JPH0745093B2 - Magnetic force control device for molten steel flow in cast slab - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to an apparatus for controlling a magnetic force distribution with respect to an unsolidified slab-content steel flow in a continuous casting machine.

[Prior art]

As shown in FIG. 9, in the continuous casting machine, the molten steel injected from the tundish 1 into the casting mold 3 through the immersion nozzle 2 flows in the casting mold 3 or the cast slab S. The braking of the molten steel flow to slow its movement promptly promotes the floating of impurities existing in the molten steel and is extremely effective in maintaining good quality of the cast slab.

As a method of applying a braking force to the molten steel flow, there is an electromagnetic device 4 that forms a static magnetic field in a mold and utilizes an electromagnetic force induced by an interaction between a current induced in the molten steel flow and the static magnetic field.

As shown in FIG. 5, such an electromagnetic device 4 comprises an iron core 5 and an electromagnetic coil 6 wound around the iron core 5. In the conventional case, the iron core 5 is fixed to the long side 3A of the mold 3. The braking force is adjusted by adjusting the magnitude of the current passed through the electromagnetic coil 6. Further, there has been proposed a device capable of moving the electromagnetic device 4 in the width direction and the length direction of the slab. (Actual development
59-85653 gazette) Incidentally, a dynamic magnetic field device for actively flowing a molten steel flow for homogenization of molten steel and a slab has a large number of electromagnetic devices installed,
The magnetic force is sequentially changed, and the magnetic force is adjusted in the same manner as the static magnetic field described above.

[Problems to be Solved by the Invention]

However, in the case of a static magnetic field, if the braking force is adjusted only by adjusting the current of the electromagnetic coil as described above, as shown in FIG. It is impossible to do.

Therefore, not only the portion where the molten steel flow needs a braking force,
The braking force also acts on unnecessary parts, which adversely affects the quality of the slab. In particular, when a braking force is applied to the uppermost meniscus portion of the molten steel surface, the temperature drop of the molten steel becomes remarkable,
Skinning etc. occurs, causing mold surface defects.

If the current is reduced in order to eliminate the braking force of the meniscus portion, the magnetic flux in the portion that originally needs to be braked also becomes smaller in the conventional technology, the braking force becomes insufficient, and the original purpose cannot be achieved. .

Further, although it is possible to eliminate the braking force of the meniscus portion by moving the electromagnetic device itself, the braking force of a necessary portion is also insufficient, which is not preferable. In particular, when lowering the molten steel surface in the mold for use, the surface quality had to be sacrificed.

The dynamic magnetic field has the same problem.

The present invention has been made in view of such circumstances,
An object of the invention is to provide a magnetic force control device capable of adjusting a magnetic flux distribution of a static magnetic field or a dynamic magnetic field formed by an electromagnetic device and optimally controlling a magnetic force distribution given to a molten steel flow.

[Means for Solving the Problems]

As shown in FIG. 1, the magnetic force control device of the present invention uses, as the iron core 5 of the electromagnetic device 4, movable iron cores 5B and 5C divided into a plurality of parts in the casting direction and / or the casting width direction. Wick 5B,
Each of 5C is configured to be independently movable to and from the mold 3 by the drive mechanism 7.

[Action]

The magnetic flux distribution can be changed by separately moving the movable iron cores 5B and 5C with respect to the cast slab S or the mold 3. For example, as shown in FIG. 4, the upper movable iron core 5B is attached to the mold 3
By arranging the movable iron core 5C on the lower side closer to the above, the magnetic flux in the meniscus portion can be eliminated, and the maximum magnetic field can be formed in the portion where the braking force is originally required.

Also in the case of a driving magnetic field device in which a large number of electromagnetic devices 4 are arranged in the width direction of the slab, the magnetic flux distribution of the end electromagnetic device is changed in accordance with the width of the slab to reduce the magnetic flux in unnecessary portions, thereby reducing the magnetic field. The action can be made proper.

〔Example〕

The present invention will be described below with reference to an embodiment showing a case of a static magnetic field. In addition, the same reference numerals are given to the same or corresponding portions as in the conventional case.

As shown in FIGS. 1 to 3, an example of a four-pole structure in which a pair of electromagnetic devices 4 facing each other are arranged on the long side 3A of the mold 3 of the slab S on the left and right in the long side direction of the immersion nozzle 2. And
The iron core 5 is divided into a rectangular tubular fixed iron core 5A and upper and lower parts,
It is composed of movable iron cores 5B and 5C that can move horizontally in the fixed iron core 5A, and the upper and lower movable iron cores 5B and 5C are independently with respect to the mold 3 by a driving mechanism 7 such as a screw rod type. It is possible to move back and forth horizontally. Also, fixed iron core on the same side
5A is connected by a yoke 8 forming a magnetic path.

