JPH0710424B2 - Immersion nozzle for continuous casting - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a continuous casting immersion nozzle, and more specifically to a molten metal of which the flow rate is controlled by a stopper from a tundish to a mold immediately below in a non-oxidized state. The non-metallic inclusions contained in the molten metal flowing down in the integrated insertion type immersion nozzle mounted on the tundish for injecting and flowing down are the fitting part of the immersion nozzle and the stopper for controlling the flow rate, that is, the immersion nozzle. A stopper equipped with a gas bubbling function for the purpose of suppressing the adhesion of inclusions to the bosh area so that it will not adhere and accumulate on the bottom part of the stopper with the top bosh area to reduce or hinder the accuracy of flow control. The present invention relates to an integrated insertion type immersion nozzle for continuous casting for a flow rate control system.

(Conventional Technology) A conventional technology of the immersion nozzle will be described by taking an immersion nozzle for continuous casting of steel as an example.

The immersion nozzle for continuous casting ensures the amount of molten steel that flows down from the tundish to the mold in the continuous casting operation. It is well known that this must be done by adjusting the flow rate of molten steel in the dipping nozzle by adjusting the clearance between the top bosh and the fitting part of the bottom of the tundish stopper. The overall size is an important control point. The immersion nozzle is used for the purpose of shutting off the atmosphere during the injection of the molten steel, preventing the oxidation of the molten steel, and preventing the splash of splash generated by the downflow injection, and injecting the molten steel into the mold at a constant flow rate.

In this continuous casting, in continuous casting of steel types such as aluminum killed steel and silicon killed steel in which non-metallic inclusions such as alumina are contained in molten steel to be cast, if the casting is continued for a long time, the tundish Adhesion of non-metallic inclusions to the molten steel flow path surface between the mold and the mold, that is, the inner surface of the immersion nozzle, and the accumulation makes it difficult to control the flow rate at the mating flow rate control part with the stopper at the top bosh section of the immersion nozzle. Since it becomes impossible, a gas pool is provided on the inner wall of the immersion nozzle top bosh section, and an inert gas such as Alcon gas is introduced into the gas pool, and bubbling is performed through the pores toward the inner surface of the immersion nozzle bosh section to form a non-metallic material. A method has been adopted that suppresses the deposition of inclusions and enables stable long-term continuous casting operations. To have. However, the placement of the gas pool on the top of the immersion nozzle top bosh is difficult to exactly aim at the position due to the restrictions during the manufacturing of the nozzle, that is, the restrictions on the method of filling the material into the mold. Since the probability of deviation or deformation is around 30%, there is a large variation in the effect of suppressing deposition of non-metallic inclusions by gas bubbling, and a gas pool is provided in the wall of the immersion nozzle bosh. The structural strength of the top of the submerged nozzle is reduced, and cracks are generated due to impact when the flow rate is controlled by the stopper, and molten steel leaks due to the expansion of cracks and abnormal flow rate control due to abnormal melting or loss of the submerged nozzle bosh. This has been an unacceptable important issue in continuous casting, causing serious troubles such as breakouts.

(Problems to be Solved by the Invention) An immersion nozzle for continuous casting of steel will be described as an example. As described above, when performing continuous casting operations for a long time in continuous casting of steel types containing non-metallic inclusions such as aluminum-killed steel and silicon-killed steel, suppressing deposition of non-metallic inclusions on the immersion nozzle bosh section The variation of gas bubbling in the bosh portion for the same has a serious adverse effect on the quality and yield of continuously cast slabs, and also on the cost, and the present invention relates to the immersion gas bubbling in the immersion nozzle bosh portion. It was made with the aim of stabilizing the structure and the structure.

The installation of the gas pool in the immersion nozzle has been devised over the entire length in response to the problems in the continuous casting operation. Suppressing the inclusion of inclusions at the fitting part with the stopper at the top bosh is extremely effective due to gas bubbling, but variations in the arrangement of the gas pool not only greatly reduce this effect, Since the present invention has a secondary adverse effect of making the structural strength of the top part of the immersion nozzle unstable, the present invention solves these problems by adding a reinforcing material to the gas pool, and continuous casting of steel is performed many times for a long time. The purpose is to enable smooth operation without adversely affecting the yield and quality of cast slabs.

(Means for Solving Problems) In the present invention, attention is paid to the above problems, and in order to solve the problems, the following structure and action are provided.

The immersion nozzle for continuous casting according to the present invention has a top bosh section,
It has an inert gas bubbling function to prevent the adhesion of non-metallic inclusions, and the funnel on the upper bent portion is for blowing gas into the bosh because it can stably control the molten steel flow rate by the stopper until the end of casting. Shaped gas pool (hollow chamber) is made of carbon fiber of 2 microns to 3.5 mm, or more than one ceramic fiber element such as alumina fiber, and the size of each side is 3 to 50 mm. The reinforcing material is knitted and reinforced by knitting, and by improving the accuracy of the gas pool arrangement on the top bosh portion, the bubbling of inert gas is stabilized and the accuracy of achieving the objective is greatly improved. It is what

Here, the reasons for limitation will be described.

