JPH09253815A - Device for adjusting molten metal quantity in ladle in continuous caster - Google Patents

Abstract

PROBLEM TO BE SOLVED: To surely prevent the flow-out of a slag with a control device at the outside without arranging a stopper in a ladle, efficiently adjust molten metal quantity remained in the ladle and improve the yield, at the time of pouring the molten metal in the ladle into a tundish. SOLUTION: This control device is constituted with an SN device 5 for adjusting the molten steal flow-out quantity from a steel pouring hole 4 at the bottom part of the ladle 1, a wt. detecting instrument 11 for measuring the molten steel quantity in the ladle and a slag detecting instrument 10 for detecting the slag flowed out from the steel pouring hole at the bottom part of the ladle. Then, at the time of lowering the molten metal quantity in the ladle to a first setting level W1 having the possibility to develop eddy current accompanied with the flow-out of the molten steel in the ladle, the detection of the slag is started by the control device 13, and at the time of detecting the slag or at the time of lowering the molten steel quantity in the ladle to a second setting level W2 surely developing the eddy current, a high speed closing signal is outputted to the SN device 5 to once stop the pouring. After passing the setting time S, an opening signal is outputted to the SN device 5 to restart the pouring, and at the time of detecting the slag, the high speed closing signal is outputted to the SN device 5 to complete the pouring of the molten steel from the ladle.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to slag in a ladle that is engulfed by a vortex generated when the molten metal flows out when the molten metal is taken out from a bottom tap of a ladle filled with the molten metal, and the slag flows out together with the molten metal. The present invention relates to an apparatus for adjusting the amount of molten metal in a ladle of a continuous casting machine, which prevents the occurrence of melt and controls the amount of molten metal remaining in the ladle.

[0002]

2. Description of the Related Art In a continuous casting machine in the steelmaking process,
The molten steel in the refined ladle is poured into the tanninsh as an intermediate container while adjusting the outflow amount of the molten steel from the tap hole provided at the bottom of the ladle by the opening / closing control device (sliding nozzle device), and further in the tandinsh. The molten steel is flow-controlled by an opening / closing control device and poured into a mold to continuously produce ingots. In this manufacturing process, what is important in producing clean steel slabs is to prevent the slag floating on the molten steel in the ladle from flowing out when pouring the molten steel from the ladle into the tundish. That is.

The outflow of slag from the ladle into the tundish is that the levitation slag is entrained by the vortex generated near the tap hole in the ladle due to the decrease in the amount of molten steel in the ladle, and flows out together with the molten steel. Time delay until the nozzle of the opening / closing control device at the bottom of the ladle is closed using a power source such as hydraulic pressure after detecting the slag by the slag detector installed at the tap hole at the bottom of the ladle or by human visual judgment. Due to the outflow of slag.

Various methods have been conventionally proposed as a method for preventing such slag outflow, for example, JP-A-60-210352 and JP-A-62-2036.
In the slag outflow prevention method of Japanese Patent No. 67, the floating valve whose specific gravity is adjusted is positioned at the slag-molten steel interface just above the tap hole at the time when the molten steel level in the ladle decreases and a swirl occurs. The generation of swirl is prevented to prevent the slag from being caught, and at the end of the injection, the floating valve is landed on the tap hole, and the tap hole is closed to prevent the floating slag from flowing out.

Further, Japanese Examined Patent Publication No. 6-42987 is an improvement of the floating valve system. When the level of the molten metal in the ladle is lowered to about 700 mm before the swirl occurs, the stopper is lowered to position it on the tap hole. Then, it is stopped and then raised and held by about 30 to 100 mm, and when the molten steel weight in the ladle suddenly changes, it is lowered to close the tapping port.

[0006]

However, in all of these methods, it is necessary to dispose a stopper, an elevating device, etc. inside the ladle or outside the ladle to prevent eddy currents and close the tap hole. The inside of the ladle and its surroundings are extremely hot, and the cost is enormous considering the heat countermeasures, repairs, and consumable parts of the equipment, facilities, and peripheral equipment. Also,
In order to prevent the outflow of slag, there is a method of stopping the outflow of molten steel immediately before the generation of swirl, but the molten steel remains in the ladle together with the slag, resulting in a decrease in yield.

