WO2013031431A1 - Continuous casting equipment for titanium or titanium alloy slab - Google Patents

Abstract

The surface of a molten metal (12) that has been poured into a mold (2) is heated using a plasma arc generated by a plasma torch (7). The surface or the vicinity of the surface of the molten metal (12) is electromagnetically stirred with EMS (8) provided on the sides of the mold (2), thereby making it possible to cast slabs with few surface defects.

Description

Continuous casting equipment for slabs made of titanium or titanium alloy

The present invention relates to a continuous casting apparatus for a slab (slab) made of titanium or a titanium alloy.

The continuous casting of the slab is performed by injecting a metal melted by vacuum arc melting or electron beam melting into a bottomless rectangular mold and pulling it downward while solidifying.

The mold vibration detection device disclosed in Patent Document 1 detects, with a position sensor, vibration in a direction perpendicular to the drawing direction, which is generated when the mold is vibrated in the drawing direction for smooth drawing. The quality of the slab can be stabilized by determining the suitability of casting based on the vibration amount in the direction orthogonal to the drawing direction.

Japanese Unexamined Patent Publication No. 2004-136368

By the way, when a slab made of titanium or a titanium alloy is continuously cast and there are irregularities and scratches on the surface of the slab, the irregularities and scratches become surface defects in the rolling process as the next step. Therefore, it is necessary to remove irregularities and scratches on the surface of the slab by cutting or the like before rolling, which causes a cost increase such as a decrease in yield and an increase in work processes. Therefore, it is required to cast a slab having no irregularities or scratches on the surface.

Here, it is presumed that the surface scratch of the slab is caused by the fact that the solidified shell grows too much in the vicinity of the wall surface of the mold and is exposed to the hot water surface, and the hot water cover is generated. Therefore, in order to suppress the growth of the solidified shell in the vicinity of the wall surface of the mold, it is necessary to increase the heat input to the molten metal surface by increasing the output of the heating device and remelt the solidified shell. However, since heat removal from the mold is large near the molten metal surface, and titanium has low thermal conductivity, there is a possibility that the initial solidified shell cannot be sufficiently dissolved.

Therefore, it is conceivable to melt the initial solidified shell by causing the molten metal to flow near the wall surface of the mold by stirring the molten metal. However, since titanium is an active metal, it is difficult to stir by putting a device such as a propeller into the molten metal or by blowing gas into the molten metal. Further, in electron beam melting, since the electron beam is easily affected by a magnetic field, electromagnetic stirring is difficult.

An object of the present invention is to provide a slab continuous casting apparatus made of titanium or a titanium alloy capable of casting a slab having few defects on the surface.

The continuous casting apparatus for slabs made of titanium or titanium alloy according to the present invention is made by injecting a molten metal obtained by melting titanium or titanium alloy into a bottomless rectangular mold and drawing it downward while solidifying it. A continuous casting apparatus for continuously casting a slab made of an alloy, a plasma arc heating apparatus for heating a molten metal surface injected into the mold by a plasma arc, and electromagnetic induction by an alternating current. And at least one electromagnetic stirring device that stirs the hot water surface or the vicinity of the hot water surface.

According to the above configuration, the molten metal surface injected into the mold is heated by the plasma arc. Since the plasma arc is not affected by the magnetic field except in the vicinity of the plasma jet flow, electromagnetic stirring, which has been difficult with electron beam melting that is easily affected by the magnetic field, can be performed. Therefore, heat is transferred to the solidified shell near the wall surface of the mold by stirring the molten metal surface or the vicinity of the molten metal surface by electromagnetic stirring. Then, since the solidified shell near the wall surface of the mold is warmed, the growth of the solidified shell is suppressed near the wall surface of the mold. Thereby, generation | occurrence | production of the defect in the surface of a slab resulting from the growth of the solidification shell in the wall surface of a casting_mold | template is suppressed. Therefore, it is possible to cast a slab with few defects on the surface.

Further, in the continuous casting apparatus for slabs made of titanium or titanium alloy in the present invention, the electromagnetic stirring device may be provided around the mold. According to said structure, by providing an electromagnetic stirring apparatus around a casting_mold | template, the hot_water | molten_metal surface of a molten metal or the hot-water surface vicinity can be stirred, without inhibiting the heating by a plasma arc.

Also, in the continuous casting apparatus for slabs made of titanium or titanium alloy in the present invention, the electromagnetic stirring device may cause a flow parallel to the wall surface of the mold to occur on or near the molten metal surface. According to the above configuration, the heat transfer coefficient between the solidified shell near the mold wall surface and the molten metal is increased by causing a flow parallel to the mold wall surface or near the molten metal surface. Can do. Thereby, the growth of the solidified shell in the vicinity of the wall surface of the mold can be suitably suppressed.

Moreover, in the continuous casting apparatus for slabs made of titanium or titanium alloy in the present invention, the electromagnetic stirring device may cause a flow swirling in the horizontal direction on the molten metal surface or in the vicinity of the molten metal surface. According to the above configuration, the flow parallel to the mold wall surface is suitable for the molten metal surface or the vicinity of the molten metal surface by causing the flow swirling in the horizontal direction in the mold to be generated near the molten metal surface or the molten metal surface. Can be generated.

