JPH08197196A - Molten metal flow control device - Google Patents

Abstract

(57) [Summary] [Purpose] To effectively drive the molten metal upper layer near the mold piece of continuous casting mold. An electromagnet core (10) having a plurality of slots extending in the x direction and distributed in the y direction, the tips of the teeth between the slots facing the upper surface of the molten metal in the mold and within the mold opening; A plurality of electric coils (1Aa ~), which are inserted and attached to the electromagnet core (10) with a body winding that circulates the base portion (10b) of each slot of the electromagnet core (10), and a part of which is located above the upper end surface of the mold. 2Ca); and an energizing means (20F1) for applying an alternating voltage having a phase difference for applying a thrust force along the slot arrangement direction y to the molten metal to each of the electric coils;
Is provided.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a flow control device for adjusting the flow rate of molten metal in a mold.

[0002]

2. Description of the Related Art For example, in continuous casting, molten steel is poured into a mold from a tundish, and in the mold, the molten steel is drawn out while gradually cooling from the wall surface of the mold. If the temperatures on the wall surfaces of the mold having the same height are not uniform, surface cracks and shell breakages are likely to occur. In order to improve this, conventionally, a linear motor is used to drive the molten steel to flow along the wall surface of the mold in the mold (for example, JP-A 1-228645).

FIG. 8 (a) shows a vertical sectional view of the mold.
FIG. 8B shows a plane looking down on the upper surface (meniscus) of the molten steel in the mold from above the mold. Molten steel flows from the nozzle 30 into the mold as shown by the solid arrow in (a), and a molten steel flow is generated in the direction of the mold short piece and slightly downward, which hits the mold short piece and part of it is upward and the other is downward. Flowing. In the meniscus, the molten steel flow that flows upward generates a superficial flow toward the nozzle 30, as indicated by a solid arrow in FIG. This superficial flow easily entrains powder on the meniscus. On the other hand, when molten steel changes to solid, CO
Such as gas (air bubbles) is generated. In addition, if the molten steel stays on a part of the inner surface of the mold, the powder is likely to remain on the molten steel, and further seizure that causes breakout is likely to occur. In order to prevent these, it is preferable to form stable rectification on the surface layer as shown by the double-dotted chain line arrow in FIG.

With respect to the surface flow caused by the molten steel flow, as shown in FIG. 10 (b), the electromagnetic driving force in the direction indicated by the dotted arrow is applied to the molten steel in the linear motors 3RF and 3RL along the mold long piece. Given that a circulating flow along the mold inner wall 1 as shown by the solid arrow in FIG. 10 (c) can be generated in the surface layer of the molten steel, this circulating flow is indicated by a two-dot chain line in FIG. 10 (b) in the surface layer portion. A circulating flow indicated by an arrow will be stably generated at a constant speed, which promotes the floating of bubbles,
The powder is not entrained in the molten steel, the inner surface of the mold near the surface layer is wiped clean, and the molten steel does not stay.

By the way, a coil end type in which one side of a tortoise-shaped (hexagonal) electric coil is inserted into each slot cut in the electromagnet core has been commonly used as an electromagnet of a linear motor. There is. That is,
For example, in the case of a three-phase linear motor, No. The slot numbers are numbered 1, 2, 3 ,. If the teeth between Nos. 1 and 2 are numbered No. 2, one of the pair of long sides of the No. 1 tortoise-shaped electric coil facing each other is slot No. 2. 1 to the other slot No.
Insert into 3 and orbit two teeth (No.2,3) between slots,
One of the pair of long sides facing each other of the second electric coil is slot No. 2 to the other slot No. No. 3, 4 teeth inserted between the slots, and one of the pair of long sides of the No. 3 electric coil facing each other is inserted into the slot No. 4. Three
To the other slot No. 5 and insert the teeth between the slots (N
o.4,5) Each electric coil is attached to the electromagnet core in such a manner that two coils are wound. Such a coil end system has a large power factor and can use a high-frequency power source, so that the power source capacity can be reduced. That is, the equipment cost is low.

