JP7109607B2 - Thin Strip Continuous Casting Method and Apparatus by Roll Crown Control - Google Patents

Description

This application is an international application of U.S. Patent Application Serial No. 14/946,872, filed November 20, 2015.

The present invention relates to the casting of metal strip by continuous casting on a twin roll caster.

In a twin roll caster, molten metal is introduced between a pair of cooled, counter-rotating horizontal casting rolls, causing a metal shell to solidify on the moving casting roll surfaces to form the nip between the casting rolls. to produce a solidified strip which is fed downwardly from the roll nip. The term "roll nip" is used herein to refer generally to the area of closest proximity between the casting rolls. Molten metal is poured from a ladle into one or a series of small vessels from which it flows through metal feed nozzles located above the nip and extends along the nip length just above the nip. A casting pool of molten metal supported on roll casting surfaces may be formed. The casting pool is typically defined by side plates or dams held in sliding engagement with the end faces of the casting rolls to dam the ends of the casting pool against overflow.

A twin roll caster is capable of continuously producing cast strip from molten steel through a series of ladles arranged on a turret. Molten metal is poured from each ladle into the tundish and then into the movable tundish before flowing through metal feed nozzles into the casting pool. The tundish allows empty ladles to replace full ladles on the turret without interrupting the production of cast strip.

In thin strip casting with a twin roll caster, casting rolls, generally made of copper or copper alloys and usually coated with chromium or nickel, are internally cooled with cooling water to provide a high heat flux and thus rapid solidification of the strip during casting. , where the casting rolls undergo substantial thermal deformation due to exposure to molten metal. The crown of the casting roll casting surface changes during the casting operation. The crown of the casting roll casting surfaces determines the strip thickness profile, ie the cross-sectional shape, of the thin cast strip produced in the twin roll caster. A casting roll with a convex (ie, positive crown) casting surface produces a cast strip with a negative (ie, center-recessed) profile. Conversely, a casting roll with a concave (ie negative crown) casting surface produces a cast strip with a positive (ie centrally raised) profile. Thus, the roll crown of the casting roll casting surface is used to produce the desired strip cross-sectional thickness profile under normal casting conditions.

In thin strip casting, the casting rolls are typically cold machined with an initial crown based on the expected crown of the casting surface of the casting rolls during casting. However, the difference in casting roll casting surface profile in the cold and as-cast conditions is difficult to predict. Furthermore, the crown of the casting surface of the casting rolls can change significantly during the casting operation. The crown of the casting surface of the casting rolls can change due to other casting conditions such as temperature changes in the molten metal being fed into the casting pool of the caster during casting, changes in casting roll casting speeds, and slight changes in molten steel composition.

Previous proposals for casting roll crown control have relied on mechanical devices to physically deform the casting rolls, such as by moving elements such as deformation pistons within the casting rolls or by applying bending forces to the casting roll support shafts. have depended. However, these conventional casting roll crown control proposals have limitations. For example, Japanese Patent No. 2544459 (hereinafter referred to as Patent Document 1) uses casting rolls having internal "water-cooled roll heating means embedded in two ends" to reduce the deformation that occurs at each roll end during casting. It discloses that it controls See the column of "Means for Solving the Problems" in Patent Document 1. The casting rolls are solid metal rolls with internal cooling passages and require water heating means at the ends of the casting rolls. A limitation of the caster disclosed in US Pat. No. 5,560,421 is discussed in US Pat. The deformation response of the outer surface of the drum to be processed is slow, and it would be difficult or impossible to control the workpiece in a timely manner." Patent document 2, column 1, line 64 to column 2, line 1. WO 2005/020000 further explains that "it may not be possible to adequately control the shape of the workpiece to be continuously cast". Ibid., column 2, lines 6-7. US Pat. No. 5,300,003 proposes a solution in which the solid casting rolls have end notches with large external annular elements (relative to the solid rolls) that are heated with hot water. These annular elements are used to modify the profile of the casting rolls. Patent document 2, column 2, lines 37-42.

Japanese Patent No. 2544459 U.S. Pat. No. 5,560,421

However, large solid casting rolls such as those proposed in US Pat. It is relatively short and not very responsive due to its large thermal mass.

