JPH0645057B2 - Electromagnetic stirrer for continuous casting mold - Google Patents

Description

The present invention relates to an electromagnetic stirrer for a continuous casting mold.

[Conventional technology]

The usefulness of the continuous casting machine is generally recognized from the viewpoint of energy saving in the steelmaking field. Applying an electromagnetic stirrer to this continuous casting machine has a great effect on product quality improvement, and is often installed in the secondary cooling zone. In recent years, continuous casting of high-grade steel and special steel has been promoted, and further quality improvement of these steel types has been demanded. As a result, application of an electromagnetic stirrer to a mold has been attempted.

The conventional electromagnetic stirring technology in the mold is disclosed in JP-A-57-
As typified by Japanese Patent No. 17356, segregation is prevented and non-metallic inclusions are reduced by the stirring effect of a moving magnetic field or a rotating magnetic field on the molten steel in the mold or the damping effect of the molten steel flow by a static magnetic field.

A conventional electromagnetic stirrer will be described with reference to FIG. A magnetizing device including a main iron core 2 and a coil 11 is provided so as to face each other from both sides of the mold 1, and a current converted into a direct current by the rectifier 6a is supplied to the coil 11 through a power feeding cable. A magnetic field 12 is generated in the molten steel inside the main iron core 2 and the mold by the action of this electric current, and the magnetic field 12 causes electromagnetic stirring of the molten steel.

In the conventional electromagnetic stirrer, the main iron core 2, the coil 11, the power supply cable, the cooling pipe and the like are integrated with the mold 1 to form the mold unit 13.

[Problems to be solved by the invention]

The conventional integrated electromagnetic stirrer has the following problems.

Since the mold cooling device and the mold short piece driving device are complicatedly arranged near the mold of the continuous casting machine, the space is narrow, and the size of the electromagnetic stirring device that can be installed is limited, and a sufficient electromagnetic stirring effect can be obtained. Sometimes I can't. This becomes a problem especially when the existing equipment is modified to install the electromagnetic stirrer.

The temperature in the vicinity of the mold of the continuous casting machine is always 200 ° C. or higher and the humidity is high, which is the worst environment for installing electric parts. Above all, the insulation of the coil and cable is easily deteriorated. In particular, the higher the operating voltage of the coil, the lower the reliability of the entire electromagnetic stirring device.

When changing the thickness size of the slab, it is necessary to also replace the electromagnetic stirring device integrated with the mold.
In this case, it is indispensable to remove the power supply cable and the cooling water pipes, and adjust the mounting operation, and the mold replacement work requires a lot of time and labor.

The effect of direct current electromagnetic stirring is the same even if a permanent magnet is used, but in general, an electromagnet is often used to obtain a stable strong magnetic field and the advantage that the magnetic field strength can be adjusted. .

Conventionally, 100 V is used for the AC power source, so that a large current of 200 A to 400 A needs to be passed through the coil to generate a strong magnetic field. Due to the action of this large current and the electric resistance of the coil and the cable, Joule heat is generated, and power (copper loss) corresponding to this heat loss is consumed. This power consumption is determined by the resistance value of the coil and the cable and the current value flowing through the coil and the cable, and is not directly related to the strength of the magnetic field.
It has reached KW.

The present invention solves these problems and provides an electromagnetic stirrer for a continuous casting mold that has low power consumption, high reliability, and improved workability when changing the thickness size of a steel slab. The purpose is to

[Means for solving problems]

The present invention is to solve the above-mentioned problems, main coils provided with coils on opposite sides of a continuous casting mold are provided facing each other, and a direct current is passed through the coils to generate a direct magnetic field in the main core.
It was applied to the electromagnetic stirrer of the continuous casting mold that stirs the molten steel in the mold by the DC magnetic field, and the following technical means were adopted. That is, the constituent parts are, apart from the main iron core, a primary iron core for mounting a primary coil connected to an AC power supply and a secondary iron core for mounting a secondary coil, which are separable from each other. The circuit configuration is such that the secondary coil is attached to the second iron core and the main iron core, and the secondary coil is connected to the closed circuit configuration via the rectifier, and the electromagnetic stirrer for AC magnetically coupling the primary coil and the secondary coil is provided. Configured.

[Action]

The operation of the present invention will be described with reference to FIGS. FIG. 1 is a circuit diagram of an embodiment of the present invention, and FIG.
It is a perspective view of the iron core and the coil of a figure.

The electromagnetic stirrer of the present invention is roughly classified into an external unit 9 composed of a first iron core 2 equipped with a primary coil 7 connected to an AC power source, and a second iron core 3 equipped with a secondary coil 8.
The main core 5, the secondary coil 8 and the rectifier 6 are formed of an internal unit 10 which is a molded unit.