The present invention has been made to solve the above-mentioned problems, and an object thereof is to prevent the outflow of slag by an external control device without disposing a stopper in the ladle. Another object of the present invention is to provide an apparatus for adjusting the amount of molten metal in a ladle in a continuous casting machine, which can efficiently control the amount of molten metal remaining in the ladle and improve the yield.

[0008]

MEANS FOR SOLVING THE PROBLEMS An apparatus for adjusting the amount of molten metal in a ladle in a continuous casting machine according to the present invention comprises an opening / closing control device for adjusting the amount of molten metal flowing out from a tap hole at the bottom of the ladle, and a molten metal in the ladle. A weight detection device capable of measuring the amount, a slag detection device capable of detecting slag flowing out from the tap hole at the bottom of the ladle, and a control device for controlling the opening / closing control device based on a detection signal of the detection device. When the amount of molten metal in the ladle decreases to a first set level W ₁ at which a swirl may occur in the molten metal in the ladle due to molten metal outflow, the control device starts detecting slag and detects slag, Alternatively, when the amount of molten metal in the ladle drops to the second set level W ₂ at which eddy current is always generated, a high-speed closing signal is output to the opening / closing control device, and an opening signal is output to the opening / closing control device after the set time has elapsed to detect slag. Then, the switching controller is closed at high speed. Is output.

In the above-mentioned structure, when the molten metal flows into the tundish and the level of the molten metal in the ladle is lowered, the weight of the molten metal in the ladle is lowered to the first set level W ₁ , and the apparatus is started. However, the slag detector goes into standby mode,
Subsequent slag outflow can be reliably detected. Furthermore, when the molten metal level drops, a swirl is generated due to the flow velocity of the molten metal in the ladle, and the slag floating on the molten metal surface is caught and begins to flow out, which is detected by the slag detection device and the slag detection signal is controlled. Output to the device. Alternatively, the slag outflow is visually detected, and a human signal visually is output to the control device. Alternatively, the slag detection signal is output when the second set level W ₂ at which the eddy current always occurs and the slag flows out without performing the detection of the first set level W _{1 and} the detection of the slag.

When the slag detection signal is input to the control device, the control device sends a quick closing signal to the hydraulic device which is the power source of the opening / closing control device such as the sliding nozzle device, and the opening / closing control device closes once. . Since the outflow of the molten metal in the ladle is once stopped, the vortex flow is stopped and the slag floats above the molten metal, and the outflow of the slag into the tundish can be prevented. When the set time has elapsed, the control device sends a signal to the opening / closing control device to open to the set opening,
The molten metal in the ladle starts to flow out again and is poured into the tundish. When the slag detection or the human signal is input again, the opening / closing control device is quickly closed, and the ladle is finished.

In the present invention, since the molten metal injection is temporarily stopped by the first slag detection or the like, the slag-molten metal interface is restored to be smooth, then the injection is restarted, and the ladle is finished by the second slag detection. It is possible to reliably prevent the outflow of slag, and it is possible to reduce the amount of residual hot water in the ladle by a corresponding amount between the re-injection and the second detection of slag, and as a result, the yield can be improved. it can.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described in detail below with reference to an embodiment shown in the drawings. This is an example of injecting molten steel into a tundish from a ladle in continuous casting of steel, and FIG. 1 shows an example of an upper part of a continuous casting machine in which a device for adjusting the amount of molten metal in a ladle according to the present invention is installed. FIG. 2 is a block diagram showing the device configuration. FIG. 3 shows changes in the molten metal amount according to the present invention, and FIG. 4 shows a flowchart of the control device.

In FIG. 1, a ladle 1, a tundish 2 and a mold 3 are arranged in this order from the top on the upper part of the continuous casting machine, and the molten steel A in the ladle 1 is a tap hole 4 at the bottom of the ladle 4. A sliding nozzle device (hereinafter referred to as an SN device) as an opening / closing control device 5, a tundish injection pipe 6 (or a long nozzle) is injected into the tundish 2, and molten steel in the tundish 2 is injected into the SN device 7. It is cast into the mold 3 through the immersion nozzle 8. The tapping port 4 is formed in an upper nozzle made of bricks embedded in the bottom of the ladle 1, and the SN device 5 of the ladle uses a slide plate as an SN such as a hydraulic cylinder for a fixed plate having a lower nozzle. The structure is such that the SN hole 5a is opened / closed by sliding with the driving device 9.
An injection hole of the ladle 1 is formed by the SN hole 5a.

