WO2018190387A1 - Molten metal agitating device and continuous casting device system provided with same - Google Patents

Abstract

[Problem] In continuous casting, to provide a product having excellent quality with high productivity. [Solution] Molten metal from a melting furnace is agitated and driven by means of a Lorentz force resulting from an intersection of a line of magnetic force from a magnet and a direct current, and is fed to a mold while the quality of the molten metal is improved, or the molten metal immediately before solidification in the mold is agitated and driven by said Lorentz force to homogenize the temperature of the molten metal immediately before solidification in the mold, thereby ultimately obtaining a high-quality product and providing a means for cooling the magnet and maintaining the performance of the magnet.

Description

Molten metal stirrer and continuous casting system provided with the same

The present invention relates to a molten metal stirring apparatus and a continuous casting apparatus system including the molten metal stirring apparatus.

Conventionally, a metal melt having conductivity (conductivity), that is, a non-ferrous metal (for example, Al, Cu, Zn or Si, or at least two of these alloys, Mg alloy, etc.) or other than a non-ferrous metal It has been practiced to obtain a product (round bar-shaped ingot or the like) by continuously casting a molten metal.

In this continuous casting, for example, it has been generally adopted that a molten metal is guided from a melting furnace with a scissors and poured into a mold.

However, only the inventor of the present invention has the following opinions with respect to the conventional manufacturing method.

That is, first, when the molten metal enters the mold, the molten metal entrains air while falling in the air. For this reason, it is inevitable that the quality of the product deteriorates.

Furthermore, when the product obtained from the mold is large (especially when the cross-sectional area is large), the cooling rate of the molten metal differs greatly between the peripheral portion and the central portion of the product. That is, the molten metal is rapidly cooled in the peripheral portion of the product, whereas the molten metal is cooled more slowly in the central portion. Thereby, the crystal structure of the metal in the peripheral part and the central part of the product is greatly different. As a result, it is inevitable that the mechanical characteristics of the product are greatly impaired.

Conventionally, those skilled in the art other than the present inventor have not had any great dissatisfaction or problems with regard to product quality or production efficiency. For this reason, those skilled in the art other than the present inventor have no awareness of the problem of having to devise and improve the manufacturing apparatus and manufacturing method in terms of product quality and production efficiency. However, as described above, only the present inventor among those skilled in the art has an original problem awareness (issue) as described above. In other words, the present inventor has had the problem that, as an engineer, a better product must be provided with higher efficiency than now.

The molten metal stirring device of the embodiment of the present invention is
A molten metal stirring device for stirring molten metal in the mold or molten metal in the mold in a continuous casting apparatus for continuously forming a product by flowing a molten metal of conductive metal into the mold,
A cylindrical case with an open top that is immersed in the molten metal, and a pipe stored in the case,
The case has an outer cylinder and an inner cylinder accommodated in the outer cylinder, and a gap for flowing cooling air is formed between the outer cylinder and the inner cylinder. Has a vent hole communicating the inside of the inner cylinder and the gap, and constitutes a cooling air passage from the inner cylinder to the gap via the vent hole,
Inside the inner cylinder, a magnetic field device in which the pipe is inserted is housed, and the magnetic field device has a magnetic field line from the magnetic field device passing through the inner cylinder and the outer cylinder to the molten metal, Or, the magnetic lines of force that run in the molten metal penetrate through the inner cylinder and the outer cylinder and reach the magnetic field device, and are magnetized with strength.
Furthermore, the first electrode, penetrating the inner cylinder and the outer cylinder, one end is exposed in the inner cylinder, the other end is exposed outside the outer cylinder and can contact the molten metal, The one end of the first electrode is electrically connected to a lead wire body running in the pipe;
Furthermore, it has the 2nd electrode attached to the said outer cylinder, and the attachment position to the said outer cylinder of the said 2nd electrode is via a molten metal between the said 2nd electrode and the said 1st electrode. It is set at a position where a flowing current crosses the magnetic field lines and generates a Lorentz force that rotationally drives the molten metal around the vertical axis.
Configured as a thing.

The molten metal stirring device of the embodiment of the present invention is
A molten metal stirring device for stirring molten metal in the mold or molten metal in the mold in a continuous casting apparatus for continuously forming a product by flowing a molten metal of conductive metal into the mold,
A cylindrical case with an open top that is immersed in the molten metal; and a pipe that is accommodated in the case, and a communication gap is formed between the lower end of the pipe and the inside of the bottom surface of the case. The interior of the pipe communicates with the interior of the case through the communication gap to form a cooling air passage.
A magnetic field device in which the pipe is inserted is accommodated in the inner cylinder, and the magnetic field device has a magnetic field line from the magnetic field device passing through the case to the molten metal, or in the molten metal. The magnetic field lines that run through the case reach the magnetic field device, and are magnetized in strength.
Further, the first electrode has a first electrode that penetrates the case, one end is exposed to the case, and the other end is exposed to the outside of the case and can be in contact with the molten metal, and the one end of the first electrode Is electrically connected to the lead wire running through the pipe,
Furthermore, it has the 2nd electrode attached to the said case, The attachment position to the said case of the said 2nd electrode is the electric current which flows through a molten metal between the said 2nd electrode and the said 1st electrode. Is set at a position to generate Lorentz force that crosses the magnetic field lines and drives the molten metal to rotate about the vertical axis.
Configured as a thing.

The continuous casting apparatus system of the embodiment of the present invention is:
Any one of the molten metal stirrers, a bowl for introducing the molten metal from the melting furnace, and a mold attached in a state where a molten metal inlet is in communication with the bottom surface of the bowl, the molten metal stirring apparatus has the lower end side at the lower end side. It is configured as being incorporated in a state where it is inserted into the molten metal lead-out path in the dredger.

