JP5131228B2 - Continuous casting mold - Google Patents

Description

  The present invention relates to a mold for continuous casting of molten metal having an electromagnetic coil, and relates to a mold capable of stably applying electromagnetic force to molten metal and obtaining a high quality slab for a long period of time.

  In the continuous casting of molten metal, in order to achieve stabilization of the molten metal surface, smoothing of the surface of a continuously cast slab, and increase in casting speed, for example, as disclosed in Patent Document 1, molten metal is used. Technology has been developed in which electromagnetic force is applied to the steel for casting. This is because an alternating current is supplied to an electromagnetic coil arranged so as to surround the mold and insulated with a refractory, and the meniscus portion of the molten metal in the mold is bent, and the CC powder is placed between the mold and the molten metal. It is a technique for improving surface properties by encouraging inflow and reducing the contact pressure between the mold and the slab during initial solidification.

  Patent Document 2 discloses a mold for a continuous casting apparatus having an electromagnetic coil, in which a pair of first cooling copper plates are sandwiched between a pair of second cooling copper plates and combined with a first cooling copper plate. The plate and the pair of back plates combined with the second cooling copper plate are electrically insulated via an insulator, and the mating surfaces of the first cooling copper plate and the second cooling copper plate are insulated from the mating surface. Disclosed is a continuous casting mold that is electrically insulated through an object and in which an insulator in the vicinity of the corner portion is installed within 50 mm from the corner portion of the casting surface of the first and second cooling copper plates. Yes.

  In Patent Document 3, in a continuous casting mold of a continuous casting apparatus for molten metal having an electromagnetic coil, a pair of first cooling copper plates are sandwiched between a pair of second cooling copper plates, and the first cooling copper plate and the above-mentioned The mating surface with the second cooling copper plate is electrically insulated from each other through an insulator, and is combined with the first back plate and the second cooling copper plate combined with the pair of first cooling copper plates. The second back plate is electrically insulated and fastened and fixed to each other via an insulator, and at least one of the pair of first back plates and the pair of second back plates A continuous casting mold is disclosed in which the outer peripheral surface of the plate is coated with an electrical insulator.

  Patent Document 4 discloses an electromagnetic coil (in a molten metal continuous casting apparatus in which electromagnetic force is applied in a direction perpendicular to the inner wall of the mold in the vicinity of the meniscus initial solidification portion of the molten metal in the continuous casting mold. And a pair of first back plates on a pair of first cooling copper plates, a pair of second back plates on a pair of first cooling copper plates. The cooling copper plate is combined with a pair of second back plates, and the pair of first cooling copper plates and the first back plate are movably sandwiched between the pair of second cooling copper plates and the second back plate. In the continuous casting mold configured as described above, either (or both) of the pair of first cooling copper plates and the pair of second cooling copper plates are parallel to the casting direction or inclined at 5 degrees or less from the casting direction, A cooling copper plate which is divided into two or more in the width direction, the back plate combined with the cooling copper plate divided into two or more is divided into two or more. Continuous casting molds are disclosed that are non-contacting or electrically insulated from each other.

  Patent Document 5 discloses an electromagnetic coil (in a continuous casting apparatus for molten metal in which electromagnetic force is applied in a direction perpendicular to the inner wall of the mold in the vicinity of the meniscus initial solidification portion of the molten metal in the continuous casting mold. And a pair of first back plates on a pair of first cooling copper plates, a pair of second back plates on a pair of first cooling copper plates. The cooling copper plate is combined with a pair of second back plates, and the pair of first cooling copper plates and the first back plate are movably sandwiched between the pair of second cooling copper plates and the second back plate. In the continuous casting mold configured as described above, at least one of the first and second cooling copper plates is divided into two or more in the plate width direction of the cooling copper plate, and the cooling copper plate is divided. Nickel or an alloy thereof, cobalt or an alloy thereof, chromium or an alloy thereof, iron or an alloy thereof in a range including at least a meniscus of at least a plane parallel to the casting direction among the opposed divided surfaces and the surfaces adjacent to the divided surfaces Between the coating layer provided on the dividing surface of the first cooling copper plate and the coating layer provided on the dividing surface of the second cooling copper plate. An insulator is provided, and the first and second back plates are electrically insulated from the first and second cooling copper plates, and the first back plate and the second back plate Continuous casting molds are disclosed that are non-contact or electrically insulated.

