JP2008161884A - Electromagnetic stirring device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To form a flow causing to stir at the same time in the axial direction and the circumferential direction only with a magnetic field generating coil moving in the axial direction. <P>SOLUTION: The magnetic field generating coil 3 moving in the axial direction, for generating the magnetic line of force to the axial direction of a solidified shell 3 to an electrically conductive material 1 in a molten state surrounded by the solidified shell 4, is constituted so that the axial centers Oa to Of of respective rings 3a to 3f are tilted to the axis Ov of the solidified shell 4, and further, the axial centers Oa to Of of the respective rings 3a to 3f are arranged so as to be shifted one by one at intervals to the circumferential direction and the axial direction of the solidified shell 4, thereby such a flow that movement in the axial direction and the rotational movement are superposed is caused to the electrically conductive material 1 in a molten state surrounded by the solidified shell 4, so as to perform stirring. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a continuous casting apparatus. More specifically, the present invention relates to a continuous casting apparatus having a step of agitating a solidified conductive material such as molten metal in a non-contact manner using electromagnetic force.

  In recent years, an in-mold electromagnetic stirrer has been proposed as a countermeasure for cleaning the slab surface layer of a slab continuous casting apparatus, in which a molten steel portion in a slab being solidified is flowed by electromagnetic force in a mold (Non-patent Document 1). By installing a linear inductor behind the slab in the mold, a parallel magnetic field that covers the entire width of the mold is generated, and the molten steel near the meniscus in the mold is rotationally driven in the horizontal direction by this parallel magnetic field. The molten steel stirring flow generated by the moving magnetic field is washed out of non-metallic inclusions captured between the columnar crystals, and is prevented from being captured by the initial solidified shell. In addition, the washed out non-metallic inclusions collide and agglomerate at the center of the molten steel and become enormous and easily float up. It is trying to be. Further, this stirring flow makes the molten steel temperature distribution in the mold uniform and reduces the deviation of the solidified shell thickness, thereby reducing the distortion of the initial solidified shell due to the solidification delay and preventing the vertical crack of the slab.

  On the other hand, in electromagnetic stirring of molten metal, it is known that it is effective to stir not only in the circumferential direction but also in the vertical direction at the same time. When applied to the stirring of molten metal in a container, electromagnetic stirring using a rotating (circumferential) moving magnetic field has the disadvantage that large electric power cannot be applied because the liquid level is greatly deformed by rotation, and only horizontal rotational motion is possible. Then, since the molten metal behaves close to a rigid body rotation, mixing of the molten metal is not sufficient. Also from the experimental results, it has been found that there is a large resistance to the movement in the axial direction as compared with the rotational movement of the molten metal, and a sufficient effect cannot be obtained only by the rotational movement by the rotating magnetic field.

  Therefore, in recent years, two types of coils, a three-phase AC coil that generates a vertical moving magnetic field and a three-phase AC coil that generates a circumferential moving magnetic field, are arranged outside the container, and the electromagnetic effect in the vertical direction and the circumferential force are utilized by using the induction effect. There has been proposed a technique in which stirring is performed simultaneously in the vertical direction and the circumferential direction by generating electromagnetic force in a direction (Patent Document 1).

  In addition, a coil (referred to as a rotating coil) that applies a rotating magnetic field to the molten metal in the container is disposed obliquely on the iron core so as to twist with respect to the axis of the container, and a torsional magnetic field is applied by energization of three-phase alternating current. There has also been proposed an inductive electromagnetic drive device that provides an axial traveling magnetic field (moving magnetic field) simultaneously with a magnetic field (Patent Document 2).

Nippon Steel Technique No. 376 “Nippon-made slab electromagnetic stirring device“ M-EMS ”” JP 2003-220323 A JP 2000-152600 A

  However, in the case of the in-mold electromagnetic stirring device in the slab continuous casting device of Non-Patent Document 1, only the horizontal magnetic field is used. Stirring by the horizontal rotating magnetic field is stronger toward the periphery and weaker toward the center. Therefore, the stirring force in the vicinity of the surrounding solidified shell formed in the mold is the strongest, and the stirring effect decreases toward the center. For this reason, although it is useful in cleaning measures of the slab surface layer that prevents non-metallic inclusions from being washed out and captured by the initial solidified shell, stirring is performed toward the center of the slab where solidification occurs most slowly in the solidified shell. It is difficult to occur, and the crystal grows greatly, so that no effect can be expected for making the crystal grains finer and uniform.

