CN114433805B - Method, device and system for measuring liquid level of molten steel in tundish - Google Patents
Method, device and system for measuring liquid level of molten steel in tundish Download PDFInfo
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- CN114433805B CN114433805B CN202210363508.2A CN202210363508A CN114433805B CN 114433805 B CN114433805 B CN 114433805B CN 202210363508 A CN202210363508 A CN 202210363508A CN 114433805 B CN114433805 B CN 114433805B
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- 239000010959 steel Substances 0.000 title claims abstract description 385
- 239000007788 liquid Substances 0.000 title claims abstract description 175
- 238000000034 method Methods 0.000 title claims abstract description 77
- 238000010438 heat treatment Methods 0.000 claims abstract description 69
- 230000008569 process Effects 0.000 claims abstract description 19
- 230000004044 response Effects 0.000 claims abstract description 10
- 230000008859 change Effects 0.000 claims description 26
- 238000010891 electric arc Methods 0.000 claims description 24
- 238000005303 weighing Methods 0.000 claims description 16
- XKRFYHLGVUSROY-UHFFFAOYSA-N Argon Chemical compound [Ar] XKRFYHLGVUSROY-UHFFFAOYSA-N 0.000 claims description 12
- 238000004364 calculation method Methods 0.000 claims description 12
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 claims description 10
- 239000007789 gas Substances 0.000 claims description 9
- 229910002804 graphite Inorganic materials 0.000 claims description 8
- 239000010439 graphite Substances 0.000 claims description 8
- 229910052786 argon Inorganic materials 0.000 claims description 6
- 238000004590 computer program Methods 0.000 claims description 6
- 238000009851 ferrous metallurgy Methods 0.000 abstract description 2
- 239000000463 material Substances 0.000 description 7
- 238000005266 casting Methods 0.000 description 6
- 238000009749 continuous casting Methods 0.000 description 6
- 239000002893 slag Substances 0.000 description 4
- 238000002474 experimental method Methods 0.000 description 3
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- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 description 2
- 229910052799 carbon Inorganic materials 0.000 description 2
- 238000007796 conventional method Methods 0.000 description 2
- 238000009826 distribution Methods 0.000 description 2
- 230000000694 effects Effects 0.000 description 2
- 230000003628 erosive effect Effects 0.000 description 2
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- 238000005259 measurement Methods 0.000 description 2
- 230000002035 prolonged effect Effects 0.000 description 2
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- XUIMIQQOPSSXEZ-UHFFFAOYSA-N Silicon Chemical compound [Si] XUIMIQQOPSSXEZ-UHFFFAOYSA-N 0.000 description 1
- 238000003723 Smelting Methods 0.000 description 1
- 238000010521 absorption reaction Methods 0.000 description 1
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- 150000002500 ions Chemical class 0.000 description 1
- 238000002844 melting Methods 0.000 description 1
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B22—CASTING; POWDER METALLURGY
- B22D—CASTING OF METALS; CASTING OF OTHER SUBSTANCES BY THE SAME PROCESSES OR DEVICES
- B22D11/00—Continuous casting of metals, i.e. casting in indefinite lengths
- B22D11/16—Controlling or regulating processes or operations
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B22—CASTING; POWDER METALLURGY
- B22D—CASTING OF METALS; CASTING OF OTHER SUBSTANCES BY THE SAME PROCESSES OR DEVICES
- B22D11/00—Continuous casting of metals, i.e. casting in indefinite lengths
- B22D11/10—Supplying or treating molten metal
- B22D11/11—Treating the molten metal
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B22—CASTING; POWDER METALLURGY
- B22D—CASTING OF METALS; CASTING OF OTHER SUBSTANCES BY THE SAME PROCESSES OR DEVICES
- B22D2/00—Arrangement of indicating or measuring devices, e.g. for temperature or viscosity of the fused mass
- B22D2/003—Arrangement of indicating or measuring devices, e.g. for temperature or viscosity of the fused mass for the level of the molten metal
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B22—CASTING; POWDER METALLURGY
- B22D—CASTING OF METALS; CASTING OF OTHER SUBSTANCES BY THE SAME PROCESSES OR DEVICES
- B22D41/00—Casting melt-holding vessels, e.g. ladles, tundishes, cups or the like
- B22D41/005—Casting melt-holding vessels, e.g. ladles, tundishes, cups or the like with heating or cooling means
- B22D41/01—Heating means
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01B—MEASURING LENGTH, THICKNESS OR SIMILAR LINEAR DIMENSIONS; MEASURING ANGLES; MEASURING AREAS; MEASURING IRREGULARITIES OF SURFACES OR CONTOURS
- G01B11/00—Measuring arrangements characterised by the use of optical techniques
- G01B11/02—Measuring arrangements characterised by the use of optical techniques for measuring length, width or thickness
- G01B11/06—Measuring arrangements characterised by the use of optical techniques for measuring length, width or thickness for measuring thickness ; e.g. of sheet material
- G01B11/0608—Height gauges
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01F—MEASURING VOLUME, VOLUME FLOW, MASS FLOW OR LIQUID LEVEL; METERING BY VOLUME
- G01F23/00—Indicating or measuring liquid level or level of fluent solid material, e.g. indicating in terms of volume or indicating by means of an alarm
- G01F23/22—Indicating or measuring liquid level or level of fluent solid material, e.g. indicating in terms of volume or indicating by means of an alarm by measuring physical variables, other than linear dimensions, pressure or weight, dependent on the level to be measured, e.g. by difference of heat transfer of steam or water
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01G—WEIGHING
- G01G17/00—Apparatus for or methods of weighing material of special form or property
- G01G17/04—Apparatus for or methods of weighing material of special form or property for weighing fluids, e.g. gases, pastes
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01K—MEASURING TEMPERATURE; MEASURING QUANTITY OF HEAT; THERMALLY-SENSITIVE ELEMENTS NOT OTHERWISE PROVIDED FOR
- G01K13/00—Thermometers specially adapted for specific purposes
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
- Y02P10/00—Technologies related to metal processing
- Y02P10/25—Process efficiency
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- Physics & Mathematics (AREA)
- Engineering & Computer Science (AREA)
- Mechanical Engineering (AREA)
- General Physics & Mathematics (AREA)
- Thermal Sciences (AREA)
- Fluid Mechanics (AREA)
- Casting Support Devices, Ladles, And Melt Control Thereby (AREA)
- Continuous Casting (AREA)
Abstract
The invention provides a method, a device and a system for measuring the liquid level of molten steel in a tundish, and relates to the technical field of ferrous metallurgy, wherein the method comprises the following steps: determining the target distance from the plasma electrode to the liquid level of molten steel in the tundish and the consumption speed of the plasma electrode; in response to receiving a control instruction for heating the molten steel in the tundish, controlling the mechanical arm to drive the bottom end of the plasma electrode to move to a target position above the liquid level of the molten steel; in the process of heating the molten steel, controlling the mechanical arm to move so that the plasma electrode heats the molten steel; determining a first liquid level height of the molten steel in real time according to a real-time voltage between the plasma electrode and the molten steel, a height difference between a real-time position and an initial position of the mechanical arm and a consumption speed of the plasma electrode; when the bottom end of the plasma electrode firstly passes through the ladle opening of the tundish, the initial position is the position of the mechanical arm. According to the scheme, the liquid level height of the molten steel in the tundish can be accurately calculated.
Description
Technical Field
The embodiment of the invention relates to the technical field of ferrous metallurgy, in particular to a method, a device and a system for measuring the liquid level of molten steel in a tundish.