[0006]

However, in the above-mentioned coil end system, the coil end protruding from the electromagnet core is large, the protruding length in the direction x in which the slots extend is long, and the outside of the core in the direction y in which the slots are distributed is large. The length (sum of two short sides) is long. In addition, for example, in the above example, the slot number. To the outside (x direction) of the side edge of 3
A large amount of coil ends exist outside the side ends of the electromagnet core, such that the short sides (coil ends) of the second and third electric coils overlap and project, which greatly increases the overall width of the linear motor. ing.

However, the width of the mold (short side length)
Is relatively narrow, the nozzle for injecting molten steel into the mold is located substantially at the center of the mold opening, and the space between the tundish above the nozzle and the top of the mold is limited so that the coil There is a problem that it is difficult to dispose the end type linear motor above the mold opening. When the linear motor is downsized, the thrust applied to the molten metal becomes small. In order to give a large thrust, the mold must be modified and the equipment cost becomes large.

An object of the present invention is to effectively apply a thrust to the molten metal in the mold from the side of the opening of the mold.

[0009]

The molten metal flow control apparatus of the present invention has a plurality of slots extending in the x direction and distributed in the y direction, and the tips of the teeth between the slots are the upper surface of the molten metal in the mold. An electromagnet core (10) opposite to and in the mold opening;
A plurality of electric coils, each of which is inserted into the slot and attached to the electromagnet core (10) by a body winding that circulates around the base portion (10b) of each slot of the electromagnet core (10), a part of which is located above the upper end surface of the mold ( 1Aa to 2Ca); and an energizing means (20F1) for applying an AC voltage having a phase difference for applying thrust to the molten metal along the slot arrangement direction y to each of the electric coils;
Is provided. In addition, in order to facilitate understanding, symbols in the parentheses that correspond to the elements shown in the drawings and described later are added for reference.

A preferred embodiment of the present invention is a mold comprising a pair of long sides (5F, 5L) extending in the y direction and facing each other and a pair of short sides (3R, 3L) extending in the x direction and facing each other. One of a pair of long sides
Molten metal in a mold having a plurality of first sets of slots distributed along (5F) and extending in the x direction, and the tips of the teeth between the slots being close to one of the pair of short sides (3R) A first electromagnet core (10) facing the upper surface and within the mold opening; inserted in the first set of slots and wrapped around the base (10b) of each slot of the first electromagnet core (10) with a body winding 1. A plurality of first sets of electric coils (1Aa to 2Ca) mounted on the electromagnet core (10) and partially located above the upper end surface of the one long side (5F); An AC voltage having a phase difference for applying a thrust force along the arrangement direction y to the molten metal, the first set of electric coils
First energizing means (20F1) applied to each of (1Aa to 2Ca);
It has a plurality of second sets of slots distributed along the other (5L) of the pair of long sides and extending in the x direction, and the tips of the teeth between the slots are on the other (3L) of the pair of short sides. A second electromagnet core (2 facing the upper surface of the molten metal in the mold at a close position and located in the mold opening)
0); inserted in the second set of slots, the second electromagnet core (20)
It is attached to the second electromagnet core (20) by a body winding that circulates around the base portion (20b) of each slot, and a part of the other long side (5L)
A plurality of second sets of electric coils (4Ab to 5Cb) located above the upper end surface of the second set, and the array direction y of the second set of slots.
A second energizing means (20L2) for applying an AC voltage having a phase difference for applying a thrust force along the wire to the molten metal to each of the second set of electric coils (4Ab to 5Cb).

[0011]

[Operation] A plurality of electric coils (1
(Aa ~ 2Ca) is a body winding, so multiple electric coils (1Aa
.About.2Ca) are distributed in the y-direction so as to go around the same y-axis, and each electric coil is inserted into only one slot and has substantially no coil end extending in the y-direction. As a result, the coil protrusion length outward (x direction) from the side end surface of the tooth between the slots is extremely small, and the overall width of the linear motor is small.
The tips of the teeth between the slots of the electromagnet core (10) can be inserted into the mold (mold) opening to bring them closer to the surface of the molten metal near the inner wall surface of the mold, which effectively gives thrust to the molten metal. it can. This can be done in existing modes without any particular improvement.

