JP6050173B2 - Plasma heating control apparatus and plasma heating control method - Google Patents

Description

  The present invention relates to a plasma heating control device and a plasma heating control method for controlling plasma heating of molten steel accommodated in a tundish of a continuous casting machine.

  A plasma heating device that installs a plasma torch above the molten steel (molten metal) housed in the tundish of a continuous casting machine, and heats the molten steel with an arc of 10000 ° C or higher by a plasma arc generated between the plasma torch and molten steel In this case, by controlling the distance between the tip of the plasma torch and the surface of the molten steel to a desired distance, the ignition failure of the plasma arc due to this distance being too long can be prevented, and this distance is too short. Therefore, it is possible to prevent the splash of molten steel from adhering to the tip of the plasma torch and the immersion of the plasma torch in the molten steel.

  In the plasma heating described above, the molten steel is stably injected into the tundish, and the molten steel is injected from the tundish into the mold. This injection is stabilized and the level of the molten steel surface in the tundish is constant. After that, it is generally performed at the stage where the molten steel temperature in the tundish starts to decrease particularly at the end of casting.

  By the way, to measure the distance to the surface of the molten steel in the tundish directly using a distance meter etc., a slag layer (thickness 20-30mm) for heat insulation and oxidation prevention is formed on the surface of the molten steel Therefore, it is extremely difficult.

  Therefore, the conventional method for specifying the distance to the molten steel surface is not a direct measurement, but a method of indirectly converting the molten steel height in the tundish from the weight measurement result of the tundish. However, the tundish is often thermally deformed, its refractory is eroded, or the tundish installation cart is often deformed, which causes the error in the converted value of the molten steel due to these factors. There is.

  Here, in Patent Document 1, the height position of the plasma torch is detected using the top of the heating chamber as a reference plane and the weight of the molten steel including the weight of the tundish is measured by the load cell. There is disclosed a tundish equipped with a plasma heating device that controls the raising and lowering of a plasma torch and adjusts the arc length of the plasma torch. By applying this tundish, even if the molten steel level in the tundish varies, the arc length is controlled to be constant and the molten steel temperature in the tundish can be maintained within a predetermined range.

  However, as disclosed in Patent Document 1, in the method of estimating the relative distance by the arc voltage, the voltage varies depending on the temperature of the heated partial atmosphere, the gas composition, and the like, and thus it is difficult to say that the measurement result is reliable.

JP-A-3-285746

  The present invention has been made in view of the above-described problems, and can precisely specify the surface height of the molten steel accommodated in the tundish of the continuous casting machine, so that the tip of the plasma torch and the surface of the molten steel can be identified. It is an object of the present invention to provide a plasma heating control device and a plasma heating control method capable of precisely controlling the distance between them.

  In order to achieve the above object, a plasma heating control apparatus according to the present invention is a plasma heating control apparatus that controls plasma heating of molten steel filled in a tundish of a continuous casting machine, and is provided above a tundish lid. The lid has a support frame provided at a position where it is cut off, a plasma torch attached to the support frame so as to be able to advance and retreat, a distance meter attached to the support frame, and a reference point defined on the tundish lid And a detection rod having a length passing through an opening formed in the tundish lid, the upper end being higher than the reference point and the lower end being located in the molten steel, and the distance measured by a distance meter The tip position of the plasma torch is controlled using the total distance of the distance L1 from the meter to the reference point and the distance L2 from the reference point measured by the detection rod to the surface of the molten steel It is.

  The plasma heating control device of the present invention takes into account that the tundish and the tundish lid are thermally deformed, and calculates the distance L1 from the reference point provided on the tundish lid and the distance L2 from the reference point to the surface of the molten steel. Each is measured, and the tip position of the plasma torch is controlled by the total distance. Here, the distance L1 is measured by a distance meter such as a distance sensor, and the distance L2 is measured by a detection rod.

  As described, the distance L2 from the reference point to the surface of the molten steel is measured with a detection rod. A slag layer (thickness 20 to 30 mm) for heat insulation and oxidation prevention is formed on the surface of the molten steel. Therefore, when measured with a distance sensor or the like, the distance is measured including the thickness of the slag layer, and it is difficult to perform precise distance measurement to the surface of the molten steel excluding such a slag layer. Because.