Moreover, in the continuous casting apparatus for slabs made of titanium or titanium alloy in the present invention, the electromagnetic stirring device may cause a flow that collides with the wall surface of the mold on or near the molten metal surface. According to the above configuration, the amount of heat input to the solidified shell near the wall surface of the mold can be increased by causing a flow that collides with the wall surface of the mold to occur on the surface of the molten metal or near the surface of the molten metal. Thereby, the growth of the solidified shell in the vicinity of the wall surface of the mold can be suitably suppressed.

Further, in the continuous casting apparatus for slabs made of titanium or a titanium alloy in the present invention, the electromagnetic stirring device may cause the molten metal to flow downward along the wall surface of the mold. According to said structure, the flow swirling in a perpendicular direction arises in a molten metal by making the molten metal produce the flow descend | falling along the wall surface of a casting_mold | template. By the flow swirling in the vertical direction, the flow that collides with the wall surface of the mold can be suitably generated on the molten metal surface or in the vicinity of the molten metal surface.

Further, in the continuous casting apparatus for a slab made of titanium or a titanium alloy in the present invention, the electromagnetic stirring device is caused to generate a pair of flows swirling in the vertical direction and swirling in opposite directions to the molten metal, A pair of flows that collide with two opposing wall surfaces of the mold may be generated on the molten metal surface or in the vicinity of the molten metal surface. According to said structure, the flow swirled in a perpendicular direction produces the flow which collides with the wall surface of a casting_mold | template in the molten metal surface or the vicinity of a molten metal surface. When the flow swirling in the vertical direction is one, the heat input to the solidified shell increases on one of the two opposing wall surfaces of the mold due to the flow that collides with the molten metal surface or the wall surface in the vicinity of the molten metal surface. To do. However, on the other of the two opposing wall surfaces of the mold, the molten metal having a low temperature after transferring heat to the solidified shell near one wall flows in the vicinity, and solidification of the solidified shell proceeds. A pair of flows that swirl in the vertical direction and swirl in opposite directions are generated in the molten metal so that the pair of flows that collide with the two opposing wall surfaces of the mold are respectively in the molten metal surface or in the vicinity of the molten metal surface. Arise. By doing so, the amount of heat input to the solidified shell increases at each of the two opposing wall surfaces of the mold, so that the solidification of the solidified shell does not proceed.

Further, in the continuous casting apparatus for a slab made of titanium or a titanium alloy according to the present invention, the electromagnetic stirring device is provided over the entire circumference of the mold, and flows downward along all the wall surfaces of the mold. It may be generated in the molten metal. According to the above configuration, the electromagnetic stirrer is provided around the entire periphery of the mold, and a flow that descends along all the wall surfaces of the mold is generated in the molten metal. It can be generated at or near the hot water surface. Thereby, the amount of heat input to the solidified shell near the wall surface of the mold can be increased over the entire circumference of the wall surface of the mold.

In the continuous casting apparatus for slabs made of titanium or a titanium alloy according to the present invention, the plasma arc heating device may heat the molten metal surface on the upstream side of the molten metal surface or the flow in the vicinity of the molten metal surface. . When a molten metal having a low temperature flows toward the solidified shell in the vicinity of the wall surface of the mold, solidification of the solidified shell proceeds. Therefore, with the above-described configuration, the molten metal surface on the upstream side of the molten metal surface or the flow in the vicinity of the molten metal surface is heated so that the molten metal having a high temperature flows toward the solidified shell near the wall surface of the mold. . Thereby, the heat transfer coefficient between the solidified shell and the molten metal or the amount of heat input to the solidified shell can be suitably increased.

According to the continuous casting apparatus for slabs made of titanium or titanium alloy according to the present invention, the molten metal surface injected into the mold is heated by the plasma arc, and the molten metal surface or the vicinity of the molten metal surface is stirred by electromagnetic stirring. As a result, heat is transferred to the solidified shell near the wall surface of the mold. Then, since the solidified shell near the wall surface of the mold is warmed, the growth of the solidified shell near the wall surface of the mold is suppressed. Thereby, since generation | occurrence | production of the defect in the surface of a slab resulting from the growth of the solidification shell in the wall surface of a casting_mold | template is suppressed, a slab with few defects can be cast on the surface.

It is a perspective view which shows a continuous casting apparatus. It is sectional drawing of the continuous casting apparatus of FIG. (A) (b) (c) (d) is explanatory drawing showing the generation | occurrence | production mechanism of a surface defect. It is explanatory drawing of electromagnetic stirring, (a) is a top view, (b) is a side view, (c) is AA sectional drawing of (b). It is explanatory drawing of electromagnetic stirring, (a) is a top view, (b) is a side view, (c) is CC sectional drawing of (b). It is explanatory drawing of electromagnetic stirring, (a) is a top view, (b) is a side view, (c) is EE sectional drawing of (b). It is explanatory drawing of electromagnetic stirring, (a) is a top view, (b) is a side view, (c) is GG sectional drawing of (b). (A) is a distribution diagram of flow velocity vectors, and (b) is a partially enlarged view of (a). (A) is a distribution diagram of flow velocity vectors, and (b) is a partially enlarged view of (a). It is explanatory drawing of electromagnetic stirring, (a) is a top view, (b) is a side view, (c) is II sectional drawing of (b).

Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings.

[First Embodiment]
(Construction of continuous casting equipment)
A slab continuous casting apparatus (continuous casting apparatus) 1 made of titanium or a titanium alloy according to the present embodiment includes a mold 2, a cold hearth 3, a raw material charging apparatus 4, a plasma torch 5, as shown in FIG. And a starting block 6. Around the continuous casting apparatus 1 is an inert gas atmosphere made of argon gas, helium gas or the like.

Material input device 4 supplies titanium or titanium alloy material such as sponge titanium and scrap into cold hearth 3. The plasma torch 5 is provided above the cold hearth 3 and generates a plasma arc to melt the raw material in the cold hearth 3. The cold hearth 3 injects the molten metal 12 in which the raw material is melted into the mold 2 from the pouring part 3a. The mold 2 is made of copper and has a bottomless rectangular cross section. The casting mold 2 is cooled by water circulating inside the walls that form four sides. The starting block 6 is moved up and down by a drive unit (not shown) and can close the lower opening of the mold 2.

Further, as shown in FIG. 2, the continuous casting apparatus 1 has a plasma torch (plasma arc heating apparatus) 7 and an EMS (Electro-Magnetic Stirrer) 8. The plasma torch 7 is provided above the mold 2 and heats the surface of the molten metal 12 injected into the mold 2 with a plasma arc. The EMS 8 is an alternating current type, and a plurality of EMSs 8 are provided around the mold 2. The EMS 8 agitates (electromagnetic agitation) the molten metal surface or the vicinity of the molten metal 12 injected into the mold 2 by electromagnetic induction using an alternating current. Details of the electromagnetic stirring will be described later. Note that the EMS 8 also has an action of heating the molten metal 12 by electromagnetic induction.

In the above configuration, the molten metal 12 injected into the mold 2 solidifies from the contact surface with the water-cooled mold 2. Then, the starting block 6 that has closed the lower opening of the mold 2 is pulled downward at a predetermined speed, whereby the slab 11 in which the molten metal 12 has solidified is continuously cast while being pulled downward.

It should be noted that it is difficult to manufacture a titanium alloy because minute components evaporate by electron beam melting in a vacuum atmosphere. However, in plasma arc melting in an inert gas atmosphere, not only pure titanium but also a titanium alloy can be cast.

(Surface defect generation mechanism)
By the way, when the slab 11 made of titanium or a titanium alloy is continuously cast and there are irregularities and scratches on the surface of the slab 11, the irregularities and scratches become surface defects in the subsequent rolling process. Therefore, it is necessary to remove irregularities and scratches on the surface of the slab 11 by cutting or the like before rolling, which causes a cost increase such as a decrease in yield and an increase in work processes. Therefore, it is required to cast the slab 11 having no irregularities or scratches on the surface.

Here, it is presumed that the scratches on the surface of the slab 11 are caused by the fact that the solidified shell that has grown too much in the vicinity of the wall surface of the mold 2 is exposed to the molten metal surface and the covered water is generated. The mechanism will be described with reference to FIGS. First, as shown in FIG. 3A, the solidified shell 13 grows in the vicinity of the wall surface of the mold 2. Next, as shown in FIG. 3B, the solidified shell 13 is lowered by drawing in a state where the molten metal 12 is not supplied near the wall surface of the mold 2. Then, as shown in FIG. 3C, the molten metal 12 flows onto the solidified shell 13 because the upper end of the solidified shell 13 is lower than the liquid level of the molten metal 12. As shown in FIG. 3 (d), the molten metal 12 that has flowed onto the solidified shell 13 is solidified to become the solidified shell 13, so that a surface defect occurs in the solidified shell 13. This becomes a surface defect of the slab 11.

(Electromagnetic stirring)
In the present embodiment, as shown in FIG. 2, in order to suppress the occurrence of defects on the surface of the slab 11, the molten metal surface of the molten metal 12 or the vicinity of the molten metal surface is stirred by electromagnetic stirring by the EMS 8. Since the plasma arc by the plasma torch 7 is not affected by the magnetic field except in the vicinity of the plasma jet flow, electromagnetic stirring that is difficult in the electron beam melting that is easily affected by the magnetic field is possible.

In the present embodiment, as shown in FIGS. 4A and 4B, three EMSs 8 are arranged on the side of the long side of the mold 2. These EMSs 8 are formed by winding an EMS coil in a vertical direction around a coil iron core, and cause the molten metal 12 to flow in a horizontal direction by electromagnetic induction.