BRIEF DESCRIPTION OF THE DRAWINGS Partial longitudinal cross-section explanatory drawing which shows the whole structure of the continuous casting apparatus as the 1st Embodiment of this invention. FIG. 2 is a longitudinal explanatory view of a molten metal stirring device in the apparatus of FIG. Partial longitudinal cross-section explanatory drawing which shows the whole structure of the continuous casting apparatus of 7th Embodiment corresponding to embodiment of FIG. FIG. 2B is an explanatory diagram showing a current flow path in the embodiment of FIG. 2A. Operation | movement explanatory drawing explaining operation | movement of the molten metal stirring apparatus in the apparatus of FIG. The partial longitudinal cross-section explanatory drawing which shows the whole structure of the continuous casting apparatus as the 2nd Embodiment of this invention. Operation | movement explanatory drawing explaining operation | movement of the molten metal stirring apparatus in the apparatus of FIG. The partial longitudinal cross-section explanatory drawing which shows the whole structure of the continuous casting apparatus as the 3rd Embodiment of this invention. Operation | movement explanatory drawing explaining operation | movement of the molten metal stirring apparatus in the apparatus of FIG. The longitudinal section explanatory drawing of the magnetic field apparatus of the molten metal stirring apparatus in the apparatus of FIG. 1, FIG. Plane | planar explanatory drawing of the magnetic field apparatus of the molten metal stirring apparatus in the apparatus of FIG. 1, FIG. FIG. 3 is a longitudinal explanatory view of a modification of the magnetic field device of the molten metal stirring device in the device of FIGS. Plane explanatory drawing of the modification of the magnetic field apparatus of the molten metal stirring apparatus in the apparatus of FIG. 1, FIG. FIG. 6 is a longitudinal explanatory view of a magnetic field device of a molten metal stirring device in the devices of FIGS. 4 and 5. Plane explanatory drawing of the magnetic field apparatus of the molten metal stirring apparatus in the apparatus of FIG. 4, FIG. Longitudinal explanatory drawing of the magnetic field apparatus of the molten metal stirring apparatus in the apparatus of FIG. 6, FIG. Plane | planar explanatory drawing of the magnetic field apparatus of the molten metal stirring apparatus in the apparatus of FIG. 6, FIG. Explanatory drawing of the bottom of the magnetic field apparatus of the molten metal stirring apparatus in the apparatus of FIG. 6, FIG. Partial longitudinal cross-section explanatory drawing which shows the whole structure of the continuous casting apparatus as the 4th Embodiment of this invention. Longitudinal explanatory drawing which longitudinally cuts the molten metal stirring apparatus in the apparatus of FIG. Partial longitudinal cross-section explanatory drawing which shows the whole structure of the continuous casting apparatus in 8th Embodiment corresponding to embodiment of FIG. Operation | movement explanatory drawing explaining operation | movement of the molten metal stirring apparatus in the apparatus of FIG. 12, FIG. Structural operation explanatory drawing explaining the structure and operation | movement of the molten metal stirring apparatus used for the continuous casting apparatus as the 5th Embodiment of this invention. Structural operation explanatory drawing explaining a structure and operation | movement of the molten metal stirring apparatus used for the continuous casting apparatus as the 6th Embodiment of this invention. The partial longitudinal cross-section explanatory drawing of one continuous prototype obtained by switching the state which removed the molten metal stirring apparatus of FIG. 1, and the state which uses a molten metal stirring apparatus as it is. 18 is a longitudinal explanatory view showing a part of the prototype of FIG. FIG. 18 is a longitudinal explanatory view showing a different part of the prototype of FIG. 17. FIG. 18 is a longitudinal explanatory view showing a further different part of the prototype of FIG. 17. FIG. 19 is a longitudinal explanatory view showing a manufacturing process of a part of the prototype of FIG. 18. FIG. 20 is a longitudinal explanatory view showing a manufacturing process of a part of the prototype of FIG. 19. FIG. 21 is a longitudinal explanatory view showing a part of the manufacturing process of the prototype of FIG. 20. Furthermore, longitudinal explanatory drawing which shows the manufacture process of the prototype for demonstrating a different experiment. The temperature distribution explanatory drawing which shows the temperature distribution of the molten metal (liquid), semi-solidified layer part, prototype (solid) in the manufacturing process of FIG. FIG. 25 is a longitudinal explanatory view showing a positional relationship of a sample (first test piece) taken out from the prototype corresponding to FIG. 24. The longitudinal section explanatory drawing which shows the positional relationship in each sample (1st test piece) of the sample (2nd test piece) further taken out from each taken out sample (1st test piece). The graph which shows the zinc concentration of the taken-out sample (2nd test piece).

FIG. 1 shows the overall configuration of a continuous casting apparatus as a first embodiment of the present invention, and shows a case where a round bar-like ingot is obtained as a product P. As can be seen from FIG. 1, this apparatus is a melting furnace for non-ferrous metals or other metals of conductors (conductors) such as Al, Cu, Zn, at least two of these alloys, or Mg alloys (see FIG. 1). The molten metal M from (not shown) is caused to flow into the mold 1 through the trough 2 and finally the product P is obtained. In 1st Embodiment of this invention, in order to improve the quality of the product P finally obtained, the molten metal stirring apparatus 3 is provided. That is, the molten metal stirring device 3 is held in a state immersed in the molten metal M at the end portion of the trough 2 by a predetermined means. As will be described in detail later by this molten metal stirring device 3, while rotating the molten metal M around the molten metal stirring device 3 by the Lorentz force, as can be seen from FIG. 1 (first embodiment), To send it to. The other embodiment will be briefly described in connection with this invention. The molten metal stirring device is used to change the molten metal M in the mold 1 in FIG. 4 (second embodiment), and in FIG. 6 (third embodiment). Both the molten metal M in the mold 2 and the mold 1 are sent to the mold 1 while being rotationally driven by Lorentz force to obtain a product P with improved quality.

Hereinafter, the first embodiment of the present invention will be described in more detail.

In FIG. 1, a molten metal M from a melting furnace (not shown) is guided to a mold 1 by a firewood 2. That is, the mold 1 is attached to the front end (end) of the flange 2 in a communicating state. More specifically, the molten metal inlet of the mold 1 is attached to the bottom surface of the bowl 2, and the molten metal stirring device 1 is incorporated in a state where the lower end side is inserted into the molten metal outlet path in the bowl 2. .

The molten metal M reaches from the bowl 2 to the mold 1 and is cooled there to obtain a so-called solid phase product P having improved quality. Above this product P is a so-called liquid-phase molten metal M that has not yet cooled down. That is, as can be seen from FIG. 1, in the mold 1, the upper part is a molten metal M in a liquid phase state and the lower part is a product P in a solid phase state. Make and touch each other.

The molten metal stirring device 3 is held in the bowl 2 in a state of being floated by a desired means. The position of the molten metal stirring device 1 can be adjusted up and down in FIG. Therefore, in FIG. 1, the lower end of the molten metal stirring device 3 is slightly in the mold 1, but the molten metal stirring device 3 can be held so that all of the molten metal stirring device 3 exists only in the tub 2. A longitudinal explanatory view of the molten metal stirring device 3 is shown in FIG. 2, and an enlarged view thereof is shown in FIG. 3 as an operation explanatory view.

In particular, as can be seen from FIG. 3, the molten metal stirring device 3 includes a substantially cylindrical case 6 having a double structure and an open top, a magnetic field device 7 having a permanent magnet 18 accommodated in the case 6, and a case 6. And an electrode portion 8 having a pair of attached electrodes (first electrode 24, second electrode 25). The molten metal stirrer 3 is configured to have an air cooling structure that can be cooled with compressed air by paying attention to the high temperature property of the molten metal M. By this air cooling, for example, the permanent magnet 18 of the magnetic field device 7 can maintain its ability.

More specifically, in FIG. 3 in particular, the case 6 has an outer cylinder 11 and an inner cylinder 12 which are made of a fire-resistant material and open in a cylindrical shape. A gap 14 for flowing compressed air for cooling is formed between the outer cylinder 11 and the inner cylinder 12. Further, in order to allow this cooling air to pass, a plurality of vent holes 12a are formed concentrically at the bottom of the inner cylinder 12 so that the inside of the inner cylinder 12 communicates with the gap 14. Thereby, the cooling air path from the inner cylinder 12C to the gap 14 and further to the atmosphere via the vent hole 12a is formed. That is, as can be seen from FIG. 3, the compressed air for cooling flows into the inner cylinder 12 from above as shown by an arrow AR1, reaches the bottom, reaches the bottom of the gap 14 from the vent hole 12a. The gap 14 rises and is eventually released into the atmosphere. During this time, the compressed air exchanges heat in the flow path to cool the magnetic field device 7 and the like. The molten metal stirring device 3 can be fixed to a desired external fixing device by the flange portion of the outer cylinder 11. Further, the molten metal stirring device 3 can appropriately adjust the depth of immersion in the trough 2 and the mold 1. Thereby, the said immersion depth can be adjusted according to the physical property etc. of the molten metal M to be used on the spot, and the molten metal M can be stirred more appropriately.

As can be seen from FIG. 3, the magnetic field device 7 is housed in the inner cylinder 12 with a stainless steel pipe 16 inserted. Details of the magnetic field device 7 are shown in FIGS. 8a and 8b. That is, the magnetic field device 7 is configured as an integrally configured cylindrical permanent magnet 18 and has a through hole 18a for allowing the pipe 16 to pass through the central axis portion. The permanent magnet 18 is magnetized to the south pole on the center side and to the north pole on the outer peripheral side. (Naturally, the direction of magnetization may be opposite to that described above. In this case, the direction of current flow can be changed by the external power supply panel 27 described later if necessary.) As can be seen from FIG. 3, magnetic field lines ML appear radially from the magnetic field device 7 and run in the molten metal M in the bowl 2. Note that the configuration of the magnetic field device 7 is not limited to that shown in FIGS. 8a and 8b, but may be any as long as the magnetic field lines ML appear as shown in FIG. For example, an example is shown in FIGS. 9a and 9b. The permanent magnets 18 in these drawings have a plurality of bar-like permanent magnet pieces 19 that are long in the vertical direction. The mode of magnetization of each permanent magnet piece 19 is shown in FIGS. 9a and 9b. The magnetic field device 7 is configured as a concentric arrangement of the permanent magnet pieces 19 as viewed in plan. As described above, the magnetic field device 7 is housed in the inner cylinder 12 in a state in which the pipe 16 is inserted, as can be seen from FIG. Thereby, the said magnetic field apparatus 7 emits the magnetic force line ML radially, and this magnetic force line ML reaches the molten metal M in the tub 2 and runs through it. When the compressed air flows through the inner cylinder 12, the compressed air reaches the vent hole 12a while cooling the magnetic field device 7 and the like.