  Therefore, as a method for measuring the distance L2 by the detection rod, for example, a manual measurement method by a measurement manager is preferable.

  In addition, there is a method in which a detection rod with a memory is installed in a robot hand, the vicinity of the molten steel surface is imaged with a CCD camera, and the molten steel surface level under the slag is measured.

  The tip position of the plasma torch (distance L4 from the distance meter to the tip of the plasma torch) is identified from the current position of the plasma torch and the length of the plasma torch on the support frame to which the plasma torch is attached so as to be able to move forward and backward, and the distance L1 and the distance L2 By subtracting the distance L4 from the total distance L3, the distance L5 from the tip of the plasma torch to the molten steel surface can be precisely specified.

  The support frame to which the distance meter is attached and the plasma torch is attached so as to be able to advance and retreat is disposed above the tundish and is separated from the tundish. Therefore, although the distance between the reference point on the lid of the tundish and the distance meter changes due to the thermal deformation of the tundish, the absolute position of the distance meter fixed by the support frame does not change due to the thermal deformation of the tundish. .

  Therefore, even if the distance L1 from the reference point on the lid of the tundish changes due to thermal deformation of the tundish, the distance L2 from the reference point to the molten steel surface is directly measured by the detection rod. In addition, the distance L4 from the distance meter to the tip position of the plasma torch is not affected by the thermal deformation of the tundish, and the distance L4 corresponding to the position of the plasma torch is specified. Thus, the distance from the tip of the plasma torch to the surface of the molten steel can be specified precisely.

  The distance L5 between the tip of the plasma torch and the molten steel surface is calculated by calculating the difference between the total distance L3 and the distance L4. Based on the calculation result, the plasma torch can be lowered or raised to control the distance L5 to a desired value (for example, about 300 mm).

  In addition, a preferred embodiment of the plasma heating control apparatus according to the present invention includes a first control unit in which a relationship graph between the weight of the tundish containing molten steel and the height of the molten steel in the tundish is stored, and a tand containing molten steel. A load cell for measuring the weight of the dish, the measurement data in the load cell is transmitted to the first control unit, and the height of the molten steel according to the measurement data received by the first control unit from the relation graph Identify and identify the corrected distance L2 by correcting the distance L2 according to the specified molten steel height, and use the total distance of the distance L1 and the corrected distance L2 of the plasma torch The tip position is controlled.

  The plasma heating control apparatus of the present embodiment first measures the distance L2 with the detection rod before plasma heating, and also measures the weight W of the tundish at this time, and transmits both to the first control unit. deep. After this preparation is completed, plasma heating is performed, and molten steel is supplied from the metal pan to the tundish, and the amount of molten steel in the tundish (fluctuation of the molten steel surface) occurs due to the injection of molten steel from the tundish to the mold. In this case, in order to control the distance between the molten steel surface and the torch to a desired value, the tundish weight W ′ is measured at any time with a load cell (container weighing meter), and the difference ΔW = The correction amount ΔH of the distance L2 is obtained from W′−W, and the tip position of the plasma torch is controlled to a position that ensures a desired separation from the molten steel surface using the corrected distance L2 ′ = L2 + ΔH.

  A relationship graph between the weight of the tundish including the molten steel and the height of the molten steel in the tundish is obtained in advance, and this is converted into data and stored in the first control unit. Further, before the plasma heating is performed, the distance L2 is measured by the detection rod, the weight W of the tundish at this time is measured, and both are transmitted to the first control unit.

  The weight W 'of the tundish containing the molten steel is measured at any time by the load cell, and the difference from the weight W when the measurement data is sent to the first control unit and measured most recently by the detection rod ΔW = W'- W is obtained, the height correction amount ΔH of the molten steel surface is calculated from the relationship graph, and the distance L2 ′ = L2 + ΔH at that time is specified.

  According to the plasma heating control apparatus of the present embodiment, the distance between the tip of the plasma torch and the molten steel surface can be constantly controlled to a desired value in accordance with the fluctuation of the molten steel surface.

