NZ757587B2 - Molten metal stirring 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. 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

Technical Fiel [ 0001] ates ten The t invention rel to a mol metal stirring device and a continuous casting device system provided with the mol metal stirring device. ound Ar [ 0002] Conventionally, a product (round bar ingot and the like) is obtained by continuously g a mol metal having t t conductivity, that is, a non-ferrous metal mel or a mel of metal other than non—ferrous metal (for example, Al, Cu, Z or Si, or an alloy of at least two of them, or Mg alloy, etc.). [ 0003] I n the continuous casting, for example, it has generally been adopted that a mol metal is introduced from a melting e d. furnace by a crucibl and poured into a mol [ 0004] However, only the present inventors independently have the ing view with respect to the conventional manufacturing method. [ 0005] That is, first, when a mol metal is poured into a mold, the mol metal drops in the air and entraps air. F or this reason, it is inevitable that the quality of a product is degraded. 3O [ 0006] Furthermore, when a t ed from a mold is large (particularly when a cross-sectional area is large), the cooling rate of a molten metal greatly differs between a peripheral portion and a central portion of the product. That is, while the molten metal is cooled rapidly in the peripheral portion of the product, it is cooled more slowly in the central portion than that in the peripheral portion. This resul in significant ences in the crystallographic structure of the metal in the peripheral and central portions of the product.

This inevitably leads to a significant loss of the mechanical properties of the product.

Summary of I Technical Prob [ 0007] i l led Conventionally, persons sk in the art other than the present inventors have not particularly had great dissatisfaction or problems in t quality and tion ency.

Therefore, persons skil in the art other than the present inventors did not have the problem that they had to mak improvements on the manufacturing device and the manufacturing method in terms of product quality and production efficiency. However, as described above, only the i l led present inventors among the persons sk in the art have had a sense of problems (issues) unique to the inventors as described above. That is, the inventors have had a problem that as an engineer, it is necessary to provide a better product with higher efficiency than now.

I t is an object of the present invention to s one or ternative. more of the problems, or e a useful al ution lem Sol to Prob [ 0008] A mol metal ng device according to embodiments of the present invention is a molten metal stirring device that 3O stirs, in a continuous casting device that continuously molds products by pouring a molten metal of a conductive metal into a ten d ten mold, a mol metal to be poured into the mol or a mol metal in the mold. ten ludes The mol metal stirring device inc a cylindrical case with open upper side immersed in the molten metal, and a pipe housed in the case, the case has an outer cylinder and an inner er housed in the outer cylinder, a gap for circulating cooling air is formed between the outer er and the inner cylinder, the inner cylinder has a vent hol communicating the inside of the inner cylinder and the gap to form a cooling air passage ing from the inner cylinder to the gap via the vent hole, a magnetic fiel device in which the pipe is inserted is housed inside the inner cylinder, in the device, magnetic lines of force from the magnetic fiel device penetrate the inner cylinder and the outer cylinder to reach the mol metal, or the magnetic lines of force running in the mol metal are strongly magnetized to penetrate the inner cylinder and the outer cylinder to reach the magnetic fiel device, ectrode further, a first el penetrating the inner cylinder and the outer cylinder is provided of which one end is exposed in the inner cylinder, and the other end is exposed to the outside of the outer cylinder to be in t with the mol ectrode metal, the one end of the first el is electrically connected to a lead wire running in the pipe, further a second el attached to the outer er ectrode is provided, and the position where the second el is attached to the outer cylinder is set at a position where the current flowing through the mol metal between the second ectrode e el and the first el crosses the magnetic lines of force to te a L orentz force that rotationally drives the mol metal about the longitudinal axis. [ 0009] A mol metal stirring device according to the embodiments of the present invention is a molten metal stirring 3O device that stirs, in a continuous casting device that continuously molds products by pouring a molten metal of a conductive metal into a mold, a mol metal to be poured into the mold or a molten metal in the mold. ten ludes The mol metal stirring device inc a cylindrical case with open upper side to be immersed in the molten metal, and a pipe to be housed in the case, a communication gap for owerend conwnunmafionisformed beUNeenthel ofthepfipeand theinner yde ofthe bothnn sufléce ofthe case,the Hfifide of the Mpe and the inmde ofthe case conwnunkate wfih each other Unough the conwnunmafion gap to fonn a cooHng aw passage, a magnefic fim devmein whkfithe mpe m msefled m housed ingde the case,in the devme,rnagneUc Hnes offorce from the magnetic fiel device penetrate the case to reach the mofi metaL orthe magneUc Hnes OffOKB runnmg Hithe fien lare n1o nweta strongly nwagneUzed to penetrate the case to hernagnetm fiekldevme, ectrode further, a first el penetrating the case is provided Of\NhiCh one end S exposed to the case, and the other end S exposed to the outgde of the case to be in contactiNKh the ten ectrode mol metal, the one end of the first el is electrically ted to a lead wire running in the pipe, ectrode further a second el ed to the case is ectrode provided, the position where the second el is attached to the case 5 set at a posnjon vvhere the current flomnng through ten ectrode the mol metal between the second el and the first xirode ek crosses the nwagnefic Hnes of force to generate a enIhetal aboutthe LorentzforcethatrotannaHy deesthernoh longhudmalaXS. [ 0010] A conUnuous casUng devme sysUnn mg to the enwbodunents ofthe presentinvenfion is pnaned mch any of the above-descflbedrnohenlhetalsfirflng devme,eacrudbk3for ten d guiding mol metal from a g furnace, and a mol attached to a botton1 surface of the crucHfle in conwnwunicanr 3O \Nhh nlhetalinmt. ThernofienrnetalsUang devme b incorporated in a state in which a lower end side of the molten metal stirring device is inserted into a mol metal discharge passage Hithe crucHfle.

Brief Description of Drawings F I 1 is a partial longitudinal cross-sectional explanatory view illustrating the entire configuration of a uous casting device as a first embodiment of the present invention. is a longitudinal explanatory view which longitudinally cut the mol metal stirring device in the device of F I 2 A is a partial longitudinal cross-sectional explanatory view rating the entire configuration of a continuous casting device of a seventh embodiment I GS. corresponding to the embodiment of F 2.

FIG. ZB is an explanatory view illustrating a current f path according to the ment of FIGS. 2A.

F I 3 is an operation atory view explaining operation of the mol metal stirring device in the device of F I 1. is a partial longitudinal cross—sectional explanatory view illustrating the entire configuration of a continuous g device as a second embodiment of the present ion. is an operation explanatory view explaining operation of the mol metal stirring device in the device of is a partial longitudinal sectional explanatory view illustrating the entire configuration of a continuous casting device as a third embodiment of the present invention.

F I 7 is an operation explanatory view explaining operation of the mol metal stirring device in the device of F I 6. is a longitudinal explanatory view of a magnetic field device of the molten metal stirring device in the devices of 3O FIGS. 1 and 2. is an explanatory plan view of the magnetic field ten I GS. device of the mol metal stirring device in the s of F 1 and 2. is a longitudinal explanatory view of a modification of the magnetic field device of the molten metal stirring device in the devices of FIGS. 1 and 2.

F I 9b is an atory plan view of a modification of the magnetic field device of the molten metal stirring device in I GS. the devices of F 1 and 2. a is a longitudinal atory view of a magnetic d ten fiel device of the mol metal stirring device in the devices of FIGS. 4 and 5.

G. d F I 10b is an explanatory plan view of the magnetic fiel ten I GS. device of the mol metal ng device in the s of F 4 and 5.

F I 11a is a longitudinal explanatory view of a magnetic d ten fiel device of the mol metal stirring device in the devices of FIGS. 6 and 7. d G.

F I 11b is an explanatory plan view of the magnetic fiel device of the mol metal stirring device in the devices of FIGS. 6 and 7. c is an atory bottom view of the magnetic d ten fiel device of the mol metal stirring device in the devices of FIGS. 6 and 7. is a partial longitudinal cross—sectional explanatory view illustrating the entire configuration of a continuous g device as a fourth embodiment of the present invention. is a longitudinal atory view which longitudinally cut the mol metal stirring device in the device I G. of F 12.

