JPS633732Y2 - - Google Patents

Description

[Detailed description of the invention] This invention is connected from the tandem to the mold to prevent oxidation of molten steel, control the flow of molten steel in the mold,
This invention relates to an improvement of a continuous casting immersion nozzle used for the purpose of preventing splash and slag entrainment.

Conventionally, these immersion nozzles have been made of fused silica or graphite-alumina in order to obtain high-quality slab properties and to operate continuous steel casting smoothly in terms of spall resistance, corrosion resistance, and airtightness. Refractories have commonly been used.

Additionally, mold powder, which is added to the mold to prevent oxidation of molten steel, causes local melting damage to the nozzle and significantly reduces its durability, but this problem can be solved by installing a protective sleeve at the powder line. , or by increasing the thickness of the powder line portion of the main body. However, these methods are limited by the mold size, and are no longer compatible with the multiple casting operations that have been trending in recent years.

The present invention addresses this type of problem by providing an immersion nozzle for continuous casting that enables stable multiple casting operations by carefully studying the structure of the protective sleeve.

The gist of the present invention is to continuously cast molten steel by fitting a refractory protection sleeve 2, which has corrosion resistance equal to or higher than the material of the nozzle body 1, in the area where local melting damage occurs due to contact with mold powder. In the submerged nozzle for use, when either the upper end or the lower end of the protective sleeve 2 is fixed to the nozzle body 1, and the protective sleeve 2 is fused,
The immersion nozzle for continuous casting is characterized in that a sliding gap is provided between the outer circumferential surface of the nozzle body 1 and the inner circumferential surface of the protective sleeve 2 at the loosely fitting portion of the protective sleeve 2, and the nozzle body of the protective sleeve The means for fixing to the base may be adhesive using inorganic mortar or screw fitting.

In other words, the immersion nozzle of the present invention is fixed to the main body either near the upper end or near the lower end, whereas the conventional protective sleeve is fixed to the main body throughout the casting process, and the other parts are fixed to the main body. This immersion nozzle for continuous casting is characterized by being equipped with a protective sleeve.

Hereinafter, the features, functions, and effects of the present invention will be explained in detail based on the accompanying drawings showing specific examples of the present invention.

FIG. 1 schematically shows a conventional protective sleeve type submerged nozzle. In this case, the main body is eroded by the mold powder from the stage when the protective sleeve 2 is fused and cut, resulting in a state as shown in FIG. 2, so that the overall service life is extremely short.

In contrast, an example of the present invention is shown in FIG. 3, and in this case, even if the protective sleeve 2 is fused and cut due to the erosion of the mold powder, the unfixed protective sleeve portion of the protective sleeve 2 that is divided into upper and lower halves. slides along the nozzle body 1 and sinks or floats to form a reintegrated protective sleeve. For example, when the part near the upper end is fixed to the main body, the lower sleeve slides due to buoyancy due to the difference in specific gravity between the refractory and molten steel, as shown in Figure 4.
It floats up and is fixed in such a way that the upper sleeve pushes it down, and the two become integrated. When the lower end portion is fixed to the main body, the upper sleeve slides and sinks due to its own weight, and the lower sleeve pushes up and fixes the upper sleeve, thereby integrating the two. The integral protective sleeve formed in this way again prevents mold powder from entering. Furthermore, since this operation is repeated each time the protective sleeve is melted and cut, the main body 1 is constantly covered with mold powder. Naturally, molding powder will flow in after the protective sleeve is fused and before the upper and lower sleeves are connected again, but the amount is so small that the degree of melting and damage to the main body is not that great.

On the other hand, even if the protective sleeve is not fixed to the main body at all during casting, even if the protective sleeve is fused, it can be re-integrated to prevent mold powder from flowing in, as in the present invention. However, in this case, since the protective sleeve is floating in the molten steel, the same location becomes the powder line for mold oscillation. That is, it is more likely to melt and break than a protective sleeve that is fixed to the main body, whose melting points change slightly depending on the oscillation of the mold. As mentioned above, the amount of mold powder that flows in each time the melt is cut is minute, but if this happens frequently, the main body will be melted and damaged by the molten metal. Therefore, a protective sleeve that is not fixed at all to the main body during casting results in no overall improvement in service life.

As described above, if the protective sleeve melts during casting, the present invention allows either the upper part of the sleeve or the lower part of the sleeve to be fixed to the main body.
For the first time, durability against mold powder can be significantly improved.

In the present invention, the material of the protective sleeve is set to be a refractory material that has corrosion resistance equal to or higher than that of the main body material, because durability cannot be effectively improved with a material that is less corrosion resistant than the main body material. Although the method of fixing the portion near the upper end or the portion near the lower end to the main body is set as inorganic mortar or screw structure, other methods may be used as long as they can be fixed to the main body during casting. Further, the portion near the upper end or the portion near the lower end can be arbitrarily selected as the portion to be fixed to the main body based on the conditions of use. The other parts must not be fixed to the main body, but if they are made of organic material such as mortar that disappears during casting, they can be used for the purpose of handling this type of nozzle.

Next, an example of use of the immersion nozzle of the present invention will be described.

Example: In a fused quartz refractory immersion nozzle and a powder line protection sleeve made of the same material, the combined immersion nozzle of the present invention, in which the upper end of the protection sleeve is fixed to the main body as shown in Fig. 3, was used in continuous casting in comparison with the conventional combined immersion nozzle shown in Fig. 1. As a result, the conventional product
In the early stages of 3ch (charge), holes appeared in the powder line of the main body due to erosion, and casting was halted. In contrast, in the case of the product of this invention, although the main body was slightly melted, it showed stable durability even in 7ch.

[Brief explanation of the drawing]

FIG. 1 shows a conventional product, and FIG. 2 is a schematic diagram showing the state in which the conventional product is used. Fig. 3 shows an example of the product of the present invention, and Fig. 4 is a schematic diagram showing the product of the present invention in use. Material.

Claims (1)

[Scope of Claim for Utility Model Registration] (1) A refractory protection sleeve 2 having corrosion resistance equal to or higher than that of the material of the nozzle body 1 is fitted in areas where local erosion occurs due to contact with mold powder. In continuous casting immersion nozzles,
Either the upper end or the lower end of the protective sleeve 2 is fixed to the nozzle body 1, and when the protective sleeve 2 is fused, the outer peripheral surface of the nozzle body 1 and the protective sleeve 2 are loosely fitted. A immersion nozzle for continuous casting, characterized in that a sliding gap is provided between the inner peripheral surface of the sleeve 2. (2) The immersion nozzle for continuous casting according to claim 1, wherein the means for fixing the protective sleeve 2 to the nozzle body 1 is adhesion using inorganic mortar or screw fitting.