JP 52-32824 A JP 2003-145251 A JP 2003-145252 A International Publication Number WO2004 / 0783380 A1 JP 2007-144513 A

  Since the electromagnetic coil for generating the electromagnetic force is disposed on the outer periphery of the mold, the electromagnetic force acting on the molten metal inside the mold is attenuated by the induced current induced in the conductive mold. This attenuation also depends on the frequency of the alternating current used, and the higher the frequency, the greater the attenuation of the magnetic field at the mold.

  In Patent Document 1, it is described that a stainless steel lining is provided in a range including the meniscus portion of the mold so as to reduce the attenuation of the magnetic field. The attenuation of the magnetic field was inevitable.

  In the molds disclosed in Patent Documents 2 and 3, a slab having a fixed width can be obtained, but a slab having an arbitrary width cannot be produced by moving the short side copper plate to an arbitrary position. .

  In the molds disclosed in Patent Documents 4 and 5, since the short side copper plate is movably sandwiched between the long side copper plate, the short side copper plate is moved to an arbitrary position to produce a slab having an arbitrary width. However, since it has a complicated structure in which a copper plate is divided and an electric insulator is provided on the divided surface, it takes time and cost to manufacture and assemble, and there is a problem in maintainability.

  An object of the present invention is to provide a continuous casting mold for casting by applying a magnetic field generated by an electromagnetic coil to a molten metal, which is relatively easy to manufacture and maintain. It is an object of the present invention to provide a durable mold capable of producing a high quality slab stably for a long time without occurring.

The gist of the present invention is as follows:
(1) A low frequency alternating current of 10 Hz to 500 Hz is applied to the outer peripheral surface of the mold in order to apply an electromagnetic force in a direction perpendicular to the inner wall of the mold at the initial solidified portion of the meniscus of the molten metal in the continuous casting mold. A pair of first cooling copper plates provided with electromagnetic coils and a pair of first cooling copper plates disposed on the short side, and a pair of second cooling copper plates disposed on the long side and a pair of second cooling plates. And the pair of the first cooling copper plate and the first back plate are movably sandwiched between the pair of the second cooling copper plate and the second back plate. In the constructed mold for continuous casting of molten metal, a concave groove extending in the casting direction is formed on a side surface of the first cooling copper plate, which is a butt surface with the second cooling copper plate, and the concave groove is formed. Not the first cooling copper A first electrical insulator is provided on a side surface of the first electrical insulator, and a second electrical insulator projecting from the surface of the first electrical insulator is provided in the groove. A mold for continuous casting of molten metal.
(2) The protruding amount of the second electrical insulator protruding from the surface of the first electrical insulator is 0.1 mm or more and 0.8 mm or less. Mold for continuous casting of molten metal.
(3) The molten metal continuous casting mold according to (1) or (2), wherein the first electrical insulator is ceramic.
(4) The molten metal according to any one of (1) to (3), wherein the second electrical insulator is a polymer material having a normal heat resistant temperature of 100 ° C. or higher. Continuous casting mold.

  According to the present invention, the mold used when continuously casting molten metal by applying electromagnetic force does not have a divided structure of the copper plate, so that it is relatively easy to manufacture, assemble and maintain, and even for long-term use. The stability of the mold can be ensured, and a high quality slab can be obtained without operating trouble over a long period of time.

