to the deviation between the actual value and the target value of the oxygen lance position. When the deviation value is greater than the set threshold, the oxygen lance motor runs at the maximum speed. When the deviation value is less than the set threshold and greater than the set dead band, the speed setting adopts proportional control, and the speed setting is calculated by multiplying the deviation value by a certain coefficient. When the deviation value is less than the set dead band value, the oxygen lance motor stops running.

[0038] In order to further better explain the embodiments of the present invention, a control method for precise positioning of an oxygen lance is also provided, comprising the following steps:

[0039] S1: The operator clicks on the desired position point for the oxygen lance on the operation interface of the PLC control unit. Common oxygen lance positions include the lance change position, waiting position, blowing position, and lowest point. The operation interface also includes 5cm and 10cm step operations, which means the current lance position rises or falls to a specified height. This is generally used to fine-tune the lance position during the blowing process. Regardless of whether the position point is selected or the step control is used, a target value for the oxygen lance position is set and a start command is sent to the PLC control unit.

[0040] S2: The PLC control unit is constantly calculating the oxygen gun real-time position value. The calculation formula is as follows:

[0041] H=H0-π*(2*r1+r2)*(M0-M1) / 2 N+1

[0042] Among them: r1 is the drum radius, r2 is the wire rope radius, M1 is the current feedback code value of the position encoder, N is the number of bits of single-turn accuracy of the position encoder, and the transmission passes through the movable pulley, so it is divided by 2;

[0043] The PLC control unit calculates the deviation value based on the comparison between the target value and the actual value;

[0044] S3: The PLC control unit sends the control word and speed setting word to the oxygen gun inverter through the standard message ST1, and receives the status word and speed feedback word fed back by the oxygen gun inverter at the same time;

[0045] S4: When the deviation value is greater than the set threshold, the oxygen gun variable frequency motor runs at the highest speed. When the deviation value is less than the set threshold and greater than the set dead zone, the speed setting adopts proportional control, and the speed setting is calculated by multiplying a certain coefficient by the deviation value. When the deviation value is less than the set dead zone value, the oxygen gun variable frequency motor stops running. During the operation of the oxygen gun variable frequency motor, the actual speed of the oxygen gun variable frequency motor is monitored by the speed encoder and fed back to the oxygen gun frequency converter. The oxygen gun frequency converter compares the speed feedback value with the set value to diagnose the operating status of the oxygen gun variable frequency motor. When the difference is greater than the threshold, an error signal is fed back to the PLC control unit.

[0046] In summary: The present invention provides a control system and method for precise positioning of an oxygen lance. The PLC control unit converts the feedback code value of the position encoder into the actual position value of the oxygen lance and calculates the deviation from the target position value. The control command is generated and sent to the oxygen lance frequency converter. The oxygen lance frequency converter directly drives the oxygen lance frequency converter motor to move and receives the feedback signal of the speed encoder. The oxygen lance frequency converter serves as an actuator to drag the gun barrel to move. The speed encoder is used to measure the rotation speed of the oxygen lance frequency converter motor and feed it back to the oxygen lance frequency converter. The position encoder is used to detect the actual position of the oxygen lance, feed back the code value, and calibrate the sensor to generate a signal to the PLC control unit to correct the actual position value of the oxygen lance. The entire invention realizes closed-loop speed control of the oxygen lance frequency converter motor through the speed encoder and closed-loop control of the actual position of the oxygen lance through the position encoder. The perfect hardware design and software processing can realize precise positioning of the oxygen lance gun position.

[0047] The above description is only a preferred specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any technician familiar with the technical field, within the technical scope disclosed by the present invention, who makes equivalent replacements or changes based on the technical solution and inventive concept of the present invention, should be covered by the scope of protection of the present invention.

