JP2836425B2 - Horizontal continuous casting equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a horizontal continuous casting facility for steel or the like.

[0002]

2. Description of the Related Art As this kind of horizontal continuous casting equipment, an equipment as shown in FIG. 9 is generally used. FIG. 9 is a diagram showing an example of a horizontal continuous casting facility for steel.

[0003] tundish 1 is provided with a so-called front nozzle 2 to the lower sidewall, (hereinafter referred to as mold) template and 5, the feed middle third and break ring 4
Are connected via The mold 5 includes both a body made of copper, a copper alloy or the like, and a jacket for cooling the mold body with water.

[0004] The molten steel 7, which is injected into the tundish 1,
Off Rontonozuru 2 from the feed middle third, and flows into the mold 5 through a break ring 4, it is rapidly cooled in the mold within 5, the solidified shell is formed, is pulled out in the direction of the arrow as the billet 6 from the mold 5. In the above facilities,
The longitudinal axis C of the front nozzle 2 and the mold 5 is the same axis.

The break ring 4 includes a feed tube 3.
At the same time, connect the tundish 1 and the mold 5,
It is used to prevent the molten steel from leaking and to keep the solidification start point of the molten steel in the mold 5 constant, and is made of a refractory material such as ceramics. Here, the slab 6 and the mold 5
Seizure preventing the inner peripheral surface of, and in order, such as to repair it even solidified shell torn off, the billet 6 is withdrawn in 歇 manner between the drawing direction of the arrow.

The slab 6 is generally "pull-stop-return".
Slab between 歇 withdrawal cycle is cast repeated several 10 times to about 100 times per minute.

[0007] In the horizontal continuous casting of this kind, the molten steel temperature toward the lower surface side of the feed middle third from the lower side of the bottom surface and the front nozzle 2 of the tundish 1 is compared with the upper surface of the molten steel temperature to pass at the same time Te, affected by the tundish bottom refractory, is known to be low.

[0008] In such cases, as shown in FIG. 8, the solidified shell 10 to produce the lower surface side of the mold 5, the seam 12 of the new shell 10a and the old shell 10b, solidification structure becomes discontinuous, cracks in the surface of the welding defects more slab. The arrow indicates the direction in which the slab is drawn. The surface crack generated at the seam 12 of the solidified shell 10 is called a cold shut crack, and such a discontinuous solidified structure is called a cold shut.

[0009] Also, the break ring 4 and when the flowing temperature low molten steel, such as above the lower surface side of the inner surface of the mold 5, the hot spot 9 of the slab lower side, the slab withdrawal side of the new shell 10a and solidified shell 10c are welded
Since hard, break ring 4 side solidified shell 10c
There is bound to the inner surface of the break ring 4 itself and the mold 5, the solidified shell 10 left preparative break ring 4 side
yields c. This phenomenon is called misple. Cracks called misple cracks remain on the surface of the cast slab where the misples have occurred.

[0010] These defects it photon Donaku disappear in the next step such as rolling, for which it is necessary work to scrape these defects formed on the surface of the slab 6. As a result, the yield of the slab 6 deteriorates, and the manufacturing cost increases. Thus, generation of Misupuru such as described above, the horizontal continuous casting, since a very large problem that countermeasures have been studied.

[0011] As an example of a countermeasure, JP-B-61-4458
The 8 discloses, as shown in FIG. 7, the molten metal to the mode Rudo 5
The wall and the facing walls of the inlet side, downward flow preventing portion 13 upward
The provided, a downflow preventing board 14 comprised of the furnace bottom theta = 30 to 70 ° inclined so inclined furnace wall provided Rutotomoni, the lower the level of the molten metal downward flow preventing portion 13, the above the molten metal inlet A tan provided with a protrusion 15 for preventing molten metal reversal at a position
Dish 1 is disclosed . As a result, the molten metal 16 can flow into the mold 5 in a laminar flow, and the temperature of the molten metal flows as uniformly and quietly as possible to prevent the occurrence of mispull.