In addition, a part of the electric coil is brought close to the mold piece so that a part of the electric coil is located above the upper end surface of the mold, and the linear motor is moved.
Since (10 + 1Aa ~ 2Ca) is installed, the thrust along the inner wall surface of the mold is positively given to the molten metal, and the flow of the molten metal by this promotes the floating of bubbles in the molten metal, Eliminates powder entrainment, wipes the inner surface of the mold near the surface cleanly, and eliminates retention of molten metal. When the molten metal stays on the inner surface of the mold, the cooling effect of the mold strongly acts, the solidification of the staying portion rapidly progresses, and the solidified metal may adhere to the inner surface of the mold, causing breakout.

The above-described preferred embodiment of the present invention includes two sets of linear motors (10 + 1Aa-2Ca / 20 + 4Ab-5Cb) at diagonal positions of the mold opening (quadrilateral) along the long side of the mold. Moreover, since some of these electric coils are installed very close to the long side so that they are above the upper end face of the long side, the surface layer flow on the surface of the molten metal can be effectively arranged. For example, a thrust force (indicated by a broken line arrow in FIG. 1) in a direction opposite to the surface flow of the molten metal generated by the protruding flow of the injection nozzle (30) can be applied to the molten metal, in which case (c) of FIG. As a result, a relatively regular surface layer flow is formed, and as a result, a stable circulating flow at a relatively constant velocity is obtained as indicated by the two-dot chain line arrow in FIG. As a result, the floating of bubbles is promoted, the powder is not caught in the molten metal, the inner surface of the mold near the surface layer is wiped clean, and the molten metal does not stay. Linear motor (10 + 1Aa to 2Ca / 20
Since there is only one pair of + 4Ab to 5Cb) and it exists only in one of the two diagonal directions of the quadrangular space, there is a lot of empty space above the molten metal and other devices or sensors can be easily arranged. . Since only one pair of energizing circuits is required, power consumption is small and energization control is simple. Therefore, equipment costs and maintenance costs are reduced.

Other objects and features of the present invention will become apparent from the following description of embodiments with reference to the drawings.

[0015]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows the arrangement of linear motors according to an embodiment of the present invention. In the figure, 5F and 5L are the first and second long pieces of the continuous casting mold, and 6R and 6L are the first and second long pieces.
Molten steel is injected into the space surrounded by these through the injection nozzle 30 from the front side to the back side of the paper surface of FIG. 1 (from the upper side to the lower side in the vertical direction z). Each side (5F, 5
L, 6R, 6L) is a copper plate 1F, 1L, 3R, 3L backed by a non-magnetic stainless steel plate 2F, 2L, 4R, 4L. A stainless cover plate is placed on the upper end surface of each side of the mold as shown in FIG. 3, but the illustration is omitted in FIGS. 1 and 2.

In this embodiment, the molds (5F, 5L, 6
R, 6L) molten steel in 3 phase linear motor type 5L long piece
First and second electromagnets facing the upper surface of the molten steel in a continuous casting mold (5F, 5L, 6R, 6L) for driving right to left along the direction (from + y to -y direction). Core 1
0 and 20 are arranged diagonally around the injection nozzle 30.

2A shows an enlarged vertical section of the first electromagnet core 10 (enlarged section 2A-2A in FIG. 1), and FIG. 3 shows an enlarged transverse section of the electromagnet core 10 (FIG. 1). Of 3
A-3A line enlarged cross section) is shown. In these drawings, the small numbers between the dimension leader lines (chain lines) are the dimension values (mm).
Indicates. The first linear motor including the first electromagnet core 10 and the second linear motor including the second electromagnet core 20 have the same size and the same electric rating, and the nozzle 30 at the center position of the mold opening is They are arranged symmetrically with respect to each other.

With reference to FIGS. 1 to 3, in this embodiment, the electromagnet core 10 is long in the y direction, and the longitudinal direction y
Is a stack of thin steel plates with flat plate surfaces in which six notches for slots are formed at equal pitches, and there are six slots, and each of the slots has an electric coil 1Aa-2.
Ca is inserted. Although the electromagnet core 10 and the electric coils 1Aa to 2Ca are cooled and covered with a heat-resistant cover, the cooling structure and the cover are not shown. The electromagnet core 10 has a comb shape having slots extending in the x direction on the lower surface, electric coils are inserted in the respective slots, teeth between the slots are magnetic poles, and lower end surfaces thereof are continuous casting molds (5F, 5L, 6R, 6L) facing the upper surface of the molten steel. The coil ends of the electric coils 1Aa to 2Ca protruding from the electromagnet core 10 in the x direction are the copper plates 1.
In the space in the upper part of F (+ z direction), the direction is turned upward by about 90 degrees, and it passes through the upper plane of the electromagnet core 10. That is, the electric coils 1Aa to 2Ca are “wound around” the electromagnet core 10.

