JPS5884173A - Manufacture of dipping nozzle for continuous casting - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for manufacturing a submerged nozzle for continuous casting of steel.

A nozzle for continuous casting of steel, for example a nozzle for a tundish, is an important member for adjusting the amount of molten steel from the tundish to the mold, and is said to be one of the key points of continuous casting technology. In other words, the nozzle that connects the tongue isher and the mold not only prevents molten steel from oxidizing and retains heat, but also prevents turbulence of the molten steel flow and slag incorporation during pouring, combined with the effect of the heat-insulating powder inside the mold. It is highly effective in improving the surface quality of the pieces.

For this reason, various fire-resistant materials are being researched for materials for this type of nozzle. For example, materials with high silicic acid, norconia, or zircon are used for S-C, but among these, those with high silicic acid are relatively soft and have poor corrosion resistance. The contact area of the nozzle is highly eroded, so it is easily damaged by melting, and the nozzle diameter is enlarged. Additionally, norconia and zirconia materials are advantageous against melt damage, but their oxides may adhere to the metal in the molten steel, especially alumina, causing the nozzle rE4 to shrink and, in severe cases, to cause nozzle blockage. was there. Furthermore, recently, a submerged nozzle with a melting surface has been developed, which has a manganese content of 1.2 to 1.
For molten steel with a high aluminum content of 0.02 to 0.6 inch, the melting loss is significant, and for molten steel with a high aluminum content of 0.02 to 0.6 inch, there is a disadvantage that nozzle clogging due to alumina adhesion is likely to occur. The present invention seeks to manufacture a nozzle that solves the above-mentioned drawbacks of conventional continuous casting nozzles, such as erosion, erosion, and clogging. The present invention will be explained in detail below.

There has been research into high alumina materials and graphite materials, but they all have advantages and disadvantages and have not been successful. For example, high alumina materials have excellent corrosion resistance, but they tend to cause nozzle clogging, and metal oxides (especially Mn) in the molten steel.

There is a problem in that a degraded layer is formed due to the reaction with Fe*(oxides such as AZ), and this layer peels off.

Moreover, high alumina materials are quite expensive.

Furthermore, although graphite materials are superior to conventional chamots materials, the problems of erosion and clogging remain unsolved.

Furthermore, since graphite has a particularly high thermal conductivity, it lowers the temperature of the nozzle and causes blockage.

In this invention, a nozzle for casting is manufactured by mainly consisting of alumina and graphite, and adding elemental silica to this and molding it by a rubber press method. However, it has sufficient corrosion resistance, which is a feature of alumina, and does not cause enlargement of the nozzle diameter or welding of the nozzle, especially in the case of immersed nozzles. A casting nozzle that has the effect of not causing flaking due to deterioration of the nozzle due to reaction with substances, and can improve spalling resistance and prevent nozzle clogging by adding a silica element. It will be done.

Next, embodiments of the present invention will be described, and all numbers in the description are percentages by weight.

First, powdered alumina is 42-93%, powdered graphite is 4-4%
An effective amount of 2% or more of powdered molten liquor is further mixed with the 4% ratio to obtain a raw material. Next, these raw materials are thoroughly kneaded together using a suitable binder such as tarvin, chi or synthetic resin. As the binder, the above-mentioned materials are most suitable, or the waste water from ponds and mother liquefaction, water glass, and molasses are also effective.

This mixture is filled into a rubber mold, loaded into a rubber press machine, and then molded under pressure.The desired casting nozzle is then manufactured through the following usual steps.

If the mixing ratio of alumina and graphite is less than 42%, the corrosion resistance of alumina will be lost, resulting in enlarged nozzle diameter and melting damage, and if it is more than 93%, metal oxides in the molten steel ( % Mn.

When the alumina content is too high, the spalling resistance becomes low. Furthermore, if the graphite content is less than 5%, the effect of graphite mixing cannot be expected, and the above-mentioned nozzle peeling and spalling resistance cannot be solved. On the other hand, if it exceeds 44%, the thermal conductivity increases and nozzle clogging is likely to occur. However, it is still not possible to prevent nozzle clogging with only such alumina and graphite, and the resistance to scratches and IJ songs is not sufficient, so a simple substance of silica is added to this.In this case, silica As a single material, it has the best melting ability. When only molten phosphorus is added, if the amount added is less than 2 inches, there will be little effect, and if it is more than 23 inches, the corrosion resistance will actually deteriorate.

