JPS58361A - Nozzle for casting of molten metal having flow regulating body - Google Patents

Abstract

PURPOSE:To ease the nonuniformity in the velocities of flow between a central part and side corner parts, to prevent stagnation and to make the homogenizing of steel quality possible by disposing a flow regulating body in a flow hole of a nozzle for casting of molten metal. CONSTITUTION:This consists of a flow regulating body 3 provided in a rectangular nozzle 1, wherein the velocity of flow in a central part A is decreased by the body 3 and is harmonized with the velocities of flow in side face parts B. The velocities of flow in the central part and side corner parts in the casting nozzle and molds are made uniform and the partial stagnation and solidification of molten steel are eliminated. Since the molten steel is moderately agitated by the body 3, the nonmetallic inclusions in the molten steel are diffused uniformly in the molds and the generation of flaws on the surfaces of steel plates is prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a molten metal casting nozzle used for injecting molten steel into a mold in continuous casting equipment, mainly in high-speed continuous casting of thin steel billets.

In conventional continuous casting of steel, it is believed that the method of casting into the mold rather than the tundish has a greater influence on the steel quality of the piece, and for this reason, a casting nozzle with an extended nozzle length below the mold surface is used. This method was used to prevent the molten steel from being oxidized or entrained in the air at the time of dropping. Recently, it has been considered to cast steel slabs as thin as possible from the casting process, and the issue has become how to make the rolled steel plates homogeneous, uniform in thickness, and free from flaws on the surface.

The causes of uneven steel quality and billet thickness and defects on the steel plate surface are as follows:
It is thought that this occurs from the time it is cast into the mold through the casting nozzle to when the steel piece (solidified shell) that has begun to solidify is pulled out, and the main cause is believed to be the flow velocity when pouring the molten steel. You can see it. In other words, in continuous casting, steel slabs are always drawn out at a certain speed, but there is little opportunity for non-metallic inclusions in the molten steel to separate due to the agitation effect of the injection flow in the mold. Even inclusions are caught in the shell during solidification, and this becomes surface flaws when rolled.

Moreover, the flow velocity of the molten steel injected from the casting nozzle in the mold is 5% lower in the center and side corners due to frictional resistance. In other words, in the side corners, solidification is likely to be accelerated due to stagnation, while in the center S, the flow velocity is high and it tends to penetrate deep while maintaining high temperature, so solidification tends to be delayed, resulting in a large difference in the solidification level and an increase in the thickness of the solidified shell. This results in unevenness, and the non-metallic inclusions do not diffuse uniformly, resulting in uneven fiber quality. It is uniform and thick due to continuous casting.
This is a problem that must be solved in order to obtain defect-free rope boards. Therefore, by injecting at the same flow rate into the center and side corners of the mold to make the stirring action uniform, a homogeneous piece of steel can be used to prevent bulges in the center of the piece, elution loss due to destruction of the surface skin, and flaws in the steel plate. It is necessary to suppress the occurrence of such outbreaks. In particular, as the cross-section of cast steel slabs becomes thinner (thinner), thickness adjustment and non-uniformity of steel quality due to differences in partial solidification timing have become noticeable and unavoidable. No. 39524, Publication No. 52-21303
The mold has a cross-sectional shape that is cylindrical at the top and rectangular at the bottom, which is already known in No. There is a continuous casting immersion nozzle designed to uniformly distribute inclusions and reduce the accumulation of non-metallic inclusions near the surface, thereby preventing the occurrence of defects.

For example, the immersion nozzle (5o) of JP-A No. 49-39524
has a shape as shown in FIG. 3 (FIG. 1 of the accompanying drawings of this specification), and is said to be able to achieve the above object. . However, with the same shape, the flow velocity is still lower at the center (A) and both sides (B), due to the influence of frictional resistance from the mold walls.
If stagnation occurs near (B) and the flow velocity of the molten steel in the center part (A) increases, it penetrates deeply into the mold and becomes a thin and long solidified shell.If it is pulled out as it is, the center part has not yet solidified well and the surface becomes thin. There was a problem in that it was not possible to obtain a piece of rope with a uniform thickness due to the occurrence of molten steel flowing out, bulging in the center, twisting, etc.

The present invention was created to solve the above-mentioned problems, and its purpose is to provide a molten metal casting nozzle that can be used for high-speed continuous casting of 11-type steel slabs, which is robust and has tS steel in the mold. This technology aims to alleviate the uneven flow velocity between the center and side corners when molten steel is injected, prevent stagnation, and homogenize the quality of the steel by uniformly stirring the molten steel. A flow regulator is provided in the molten #l/1lXiI hole of the casting nozzle whose cross section is the same as that of the mold and the injection hole corresponding to the shape of the rope piece, or a shape similar to that, so that there is no partial stagnation or solidification of molten steel. Providing sealing properties eliminates air oxidation of molten steel in the mold, and blowing inert gas prevents the precipitation of nonmetallic inclusions, which eliminates the cause of defects that appear on the homogeneous steel plate surface and improves yield. The aim is to improve productivity by increasing the casting speed.

