JPH03294051A - Pouring nozzle for twin drum type continuous casting apparatus - Google Patents

Abstract

PURPOSE:To prevent remelting of solidified part caused by poured molten metal flow in pouring basin by, for instance, communicating a pouring chamber in an outer nozzle and a molten metal flow buffering chamber through refractoriness partition plate having plural pieces of through holes. CONSTITUTION:In twin drum type continuous casting apparatus, molten metal caused to flow out from an inner nozzle 12 is caused to flow into the pouring chamber 16 in the outer nozzle 13 and further into the molten metal flow buffering chamber 19 through the through holes to thickness direction of the refractoriness partition plate 17. The molten flow is supplied into the pouring basin 52 from discharging holes 18 at both sides of cooling drums 50. Solidified shells grown on the drum surfaces S in both cooling drums 50 are progressed downward accompanied with rotation of the cooling drums 50 and integrated at kissing point K to complete the solidification of the whole thickness of a cast strip 53. Under condition of reliving flowing energy with three steps of buffering action through the partition plate 17 and the buffering chamber 19, and only to axial direction of the cooling drums 50, the molten metal supply into the pouring basin 52 can be executed. By this method, the remelting of the solidified shell and the remelting of solidified completing part can be prevented at the same time.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a pouring nozzle for a twin-drum continuous casting machine.

[Conventional technology]

A twin-drum type (also called a "double-roll type J") continuous casting machine consists of a pair of cooling drums arranged parallel to each other with their drum surfaces facing each other, and a pair of side weirs pressed against both end surfaces of these cooling drums. Inside the bottomless mold formed by
This is a continuous casting machine that injects molten metal to form a pool, and casts thin slabs with a thickness close to the product thickness in order to manufacture cold rolled sheets from continuously cast slabs without hot rolling. It is particularly suitable as a continuous casting method.

When supplying molten metal to the pool between the cooling drums in twin-drum continuous casting, if the powerful flow of molten metal discharged from the pouring nozzle immersed in the pool hits the drum surface of the cooling drum directly, it will cause a drop on the drum surface. The formed solidified shell remelts, causing uneven solidification, which causes slab cracking and breakouts. In addition, if the molten metal is discharged downward without directly facing the drum surface, the solidified shells that have grown on both drum surfaces meet and the entire thickness of the slab is solidified at the closest point to the cooling drum (so-called Direct contact of the hot molten metal stream (kissing points) causes local incomplete solidification or non-uniform solidification, which also causes slab cracking and breakouts.

As a countermeasure to these problems, it has been proposed to reduce the flow force of the discharged molten metal by covering the discharge port that discharges the molten metal downward or toward the surface of the cooling drum with a filter such as a porous refractory (for example, (Sho 63-207454, Japanese Patent Application Laid-Open No. Sho 64-11055) FIGS. 4(a) and (b) show an example of the conventional wide nozzle described above. FIG. 4(a) shows the pouring nozzle 41 connected to a pair of cooling drums 50. FIG. 4(b) is a view of the cooling drum 50 placed at a casting position between the two sides, as seen from the end surface direction, and FIG. 4(b) shows a cross section taken along the line A-A of FIG. The nozzle 41 consists of an inner nozzle 42 having a molten metal flow port 44 at the upper part and a molten metal outlet 45 at the lower part, and an outer nozzle 43 that accommodates the inner nozzle 42.The tip of the outer nozzle 43 is connected to the cooling drum as shown in FIG. A porous refractory filter 47 is inserted in the middle of this wide portion of the molten metal flow path, that is, in front of the molten metal discharge port 48. Inner nozzle 42
The molten metal flowing out from the molten metal outlet 45 enters the space 46 between the outer nozzle 43 and the inner nozzle 42, passes through the through hole of the refractory filter 47, and flows downward below the molten metal level M into the molten metal pool 52. Supplied. Water reservoir 52 between cooling drums 50
are the side weirs 5 pressed against both end surfaces of the cooling drum 50.
As the cooling drums 50 rotate (arrow R in the figure), the solidified shells that have grown on the drum surfaces S of both cooling drums 50, which are sealed by the cooling drums 50 and 50, move downward, resulting in kissing.
The solidification of the entire thickness of the slab 53 is completed by coalescence at the point.

