JPH07328763A - Nozzle for molten metal and its manufacture - Google Patents

Abstract

PURPOSE:To fit a metal case so that cracks are not generated in a nozzle for the molten metal such as a sliding nozzle. CONSTITUTION:The inner circumference of a metal case 4 to be fitted to the outer circumferential part of a nozzle for the molten metal is made smaller in the length by 0.1-2% than the outer circumference of the nozzle, the metal case 4 is heated to 500-1000 deg.C by a high frequency heating device 5 to be shrinkage fitted to the outer circumferential part of the nozzle coated with the refractory heat insulating material 3. High heat is difficult to be transmitted to the metal case 4, and the restrictive force is given to the nozzle to prevent the nozzle from being cracked.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a molten metal nozzle such as a sliding nozzle used for controlling a molten metal flow in the steel industry and a method for manufacturing the same.

[0002]

2. Description of the Related Art A sliding nozzle controls the flow rate of molten metal in the steel industry and is generally composed of an upper nozzle, an open / close control plate brick, and a lower nozzle.

The above-mentioned lower nozzle and the like are subjected to extremely severe thermal shock because the hot molten metal passes through the inside of the molten metal when the molten metal flows from the ladle to the tundish.

Therefore, the nozzle is apt to be cracked, and further, the molten steel is introduced into the cracked portion or the preceding melting loss is caused by the entrainment of air, resulting in a shortened life.

In order to prevent this crack, a metal case is usually attached to the outer peripheral portion of the nozzle, and refractory mortar is used to attach the metal case.

[0006]

However, when the metal case is mounted with the refractory mortar, a gap is generated between the nozzle and the metal case due to the filling failure of the refractory mortar or the contraction of the refractory mortar. Metal case
The restraint force of the nozzle was not sufficient, the thermal stress generated in the nozzle during use could not be suppressed, and the nozzle sometimes cracked.

In the method using refractory mortar, it is necessary to coat the nozzle or the metal case with refractory mortar to remove excess refractory mortar, and to dry at 70 to 150 ° C. Therefore, the work is complicated, skill is required, and the cost is high.

[0008]

SUMMARY OF THE INVENTION The present invention has been made in view of the above points, and in order to solve the above problems, a metal case is formed on the outer peripheral portion of a molten metal nozzle coated with a refractory heat insulating material.
It is an object of the present invention to provide a molten metal nozzle and a method for manufacturing the same, which is characterized in that the molten metal is heated by high frequency induction and fitted.

[0009]

When the molten metal nozzle of the present invention is used, the metal case is heated and fitted into the outer peripheral portion of the molten metal nozzle coated with the refractory heat insulating material by high frequency induction, so that the metal case is evenly distributed on the nozzle. Can be closely fitted in a metal shape, and it is difficult to transfer high heat from the molten metal nozzle to the metal case, and it is possible to significantly prevent the nozzle from cracking due to the uniform restraining force of the metal case. In addition to being able to do this, mass production of products of the same quality can be done easily and cost can be reduced.

[0010]

The present invention will be described in detail below. 1 and 2 show an embodiment of the present invention. As shown in FIG. 1, a lower nozzle 1 of a molten metal nozzle for injecting molten steel from a ladle into a tundish with a controlled flow rate has a nozzle body 2 of a predetermined refractory material coated with a refractory heat insulating material 3, and an outer peripheral surface of the steel. A metal case 4 made of metal is shrink-fitted and attached.

As the fireproof heat insulating material 3, a commercially available fireproof sheet, fireproof board, heat insulating sheet, heat insulating board, ceramic fiber, ceramic cloth or the like can be used. As the material, a refractory material such as alumina, silica, magnesia is preferable.

The thickness of the refractory heat insulating material 3 is as follows.
0.2 to 5 mm can be used and its thickness is 0.2 mm
If the thickness is less than 5 mm, the heat insulation effect is not sufficient, and if the thickness is 5 mm or more, the surface coverage of the nozzle brick becomes poor, and the expansion of the nozzle brick cannot be suppressed by the metal case 4, which is not preferable because the crack preventing effect is poor.