Background
In the continuous casting process of steel production, the steel liquid level in the tundish is controlled to be stable, so that the quality of a steel billet product can be improved, the service life of the tundish is prolonged, and the slag rolling amount in the casting process is reduced. Therefore, the accurate measurement of the liquid level of the molten steel in the tundish is of great significance.
However, in the process of plasma heating of the tundish, the molten steel level of the tundish is generally obtained by a weighing method or a laser method, but the conventional weighing method cannot accurately obtain the molten steel level information due to the continuous erosion of the lining material of the tundish and the existence of the mold flux. And because the thickness distribution of the covering slag in the molten steel is not uniform, the accuracy of the method for calculating the liquid level of the molten steel by using laser or microwave to project the covering slag into the molten steel of the tundish and by the time difference between the incident light emission and the reflected light reception is difficult to ensure.
Therefore, the conventional method for measuring the molten steel level in the tundish cannot accurately obtain the molten steel level, and a new method for measuring the molten steel level in the tundish is urgently needed.
Disclosure of Invention
Based on the problem that the liquid level of molten steel cannot be accurately obtained by the conventional method for measuring the liquid level of molten steel in a tundish, the embodiment of the invention provides a method, a device and a system for measuring the liquid level of molten steel in a tundish, which can accurately calculate the liquid level of molten steel in the tundish.
The embodiment of the invention provides a method for measuring the liquid level of molten steel in a tundish, which comprises the following steps:
determining the target distance from the plasma electrode to the liquid level of molten steel in the tundish and the consumption speed of the plasma electrode;
in response to receiving a control instruction for heating the molten steel in the tundish, controlling the mechanical arm to drive the bottom end of the plasma electrode to move to a target position above the liquid level of the molten steel; wherein the distance from the target position to the liquid level of the molten steel is a target distance;
in the process of heating the molten steel, controlling the mechanical arm to move so that the plasma electrode heats the molten steel;
determining a first liquid level height of the molten steel in real time according to a real-time voltage between the plasma electrode and the molten steel, a height difference between a real-time position and an initial position of the mechanical arm and a consumption speed of the plasma electrode; when the bottom end of the plasma electrode firstly passes through the ladle opening of the tundish, the initial position is the position of the mechanical arm.
Preferably, the method further comprises the following steps: controlling a plasma electrode to generate a heating arc in response to receiving a control instruction for heating molten steel in the tundish;
the bottom that the control arm drove the plasma electrode moves to the target location who is located the liquid level top of molten steel, includes:
the control mechanical arm drives the plasma electrode to move downwards from the upper part of the liquid level of the molten steel;
when the voltage between the plasma electrode and the molten steel is zero, determining that the bottom end of the plasma electrode contacts the molten steel, and controlling the mechanical arm to stop descending;
and controlling the mechanical arm to ascend to the target position.
Preferably, after controlling the robot arm to drive the bottom end of the plasma electrode to move to the target position above the liquid level of the molten steel and before controlling the robot arm to move during the process of heating the molten steel, the method further comprises:
and determining the initial liquid level height of the molten steel according to the height difference between the position of the mechanical arm and the initial position when the voltage between the plasma electrode and the molten steel is zero and the height from the ladle opening of the tundish to the ladle bottom.
Preferably, the controlling of the movement of the robot arm comprises:
determining the voltage between the plasma electrode and the molten steel as a target voltage when the bottom end of the plasma electrode is positioned at a target position;
and controlling the mechanical arm to drive the plasma electrode to move according to the voltage change between the plasma electrode and the molten steel so as to keep the voltage between the plasma electrode and the molten steel at a target voltage.
Preferably, the controlling of the movement of the robot arm comprises:
calculating the second liquid level height of the molten steel in real time according to the weight of the molten steel in the tundish;
determining a second consumption length of the plasma electrode in a set time interval according to the consumption speed of the plasma electrode;
and adjusting the height of the plasma electrode in real time according to the change of the second liquid level height and the second consumption length of the plasma electrode so as to keep the distance from the bottom end of the plasma electrode to the liquid level of the molten steel at a target distance.
Preferably, the determining the first liquid level height of the molten steel in real time according to the real-time voltage between the plasma electrode and the molten steel, the height difference between the real-time position and the initial position of the mechanical arm, and the consumption speed of the plasma electrode includes:
calculating the length of an electric arc generated by the plasma electrode according to the real-time voltage between the plasma electrode and the molten steel;
determining the height difference between the real-time position of the mechanical arm and the initial position of the mechanical arm;
determining a first consumption length of the plasma electrode according to the consumption speed of the plasma electrode and the heating time of the plasma electrode;
and determining the first liquid level height of the molten steel in real time according to the length of an electric arc generated by the plasma electrode, the height difference between the real-time position and the initial position of the mechanical arm and the first consumption length of the plasma electrode.
Preferably, the controlling of the movement of the robot arm comprises:
and adjusting the height of the plasma electrode in real time according to the change of the first liquid level height of the molten steel and the second consumption length of the plasma electrode so as to keep the distance from the bottom end of the plasma electrode to the liquid level of the molten steel at a target distance.
Preferably, the calculation formula of the length of the arc generated by the plasma electrode is:
wherein,
for the length of the arc generated by the plasma electrode,
is the real-time voltage between the plasma electrode and the molten steel,
is the voltage drop of the plasma electrode before contacting the molten steel,
is the mean potential gradient.
Preferably, the calculation formula of the first liquid level height of molten steel is:
wherein,
is the first liquid level height of the molten steel,
the height from the opening of the tundish to the bottom of the tundish,
for the length of the arc generated by the plasma electrode,
the concave quantity of the liquid level of the molten steel when the electric arc impacts the molten steel,
the height difference between the real-time position of the mechanical arm and the initial position of the mechanical arm, v is the consumption speed of the plasma electrode, and t is the heating time of the plasma electrode.
In a second aspect, an embodiment of the present invention further provides a device for measuring a molten steel level in a tundish, including a memory and a processor, where the memory stores a computer program, and the processor executes the computer program to implement the method for measuring a molten steel level in a tundish according to any embodiment of this specification.
In a third aspect, an embodiment of the present invention further provides a system for measuring a molten steel level in a tundish, including:
the tundish is used for containing molten steel;
the plasma electrode is arranged above the tundish and used for ionizing plasma gas so as to heat the molten steel;
the two ends of the plasma generator are respectively connected with the plasma electrode and the molten steel and used for supplying power to the plasma electrode;
the bottom electrode is arranged at the bottom of the tundish, and two ends of the bottom electrode are respectively connected with molten steel and the plasma generator;
the mechanical arm is connected with the plasma electrode and is used for driving the plasma electrode to move;
the voltage sensor is arranged between the plasma electrode and the molten steel and is used for collecting the voltage between the plasma electrode and the molten steel in real time;
the photoelectric sensor is arranged at the ladle opening of the tundish and used for determining the initial position of the mechanical arm;
the temperature sensor is arranged in the molten steel and used for collecting the temperature of the molten steel in real time;
the weighing device is arranged at the bottom of the tundish and is used for weighing the molten steel in real time;
and the measuring device is electrically connected with the plasma generator, the mechanical arm, the voltage sensor, the photoelectric sensor, the temperature sensor and the weighing device respectively, and the measuring device is the measuring device in the second aspect of the specification.
Preferably, the plasma electrode is a graphite electrode and adopts a hollow structure; the plasma gas is argon and is introduced from the middle of the plasma electrode.
The embodiment of the invention provides a method for measuring the liquid level of molten steel in a tundish. According to the scheme, the liquid level height of the molten steel in the tundish can be accurately calculated.
Drawings
In order to more clearly illustrate the embodiments or technical solutions of the present invention, the drawings used in the embodiments or technical solutions in the prior art are briefly introduced below, and it is obvious that the drawings in the following description are some embodiments of the present invention, and it is obvious for those skilled in the art that other drawings can be obtained according to these drawings without creative efforts.
