JPH02104454A - Nozzle for continuous casting - Google Patents

Abstract

PURPOSE:To improve casting efficiency and the quality of a cast slab without allowing slag to flow into a tundish by assembling a fire resistant pipe having penetrating fine hole to a part of blowing hole system of inert gas, etc., in a nozzle body as built-in. CONSTITUTION:The fire resistant pipe 10 having penetrating fine hole 12 is set to the nozzle for continuous casting, such as long nozzle, submerged nozzle. At the time of introducing the inert gas into the penetrating hole 8 from a blowing metal fitting 6, the inert gas is blown into inner hole 3 of the nozzle through the penetrating fine hole 12 in the refractoriness pipe 10 and the penetrating hole 9 near the inner hole 2 of the nozzle. By this method, the blowing of the inert gas is surely and stably executed and flowing of non-metallic inclusion into the tundish and mold can be prevented.

Description

Detailed Description of the Invention (Industrial Application Field) The present invention relates to a continuous casting refractory nozzle used for continuous metal casting, and more specifically relates to a refractory nozzle having a through hole in an inert nozzle body. The present invention relates to a nozzle for continuous casting, characterized in that it is assembled into a part of a gas, etc. blowing hole system.

(Prior Art) The conventional technology will be explained by taking as an example a long nozzle used between a ladle and a tundish in continuous casting.

The function of the long nozzle in continuous casting operation is to inject molten metal from the ladle into the tundish.■ It prevents the molten metal from coming into contact with the atmosphere and deterioration, and ■ It prevents splashing when pouring the molten metal. In addition to ensuring operational safety and suppressing the entrainment of inclusions, and maintaining a constant flow of molten metal into the tundish to prevent turbulence, depending on the type of metal to be cast, Examples include measures to prevent inclusions from floating, to make them fine, and to inject special powder to improve the quality of slabs. More recently, the ability to accurately cut the slag at the final stage of pouring molten metal from a ladle has become a new functional need. Various measures are being taken to address these issues.

In other words, the problem with preventing oxidative deterioration of molten metal is the joint (fitting part) with the ladle collector nozzle at the top of the long nozzle.
This is due to air entrainment due to poor sealing performance in the long nozzle. Measures are taken such as increasing the hole pressure to prevent outside air from entering, and preventing air from entering through the pores of the long nozzle itself by making the material of the long nozzle denser.

In order to blow special powder, a blow hole was provided in the body of a long nozzle and a supply pipe was connected to the blow hole.

In addition, when pouring molten metal from a ladle into a tundish, injecting the slag in the ladle into the tundish at the end of charging may have an adverse effect on the quality of the slab and seriously impede the continuation of casting after the first charge. Therefore, it is important to prevent the ladle slag from flowing down into the dandice (this is called slag cutting) due to operational problems in improving slab quality and achieving long casting times.

Conventionally, there was no definitive method, and at the end of the process, the long nozzle was pulled up into the molten metal from the immersed state to release it, and the judgment was made by visual inspection, or by using a ladle weight meter. ! +! Although the final stop was determined by I control, there remained a major problem that it was not effective and effective, and this became a serious bottleneck in continuous casting.

(Problems to be Solved by the Invention) The conventional methods described in L have various problems as listed below. This is also an example of a long nozzle.With a long nozzle, it is common to intermittently inject molten metal into at least 5 ladles, and sometimes up to 10 ladles. It is used under extremely severe and harsh conditions where it is subjected to intense thermal history due to heating and cooling.1 For example, as shown in Figure 1, a porous brick 4a is fitted into the joint between the long nozzle 1a and the ladle collector nozzle 2a, and the In the method in which active gas is bubbled from the porous brick 4a through the air pocket 7a from the blowing fitting 6a, the porous brick 4a cracks when subjected to thermal history, making it impossible to uniformly bubble the inert gas and making the important joint surface smooth. In addition, it is not possible to measure the negative pressure in the nozzle inner hole 3a of the long nozzle 1a. In addition, the manufacturing cost is high, and this has a negative impact on the casting cost as well as the low durability.

Next, as shown in Figure 2, we use a long nozzle l with an inlet for injecting metal and flux into the molten steel.
In case a, the blowing pipe 5a is likely to break during casting,
In addition, the air sealability becomes incomplete, which also increases the cost of refractories, and makes it difficult to measure negative pressure because metal backflow tends to occur.

The above-mentioned problems with the conventional method have been a factor that hinders ensuring the quality of slabs in continuous casting and impedes safe operation, so countermeasures have been awaited.

(Means for Solving the Problems) The present invention has been made in order to solve these problems under the above background, and is configured as follows.

The present invention is a continuous casting nozzle characterized in that a refractory pipe having a through hole with an inner diameter of 0.1 to 5+ m is assembled into a part of the blow hole system within the nozzle body.

That is, this invention was made in order to completely seal the joint with the ladle collector nozzle at the top of the long nozzle, and to also establish negative pressure in the inner hole of the long nozzle. A fire-resistant pipe with small holes in the middle of the through-hole system is assembled with mortar, and inert gas can be introduced to achieve high sealing performance by inert gas bubbling. An object of the present invention is to provide a continuous casting nozzle that enables negative pressure measurement in a long nozzle inner hole.

Next, the present invention will be explained in detail with reference to FIGS. 3 and 4 in the case of a long nozzle used between a ladle and a tundish.

As an example of the material of the fire-resistant pipe, graphite 12% by weight is used.
After kneading a mixture consisting of 75% by weight of alumina and 13% by weight of silica and adding 7.5% by weight of an organic binder, the resulting clay was pressurized with a press. The molded and fired product was used.