The reason for limiting the reinforcing material to the ceramic fiber such as carbon fiber or alumina fiber is that it is highly reliable because it has good workability for placement during cold during manufacturing of the immersion nozzle and hot during use, and does not deteriorate. In addition, it is relatively inexpensive and easily available.

The reason why the thickness of the wire is limited to 2 to 3.5 mm is that the wire cannot be obtained below 2 μm, and above 3.5 mm due to thermal expansion at high temperature during firing and use during manufacturing of the immersion nozzle, This is because the structure of the immersion nozzle is adversely affected. When the mesh size of the wire having this diameter is knitted into a mesh, if the size of the mesh is 3 mm or less, the balance with the immersion nozzle material aggregate particles is disturbed and the dispersion of the aggregate is hindered, resulting in partial dispersion. This is because if the thickness is 50 mm or more, the mesh spacing is too wide and the effect is reduced.

Next, the present invention will be described with reference to the following embodiments with reference to FIGS.

〔Example〕

In FIG. 1, 1 is an immersion type immersion nozzle and 2 is a stopper, both of which are made of Al ₂ O ₃ -C.

Numerals 7 and 8 are fitting portions for controlling the flow rate of the molten metal at the stopper nozzle bottom portion and the immersion nozzle top bosh portion in this type of flow rate control method, and suppress the adhesion and deposition of non-metallic inclusions at this portion. For this purpose, the entire area of the gas pool 5 was reinforced from the outside with a square mesh of carbon fiber strands having a thickness of 0.3 mm and a side of 3.5 mm.

With this reinforcement, the maximum aim is to stabilize the position of the upper bent portion 5'in Fig. 2 and to protect it from physical shock.

The shape of the mesh of the present invention is suitably a polygon such as a square, a rectangle, and a hexagonal shape. 3 is a tundish tuyere brick, and 6 is a suction port. It is also possible to deal with the way of forming the bent portion 5'of the upper end of the gas pool 5, that is, the connection of two straight lines (the shape shown in FIG. 2) or the one using an arc. Further, FIG. 4 shows an example of the shape of the gas pool 5 of the upper bent portion 5 ″, 5.

(Effect of the invention) The effect of the embodiment is that inert gas bubbling is extremely possible because the deposition precision of the non-metallic inclusions at the fitting portion of the immersion nozzle and the stopper can be aimed at the gas pool placement accuracy. It is possible to stably and exactly suppress the amount of gas with the minimum required amount, and as a structure against the physical stress when opening and closing the stopper at the same part from the gas pool arrangement on the bosh. Since the strength is greatly increased and stabilized, the reliability of the casting operation is greatly improved, the quality of the slab is stabilized at a high level, and it is possible to operate for a longer time. It will bring about a great effect in.

[Brief description of drawings]

The drawings show an embodiment of the present invention, in which FIG. 1 is a longitudinal sectional view showing an engagement between a dipping nozzle and a stopper, and FIG.
FIG. 3 is a vertical cross-sectional view showing details of the gas pool, FIG. 3 is a perspective view of a reinforcing wire mesh, and FIG. 4 is a vertical cross-sectional view showing a shape example of the gas pool. 1 ... Insertion type immersion nozzle, 2 ... Stopper, 3 ...
… Tundish Tuyere Brick, 4 …… Top Morning Glory, 5…
… Gas pool, 5 ′, 5 ″, 5 …… Upper bent part, 5A reinforcement, 6 …… Gas inlet, 7,8 …… Mating part,

Claims (4)

[Claims] 1. A dipping nozzle with a funnel-shaped mesh-like reinforcing material adapted to the shape of the funnel-shaped gas pool in an insertion-integrated dipping nozzle having a funnel-shaped gas pool with a bent upper end for blowing gas into the bosh. Immersion nozzle that reinforces the gas pool structure part, the reinforcement material is made of inorganic ceramic fiber such as carbon fiber, alumina fiber, etc. Immersion nozzle for continuous casting, which is formed as a funnel shape. 2. The reinforcing material for reinforcing the gas pool manufacturing portion has a mesh shape, and one side of the mesh has a size in the range of 3 mm to 50 mm, and the arrangement is a single layer. The immersion nozzle for continuous casting according to 1. 3. The continuous casting immersion nozzle according to claim 2, wherein the reinforcing material for reinforcing the gas pool manufacturing portion is arranged in a plurality of layers or more. 4. The immersion nozzle for continuous casting according to claim 1, wherein the reinforcing material for reinforcing the gas pool manufacturing portion is arranged partially in the axial direction (length direction) and on the circumference.