JP4202718B2 - High frequency electromagnetic casting mold for continuous casting of molten metal - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a high-frequency electromagnetic casting mold used for continuous casting of molten metal, and more particularly to a high-frequency electromagnetic casting mold that can be manufactured at low cost.
[0002]
[Prior art]
In continuous casting of molten metal, a method of casting by applying a high-frequency magnetic field to a meniscus portion in a mold for the purpose of improving the properties of the slab surface is known (for example, “Iron and Steel” Vol. 80 (1994 No. 9 pp. 711 to 716) (see Non-Patent Document 1). In this method, in order to make the high-frequency magnetic field easily penetrate into the meniscus portion in the mold, it is necessary to use a metal mold in which a slit is formed in the vertical direction, and an electromagnetic coil is disposed around the mold. Of course, the mold has a cooling structure.
[0003]
FIG. 8 is a cross-sectional view of an essential part illustrating this type of continuous casting apparatus. A plurality of slits 3 are formed in the mold 1 in the vertical direction, and the high-frequency coil 2 is disposed around the mold 1. The cooling structure in the mold wall is not shown. The interval between the adjacent vertical slits 3 should be 140 mm or less in order to keep the attenuation rate of magnetic flux density to 50% or less, while it should be 10 mm or more to form a cooling structure in the mold wall. Is desired. The width of the slit 3 is preferably about 0.2 to 0.5 mm from the viewpoint of slit workability, the effect of suppressing the attenuation of magnetic flux density, and prevention of molten metal leakage (Japanese Patent Laid-Open No. 4-178247) (patent) Reference 1). The length of the slit 3 is preferably at least 1.5 times the length of the coil wound in the vertical direction from the viewpoint of magnetic field permeability. During Naozu, 4 immersion nozzle for molten metal supply, P is mold powder, is M _L is the molten metal, M _S is solidified shell.
[0004]
By the way, as a cooling structure of the high frequency electromagnetic field casting mold as described above, since the mold is divided by a slit, it is necessary to provide a cooling water channel in each segment divided by the slit. JP-A-190509 and JP-A-10-156489 describe a structure in which cooling water passes through each segment (see Patent Documents 2 and 3). Further, Japanese Patent No. 2611559 discloses a cooling water passage that reciprocates in a vertical direction in one segment (see Patent Document 4), and Japanese Patent Application Laid-Open No. 7-204789 discloses. In addition, there is disclosed a structure in which a double pipe line having an inside as a cooling water forward path and an outside as a cooling water return path is provided in one segment (see Patent Document 5).
[0005]
[Non-Patent Document 1]
"Iron and Steel" Vol.80 (1994) No.9 pp.711-716 [Patent Document 1]
JP-A-4-178247 [Patent Document 2]
JP-A-6-190509 [Patent Document 3]
JP-A-10-156489 [Patent Document 4]
Japanese Patent No. 2611559 [Patent Document 5]
Japanese Patent Laid-Open No. 7-204789 [Patent Document 6]
Japanese Patent Laid-Open No. 2000-246397 [0006]
[Problems to be solved by the invention]
In this way, in order to make the mold into a water cooling structure, cooling channels must be formed in individual segments. However, since each segment is small, it takes a lot of labor and cost to form the cooling channel. There is.