In this embodiment, the electric coils 1Aa to 2C are used.
An electromagnet core 10 having a height (z) of 150 mm in the inner space of a
After passing through the electric coils 1Aa to 2Ca, one side of the electric coils 1Aa to 2Ca is pushed into each slot. Therefore, the width of the inner space of the electric coils 1Aa to 2Ca in the height direction z is 150 mm in this embodiment, and the slot depth (z ) Is 75 mm, a 75 mm gap is created between the upper side of the electric coil and the back surface (top surface) of the core 10 after the electric coil is pushed into the slot. The auxiliary core 10a in which rectangular thin steel plates are laminated is inserted into this void. Both the electromagnet core 10 and the auxiliary core 10a also have a cooling fluid flow path, to which a refrigerant pipe is connected, but they are not shown.

Since the electric coils 1Aa to 2Ca are wound around the electromagnet core 10, each electric coil is distributed in the y direction only by the width of the slot in the y direction, which is similar to that of a conventional coil end type linear motor. In addition, one electric coil does not extend in the y direction for several slots, so that the protruding length of the outer side (x direction) of the electromagnet core 10 is short and the width of the linear motor (10 + 1Aa to 2Ca) in the x direction is narrow. . As a result, as shown in FIG. 3, by inserting the tips of the teeth between the slots of the electromagnet core 10 into the mold opening and placing a part of the electric coil above the mold wall 5F, the electromagnet core 1
0 can be placed very close to the mold side 5F. That is, since the width of the linear motor in the x direction is narrow, it is possible to dispose the linear motor even in a mold having a narrow short side width, and further, it is possible to effectively thrust the molten steel near the inner surface of the mold side. The electromagnet core 10 can be placed in the immediate vicinity of the mold side to provide

FIG. 2B shows an enlarged vertical section of the second electromagnet core 20 (enlarged section 2B-2B in FIG. 1). The electromagnet core 20 also has a structure similar to that of 10, and is positioned with respect to the long side 5L and the short side 6L, similar to the positional relationship of the first electromagnet core 10 with respect to the long side 5F and the short side 6R.

FIG. 4 shows the connection between the electric coils 1Aa to 2Ca and 4Ab to 5Cb shown in FIGS. 2A and 2B and the connection with the power supply circuit. This connection has 2 poles (N = 2)
The electric coil is energized with a three-phase alternating current (M = 3). For example, the electric coils 1Aa to 2Ca are represented by u, V, w, U, v, W in this order in FIG. The "U" represents the U-phase positive phase energization of the three-phase alternating current (the energization as it is), and the "u" represents the U-phase reverse phase energization (the phase is energized by 180 degrees from the U phase). , The U-phase is applied to the winding start end, while the electric coil "u"
Means that the U phase is applied to the end of the winding.
Similarly, “V” is the positive phase current of the V phase of the three-phase alternating current,
Indicates V-phase reverse-phase conduction, "W" indicates W-phase positive-phase conduction of three-phase AC, and "w" indicates W-phase reverse-phase conduction. Terminals U11, V11 and W11 shown in FIG.
2Ca is a power supply connection terminal, and terminals U12, V12, and W12 are power supply connection terminals for the electric coils 4Ab to 5Cb.