As can be seen from FIG. 3, a guide rod 22 made of a conductive material such as copper, which functions as a lead wire body, is accommodated in the stainless steel pipe 16. A first electrode 24 made of tungsten, graphite or the like is attached to the lower end of the guide rod 22 in an electrically conductive state. The first electrode 24 penetrates the inner cylinder 12 and the outer cylinder 11 in a liquid-tight state (at least in a molten-metal state), exposes the tip (lower end) to the outside, and contacts the molten metal M in the bowl 2. It is possible.

The second electrode 25 configured in a ring shape by graphite or the like, which is paired with the first electrode 24, is attached to the outer peripheral surface of the outer cylinder 11 so as to be detachably inserted. As a result, when the molten metal stirring device 3 is immersed in the molten metal M of the tub 2, the current i is transferred from the second electrode 25 to the first electrode 24 via the molten metal M as shown in FIG. Flows. As a result, the magnetic field lines ML from the magnetic field device 7 and the current i flowing between the first electrode 24 and the second electrode 25 intersect to generate Lorentz force. Thereby, as shown in FIG. 1, the molten metal M in the tub 2 is rotationally driven. The second electrode 25 can be replaced with another one as necessary, for example, when worn.

The molten metal M in the cocoon 2 is rotationally driven, that is, stirred, and the following advantages are obtained.

First, the impurities existing inside rise in the molten metal M and gather in the surface portion, and the quality of the molten metal M other than the surface portion, that is, the molten metal M flowing into the mold 1 is improved. Thereby, the quality of the product P obtained with the mold 1 is improved.

Further, the molten metal M is stirred in the bowl 2 and flows into the mold 1 while rotating. As a result, the molten metal M also rotates in the mold 1. That is, the molten metal M is indirectly rotated in the mold 1 as well. Due to the rotation in the mold 1, the molten metal M is solidified in a state where the temperatures of the inner part and the outer part are averaged. Thereby, coupled with the removal of impurities in the molten metal M as described above, the product P can be obtained with a higher quality. Such a quality improvement mechanism is also applicable to other embodiments and modifications described below.

Referring back to FIG. 1, the first electrode 24 and the second electrode 25 are connected to an external power supply panel 27 so that a desired DC current can be supplied. The amount of supplied current can be adjusted by the external power supply panel 27, and the polarity can also be switched. By rotating the polarity, the rotation direction of the molten metal M in the trough 2 and the mold 1 can be reversed. Such control can also be performed while observing the stirring state of the molten metal M in the field, thereby individually controlling each characteristic of the molten metal M to be used, not depending on the characteristics of the molten metal M to be used, and higher quality. Product P can be obtained. In addition, such control is possible by a simple operation on the external power supply panel 27, and its usefulness in the field is extremely high.

In the mold 1, for example, as can be seen from FIG. 1, a circulation path 1a for circulating cooling water is formed. A plurality of locations facing the product P in the circulation path 1a are used as cooling water ports 1b penetrating to the outside. The product P is manufactured while being cooled by the cooling water discharged from these cooling water ports 1b. Thus, as described above, since the molten metal M is driven to rotate in the mold 1 as well, it is possible to obtain a higher quality product P by making the temperature uniform. The reason why the shape of the interface I is a downwardly convex paraboloid as shown in FIG. 1 is that the cooling rate of the outer portion and the inner portion of the molten metal M is different. As the product P increases in size, that is, when the cross section is increased, the curve near the apex of the paraboloid of the interface I becomes steeper. Similarly, the higher the drawing speed of the product P, the sharper the above. Thereby, the difference of the cooling rate of an external part and an internal part becomes larger. This inevitably causes variations in the internal quality of the product P. However, as described above, the molten metal M is also stirred in the mold 1 so as to make the temperature uniform, and in combination with the removal of impurities in the tub 2, higher quality is achieved. You can get a product.

Although the operation of the first embodiment of the present invention can be understood from the above description, it will be briefly described below.

1, current i flows between a pair of electrodes (first electrode 24 and second electrode 25) as shown in FIG. 3 from the external power supply panel 27 of FIG. This current i crosses the magnetic field line ML to generate a Lorentz force f. Due to the Lorentz force f, the molten metal M in the bowl 2 (and a little molten metal M in the mold 1) is rotationally driven as shown in FIG. As a result, the molten metal M flows into the mold 1 while rotating, and is cooled and solidified by cooling water from the cooling water port 1b while rotating in the mold 1 to become a product P. Here, by adjusting the amount of current from the external power supply panel 27, the rotational speed of the molten metal M in the trough 2 and in the mold 1 can be adjusted. That is, the quality, properties, components, etc. of the molten metal M flowing from the melting furnace (not shown) are not always the same, but the amount of current is adjusted depending on the quality, properties, etc. of the molten metal M used. Regardless of the physical properties of M, a product P having more appropriate quality can be obtained. In addition, by changing the flow direction of the current i in small increments, the rotation direction of the molten metal M in the trough 2 can be changed in a very short time to make a so-called vibration state, thereby further promoting the removal of impurities. You can also

Next, a second embodiment of the present invention will be described.

In the second embodiment of the present invention, as can be seen from FIG. 4 in particular, the permanent magnet 18A (see FIG. 5) mounted on the molten metal stirring device 3A is not the molten metal M in the bowl 2, but before the solidification in the mold 1. The molten metal M is rotationally driven. Even if the molten metal M in the mold 1 is agitated, as can be seen from the description in the first embodiment of the present invention, it is possible to obtain substantially the same operational effects as in the case of the first embodiment of the present invention. Obviously you can.

Hereinafter, differences from the first embodiment of the present invention will be mainly described. The melt stirring apparatus 3A mounted in the second embodiment of the present invention shown in FIG. 4 is shown in FIG. The melt stirrer 3A shown in FIG. 5 differs from the melt stirrer 3 shown in FIG. 3 only in the direction in which the lines of magnetic force ML appear, as can be easily seen from the comparison of both figures. Are almost the same. That is, the permanent magnet 18A of the magnetic field device 7A in FIG. Details of the magnetic field device 7A are shown in FIGS. 10a and 10b. 10a is a longitudinal sectional view, and FIG. 10b is a plan view. As can be seen from these drawings, the outer shape is almost the same as that of FIGS. 8a and 8b, but the mode of magnetization is different, and the upper part of the cylindrical body is magnetized to the S pole and the lower part is magnetized to the N pole.

As can be seen from FIG. 5, the magnetic field lines ML from the magnetic field device 7A and the current i flowing between the pair of electrodes (the first electrode 24 and the second electrode 25) are on the bottom surface of the outer cylinder 11 of the magnetic field device 7A. Cross on the outside. Due to the Lorentz force f generated thereby, the molten metal M in the mold 1 is rotationally driven as shown in FIG.

As described above, in the second embodiment of the present invention, the configuration and operation other than those described above are substantially the same as those of the first embodiment of the present invention, and thus detailed description thereof is omitted.

Next, a third embodiment of the present invention will be described.