[0007]
In addition, in the small cross-section mold for billets that does not apply a high-frequency magnetic field, FIG. 9 [FIG. 9A is a front view of the small cross-section mold for billets, and FIG. ], A copper tube 61 (no slit) having a thickness of about 10 mm is used as a mold (such a tubular mold is generally called a tuber mold), which is not provided with a cooling water channel and is made of copper. A cylindrical jacket 63 is arranged outside the tube 61, and the mold is cooled by passing cooling water between the copper tube 61 and the jacket 63 (cooling water channel 62). In this case, the copper tube 61 is drawn. Can be manufactured by integral molding, and there is an advantage that the manufacturing cost increases. In addition, since it can be integrally molded without any joints, it is highly reliable for the strength and durability of the mold, and it is not necessary to connect and secure a copper plate in combination with an assembled mold, simplifying the mold peripheral equipment. It also has the advantage that it can
[0008]
However, when adopting a method of applying a high-frequency magnetic field, it is indispensable to provide a slit in the mold and divide it into a plurality of segments as described above. By simply forming a slit in the copper tube 61, Cooling water leaks from the slit to the inside of the mold. Therefore, in order to prevent water leakage, after all, a cooling water channel is provided for each segment as in the above-described conventional example, the structure is complicated, and much labor and cost are required for mold production. In addition, a copper tube that is so thick that a cooling structure can be formed inside is difficult to manufacture by drawing itself. Therefore, conventionally, a thick mold is first cut out from a copper lump, It must be manufactured by cutting the cooling water channel into a thick mold, which requires a lot of work and cost. Further, in the case of a curved mold, it is technically impossible to cut a cooling water channel that curves along the mold, so FIG. 10A [for explaining the arrangement of the cooling water channel 65 in the curved mold] As shown in the schematic cross-sectional view], a method is adopted in which a very thick mold 1 is cut out and a cooling water channel 65 is cut into the vertical direction, but this method is also not easy. Compared with the casting mold (FIG. 10B: schematic sectional view for explaining the arrangement of the cooling water channel 65 in the vertical casting mold), the machining operation becomes more difficult.
[0009]
A casting method that provides a low-frequency magnetic field instead of a high-frequency magnetic field has also been proposed. This method also applies a magnetic field to the meniscus portion in the mold as in the case of a high-frequency magnetic field. However, when a low-frequency magnetic field is used, the attenuation of the magnetic field is originally low, so it is necessary to provide many vertical slits in the mold. Therefore, since a small segment is not formed, a fine work for forming the cooling water channel is not necessary. As a casting mold using a low-frequency magnetic field, for example, Japanese Unexamined Patent Publication No. 2000-246397 discloses an assembly mold for a slab (see Patent Document 6). Since the slab mold is relatively large, an assembly mold is used. However, the assembly mold lacks suitability for a casting method using a high-frequency magnetic field for the following reasons.
[0010]
That is, in the assembly mold, each part must be fixed with a bolt or the like. In this case, peripheral equipment for supporting the mold from the outside is required. Since a coil for applying a magnetic field is installed around the mold peripheral equipment, the peripheral equipment is also heated by the influence of the magnetic field applied from the coil. In particular, in the case of a high frequency magnetic field, since the heating power for the metal is large, the peripheral equipment must also be water-cooled, and the whole equipment becomes very complicated and the manufacturing cost increases. For this reason, it is actually impossible to apply an assembly mold to a method of casting by applying a high-frequency magnetic field.
[0011]
The present invention has been made in view of the above points, and for continuous casting, which is a mold with a slit having a cooling water channel in each segment, but can be easily and inexpensively manufactured by using a drawing method. An object is to provide a high-frequency electromagnetic casting mold.
[0012]
[Means for Solving the Problems]
A high frequency electromagnetic field casting mold for continuous casting of molten metal (hereinafter sometimes referred to as a high frequency mold) according to the present invention includes a tubular body constituting an inner surface of the mold, and an outer surface of the mold in contact with the outer peripheral surface of the tubular body. an exterior member constituting the can, which has been assembled, the tubular body and the outer member, a slit penetrating phases corresponding to these, together comprising a plurality of along the casting direction, the said tubular body has a groove extending over one side or both of the boundary portion of the exterior member, have along the casting direction concave grooves to avoid the slit, is formed and over the segments divided by said slit, The gist of the invention is that the concave groove is a cooling water channel.
[0013]
The tubular body and the exterior member have a simple structure. Therefore, as a manufacturing method thereof, the tubular body, the plate-shaped body, and the tubular body, It becomes an exterior member. And by combining these, the said ditch | groove becomes a sealed flow path, and this ditch | groove part can be used as a cooling water channel. In this way, a high-frequency mold having a cooling water channel in each segment can be easily obtained, thus reducing manufacturing costs.
[0014]
The groove is preferably formed along the casting direction while avoiding the slit as described above. The reason for avoiding the slit is that if the groove intersects the slit, the cooling water channel (recess This is because the groove portion) is in an open state, and cooling water leaks into the mold. The reason why the groove is formed along the casting direction is that the inside of the segment finely divided by the slit can be efficiently cooled. As an aspect thereof, one groove is formed linearly along the casting direction. In addition to the groove formed in the shape, two or more grooves may be formed, or a straight groove may be formed by making a U-turn so as to reciprocate in the casting direction. Further, the meandering concave groove may be formed along the casting direction (that is, the meandering line may be formed along the casting direction as a whole).
