JPH0724919B2 - Metal tube continuous casting method and apparatus - Google Patents

Abstract

Dense, homogeneous tubular metal products (33) such as pipe is cast in long lengths continuously by introducing liquid metal (32) into the lower portion of an annular-shaped casting vessel (11). The liquid metal (32) is withdrawn in the presence of at least one elongated upwardly travelling alternating electromagnetic levitation field and a second inner electromagnetic containment field for maintaining the tubular liquid metal column (26) in a substantially weightless and pressureless condition while solidifying. The resulting solidified tubular metal product (33) is withdrawn from the upper portion of the field, cooled and further processed to result in a desired end product.

Description

Description: FIELD OF THE INVENTION The present invention relates to a new and improved method and apparatus for the continuous production of tubular metal products (eg pipes) and the products obtained thereby.

More specifically, the present invention is directed to gravity and friction acting on the molten tubular metal product while maintaining the highest degree of effective heat transfer between the heat exchanger and the tubular molten metal column that forms the tubular metal product upon solidification. It relates to the continuous production of long tubular metal products (for example pipes) by casting in the presence of levitation fields to minimize forces and adhesions.

Prior art Tubular metal products such as pipes have been manufactured by various methods including casting,
They are described in detail in the literature relevant to the art. For example, US Pat. No. 427447 dated June 23, 1981.
In the description of the prior art found in columns 1 and 2 of the '0 specification, a number of prior patents and technical articles describing electromagnetic casting equipment suitable for the production of tubular metal products such as pipes are listed, and The drawbacks of these known prior art methods have been devised. Examples of such prior patents are Getselev et al. U.S. Pat. No. 3,467,166, Getselev U.S. Pat. No. 3605865, Carlson (K.
arlson U.S. Pat. No. 3,735,799, Getselev
v) U.S. Pat. No. 4,014,379 and Getzelev (Getsele
v) U.S. Pat. No. 4,126,175, the use of electromagnetic molds being described in these patent specifications. Such electromagnetic molds serve to confine the downwardly moving molten metal pool within defined dimensions and to solidify therein the laterally-extending outer portion of the pool. At this size, the solidification of the solidified metal occurs along the longitudinal direction, so that the molten metal is fed by gravity flow semi-continuously or continuously to the upper end of the descending pool forming the solidified ingot. One of the major drawbacks of this method is
The lack of the "failsafe" properties of previously known ascending casting techniques. Therefore, in the event of an unexpected power system failure, the molten metal may not simply flow back as seen in the ascending casting system, but may spill out of the downward moving molten metal pool. is there. Moreover, in these known descending casting techniques, it is necessary to constantly and closely control both the molten metal feed rate and the solidified ingot withdrawal rate, as molten metal can overflow and escape. These rates are significantly limited by heat exchange problems, which reduces the commercial utility of this continuous casting process.

All of them are from Outokump
o Loyskiski et al U.S. Pat. No. 3,746,077 and Lohikoski U.S. Pat. No. 3,872,913, which were assigned to Oy An ascending casting technique is described in which a fresh molten metal is pushed up by water pressure or sucked up by vacuum. According to this method
The cooled cast product is intermittently released from physical contact with the upper end of a mechanical mold into which molten metal is continuously introduced. While such systems achieve the desirable "failsafe" properties of ascending casting techniques, significant wear of the outer contact mold is unavoidable.
In fact, during continuous or semi-continuous operation of such systems, the molds wear out in an unacceptably short time. Therefore, there is a current need for an improved continuous casting system for tubular metal products that overcomes the deficiencies of previously known electromagnetic casting systems.

SUMMARY OF THE INVENTION Accordingly, the main object of the present invention is to produce a long tubular metal product (for example, a pipe) which overcomes the drawbacks and drawbacks of the tubular metal product continuous casting technology and system currently known and in use as described above. SUMMARY OF THE INVENTION It is an object of the present invention to provide a new and improved continuous casting method and apparatus.

According to one of the features of the present invention, the minimum of gravity, friction and adhesion acting on the tubular metal product while maintaining the highest degree of effective heat transfer between the tubular metal product and the heat exchanger during solidification. An improved continuous manufacturing method and apparatus for long tubular metal products (e.g., pipes) is provided by casting in the presence of an upwardly traveling levitating electromagnetic field.