FIG. 5 shows a power supply circuit 20F1 for supplying a three-phase alternating current to the electric coils 1Aa to 2Ca. 3-phase AC power supply (3
Phase power line) 21 is a thyristor bridge 2 for DC rectification
2A1 is connected, and its output (pulsating current) is smoothed by the inductor 25A1 and the capacitor 26A1. The smoothed DC voltage is applied to the power transistor bridge 27A1 for forming a three-phase AC, and the U-phase of the three-phase AC output from the power-transistor bridge 27A1 is supplied to the power connection terminal U11 shown in FIG. , And W phase is the power supply connection terminal W11
Is applied to

For the electric coils 1Aa to 2Ca, the coil voltage command value VdcA1 for generating the thrust indicated by the dotted arrow in FIG. 10B is given to the phase angle α calculator 24A1, and the phase angle α calculator 24A1 commands The conduction phase angle α (thyristor trigger-phase angle) corresponding to the value VdcA1 is calculated, and a signal representing this is given to the gate driver 23A1. Gee
The driver 23A1 starts phase counting of the thyristor of each phase from the zero-cross point of each phase and triggers conduction at the phase angle α. As a result, the transistor bridge 27
A direct current voltage indicated by the command value VdcA1 is applied to A1.

On the other hand, the three-phase signal generator 31A1 has a frequency designated by the frequency command value Fdc (50H in this embodiment).
z), a constant voltage three-phase AC signal is generated, and the comparator 29A
Give to one. The comparator 29A1 also includes a triangular wave generator 3
0A1 gives a constant voltage triangular wave of 3 KHz. Comparator 2
9A1 is a high level H (transistor on) when the U-phase signal has a positive level and is higher than the level of the triangular wave provided by the triangular wave generator 30A1, and a low level L (transistor off) when it is less than the level of the triangular wave. Is output to the gate driver 28A1 to the positive section of the U-phase (to the U-phase positive voltage output transistor), and when the U-phase signal is at a negative level, it is below the level of the triangular wave provided by the triangular wave generator 30A1. When the level is high level H, and when the level of the triangular wave is exceeded, a low level L signal is sent to the negative section of the U phase (U
Gate driver 2 to the phase negative voltage output transistor)
Output to 8A1. The same applies to the V-phase signal and the W-phase signal. The gate driver 28A1 is provided for each of these phases,
Each transistor of the transistor bridge 27A1 is turned on and off in response to a signal addressed to the positive and negative sections. As a result, a U-phase voltage of three-phase AC is output to the power supply connection terminal U11, a similar V-phase voltage is output to the power supply connection terminal V11, and a similar W-phase voltage is output to the power supply connection terminal W11. The level between the upper peak and the lower peak of these voltages is determined by the coil voltage command value VdcA1. In this embodiment, the frequency of the three-phase voltage is 50 Hz according to the frequency command value Fdc.
Is. That is, a three-phase AC voltage of 50 Hz having a peak voltage value (thrust) designated by the coil voltage command value VdcA1 is applied to the electric coils 1Aa to 2Ca shown in FIGS.

FIG. 6 shows a power supply circuit 20L2 for supplying a three-phase alternating current to the electric coils 4Ab to 5Cb. This power circuit 20
The configuration of L2 is the same as that of 20F1 described above, but the coil voltage command value (VdcB2) is different.

That is, the coil voltage command value VdcB2 that causes the electric coils 4Ab to 5Cb to generate the thrust indicated by the dotted arrow in FIG. 10B is given to the phase angle α calculator 24B2. The coil voltage command value VdcA1 (FIG. 5) and the coil voltage command value VdcB2 (FIG. 6) are supplied to the power supply circuits 20F1 and 20L2 by the computer 43 shown in FIG.
To give to.

FIG. 7 shows the mold short pieces 6L and 6 shown in FIG.
The back of R is shown. In these short pieces 6L, 6R, thermocouples S31 to S3n and S41 to S4n are arranged at equal intervals in one row in the slab drawing direction (height direction z; vertical direction), and each thermocouple is The temperature of the inside of the copper plate (on the surface that contacts molten steel) is detected by penetrating the backing stainless steel plate. The signal processing circuits 41A and 41B generate an analog signal (detection signal) representing the temperature detected by the thermocouple and apply it to the analog gate 42.