It is the perspective view which showed typically the casting_mold | template for continuous casting concerning this invention. It is a schematic diagram which shows the state which assembled the 1st cooling copper plate 1 concerning this invention to the 1st backplate 3, (a) is a perspective view, (b) is a horizontal sectional view of the AA line of (a). (C) is the horizontal sectional view of the BB line of (a), (d) is an enlarged view of the C section of (c).

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

  FIG. 1 shows an example of an embodiment of the present invention corresponding to a variable width mold, and the side surface of the first cooling copper plate 1 (short side), that is, the second cooling copper plate 2 (long side). A concave groove extending in the casting direction (downward on the paper surface in FIG. 1) is provided on the butt surface, a first electrical insulator 6 is provided in a portion where the concave groove is not formed, and a second electrical insulator is provided in the concave groove. It is a perspective view which shows the assembly state of the casting mold 21 for continuous casting provided with the insulator 7. FIG.

  The pair of first cooling copper plates 1 is sandwiched between a pair of second cooling copper plates 2 attached to a pair of second back plates 4 provided facing the long side, and the second cooling copper plates The cylinder 15 attached to a pair of back plates 3 provided opposite to the short side can be changed in width during casting. . By making the first back plate 3 attached to the first cooling copper plate 1 and the second back plate 4 attached to the second cooling copper plate 2 non-contact with each other, The second cooling copper plate 2 is assembled so that electrical conduction through the back plates 3 and 4 does not occur. An electromagnetic coil 16 for applying an electromagnetic force to the molten metal in a direction perpendicular to the inner wall of the mold is provided on the outer periphery of the mold 21 in the vicinity of the meniscus portion of the molten metal in the mold 21. The electromagnetic coil 16 is energized with a low frequency alternating current of 10 Hz to 500 Hz.

  2A and 2B are schematic views showing a state in which the first cooling copper plate 1 is assembled to the first back plate 3, wherein FIG. 2A is a perspective view, and FIG. 2B is a horizontal view seen from the line AA in FIG. Sectional drawing, (c) is a horizontal sectional view as seen from line BB in (a), and (d) is an enlarged view of a C portion of (c), that is, a concave groove portion. As shown in the figure, the first cooling copper plate 1 and the first back plate 3 are in contact with each other through an electrical insulator 8. Further, a sulfide-resistant coating 14 is applied to the front side of the first cooling copper plate 1 (the side in contact with the molten metal).

  As shown in FIG. 2 (d), a concave groove 5 extending in the casting direction (downward on the paper in FIG. 2 (a)) is formed on the side surface of the first cooling copper plate 1, and the concave groove 5 is formed. A first electrical insulator 6 is provided in the unexposed portion, and a second electrical insulator 7 is provided in the groove 5.

  Generally, the thickness of the copper plate used for the short side copper plate of the continuous casting mold corresponding to the variable width is 40 to 60 mm. In the present invention, a concave groove 5 is formed on the side surface of the first cooling copper plate 1, and a first electrical insulator 6 is provided in a portion where the concave groove 5 is not formed. If the area where the first electrical insulator 6 is provided becomes too small, even if a slight mechanical force or thermal stress is applied in the vicinity of the side edge of the first cooling copper plate 1, it will be deformed. The possibility that the first electrical insulator 6 provided in the part is damaged or peeled off increases. Therefore, it is desirable that the portion where the first electrical insulator 6 is provided has a width of 5 mm or more from the side edge.

  About the width | variety of the ditch | groove 5 formed in the side surface of the 1st cooling copper plate 1, if it is the range except 5 mm from the edge part by the side of an operation surface, and 5 mm from the edge part by the side of a backplate, it can set arbitrarily. Since the second electrical insulator 7 embedded in the concave groove 5 becomes a contact surface with the second cooling copper plate 2, the width of this contact surface, that is, the area of the second electrical insulator 7 is small. If it is too large, the load must be handled in a small area, so that wear due to wear is accelerated. Therefore, the width of the groove 5 is preferably 20 mm or more.