G. A F I 13 is a partial longitudinal cross—sectional explanatory view of the entire configuration of a continuous casting device of an eighth embodiment corresponding to the embodiment of . 3O is an operation explanatory view explaining operation of the molten metal stirring device in the devices of F I 12 and 13. is a structural operation explanatory view for explaining the configuration and operation of a mol metal stirring device used for a continuous casting device as a fifth embodiment of the present invention.

F I 16 is a structural operation explanatory view for explaining the uration and operation of a molten metal ng device used for a continuous casting device as a sixth embodiment of the present invention.

F I 17 is a partially udinal explanatory view of one continuous prototype obtained by switching the state in which ten G. the mol metal stirring device in F I 1 is removed and the state in which the mol metal stirring device is used as it is. is a longitudinal explanatory view illustrating a I G. . part of the prototype of F 17 is a longitudinal explanatory view illustrating a different part of the prototype of F I 20 is a longitudinal atory view illustrating a r different part of the prototype of F I 21 is a longitudinal explanatory view rating a process of manufacturing a part of the prototype of . is a longitudinal explanatory view illustrating a s of manufacturing a part of the prototype of ; is a longitudinal explanatory view illustrating a process of manufacturing a part of the prototype of . is a longitudinal explanatory view illustrating a process of manufacturing a prototype for explaining a further different experiment.

F I 25 is a temperature distribution explanatory view indicating temperature distributions of a mol metal (liquid), a dified semi—soli layer portion, and a prototype (solid) in the I G. 4. manufacturing process of F 2 is a longitudinal explanatory view ting a k en positional relationship of a sample (first test piece) ta out 3O from the ype corresponding to . is a longitudinal explanatory view indicating a positional relationship in each sample (first test piece) of a sample (second test piece) further tak out from each sample (first test piece) taken out. is a graph indicating a zinc concentration of the sample (second test piece) taken out.

Description of Embodiments [ 0012] indicates the entire configuration of a continuous casting system as a first embodiment of the present invention, and indicates the case where a round rod-l ingot is obtained as a product P. As can be seen from this F I 1, this device is low ten configured to al a mol metal M from a g furnace (not illustrated) of nonferrous metal or other metal of a tor such as Al, Cu, Z or an alloy of at least two of them, d e or an Mg alloy to f low into a mol 1 through a crucibl 2 to finally obtain the product P. I n the first embodiment of the present invention, in order to improve the quality of the y obtained t P, a mol metal stirring device 3 is provided. ten d ten That is, the mol metal stirring device 3 is hel in the mol metal M at the end portion of the crucibl 2 in a state of being immersed by a predetermined means. By the mol metal l orentz stirring device 3, as wil be described in detail later, by a L ten d e force, the mol metal M is fed into the mol 1 whil being rotationally driven around the mol metal stirring device 3, as can be seen from (first embodiment). Another ated l embodiment of the rel invention wil be y described. ten ten By the mol metal stirring device, the mol metal M in the d d G. mol 1 is fed to the mol 1 in F I 4 (second embodiment), and ten e d the mol metal M in the crucibl 2 and in the mol 1 are both d G. e fed to the mol 1 in F I 6 (third embodiment), whil being orentz rotationally driven by the L force, to obtain the product P with improved quality [ 0013] 3O Hereinafter, a first embodiment of the present invention will be further described in detail.

In the molten metal M from a melting furnace d e (not illustrated) is introduced to the mol 1 by the crucibl 2.

That is, the mold 1 is attached to the tip (end) of the crucible 2 in a icating state. M specifically, a molten metal et d inl of the mol 1 is in communication with the bottom of the crucible 2, and a molten metal stirring device 1 is incorporated in a state in which the lower end side thereof is inserted into a ten e mol metal discharge passage of the crucibl 2. [ 0015] ten e The mol metal M passes from the crucibl 2 to the d ed l ed id mol 1 and is cool there to obtain a so-cal sol phase l ed product P with improved quality. A so-cal liquid phase ten ed mol metal M which has not been cool down yet is present on the upper side of the t P. That is, as can be seen d ten from in the mol 1, the upper part is the mol metal M in liquid phase, and the lower part is the product P in a sol phase, and these are in t with each other to form a downwardly convex paraboloid interface I . [ 0016] e ten I n the crucibl 2, the mol metal stirring device 3 is hel in a floating state by a desired means. The position of the mol metal stirring device 1 is vertically adjustable in e d with respect to the crucibl 2 and the mol 1. Therefore, in the lower end of the mol metal stirring device 3 is d ten slightly inserted into the mol 1, but the mol metal stirring d l ten device 3 can be hel such that al of the mol metal ng device 3 is t in the l 2. is a longitudinal ten G. sectional view of the mol metal stirring device 3, and F I 3 is an enlarged view thereof as an operation explanatory view. [ 0017] ten G.

I n particular, as can be seen from F I 3, the mol ludes metal stirring device 3 inc a substantially cylindrical case 6 having a double structure and an open upper side, a magnetic 3O field device 7 having a permanent magnet 18 housed in the case 6, and an electrode portion 8 having a pair of electrodes ectrode ectrode (first el 24 and second el 25) ed to the case 6. The molten metal stirring device 3 is configured to have an air g structure capable of air cooling with compressed air, focusing on the high temperature property of the molten metal M. By this air cooling, for example, the permanent magnet 18 of the ic fiel device 7 can maintain and exert its ability. [ 0018] More specifically, particularly in the case 6 has an outer cylinder 11 and an inner cylinder 12 which are both made of a refractory material and formed as a cylindrical member with open upper side. A gap 14 for flowing compressed air for cooling is formed between the outer cylinder 11 and the inner cylinder 12. Furthermore, in order to pass this air for cooling, a plurality of vent hol 12a is formed concentrically on the bottom of the inner cylinder 12 to communicate the inside of the inner cylinder 12 with the gap 1 As a result, a cooling air passage extending from the inner cylinder 12C to the gap 14 and r to the atmosphere via the vent hol 12a is formed.

G. w That is, as can be seen from F I 3, as indicated by the arro ARl, the compressed air for cooling f lows into the inside of the inner cylinder 12 from above, reaches the bottom, s the bottom of the gap 14 from the vent hol 12a, rises in the gap leased 14, and is eventually re to the atmosphere. During this time, the compressed air exchanges heat in a f low path to cool d k e. ten the magnetic fiel device 7 and the l i The mol metal ng device 3 can be fixed to a desired external fixing device by a flange portion of the outer cylinder 11. r, in the mol metal stirring device 3, the depth of immersion in the e d l 2 and the mol 1 can be appropriately adjusted. I n ten , this way it is possible to more appropriately stir the mol metal M by adjusting the immersion depth in accordance with k e ten the physical properties and the li of the mol metal M used on site. 3O [ 0019] The ic field device 7 is housed in the inner cylinder 12 in a state in which a stainl steel pipe 16 is inserted, as can be seen from Details of the magnetic d lustrated fiel device 7 are i l in FIGS. 8a, 8b. That is, the magnetic field device 7 is configured as a cylindrical permanent magnet 18 having an integral structure, and has a through hole 18a for allowing the pipe 16 to penetrate in the l axis portion. The permanent magnet 18 is magnetized such that the central side is an S pole, and the outer peripheral side is an N pole. (It is obvious that the direction of magnetization may be opposite to the above. I n this case, the direction of current f low can be changed by an external power supply panel 27 described later, as necessary.) As a result, as can be seen from G. L F I 3, magnetic lines of force M radiate from this magnetic d ten e fiel device 7 and run in the mol metal M in the crucibl 2.

