JPS60130456A - Nozzle for pouring molten metal - Google Patents

Abstract

PURPOSE:To prevent intrusion of non-metallic inclusions into the deep part of a molten metal and the disturbance of the molten metal surface by providing resistance parts to provide resistance to the flow of the molten metal into a nozzle to be passed therein with the molten metal. CONSTITUTION:An immersion nozzle 1 for high-speed continuous casting is formed to have a rectangular section and plural resistance parts 2 are provided in the nozzle 1 to be passed therein with a molten metal. A flange part 3 to be fixed to a tundish is formed to the top end thereof and the aperture at the bottom end is used as a discharge hole 4. The resistance parts 2 are formed of suitable refractories into a circular columnar shape and are fixed by directing the axial line in the thickness direction of the nozzle 1. The intrusion of non-metallic inclusions deep into the molten metal is thus prevented and at the same time the disturbance of the molten metal surface is eliminated, by which the billet having high cleanliness is obtd.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a nozzle used, for example, when pouring molten metal such as molten steel into a mold in continuous casting equipment.

As is well known, continuous casting is a method in which molten metal poured into a mold is cooled, and the resulting solidified shell is pulled out of the mold and further cooled to obtain a slab. Submerged nozzles are commonly used to prevent oxidation, and powder is added to the mold to prevent oxidation and provide lubrication between the mold and the solidified shell.

Recently, there has been a trend to increase casting speed in order to improve productivity, but this has led to the following problems. In other words, when casting at high speed, it is necessary to increase the amount of metal poured into the mold per unit time, but depending on the pouring method, powder may be drawn into the molten metal, which may cause internal defects or Surface defects may occur.

When pouring metal into a mold through an immersion nozzle, increasing the flow rate of the molten metal or increasing the cross-sectional area of the immersion nozzle can increase the amount of molten metal poured per unit time. If the speed is increased, non-metallic inclusions may penetrate deep into the molten metal in the mold and become trapped inside the slab without floating to the surface of the molten metal, resulting in problems such as deterioration of the cleanliness of the slab. arise.

In order to solve this problem, it is possible to promote the floating separation of inclusions by oriented the discharge port at the tip of the nozzle upward, but if this is done, the molten metal level in the mold will be disturbed. This causes the powder to become entangled and the various problems associated with it as described above. If the pouring speed is further increased, the molten metal flow directly hits the solidified shell in the mold, resulting in a so-called breakout in which the solidified shell remelts and the molten metal inside spouts out, making continuous casting impossible. It may lead to a serious accident.

On the other hand, as a method of increasing the amount of molten metal poured per unit time without increasing the flow rate of the molten metal, it is possible to widen the molten metal discharge area of the nozzle, and such a nozzle
No. 8-107245. However, in the case of a nozzle with a wide molten metal discharge area, although a uniform molten wA flow is originally preferable, localized flow, that is, uneven flow, is likely to occur, which may impede the homogenization of the slab. There is. On the other hand, in order to widen the molten metal discharge area, it is possible to provide a large number of discharge ports and reduce the diameter of each discharge port. There was a great risk of this, and it was difficult to secure a sufficient amount of molten metal to perform high-speed casting.

In any case, with conventional nozzles, in order to pour enough metal for high-speed continuous casting, it is necessary to reduce the penetration depth of non-metallic inclusions into the mold to facilitate their floating separation. The reality is that it has not been possible to satisfy both the problem of suppressing the disturbance of the surface of the hot water and pouring the hot water at the expense of one of them to some extent.

This invention was made in view of the above circumstances, and it is possible to pour molten metal without causing non-metallic inclusions to penetrate deeply into the molten metal in the mold, and without disturbing the molten metal surface in the mold. The third feature of the present invention is that a resistance part is provided in the interior where the molten metal is to flow, providing resistance to the flow of the molten metal. .

Embodiments of the present invention will be described below with reference to the accompanying drawings.