FIG. 1 is a flowchart of a method for measuring a molten steel level in a tundish according to an embodiment of the present invention;
FIG. 2 is a front view of a tundish configuration according to an embodiment of the invention;
FIG. 3 is a side view of a tundish structure provided in an embodiment of the invention;
FIG. 4 is a flow chart of another method for measuring the level of molten steel in a tundish according to an embodiment of the present invention;
FIG. 5 is a schematic view of a system for measuring a molten steel level in a tundish according to an embodiment of the present invention;
in the figure:
1. a tundish; 2. a plasma electrode; 3. a plasma generator; 4. a bottom electrode; 5. a mechanical arm; 6. A voltage sensor; 7. a photosensor; 8. an electrical cable.
Detailed Description
In order to make the objects, technical solutions and advantages of the embodiments of the present invention clearer and more complete, the technical solutions in the embodiments of the present invention will be described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are some, but not all, embodiments of the present invention, and based on the embodiments of the present invention, all other embodiments obtained by a person of ordinary skill in the art without creative efforts belong to the scope of the present invention.
As described above, the conventional weighing method and laser method cannot accurately measure the height of the molten steel level in the tundish due to the continuous erosion of the tundish lining material and the presence of mold flux having non-uniform thickness distribution. Therefore, it is considered that the liquid level height of molten steel is determined in real time by the real-time voltage between the plasma electrode and molten steel, the height difference between the real-time position and the initial position of the robot arm, and the consumption rate of the plasma electrode. The height of the mechanical arm can be continuously adjusted so that the plasma electrode can stably heat the molten steel, and therefore the voltage between the plasma electrode and the molten steel and the real-time position of the mechanical arm can be continuously changed, the height change of the molten steel liquid level can be accurately reflected through the voltage between the plasma electrode and the molten steel and the height difference between the real-time position and the initial position of the mechanical arm, and the liquid level height of the molten steel in the tundish can be accurately calculated.
Specific implementations of the above concepts are described below.
Referring to fig. 1, an embodiment of the present invention provides a method for measuring a molten steel level in a tundish, including:
102, in response to receiving a control instruction for heating molten steel in a tundish, controlling a mechanical arm to drive the bottom end of a plasma electrode to move to a target position above the liquid level of the molten steel; wherein the distance from the target position to the liquid level of the molten steel is a target distance;
104, controlling the mechanical arm to move in the process of heating the molten steel so that the plasma electrode heats the molten steel;
106, determining a first liquid level height of the molten steel in real time according to the real-time voltage between the plasma electrode and the molten steel, the height difference between the real-time position and the initial position of the mechanical arm and the consumption speed of the plasma electrode; when the bottom end of the plasma electrode firstly passes through the ladle opening of the tundish, the initial position is the position of the mechanical arm.
In the embodiment of the invention, in the process of heating the molten steel, the plasma electrode is enabled to stably heat the molten steel by controlling the movement of the mechanical arm, and the liquid level height of the molten steel is determined in real time according to the real-time voltage between the plasma electrode and the molten steel, the height difference between the real-time position and the initial position of the mechanical arm and the consumption speed of the plasma electrode. According to the scheme, the liquid level height of the molten steel in the tundish can be accurately calculated.
The manner in which the various steps shown in fig. 1 are performed is described below.
First, in step 100, a target distance from the plasma electrode to the molten steel surface in the tundish and a consumption rate of the plasma electrode are determined.
In order to improve the heating efficiency of the plasma electrode, the heating height of the plasma electrode needs to be determined, namely, the target distance between the plasma electrode and the liquid level of the molten steel in the tundish is selected.
In the embodiment of the invention, the heating speed of the molten steel in the tundish is determined through experiments, and specifically, the heating speed of the molten steel in the tundish is tested when the plasma electrode and the molten steel level in the tundish are at different distances; and determining the distance with the fastest heating speed as the target distance.
Of course, the method and criteria for determining the target distance are not exclusive, and for example, a distance that increases the carbon content of the molten steel in the tundish to the minimum may be selected as the target distance, and thus, is not particularly limited herein.
In addition, not only the change of the molten steel level but also the consumption of the plasma electrode should be considered. Since the plasma electrode is consumed when it is used, the consumption of the electrode at the lower end of the electrode inevitably causes a change in the distance between the plasma electrode and the molten steel surface, and it is necessary to determine the consumption rate of the plasma electrode in advance so that the plasma electrode can stably heat the molten steel.
In an embodiment of the present invention, determining a consumption rate of a plasma electrode comprises:
establishing a corresponding consumption speed relation database according to the material of the plasma electrode, the diameter of the plasma electrode and the working current of the plasma electrode;
and determining the consumption speed of the current plasma electrode according to the material, the diameter and the working current of the current plasma electrode and the consumption speed relation database.
In the embodiment of the invention, a relational database needs to be established in advance according to the consumption speeds of the plasma electrodes with different materials, different diameters and different working currents.
Specifically, the method can be established through experiments, for example, graphite electrodes with different diameters are used, molten steel is heated under different working currents, the change of the length of the plasma electrode before heating and the length of the plasma electrode after heating in a set time is recorded, and the consumption speed of the graphite electrode under different diameters and different working currents is calculated. To prevent contingency, the average value can be taken by changing the set time, testing multiple times.
It is understood that the consumption speed of the current plasma electrode can be determined according to the material, diameter and working current of the currently used plasma electrode and a consumption speed relation database established in advance.
Then, aiming at step 102, in response to receiving a control instruction for heating the molten steel in the tundish, controlling the mechanical arm to drive the bottom end of the plasma electrode to move to a target position above the liquid level of the molten steel; wherein the distance from the target position to the liquid surface of the molten steel is a target distance.
In the embodiment of the present invention, when the molten steel in the tundish needs to be heated, the bottom end of the plasma electrode needs to be controlled to move to the target position, and the distance from the target position to the current liquid level of the molten steel is the target distance determined in step 100.
When the plasma electrode is not heated, it is necessary to confirm the distance from the plasma electrode to the current molten steel surface again, whether the plasma electrode is located above the molten steel surface or moved to another position.
In an embodiment of the present invention, the controlling of the mechanical arm to drive the bottom end of the plasma electrode to move to the target position above the liquid level of the molten steel can be implemented in at least two ways:
the first method is that the current molten steel liquid level position is determined through the short circuit of the plasma electrode and the molten steel, and then the plasma electrode is controlled to move to the target position.
And secondly, firstly, aligning the height of the bottom end of the plasma electrode with the bottom surface of the inner part of the tundish, and then controlling the plasma electrode to move to a target position according to the current liquid level height of the molten steel and the target distance determined in the step 100.
The following describes the above two modes, respectively.
First, the first embodiment will be described.
In the first aspect, since it is necessary to monitor the voltage between the plasma electrode and the molten steel and determine the current molten steel level position when the voltage becomes 0, it is necessary to control the plasma electrode to generate a heating arc in advance in response to receiving a control command for heating the molten steel in the tundish so that the arc generated by the plasma electrode is electrically connected to the molten steel.
In the embodiment of the present invention, the first method may specifically include the following steps S1-S3:
s1: the control mechanical arm drives the plasma electrode to move downwards from the upper part of the liquid level of the molten steel;
s2: when the voltage between the plasma electrode and the molten steel is zero, determining that the bottom end of the plasma electrode is in contact with the molten steel, and controlling the mechanical arm to stop descending;
s3: and controlling the mechanical arm to ascend to the target position.