N ow that, the configuration of the magnetic fiel device 7 is not lustrated limited to those i l in FIGS. 8a and 8b, and any device may be used as long as it has the magnetic lines of force M as lustrated G. i l in F I 3. F or example, examples are indicated in FIGS. 9a and 9b. The permanent magnet 18 in these drawings has a plurality of rod-l ent magnet pieces 19 which are long in the al direction. The aspects of ization of each permanent magnet piece 19 are indicated in FIGS. 9a and 9b. The magnetic fiel device 7 is configured by arranging the respective permanent magnet pieces 19 concentrically in plan view. As bed above, the ic fiel device 7 is housed in the inner cylinder 12 in a state in which the pipe 16 is inserted, as can be seen from As a result, the magnetic fiel device 7 radially emits the magnetic lines of force ML, ten e which reach the mol metal M in the crucibl 2 and run therethrough. When the compressed air f lows in the inner es e cylinder 12, it s the vent hol 12a whil cooling the magnetic fiel device 7 and the l ike. [ 0020] As can be seen from a guide rod 22 made of a 3O conductive material such as copper, which functions as a lead wire, is housed inside the stainless steel pipe 16. The first ectrode el 24 made of tungsten or graphite is attached to the lower end of the guide rod 22 in an electrically conducting state. ectrode The first el 24 penetrates the inner cylinder 12 and the outer er 11 in a liquid tight state (at least a molten metal- tight state), exposes the tip (lower end) to the outside, and ten e contacts the mol metal M in the crucibl 2. [ 0021] ectrode A second el 25 formed in, for example, a ring shape of graphite or the like, which makes a pair with the first ectrode el 24, is attached to the outer peripheral surface of the outer cylinder 11 so as to be detachably inserted. Thereby, when the mol metal stirring device 3 is ed in the ten e lustrated G. mol metal M of the crucibl 2, as i l in F I 3, a ectrode current i f lows from the second el 25 to the first ectrode ten el 24 via the mol metal M. As a result, the magnetic lines of force M L from the magnetic fiel device 7 and the current i flowing n the first el 24 and the second ectrode el 25 intersect to generate a L orentz force. Thereby, as lustrated ten e i l in the mol metal M in the crucibl 2 is ectrode rotationally driven. Now, the second el 25 can be replaced with another one as needed, for example, at the time of wear and tear. [ 0022] ten e The mol metal M in the l 2 can be rotationally driven, that is, d, and the following advantages can be obtained. [ 0023] First, impurities present inside rises in the mol metal M and gather on a surface portion, and the quality of the mol metal M other than the surface n, that is, the mol metal M g into the mol 1 is improved. Thereby, the quality of the product P obtained by the mol 1 can be improved. [ 0024] Further, the molten metal M is stirred in the crucible 2 3O and flows into the mold 1 while rotating. Thereby, the molten metal M is also rotated in the mold 1. That is, the molten so so d metal M is al onally driven indirectly al in the mol 1.

By the rotation in the mold 1, the molten metal M solidifies in a state where the temperatures of the inner portion and the outer portion are averaged. As a result, in combination with the removal of impurities in the molten metal M as described above, l ent the product P with more excel quality can be obtained.

Such a mechanism for y improvement applies to all the other embodiments and variations described bel [ 0025] G. ectrode Referring back to F I 1, the first el 24 and the ectrode second el 25 are connected to the external power supply panel 27 such that a desired DC current can be supplied. The amount of supplied current can be adjusted by the external power supply panel 27, and a polarity can al be switched. By switching the polarity, the rotation ion of the mol metal e d M in the l 2 and the mol 1 can be reversed. Such so e control can al be performed whil watching the stirring state of the mol metal M on site. As a result, the product P with high quality can be obtained without being inf by the characteristics of the mol metal M to be used by controlling individually for each characteristic of the mol metal M.

Moreover, such control is possible by simple operation with the external power supply panel 27, and the utility on site is extremely high. [ 0026] ation F or example, as can be seen from a circul path 1a for circulating cooling water is formed inside the mol 1. ation Among the circul paths 1a, a plurality of places facing the product P are used as cooling water ports 1b penetrating to the e ed outside. The products P are ctured whil being cool by the cooling water rged from the g water ports 1b.

As described above, since the mol metal M is rotationally so d driven al in the mol 1, it is possible to obtain the t P with higher quality by achieving uniform temperature. The 3O reason why the shape of the interface I is a downwardly convex paraboloid as indicated in is that the cooling rates of the outer portion and the inner portion of the mol metal M are different. A curve in the vicinity of the apex of the paraboloid of the interface I becomes steep as the size of the product P increases, that is, as cross-over of the cross section increases.

Further, as a drawing speed of the product P increases, the . v e above-described cur becomes further sharp as well As a result, the ence between the cooling rates of the outer and inner portions ses. As a result, the occurrence of variations in the internal quality of the t P cannot be avoided. However, as described above, since the mol metal so d M is stirred al in the mol 1 to make the temperature uniform, products with higher quality can be achieved because impurities so e are al removed in the crucibl 2. [ 0027] Although the operation of the first embodiment of the present invention can be understood from the above ption, l ow. it wil be briefly described bel [ 0028] F rom the external power supply panel 27 of as lustrated lowed G. i l in F I 3, the current i is al to f low between a es ectrode ectrode pair of the el (first el 24 and second el ). The current i intersects the ic line of force M to generate a L orentz force f. By the L orentz force f, the mol e ten metal M in the crucibl 2 (and a small amount of the mol d lustrated metal M in the mol 1) is rotationally driven as i l in FIG. ten d e 1. Thereby, the mol metal M f lows into the mol 1 whil rotating, and is cool by the cooling water from the cooling idified e d water port 1b and sol whil being rotated in the mol 1 to form the product P. Here, the onal speed of the mol e d metal M in the crucibl 2 and in the mol 1 can be adjusted by ing the amount of current from the external power supply panel 27 That is, although the quality, properties, components, etc. of the mol metal M flowing from a melting furnace (not illustrated) are not always the same, the amount of current is 3O adjusted depending on the y, properties, etc. of the molten metal M used, and the product P with more appropriate quality can be obtained regardless of the physical properties of the molten metal M. Further, by changing the flow direction of the current i litt by little, the direction of rotation of the molten metal M in the crucible 2 can be changed in a very short time so as to be in a so-called vibration state, whereby the removal of impurities can be further promoted. [ 0029] Next, a second embodiment of the present invention will be described. [ 0030] According to the second embodiment of the present invention, as can be seen particularly from F I 4, a permanent A G. ten magnet 18 (refer to F I 5) mounted on a mol metal stirring device 3A rotationally drives the mol metal M in the d ten mol 1 before solidification, not the mol metal M in the e ven ten d crucibl 2 E if the mol metal M in the mol 1 is stirred, as can be understood from the description of the first embodiment of the present invention, it is s that substantially the same effects as those of the first embodiment of the t invention can be obtained. [ 0031] after, points different from the first embodiment of the present invention wil be mainly described. is a vertically enlarged operation explanatory view of the mol metal stirring device 3A mounted according to the second embodiment of the present invention i l in The ten l lustrated mol metal stirring device 3A i in s from ten lustrated the mol metal stirring device 3 i l in only in the direction of the magnetic lines of force ML, and the other configuration is substantially the same, as can be easily seen from the comparison of the drawings. That is, the permanent d A A I G. magnet 18 of the magnetic fiel device 7 of F 5 emits the magnetic lines of force M L in the lower side in the drawing.

Details of the magnetic field device 7A are illustrated in FIGS. 3O 10a and 10b. a is a longitudinal sectional view, and b is a plan view. As can be seen from these gs, the most GS. outer shape is al the same as in F I 8a and 8b, but the aspect of magnetization is different, and the upper part of the rical body is magnetized to the S pole and the lower part to the N pole.