It is necessary that the metal case 4 is accurately aligned with the outer peripheral portion of the nozzle body 2, and the inner diameter of the metal case 4 is made slightly smaller than the outer diameter of the nozzle body 2 so that the shrink fitting rate is 0. It is preferable to mount it as 1 to 2.0%.

The shrink fitting ratio is the shrink fitting ratio (%) = (1-
The inner diameter of the metal case / outer diameter of the nozzle brick is defined by the formula of 100, and when the shrinkage fitting rate is 0.1% or less, the nozzle body 2
Is not sufficient, and if it is more than 2.0%, it is difficult to shrink fit the nozzle body 2. It should be noted that the larger the shrinkage fitting rate is, the more the restraining force of the nozzle body 2 during use can be prevented from being lowered.

The above-mentioned metal case 4 is uniformly heated by the high frequency induction heating device 5 as shown in FIG. 2, and the heated metal case 4 is dropped toward the nozzle body 2 below and fitted. , Cooled.

The heating temperature in the high frequency induction heating device 5 is preferably 500 to 1000 ° C. When the temperature is lower than 500 ° C., the metal case 4 does not expand sufficiently, so that the nozzle body 2 cannot be fitted and the heating temperature is 1000 ° C. If the temperature is higher than ° C, the surface of the metal case 4 is notably oxidized, and there is a problem that it is deformed.

[0017]

[Example of use] A lower nozzle having the above-mentioned structure is coated with a fireproof heat insulating sheet of alumina fiber having a thickness of 2 mm on the entire surface of the nozzle body.
80 mm iron metal case with high frequency induction heating device
It was heated to 0 ° C. and fitted into the nozzle body.

When this lower nozzle is used in an actual furnace, it has a life of about 1. compared with the conventional mortar set product.
I was able to extend it five times.

Although the lower nozzle of the sliding nozzle has been described above, the present invention is also applicable to the upper nozzle, the plate brick, and other pouring nozzles.

[0020]

As described above, according to the present invention, the nozzle body can be restrained by the metal case, and
The refractory heat insulating material can prevent high heat from being transferred to the metal case, can maintain the restraining force to the nozzle, and can significantly improve the crack preventing effect of the nozzle and extend the life.

Further, in the manufacture of nozzles, the same quality can be easily mass-produced, and the working time can be shortened and the cost can be reduced.

Furthermore, since the induction heating is used, the fitting rate can be easily controlled, the required shrinkage fitting rate can be obtained, and the restraining force for the nozzle is increased, so that the cracking of the nozzle in use can be effectively prevented. be able to.

[Brief description of drawings]

FIG. 1 is a side sectional view of an embodiment of the present invention,

FIG. 2 is a schematic side sectional view showing the same manufacturing method as above.

[Explanation of symbols]

1 ... Lower nozzle 2 ... Nozzle body 3
… Refractory insulation 4… Metal case 5… High frequency induction heating device

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Go Okamoto 2 1576, Higashioki, Nakaho, Ako-shi, Hyogo Prefecture 2 Kawasaki Furnace Co., Ltd. (72) Inventor Akiyoshi Tsuda 43 Wakasano-cho, Aioi-shi Sanyo High Frequency Industry Co., Ltd. (72) Inventor Yutaka Okakawa One share company, Asahi Giken, 214 Sugaya, Yano Town, Aioi City, Hyogo Prefecture

Claims (4)

[Claims] 1. A molten metal nozzle fitted with a metal case heated by high frequency induction and fitted around the outer periphery of the molten metal nozzle coated with a refractory heat insulating material. 2. The molten metal nozzle according to claim 1, wherein the metal case has an inner circumference smaller than the outer circumference of each portion of the molten metal nozzle by 0.1 to 2%. 3. A molten metal nozzle is coated on its outer peripheral surface with a thin refractory heat insulating material, and a metal case is heated by high frequency induction to be fitted into the molten metal nozzle coated with the refractory heat insulating material. A method for manufacturing a molten metal nozzle. 4. The inner circumference of the metal case mounted on the outer circumference of the molten metal nozzle is 0.1 to 2% of the outer circumference of the molten metal nozzle.
4. The method for manufacturing a molten metal nozzle according to claim 3, wherein the molten metal nozzle is reduced in size and heated to 500 to 1000 [deg.] C. by high frequency heating to be fitted on the outer peripheral portion of the molten metal nozzle.