As can be seen from FIG. 6 in particular, the third embodiment of the present invention uses the permanent magnets 18B1, 18B2 (see FIG. 7) mounted on the molten metal stirring device 3B to solidify the molten metal M in the bowl 2 and the mold 1. Both the previous molten metal M and both molten metals M are directly driven to rotate. Since both the molten metal M in the bowl 2 and the molten metal M in the mold 1 are directly agitated, they are almost the same as those in the first embodiment of the present invention and the second embodiment of the present invention. Obviously, it is possible to obtain an action effect or more.

More specifically, FIG. 7 shows a longitudinally enlarged operation explanatory view of the molten metal stirring device 3B of FIG. The molten metal stirring device 3B (third embodiment) shown in FIG. 7 includes the molten metal stirring device 3 (first embodiment) shown in FIG. 3 and the molten metal stirring device 3B (second embodiment) shown in FIG. ) Is configured to have both functions. As can be seen from FIG. 7, in the magnetic field device 7B, the cylindrical first permanent magnet 18B1 and the second permanent magnet 18B2 are stacked one above the other through spacers 30 made of nonmagnetic material. The details are shown in FIGS. 11a (longitudinal explanatory view), FIG. 11b (top view), and FIG. 11c (bottom view). As can be seen from FIGS. 11a and 11b, the first permanent magnet 18B1 is composed of a plurality of permanent magnet pieces 19 similar to those shown in FIGS. 9a and 9b, with the inside being the S pole and the outside being the N pole. It is said that. As can be seen from FIGS. 11a and 11c, the second permanent magnet 18B2 is magnetized with the N pole on the upper side and the S pole on the lower side, as shown in FIGS. 10a and 10b. The first permanent magnet 18B1 and the second permanent magnet 18B2 are integrally configured with the spacer 30 interposed therebetween.

As can be seen from FIG. 7, the magnetic field lines ML from the permanent magnet 18 </ b> B <b> 1 of the magnetic field device 7 </ b> B and the current i flowing between the pair of electrodes (first electrode 24, second electrode 25) are on the side surface of the outer cylinder 11. Cross on the outside. The magnetic field lines ML from the second permanent magnet 18B2 of the magnetic field device 7B and the current i flowing between the pair of electrodes (the first electrode 24 and the second electrode 25) are those of the outer cylinder 11 of the magnetic field device 7A. Cross on the outside of the side. As shown in FIG. 6, the two types of Lorentz forces f generated thereby rotate and drive the outer side of the outer peripheral surface of the magnetic field device 7B in the cage 2 and the outer side of the bottom surface in the mold 1, respectively.

In the third embodiment of the present invention, the configuration and operation other than those described above are substantially the same as those of the first and second embodiments of the present invention, and thus detailed description thereof is omitted.

In the first to third embodiments of the present invention described above, the case 6 has a double structure of the outer cylinder 11 and the inner cylinder 12, and a gap 14 is formed between the two, and compressed air for cooling is provided here. I tried to distribute it. However, the strength of the case 6 can also be increased by overlapping the outer cylinder 11 and the inner cylinder 12 in close contact with each other without a gap. In this case, a separate cooling air flow path is secured. Fourth to sixth embodiments of the present invention that embody this technical idea are shown in FIGS. In these embodiments, the compressed air for cooling is fed from the pipe 16C.

Next, a fourth embodiment of the present invention will be described first.

A fourth embodiment of the present invention is shown in FIGS. As can be seen from FIG. 14 in particular, in this embodiment, the melt M before solidification in the mold 1 is rotationally driven by a permanent magnet 18C mounted on the melt stirring device 3C. In the fourth embodiment of the present invention, a permanent magnet equivalent to that shown in FIGS. 8a and 8b is used. The molten metal stirring device 3C of FIG. 14 (fourth embodiment of the present invention) differs from the molten metal stirring device 3 of FIG. 3 (first embodiment of the present invention) in that the case 6C is connected to the outer cylinder 11C. The point is that the cylinder 12C is superposed without gaps, and that the compressed air for cooling is sent from the pipe 16C that is slightly thicker. The inner cylinder 12C can be configured to function as a heat insulating cylinder by a heat insulating member. A communication gap for communication is formed between the lower end of the pipe 16C and the bottom surface of the inner cylinder 12C. Thereby, the inside of the pipe communicates with the inside of the case through the communication gap to form a cooling air passage, and the inside of the pipe and the inside of the inner cylinder are connected via the communication gap. A cooling air path is formed in communication. As a result, the compressed air sent into the pipe 16C reaches the gap 14C between the pipe 16C and the inner cylinder 12C from the lower end of the pipe 16C, as shown by an arrow AR2, and is inverted and raised and discharged to the outside. The permanent magnet 18C and the like are cooled by the compressed air that rises in the reverse direction.

Other configurations and operations in the fourth embodiment are the same as those in the above-described embodiment, and thus detailed description thereof is omitted.

Next, a fifth embodiment of the present invention will be described.

In the fifth embodiment of the present invention, similar to the second embodiment of the present invention shown in FIG. 4, the molten metal M in the mold 1 is directly driven. FIG. 15 shows a molten metal stirring device 3D as a main part. In the fourth embodiment of the present invention, a magnetic field device 7D using a permanent magnet 18D equivalent to that shown in FIG. 10a is used. Since other configurations and operations are substantially the same as those in FIGS. 14 and 5, detailed description thereof is omitted.

Next, a sixth embodiment of the present invention will be described.

In the sixth embodiment of the present invention, the molten metal M in the tub 2 and the molten metal M in the mold 1 are to be driven directly, as in the third embodiment of the present invention in FIG. FIG. 16 shows a molten metal stirring device 3E as a main part. In the sixth embodiment of the present invention, a magnetic field device 7E using a first permanent magnet 18E1 and a second permanent magnet 18E2 equivalent to those shown in FIG. 11a is used. Other configurations are almost the same as those of FIGS. 14 and 7, and detailed description thereof is omitted.

Next, a seventh embodiment of the present invention will be described.

In the seventh embodiment of the present invention, as shown in FIG. 2A, the outer cylinder 11D in the case 6D is made of a conductive material that generates heat by energization and reaches several hundred degrees close to the temperature of the molten metal. The electric resistance of the conductive material is larger than that of the molten metal M used. As this conductive material, various materials such as graphite can be used as long as they have fire resistance and are resistant to the molten metal used.

Also, the upper second electrode 25D in the electrode portion 8D is provided above the second electrode 25 in FIG. 2 so as not to contact the molten metal M during actual use.

Other configurations are substantially the same as those of the embodiment of FIG.

In the seventh embodiment of the present invention, as described above, the outer cylinder 11D can be self-heated by energization. Due to the self-heating, it can be several hundred degrees, for example. Thereby, if it is made into a high temperature state by energization prior to actual use, it can be used immediately after being actually submerged in the molten metal, and waste of time can be reduced as much as possible. In other words, according to this embodiment, it is not necessary to wait for several hours in order to sink the molten metal stirring device 3D into the molten metal and actually operate the molten metal stirring apparatus 3D.

FIG. 2B is an explanatory diagram showing a current path in the molten metal stirring device 3D. As can be seen from the arrow ARD in FIG. 2B, the current from the positive terminal 27a of the external power supply panel 27 passes through the outer cylinder 11D such as graphite from the second electrode 25D, and then the molten metal M having a relatively low electric resistance. , Reaches the first electrode 24, and returns to the negative terminal 27b of the external power supply panel 27.

FIG. 13A shows an eighth embodiment of the present invention.

In the eighth embodiment of the present invention, as compared with the apparatus shown in FIG. 13, the second electrode 25E of the electrode portion 8E of the molten metal stirring apparatus 3E is provided on the upper side as in the embodiment of FIG. An example in which the outer cylinder 11E in the case 6E is made of a conductive material such as graphite is shown. The rest is almost the same as the example of FIG.