  Moreover, in the electromagnetic stirring apparatus of patent document 1, since the three-phase alternating current coil which produces a vertical movement magnetic field, and the three-phase alternating current coil which produces a circumferential movement magnetic field are piled up on the outer side of a container, a coil volume is bulky. Since the size is increased and two types of coils are provided, expensive equipment is required.

  In addition, since the electromagnetic stirrer of Patent Document 2 is arranged so as to twist a coil that applies a rotating magnetic field, the current flowing through the molten metal does not form a closed loop in the device, and thus does not contribute to the generation of thrust. Energy is generated and the stirring ability tends to be low.

  An object of this invention is to provide the continuous casting apparatus and method which enable refinement | miniaturization and uniformization of a crystal grain. In addition, the present invention provides a continuous casting apparatus and method in which the flow of stirring the axial direction and the circumferential direction simultaneously can be generated by one kind of moving magnetic field generating means, the equipment cost is low, and the equipment volume is compact. With the goal.

  In order to achieve such an object, the continuous casting method of the present invention provides a solidified shell for a molten conductive material inside the solidified shell until the molten conductive material starts to solidify and completes solidification. A plurality of axially moving magnetic fields that move in the axial direction of the solidified shell are inclined with respect to the axis of the solidified shell and are sequentially shifted at intervals in the circumferential direction and the axial direction of the solidified shell, and the axially moving magnetic field is applied to the solidified shell. It is made to rotate around and electromagnetically stir. Further, the continuous casting apparatus of the present invention surrounds the solidified shell in the whole region or any region until the solidified conductive material starts to solidify and completes solidification, and the molten state conductive material inside the solidified shell. An axially moving magnetic field generating ring for generating a magnetic force line in the axial direction of the solidified shell with respect to the active substance inclines the axis of each ring with respect to the central axis, and the axis of each ring is arranged in the circumferential direction of the solidified shell. Axial electromagnetic force is generated in the molten conductive material, which is arranged sequentially shifted at intervals in the axial direction and surrounded by the solidified shell by the axially moving magnetic field generating ring, and at the same time, the axially moving magnetic field is solidified. It is designed to rotate around the shell.

  In the conductive material in the molten state near the solidified shell, the magnetic field generated by the axially moving magnetic field generating ring has a vertical component and a horizontal component due to the inclination of the coil axis, and the vertical component is in the vertical direction (axial direction). The horizontal component acts as a magnetic field that rotates the horizontal plane in the circumferential direction. For this reason, the moving magnetic field of the spiral flow which synthesize | combines a vertical component and the rotation component of the circumferential direction is produced | generated. An electromagnetic force having a vertical component and a rotational component is formed between the moving magnetic field of the spiral flow and a molten conductive material such as a current flowing through the molten metal by electromagnetic induction, and the molten conductive material in the vicinity of the solidified shell. Is given a spiral motion.

  Here, in the electromagnetic stirrer of the present invention, the axially moving magnetic field generating ring is preferably an annular electromagnetic coil in which the axially moving magnetic field rotates around the solidified shell when energized, more preferably a three-phase AC coil. Adopting and using a forward winding coil and a reverse winding coil, a phase difference of 60 ° is provided between adjacent coils.

  In the electromagnetic stirring device of the present invention, the axially moving magnetic field generating ring is a permanent magnet, and the axially moving magnetic field is moved around the container or flow by rotating the ring itself around the container or the central axis of the flow. You may make it rotate. In this case, the axially moving magnetic field generating ring is preferably a high-temperature superconducting magnet.

  Further, it is preferable that the axially moving magnetic field generating ring in the electromagnetic stirrer of the present invention has its axial center shifted by 60 ° in the circumferential direction and made one turn with 6 rings.

  According to the electromagnetic stirrer and method of the present invention, the axial electromagnetic force is generated in the molten conductive material surrounded by the solidified shell by the axially moving magnetic field generating coil, and at the same time, the magnetic field flows through the conductive material. Therefore, the molten metal is provided with a molten metal flow caused by the axial electromagnetic force and a flow different from this flow, that is, a flow accompanying the movement of the magnetic field in the circumferential direction. As a result, the molten metal in the vicinity of the peripheral wall of the container has a flow in which the axial motion and the rotational motion due to the electromagnetic force in the axial direction are superimposed, and the molten metal is moved around the axial direction only by the axial moving magnetic field generating means. Are simultaneously stirred in the direction. Therefore, since it is possible to form a spiral swirl flow that enables simultaneous stirring in the axial direction and the circumferential direction only by the axial moving magnetic field generating coil without combining two types of electromagnetic coils of the rotating magnetic field type and the linear motor type, The number of parts is small and the equipment can be made compact and inexpensive.