For example, by placing an expansion ring directly into a cylindrical tube, 80 mm thick, made of copper and copper alloys, optionally coated with chromium or a chromium alloy, and having a plurality of longitudinal water channels extending therein, the casting rolls It has also been proposed to form This proposal has been tried and failed. Since the heat provided to the expansion ring is transferred to the cylindrical tube, the ring must be thermally effective to expand the cylindrical tube to commercially control the crown shape of the casting roll casting surface. They didn't respond. Therefore, there is still a need for a reliable and effective strategy for directly and closely controlling the crown shape of the casting roll casting surface during casting and thus the cross-sectional thickness profile of thin cast strip produced in twin roll casters. ing.

Disclosed is a reliable method for controlling the casting roll crown, and thus the cross-sectional strip thickness profile, by controlling the crown of the casting surface of the casting roll with expansion rings positioned adjacently within the cylindrical tubes forming the casting rolls. is a valid and effective method. Disclosed is
a. A pair of counter-rotating casting rolls with a nip between them so that the cast strip can be fed downwardly through the nip, each casting roll having a casting surface having a thickness of 80 mm or less and made of copper or a copper alloy. assembling a caster formed by a cylindrical tube made of a material selected from the group and having a plurality of longitudinal water passages extending therein;
b. At least two expansion rings are positioned adjacent within the cylindrical tube within 450 mm inwardly from the cast strip edges formed at the opposite ends of the casting rolls during the casting operation, each expansion ring receiving at least one heating element. and a thermal insulation coating configured to alter the roll crown and cast strip thickness profile of the casting roll casting surface during casting by causing expansion of the cylindrical tube due to an increase in radial dimension; configured to minimize heat transfer from the inner expansion rings to the casting rolls and to regulate the expansion of the expansion rings and thus the cylindrical tube by providing channels in each expansion ring through which water can flow;
c. assembling a metal feed system capable of forming a casting pool supported on the casting surfaces of the casting rolls above the nip by side dams defining the casting pool adjacent the ends of the nip;
d. A roll crown comprising controlling the roll crown of a casting roll casting surface during a casting operation by controlling the radial dimension of an expansion ring in response to at least one of digital or analog signals received from at least one sensor. Controlled thin strip continuous casting method.

The amount of power applied to the expansion ring can be varied based on feedback from the at least one sensor, the sensor capable of detecting at least one of the following characteristics:
temperature of the expansion ring,
downstream cast strip thickness profile;
the local thickness of the cast strip at a defined point close to the cast strip edge;
casting roll surface crown during casting operation and radial casting roll expansion at a defined point close to the casting strip edge;
and can emit a digital or analog (usually electrical) signal indicative of at least one of said properties of the cast strip.

Care should be taken to make the thermal barrier coating on each expansion ring sufficiently thick to control or eliminate heat transfer from the expansion ring to the casting rolls. A thermal barrier coating of at least 0.010 inch (eg, 0.025 inch) thickness is required for effective control of heat transfer from the expansion ring to the casting rolls. The thermal barrier coating may be plasma jets on the expansion ring. The thermal barrier coating may be plasma blasted with a zirconia blast, such as an 8% yttria stabilized zirconia blast. The thermal insulation coating can also be applied to the cylindrical tube, but for economy and effectiveness the thermal insulation coating should be applied directly to the expansion ring.

Each expansion ring may have at least one heating element, which may be made of stainless steel, nickel, or nickel alloys, and may be positioned within each expansion ring at desired locations. Each expansion ring can provide a heat input of up to 30 kW, preferably at least 3 kW.

Also, by adjusting the water flow through the expansion ring, the radial dimension of the expansion ring can be scaled, and thus the diameter of the cylindrical tube can be increased or decreased as desired to control the casting roll casting surface crown shape during operation.

Furthermore, the method for continuously casting thin strip with roll crown control comprises controlling a casting roll drive to vary the casting roll rotation speed, and in accordance with at least one of the digital or analog signals received from the at least one sensor. It may further comprise controlling the roll crown of the casting roll casting surface during the casting operation by varying the expansion ring radial dimension.

In addition, the continuous thin strip casting process with roll crown control has at least one heating element each, is thermally insulated, and increases or decreases in radial dimension to cause expansion and contraction of the cylindrical tube to increase or decrease the casting during casting. At least one expansion ring (e.g., up to 15 expansion rings) configured to alter the crown of the roll casting surface and the cast strip thickness profile corresponding to the casting strip center formed on the casting roll during casting. It may further comprise placing. Furthermore, a method of continuously casting thin strip with roll crown control includes an expansion ring with a thermal insulation coating and spaced from the cast strip edge while controlling a casting roll drive to vary the casting roll rotational speed; varying the radial dimension of the expansion ring corresponding to the center of the cast strip to which the casting is applied in response to electrical signals received from the sensor to control the roll crown of the casting surface of the casting roll during the casting operation.

