JP2010284717A - Twin roll continuous caster - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a twin roll continuous caster which attains the fining of a crystalline solid of molten metal in the center of the thickness of a cast piece and the prevention of segregation and which can manufacture the cast piece having excellent product characteristics. <P>SOLUTION: The caster 1 is equipped with a pair of rolls 2 and 2 and a cylindrical nozzle 3 and manufactures the cast piece 6 by feeding the molten metal 4 between the rolls 2 and 2 via the nozzle 3. The caster 1 is also equipped with a means inserted into a basin of the molten metal 4 and providing an external field for a semi-solidified object 7 in the center of the thickness of the cast piece 6. The means of providing the external field includes a core 10 which is hollow and of which the inside is supplied with the molten metal 4 and a plurality of screws 11, 11, ..., which fluidize the molten metal 4 inside the core 10. The core 10 is provided with an outflow hole 10a which communicates with the inside and outside of the core 10 and is open toward the center of the thickness of the cast piece 6. The molten metal 4 inside the core 10 flows out from the outflow hole 10a by means of the screws 11, 11, ..., and the molten metal 4 inside and outside the core 10 is fluidized toward the center of the thickness of the cast piece 6 so that the semi-solidified object 7 in the center of the thickness of the cast piece 6 is stirred. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a twin roll type continuous casting machine.

Conventionally, a pair of rolls arranged at a predetermined interval and rotating at a constant speed in opposite directions are provided, and the molten metal supplied between these rolls is cooled on the surface of each roll to form a solidified shell. 2. Description of the Related Art A twin roll type continuous casting machine is known in which solidified shells are pressed against each other between rolls to continuously form a plate-shaped slab.
In such a twin-roll type continuous casting machine, the molten metal may stay in the vicinity of the axial end portion of the roll by convection, and the molten metal may solidify while adhering to the surrounding members. Since the molten metal thus solidified is not rapidly cooled on the surface of the roll, it gradually grows at a relatively slow cooling rate. When the cooling rate of the molten metal is slow, the solidified crystal of the molten metal becomes coarse or segregation occurs. Therefore, when the molten metal solidified as described above grows to a predetermined size, it peels off from the attached member, and when the slab is cast by being taken in between the rolls, slab cracking occurs, or elongation characteristics, etc. There were problems such as insufficient product characteristics.

In Patent Document 1, a hollow core having an opening is provided in the vicinity of the end portion of the roll, and the core is directed toward a part of the solidified molten metal attached to the peripheral member at the shaft end portion of the roll as described above. A technology for preventing the solidified molten metal from being taken in between the rolls by supplying a new molten metal from the opening of the metal and remelting the solidified molten metal or damming it near the core to prevent outflow is described. ing.
However, the technique described in Patent Literature 1 is disadvantageous in that the cooling rate of the molten metal in the vicinity of the center of the slab thickness (plate thickness center portion) cannot be improved. That is, since the molten metal is rapidly cooled on the surface of the roll, the cooling rate of the molten metal gradually decreases as the distance from the surface of the roll increases. In particular, the cooling rate of the molten metal at the center portion of the slab thickness is minimized, and as described above, there is a high possibility that the solidified crystal of the molten metal becomes coarse or segregates. As a result, there arises a problem that the cast slab is cracked or product characteristics such as elongation characteristics are insufficient.

JP-A 61-195747

  The present invention provides a twin-roll continuous casting machine that achieves refinement of solidified crystals of molten metal and prevention of segregation at the center of the slab thickness, and is capable of casting slabs with good product characteristics. Is an issue.

  In Claim 1, it is provided with a pair of rolls arranged at predetermined intervals and rotating at a constant speed in opposite directions, and a cylindrical nozzle for supplying molten metal between the pair of rolls. A twin-roll continuous casting machine that continuously feeds a plate-shaped slab by supplying the molten metal through the nozzle between rolls, and serving as a molten metal reservoir formed in the nozzle. Means for inserting an external field into the molten metal inserted in the center portion of the thickness of the slab is provided.