  The above-mentioned relationship graph prepared in advance is obtained when a new tundish is used, and the gradient (linear gradient or curve gradient) of the relationship graph is slightly different depending on the degree of erosion in the melted tundish. However, since the difference in the steel height ΔH is calculated from the difference in weight ΔW, such a difference in gradient is an error range, so the relationship graph created using the new tundish can be represented in the tundish. You may use as it is over a lifetime.

  Further, a preferred embodiment of the plasma heating control apparatus according to the present invention includes an inert gas providing unit that provides an inert gas in the tundish, a standard value L0 of the distance L1, and an error between the distance L1 and the distance L0. A second control unit that stores an allowable value, and a measured value of the distance L1 is transmitted to the second control unit, and when the distance L1 deviates from the allowable value, the second control unit A command signal for providing a larger amount of inert gas than usual in the tundish is transmitted to the active gas providing unit, and a signal for issuing an alarm is transmitted from the second control unit to the alarm unit. It is something that has come to be.

  In plasma heating, the inside of the tundish is generally an inert gas atmosphere (argon gas atmosphere) in order to ensure the life of the tip of the plasma torch (the material is mainly composed of tungsten, for example) during heating.

  If the standard value L0 of the distance L1 is determined in advance and the measured distance L1 is larger than the standard value L0 and the deviation exceeds a certain value, the tundish lid is thermally deformed, etc. It can be identified that gas is leaking. Therefore, in such a case, the second control unit that stores the allowable value of the error between the distance L1 and the distance L0 and specifies that the received measured value of the distance L1 deviates from the allowable value is inactive. A command signal for supplying a larger amount of inert gas than usual into the tundish is transmitted to the gas supply unit. For example, a command signal that increases the amount of argon gas blown into the tundish to about 1.5 times the normal amount is transmitted, and such control is executed.

  At the same time, it alerts the administrator to check the tundish lid and perform maintenance if necessary.

  The present invention also extends to a plasma heating control method. This control method is a plasma heating control method for controlling plasma heating of molten steel contained in a tundish of a continuous casting machine, and includes a tundish lid. A plasma torch is attached to a support frame provided at a position where the lid is cut off from the lid, and a distance meter is attached to the support frame, and a reference point is defined on the tundish lid. A detection rod having a length passing through an opening formed in the lid of the dish, the upper end being higher than the reference point, and the lower end being located in the molten steel, is arranged from the distance meter with a distance meter. The distance L1 from the reference point to the surface of the molten steel is measured with a detection rod, and the tip position of the plasma torch is controlled using the total distance L1 and L2.

  According to this control method, the distance L1 to the reference point on the tundish lid that can be thermally deformed is measured with a distance meter that is not affected by the thermal deformation of the tundish, and the distance from the reference point to the molten steel surface L2 is measured manually using a detection rod, and after obtaining these total distances L3, the distance L4 from the distance meter to the tip of the plasma torch is specified, and the difference between these L3 and L4 is obtained. The distance from the tip of the plasma torch to the molten steel surface can be specified precisely, and can be controlled to a desired distance.

  Also in the plasma heating control method according to the present invention, a relationship graph between the weight of the tundish containing molten steel and the height of the molten steel in the tundish is obtained in advance, and the weight of the tundish containing molten steel is measured at any time using a load cell. Then, the measurement data in the load cell is transmitted to the first control unit, the height of the molten steel corresponding to the measurement data received by the first control unit is specified from the relation graph, and the height of the specified molten steel is determined. Accordingly, it is preferable to correct the distance L2 to identify the corrected distance L2, and to control the tip position of the plasma torch using the total distance of the distance L1 and the corrected distance L2.

  In addition, plasma heating is performed with the inside of the tundish as an inert gas atmosphere, and the standard value L0 of the distance L1 and the allowable value of the error between the distance L1 and the distance L0 are specified in advance, and the distance L1 When the measured value deviates from the allowable value, it is preferable to provide a larger amount of inert gas than usual in the tundish and to warn that the inert gas is leaking from the tundish.