Alternatively, the thin strip continuous casting method by roll crown control is
a. A pair of counter-rotating casting rolls with a nip between them so that the cast strip can be fed downwardly through the nip, each casting roll having a casting surface having a thickness of 80 mm or less and made of copper or a copper alloy. assembling a caster formed by a cylindrical tube made of a material selected from the group and having a plurality of longitudinal water passages extending therein;
b. At least one expansion ring is positioned within the cylindrical tube corresponding to the central portion of the cast strip formed against the casting rolls during the casting operation, each expansion ring having at least one heating element and a thermal insulation coating. is configured to alter the crown of the casting surface and cast strip thickness profile during casting by causing expansion of the cylindrical tube by increasing its radial dimension; configured to adjust the expansion of the expansion ring and thus the cylindrical tube by providing a channel within each expansion ring through which water can flow, minimizing transmission;
c. assembling a metal feed system capable of forming a casting pool supported on the casting surfaces of the casting rolls above the nip with side dams defining the casting pool adjacent the ends of the nip;
d. Roll crown of the casting surface of the casting roll during casting operations by controlling the radial dimension of the at least one thermally coated expansion ring in response to at least one digital or analog signal received from at least one sensor. may be configured by controlling the

The amount of power applied to the expansion ring can be varied based on feedback from the at least one sensor, the sensor capable of detecting at least one of the following characteristics:
temperature of the expansion ring,
downstream cast strip thickness profile;
the local thickness of the cast strip at a defined point close to the center of the cast strip;
radial casting roll expansion at defined points close to the casting roll surface crown and the center of the cast strip during the casting operation;
and can emit a digital or analog (usually electrical) signal indicative of said at least one of said properties of the cast strip.

Again, the thermal barrier coating on each expansion ring should be thick enough to effectively control heat transfer from the expansion ring to the casting rolls. Effective control of heat transfer from the expansion ring to the casting rolls requires a thermal barrier coating of at least 0.010 inch (eg, 0.025 inch) thickness. The thermal barrier coating may be plasma sprayed onto the expansion ring. The thermal barrier coating may be plasma blasted with a zirconia blast, such as an 8% yttria stabilized zirconia blast. The thermal insulation coating can also be applied to the cylindrical tube, but for economy and effectiveness the thermal insulation coating should be applied directly to the expansion ring.

Again, each expansion ring may have at least one heating element, which may be made of stainless steel, nickel, or nickel alloys, and may be positioned anywhere about each expansion ring as desired. Each expansion ring can provide a heat input of up to 30 kW, preferably at least 3 kW.

Again, by adjusting the flow of water, the radial dimension of the expansion ring can be increased or decreased, and thus the diameter of the cylindrical tube can be increased or decreased as desired to control the casting roll geometry during operation.

Further, the method for continuously casting thin strip with roll crown control comprises controlling the casting roll drive to vary the rotational speed of the casting rolls while varying the radial dimension of the expansion ring according to the electrical signal received from the at least one sensor. It may further comprise variably controlling the casting surface roll crown of the casting rolls during the casting operation.

In addition, alternative roll crown controlled continuous thin strip casting processes each have at least one heating element and are thermally insulated to increase the radial dimension to cause expansion of the cylindrical tube during casting. at least two expansion rings configured to alter the roll crown and cast strip thickness profile of the casting surfaces of the casting rolls inwardly from the casting strip edges formed at the opposite ends of the casting rolls during the casting operation; adjacently positioned within the cylindrical tube within 450 mm of each other. Furthermore, the method for continuously casting thin strip by roll crown control comprises controlling the casting roll drive device to change the rotational speed of the casting rolls, while adjusting the radial dimension of the expansion ring corresponding to the central portion of the cast strip to which the thermal insulation coating is applied. and the roll crown of the casting surface of the casting roll during the casting operation by varying the radial dimension of the thermally coated expansion ring spaced from the casting strip edge in response to electrical signals received from said at least one sensor. may include controlling the

In each embodiment, the expansion ring may be made of austenitic stainless steel, such as 18/8 austenitic stainless steel. Each expansion ring may have an annular dimension of 50-150 mm, preferably 70 mm. Each expansion ring may have a width of up to 200 mm, preferably up to 100 mm, more preferably 83.5 mm.