According to each embodiment described above, the following advantages are obtained.
(1) Since the molten metal is directly stirred, the stirring efficiency is extremely high.
(2) It can efficiently handle large ingots.
(3) In the case of a large ingot, a plurality of molten metal stirring devices may be incorporated.
(4) The depth of the ingot in the mold to the interface varies depending on the drawing speed and size of the product. In this case, the molten metal can be stirred more appropriately by adjusting the depth of the molten metal stirring device and the immersion depth in the mold.
(5) The molten metal stirrer can be made compact, so that a large space is not required for installation.
(6) Thereby, application to the existing mold apparatus etc. is easy.
(7) The crystal structure of the product (ingot) can be refined.
(8) The crystal structure of the product (ingot) can be made uniform.
(9) Product production speed can be increased. For example, production can be increased by 10-30%.
(10) Since the molten metal is agitated internally, oxidation of the molten metal can be prevented and the quality of the product can be improved.

As described above, the continuous casting apparatus according to the embodiment of the present invention has various advantages. Among the advantages, the improvement of the production speed (productivity) of the product will be further described as follows.

Generally, in continuous casting, product productivity depends on the product drawing speed. Increasing the drawing speed increases productivity. However, when the drawing speed is increased to a certain speed or more, one or more cracks extending vertically are generated inside the product. The presence of this crack can be confirmed by, for example, cutting the cooled product and observing the inside of the product.

Thus, in the past, even if it was attempted to increase productivity, there was a limit to increasing the drawing speed, and therefore productivity could not be sufficiently improved.

However, according to the continuous casting apparatus of the embodiment of the present invention, even if the drawing speed is increased beyond the speed of the conventional continuous casting apparatus, it is possible to obtain a high-quality product having no cracks inside. I think this can be understood from the above-mentioned explanation, but the present inventor conducted an experiment described below and actually manufactured a prototype to confirm this.

Also, as a standard for judging the quality of the product, there is a degree of refinement of the crystal structure. That is, a high-quality product can be said to be a product with a finer crystal structure. In order to refine the crystal structure, the molten metal may be rapidly cooled. In other words, the crystal structure is not refined unless cooled rapidly.

In the process of continuous casting, in the upper part of the mold, a solid phase part SP that has already solidified by cooling of the molten metal (see SP1 in FIG. 21, etc.), and a liquid phase part LP to solidify in the future (see LP1 in FIG. 21, etc.) Are adjacent to each other, creating an interface. Further, a semi-solidified layer portion (Mussy zone: Mushy Zone) MZ (see MZ1 in FIG. 21, etc.) having an intermediate property between the solid phase and the liquid phase appears at the interface portion between the two. This semi-solidified layer portion MZ is a transition layer in the process of transition from the liquid phase to the solid phase.

The inventor has produced a number of products and cut the product that the semi-solidified layer portion MZ appears as thin when cooling is performed rapidly and appears as thick when it is performed slowly. And I knew it independently by observing. Therefore, conversely, when the semi-solidified layer portion MZ is thin, the quality of the crystal structure in the solid phase portion SP is fine and good, and when it is thick, the quality of the crystal structure in the solid phase portion SP is rough and malicious. That is, it can be said that if the thickness of the semi-solidified layer portion MZ is seen, it can be seen whether the crystal structure inside the product is fine, high quality or rough, non-quality.

However, according to the continuous casting apparatus of the embodiment of the present invention, the semi-solid phase portion MZ does not become thick even if the drawing speed is increased beyond the speed of the conventional continuous casting apparatus. According to the continuous casting apparatus of the embodiment of the present invention, the molten metal is supplied to the mold in a stirring state, which has not been performed in the conventional continuous casting apparatus and is impossible in the first place. This is because the melt just before it hardens is now stirred. That is, according to the continuous casting apparatus of the embodiment of the present invention, a high-quality product can be obtained even if the production efficiency is increased. This was confirmed by the following experiment conducted by the present inventors.

(Experiment 1)
Outline of Experiment The liquid phase portion LP and the semi-solidified layer portion MZ are then completely solidified and become only the solid phase portion SP. In the experiment conducted by the present inventor, the liquid phase portion LP and the semi-solidified layer appearing only in the manufacturing process, which are originally disappeared in the prototype TP finally obtained so as to be visually confirmed. Part MZ was made to appear. In other words, the prototype TP can be obtained entirely as a solid (solid phase). However, when viewed at a certain moment in the manufacturing process, the prototype TP is the first solid portion SP (MZ) that was once the liquid phase portion LP. It consists of three solid parts, the second solid part SP (MZ) that was the semi-solidified layer part MZ and the third solid part SP (SP) that was also solid. In this experiment, these three solid portions can be visually grasped in the prototype TP so that the quality of the prototype TP can be easily determined.

In other words, in general, the finished product becomes all the solid phase part SP, the liquid phase part LP and the semi-solidified layer part MZ disappear, and the liquid phase part LP and the semi-solidified layer part MZ are visually confirmed. Can not. However, in this experiment, a special treatment was applied at a certain moment in the manufacturing process, and the finished product was a solid product (prototype). At the moment, the liquid phase portion LP was once shown in FIG. The portion that was once, the portion that was once the semi-solidified layer portion MZ, and the portion that was once the solid phase portion SP can be visually identified.

Details of Experiment (1) Manufacture of Prototype (Aluminum Cylindrical Ingot (Round Ingot)) Performed by the Inventor to Confirm Productivity Improvement, which is the Effect of the Continuous Casting Device of the Present Invention The experiment will be described. In this production experiment, the continuous casting apparatus according to the embodiment of the present invention and the apparatus obtained by removing the molten metal stirring device 3 from the continuous casting apparatus according to the embodiment of the present invention (continuous casting apparatus before improvement) were used.

In other words, the inventor manufactured the prototype TP using the continuous casting apparatus according to the embodiment of the present invention shown in FIG. 1, with the molten metal stirring apparatus 3 in FIG. 1 removed (continuous casting apparatus before improvement) and A continuous prototype TP shown in FIG. 17 was manufactured by switching between the state where the molten metal stirring device 3 is used as it is (continuous casting device according to the embodiment of the present invention). In FIG. 17, a part of the prototype TP is shown broken (cut) for easy understanding. That is, the inside of the prototype TP can be observed by being longitudinally cut after manufacture. In place of the molten metal stirring device 3 in FIG. 1, the same prototype TP as in FIG. 17 can be obtained by using the continuous casting device of the embodiment of the present invention in FIGS. 4, 6, 12, 15, and 16. It is clear that can be obtained.

In the prototype TP shown in FIG. 17, the first prototype 100 is a part manufactured by the continuous casting apparatus before the improvement, and the second prototype 200 is manufactured by the continuous casting apparatus according to the embodiment of the present invention. It is the part which did. Further, the first prototype part 100 is obtained by drawing in the direction of arrow AR at a slow low speed drawing portion 50A obtained by drawing at a slow drawing speed (casting speed) and at a drawing speed (casting speed) faster than that. And a first high-speed extraction portion 50B. On the other hand, the second prototype part 200 has a second high-speed drawing part 60B obtained by drawing at the same drawing speed (casting speed) as that of the first high-speed drawing part 50B.

As will be described later, as is apparent from the comparison between the first high-speed drawing portion 50B and the second high-speed drawing portion 60B, the first high-speed drawing portion 50B obtained by the continuous casting apparatus before improvement has cracks. Although C exists, the presence of cracks was not recognized in the second high-speed drawing portion 60B obtained by the continuous casting apparatus of the present invention. That is, according to the experiment conducted by the present inventor, it has been confirmed that according to the continuous casting apparatus of the present invention, a cast product having no cracks can be obtained even if the drawing speed (casting speed) is increased. That is, productivity could be improved in continuous casting.

