JPH08257712A - Method and device for feeding wire-additive in continuous casting - Google Patents

Abstract

PURPOSE: To enable the feed and the stop in the suitable time to a wire-additive for executing the shape-control and the reform of non-metallic inclusion in molten steel pouring into a mold, in a continuous casting. CONSTITUTION: A feeding device for wire is constituted by arranging a wire insert hole 5 at the core part of a stopper 4 for opening/closing a discharging nozzle 3a in a tundish 3 arranged above the mold 1 through a pouring nozzle 2 so as to feed the wire fed from a wire feeding reel 9 into the pouring nozzle from the wire insert hole. Further, a tip polishing machine 6 for wire-additive at the upper part of the stopper, inert gas supplying device 7 and a wire-feeder 10 reciprocable to between the tip polishing machine and the wire feeding reel, are arranged. By this method, the feed of the additive in the suitable time even during casting can be executed, and the lowering of unit consumption, the fining of grain developed by the reaction and the improvement of the quality in a cast slab, can be obtd.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a wire additive supply method and apparatus for controlling the shape and modifying the nonmetallic inclusions in molten steel injected into a mold during continuous casting.

[0002]

2. Description of the Related Art In continuous casting of steel, non-metallic inclusions such as alumina (Al ₂ O ₃ ) mixed in molten steel are very hard and have a high melting point. If it is rolled as it is, this will remain as a surface flaw (sliver flaw) of the product, which is not preferable in terms of quality.

As a means for modifying these hard inclusions, for example, by adding Ca as an additive, alumina is soft and has a low melting point of (Al ₂ O ₃ ) _m (CaO) _n.
To prevent the occurrence of surface defects during rolling.

As a method of adding this additive to molten steel, conventionally, for example, a method has been taken in which massive Ca is directly put into a ladle or a tundish of molten steel and reacted with alumina. However, in general, the specific gravity of the added substance is smaller than that of molten steel, so even if it is put into a ladle or tundish as it is, it floats on the surface and does not melt and react normally, which is inefficient and wasteful. there were.

In the case of an additive such as Ca, it has a low solubility in molten steel, has a low boiling point, and is easily gasified. Therefore, it is necessary to push it into a position where the flow velocity of molten steel is as fast as possible.
Therefore, it is effective to linearize the additive. Therefore, this is made into a wire shape, and when it is intended to be added only to a specific part of a cast piece, for example, a bottom piece (B piece), it is supplied in a mold or in a dipping nozzle with a high molten steel flow rate. However, it is effective in reducing the waste of additives and further reducing the chance of contamination such as oxidation.

[0006] In this case, inserting from the molten metal surface in the mold causes disturbance of the molten metal surface and increases the risk of powder entrapment. Therefore, at present, the wire feeding method in the dipping nozzle for rapid melting and mixing is used. Considered the best option.

As a means for supplying the wire-shaped additive into the immersion nozzle, for example, US Pat. No. 4,520,861 is used.
(Jun, 4.1985) discloses a method and apparatus for continuously feeding an alloy wire into a dipping nozzle through a stopper rod in continuous casting.

[0008] In this technique, in the initial stage of casting, the molten steel penetrates into the wire conduit provided on the stopper rod.
In order to prevent the blockage due to coagulation, the apparatus shown here is provided with an introduction hole 14a in the stopper rod 14 for opening and closing the discharge nozzle 13a at the bottom of the tundish 13 as shown in FIG. Wire as an agent 15
To pass through.

Next, the wire additive 15 supplied from the wire feeder 20 is fed into the immersion nozzle 12 through the stopper rod 14 so that the additive is supplied to the molten steel 21. In the figure, 1 is a mold, 17
Is an inert gas supply device, and 18 is a wire insertion tube.

[0010]

By the way, this device is
The wire 15 as an additive is fed from the stopper rod 14 in parallel with the molten steel, and the amount of the additive according to the injection amount of the molten steel can be supplied, and the supplied wire is assisted by the flow of the molten steel. Since it dissolves in the immersion nozzle 12, it is effective in reducing the basic unit of the additive and making the additive particles finer.