In each embodiment of the method, the crown of the casting roll casting surface can be easily changed to achieve the desired cast strip thickness profile. Each thermally coated expansion ring is configured to increase or decrease its radial dimension to cause expansion or contraction of the cylindrical tube, thereby altering the crown of the casting roll casting surface and the cast strip thickness profile. The thickness of the cylindrical tube can range from 40-80 mm or 60-80 mm.

In each embodiment of the method, at least one sensor may be positioned downstream and configured to detect the cast strip thickness profile and provide an electrical signal indicative of the cast strip thickness profile. The sensor can be placed adjacent to pinch rolls through which the strip passes after casting. Crown control of the casting roll casting surface may be achieved by controlling the radial dimension of each expansion ring in response to electrical signals received from the sensors. Further, crown control of the casting surface of the casting rolls is achieved by controlling the casting roll drives to vary the rotational speed of the casting rolls while also varying the radial dimension of each expansion ring in response to electrical signals received from sensors. achievable.

The radial dimension of each expansion ring can be controlled independently of the radial dimensions of the other expansion rings. The radial dimension of each expansion ring adjacent the strip edge of the casting roll casting surface can be controlled independently of each other. Additionally, the radial dimension of the expansion ring adjacent the strip edge of the casting roll casting surface can be controlled independently of the expansion ring corresponding to the casting strip center.

A thin strip continuous casting apparatus with controlled roll crown is also disclosed, comprising: a. A pair of counter-rotating casting rolls with a nip therebetween and capable of feeding cast strip downwardly through the nip, each casting roll having a casting surface having a thickness of 80 mm or less and made of copper and copper alloys. a pair of casting rolls formed of a cylindrical tube made of a material selected from the group consisting of:
b. having at least one heating element and a thermal insulation coating, configured to cause expansion of the cylindrical tube by increasing its radial dimension to alter the roll crown and cast strip thickness profile of the casting roll casting surface during casting; A cylinder configured to minimize heat transfer from the expansion ring to the casting rolls during casting by a thermal insulation coating and to regulate expansion of the expansion ring and thus the cylindrical tube by providing channels therein through which water can flow. at least two expansion rings positioned adjacent within the shaped tube and spaced within 450 mm inwardly from the cast strip edges formed at the opposite ends of the casting rolls during the casting operation;
c. a metal feed system capable of forming a casting pool positioned above the nip and supported on the casting surfaces of the casting rolls by side dams defining the casting pool adjacent the ends of the nip.

The apparatus may further comprise at least one sensor positioned downstream of the nip and capable of detecting the cast strip thickness profile and generating an electrical signal indicative of the cast strip thickness profile, the electrical signal received from the sensor being Control the roll crown of the casting roll casting surface during the casting operation by varying the radial dimension of the expansion ring in response to .

Furthermore, the continuous thin strip casting apparatus with roll crown control comprises an electrical sensor receiving the radial dimension of the thermally coated expansion ring while controlling the casting roll drive to vary the rotational speed of the casting rolls. It may consist of a control system that can be changed in response to a signal to control the roll crown of the casting surface of the casting rolls during the casting operation.

In addition, the continuous thin strip casting apparatus for controlling roll crown further comprises at least one expansion ring positioned within the cylindrical tube at a location corresponding to the center of the cast strip formed on the casting roll during casting. The at least one expansion ring may have at least one heating element and may be thermally insulated to increase the radial dimension to cause expansion of the cylindrical tube to the casting surface crown and the casting roll during casting. It is configured to change the cast strip thickness profile. Furthermore, the roll crown controlled thin strip continuous caster controls the casting roll drive to vary the rotational speed of the casting rolls while controlling the cast strip edge in response to electrical signals received from the at least one sensor. It may further comprise a control system capable of altering the radial dimension of the expansion ring spaced apart from and the radial dimension of the expansion ring corresponding to the casting strip center to alter the roll crown of the casting roll casting surface during the casting operation.

