JPS62270261A - Immersion nozzle of continuous casting equipment - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

Detailed Description of the Invention 3. Detailed Description of the Invention (Field of Industrial Application) The present invention relates to an immersion nozzle for a continuous casting machine that continuously produces steel pieces such as slabs and blooms directly from molten steel.

(Prior art and its problems) Conventionally, when relatively large pieces of steel such as slabs and blooms are continuously cast, molten steel is injected into a cooling mold using a dip or nozzle as shown in Figure 6. Continuous casting methods are known. More specifically, an immersion nozzle 2 is attached to the bottom of the tampon push l, and molten steel is injected from the immersion nozzle 2 into a mold 3 that is cooled with cooling water. The injected 18w4 is cooled on the wall of the mold 3 and partially solidifies.
The partially solidified slab 5 is continuously pulled out by pinch rolls (not shown) while being held by the guide rolls 4.

The slab 5 pulled out from the mold 3 has an unsolidified liquid phase portion 5a inside thereof, and the spray 6 sprays cooling water onto the slab 5 to cool it and complete solidification.

The above-mentioned casting method is a common method when relatively large pieces of steel such as slabs and blooms are continuously cast. 5b, the molten steel is not oxidized by the atmosphere when it is injected from the tundish 1 into the mold 3, and the formation of inclusions is prevented. It is superior to so-called oven casting, which is poured by dropping it toward the scene.

However, compared to oven casting, the molten steel is injected into the mold 3 relatively quietly through the immersion nozzle 2, so there is less flow in the liquid phase part 5a, and the solidification rate of the liquid phase part 5a is slow, so the slab center There was a problem in that central segregation of C4S and the like was likely to occur in the parts.

In order to solve this problem, a method is known in which, for example, an electromagnetic stirring device is disposed near the cooling mold or on the back of the cooling mold, and the molten steel is stirred using electromagnetic force to promote cooling of the molten steel. However, the electric +1111 stirring device is an extremely expensive device, so an inexpensive alternative device can be used to cool the inside of the cooling mold. A device for stirring 8 steel was requested.

The present invention has been made in view of such demands, and has a simple configuration that widely stirs the molten steel in the cooling mold to promote cooling and melting of the casting powder, thereby reducing center segregation and wrinkles on the surface of the slab. It is an object of the present invention to provide an immersion nozzle for a continuous casting apparatus that prevents the occurrence of such occurrence.

(Means for Solving the Problems) In order to achieve the above-mentioned object, the immersion nozzle of the continuous casting apparatus of the present invention has an upper end opening that communicates with a lower end outlet of the tundish nozzle fixedly installed on the bottom surface of the tundish. In an immersion nozzle of a continuous casting device, in which molten steel is injected into a cooling mold from a discharge port provided in a lower peripheral wall that is immersed below the surface of the molten metal, at least two discharge ports for injecting molten steel into the cooling mold at different heights are arranged in the circumferential direction. The submerged nozzle is formed at regular intervals, and the submerged nozzle is rotatably supported with respect to the tundish nozzle, and is rotated by a drive device.

(Operation) When the immersion nozzle is rotated around the nozzle axis and molten steel is injected into the cooling mold from each discharge port bored in the side wall of the immersion nozzle, the molten steel is injected into the cooling mold while swirling at different heights. be done. This swirling flow of molten steel widely stirs the liquid phase inside the slab, promotes heat dissipation from the liquid phase to the cooling mold wall, accelerates the solidification of the liquid phase, and thereby prevents center segregation. At the same time, it promotes melting of the casting powder, thereby preventing the occurrence of wrinkles on the surface of the slab.

(Example) An example of the present invention will be described in detail below with reference to the drawings.

FIG. 1 is a partial cross-sectional view of the lower part of the tundish and the vicinity of the cooling mold of a continuous casting apparatus to which the immersion nozzle according to the present invention is applied, and numerals 10 and 13 are the kundish and the cooling mold, respectively. An insertable tundish nozzle 12 is located at the center of the bottom surface 10a of the tundish 10, and the lower end 1
2a is attached to the tundish 10 by protruding downward from the bottom surface 10a. A submerged nozzle 14 is rotatably disposed coaxially with and below the tundish nozzle 12. More specifically, the immersion nozzle 14 is formed into a substantially cylindrical shape, and has an upper opening 14a' of a center hole 14a.
The lower end 12a of the tundish nozzle 12 is rotatably fitted into the immersed nozzle 14. On the other hand, the end face 14C of the lower end 14b of the immersed nozzle 14 is closed and Discharge ports 14e and 14f are bored in the circumferential wall near the lower end +4b in the radial direction at equal intervals on the circumference (diametrically at both end positions).
, 14r are infiltrated below the molten metal surface 40a in the cooling mold 13 during continuous casting.