The present invention relates to a nozzle for casting molten metal having a flow regulator, characterized in that a flow regulator is disposed in the flow hole of a nozzle for casting molten metal in which at least the tip of the flow hole of the molten metal has a flat or nearly flat shape. This is related.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A nozzle for casting molten metal having a flow regulator according to the present invention will be specifically described below based on embodiments shown in the accompanying drawings.

First embodiment; Figure @2 shows a casting nozzle according to this embodiment,
Figure 2a shows a rectangular nozzle (1) with a flow regulator (3), which weakens the flow velocity in the center part (A) and harmonizes it with the flow velocity in the side parts (B). It is something.

Figure 2b shows that the molten steel that has flowed into the mold (2) through the upper molten steel outflow hole (4) collides with the -@11 fluid (3) to soften the flow velocity in the central part (A), change the flow direction, and stir the molten steel. The aim is to achieve homogeneity and average the flow velocity in each part. In this case, it is desirable to use the steel with the inside filled with molten steel, but if the sealing properties are lost and a liquid level occurs inside, inert gas is added to prevent air from entering the upper space. It is a good idea to blow it in. In addition, considering the downward movement, it is desirable that the position of the flow regulator (3) is such that it does not receive molten steel in the air. (Especially when a linear surface is formed in the nozzle, the flow velocity in the central part becomes faster.) Note that the cross-sectional shape of the rectifying end is not limited to the eccentric circle or trapezoid of this example, but also circular, square, rectangular, concave plate, etc. Any shape may be used as long as the flow velocity can be averaged and homogenized by stirring.It goes without saying that the internal cross-sectional shape of the nozzle (1) is not limited to a rectangle, but may be an ellipse or a shape close to it. stomach.

Second Embodiment: FIG. 3 shows a casting nozzle according to this embodiment, in which a plurality of flow regulators are used as shown. 3rd a
In the figure, the upper molten steel outflow hole is also elongated in the same shape as the connection part of the rectangular nozzle fl), and a plurality of flow regulators (3) that receive the molten steel flow are placed on the side wall, which is the long side of the molten steel flow hole of the nozzle (1). Once the rope collides with each fluid regulator (3), it weakens the flow velocity and is agitated to eliminate stagnation around the sides and allow it to flow down into the mold.

Figure 3b shows the same circular connection part as the conventional upper molten steel outflow hole, where the molten steel flow hole widens at the end so that the tip can fit into the mold, and the molten steel flow hole has an opening on the long side of the side wall. The flow regulators (3) and (31) each having a shape similar to the above were disposed. The side surfaces of the molten steel flow hole in this shape are particularly prone to stagnation, but these flow regulators disperse and average the flow velocity.

In addition, the cross-sectional shape of the above-mentioned fluid regulator (3) is not limited to this example,
Any shape such as a flat plate, square, trapezoid, inverted triangle, etc. may be used as long as it can average the flow velocity of the molten steel and homogenize it by stirring.

Third and fourth embodiments; Figures 4 and 5 respectively show the third and fourth embodiments of the casting nozzle according to the present invention. In other words, the third embodiment; this embodiment, as shown in FIG. Porous body (5) (or pores)
The porous body (5) is composed of a plurality of porous bodies (5) disposed below each fluid regulator and one part slightly above the fluid regulator.

Fourth embodiment; As shown in FIG. 5, this embodiment differs from the third embodiment in that the arrangement of the flow regulator (3) and porous body (5) is The flow velocity distribution (3) and the flow regulation (31°) protruding from the short side wall eliminate flow velocity dispersion and stagnation in various places. In addition, there is a porous body (5) on the bottom of the central fluid regulator (3), and a plurality of pores (6) at the lower position, a protruding fluid regulator (3") buried inside the porous body (3"), and a lower position. It has a configuration in which a pore portion (6) is provided.

3 above. In the fourth embodiment, the flow regulating (3) surface has parts exposed to high flow velocity and parts where there is almost no flow, and in particular near the parts where there is no flow, solidification of molten steel and non-metallic inclusions occur. For example, on the lower side of the flow regulator (3), stagnation often occurs and solidification of molten steel occurs, and on the side, the flow tends to be laminar and monotonous, causing non-metallic inclusions to precipitate. Solidification of molten steel is likely to occur. In addition, in consideration of the possibility that stagnation may occur on the upper surface of the fluid regulating (3), it may be necessary to provide a gas blowing section to the upper surface.

The fluid with protruding short sides is shown only in the fourth embodiment, but if the molten steel has a long vertical inner wall, when the molten steel flows along it, stirring will be insufficient, which tends to cause a local temperature drop.