Alternatively, a thin strip continuous casting device that controls the roll crown is
a. A pair of counter-rotating casting rolls with a nip between them and capable of feeding cast strip downwardly through the nip, each casting roll having a casting surface of less than 80 mm in thickness and made of copper or a copper alloy. a pair of casting rolls formed of a cylindrical tube made of a material selected from the group and having a plurality of longitudinal water channels extending therein;
b. having at least one heating element and a thermal insulation coating, configured to alter the crown of the casting surface and the cast strip thickness profile during casting by causing expansion of the cylindrical tube with an increase in radial dimension; a cylindrical tube configured to minimize heat transfer from the expansion ring to the casting rolls during casting and to regulate the expansion of the expansion ring and thus the cylindrical tube by providing channels therein through which water can flow; , at least one expansion ring positioned to correspond to the central portion of the cast strip formed against the casting rolls during the casting operation;
c. and a metal feed system capable of forming a casting pool supported on the casting surfaces of the casting rolls by side dams positioned above the nip and defining the casting pool adjacent the ends of the nip. .

The apparatus may further comprise at least one sensor positioned downstream of the nip for detecting the cast strip thickness profile and generating an electrical signal indicative of the cast strip thickness profile, the electrical signal received from the at least one sensor. Control the roll crown of the casting roll casting surface during the casting operation by controlling the radial dimension of the expansion ring as a function of .

Further, the roll crown controlled continuous thin strip casting apparatus controls the casting roll drive to vary the rotational speed of the casting rolls while measuring the radial dimension of the thermally insulated expansion ring with the at least one sensor. A control system that can be modified in response to electrical signals received from the casting roll to control the roll crown of the casting surfaces of the casting rolls during the casting operation.

In addition, a continuous thin strip casting apparatus for controlling roll crown is adjacent within the cylindrical tube and spaced at least within 450 mm inwardly from the cast strip edges formed at the opposite ends of the casting rolls during the casting operation. It may further consist of two expansion rings. Each expansion ring has at least one heating element and is thermally insulated. The thermally coated expansion ring is configured to change the roll crown and cast strip thickness profile of the casting roll casting surface during the casting operation by increasing the radial dimension to cause expansion of the cylindrical tube. there is

Furthermore, the roll crown control thin strip continuous casting apparatus controls the casting roll driving apparatus to change the rotation speed of the casting rolls, and expands the center of the cast strip according to the electrical signal received from the sensor. It may further comprise a control system capable of varying the radial dimension of the ring and the radial dimension of the expansion ring spaced from the casting strip edge to control the roll crown of the casting roll casting surface during the casting operation. .

In each embodiment of the device, the expansion ring may be made of austenitic stainless steel, such as 18/8 austenitic stainless steel. Each expansion ring may have an annular dimension of 50-150 mm (eg 70 mm). Each expansion ring may have a width of up to 200 mm (eg 83.5 mm).

In each embodiment of the apparatus, each thermally coated expansion ring increases in radial dimension to cause expansion of the cylindrical tube, altering the casting roll casting surface crown and cast strip thickness profile during casting. is configured as follows. Each expansion ring has at least one heating element, which can be made of stainless steel, nickel, or nickel alloys, and can be positioned about each expansion ring as desired. Each expansion ring can provide a heat input of up to 30 kW, preferably at least 3 kW.

Again, in each embodiment of the apparatus, at least one sensor can be positioned downstream that can detect the cast strip thickness profile and generate an electrical signal indicative of the cast strip thickness profile. The sensor may be located adjacent pinch rolls through which the strip passes after casting.

Crown control of the casting roll casting surface can be achieved by controlling the radial dimension of each expansion ring in response to electrical signals received from sensors. In addition, the crown control of the casting roll casting surfaces controls the casting roll drives to vary the rotational speed of the casting rolls while also controlling the radial dimension of each thermally coated expansion ring from sensors. It can be achieved by changing according to the signal.

The radial dimensions of the expansion rings adjacent the strip edges formed on the casting roll casting surface can be controlled independently of each other. In addition, the radial dimension of the expansion rings adjacent the strip edges formed on the casting roll casting surfaces can be controlled independently of the expansion rings corresponding to the casting strip center.

Again, in embodiments of the method and apparatus, the thermal insulation coating on the expansion ring is sufficiently thick that only a small amount of heat is transferred to the cylindrical tube to cause the expansion ring to expand upon heating to reduce the crown of the casting rolls during the casting operation. The shape can be controlled as desired. A thermal barrier coating that is at least 0.010 inches (eg, 0.025 inches) thick is effective. The thermal barrier coating can also be applied to the cylindrical tube, but for economy and effectiveness the thermal barrier coating should be applied directly to the expansion ring during assembly of the expansion ring and casting rolls.

In each of these embodiments of the method and apparatus, channels may also be provided within the expansion ring to channel water through the channels of the ring and regulate water flow through these channels. The flow of water through the expansion ring can be adjusted to expand or contract the radial dimension of the expansion ring, thus increasing or decreasing the diameter of the cylindrical tube as desired to control the crown shape of the casting roll casting surface during operation. can.