‘ I6 As can be seen from F I 5, the magnetic lines of force M L from the magnetic field device 7 and the current i flowing ectrodes ectrode between a pair of the el (the first el 24 and the ectrode second el 25) cross on the outside of the bottom of the d ten outer cylinder 11 of the magnetic fiel device 7 A. The mol d l lustrated metal M in the mol 1 is rotationally driven as i in FIG. orentz 4 by the L force f ted thereby. [ 0033] As described above, in the second embodiment of the present invention, configurations and operations other than those described above are substantially the same as those in the first embodiment of the present invention, and thus detail descriptions thereof will be omitted. [ 0034] Next, a third embodiment of the t invention will be described. [ 0035] According to the third embodiment of the present invention, as can be seen in particular from by permanent magnets 1881 and 1882 (refer to mounted ten ten on a mol metal stirring device 38, both the mol metal M e ten d in the crucibl 2 and the mol metal M in the mol 1 before idification sol are directly rotationally driven together. Since the ten e ten mol metal M in the crucibl 2 and the mol metal M in the mol 1 are directly stirred together, it is obvious that substantially the same or more advantages as those of the first embodiment of the present invention and the second embodiment of the present invention can be obtained. [ 0036] 3O More specifically, is a longitudinal enlarged operation explanatory view of the molten metal stirring device ten G. 38 of F I 6. The mol metal stirring device 38 (third embodiment) illustrated in have ons both of the ten ted mol metal stirring device 3 (first embodiment) i l in and the molten metal ng device 38 d ment) illustrated in As can be seen from in the specific uration, the magnetic fiel device 7 8 is integrally fixed in a state in which the first cylindrical ent magnet 1881 and the second cylindrical permanent magnet 1882 are stacked vertically through a nonmagnetic spacer 30, s lustrated G. and the detail of them are i l in F I 11a cal explanatory view), b (top view) and c (bottom view). As can be seen from F I 11a and 11b, the first ludes permanent magnet 1881 inc a plurality of permanent magnet pieces 19 as with those i l in FIGS. 9a and 9b, and the inner side is set to the S pole, and the outer side is set to the N pole. Further, as can be seen from FIGS. 11a and 11c, the second permanent magnet 1882 is magnetized with the N pole at the upper side and the S pole at the lower side, as in the case i l in FIGS. 10a and 10b. The first permanent magnet 1881 and the second permanent magnet 1882 are ally formed across the spacer 30. [ 0037] As can be seen from the magnetic lines of force M L from the permanent magnet 1881 of the magnetic fiel device 7 8 and the current i flowing between a pair of the ectrodes ectrode ectrode el (first el 24 and second el 25) cross on the outside of the side surface of the outer cylinder 11. Further, the magnetic lines of force M L from the second permanent d 8 magnet 1882 of the magnetic fiel device 7 and the current i ectrodes ectrode flowing between a pair of the el (first el 24 and ectrode second el 25) cross on the outside of the outer cylinder 11 of the ic fiel device 7 A. Due to two types of the l lustrated L orentz force f generated thereby, as i in in the crucible 2, it is rotationally driven on the outside of the outer 3O peripheral surface of the magnetic field device 78 and on the outside of the bottom in the mold 1.

In the third embodiment of the present invention, configurations and operations other than those described above are substantially the same as those in the first and second embodiments of the present invention, and thus detailed descriptions thereof will be omitted. [ 0039] I n the first to third embodiments of the present invention described above, the case 6 has a doubl structure of the outer cylinder 11 and the inner cylinder 12, and the gap 14 is formed n them, and compressed air for cooling is distributed to 4. so the gap 1 However, the strength of the case 6 can al be increased by overlapping the outer cylinder 11 and the inner cylinder 12 in cl t without gaps. I n this case, a f low path of the cooling air is d separately. The fourth to sixth ments of the present invention embodying this lustrated technical concept are i l in FIGS. 12 to 16. I n these embodiments, compressed air for cooling is fed from the pipe 16C. [ 0040] Next, first a fourth embodiment of the present invention wil be described. [ 0041] A fourth embodiment of the present invention is lustrated 4. i l in FIGS. 12 to 1 As can be seen particularly from , in the present embodiment, the mol metal M in the d idification mol 1 before sol is rotationally driven by the permanent magnet 18C mounted on the mol metal stirring device 3C. I n the fourth embodiment of the present invention, lustrated GS. a permanent magnet equivalent to those i l in F I 8a ten I G. and 8b is used. The mol metal stirring device 3C of F 14 (the fourth embodiment of the present invention) and the mol metal stirring device 3 of (the first embodiment of the present invention) are different in that the case 6C is 3O formed by polymerizing the outer cylinder 11C and the inner cylinder 12C without a gap, and compressed air for g is fed from a slightly thicker pipe 16C. The inner cylinder 12C can be configured to function as a heat ting cylinder by a heat insulating . A ication gap for communication is formed between a lower end of the pipe 16C and a bottom surface of the inner cylinder 12C. Thus, the inside of the pipe and the inside of the case communicate with each other through the communication gap to form a cooling air passage, and the inside of the pipe and the inside of the inner cylinder are communicated through the ication gap to form the cooling air e. As a result, the ssed air fed into the pipe 16C reaches a gap 14C between the pipe 16C and the inner cylinder 12C from the lower end of the pipe 16C as indicated by an arro ARZ, and is inverted and raised to be discharged to the outside. The permanent magnet 18C and the k e ed li are cool by the reversing and rising compressed air. [ 0042] Other urations and operations in the fourth embodiment are the same as those in the above-described embodiment, and thus detail description will be omitted. [ 0043] Next, a fifth embodiment of the present invention will be described. [ 0044] The fifth embodiment of the present invention is to ten d directly drive the mol metal M in the mol 1 as in the second embodiment of the present invention of tes ten i l a mol metal stirring device 3D as a principal part.

I n the fourth embodiment of the present invention, a ic d D fiel device 7 with a permanent magnet 18D equivalent to that lustrated G. i l in F I 10a is used. Other configurations and operations are substantially the same as those in F I 14 and , and therefore detail description will be omitted. [ 0045] Next, a sixth ment of the present invention will be 3O described. [ 0046] The sixth embodiment of the present invention is to directly drive the molten metal M in the crucible 2 and the ten d mol metal M in the mol 1 as in the third embodiment of the present invention of A molten metal stirring device 3E as a principal part is shown in . I n the sixth embodiment d E of the present invention, a magnetic fiel device 7 with a first permanent magnet 18E1 and a second permanent magnet 18E2 lustrated G. equivalent to those i l in F I 11a is used. The other configuration is substantially the same as those in FIGS. 14 and 7, and therefore detail description will be omitted. [ 0047] Next, a seventh ment of the present invention will be described. [ 0048] The seventh embodiment of the present ion is lustrated i l in , and the outer cylinder 11D in the case 6D is made of a conductive material that tes heat by energization to reach several hundred degrees cl to the ten ectrical temperature of the mol metal. Further, the el resistance of this tive material is larger than that of the mol metal M used. As the conductive material, various material such as graphite can be used, and any material may be used as long as it has fire resistance and is resistant to the mol metal used. [ 0049] ectrode ectrode r, the upper second el 25D of the el ectrode n 8D is provided above the second el 25 of so as not to contact the mol metal M in actual use. [ 0050] The other uration is substantially the same as the I G. embodiment of F 2. [ 0051] I n the seventh embodiment of the present invention, as described above, the outer cylinder 11D is capable of self- 3O heating by energization. Due to its self-heating, for example, the outer er 11D can reach several hundred degrees Thus, by setting to a high temperature by energization prior to actual use, it can be immediately sunk in the molten metal in actual use, and it is possible to reduce waste of time as much as possible. That is, according to this embodiment, it is not necessary to wait for several hours to submerge the molten metal stirring device 3D in the mol metal and ly operate it. [ 0052] is an explanatory view illustrating paths of current in the mol metal stirring device 3D. As can be seen from the arrow A RD in , the current from a positive terminal 27 of the external power supply panel 27 passes from ectrode the second el 25D through the outer cylinder 11D such as graphite, f lows in the mol metal M having a relatively low ectric e el resistance, s the first el 24, and returns to the negative terminal 27b of the al power supply panel 27. [ 0053] lustrates G. A F I 13 i l an eighth embodiment of the present invention. [ 0054] The eighth embodiment of the present invention exemplifies a configuration in which, as compared with the lustrated ectrode device i l in , a second el 25E of an ectrode ten el portion 8E of the mol metal stirring device 3E is provided at the top as in the embodiment of , and an outer cylinder 11E in a case 6E is formed of a conductive material such as graphite. Others are substantially the same as the example of , and therefore detail description wil be omitted. [ 0055] According to each embodiment described above, the following advantages can be obtained. (1) The stirring efficiency is extremely high because a molten metal is ly stirred. 3O (2) It is possible to respond efficiently also to a large- sized ingot. (3) I n the case of a large ingot, a plurality of mol metal stirring s may be incorporated. (4) The depth to the interface of the ingot in a mol varies depending on a g speed, size and the like of the product. I n this case, the molten metal can be stirred more riately by ing the immersion depth of the mol metal stirring device into the crucible and the mold. (5) The mol metal stirring device can be made l ation. compact, and thus, a large space is not required for instal (6) Thereby, the mol metal stirring device can be easily applied to the existing molding device and the like. (7) The crystal structure of the product (ingot) can be refined. (8) It is possible to make the crystal structure of the product (ingot) uniform. (9) The production speed of the product can be increased.