In the embodiment of the invention, the voltage between the plasma electrode and molten steel in the tundish needs to be acquired in real time. When the plasma heating arc is electrically connected with the molten steel, the plasma heating arc is not in contact with the liquid level of the molten steel, and the voltage between the plasma electrode and the molten steel in the tundish collected at the moment is indicated.
And then, the control mechanical arm drives the plasma electrode to move downwards from the upper part of the liquid level of the molten steel, when the collected voltage shows 0, the short circuit between the plasma electrode and the molten steel is indicated, the bottom end of the plasma electrode is determined to touch the surface of the molten steel, and the control mechanical arm stops descending. And then, the control mechanical arm drives the plasma electrode to move upwards for a target distance and then reach a target position, and the distance from the plasma electrode to the molten steel is equal to the target distance.
It should be noted that, when the bottom end of the plasma electrode first passes through the bag opening of the tundish, the position of the mechanical arm at this time needs to be recorded as an initial position. It is understood that the position above the highest liquid level that the molten steel in the tundish can reach is not necessarily the ladle opening as the reference height.
In the embodiment of the present invention, after controlling the robot arm to drive the bottom end of the plasma electrode to move to the target position above the liquid level of the molten steel, the method further includes: and determining the initial liquid level height of the molten steel according to the height difference between the position of the mechanical arm and the initial position when the voltage between the plasma electrode and the molten steel is zero and the height from the ladle opening of the tundish to the ladle bottom.
For example, when molten steel needs to be heated, the robot arm drives the plasma electrode to descend. When the plasma electrode passes through the photoelectric sensor of the bag opening, the initial position of the mechanical arm is recorded
. When the plasma electrode is lowered to contact with the molten steel level, namely the voltage between the plasma electrode and the molten steel is zero, the position of the mechanical arm is recorded
。
Then it is determined that,
the distance from the initial liquid level of the molten steel to the ladle opening,
i.e. the initial level height of the molten steel, wherein
The height from the opening of the tundish to the bottom of the tundish is shown.
The above description is completed for the first embodiment, and the following description is given for the second embodiment.
In the second mode, the embodiment of the present invention may specifically include:
the bottom end of the plasma electrode is positioned at the height when the liquid level of the molten steel is 0, namely, the bottom end of the plasma electrode is aligned with the bottom surface inside the tundish, and the plasma electrode can be clamped at the height in advance. And then controlling the plasma electrode to move upwards, wherein the moving distance is the sum of the current liquid level height of the molten steel and the target distance determined in the step 100, and controlling the plasma electrode to horizontally move to the position above the molten steel, namely, the target position is reached.
The current liquid level height of the molten steel can be manually input, can be measured by using a laser method, and can also be determined by other modes. The specific determination process will be described in detail in the following step 104, i.e. the calculation process of the second liquid level height.
In the second embodiment, it is not necessary to control the plasma electrode to generate the heating arc until the plasma electrode reaches the target position. After the plasma electrode reaches the target position, the plasma electrode can be controlled to generate a heating arc to start heating the molten steel.
Next, in step 104, the robot arm is controlled to move so that the plasma electrode heats the molten steel while the molten steel is being heated.
In steel production, continuous casting is an important link. In the continuous casting process, the control of the temperature stability and the low superheat degree of molten steel in the tundish has important significance for improving the production efficiency and the product quality. However, in the entire continuous casting process, particularly at the beginning, ladle change and the end of casting, the tundish water heat quantity inevitably has loss due to the heat absorption of the tundish lining, the heat loss of the tundish bath surface and the refractory material ladle wall, so that the heating technology of compensating the temperature drop of the molten steel in the tundish by the plasma heating of the tundish and stabilizing the molten steel casting temperature near the target value is receiving more and more attention.
During the heating process, since the ladle located above the tundish supplies molten steel to the tundish and simultaneously the molten steel in the tundish is also fed into the mold to form a billet, the volume of the molten steel in the tundish changes during the heating process. Further, the plasma electrode is also consumed during the heating process, and the length of the plasma electrode is changed. In order to stably heat molten steel by the plasma heating arc, it is necessary to control the height of the plasma electrode.
In one embodiment of the present invention, the height of the plasma electrode is adjusted and controlled, and the movement of the mechanical arm is controlled, which can be realized by at least three methods:
the method comprises the steps that a mechanical arm is controlled to move, so that the voltage between a plasma electrode and molten steel is constant;
calculating a second liquid level height through the weight of the molten steel in the tundish, and adjusting the height of the plasma electrode in real time according to the change of the second liquid level height and a second consumption length of the plasma electrode so as to keep the distance from the bottom end of the plasma electrode to the liquid level of the molten steel at a target distance;
and thirdly, calculating the height of the first liquid level through the real-time voltage between the plasma electrode and the molten steel, and adjusting the height of the plasma electrode in real time according to the change of the height of the first liquid level and the second consumption length of the plasma electrode so as to keep the distance from the bottom end of the plasma electrode to the liquid level of the molten steel at a target distance.
The three methods are described below.
First, a first method will be described.
In the first method, the control of the movement of the mechanical arm comprises the following steps:
determining the voltage between the plasma electrode and the molten steel as a target voltage when the bottom end of the plasma electrode is positioned at a target position;
and controlling the mechanical arm to drive the plasma electrode to move according to the voltage change between the plasma electrode and the molten steel so as to keep the voltage between the plasma electrode and the molten steel at a target voltage.
In the embodiment of the present invention, the voltage between the plasma electrode and the molten steel when the bottom end of the plasma electrode is located at the target position immediately after the start of heating is determined as the target voltage. And in the heating process, detecting the voltage between the plasma electrode and the molten steel in real time, and when the voltage begins to change, controlling the mechanical arm to drive the plasma electrode to move correspondingly so as to eliminate the change of the voltage and return the voltage between the plasma electrode and the molten steel to the target voltage.
The above description is completed on the first method, and the second method is described next.
The existing method utilizes a constant voltage or constant impedance mode to dynamically adjust the height of an electrode, and because the plasma arc has instability, such as the left and right shaking of the electrode, the position change of the arc, the unstable arc length and other factors, the fluctuation of voltage or impedance can be caused, at the moment, a mechanical arm can blindly adjust the height of the electrode to eliminate the fluctuation, and the fluctuation of larger current and voltage is caused, so that the stability of the arc is difficult to control. In addition, the fluctuation of voltage and current can generate harmonic waves and electromagnetic fields to interfere the operation of other equipment, the heating effect can be reduced, the smelting speed can be reduced, the consumption of graphite electrodes can be increased, and the carbon content of molten steel in a tundish can be increased.
Therefore, in the second method, in order to control the plasma arc to be stable, the plasma electrode of the tundish is heated stably, the heating efficiency is improved, and the product quality is further improved. It is considered that the plasma electrode is controlled by a constant arc length method, and the plasma heating arc is controlled by keeping the distance between the plasma electrode and the molten steel level constant, that is, the arc length constant. And not only the change of the liquid level height of the molten steel is considered, but also the consumption of the plasma electrode is considered, so that the plasma electrode can also move slowly along with the slow change of the liquid level height of the molten steel and the consumption of the plasma electrode, and large fluctuation can not occur, so that the plasma heating arc is more stable.
In the second method, the controlling the movement of the robot arm in the embodiment of the present invention may specifically include the following steps B1-B3:
b1: calculating the second liquid level height of the molten steel in real time according to the weight of the molten steel in the tundish;
b2: determining a second consumption length of the plasma electrode in a set time interval according to the consumption speed of the plasma electrode;
b3: and adjusting the height of the plasma electrode in real time according to the change of the second liquid level height and the second consumption length of the plasma electrode so as to keep the distance from the bottom end of the plasma electrode to the liquid level of the molten steel at a target distance.