  In Claim 2, the said external field provision means comprises a core which has a hollow shape and a molten metal is supplied to the inside, and a means for flowing the molten metal supplied to the inside of the core, In the core, an outflow hole that communicates the inside and the outside of the core is opened toward the center of the plate thickness of the slab, and the molten metal inside the core is discharged from the outflow hole by the flow means. The molten metal inside and outside the core flows toward the center of the thickness of the slab, and the molten metal at the center of the thickness of the slab is agitated.

  In Claim 3, the said outflow hole is arrange | positioned below the point from which a pair of said roll and the said molten metal start a contact.

  According to a fourth aspect of the present invention, the core has a predetermined heat insulating property.

  According to a fifth aspect of the present invention, the molten metal inside the core is made of a different kind of metal from the molten metal outside the core.

  The synthetic | combination formed in the said external field provision means is provided with the several vibration plate which generate | occur | produces a wave in the said molten metal, and the said several vibration plate vibrates and generate | occur | produces. The portion where the amplitude of the wave is maximum is located at the center of the plate thickness of the slab.

  According to a seventh aspect of the present invention, the plurality of diaphragms are arranged so as to coincide with a height of a point where the pair of rolls and the molten metal start contact.

  In Claim 8, the said external field provision means comprises the rotary body to which the solidified crystal of the molten metal adheres to the surface, and the solidified crystal of the molten metal is removed from the surface of the rotary body by rotating the rotary body. It peels and falls toward the plate | board thickness center part of the said slab.

  ADVANTAGE OF THE INVENTION According to this invention, refinement | miniaturization of the solidification crystal | crystallization of the molten metal in the plate | board thickness center part of slab and prevention of segregation are achieved, and the slab which has a favorable product characteristic can be cast.

The perspective view which shows a twin roll type continuous casting machine. The schematic front view which shows a twin roll type continuous casting machine. The schematic front view which shows the external field provision means in 1st embodiment of this invention. The schematic front view which shows the external field provision means in 2nd embodiment of this invention. The schematic side view which shows the external field provision means in 2nd embodiment of this invention. The schematic front view which shows the external field provision means in 3rd embodiment of this invention.

[First embodiment]
Below, with reference to FIGS. 1-2, the casting machine 1 which concerns on 1st embodiment of this invention is demonstrated.

The casting machine 1 cools the molten metal 4 supplied between the rolls 2 and 2 through the nozzle 3 on the surface of the rolls 2 and 2 to form the solidified shells 5 and 5. A twin roll type continuous casting machine in which the slab 6 is continuously formed by press-contacting between the two.
The molten metal 4 is a liquid phase metal obtained by melting a metal such as an aluminum alloy or cast iron.
The solidified shell 5 is a solid phase metal that is solidified by cooling the molten metal 4 on the surface of the roll 2.
The slab 6 is a plate-like metal that is formed by press-contacting the solidified shells 5 and 5 between the rolls 2 and 2 and is appropriately processed after being cut at an arbitrary length.

  As shown in FIGS. 1 and 2, the casting machine 1 includes rolls 2 and 2, a nozzle 3, and a core 10.

The rolls 2 and 2 are substantially cylindrical members made of a metal having high heat conductivity and excellent heat resistance and durability. The rolls 2 and 2 are spaced at predetermined intervals so that the axes of the rolls 2 and 2 are parallel to each other. Placed horizontally. The rolls 2 and 2 are cooled by appropriate cooling means so that the vicinity of the surface has a predetermined temperature.
The rolls 2 and 2 form the solidified shells 5 and 5 by cooling the molten metal 4 supplied through the nozzle 3 between them on the respective surfaces. The rolls 2 and 2 rotate at the same speed in mutually opposite directions (arrow directions in FIGS. 1 and 2) to press the solidified shells 5 and 5 between the rolls 2 and 2 so as to have a predetermined thickness. The slab 6 having the shape is continuously formed and discharged downward (on the side opposite to the side on which the nozzle 3 is disposed). The thickness of the slab 6 is determined by the distance between the rolls 2 and 2, and is appropriately set so as to obtain a desired thickness.

