JP3361044B2 - Lower nozzle for slide gate - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a lower nozzle for a slide gate used for adjusting the flow rate of molten metal,
Particularly, the present invention relates to a nozzle tip structure with improved durability.

[0002]

2. Description of the Related Art In recent years, in a steelmaking process, in many cases, a continuous casting method is adopted in which molten steel is continuously poured into a mold from a ladle through an intermediate container for distribution called a tundish. In this method, a mechanism for supplying molten steel from the ladle to the casting machine side at an appropriate flow rate is important, and a slide gate is used as one of such flow rate control mechanisms.

This slide gate is usually provided with two upper and lower nozzles forming a molten steel flow path from the ladle to the tundish or from the tundish to the mold, and a hole for the molten steel flow path which is arranged between the two nozzles. It is composed of a plurality of plate-shaped refractory materials that it has, and the molten steel flow rate is controlled by sliding each plate-shaped refractory material in the horizontal direction to adjust the overlapping state of the holes.

FIG. 6 illustrates a lower nozzle of a slide gate (hereinafter referred to as "SG lower nozzle", if necessary) attached to the bottom of a ladle. The tip portion of the lower nozzle 100 has heat conduction from the molten steel in the flow path FL, and a tundish (TD) 10 to which the molten steel is supplied.
Since the radiant heat from 1 is also received, cracks due to spalling or oxidation are more likely to occur than other structural elements. Moreover, once a crack is generated and it expands, there is a possibility that a part of the refractory brick 102 constituting the main body of the nozzle 100 may be melted or dropped along the crack.

Therefore, in the SG lower nozzle 100, it is particularly important to prevent the cracks generated from expanding and improve the durability. As one of such methods, as shown in FIG. A method has been proposed in which a metal case 104 is attached to the outer peripheral portion via a mortar 103 and the restraining force of the case 104 is utilized.

[0006]

However, the number of hot uses of the conventional SG lower nozzle has been increasing steadily. Therefore, the metal case is exposed to a higher temperature than in the past, and deterioration of the metal case due to oxidation or trumpet-like expansion deformation may occur, so that the desired binding force may not be obtained. When the restraint force by the metal case decreases, the cracks generated in the nozzle main body expand.

In recent years, in order to improve the corrosion resistance and reduce the cost, the material of the SG lower nozzle has been changed to a non-fired product of alumina / carbon. Alumina-carbon material has a large thermal conductivity as compared with high-alumina material and zircon material that have been often used for SG noise in the past. Therefore, the temperature of the nozzle body easily rises, and S
The metal case used for the lower nozzle for G is exposed to higher temperature than before, and it is considered that deterioration of the metal case due to oxidation and trumpet-like expansion deformation are promoted from the viewpoint of the material.

The present invention solves such a problem, and it is an object of the present invention to provide a lower nozzle for a slide gate capable of suppressing a decrease in restraining force without deforming even if a metal case is hotly used many times. , Aim.

[0009]

In order to achieve the above object, a lower nozzle for a slide gate according to the present invention covers a cylindrical nozzle body having a flow path for molten metal and an outer peripheral portion of the nozzle body. A cylindrical metal case body for restraining the nozzle body from the outside, and a reinforcing body for reinforcing the nozzle body via the case body is provided around at least the outer periphery of the tip of the case body. And

The reinforcing body is preferably a cylindrical metallic reinforcing body which covers the outer peripheral portion of the case body, and the reinforcing body and the case body surround at least double the tip portion of the nozzle body. And

In the present invention, preferably, the case body and the reinforcing body surrounding the nozzle body are formed of a tubular member,
At least the tip of the tubular member is formed in a tapered shape extending toward the tip of the nozzle so as to reduce its diameter. With this tapered shape, it is possible to suppress the trumpet-shaped expansion and deformation of the tubular case body and the reinforcing body, and to further maintain the constraint force on the nozzle body.

The position where the reinforcing member is provided is 50 mm in the axial direction from the nozzle tip position of the case body and this tip position.
It is preferable that the outer periphery of the front end of the case body covers a position selected within the range of 400 mm or less. This range is because it corresponds to the tip portion that is easily exposed to high temperature to be oxidized or deformed.

As another aspect of the present invention, the reinforcing body and the case body are integrally formed. In this case, in addition to the layered structure of the reinforcing body and the case body, a thick structure in which the both are integrated can be constructed.

If the nozzle body is made of an alumina-carbon refractory, it can be expected that the corrosion resistance is improved. Even if an unfired refractory material is used for the nozzle body, a sufficient effect can be obtained.

[0015]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of a lower nozzle for a slide gate according to the present invention will be described below with reference to the drawings.

FIG. 1 illustrates a main part of equipment used in continuous casting. This equipment is to inject molten steel from the ladle 10 into the molds 30 and 30 through the tundish 20, and slide gates 40 and 40a for adjusting the molten steel flow rate are provided at the bottoms of the ladle 10 and the tundish 20, respectively. Are provided (reference numerals 50 and 51 in the figure denote immersion nozzles for injection).