  In addition, a portion of the molten conductive material that has been agitated by convection toward the center of the solidified shell while being given a helical rotational force, that is, a portion that has started to crystallize, is crystallized due to collision at the boundary with the solidified shell. Since the grains are crushed and made fine, the crystal grains can be made finer and uniform. In addition, since the axial movement component effective for stirring is mainly generated and the circumferential movement component (rotation) is generated, the stirring ability is also high. Accordingly, the crystal grains are crushed and refined, and the crystal grains can be solidified with the crystal grains kept small to suppress regrowth of the crystal grains.

  Furthermore, according to the electromagnetic stirrer according to claim 3, since the moving magnetic field is generated only by the energization control to the electromagnetic coil constituting the axial direction moving magnetic field generating ring, and the mechanical drive unit is not required, the operation is stable. To do. In particular, according to the electromagnetic stirrer described in claim 4, it is possible to generate a moving magnetic field by using the phase difference of the current of the three-phase power source simply by using the commercial power source as it is.

  According to the electromagnetic stirrer of claim 5, since the axially moving magnetic field generating ring is composed of a permanent magnet, the ring itself can be rotated only by rotating the ring itself around the central axis of the container or the flow. The rotation of the moving magnetic field can be realized. In particular, according to the electromagnetic stirring device according to claim 6 using a high-temperature superconducting magnet, a large stirring force can be obtained because a large electromagnetic force can be applied.

  Hereinafter, the configuration of the present invention will be described in detail based on embodiments shown in the drawings.

  FIG. 1 shows an embodiment of an electromagnetic stirring type continuous casting apparatus according to the present invention. The continuous casting apparatus of this embodiment includes an electromagnetic stirring device 3 that applies electromagnetic stirring force around the mold 2 or the secondary cooling zone 8, and a molded product in which a molten conductive material 1 is surrounded by a solidified shell 4. On the other hand, electromagnetic stirring is applied until the molten conductive material 1 starts to solidify and solidifies. The electromagnetic stirring device 3 includes a plurality of, for example, six axially moving magnetic field generating rings 3 a to 3 f that generate magnetic lines of force in the axial direction of the solidified shell 4 with respect to the molten conductive material 1 surrounded by the solidified shell 4. The axial centers Oa to Of of the rings 3a to 3f are inclined with respect to the central axis Ov of the solidified shell 4 or the mold 2, and the axial centers Oa to Of of the rings 3 are arranged in the circumferential direction of the solidified shell 4 or the mold 2. They are arranged so as to be sequentially shifted with an interval in the axial direction.

  The electromagnetic stirring device 3 applies an axial moving magnetic field to the molten conductive material 1 inside the solidified shell 4 until the molten conductive material 1 starts to solidify and completes solidification. 4 is applied while rotating around 4. The electromagnetic stirring applies an axial moving magnetic field to the molten conductive material 1 surrounded by the solidified shell 4 at any time between the start of solidification of the molten conductive material 1 and the completion of solidification. is required. Therefore, the electromagnetic stirring device in the continuous casting apparatus is preferably used by being disposed in any one of the three positions in the mold, under the mold, or at the end of solidification, or in combination of two or more, and more preferably the solidification start. To provide electromagnetic stirring throughout the entire process. Therefore, in this embodiment, the electromagnetic stirring device 3 is arranged around the mold 2 and the solidified shell 4 of the secondary cooling zone 8.