  The nozzle 3 is a cylindrical member in which a hot water pool of the molten metal 4 is formed and supplies the molten metal 4 to a space formed between the rolls 2 and 2, near the upper part between the rolls 2 and 2, and The rolls 2 and 2 are arranged along the axial direction. A spout for pouring out the molten metal 4 is opened at the same width along the axial direction of the roll 2 at the lower end of the nozzle 3 (the end on the roll 2 or 2 side). Further, the outer periphery of the lower end portion of the nozzle 3 is formed in an arc shape along the outer peripheral shape of the rolls 2 and 2, and the molten metal 4 is supplied with the lower end portion of the nozzle 3 as close as possible to the outer peripheral surface of the rolls 2 and 2. And the molten metal 4 is prevented from entering the gap between the outer peripheral surface of the rolls 2 and 2 and the lower end of the nozzle 3.

The core 10 is a member made of a material excellent in heat resistance, durability, and the like, and improves the cooling efficiency of the molten metal 4 supplied between the rolls 2 and 2 by the rolls 2 and 2. The core 10 is inserted into a hot water pool of the molten metal 4 formed inside the nozzle 3 and is disposed along the axial direction of the rolls 2 and 2 above a central position between the rolls 2 and 2.
In the lower part of the core 10, an inclined surface is formed in the axial direction of the rolls 2 and 2 so as to face the outer peripheral surface of the rolls 2 and 2 and to follow the outer peripheral shape of the rolls 2 and 2. The inclined surface is a point where the surface of the rolls 2 and 2 and the molten metal 4 start to contact (the position where the lower end of the nozzle 3 and the rolls 2 and 2 are closest to each other. ").” Is formed toward the lower surface of the core 10. That is, the distance between the core 10 and the rolls 2 and 2 is substantially constant in a range where the core 10 and the rolls 2 and 2 face each other and the molten metal 4 is sandwiched therebetween. Therefore, the volume in each part of the molten metal 4 supplied between the core 10 and the rolls 2 and 2 is made substantially constant (more strictly, it is formed between the core 10 and the surface of the roll 2. The cross section of each part can be made substantially constant), and the cooling of the molten metal 4 by the rolls 2 and 2 can be made efficient.
The length of the core 10 in the axial direction of the roll 2 is set to be substantially the same as the length inside the nozzle 3, and the core 10 in the thickness (distance between the rolls 2 and 2) direction of the cast piece 6. The length is set smaller than the internal length of the nozzle 3.

The casting machine 1 further has a position near the center of the thickness of the slab 6 (distance between the rolls 2 and 2) at a position where the distance between the rolls 2 and 2 is minimized, that is, the solidified shells 5 and 5 and the slab 6. And a means for applying an external field to the vicinity of the point C (thickness center point) C (hereinafter referred to as “thickness center portion”).
That is, in the center portion of the plate thickness, there is a metal in which the molten metal 4 is cooled and a solid phase metal and a liquid phase metal are mixed to be in a semi-solid state as described later. The external field applying means 1 applies an external field to the semi-solidified metal at the center of the plate thickness.

Below, with reference to FIG. 3, the external field provision means in 1st embodiment of this invention is demonstrated.
In the present embodiment, the molten metal 4 is agitated by the core 10 and the screws 11, 11... To mechanically apply an external field to the center portion of the plate thickness.

As shown in FIG. 3, the core 10 is formed in a hollow shape, and the molten metal 4 is supplied to the inside of the core 10 in the same manner as the outside of the core 10. The core 10 communicates with the inside and the outside through an outflow hole 10a.
The outflow hole 10 a is a hole that communicates the inside and the outside of the core 10, and is opened with the same width along the axial direction of the roll 2 at the center of the lower surface of the core 10. That is, the outflow hole 10a is opened toward the center portion of the plate thickness, and is disposed below the contact points P · P.
In this way, in the nozzle 3, the molten metal 4 is supplied between the rolls 2 and 2 from both the inside and the outside of the core 10.