However, this structure has no problem when the additive is continuously supplied. For example, when the supply of the additive is stopped in the middle and the supply is restarted, the supply mechanism having a thin wire tip portion is used. There is a problem that the wire feeding becomes impossible because it is stuck inside.

The present invention has been made in view of the above-mentioned problems, and at the time of shape control and reforming of molten steel in continuous casting, it is possible to feed / stop a wire additive which is vertically fed through a stopper in a tundish. The above-mentioned supply method and device are provided.

[0013]

According to the method of the present invention, a tundish is provided on the upper part of a continuous casting mold through a dipping nozzle, and a wire is attached to the core of a stopper for opening and closing a discharge nozzle attached to the bottom of the tundish. An introduction hole is provided, and the wire additive fed from the wire feed reel is fed into the immersion nozzle through the introduction hole to control the shape of the injected molten steel inclusions and supply the wire additive. In the method, when the supply of the wire additive is stopped, the wire is temporarily pulled up to the upper position of the stopper, the feed path of the wire is pressurized and filled with an inert gas, and the additive is again introduced into the hole as needed. This is a method of supplying the wire additive in continuous casting, characterized in that the morphology of the inclusions in the molten steel is controlled and modified by further feeding.

Further, according to the present invention, a tundish is provided on an upper part of a continuous casting mold through a dipping nozzle, and a wire introducing hole is provided at a core part of a stopper which opens and closes a discharge nozzle attached to a bottom part of the tundish. In the method of supplying the wire additive fed from the supply reel into the immersion nozzle through the introduction hole to control the shape of the injected molten steel inclusions and to modify, the upper part of the stopper. A wire additive tip polisher is installed in the machine, and when the supply of the wire additive is stopped, the wire is pulled up to the tip polisher position to polish the tip of the wire, and an inert gas is used in the wire feed path. Is filled under pressure, and the additive is fed again through the introduction hole as needed to control the morphology of the inclusions in the molten steel and modify it. A method of supplying over additives.

According to the method of the present invention, a tundish is provided on the upper part of a continuous casting mold through a dipping nozzle, and a wire introducing hole is provided at the core of a stopper for opening and closing a discharge nozzle attached to the bottom of the tundish. In a wire additive supply device for supplying the wire additive supplied from a supply reel into the immersion nozzle through the introduction hole, an inert gas supply device is provided above the stopper, the tip polishing machine and the wire transfer device. A wire additive supply device for continuous casting, characterized in that a reciprocable wire feeder is provided between the supply reels.

In the apparatus of the present invention, a tundish is provided on the upper part of the continuous casting mold through a dipping nozzle, and a wire introducing hole is provided in the core of a stopper for opening and closing a discharge nozzle attached to the bottom of the tundish. A wire additive supply device for supplying a wire additive sent from a wire supply reel into the dipping nozzle through the introduction hole, wherein a wire additive tip polisher and an inert gas supply device are provided above the stopper. And a wire feeder capable of reciprocating between the tip polishing machine and the wire feed reel, the wire additive supply device in continuous casting.

Further, in the above wire additive supply device, the wire additive tip grinder is composed of a fan-shaped rotary grinder divided in the circumferential direction, and converges in the central portion during polishing, and when passing through the wire. Is a structure that radiates in the radial direction.

[0018]

The present invention solves the drawback of the conventional wire additive feeder, which makes it impossible to restart the wire feed during the operation, and therefore the tundish. It allows the wire to wait on top of the stopper or is equipped with a wire additive tip polisher.

With this structure, after the supply of the wire is stopped, the wire feeder is operated to temporarily pull up the wire from the inside of the stopper to the position above the stopper or the position of the tip grinder, and at the end of the wire, the small ball at the time of solidification can be formed. Is sharpened and sharpened by a polishing machine to prevent the wire from being caught when it is re-supplied, so that the wire can smoothly descend in the introduction hole.

Further, when the wire supply is stopped, the wire is pulled up and retracted from the stopper to suppress the softening, strength reduction and adhesion of the coating metal due to the heat effect of the molten steel in the tundish, and at the same time prevent the deterioration of the additive. Further, during this period, an inert gas such as Ar is supplied from the inert gas supply device to the wire feeding path to perform purging to prevent molten steel from entering the feeding path such as the introduction hole in the stopper. Makes it easier to insert the wire when resupplying.