It should be noted that patent publication No. CN113714495A discloses a method for controlling direct current plasma arc heating of a continuous casting tundish, which dynamically adjusts the height of an electrode by adopting a constant voltage mode, specifically: after starting arc in the casting stage, the cathode electrode is lifted, and the output voltage of the power supply is controlled to gradually rise to reach a set voltage range so that the arc length of the arc reaches a set arc length, wherein the arc length is in direct proportion to the output voltage of the power supply and is adjusted according to a set proportional value; during the stable casting phase, due to the influence of factors (such as arc length variation, arc length instability, etc.), voltage deviation occurs between the detected real-time voltage value and the set voltage value of the electrode, and in order to reduce the voltage deviation, the height of the electrode above the liquid level is adjusted blindly to eliminate the voltage deviation. And blind adjustment causes the arc length to change greatly this moment on the contrary, and this patent has set up a deviation scope, makes the arc length behind the adjustment electrode within the deviation scope of setting for the arc length, is in order to prevent to cause the arc length to change too greatly because blind adjustment, causes the unstability of plasma heating electric arc on the contrary, influences the heating effect.
Therefore, when the molten steel level of the tundish rises or falls, the cathode electrode is lifted or lowered to enable the arc length of the arc to reach the deviation range of the set arc length, and the result of the change of the arc length after the electrode height is adjusted according to the constant voltage mode is not disclosed.
In step B1, the second level of molten steel may be calculated at least by the following steps N1-N2:
n1: establishing a relational expression between the weight of the molten steel in the tundish and the second liquid level height according to the internal size of the tundish and the density of the molten steel;
specifically, a first equation of the volume and the liquid level height of molten steel is established according to the size of the interior of the tundish; establishing a second equation of the volume and the weight of the molten steel according to the density of the molten steel; determining a relation between the weight of the molten steel in the tundish and the height of the second liquid level according to the first equation and the second equation.
In the embodiment of the invention, as shown in fig. 2 and fig. 3, a tundish is respectively providedA front view and a side view, in which,
the length of the bottom of the interior of the tundish,
is the width of the bottom of the inner part of the tundish,
the length of the highest liquid level in the tundish is,
is the width of the highest liquid level in the tundish, H is the height of the highest liquid level in the tundish,
the inclination angle of the inner wall of the tundish in the length direction is,
the inclination angle of the inner wall of the tundish in the width direction is shown. These dimensional parameters are determined according to the specification of the tundish used, and the specific parameter values need to be measured in advance.
Then, assuming that the liquid level height of molten steel is h, a first equation of the volume of molten steel and the liquid level height may be established according to the size of the interior of the tundish as shown above.
In the embodiment of the present invention, the first equation is:
wherein,
is the volume of the molten steel, h is the liquid level height of the molten steel,
in a tundishThe length of the bottom of the section is,
the width of the bottom of the interior of the tundish,
the inclination angle of the ladle wall in the length direction of the inner part of the tundish is,
the inclination angle of the inner wall of the tundish in the width direction is shown.
In the first equation of the volume and the liquid level height of the molten steel,
are all known amounts of, among others,
can be calculated by the following formula.
And a second equation of the volume and weight of the molten steel may be established according to the density of the molten steel.
In the embodiment of the present invention, the second equation is:
wherein,
is the volume of the molten steel, M is the weight of the molten steel in the tundish,
is the density of the molten steel.
In the second equation of the volume and weight of molten steel, M can be measured in real timeIn order to achieve the above-mentioned object,
also in known amounts.
Then, based on the first equation and the second equation, the relationship between the weight of the molten steel in the tundish and the second liquid level height can be determined.
In the embodiment of the invention, the relation between the weight of the molten steel in the tundish and the second liquid level height is as follows:
wherein M is the weight of the molten steel in the tundish,
is the density of the molten steel, h is the liquid level height of the molten steel,
the length of the bottom of the interior of the tundish,
is the width of the bottom of the inner part of the tundish,
the inclination angle of the inner wall of the tundish in the length direction is,
the inclination angle of the inner wall of the tundish in the width direction is shown.
In the relational expression of the weight of molten steel and the liquid level height,
、
are all known, the weight M of the molten steel in the tundish and the second liquid level h are formedThe relational expression (c) of (c).
N2: and acquiring the weight of the molten steel in the tundish in real time, and calculating the second liquid level height of the molten steel in the heating process in real time according to the weight of the molten steel and the relational expression.
In the embodiment of the present invention, the weight of the molten steel is obtained in real time by a weighing device through a weighing method, and then the second liquid level height of the molten steel during the heating process is calculated in real time according to the relational expression between the weight of the molten steel and the second liquid level height in step N1 and the weight of the molten steel obtained in real time.
In addition, according to the manner of obtaining the second liquid level height of molten steel in this step, the current liquid level height of molten steel in the second mode in step 102 may be determined, and then the plasma electrode may be controlled to move to the target position according to the current liquid level height of molten steel and the target distance determined in step 100, thereby completing the second mode in step 102.
In step B2, calculating a second consumption length of the plasma electrode during heating in real time according to the consumption speed of the plasma electrode, comprising: acquiring the consumption speed of the plasma electrode; setting a time interval according to the consumption speed of the plasma electrode; a second consumption length of the plasma electrode is calculated over a set time interval.
For example, in step 100, the consumption speed of the plasma electrode is determined as v, i.e. the consumption length of the plasma electrode per unit time, if the time interval is set as
Then the second consumption length of the plasma electrode in the set time interval is
。
It should be noted that the time interval needs to be determined according to the consumption speed of the plasma electrode, and if the consumption speed of the plasma electrode is relatively high, the time interval needs to be set relatively small; if the consumption rate of the plasma electrode is relatively slow, the time interval may be relatively large. After the time interval is determined, a second elapsed length of the plasma electrode during the time interval is calculated.
Finally, in step B3, the height of the plasma electrode is adjusted in real time so that the plasma electrode is kept at the target distance from the liquid surface of the molten steel, based on the change in the second liquid level height and the second consumption length of the plasma electrode.
The above description of the second method is completed, and the following description of the third method is made.
In the third method, the controlling the movement of the robot arm in the embodiment of the present invention may specifically include:
and adjusting the height of the plasma electrode in real time according to the change of the first liquid level height of the molten steel and the second consumption length of the plasma electrode, so that the distance from the bottom end of the plasma electrode to the liquid level of the molten steel is kept at a target distance.
In the embodiment of the invention, different from the second method, the second liquid level height of the molten steel is not measured by using a weighing method, but the first liquid level height is calculated by using the real-time voltage between the plasma electrode and the molten steel, the height difference between the real-time position and the initial position of the mechanical arm and the consumption speed of the plasma electrode, and the height of the plasma electrode is adjusted in real time according to the change of the first liquid level height and the second consumption length of the plasma electrode, so that the distance from the bottom end of the plasma electrode to the liquid level of the molten steel keeps the target distance.
It should be noted that the calculation method of the first liquid level height of molten steel in the tundish is shown in step 106.
Next, aiming at step 106, determining a first liquid level height of the molten steel in real time according to a real-time voltage between the plasma electrode and the molten steel, a height difference between a real-time position and an initial position of the mechanical arm and a consumption speed of the plasma electrode; when the bottom end of the plasma electrode firstly passes through the ladle opening of the tundish, the initial position is the position of the mechanical arm.
The calculation method of the first liquid level height is explained below.
In the embodiment of the present invention, referring to fig. 4, the first liquid level height of molten steel can be calculated at least by using the following steps 400 and 406:
and 406, determining the first liquid level height of the molten steel in real time according to the length of the arc generated by the plasma electrode, the height difference between the real-time position and the initial position of the mechanical arm and the first consumption length of the plasma electrode.