1 to 3 are cross-sectional views showing one embodiment of the present invention, and the immersion nozzle 1 shown here has a rectangular cross section, and has a plurality of resistor parts 2 provided therein, and further has an upper end portion. A flange portion 3 for fixing to a tundish (not shown) is formed on the flange portion 3, and a lower end opening is formed as a discharge port 4.
It is said that the structure is as follows. The resistance part 2 serves as a resistance to the flow of molten metal to be poured into a mold (not shown), and is formed into a cylindrical shape as shown in the figure by an appropriate refractory material, and is connected to the immersion nozzle 1. It is fixed with the axis oriented in the thickness direction. As shown in FIGS. 1 and 4, each resistance section 2 is arranged in multiple rows (three rows in the illustrated example) along a direction (i.e., horizontal direction) perpendicular to the flow direction of the molten metal (arrow A in the figure). ) with a constant pitch W, and the pitch W in each row is shifted by W/2 as shown in Figure 4-4.In other words, the resistor parts 2 are arranged in a so-called triangular array. There is. Here, if the diameter of the resistance section 2 is d and the interval between each row is l, the ratio W/d of the diameter d of the resistance section 2 and the pitch W is set to 2 to 3, and the resistance section Diameter d of 2 and spacing between each row! It is preferable to set the ratio 1/d to 2 to 4. In other words, when W/d<2 and R/d<2, the flow resistance to the molten metal becomes too large, and if the molten metal solidifies or nonmetallic inclusions adhere to the periphery of the resistance part 2, the nozzle may become clogged. This is likely to occur, and as a result, there is a high risk that the casting flow rate will not be secured. Also W/d>
If l/d > 4 in 3, the flow resistance to the molten metal becomes too low and the pouring flow cannot be slowed down sufficiently, resulting in non-metallic inclusions being made to penetrate deeply into the molten metal in the mold. There is a lot of danger of it getting lost.

However, when pouring metal into a mold from a tundish in continuous casting equipment using the immersion nozzle 1 configured as described above, the flow of molten metal flowing inside the immersion nozzle 1 is slowed down by the flow resistance of the resistance part 2, and therefore the flow of the molten metal is slowed down. Because the downward kinetic energy within the mold is reduced,
Non-metallic inclusion 1! Since the IC can be floated and separated, and the discharge port 4 can be directed downward, disturbance of the molten metal level in the mold can be prevented. Furthermore, in the above-mentioned immersion nozzle 1, since there is no particular factor that reduces the area of the discharge port 4, a sufficient amount of Im can be supplied to the mold even when performing high-speed casting.

Note that the nozzle of the present invention is not limited to the shape shown in FIGS. 1 to 3, but may have the configuration shown in FIGS. 5 to 7, for example. That is, in the nozzle 1O shown in FIGS. 5 to 7, the first zone 12 from the upper end where the flange portion 11 is provided to a position of a predetermined dimension is cylindrical, and the discharge port 13 at the lower end from the first zone 12 is cylindrical.
The second zone 14 up to the second zone 14 has a hollow rectangular shape, and the resistance section 2 is provided inside the second zone 14. Even with the nozzle 1O configured in this way, the resistance portion 2 acts to decelerate the flow of the poured metal, so as shown in FIGS.
The same effects as the immersion nozzle 1 shown in the figure can be obtained.

Next, experimental examples conducted to confirm the effects of the present invention will be described together with comparative examples.

Experimental example ■ The deceleration effect on the injection flow was confirmed.

Immersion nozzle (length 10
00IIi11 (cross-sectional area: 450 x 70 mJ) was fabricated, and a cylindrical resistance section (diameter d-50111+
11) were arranged in three rows in a triangular pyramid row. On the other hand, a nozzle without a resistance part was used as a comparative example.

When I measured the discharge flow rate by flowing water, the flow rate was 8.61.
/sec, in the present invention column, the flow rate is 70CI/sec.
SeC, whereas in the comparative example, 25Qc+a,
/Sec, and it was confirmed that the provision of the resistance section had a deceleration effect of about 70%.