The computer 43 is an analog gate 42.
To control thermocouples S31 to S3n and S41 to S4.
n detection signals are sequentially selected, A / D converted and read,
By the high temperature value extraction process 44, the highest temperature value Tm1L1 and the next highest temperature value Tm2L1 among the detection temperatures of the thermocouples S31 to S3n are extracted, and the highest temperature value Tm1R1 of the detection temperatures of the thermocouples S41 to S4n. And the next highest temperature value Tm2R1. Then, the representative temperature (Tm1L1-Tm2L1) × 0.7 + TM2L1 of the short piece 6L is calculated, the representative temperature (Tm1R1-Tm2R1) × 0.7 + TM2R1 of the short piece 6R is calculated, and the difference between them, that is, the representative between the short pieces 6L and 6R. Temperature difference (Tm1L1-Tm2L1) × 0.7 + TM2L1-(Tm1R1-Tm2R1) × 0.7-T
When M2R1 is calculated and is a positive value (0 or more) (the temperature of the short piece 6R is higher), VdcA1 = representative temperature difference ×
A (A is a coefficient) is calculated, and VdcB2 = B-VdcA
Calculate 1. When the representative temperature difference is a negative value (the temperature of the short piece 15L is higher), VdcB2 = −representative temperature difference ×
A is calculated, and VdcA1 = B−VdcB2 is calculated.

VdcA1 is an electric coil 1A on the short piece 6R side.
a to 2Ca (FIG. 4) is a current level (thrust) command value, and VdcB2 is an electric coil 4Ab to 5B on the short piece 6L side.
It is a current level (thrust) with respect to Cb (FIG. 4). These command values are applied to the electric coils of the electric coils 1Aa to 2Ca when the representative temperature difference is a positive value (the temperature of the short piece 6R is higher; the unbalanced surface layer flow shown in b of FIG. 11 is estimated by the protruding flow). By increasing the level of the three-phase alternating current to be applied and applying a strong thrust (dotted line arrow in FIG. 1 and FIG. 9), the electric coil 4A
When the representative temperature difference is a negative value (the temperature of the short piece 6L is higher), the phase AC current level flowing in b to 5Cb is made smaller, and conversely, when the representative temperature difference is negative (the temperature of the short piece 6L is higher), the electric current is supplied to the electric coils 4Ab to 5Cb
This means increasing the phase AC current level to apply a strong thrust, and decreasing the level of the three-phase AC current flowing through the electric coils 1Aa to 2Ca to weaken the thrust.

When the molten steel flow (protruding flow shown in FIG. 8a) flowing from the nozzle 30 into the mold is substantially symmetrical with respect to the nozzle 30, the temperatures of the short pieces 6R and 6L are substantially the same, and the surface layer flow is shown in FIG. 9B and FIG. 9A, the nozzles 30 are symmetrical with respect to the nozzle 30, as shown by the solid line arrow. In this case, VdcA1 = VdcB2, and the electric coils 1Aa to 2Ca on the short piece 6R side and the short piece 6L side. The electric current levels of the electric coils 4Ab to 5Cb are substantially equal to each other, and the first electromagnet core 10 and the second electromagnet core 20 have substantially equal strengths, as shown by dotted arrows in FIGS. 1 and 8B. , Thrust is applied in the opposite direction to molten steel. As a result, the actual surface layer flow of the molten steel has a shape in which the solid line arrow in (c) of FIG. 10 is changed in the opposite direction, and the circulating flow shown by the two-dot chain line arrow in (b) of FIG. 8 is provided. As a result, the floating of the bubbles is promoted, the powder is not caught in the molten steel, the inner surface of the mold near the surface layer is wiped clean, and the molten steel does not stay.
Uniform temperature distribution of molten steel in the mold.

As shown in FIG. 11A, when the protruding flow toward the short piece 6R is strong and the protruding flow toward the short piece 6L is weak, the temperature of the short piece 6R rises and the temperature of the short piece 6L decreases, and the surface layer flow 11B, the superficial flow between the nozzle 30 and the short piece 6R is strong and the superficial flow between the nozzle 30 and the short piece 6L is weak, as indicated by the solid arrow in FIG. 11B. In this case, VdcA1> VdcB2 Therefore, the energization level of the electric coils 1Aa to 2Ca on the short piece 6R side is high, and the short piece 6L is
The energization level of the side electric coils 4Ab to 5Cb becomes low, and the first electromagnet core 10 gives a strong thrust and the second electromagnet core 20 gives a weak thrust to the molten steel. As a result, the first electromagnet core 10 gives a strong thrust to the molten steel, and the second electromagnet core 20 gives a weak thrust to the molten steel, as shown by a dotted arrow in FIG. 9B. As a result, a circulating flow indicated by a two-dot chain line arrow in FIG. In this case, the circulating flow is high speed on the high temperature short piece 6R side and low speed on the low temperature short piece 6L side,
Since it is a circulation flow that draws a loop, no eddy current is generated. Short piece 6
The high temperature molten steel on the R side is conveyed to the low temperature short piece 6L side to reduce the temperature difference. This circulation flow promotes the floating of bubbles,
The powder is not entrained in the molten steel, the inner surface of the mold near the surface layer is wiped clean, and the molten steel does not stay. Uniform temperature distribution of molten steel in the mold.