[0015]
In addition, a groove may be formed so as to bridge between adjacent segments (see, for example, FIG. 4B). In this case, the cooling water circulates (bridges) over the bridged segments. Therefore, it is not necessary to provide a cooling water supply / discharge port for each segment, and the number of supply / discharge ports can be reduced.
[0016]
Further, if the tubular body and the exterior member are simply coupled with a bolt or the like, there is a concern that the cooling water in the recessed groove may leak and leak between the contact surfaces of the tubular body and the exterior member. If packing (for example, an O-ring) is arranged along, it is possible to effectively prevent leakage, which is preferable.
[0017]
Furthermore, when connecting the said tubular body and the said exterior member with a volt | bolt, it is preferable to set it as the structure which fastens a volt | bolt in the location close | similar to the said ditch | groove. By the way, when a high frequency magnetic field is applied to the mold as described above, the temperature of the bolts as well as the metal mold part is increased, but if the bolt is fastened at a position close to the concave groove serving as a cooling water channel, This is because overheating of the bolt can also be prevented.
[0018]
In addition, it is preferable that the high-frequency mold is a billet mold. The reason is that in the case of a large mold such as a slab mold, the tubular body itself is also large and difficult to manufacture by drawing, but the billet mold is originally small, so that the tubular body and the exterior member This is because it is possible to easily manufacture a long material which is the basis of the above by drawing.
[0019]
DETAILED DESCRIPTION OF THE INVENTION
<Embodiment 1>
FIG. 1 is a perspective view showing a high-frequency mold 10 and a high-frequency coil 2 (partially broken) according to Embodiment 1 of the present invention, and FIG. It is a front view, (b) is the sectional view on the AA line shown to (a). This mold is for billets.
[0020]
The high-frequency mold 10 has a structure in which four copper exterior members 12 are assembled with bolts 13 on the outer peripheral surface of a copper tubular body 11 having a square cross section, and the inner wall surface of the tubular body 11 serves as the inner surface of the mold. A plurality of slits 15 are formed in the mold 10 along the casting direction (the slab drawing direction). The slits 15 pass through the tubular body 11 and the exterior member 12 to form a continuous slit. Yes. A high frequency coil 2 is disposed around the mold 10 at the position of the slit 15. A cooling water channel 16 is formed inside each segment 10 a of the mold 10, and a cooling water drain hole 14 is provided in a lower portion of the mold 10.
[0021]
Next, a method for manufacturing the high-frequency mold 10 of Embodiment 1 will be described. FIGS. 3A and 3B are perspective views for explaining a method for manufacturing the tubular body 11 in the mold 10 of the first embodiment, and FIG. 4A is a front view of the tubular body 11. (b) is the BB sectional view taken on the line (a), (c) is the CC sectional view taken on the line (a). FIG. 5 is a perspective view of one exterior member 12.
[0022]
First, a copper tubular product 18 having a square cross section is manufactured by drawing ((a) of FIG. 3). The thickness of the tubular object 18 may be any thickness as long as it can be drawn and can form a concave groove, and may be arbitrarily set according to the strength and material of the mold 10. Next, a plurality of slits 15a are formed in the tubular object 18 at a position corresponding to the place where the high-frequency coil 2 is disposed, and a concave groove 17 serving as a cooling water channel 16 is formed on the outer surface side. ((B) of FIG. 3, FIG. 4). The concave groove 17 is formed so as not to intersect with the slit 15a (in parallel with the slit 15a), and to cross between the slits 15a, with one segment as a forward path and the adjacent segment as a return path ( As shown in FIGS. 4 (a) and 4 (c), the groove 17 advances linearly in the segment and makes a U-turn at the upper portion of the tubular body 11). The tubular body 11 is formed with a bolt mounting portion 13a.