Experimental Example ■ As an example of the present invention, a nozzle having the shape shown in Figs. 5 to 7 is used, the length of the first zone is 5O01I1117-, the inner diameter is 70Illl, and the length of the second zone is 4001- At the same time, the cross-sectional dimensions of the discharge port are set to 70X4.
00- Closed. Furthermore, the resistance part provided inside the second zone is cylindrical, its diameter d=50+u+, and the pitch W-1.
00u+, the interval between each row was set to 1-100nv+, and the triangular pyramid array was arranged in 1.3 rows.

As a comparative example, the inner diameter is 70111, the discharge number is 2, and the discharge opening diameter is 7.
A nozzle A1 with a discharge opening angle of 159 downward and a nozzle B having a shape shown in FIGS. 1 to 3 and without a resistance portion were used.

SPCE Im with JISM rating was cast into a 230X1500-size mold at a casting speed of 1.5 m/*.

When the amount of inclusions in the obtained slab was investigated by the slime electrolytic extraction method, when the nozzle of the present invention example was used, the amount of inclusions with a diameter of 50μ or more was 0.021 (1/1
0 kQ -5teel, whereas when using nozzle A of the comparative example, it was 0.30 ml/10
kg・5t13e+, and when the nozzle 8 of the comparative example was used, it was 0.21 so/1o ko -5teel.

8- Also, when we measured the fluctuation range of the mold level during casting, when the nozzle of the present invention was used, it was ±6g+
m, and on the other hand, when nozzle 8 of the comparative example was used, it was ±151111.

From these experimental examples, it is clear that the nozzle according to the present invention
It was found that the flow rate of the flow could be sufficiently reduced, and that it was also effective in reducing nonmetallic inclusions.

As is clear from the above description, according to the present invention, since the resistance section is configured to decelerate the flow, the high-fi
Even when a sufficient amount of molten metal is poured for continuous casting, it is possible to prevent non-metallic inclusions from penetrating deep into the molten metal, and at the same time prevent the molten metal surface from being disturbed. When continuous casting is performed using this method, there are advantages such as being able to obtain slabs with high cleanliness and no surface defects or internal defects.

[Brief explanation of drawings]

Figures 1 to 3 are schematic diagrams showing an embodiment of the present invention, in which Figure 1 is a longitudinal cross-sectional view, and Figure 2 is a cross-sectional view of Figure 1.
Figure 3 is a diagram showing the ■-■ line diagram in Figure 1, Figure 4 is an explanatory diagram showing the arrangement of the resistor parts, and Figures 5 to 7 are other embodiments of the present invention. It is a schematic diagram showing
5 is a vertical sectional view, FIG. 6 is a view taken along the line VI-Vl in FIG. 5, and FIG. 7 is a view taken along the line Vl-Vl in FIG. 1... Immersion nozzle, 2... Resistance part, 1O...
Nozzle, d...Diameter of resistance part, ! ... Spacing between rows of resistance sections, W... Pitch of resistance sections. Applicant Kawasaki Steel Co., Ltd. Agent Patent Attorney Takehisa Toyota (one idiot) 11- To

Claims (2)

[Claims] (1) A nozzle for pouring molten metal, characterized in that a resistance portion that provides resistance to the flow of molten metal is provided inside the interior through which molten metal is to flow. (2) The plurality of resistance parts each having a circular cross section are arranged in a plurality of rows at a constant pitch along a direction perpendicular to the flow direction of the molten metal, and the pitches of the resistance parts in adjacent rows are shifted from each other. Furthermore, the ratio W/d of the diameter d of the resistance part and the pitch W of the resistance part in each row is 2 to 3, and the ratio l/d of the diameter d of the resistance part and the interval l between each row is
2. The molten metal pouring nozzle according to claim 1, wherein the molten metal pouring nozzle is set to be 2 to 4.