JPH1029045A - Method and equipment for casting metal strip - Google Patents

Abstract

PROBLEM TO BE SOLVED: To perform the casting without forming any skull defects or cracking defects by rapidly feeding the molten metal to the meniscus zone in the casting pool and the triple point zone at the end part of the casting pool, and feeding the molten metal at low temperature in a simple metal feed system. SOLUTION: When the molten metal is poured between a pair of cooled casting rolls 16 through a metal feed nozzle 19, and the casting pool which is supported above the roll gap and surrounded by a side gate plate 56 (end closure) at the roll gap end part to cast the solidified strip, the molten metal flows as two outwardly injected flows in the reciprocal direction from the nozzle 19 so as to be directly collided with the cooling surface of the casting roll in the vicinity of the casting pool surface, and the gate plate is made of the non-conductive material, and the current runs in an induction heating element 101 (conductive body) arranged outside of the gate plate 56 to perform the electromagnetic induction heating of the molten metal in the vicinity of the surface of the gate plate 56 and the casting pool.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to the casting of metal strip. In particular, the present invention is applied to the casting of an iron-based metal strip, but is not limited thereto.

[0002]

BACKGROUND OF THE INVENTION It is known to cast metal strip by continuous casting in a twin roll caster. The molten metal is introduced between a pair of horizontal casting rolls that are cooled and rotate in opposite directions, the metal shells are solidified on the moving roll surface, and the metal shells are united at the roll gap to form a solidified strip product. It is fed downward from the roll gap.
As used herein, the term "roll nip" refers to the overall area where the rolls are closest. The molten metal is poured from the ladle into a small container, and then flows from the ladle to the metal supply nozzle located above the roll gap to the roll gap, and as a result, the roll is supported by the roll casting surface immediately above the roll gap. A casting pool of molten metal extending in the gap length direction can be formed. Usually, the ends of this casting pool are
Side weirs or side plates that are slidably engaged and held on the roll end faces to prevent overflow from both ends of the casting pool.

[0003]

However, twin roll casting has met with some success for non-ferrous metals that solidify rapidly upon cooling, but the solidification temperature is high and imperfections on the cooled roll casting surface. There are various problems in applying the technology to the casting of iron-based metals, which tend to cause defects due to uniform solidification. Accordingly, much attention has been paid to the design of the metal supply nozzle to flow the metal into and out of the casting reservoir smoothly and uniformly. US Patent No. 5,178,
In both the devices disclosed in No. 205 and 5,238,050, the metal feed nozzle extends below the casting pool surface and flows down to the slot outlet of the bottom end of the metal feed nozzle immersed in the casting pool. It incorporates means to reduce the kinetic energy of the molten metal. In the device disclosed in US Pat. No. 5,178,205, it is the flow diffuser that reduces the kinetic energy. The flow diffuser has a plurality of flow paths and a baffle located above the diffuser, below which the molten metal flows slowly and uniformly through the elongate exit hole into the casting reservoir to minimize turbulence.
In the apparatus disclosed in U.S. Pat. No. 5,238,050, the molten metal flow is allowed to fall and collide with the nozzle inclined side wall surface at an acute collision angle, so that the metal adheres to the side wall surface and exits. Form a flow sheet towards the channel.
Again, the goal is to allow the metal flow to flow slowly and uniformly from the bottom of the metal supply nozzle to minimize turbulence in the casting pool.

[0004] Tokuho 5-7053 of Nippon Steel Corporation
No. 7 also discloses a metal supply nozzle adapted to allow a gentle and uniform metal flow to flow down into a casting pool. The metal supply nozzle is provided with a perforated baffle / diffuser to remove kinetic energy from the flowing molten metal, and the kinetic energy-depleted metal stream flows through a series of openings in the nozzle sidewall into the casting pool. The openings are angled such that the metal stream flows along the roll casting surface in the longitudinal direction of the roll gap. That is, the opening on one side of the metal supply nozzle allows the metal flow to flow in one direction in the longitudinal direction of the roll gap, and the opening on the other side allows the metal flow to flow in the other direction in the longitudinal direction of the roll gap, so that the metal flows smoothly along the casting surface. The aim is to minimize the disturbance of the casting pool surface by creating a uniform flow in the casting.

As a result of extensive studies and studies conducted by the present inventor, a major cause of the defect is that the molten metal prematurely solidifies in the so-called "meniscus" or "meniscus area" where the casting pool surface meets the roll casting surface. I realized that. The molten metal in each of these zones flows toward the adjacent casting surface, and if solidification of the molten metal occurs before even contact with the roll surface, an irregular initial heat transfer between the metal shell and the roll occurs. This is likely to occur, and as a result, surface defects such as pits, ripple marks, hot water boundaries, and cracks will be formed.

