JP7119684B2 - continuous casting machine - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a technique for braking molten metal flow in a mold by using a static magnetic field in continuous casting of molten metal such as molten steel.

Melting into a mold in continuous casting of molten metal such as molten steel (including high-alloy steel in which the total content of alloying elements other than iron such as chromium and nickel exceeds 50%; the same shall apply hereinafter) A method using a refractory submerged nozzle is widely used to supply metal.

A submerged nozzle that supplies molten metal to a mold with a large rectangular ratio (wide width) such as continuous casting of slabs is a two-hole nozzle with two discharge holes drilled from the center of the mold width direction toward both short sides of the mold. is common.

In a slab continuous caster, which has a thinner slab thickness than a bloom continuous caster and is capable of high-speed casting, the molten metal flow is normally discharged obliquely downward from the two-hole nozzle, and is divided into upper and lower parts near the short side of the mold. It forms an ascending flow along the short side and a descending flow along the short side. Under high-speed casting conditions, the discharge flow from the submerged nozzle melts the solidified shell on the short side and causes breakout, and the rising flow along the short side disturbs the surface of the molten steel and deteriorates the surface quality of the slab. In addition, the downward flow along the short side brings non-metallic inclusions deep into the slab and deteriorates the internal quality of the slab. For the purpose of preventing these adverse effects, a technique has been applied in which a static magnetic field is used to brake the discharge flow from the submerged nozzle. A static magnetic field can be obtained by using a permanent magnet, but an electromagnet in which a coil is wound around an iron core and energized is widely used.

For example, as disclosed in FIG. 6 of Patent Document 1, a technique is known in which the left and right electromagnetic brake iron core and coil generate static magnetic fields with opposite polarities. Alternatively, as disclosed in Patent Document 2, there is known a technique of generating a magnetic field of the same polarity over the entire mold width direction.

JP-A-62-254954 JP-A-9-285854

However, sufficient research has been conducted so far on the technology that captures the characteristics of the different magnetic field distributions of the opposite polarity and the same polarity and uses them according to the casting conditions, and the arrangement of the electromagnetic brake iron core that makes it possible. not established. Therefore, it has been difficult to perform a continuous casting operation that achieves both high productivity and high quality at a high level.

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a continuous casting machine capable of performing a continuous casting operation that achieves both high productivity and high quality at a high level.

The present inventors have studied in detail the effect of the difference in magnetic field distribution on the in-mold flow and slab quality. As a result, the following new knowledge was obtained and the present invention was completed.

First, in the case of an electromagnetic brake that generates a magnetic field of the same polarity over the width of the mold, a braking force is also generated on the molten metal flow inside the immersion nozzle. Since the descending flow inside the submerged nozzle generally has the highest flow velocity in the mold, the eddy current that produces the electromagnetic braking force is also large.

At this time, since the direction of the magnetic flux of the static magnetic field is the thickness direction of the mold and the direction of the downward flow in the submerged nozzle is the vertical direction, the direction of the generated eddy current is the width direction of the mold. That is, the eddy current generated in the submerged nozzle flows in the mold width direction so as to penetrate the left and right discharge holes. For convenience of explanation, assuming that the eddy current in the submerged nozzle flows from the left discharge hole toward the right discharge hole, the eddy current exiting the right discharge hole is It creates a current loop that flows through the surrounding molten metal in the mold and returns to the left discharge hole. Due to the nature of the eddy current to form a current loop, an electromagnetic force acting against the flow also acts around the flow that should be damped. This incidental braking force creates a flow around the flow to be braked and in opposition to that flow. This countercurrent is called an electromagnetic countercurrent here.

Normally, in an electromagnetic brake using a static magnetic field, eddy currents and braking force are generated according to the flow velocity. As a result, the flow velocity of the molten metal decreases and the eddy current becomes smaller. does not occur in excess.