(2) Details of the production experiment will be described below. As an experiment, an experiment A for obtaining the low-speed extraction part 50A in the first prototype part 100, an experiment B for obtaining the first high-speed extraction part 50B, and the first in the second prototype part 200 Three experiments were conducted: Experiment C for obtaining two high-speed drawn portions 60B.

The low-speed extraction portion 50A, the first high-speed extraction portion 50B, and the second high-speed extraction portion 60B were obtained by the experiment A, the experiment B, and the experiment C, respectively. The low speed drawing portion 50A, the first high speed drawing portion 50B, and the second high speed drawing portion 60B are shown enlarged in FIGS. 18, 19, and 20, respectively. 18, 19, and 20 are partial cross-sectional views of the prototype (solid) TP. From FIGS. 18, 19, and 20, there are various processes in the manufacturing process using the continuous casting apparatus. The state of the inside of the mold 1 at the moment is grasped in FIG. 21, FIG. 22, and FIG. 23 as three phases of solid, semi-solidified layer, and liquid coexist. This is because the prototype (product) TP is obtained as it represents a certain moment in the manufacturing process. Therefore, in the following, description will be given using FIGS. 21, 22 and 23 as explanatory diagrams showing the inside of the mold at a certain moment in the product manufacturing process.

(2) -1 First, Experiments A and B for manufacturing the first prototype 100 (50A and 50B) shown in FIG. 17 will be described. Details of the low speed drawing portion 50A and the first high speed drawing portion 50B in the prototype TP are shown in FIGS.

In producing the prototype part 100 as a product (casting product) by performing extraction with the continuous casting device before improvement by removing the molten metal stirring device 3 from the continuous casting device of FIG. The speed was changed to low speed and then switched to high speed. That is, the low-speed extraction part 50A of FIG. 17 was obtained by the initial low-speed extraction, and then the first high-speed extraction part 50B was obtained by switching to high speed.

The condition 1 (experiment A) at the time of the low speed drawing and the condition 2 (experiment B) at the time of the high speed drawing were as follows. Further, as shown in FIG. 21 and FIG. 22 showing a certain moment in the manufacturing process, the sump depths (maximum depth of the liquid phase portion LP) d1, d2, which appear in the case of these conditions 1 and 2, It can be seen from FIGS. 18 and 19 showing the prototype TP that the thicknesses t1 and t2 of the semi-solidified layer portion (Mushy 図 Zone) MZ were as follows.

(Experiment A) (Condition 1 and result)
・ Material: Aluminum ・ Additive: Zinc ・ Diameter of round ingot Φ = 355mm
・ Drawing speed (casting speed) v1 = 75mm / min
Sump depth (maximum depth of liquid phase portion LP) (FIG. 21) d1 = 171.5 mm
・ Thickness of semi-solidified layer (Mushy Zone) (Fig. 21) t1 = 4mm

That is, drawing was performed at a low speed under the above condition 1 by the continuous casting apparatus before the improvement. Zinc was added to the liquid phase part LP1 at a certain moment when the extraction under the condition 1 was performed. The added zinc instantly diffused into the aluminum of the liquid phase part LP1, and formed an alloy, which served as a contrast agent. Drawing was performed under the above condition 1 for a predetermined time after the addition. By this experiment A, the low speed drawing part 50A of FIG.17 and FIG.18 was obtained. A mechanism for obtaining the low speed drawing portion 50A will be described later.

It can be seen from FIG. 21 that the internal state of the mold 1 in the experiment A under the condition 1 is as follows. That is, FIG. 21 shows a longitudinal section of the top (top) of the product in the mold 1 at a certain moment. In FIG. 21, a solid phase portion SP1 already solidified appears on the lower side, and a liquid phase portion LP1 to be solidified appears on the upper side. Further, a semi-solid phase portion (Mushy Zone) MZ1 appears at the interface portion between the two phases. As shown in FIG. 21, the sump depth (maximum depth of the liquid phase portion LP1) d1 = 171.5 mm and the thickness t1 of the semi-solid phase portion (Mushy Zone) MZ1 = 4 mm. As can be seen from FIG. 21, when the drawing speed (casting speed) is low, no cracks (cavities) are generated in the liquid phase portion LP1. Along with this, as can be seen from the prototype TP shown in FIG. 17, the low-speed extraction part 50A without cracks is finally formed.

(Experiment B) (Condition 2 and results)
・ Material: Aluminum ・ Additive: Zinc ・ Diameter of round ingot Φ = 355mm
・ Drawing speed (casting speed) v2 = 109mm / min
Sump depth (maximum depth of liquid phase portion LP) (FIG. 22) d2 = 282.2 mm
・ Thickness of semi-solidified layer (Mushy Zone) (Fig. 22) t2 = 5.5mm

Following the drawing under the condition 1 performed by the continuous casting apparatus before the improvement, the drawing was performed at the higher speed than before by the continuous casting apparatus before the improvement under the condition 2 described above. Similarly to the above, zinc was added to the liquid phase portion LP2 at a certain moment when the extraction under the condition 2 was performed. Similarly to the above, the added zinc diffuses at high speed in the aluminum of the liquid phase part LP2, forms an alloy, and plays a role as a contrast agent. By this experiment B, the first high-speed drawing portion 50B of FIGS. 17 and 22 is obtained. A mechanism for obtaining the first high-speed drawing portion 50B will be described later.

In the experiment B under the above condition 2, the longitudinal section of the uppermost part (top) of the mold 1 is as shown in FIG. In FIG. 22, the solid phase part SP2 already solidified appears on the lower side, and the liquid phase part LP2 to be solidified appears on the upper side. Further, a semi-solid phase portion (Mushy Zone) MZ2 appears at the interface portion between the two phases. As shown in FIG. 22, the sump depth (maximum depth of the liquid phase portion LP) d2 = 282.2 mm, and the thickness t2 of the semi-solidified layer portion (Mushy Zone) MZ2 is 5.5 mm. As can be seen from FIG. 22, when the drawing speed (casting speed) is high, generation of cracks (cavities) is observed in the liquid phase portion LP2. Accordingly, the first high-speed drawing portion 50B including the crack shown in FIG. 17 is formed.

(2) -2 Next, Experiment C for manufacturing the second prototype part 200 of FIG. 17 will be described.
The drawing speed (casting speed) for producing the prototype 200 as a product (casting product) by performing drawing with the continuous casting apparatus of the present invention shown in FIG. 1 is the first high speed in the first prototype part 100. The same high speed drawing speed (casting speed) as that for manufacturing the drawn portion 50B was used. As a result, the second high speed drawing portion 60B of FIG. 17 was obtained.

The condition 3 (experiment C) at the time of the high speed drawing was as follows. Further, the sump depth (maximum depth of the liquid phase portion LP) d3 and the thickness t3 of the semi-solidified layer portion (Mushy Zone) appearing in the case of Condition 3 were as follows.

(Experiment C) (Condition 3 and results)
・ Material: Aluminum ・ Additive: Zinc ・ Diameter of round ingot Φ = 355mm
・ Drawing speed (casting speed) v3 = 102mm / min
Sump depth (maximum depth of liquid phase portion LP) (FIG. 23) d3 = 276.2 mm
・ Thickness of semi-solidified layer (Mushy Zone) (Fig. 23) t3 = 4mm

Drawing was performed under the condition 3 using the continuous casting apparatus of the present invention. Zinc was added to the liquid phase portion LP3 in the same manner as described above at a certain moment when the extraction under the condition 3 was performed. In the same manner as described above, the added zinc diffused at high speed in the aluminum of the liquid phase portion LP to form a kind of alloy and served as a contrast agent. By this experiment C, the second high-speed drawing portion 60A shown in FIGS. 17 and 20 was obtained. The mechanism by which the second high speed drawing portion 50B is obtained will be described later.

