JP2001219252A - Gas-blowing nozzle for continuous casting - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a nozzle for continuous casting which can prevent the oxidation of the molten metal which causes the nozzle clogging by ensuring the excellent sealability from the atmosphere. SOLUTION: In the gas-blowing nozzle for continuous casting which is provided with a slit-like gas inlet passage capable of blowing the gas inside the nozzle and a ring-shaped feeder to introduce the gas in the gas inlet passage in a nozzle side wall of the refractory, the ring-shaped feeder comprises a male screw to be screwed in the nozzle side wall of the refractory outside thereof, and the ring-shaped feeder which is provided with a stop projecting portion on a part of the male screw and closely connected to a feed pipe. The projecting portion is spot-welded, of a nut having a stopper to be screwed in the ring- shaped feeder.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is mainly used for adjusting the flow rate of molten metal injected from a tundish into a mold in continuous casting of metals, for example, steel, copper alloys and auminium alloys. High performance continuous casting nozzle.

[0002]

2. Description of the Related Art In continuous casting, molten metal is stored in a tundish located above a continuous casting nozzle, and the molten metal is injected into a mold through the continuous casting nozzle at a speed suitable for casting conditions. . The nozzle for continuous casting adjusts the injection speed.

FIG. 4 shows a tundish in continuous casting.
1 shows a configuration of a nozzle and a mold. The molten metal flows from the tundish 1 through the continuous casting nozzle 10 and flows into the mold 2.

FIG. 5 shows an example of an immersion type continuous casting nozzle capable of introducing a gas into the continuous casting nozzle. The continuous casting nozzle 10 is provided with one or more ring-shaped supply parts 7 for screwing the gas supply pipes 5 in the longitudinal direction. In the figure,
Reference numeral 43 denotes a through passage for molten metal and gas, 6 denotes a highly permeable refractory inner wall, a blowout port for supplying an argon gas through the passage, 62 denotes a refractory having erosion resistance to mold powder, Reference numeral 8 denotes a spout of molten metal.

FIG. 6 shows the structure of a conventional ring-shaped supply unit. A gas supply pipe 5 is provided on the refractory nozzle side wall, and this gas supply pipe is connected via a ring-shaped supply section 7 to a slit-like gas introduction passage 4 provided in the refractory nozzle side wall 3. The ring-shaped supply unit 7 is fixed to the nozzle side wall by an iron shell 53.

[0006] The flow rate of the molten metal flowing out of the tundish per unit time reaches, for example, 60 l / min at the maximum. Therefore, a negative pressure is generated in the through passage of the continuous casting nozzle according to Bernoulli's theorem. Due to this, the atmosphere penetrates the nozzle side wall of the refractory and penetrates into the nozzle to oxidize the molten metal. In order to prevent this, argon gas is supplied into the nozzle from a gas supply pipe connected to the continuous casting nozzle to maintain the internal pressure at a certain level or more, thereby preventing the intrusion of atmospheric gas (air).

[0007]

However, for example, when the depth of the molten steel in the tundish becomes as large as 1 m, the static pressure becomes 0.
7 atm, the flow velocity of molten steel at the outlet of the stopper rod is large. Further, since the nozzle side wall of the refractory is, for example, a graphite refractory of about 70 wt% of alumina, complete airtightness cannot be secured, and atmospheric gas cannot be secured from the contact surface with the nozzle side wall of the refractory and the gas supply pipe. Penetrate.

For this reason, a phenomenon occurs in which the gas pressure in the nozzle drops to one third or less of the initial value at a probability of 60% of the total number of nozzles used, and it has been found that atmospheric gas enters the nozzle. ing. For this reason, molten metal such as molten steel is oxidized, causing nozzle closure.

Further, during casting, the temperature of the nozzle refractory is about
Since the temperature exceeds 1000 ° C, cracks occur on the nozzle side wall surface of the refractory in contact with the ring-shaped supply because the thermal expansion coefficient of the steel ring-shaped supply is higher than that of the continuous casting nozzle refractory. However, airtightness is impaired due to this.

[0010] As described above, it is impossible to ensure the airtightness of the contact portion between the continuous casting nozzle and the ring-shaped supply portion only by the contact surface between them, and the difference in the thermal expansion coefficient between the two. Therefore, a gap such as a crack is formed on the side wall of the nozzle of the refractory, so that the air enters and a smooth casting cannot be ensured. The present invention has been made to solve the above problems,
In particular, an object of the present invention is to provide a continuous casting nozzle having high gas tightness.

[0011]

According to a first aspect of the present invention, there is provided a slit-like gas introduction passage through which a gas can be blown into the inside of a nozzle on a side wall of a refractory nozzle, and introduction of a gas into the gas introduction passage. A continuous casting nozzle provided with a ring-shaped supply portion, wherein the ring supply portion has an external thread screwed to the nozzle side wall of the refractory on the outside thereof, and a convex portion of a rotation stop on a part of the external thread. A continuous casting nozzle capable of gas injection, comprising a ring-shaped supply portion provided with a portion and capable of being closely connected to a supply pipe.