In the case of an electromagnetic brake that generates a magnetic field of the same polarity over the width of the mold, eddy currents and braking force are also generated in the downward flow in the submerged nozzle, as described above. However, even with the braking force, the downward flow velocity in the submerged nozzle is maintained at a magnitude corresponding to the throughput determined by the mold size and casting speed. It uses the molten metal head in the tundish or potential energy to maintain it. In this state, the potential energy of the molten metal in the tundish is used to generate eddy current in the submerged nozzle. Such conditions produce excessive braking forces and electromagnetic countercurrents.

As a result, in the case of an electromagnetic brake that generates a magnetic field of the same polarity across the width of the mold, the discharge flow from the submerged nozzle is completely repelled by the electromagnetic brake, and the discharge flow and the downward flow in the submerged nozzle , creating an upward flow toward the hot water surface.

This ascending flow favorably floats non-metallic inclusions and improves the quality of the slab's interior, while causing ripples in the surface of the slab and deteriorating the surface quality of the slab. Fluctuations in the molten metal surface caused by an upward flow are conspicuous during high-speed casting where the casting speed is high.

That is, the electromagnetic brake, which generates a magnetic field of the same polarity over the width of the mold, promotes the floating and removal of non-metallic inclusions under conditions where the casting speed is relatively low, and improves the internal quality of the slab. While advantageous, it suffers from the problem of poor surface quality during high speed casting.

Next, in the case of an electromagnetic brake in which the left and right electromagnetic coils generate static magnetic fields with opposite polarities, the center of the mold width, that is, the position of the immersion nozzle, which is equidistant from the left and right electromagnetic coils, becomes the magnetic field interference area. Therefore, almost no braking force is generated in the downward flow in the submerged nozzle, and eddy currents and accompanying braking forces are generated in the left and right discharge flows, respectively. In this case also, the incidental braking force generated around the discharge flow is limited, although not zero, due to the nature of the eddy current forming a loop. Slow down without being bounced back.

Due to such characteristics, in the case of an electromagnetic brake in which the left and right electromagnetic coils generate static magnetic fields with opposite polarities, the molten metal surface is not greatly disturbed even during high-speed casting, and deterioration of the slab surface quality is suppressed. can. On the other hand, the fact that the ascending flow toward the surface of the molten steel is weak is disadvantageous for floating removal of non-metallic inclusions.

On the other hand, in the case of an electromagnetic brake in which the left and right electromagnetic coils generate static magnetic fields with opposite polarities, if the electromagnetic coil or iron core is small relative to the width of the mold, a flow that bypasses the electromagnetic brake area will occur, The effect tends to be unstable. Therefore, it is necessary to keep the ratio of the iron core occupying a certain value or more with respect to the width of the mold. As long as the proportion of the iron core occupied is sufficient, the characteristics of the electromagnetic brake, in which the left and right electromagnetic coils generate static magnetic fields with opposite polarities, can be fully exhibited.

The present invention uses two types of electromagnetic brake technology with different characteristics as described above, depending on the required slab quality requirements and casting conditions. Equipped with an electromagnetic brake device configured to switch between an electromagnetic brake that generates a magnetic field of the same polarity over the entire direction and an electromagnetic brake that generates a static magnetic field with opposite polarities from left and right electromagnetic coils. It is a continuous casting machine for molten metal.
The present invention will be described in more detail below. In the present invention, the mold width is at least three times the mold thickness.

The present invention is a continuous casting machine for molten metal, comprising a mold having a rectangular cross section, a tundish disposed above the mold, and an immersion nozzle for supplying molten metal from the tundish into the mold. and an electromagnetic brake device for braking two flows of molten steel metal discharged from the immersion nozzle toward both short sides of the mold by using a static magnetic field, the electromagnetic brake devices being arranged in parallel in the width direction of the mold. Two iron cores, and two iron cores installed so as to face the two iron cores with the mold interposed therebetween, respectively, and are excited by the two iron cores installed so as to face each other with the mold interposed. The electromagnet has opposite polarities and includes a current switching means for changing the direction of the current flowing through the electromagnet. By changing the direction of the current with the current switching means, the two iron cores arranged in parallel in the width direction of the mold are excited. Even if the polarity of the electromagnet to be excited is switched between the same polarity and the opposite polarity, and the polarity of the electromagnet excited by the two iron cores arranged in parallel in the width direction of the mold is the same polarity, even if the polarity is opposite. A continuous casting machine characterized in that two streams of molten steel metal directed to both short sides of the mold are braked by electromagnetic brakes .