4A, the three EMSs 8a, 8a, 8a arranged side by side on the long side of the mold 2 cause the molten metal 12 to flow to the right side in the drawing. On the other hand, the three EMSs 8b, 8b, and 8b arranged side by side on the long side of the mold 2 on the lower side in the drawing of FIG. Thereby, the flow B swirling in the horizontal direction is generated on the surface of the molten metal 12 or in the vicinity of the surface of the molten metal. As a result, a flow parallel to the wall surface of the mold 2 is generated on the surface of the molten metal 12 or in the vicinity of the surface of the molten metal. When the molten metal 12 heated by the plasma arc touches the solidified shell 13 near the wall surface of the mold 2, the heat transfer coefficient between the solidified shell 13 and the molten metal 12 increases. Therefore, the growth of the solidified shell 13 in the vicinity of the wall surface of the mold 2 is suppressed.

Further, the plasma torch 7 is arranged so as to heat the molten metal 12 or the molten metal 12 on the upstream side of the flow near the molten metal surface. If the molten metal 12 having a low temperature flows toward the solidified shell 13 near the wall surface of the mold 2, solidification of the solidified shell 13 proceeds. Therefore, in the present embodiment, the molten metal surface of the molten metal 12 or the molten metal surface on the upstream side of the flow near the molten metal surface is heated by a plasma arc. Thereby, since the molten metal 12 with a high temperature flows toward the solidified shell 13 near the wall surface of the mold 2, the heat transfer coefficient between the solidified shell 13 and the molten metal 12 is suitably increased.

In addition, in the four corners of the rectangular mold 2, the molten metal 12 is cooled from the two surfaces of the short side and the long side, so the molten metal 12 is easier to cool than the other parts. Moreover, since the four corners of the mold 2 are separated from the pouring part 3a, the hot molten metal 12 is difficult to reach. However, since the AC type EMS 8 can exert a local force and has high controllability, it is possible to flow the high-temperature molten metal 12 at the four corners of the mold 2.

Even if the heating conditions by the plasma arc and the cooling conditions by the mold 2 fluctuate during continuous casting, the surface defects are always maintained by controlling the current and frequency of the EMS 8 to control the speed of electromagnetic stirring and the application position of the magnetic field. It is possible to cast a slab 11 having no surface. The same applies to the case where the heat input conditions change greatly, such as in the initial and final stages of continuous casting.

(effect)
As described above, the continuous casting apparatus 1 according to this embodiment heats the molten metal surface of the molten metal 12 injected into the mold 2 with a plasma arc. Since the plasma arc is not affected by the magnetic field except in the vicinity of the plasma jet flow, electromagnetic stirring, which has been difficult with electron beam melting that is easily affected by the magnetic field, can be performed. Therefore, heat is transferred to the solidified shell 13 near the wall surface of the mold 2 by stirring the molten metal surface or the vicinity of the molten metal surface by electromagnetic stirring. Then, since the solidified shell 13 near the wall surface of the mold 2 is warmed, the growth of the solidified shell 13 near the wall surface of the mold 2 is suppressed. Thereby, generation | occurrence | production of the defect of the surface of the slab 11 resulting from the growth of the solidification shell 13 in the wall surface vicinity of the casting_mold | template 2 is suppressed. Therefore, the slab 11 with few defects on the surface can be cast.

Further, by providing the EMS 8 around the mold 2, the molten metal 12 or the vicinity of the molten metal can be stirred without inhibiting the heating by the plasma arc.

Further, by generating a flow parallel to the wall surface of the mold 2 on or near the molten metal surface, the heat transfer coefficient between the solidified shell 13 near the wall surface of the mold 2 and the molten metal 12 can be increased. it can. Thereby, the growth of the solidified shell 13 in the vicinity of the wall surface of the mold 2 can be suitably suppressed.

Further, by causing the flow B swirling in the mold 2 in the horizontal direction to be generated on the surface of the molten metal 12 or in the vicinity of the molten metal surface, the flow parallel to the wall surface of the mold 2 is suitably applied to the surface of the molten metal 12 or the molten metal surface. Can be generated.

Further, when the molten metal 12 having a low temperature flows toward the solidified shell 13 in the vicinity of the wall surface of the mold 2, solidification of the solidified shell 13 proceeds. Therefore, the molten metal 12 on the upstream side of the molten metal 12 or the flow in the vicinity of the molten metal surface is heated with a plasma arc so that the molten metal 12 having a high temperature flows toward the solidified shell 13 near the wall surface of the mold 2. To. Thereby, the heat transfer coefficient between the solidified shell 13 and the molten metal 12 can be suitably increased.

[Second Embodiment]
(Electromagnetic stirring)
Next, a continuous casting apparatus 201 according to the second embodiment of the present invention will be described. In addition, about the same component as the component mentioned above, the same reference number is attached | subjected and the description is abbreviate | omitted. As shown in FIGS. 5A and 5B, the continuous casting apparatus 201 of the present embodiment is configured to melt a pair of flows D1 and D2 in which the EMS 8 collides with the opposing two short-side wall surfaces of the mold 2, respectively. It differs from the continuous casting apparatus 1 of 1st Embodiment by the point made to produce in the hot_water | molten_metal surface of 12 or a hot-water surface vicinity.