As described above, when the additive is added to the molten steel in the mold to control and modify the shape of the molten steel, it is possible to stop and feed the wire additive to be supplied at a proper time, so that the specific portion of the slab is simply Not only (for example, B piece), but also during casting, it is possible to add it in a timely manner as needed, and it is possible to improve the quality of the cast piece together with the reduction of the basic unit of additive and the miniaturization of particles.

[0022]

EXAMPLE FIG. 1 (a) is a schematic side sectional view showing an example of a wire additive supply device of the present invention, and FIG. 1 (b) is a detailed view of a portion A showing a wire tip polishing machine.

In this apparatus, a tundish 3 is provided on an upper part of a continuous casting mold 1 through a dipping nozzle 2, and a core of a stopper 4 for opening and closing a discharge nozzle 3a provided at the bottom of the tundish 3 has a wire. An introduction hole 4a for the additive 5 is provided.

Immediately above the stopper 4, a wire additive tip polishing machine 6 is connected, and an insertion tube 8 is connected to an inert gas supply device 7 such as Ar gas. As shown in FIG. 1B, for example, the tip grinder 6 is composed of a fan-shaped rotary grinder 6a divided in the circumferential direction, and the grinder is converged to the center during polishing. When passing through the wire, the structure is such that it radiates in the radial direction.

Reference numeral 9 denotes a wire feed reel, and a wire feeder 10 which can reciprocate is provided between the wire feed reel 9 and the tip polishing machine 6. Further, the wire introducing portion 8a on the proximal end side of the insertion tube 8 is kept airtight in order to block outside air.

The wire additive supply device is configured as described above, and at the initial stage of casting, the wire introduction hole outlet at the tip of the stopper 4 is closed with a soluble metal such as aluminum foil or a thin copper plate, and the immersion nozzle 2 The molten steel 12 inside is prevented from flowing back into the introduction hole 4a.

Then, together with the injection of the molten steel, the additive 5 is sent out from the wire feeding reel 9 into the dipping nozzle 2 through the introduction hole 4a, and is mixed there with the molten steel and discharged into the mold 1 to form inclusions in the molten steel. Control and reform.

Calcium (Ca) is often used as an additive for controlling the shape and modification of inclusions in molten steel. Bismuth (Bi), lead (P
b), boron (B), titanium (Ti), etc. may be used. These additives are coated with a steel tube and the outer diameter is 7
It is stretched to about 8 mmφ and used as a wire.

When the supply of the additive is stopped or interrupted here, the supply of the additive 5 from the wire supply reel 9 is stopped and at the same time, the Ar gas from the inert gas supply device 7 is stopped.
The supply pressure of the equal inert gas is increased to pressurize and fill the feed path of the wire with the inert gas, and the reverse flow of the molten steel from the introduction hole 4a is suppressed.

Subsequently, the wire feeder 10 is reversed to pull up the wire 5 until the tip of the wire reaches the position of the tip grinder 6, where the tip grinder 6 is operated.
The small spheres at the time of solidification, which can be formed at the tip of the wire when stopped, are sharply ground with a grinder, and after grinding, the wire is made to stand by at this position.

If it is necessary to supply the additive again to control the morphology of the molten steel and reform the molten steel, the wire additive 5 may be fed as it is, and the tip of the wire is polished so that the introduction hole 4a can be easily formed. It can be passed through to and sent out into the immersion nozzle 2.

[0032]

As described above, according to the method and apparatus for supplying a wire additive of the present invention, the supplied wire additive is rapidly melted by the flow of the molten steel in the immersion nozzle, and the molten steel is melted. Since the additives are uniformly stirred inside, the additives react effectively without waste, and the unit consumption of the additives can be reduced and the additives can be uniformly dispersed.

Further, by installing a wire tip grinder on the upper part of the stopper so that the wire additive to be supplied can be stopped and fed at a proper time, not only at a specific portion of the cast slab but also during casting. Since the additive can be added to a necessary portion in a timely manner and the additive can be efficiently supplied without waste, the basic unit of the additive can be reduced, the non-metallic inclusion particles generated by the reaction can be miniaturized, and the quality of the slab can be improved.