However, in the conventional method described above, although the flow force of the molten metal is weakened by the refractory filter 47, basically all of the newly supplied high-temperature discharged molten metal flows downward or toward the drum surface. The issue has not been completely resolved, and there are limits to its effectiveness.

In addition, in order to cast wide slabs that can be used to manufacture wide cold-rolled sheets, it is necessary to use a large and wide pouring nozzle that has a long molten metal discharge port 48 in the axial direction of the cooling drum. 48 requires a large and expensive refractory filter 47, which poses a problem of increasing the cost of the pouring nozzle.

[Problem to be solved by the invention]

SUMMARY OF THE INVENTION An object of the present invention is to provide a pouring nozzle for a twin-drum continuous casting apparatus that can prevent the solidified portion from being remelted by the pouring flow within the tundish without requiring an increase in size.

[Means to solve the problem]

According to the present invention, metal is placed in a bottomless mold formed by a pair of cooling drums arranged in parallel with their drum surfaces facing each other, and a pair of side weirs pressed against both end surfaces of these cooling drums. A pouring nozzle for a twin-drum continuous casting device that injects molten metal to form a pool, comprising: an inner nozzle having a molten metal inlet at the top and a molten metal outlet at the bottom; and at least a portion of the molten metal outlet of the inner nozzle. and an outer nozzle having a pouring chamber at its lower end that receives the molten metal from the molten metal outlet of the inner nozzle, and a molten metal flow having a discharge port disposed below the outer nozzle and discharging the molten metal in the axial direction of the cooling drum. a buffer chamber, the pouring chamber of the outer nozzle and the molten metal flow buffer chamber communicate with each other via a fireproof partition plate provided with a number of through holes in the thickness direction, and the discharge of the molten metal flow buffer chamber This is achieved by a pouring nozzle for a twin-drum continuous casting machine whose outlet is covered with a fire-resistant partition plate having a large number of through holes in the thickness direction.

When casting a very wide slab, in the pouring nozzle of the present invention, in the pouring nozzle according to claim 1, the molten metal flow auxiliary buffer chamber communicates with the molten metal flow buffer chamber and the discharge port. There is a main discharge port covered with a fire-resistant partition plate with many through holes in the thickness direction, which discharges most of the molten metal supply in the axial direction of the cooling drum, and at least one of the lower part and the cooling drum surface. A molten metal flow auxiliary buffer chamber having an auxiliary outlet for discharging the remaining portion of the molten metal supply toward the molten metal can be provided.

[Effect]

In the pouring nozzle of the present invention, the molten metal introduced into the inner nozzle from the molten metal inlet of the inner nozzle enters the molten metal pouring chamber of the outer nozzle from the molten metal outlet of the inner nozzle, and from the molten metal pouring chamber, the refractory partition plate It enters the melt flow buffer chamber through a through hole in the melt flow buffer chamber, and is then discharged from the melt flow buffer chamber through a through hole in another refractory partition plate. In the above process, the flow of molten metal is first relaxed by the partition plate as it flows from the pouring chamber to the buffer chamber, then the flow force is relaxed by passing through the buffer chamber, and finally the flow force is relaxed from the buffer chamber. When being discharged, the flow force is relaxed again by the partition plate. After the molten metal flow is thus subjected to three stages of flow relaxation effects, it is finally discharged into the molten metal pool in the axial direction of the cooling drum, that is, toward the side weir.

The discharged molten metal flow hits the side weir in the pool and then smoothly advances along the cooling drum surface from both sides, so the molten metal flow remains strong and reaches the cooling drum surface and the kissing point below. There is no direct contact.