F or example, the production speed can be increased about 10 to (10) Since the mol metal is internally stirred, the quality of the product can be improved by preventing oxidation of the mol metal. [ 0056] As described above, the continuous casting device of the ments of the present ion provides various ages. Among the advantages, the improvement of the tion speed (productivity) of the product will be r described bel [ 0057] I n general, in continuous casting, the productivity of a product depends on the drawing speed of the product.

Productivity can be improved by increasing the drawing speed.

However, if the g speed is increased beyond a certain rate, one or more longitudinally extending crac may occur inside the product. The presence of the crac can be confirmed, for 3O example, by cutting the product after cooling and observing the inside of the product.

As described above, conventionally, even if it is intended to improve the productivity, there is a limit in increasing the drawing speed, and therefore, the productivity cannot be sufficiently improved. [ 0059] However, according to the continuous casting device according the embodiments of the present invention, it is possible to obtain a high quality product having no crack therein ev if the drawing speed is increased more than the speed in the conventional continuous casting device. Although this can be understood from the ation described above, the present inventors have confirmed this by ting experiments and actually manufacturing a prototype. [ 0060] I n addition, as a criterion for determining the quality of the product, there is a degree of refinement of the crystal structure. I n other words, uality products are products in which the crystal structure is further refined. I n order to refine the crystal structure, the mol metal may be quenched rapidly. That is, conversely, the l ure is not refined ess ed. unl it is rapidly cool [ 0061] I n the process of uous casting, in the upper part of the mold, a sol phase portion SP (refer to SP1 in and idified ten the like) already sol by the g of the mol metal, and a liquid phase portion L P (refer to L P1 in and the idified like) to be sol are present adjacent to each other to form an interface. Furthermore, at the interface between the two, a dified Z 2 1 semi—soli layer portion (Mushy Zone) M (refer to M in G. id F I 21) having an intermediate property between a sol phase dified and a liquid phase appears. The semi-soli layer portion M Z is a transition layer in the process of transition from the liquid phase to the solid phase. 3O [ 0062] The present inventors have uniquely k nown by manufacturing a number of products and cutting and ing the ts that when cooling is performed rapidly, this semi- idified Z sol layer portion M becomes thin, and when cooling is performed gradually, it becomes thick. Therefore, it is said that conversely when the semi-solidified layer portion M is thin, the quality of the crystal structure in the sol phase portion SP is fine and excellent, and when it is thick, the quality of the crystal structure in the sol phase portion SP is rough and poor. I n dified other words, from the thickness of the semi-soli layer n MZ, it can be understood whether the internal crystal structure of the product is fine good quality or coarse poor quality. [ 0063] However, according to the continuous casting device of the embodiments of the present invention, the semi-sol phase portion M does not become thick even if the drawing speed is increased more than the speed in the conventional continuous casting device. This is because, gh it has not been performed or has been originally impossible in the conventional continuous casting device, according to the continuous casting device of the embodiments of the t invention, the mol d e s metal is ed to the mol as a stirring state, and this mak it possible to stir the mol metal immediately before it idifies d. sol in the mol That is, according to the continuous casting device of the embodiments of the present invention, it is possible to obtain a good quality product even if the production efficiency is sed. This has been confirmed by the following experiments conducted by the present inventors. [ 0064] (Experiment 1) Outl of experiment dified The liquid phase portion L P and the semi-soli layer portion M Z are then completely solidified, and only the sol phase portion SP is formed. In the experiment conducted by 3O the t inventors, as can be confirmed visually, in the finally obtained prototype TP, the liquid phase portion LP and dified Z the semi-soli layer portion M which appear only in the process of production, which originally disappears are made to appear. That is, gh al prototypes TP are naturally obtained as solid (solid , when viewed at a moment in the cturing process, the ype TP includes three solid id as portions including a first sol portion SP (MZ), which w once liquid phase portion LP, a second solid portion SP (MZ), which dified as w once a semi-soli layer portion M2, and a the third id id. sol portion SP (SP), which was once a sol I n this experiment, these three sol portions can be visually grasped in the prototype TP such that the quality of the prototype TP can be easily determined. [ 0065] l id That is, in general, al the finished products are sol phase portions SP, the liquid phase portion L P and the semi- sol layer portion M Z disappear, and the liquid phase dified Z n L P and the semi—soli layer portion M cannot be visually fied. However, in this ment, at a certain moment in the process of production, special treatment is applied to manufacture the finished product as a sol product lustrated (prototype), at the certain moment, as i l in , a portion that was once the liquid phase portion LP, a portion that dified was once the semi—soli layer portion M2, and a portion that was the sol phase n SP. [ 0066] Detail of experiment (1) A manufacturing experiment of a ype (a luminum l cylindrical ingot of a (round ingot)) wil be described.

The manufacturing experiment w conducted by the present inventor in order to confirm the improvement in productivity which is the effect of the continuous casting device of the present invention described above. I n this manufacturing experiment, the continuous casting device of the embodiment of the present ion and the uous casting device of the 3O embodiments of the present invention from which the molten metal stirring device 3 is d nuous casting device before improvement) have been used. [ 0067] That is, when manufacturing the prototype TP using the continuous casting device of the embodiment of the present invention in the present inventors have switched a state ten I G. in which the mol metal stirring device 3 of F 1 is removed (continuous casting device before improvement) and a state in which the mol metal stirring device 3 is used as it is (a continuous casting device according to the embodiment of the present invention) to produce one continuous prototype TP ted itate i l in . I n , to facil understanding, a part of the prototype TP is brok (cut). That is, the inside of the prototype TP can be ed by longitudinally cutting after production. Now that, even if the continuous casting device lustrated according to the embodiment of the present invention i l in in FIGS. 4, 6, 12, 15 and 16 is used instead of the mol l lustrated metal stirring device 3 i in it is obvious that the ar I G. prototype TP simil to that of F 17 can be obtained. [ 0068] lustrated G.

I n the prototype TP i l in F I 17, a first prototype unit 100 is a portion manufactured by the continuous casting device before the improvement, and a second prototype unit 200 is a portion manufactured by the continuous casting device of the ment of the present ion.

