JPH07112600B2 - Twin belt type continuous casting machine - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a twin belt type continuous casting apparatus for continuously obtaining a slab from molten metal.

[Prior Art] Fig. 3 shows a conventional twin belt type continuous casting apparatus for continuous casting of thin slabs.

1,1 'is a metal (mainly steel) endless belt, 2,2' is a belt driving roll, 3,3 'is a belt positioning top roll, and 4,4' is a belt meandering prevention Steering roll of the above-mentioned drive roll 2,
The pair of belts 1,1 'driven by 2'is the arrow W,
The rolls are guided and moved in the W'direction. Between the positioning top rolls 3 and 3'and the driving rolls 2 and 2 ', the pair of belts 1 and 1'are parallel to each other and move downward with a space C therebetween.

In the part of the pair of belts 1 and 1'which descends in parallel between the positioning rolls 3 and 3'and the driving rolls 2 and 2 at the interval C, the belts 1 and 1'are provided near both ends thereof. A pair of side molds (not shown) is installed to form a mold part extending vertically above and below a rectangular cross section surrounded by the belts 1 and 1'and the side molds.

Reference numerals 5 and 5'represent water-cooling pads for cooling the belts 1 and 1'from the back surface (herein, the back surface opposite to the mold will be referred to). Reference numeral 20 is a ladle for holding molten steel metal, 6 is a tundish for accommodating the molten metal from the ladle 20, and 7 is a pouring nozzle provided in the tundish, which is opened at the upper part of the mold part. Reference numeral 8 is a molten metal surface in the mold portion, and 9 is a slab cast piece formed in the mold portion.

In the conventional twin belt type continuous casting apparatus having such a configuration, a pair of endless metal belts 1,
1'is driven by rolls 2 and 2 ', respectively, at a constant speed, and has a rectangular cross section formed between the pair of belts and a pair of side molds located at the belt ends. The molten metal is continuously poured from the tundish 6 by the pouring nozzle 7. Since the belts 1,1 'driven endlessly are cooled from the back side by the water cooling pads 5,5' as described above, the molten metal injected between the belts 1,1 'is sequentially cooled and solidified. As a result, a slab slab 9 is formed, and the slab slab 9 is fed further downward away from the belts 1 and 1'moving around the rolls 2 and 2 '.

[Problems to be solved by the invention]

FIG. 4 shows a state near the pouring nozzle of the conventional twin belt type continuous casting apparatus. The thickness A of the pouring nozzle 7 is
Due to strength and manufacturing restrictions, it is impossible to reduce the thickness below a certain value. For this reason, if the gap C (corresponding to the thickness of the slab) formed by both belts 1, 1'is made as small as possible to reduce the slab thickness, the belt 1,
1'and the side surface of the pouring nozzle 7 come close to each other. The molten metal near the molten metal surface 8 is cooled by the water-cooling pads 5, 5 ', while the molten metal near the outer surface of the pouring nozzle 7 is also cooled by heat removal from the nozzles. The closer the side of the pouring nozzle 7 is to 1 ', the bridging crust of solidified material, which is indicated by reference numeral 13, is generated in the vicinity of the molten metal surface 8. When the skin beam 13 is generated, the pouring nozzle 7 receives a downward force due to the driven belts 1 and 11 ', so that the pouring nozzle 7 is damaged.

The present invention is intended to solve such a problem.

[Means for solving problems]

The present invention has a mold part having a quadrangular cross section that extends in the vertical direction, and the mold part is a twin formed by a pair of moving belts forming two opposite sides and a pair of molds forming other two opposite sides. In a belt-type continuous casting machine, at least the part of the pouring nozzle facing the belt is made of a conductive refractory, and it faces the back surfaces of the pair of belts in the vicinity of the molten surface of the mold part. Both are provided with a pair of induction heating devices.

[Action]

In the present invention, the induction heating device causes the portion of the pouring nozzle located near the molten metal surface formed between the belts and made of the conductive refractory material to undergo Joule heating by the induction heating device, and the molten metal The temperature is maintained above the freezing point of.

Therefore, even if the distance between the pair of belts is narrowed in order to reduce the wall thickness of the slab, peeling of the solidified material bridging between the pouring nozzle and the belt is prevented.

〔Example〕

An embodiment of the present invention will be described with reference to FIGS.

1 and 2, reference numerals 1 to 8 and reference numeral 1'to
The portion indicated by 5'is the same as the portion indicated by the reference numerals corresponding to FIGS. 3 and 4, and therefore the description thereof will be omitted.

In this embodiment, as shown in FIG. 2, a pair of belts 1 and 1'and a pair of molds 11 and 11 arranged near the ends thereof.
11 'and a mold section M having a rectangular cross section extending vertically is formed. The molds 11 and 11 'have a rectangular cross section and are made of a material such as copper having good thermal conductivity.

9,9 'are cooling pads 5,5' near the molten metal surface 8
Reference numeral 10 denotes an electromagnetic coil provided on the back surface of the inner belt 1, 1 ', and 10 denotes a magnetic field line generated by the electromagnetic coil.

Numerals 30 and 30 'are conductive refractory linings provided on the belt-side surface of the pouring nozzle, and as shown in FIG. 1, are provided near the molten metal surface so as to cover the molten metal surface 8. is there.