  As can be understood from the above description, according to the plasma heating control apparatus and the plasma heating control method of the present invention, the distance L1 to the reference point on the tundish lid that can be thermally deformed is measured with a distance meter, The distance L2 from the reference point to the surface of the molten steel is directly measured with a detection rod to obtain the total distance L3, and the distance L4 from the distance meter to the tip of the plasma torch is specified and the difference between the distance L4 and the distance L3 By specifying the distance L5 from the tip of the plasma torch to the molten steel surface, precise distance measurement that is not affected by thermal deformation of the tundish is realized, and the distance L5 between the tip of the plasma torch and the molten steel surface is desired. Can be controlled.

It is a side view of Embodiment 1 of the plasma heating control apparatus of this invention. It is an II arrow directional view of FIG. It is the side view explaining another embodiment of the measuring method of distance L1. It is a side view of Embodiment 2 of the plasma heating control apparatus of this invention. (A) is the block diagram explaining the structure in a control part, (b) is the figure explaining the relationship graph built in the 1st control part. It is a side view of Embodiment 3 of the plasma heating control apparatus of this invention. It is the block diagram explaining the structure in a control part.

  Embodiments 1, 2, and 3 of the plasma heating control apparatus and control method of the present invention will be described below with reference to the drawings.

(Embodiment 1 of Plasma Heating Control Device and Control Method)
FIG. 1 is a side view of Embodiment 1 of the plasma heating control apparatus of the present invention, and FIG. 2 is a view taken along arrow II in FIG.

  The configuration of the continuous casting machine will be outlined with reference to FIGS. 1 and 2. From the ladle N at the top where the molten steel Y is poured, the tundish 1 mounted on the operating floor frame, and the tundish 1 It is generally composed of a mold M into which molten steel Y is injected through the immersion nozzle 1c, and a roll (not shown) that transports a steel piece SP that has been rapidly solidified by the mold M and discharged (X2 direction).

  Molten steel made in the blast furnace is injected into the ladle N through secondary refining. And after the ladle N is installed in the uppermost part of the continuous casting machine, the molten steel accommodated in the ladle N is poured into the lower tundish 1 from the bottom of the ladle N, and even this tundish 1 is in the molten steel. Part of the inclusions is removed by floating separation.

  The molten steel Y accommodated in the tundish 1 is then poured into the mold M from the immersion nozzle 1c at the bottom. The mold M is generally made of copper and is always water-cooled, and the molten steel in contact with the mold M is cooled while precisely adjusting the temperature. In the mold M, the molten steel begins to form a thin solidified shell consisting of fine crystals from the outside, the fine crystals are connected and grow into large dendrites, and are transferred from below the mold M as steel pieces SP. (X2 direction).

  The steel slab SP begins to solidify from the outside while being carried by a roll, and when the steel slab S is a large slab called slab or bloom, it is appropriately lengthened by a gas cutter (not shown) at the end of the roll row. Disconnected. On the other hand, when the steel piece S is a small slab called billet, it is cut by a shear (not shown) and adjusted to an appropriate length.

  Next, the configuration of the first embodiment of the plasma heating control apparatus will be described with reference to FIGS.

  The illustrated plasma heating control apparatus 10 includes a tundish 1, a support mechanism 2 provided above the lid 1 a of the tundish 1 and cut off from the lid 1 a, and a support frame constituting the support mechanism 2. A plasma torch 4 attached to the support frame 2a, a distance meter 5 fixed to a distance meter fixture 2c of a predetermined length attached to the support frame 2a, and a reference defined on the lid 1a of the tundish 1 The detection rod 6 is generally composed of a point 1b and a detection rod 6 having a length passing through an opening 1aa opened in the lid 1a of the tundish 1 and having an upper end higher than the reference point 1b and a lower end located in the molten steel Y. ing.

  A drive motor 2b is mounted on the upper end of the support frame 2a, and the moving table 3 to which the plasma torch 4 is fixed is mounted so as to be movable up and down according to the drive of the motor 2b along the vertical members constituting the support frame 2a. (X1 direction).

  In the lid 1a of the tundish 1, a reference point 1b is set in the vicinity of the opening 1aa into which the detection rod 6 is put in and out, and at a vertically lower position of the distance meter 5 fixed to the support frame 2a. The laser La emitted from the distance meter 5 is reflected by the reference point 1b, and the distance meter 5 detects the reflected wave and measures the distance L1 between the distance meter 5 and the reference point 1b. The opening 1aa is also an opening through which the plasma torch 4 for irradiating plasma passes. Therefore, a region below the opening 1aa is a plasma heating region.