Furthermore, since the molten metal is supplied to the trough from both sides, wide slabs can be cast without enlarging the discharge port itself to the trough.

In one aspect of the present invention, after performing the above-mentioned three stages of relaxation, the majority of the supplied molten metal is further passed through an auxiliary buffer chamber to provide a relaxation effect and a partition when discharged from the auxiliary buffer chamber. In addition to the relaxation effect of the plate, a total of 5 stages of relaxation effect are performed and the cooling drum is supplied in the axial direction.
For the remaining relatively small amount of molten metal, a relaxation effect by passing through the auxiliary buffer chamber is added to the above three stages, and a total of four stages of relaxation action can be performed and the molten metal can be supplied downward and/or toward the cooling drum surface. Even when casting very wide slabs, a sufficient amount of molten metal can be supplied without adversely affecting solidification on the cooling drum surface and at the kissing point. In this case as well, the auxiliary buffer chamber may be connected to the discharge port of the buffer chamber, so there is no need to enlarge the discharge port itself into the pool.

In the following, the invention will be explained in more detail by means of examples with reference to the accompanying drawings.

[Example 1] FIGS. 1(a) to 1(d) show an example of a pouring nozzle according to the present invention. FIG. The cooling drum 50 shows the arranged state.
A view seen from the end surface direction, the same figure (b) is the line B of the same figure (a)
-A cross-sectional view along the line B, the same figure (c) is the arrow C in the same figure (a)
The figure seen from the direction of , and the same figure (d) are the same figure (a), (
Lines D-D and D'-D' in b) and (c), respectively.
, D''-D'' is a diagram showing the cross section of the pouring nozzle 11 corresponding to the lower cooling drum 50, the side weir 51, the contour line m of the scene M on the surface S of the cooling drum 50, and the kissing point. .

The pouring nozzle 11 includes an inner nozzle 12 having a molten metal flow port 14 at the upper part and a molten metal outlet 15 at the lower part, the inner nozzle 12 is held by the flange at the upper end, and the part below the flange of the inner nozzle 12 is accommodated. Outer nozzle 13 and outer nozzle 1
3, and has a molten metal flow buffer chamber 19 having a discharge port 18 for discharging the molten metal in the axial direction of the cooling drum 50. The space between the inner nozzle 12 and the outer nozzle 13 functions as a pouring chamber 16 that receives the molten metal from the molten metal outlet 15 of the inner nozzle 12 . The pouring chamber 16 of the outer nozzle 13 and the molten metal buffer chamber 19 communicate with each other via a fireproof partition plate F provided with a large number of through holes in the thickness direction.

The discharge port 18 of the molten metal buffer chamber 19 is covered with a fire-resistant partition plate provided with a large number of through holes in the thickness direction.

The fireproof partition plates 17 and 18 are assembled by arranging firebricks or the like so as to have many slits in the thickness direction, firebricks with many unidirectional straight holes in the thickness direction, or porous. Manufactured from porous bricks, etc. Since porous bricks are expensive, it is economical to use slit-formed or one-way straight hole bricks. Figures 3(a) and 3(b) show an example of a refractory brick with a large number of unidirectional straight holes in the thickness direction.
The one-way straight hole brick 31 shown in the same figure shows a cross section along
A large number of through holes 32 are made in the thickness direction of the kneaded and shaped brick material in an unfired state using a tool shaped like a tsurugisan.
It can be easily produced by firing in that state, so it is very inexpensive.

The pouring nozzle 11 shown in FIG. 1 discharges the molten metal only in the axial direction of the cooling drum 50 from the discharge hole 18 of the molten metal flow buffer chamber 19. The process from supplying the molten metal to the pouring nozzle 11 to forming the slab 53 is as follows.