[0006] Prior attempts to make the molten metal flow into the casting pool very uniformly have been made in an area where the metal first solidifies due to shell surface formation, ie, the area that eventually becomes the outer surface of the formed strip. The premature solidification is inevitably intensified to some extent due to the inflow of the metal stream out of the way, so the molten metal temperature in the casting pool surface area between the rolls is much higher than the temperature of the incoming molten metal. Low. If the temperature of the casting pool molten metal in the meniscus area is too low, cracks and "meniscus marks" (marks on the strip caused by the meniscus that solidify with non-uniform casting pool levels) are very likely to occur. Conventionally, one way to address this problem is to apply a high level of superheating to the incoming molten metal so that the molten metal can cool down in the casting pool without reaching the solidification temperature before reaching the roll surface. However, a much more effective method has been developed in which a metal supply nozzle is inserted directly into the meniscus area of the casting pool to ensure a relatively rapid supply of molten metal, before contact with the casting roll surface. The tendency of the molten metal to prematurely solidify is minimized. This method is much more effective at avoiding surface defects than providing an absolutely steady metal flow to the casting pool, and the casting pool does not solidify until the metal contacts the roll surface. It has been found that some surface variations are acceptable. A very large reduction in the superheat required for the incoming metal can also be achieved.

According to a special method and apparatus developed by the Applicant, molten metal exits the metal feed nozzle as a reciprocally outwardly directed double jet and impinges immediately near the casting pool surface. It has been found that casting can be performed with a relatively low level of superheated molten metal without forming surface cracks. However, solid metal pieces called skulls are formed near side dams of the casting pool. Doing so can cause various problems. These problems are exacerbated by reducing overheating of the incoming molten metal. The heat loss rate from the casting pool is the largest near the side weir, mainly due to the additional heat transfer from the side weir to the roll end, and this area reflects the magnitude of the local heat loss. Solid metal skulls tend to form, grow to significant dimensions, fall between rolls and "bounce", and can cause strip defects.

Since the net rate of heat loss is large near the side weir,
To prevent skulls, the rate of heat input to these areas must be increased. For example, Applicant's U.S. Pat.
As seen in the metal feed nozzles disclosed in U.S. Pat. No. 21,511, these "triple point" areas are formed by forming galleries at the top of the metal feed nozzle that receive a separate metal stream from the tundish. Previous proposals to increase flow have required the formation of complex tunnels and high levels of molten metal overheating due to lower metal temperatures in the tunnels. Becomes

In accordance with the present invention, a casting pool in which a "skull" can be formed without significantly increasing overheating of the entire casting pool and without adversely affecting metal solidification in the lower area of the casting pool near the roll gap. The required increase in net heat input can be achieved by electromagnetic induction heating of the molten metal in the upper portion of the casting pool near the side dams with sufficient focus.

Japanese Patent Application Laid-Open No. 62-771 by Nippon Steel Corporation
No. 56 is a prior application that discloses electromagnetic induction heating of a casting pool near a side weir of a twin-roll caster. In this application, a C-shaped winding arranged in a substantially central vertical plane between casting rolls is disclosed. Induction heating is achieved by placing a pair of induction heating devices having an induction coil on the outside of the side weir to provide diffusion heating over substantially the entire depth in the central region of the casting pool. According to the invention, much more carefully targeted,
Heating of the molten metal entering the casting pool can be achieved in the meniscus area of the casting pool upper surface where skull formation is a problem. This is achieved by targeted heating over the top surface of the casting pool and in the meniscus area by means of an induction heating coil formed in a single closed loop and located near the top of the casting pool.

European Patent Publication No. 491641 describes:
A twin roll caster is disclosed wherein a thin metal side plate surrounds the casting pool and an electromagnetic induction coil is disposed outside the side plates to heat the side plate and the metal in the casting pool. ing. The use of thin metal side plates requires external cooling means to prevent the plates from melting and deforming, and the molten metal cools down, causing various severe problems. A balanced external heating means is essential. The induction coil of the device disclosed in this European document is operated at a low frequency to provide diffusion heating over the entire casting sump area, including the lower area adjacent to the casting roll gap. This is in contrast to the targeted heating achievable by the present invention.