  Here, the mold 2 must have a cooling capability and at the same time allow the magnetic flux to pass therethrough, and is a material that can easily penetrate the magnetic field lines and has a melting point higher than the melting point of the molten metal 1 to be stirred. For example, it is made of austenitic stainless steel having a low magnetic permeability, non-ferrous metal such as copper or aluminum, or a combination thereof. For example, it is preferable to use a mold composed of a copper plate having a function of cooling molten steel and a stainless steel member for maintaining rigidity as a mold. However, if the copper plate or stainless steel is too thick, an eddy current flows inside due to the magnetic field and a repulsive magnetic field is generated. As a result, the magnetic field in the molten conductive material may be attenuated. Therefore, in order to apply a strong electromagnetic force to the molten conductive material, the copper plate is preferably low in conductivity and thin, and the stainless steel member is also preferably thin. Therefore, the mold 2 is composed of, for example, a thin copper plate or a cooling copper plate in which slits are inserted to suppress the generation of eddy currents and stainless steel that is in direct contact with the molten metal. It is also possible to reduce the attenuation of the magnetic flux density by reducing the frequency of the exciting current. For example, the use of a low frequency current of 10 Hz or less, preferably about 5 Hz, facilitates the passage of the magnetic flux. In particular, it is preferable to use a low-frequency current of 10 Hz or less for electromagnetic stirring at the end of solidification of a large-section bloom because it is necessary to apply an electromagnetic force through the thick solidified shell 4. Further, in the case of the electromagnetic stirring device 3 arranged immediately below the mold or at the position reaching the end of solidification, a current at a commercial power supply frequency is used to reduce the attenuation of the electromagnetic force.

  A cooling pipe (not shown) that circulates cooling water for forming the solidified shell 4 is embedded in the mold 2 and is always cooled. Therefore, the axial movement of the electromagnetic stirring device 3 arranged around the cooling pipe is provided. The magnetic field generating rings 3a to 3f do not directly receive the radiant heat of the molten metal, and there is no possibility of being heated by the solid radiant heat.

  The axially moving magnetic field generating rings 3a to 3f that constitute the electromagnetic stirring device 3 apply an axially moving magnetic field to the molten conductive material 1 wrapped in the solidified shell 4, so that the outside of the mold 2 or the mold 2 is installed around the solidified shell 4 pulled out from 2. In the case of the present embodiment, the axially moving magnetic field generating rings 3 a to 3 f are configured by annular magnetic field generating coils, and include a cylindrical iron core 5 that opens inwardly on the inner peripheral surface side of the iron core 5. Each of the annular grooves (slots) 6 formed as described above is wound with a number of turns as necessary. Here, since the strength of the magnetic field is determined by multiplying the number of turns of the coil by the current value, the number of turns is determined so as to satisfy a condition for obtaining a desired magnetic field strength. That is, the number of turns is determined so as to satisfy the condition of (magnetic field strength) = (number of turns) × (current). Moreover, the electric current sent through each coil 3a-3f is calculated | required from (current) = (voltage) / (impedance).

  And the annular coils 3a-3f which wound the coil wire material concentrically in each slot 6 are accommodated. That is, the axial direction moving magnetic field generating coils 3a to 3f are formed by concentrically arranging a plurality of annular coils in the axial direction. The number of axially moving magnetic field generating rings constituting the electromagnetic stirrer 3 is not particularly limited to the above six, and the material, type and amount of the molten conductive material 1 to be stirred, the mode and strength of stirring, etc. Set arbitrarily according to.

  FIG. 3 shows a conceptual diagram of axially moving magnetic field generating rings 3a to 3f composed of magnetic field generation in which 20 turns are wound. In this figure, the axially moving magnetic field generating rings (magnetic field generating coils) 3a to 3f in FIG. 1 are arranged concentrically for convenience of explanation in order to explain the relationship between the energized state of the three-phase alternating current and the generated magnetic flux. The iron core 5 and the slots 6 are also shown in a state in which a plurality of concentric circles are arranged at equal intervals in the axial direction. The magnetic field generating coil 3 in FIG. 3 includes three types of coils A, B, and C that respectively flow three-phase alternating current having a phase difference of 120 °, and X, Y, Three types of coils, Z, are set. As for the arrangement order of the coils, assuming that the coils of the three-phase alternating current phases are A, B, and C, and the coils wound in the opposite directions are X, Y, and Z, for example, FIG. As shown in B) and (C), A → Z → B toward the lower side in the axial direction of the mold so that A and X, B and Y, and C and Z are connected and face each other. → X → C → Y → A →... → Y, the phase difference of each coil is set to 60 °, and it is provided so as to make one round with the six rings 3a to 3f. That is, as shown in FIGS. 3B and 3C, when A is 0 degree, Z is 60 degrees, B is 120 degrees, X is 180 degrees, C is 240 degrees, and Y is 300 degrees. . That is, as shown in FIG. 1, the electromagnetic stirring device 3 of the present embodiment surrounds the solidified shell 4 and includes six annular coils 3 a to 3 f, and the coil is a three-phase AC coil. Using a direction-wound coil and a reverse-wound coil, a phase difference of 60 ° is provided between adjacent coils. Therefore, when a three-phase AC current is supplied to the magnetic field generating coil 3 from a power source (not shown), for example, as indicated by an arrow in FIG. After reaching, magnetic lines of force that pass through the mold 2 and return to the iron core 5 are generated. Magnetic field lines are generated for each coil, but a moving magnetic field downward in the axial direction of the mold is formed by a phase difference between adjacent coils, a winding direction, and a change in current flowing in each coil. In addition, since the magnetic field moves in the circumferential direction according to the amplitude of the three-phase alternating current, a spiral flow 7 occurs in the molten metal that is the conductive material 1 in the molten state.