The AC power source is connected to the primary coil 7 of the first iron core 2 and
The next iron core 4 is configured to be separable into a first iron core 2 and a second iron core 3. The secondary coil 8 is configured in a mold unit as shown in FIG. 2, and the inside thereof is composed of two sets of coils, which are respectively attached to the second iron core 3 and the main iron core 5 so as to be linked to each other and closed by the rectifier 6. Connected to form a circuit. As a result, as shown in FIG. 1, the second iron core 3 has the opposite winding direction, and the main iron core 5 has the same winding direction. Therefore, the energy transmission means of the external unit 9 and the internal unit 10 is performed by AC magnetic coupling by coupling the separable primary cores 4. Further, the internal unit 10 is integrally formed independently and eliminates the exposed portion of the circuit.

Therefore, the problem of insulation deterioration in a bad environment such as when connecting and disconnecting with a cable as in the past is solved and the reliability of the device can be improved. Further, since the external unit 9 is attached at a position separated from the center of the mold 1 by about 2 m or more, there is no limitation on the environment and size. In addition, the external unit 9 can be used as it is even when changing the size of the slab, and the work of connecting and disconnecting the external unit 9 and the internal unit 10 can be simplified and the size of the slab can be changed in a short time. Became.

When an AC voltage is applied to the primary coil 7, the AC voltage induced in the two sets of the secondary coils 8 is converted into DC by the rectifier 6, but flows to the second iron core 3 side of the secondary coil 8. Since the direction of the direct current is opposite, the direct-current magnetic field induced in the second iron core 3 is canceled, the direct-current excitation of the primary iron core 4 can be prevented, and the secondary coil 8 flows toward the main iron core 5 side. Since the directions of the direct currents are the same, the direct current magnetic fields 12 induced in the main iron core 5 are added respectively, and the efficiency of alternating current and direct current exchange is improved.

Also, since there is no concern about insulation deterioration, the AC input voltage can be increased, and therefore, if the ampere-turns of the secondary coil 8 on the main iron core side are the same, the number of turns of the secondary coil 8 on the main iron core side can be increased. Since the direct current flowing through the secondary coil 8 can be reduced as well as the number of the secondary coils is increased, the copper loss of the secondary coil 8 can be reduced.

In this case, the number of turns of the secondary coil 8 on the main iron core side is 100
Even if the number of times is up to 300 times, since a direct current is applied, there is no effect of the inductance of the secondary coil 8, and copper loss due to only the direct current resistance value may be considered.

〔Example〕

An embodiment of the present invention will be described with reference to FIG. The secondary coil 8 is formed integrally with the rectifier 6 with an insulator to form an 8-shape. As the insulator, an epoxy resin having good thermal conductivity was used. The production of such a transformer is well established as a technology for producing a mold type transformer, and is easily available.

As shown in FIG. 2, the separated shape of the primary iron core 4 is considered to improve the contact of the iron cores, and the second iron core 3 of the inner unit 10 is used as one part of the outer unit 9,
This facilitates the replacement work of the mold unit when changing the billet size.

Further, in order to reduce the iron loss because an AC magnetic flux (50 to 60 Hz) is passed through the primary iron core 4, a silicon steel plate used in a general transformer has a laminated structure, and the primary AC voltage is 400 V and the primary coil is By increasing the number of turns to reduce the alternating current flowing through the primary coil, the combined copper loss of the primary and secondary can be reduced to 3 to 5 KW, and as a result, the electromagnetic stirrer can be easily cooled.

〔The invention's effect〕

The electromagnetic stirrer of the continuous casting mold of the present invention, as shown below,
It has an excellent effect that high-quality steel billets can be produced efficiently and while saving energy.

The work time required to change the thickness of the slab was about 20 minutes, which was about 30 minutes in the past.

High reliability is obtained, and power consumption is 1/10 to 1 /
It decreased to 15.

[Brief description of drawings]

FIG. 1 is a circuit diagram of an embodiment of the present invention, FIG. 2 is a perspective view of an iron core and a coil of an embodiment of the present invention, and FIG. 3 is a circuit diagram of a conventional example. DESCRIPTION OF SYMBOLS 1 ... Mold, 2 ... 1st iron core 3 ... 2nd iron core, 4 ... Primary iron core 5 ... Main iron core, 6 ... Rectifier 6a ... Rectifier, 7 ... Primary coil 8 ... Secondary coil, 9 ... External unit 10 … Internal unit, 11… Coil 12… Magnetic field, 13… Unit

Claims (1)

[Claims] 1. A continuous casting mold is provided with main iron cores having coils mounted on opposite sides thereof so as to face each other, and a direct current is passed through the coils to generate a direct current magnetic field in the main iron core. In an electromagnetic stirrer of a continuous casting mold for stirring molten steel inside, a secondary coil of a primary iron core different from the main iron core is connected to the coil in series via a rectifier, and the primary iron core of the primary iron core is connected. The coil is connected to an AC power source, and the primary core is separable into a first core for mounting the primary coil and a second core for mounting the secondary coil. An electromagnetic stirrer for a continuous casting mold, characterized in that the secondary coil is AC magnetically coupled.