In step 400, the length of the arc generated by the plasma electrode is calculated by the formula:
wherein,
for the length of the arc generated by the plasma electrode,
is the real-time voltage between the plasma electrode and the molten steel,
is the voltage drop of the plasma electrode before contacting the molten steel,
is the mean potential gradient.
In the embodiment of the invention, when the plasma electrode generates plasma to form electric arc, the electric arc impacts the liquid level of molten steel in the tundish, so that the liquid level of the molten steel is sunken. Therefore, the length of the arc generated by the plasma electrode calculated by the above formula
Comprises two parts, one part is the distance from the lower end surface of the plasma electrode to the liquid level of the molten steel, and the other part is the concave amount of the liquid level of the molten steel when the electric arc impacts the molten steel
. Therefore, the distance from the lower end surface of the plasma electrode to the molten steel surface is
。
Note that the voltage drop of the plasma electrode before contacting the molten steel
Average potential gradient
The amount of sinking of the liquid surface of the molten steel when the electric arc strikes the molten steel
Are all constant, mean potential gradient
And voltage drop near the electrode
The amount of sinking of the molten steel level when the arc strikes the molten steel is influenced by the furnace conditions
Depending on the operating current, it is necessary to determine the magnitude of the constant current in advance according to actual conditions, and then obtain the values of the three constants through experiments.
The experimental process is as follows: controlling the plasma electrode to generate a heating arc, slowly moving the plasma electrode to descend, and recording the position of the mechanical arm when the plasma electrode touches the molten steel and the voltage between the plasma electrode and the molten steel is 0
。
The amount of sinking of the liquid surface of the molten steel due to the electric arc striking the molten steel
In relation to the magnitude of the current, and is thus obtained in the above
In the process, the working current of the plasma electrode is small and is lower than the constant current in the actual situation, so that the liquid level of the molten steel is hardly recessed.
Then, the plasma electrode is lifted upwards, the plasma electrode is controlled to generate a heating arc, and the working current is equal to the constant current in the actual situation, so as to obtain the constant current
The same speed slowly moves the plasma electrode down. At the moment, the plasma arc impacts the liquid level of the molten steel, and the voltage between the plasma electrode and the molten steel is monitored at the moment that the electrode touches the molten steel
Becomes 0, whereby a voltage drop of the plasma electrode before contacting the molten steel can be obtained
。
At the same time, the position of the mechanical arm at the moment is recorded
Due to obtaining of
In the process (2), the electric arc impacts the molten steel surface, so that the concave amount of the molten steel surface when the electric arc impacts the molten steel can be obtained
I.e. by
。
Finally, the plasma electrode is lifted upwards to a random position where the voltage between the plasma electrode and the molten steel is not 0, and the voltage between the plasma electrode and the molten steel is recorded
And the position of the mechanical arm
The length of the arc generated by the plasma electrode can be obtained
Using the formula
The average potential gradient can be calculated
。
It can be seen that the voltage drop of the plasma electrode before contacting the molten steel
Average potential gradient
The amount of sinking of the liquid surface of the molten steel when the electric arc strikes the molten steel
Numerical values are obtained through the experimental process, and in order to reduce errors, the experimental process can be repeated, multiple times of measurement are carried out, and an average value is obtained.
It can be understood that the voltage drop of the plasma electrode before contacting the molten steel
Average potential gradient
The amount of sinking of the liquid surface of the molten steel when the electric arc strikes the molten steel
Is a constant value, and is characterized in that,
the real-time voltage between the plasma electrode and the molten steel can be detected in real time, and the length of the arc generated by the plasma electrode can be calculated
And then the distance from the lower end surface of the plasma electrode to the liquid level of the molten steel can be calculated by subtracting the concave amount of the liquid level of the molten steel
。
In step 402, a height difference between the real-time position of the robot arm and the initial position of the robot arm is calculated according to the real-time position of the robot arm and the initial position of the robot arm, that is, the position of the robot arm when the lower end of the plasma electrode first passes through the tundish nozzle
。
In step 404, a first consumption length of the plasma electrode is determined in real time based on the consumption speed v of the plasma electrode determined in step 100 and a real-time heating time t of the plasma electrode, i.e., a time interval from the start of heating of the plasma electrode to this moment.
In step 406, the calculation formula of the first level height of molten steel is:
wherein,
is the first liquid level height of the molten steel,
the height from the opening of the tundish to the bottom of the tundish,
for the length of the arc generated by the plasma electrode,
the concave quantity of the liquid level of the molten steel when the electric arc impacts the molten steel,
the height difference between the real-time position of the mechanical arm and the initial position of the mechanical arm, v is the consumption speed of the plasma electrode, and t is the heating time of the plasma electrode.
As can be appreciated, the first and second,
the distance from the real-time liquid level of the molten steel to the ladle opening of the tundish and the height from the ladle opening of the tundish to the ladle bottom are used
And subtracting the distance from the real-time liquid level of the molten steel to the opening of the tundish to obtain the real-time first liquid level height of the molten steel in the tundish.
In the embodiment of the invention, the plasma electrode is controlled to generate the heating electric arc, so that the mechanical arm drives the plasma electrode to descend, and when the plasma electrode passes through the tundish nozzle, the initial position of the mechanical arm is recorded; the plasma electrode continues to descend, when the voltage feedback between the plasma electrode and the molten steel is 0, the plasma electrode is shown to touch the molten steel, and the initial liquid level height of the molten steel can be calculated according to the step 102; then, according to step 102, the mechanical arm is lifted to drive the plasma electrode to reach a target position, and molten steel is heated; in the heating process, according to any one of the three methods in the step 104, the mechanical arm is controlled to drive the plasma electrode to continuously adjust the height so that the plasma electrode can stably heat the molten steel, and according to the method in the step 106, the real-time first liquid level height of the molten steel is calculated through the real-time voltage between the plasma electrode and the molten steel and the real-time position of the mechanical arm.
The embodiment of the invention provides a measuring device for the liquid level of molten steel in a tundish, which comprises a memory and a processor, wherein a computer program is stored in the memory, and when the processor executes the computer program, the measuring method for the liquid level of molten steel in the tundish, which is described in any embodiment of the specification, is realized.
Specifically, the controller may be a PLC controller. The method for measuring the liquid level of the molten steel in the tundish, which is described in any embodiment of the specification, is realized by calculating the liquid level height of the molten steel and the consumption length of the plasma electrode by using a PLC (programmable logic controller) and controlling the ion electrode to move.
As shown in fig. 5, an embodiment of the present invention further provides a system for measuring a molten steel level in a tundish, including:
the tundish 1 is used for containing molten steel;
the plasma electrode 2 is arranged above the tundish 1 and used for ionizing plasma gas to heat the molten steel;
the two ends of the plasma generator 3 are respectively connected with the plasma electrode 2 and the molten steel and used for supplying power to the plasma electrode 2;
the bottom electrode 4 is arranged at the bottom of the tundish 1, and two ends of the bottom electrode are respectively connected with molten steel and the plasma generator 3;
the mechanical arm 5 is connected with the plasma electrode 2 and is used for driving the plasma electrode 2 to move;
the voltage sensor 6 is arranged between the plasma electrode 2 and the molten steel and is used for collecting the voltage between the plasma electrode 2 and the molten steel in real time;
the photoelectric sensor 7 is arranged at the ladle opening of the tundish 1 and used for determining the initial position of the mechanical arm 5;
the temperature sensor (not marked in the figure) is arranged in the molten steel and is used for acquiring the temperature of the molten steel in real time;
a weighing device (not shown) arranged at the bottom of the tundish 1 and used for weighing the molten steel in real time;
the measuring device (not shown) is respectively connected with the plasma generator 3, the moving assembly 5, the voltage sensor 6, the photoelectric sensor 7, the temperature sensor (not shown) and the weighing device (not shown), and is used for implementing the method for measuring the molten steel level of the tundish according to any embodiment of the present specification.