In general, immersion nozzles for continuous casting are frequently rapidly heated and cooled to zero, so they must have particularly excellent spalling resistance. For this reason, in addition to using only 7-force materials such as molten resin (l) f), the inventors also considered the molding method, and found that the rubber press method was used instead of the conventional molding method. It has been found that the corrosion resistance and sailing properties can be further improved.

In the conventional molding method, the mixture is packed into a steel or wooden mold of a certain shape and then pressure-formed.
In such cases, if the product is of various irregular shapes or long, the core tends to become rough, cracks or so-called holes appear, and the inner part tends to be rougher than the outer part. There are disadvantages such as a decrease in bulk specific gravity.

On the other hand, according to the rubber press method, the rubber mold is filled with a rubber mold, loaded into a press machine, and static pressure is applied, so a molded product with a smooth structure can be easily obtained. In other words, the molded product made using the rubber press method has no difference in density between the inside and the outside, and is uniform throughout and is free from cracks and cracks.
It is something without.

This rubber press is particularly effective in molding long items such as immersion nozzles.

To further explain the drawings, in Fig. 1, 1 is a tandyone nozzle, and 2 is a submerged nozzle that is provided so as to extend therefrom, and both of them are casting nozzles for tandinone manufactured by the method of the present invention. It is.

Fig. 2 shows the tandinone 3 with the same nozzle 1.2 attached, the mold 4 and molten steel 5 located below it, and the molten steel 5 in the tandinone 3 passes through the nozzle 1.2 to the molten steel 5 of the mold 4. '.

Example 1 57 parts of powdered alumina and 38 parts of powdered graphite were mixed, and 5 parts of powdered molten phosphoric acid were added, and then 3 parts of raw tar pitch was added and the mixture was thoroughly mixed. match. This mixture is filled into a rubber mold of a predetermined size, loaded into a rubber mold (using glycerin as the liquid), and molded by increasing the pressure to 200 to 9/an2 in about 5 minutes, and then dried after demolding. and fired.

Round Example 2 45 parts of Matsubushi alumina, 40 parts of powdered natural graphite, and 15 parts of powdered molten lime were mixed, 5 parts of phenol resin was added thereto, and the mixture was sufficiently kneaded and granulated. This was filled into a rubber mold of a predetermined size, loaded into a rubber press, and molded by increasing the pressure to 1,000 to 97 cm2 in about 15 minutes. After removing the mold, it was dried and fired.

Example 3: Mix 63 parts of powdered alumina with 27 parts of powdered graphite, add 10 parts of powdered fused phosphoric acid, add 2 parts of polyvinyl alcohol resin, and mix. match. This mixture is filled into a rubber mold using a predetermined method.
Load this into a rubber press and increase it to 2000 in about 20 minutes.
The pressure was increased to /Crn2 and molded, and after demolding, it was dried and fired.

The cast nozzle obtained in Example 1.2.3 had the properties shown in the table below, and had a uniform dense structure as a whole, with no cracks, pores, or "s". In addition, when these casting nozzles were used as casting nozzles for tandies during continuous steel casting (particularly casting of manganese steel and aluminum killed steel), they were found to be unusable after a few times. It is recognized that it can withstand several times the number of uses, and is therefore also economical.

In this case, the number of times per cost differs depending on the capacity of the tandinong, so if the life of the casting nozzle is expressed in terms of the amount of molten steel cast, conventionally it becomes unusable after several tons to several tens of tons, whereas the method of the present invention The casting nozzle manufactured by the company was capable of casting tens to hundreds of tons.

[Brief explanation of drawings]

FIG. 1 is a cross-sectional view showing an example of a continuous casting immersion nozzle manufactured by the method of the present invention. FIG. 2 is a cross-sectional view of a continuous casting tundish and mold to which the same nozzle is attached. Figure 1 Proceedings Amendment (Spontaneous) July 30, 1980 Yoshio Kawahara, Commissioner of the Japan Patent Office 1. Indication of the case 1981 Patent Application No. 81487 2. Name of Akira Immersion Nozzle for Continuous Casting Relationship with the case of the person amending the manufacturing method; New patent applicant 1-26-2 Nishi-Shinjuku, Shinjuku-ku, Tokyo Name: Toshiba Ceramics Co., Ltd. 1 Agent 5 Drawings subject to amendment

Claims (1)

[Claims] By weight, raw materials consisting of 42 to 93 g of powdered alumina, 4 to 44% of powdered graphite, and an effective amount of powdered silica are mixed, and a binder i' is added. 1. A method for producing a immersion nozzle for continuous casting, which comprises: sufficiently kneading the immersion nozzle using a rubber press, molding it into a predetermined shape by applying pressure using a rubber press, and drying and firing after removing the mold.