A plurality of screws 11, 11... Are provided inside the core 10.
The screws 11, 11... Are means for rotating the molten metal 4 to generate a flow of the molten metal 4 in the direction of the rotation axis and flowing the molten metal 4. .. Are disposed along the axial direction of the roll 2 so as to be located above the outflow hole 10a of the core 10. The screws 11, 11... Are respectively fixed to appropriate shaft members, and are rotated in a predetermined direction at a fixed position by being rotationally driven by an arbitrary drive device.
The number of screws 11 is appropriately determined depending on the length of the slab 6 in the axial direction of the roll 2.

In the configuration as described above, when the screws 11, 11... Are rotationally driven by the driving device, a flow directed downward from the screws 11, 11. The molten metal 4 inside the core 10 thus flowed flows out of the core 10 from the outflow hole 10a of the core 10, joins the molten metal 4 outside the core 10, and reaches the center of the plate thickness. . In the molten metal 4, a semi-solid body 7 is formed so as to cover the solidified shells 5, 5 from the outflow hole 10 a of the core 10 to the center portion of the plate thickness.
The semi-solidified body 7 is a process in which the molten metal 4 which is a liquid phase metal is cooled to change into a solidified shell 5 which is a solid phase metal, and a liquid phase metal and a solid phase metal are mixed. It is a so-called semi-solid metal. The semi-solidified body 7 is formed between the solidified shells 5 and 5 so as to cover the solidified shells 5 and 5.

The molten metal 4 that has been flowed to the center of the plate thickness by the screws 11, 11... Stirs the semi-solid body 7 by the flow. In other words, the semi-solid body 7 is agitated by the flow of the molten metal 4 generated by the rotation of the screws 11, 11.
Since the semi-solid body 7 is separated from the rolls 2 and 2, it is cooled at a relatively slow cooling rate. In particular, the cooling rate of the semi-solid body 7 at the center of the plate thickness is the slowest, and the crystal grains tend to become coarse. However, when the semi-solid body 7 is agitated by the screws 11, 11..., The crystal grains of the semi-solid body 7 at the center of the plate thickness are refined.
In addition, the magnitude | size of the outflow hole 10a is set to such an extent that sufficient stirring force is transmitted to the semi-solid body 7 in the plate | board thickness center part by allowing the predetermined amount of molten metal 4 to pass through.

  As described above, the core 10 and the screws 11, 11... Are used as means for applying an external field to the semi-solid body 7 at the center of the plate thickness, and a plurality of screws provided inside the core 10. By stirring the semi-solid body 7 by 11, 11..., The crystal grains of the semi-solid body 7 at the center of the plate thickness can be refined and segregation can be prevented. The piece 6 can be cast.

Further, since the contact points P and P are points where the surface of the rolls 2 and 2 and the molten metal 4 start to contact, the solidified shells 5 and 5 are relatively thin and easily peel from the surface of the rolls 2 and 2. However, the screws 11, 11,... Are provided inside the core 10, and the outflow holes 10a of the core 10 are disposed below the contact points P, P. Therefore, the screws 11, 11,. The flow of the molten metal 4 passes through the outflow hole 10a, reaches the pin point at the center of the plate thickness, and does not reach the contact points P and P.
Therefore, while stirring force (disturbance caused by the flow of the molten metal 4) is transmitted to the semi-solid body 7 at the center of the plate thickness where it is difficult to give an external field, the vibrations at the contact points P and P are suppressed to a small level and the rolls 2.2 It is possible to prevent the solidified shells 5 and 5 from being peeled off. Accordingly, it is possible to prevent wrinkles and the like from being generated on the surface of the cast slab 6 to deteriorate the quality.