In carrying out the method of the present invention for producing a long tubular metal product, an upward alternating elongated levitation electromagnetic field is generated inside the annular casting container, and an upwardly directed levitation electromagnetic field is generated. An apparatus is provided that includes means for generating a first containment field component that extends at a right angle and extends over the same extent. Such a device is also for generating a second containment field component for producing at least a second containment field component which acts in the central portion of the annular casting container in the opposite direction to the first containment field component. The second electromagnetic field generating means is also included. A tubular molten metal column is formed by introducing molten metal into the annular casting vessel and below the electromagnetic field. The value of the levitation electromagnetic field acting on the tubular molten metal column is determined by suitable means while maintaining a predetermined dimensional relationship between the inner and outer surfaces of the tubular molten metal column and the opposing surrounding surface of the annular casting container. It is set to reduce the hydrostatic head of the column to a minimum. The electromagnetic field acting on the tubular molten metal column is also substantially such that the cross-sectional dimensions of the tubular molten metal column provide pressureless contact between the inner and outer surfaces of the tubular molten metal column and the opposing surrounding surface of the annular casting vessel. The size of such a gap is such that it does not form, thereby achieving pressureless contact and maximum heat transfer between the tubular molten metal column and the annular casting vessel while at the same time reducing gravity, friction and adhesion. It is kept to a minimum. In this way, the tubular molten metal column ascends in the annular casting container while being levitated and solidified in the solidification zone surrounded by the heat exchanger, and the solidified tubular metal product is taken out from the upper part of the annular casting container. It

During the operation of the continuous casting system, the molten metal is continuously introduced into the lower part of the annular casting container, and the solidified tubular metal product is continuously taken out from the upper part of the annular casting container. The production rate of the tubular metal product in that case is determined by controlling the rate of withdrawing the solidified tubular metal product from the upper part of the annular casting container and the corresponding introduction of the molten metal into the lower part of the annular casting container. It

According to a preferred embodiment of the present invention, the second levitation electromagnetic field generating means is arranged in the central opening of the annular casting container and generates the levitation electromagnetic field that travels upward. Composed.

At the start of the operation of the method of the present invention, the starting metal tube is joined to the tubular molten metal column rising in the levitation electromagnetic field. For that purpose, in the solidification region, the upper end of the tubular molten metal column in the electromagnetic field may be cooled and solidified while being in contact with the lower end of the starting metal pipe. It is also equipped with means for removing the starting metal tube and the solidified tubular metal product adhering thereto at a rate which determines the production rate of the tubular metal product.
The withdrawn tubular metal product is precooled immediately after it is detached from the upper portion of the tubular casting container, and if necessary, rolled into a desired finished state, and then cooled to room temperature. Alternatively, if initially cast to the desired size, the tubular metal product is pre-cooled immediately after it is removed from the top of the annular casting vessel, then cooled to ambient temperature and stored.

Many of the above as well as other objectives, features, and their attendant advantages of the present invention will become readily apparent upon reading the following detailed description with reference to the accompanying drawings. In the drawings, like parts are designated by like reference numerals.

BEST MODE FOR CARRYING OUT THE INVENTION General Electric Company
Hugh R. Raleigh and Robert T. Frost (November 8, 1983) entitled "Continuous Metal Casting Process, Equipment and Products" assigned to the Tric Company).
R. Lowry & Robert T. Frost) in U.S. Pat. No. 4,414,285 describes the formation of a long, dense, homogeneous material by introducing molten metal into the bottom of a casting vessel in the presence of an upwardly elongating alternating levitation electromagnetic field. A novel continuous metal casting method, apparatus and product for casting various hollow metal rods is disclosed. The present invention is an improvement on U.S. Pat. No. 4,414,285 which discloses a method and apparatus for extending the principles described therein to produce tubular metal products such as pipes.