As shown in FIG. 1, the electromagnetic coils 9, 9'are provided near the molten metal surface 8, and as shown in FIG.
They are provided at positions symmetrical with respect to the center line of 1,1 '.
An alternating current having an appropriate frequency is applied to the electromagnetic coils 9, 9 '.

In this way, the magnetic field lines 10 are induced between the coils 9 and 9'by the alternating current flowing through the electromagnetic coils 9 and 9'on both sides,
The induced magnetic force lines 10 pass through the molten metal surface, the molten metal in the vicinity of 8 and the pouring nozzle 7. However, on the side facing the belt of the molten metal and the pouring nozzle, and since the portion in the vicinity of the molten metal surface is conductive, an electric current is induced around the magnetic force line 10 whose polarity is alternately switched, and this induced current As a result, the molten metal near the molten metal surface 8 and the conductive refractory linings 30 and 30 'of the pouring nozzle are subjected to so-called Joule heating. Therefore, since the nozzle wall surface of the pouring nozzle 7 on the side facing the belt corresponding to the conductive refractory linings 30 and 30 'is maintained at a temperature equal to or higher than the freezing point of the molten metal, the peeling phenomenon near the molten metal surface 8 (belt And the molten metal existing between the nozzle and the nozzle solidify, and the nozzle 7 and the belt 1,1 '
It is possible to prevent the phenomenon of bridging the and
It is possible to prevent damage accidents of the pouring nozzle 7 in advance.

Further, in this embodiment, since the belts 1, 1'are made of metal, they are subjected to induction heating (Joule heating) by the electromagnetic coils 9, 9 ', but the back side of the belt is directly cooled by the water cooling pads 5, 5'. Therefore, the belt itself is not heated to a high temperature.

Alumina graphite, zirconia graphite, and materials for the conductive refractory parts 30, 30 'of the pouring nozzle 7
Conductive ceramics such as zirconium boride can be used.

In the present embodiment, an example is shown in which the conductive refractory material is attached to the belt of the pouring nozzle 7 and is lined and attached only near the molten metal surface 8. It may be made of a refractory refractory, or only the lower part of the pouring nozzle 7 (in the vicinity of the portion where the molten metal is immersed) may be made of a conductive refractory.

Further, it is desirable that the electromagnetic coils 9 and 9'are installed at positions so as to cover the vicinity of the molten metal surface 8 in terms of the vertical level. In this case, since the molten metal surface 8 fluctuates during the operation of the continuous casting apparatus, it is desirable to set the coil size in consideration of the fluctuation allowance.

Further, the distance from the belts 1,1 'to the tips of the electromagnetic coils 9,9' should be as close as possible to the belts 1,1 ', that is, the magnetic flux 10 It is desirable to secure the density.

The above embodiment relates to a twin wire type continuous casting apparatus of a type having a water cooling pad, but the present invention is not limited to this, and may be one that cools with a spray or the like instead of the water cooling pad, and induction The heating device only needs to be provided on the back surface of the belt near the pouring surface, and is not limited to the one provided in the cooling pad.

〔The invention's effect〕

 The present invention can exert the following effects.

That is, since the molten metal near the molten metal surface and the pouring nozzle are heated by the induction heating device, the molten metal surface is cooled and solidified, and the formation of a skin that bridges between the belt and the pouring nozzle is prevented.

Therefore, it is possible to prevent the pouring nozzle from being damaged by the peeling.

[Brief description of drawings]

1 is an explanatory view of an embodiment of the present invention, FIG. 2 is a sectional view taken along the line II-II of FIG. 1, FIG. 3 is an explanatory view of a conventional twin belt type continuous casting apparatus, and FIG. It is explanatory drawing which shows the state near the pouring nozzle of the conventional twin belt type continuous casting apparatus shown in FIG. 1,1 ′ …… Metal belt, 2,2 ′ …… Driving roll 3,3 ′ …… Positioning top roll 5,5 ′ …… Water cooling pad, 7 …… Pouring nozzle 8 …… Melting surface, 9,9 ′ …… Electromagnetic coil 10 …… Magnetic field, M …… Mold part 30,30 ′ …… Conductive refractory part of pouring nozzle

 ─────────────────────────────────────────────────── ─── Continuation of front page (72) Koichi Hirata 4-6-22 Kannon Shinmachi, Nishi-ku, Hiroshima City, Hiroshima Prefecture Mitsubishi Heavy Industries, Ltd. Hiroshima Research Laboratory (72) Inventor Toru Nishimura 4-chome, Kannon Shinmachi, Nishi-ku, Hiroshima Prefecture 6-22 No. 22 Hiroshima Works, Mitsubishi Heavy Industries, Ltd. (56) Reference JP-A-64-18551 (JP, A)

Claims (1)

[Claims] 1. A mold section having a quadrangular cross section extending in the vertical direction, the mold section being formed by a pair of moving belts forming two opposite sides and a pair of molds forming other two opposite sides. In a twin-belt continuous casting machine that uses a twin-belt continuous casting machine, at least the part of the immersion pouring nozzle that faces the belt is made of conductive refractory, and the back surface of the pair of belts near the molten surface of the mold part. A twin characterized by having at least a pair of induction heating devices facing each other.
Belt type continuous casting machine.