  Although not shown in the drawings, the magnetic field generating coils 3a to 3f are sometimes installed in an annular mold filled with a coolant, for example, cooling oil, to prevent overheating due to energization. An axially moving magnetic field generating coil is energized with a three-phase alternating current of an arbitrary frequency from a three-phase alternating current commercial power source through a frequency variable inverter or the like.

  According to the continuous casting apparatus including the electromagnetic stirrer 3 configured as described above, when a three-phase alternating current is supplied to the three-phase alternating current coils that are the axially moving magnetic field generating rings 3a to 3f, the coil is in accordance with Ampere's law. Magnetic field lines are generated through the surrounding yoke material. The lines of magnetic force generated by the concentric ring coils penetrate the mold 2 and the solidified shell 4 and enter the molten metal 1 to form a magnetic path. As the current of the three-phase alternating current changes with time, the magnetic field around the coil moves. By this moving magnetic field, current is always generated in the circumferential direction in the molten metal 1 according to Faraday's law of electromagnetic induction. The direction of this current always changes due to the fluctuation of the magnetic field due to the moving magnetic field, but the direction of the electromagnetic force is always the same direction and is generated in a certain direction, for example, downward. That is, by forming a downward moving magnetic field, a current flowing in the circumferential direction is generated in the vicinity of the wall surface of the molten metal mold 2, that is, at a position where the lines of magnetic force penetrate the mold 2 and the solidified shell 4 in the radial direction. For example, at the P1 position in FIG. 3A, a current from the back side to the near side in the figure is generated, and at the P2 position, a current from the near side to the back side in the figure is generated. A downward electromagnetic force F is generated from the Fleming's left-hand rule by the moving magnetic field and the current generated in the molten metal 1. The direction of the current generated in the conductive liquid 1 is reversed depending on the location, but the winding directions of the A, B, C coil 3 and the X, Y, Z coil 3 are also reversed. Electromagnetic force F is generated.

  For this reason, since the electromagnetic force F in the axial direction is generated in the molten metal 1 and this electromagnetic force is moved in the circumferential direction and in the axial direction at the same time, the axial electromagnetic force and the circumferential direction of the molten metal 1 are increased. A slanting direction thrust combined with the electromagnetic force works to cause the molten metal 1 to flow in a certain direction, that is, a slanting downward direction. The flow along the inner surface of the solidified shell then reverses to become an upward flow, rises toward the liquid level at the center of the solidified shell, and reverses again to the wall surface side of the solidified shell at the liquid level. Causing convection to circulate as a downward flow along. This convection has a movement in the axial direction as a main component, but is accompanied by a rotation component in the circumferential direction, and thus becomes a spiral flow in which the axial direction and the circumferential direction are simultaneously stirred. In this case, a strong spiral flow toward the center of the unsolidified molten metal due to the axial electromagnetic force and the movement of the circumferential magnetic field acts on the molten conductive material and stirs. Growth can be controlled. For example, it becomes possible to increase equiaxed dendrites and disperse segregation of solute elements at the final solidification position among a number of equiaxed crystals. Moreover, the crystal grains can be made fine by crushing the crystal grains by hitting the liquid metal with the liquid metal. Agitation by a rotating magnetic field is stronger toward the periphery and weaker toward the center. However, the crystal grains can be made finer and uniform by colliding at the boundary surface.