By changing the direction of the current with the current switching means, two types of electromagnetic brake technology with different characteristics can be selectively used according to the desired slab quality requirements and casting conditions. As a result, it is possible to provide a continuous casting machine capable of a continuous casting operation that achieves both high productivity and high quality at a high level. In the present invention, the form of the "current switching means" is not particularly limited as long as it can change the direction of the current flowing through the electromagnet. It may be a device having a switch for switching the direction of current, or may be in a form in which a user changes the connection of a connector connected to a power source.

Further, in the present invention, the two iron cores arranged side by side in the width direction of the mold are such that the distance between the left end of the left iron core and the right end of the right iron core is greater than 80% of the width of the mold, and The distance between the iron core and the right iron core is smaller than 30% of the width of the mold and larger than 60% of the thickness of the mold, and two iron cores are arranged side by side in the width direction of the mold with respect to the width of the mold. is preferably 60% or more.

The distance between the left end of the left core and the right end of the right core (hereinafter sometimes referred to as "core end distance") is greater than 80% of the width of the mold, so that the core and the short side of the mold Since it becomes difficult for avoidance flow to flow downward through the gap, the braking effect of the electromagnetic brake can be stably exhibited. More preferably, the core end-to-end distance is 85% or more. In the present invention, the upper limit of the distance between both ends of the iron core is not particularly limited, but from the viewpoint of making it easier to appropriately obtain the braking effect of the electromagnetic brake, for example, it can be set to 150% or less of the width of the mold.
In addition, when the gap between the left core and the right core (hereinafter sometimes referred to as "core gap") is greater than 60% of the thickness of the mold, the interaction between the left and right coils is excessive. Since it does not become strong, it becomes difficult to reduce the magnetic flux density reaching the iron cores facing each other across the mold (that is, the strength of the magnetic field that exerts the braking force of the electromagnetic brake). As a result, the efficiency as an electromagnetic brake can be improved. Furthermore, since the iron core interval is smaller than 30% of the width of the mold, it is difficult for avoidance flow to flow downward between the left and right iron cores, so that the braking effect of the electromagnetic brake can be stably exhibited.
In addition, the ratio of the two iron cores arranged side by side in the width direction of the mold (hereinafter sometimes referred to as “core width occupation ratio”) to the mold width is 60% or more, so that the left and right iron cores Since it becomes difficult for avoidance flow to flow downward through the gap between the iron core and the short side of the cast slab, the braking effect of the electromagnetic brake can be stably exhibited. More preferably, the core width occupation ratio is 65% or more. In the present invention, the upper limit of the core width occupation ratio is not particularly limited, and can be set to 90% or less, for example.

Moreover, in the present invention, it is preferable that the two iron cores arranged side by side in the width direction of the mold are connected at their rear surfaces. As a result, it becomes possible to improve the excitation efficiency and to facilitate positioning, attachment and detachment. Furthermore, the effect of being able to design the entire electromagnetic brake device in a compact and lightweight manner can also be obtained.

Moreover, in the present invention, it is preferable that the two iron cores facing each other with the mold interposed therebetween are connected from the rear surface through the outside of the short side of the mold. As a result, the excitation efficiency can be improved, and since the magnetic flux density can be changed independently on the left and right sides of the mold width direction, the flow of the molten metal in the mold is biased to either the left or right side. It becomes easier to reduce this bias. Furthermore, in the present invention, it is preferable that the submerged nozzle is arranged at the center of the mold in the width direction of the mold.