The slide gate 40 is disposed between the upper and lower nozzles 41 and 42 which form a molten steel flow path FL which is connected to each other inside and outside with the bottom of the ladle 10 interposed therebetween, and the molten steel flow 41 and 42. It is composed of two plate-shaped refractories 43, 43 having holes for roads, and both plate-shaped refractories 43, 43 are slid horizontally to adjust the overlapping state of the holes so that the molten steel flow rate can be controlled. Control. This is substantially the same also in the case of the tundish-side slide gate 40a.

The lower nozzle 42 of the present invention having such a slide gate structure forms a flow path FL of molten metal as shown in FIG. 2 and has a refractory material of high alumina or zircon, or alumina / carbon material. A cylindrical nozzle body 2 made of non-fired refractory and a cylindrical iron metal case (iron skin) 4 surrounding the outer peripheral portion of the nozzle body 2 with a mortar 3.
And a tubular iron reinforcing metal case (iron skin) that surrounds the outer peripheral portion of the tip of the metal case 4 and forms the reinforcing material of the present invention.
5, the nozzle body 2 is a two-layer metal case 4
And 5 has a tip structure for reinforcement by stacking two sheets.

The reinforcing metal case 5 is exposed to a high temperature because it receives radiant heat from the tundish 20 in the inner metal case 4, and is easily oxidized or expanded and deformed. It is arranged in a portion that covers a position from there to a position set in the range of preferably 50 mm or more and 400 mm or less.

The tips of the two-layer metal cases 4 and 5 are
To prevent it from expanding and deforming into a trumpet shape each time it is used, it has a tapered shape in advance,
This taper shape makes it possible to more effectively maintain the restraining force on the tip of the nozzle body 2.

Now, the overall operation of this embodiment will be described. First, consider the injection of molten steel from the ladle 10 into the tundish 20. When pouring molten steel, slide gate 40
By adjusting the open / closed state, that is, the overlapping state of the holes of the two plate-like refractories 43, 43 by the sliding operation, the molten steel flow rate from the upper nozzle 41 to the lower nozzle 42 is appropriately controlled.

At this time, the tip of the lower nozzle 42 is exposed to a high temperature due to heat conduction from the molten steel and radiant heat from the tundish 20. Considering the case where there is no reinforcing metal case 5 under such an environment, the deformation of the metal case 4 due to oxidation or expansion proceeds, so that crack expansion of the brick is prevented and melting damage or chipping is prevented. The original function expected of the metal case 4 cannot be fully exerted.

Therefore, according to this embodiment, since a two-layer structure using the reinforced metal case 5 is constructed as a structure for reinforcing the metal case 4, it is possible to suppress a decrease in the reinforcing force of the metal case 4 with respect to the nozzle body 2. , Effectively prevent deformation such as oxidation and expansion, and as a result prevent expansion of cracks that occur in the nozzle body (brick). Is also eliminated, and it becomes possible to greatly improve durability.

As a secondary effect, a heat insulating effect due to the two-layer structure can be expected. Since the double enclosing portion is only the nozzle tip portion, there is also an advantage that it can be provided at a relatively low cost with a simple structure compared to the case of enclosing the entire portion.

In this embodiment, the double structure of the metal case is adopted, but the present invention is not limited to this, and may be reinforced with a triple structure or more sheets, or instead of this. The same effect as above can be expected even with a structure using a thick portion integrally forming a metal case and a reinforcing case such as changing the thickness of one iron skin. As the reinforcing structure material, a structure using ribs may be adopted instead of the above-described iron skin layer structure or thick structure.

Further, although the nozzle tip portion is tapered in this embodiment, the present invention is not limited to this and may be, for example, a straight shape.

The lower nozzle for the slide gate in this embodiment is for ladle or tundish,
Of course, the present invention is not limited to this, and an injection and immersion nozzle for tundish (see reference numerals 50 and 51 in FIG. 1).
For example, various types of refractory structural materials that form a flow path system for other molten metals can be applied as necessary.

(Example) In order to verify the above effects, a lower nozzle sample for SG of the product of the present invention and a conventional product was prepared, and a test of setting and using this in an actual machine was tried. 3 and 4 show samples of Examples 1 and 2 (invention product), and FIG. 5 shows samples of Comparative Examples 1 and 2 (conventional product), respectively. In the second embodiment, the length of the taper portion (throttle portion) at the tip of the nozzle is shorter than that of the first embodiment. In Comparative Example 1, the reinforcing metal case was removed, and the other configurations were the same as those in Example 2, and in Comparative Example 2, the nozzle material was a zircon fired product. Table 1 shows the results of actual use using each sample.