At the start of casting, the pouring nozzle 11 is arranged in advance so that the molten metal flow buffer chamber 19 is located directly below the desired area M of the pool 52. At this time, if the refractory partition plate 17 is located above the molten metal level M, air bubbles may accumulate in the molten metal flow buffer chamber 19.
The molten metal transported from the melting/refining furnace or the like to the twin-drum continuous casting device by a ladle or the like is placed on the pouring nozzle 11 (not shown), which is preferably disposed at a slightly lower position. The molten metal is supplied to the molten metal inlet 14 of the inner nozzle 12 by the tundish. The molten metal flowing out from the molten metal outlet 15 of the inner nozzle 12 enters the pouring chamber 16 of the outer nozzle 13, passes through the through hole in the thickness direction of the refractory partition plate 17 (for example, 32 in FIG. 3), and is buffered for molten metal flow. Enter room 19. The molten metal flow becomes two flows in the axial direction of the cooling drum 50 within the buffer chamber 19 and is supplied to the molten metal reservoir 52 from the discharge holes 18 on both sides. The pool 52 between the cooling drums 50 is sealed by side weirs 51 pressed against both end surfaces of the cooling drum 50. The solidified shells that have grown on the drum surfaces S of both cooling drums 50 advance downward as the cooling drums 50 rotate (arrow R in the figure), coalesce at the kissing point, and form the entire thickness of the slab 53. Coagulation is complete.

By using the pouring nozzle 11 of this embodiment, the flow force is extremely relaxed due to the three-stage buffering action of the partition plates 17 and 18 and the buffer chamber 19, and the cooling drum 50
Molten metal can be supplied to the pool 52 only in the axial direction. This makes it possible to simultaneously prevent the remelting of the solidified shell formed on the drum surface S of the cooling drum 50 and the remelting of the solidified portion at the kissing point.

Since the pouring nozzle 11 of this embodiment supplies the molten metal in the axial direction of the cooling drum 50, a wide slab can be cast without enlarging the communication portion 19 or the discharge port 18. therefore,
Since there is no need to use a large and expensive refractory plate as the refractory partition plate of the communication portion 19 and the discharge port 18, the cost of the pouring nozzle can be suppressed to a minimum.

[Example 2] Figures 2(a) to 2(e) show an example of the pouring nozzle of the present invention suitable for casting very wide slabs.

Figure (a) is a view of the pouring nozzle 201 placed at the casting position between the cooling drums 50 when viewed from the end surface direction of the cooling drum 50, and figure (b) is the line E-- in Figure (a). A cross-sectional view taken along line H, the same figure CC> is a view seen from the direction of the arrow F in the same figure (a), and the same figure (d) shows the same figure (a), (b), and (C
), the cross section of the pouring nozzle 201 corresponding to the lines G-G, G"-G"Qllc12" is shown below on the cooling drum 5
0, the side weir 51, the contour line m of the hot water level M on the cooling drum 50 surface S, and the kissing point, and the figure Ce) is the same as the line H in the figure (c) or (d).
-H or a cross-sectional view along line H'-H'.

The pouring nozzle 201 includes an inner nozzle 202 having a molten metal flow port 204 at the upper part and a molten metal outlet 205 at the lower part, and an inner nozzle 202 that holds the inner nozzle 202 by a flange section at the upper end.
An outer nozzle 203 that accommodates a portion below the flange portion of No. 2
The cooling drum 50 is arranged below the outer nozzle 203.
A molten metal flow buffer chamber 209 having a discharge port 208 for discharging molten metal in the axial direction of A melt flow auxiliary buffer chamber 211 having auxiliary discharge ports 212 and 213 is provided. The main discharge port 210 of the auxiliary buffer chamber 211 discharges most of the molten metal supply in the axial direction of the cooling drum 50, and the auxiliary discharge ports 212 and 213 of the auxiliary buffer chamber 211 discharge the remainder of the molten metal supply to the cooling drum 50, respectively. Discharge toward a surface or downwards.