Advantageous Effects of Invention According to the present invention, it is possible to provide a continuous casting machine capable of performing a continuous casting operation that achieves both high productivity and high quality at a high level.

It is an explanatory view showing an outline of composition of a continuous caster of the present invention. It is an explanatory view showing an outline of composition of an electromagnetic brake device and current switching means. FIG. 4 is an explanatory view showing the outline of the configuration of an electromagnetic brake device that generates a magnetic field of the same polarity over the entire mold width direction. FIG. 3 is an explanatory view showing the outline of the configuration of an electromagnetic brake device in which electromagnetic coils divided into left and right in the mold width direction generate magnetic fields with opposite polarities. FIG. 3B is a diagram schematically explaining the flow that occurs in the mold in the case of the form shown in FIG. 3A. FIG. 3B is a diagram schematically explaining the flow that occurs in the mold in the case of the form shown in FIG. 3B; It is a figure explaining mold both-ends distance, core interval, mold width, and mold thickness. It is a figure explaining the iron core which was connected in the back surface and which was paralleled to right and left of the mold width direction. FIG. 4 is a diagram illustrating iron cores placed opposite to each other with the mold interposed therebetween, which are connected from the back through the outside of the short side of the mold. BRIEF DESCRIPTION OF THE DRAWINGS It is a figure explaining one embodiment example of the electromagnetic brake device in this invention. It is a figure explaining other examples of embodiment of the electromagnetic brake equipment in the present invention. It is a figure explaining other examples of embodiment of the electromagnetic brake equipment in the present invention. It is a figure explaining other examples of embodiment of the electromagnetic brake equipment in the present invention. It is a figure explaining other examples of embodiment of the electromagnetic brake equipment in the present invention. It is a figure explaining other examples of embodiment of the electromagnetic brake equipment in the present invention. It is a figure explaining the form of the conventional electromagnetic brake device. It is a figure explaining other forms of the conventional electromagnetic brake equipment.

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the present specification and drawings, constituent elements having substantially the same functional configuration are denoted by the same reference numerals, thereby omitting redundant description.

FIG. 1 is an explanatory diagram showing the outline of the configuration of a continuous casting machine 100 of the present invention. In FIG. 1, description of a power source and current switching means is omitted. A continuous casting machine 100 shown in FIG. 20, and an electromagnetic brake device 40 that brakes the two molten steel metal flows discharged from the immersion nozzle 20 toward both short sides of the mold 30 using a static magnetic field.

FIG. 2 is an explanatory diagram showing the outline of the configuration of the electromagnetic brake device 40 and the current switching device 45. As shown in FIG. As shown in FIG. 2, the electromagnetic brake device 40 has four electromagnets AD.
Electromagnet A and electromagnet C, electromagnet B and electromagnet D are installed side by side in the width direction of mold 30, and electromagnet A and electromagnet B and electromagnet C and electromagnet D face each other with mold 30 interposed therebetween. is set up to Electromagnets A-D have cores 41a-41d and coils 42a-42d wound therearound, respectively. The coils 42a and 42b of the electromagnet A and the electromagnet B, which are installed to face each other with the mold 30 interposed therebetween, are connected to a power supply 43, respectively. Also, the coils 42c and 42d of the electromagnets C and D, which are placed facing each other with the mold 30 interposed therebetween, are connected to the power source 44 via the current switching device 45, respectively. The electromagnetic brake device 40 shown in FIG. 2 uses the current switching device 45 to change the direction of the current flowing through the coils 42c and 42d, so that the polarities of the two electromagnets arranged in parallel in the width direction of the mold 30 are changed to Switchable between same polarity and opposite polarity. With such a configuration, two electromagnetic brake modes as shown in FIGS. 3A and 3B, which will be described later, can be selectively used according to the required slab quality requirements and casting conditions. A continuous casting operation that achieves both high quality and a high level becomes possible. Since the electromagnetic brake device 40 in the present invention is intended to brake the discharge flow from the immersion nozzle 20, it is intended for powder casting using an immersion nozzle, which is the most common continuous casting method. Therefore, hot water supply to the mold 30 of the continuous casting machine 100 is configured such that molten metal is supplied into the mold 30 from the tundish 10 above through the submerged nozzle 20 .