Therefore, it is desirable to intentionally disturb the molten steel and mix it with the molten steel descending inside, instead of allowing it to descend monotonously up and down for a long time. In the third embodiment as well, it is preferable to provide a flow regulator projecting from the short side as necessary.

Fifth Embodiment; Fig. 6 shows a fifth embodiment of the casting nozzle according to the present invention, and this embodiment applies the casting nozzle to a sliding nozzle device (hereinafter referred to as "rSN device"). This is related to the case where

The casting nozzle (1), which has a sealing part (8) on the contact surface with respect to the lower fixing plate (9) of the three-piece SN device, directs the flow at 21 points vertically at the center of the long side wall surface and at further short points. A protruding fluid regulator (3") is placed on the side wall relatively above the assembled fluid regulator to adjust the flow velocity disturbance. In this example, the lower end of the SN device and the connection part are sealed with gas. Although the figure shows this, it is not necessary if the inside of the casting nozzle (1) is kept airtight.

If the molten steel falls freely, the contact with the gas phase increases and it becomes difficult to maintain the quality of the steel, so it is desirable that the molten steel whose flow rate is restricted by the SN device fills the nozzle 11). In case a gas phase is formed inside the steel, the part that comes into contact with the SN device is sealed with gas to prevent changes in the steel quality. In addition, when injecting inert gas from various places, it is desirable that the bubbles float up and flow down into the mold (2) with the flow. It is necessary to consider the structure and dimensions of the

The gas seal may be placed from the outside of the connection rather than from the inside. Note that QOI is a gas supply pipe.

Sixth embodiment; Fig. 7 shows a sixth embodiment of the casting nozzle according to the present invention, and the casting nozzle of this embodiment has a flat part at the tip and an irregularly shaped bottom part. This is a nozzle, for example, a nozzle for casting H-shaped steel pieces.

The upper connecting part is circular or elliptical, and the tip of the casting nozzle matches the shape of the H-shaped mold into which it is poured.The molten steel flows down into the gap (11) that corresponds to the horizontal bar of the H at a position below the middle of the overall length of the casting nozzle. When the left and right long sides (1
2) so as to block a part of the gap (11) from the flow regulator (3). In order to receive the dispersed molten steel flow and allow the flow to flow to both corners of the long side, a protruding combing body (3") is installed on the long side at a position lower than the narrowing part (11) and the flow regulating body (3). It is placed in the center of the wall.

The shape of these flow regulators divides the molten steel flow into two at the gap (11), and the protruding flow regulators placed below the left and right long sides allow the flow to flow evenly to the corners of the long sides, and eliminates the accumulation of molten steel. It is recommended to use a combination of stacked shapes such as a house shape, a triangle, an inverted triangle, a horizontal ellipse, a concave plate, and a square, taking into consideration the shape and location that will not cause local coagulation.

As described above, the casting nozzle according to the present invention can achieve the following effects.

(1) By arranging a flow regulator in the flow hole, the flow velocity in the center and side corners of the casting nozzle and mold is made uniform, eliminating partial retention and solidification of molten steel.

(2) Since the molten steel is appropriately agitated by the above-mentioned flow regulation, non-metallic inclusions in the molten steel are evenly dispersed within the mold, thereby preventing the occurrence of flaws on the surface of the steel plate.

(3) By sealing the upper connection part of the casting nozzle with an inert gas, oxidation of the molten steel can be prevented, and changes in the quality of the steel can be prevented.

(4) By blowing inert gas through the pores or porous body in the molten steel flow hole of the casting nozzle, it is possible to prevent the precipitation of nonmetallic inclusions and eliminate scratches that occur on the surface of the steel plate.
It is also possible to improve yield.

[Brief explanation of the drawing]

Figure 1 is a structural diagram showing the conventional submerged nozzle structure;
4, 5, and 6 are side sectional views showing a casting nozzle according to the present invention, FIG. 3 is a side sectional view and a plan view, and FIG.
The figures are a cutaway perspective view and a bottom view of the casting nozzle of the sixth embodiment. (1) Casting nozzle (2) Mold (3) Fluid regulating patent applicant Kurosaki Ceramics Co., Ltd. Agent Moritake Ito (and one other person) No. 1
Figure A Figure 2 Figure 3 (a) (b) Figure 4 Figure 6

Claims (1)

[Scope of Claims] +11 Molten metal having a flow regulator, characterized in that a flow regulator is disposed in the flow hole of a nozzle for casting molten metal in which the tip of the molten steel flow hole has a flat or nearly flat shape. Casting nozzle. (2) A molten metal melt having a flow regulator according to claim 1, characterized in that a porous body or pores for blowing an inert gas are provided in the molten steel flow hole and/or in the connection part of the upper part of the nozzle. Nozzle for metal casting.