JPH0716772B2 - Twin belt type continuous casting machine - Google Patents

Description

TECHNICAL FIELD The present invention relates to a twin-belt type continuous casting apparatus for continuously obtaining a thin plate-shaped 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 And a steering roll for driving the above
A pair of belts 1,1 'driven by 2,2' have arrows 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, and a mold part extending vertically is formed in 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 (the surface on the opposite side of the mold portion is referred to as the back surface in this specification). Reference numeral 20 is a ladle for holding the molten metal, 6 is a tundish for containing 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 portion. 8
Is a molten metal surface in the mold part, and 9 is a slab cast piece formed in the mold part.

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 is applied to the mold part having a rectangular cross section formed between the pair of belts and the pair of side molds located at the belt ends. The molten metal is continuously injected from the tundish 6 by the pouring nozzle 7 as a dipping nozzle. Since the belts 1 and 1'driven endlessly are cooled from the back side by the water cooling pads 5 and 5'as described above,
The molten metal injected between the belts 1 and 1'is sequentially cooled and solidified to form a slab slab 9, which is formed by the roll 2,
It is fed further downward away from the belts 1, 1'moving around 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 by the driven belts 1 and 1 ', 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 focuses on the fact that the molten metal cast in the twin-belt type continuous casting apparatus is a molten metal such as molten steel and has conductivity, and an induction heating coil for heating the molten metal has a molten metal. It was installed near the plane.

That is, the present invention has a mold part having a rectangular cross section that extends in the vertical direction as described above, and the mold part is formed by a pair of molds forming two opposite sides, and the molten metal is poured into the mold part for immersion. In a twin belt type continuous casting apparatus equipped with nozzles, a plurality of pairs of induction heating coils facing each other and heating the vicinity of the molten metal surface are provided in the belt width direction on the back surfaces of the pair of belts.

[Action]

In the present invention, a plurality of pairs of induction heating coils for heating the vicinity of the molten metal surface of the molten metal are provided on the back surfaces of the pair of belts in the width direction of the belt. An induced current is generated, whereby the entire molten metal in the vicinity of the molten metal surface is Joule heated, and the molten metal surface is not cooled below the freezing point to solidify. Therefore,
Even if the distance between the pair of belts is narrowed in order to reduce the thickness of the slab, peeling of the solidified material bridging the dipping 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 'is a water cooling pad 5,5' near the molten metal surface 8.
The electromagnetic coils serving as a pair of induction heating coils are provided on the back surfaces of the belts 1 and 1'inside, and reference numeral 10 denotes magnetic lines of force generated by the electromagnetic coils.

As shown in FIG. 1, a pair of electromagnetic coils 9, 9'is provided near the molten metal surface 8, and as shown in FIG. Belt at the position of 1,1 ′
A plurality of pairs are provided in the width direction. Same electromagnetic coil 9,9 '
An alternating current having an appropriate frequency is applied to.

By thus flowing an alternating current in the electromagnetic coils 9 and 9'on both sides, magnetic lines of force 10 are induced between the coils 9 and 9 ', and the molten metal has a higher magnetic permeability than air.
The lines of magnetic force pass through the molten metal, that is, the molten metal mainly near the molten metal surface 8. Moreover, since the molten metal is electrically conductive, the magnetic field lines 10 whose polarities are switched alternately.
An electric current is induced in the area surrounded by, and the molten metal in the vicinity of the molten metal surface 8 is subjected to so-called Joule heating by this induced current. Moreover, the pair of electromagnetic coils 9 and 9'includes the belt 1,
Plural pairs are provided in the width direction of 1 '. Therefore, it is possible to reliably prevent the molten metal in the vicinity of the molten metal surface 8 from being heated and the molten metal surface 8 to be cooled to solidify the molten metal to cause peeling. Accidents such as breakage of the nozzle 7 can be prevented in advance.

Further, in the present embodiment, the pressure of the molten metal is almost 0 in the vicinity of the molten metal surface 8, whereas the back surface of the belts 1, 1'is subjected to water pressure due to the water flow in the water cooling pads 5, 5 '. There is. For this reason, the belts 1 and 1'may be pushed to the pouring nozzle 7 side, and the slab thickness tends to fluctuate. However, the electromagnetic coils 9 and 9'are installed near the molten metal surface 8. As a result, the steel belts 1 and 1 ′, which are ferromagnetic materials, are attracted to the electromagnetic coils 9 and 9 ′, respectively, and the nozzle 7 is driven by water pressure.
Don't go to the side. Therefore, the gap between the belts 1 and 1'is always kept constant, and the slab having a constant thickness can be obtained.

Furthermore, in this embodiment, since the electromagnetic coils 9 and 9'are provided in the water cooling pads 5 and 5 ', the coils 9 and 9'are thermally protected by the pads 5 and 5'.

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.

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 that the coil size be set in consideration of 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-belt type continuous casting device of a type having a water cooling pad, but the present invention is not limited to this, and cooling may be performed by a spray or the like instead of the water cooling pad. The heating coil 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, by providing a plurality of pairs of induction heating coils in the belt width direction that face each other on the back surfaces of the pair of belts and heat the vicinity of the molten metal surface, it is possible to heat the entire molten metal near the molten metal surface. As a result, the molten metal surface is cooled and solidified, and the occurrence of peeling that bridges between the belt and the dipping nozzle is prevented.

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

[Brief description of drawings]

FIG. 1 is an explanatory view of an embodiment of the present invention, FIG. 2 is a sectional view taken along 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 ′… Drive 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.

 ─────────────────────────────────────────────────── ─── Continuation of front page (72) Inventor Osamu Nishimura 4-6-22 Kannon Shinmachi, Nishi-ku, Hiroshima City, Hiroshima Prefecture Mitsubishi Heavy Industries Ltd. Hiroshima Works (56) References JP-A-62-183940 (JP, A)

Claims (1)

[Claims] 1. A mold part having a quadrangular cross section extending in the vertical direction, and the mold part is formed by a pair of belts forming two opposite sides and a pair of molds forming other two opposite sides. In a twin-belt type continuous casting apparatus equipped with a dipping nozzle for pouring molten metal into a belt, a pair of induction heating coils for heating the vicinity of the molten metal surface of the molten metal are provided on the back surfaces of the pair of belts so as to face each other. Twin belt type continuous casting machine characterized by having multiple pairs in the width direction.