FIG. 3A is a diagram schematically showing the configuration of the electromagnetic brake device when the polarities of the two electromagnets arranged in parallel in the width direction of the mold 30 are the same. Flow is shown schematically in FIG. 4A. FIG. 3B is a diagram schematically showing the configuration of the electromagnetic brake device when the polarities of the two electromagnets arranged in parallel in the width direction of the mold 30 are opposite to each other. The resulting flow is schematically shown in FIG. 4B. In Figures 4A and 4B, the direction of the discharge flow is indicated by arrows.
In the form shown in FIG. 3A, the electromagnets A and C installed above the mold 30 on the paper surface have the same polarity N, and the electromagnets B and D installed on the lower surface of the mold 30 both have the same polarity. also has the same polarity S. When the electromagnetic brake device 40 having such a configuration is used to brake the flow of molten steel, as shown in FIG. It opposes the downward flow in the nozzle 20 and produces an upward flow toward the molten steel surface. As a result, the melt surface around the submerged nozzle 20 rises and fluctuates. On the other hand, as shown in FIG. 4A, the upward flow that rises up around the submerged nozzle 20 then flows toward the short side of the mold just below the surface of the molten metal. This flow provides an opportunity for non-metallic inclusions in the molten metal to rise to the surface and be absorbed by the molten layer of the mold powder, thus cleaning the molten metal.
On the other hand, the configuration shown in FIG. 3B is achieved by changing the directions of the currents flowing through the coils of the electromagnets B and D from the state shown in FIG. 3A. When the molten steel flow is braked by the electromagnetic brake device 40 having the configuration shown in FIG. 3B, the discharge flow from the submerged nozzle 20 is decelerated without being bounced back as shown in FIG. form a gentle upward and downward flow along the As a result, the interior of the mold remains relatively calm.
It should be noted that the magnetic flux density required to induce the flow shown in FIGS. 4A and 4B is approximately 3000 Gauss or greater. Also, a magnetic flux density exceeding 6000 gauss is excessive and unnecessary.
In addition, the thickness of the iron core in the electromagnetic brake device required to obtain such magnetic flux density is 150 mm or more. Moreover, the thickness of the iron core exceeding 400 mm is excessive and unnecessary.

FIG. 5 is a top view for explaining the distance between mold ends, the distance between cores, the mold width, and the mold thickness. Conditions that are preferably satisfied by the present invention will be described with reference to FIG.

The electromagnetic brake device 40 preferably has a core end-to-end distance greater than 80% (more preferably 85%) of the width of the mold. This makes it difficult for the avoidance flow to flow downward through the gap between the iron core and the short side of the mold 30, so that the braking effect of the electromagnetic brake device 40 can be stably exhibited. In the electromagnetic brake device 40, the upper limit of the distance between both ends of the iron core is not particularly limited, but from the viewpoint of making it easier to appropriately obtain the braking effect of the electromagnetic brake device 40, for example, it may be set to 150% or less of the width of the mold. can.

Further, the electromagnetic brake device 40 preferably has a core interval smaller than 30% of the mold width and larger than 60% of the mold thickness. Since the inter-core spacing is greater than 60% of the mold thickness, the interaction between the left and right coils does not become excessively strong, so the magnetic flux density reaching the iron cores facing each other across the mold 30 (that is, the limit of the electromagnetic brake device 40). strength of the magnetic field that exerts power) is difficult to reduce. As a result, the efficiency of the electromagnetic brake device can be enhanced. Furthermore, since the core interval is smaller than 30% of the width of the mold, it is difficult for avoidance flow to flow downward between the left and right cores, so that the braking effect of the electromagnetic brake device 40 can be stably exhibited.