FIG. 1 is a schematic functional diagram of an improved apparatus suitable for continuously producing long tubular metal products in accordance with the present invention using the principles described in US Pat. No. 4,414,285. The apparatus shown in FIG. 1 includes an annular molten metal reservoir 10 into which molten metal from which pipes or other tubular metal products are made is supplied. Needless to say, a suitable refractory liner heat insulating material and a heating element for maintaining the molten metal contained therein in a molten state are provided in the molten metal reservoir 10. At the upper end of the molten metal sump 10 is arranged a tubular casting vessel and heat exchanger 11, the annular internal passage of which is aligned and in communication with a correspondingly shaped opening in the upper part of the molten metal sump 10. .

The annular casting container / heat exchanger 11 includes a cylindrical outer ceramic liner 12 projectingly supported in an annular passage provided in an upper portion of the molten metal reservoir 10. Further, an inner ceramic liner 13 is arranged above the central opening 14 formed in the central portion of the annular molten metal reservoir 10 in an inverted cup shape. The side wall of the inner ceramic liner 13
Together with the outer ceramic liner 12, an elongated annular casting vessel is defined for solidifying the molten metal in the molten metal reservoir 10 into the desired annular metal product.

An annular external heat exchanger 15 is arranged around the outer ceramic liner 12 in a region immediately above the molten metal reservoir 10. Such an external heat exchanger 15 is described in US Pat.
It may be constructed and operated similarly to the heat exchanger described in connection with FIG. Note that the disclosure contents of the above patent specifications are incorporated herein by reference. In the external heat exchanger 15, the arrow
While cooling water is supplied from the inlet indicated by 16,
Hot water is discharged from the outlet indicated by arrow 17. Further, in order to remove heat from the inverted cup-shaped inner ceramic liner 13, an annular internal heat exchanger 18 is physically arranged adjacent to the inner surface of the inner ceramic liner 13. The internal heat exchanger 18 includes an upper header portion 18A that contacts the bottom surface of the inverted cup-shaped inner ceramic liner 13 and supplies cooling water to a downwardly extending lateral portion 18B. The downwardly extending lateral portion 18B contacts the downwardly extending lateral portion of the inverted cup-shaped inner ceramic liner 13 which defines an annular casting vessel for forming a tubular metal product with the cylindrical outer ceramic liner 12. Then remove the heat. Cooling water is supplied to the header portion 18A through a central inlet pipe 18C, as shown by arrows 19 and 21, and then branches and passes through a downwardly extending side portion 18B of the internal heat exchanger 18.
The entire structure is physically supported within the central opening 14 of the annular molten metal reservoir 10 by a suitable physical support (not shown). Thus, the cooling water is supplied to the internal heat exchanger 18 through the central inlet pipe 18C as indicated by arrow 19 and circulates through the header portion 18A and the downwardly extending side portion 18B, then indicated by arrow 21. It will be recognized that the gas is discharged from the discharge pipe 18D.

The outer periphery of the external heat exchanger 15 is surrounded by the external multiplex winding 22 as shown in FIG. Such outer multiple windings 22 are, for example, vertically stacked around the outer ceramic liner 12 while the plane defined by the windings is substantially perpendicular to the central axis of the outer ceramic liner 12. It can consist of individual coils. As described in more detail in the aforementioned U.S. Pat. No. 4,414,285, particularly with respect to FIG. 3 thereof, each coil of the external multiplex winding 22 is a set of three multi-phase power supplies (second (Figure)
Are connected to each other in sequence, thereby generating an upward levitation electromagnetic field.

In a substantially similar manner, an internal multiplex winding 23 is provided which comprises a plurality of coils located in a plane perpendicular to the central axis of the inverted cup-shaped inner ceramic liner 13. Each coil of the internal multiplex winding 23 is wound circumferentially along the inner surface of the side portion 18B of the inverted cup-shaped internal heat exchanger 18. A power supply current is supplied to the internal multiplex winding 23 through a conductor 24. It is preferable to excite the internal multiplex winding 23 with a multiphase power source to generate a second upwardly traveling electromagnetic field. However, as will be described in more detail later, such an internal multiplex winding is referred to as a single-phase winding. It is also possible to configure. However, in accordance with the preferred embodiment of the present invention, the internal multiplex winding 23 is connected as a polyphase winding and the conductor 24
A multiphase current is supplied via the. As a result, an upward levitation electromagnetic field that is substantially in phase with the upward levitation electromagnetic field generated by the external multiplex winding 22 is generated. Such a levitation field also has a containment field component which extends in a direction perpendicular to the upwardly traveling levitation field and which acts in the opposite direction to the containment field component produced by the external multiplex winding 22. .