  The groove 5 formed on the side surface of the first cooling copper plate 1 has a structure penetrating in the height direction (vertical direction) of the first cooling copper plate 1, so that the second electrical insulation is performed during use of the mold. Since the object 7 may fall off in the height direction of the mold, it is desirable that the upper end and the lower end are closed. Although there is also a method of forming the groove 5 while leaving the upper end and the lower end of the side surface of the first cooling copper plate 1, for example, after processing the groove 5 so as to penetrate up and down in advance, FIG. 2 (a) As shown in (b), the vertical movement of the second electrical insulator 7 can be suppressed by installing the pressing plates 9 at the upper and lower ends of the groove 5.

  About the depth of the ditch | groove 5, 2 mm or more and 5 mm or less are desirable. If it is shallower than 2 mm, the second electrical insulator 7 embedded in the concave groove 5 may come off during use, and if it is deeper than 5 mm, the volume of the second electrical insulator 7 increases. This is because it is not economically preferable.

  The cross-sectional shape of the groove 5 is preferably a so-called trapezoidal shape in which the width on the inner side of the first cooling copper plate 1 is wider than the width on the front surface side. When the cross-sectional shape of the concave groove 5 is a rectangle, or the width on the surface side is wider than the width on the inner side (the reverse shape of the trapezoid), the second electrical insulator 7 is filled. This is because the work becomes easy, but the second electrical insulator 7 may come off the concave groove 5 when an unexpected force is applied.

  As the second electrical insulator 7 filling the concave groove 5, it is desirable to use a polymer material having a normal heat resistant temperature of 100 ° C. or higher. As an electrical insulator, ceramic materials are superior in heat resistance, strength, etc., but ceramic materials are generally hard, and when the width of the short-side copper plate is varied, there is a possibility of scratching the surface of the long-side copper plate. Therefore, it is not preferable. The polymer material having a heat-resistant temperature of 100 ° C. or higher is used because the short-side copper plate is water-cooled, but the temperature rises due to the heat received from the molten steel during casting, and the concave that fills the second electrical insulator 7 This is because the temperature is about 100 ° C. in the groove 5 portion. If the normal heat-resistant temperature of the second electrical insulator 7 is lower than 100 ° C, it may be softened or deteriorated during casting, and it will wear rapidly due to sliding with the long side when changing the width of the short side. Progresses and lacks durability.

  As the second electrical insulator 7, a polymer material having a normal heat resistant temperature of 100 ° C. or higher, for example, a fluororesin, polyimide, polyamide, polypropylene, polycarbonate, ABS resin, melamine resin, epoxy resin, or the like can be used. . Among these, fluororesins such as polytetrafluoroethylene (PTFE), polyvinyl fluoride (PVF), perfluoroalkoxy fluororesin (PFA) and tetrafluoroethylene / hexafluoropropylene copolymer (FEP) are electrically insulated. It is particularly suitable because it is excellent not only in properties but also in lubricity.

  Projection amount H of the second electrical insulator 7 filling the concave groove 5 formed on the side surface of the first cooling copper plate 1 from the surface on which the first electrical insulator 6 is formed (FIG. 2D )) Is preferably from 0.1 mm to 0.8 mm. If the protrusion H is smaller than 0.1 mm, the possibility of the first electrical insulator 6 coming into contact with the second cooling copper plate 2 increases when the width is changed, and wrinkles are generated on the operating surface of the cooling copper plate 2. Or the possibility of chipping in the first electrical insulator 6 increases. Further, the second electrical insulator 7 is worn gradually by sliding by changing the width of the mold. Therefore, if the protrusion H is smaller than 0.1 mm, the durability of the mold is deteriorated. On the other hand, when the protrusion amount H is larger than 0.8 mm, the molten steel can be easily inserted into the gap, and the possibility of operation troubles such as breakout increases.