As shown in FIG. 5 (a), two EMSs 8 are arranged on the side of the long side of the mold 2. These EMSs 8 are formed by winding an EMS coil in a vertical direction around a coil iron core, and cause the molten metal 12 to flow in a horizontal direction by electromagnetic induction. On the right side in the drawing of FIG. 5 (a), the two EMSs 8a and 8a facing each other with the mold 2 in between flow the molten metal 12 on the right side in the drawing. As a result, as shown in FIG. 5A, a flow D <b> 1 that collides with the wall surface forming the short side on the right side of the mold 2 in the drawing occurs in the vicinity of the molten metal surface of the molten metal 12. As shown in FIG. 5B, the flow D1 that has collided with the wall surface then descends along the wall surface forming the short side and becomes a flow D1 'that swirls in the vertical direction. Then, the flow D <b> 1 ′ that swirls in the vertical direction generates a flow D <b> 1 that collides with the wall surface that forms the short side on the right side of the mold 2 in the drawing, on or near the molten metal surface.

Further, on the left side in the drawing of FIG. 5A, the two EMSs 8b and 8b facing each other with the mold 2 sandwiching the molten metal 12 flow on the left side in the drawing. As a result, as shown in FIG. 5A, a flow D <b> 2 that collides with the wall surface forming the short side on the left side of the mold 2 in the drawing is generated on the molten metal surface or in the vicinity of the molten metal surface. As shown in FIG. 5B, the flow D2 that has collided with the wall surface then descends along the wall surface forming the short side and becomes a flow D2 'that swirls in the vertical direction. Then, the flow D <b> 2 ′ swirling in the vertical direction generates a flow D <b> 2 that collides with the wall surface forming the short side on the left side of the mold 2 on the molten metal 12 or in the vicinity of the molten metal surface.

A pair of flows D1 and D2 that collide with the opposing two short side wall surfaces of the mold 2 in the vicinity of the molten metal 12 or near the molten metal surface, to the solidified shell 13 near the short side wall surface of the mold 2. The amount of heat input increases. Therefore, the growth of the solidified shell 13 in the vicinity of the wall surface on the short side of the mold 2 is suppressed.

In addition, the pair of flows D1 and D2 that collide with the opposing two short side walls of the mold 2 are swirled in the vertical direction and in the opposite directions to the pair of flows D1 ′ and D2 ′, respectively. Twelve. The pair of flows D1 ′ and D2 ′ swirling in the vertical direction are the same as the pair of flows D1 and D2 that collide with the opposing two short-side walls of the mold 2, respectively. To cause. Here, if there is one flow swirling in the vertical direction, the flow to the solidified shell 13 is caused by the flow that collides with the wall surface of the molten metal 12 or in the vicinity of the molten metal surface on one of the two short side walls. The amount of heat input increases. However, in the vicinity of the other of the wall surfaces on the two short sides, the molten metal 12 having a low temperature after transferring the heat amount to the solidified shell 13 in the vicinity of the one wall surface flows, so that the solidification of the solidified shell 13 proceeds. . Therefore, a pair of flows D1, which collide with two opposing wall surfaces of the mold 2 by causing the molten metal 12 to generate a pair of flows D1 ′, D2 ′ which swirl in the vertical direction and swirl in opposite directions. D2 is generated on or near the surface of the molten metal. By doing so, the amount of heat input to the solidified shell 13 increases on each of the two opposing short side walls of the mold 2, so that the solidification of the solidified shell 13 does not proceed.

Further, the plasma torch 7 is arranged so as to heat the molten metal 12 or the molten metal 12 on the upstream side of the flow near the molten metal surface. Thereby, since the molten metal 12 having a high temperature flows toward the solidified shell 13 near the wall surface on the short side of the mold 2, the amount of heat input to the solidified shell 13 near the wall surface on the short side of the mold 2 is suitably increased. .

Note that the pair of flows D1 and D2 that collide with the wall surface on the short side of the mold 2 includes a flow parallel to the wall surface on the long side of the mold 2. Therefore, the heat transfer coefficient between the solidified shell 13 and the molten metal 12 increases on the long side wall surface of the mold 2. Therefore, the growth of the solidified shell 13 in the vicinity of the long-side wall surface of the mold 2 is suppressed.

(effect)
As described above, according to the continuous casting apparatus 201 according to the present embodiment, by causing the flows D1 and D2 that collide with the wall surface on the short side of the mold 2 to occur on the molten metal 12 or near the molten metal surface, The amount of heat input to the solidified shell 13 near the wall surface on the short side of the mold 2 can be increased. Thereby, the growth of the solidified shell 13 in the vicinity of the wall surface on the short side of the mold 2 can be suitably suppressed.