FIG. 2 shows that the external multiplex winding 22 is connected to the multiphase power supply / controller 25. The multi-phase power supply / controller 25 can also be independently subjected to frequency control by a known frequency controller 26 and output level control by a known output controller 27. Similarly, the internal multiplex winding of FIG.
Reference numeral 23 is connected to an internal coil power supply / controller 28 via a lead wire 24. The internal coil power supply and controller 28 also comprises an independent frequency controller 29 and an independent output controller 31 for controlling the frequency and intensity (output) of the current thereby supplied to the internal multiplex winding 23. ing. As described above, the inner multiplex winding 23 may be composed of the same multiphase winding as the outer multiplex winding 22. In that case, the current supplied from the internal coil power supply / controller 28 via the lead wire 24 is a multi-phase power supply capable of generating an upward levitation electromagnetic field. Such levitation field is preferably substantially in phase with the upward traveling levitation field generated by the outer multiplex winding 22. Such a levitation field also has a confining field component that extends in a direction substantially perpendicular to the upward traveling levitation field and acts in a direction opposite to the confinement field component generated by the external multiplex winding 22. is doing.

During operation, the molten metal prepared in the furnace (not shown) is supplied to the molten metal reservoir 10 through the feed pipe 10A.
The molten metal then rises from the molten metal reservoir 10 and enters the lower portion of the annular casting vessel defined by the inner surface of the outer ceramic liner 12 and the opposing outer surface of the inverted cup-shaped inner ceramic liner 13. In that case, the ceramic liner may be subjected to gravity flow or pressurization of an inert gas coating
A molten metal column 32 rising in an annular casting vessel defined between 12 and 13 is arranged to reach the liquid level just above the lower ends of the outer and inner multiplex windings 22, 23. During continuous operation, in order to maintain such an initial liquid level of the molten metal in the annular casting vessels 12, 13, the holding furnace intermittently or continuously sends the molten metal to the molten metal reservoir 10. To enter. The molten metal at the above-mentioned initial liquid level will be subject to the upward traveling levitation field generated by the outer multiplex winding 22 and the electromagnetic field generated by the inner multiplex winding 23. This means that even when the electromagnetic field generated by the internal multiplex winding 23 is a confining electromagnetic field acting only in the horizontal direction,
Alternatively, it is also the case if the levitation field is an upwardly traveling levitation field having a confinement field component acting in the opposite direction to the confinement field component of the levitation field generated by the external multiplex winding 22.

At the start of operation, a lifting hoisting tubular member (not shown) is introduced from the upper end of the annular casting containers 12 and 13, and the lower end of the tubular melting member is formed by the molten metal rising in the annular casting containers 12 and 13. It is brought into contact with the upper end of the metal column.
When the cooling water is caused to flow through the respective heat exchangers 15 and 18 at full speed, the upper portion of the tubular molten metal column indicated by 26 is solidified while contacting the starting lifting tubular member. Then, by a suitable take-out roll as shown in FIG. 2, the starting hoisting tubular member and the tubular metal column 26 attached thereto are taken out upward from the annular casting containers 12, 13. The withdrawal rate of the starting hoisting tubular member and the tubular metal column 26 attached thereto is determined by the solid metal column formation rate, and the withdrawal rate determines the production rate of the continuous casting system. Upon solidification within the solidification zone, which is essentially defined by the lengths of the multiple windings 22 and 23, the metal in the molten and solidified states, as described in more detail in the aforementioned U.S. Pat. The column is maintained in a substantially weightless to pressureless state by the upward levitation electromagnetic field.