  As shown in the figure, the support mechanism 2 to which the distance meter 5 is fixed and the lid 1a of the tundish 1 on which the reference point 1b is placed are cut off. Even if the dish 1 is deformed, the absolute position of the distance meter 5 is not affected by the thermal deformation of the tundish 1, and the distance to the reference point 1b on the lid 1a of the tundish 1 after the thermal deformation is measured. can do.

  On the other hand, the distance L2 between the surface S of the molten steel Y having a height H accommodated in the tundish 1 and the reference point 1b is detected by the detection rod 6 by a manual operation by an administrator.

  The detection rod 6 is provided with a memory (not shown), and after a part of the detection rod 6 is immersed in the molten steel Y and taken out, the thickness of the slag layer remaining on the molten steel surface attached to the detection rod 6 is removed. The precise distance L2 to the surface of the molten steel Y is measured by the administrator.

  Since the position of the moving table 3 is specified by the drive motor 2b and the length of the plasma torch 4 attached to the moving table 3 is known, the absolute position of the tip of the plasma torch 4 at any time is specified. Is done.

  The total L3 of the distance L1 measured with the distance meter 5 and the distance L2 manually measured with the detection rod 6 is calculated, and the distance L4 from the distance meter 5 to the tip of the plasma torch 4 is subtracted from the distance L3. A distance L5 from the tip of the torch 4 to the surface S of the molten steel Y is specified.

  Thus, based on the measurement of the distance L1 to the reference point 1b by the distance meter 5 and the measurement of the distance L2 from the reference point 1b to the molten steel surface S using the detection rod 6, the tip position of the plasma torch 4 and the molten steel surface By specifying the distance L5 to S, even if the tundish 1 is thermally deformed and the molten steel height H changes, the distance L5 at the time of measurement can be precisely measured, and the distance L5 is desired. It becomes possible to control to the value. That is, when the specified distance L5 is not the desired value, the motor 2b is driven to raise or lower the plasma torch 4 as desired, and adjustment is performed so that the distance L5 becomes the desired value.

  FIG. 3 is a side view for explaining another embodiment of the method for measuring the distance L1.

  The distance L1 shown in the figure is measured by applying a distance meter fixture 2c 'having a length longer than that of the distance meter fixture 2c shown in FIG. Among them, a reference point 1b ′ is set in the vicinity of a separate opening 1ab located at a position away from the opening 1aa serving as a plasma heating region, the laser La from the distance meter 5 is irradiated in an oblique direction, and a reflected wave is emitted. It detects and measures distance L1 '.

(Embodiment 2 of Plasma Heating Control Device and Control Method)
FIG. 4 is a side view of the second embodiment of the plasma heating control apparatus of the present invention, FIG. 5a is a block diagram illustrating the configuration in the control unit, and FIG. 5b is a relationship graph built in the first control unit. FIG.

  The illustrated plasma heating control apparatus 10A is an apparatus further provided with a load cell 8 for measuring the weight of the tundish 1 and a control unit 7A.

  Due to the supply of molten steel Y from the metal pan N to the tundish 1 and the injection of molten steel Y from the tundish 1 to the mold M, the amount of molten steel in the tundish 1 always fluctuates, and the surface of the molten steel Y accordingly. S also fluctuates. Therefore, for the purpose of specifying the precise distance L5 from the tip of the plasma torch 4 to the surface S of the molten steel by correcting the distance L2 according to the identification result, and identifying the precise distance L5 from time to time. Yes.

  Measurement data in the load cell 8 is transmitted to the control unit 7A as needed. Here, in the control unit 7A, the CPU is connected by a bus to the first control unit in which the relationship graph between the weight of the tundish including the molten steel and the height of the molten steel in the tundish is converted into data and stored. The distance L2 measured by the detection rod and the latest value of the tundish weight W at that time are stored, and the measurement data of the tundish weight W ′ sent from the load cell 8 changing every moment is stored in the first control unit. (U1).