Further, the flows D1 'and D2' swirling in the vertical direction cause the flows D1 and D2 that collide with the wall surface of the mold 2 to be generated on the molten metal 12 or in the vicinity of the molten metal surface. If the flow swirling in the vertical direction is one, the solidified shell is caused by a flow that collides with the wall surface of the molten metal 12 on the surface of the molten metal 12 or in the vicinity of the molten metal surface, on one of the two opposed short side walls. The heat input to 13 increases. However, on the other of the opposing two short side walls of the mold 2, the molten metal 12 having a low temperature after transferring heat to the solidified shell 13 in the vicinity of the one wall flows in the vicinity of the solidified shell 13. Solidification of the will progress. Therefore, a pair of flows D1 ′ and D2 ′ that swirl in the vertical direction and swirl in opposite directions are generated in the molten metal 12 so as to collide with the two opposing short side walls of the mold 2 respectively. Flows D1 and D2 are generated on the surface of the molten metal 12 or in the vicinity of the surface of the molten metal. By doing so, the amount of heat input to the solidified shell 13 increases in each of the two opposing short side walls of the mold 2, so that the solidification of the solidified shell 13 does not proceed.

[Third Embodiment]
(Electromagnetic stirring)
Next, a continuous casting apparatus 301 according to the third embodiment of the present invention will be described. In addition, about the same component as the component mentioned above, the same reference number is attached | subjected and the description is abbreviate | omitted. In the continuous casting apparatus 301 of this embodiment, as shown in FIGS. 6A and 6B, one EMS 8 is disposed on the side of the two short side walls facing each other of the mold 2. Thereby, the continuous casting apparatus 301 of this embodiment differs from the continuous casting apparatus 201 of 2nd Embodiment by the point which produces the flow which descends | falls along the wall surface by the side of the short side of the casting_mold | template 2.

The EMS 8 is formed by winding an EMS coil in a horizontal direction around a coil iron core, and causes the molten metal 12 to flow downward in the vertical direction by electromagnetic induction. The EMS 8a arranged on the right side in FIG. 6B causes the molten metal 12 to flow downward along the wall surface forming the short side on the right side of the mold 2 in the drawing. Moreover, EMS8b arrange | positioned at the left side in the figure of FIG.6 (b) produces the flow which descends | falls along the wall surface which makes the short side of the left side of the casting_mold | template 2 in the figure. As shown in FIG. 6B, these flows generate a pair of flows F1 'and F2' that swirl in the vertical direction and swirl in opposite directions.

As shown in FIG. 6 (b), the flow F1 'generates a flow that collides with the wall surface of the mold 2 on the right side in the drawing in the vicinity of the molten metal surface or in the vicinity of the molten metal surface. Therefore, as shown in FIG. 6A, a flow F <b> 1 that collides with the wall surface forming the short side on the right side of the mold 2 in the drawing is generated on the molten metal 12 or in the vicinity of the molten metal surface. Further, as shown in FIG. 6B, the flow F2 ′ is a flow swirling in the opposite direction to the flow F1 ′, and is short on the left side of the mold 2 in the drawing at the molten metal surface or in the vicinity of the molten metal surface. A flow that collides with the wall surface forming the side is generated. Therefore, as shown in FIG. 6A, a flow F <b> 2 that collides with the wall surface forming the short side on the left side of the mold 2 in the drawing is generated on the molten metal 12 or in the vicinity of the molten metal surface.

The amount of heat input to the solidified shell 13 near the short side wall of the mold 2 by a pair of flows F1 and F2 that collide with the two short side walls of the mold 2 on the molten metal 12 or in the vicinity of the molten metal surface, respectively. Will increase. Therefore, the growth of the solidified shell 13 in the vicinity of the wall surface on the short side of the mold 2 is suppressed.

Further, the plasma torch 7 is arranged so as to heat the molten metal 12 or the molten metal 12 on the upstream side of the flow near the molten metal surface. Thereby, since the molten metal 12 having a high temperature flows toward the solidified shell 13 near the wall surface on the short side of the mold 2, the amount of heat input to the solidified shell 13 near the wall surface on the short side of the mold 2 is suitably increased. .

(effect)
As described above, according to the continuous casting apparatus 301 according to the present embodiment, the flow F1 ′ swirling in the vertical direction is generated by causing the molten metal 12 to flow down along the wall surface on the short side of the mold 2. , F2 'occurs in the molten metal 12. With the flows F1 ′ and F2 ′ swirling in the vertical direction, the flows F1 and F2 that collide with the wall surface of the mold 2 can be suitably generated on the molten metal 12 or in the vicinity of the molten metal surface.

[Fourth Embodiment]
(Electromagnetic stirring)
Next, a continuous casting apparatus 401 according to the fourth embodiment of the present invention will be described. In addition, about the same component as the component mentioned above, the same reference number is attached | subjected and the description is abbreviate | omitted. The continuous casting apparatus 401 of this embodiment is different from the continuous casting apparatus 301 of the third embodiment in that the EMS 8 is along the wall surface on the long side of the mold 2 as shown in FIGS. This is a point in which a downward flow is generated in the molten metal 12.

As shown in FIG. 7 (a), two EMSs 8 are arranged on the side of the long side of the mold 2. The EMS 8 is formed by winding an EMS coil around a coil iron core in the horizontal direction. The EMS 8 causes the molten metal 12 to flow downward in the vertical direction by electromagnetic induction. On the right side in the drawing of FIG. 7C, the two EMSs 8a and 8a arranged side by side on the long side of the mold 2 flow downward along the wall surface forming the long side on the right side of the mold 2 in the drawing. It is generated in the molten metal 12. 7C, the two EMSs 8b and 8b arranged side by side on the long side of the mold 2 are lowered along the wall surface forming the long side on the left side of the mold 2 in the figure. A flow is generated in the melt 12. As shown in FIG. 7C, these flows generate a pair of flows H1 'and H2' that swirl in the vertical direction and swirl in opposite directions.