In operation, the tubular molten metal column in the solidification zone which is subjected to the above-mentioned levitation action exhibits a unique and unexpected self-regulating characteristic. Due to this self-regulating property, the levitation force is greater than the gravity exerted on the tubular molten metal column, so that when the tubular molten metal column is accelerated upward, a decrease in its cross-sectional area occurs. In that case, the levitation force is automatically reduced as a result of the reduced cross-sectional area of the tubular molten metal column, which is caused by the large levitation force. As a result, the rise of the tubular molten metal column is automatically slowed down so that the system stabilizes and exhibits a self-regulating characteristic. The same is true for the opposite case. That is, when the tubular molten metal column is decelerated due to the reduced levitation force, an increase in its cross-sectional area occurs. As a result, the levitation force acting on the tubular molten metal column is increased, which accelerates the rise of the tubular molten metal column. Thus, the levitation zone (ie, the area where the upward levitation electromagnetic field acts on the molten or solidified tubular metal column)
In the inside of the system, if the tubular molten metal column that solidifies in the solidification zone is floated and supported in a substantially weightless and pressureless state as described above, the system exhibits essentially self-regulating characteristics. I understand.

Most of the molten and solidified tubular metal columns in the solidification zone in the length direction are completely affected by the levitation electromagnetic field, but the average levitation force is about 1/2 of that in the central area of the solidification zone.
The tubular metal columns at the lower and upper ends of the solidification zone are exerted via pressure heads added to raise the molten metal to the initial liquid level and the starting lifting tubular member. Each is supported by lift. As a result, immediately after the formation of the tubular molten metal column, only a small upward accelerating force is exerted by the levitation force in the lower end region, but when the tubular molten metal column rises and reaches the central portion of the levitation region, the tubular molten metal A magnetic field of sufficient strength will be encountered to maintain the metal column in essentially weightless and to bring it into contact with the sidewalls 12 and 13 of the annular casting substantially pressureless. By "pressureless" herein is meant that there is substantially no continuous pressure contact between the inner and outer surfaces of the tubular molten metal column and the enclosing surfaces of the annular casting vessels 12,13. As a result, the tubular molten metal column in the critical solidification does not have a substantial hydrostatic head, and the gravity, frictional force and adhesive force acting on the tubular molten metal column in the solidification are minimized in the critical solidification zone. descend.

The inner diameter of the outer ceramic liner 12 and the outer diameter of the side portion of the inner ceramic liner 13 form a minute tubular gap between the inner and outer surfaces of the tubular molten metal column 32 and the opposing surfaces of the ceramic liners 12 and 13. Is set as follows. Such a gap is actually a tubular molten metal column 32 rather than a gap.
The spaces are irregularly scattered between the inner and outer surfaces of the mold and the annular casting container, and are too small to be illustrated. In order to achieve good heat transfer, it is essential to maintain the dimensions of such gaps to very small values.
Incidentally, in FIGS. 2 and 3 of the above-mentioned U.S. Pat. No. 4,414,285, it is attempted to illustrate the existence location of such a gap. However, it should be noted that such an illustration is merely a schematic representation and does not truly represent the location and size of the gap. Nonetheless, such gaps are indeed present with irregular interspersions, the presence of which is evidenced by the surface of the solidified tubular metal product having a shiny, wavy appearance. If the gap is made too large by increasing the containment component of the upward levitation electromagnetic field, the effective heat transfer between the tubular molten metal column and the facing surfaces of the ceramic liners 12 and 13 will be significantly impaired. There is.
It is known that there is a high degree of inverse proportionality between electromagnetic field strength and heat transfer rate. Therefore, the strength of the levitation field should be set at the beginning of the casting operation to achieve the desired pressureless contact as defined above, while maintaining a small gap that provides good heat transfer. . The electromagnetic field strength should be maintained at this set value during the casting operation, and the electromagnetic field strength should not be changed even if the speed at which the tubular molten metal column separates from the solidification zone (linear velocity) changes.

Next, referring to FIG. 2, the solidified tubular metal product taken out from the upper end of the annular casting container is introduced into the pre-cooling chamber 34, passes through the take-out rolls 35 and 36,
It passes through two hot rolling steps 37 and 38 arranged in series and is finally cooled in a coiling step 39 before being coiled. Alternatively, if the solidified tubular metal product has a diameter and finish suitable for use as cast, the tubular metal product may be removed from precooling chamber 34 by unload rolls 35 and 36, It is cooled and coiled without further processing.