Further, the core 10 may be provided with a heat insulating material that prevents a heat flow from occurring between the inside and the outside of the core 10. Thereby, the core 10 has a predetermined heat insulation characteristic, and the molten metal 4 inside the core 10 can maintain a constant temperature. Therefore, the temperature drop can be suppressed until the molten metal 4 inside the core 10 flows out from the outflow hole 10a, and the deterioration of the cooling rate of the molten metal 4 can be prevented. 7 can be refined. Here, the “predetermined heat insulating property” is a heat insulating property that can maintain a constant temperature until the molten metal 4 inside the core 10 flows out from the outflow hole 10a.
The predetermined heat insulating property may be imparted to the core 10 as long as the molten metal 4 inside the core 10 can maintain a predetermined temperature, and the method is not particularly limited. For example, the core 10 is configured to have a predetermined heat insulating property by attaching a heat insulating material to the inner peripheral surface or outer peripheral surface of the core 10 or by configuring the core 10 itself with a heat insulating material. Can do.

Further, a molten metal made of a different kind of metal from the outside of the core 10 may be supplied inside the core 10. As a result, the molten metal inside the core 10 flows out from the outflow hole 10a toward the center of the plate thickness and is pressed between the rolls 2 and 2 together with the molten metal outside the core 10 to form a casting made of a plurality of metals. A piece (cladding material) can be cast.
Further, for example, by supplying a molten metal with a high hydrogen dissolution amount to which titanium hydride is added into the core 10, a foamed material in which bubbles are formed by supersaturated hydrogen gas discharged during solidification of the molten metal is cast. can do.

[Second Embodiment]
Below, with reference to FIGS. 4-5, the external field provision means in 2nd embodiment of this invention is demonstrated.
In this embodiment, instead of the core 10 and the screws 11, 11..., A pair of diaphragms 20, 20, etc. are inserted into a hot water pool of the molten metal 4 formed inside the nozzle 3, and the vibrator 21. By vibrating the diaphragms 20 and 20 by 21, a predetermined wave is generated in the molten metal 4, and an external field is mechanically applied to the semi-solidified body 7 at the center of the plate thickness.

  As shown in FIGS. 4 and 5, the external field imparting means in the present embodiment is composed of a pair of diaphragms 20 and 20.

  The vibration plates 20 and 20 are plate materials that generate a predetermined wave in the molten metal 4 by vibrating in the molten metal 4, and are axially arranged in the axial direction of the roll 2 with a predetermined interval in the thickness direction of the slab 6. Are extended so as to have the same cross section. The diaphragms 20 and 20 are inserted into a puddle of the molten metal 4 formed inside the nozzle 3, are symmetrical with respect to a line drawn in the vertical direction from the plate thickness center point C, and have high contact points P and P. So as to coincide with each other, are arranged horizontally in a state of facing each other. The diaphragms 20 and 20 are connected to the vibrators 21 and 21 via a plurality of connecting members 22 and 22.

The vibrators 21 and 21 are members that vibrate the diaphragms 20 and 20, and are connected to the diaphragms 20 and 20 via connection members 22, 22. The vibrators 21 and 21 are arranged outside the hot water pool of the molten metal 4 formed inside the nozzle 3 and above the diaphragms 20 and 20, respectively.
The connecting member 22 is a bar that connects the diaphragm 20 and the vibrator 21, and a plurality of connecting members 22 are provided along the axial direction of the roll 2.

In the above configuration, when the diaphragms 20 and 20 are vibrated in the direction of the arrows shown in FIG. 4 by the vibrators 21 and 21 via the connecting members 22 and 22. Waves are generated in the molten metal 4. At this time, as the diaphragms 20 and 20 vibrate in the same phase, as shown in FIG. 4, a line drawn vertically from the central portion between the diaphragms 20 and 20 causes the diaphragms 20 and 20 to move. It becomes the maximum part (antinode of standing wave) of the amplitude of the synthesized wave (standing wave) formed by the interference of two waves as the wave source. Here, the alternate long and short dash line in FIG. 4 indicates the maximum part (antinode of the standing wave) of the combined wave (standing wave) formed by the interference of the two waves using the diaphragms 20 and 20 as the wave source.
A plate thickness center point C is located on a line drawn in the vertical direction from the central portion between the diaphragms 20 and 20. Therefore, the maximum portion (antinode of the standing wave) of the combined wave (standing wave) formed by the interference of the two waves having the vibration plates 20 and 20 as the wave source reaches the center of the plate thickness. It becomes possible to give a comparatively big vibration to the semi-solidified body 7 in a part. Accordingly, the crystal grains of the semi-solid body 7 in the center portion of the plate thickness can be refined by the vibration, and segregation can be prevented, and the slab 6 having good product characteristics can be cast.
In addition, since only the diaphragms 20 and 20 inserted in the hot water reservoir of the molten metal 4 formed inside the nozzle 3 are vibrated by the vibrators 21 and 21, the hot water surface of the hot water reservoir of the molten metal 4 is not disturbed. Air does not enter the hot water pool of the molten metal 4.