Various aspects of the present invention will become apparent to those skilled in the art from the following detailed description, drawings and claims.

1 is a schematic side view of a twin roll caster of the present disclosure; FIG. 2 is an enlarged partial cross-sectional view of a portion of the twin roll caster of FIG. 1, including strip inspection equipment for strip profile measurement; FIG. 3 is a schematic diagram of a portion of the twin roll caster of FIG. 2; FIG. FIG. 3 is a cross-sectional view of a longitudinal portion of one of the casting rolls of FIG. 2 with expansion rings corresponding to the center of the cast strip; 3B is a longitudinal cross-sectional view of the remainder of the casting roll of FIG. 3A, joined by line AA; FIG. FIG. 4 is an end view along line 4-4 of the casting roll of FIG. 3A showing partial internal details in phantom; 5 is a cross-sectional view of the casting roll of FIG. 3A along line 5-5; FIG. 6 is a cross-sectional view of the casting roll of FIG. 3A taken along line 6-6; FIG. 7 is a cross-sectional view of the casting roll of FIG. 3A along line 7-7; FIG. Figure 3 is a cross-sectional view of a longitudinal portion of one of the casting rolls of Figure 2 with two expansion rings spaced from the ends of the casting strip; FIG. 4 is a cross-sectional view of a longitudinal portion of a casting roll with expansion rings spaced from the ends of the casting strip; Figure 3 is a cross-sectional view of one longitudinal section of the casting roll of Figure 2 with two expansion rings spaced from the ends of the casting strip and a corresponding expansion ring at the center of the casting strip; FIG. 10 is a cross-sectional view of an expansion ring with channels; Fig. 3 is a comparative graph of delta RTD temperature versus time; FIG. 5 is a graph comparing average expansion ring temperature and edge drop; FIG. Fig. 3 is a graph comparing expansion of a heated ring and temperature inside a caster; FIG. 3 is a side cross-sectional view of an expansion ring with heating elements;

The invention will be described in more detail with reference to the accompanying drawings.

With reference to FIGS. 1, 2 and 2A, the main machine frame 10 comprising the illustrated twin roll caster rises from the factory floor and carries a pair of counter-rotatable casting rolls 12 modularly mounted in roll cassettes 11 . To support. The attachment of the casting rolls 12 to the roll cassette 11 is for ease of operation and movement as described below. The roll cassette 11 facilitates the rapid movement together of the casting rolls 12 prepared for casting from the set position to the casting operating position in the casting machine, and the casting rolls 12 to the casting position when the casting rolls 12 are replaced. is to be removed quickly from The roll cassette 11 does not have any particular configuration that is desired, it need only serve the function of facilitating the movement and placement of the casting rolls 12 as described herein.

A pair of counter-rotatable casting rolls 12 included in a casting apparatus for continuously casting thin steel strip have casting surfaces 12A that are laterally disposed to form a roll nip 18 therebetween. Molten metal is fed from the ladle 13 through a metal feed system to a metal feed nozzle 17 (core nozzle) located between the casting rolls 12 above the roll nip 18 . The molten metal thus fed forms a casting pool 19 of molten metal supported on the casting surfaces 12A of the casting rolls 12 above the nip 18. As shown in FIG. Enclosing this casting pool 19 in the casting zone at the ends of the casting rolls 12 are a pair of side closure plates or dams 20 (shown in dashed lines in FIG. 2A). The upper surface of casting pool 19 (commonly referred to as the “meniscus” level) may be above the lower end of metal feed nozzle 17 so that the lower end of metal feed nozzle 17 is submerged within casting pool 19 . The casting zone includes the addition of a protective atmosphere above the casting pool 19 to inhibit oxidation of the molten metal in the casting zone.

The ladle 13 is of conventional construction, generally supported on a rotating turret 40 . For metal feeding, ladle 13 is placed above movable tundish 14 in casting position to fill movable tundish 14 with molten metal. A tundish car 66 on which the movable tundish 14 may be positioned can transport the movable tundish 14 from a heating station (not shown) that heats the movable tundish 14 to about the casting temperature to the casting position. A tundish guide, such as a rail 39, can be positioned below the tundish car 66 to move the movable tundish 14 from the heating station to the casting position.