  Based on this measurement data W ', the difference ΔW = W'-W from the latest tundish weight W when measuring L2 with the detection rod is calculated and detected using the relation graph stored in the first control unit The amount of change ΔH from the molten steel surface height H when measured with a rod is calculated as shown in FIG. 5b. With this value, the current distance L2 '= L2 + ΔH is specified.

  When the height H measured with the detection rod changes to H ', the set distance L2 (the molten steel height at this time is H) from the tip of the plasma torch 4 to the molten steel surface S is set to the molten steel height H The torch tip position is moved so that the distance L2 after correction is set to the set distance L2. For example, when H ′ increases by 10 mm from the initial height H, the corrected distance L2 ′ is set to a value obtained by subtracting 10 mm from the initial distance L2, and in accordance with this, the tip position of the plasma torch 4 is also increased by 10 mm. By executing, the distance to the molten steel surface S can be maintained at the initially set desired value.

(Embodiment 3 of Plasma Heating Control Device and Control Method)
FIG. 6 is a side view of Embodiment 3 of the plasma heating control apparatus of the present invention, and FIG. 7 is a block diagram illustrating the configuration in the control unit.

  The illustrated plasma heating control apparatus 10B is an apparatus further provided with an inert gas providing unit 9 that provides an inert gas into the tundish 1 and a control unit 7B.

  In plasma heating, the inside of the tundish 1 is generally set to an inert gas atmosphere (argon gas atmosphere) in order to ensure the life of the tip of the plasma torch 4 during heating (the alloy is mainly composed of tungsten, for example). Is. Therefore, an inert gas providing unit 9 is installed in the tundish 1 so that the inside of the tundish 1 has a desired inert gas atmosphere.

  By the way, when the distance L1 measured by the distance meter 5 has a deviation of a certain value or more from the preset standard value L0 at a certain time, the lid 1a of the tundish 1 is thermally deformed. There is a possibility that argon gas is leaking from the reason such as being present, and there is a high possibility that the inside of the tundish 1 is not in a desired argon gas atmosphere.

  Therefore, as shown in FIG. 7, a second control unit is provided in the control unit 7B, and the measurement data from the distance meter 5 is received by the second control unit (U2). ).

  In the control unit 7B, there are a standard value L0 storage unit for the distance L1 and an error tolerance storage unit for the distance L1 and the standard value L0. From these storage units, the standard value L0 and the error tolerance are the second control unit. Data is transmitted to The second control unit calculates the deviation between the received measurement data from the distance meter 5 (distance L1 at a certain time) and the standard value L0, compares the calculated deviation with the error tolerance, and calculates the error tolerance. When it deviates, it is specified that argon gas is leaking.

  In this case, a command signal for providing a larger amount of inert gas than usual in the tundish 1 is transmitted from the second control unit to the inert gas providing unit 9 (U3). For example, a command signal is transmitted to increase the amount of argon gas blown into the tundish to about 1.5 times the normal amount, and such control is executed.

  At the same time, an alarm signal command is transmitted from the second control unit to the alarm unit, and an alarm is issued to the administrator so that the lid 1a of the tundish 1 is confirmed and maintenance is performed as necessary.

  The plasma heating control devices 10 and 10A shown in FIGS. 1 and 4 do not include the inert gas providing unit 9 like the plasma heating control device 10B, but these devices 10 and 10A do not include the control unit 7B. Even so far, the embodiment including the inert gas providing unit 9 is preferable.

“Product Quality Confirmation Test and Results”
The present inventors conducted an experiment to confirm the quality of the slab to be manufactured both when the conventional plasma heating control device is used and when the plasma heating control device of the present invention is used. In addition, regarding the product quality, whether or not the quality is good is distinguished according to the presence or absence of cracks in the product and the presence or absence of impurities.

  As a result of the experiment, the ignition failure of the plasma torch in the conventional device was 25%, whereas the device of the present invention was greatly improved to 2%. As a result, the fluctuation of the molten steel casting temperature from the target value can be reduced, and the quality of the slab is greatly improved. Specifically, while the product quality acceptance rate with the conventional device was 72%, the product quality acceptance rate with the device of the present invention was greatly improved to 94%.