The space between the inner nozzle 202 and the outer nozzle 203 functions as a pouring chamber 206 that receives the molten metal from the molten metal outlet 205 of the inner nozzle 202 . The pouring chamber 206 and the molten metal buffer chamber 209 communicate with each other via a fireproof partition plate 207 provided with a large number of through holes in the thickness direction. The buffer chamber 209 and the auxiliary buffer chamber 211 communicate with each other via a fire-resistant partition plate that covers the discharge port 208 of the buffer chamber 209 and has a large number of through holes in the thickness direction. The main discharge port 210 of the auxiliary buffer chamber 211 is covered with a fire-resistant partition plate provided with a large number of through holes in the thickness direction. Fireproof partition plates 207, 208 and auxiliary discharge ports 212, 21
3 is a through hole 3 in the thickness direction as shown in FIGS. 3(a) and 3(b).
It can be formed using a fire-resistant partition plate 31 provided with a large number of partition plates 2, or it can also be formed in a slit shape as shown in FIGS. 2(b) and 2(C).

The fireproof partition plates 207, 20B and 210 can be produced in the same manner as in Example 1.

The pouring nozzle 201 shown in FIG.
and 213, the remaining portion of the molten metal supply is discharged toward the surface of the cooling drum 50 or downward.

The process from supplying the molten metal to the pouring nozzle 201 to forming the slab 53 is the same as the process up to the molten metal flow buffer chamber 19 in Example 1 with respect to the process up to the molten metal flow buffer chamber 209, and thereafter. is as follows.

The two molten metal flows in the axial direction of the cooling drum 50 within the buffer chamber 209 pass from the discharge holes 208 on both sides through the through holes in the thickness direction of the fireproof partition plate, and flow into the adjacent auxiliary buffer chamber 211.
Most of the water flows in the axial direction of the cooling drum 50 as it is, passes through the through hole in the thickness direction of the fireproof partition plate of the main discharge port 210, and is supplied to the sump 52 in the axial direction of the cooling drum 50. be done. The remaining portion of the molten metal is supplied to the sump 52 through the lower and side auxiliary discharge ports 212 and 213, downward or toward the surface of the cooling drum 50.

The pool 52 between the cooling drums 50 is sealed by side weirs 51 pressed against both end surfaces of the cooling drum 50. The solidified shells grown on the drum surfaces S of both cooling drums 50 advance downward as the cooling drums rotate 500 times (arrow D in the figure), coalesce at the kissing point, and solidify the entire thickness of the slab 53. is completed.

By using the pouring nozzle 201 of this embodiment, the partition plates 207 and 208, the buffer chamber 209, and the auxiliary buffer chamber 21
After performing the four-stage buffering action according to No. 1, the buffering action of the partition plate 210 is further added for most of the molten metal supply amount, and a total of five stages of buffering action are performed, and in the axial direction of the cooling drum 50, The remainder of the molten metal supply is handled by the cooling drum 50 below and the cooling drum 5
Molten metal can be supplied to the pool 52 toward the surface. The discharge flow from the auxiliary discharge ports 212 and 213 is 4
The discharge flow rate can be considerably lower than the discharge flow rate from the main discharge port 210. As a result, extremely wide slabs can be cast while simultaneously preventing the remelting of the solidified shell formed on the drum surface S of the cooling drum 50 and the remelting of the solidified portion at the kissing point. Can be done.

Since the pouring nozzle 201 of this embodiment discharges most of the molten metal supply in the axial direction of the cooling drum 50, the communication portion 207
．． Very wide slabs can be cast without enlarging either the discharge port 208 or the discharge port 210. In addition, the auxiliary discharge port 212.21
3 may be a simple opening, and there is no need to use a refractory partition plate.Therefore, there is no need to use large and expensive refractory plates as partition plates for the communication portions 207 and 208 and the discharge port 210, so pouring Nozzle costs can be kept to a minimum.

In the pouring nozzle of the present invention, the total cross-sectional area of the through-holes of the fireproof partition plate covering the discharge ports (18, 210) that ultimately discharge the molten metal flow into the molten metal reservoir 52 is made as large as possible. It is desirable to slow down the flow rate of the discharge stream.