[0012]

According to the present invention, molten metal is introduced between casting rolls through an elongated metal supply nozzle disposed above and along the roll gap between a pair of cooled casting rolls. Forming a casting pool of molten metal supported above the roll gap and surrounded at the roll gap end by a casting pool enclosure end closure to cast a solidified strip fed down from the roll gap. Rotating the metal strip casting method, wherein the molten metal flows out of the metal supply nozzle as a double jet flowing outward in opposite directions and directly collides with a casting roll cooling surface near the casting pool surface, The end closure is made of a non-conductive material and a current is passed through a conductor disposed outside the end closure to melt the end closure and the vicinity of the casting pool surface. Metal strip casting method, characterized in that the electromagnetic induction heating of the metal is provided.

Further, the present invention provides a pair of parallel casting rolls forming a roll gap therebetween, and a molten metal disposed along the roll gap above the roll gap between the two casting rolls and supplying molten metal to the roll gap. An elongated metal supply nozzle that forms a casting pool of molten metal supported above the roll gap,
A metal strip casting apparatus comprising a pair of casting pool surrounding end closures, one at each end of said pair of casting rolls, wherein the molten metal flows out in a reciprocally outward double jet stream. A metal feed nozzle having a series of side openings along each of its longitudinal sides to directly impinge on a casting roll cooling surface near a casting pool surface, said end closure being a plate of non-conductive material. Disposing a pair of conductors one outside each of the end closures,
An electric supply means for supplying an electric current to the conductor to cause induction heating of the molten metal near the end closure and the casting pool surface, wherein each of the conductors is substantially at the level of the casting pool surface and A relatively wide horizontal top extending over the roll gap height to a relatively narrow bottom spaced upwardly from the roll gap height by a single loop formed by a pair of downwardly constricted sides. And a metal strip casting apparatus.

The conductor loops in such a metal strip casting apparatus are spaced above the roll gap so that they do not extend below two thirds of the casting pool depth, and the sides of each loop are connected to each end closure. Preferably, it is curved following the connection with the casting roll, and more preferably the bottom of the loop is within about 70 mm below the casting pool surface height.

Further, the loop of the conductor is preferably a single trapezoidal loop formed of a hollow metal tube, and a cooling means for circulating a cooling fluid is preferably provided in the hollow metal tube.

The electric current passing through the conductor has a frequency of 6 to 10
It is preferably an alternating current of kHz.

Further, a plate of the end closure is held in a plate holder, and the plate holder is connected to a piston rod of a pair of thruster cylinder devices so that the end closure can be pressed against a casting roll. It is preferred to be spaced above the rod, the plate holder being pivotally connected to the piston rod of the cylinder device to allow the end closure to tilt and the conductor to be fixed to the piston rod so as not to interfere with the tilt of the end closure. Is preferred.

[0018]

Embodiments of the present invention will be described below with reference to the drawings.

1 to 8 show an embodiment of the present invention. The illustrated casting apparatus has a main machine frame 11 rising from a factory floor 12. Main machine frame 1
A casting roll carriage 13 supported by 1 is horizontally movable between an assembly station 14 and a casting station 15. A pair of parallel casting rolls 16 carried by a casting roll carriage 13 are provided with a dispenser 18 from a ladle 17 during casting.
The molten metal is supplied through the metal supply nozzle 19 and the metal supply nozzle 19. Since the casting roll 16 is water-cooled, a metal shell is formed on the surface of the moving roll and is joined at the roll gap to produce a solidified metal strip 20 at the roll exit.
This metal strip 20 may be sent to a main coiler 21 and then to a second coiler 22. Since the container 23 is mounted on the main machine frame 11 adjacent to the casting station 15, molten metal can escape to the container 23 via the overflow port 24 of the distributor 18.

The bogie frame 31 constituting the cast roll bogie 13 is mounted on the rails 33 by the wheels 32, and the rails 33 extend along a part of the main machine frame 11, so that the entire cast roll bogie 13 moves to the rails 33. It will be listed as possible. The casting roll 16 is rotatably mounted on a pair of roll cradle 34 carried by the carriage frame 31. A double-acting hydraulic piston cylinder device 39 capable of moving the entire casting roll truck 13 along the rail 33 is provided with a drive bracket 40 of the casting roll truck 13.
And the main machine frame 11 so that the casting roll carriage 13 can be moved from the assembly station 14 to the casting station 15 and vice versa.