Furthermore, the first prototype unit 100 is ed with a s low speed drawing portion 50A obtained by drawing at a low drawing speed (casting speed) in the direction of arrow A and a first high speed g portion SOB obtained by drawing at a drawing speed (casting speed) faster than that. On the other hand, the second ype unit 200 has a second high speed g portion 608 obtained by drawing at the same drawing speed (casting speed) as the first high speed drawing portion SOB. [ 0069] 3O As will be described later, as apparent from the comparison between the first high speed drawing portion 50B and the second high speed drawing portion 608, the first high speed drawing portion SOB obtained by the continuous g device before the improvement has a cl C. However, no cracks have been observed in the second high speed drawing portion 608 obtained by the continuous casting device of the present invention. That is, ing to the experiment ted by the present inventors, it has been confirmed that according to the continuous casting device of the present invention, even if the drawing speed (casting speed) is high, it is possible to obtain a cast product without crac inside. That is, productivity coul be improved in continuous casting. [ 0070] (2) Hereinafter, detail of the above-described manufacturing ment will be described. As an experiment, an experiment A for obtaining the low speed drawing portion 50A in the first prototype unit 100, an experiment B for obtaining the first high speed drawing portion SOB, and an experiment C for obtaining the second high speed drawing portion 608 in the second prototype unit 200 have been d out. [ 0071] The low speed drawing portion 50A, the first high speed drawing portion 50B, and the second high speed drawing portion 60B are 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 l lustrated high speed drawing portion 60B are i enlarged in FIGS. 18, 19, and 20, respectively. N ote that, although each of FIGS. 18, 19, and 20 is a sectional view of part of the prototype (solid) TP, from these F I 18, 19, and 20, it is understood that the internal appearance of the mol 1 at each instant in the process of manufacturing by the continuous casting device is lustrated i l in FIGS. 21, 22, and 23 where three phases of solid, semi-solidified layer portion and liquid coexist. That is e 3O the ype (product) TP is obtained as it represents a certain moment in the manufacturing process. Therefore, hereinbelow, F I 21, 22, and 23 will be described using an explanatory view illustrating the internal appearance of the mold at a certain moment in the product manufacturing process.

[0072] (2)-1 First, Experiments A and B for manufacturing the ted G. first prototype unit 100 (50A, 508) i l in F I 17 will be described. Details of the low speed drawing n 50A and the first high speed drawing portion 508 in the prototype TP are lustrated i l in FIGS. 18 and 19. [ 0073] When the prototype unit 100 as a product (casting product) is manufactured by drawing with the continuous casting device before the ement which remov the mol metal stirring device 3 from the continuous casting device of F I 1, the drawing speed (casting speed) is first made low and then switched to high. I n other words, the initial low speed drawing resul in the low speed drawing portion 50A ts I G. of F 17, and the high speed drawing thereafter resul in the first high speed drawing portion SOB. [ 0074] Condition 1 (experiment A) at the time of the low speed drawing and condition 2 (experiment B) at the time of the high lows. speed drawing are as fol r, as ted in FIGS. 21 and 22 indicating respective s in the manufacturing process, the sump depths (maximum depth of the liquid phase k nesses portion LP) d1 and d2 and the thic t1 and t2 of the dified semi-soli layer portion (Mushy Zone) MZ, appearing in the lows cases of the conditions 1 and 2 are as fol from FIGS. 18 and 19 illustrating the prototype TP [ 0075] (Experiment A) (Condition 1 and results) : uminum - Material Al - Additives: Z - Diameter of round ingot (D = 355 mm m in 3O -Drawing speed (casting speed) v1 = 75 mm/ -Sump depth (maximum depth of liquid phase portion LP) (Fig. 21) d1 = 171.5 mm k ness -Thic of semi-solidified layer portion (Mushy Zone) (Fig. 21) t1 = 4 mm

[0076] That is, drawing is performed at low speed under the above condition 1 by the continuous casting device before the improvement. Zinc is added to the liquid phase portion L P1 at a certain moment when the g under the condition 1 is performed. The added zinc instantaneously diffuse into luminum a of the liquid phase portion L P1 to form an alloy and act as a contrast agent. Drawing is performed under the above ion 1 for a predetermined time after the addition. By this A I GS. experiment A, the low speed drawing portion 50 of F 17 and 18 is obtained. The mechanism by which this low speed drawing portion 50 is obtained will be described later. [ 0077] I t can be seen from that the internal state of the d lows. mol 1 in the experiment A under the condition 1 is as fol That is, indicates the case when viewed from a vertical cross section of the top of the product in the mol 1 at a certain moment. I n , the sol phase portion SP1 which has idified been sol y appears on the lower side, and the liquid phase portion L P1 to be sol appears on the upper side. id l Furthermore, a semi—sol phase portion (Mushy Zone) M Z l lustrated appears at the interface between the two phases. As i in , the sump depth (the maximum depth of the liquid k ness phase portion LP1) d1 = 171.5 mm, and the thic t1 of the id Zl semi-sol phase portion (Mushy Zone) M is 4 mm. As can be seen from F I 21, when the drawing speed (casting speed) is low, generation of crac (voids) is not observed in the liquid phase portion L Along with this, finally, as can be seen from ted G. the prototype TP i l in F I 17, the low speed drawing n 50A free of crac is formed. [ 0078] 3O iment B) (Condition 2 and results) - Material: Aluminum - Additives: Z - Diameter of round ingot CD = 355 mm -Drawing speed (casting speed) v2 = 109 mm/min - Sump depth (maximum depth of liquid phase portion LP) (Fig. 22) d2 = 282.2 mm dified k ness - Thic of semi-soli layer portion (Mushy Zone) (Fig. 22) t2 = 5.5 mm [ 0079] Following the drawing under the above condition 1 performed by the continuous casting device before improvement, similarly, drawing is performed at a higher speed than before under the above ion 2 by the continuous casting device before the improvement. As described above, zinc is added to the liquid phase portion LP2 at a n moment when the drawing under the condition 2 is performed. Simil to the luminum above, the added zinc es at high speed into a of the liquid phase portion LP2, forms an alloy, and serves as a contrast agent. By this experiment B, the first high speed drawing portion SOB of FIGS. 17 and 22 is obtained. The mechanism by which the first high speed drawing portion 50B is obtained wil be described later. [ 0080] I n the experiment B under the condition 2, the longitudinal cross section of the top of the mol 1 is as indicated in . I n , the sol phase portion SP2 which has idified been sol already appears on the lower side, and the liquid phase portion LP2 to be sol appears on the upper side.

Furthermore, a semi-sol phase portion (Mushy Zone) MZ2 l lustrated appears at the interface between the two . As i I G. in F 22, the sump depth um depth of the liquid phase k ness portion LP) d2 = 282.2 mm, and the thic t2 of the semi— idified Z2 sol layer portion (Mushy Zone) M = 5.5 mm. As can be seen from , when the drawing speed (casting speed) is high, generation of crac (voids) is observed in the liquid 3O phase portion LP2. Along with this, the first high speed drawing portion 50B including the crack illustrated in is [ 0081] (2)-2 Next, the experiment C for manufacturing the second prototype unit 200 of will be described.

The drawing speed (casting speed) at the time of manufacturing a prototype 200 as a product (casting product) by drawing using the continuous casting device of the present invention of F I 1 is the same high drawing speed (casting speed) as in the manufacturing of the first high speed drawing portion SOB in the first prototype unit 100. As a result, the second high speed drawing portion 60B of can be obtained. [ 0082] The ion 3 (experiment C) at the time of the high lows. speed drawing is as fol Further, the sump depth (maximum depth of the liquid phase portion LP) d3 and the k ness dified thic t3 of the semi—soli layer portion (Mushy Zone) lows. appearing under the condition 3 are as fol [ 0083] (Experiment C) (Condition 3 and results) : uminum - Material Al - Additives: Z - Diameter of round ingot (D = 355 mm m in -Drawing speed (casting speed) v3 = 102 mm/ -Sump depth (maximum depth of liquid phase portion LP) (Fig. 23) d3 = 276.2 mm k ness dified -Thic of oli layer n (Mushy Zone) (Fig. 23) t3 = 4 mm [ 0084] The drawing under the condition 3 is performed by the continuous casting device of the t invention. At an instant when drawing under this condition 3 is performed, zinc is added to the liquid phase portion LP3 as described above.

Similar to the above, the added zinc diffuses at a high speed 3O into aluminum of the liquid phase portion LP to form a certain alloy, and serves as a contrast agent. This experiment C ted I GS. resul in the second high speed drawing portion 60A of F 17 and 20. The mechanism by which this second high speed g n SOB is obtained will be described later.