[0012]

THE INVENTION Problems to be Solved] above-mentioned JP-B-61-
In horizontal continuous casting equipment shown in 44588 JP, billets of small cross-sectional size (e.g., thickness 50 mm × width 300m
While improving effect by casting m) it has been described that there has been limited to improvements in the tundish body, coupling structure through the front nozzle and tundish and the mold, feed paralytic, a break ring,及 No mention is made of the effect of this structure on the occurrence of misples. The experimental results by the present inventors had use a conventional horizontal continuous casting equipment as shown in Figure 9 is shown in FIG. In the above facility, the longitudinal axes of the front nozzle 2 and the mold 5 are the same.

[0013] Figure 5 is the tundish molten steel temperature on the frequency of occurrence of contact only that Misupuru to 170mmφ cast (molten steel superheat: [Delta] T) is a diagram showing the relationship, the frequency of occurrence as Misupuru the molten steel temperature drops Is high, and in 170 mmφ casting, ΔT is prevented at 20 ° C. or more. This molten steel temperature becomes the composed refractory steel inner wall of the nozzle between the tundish-mold tends to be constrained by a thin solidified shell is led toward a break ring inner wall lower believed Misupuru is likely to occur.

On the other hand, as shown in FIG. 6 , in the casting of a billet having a large sectional size such as 300 mmφ, the frequency of occurrence of misple tends to be relatively high. That is, FIG. 6 shows the frequency of mispull occurrence by size and location of continuous casting by the horizontal continuous casting equipment. As is apparent from the figure, mispulling occurs in a billet casting having a small cross-sectional size of 170 mm to 230 mm. Although the incidence is very small, very is Misupuru frequency in bi <br/> let casting of large cross-sectional size of 300mmφ~370mmφ many, and, when the billet casting large cross-sectional size, site of occurrence of Misupuru most It is characterized in that it concentrates on the lower surface side of the slab.

The present invention has been made to solve the problem of the occurrence of misples based on the knowledge of the above experimental results.
It is an object of the present invention to provide a horizontal continuous casting facility capable of significantly reducing the frequency of occurrence of misples even in billet casting with a large cross-sectional size and capable of performing stable casting.

[0016]

[MEANS FOR SOLVING THE PROBLEMS] To achieve the above object
The horizontal continuous casting installation according to the invention, the tundish and the mold and the front nozzle, a feed paralytic, in a horizontal continuous casting equipment which is connected via a break ring, the longitudinal axis of the front nozzle bore, wherein the <br/> bore longitudinal axis of the mold, the with axis of the mold in the hole is positioned higher than the axis of the front nozzle bore, the front nozzle bore tundish side containing
Opposite the mouth, place the immersed dam on the bottom of the tundish lining
It is characterized in that provided in the.

[0017]

[Action] According to the experimental results of the inventor, the large cross-sectional size
Mold flange thermometer for monitoring casting during billet casting
In the temperature measurement result, the temperature difference between the upper and lower sides is about 27 ° C.
The measured value of the mold flange thermometer on the bottom side is always
Low. Furthermore, casting at 170 mmφ and 330 mmφ
The surface solidification structure was investigated.
Is columnar from the slab surface on both the upper and lower sides
Crystals are growing, but on the underside of the slab of 330 mmφ
Is probably near the surface layer where the cooling rate should be quite fast
Amount of equiaxed crystals are generated and these are considered
When casting large section billets, molten steel in the mold
The temperature is uneven in the vertical direction, and the lower surface side has a considerably low temperature.
It is thought that molten steel was flowing.