  Here, a downward flow is generated with respect to the molten metal 1 in the vicinity of the peripheral wall of the mold 2 or the inner wall surface of the solidified shell 4, and an upward flow is generated with respect to the molten metal 1 in the central portion of the mold 2 or the solidified shell 4. The liquid surface of the molten metal 1 is recessed at the center of the mold 2 due to the rotational movement caused by the movement of the moving magnetic field in the circumferential direction at the same time. As a result, the liquid level of the molten metal 1 is substantially uniform over the radial direction of the mold 2 and is kept almost flat. Therefore, a large current is supplied to the axially moving magnetic field generating coil 3 to the molten metal 1. Even if a large movement is generated, the molten metal 1 does not overflow from the mold 2.

  In addition, the apparatus of the present invention can mainly superimpose the rotational motion obtained without impairing the axial motion, with the generation of the magnetic field mainly consisting of the axial motion in which a large resistance is generated compared to the rotational motion of the molten metal 1. It is possible to give strong and uniform stirring to the molten metal 1.

  By forming an axially moving magnetic field in the solidified shell 4 by the axially moving magnetic field generating coil 3, in the vicinity of the peripheral wall of the solidified shell 4, there is a gap between the current flowing in the molten conductive material such as molten metal by electromagnetic induction. An electromagnetic force in the axial direction is formed on the metal to impart axial motion to the molten metal in the vicinity of the peripheral wall. At the same time, the axes Oa to Of of the rings 3a to 3f are inclined with respect to the center axis (for example, a perpendicular line) Ov of the solidified shell 4, and the axes Oa to Of of the rings 3a to 3f are solidified shell 4 (or continuous casting). By sequentially shifting the casting mold 2) in the circumferential direction and the axial direction at intervals, the magnetic field entering the solidified shell 4 moves downward in the axial direction while rotating in the circumferential direction. In other words, in the conductive material 1 in the molten state in the vicinity of the solidified shell 4, the magnetic field generated by the axial moving magnetic field generating rings 3a to 3f has a vertical component and a horizontal component due to the inclination of the coil axes Oa to Of. The vertical component acts as a moving magnetic field in the vertical direction (axial direction), while the horizontal component acts as a magnetic field that rotates the horizontal plane in the circumferential direction. For this reason, a spiral flow magnetic field 7 is generated that combines the vertical component and the circumferential rotation component. An electromagnetic force having a vertical component and a rotational component is formed between the spiral moving magnetic field 7 and a current flowing in the molten conductive material such as the molten metal 1 by electromagnetic induction, and the molten metal 1 in the vicinity of the solidified shell is formed in the molten metal 1. Spiral movement is given. In this embodiment, the moving magnetic field is moved in the axial direction from the top to the bottom of the mold 2.

  The above-described embodiment is an example of a preferred embodiment of the present invention, but is not limited thereto, and various modifications can be made without departing from the gist of the present invention. For example, in the present embodiment, the case where the moving direction of the magnetic field and the direction of the electromagnetic force are assumed to be downward has been mainly described, but in some cases, the moving direction of the magnetic field can be set upward. The same stirring effect can be obtained regardless of the direction of movement of the magnetic field, and the upward and downward selection of electromagnetic force is appropriately selected according to the required conditions. Furthermore, in the present embodiment, the coil is arranged around the mold 2, but the present invention is not limited to this. If the molten conductive material starts to solidify and solidifies, electromagnetic stirring is performed. Therefore, as long as it is a region surrounded by the solidified shell 4 and containing the conductive material 1 in a molten state, the region is not limited to the above-described installation location, and is arranged around any location requiring electromagnetic stirring. Also good.

  Further, in this embodiment, electromagnetic stirring is mainly applied in the vicinity of the secondary cooling zone where the molten conductive material 1 flows down and is surrounded by the continuous casting mold 2 and the solidified shell 4 on the downstream side. However, in some cases, electromagnetic stirring is applied to the turn dish or the immersion nozzle portion between the turn dish and the mold, so that the primary crystal can be atomized and homogenized by strong stirring. good.

  In the present embodiment, the moving magnetic field in the axial direction is rotated by rotating the magnetic field by switching the energization using a three-phase AC coil that generates a smooth magnetic field spatial distribution. If it is an AC coil, it can be implemented with a two-phase coil. Furthermore, in the present embodiment, a three-phase AC coil is used as the axially moving magnetic field generating ring 3, but this is not particularly limited, and a permanent magnet is used, and this permanent magnet is used as the center of the mold 2 or the flow. You may make it rotate centering on a center. In this case, the ring-shaped magnets 3a to 3f are inclined with respect to the center axis Oa to Of of the stirring region, that is, the axis Ov of the solidified shell, and the axis Oa to each ring. Of is fixedly connected by a connecting shaft (not shown) in a state where the OF is sequentially shifted in the circumferential direction and the axial direction of the solidified shell, and the inclination and circumferential direction of each ring with respect to the axis Ov of the solidified shell, The magnet is provided to rotate around the solidified shell while maintaining the axial deviation. In this case, the axial movement magnetic field moves in the circumferential direction at the same time only by rotating the magnet. Here, the magnet can be a normal permanent magnet or a high-temperature superconducting magnet composed of a high-temperature superconducting magnet, but preferably a high-temperature superconducting magnet composed of a high-temperature superconducting magnet is used.