The casting roll 16 is rotated in opposite directions via a roll drive shaft 41 of an electric motor and a transmission on the bogie frame 31. A series of water cooling passages formed in the copper peripheral wall of the casting roll 16 and extending in the longitudinal direction and separated in the circumferential direction are connected with a roll end from a water cooling conduit in a roll drive shaft 41 connected to a water cooling hose 42 via a rotating gland 43. Cooling water is supplied via the A typical size of the casting roll 16 is about 500 mm in diameter and can be up to 2 m in length to produce strips up to 2 m wide.

The ladle 17 is entirely conventional and is supported from the overhead crane via the yoke 45 and can be moved from the hot metal receiving station to a fixed position.
By moving a stopper rod 46 attached to the ladle 17 with a servo cylinder, the molten metal is removed from the ladle 17.
Through the outlet nozzle 47 and the refractory shroud 48 to the distributor 18.

The distributor 18 is a wide dish made of a refractory material such as a high-alumina castable having a corrosion-proof lining. One side of the distributor 18 receives the molten metal from the ladle 17 and is provided with the overflow port 24 described above. On the other side of the distributor 18 are a series of vertically spaced outlet openings 52.
Is provided. A mounting bracket 53 for supporting the lower portion of the distributor 18 is for mounting the distributor 18 to the bogie frame 31. The mounting bracket 53 receives the positioning pegs 54 of the bogie frame 31 through an opening provided in the mounting bracket 53, and the distributor 18 is moved. It is designed to position accurately.

The metal supply nozzle 19 is formed as an elongate body made of a refractory material such as alumina graphite, and has a tapered lower portion and narrows inward and downward. it can. The mounting bracket 60 is provided to support the metal supply nozzle 19 with the bogie frame 31, and a side flange 55 that protrudes outward is formed above the metal supply nozzle 19 and is located on the mounting bracket 60.

The metal supply nozzle 19 has an upwardly open nozzle trough 61 for receiving molten metal flowing down from an outlet opening 52 of the distributor 18. The bottom of the nozzle trough 61 is formed between the side walls 62 narrowing downward, and the trough bottom is closed by a horizontal bottom floor 63. Each longitudinal side wall 62
A series of horizontally spaced side openings 64 in the form of circular holes extending horizontally through the side walls 62 are drilled.

The molten metal falls from the outlet opening 52 of the distributor 18 as a series of free-falling vertical flows 65, forming a molten metal reservoir 66 at the bottom of the nozzle trough 61. Molten metal flows out of this reservoir 66 through side openings 64 to form a casting pool 68 supported above the roll gap between the casting rolls 16. Casting pool 68 into casting roll 16
Surrounded by the ends are a pair of side dams 56 which are held against the end 57 of the casting roll 16. The side dam plate 56 is made of a strong refractory material such as boron nitride and attached to the plate holder 82. The plate holder 82 is movable by the operation of the pair of hydraulic cylinder devices 83,
The side dam plate 56 is engaged with the end of the casting roll 16 to form an end closure for the casting pool of molten metal.

In the casting operation, by controlling the metal flow, the casting reservoir 68 is held at a height at which the lower end of the metal supply nozzle 19 is immersed in the casting reservoir 68, and the metal supply nozzle 19
A series of horizontally spaced side openings 64 are located just below the surface of the casting pool 68. Molten metal exits as two laterally outward jets near the casting pool 68 surface generally through the side opening 64 so as to impinge on the casting roll 16 cooling surface immediately adjacent to the casting pool 68 surface. I do. It has been found that this maximizes the temperature of the molten metal supplied to the meniscus area of the casting pool 68 and significantly reduces cracking and meniscus mark formation on the strip surface.

According to the present invention, a pair of induction heating elements 10
1 is disposed immediately outside the side dam plate 56. More specifically, the induction heating element 101 is attached to the thruster body 85 so that the upper side of the side dam plate 56 does not interfere with the rotation of the side dam plate 56 about the pivot pin 84.

Each side dam board 56 has a shape including a wide top 102, a narrow bottom 103, and an arc-shaped side 104 overlapping the end 57 of the casting roll 16. Each induction heating element 101 has a substantially trapezoidal conductive structure disposed adjacent to the back of each side dam plate 56 so as to be adjacent to the top of the casting pool 68 when the apparatus is used. More specifically, each induction heating element 1
In the terminal 01, a thick tubular copper conductor having a substantially rectangular cross section extends from the parallel terminal socket 105 in the form of a trapezoidal loop and is connected to the alternating current supply lead 120 by a bus bar 110. An alternating current is supplied via the socket 105. The cooling water is circulated in the loop through the conductive part 106 as shown by the arrow 121 in FIG. 8, and a separate cooling water flow is passed through the bus bar 110 as shown by the arrow 122.