The casting speed during operation (that is, the linear velocity of the tubular molten metal column passing through the annular casting container / heat exchanger 11) is the drive motor for the take-out rolls 35 and 36 synchronized with the rolling mills 37 and 38 and the coiling mechanism 39. Should be adjusted by controlling The strength of the levitation field and the excitation frequency should be set to values calculated to allow for levitation ratios in the range of 75-200%, depending on the size and resistivity of the tubular metal product to be cast. In a practical system utilizing the present invention, it is desirable to begin operation at a linear velocity less than normal and a levitation ratio greater than normal in order to achieve a reliable start. After a steady state of operation is obtained (within a few minutes), the linear velocity is manually increased stepwise and the strength of the levitation electromagnetic field is stepwise reduced to convert the molten metal into a tubular metal product. It may be adjusted so that the casting speed expressed by the conversion tonnage per hour reaches a maximum value. The system is then maintained at this set point throughout the run time. It is usually desirable to monitor the temperature of the solidified tubular metal product to ensure good production performance. For that purpose, the tubular metal product immediately after being detached from the annular casting container may be monitored by a visual inspection or a pyrometer.

INDUSTRIAL APPLICABILITY According to the present invention, tubular metal products, such as pipes, can be continuously processed in the presence of levitation electromagnetic fields, which greatly reduces the powerful forces and wear found in equipment commonly used in casting tubular metal products. A new method and apparatus for casting is provided.

Although the method and apparatus according to the present invention and the solidified tubular metal product obtained thereby have been described above, it will be apparent to those skilled in the art that other modifications of the present invention are possible in light of the above description. Believed to be. It goes without saying, therefore, that various changes may be made to the particular embodiment described above without departing from the scope of the invention defined by the claims.

[Brief description of drawings]

1 is a partial schematic functional diagram of a new and improved apparatus for casting tubular metal products according to the invention, the main components of such apparatus and their interrelationships during the manufacture of the tubular metal product according to the invention. Is shown. FIG. 2 is a functional block diagram of the entire continuous casting system based on the method of the present invention, which uses the apparatus shown in FIG. In the figure, 10 is a molten metal reservoir, 11 is an annular casting container and heat exchanger, 12 is an outer ceramic liner, 13 is an inner ceramic liner, 14 is a central opening, 15 is an external heat exchanger, 18 is an internal heat exchanger, 22 is an external multiplex winding, 23 is an internal multiplex winding, 24 is a lead wire, 25 is a multi-phase power supply / controller, 26 is a frequency controller, 27 is an output controller, 28 is an internal coil power supply / controller, and 29 is A frequency controller, 31 is an output controller, 32 is a tubular molten metal column, 34 is a precooling chamber, 35 and 36 are take-off rolls, 37 and 38 are rolling mills, and 39 is a coiling mechanism.

Claims (18)