[Brief description of drawings]

1 shows an embodiment of the present invention, FIG. 1 (a) is a schematic side sectional view showing the entire wire additive supply device, and FIG. 1 (b) is a detailed view of a portion A showing a wire tip polishing machine. .

FIG. 2 is a schematic side sectional view showing a conventional example of a wire additive supply device.

[Explanation of symbols]

 1 Mold 2, 12 Immersion Nozzle 3,13 Tundish 3a, 13a Discharge Nozzle 4,14 Stopper 4a, 14a Introductory Hole 5,15 Wire Additive 6 Tip Polishing Machine 6a Rotating Grinder 7,17 Inert Gas Supply Device 8,18 Wire insertion tube 8a Wire introduction part 9 Wire feeding reel 10,20 Wire feeder 11,21 Molten steel

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁶ Identification number Internal reference number FI technical display location // B22D 1/00 B22D 1/00 E (72) Inventor Shio Kiyomi 20-1 Shintomi, Futtsu-shi New Nippon Steel Co., Ltd. Technical Development Division (72) Inventor Kiyoshi Isono 1 Fujimachi, Hirohata-ku, Himeji-shi Hirohata Works, Nippon Steel Co., Ltd.

Claims (5)

[Claims] 1. A tundish is provided on an upper part of a continuous casting mold through a dipping nozzle, and a wire introduction hole is provided at a core part of a stopper which opens and closes a discharge nozzle attached to a bottom part of the tundish. In the method of feeding the wire additive, which feeds the fed wire additive into the immersion nozzle through the introduction hole to control the morphology and reform of the injected molten steel inclusions, the supply of the wire additive is stopped. When the wire is pulled up to the upper position of the stopper, an inert gas is pressure-filled in the wire feeding path, and the additive is fed again from the introduction hole as needed to again introduce inclusions in the molten steel. A method for supplying a wire additive in continuous casting, characterized by performing morphology control and modification. 2. A tundish is provided on an upper part of a continuous casting mold through a dipping nozzle, and a wire introducing hole is provided at a core part of a stopper which opens and closes a discharge nozzle attached to a bottom part of the tundish. In the method of feeding the wire additive, which feeds the fed wire additive into the immersion nozzle through the introduction hole to control and modify the shape of the injected molten steel inclusions, wire is added to the upper part of the stopper. A tip polisher for the agent is installed, and when the supply of the wire additive is stopped, the wire is temporarily pulled up to the position of the tip polisher to polish the tip of the wire, and an inert gas is pressurized in the wire feed path. A method for supplying a wire additive in continuous casting, which comprises filling and again supplying an additive through an introduction hole as needed to control the shape and reforming of molten steel. 3. A tundish is provided on an upper part of a continuous casting mold through a dipping nozzle, and a wire introduction hole is provided at a core part of a stopper which opens and closes a discharge nozzle attached to a bottom part of the tundish. In the wire additive supply device for supplying the fed wire additive into the dipping nozzle through the introduction hole, an inert gas supply device is provided above the stopper, and the tip polishing machine and the wire feed reel are connected to each other. An apparatus for supplying a wire additive in continuous casting, which is provided with a wire feeder capable of reciprocating. 4. A tundish is provided in the upper part of a continuous casting mold through a dipping nozzle, and a wire introduction hole is provided in a core portion of a stopper which opens and closes a discharge nozzle attached to the bottom of the tundish. In a wire additive supply device for supplying the fed wire additive into the immersion nozzle through the introduction hole, a wire additive tip polishing machine and an inert gas supply device are provided above the stopper, and the tip polishing is performed. An apparatus for supplying a wire additive in continuous casting, characterized in that a reciprocating wire feeder is provided between the machine and the wire feeding reel. 5. A wire additive tip grinder is composed of a fan-shaped rotary grinder divided in the circumferential direction,
The wire additive supply device according to claim 4, wherein the wire additive is converged to a central portion during polishing, and is radiated in a radial direction when passing through the wire.