In the embodiment of the invention, the plasma electrode 2 is a graphite electrode and adopts a hollow structure; the plasma gas is argon and is introduced from the middle of the plasma electrode. When the plasma electrode 2 starts to work, the plasma electrode 2 discharges electricity to ionize argon gas to generate high-energy plasma so as to heat molten steel.
It should be noted that the plasma electrode 2 is made of graphite because graphite has a high melting point and is excellent in conductivity, and other materials may be used. Argon is selected as the plasma gas because the argon is inert gas and is not easy to react with the molten steel. Of course, other gases, such as nitrogen, may be used.
In the embodiment of the invention, the plasma generator 3 is a power supply, and the alternating current is converted into the direct current through silicon controlled rectifier rectification, so that the constant current can be controlled. The plasma generator 3 is used to supply power to the plasma electrode 2 to cause the plasma electrode 2 to generate plasma.
In the embodiment of the present invention, the bottom electrode 4 is disposed at the bottom of the tundish 1 and serves as an anode.
In the embodiment of the present invention, the robot arm 5 has a plurality of axes, and can simultaneously move in multiple axes, and an automatic operation path needs to be set before automatic operation.
In the embodiment of the present invention, the measuring device (not shown) is a PLC controller, and is electrically connected to the plasma generator 3, the moving assembly 5, the voltage sensor 6, the photoelectric sensor 7, the temperature sensor (not shown) and the weighing device (not shown), so as to control the whole system and implement the method for measuring the molten steel level in the tundish according to any embodiment of the present specification.
In addition, since the amount of heat generated by the plasma electrode 2 is too large, it is necessary to cool down the cable 8 connecting the plasma electrode 2 and the plasma generator 3, the bottom electrode 4 and the plasma generator 3 by water cooling.
The embodiments of the invention have at least the following beneficial effects:
the real-time voltage between the plasma electrode and the molten steel and the real-time position of the mechanical arm are used for calculating the liquid level height of the molten steel in the tundish, and the tundish liquid level measuring device has the advantages of being high in measuring precision, not prone to interference, free of extra equipment and the like. The method is used for obtaining the accurate liquid level of the tundish, and then the liquid level of the molten steel of the tundish is accurately controlled through the continuous casting system, so that the quality of a billet product can be improved, the service life of the tundish can be prolonged, and the slag rolling amount in the casting process can be reduced.
Finally, it should be noted that: the above examples are only intended to illustrate the technical solution of the present invention, but not to limit it; although the present invention has been described in detail with reference to the foregoing embodiments, it will be understood by those of ordinary skill in the art that: the technical solutions described in the foregoing embodiments may still be modified, or some technical features may be equivalently replaced; and such modifications or substitutions do not depart from the spirit and scope of the corresponding technical solutions of the embodiments of the present invention.
Claims (8)
1. A method for measuring the liquid level of molten steel in a tundish is characterized by comprising the following steps:
determining a target distance from a plasma electrode to the liquid level of molten steel in the tundish and a consumption speed of the plasma electrode;
in response to the received control instruction for heating the molten steel in the tundish, controlling the mechanical arm to drive the bottom end of the plasma electrode to move to a target position above the liquid level of the molten steel; wherein the distance from the target position to the liquid level of the molten steel is a target distance;
controlling the mechanical arm to move in the process of heating the molten steel so that the plasma electrode heats the molten steel;
determining a first liquid level height of the molten steel in real time according to the real-time voltage between the plasma electrode and the molten steel, the height difference between the real-time position and the initial position of the mechanical arm and the consumption speed of the plasma electrode; when the bottom end of the plasma electrode passes through a ladle opening of a tundish for the first time, the initial position is the position of the mechanical arm at the moment;
the controlling the robotic arm to move includes:
determining a voltage between the plasma electrode and the molten steel as a target voltage when the bottom end of the plasma electrode is located at a target position;
controlling the mechanical arm to drive the plasma electrode to move according to the voltage change between the plasma electrode and the molten steel so as to keep the voltage between the plasma electrode and the molten steel at a target voltage;
the determining the first liquid level height of the molten steel in real time according to the real-time voltage between the plasma electrode and the molten steel, the height difference between the real-time position and the initial position of the mechanical arm and the consumption speed of the plasma electrode comprises the following steps:
calculating the length of an electric arc generated by the plasma electrode according to the real-time voltage between the plasma electrode and the molten steel;
determining a height difference between a real-time position of the mechanical arm and an initial position of the mechanical arm;
determining a first consumption length of the plasma electrode according to the consumption speed of the plasma electrode and the heating time of the plasma electrode;
determining a first liquid level height of the molten steel in real time according to the length of an electric arc generated by the plasma electrode, the height difference between the real-time position and the initial position of the mechanical arm and the first consumption length of the plasma electrode;
the calculation formula of the length of the arc generated by the plasma electrode is as follows:
wherein,
for the length of the arc generated by the plasma electrode,
is the real-time voltage between the plasma electrode and the molten steel,
is the voltage drop of the plasma electrode before contacting the molten steel,
is the mean potential gradient;
the calculation formula of the first liquid level height of the molten steel is as follows:
wherein,
is a first liquid level height of the molten steel,
the height from the opening of the tundish to the bottom of the tundish is,
for the length of the arc generated by the plasma electrode,
the amount of the liquid level of the molten steel is reduced when the electric arc impacts the molten steel,
and v is the height difference between the real-time position of the mechanical arm and the initial position of the mechanical arm, v is the consumption speed of the plasma electrode, and t is the heating time of the plasma electrode.
2. A method for measuring the liquid level of molten steel in a tundish is characterized by comprising the following steps:
determining a target distance from a plasma electrode to the liquid level of molten steel in the tundish and a consumption speed of the plasma electrode;
in response to the received control instruction for heating the molten steel in the tundish, controlling the mechanical arm to drive the bottom end of the plasma electrode to move to a target position above the liquid level of the molten steel; wherein the distance from the target position to the liquid level of the molten steel is a target distance;
controlling the mechanical arm to move in the process of heating the molten steel so that the plasma electrode heats the molten steel;
determining a first liquid level height of the molten steel in real time according to a real-time voltage between the plasma electrode and the molten steel, a height difference between a real-time position and an initial position of the mechanical arm and a consumption speed of the plasma electrode; when the bottom end of the plasma electrode passes through a ladle opening of a tundish for the first time, the initial position is the position of the mechanical arm at the moment;
the controlling the robotic arm to move, comprising:
calculating the second liquid level height of the molten steel in real time according to the weight of the molten steel in the tundish;
determining a second consumption length of the plasma electrode in a set time interval according to the consumption speed of the plasma electrode;
adjusting the height of the plasma electrode in real time according to the change of the second liquid level height and the second consumption length of the plasma electrode, so that the distance from the bottom end of the plasma electrode to the liquid level of the molten steel is kept at a target distance;
the determining the first liquid level height of the molten steel in real time according to the real-time voltage between the plasma electrode and the molten steel, the height difference between the real-time position and the initial position of the mechanical arm and the consumption speed of the plasma electrode comprises the following steps:
calculating the length of an electric arc generated by the plasma electrode according to the real-time voltage between the plasma electrode and the molten steel;
determining a height difference between a real-time position of the mechanical arm and an initial position of the mechanical arm;
determining a first consumption length of the plasma electrode according to the consumption speed of the plasma electrode and the heating time of the plasma electrode;
determining a first liquid level height of the molten steel in real time according to the length of an electric arc generated by the plasma electrode, the height difference between the real-time position and the initial position of the mechanical arm and the first consumption length of the plasma electrode;
the calculation formula of the length of the arc generated by the plasma electrode is as follows:
wherein,
for the length of the arc generated by the plasma electrode,
is the real-time voltage between the plasma electrode and the molten steel,
is the voltage drop of the plasma electrode before contacting the molten steel,
is the mean potential gradient;
the calculation formula of the first liquid level height of the molten steel is as follows:
wherein,
is a first liquid level height of the molten steel,
the height from the opening of the tundish to the bottom of the tundish is,
for the length of the arc generated by the plasma electrode,
the amount of the liquid level of the molten steel is concave when the electric arc impacts the molten steel,
and v is the height difference between the real-time position of the mechanical arm and the initial position of the mechanical arm, v is the consumption speed of the plasma electrode, and t is the heating time of the plasma electrode at the moment.
