JPS5813452A - Adding method of powder to molten metal - Google Patents

Abstract

PURPOSE:To prevent the clogging of a powder adding nozzle and to prevent the quality degradation of an ingot by analyzing the sticking distance of the sticking jet generated in the metallic flow in the powder mixing part of a continuous casting device and providing the opening part of said nozzle in the position higher than the sticking position. CONSTITUTION:The molten steel flow 5 flowing down from a tundish nozzle 2 is bent by the vortexes of air generated in a tightly closed mixing part and sticks on the inside wall 8 of the mixing part. In order to prevent the generation of the internal defects of an ingot, it is necessary to prevent the clogging of a nozzle 6 for adding powder by locating the opening part 9 at the leading end of said nozzle 6 in the position higher than the sticking distance Xr of the stucking jet 5. Said Xr can be determined geometrically and empirically by the equation. Here, Xr; the distance of the sticking jet mm., Ws; the outflow diameter of the down flow metal mm., alpha; the angle of inclination of the wall 8 deg., R; the radius of curvature of the sticking jet mm., theta; the angle of collision of the sticking jet deg., Y; the distance between the point where the centerline of the sticking jet and the wall 8 intersect and the sticking jet line mm..

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention is directed to a method of adding powder to molten metal flowing down from a tamp pusher into a mixing nozzle in continuous casting.

Traditionally, slabs manufactured by continuous casting have center segregation,
Alternatively, internal defects such as center porosity occur. In order to prevent such internal defects, electromagnetic stirring treatment of mold-like molten steel has been widely adopted, and although it has been somewhat effective, it is not sufficient.

On the other hand, it is known that internal defects can be significantly improved by adding cold materials such as iron wire, iron pieces, iron powder, etc. to the molten steel flow during pouring, and the addition of iron powder is particularly effective. Various methods for adding iron powder have been proposed, but in continuous casting, the addition of iron powder, etc. is carried out in a mixing nozzle that also serves as an immersion nozzle, isolated from the atmosphere. Figure 1 is a diagram showing the addition of cold material by the addition nozzle in the mixing nozzle.
(3) is a mixing nozzle, and (4) is a mold (6) which is an addition nozzle. The molten steel ordered to the tank push (1) is injected from the tank push nozzle A/ (2) into the mixing nozzle (3) and cast into the mold (4). Iron powder (7) is added to stream (5) from addition nozzle iv (a). In such an addition method, the addition nozzle yv (6)
A method has been proposed in which iron powder is added to the molten steel stream by spraying it using a carrier gas. (Unexamined Japanese Patent Publication No. 53-130230
However, since iron powder is sprayed onto the molten steel flow together with a carrier gas such as Ar gun, this method has the disadvantage that the carrier gas gets caught up in the molten steel flow, causing bubbles in the molten steel and causing internal defects. For this reason, it is preferable to add the iron powder by allowing the iron powder to naturally flow without using a carrier gas, and for this purpose, it is necessary to set the inclination angle of the addition nozzle to about 40° or more. However, if such an angle is provided, the addition nozzle /1/
The tip opening (9) of (6) is located below the mixing part. Furthermore, when the molten steel flows down within the sealed mixing section, a vortex of air is generated; the Coanda phenomenon occurs in which the molten steel flow bends and collides with the inner wall (8) of the mixing section.

If the opening (9) of the steel is located below the adhesion distance Xr, the opening (9) will be blocked by molten steel, making it impossible to add iron powder.

This invention was made to deal with such drawbacks, and the addition nozzle is installed so that the tip opening (9) of the addition nozzle is above the attachment position by analyzing the attachment distance of the attachment jet. This device adds iron powder, and its characteristics are that the distance Mlk (Xr) of the adhesion jet is determined by the following formula, the opening of the addition nozzle is provided within the Xr range, and the powder is removed from the addition nozzle. It is characterized by being added to molten steel. Outflow diameter of metal (Parrot) α: Inclination angle of the inner wall of the mixing section (R = radius of curvature of the adhering jet (M) θ: Collision angle of the adhering jet on the inner wall of the mixing section (0) (3rd
Page) The present invention will be explained below based on the drawings. FIG. 2 is a diagram showing an analytical model of the adhesion jet. Tandetshu Nozu l
The molten steel flow (5) flowing down from (2) bends as shown in the figure to become a sticking jet and collides with the inner wall (8) of the mixing section.

In the figure, the distance of Xr from the lower end of the tundish nozzle /l/ (2) is the upper limit of the adhesion jet, and within this Xr value, the attached nozzle will not be clogged by the adhesion jet, so add within this Xr range. A nozzle tip opening (9) may be provided. The geometrically determined XrO value is shown above (
1) is the formula.