Discharge port 140° 14f at lower end +4b of immersion nozzle 14
At a predetermined position above the immersion nozzle 1 with a slug 45
A corrosion-resistant slag line 15 is fitted on the outside to prevent corrosion of the parts 4 and 4. 2 of the lower end 14b of the immersion nozzle 14
As shown in FIG. 2, the two discharge ports 14e and 14r are formed at positions shifted in the axial direction of the immersion nozzle 14, and each opening end is formed with a step in the axial direction by a distance (height) h. has been done. Each of these discharge ports 148.14f faces in the horizontal direction when the immersion nozzle 14 is installed as shown in FIG.

The upper end 14d of the immersion nozzle 14 is fixed to the inner circumferential wall of a cylindrical body plate 16 with mortar 17, and the body plate 16 is fixed and suspended concentrically with the tundish nozzle 12 on the bottom surface 10a of the tundish 10. Cylindrical mounting member 1
It is rotatably supported on the inner peripheral wall of 8 via bearings 19a and 19b. The lower end surface of the body plate 16 slightly protrudes from the lower end surface of the mounting member I8, and the protruding body plate 1
A ring-shaped sprocket 20 is attached to the lower end surface of the body plate 16 concentrically with the body plate 16. Bottom surface 10 of tundish 10
A reduction gear device 22 is attached to a, and a sprocket 23 is attached to an output shaft 22a of the reduction gear device 22. The sprocket 20 and the sprocket 23 are connected to a roller chain 2 stretched between them.
Connected via 4. The input shaft 22b of the reduction gear device 22 is connected to the output shaft 25a of the electric motor 25 via the power transmission shaft 26, and ball joints 26a and 26b are interposed at both ends of the power transmission shaft 26, and the reduction gear device 22 is connected to the output shaft 25a of the electric motor 25 via the power transmission shaft 26. The input shaft 22b of 22 and the power transmission shaft 16 are spline connected by an insertion joint 22c.

Reference numeral 28 is an inert gas introduction pipe that communicates with the inside of the mounting member 18, and the inside of the mounting member 18 is filled with inert gas, for example, argon gas, through the PAR inlet pipe 28, thereby cooling the bearings 19a919b. At the same time, when pouring molten steel from the tundish 10 into the cooling mold 13, oxygen in the atmosphere flows into the molten steel from the gap between the lower end opening of the tundish nozzle 12 and the upper end 14a'' of the center hole 14a of the submerged nozzle 14. Preventing it from being taken in.

Reference numeral 30 is a heat shield plate, which is injected into the cooling mold 13. Radiant heat is suppressed from being transmitted from the hot water surface 45a of the No. 8 steel to the body plate 16, reduction gear device 22, etc.

With the continuous casting apparatus configured as described above, steel pieces such as blooms are continuously cast in the following manner.

The tundish IO is injected and supplied with molten steel 32 from a ladle (not shown), and the tundish 10 injects this molten steel 32 into the cooling mold 13 via the tundish nozzle 12 and the immersion nozzle 14 in a predetermined casting amount. At this time, electric power is supplied to the electric motor 25 and the electric motor 25 is rotating, and the rotation of the electric motor 25 causes the power transmission shaft 1 to rotate.
6. It is transmitted to the body plate 16 and the submerged nozzle 14 via the reduction gear device 22, sprocket 23, roller chain 24, sprocket) 20, and the submerged nozzle 14 rotates at a predetermined rotation speed (for example, 10 to 80 rp+w). There is. Therefore, each outlet 14e of the immersion nozzle 14.

As shown by arrows A and B in FIG. 2 from 14f, the molten steel spouted and injected into the cooling mold 13 in the horizontal direction is also injected while rotating approximately horizontally, and with this rotation, the cooling mold 13 The molten metal inside is stirred.

Further, since each of the discharge ports +4e and 14f is stepped by a height h, the swirling flow of the molten steel expands in the vertical direction by this step, thereby widening the range of stirring.

As a result, heat radiation from the liquid phase portion 40b to the wall surface of the cooling mold 13 that is cooled by the cooling water is promoted, and the formation of the solidification phase is accelerated. Moreover, the surface inclusions of the slab 40 are reduced due to the centrifugal force effect caused by the rotation of the molten metal.

Incidentally, casting powder 45 is poured into the molten metal surface 40a in the cooling mold 13, and this casting powder 45 floats like a slag to cover the molten metal surface 40a, shielding the molten metal surface 40a from the atmosphere, and is also connected to the cooling mold 13. It is interposed between the slabs 40 to provide lubrication between the two, making it easy to pull out the slabs 40 from the mold 13. However, due to the rotation of the molten metal in the cooling mold 13, the casting powder 4
5 is promoted and a uniform and smooth slag layer is formed between the mold 13 and the slab 40, resulting in a good surface quality free of wrinkles etc. on the surface of the slab.