  In addition, in the structure of the 1st electrical insulator 6 provided in the part in which the concave groove 5 of the 1st cooling copper plate 1 side surface is not formed, the coating material and coating method of the cooling copper plate 1 for improving sulfur resistance As for the material and application method of the durable electrical insulator, those shown in Patent Document 5 may be used as they are.

  In the mold of the present invention, the cooling copper plates 1 and 2 can be cooled by forming slits in the cooling copper plates 1 and 2 and providing water channels between the cooling copper plates 1 and 2 and the back plates 3 and 4. A well-known method may be employed such as providing a cooling water channel by opening a through hole in the cooling copper plates 1 and 2.

  Further, for the intermediate portion and the lower end portion in the height direction of the working surface of the cooling copper plates 1 and 2, commonly used nickel plating, cobalt-nickel plating, self-fluxing, in order to improve corrosion resistance and wear resistance. Needless to say, it is better to apply alloy spraying.

  In a mold having dimensions such that the width of the second cooling copper plate 2 (long side) is 2000 mm, the width of the first cooling copper plate 1 (short side) is 250 mm, the height is 900 mm, and the thickness is 50 mm, the first cooling copper plate 1 Cross-sectional shape with 5 mm from the end on the working surface side and 5 mm from the end on the back plate side, 41 mm on the inner side, 40 mm on the front side, and 2 mm in depth on both sides Is a trapezoidal concave groove 5 penetrating in the vertical direction. Nickel plating with a thickness of 0.05 mm is provided on the side surface of the first cooling copper plate 1 excluding the concave groove 5 and the surface on the back plate side, and the working surface is 0.00 mm from the upper end to 300 mm in the height direction. A chrome plating having a thickness of 05 mm was provided, and 1 mm of a nickel-based self-fluxing alloy spray was provided from the height of 300 mm to the lower end. On the side surface of the first cooling copper plate 1, the nickel-base alloy “HASTELLOY C-276” (“HASTELLOY” is a registered trademark) having a thickness of 0.05 mm is formed on the entire length in the height direction excluding the groove 5 by high-speed flame spraying. In addition, a 0.15 mm thick zirconia ceramic is applied in the height direction from the upper end to 600 mm in the height direction, and the thickness is applied in the range from the upper end to 600 mm to the lower end by plasma spraying. A 0.15 mm yttria ceramic sprayed layer was formed, and a first electrical insulator 6 was provided.

  Fluororesin that has a cross-sectional shape that fits into the groove 5 provided on the side surface of the first cooling copper plate 1, has a length of 840 mm, and is processed so that various thicknesses protrude from the surface of the groove 5 The “Teflon” (registered trademark) plate was fitted into the groove 5 as the second electrical insulator 7. Protrusions were 0.09 mm, 0.1 mm, 0.2 mm, 0.5 mm, 0.8 mm, and 0.9 mm, and molds of the respective protrusions were assembled and cast. At this time, 30 mm from each of the upper end and the lower end was screwed to the contact plate 9 for preventing the displacement of the second electrical insulator 7 using a bolt 10. Further, the back plate 3 combined with the first cooling copper plate 1 is formed on the surface in contact with the first cooling copper plate 1 by a high-speed flame spraying method with a nickel-based alloy “Hastelloy C-276” (“ In “Hastelloy”, a base sprayed layer of registered trademark) was formed, and a zirconia ceramic having a thickness of 0.15 mm was formed by plasma spraying to provide an electrically insulating layer 7. As shown in FIGS. 2B and 2C, the cooling copper plate and the back plate are assembled using the insulating washer 11, the insulating sleeve 12, and the fastening bolt 13 so that there is no electrical conduction between them. Then, it was incorporated into a continuous casting mold and cast.

  The purpose of this mold was to investigate the change in insulation resistance between the long-side copper plate and the short-side copper plate with the increase in the number of castings and the durability of the second electrical insulator 6. Is cast without installation, and the insulation resistance between the second cooling copper plate 2 and the first cooling copper plate 1 is measured using a mega tester, and the second cooling copper plate 2 and the first cooling copper plate 1 The gap between the butted portions was appropriately measured with a skimming gauge.