[Claims] (A) An elongated alternating levitation electromagnetic field that travels upward is generated inside an annular casting container, and extends at a right angle to the buoyant electromagnetic field that travels upward and extends over the same range. (B) at least a second confinement electromagnetic field component acting in the opposite direction to the first confinement electromagnetic field component is generated in the central portion of the annular casting container, and (c) A molten metal is introduced into the annular casting container and the lower part of the electromagnetic field to form a tubular molten metal column, and (d) between the inner surface and the outer surface of the tubular molten metal column and the opposing surrounding surface of the annular casting container. Setting the value of the levitation electromagnetic field acting on the tubular molten metal column so as to reduce the hydrostatic head of the tubular molten metal column to a minimum while maintaining a predetermined dimensional relationship, and (e) the tubular molten metal Pillar The cross-sectional dimension is such that it provides pressureless contact between the inner and outer surfaces of the tubular molten metal column and the opposing surrounding surface of the annular casting vessel, but does not form a substantial gap, thereby The value of the electromagnetic field such that pressureless contact and the highest degree of heat transfer between the tubular molten metal column and the annular casting vessel are achieved while at the same time reducing gravity, friction and adhesion to a minimum. And (f) raising the tubular molten metal column in the annular casting vessel, (g) solidifying the molten metal during raising in the annular casting vessel and in the electromagnetic field, and (h ) A method for producing a long tubular metal product, comprising the steps of taking out a solidified tubular metal product from the upper portion of the annular casting container. 2. A continuous casting method in which molten metal is continuously introduced into the lower part of the annular casting container and solidified tubular metal products are continuously taken out from the upper part of the annular casting container. In some cases, the tubular metal product production rate is determined by controlling the rate of withdrawing the tubular metal product from the upper portion of the annular casting vessel and the corresponding rate of introducing molten metal into the lower portion of the annular casting vessel. And the second containment field component is provided by a second upwardly traveling levitation field acting in the central opening of the annular casting vessel. 3. The molten metal column extending upwards in the electromagnetic field is weightless such that the tubular molten metal column has substantially no hydrostatic head over most of its length located in the electromagnetic field. And the strength of the electromagnetic field is set so as to maintain a predetermined dimensional relationship between the inner and outer surfaces of the tubular molten metal column and the opposing surrounding surface of the annular casting vessel, resulting in the tubular shape. The cross-sectional dimension of the molten metal column is maintained at a value that prevents substantially continuous pressure contact between the inner and outer surfaces of the tubular molten metal column and the opposing surrounding surface of the annular casting vessel while at the same time The tubular molten metal column has no substantial hydrostatic head, whereby the tubular molten metal during solidification without impairing the heat transfer between the tubular molten metal column during solidification and the annular casting vessel in the solidification zone. Acts on metal columns That gravity Claims second term method according claims decreases to friction and adhesion minimal. 4. The starting metal pipe is cooled and solidified by contacting the lower end of the starting metal pipe with the upper end of the tubular molten metal column rising in the electromagnetic field as one step of the initial stage. A method as claimed in claim 3 in which is bonded to the tubular molten metal column. 5. (a) an elongated annular casting vessel placed upright to contain molten metal to be solidified, (b)
Means for supplying molten metal to the lower portion of the annular casting vessel to form tubular molten metal columns, (c) heat exchange means connected to the annular casting vessel for cooling and solidifying the tubular molten metal columns. (D) means for removing the solidified tubular metal product from the top of the annular casting container, (e) arranged to surround the outer circumference of the annular casting container along a portion of the length of the annular casting container. First levitation electromagnetic field generating means, (f) the annular shape for generating at least a second confinement electromagnetic field component acting in the opposite direction to the confinement electromagnetic field component generated by the first levitation electromagnetic field generating means Second electromagnetic field generating means arranged at the center of the casting container (the first floating electromagnetic field generating means and the second electromagnetic field generating means lower the hydrostatic head of the tubular molten metal column and Molten gold (Helping to maintain a predetermined dimensional relationship between the inner and outer surfaces of the column and the opposing surrounding surface of the annular casting vessel), (g) the cross-sectional dimension of the tubular molten metal column being the inner surface of the tubular molten metal column And has a size such that it does not form a substantial gap between the outer surface and the opposing surrounding surface of the annular casting vessel to achieve maximum heat transfer between the tubular molten metal column and the annular casting vessel. At the same time, the means for maintaining the values of the levitation electromagnetic field and the confining electromagnetic field components so that gravity, frictional force and adhesive force are reduced to a minimum, and (h) the tubular molten metal column in an annular casting vessel. A continuous casting apparatus for tubular metal products, which comprises means provided separately from the first levitation electromagnetic field generating means and the second electromagnetic field generating means for raising the temperature. 6. The first and second electromagnetic field generating means, wherein the second electromagnetic field generating means also comprises a levitation electromagnetic field generating means.