[0012] A second aspect of the present invention is a continuous casting nozzle characterized in that the projection is manufactured as a spot weld.

[0013] A third aspect of the present invention is a continuous casting nozzle, characterized in that the spot welding portion has three or more locations on the outer periphery of the ring-shaped supply portion.

According to a fourth aspect of the present invention, there is provided a continuous casting nozzle, wherein the convex portion is a nut having a ring-shaped supply portion provided with a rotation stopper.

According to a fifth aspect of the present invention, there is provided a continuous casting nozzle characterized in that the gas-blowing slit-shaped introduction portion is provided at two or more locations in the longitudinal direction of the continuous casting nozzle. is there.

A sixth aspect of the present invention is a continuous casting nozzle capable of gas injection, wherein the ring-shaped supply portion is made of steel, metal including stainless steel, or engineering ceramics.

According to a seventh aspect of the present invention, there is provided a nozzle for continuous casting, wherein the engineering ceramic is any one of alumina, mullite, silicon carbide, silicon nitride, sialon, and zirconia, or a composite thereof. It is.

[0018]

Embodiments of the present invention will be described with reference to the drawings. As described above, FIG. 5 is a sectional view of the continuous casting nozzle 10 in the longitudinal direction. The continuous casting nozzle is provided with a ring-shaped supply section 7 for screwing a gas supply pipe in the longitudinal direction. In the figure, reference numeral 4 denotes a slit-shaped gas introduction path, 43 denotes a molten metal and gas through path, 6 denotes an argon gas blowing part of a highly permeable refractory, and 62 denotes melting resistance to mold powder. It shows a refractory having a property, and 8
Indicates a jet port of the molten metal.

An embodiment of the present invention will be described with reference to FIGS. 1, 2 and 3. FIG. 1 shows a joint between a continuous casting nozzle of the present invention and a gas supply pipe. FIG. 2 shows a spot welding projection at the joint between the continuous casting nozzle and the gas supply pipe.
Shows the structure of a nut provided with a rotation stop.

A ring-shaped supply portion 7 screwed to the female screw portion of the nozzle side wall 3 of the refractory is joined. The inside of the ring-shaped supply part 7 and the gas supply pipe 5 are provided with a female screw part 9 for, for example, screw connection.

As shown in FIG. 1, a ring-shaped supply pipe 7 is screwed into the nozzle side wall 3, and this ring-shaped supply section is connected to the gas introduction path 4. Further, the gas supply pipe 5 is screwed to the ring-shaped supply section 7. Thus, the tip of the gas supply pipe is connected to the gas introduction path 4 on the side wall of the refractory nozzle, and the argon gas flows from the gas supply pipe 5 to the gas introduction path 4. As the convex portion for preventing the rotation of the ring-shaped supply portion 7 and the gas supply pipe 5, a spot welded portion which is easy to manufacture is desirable, and the number is preferably one or more and three.

As shown in FIGS. 1 and 2, a spot weld 12 for preventing rotation is fixed by a recess 11. Desirably, the spot welding portion 12 can be fixed by the mortar portion 13. Further, FIG. 3 shows the structure of the nut 14 provided with a rotation stopper 140 instead of the spot weld. The nut can be screwed into the ring-shaped supply unit 7 in advance and embedded in the nozzle side wall 3.

The material of the ring-shaped supply section may be made of metal including steel and stainless steel, but has a flexural strength of 10 at normal temperature.
Engineering ceramics having a pressure of 0 MPa or more is desirable from the viewpoint of preventing damage. Here, engineering ceramics include alumina, mullite,
Any of silicon carbide, silicon nitride, sialon, and zirconia, or any of these composites is desirable.

Here, the engineering ceramics will be additionally described. Engineering ceramics are refractories made from highly refined natural inorganic materials or artificially synthesized inorganic compounds, and are ceramics with excellent mechanical properties. Normally, sintering is used to mold engineering ceramics. Sintering methods include reaction sintering, post-reaction sintering, constant pressure sintering, atmospheric pressure sintering, hot pressing, HIP, and ultra-high pressure sintering. is there.

In consideration of the characteristics of the aggregate of engineering ceramics, the cost and strength of the product, alumina is manufactured by normal pressure sintering. The aforementioned mullite is sintered by reaction or normal pressure sintering, silicon carbide is sintered by reaction or normal pressure sintering, silicon nitride is sintered by reaction sintering, pressure sintering, hot pressing, etc., and sialon is sintered by reaction sintering. You.

[0026]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows a continuous casting nozzle provided with a ring # -shaped supply portion according to the present invention.
Here is an example. Approximately 18mm outside diameter and 12m inside diameter of ring-shaped supply pipe
m and length 22 mm. Protrusion for rotation prevention is 3 by spot welding
Places.