Movable tundish 14 is fitted with a servomechanically actuable slide gate 25 to allow molten metal to flow from movable tundish 14 through slide gate 25 and through refractory outlet shroud 15 to distributor 16. be able to. From distributor 16 the molten metal flows to metal feed nozzles 17 positioned between casting rolls 12 above nip 18 .

The side dams 20 may be made of a refractory material such as zirconia-graphite, alumina-graphite, boron nitride, boron nitride-zirconia, or any suitable composite. The side dams 20 have face surfaces that are physically contactable with the molten metal of the casting rolls 12 and casting pool 19 . A side dam holder (not shown) to which the side dam 20 is mounted is movable by a side dam actuator (not shown), such as a hydraulic or pneumatic cylinder, servomechanism or other actuator, to move the side dam 20 to the casting roll. 12 ends can be engaged. Additionally, the side dam actuator can position the side dam 20 during casting. The side dams 20 form end closures for the molten pool of metal on the casting rolls 12 during the casting operation.

A cast strip 21 produced by the twin roll caster shown in FIG. 1 passes through a guide table 30 to a pinch roll stand 31 comprising pinch rolls 31A. The cast strip 21 coming out of the pinch roll stand 31 is composed of a pair of work rolls 32A and a backup roll 32B, and forms a gap for hot rolling the cast strip 21 fed from the casting rolls 12 to roll the cast strip 21. The strip surface and strip flatness can be improved by passing through a hot rolling mill 32 where the hot rolling reduces to the desired thickness. Work roll 32A has a work surface associated with the desired strip profile across the work roll. The hot rolled cast strip 21 then passes over the runout table 33 where it is cooled by contact with a coolant such as water supplied via water jets 90 or other suitable means and by convection and heat dissipation. obtain. In any event, the hot rolled cast strip 21 can then be passed through a second pinch roll stand 91 to tension the cast strip 21 and then to a coiler 92 . The thickness of the cast strip 21 before hot rolling may be between about 0.3 and 2.0 mm.

Short lengths of imperfect strip usually occur at the start of a casting operation until casting conditions stabilize. After continuous casting has been established, the casting rolls 12 are pulled apart slightly and then brought together again to cause this leading edge cut of the cast strip 21 to form a clean head end of the next cast strip 21 . Defective material falls onto a scrap receptacle guide onto a movable scrap receptacle 26 . A scrap container 26 is located in a scrap receiving position below the casting machine and forms part of a sealed enclosure 27 as described below. Normally, the sealing portion 27 is water-cooled. At this time, the water cooling apron 28, which normally depends from the pivot 29 to one side of the seal 27, is pivoted to guide the clean end of the casting strip 21 to the guide table 30 and feed it to the pinch roll stand 31. reach the position. The water cooling apron 28 is then pulled back to a hanging position, allowing the casting strip 21 to hang in a loop within the seal 27 below the casting rolls 12 and onto the guide table 30 where it engages a series of guide rollers. match.

An overflow container 38 is provided below the movable tundish 14 and can receive molten material that may overflow the movable tundish 14 . As shown in FIG. 1, the overflow vessel 38 is movable on guides such as rails 39 and can be positioned below the movable tundish 14 as desired in the casting position. Additionally, an additional overflow container (not shown) may be positioned adjacent distributor 16 for distributor 16 .

The sealed enclosure 27 is constructed by joining a plurality of separate wall sections at various seal connections to form a continuous sealing wall that allows for atmospheric control within the enclosure 27 . In addition, the scrap container 26 can be attached to the seal 27 so that the seal 27 can support a protective atmosphere just below the casting rolls 12 in the casting position. The seal 27 includes an opening in a seal lower portion 44, which is the bottom of the seal 27, to provide an outlet for scrap from the seal 27 into the scrap container 26 in the scrap receiving position. The lower seal portion 44 can extend downwardly as part of the seal portion 27 with the opening positioned above the scrap receptacle 26 in the scrap receiving position. "seal", "sealed", "sealing" and "seals" as used herein and in the claims with respect to scrap container 26, seal 27 and related features. "sealingly" is not a perfect seal that prevents leakage, but usually includes some acceptable leakage, less than a perfect seal, as appropriate to control and maintain the atmosphere within the seal 27 as desired. It is a seal that can

A rim portion 45 can surround the opening of the lower seal portion 44 and can be movably positioned above the scrap container 26 and can be sealingly engaged and/or attached to the scrap container 26 in the scrap receiving position. Rim portion 45 may be movable between a sealing position in which rim portion 45 engages scrap container 26 and a retracted position in which rim portion 45 is disengaged from scrap container 26 . Alternatively, the caster or scrap container 26 may include a lift mechanism to lift the scrap container 26 into sealing engagement with the rim portion 45 of the seal 27 and then lower the scrap container 26 to the retracted position. During sealing, seal 27 and scrap container 26 are flooded with a desired gas, such as nitrogen, to reduce the amount of oxygen in seal 27 and provide a protective atmosphere for cast strip 21 .