3. A method for measuring the liquid level of molten steel in a tundish is characterized by comprising the following steps:
determining a target distance from a plasma electrode to the liquid level of molten steel in the tundish and a consumption speed of the plasma electrode;
in response to the received control instruction for heating the molten steel in the tundish, controlling the mechanical arm to drive the bottom end of the plasma electrode to move to a target position above the liquid level of the molten steel; wherein the distance from the target position to the liquid level of the molten steel is a target distance;
controlling the mechanical arm to move in the process of heating the molten steel so that the plasma electrode heats the molten steel;
determining a first liquid level height of the molten steel in real time according to a real-time voltage between the plasma electrode and the molten steel, a height difference between a real-time position and an initial position of the mechanical arm and a consumption speed of the plasma electrode; when the bottom end of the plasma electrode passes through a ladle opening of a tundish for the first time, the initial position is the position of the mechanical arm at the moment;
the controlling the robotic arm to move includes:
determining a second consumption length of the plasma electrode in a set time interval according to the consumption speed of the plasma electrode;
according to the fed back change of the first liquid level height of the molten steel and the second consumption length of the plasma electrode, adjusting the height of the plasma electrode in real time to enable the distance from the bottom end of the plasma electrode to the liquid level of the molten steel to keep a target distance;
the determining the first liquid level height of the molten steel in real time according to the real-time voltage between the plasma electrode and the molten steel, the height difference between the real-time position and the initial position of the mechanical arm and the consumption speed of the plasma electrode comprises the following steps:
calculating the length of an electric arc generated by the plasma electrode according to the real-time voltage between the plasma electrode and the molten steel;
determining a height difference between a real-time position of the mechanical arm and an initial position of the mechanical arm;
determining a first consumption length of the plasma electrode according to the consumption speed of the plasma electrode and the heating time of the plasma electrode;
determining a first liquid level height of the molten steel in real time according to the length of an electric arc generated by the plasma electrode, the height difference between the real-time position and the initial position of the mechanical arm and the first consumption length of the plasma electrode;
the calculation formula of the length of the arc generated by the plasma electrode is as follows:
wherein,
for the length of the arc generated by the plasma electrode,
is the real-time voltage between the plasma electrode and the molten steel,
is the voltage drop of the plasma electrode before contacting the molten steel,
is the mean potential gradient;
the calculation formula of the first liquid level height of the molten steel is as follows:
wherein,
is a first liquid level height of the molten steel,
the height from the opening of the tundish to the bottom of the tundish is,
for the length of the arc generated by the plasma electrode,
is electricityThe amount of liquid level of the molten steel is concave when the arc impacts the molten steel,
and v is the height difference between the real-time position of the mechanical arm and the initial position of the mechanical arm, v is the consumption speed of the plasma electrode, and t is the heating time of the plasma electrode at the moment.
4. The method according to any one of claims 1-3, further comprising: controlling the plasma electrode to generate a heating arc in response to receiving a control instruction for heating molten steel in the tundish;
the control mechanical arm drives the bottom end of the plasma electrode to move to a target position above the liquid level of the molten steel, and the control mechanical arm comprises:
controlling a mechanical arm to drive the plasma electrode to move downwards from the upper part of the liquid level of the molten steel;
when the voltage between the plasma electrode and the molten steel is zero, determining that the bottom end of the plasma electrode is in contact with the molten steel, and controlling the mechanical arm to stop descending;
and controlling the mechanical arm to ascend to a target position.
5. The method of claim 4, further comprising, after the controlling the robot arm to move the bottom end of the plasma electrode to a target position above the liquid level of the molten steel and before the controlling the robot arm to move during the heating of the molten steel:
and determining the initial liquid level height of the molten steel according to the height difference between the position of the mechanical arm and the initial position when the voltage between the plasma electrode and the molten steel is zero and the height from the ladle opening of the tundish to the ladle bottom.
6. A measuring device for the level of molten steel in a tundish, comprising a memory in which a computer program is stored and a processor which, when executing said computer program, carries out the method according to any one of claims 1 to 5.
7. A measuring system of molten steel level in a tundish is characterized by comprising:
the tundish is used for containing molten steel;
the plasma electrode is arranged above the tundish and used for ionizing plasma gas so as to heat the molten steel;
the two ends of the plasma generator are respectively connected with the plasma electrode and the molten steel and used for supplying power to the plasma electrode;
the bottom electrode is arranged at the bottom of the tundish, and two ends of the bottom electrode are respectively connected with the molten steel and the plasma generator;
the mechanical arm is connected with the plasma electrode and is used for driving the plasma electrode to move;
the voltage sensor is arranged between the plasma electrode and the molten steel and is used for collecting the voltage between the plasma electrode and the molten steel in real time;
the photoelectric sensor is arranged at the ladle opening of the tundish and used for determining the initial position of the mechanical arm;
the temperature sensor is arranged in the molten steel and used for acquiring the temperature of the molten steel in real time;
the weighing device is arranged at the bottom of the tundish and is used for weighing the molten steel in real time;
a measuring device electrically connected to the plasma generator, the robot arm, the voltage sensor, the photoelectric sensor, the temperature sensor, and the weighing device, respectively, the measuring device according to claim 6.
8. The system of claim 7, wherein the plasma electrode is a graphite electrode, and is of a hollow structure; the plasma gas is argon and is introduced from the middle of the plasma electrode.
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| CN1088679A (en) * | 1993-11-03 | 1994-06-29 | 唐山钢铁(集团)公司 | Liquid level checking method for melted steel container heated by plasma |
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| EP2568265A1 (en) * | 2011-09-09 | 2013-03-13 | Tata Steel UK Limited | Apparatus and method for measuring the liquid metal level in a metallurgical vessel |
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| CN112828252A (en) * | 2019-11-22 | 2021-05-25 | 上海梅山钢铁股份有限公司 | Method for determining plasma heating position of tundish by using physical model |
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| CN1088679A (en) * | 1993-11-03 | 1994-06-29 | 唐山钢铁(集团)公司 | Liquid level checking method for melted steel container heated by plasma |
| JPH08320111A (en) * | 1995-05-26 | 1996-12-03 | Hitachi Zosen Corp | Surface level detection method for base metal in plasma type ash melting furnace |
| US6614832B1 (en) * | 1999-05-31 | 2003-09-02 | Stahlwerk Thueringen Gmbh | Method of determining electrode length and bath level in an electric arc furnace |
| EP2568265A1 (en) * | 2011-09-09 | 2013-03-13 | Tata Steel UK Limited | Apparatus and method for measuring the liquid metal level in a metallurgical vessel |
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