  With a continuous casting machine that casts 350 tonnes of molten steel per charge in one strand, slabs of various widths from 960 mm to 1760 mm are manufactured, and casting is performed until the periodic mold replacement cycle (total 400 to 450 charges). went. During this time, the number of times the width of the mold was variable was 200 to 250 times.

  Table 1 shows the gap between the butted portions of the second cooling copper plate 2 before use and the first cooling copper plate 1 before use, and the first before use, for each mold having different protrusion amounts of the second electrical insulator 7. Insulation resistance between the cooling copper plate 1 and the second cooling copper plate 2, the number of times of use, the number of variable widths, the gap between the butted portions of the second cooling copper plate 2 and the first cooling copper plate 1 after use, after use The insulation resistance between the 1st cooling copper plate 1 and the 2nd cooling copper plate 2 is shown.

  As shown in Table 1, in the mold a in which the protruding amount H of the second electrical insulator 7 is smaller than 0.1 mm, the gap cannot be maintained until the periodic replacement period of the mold, and the first cooling copper plate 1 has a side surface. Due to the first electrical insulator 6 provided, wrinkles were generated on the surface of the second cooling copper plate 2 (long side). Further, in the mold f in which the protrusion amount H of the second electrical insulator 7 is larger than 0.8 mm, breakout due to hot water pouring into the gap occurred. On the other hand, in the molds b, c, d, and e in which the projecting amount H of the second electrical insulator 7 is in the range of 0.1 to 0.8 mm, the insulation durability of the mold is improved without any trouble such as breakout. I found that it can be maintained.

  The present invention can be applied to a mold for continuous casting of molten metal having an electromagnetic coil.

DESCRIPTION OF SYMBOLS 1 1st cooling copper plate 2 2nd cooling copper plate 3 1st back plate 4 2nd back plate 5 The ditch | groove 6 provided in the 1st cooling copper plate side surface 1st electrical insulator 7 2nd electrical insulation Object 8 (provided between the cooling copper plate and the back plate) Electrical insulator 9 Holding plate 10 Bolt 11 Insulating washer 12 Insulating sleeve 13 Fastening bolt 14 Sulfur-resistant coating 15 Cylinder 16 Electromagnetic coil

Claims (4)

In order to apply an electromagnetic force in a direction perpendicular to the inner wall of the mold at the initial solidification portion of the meniscus of the molten metal in the continuous casting mold, an electromagnetic coil for applying a low frequency alternating current of 10 Hz to 500 Hz on the outer peripheral surface of the mold is provided. A pair of first cooling copper plates disposed on the short side and a pair of first back plates, and a pair of second cooling copper plates disposed on the long side and a pair of second back plates Are combined, and the pair of the first cooling copper plate and the first back plate are sandwiched between the pair of the second cooling copper plate and the second back plate. In the mold for continuous casting of molten metal,
A concave groove extending in the casting direction is formed on a side surface of the first cooling copper plate that is a butt surface with the second cooling copper plate, and a side surface portion of the first cooling copper plate that is not formed with the concave groove. A molten metal, characterized in that a first electrical insulator is provided, and a second electrical insulator projecting from the surface of the first electrical insulator is provided in the groove. Mold for continuous casting.   2. The molten metal according to claim 1, wherein a protruding amount of the second electrical insulator protruding from a surface of the first electrical insulator is 0.1 mm or more and 0.8 mm or less. Continuous casting mold.   The mold for continuous casting of molten metal according to claim 1 or 2, wherein the first electrical insulator is ceramic.   4. The molten metal continuous casting mold according to claim 1, wherein the second electrical insulator is a polymer material having a normal heat resistant temperature of 100 ° C. or more. 5.

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