[0023]
On the other hand, a copper plate is manufactured by drawing, and a slit 15b is formed in the same position corresponding to the slit 15a of the tubular body 11, and a cooling water drain hole 14 and a bolt mounting hole 13b are formed. Thus, the exterior member 12 is obtained. The drain hole 14 is provided so as to correspond to one lower end 17 a of the concave groove 17. The other lower end 17 b of the concave groove 17 opened at the lower end of the tubular body 11 is a cooling water supply hole 24.
[0024]
Next, the O-ring 19 is disposed along the concave groove 17, and the exterior member 12 (four sheets) is brought into contact with the four outer circumferential surfaces of the tubular body 11 and fixed with the bolts 13 to complete the mold 10 ( FIG. 1). The mounting position of the bolt 13 is close to the concave groove 17, and the bolt 13 is also cooled by the cooling water passing through the concave groove 17. Further, the O-ring 19 prevents the leakage of the cooling water in the concave groove 17. Moreover, since the slit 15a and the slit 15b are formed in the same position, it becomes a continuous slit 15. In cooling the mold 10, cooling water is supplied from the supply hole 24, and the segment is cooled by using the concave groove 17 as a cooling water passage to cool the segment, and is discharged from the drain hole 14.
[0025]
As described above, in the method for manufacturing the mold 10 according to the first embodiment, an inexpensive drawing process can be adopted, and the process and assembly work up to completion of the mold are simple, so that the high-frequency mold 10 can be obtained at a low cost. . For example, the mold manufacturing cost can be reduced to about 1/5 as compared with a conventional machining process. Further, even if it is a curved mold instead of a vertical mold, it can be easily manufactured. That is, first, a slit is formed in a curved tubular product (corresponding to a curved tubular product 18 shown in FIG. 3A). A curved mold can be obtained simply by forming a concave body on the outer surface side to form a tubular body, and forming a slit in a curved plate-shaped object to form an exterior member, and combining these tubular body and exterior member.
[0026]
<Embodiment 2>
6A is a front view showing an upper portion of the high-frequency mold 20 according to Embodiment 2 of the present invention, and FIG. 6B is a sectional view taken along the line DD shown in FIG.
[0027]
In the first embodiment, the example in which the exterior member 12 to be brought into contact with one surface of the tubular body 11 having a rectangular cross section is configured by one sheet is shown, but in the second embodiment, the outer member 12 is brought into contact with one surface. The exterior member 22 is composed of two sheets. And the division | segmentation location of the two exterior members 22 is made to respond | correspond to the center slit 15 position. That is, among the three slits 15a formed on one surface of the tubular body 11, the adjacent portion 22s between the two exterior members 22 is located at the central slit 15a, and a gap is provided in the adjacent portion 22s. Thus, the central slit 15 is formed. In this way, by forming the adjacent portion 22s of the exterior member 22 at the position of the slit 15, the formation of the central slit 15b in the exterior member 22 can be omitted. In addition, since the size of each exterior member can be reduced, water leakage can be prevented by reducing the deformation amount of the exterior member 22, which is advantageous. Other configurations are the same as those of the first embodiment.
[0028]
Also in the case of the second embodiment, the mold 20 can be manufactured at a low cost by employing the drawing process.
[0029]
< Reference example >
FIG. 7A is a front view showing an upper portion of the tubular body 31 in the high-frequency mold according to the reference example , and FIG. 7B is a cross-sectional view taken along line EE shown in FIG.
[0030]
The first embodiment in groove 17 (cooling canals) is forward of the one segment, it showed that formed within the other segments as a return path, in the present reference example, one as a thin recessed groove 37 of the It is formed so as to reciprocate within the segment. A thin cooling water channel is formed by the thin concave groove 37. Other configurations in the reference example are the same as those in the first embodiment.
[0031]
Even if the concave groove 37 is thin like this, the manufacturing process itself of the tubular body 31 is as simple as that of the first embodiment, that is, it is only necessary to dig a groove on the surface of the tubular product obtained by the drawing process. . Therefore, since the production of the tubular body 31 is easy and the work of the exterior member is also simple, the high-frequency mold can be manufactured at a low cost.
[0032]
As described above, the high-frequency mold according to the present invention has been specifically described with reference to the drawings showing typical examples. However, the present invention is not limited to the illustrated examples, and can be applied to the above-described purpose. The present invention can be carried out with appropriate modifications, all of which are included in the technical scope of the present invention.