According to these observations, a large cross-sectional size
In the cast casting, the inside diameter of the front nozzle and feed tube
Since it is large, the refractory material between the tundish and the mold
The speed of molten steel in the chisel is low,
The molten steel cooled by the refractory at the bottom
Mold without being uniformly mixed with high temperature molten steel
The possibility of flowing into the bottom side
Does the feed tube shape change from the inlet section to the outlet section?
Because the diameter suddenly increased, the molten steel
When passing through, the flow velocity suddenly drops, causing stagnation
With the possibility that low-temperature parts may occur, especially in the lower molten steel.
Two possibilities were considered as causes of equiaxed crystal formation.

FIG . 2 is an explanatory view showing a main part of the present invention.
The horizontal continuous casting equipment of the present invention comprises a tundish 1 and a mold.
5 is a front nozzle 22, a feed tube 23,
Horizontal continuous casting connected via rake ring 24
In the equipment, the longitudinal length of the inner hole 22a of the front nozzle 22
Axis A in the direction, and axis B in the longitudinal direction of the inner hole 5a of the mold 5
And the axis B is positioned higher than the axis A.
You. The functions and effects brought by the above features are as follows.

(1) Position the shaft center B higher than the shaft center A
Therefore, the mold 5 is inserted through the front nozzle inner hole 22a.
As shown by the arrow, the molten steel flowing into
As it flows along the surface 5b, the molten steel temperature
It can be kept high.

(2) Position the shaft center B higher than the shaft center A
Therefore, the feed tube 23 is
At the center of the cross-section of the inlet and the center of the cross-section of the outlet
The center of the section is necessarily lower,
Exit of inner wall of feed tube 23 connecting exit section
The taper angle in the direction is higher on the upper side than on the lower side.
It is steeper. For example, as shown in FIG.
Close to the horizontal, and make the top side a steep angle.
The effect can be maintained. Inlet section and outlet
Each area of the cross-section is caused by
Refer to the casting results according to the casting conditions to the extent that
Can be selected appropriately.

(3) In addition to the above (1) and (2),
In the tundish 1 side of the front nozzle inner hole 22a,
A sunk weir facing the entrance, lined with tundish
By installing it on the bottom surface, the bottom
To prevent the flow of the retained low-temperature molten steel into the mold 5.
Can be.

[0023]

【Example】 An embodiment of the present invention will be described with reference to the drawings. Figure
FIG. 1 shows an embodiment of a horizontal continuous casting facility for steel of the present invention.
It is. The horizontal continuous casting equipment of the present invention is a tundish
1 and mold 5 are front nozzle 22, feed tube
23, and are connected via a break ring 24. This
Here, the longitudinal axis of the inner hole 22a of the front nozzle 22
The core A and the axial core B in the longitudinal direction of the inner hole 5a of the mold 5 are cast.
The axis B of the inner hole 5 a of the mold 5 is the inner hole 2 of the front nozzle 22.
2a and higher than the axis A
Tundish 1 side entrance 2 of inner hole 22a of nozzle 22
2c, immersed submerged weir 25 in tundish
It is provided on the bottom surface.

The horizontal continuous casting apparatus of the present invention as shown in FIG.
Details on horizontal continuous casting of steel
I do. Table 1 shows the casting conditions for horizontal continuous casting used in the present invention.
Here are the main specifications.

[0025]

[Table 1]

FIG . 3 is a flowchart showing one of the components of the present invention.
The longitudinal axis of the nozzle bore and the length of the mold bore
Axis of the mold and the axis of the mold bore are the front nozzle bore
330mmφ carbon when positioned higher than the axis of
FIG. 3 is a diagram showing the effect of preventing the occurrence of misple of steel billets.
As is evident from the figure, the
The sprue occurrence index is improved to about 1/5 or less. Only
However, it is not possible to completely prevent the occurrence of mispull.

FIG . 4 is a view showing a state in which the
Change the height of the pickled weir and adjust the tandy
Level difference between the lower end position of the ash side and the upper end position of the weir in the height direction
Is a diagram showing the effect of
In the figure, the symbol “△” indicates that no mispull occurred in the embodiment of the present invention.
And ● marks can completely prevent the occurrence of mispull in the examples.
This is the case where there was no such information.