  Further, since the diaphragms 20 and 20 and the contact points P and P are horizontally arranged in a straight line and the contact points P and P are located outside the diaphragms 20 and 20, the contact points P and P The maximum portion (antinode of standing wave) of the combined wave (standing wave) formed by the interference of two waves using the diaphragms 20 and 20 does not reach. Therefore, it is possible to suppress the vibration at the contact points P and P to be small and prevent the solidified shells 5 and 5 from peeling from the rolls 2 and 2. Accordingly, it is possible to prevent wrinkles and the like from being generated on the surface of the cast slab 6 to deteriorate the quality.

[Third embodiment]
Below, with reference to FIG. 6, the external field provision means in 3rd embodiment of this invention is demonstrated.
In the present embodiment, the solidified crystals of the molten metal 4 serving as solidification nuclei are supplied to the center portion of the plate thickness by a plurality of rotating bodies 30, 30. Chemically provide an external field.

  As shown in FIG. 6, the miniaturization means in the present embodiment is composed of a plurality of rotating bodies 30, 30.

The rotators 30... Are members made of a metal having high heat conductivity and excellent heat resistance, durability, and the like, and fine particles 5a that are solidified crystals of the molten metal 4 adhere to the surface. .
The fine grains 5a are solidified crystals of the molten metal 4, that is, solidified shells 5 formed by solidifying the molten metal 4 and are in the form of fine crystal grains.

The rotating bodies 30, 30... Are formed in a substantially cylindrical shape projecting to the outside while gradually reducing the diameter of one end surface, and the molten metal formed inside the nozzle 3 with the projected one end surface facing downward 4 is inserted into the hot water reservoir 4 and disposed above the center of the plate thickness along the axial direction of the roll 2. The rotating bodies 30, 30... Are respectively fixed to an appropriate shaft member and the other end surface (upper end surface). The shaft member is rotated by an arbitrary driving device, so that a predetermined position is obtained at a predetermined position. Rotate in the direction.
Note that the number of rotating bodies 30 is appropriately determined depending on the length of the slab 6 in the axial direction of the roll 2.

In the configuration as described above, the molten metal 4 is solidified by the temperature difference between the molten metal 4 and the rotating bodies 30..., And the formed plurality of fine particles 5 a, 5 a.・ Attaches to the surface of At this time, more fine particles 5a, 5a,... Are formed in a portion close to the rolls 2, 2, which serve as a cooling source for the molten metal 4, that is, in the lower portions of the rotating bodies 30, 30.
When the rotary body 30... Is rotated by the driving device, the fine particles 5 a, 5 a... Adhering to the surface of the rotary body 30.・ Peel off from the surface. The peeled fine particles 5a, 5a,... Fall downward due to their own weight and are taken into the semi-solidified body 7 at the center of the plate thickness. At this time, as in the first embodiment and the second embodiment, since a predetermined disturbance is not transmitted to the contact points P and P, vibration at the contact points P and P is suppressed to a small level.