As shown in FIG. 7C, the flow H1 'generates a flow that collides with the wall surface of the mold 2 on the right side in the drawing in the vicinity of the molten metal surface or in the molten metal surface. Therefore, as shown in FIG. 7A, a flow H <b> 1 that collides with the wall surface that forms the long side on the upper side in the drawing of the mold 2 is generated on the surface of the molten metal 12 or in the vicinity of the molten metal surface. Further, as shown in FIG. 7 (c), the flow H2 ′ is a flow swirling in the opposite direction to the flow H1 ′, and the length of the left side of the mold 2 in the drawing is near the molten metal surface or the molten metal surface. A flow that collides with the wall surface forming the side is generated. Therefore, as shown in FIG. 7A, a flow H <b> 2 that collides with the wall surface that forms the long side of the lower side of the mold 2 in the figure is generated on the molten metal 12 or in the vicinity of the molten metal surface.

The amount of heat input to the solidified shell 13 near the long side wall of the mold 2 by the pair of flows H1 and H2 that respectively collide with the two long side wall surfaces of the mold 2 at or near the molten metal surface of the molten metal 12. Will increase. Therefore, the growth of the solidified shell 13 is suppressed in the vicinity of the long side wall surface of the mold 2.

Further, the plasma torch 7 is arranged so as to heat the molten metal 12 or the molten metal 12 on the upstream side of the flow near the molten metal surface. Thereby, the molten metal 12 having a high temperature flows toward the solidified shell 13 near the wall surface on the long side of the mold 2, so that the amount of heat input to the solidified shell 13 near the wall surface on the long side of the mold 2 is suitably increased. .

(Comparison of stirring conditions)
Here, using the flow velocity vector distribution diagrams shown in FIGS. 8A, 8B, 9A, and 9B, the stirring state of the molten metal 12 in the continuous casting apparatus 401 of the present embodiment is determined as follows. This will be described in comparison with a reverse comparative example. In the continuous casting apparatus 401 of this embodiment, as shown to Fig.8 (a), by making the molten metal 12 produce a pair of flow swirling in the vertical direction and swirling in opposite directions, A pair of flows that collide with the two long side walls are generated on the surface of the molten metal 12 or in the vicinity of the surface of the molten metal. As can be seen from FIG. 8B, which is a partially enlarged view of FIG. 8A, the molten metal 12 having a high temperature flows toward the solidified shell 13 near the wall surface on the long side of the mold 2. As a result, the amount of heat input to the solidified shell 13 in the vicinity of the wall surface on the long side of the mold 2 is increased, and the progress of solidification of the solidified shell 13 is suppressed.

On the other hand, in the comparative example, as shown in FIG. 9A, a pair of flows swirling in the vertical direction and swirling in opposite directions are generated in the molten metal 12. However, in the comparative example, contrary to the continuous casting apparatus 401 of the present embodiment, a pair of flows from each of the two long side wall surfaces of the mold 2 toward the center of the mold 2 are used. It is generated in the vicinity. As can be seen from FIG. 9B, which is a partially enlarged view of FIG. 9A, the molten metal 12 having a low temperature flows toward the solidified shell 13 in the vicinity of the wall surface on the long side of the mold 2. Thereby, the amount of heat input to the solidified shell 13 near the wall surface on the long side of the mold 2 is reduced, and the solidification of the solidified shell 13 is promoted.

In this way, in order to cause the molten metal 12 to generate a pair of flows swirling in the vertical direction and swirling in opposite directions, the wall surfaces on the two long sides facing the mold 2 as in the present embodiment. It can be seen that it is effective to generate a pair of flows that collide with each other at or near the surface of the molten metal 12. Therefore, in the present embodiment, the solidified shell 13 has a pair of flows from the wall surfaces on the two long sides of the mold 2 toward the center of the mold 2 in the vicinity of the molten metal surface or in the vicinity of the molten metal surface. It is effective in preventing the progress of coagulation. The same applies to the second embodiment and the third embodiment.

[Fifth Embodiment]
(Electromagnetic stirring)
Next, a continuous casting apparatus 501 according to a fifth embodiment of the present invention will be described. In addition, about the same component as the component mentioned above, the same reference number is attached | subjected and the description is abbreviate | omitted. The continuous casting apparatus 501 of the present embodiment is different from the continuous casting apparatus 1 of the first embodiment in that an EMS 508 is provided around the entire periphery of the mold 2 as shown in FIG. This is a point that causes the molten metal 12 to flow downward.