Each trapezoidal copper loop has a wide top 107 located approximately at the level of the casting pool 68 surface and a narrow bottom 108 configured to be positioned about 70 mm below the casting pool 68 surface. . The top 107 and the bottom 108 are connected by an arc-shaped side 109 following the curve of the casting roll 16.

The induction heating element 101 is effective to induce induction heating of the molten metal above the casting pool 68 immediately adjacent to the side dam plate 56. The loop is designed to maximize heating around the triple point in the meniscus area of the casting pool 68. This reduces "skull" formation in this area of the casting pool 68 and, in conjunction with a metal supply nozzle that allows a uniform metal flow to flow through the length of the casting roll 16 to the meniscus area of the casting pool 68, provides It has been proved that the superheating of the molten metal supplied to the furnace can be drastically reduced and that the superheating of 70 ° C. or less can be achieved.

By using the non-conductive side dam plate 56,
The electromagnetic field generated by the formed induction heating element 101 extends through the side dam plate 56, without heating the side dam plate 56 and without the need for an electromagnetic shaping element or an electromagnetic field concentrator element. It has been found to cause effective heating of the molten metal. However, it is also within the scope of the present invention to provide a suitable electromagnetic shaped core piece around the conductor loop to act as an electromagnetic field concentrator for the purpose of reducing power requirements.

FIGS. 9 and 10 illustrate the effectiveness of the present invention in which no skull is formed during low superheat casting. These figures show the results of measuring the casting roll separating force during the single strip casting operation of the steel strip in the twin roll casting machine as shown in FIGS. FIG. 9 shows the casting roll separation force measured when the switch that energizes the induction heating element 101 is intentionally turned off, and it can be seen that the roll separation force constantly varies over time. Varying roll separation forces are associated with skull passing through the casting roll gap, resulting in severe defects in the strip. FIG. 10 shows the measurement result of the roll separation force after turning on the switch for energizing the induction heating element 101, and it can be seen that the fluctuation of the roll separation force is reduced. This is related to the elimination of skull formation,
No corresponding defects occur in the strip.

In the operation of a conventional twin roll caster producing one meter wide steel strip at a rate of 60 m / min,
The induction heating element 101 has a frequency of 6 to 10 kHz and 300
It is necessary to supply a current of 0 to 8000 amp. Therefore, the total power input to the induction heating element 101 is about 10 to 100 kW per heater.

It is important to note that operation of the present invention is that the induction heating element 101 does not extend below the casting sump 68. It has been found that severely damaging skulls are formed only in the upper part of the casting pool up to a depth of about 70 mm, while in the lower part of the casting pool the metal has already solidified when the casting roll approaches the roll gap. It is important not to reheat at this stage. This can be ensured by separating the loops above the roll gap so that they do not extend downward from below the casting pool depth to 1/3 the height. In the prior art for induction heating of a casting pool, only a general heating of the casting pool is performed, and a heater for heating the entire casting pool depth is used. By arranging the induction heating element 101 sufficiently above the gap between the casting rolls, the fluid pressure cylinder device 83 and related thruster components can be arranged below the induction heating element 101, causing interference as described above. The side dam 56 can be tilted about the pivot pin 84 without inadvertently heating the thruster components.

The above-described device is merely an example, and it is needless to say that various modifications can be made. For example, instead of supplying molten metal in a series of free-falling flows from a distributor such as a tundish to the metal supply nozzle as in the apparatus shown in FIGS. It is possible to distribute to the nozzle. Such an inlet nozzle may be a single tube, for example as disclosed in the applicant's international application PCT / AU97 / 00022. This allows a sufficient direct flow of molten metal to be evenly distributed along the casting pool through the metal feed nozzle outlet, thereby rapidly distributing the molten metal to the meniscus area of the casting pool.

[0037]

As described above, according to the metal strip casting method and apparatus of the present invention, a simple metal supply can be performed without requiring a complicated injection system for triple point injection as in the conventional proposal. The system is capable of rapidly supplying molten metal to the meniscus area of the casting pool and the triple point area at the end of the casting pool, and the excellent effect that the molten metal supplied with low superheat allows casting without forming skull defects and crack defects. Can be played.

[Brief description of the drawings]

FIG. 1 is an overall view showing an example of an embodiment for implementing the present invention.

FIG. 2 is a longitudinal sectional view showing details of a main part of the twin roll casting machine shown in FIG.