Further, the electromagnetic brake device 40 preferably has an iron core width occupation ratio of 60% (more preferably 65%) or more. This makes it difficult for avoidance flow to flow downward between the left and right iron cores and the gap between the iron core and the short side of the slab 30, so that the braking effect of the electromagnetic brake device 40 can be stably exhibited. In the electromagnetic brake device 40, the upper limit of the core width occupation ratio is not particularly limited, and can be set to 90% or less, for example.

6 and 7 are diagrams illustrating a preferred form of the electromagnetic brake device according to the present invention. FIG. 6 is a top view for explaining the iron cores arranged side by side in the width direction of the mold, which are connected at the back, and FIG. It is a top view explaining the iron core installed so that it might oppose on both sides.
Iron cores provided in electromagnetic brake devices are generally connected on the back side for the purpose of enhancing excitation efficiency or facilitating positioning, attachment and detachment. Here, "connecting" the cores means connecting two cores as cores. A form in which two iron cores are integrated may be used, a form in which a member for connecting the two iron cores and the two iron cores are in contact with each other, and a member for connecting the two iron cores and the two iron cores may be in contact with each other. A form in which they are arranged at intervals of about several millimeters may also be used.

By adopting the form shown in FIG. 6, it is possible to improve the excitation efficiency and facilitate positioning, attachment and detachment. Furthermore, the effect of being able to design the entire electromagnetic brake device in a compact and lightweight manner can also be obtained.
In addition, by adopting the form shown in FIG. 7, it is possible to increase the excitation efficiency, and in addition, it is possible to independently change the magnetic flux density on the left side and the right side in the width direction of the mold. If the flow of molten metal deviates to the left or right, it becomes easier to reduce this deviation.
In this way, the effect obtained is partly different between the form shown in FIG. 6 and the form shown in FIG.
Therefore, it is preferable to select a suitable configuration according to the individual conditions (required quality and equipment specifications) of the continuous casting machine.

The present invention will be described below with specific examples. Table 1 shows specific conditions for the examples described below. 8 to 15 showing examples and comparative examples, the mold is shown in a more simplified manner than in FIGS. 1 to 7, and for simplification, top and front views of the mold and the electromagnetic brake device are shown. While shown schematically, the front view omits the description of members that connect the cores.

1. Examples 1.1. Example 1
Embodiment 1 shown in FIG. 8 is an embodiment that satisfies claims 1-3.
In Example 1, when the discharge flow from the two-hole submerged nozzle is braked by the left and right electromagnetic brakes, the polarities of the electromagnets excited by the two iron cores arranged in the width direction of the mold are the same. It is possible to switch between two types of electromagnetic brake modes with opposite polarities. The in-mold flow at that time is the same as in FIGS. 4A and 4B.
Moreover, since Example 1 has a distribution in the width direction of the iron core that satisfies the preferable conditions described with reference to FIG. Moreover, the efficiency as an electromagnetic brake device is also high.
Furthermore, in Example 1, since the iron cores arranged side by side in the width direction of the mold are connected at the rear surface thereof, it is compact and lightweight, and can be easily introduced by modifying an existing continuous casting machine.

1.2. Example 2
Embodiment 2 shown in FIG. 9 is an embodiment that satisfies claims 1, 2 and 4. FIG.
In Example 2, when the discharge flow from the two-hole submerged nozzle is braked by the left and right electromagnetic brakes, the polarities of the electromagnets excited by the two iron cores arranged in the width direction of the mold are the same. It is possible to switch between two types of electromagnetic brake modes with opposite polarities. The in-mold flow at that time is the same as in FIGS. 4A and 4B.
Moreover, since Example 2 has a distribution in the width direction of the iron core that satisfies the preferable conditions described with reference to FIG.
Moreover, the efficiency as an electromagnetic brake device is also high.
In Example 2, the distance between both ends of the iron core is greater than the width of the mold, which indicates that the electromagnetic brake is designed to accommodate a wider mold width.
Furthermore, in Example 2, the iron cores facing each other across the mold are connected from the back through the outside of the short side of the mold. , the left and right magnetic flux densities can be changed independently (for example, the braking force on the side with the stronger discharge flow can be relatively increased). On the other hand, since the electromagnetic brake device is large and heavy, its installation requires a sufficient space around the mold and a mold vibration device that can withstand the load.