The EMS 508 is formed by winding an EMS coil around a coil iron core in the horizontal direction, and causes the molten metal 12 to flow downward in the vertical direction by electromagnetic induction. Thereby, in the molten metal 12, a flow that descends along all the wall surfaces of the mold 2 is generated, and this flow generates a flow that swirls in the vertical direction. Since the flow swirling in the vertical direction is directed in all directions, as shown in FIG. 8A, a flow J that collides with all the wall surfaces of the mold 2 on or near the molten metal surface of the molten metal 12. Occurs. This increases the amount of heat input to the solidified shell 13 over the entire circumference of the wall surface of the mold 2.

Further, the plasma torch 7 is arranged so as to heat the molten metal 12 or the molten metal 12 on the upstream side of the flow near the molten metal surface. Thereby, since the molten metal 12 having a high temperature flows toward the solidified shell 13 near the wall surface of the mold 2, the amount of heat input to the solidified shell 13 near the wall surface of the mold 2 is suitably increased.

(effect)
As described above, in the continuous casting apparatus 501 according to the present embodiment, the EMS 508 is provided around the mold 2 over the entire circumference. Thus, according to the continuous casting apparatus 501 according to the present embodiment, the flow J that collides with all the wall surfaces of the mold 2 is generated by causing the molten metal to flow down along all the wall surfaces of the mold 2. It can be generated on the surface of the molten metal 12 or in the vicinity of the surface of the molten metal. Thereby, the amount of heat input to the solidified shell 13 near the wall surface of the mold 2 can be increased over the entire circumference of the wall surface of the mold 2.

(Modification of this embodiment)
Although the embodiments of the present invention have been described above, they are merely illustrative examples and do not particularly limit the present invention. The specific configuration and the like can be appropriately changed in design. Further, the actions and effects described in the embodiments of the invention are merely a list of the most preferable actions and effects resulting from the present invention. The operations and effects of the present invention are not limited to those described in the embodiment of the present invention.

For example, a flux feeding device for feeding flux to the molten metal surface of the molten metal 12 in the mold 2 may be further provided. Due to the lubrication effect of the flux entering between the mold 2 and the solidified shell 13, the occurrence of defects on the surface of the slab 11 can be further suppressed.

This application is based on a Japanese patent application (Japanese Patent Application No. 2011-192062) filed on September 2, 2011, the contents of which are incorporated herein by reference.

1, 201, 301, 401, 501 Continuous casting device 2 Mold 3 Cold hearth 3a Pouring part 4 Raw material charging device 5 Plasma torch 6 Starting block 7 Plasma torch (plasma arc heating device)
8 EMS (Electromagnetic Stirrer)
11 Slab 12 Molten metal 13 Solidified shell

Claims (10)

A continuous casting apparatus for continuously casting a slab made of titanium or a titanium alloy by injecting a molten metal in which titanium or a titanium alloy is melted into a bottomless rectangular mold and solidifying the molten metal. ,
A plasma arc heating apparatus for heating the molten metal surface injected into the mold with a plasma arc;
A continuous casting apparatus for slabs made of titanium or a titanium alloy, comprising: at least one electromagnetic stirrer that stirs the molten metal surface or the vicinity of the molten metal surface by electromagnetic induction using an alternating current. The slab continuous casting apparatus made of titanium or a titanium alloy according to claim 1, wherein the electromagnetic stirring device is provided around the mold. 3. The continuous slab made of titanium or a titanium alloy according to claim 1, wherein the electromagnetic stirrer generates a flow parallel to the wall surface of the mold on the molten metal surface or in the vicinity of the molten metal surface. Casting equipment. 4. The continuous casting apparatus for a slab made of titanium or a titanium alloy according to claim 3, wherein the electromagnetic stirring device generates a flow swirling in a horizontal direction on the surface of the molten metal or in the vicinity of the surface of the molten metal. 3. The continuous slab made of titanium or a titanium alloy according to claim 1, wherein the electromagnetic stirrer generates a flow that collides with a wall surface of the mold on the molten metal surface or in the vicinity of the molten metal surface. Casting equipment. The continuous casting apparatus for a slab made of titanium or a titanium alloy according to claim 5, wherein the electromagnetic stirrer causes the molten metal to flow downward along the wall surface of the mold. The electromagnetic stirrer generates a pair of flows that swirl in the vertical direction and swirl in opposite directions in the molten metal, thereby causing a pair of flows that collide with two opposing wall surfaces of the mold to flow into the molten metal. The continuous casting apparatus for slabs made of titanium or a titanium alloy according to claim 5, wherein the continuous casting apparatus is produced at or near the molten metal surface. The electromagnetic stirrer is provided over the entire circumference of the mold,
The said electromagnetic stirring apparatus produces the flow which descends along all the wall surfaces of the said casting_mold | template in the said molten metal, The continuous casting apparatus of the slab which consists of titanium or a titanium alloy of Claim 6 characterized by the above-mentioned. The said plasma arc heating apparatus heats the molten metal surface of the molten metal on the upstream side of the molten metal surface or the flow in the vicinity of the molten metal surface, and is a continuous slab made of titanium or a titanium alloy according to claim 3. Casting equipment. The continuous plasma slab made of titanium or a titanium alloy according to claim 5, wherein the plasma arc heating device heats the molten metal surface on the upstream side of the molten metal surface or in the vicinity of the molten metal surface. Casting equipment.

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