The process of experiment C under the condition 3 is shown in FIG. In FIG. 23, a solid phase portion SP3 that has already solidified appears on the lower side, and a liquid phase portion LP3 that solidifies from now on appears on the upper side. Furthermore, a semi-solid phase portion (Mushy Zone) MZ3 appeared at the interface portion between the two phases. As shown in FIG. 23, the sump depth (maximum depth of the liquid phase portion LP3) d3 = 276.2 mm, and the thickness t3 = 4 mm of the semi-solid phase portion (Mushy Zone) MZ3. As can be seen from FIG. 23, no cracks (cavities) were observed in the liquid phase portion LP3, although the drawing speed (casting speed) was increased. That is, when the product is manufactured under the condition 3, the thickness of the semi-solid phase portion (Mushy Zone) MZ3 is increased although the sump depth is increased as compared with the case of the condition 1 where no crack is generated. There was little increase. Since the semi-solid phase part (Mushy Zone) MZ3 does not become thick, even if high speed drawing casting is performed by the apparatus of the present invention, the heat transfer in the material is accelerated, the crystal structure becomes uniform and refined, and It can be expected that productivity will be improved while maintaining the mechanical strength of the product. Thus, as shown in FIG. 20, it was possible to form the low-speed drawing portion 60A without cracks.

As can be seen from the above description, as explained in paragraph (0046) (9) above, according to the continuous casting apparatus of the present invention, about 30% as compared with the continuous casting apparatus before the improvement. The pulling speed of the product could be increased.

Further, the gist, outline, and further experiment of the present invention will be described below.

Generally, various ingot metal products such as round bars or prisms are obtained through a process of solidifying a raw material metal, adjusting components, and solidifying into a predetermined shape. At this time, the quality of the final product, for example, mechanical properties, homogenization and refinement of the crystal structure, is determined by the state in the sump during solidification (the unsolidified liquid portion at the top of the product during continuous casting). End up.

Solidification of the molten metal occurs due to heat transfer, but since the heat conduction in the solid is twice that of the liquid, the molten metal in the container or continuous casting mold progresses from the outer periphery to the center. To do. In the case of continuous casting, for example, as can be seen from FIG. 1, solidification proceeds in a state where a liquid and a solid coexist in the top portion of the product.

An important point for improving the quality of the product is, for example, to reduce the liquid part and the semi-solidified layer part in FIG. 1 as much as possible. It is very difficult to achieve.

Therefore, the present inventor paid attention to the fact that the thermal conductivity of the liquid is lower than the thermal conductivity of the solid, and applied the magnetic field and current to the molten metal and stirred to thereby reduce the drawing speed (casting speed). Even if the sump is deepened when it is raised, cracks are prevented from occurring.

Now, when the present invention is applied to continuous casting of various ingots (such as round ingots (round bar-shaped ingots) or prismatic ingots), particularly when the cooling rate is improved by the present invention to improve quality. To do.

In the continuous casting process, for example, as can be seen from FIG. 1, a downwardly convex conical column-shaped sump (a downwardly convex parabolic shape in the longitudinal section) always appears.

Now, heat transfer can be explained by Newton's law of cooling.

That is, if the amount of heat Q to move, time t, surface area S, high temperature side temperature TH, low temperature side temperature TL, temperature coefficient α,
-DQ / dt = α · S (TH-TL)
It becomes.

That is, the heat transfer is performed more smoothly as the temperature gradient proportional to the difference between the high temperature side temperature TH and the low temperature side temperature TL increases.

By the way, although the heat transfer increases by stirring, the difference in temperature difference with and without stirring is considered.

FIG. 24 is a longitudinal explanatory view at a certain point in one process in which a molten metal (liquid) is changed into a product (solid) inside a mold in general continuous casting.

FIG. 25 shows the heat state of the portion surrounded by the elongated circle CIR in FIG. The solid line SL indicating the temperature is for continuous casting without stirring, and the broken line BL is for stirring according to the present invention. To reiterate, the solid line SL indicates the temperature distribution when the molten metal is not stirred, and the broken line BL indicates the temperature distribution when the molten metal is stirred. However, the outer side (right side in the figure) of the point b to be described later of the solid line SL shows a common temperature distribution in two cases with and without stirring. Further, when not stirred, the semi-solidified layer portion MZ becomes the semi-solidified layer portion MZ1 (thickness L1), and when stirred, the semi-solidified layer portion MZ2 (thickness L2 = L1-L11) thinner than that is thinner. It becomes. 25, as will be described later, the temperature difference between the inner point a and the outer point b of the semi-solidified layer portion MZ1 is ΔTn, the inner surface point c and the outer surface of the semi-solidified layer portion MZ2. The temperature difference from point b is ΔTm.

That is, when not stirred, as can be seen from the solid line SL, the portion of the center line CL shows the highest temperature TH1, and gradually decreases toward the outer periphery, on the boundary line between the liquid portion LP and the semi-solidified layer portion MZ1. It drops to the temperature at point a. Inside the semi-solidified layer portion MZ, the cooling rate is faster than that of the liquid portion LP, and the temperature drops to the temperature at the point b on the boundary line between the semi-solidified layer portion MZ1 and the solid portion SP. In the solid portion SP, the temperature rapidly decreases and reaches the temperature TL in FIG.

On the other hand, when stirring is performed, as can be seen from the broken line BL, the temperature distribution in the liquid (molten metal) is almost uniform, so that the temperature gradient is almost from the center line CL to the inside of the semi-solidified layer portion MZ2. Does not occur. That is, in this case, the temperature of the center line CL is also the temperature TH2 lower than the previous temperature TH1. Thus, as described above, the thickness L2 of the semi-solidified layer portion MZ2 becomes thinner by the thickness T11 than the thickness T1 by stirring. This temperature TH2 continues to a point c inside the semi-solidified layer portion MZ2. In the semi-solidified layer portion MZ2, the temperature decreases from the point c to the point b. Thereafter, the temperature becomes TL as in the case of no stirring.

Here, looking at the semi-solidified layer portion MZ, the thickness becomes the thickness L1 when there is no stirring, and the thickness L2 (= L1-L11) when there is stirring. That is, the thickness L1> L2. Further, the temperature difference between the inner surface and the outer surface of the semi-solidified layer portion MZ is the temperature difference ΔTn when there is no stirring, and the temperature difference ΔTm when there is stirring. Therefore, when comparing the temperature gradient with and without stirring, ΔTn / L1 <ΔTm / L2. When this is compared with Newton's law of cooling, it can be seen that the cooling rate is overwhelmingly faster with cooling.

Considering the quality of various ingots (round bar shape, prismatic shape, etc.), it is desirable that the temperature distribution of the liquid portion LP is uniform, and it is desirable that the cooling is performed at a high speed.

In other words, in the present invention, the liquid phase portion LP at the top of the product, which appears during continuous casting, is not cooled by natural cooling, but is forcibly agitated, whereby the temperatures of the central portion and the peripheral portion of the liquid phase portion LP are obtained. The difference is made as small as possible, and the semi-solidified layer portion MZ is made thin so as to be cooled. As a result, according to the present invention, it is possible to significantly improve productivity while achieving uniform and fine crystals and improving mechanical properties, that is, improving product quality. I understood that.

Furthermore, in order to obtain a cylindrical ingot as a prototype TP for continuous casting, zinc (Zn) was introduced into the sump as a chemical tracer. FIG. 26 shows the prototype divided vertically after solidification. In the figure, when Zn was added, the portion that was liquid was SP (LP), the portion that was a semi-solidified layer portion was SP (MZ), and the portion that was solid was SP.

From the prototype TP, five first specimens (cylinders) A to E were cut out from the position shown in FIG. That is, five first test pieces AE were cut out from the prototype TP in a direction perpendicular to the paper surface of FIG. Further, as can be seen from FIG. 27, five measurement points (measurement point MP1 to measurement point MP5) are defined for each of the first test pieces AE, and five second tests perpendicular to the paper surface from these measurement points. I cut out a piece. That is, five second test pieces A1-A5 were obtained from the first test piece A, and five second test pieces B1-B5 were also obtained from the first test piece B. Similarly, five second test pieces C1-C5, D1-D5, and E1-D5 were obtained from the first test pieces C, D, and E, respectively. As a result, 25 second test pieces were obtained.