1.3. Example 3
Example 3 shown in FIG. 10 is an example that satisfies claims 1 and 2 .
In Example 3, when the discharge flow from the two-hole submerged nozzle is braked by the left and right electromagnetic brakes, the polarities of the electromagnets excited by the two iron cores arranged in the width direction of the mold are the same. It is possible to switch between two types of electromagnetic brake modes with opposite polarities. The in-mold flow at that time is the same as in FIGS. 4A and 4B.
Moreover, since Example 3 has a distribution in the width direction of the iron core that satisfies the preferable conditions described with reference to FIG.
In addition, the iron core arrangement is capable of suppressing a decrease in efficiency due to interaction between the left and right coils as an electromagnetic brake device.
On the other hand, the third embodiment has an iron core configuration that does not satisfy the third and fourth aspects. difficult to raise.

1.4. Example 4
Example 4 shown in FIG. 11 is an example that satisfies claims 1 and 4. FIG.
In Example 4, when the discharge flow from the two-hole submerged nozzle is braked by the left and right electromagnetic brakes, the polarities of the electromagnets excited by the two iron cores arranged in the width direction of the mold are the same. It is possible to switch between two types of electromagnetic brake modes with opposite polarities. The in-mold flow at that time is the same as in FIGS. 4A and 4B.
However, in Example 4, since the width-direction occupation ratio of the iron core is small, the flow tends to occur avoiding the outside of the electromagnetic braking area (near the short side of the mold). Therefore, compared with Examples 1 to 3, the braking effect tends to be unstable.
On the other hand, in Example 4, the iron cores facing each other across the mold are connected from the back through the outside of the short side of the mold. , the left and right magnetic flux densities can be changed independently (for example, the braking force on the side with the stronger discharge flow can be relatively increased). On the other hand, since the electromagnetic brake device is large and heavy, its installation requires a sufficient space around the mold and a mold vibration device that can withstand the load.

1.5. Example 5
Example 5 shown in FIG. 12 is an example that satisfies claims 1 and 3. FIG.
In Example 5, when the discharge flow from the two-hole submerged nozzle is braked by the left and right electromagnetic brakes, the polarities of the electromagnets excited by the two iron cores arranged in the width direction of the mold are the same. It is possible to switch between two types of electromagnetic brake modes with opposite polarities. The in-mold flow at that time is the same as in FIGS. 4A and 4B.
However, in Example 5, since the iron core spacing is small, compared with Examples 1 to 3, the efficiency as an electromagnetic brake device is low.
On the other hand, in Example 5, since the iron cores arranged side by side in the width direction of the mold are connected at the rear surface thereof, it is compact and lightweight, and can be easily introduced by modifying an existing continuous casting machine.

1.6. Example 6
Example 6 shown in FIG. 13 is an example that satisfies claim 1 .
In Example 6, when the discharge flow from the two-hole submerged nozzle is braked by the left and right electromagnetic brakes, the polarities of the electromagnets excited by the two iron cores arranged in the width direction of the mold are the same. It is possible to switch between two types of electromagnetic brake modes with opposite polarities. The in-mold flow at that time is the same as in FIGS. 4A and 4B.
However, in Example 6, since the iron core spacing is large and the width direction occupation ratio of the iron core is small, the flow that avoids between the left and right electromagnetic braking areas (near the center of the width of the mold) is likely to occur. Therefore, compared with Examples 1 to 3, the braking effect tends to be unstable.
Also, in Example 6, all cores are independent (not connected to other cores). Therefore, compared with Examples 1 and 2 and Examples 4 and 5, it is difficult to position the coil when installing the electromagnetic brake device, and it is difficult to improve the excitation efficiency of the coil.

