JPH07112601B2 - 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.

[Conventional technology]

Fig. 5 shows a conventional twin belt type continuous casting device 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 (in this specification, the surface opposite to the mold portion is referred to as the back surface). 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. 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 injected 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. 6 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.

An object of the present invention is to solve such a problem.

[Means for Solving the Problems]

The present invention, in the twin belt type continuous casting apparatus,
Focusing on the fact that the molten metal to be cast is a molten metal such as molten steel and has conductivity, a one-turn induction heating coil for heating the molten metal was installed near the molten metal surface.

That is, according to the present invention, in a twin-belt type continuous casting apparatus having a mode portion having a rectangular cross section extending in the vertical direction, and the mold portion is formed by a pair of molds forming two opposite sides, the mold portion is injected. A pair of one-turn induction heating coils facing each other was provided on the back surface of the pair of belts near the molten metal surface.

[Action]

In the present invention, a pair of one-turn type induction heating coils provided on the back surface of the belt in the vicinity of the pouring surface and facing each other generate an induction current in the molten metal existing near the surface of the molten metal, which causes melting. Since the metal is Joule heated, the molten metal surface is not cooled below the freezing point and solidifies. 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 between the pouring nozzle and the belt is prevented.

Further, in the present invention, since a pair of one-turn type induction coils are adopted, in each one-turn type induction coil, a magnetic field that forms a closed loop independently in the iron core is formed, The molten metal is efficiently heated with little loss.

〔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. 5 and 6, 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 13 disposed near the ends of the belts 1 and 1 '.
13 'forms a mold section M having a rectangular cross section extending in the vertical direction. The molds 13 and 13 '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
Is the iron core for the one-turn type induction coil, which is provided on the back side of the inner belt 1,1 'and has a U-shaped vertical cross section. One-turn induction coils 11, 11 'are formed by the iron cores 9, 9'and the one-turn coils 10, 10', respectively. Also, 12,12 '
Indicates magnetic field lines generated by the one-turn induction coil.

As shown in Fig. 1, one-turn type induction coil 11, 11 '
Are provided in the vicinity of the molten metal surface 8 so as to face each other, and, as shown in FIG. 2, are provided at positions substantially symmetrical with respect to the center line in the width direction of the pair of belts 1, 1 '. An alternating current having an appropriate frequency is applied to the one-turn coils 10, 10 '.

In this way, the alternating current flows through the one-turn coils 10 and 10 ', so that the circumference of each induction coil is
Magnetic force lines 12 and 12 'are induced, and these magnetic force lines pass through the molten metal, that is, mainly in the molten metal near the molten metal surface 8. Moreover, since the molten metal is conductive, a current is induced around the magnetic lines of force 12, 12 'whose polarities are alternately switched, and the induced current causes the molten metal in the vicinity of the molten metal surface 8 to undergo so-called Joule heating. It will be. Therefore, it is possible to reliably prevent the vicinity of the molten metal surface 8 from being cooled and solidified to cause peeling, so that it is possible to prevent accidents such as damage of the pouring nozzle 7 due to peeling. .

The one-turn induction coil of this embodiment is shown in FIG.
Superior in induction efficiency to the transformer / verse induction coil. That is, in the case of the transverse type induction coil, as shown in FIG. 4, the magnetic force lines 102 generated by the copper coils 101, 101 'respectively wound on the iron cores 100, 100'.
The magnetic field lines 102 pass through the installed iron cores 100 and 100 ′ so as to face each other, and then pass through the space on the back side of the iron cores to form a magnetic field having magnetic field lines 102 that enter the iron core of the other side. However, the rate of loss when passing through space increases, resulting in lower efficiency. Further, since it is necessary to wind a large number of coils 101, 101 ', the diameter of the copper wire must be reduced, and a large amount of current cannot flow. On the contrary, in the case of the one-turn induction coil, as shown in detail in FIG.
The magnetic fields are formed independently in the respective iron cores 9 and 9 ', and the magnetic field lines 12 and 12' do not pass through the space behind the iron cores 9 and 9'to form a closed loop in the iron cores. High efficiency with little loss. Also, because it is a one-turn type,
The coils 10 and 10 'can be made hollow so as to have a large air cross-sectional area. With this, a water cooling structure is adopted and a large amount of cooling water can be flowed, so a large current can be passed and a powerful The magnetic flux density can be obtained.

For the above reason, the present embodiment has an advantage that the molten metal in the vicinity of the molten metal surface 8 can be efficiently heated by using the one-turn type induction coils 11, 11 '.

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 is likely to fluctuate. However, the one-turn type induction coils 11 and 11 'are attached to the molten metal surface 8 The belt, which is a ferromagnetic material made of copper, can be installed in the vicinity.
1,1 'are attracted to the one-turn type induction coils 11, 11', respectively, and do not come close to the nozzle 7 side due to water pressure.
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, the one-turn induction coil 1
Since 1,11 'are provided in the water cooling pads 5,5', the coils 11,11 'are thermally protected by the pads 5,5' and the one-turn coil 10,10 'is provided. It is possible to adopt a water cooling structure that makes it hollow and allows cooling water to pass inside,
As a result, the temperature rise of the coils 11, 11 'can be prevented, a large current can be passed, and a strong magnetic flux density can be obtained.

In this embodiment, since the belts 1, 1'are made of metal, they are subjected to induction heating (Joule heating) by the one-turn type induction coils 11, 11 ', but the back side of the belts are water-cooled pads 5, 5'. The belt itself is not heated to a high temperature because it is directly cooled by.

Further, it is desirable that the positions where the one-turn induction coils 11 and 11 'are installed should 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.

Also, the one-turn type induction coil 11 from the belts 1, 1 ',
The distance of the tip of 11 'should be as close as possible to the belt 1, 1', as long as the water flow for cooling the belt is not obstructed.
It is desirable to secure the strength of 2 ', that is, the magnetic flux density.

The above embodiment relates to a twin-belt 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 with a spray or the like instead of the water cooling pad. The turn induction heating coil may 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, the one-turn induction heating coil efficiently heats the molten metal in the vicinity of the molten metal surface, so that the molten metal surface is cooled and solidified, and the peeling that bridges between the belt and the pouring nozzle is prevented. It

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

[Brief description of drawings]

FIG. 1 is an explanatory view of an embodiment of the present invention, and FIG. 2 is a view of FIG.
II-II sectional view, FIG. 3 is an explanatory view showing the operation of the one-turn type coil of the present invention, FIG. 4 is an explanatory view showing the operation of the transverse type coil, and FIG. 5 is a conventional twin belt type continuous FIG. 6 is an explanatory view of the casting apparatus, and FIG. 6 is an explanatory view showing a 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…
… Molding nozzle, 8 …… Melting surface, 9,9 ′ …… Iron core 10,10 ′ …… One turn coil, 11,11 ′ …… One turn induction coil, M …… Mold part, 12 , 12 '... Magnetic field lines.

 ─────────────────────────────────────────────────── ─── 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 in Mitsubishi Heavy Industries, Ltd. Hiroshima Works (56) Reference JP-A-1-138042 (JP, A) JP-A-7-16772 (JP, A)

Claims (1)

[Claims] 1. A twin formed by a mold section having a quadrangular cross section extending in the vertical direction, the mold section comprising a pair of belts forming two opposite sides and a pair of molds forming the other two opposite sides.・ In the belt type continuous casting apparatus, a pair of one-turn type induction heating coils facing each other is provided on the back surface of the pair of belts near the pouring surface of the mold section, which is a twin belt type continuous casting apparatus. Casting equipment.