27, the directions of the center lines CA, CB,... In which the second test pieces A1-A5, B1-B5,... Are arranged are shown in FIG. . That is, as can be seen from FIG. 26, each center line CA, CB,... Is oriented along the thickness direction of the portion SP (MZ) that was once the semi-solidified layer portion MZ.

The concentration of zinc as the chemical tracer in the 25 second specimens A1-A5, B1-B5,... Is measured, and the concentrations CA1-CA5, CB1-CB5,. Got. Further, average values a1, a2,... A5 of zinc concentrations at the measurement points MP1 to MP5 in the first test pieces AE were determined from the following formulae.
a1 = (CA1 + CB1 + CC1 + CD1 + CE1) / 5
a2 = (CA2 + CB2 + CC2 + CD2 + CE2) / 5
・
・
a5 = (CA5 + CB5 + CC5 + CD5 + CE5) / 5
That is, the average values a1, a2,... Of zinc at the measurement points MP1 to MP5 were obtained from the above formula.

The average values a1, a2,... A5 of the zinc concentration are plotted in FIG. From FIG. 28, it was found that the thickness of the semi-solidified layer portion MZ was about 2 mm.

Such an experiment was repeated to create a plurality of graphs corresponding to FIG. That is, in the continuous casting, the drawing speed (casting speed) was changed variously, and a plurality of graphs corresponding to FIG. 28 were obtained from the prototype TP obtained at that time. These graphs were obtained almost as shown in FIG. That is, when the product was obtained while stirring the molten metal according to the embodiment of the present invention, the thickness of the semi-solidified layer portion MZ did not increase. That is, according to the apparatus of the embodiment of the present invention, the quality of the product is not deteriorated even if the drawing speed (casting speed) of the product is increased.

In addition, an observation end surface SUF2 obtained by performing CMP on the end surface that was lowered by DEP (7 inches) from the end surface SUF1 of the cut-out prototype TP shown in FIG. 26 was observed by SEM. This observation was made on a prototype TP obtained by varying the drawing speed (casting speed). As a result, it was observed that in the prototype TP obtained by stirring the molten metal with the apparatus of the embodiment of the present invention, the crystal structure does not become rough even if the drawing speed (casting speed) is increased.

Claims (14)

1. A molten metal stirring device for stirring molten metal in the mold or molten metal in the mold in a continuous casting apparatus for continuously forming a product by flowing a molten metal of conductive metal into the mold,
   A cylindrical case with an open top that is immersed in the molten metal, and a pipe stored in the case,
   The case has an outer cylinder and an inner cylinder accommodated in the outer cylinder, and a gap for flowing cooling air is formed between the outer cylinder and the inner cylinder. Has a vent hole communicating the inside of the inner cylinder and the gap, and constitutes a cooling air passage from the inner cylinder to the gap via the vent hole,
   Inside the inner cylinder, a magnetic field device in which the pipe is inserted is housed, and the magnetic field device has a magnetic field line from the magnetic field device passing through the inner cylinder and the outer cylinder to the molten metal, Or, the magnetic lines of force that run in the molten metal penetrate through the inner cylinder and the outer cylinder and reach the magnetic field device, and are magnetized with strength.
   Furthermore, the first electrode, penetrating the inner cylinder and the outer cylinder, one end is exposed in the inner cylinder, the other end is exposed outside the outer cylinder and can contact the molten metal, The one end of the first electrode is electrically connected to a lead wire body running in the pipe;
   Furthermore, it has the 2nd electrode attached to the said outer cylinder, and the attachment position to the said outer cylinder of the said 2nd electrode is via a molten metal between the said 2nd electrode and the said 1st electrode. It is set at a position where a flowing current crosses the magnetic field lines and generates a Lorentz force that rotationally drives the molten metal around the vertical axis.
   A melt agitator characterized by that.
2. The first electrode is attached to the case through the bottom plate of the inner cylinder and the bottom plate of the outer cylinder, and the second electrode is higher than the magnetic field device on the outer peripheral surface of the outer cylinder The molten metal stirring apparatus according to claim 1, wherein the molten metal stirring apparatus is attached to a position.
3. 3. The molten metal stirring device according to claim 1, wherein the magnetic field device is magnetized so as to emit or receive a magnetic field line along a horizontal line or a downward line.
4. The melt stirrer according to claim 1 or 2, wherein the magnetic field device is magnetized so as to emit or receive a magnetic force line along a horizontal line and a downward line.
5. The magnetic field device includes a magnet magnetized to emit or receive lines of magnetic force along a transverse line;
   The molten metal stirring apparatus according to claim 4, wherein the molten metal stirring apparatus is configured by vertically laminating magnets magnetized so as to emit or receive lines of magnetic force along a downward line.
6. The molten metal stirring apparatus according to any one of claims 1 to 5, wherein the outer cylinder is made of a conductive material that generates heat when energized.
7. A molten metal stirring device for stirring molten metal in the mold or molten metal in the mold in a continuous casting apparatus for continuously forming a product by flowing a molten metal of conductive metal into the mold,
   A cylindrical case with an open top that is immersed in the molten metal; and a pipe that is accommodated in the case, and a communication gap is formed between the lower end of the pipe and the inside of the bottom surface of the case. The interior of the pipe communicates with the interior of the case through the communication gap to form a cooling air passage.
   The magnetic field device in which the pipe is inserted is accommodated in the case, and the magnetic field device passes through the case to reach the molten metal or runs in the molten metal. Magnetic field lines penetrate through the case and reach the magnetic field device, and are magnetized in strength.
   Further, the first electrode has a first electrode that penetrates the case, one end is exposed to the case, and the other end is exposed to the outside of the case and can be in contact with the molten metal, and the one end of the first electrode Is electrically connected to the lead wire running through the pipe,
   Furthermore, it has the 2nd electrode attached to the said case, The attachment position to the said case of the said 2nd electrode is the electric current which flows through a molten metal between the said 2nd electrode and the said 1st electrode. Is set at a position to generate Lorentz force that crosses the magnetic field lines and drives the molten metal to rotate about the vertical axis.
   A melt agitator characterized by that.
8. The first electrode is attached to the case in a state of passing through the bottom plate of the case, and the second electrode is attached to a position higher than the magnetic field device on the outer peripheral surface of the case. The molten metal stirrer according to claim 7.
9. The melt stirrer according to claim 7 or 8, wherein the magnetic field device is magnetized so as to emit or receive a magnetic field line along a horizontal line or a downward line.
10. The melt stirrer according to claim 7 or 8, wherein the magnetic field device is magnetized so as to generate or receive a magnetic force line along a horizontal line and a downward line.
11. The magnetic field device includes a magnet magnetized to emit or receive lines of magnetic force along a transverse line;
    The molten metal stirring apparatus according to claim 10, wherein the molten metal stirring apparatus is configured by vertically stacking magnets magnetized so as to emit or receive lines of magnetic force along a downward line.
12. The molten metal stirrer according to any one of claims 7 to 11, wherein the case has an outer cylinder made of a conductive material that generates heat when energized.
13. A molten metal stirrer according to any one of claims 1 to 12, a gutter that guides the molten metal from a melting furnace, and a mold that is attached in a state where a molten metal inlet is in communication with the bottom surface of the gutter, The continuous casting apparatus system is characterized in that the molten metal stirring device is incorporated in a state where the lower end side is inserted into the molten metal lead-out path in the bowl.
14. The said molten metal stirring apparatus is hold | maintained with respect to the said soot so that the insertion amount to the said molten metal lead-out path of the said hot metal at the lower end part of the said molten metal stirring apparatus can be adjusted. Casting equipment system.

Images