  In this embodiment, the molten conductive material to be agitated is exemplified by stainless steel, but depending on the case, cast iron or steel, or non-ferrous metal such as aluminum or copper is continuously cast. Needless to say, it can also be applied. It is also possible to apply the method in which a molten conductive material is continuously molded directly into a molded product having a certain shape while being pulled out by a roller or the like in the vertical direction or in some cases in the horizontal direction while cooling the surroundings. is there.

It is a schematic explanatory drawing which shows an example of embodiment of the coil for electromagnetic stirring of the electromagnetic stirring type continuous casting apparatus concerning this invention. It is the schematic which shows one Embodiment of an electromagnetic stirring type continuous casting apparatus. FIG. 2 is a principle diagram showing a phase relationship of energization of the six coils shown in FIG. 1 and a method of generating magnetic lines when a three-phase AC coil is used as an electromagnetic force generator, and FIG. Sectional drawing shown in the state where it piled up on the axial direction, (B) is a figure which shows the phase difference of a three-phase alternating current coil, (C) is a figure which shows the electrical arrangement | positioning of a three-phase alternating current coil.

Explanation of symbols

1 Molten metal (conductive substance in the molten state)
2 Mold 3 (3a-3f) Axial moving magnetic field generating coil 4 Solidified shell 7 Spiral flow of molten metal

Claims (7)

A molten conductive material is cooled from the periphery with a mold to form a solidified shell, and the molten conductive material is wrapped in the solidified shell and drawn from the mold and cooled in a secondary cooling zone. In the continuous casting method, the molten conductive material moves in the axial direction of the solidified shell with respect to the molten conductive material inside the solidified shell until solidification is completed after the molten conductive material starts to solidify. A plurality of axially moving magnetic fields are applied to each other with an inclination relative to the axis of the solidified shell and sequentially shifted at intervals in the circumferential direction and the axial direction of the solidified shell, and the axially moving magnetic field is applied around the solidified shell. A continuous casting method in which the magnetic stirrer is rotated by rotating. The molten conductive material is cooled from the periphery with a mold to form a solidified shell, and the molten conductive material is drawn from the mold in a state of being wrapped in the solidified shell, and further cooled in the secondary cooling zone. In a continuous casting apparatus to be a molded product, the molten conductive material surrounds the solidified shell in any region or any region until solidification starts and solidification is completed. An axially moving magnetic field generating ring that generates magnetic lines of force in the axial direction of the solidified shell with respect to the conductive material in a state inclines the axis of each ring with respect to the central axis, and the axis of each ring is solidified An electric current in the axial direction is applied to the molten conductive material, which is sequentially shifted at intervals in the circumferential direction and the axial direction of the shell, and surrounded by the solidified shell by the axially moving magnetic field generating ring. Continuous casting apparatus axially traveling magnetic field at the same time a force is created which is characterized in that rotate around the said solidified shell. The electromagnetic stirrer according to claim 2, wherein the axially moving magnetic field generating ring is an electromagnetic coil, and the axially moving magnetic field rotates around the solidified shell when energized. The electromagnetic stirrer according to claim 3, wherein the electromagnetic coil is a three-phase AC coil, and a phase difference of 60 ° is provided between adjacent coils by using a forward winding coil and a reverse winding coil. 3. The electromagnetic wave according to claim 2, wherein the axially moving magnetic field generating ring is a permanent magnet, and the axially moving magnetic field rotates around the solidified shell by rotating the ring itself about the central axis of the flow. Stirring device. The electromagnetic stirrer according to claim 5, wherein the axially moving magnetic field generating ring is a high-temperature superconducting magnet. The electromagnetic stirrer according to any one of claims 2 to 6, wherein the axially moving magnetic field generating ring has its axis shifted by 60 ° in the circumferential direction and makes one turn with six rings.