Claims

1. A control system for precise positioning of an oxygen lance, characterized in that: It includes a PLC control unit, an oxygen gun frequency converter, an oxygen gun frequency conversion motor, a speed encoder, a position encoder and a calibration sensor; the PLC control unit is installed in the PLC room, and is connected to the oxygen gun frequency converter in the low-voltage distribution room and the on-site position encoder through optical fiber; the oxygen gun frequency converter is installed in the low-voltage cabinet of the low-voltage power distribution room, and is equipped with an Ethernet adapter module FENA-01 and a pulse encoder interface module FEN-31, wherein FENA-01 is connected to Siemens CPU1517 PN / DP, and FEN-31 is connected to the speed encoder module; the oxygen gun frequency conversion motor is installed on the highest platform of the converter equipment in the steelmaking workshop, and the oxygen gun barrel is dragged by a reducer, a drum, a wire rope and a movable pulley; the speed encoder is installed on the driving shaft of the oxygen gun frequency conversion motor; the position encoder is installed on the shaft diameter of the oxygen gun drum, and is connected to Siemens CPU1517PN / DP through optical fiber; the calibration sensor is installed at the gun change position of the oxygen gun; Among them, the PLC control unit is used to obtain the feedback code value of the position encoder, calculate the actual position value of the oxygen gun, calculate the speed setting value according to the deviation between the actual position value and the target position value, and send a control command to the oxygen gun frequency converter. When the PLC control unit receives the calibration sensor signal, it automatically calibrates the actual position value of the oxygen gun; When the oxygen gun inverter receives the control command from the PLC control unit, it drives the oxygen gun inverter motor to operate and monitors the operating state of the oxygen gun inverter motor according to the feedback value of the speed encoder; The oxygen gun variable frequency motor is used as the actuator to drag the gun barrel up and down through the reducer, drum and wire rope, and a speed encoder is installed on the transmission shaft; The speed encoder uses an incremental encoder as a detection device for the speed of the oxygen gun frequency conversion motor, and feeds back the code value to the oxygen gun frequency converter; The position encoder uses a multi-turn absolute encoder to detect the actual position of the oxygen gun and feed back the code value to the PLC control unit; The calibration sensor is used as the base point of the relative position of the oxygen lance to correct the deviation of the actual position value of the oxygen lance.

2. A control system for precise positioning of an oxygen lance as claimed in claim 1, characterized in that: The position encoder feeds back a code value to the PLC control unit via the Profinet network.

3. A control system for precise positioning of an oxygen lance as claimed in claim 1, characterized in that: Each time the calibration sensor receives a calibration signal, the PLC control unit sets the oxygen gun position value to the highest point H0 and records the code value M0 of the current position encoder.

4. A control system for precise positioning of an oxygen lance as claimed in claim 3, characterized in that: The PLC control unit calculates the actual position H of the oxygen lance according to the linear ratio of the code value increment and the oxygen lance position increment, and the formula is as follows: H=H0-π*(2*r1+r2)*(M0-M1) / 2 N Among them: r1 is the drum radius, r2 is the wire rope radius, M1 is the current feedback code value of the position encoder, and N is the number of digits of the single-turn accuracy of the position encoder.

5. A control system for precise positioning of an oxygen lance as claimed in claim 1, characterized in that: The PLC control unit sends a control command to the oxygen gun frequency converter via the Profinet network. The control command adopts a standard message including a control word and a speed setting.

6. A control system for precise positioning of an oxygen lance as claimed in claim 1, characterized in that: The speed encoder is used to monitor the actual speed of the oxygen lance variable frequency motor and feed it back to the oxygen lance frequency converter. The oxygen lance frequency converter compares the feedback value of the speed with the set value to diagnose the operating status of the oxygen lance variable frequency motor.

7. A control system for precise positioning of an oxygen lance as claimed in claim 5, characterized in that: The speed setting refers to limiting the maximum speed of the oxygen lance variable frequency motor, and adopting segmented control according to the deviation between the actual value and the target value of the oxygen lance position.

8. A control system for precise positioning of an oxygen lance as claimed in claim 7, characterized in that: The segmented control method is as follows: when the deviation value is greater than the set threshold, the oxygen gun motor runs at the highest speed; when the deviation value is less than the set threshold and greater than the set dead zone, the speed setting adopts proportional control, and the speed setting is calculated by multiplying a certain coefficient by the deviation value; when the deviation value is less than the set dead zone value, the oxygen gun motor stops running.

9. A control method for accurate positioning of an oxygen lance, implemented based on the control system for accurate positioning of an oxygen lance according to claim 1, characterized in that: The following steps are involved: S1: The operator sets a target value for the oxygen gun position on the operation interface of the PLC control unit and sends a start command to the PLC control unit; S2: The PLC control unit calculates the real-time position value of the oxygen gun according to the calculation formula, compares the real-time position value with the target value, and calculates the deviation value; S3: The PLC control unit sends the control word and speed setting word to the oxygen gun inverter through the standard message ST1, and receives the status word and speed feedback word fed back by the oxygen gun inverter at the same time; S4: When the deviation value is greater than the set threshold, the oxygen gun variable frequency motor runs at the highest speed. When the deviation value is less than the set threshold and greater than the set dead zone, the speed setting adopts proportional control, and the speed setting is calculated by multiplying the deviation value by a certain coefficient; when the deviation value is less than the set dead zone value, the oxygen gun variable frequency motor stops running.

10. A control method for accurate positioning of an oxygen lance as claimed in claim 9, characterized in that: During the operation of the oxygen gun variable frequency motor, the actual speed of the oxygen gun variable frequency motor is monitored by the speed encoder and fed back to the oxygen gun frequency converter. The oxygen gun frequency converter compares the feedback value of the speed with the set value to diagnose the operating status of the oxygen gun variable frequency motor. When the difference is greater than the threshold, an error signal is fed back to the PLC control unit.

Images