The movable iron cores 5B, 5C and the yoke 8 are made of magnetic steel to reduce the magnetic resistance, and the fixed iron core 5A supports the movable iron cores 5B, 5C and is a structure attached to the long side 3A. Although such a material may be used, a non-magnetic material is preferable in order to concentrate all the magnetic flux on the movable iron cores 5B and 5C.

In the above configuration, as shown in FIG. 4 (A), when the upper and lower movable iron cores 5B and 5C are closely attached to the long side 3A and a current is applied to the electromagnetic coil 6, the magnetic flux distribution in the mold is It becomes the same as the conventional one.

However, when only the upper movable iron core 5B is arranged away from the long side 3A, the maximum part of the magnetic flux distribution is shown in FIG. 4 (B).
As shown in FIG. As a result, the upper braking force disappears, and the lower braking force is maintained at the maximum braking force shown in FIG. 4 (A).

In the conventional technique of lowering the current shown in FIG. 5 (B), the magnetic flux distribution is wholly reduced, and the maximum portion is greatly reduced. However, in the present invention, the necessary portion is eliminated while eliminating the braking force of the meniscus portion. The maximum braking force can be applied to.

Further, by reversing the vertical pushing amounts of the movable iron cores 5B and 5C, the magnetic flux distribution can be reversed, and various magnetic flux distributions can be obtained by adjusting the vertical pushing amount and the current of the electromagnetic coil 6. Needless to say.

Further, if the drive mechanism 7 can be operated remotely by using electric power or hydraulic pressure, it is possible to perform dynamic control according to the molten steel level, the molten steel temperature and the like.

Next, FIG. 6 to FIG. 8 show a modified example, and FIG. 6 shows a movable iron core 5A to 5E which is divided into two in four in the width direction of the slab, and the width of the slab is directional. Also, it is possible to control the magnetic flux distribution. FIG. 7 shows an example of division into three parts, which is shown in FIG.
The magnetic flux distribution can be controlled more finely than the division. FIG. 8 shows an example in which a through hole 9a is provided in the iron core 9, and the movable iron core 5 engaged with a screw part engraved in the through hole 9a is swung by a drive mechanism 7 so as to be able to move forward and backward. is there.

〔The invention's effect〕

As described above, the device of the present invention is configured such that the movable iron core divided into a plurality of parts in the casting direction or / and the casting width direction can be moved back and forth with respect to the slab, so that the magnetic field magnetic flux density distribution in the slab can be arbitrarily set. It is possible to change, the optimal magnetic flux density distribution, that is, the optimal braking force or The driving force can be applied to the molten steel flow. As a result, it is possible to give a desired braking force while eliminating the adverse effect of the braking force in the meniscus portion, to eliminate the surface flaw of the slab and to improve the inner chamber. Alternatively, it is possible to form an optimum magnetic flux distribution according to the width of the slab and reduce unnecessary power.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1, FIG. 2, and FIG. 3 are a longitudinal sectional view showing a device of the present invention, a plan view, a side view, and FIG. 4 is an explanatory view showing an operating state of the present invention. FIG. 5 is an explanatory view showing a conventional operating state, and FIG.
FIGS. 7, 7 and 8 show modified examples of the device of the present invention,
(A) is a longitudinal sectional view, (B) is a side view, and FIG. 9 is an overall view showing a continuous casting machine. 1 ... Tundish, 2 ... Immersion nozzle, 3 ... Mold, 4 ... Electromagnetic device, 3A ... Long side, 5 ... Iron core, 5A ...
... Fixed iron core, 5B-5E ... Movable iron core, 6 ... Electromagnetic coil,
7 ... Drive mechanism, 8 ... Yoke, 9 ... Fixed iron core.

Claims (1)

[Claims] 1. An electromagnetic device comprising an iron core and an electromagnetic coil wound around the iron core is arranged in a mold or on the side of an unsolidified cast piece after the mold, and a magnetic field is generated in the cast piece by the electromagnetic apparatus. In the device for applying a magnetic force to the molten steel flow in the cast slab by forming a plurality of movable iron cores in the casting direction and / or the casting width direction in the iron core of the electromagnetic device, A magnetic force control device for molten steel flow in a slab, characterized in that the cores are independently movable with respect to the slab by a drive mechanism.