[0085] The process of the experiment C under the condition 3 is id G. G. ted in F I 23. I n F I 23, the sol phase portion SP3 which has been solidified already appears on the lower side, and idified the liquid phase portion L P3 to be sol appears on the upper side. Furthermore, a semi-sol phase portion (Mushy Zone) M Z3 s at the interface between the two phases. lustrated As i l in , the sump depth (the maximum depth 7 6.2 of the liquid phase portion LP3) d3 is 2 mm, and the k ness dified thic t3 of the semi-soli phase portion (Mushy Zone) M23 is 4 mm. Further, as can be seen from , although the drawing speed (casting speed) is high, tion of crac (voids) is not observed in the liquid phase portion LP3. That is, when the product is manufactured under this condition 3, gh the sump depth is sed compared to the case of k ness the above condition 1 in which no crack occurs, the thic of the semi-sol phase portion (Mushy Zone) M Z3 hardly increased. Since the semi—sol phase portion (Mushy Zone) M23 does not become thick, even if high—speed drawing casting is performed by the device of the present invention, it can be ed that the heat transfer in the material can be erated e accel to improve the productivity whil maintaining the uniformity and refinement of the crystal structure and the lustrated mechanical strength of the product. I n fact, as i l in , it is possible to form the low speed drawing portion A s . 60 without crack [ 0086] As can be seen from the above description, as described in paragraph [ 0046] (9) above, according to the continuous casting device of the present invention, it is about 30% as compared to the continuous g device before ement, 3O and the drawing speed of the product can be increased. [ 0087] Further, the purpose, summary and further experiments of the present ion will be described below.

I n general, metal products of various ingots such as round rods or prisms are obtained through the steps of melting the ra material metal, adjusting its components, and solidifying it into a predetermined shape. At this time, the y of the final product, for e, the mechanical properties, the homogenization of the crystal structure, the refinement, etc., is determined by the state in the sump during idification dified sol (the unsoli liquid portion at the top of the product during continuous casting). [ 0089] idification ten Sol of the mol metal is caused by heat transfer, but the heat conduction in the sol is twice that of the liquid, therefore the mol metal in the container or in the d idifies mol for continuous casting sol from the outer peripheral portion toward the center. I n the case of continuous casting, idification for example, as can be seen from sol proceeds with the liquid and sol ting in the top portion of the product. [ 0090] An important point to improve the quality of the product dified is to reduce, for example, the liquid portion and semi—soli layer portion as much as possible in but because the thermal conductivity of liquid and sol is different, it is significantly difficul to achieve such purpose. [ 0091] Therefore, the present inventor has focused on that the thermal conductivity of liquid is lower than that of solid, and by d ten ng a magnetic fiel and a current to a mol metal and ng, ev if the sump depth ses by increasing the drawing speed (casting speed), no crac occur. [ 0092] 3O Now that, according to the present invention, particularly, the case of improving the g rate to improve the quality, the case where the present invention is applied to continuous g of various ingots (round ingots (round rod-like ingots) or tic ingots) will be described.

[0093] I n the continuous casting process, for example, as can be G. ex seen from F I 1, a downward conv conical pillar (a downward convex parabolic shape in the longitudinal cross section) sump always appears. [ 0094] N ow that heat transfer can be explained by Newton's law of cooling. [ 0095] That is, assuming that the amount of a heat transfer Q, a time t, a surface area S, a high temperature side temperature TH, a low temperature side ature TL, and a temperature coefficient 0, —dQ/dt 2 c1 - S (TH—TL) hol [ 0096] That is, heat transfer is smoothly performed as the temperature gradient proportional to the difference between the high temperature side temperature T and the low temperature side temperature TL is large. [ 0097] gh heat transfer increases by stirring, the difference in temperature difference between the presence and absence of stirring is considered. [ 0098] is a longitudinal sectional view at a certain point in a s of ng mol metal d) into a product (solid) inside a mol in general continuous casting. [ 0099] F I 25 indicates a state of heat of a portion surrounded e id by the elongated circl CIR in . The sol line SL ting the temperature indicates a case of continuous 3O casting without stirring, and the brok line BL indicates a case of stirring according to the present ion. Repeatedly, the sol line SL indicates the temperature distribution when the molten metal is not stirred, and the brok line BL indicates the temperature distribution when the mol metal is stirred.

However, the outer side (right side in the drawing) of a point b described later of the solid line SL indicates a common ature distribution in the two cases with and without stirring. Further, when not stirred, the semi-solidified layer dified l portion M Z s the semi-soli layer portion M Z dified (thickness L1), and when stirred, it becomes the semi-soli ZZ dified layer portion M thinner than the semi-soli layer portion lustrated M Zl (thickness L2 = L 1 - L11). Further, as i l in , as described later, the temperature difference between the dified 21 inside point a of the semi-soli layer portion M and the outside point b is ATn, and the temperature ence between dified the point c on the inner surface of the semi-soli layer T m. portion M22 and the point b on the outer surface is A [ 0100] That is, when stirring is not performed, as can be seen from the sol line SL, the portion of the center line CL indicates the highest temperature TH1, and the temperature gradually decreases toward the outer periphery and decreases to the temperature of the point a on the boundary between the liquid P dified Zl . portion L and the semi—soli layer n M Inside the dified semi—soli layer portion M2, the cooling rate is faster than the liquid n L P and decreases to the temperature of the dified point b on the boundary between the semi-soli layer id id 2 1 portion M and the sol portion SP. I n the sol portion SP, the temperature drops rapidly and reaches the temperature TL I G. in F 25. [ 0101] On the other hand, when ng is performed, the temperature distribution inside the liquid (molten metal) is most en . al m as seen from the brok line BL Therefore, almost no temperature gradient occurs from the center line CL 3O to the inside of the semi-solidified layer portion M22. That is, in this case, the temperature of the center line CL portion is also H 2 H 1. the temperature T lower than the previous temperature T k ness Thus, as described above, the thic L2 of the semi-solidified layer portion MZZ becomes thinner by the thickness T than the thickness T1 by the ng. This temperature TH2 continues to the point c inside the semi-solidified layer portion dified Z2 .

M I n the semi-soli layer portion M22, the temperature drops from the point c to the point b. After this, as in the case of no stirring, the temperature TL is obtained. [ 0102] dified Here, when viewed at the oli layer portion MZ, the thickness is the thickness L 1 without stirring, and the k ness L 2 k ness thic (2 L1-L11) with stirring. That is, the thic is L 1 > L 2. Further, the temperature difference between the inner dified surface and the outer surface of the semi-soli layer portion M Z is the temperature ence A without stirring, and the temperature difference A with stirring. Therefore, when the temperature gradients without stirring and with stirring are Ll L2 compared, ATn/ <ATm/ is obtained. If this is compared with 's law of cooling, it can be seen that the cooling rate is elmingly fast in the case of cooling. [ 0103] I n consideration of the quality of various ingots (round bar, prism, etc.), it is desirabl that the temperature distribution of the liquid portion L P be uniform, and it is desirabl that the g be med at once in a high speed. [ 0104] That is, in the present invention, by forcibly stirring the liquid phase portion L on the top of the t, which s during continuous casting, rather than cooling by natural cooling, the temperature ence between the central part and the peripheral part of the liquid phase portion L P is made as small dified Z as possible, and the semi-soli layer portion M is made to be thin and to be cool As a result, according to the present invention, it is found that productivity can be greatly improved 3O while achieving uniformization and miniaturization of crystals, and ement of mechanical characteristics, that is, improvement of product quality. [ 0105] Furthermore, in order to obtain a cylindrical ingot as a prototype TP for continuous casting, zinc (Zn) is introduced into the sump as a chemical tracer. The solidified version of the lustrated G. prototype is i l in F I 26. I n the drawing, when the above Z is uced, the liquid portion is SP (LP), the semi- idified id sol layer portion is SP (M2), and the sol portion is SP. [ 0106] F rom this prototype TP, the five first test pieces lowed (cylinders) of A to E are hol out from the part of which on is indicated in F I 26. That is, from the prototype TP, lowed five first test pieces A to E are hol out in the ion perpendicular to the paper surface of . Further, as can be seen from F I 27, five measurement points (measurement points M to MP5) are defined for each of the first test pieces A lowed to E, and five more second test pieces are hol out in the direction perpendicular to the paper surface from those measurement points. That is, five second test pieces Al to A5 are obtained from the first test piece A, and five second test pieces Bl to B5 are obtained al from the first test piece B.