6. An apparatus according to claim 5, wherein each of the levitation electromagnetic field generating means is composed of a plurality of electromagnetic coils which are connected to successive phases of the multi-phase power source to generate an alternating electromagnetic field which travels upward. 7. A molten metal reservoir for containing a molten metal bath is disposed in communication with the lower end of the annular casting vessel, and forms a tubular molten metal column in the annular casting vessel and at least the first molten metal column. 7. An apparatus according to claim 6, wherein means for raising said tubular molten metal column to a liquid level above the lower end of the levitation electromagnetic field generating means is provided in connection with said molten metal reservoir. 8. A multi-phase generator from a three-phase generator whose power and frequency can be set so as to generate an upward levitation electromagnetic field that is uniform and balanced depending on the type of tubular metal product to be cast. An apparatus according to claim 7, comprising a power supply. 9. The tubular molten metal for use in initial startup of the apparatus, by contacting the lower end of a lifting metal tube with the upper end of the tubular molten metal column in the solidification zone and then solidifying the tubular molten metal column. A patent comprising means for joining the lifting metal tube to the upper end of a pillar and means for removing the lifting metal tube and the solidified tubular metal pillar attached to it at a rate that determines the production rate of the tubular metal product. Device according to claim 8. 10. A means for precooling the solidified tubular metal product immediately after it is released from the upper portion of the annular casting container, a means for rolling the tubular metal product to a desired size, and the means after rolling. An apparatus according to claim 9, comprising means for cooling the tubular metal product to ambient temperature. 11. A means for precooling the solidified tubular metal product immediately after being separated from the upper portion of the annular casting container, and a means for cooling the tubular metal product after precooling to room temperature. Device according to claim 9. 12. A method according to claim 5, wherein the second electromagnetic field generating means comprises a single phase confining electromagnetic field generating means for generating an outward confining electromagnetic field acting on the tubular molten metal column. Equipment. 13. Use for initial startup of the device,
Means for joining the lifting metal tube to the upper end of the tubular molten metal column by contacting the lower end of the lifting metal tube with the upper end of the tubular molten metal column in the solidification zone and then solidifying the tubular molten metal column 13. An apparatus as claimed in claim 12 and comprising means for removing the lifting metal tube and the solidified tubular metal column adhered thereto at a rate which determines the production rate of the tubular metal product. 14. (a) Forming a tubular molten metal column, (b)
At the same time when the tubular molten metal column is introduced into the solidification zone,
Electromagnetically levitating a substantial portion of the tubular molten metal column in the solidification zone to lower the hydrostatic head of the tubular molten metal column, and the inner and outer surfaces of the tubular molten metal column and the surrounding surface of the casting vessel. Electromagnetically enclosing the tubular molten metal column so that a predetermined dimensional relationship is established between
The tubular molten metal column has a cross-sectional dimension such that it does not form a substantial gap between the inner surface and the outer surface of the tubular molten metal column and the surrounding surface of the casting container. The values of the levitation field and the confinement field are set so that pressureless contact and the highest degree of heat transfer with the casting vessel are achieved while at the same time reducing gravity, friction and adhesion to a minimum. And (d) a continuous casting method for a long tubular metal product, which comprises: (d) removing the solidified tubular metal product from the solidification zone while electromagnetically holding the tubular molten metal column. . 15. A major part of the length of the tubular molten metal column in the solidification zone in the longitudinal direction establishes a predetermined dimensional relationship between the inner surface and the outer surface of the tubular molten metal column and the surrounding surface of the casting vessel. As a result of being electromagnetically retained, the cross-sectional dimension of the tubular molten metal column avoids substantially continuous pressure contact between the inner and outer surfaces of the tubular molten metal column and the surrounding surface of the casting vessel. The tubular molten metal column has substantially no hydrostatic head, thereby substantially impairing heat transfer between the tubular molten metal column and the casting vessel during solidification. 15. The method of claim 14 wherein the gravity, friction and adhesion forces acting on the tubular molten metal column during solidification are reduced to a minimum. 16. The tubular molten metal column is continuously formed and enters the solidification zone, while the tubular metal product solidified by means other than the levitation electromagnetic field is continuously taken out from the solidification zone. The method of claim 15 wherein the production rate of the tubular metal product is controlled. 17. The method of claim 16 wherein said levitation electromagnetic field traveling upward has a frequency in excess of 1 kilohertz. 18. The strength of the levitation electromagnetic field so as to give a levitation ratio of 75 to 200% based on the weight per unit length of the tubular molten metal column, depending on the type and size of the tubular metal product to be cast. 17. The method according to claim 16, wherein is set.