As is apparent from FIG .
The lower end position of the front nozzle bore and the weir
The difference in the height direction from the upper end position must be 140 mm or more.
Is preferred. However, the value of weir height as described above is
Condition, steel type, slab cross-sectional shape, for example, round, square, etc.
So you have to decide empirically.

[0029]

【The invention's effect】 As described above, in the present invention,
Improved the refractory arrangement between the shell and the mold to improve the flow of molten steel
Can be improved, large section size billet casting
Can greatly reduce the frequency of occurrence of defects such as mispulls
Therefore, stable casting can be performed. These defects are the next
It hardly disappears in the process, so
It is necessary to remove these defects formed on the surface.
However, according to the present invention, the occurrence of mispull is prevented.
The cutting work is omitted, the yield of slab is high,
The manufacturing cost can be reduced.

[Brief description of the drawings]

FIG. 1 is a view showing one embodiment of a horizontal continuous casting facility according to the present invention.

FIG. 2 is a view showing a main part of a horizontal continuous casting facility according to the present invention .
FIG.

FIG. 3 is a front nozzle which is one of the components of the present invention .
The longitudinal axis of the bore and the longitudinal axis of the mold bore
And the axis of the mold inner hole is larger than the axis of the front nozzle inner hole.
Steel billet of 330mmφ when it is positioned too high
FIG. 4 is a diagram showing the effect of preventing the occurrence of a misple.

FIG. 4 is a view showing a case where a weir height is changed in the embodiment of the present invention .
Figure showing the effect of preventing the occurrence of misple of carbon steel billet
is there.

[Fig. 5] For 170mmφ casting of conventional horizontal continuous casting equipment
Of Tundish Dissolution on the Frequency of Misple Occurrence
It is a figure which shows the relationship of steel temperature (superheat degree of molten steel: (DELTA) T).

FIG. 6 shows the size of continuous casting in a conventional horizontal continuous casting facility.
It is a figure which shows the mis-pull occurrence frequency according to another and a site | part.

FIG. 7 is a conventional horizontal continuous casting facility for preventing mispull .
It is a figure showing an example of.

FIG. 8 shows a case where a misple has occurred in a conventional horizontal continuous casting facility and
Concept near the mold when a cold shut crack occurs
FIG.

FIG. 9 is a diagram showing an example of a conventional horizontal continuous casting facility.
You.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Tundish 5 Mold (mold) 5a Mold inner hole 5b Mold inner wall (lower surface part) 22 Front nozzle 22a Front nozzle inner hole 23 Feed tube 24 Break ring 25 Submerged weir A Longitudinal direction of front nozzle inner hole Axis of B B Axis of longitudinal direction of inner hole of mold

──────────────────────────────────────────────────続 き Continuation of the front page (72) Inventor Kazuki Ibuki, 1-2-1, Marunouchi, Chiyoda-ku, Tokyo Nippon Kokan Co., Ltd. Examiner Taro Moriyasu (56) References JP-A-4-339559 (JP, A JP-A-56-111552 (JP, A) JP-A-54-95928 (JP, A) JP-A-4-172150 (JP, A) JP-B-39-23710 (JP, B1) (58) Field (Int.Cl. ⁶ , DB name) B22D 11/04

Claims (1)

(57) [Claims] 1. A tundish and the mold and the front nozzle, a feed paralytic, in a horizontal continuous casting equipment which is connected via a break ring, wherein the longitudinal axis of the front nozzle bore, the inner bore of said mold of the longitudinal axis, with the axis of the mold in the hole is positioned higher than the axis of the front nozzle bore, opposite the tundish side entrance of the front nozzle bore, and submerged
Horizontal continuous casting equipment characterized in that a weir is provided on the bottom of the tundish lining .