[0029]

[Table 1]

[0030] First, as to the number of times of use, as shown in Table 1, the products of the present invention are increased in comparison with the conventional products. Especially, the average number of times of use is a comparative example 2 composed of a zircon fired refractory.
Compared with the above, it was confirmed that the amount increased about twice because of the use of an alumina-carbon refractory having excellent corrosion resistance.

Regarding the oxidation of the metal case, both the product of the present invention and the conventional product were recognized, but the deformation of the product of the present invention was small, and the expansion of cracks that occurred was suppressed. It was determined that the state of the tip portion after use was generally good with the product of the present invention, and that it could be reused once or twice.

It was also confirmed that in the product of the present invention, the one in which the narrowed portion at the tip end is set to be longer (Example 1) has fewer cracks and is more excellent in the restraining effect.

[0033]

As described above, according to the present invention, since the reinforcing material for reinforcing the metal case body (metal case), for example, the structure in which the tip end portion of the nozzle body is at least double-enclosed, the slide gate is provided. It is possible to prevent the deformation of the metal case of the servicing nozzle and to maintain the binding force to the brick that constitutes the nozzle body for a long period of time. Therefore, it is possible to more effectively prevent the crack from expanding at the tip of the nozzle, so that the durability can be greatly improved.

[Brief description of drawings]

FIG. 1 is a schematic sectional view showing the overall structure of a lower nozzle for a slide gate according to the present invention.

FIG. 2 is a schematic view of a lower nozzle for a slide gate according to the present invention.

FIG. 3 is an explanatory diagram of a lower nozzle according to the first embodiment.

FIG. 4 is an explanatory diagram of a lower nozzle according to the second embodiment.

FIG. 5 is an explanatory diagram of a lower nozzle according to Comparative Examples 1 and 2.

FIG. 6 is a schematic diagram illustrating a conventional lower nozzle for a slide gate.

[Explanation of symbols]

2 nozzle body 3 mortar 4 metal cases 5 Reinforcing metal case (reinforcing material) 10 ladle 20 tundish 30 molds 40, 40a slide gate 41 Upper nozzle 42 Lower nozzle (lower nozzle for slide gate of the present invention) 100 lower nozzle 101 Tundish (TD) 102 refractory brick 103 mortar 104 metal case

─────────────────────────────────────────────────── ─── Continuation of the front page (72) Hideaki Kato 1st Nanto, Ogakie-cho, Kariya-shi, Aichi Toshiba Ceramics Co., Ltd. Kariya Works (72) Inventor Takaaki Hirano 1st Nanto, Ogakie-cho, Kariya-shi, Aichi Toshiba Ceramics Co., Ltd. Kariya Factory (72) Inventor Osamu Morita 1 Minamito, Ogakie-cho, Kariya City, Aichi Toshiba Ceramics Company Kariya Factory (56) Reference JP-A-52-39533 (JP, A) JP-A-7-256438 (JP) , A) JP 7-308766 (JP, A) JP 59-54460 (JP, A) Actual opening 55-98470 (JP, U) Actual opening 53-119412 (JP, U) Actual opening 7-9555 (JP, U) Actual Kaihei 6-9749 (JP, U) (58) Fields investigated (Int.Cl. ⁷ , DB name) B22D 41/22 B22D 11/10 340 B22D 11/10 320 B22D 41/50 C21C 5/46 103 F27D 3/14

Claims (7)

(57) [Claims] 1. A cylindrical nozzle body having a flow path for molten metal, and a cylindrical metal case body that covers an outer peripheral portion of the nozzle body and restrains the nozzle body from the outside.
A lower nozzle for a slide gate, wherein a reinforcing body for reinforcing the nozzle body is provided around at least the outer periphery of the tip of the case body via the case body. 2. The invention according to claim 1, wherein the reinforcement body is a tubular metal reinforcement body that covers an outer peripheral portion of the case body, and the tip end of the nozzle body is formed by the reinforcement body and the case body. A lower nozzle for a slide gate, which is characterized by enclosing at least a double portion. 3. The invention according to claim 2, wherein the case body and the reinforcing body surrounding the nozzle body are formed by a tubular member, and at least the tip end portion of the tubular member has a diameter toward the nozzle tip end side. A lower nozzle for a slide gate, which is formed in a tapered shape extending so as to squeeze. 4. The invention according to claim 2, wherein a position at which the reinforcing body is provided is a nozzle tip position of the case body,
A lower nozzle for a slide gate, which is an outer periphery of a front end portion of the case body which covers a space between the front end position and a position selected within a range of 50 mm to 400 mm in the axial direction. 5. The lower nozzle for a slide gate according to claim 2, wherein the reinforcing body and the case body are integrally formed. 6. The lower nozzle for a slide gate according to claim 1, wherein the nozzle body is made of an alumina / carbon refractory material. 7. The lower nozzle for a slide gate according to claim 1, wherein the nozzle body is made of an unfired refractory material.