As described above, the fine grains 5a, 5a,... Grow on the surfaces of the rotators 30, 30. Are peeled in the form of fine crystal grains by the rotation of... And taken into the semi-solidified body 7 at the center of the plate thickness. Therefore, it is possible to generate uniform and equiaxed crystals starting from the fine grains 5a, 5a... That have dropped to the center part of the plate thickness. In addition to miniaturization, segregation can be prevented, and a slab 6 having good product characteristics can be cast.
In addition, the rotating bodies 30 ····· are made of a material of a material in which the fine particles 5a · 5a ··· are easily attached to the surface and the fine particles 5a · 5a ··· are easily peeled off by rotation, or It is preferable to process the surfaces of the rotating bodies 30.

Moreover, you may cool the rotary bodies 30 * 30 ... so that the surface vicinity may become predetermined | prescribed temperature by a suitable cooling means similarly to the rolls 2 * 2. Thereby, the fine particles 5a, 5a,... Can be formed on the surfaces of the rotating bodies 30, 30.
Further, the shape of the rotary bodies 30, 30... May be conical, and the tip may be disposed downward. As a result, the fine particles 5a, 5a,... Adhering to the surfaces of the rotating bodies 30, 30... Can be satisfactorily dropped toward the center of the plate thickness. Refinement of crystal grains can be promoted.
Further, a spiral plate member may be provided on the surface of the rotating body 30. Thereby, as in the first embodiment, the molten metal 4 flows toward the center of the plate thickness, and the crystal grains of the semi-solid body 7 in the center of the plate thickness are refined. Can be satisfactorily made to reach the center portion of the plate thickness, and the refinement of the crystal grains of the semi-solid body 7 at the center portion of the plate thickness can be promoted.

DESCRIPTION OF SYMBOLS 1 Casting machine 2 Roll 3 Nozzle 4 Molten metal 5 Solidified shell 5a Fine grain 6 Cast piece 7 Semi-solid body 10 Core 10a Outflow hole 11 Screw C Plate thickness center point

Claims (8)

A pair of rolls arranged at a predetermined interval and rotating at the same speed in opposite directions;
A cylindrical nozzle for supplying molten metal between the pair of rolls,
A twin-roll continuous casting machine that supplies the molten metal through the nozzle between the pair of rolls and continuously casts a plate-shaped slab,
A twin-roll continuous casting machine comprising means for applying an external field to the molten metal in the center of the plate thickness of the slab, which is inserted into the molten metal reservoir formed inside the nozzle. The external field giving means is
A core that has a hollow shape and is supplied with molten metal;
And a means for flowing molten metal supplied to the inside of the core,
In the core, an outflow hole that communicates the inside and the outside of the core is opened toward the center of the plate thickness of the slab,
The molten metal inside the core flows out from the outflow hole by the flow means, and the molten metal inside and outside the core flows toward the center of the plate thickness of the slab, and the plate thickness of the slab The twin-roll continuous casting machine according to claim 1, wherein the molten metal at the center is stirred.   The twin-roll continuous casting machine according to claim 2, wherein the outflow hole is disposed below a point where the pair of rolls and the molten metal start to contact each other.   The twin roll continuous casting machine according to claim 2 or 3, wherein the core has a predetermined heat insulating property.   The twin-roll continuous casting machine according to any one of claims 2 to 4, wherein the molten metal inside the core is made of a different kind of metal from the molten metal outside the core. The external field giving means is
A plurality of diaphragms for generating waves in the molten metal;
2. The twin-roll type according to claim 1, wherein a portion where the amplitude of a composite wave formed by interference of a plurality of waves generated by the vibration of the plurality of diaphragms is maximized is located at the center of the plate thickness of the slab. Continuous casting machine.   The twin roll continuous casting machine according to claim 6, wherein the plurality of diaphragms are arranged so as to coincide with a height of a point at which the pair of rolls and the molten metal start to contact each other. The external field giving means is
Comprising a rotating body on which a solidified crystal of the molten metal adheres to the surface;
As the rotating body rotates, the solidified crystal of the molten metal peels from the surface of the rotating body,
The twin-roll continuous casting machine according to claim 1, wherein the twin-roll continuous casting machine falls toward a plate thickness center portion of the slab.

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