In such a continuous casting machine, the slag detector 10 is embedded in the brick at the bottom of the ladle surrounding the tap hole 4 or in the upper part of the SN device 5 surrounding the SN hole 5a. Also,
The ladle 1 is provided with a ladle weight detector 11 capable of detecting the ladle weight, that is, the weight of molten steel in the ladle, and the tundish 2 is provided with a tundish weight detector 12. The detection signal of each detector is input to the control device 13. The control device 13 has a built-in sequencer, and the hydraulic device 14 of the SN device 7 is controlled based on the detection result.

The slag detector 10 uses, for example, a sensor for measuring the voltage generated in the receiving coil by inducing an eddy current in the molten steel when an alternating current is passed through the transmitting coil. Since the eddy current is inversely proportional to the volume ratio of the slag B to the molten steel A, it can be detected that the slag is mixed in the molten steel. Needless to say, the slag detector 10 is not limited to this, and other slag detectors can be used. Further, the weight detectors 11 and 12 are load cells provided on a trunnion shaft which is a supporting member of a ladle or a tundish, and the amount of molten steel in the ladle and the like can be known by a difference from the empty weight of the ladle or the like. .

The detection signal of the slag detector 10 is input to the control device 13 for controlling the hydraulic device 14 of the SN drive device 9 via a connector, a preamplifier and the like. Control device 13
A slag detection threshold is set in advance, and when the measured value exceeds this threshold, a slag detection signal is output to the hydraulic device 14. Further, the control device 13 controls the first set level W ₁ of the ladle internal weight where swirl may occur in the molten steel in the ladle, the second set level W ₂ of the ladle internal weight where swirl always occurs, such as setting time S for holding the closed state of the SN hole 5a of the ladle in the third setting level W ₃ of the weight or the SN device 5, for the pot ends is settable.

With the above-mentioned structure, the molten steel injection control in the ladle is performed by the following procedure (see FIGS. 3 and 4).

(1) The SN device 5 is normally hydraulically controlled by the control device 13 and the SN drive device 9, and the molten steel A in the ladle 1 is controlled.
Is poured into the tundish 2, and the molten steel level in the ladle is lowered accordingly, and the weight of the ladle 1 is lowered. The weight in the ladle is detected by the ladle weight detector 11, and there is a possibility that a swirl may occur in the molten steel in the ladle.
_When it reaches ₁ (a level at which a vortex flow occurs, for example, 70 t), the sequencer in the control device 13 sets the slag detector 10 in a standby state and starts slag detection. The state of molten steel A and slag B at this time is shown in FIG.

(2) When the level of the molten metal further decreases and the state shown in FIG. 3B is reached, a vortex is generated near the top of the tap hole 4, and the slag B is caught in the molten steel A and starts to flow out. The slag detector 10 detects this, and this slag detection signal is transmitted to the control device 13. Upon receiving the slag detection signal, the control device 13 immediately outputs a command to the hydraulic device 14 to close the SN device 5 at high speed (high pressure).

(3) The hydraulic system 14 is switched to the high pressure side,
The SN driving device 9 is pushed out in the closing direction at high speed to close the SN hole 5a of the SN device 5. As a result, as shown in FIG. 3C, the eddy current is stopped when the outflow of the molten steel A is stopped, and the slag B is floated on the upper surface of the molten steel.

The SN hole 5a of the SN device 5 is closed for a predetermined set time S (a time such that the molten steel A does not solidify at the tap hole and the slag is sufficiently floated, for example, 1.8 seconds). Is retained.

(4) When the set time S has elapsed, the control device 13 outputs a command to the hydraulic device 14 to open the SN device 5 at a low speed (low pressure). The hydraulic device 14 switches to low pressure, moves the SN drive device 9 in the opening direction, and opens the SN hole 5a of the SN device 5 (for example, 80% opening). The SN device 5 is normally hydraulically controlled, and the molten steel A in the ladle flows out again into the tundish 2. When the molten metal surface further decreases, the slag layer approaches the bottom of the ladle, and the slag B starts to flow out together with the molten steel A, the slag detector 10 detects the slag B again,
The detection signal is transmitted to the control device 13. Control device 13
Outputs a high-speed closing command to the SN driving device 9, closes the SN hole 5a of the SN device 5 at high speed, and as shown in FIG.