Similarly, five second test pieces C1 to C5, D1 to D5 and E 1 to D5 were obtained from the first test pieces C, D and E, respectively. This gave twenty five second test pieces. [ 0107] The directions of the center lines CA, CB,... of the second test pieces Al to A5, Bl to B5,... in the first test pieces A to E in are indicated in . That is, as can be seen from F I 26, the center lines CA, CB,... are oriented k ness as along the thic direction of the portion SP (MZ) which w dified Z. once the oli layer portion M [ 0108] The concentration of zinc as the chemical tracer in the above-described twenty five second test pieces Al to A5, Bl to 3O B5,... is measured, and the concentrations CA1 to CA5, CB1 to CB5, CE1 to CE5 are obtained. Further, the average values a1, a2,... a5 of the concentrations of zinc at the ement points MP1 to MP5 of the first test pieces A to E are determined from the following equations. a1 = (CA1 + CB1 + CCl + CD1 + CEl)/5 a2 = (CA2 + CB2 + CC2 + CD2 + CE2)/5 a5 = (CA5 + CBS + CC5 + CD5 + CE5)/5 That is, the average val a1, a2,... of the P1 P5 concentrations of zinc at the measurement points M to M are obtained from the above equation. [ 0109] The mean val a1, a2,...a5 of the concentration of zinc are plotted in . From , it is found that the 2 k ness dified thic of the semi-soli layer portion M is about 2 mm. [ 0110] Such an experiment is ed to create a plurality of graphs corresponding to F I 28. That is, in the continuous casting, the drawing speed (casting speed) is variously changed, and a plurality of graphs corresponding to F I 28 is obtained from the prototype TP obtained at that time. M of these l lustrated graphs are obtained as i in . That is, when the e ten product is obtained whil stirring the mol metal according to k ness the embodiment of the present invention, the thic of the dified semi-soli layer portion M Z does not increase. That is, according to the device of the embodiment of the present invention, the quality of the product does not orate even if the drawing speed (casting speed) of the product is increased. [ 0111] I n on, an observation end face SUF obtained by MP EP performing C on the end face lowered by D (7 inches) from the end face SUF of the prototype TP cut out as indicated in is observed with an SEM. This observation is performed on the prototype TP obtained by sly changing 3O the drawing speed (casting speed). As a result, it is ed that in the prototype TP obtained by ng the molten metal by the device of the embodiment of the t invention, the crystal structure did not become rough even if the drawing speed (casting speed) is increased.

A I M S

Claims (14)

1. A mol metal stirring device configured to stir, in a continuous casting device that continuously mol products by pouring a mol metal of a conductive metal into a mold, a ten d ten mol metal to be poured into the mol or a mol metal in the mold, the mol metal stirring device, comprising a cylindrical case with open upper side immersed in the mol metal, and a pipe housed in the case, wherein the case has an outer cylinder and an inner cylinder housed in the outer cylinder, a gap for circulating cooling air is formed n the outer cylinder and the inner cylinder, the inner cylinder has a vent hol communicating the inside of the inner cylinder and the gap to form a cooling air passage ing from the inner cylinder to the gap via the vent hole, a magnetic fiel device in which the pipe is inserted is housed inside the inner er, in the device, magnetic lines of force from the magnetic fiel device penetrate the inner cylinder and the outer cylinder to reach the mol metal, or the magnetic lines of force running in the mol metal are strongly magnetized to penetrate the inner cylinder and the outer cylinder to reach the magnetic fiel device, ectrode further, a first el penetrating the inner cylinder and the outer cylinder is provided of which one end is d in the inner cylinder, and the other end is exposed to the outside of the outer cylinder to be in contact with the mol metal, the one end of the first electrode is electrically connected to a lead wire running in the pipe, further a second electrode attached to the outer er ectrode is provided, and the position where the second el is attached to the outer er is set at a position where the current flowing through the mol metal between the second ode and the first electrode crosses the magnetic lines of force to generate a L orentz force that rotationally drives the mol metal about the udinal axis. ten aim

2. The mol metal stirring device according to cl 1, ectrode wherein the first el is attached to the case in a state of penetrating a bottom plate of the inner cylinder and a bottom ectrode plate of the outer cylinder, and the second el is attached to a position higher than the magnetic fiel device on an outer peripheral surface of the outer cylinder. ten aims

3. The mol metal stirring device according to cl 1 or 2, wherein the ic fiel device is magnetized so as to emit or receive magnetic lines of force along lateral lines or along downward lines. ten aims

4. The mol metal ng device ing to cl 1 or 2, wherein the magnetic fiel device is magnetized so as to emit or receive magnetic lines of force along lateral lines and along downward lines. ten aim

5. The mol metal stirring device according to cl 4, wherein, in the magnetic fiel device, a magnet magnetized to emit or receive magnetic lines of force along the lateral lines a magnet magnetized to emit or receive magnetic lines of k ed force along the downward lines are stac ally.

6. The mol metal stirring device ing to any one of claims 1 to 5, wherein the outer cylinder is formed with a conductive material which generates heat by energization.

7. A mol metal stirring device configured to stir, in a continuous casting device that continuously molds products by pouring a mol metal of a conductive metal into a mold, a molten metal to be poured into the mold or a molten metal in the mold, the mol metal stirring device, comprising a rical case with open upper side to be immersed in the molten metal, and a pipe to be housed in the case, wherein a communication gap for communication is formed between the lower end of the pipe and the inner side of the bottom surface of the case, the inside of the pipe and the inside of the case communicate with each other through the communication gap to form a cooling air a ic fiel device in which the pipe is inserted is housed inside the case, in the device, magnetic lines of force from the magnetic fiel device penetrate the case to reach the mol metal, or the magnetic lines of force running in the mol metal are strongly magnetized to penetrate the case to reach the magnetic fiel device, ectrode further, a first el penetrating the case is provided of which one end is exposed to the case, and the other end is exposed to the outside of the case to be in contact with the ten ectrode mol metal, the one end of the first el is ically connected to a lead wire running in the pipe, ectrode further a second el attached to the case is ectrode provided, the position where the second el is attached to the case is set at a position where the current flowing through ten e the mol metal between the second el and the first ectrode el crosses the magnetic lines of force to generate a L orentz force that rotationally drives the mol metal about the longitudinal axis. ten aim

8. The mol metal stirring device, according to cl 7, wherein the first electrode is attached to the case in a state of penetrating a bottom plate of the case, and the second electrode is attached to a position higher than the magnetic fiel device on an outer peripheral e of the case. ten aims

9. The mol metal stirring device according to cl 7 or 8, wherein the magnetic field device is ized so as to emit or receive ic lines of force along lateral lines or along downward lines. ten aims

10. The mol metal stirring device according to cl 7 or 8, wherein the magnetic fiel device is magnetized so as to emit or receive magnetic lines of force along lateral lines and along downward lines. ten aim

11. The mol metal stirring device according to cl 10, wherein, in the magnetic fiel device, a magnet magnetized to emit or receive ic lines of force along the lateral lines a magnet magnetized to emit or receive magnetic lines of k ed force along the downward lines are stac vertically. ten aims

12. The mol metal stirring device according to cl 7 to ludes 11, wherein the case inc an outer cylinder formed with a tive material which generates heat by energization.

13. A continuous casting device system, sing: the ten aims mol metal stirring device according to any one of cl 1 to e ten 12, a crucibl for g mol metal from a melting furnace, d e and a mol attached to a bottom surface of the l in ten ten communication with a mol metal inlet, wherein the mol metal stirring device is incorporated in a state in which a lower end side of the mol metal stirring device is inserted into a ten e. mol metal discharge passage in the crucibl

14. The continuous casting device system according to claim 13, wherein the molten metal stirring device is capable of adjusting an insertion amount of the lower end portion of the ten ten mol metal stirring device into the mol metal rge passage of the crucible with respect to the crucible.