Slab 40 cooled and solidified on the wall of cooling Sir mold 13
is drawn out by the same known method as explained in FIG. 6, cut into steel pieces of a predetermined length by a cutting machine (not shown), and finished into blooms or the like.

3 and 4 show other embodiments of the submerged nozzle according to the present invention, and the submerged nozzle 14'' shown in FIG.
A step of height h is provided between two discharge ports 14'g and 14"h that are bored in the circumferential wall at both ends of the diameter of °b, and one discharge port 14'g is directed diagonally upward and the other outlet 14'
h is formed to face diagonally downward. As a result, as the immersion nozzle 14 rotates, the discharge port 14'g, 14°h
The molten steel discharged from the molten steel turns diagonally upward and downward as shown by arrows C and D, and the stirring range of the molten metal becomes wider.

Further, the submerged nozzle 14' shown in FIG. 4 has a lower end portion 14'b.
There are discharge ports 14'6.14' f, 14' g, and 14' h in the circumferential wall at both ends of two diameters perpendicular to each other.
(Fig. 5) and facing discharge ports 14°e and 14
'f is formed with a step of height h in the horizontal direction as in FIG. 2, and the opposing discharge ports 14'g and 14'h are formed with a step of height h as in FIG. One discharge port 14''g is formed diagonally upward, and the other discharge port 14'h is formed diagonally downward.

As a result, as the immersion nozzle 14 rotates, the discharge port L4
The molten steel discharged from ``e, 14'f is horizontally shown by arrows A and B (Figs. 2 and 5), and is discharged from 14'g, 14'f.
The molten steel discharged from 'h is arrow C1D (Fig. 3, Fig. 5)
It turns diagonally upward and downward as shown by , and as a result,
The stirring range of molten steel becomes wider.

In the embodiment shown in Figs.
Although the description has been made for the case where one is provided, the present invention is not limited to this, and four may be provided as shown in FIGS. 4 and 5.

In addition, two discharge ports 14'g shown in FIGS. 3 and 4
+ 14' h h may be provided at the same height position.

(Effects of the Invention) As described in detail above, according to the present invention, the upper end opening communicates with the lower end discharge port of the tundish nozzle fixedly installed on the bottom surface of the tamp pusher, and the lower end circumferential wall is immersed below the molten metal surface. In a submerged nozzle of a continuous casting apparatus that injects molten steel into a cooling mold from a discharge port provided therein, at least two discharge ports for injecting molten steel into the cooling mold at different heights are formed at equal intervals in the circumferential direction, and The soaking nozzle is rotatably supported relative to the Densch nozzle, and the driving device rotates the soaking nozzle while injecting molten steel into the cooling mold from the discharge port. The molten steel injected into the molten steel can be stirred, the cooling and solidification of the molten steel center is promoted, and as a result, the center segregation of the slab can be suppressed, the surface layer of the slab can be reduced, and wrinkles can be prevented. It has various excellent effects such as obtaining slabs with good surface quality free of surface defects.

[Brief explanation of the drawing]

FIG. 1 shows an embodiment of a continuous casting apparatus to which the immersion nozzle according to the present invention is applied, and FIG. 2 is a partial cross-sectional configuration diagram of the lower part of the continuous casting apparatus and the vicinity of the cooling mold. 3 and 4 are enlarged sectional views of the lower end showing other embodiments of the immersion nozzle according to the present invention, and FIG. 5 is an arrow line V-V in FIG. Sectional view, No. 6
The figure is a partial cross-sectional configuration diagram of the lower part of the kundefush and the vicinity of the cooling mold of a continuous casting apparatus using a conventional immersion nozzle. 10...Tunpush, 12...Tundish nozzle, 13...Cooling mold, 14.14'...Immersion nozzle, 16...IF4N, 20, 23...Sprokeft, 22... Reduction gear device, 24... roller chain, 25... electric motor.

Claims (3)

[Claims] (1) Continuous casting equipment in which the upper end opening communicates with the lower end outlet of the tundish nozzle fixedly installed on the bottom of the tundish, and the molten steel is injected into the cooling mold from the outlet provided in the lower end circumferential wall, which is immersed below the molten metal surface. In the immersion nozzle, at least two discharge ports for injecting molten steel into the cooling mold at different heights are formed at equal intervals in the circumferential direction, and the immersion nozzle is rotatably supported and driven with respect to the tundish nozzle. An immersion nozzle for a continuous casting device, which is rotated by the device. (2) The immersion nozzle for a continuous casting apparatus according to claim 1, wherein the at least two discharge ports are formed at different height positions. (3) The immersion nozzle for a continuous casting apparatus according to claim 1, wherein the at least two discharge ports are formed to face different directions with respect to the axial direction of the immersion nozzle.