In formula (1), the outflow diameter Ws of the falling metal and the inclination angle α of the inner wall of the mixing section are arbitrarily determined.

In equation (1), the collision angle θ of the adhering jet to the inner wall of the mixing section and the distance Yr between the point where the center line of the adhering jet intersects with the mixing section inner wall and the adhering jet line are determined experimentally in advance. Using the parameter tr (0<tr<1), the following equation (2), (
3) It is determined by the formula.

3 Oosθ=-tr-tf・C2) 2 (Page 4) Furthermore, the radius of curvature R of the adhesion jet in equation (1) is expressed as follows (4
) is obtained by the formula.

Here, D: Ws arbitrarily determined to be greater than or equal to the offset amount of the inner wall of the mixing section D and α, and the above (2
) to (4), the above (1)
) is used to find Xr, and the opening position of the addition nozzle is determined within the range of this value.

For the purposes of this invention, Xr can be increased by increasing the offset of the inner wall of the mixing section or by increasing the inclination angle α of the mixing section.

Also, if the lower end of the tongue push nozzle is extended, that amount will be added to Xr. Such changes are appropriately determined depending on the shape of the tongue pusher and other surrounding conditions.

Embodiment FIG. 3 is a diagram showing an embodiment of this invention. In Fig. 3, the outflow diameter Ws of molten steel is 2, and the offset diameter of the mixing section)
Jtt D 2Fsrb, the inclination angle of the inner wall of the mixing section is 0, and the parameter tr is /3, and from the above equations (2), (3), and (4), R = 1981 im, θ = 3
2°, Yr = 5 seagulls, and these values are calculated from (1) above.
Substituting into the formula, we obtained Xr=95 cranes.

Here, the inclination angle of the addition nozzle needs to be about 40 degrees or more, and in order to avoid interference with the tongue push, the tongue push nozzle is extended (1708 (in the figure)), and furthermore, from the lower end of this tandem V unit nozzle, the above The opening (9) of the addition nozzle was provided 20 mm below (in the figure!) within the range of Xr.

Continuous casting of 820C steel was carried out using such equipment, and iron powder with an average particle size of 0.1 m was added from the above-mentioned addition nozzle opening so that the amount added was 1.5 cm of molten steel.
There was no molten steel adhering to the addition nozzle opening. In addition, almost the entire surface of the obtained slab has a fine dendrite structure, and the center of gravity segregation, center, and -porosity are significantly improved; the distance from the meninuccus to the final pseudo-solidification position is shortened by about 401 points, making high-speed casting possible. As a result, productivity has improved.

As described above, this invention analyzes the adhesion distance of the adhesion jet that occurs in the metal flow in the mixing nozzle in continuous casting, and adds powder by providing an addition nozzle opening (9) above this adhesion position. This completely eliminates clogging of the addition nozzle, making it possible to produce high-quality slabs with high efficiency.

Although the continuous casting of molten steel has been described in the description of this invention, it goes without saying that the same effect can be obtained in the continuous casting of non-ferrous metals.

[Brief explanation of drawings]

FIG. 1 is a diagram showing the addition of powder by a mixing nozzle, FIG. 2 is a diagram showing an analytical model of a deposition jet, and FIG. 3 is a diagram showing an embodiment of the present invention. In the figure, 1... tongue push, 2... tongue push nozzle, 3... mixing nozzle, 4... mold, 5...
・ Molten steel flow, 6... Addition nozzle, 7... Powder, 8...
・Inner wall of mixing section, 1,: 9... Addition nozzle tip □ end, opening Applicant: Sumitomo Metal Industries, Ltd. Figure 2 Figure 3

Claims (1)

[Claims] A method of adding powder to molten metal flowing down from a tamp push nozzle into a mixing nozzle using an addition nozzle,
Powder to molten metal characterized in that the distance Xr of the adhering jet is determined by the following formula, an opening of an addition nozzle μ is provided within the range of Xr, and the powder is added toward the molten metal from the addition nozzle. Body addition method. Xr R5in (α10) Yr■-Good”
Oosα -WE revised, xr: Distance of adhesion jet -) Ws: Outflow diameter of falling metal (IB) α: Inclination angle of inner wall of mixing section (0) R = Radius of curvature of adhesion jet (a) θ: Mixed mixture Collision angle of the adhering jet into the part (Yr: distance CHI- between the point where the center line of the adhering jet intersects with the inner wall of the mixing part and the adhering jet line)