First, 1 is a long nozzle having a nozzle inner hole 3, and 2 is a ladle collector nozzle. Therefore, in the vicinity of the flange of the long nozzle 1 main body, the large diameter through hole 8 and the same small diameter through hole 9 for blowing inert gas etc., which are linearly connected, are horizontal or downward at an angle of 045 with respect to the straight line of the nozzle inner hole 3 button. A fire-resistant pipe 1 is installed in the large-diameter through-hole 8 over a part of its total length (injection hole system), that is, 20 to 80%.
0 is fixed with mortar and assembled internally, and a blowing fitting 6 for blowing inert gas or powder is integrally provided on the outer periphery of the long nozzle 1 by attaching it to the iron skin 1''. Among these, the fireproof pipe 10 has a through hole 12 with an inner diameter of 0.1 to 5 mm on its new surface, for example, in FIGS.
The cross-sectional area and the number of elements arranged can be selected as appropriate depending on the purpose. Various other applications may also be used as long as the method of arranging shape values similar to the shape illustrated in FIG. 4 is acceptable. In any case, the refractory pipe 10 only needs to have a shape and cross-sectional area according to the purpose and to prevent backflow of metal from the nozzle inner hole 3 of the long nozzle 1. And such large diameter and small diameter through holes 8, 9. The arrangement of multiple or more blow holes forming the structure of the through-holes 12 can be selected depending on the U construction conditions from the nozzle hole, but it is important to consider the number and size of the blow holes so as not to impair the absolute strength of the long nozzle 1. be. Furthermore, in terms of the shape of the arrangement, in the vertical section, it is at a horizontal or downward angle of 045 degrees with respect to the vertical line of the nozzle inner hole 3 of the long nozzle 1, and in the horizontal section, it is perpendicular to 30 degrees with respect to the nozzle inner hole 3 surface of the long nozzle 1. is applicable to the possible range.

(Function) Inert gas guided from the gas supply device is introduced into the through hole 8 from the blowing fitting 6. And more fireproof pipe 1
The gas is blown into the nozzle inner hole 3 through the through hole 12 of the nozzle body, and then through the through hole 9 near the nozzle inner hole 3 of the nozzle body, but this blowing of gas is reliable and stable compared to the porous body. It can be done accurately.

This invention is as described above, and a fire-resistant pipe having through holes 12 is arranged in a continuous casting nozzle such as a long nozzle or an immersion nozzle, and the non-metallic intervening material is used to seal joints and to insert non-metallic materials into a tandate mold. The structure is such that it is possible to bubble inert gas as a countermeasure against materials, to detect the negative pressure inside the nozzle at the end of casting, to cut the tundish slag, and to blow powder such as metal into the tundish and mold.

(Effects of the Invention) Since the continuous casting nozzle of the present invention is configured as described above, a predetermined amount of gas can be reliably and stably blown into a predetermined location compared to the case of a conventional porous body. Even if the metal tries to flow backward through the blow hole, it can be reliably stopped before the through hole 12.

Next, it is possible to increase the strength of the joint surface by more than twice that of the conventional method, making it possible to prevent damage to the joint and maintain high sealing performance for a long time.

In addition, by measuring the gas square in front of the blowing fitting 6 while blowing inert gas, it is possible to maintain a constant negative pressure itp+ in the nozzle inner hole 3, and the pressure change when the slag falls from the ladle can be controlled. Since it can be easily detected, it is possible to switch to the next ladle without letting the slab flow into the tundish, and compared to conventional methods, it can achieve extremely accurate control, improving casting efficiency and slab quality in continuous casting. This has a great effect on improvement. In addition, it has the advantage that powder such as alloy powder can also be blown in the same way as this inert gas blowing.

When the nozzle of this invention was actually used as a long nozzle between a ladle and a tundish, it was possible to stably blow inert gas as shown in the figure below, and the sealing performance of the joint was kept high for a long time. The result was that the floating effect of non-metallic inclusions in the tundish was great, and the inflow of slag when changing the ladle was suppressed to an extremely small amount. As a result, we were able to significantly improve the quality of slabs and shorten the ladle replacement time in continuous casting.

Also, out of 35 trials, there was no backflow of metal.

In two of these cases, the solidification occurred in front of the fireproof pipe, proving that backflow was prevented.

As described above, the present invention has an extremely large effect on making continuous casting operations safer, reducing safety ratios and costs, and further improving the quality of slabs.

[Brief explanation of the drawing]

1 and 2 are longitudinal sectional front views of conventional long nozzles, FIG. 3 is a longitudinal sectional front view of a long nozzle showing an embodiment of the present invention, and 4) to (S) are fire-resistant pipes. FIG. ■, 1a... Long nozzle, 2, 2a... Collector nozzle, 3, 3a... Nozzle inner hole, 4a... Porous brick, 5a... Blow pipe, 6, 6a... Blow metal fitting , 7a... Air pocket, 8... Large diameter through hole,
9...Small diameter through hole, 10...Fireproof pipe, 11...
... Iron skin, 12 ... Penetration pores, 0 ... Downward angle. Patent Applicant Akechi Ceramics Co., Ltd. Agent Patent Attorney Kazu Oyasu Name 4 Figure 1269 Through Hole

Claims (1)

[Claims] A continuous casting nozzle characterized in that a refractory pipe having a through hole with an inner diameter of 0.1 to 5 mm is assembled and built into a part of a blow hole system within a nozzle body.