  The embodiment of the present invention has been described in detail with reference to the drawings. However, the specific configuration is not limited to this embodiment, and there are design changes and the like without departing from the gist of the present invention. They are also included in the present invention.

  DESCRIPTION OF SYMBOLS 1 ... Tundish, 1a ... Lid, 1b, 1b '... Reference point, 1c ... Immersion nozzle, 2 ... Support mechanism, 2a ... Support frame, 2b ... Drive motor, 2c, 2c' ... Distance meter fixing tool, 3 ... Movement 4 ... Plasma torch, 5 ... Distance meter, 6 ... Detection rod, 7A, 7B ... Control unit, 8 ... Load cell, 9 ... Inert gas supply unit, 10, 10A, 10B ... Plasma heating control device, N ... Take Pan, M ... mold, Y ... molten steel, S ... surface of molten steel, SP ... slab

Claims (6)

A plasma heating control device for controlling plasma heating of molten steel contained in a tundish of a continuous casting machine,
A support frame provided above the tundish lid and at a position cut off from the lid;
A plasma torch attached to the support frame so as to freely advance and retract;
A rangefinder attached to the support frame;
A reference point defined on the tundish lid,
A detection rod having a length passing through an opening formed in the tundish lid, the upper end being higher than the reference point and the lower end being located in the molten steel;
A control unit, and
The control unit uses the total distance of the distance L1 from the distance meter measured by the distance meter to the reference point and the distance L2 from the reference point measured by the detection rod to the surface of the molten steel. Plasma heating control device that controls the tip position. A first control unit storing a relationship graph between the weight of the tundish containing molten steel and the height of the molten steel in the tundish;
A load cell for measuring the weight of the tundish containing molten steel, and
The measurement data in the load cell is transmitted to the first control unit, the height of the molten steel corresponding to the measurement data received by the first control unit is specified from the relation graph, and the height of the specified molten steel is determined. Correct the distance L2 to identify the corrected distance L2,
The plasma heating control device according to claim 1, wherein the tip position of the plasma torch is controlled using a total distance of the distance L1 and the corrected distance L2. An inert gas providing unit for providing an inert gas in the tundish;
A second control unit for storing a standard value L0 of the distance L1 and an allowable value of an error between the distance L1 and the distance L0;
The measured value of the distance L1 is transmitted to the second control unit, and when the distance L1 deviates from the allowable value, a larger amount of inert gas than usual is tundished from the second control unit to the inert gas providing unit. The plasma heating according to claim 1 or 2, wherein a command signal to be provided is transmitted, and a signal for issuing an alarm is transmitted from the second control unit to the alarm unit. Control device. A plasma heating control method for controlling plasma heating of molten steel contained in a tundish of a continuous casting machine,
A plasma torch is attached to a support frame provided at a position above the lid of the tundish and cut from the lid, and a distance meter is attached,
Define a reference point on the tundish lid,
Through the opening opened in the lid of the tundish, a detection rod having a length where the upper end is higher than the reference point and the lower end is located in the molten steel,
The distance L1 from the distance meter to the reference point is measured with a distance meter, the distance L2 from the reference point to the surface of the molten steel is measured with a detection rod, and the tip of the plasma torch is measured using the total distance L1 and L2. Plasma heating control method for controlling position. Obtain in advance a relationship graph between the weight of the tundish containing molten steel and the height of the molten steel in the tundish,
Measure the weight of the tundish containing molten steel at any time with the load cell,
The measurement data in the load cell is transmitted to the first control unit, and the height of the molten steel corresponding to the measurement data received by the first control unit is specified from the relation graph, and according to the specified height of the molten steel Correct the distance L2 to identify the corrected distance L2,
The plasma heating control method according to claim 4, wherein the tip position of the plasma torch is controlled using the total distance of the distance L1 and the corrected distance L2. Plasma heating is performed with an inert gas atmosphere in the tundish,
The standard value L0 of the distance L1 and the tolerance value of the error between the distance L1 and the distance L0 are specified in advance,
5. When the measured value of the distance L1 deviates from the allowable value, a larger amount of inert gas than usual is provided in the tundish, and an alarm is given that the inert gas is leaking from the tundish. 5. The plasma heating control method according to 5.

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