[0033]
For example, in the above embodiment, the tubular body and the exterior member are made of copper. However, the present invention is not limited to this, and a material that does not generate Joule heat in a high-frequency magnetic field such as ceramic may be used. In addition, since the thing made from copper has high heat conductivity, it is efficiently cooled with the cooling water in a cooling water channel (concave groove).
[0034]
Moreover, although the thing of the structure which provides a tubular body with a ditch | groove was shown in the said embodiment, a ditch | groove may be formed in an exterior member and this may be used as a cooling water channel, or a ditch | groove is formed in both a tubular body and an exterior member. It may be what you did.
[0035]
<Experiment>
Using the high-frequency molds 10 and 20 shown as Embodiments 1 and 2, 0.12% C steel was continuously cast, and the molds were evaluated. As casting conditions, the casting speed is 1.6 m / min and 2.0 m / min, two magnetic field frequencies are 10 kHz and 20 kHz, and the applied magnetic field strength is 100 gauss, 200 gauss, and 300 gauss. It was.
[0036]
As a result, for any high-frequency molds of Embodiments 1 and 2, no adverse effects due to poor cooling are observed in the obtained slab, and damage to equipment due to overheating of the tubular body or exterior member, No leakage of cooling water was observed. Even a high-frequency mold obtained by such a simple manufacturing method was inferior to a conventional mold.
[0037]
【The invention's effect】
As described above, the high-frequency mold according to the present invention has a structure having a cooling water channel in each segment, but can be easily manufactured by using an inexpensive drawing method, and the manufacturing cost is low.
[Brief description of the drawings]
FIG. 1 is a perspective view showing a high frequency electromagnetic casting mold and a high frequency coil for continuous casting according to Embodiment 1 of the present invention.
2A is a front view showing an upper portion of the high-frequency mold of Embodiment 1, and FIG. 2B is a cross-sectional view taken along line AA shown in FIG.
3 is a perspective view for explaining a method for manufacturing a tubular body in the high-frequency mold of Embodiment 1. FIG.
4A is a front view of the tubular body of the first embodiment, FIG. 4B is a cross-sectional view taken along the line BB shown in FIG. 4A, and FIG. 4C is a cross-sectional view taken along the line CC shown in FIG.
5 is a perspective view of one exterior member in the high-frequency mold of Embodiment 1. FIG.
6A is a front view showing an upper portion of a high-frequency mold 20 according to Embodiment 2 of the present invention, and FIG. 6B is a sectional view taken along the line DD shown in FIG.
FIG. 7A is a front view showing an upper part of a tubular body 31 in a high-frequency mold according to a reference example ;
(B) is the EE sectional view taken on the line shown to (a).
FIG. 8 is a cross-sectional view of an essential part showing a continuous casting apparatus in high frequency electromagnetic field casting.
FIG. 9 is a front view of a small cross-section mold for billets that does not apply a high-frequency magnetic field, and (b) is a cross-sectional view taken along line AA shown in (a).
10A is a schematic cross-sectional view for explaining the arrangement of cooling water channels in the curved mold, and FIG. 10B is a schematic cross-sectional view for explaining the arrangement of cooling water channels in the vertical mold.
[Explanation of symbols]
2 High-frequency coils 10 and 20 High-frequency molds 11 and 31 Tubular bodies 12 and 22 Exterior member 13 Bolts 15, 15a and 15b Slit 16 Cooling water channels 17 and 37 Groove 19

Claims (2)

In high frequency electromagnetic casting mold for continuous casting,
The template is for a tubular body constituting the mold inner surface, and the exterior member constituting the contact has been mold outer surface to the outer peripheral surface of the tubular body, assembled,
The tubular body and the exterior member are provided with a plurality of slits penetrating correspondingly thereto along the casting direction,
Comprising a groove extending over one side or both of the boundary between the tubular body and the exterior member ;
Concave grooves, have along the casting direction to avoid the slit, is formed and over the segments divided by the slits, the molten metal, characterized in that is obtained by the concave grooves and the cooling canals High frequency electromagnetic casting mold for continuous casting.   The high frequency electromagnetic field casting mold for continuous casting of molten metal according to claim 1, wherein the continuous casting mold is a mold for billets.

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