FIG. 3 is a further longitudinal sectional view in a direction perpendicular to the section of FIG. 2;

FIG. 4 is an enlarged vertical sectional view of a portion adjacent to a metal supply nozzle and a casting roll.

FIG. 5 is a side view of a metal supply nozzle.

6 is a view in the direction of arrows VI-VI in FIG. 3;

FIG. 7 is an end view showing the casting roll with the side dam plate and the induction heating element.

FIG. 8 is a perspective view of FIG. 7;

FIG. 9 is a graph showing roll separation force measurement results when induction heating is not performed.

FIG. 10 is a graph showing a result of roll separation force measurement when induction heating is performed.

[Explanation of symbols]

Reference Signs List 16 casting roll 19 metal supply nozzle 20 metal strip 56 side dam plate (end closure) 64 side opening 68 casting reservoir 82 plate holder 83 fluid pressure cylinder device (thruster cylinder device) 101 induction heating element (conductor) 107 top 108 Bottom 109 side

 ──────────────────────────────────────────────────の Continued on the front page (72) Inventor Chris Baharris Australia Victoria 3152 Wantana Milpera Crescent 84

Claims (9)

[Claims] 1. A molten metal is introduced between casting rolls through an elongated metal supply nozzle disposed above and along the roll gap between a pair of cooled casting rolls, the molten metal being supported above the roll gap and having a casting pool. A method of casting a metal strip, comprising forming a casting pool of molten metal surrounded at an end of a roll gap by a surrounding end closure, and rotating a casting roll to cast a solidified strip fed downward from the roll gap. The molten metal flows out of the metal supply nozzle as a reciprocally outward outward jet stream to directly collide with the casting roll cooling surface near the casting pool surface, and the end closure is made of a non-conductive material. It is characterized in that electromagnetic current is applied to the molten metal near the end closure and the surface of the casting pool by passing an electric current through a conductor disposed outside the end closure. Metal strip casting method. 2. A pair of parallel casting rolls forming a roll gap between each other, and disposed along the roll gap above the roll gap between the two casting rolls and supplying molten metal to the roll gap to supply the molten metal to the roll gap. A metal strip casting apparatus comprising an elongated metal supply nozzle forming a casting pool of molten metal supported on a pair of casting rolls and a pair of casting pool surrounding end closures arranged one at each end of the pair of casting rolls. There is a series of sides along each longitudinal side of the metal feed nozzle to discharge the molten metal as a series of reciprocally outwardly directed jets and directly impact the casting roll cooling surface near the casting pool surface. The end closure is a plate made of a non-conductive material, and a pair of conductors are disposed one outside each of the end closures, and the end closure and the casting reservoir surface are provided. Providing electricity supply means for supplying current to the conductor to cause induction heating in the nearby molten metal,
Each conductor constricts a relatively wide horizontal top extending substantially over the casting pool surface and extending across the casting pool end to a relatively narrow bottom spaced upwardly from the roll gap height. A metal strip casting apparatus having a single loop shape connected by a whole pair of side portions. 3. The conductor loop may have a depth of 2/1/2 of the casting pool depth.
3. The metal strip casting apparatus according to claim 2, wherein the metal strip casting apparatus is spaced above the roll gap so as not to extend below 3. 4. The metal strip casting apparatus according to claim 2, wherein a side portion of the loop of the conductor is curved in accordance with a connection portion between each end closure and the casting roll. 5. The metal strip casting apparatus according to claim 2, wherein the bottom of the conductor loop is within about 70 mm below the casting pool surface height. 6. The loop according to claim 2, wherein the conductor loop is a single trapezoidal loop formed of a hollow metal tube, and cooling means for circulating a cooling fluid in the hollow metal tube is provided. Metal strip casting equipment. 7. An electric current passing through a conductor has a frequency of 6 to 10 kHz.
The metal strip casting apparatus according to any one of claims 2 to 6, wherein the current is an alternating current of z. 8. An end closure is held in a plate holder, and the plate holder is connected to a piston rod of a pair of thruster cylinder devices so as to press the end closure against a casting roll, and a conductor is disposed above the piston rod. The metal strip casting apparatus according to claim 2, 3 or 4, which is spaced apart. 9. The plate holder according to claim 8, wherein the plate holder is pivotally connected to the piston rod of the cylinder device to enable the tilting of the end closure, and the conductor is fixed to the piston rod so as not to interfere with the tilting of the end closure. The metal strip casting apparatus as described in the above.