Also, there is a pouring room (16,206) and a buffer room (19,209).
) The total cross-sectional area of the communication hole of the fireproof partition plate between the inner nozzle (12, 202) is designed to buffer air bubbles caused by the molten metal falling from the outlet (15, 205) of the inner nozzle (12, 202) into the pouring chamber (16, 206). Room (
19, 209) to prevent it from getting caught in the pouring chamber (16).
, 2o6), it is desirable to maintain the scene at an appropriate height.

〔Effect of the invention〕

As explained above, according to the pouring nozzle of the present invention, there is no need to increase the size of the pouring nozzle, and there is no need to increase the size of the pouring nozzle.
It is possible to prevent slab cracking and breakout caused by remelting of solidified parts at points, and to perform twin-drum continuous casting in a stable manner.

[Brief explanation of the drawing]

1(a) to 1(d) are (a) a side view and (b) a side view showing an example of the pouring nozzle of the present invention in an arrangement state during casting; FIG.
) sectional view, (C) front view, and (d) plan view (partial sectional view). (a) Side view shown in the arranged state,
(b) sectional view, (c) front view, (d) plan view (partial sectional view), and (e) sectional view. (a) A perspective view and (b) a partially cut away perspective view showing an example of a one-way straight hole brick for producing a fireproof partition plate to be used, and FIGS. 4(a) and (b) (a) Side view and (b) showing the pouring nozzle in its arrangement state during casting.
) is a sectional view. 11.201, 41: Pouring nozzle, 12.202.42: Inner nozzle, 13.203.43: Outer nozzle, 14.204, 44: Molten metal inlet of inner nozzle, 15.2
05, 45: Molten metal outlet of inner nozzle, 16.206: Pouring chamber, 46: Space, 17.207: Fireproof partition plate communication part, 47: Refractory filter 18: Fireproof partition plate discharge port, 208: Fireproof partition plate communication section, 19.209: Molten metal flow buffer chamber, 210: Fireproof partition plate discharge port, 211: Molten metal flow auxiliary buffer chamber, 50: Cooling drum, 51: Side weir, 52: Water pool, 53: slab, S: drum surface of the cooling drum 50, M: hot water surface of the molten metal pool 52, m contour line of the hot water surface M on the drum surface S, K: kissing point.

Claims (1)

[Claims] 1. Molten metal is poured into a bottomless mold formed by a pair of cooling drums arranged in parallel with their drum surfaces facing each other and a pair of side weirs pressed against both end surfaces of these cooling drums. A pouring nozzle for a twin-drum continuous casting device that forms a pool by forming a molten metal pool includes an inner nozzle having a molten metal inlet at an upper part and a molten metal outlet at a lower part; an outer nozzle having a pouring chamber at its lower end that receives the molten metal from the molten metal outlet of the inner nozzle; and a molten metal flow buffer chamber disposed below the outer nozzle and having a discharge port for discharging the molten metal in the axial direction of the cooling drum. The pouring chamber of the outer nozzle and the molten metal flow buffer chamber communicate with each other via a fire-resistant partition plate provided with a large number of through holes in the thickness direction, and the discharge port of the molten metal flow buffer chamber has a thickness A pouring nozzle for a twin-drum continuous casting machine characterized by being covered with a fire-resistant partition plate having a large number of horizontal through holes. 2. The pouring nozzle according to claim 1, wherein the molten metal flow auxiliary buffer chamber communicates with the molten metal flow buffer chamber through the discharge port, and discharges most of the molten metal supply in the axial direction of the cooling drum.
A molten metal having a main discharge port covered with a fire-resistant partition plate having a large number of through holes in the thickness direction, and an auxiliary discharge port for discharging the remainder of the molten metal supply toward at least one of the downward direction and the cooling drum surface. A pouring nozzle characterized by having a flow auxiliary buffer chamber.