2. Comparative example 2.1. Comparative example 1
Comparative Example 1 shown in FIG. 14 is a comparative example that does not satisfy the conditions of the present invention.
The iron core configuration of the electromagnetic brake device of Comparative Example 1 is the same as that of Example 1, but in Comparative Example 1, when braking the discharge flow from the two-hole submerged nozzle with left and right electromagnetic brakes, the width direction of the mold It is applicable only when the polarities of the electromagnets excited by the two iron cores arranged side by side are opposite to each other.
That is, in Comparative Example 1, the direction of the current flowing through the electromagnetic coil cannot be changed, and the case where the polarities of the electromagnets excited by the two iron cores arranged in the width direction of the mold are the same cannot be realized. As a result, the effect of the present invention of switching the mode of the current brake according to the required quality requirements and casting conditions cannot be enjoyed. Specifically, in Comparative Example 1, the operating factor of the electromagnetic brake device in operation was only the current value, and compared with Examples 1 to 6, the degree of freedom of flow control within the mold was poor.

2.2. Comparative example 2
Comparative Example 2 shown in FIG. 15 is a comparative example that does not satisfy the conditions of the present invention.
Unlike Examples 1 to 6 and Comparative Example 1, Comparative Example 2 does not have two iron cores aligned in the width direction of the mold, and generates a magnetic field of the same polarity over the entire width direction of the mold. Therefore, the form described in FIG. 4B cannot be realized. As a result, the effect of the present invention of switching the mode of the current brake according to the required quality requirements and casting conditions cannot be enjoyed.

A, B, C, D... Electromagnet 1... Molten metal 10... Tundish 20... Immersion nozzle 30... Mold 40... Electromagnetic brake device 41a, 41b, 41c, 41d... Iron core 42a, 42b, 42c, 42d... Coil 43, 44 ... power supply 45 ... current switching device (current switching means)
100 Continuous casting machine

Claims (5)

A continuous casting machine for molten metal,
a mold having a rectangular cross section;
a tundish positioned above the mold;
a submerged nozzle feeding molten metal from the tundish into the mold;
an electromagnetic brake device that brakes two molten steel metal flows discharged from the immersion nozzle toward both short sides of the mold using a static magnetic field,
The electromagnetic brake device has two iron cores arranged in parallel in the width direction of the mold, and two iron cores arranged to face the two iron cores with the mold interposed therebetween,
The respective electromagnets excited by the two iron cores arranged to face each other across the mold have opposite polarities,
A current switching means for changing the direction of the current flowing through the electromagnet,
By changing the direction of the current with the current switching means, the polarities of the electromagnets excited by the two iron cores arranged in parallel in the width direction of the mold are switched between the same polarity and the opposite polarity ,
Even if the polarities of the electromagnets excited by the two iron cores arranged in parallel in the width direction of the mold are the same or opposite, both short sides of the mold are operated by the electromagnetic brake. Continuous casting machine, characterized in that the two streams of molten steel metal directed to are braked . The two iron cores arranged side by side in the width direction of the mold are
The distance between the left end of the left core and the right end of the right core is greater than 80% of the width of the mold, and
The distance between the left core and the right core is less than 30% of the width of the mold and greater than 60% of the thickness of the mold, and
2. The continuous casting machine according to claim 1, characterized in that the ratio of the two iron cores arranged side by side in the width direction of the mold is 60% or more of the width of the mold. . 3. The continuous casting machine according to claim 1, wherein the two iron cores arranged side by side in the width direction of the mold are connected at their rear surfaces. 3. The continuation according to claim 1 or 2, characterized in that the two iron cores arranged to face each other with the mold sandwiched therebetween are connected from their rear surfaces through the outside of the short sides of the mold. Casting machine. The continuous casting machine according to any one of claims 1 to 4, wherein the submerged nozzle is arranged at the center of the mold in the width direction of the mold.

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