The size of the continuous casting nozzle is about 90 in length.
0mm, side wall diameter is about 170mm, penetration path diameter is about 90mm
Met. The nut of the rotation stopper had a diameter of the rotation stopper of 24 mm and an inner diameter of 18 mm, and was screwed into the ring-shaped supply part. Fifty nozzles for continuous casting were manufactured in this shape and implemented.

The material used for the continuous casting nozzle is alumina: 60 wt%, graphite: 24 wt%, SiO:
₂ : Alumina graphite of 9.2 wt% and SiC: 4.7 wt%. The steel ring-shaped supply pipe is manufactured by SC45,
The ring-shaped supply section of the structural fine ceramics was made of alumina and mullite. Alumina was manufactured by a normal pressure sintering method, and mullite was manufactured by a reaction sintering method. The flexural strength of alumina and mullite is 15
It exceeded 100 MPa at 0 MPa and 500 ° C.

Using the continuous casting nozzle having the above structure, the gas blowing rate into the nozzle inner hole was 5 l / min and the low carbon Al
Killed steel was cast. In the conventional nozzle, alumina inclusions were generated in the nozzle inner hole, and the casting was stopped at 3 to 5 heats (each heat was 150 to 200 tons of molten steel). In the nozzle of the present invention, nozzle closing was not observed in the example of 50 heats, and 5 to 7 heats could be cast.

Further, conventionally, a process such as applying mortar around the ring-shaped supply portion, winding an iron shell, and drying is required, but the present invention does not require such a process. Further, the heat insulating material could not be wrapped around the steel shell because the steel shell dissolved. Since the nozzle of the present invention can surround the heat insulating material, the nozzle can be kept warm, the temperature can be prevented from dropping during casting, and the solidification of the molten metal in the nozzle inner hole can also be prevented.

[0031]

(1) With the continuous casting nozzle of the present invention, a more complete seal against atmospheric gas can be obtained, so that nozzle closing can be prevented for a longer time. (2) Further, since cracks and the like do not occur on the nozzle side wall of the refractory during casting, intrusion of atmospheric gas can be more completely prevented. (3) Further, in the conventional nozzle, the work of attaching the iron shell with the mortar, etc. was required. However, since this work is not required, productivity and economic efficiency are improved, and the iron shell is not used. The nozzle can be kept warm by the heat insulating material, and the heat retention during casting improved the effect of suppressing the adhesion of the metal.

[Brief description of the drawings]

FIG. 1 is a view showing a structure of a joint portion between a continuous casting nozzle and a gas supply pipe according to the present invention.

FIG. 2 is a view showing a spot welding portion between a continuous casting nozzle and a gas supply pipe according to the present invention.

FIG. 3 shows a structure of a nut provided with a rotation stopper of a gas supply unit according to the present invention.

FIG. 4 shows a configuration of a tundish, a nozzle, and a mold in the current conventional continuous casting.

FIG. 5 is a view showing a structure of a continuous casting nozzle in a longitudinal direction.

FIG. 6 shows a structure of a joining portion between a current continuous casting nozzle and a gas supply pipe.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Dundish 10 Continuous casting nozzle 2 Mold 3 Refractory nozzle side wall 4 Slit-shaped gas introduction path 43 Penetration path (inner hole) through which molten metal penetrates 5 Gas supply pipe 53 Iron shell 6 Argon gas outlet 62 62 Melting resistance 7 Ring-shaped supply part 8 Molten metal and gas injection port 9 Female screw part 11 Depressed part of nozzle side wall 12 Point welded part 13 Mortar 14 Nut 140 Rotation stop

Claims (7)

[Claims] 1. A slit-like gas introduction path through which gas can be blown into a nozzle, on a side wall of the nozzle of the refractory,
A continuous casting nozzle provided with a ring-shaped supply portion for introducing a gas into the gas introduction path, wherein the ring-shaped supply portion has a male screw screwed to a nozzle side wall of the refractory on the outside thereof, A gas-injectable continuous casting nozzle, comprising: a ring-shaped supply portion which has a convex portion for stopping rotation on a part of a male screw and which can be air-tightly connected to a gas supply pipe. 2. The continuous casting nozzle according to claim 1, wherein the projection is a spot weld. 3. The continuous casting nozzle according to claim 1, wherein the spot welding portion has three or more locations on the outer periphery of the ring-shaped supply portion. 4. The nut according to claim 1, wherein the projection is a nut provided with a rotation stopper screwed into the ring-shaped supply portion.
5. The nozzle for continuous casting according to 4. 5. The continuous casting nozzle according to claim 1, wherein the ring-shaped supply portion is provided at two or more locations in a longitudinal direction of the continuous casting nozzle. 6. The gas blowable member according to claim 1, wherein the ring-shaped supply portion is made of steel, metal including stainless steel, or engineering ceramics. Nozzle for continuous casting. 7. The engineering ceramics according to claim 1,
The continuous casting nozzle according to claim 6, wherein the nozzle is any one of alumina, mullite, silicon carbide, silicon nitride, sialon, and zirconia, or any of a composite thereof.