The above is the case of the automatic operation by the automatic weight detection at the first set level W ₁ , the first automatic slug detection and the second automatic slug detection, but not limited to this, the first or second slug. Instead of automatic detection, a sequence of control devices may be arranged so that artificial slag detection can be performed on the way. In this case, after the automatic weight detection at the first setting level W ₁ , the slag is visually detected and the push button is turned on to input the slag detection signal to the control device. After the injection is restarted, the slag is visually detected and a slag detection signal is similarly input to the control device.

Further, instead of the first slag detection, it is possible to use the second set level W ₂ in which the eddy current is always generated. In this case, without performing automatic weight detection at the first set level W ₁ , the SN device 5 is closed at a high speed at the same time as the weight in the ladle reaches the second set level W ₂ . After that, the second automatic slag detection and the like are performed as described above. Further, instead of the second slag detection, the third setting level W ₃ (for example, 0.3 t) may be used, and the ladle may be ended by this.

As described above, the amount of molten steel in the ladle can be adjusted while preventing the slag from flowing out of the ladle 1.
FIG. 5 shows an example in which the amount of residual steel in the ladle of a 300T ladle is compared between the present invention and the conventional one, and 4.8t is 4.
It was 0t, and the yield could be improved.

In the above, the case where molten steel is poured from the ladle into the tundish has been described, but the present invention is not limited to this, and the present invention is also applicable to the case where molten metal is poured into another container from the ladle. Can be applied. Further, the slag detector is not limited to the transmission / reception coil system, and any sensor that can distinguish between slag and molten metal can be used.

[0027]

As described above, the present invention starts detecting slag when the amount of molten metal in the ladle drops to the first set level at which swirl may occur in the molten metal in the ladle due to the outflow of molten metal. When slag is detected, or when the amount of molten metal in the ladle drops to the second set level where swirl flow always occurs, a high-speed closing signal is output to the opening / closing control device, and an opening signal is output to the opening / closing control device after the set time has elapsed. When the slag is detected, the high-speed closing signal is output to the opening / closing control device, so that the following effects are obtained.

(1) It is possible to reliably prevent the outflow of slag by an external control device without disposing a stopper or the like in the ladle, and eliminating the conventional heat countermeasures, repairs, consumable parts, etc. Therefore, the outflow of slag can be prevented with a low-cost device.

(2) The amount of molten metal remaining in the ladle can be efficiently adjusted to prevent the outflow of slag and improve the yield.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing a molten metal amount adjusting device in a ladle according to the present invention.

FIG. 2 is a block diagram of the molten metal amount adjusting device in the ladle shown in FIG.

FIG. 3 is a graph and a sectional view showing changes in the amount of molten metal in a ladle according to the present invention.

FIG. 4 is a flowchart of a control device of the molten metal amount adjusting device in a ladle according to the present invention.

FIG. 5 is a graph comparing the amount of residual steel in a ladle between the present invention and a conventional one.

[Explanation of symbols]

 A ... molten steel (molten metal), B ... slag, 1 ... ladle 2 ... tundish 3 ... mold 4 ... tapping mouth 5 ... ladle sliding nozzle device (opening / closing control device) 5a ... sliding nozzle hole 6 ... tundish Injection pipe 7 ... Tundish sliding nozzle device 8 ... Immersion nozzle 9 ... Sliding nozzle drive device 10 ... Slag detector 11 ... Ladle weight detector 12 ... Tundish weight detector 13 ... Controller 14 ... Hydraulic system

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI technical display location B22D 39/04 8719-4K B22D 39/04 41/22 8719-4K 41/22

Claims (1)

[Claims] 1. An opening / closing control device for adjusting the amount of molten metal flowing out from the tap hole at the bottom of the ladle, a weight detection device capable of measuring the amount of molten metal in the ladle, and a slag flowing out from the tap hole at the bottom of the ladle. Slag detection device capable of detecting, and a control device for controlling the opening and closing control device based on the detection signal of the detector unit, the control device, the amount of molten metal in the ladle to the molten metal in the ladle outflow. Opening / closing control is started when slag detection is started when slag is detected when the level drops to the first set level at which eddy current may occur, or when the amount of molten metal in the ladle drops to the second set level where eddy flow is always generated. The molten metal in the ladle in the continuous casting machine is characterized in that it outputs a high-speed closing signal to the equipment, outputs an opening signal to the opening and closing control device after the lapse of a set time, and outputs a high-speed closing signal to the opening and closing control device when slag is detected. Quantity adjustment device.