On the contrary, the protruding flow toward the short piece 6R is weak,
When the projecting flow toward the short piece 6L becomes strong, the temperature of the short piece 6R decreases and the temperature of the short piece 6L rises, and the surface layer flow causes the nozzle 3 to flow.
The surface flow between 0 and the short piece 6R is weak, and the surface flow between the nozzle 30 and the short piece 6L is strong. In this case, VdcA
1 <VdcB2, and the electric coil 1Aa on the short piece 6R side
The energization level of ~ 2Ca is low, the energization level of the electric coils 4Ab-5Cb on the short piece 6L side is high, and the first electromagnet core 10 gives a weak thrust and the second electromagnet core 20 gives a strong thrust to the molten steel. As a result, the first electromagnet core 10 gives a weak thrust to the molten steel and the second electromagnet core 20 gives a strong thrust to the molten steel, as shown by a dotted arrow in (c) of FIG. 9. This allows
The circulating flow indicated by the two-dot chain line arrow in FIG.
In this case, this circulation flow is low speed on the side of the low temperature short piece 6R,
Although it is high speed on the side of the high temperature short piece 6L, it does not generate a vortex because it is a circulating flow that draws a loop. The high temperature molten steel on the short piece 6L side is conveyed to the low temperature short piece 6R side to reduce the temperature difference. By this circulating flow, the floating of bubbles is promoted, the powder is not entrained in the molten steel, the inner surface of the mold near the surface layer is wiped clean, and the molten steel does not stay. Uniform temperature distribution of molten steel in the mold.

In the above-mentioned embodiment, the temperature of the short pieces 6R, 6L is detected by the thermocouple to detect the strength of the surface layer flow (flow velocity) corresponding to the strength of the protruding flow from the injection nozzle 30 into the mold. Correspondingly stable circulation flow (two-dot chain line arrow in Fig. 8b)
Although the electromagnetic thrust for generating is applied to the molten steel by the first and second electromagnet cores 10 and 20, for example, the velocity Vs of the surface layer flow at the position of Vspa in FIG.
The velocity Vsb of the surface flow at the positions of a and Vspb is detected, and the current level instruction values VdcA1 and VdcB2 are respectively set to V
The value may be inversely proportional to sa and Vsb.
In the present invention, since only one pair of electromagnets are diagonally arranged above the mold space, the flow velocity sensor is arranged to detect the flow velocity at the positions Vspa and Vspb, or the position V
It is easy to move up and down with respect to spa and Vspb.

[Brief description of drawings]

FIG. 1 is a plan view showing an arrangement of magnetic poles and electric coils above the surface of molten steel of a continuous casting mold according to an embodiment of the present invention.

FIG. 2 is an enlarged vertical sectional view of electromagnet cores 10 and 20 shown in FIG.

3 is an enlarged cross-sectional view of electromagnet cores 10 and 20 shown in FIG.

4 is an electric circuit diagram showing a connection mode of the electric coil shown in FIG. 2 and a connection with a power supply circuit.

5 is an electric circuit diagram showing a power supply circuit for applying a three-phase AC voltage to the electric coils 1Aa to 2Ca shown in FIG.

6 is an electric circuit diagram showing a power supply circuit for applying a three-phase alternating current to the electric coils 4Ab to 5Cb shown in FIG.

7 is a block diagram showing the electric circuits connected to the backs of the short pieces 6L and 6R of the casting mold shown in FIG. 1 and the thermocouples provided therein.

FIG. 8 (a) is a template (5F, 5L, 6 shown in FIG.
(F, 6R) is a vertical sectional view, and (b) is a horizontal sectional view.

9 (a) is a plan view showing the upper surface of the molten steel in the mold, FIG.
(B) And (c) is a top view which shows the surface layer flow (dotted line arrow) induced in the meniscus of molten steel in a mold by electromagnet ko, 10.

FIG. 10 (a) is a plan view showing a superficial flow caused by molten steel injection from an injection nozzle in a meniscus of molten steel in a mold, and FIG. 10 (b) is a superficial flow intended to occur by two conventional linear motors. Is a plan view indicated by a dotted arrow, and (c) is a plan view showing a vector sum of the surface layer flow generated by the molten steel injection from the injection nozzle and the surface layer flow generated by the thrusts of the two linear motors by a solid arrow.

11A is a cross-sectional view of the molten steel in the mold, and FIG. 11B is a plan view showing a superficial flow in the meniscus of the molten steel in the mold.

[Explanation of symbols]

1: Inner wall of mold 1F, 1L, 3R, 3
L: Copper plate 2F, 2L, 4R, 4L: Non-magnetic stainless plate 5F, 5L: Long piece 6R, 6L: Short piece 10, 20: Electromagnetic core 10a, 20a: Auxiliary core 10b, 20b: Base portion 19: Outlet port 30: Injection nozzle 20F1, 20L2:
Power supply circuit PW: Powder 1Aa, 1Ba, 1Ca, 2Aa, 2Ba, 2Ca: Electric coil 4Ab, 4Bb, 4Cb, 5Ab, 5Bb, 5Cb: Electric coil U11, V11, W11 / U12, V12, W12: Power supply connection terminal

Claims (3)

[Claims] 1. An electromagnet core having a plurality of slots extending in the x-direction and distributed in the y-direction, the tips of the teeth between the slots facing the upper surface of the molten metal in the mold and within the mold opening; A plurality of electric coils, which are attached to the electromagnet core by a body winding that circulates around the base of each slot of the electromagnet core, and a part of which is located above the upper end surface of the mold; and the thrust force along the slot arrangement direction y. A molten metal flow control device, comprising: energizing means for applying an AC voltage having a phase difference to the metal to each of the electric coils. 2. A plurality of slots distributed along the long side and extending in the x direction of a mold including a pair of long sides extending in the y direction and facing each other and a pair of short sides extending in the x direction and facing each other. An electromagnet core having tips of teeth between slots facing the upper surface of the molten metal in the mold and within the mold opening; the electromagnet core being inserted into the slot and wound around the base of each slot of the electromagnet core. A plurality of electric coils mounted on the upper part of the long side of the mold, and an AC voltage having a phase difference for applying thrust to the molten metal along the slot arrangement direction y. A molten metal flow control device comprising: an energizing means for applying to each of the. 3. A mold having a pair of long sides extending in the y direction and facing each other and a pair of short sides extending in the x direction and facing each other, and distributed along one of the pair of long sides in the x direction. A first electromagnet having a plurality of first sets of slots extending therein, the tips of teeth between the slots facing the upper surface of the molten metal in the mold at a position close to one of the pair of short sides and within the mold opening. Core; inserted in the first set of slots and attached to the first electromagnet core by a body winding that circulates around the base of each slot of the first electromagnet core, and a part thereof is located above the upper end surface of the one long side, A plurality of first
A pair of electric coils; a first energizing means for applying an AC voltage having a phase difference for applying a thrust force along the arrangement direction y of the slots of the first set to the molten metal to each of the electric coils of the first set; It has a plurality of second sets of slots distributed along the other of the long sides and extending in the x direction, and the tips of the teeth between the slots are on the upper surface of the molten metal in the mold at a position near the other of the pair of short sides. A second electromagnet core opposite and within the mold opening; a second
A plurality of first electromagnet cores, each of which is inserted into a set of slots and is wound around the base of each slot of the second electromagnet core, and is attached to the second electromagnet core by a part of which is located above the upper end surface of the other long side. Two sets of electric coils; and a second energizing means for applying an alternating voltage having a phase difference for applying thrust to the molten metal along the array direction y of the second set of slots to each of the second sets of electric coils; A molten metal flow control device.