Seal 27 may include an upper collar portion 43 that supports a protective atmosphere beneath casting rolls 12 in the casting position. When the casting rolls 12 are in the casting position, the upper collar portion 43 is moved to its extended position as shown in FIG. . The upper collar portion 43 may be provided within or adjacent the seal 27 and adjacent the casting rolls 12 and may include a plurality of actuators such as servomechanisms, hydraulic mechanisms, pneumatic mechanisms and rotary actuators (see FIG. 1). not shown).

The casting rolls 12 are internally water cooled as described below so that as the casting rolls 12 rotate in opposite directions, the casting surfaces 12A contact and pass through the casting pool 19 with each revolution of the casting rolls 12. So the shell solidifies on the casting surface 12A. The shells meet together at the nip 18 of the casting rolls 12 to produce a cast strip 21 that is fed downwardly from the nip 18 . A casting strip 21 is formed from the shell in the nip 18 between the casting rolls 12 and is fed downward and moved downstream as described below.

3A-10, each casting roll 12 includes a cylindrical tube 120 made of a metal selected from the group consisting of copper and copper alloys and coated with a metal or metal alloy such as chromium or nickel. is optionally applied to form casting surface 12A. Each cylindrical tube 120 can be mounted between a pair of stub shaft assemblies 121,122. Stub shaft assemblies 121 and 122 have ends 127 and 128 (shown in FIGS. 4-6), respectively, which fit snugly over the ends of cylindrical tube 120 to form casting roll 12 . Cylindrical tube 120 is thus supported by ends 127 and 128 having flange portions 129 and 130 respectively to form an internal cavity 163 to support the assembled casting rolls between stub shaft assemblies 121 and 122 .

The cylindrical outer surface of each cylindrical tube 120 is the roll casting surface 12A. The radial thickness of cylindrical tube 120 may be 80 mm or less, and may be 40-80 mm or 60-80 mm.

A series of longitudinal channels 126 provided in each cylindrical tube 120 can be formed by drilling long holes through the circumferential thickness of the cylindrical tube 120 from one end to the other. The ends of the holes are later closed by end plugs 141 which are attached by fasteners 171 to the ends 127,128 of the stub shaft assemblies 121,122. Channel 126 is formed in the thickness of cylindrical tube 120 with end plugs 141 . The number of stub shaft fasteners 171 and end plugs 141 can be selected as desired. The provision of end plugs 141 can provide single pass cooling or multi-pass cooling from one end of casting roll 12 to the other with channels in the stub shaft assembly described below, where multi-pass cooling includes, for example, channel 126 After being connected together to provide three passes of cooling water through adjacent channels 126, the water is returned to the water supply either directly or via cavity 163. FIG.

A waterway 126 through the thickness of cylindrical tube 120 can be connected to a water supply in series with cavity 163 . Since channel 126 can be connected to a water supply, the cooling water can either flow first through cavity 163 and then through channel 126 to the return line, or first through channel 126 and then through cavity 163 to the return line. reach.

The end of the cylindrical tube 120 may be provided with a circumferential step 123 to form a shoulder 124 between it and the working portion of the roll casting surface 12A of the casting roll 12 . A shoulder 124 is provided to engage the side dam 20 to enclose the casting pool 19 during casting operations as described above.

Ends 127, 128 of stub shaft assemblies 121, 122, respectively, generally sealingly engage the ends of cylindrical tube 120 and have radially extending channels 135, 136, shown in FIGS. A channel 126 is fed through the cylindrical tube 120 . Radial channels 135, 136 are connected to the ends of at least some of the channels 126, for example in a threaded arrangement, depending on whether the cooling is a single pass or a multi-pass cooling system. If the water cooling is a multi-pass system, the remaining ends of the channels 126 can be closed, for example by threading end plugs 141 as described.

As shown in detail in FIG. 7, the cylindrical tubes 120 may be arranged in an annular array through the thickness of the cylindrical tubes 120 in a single pass or multi-pass array of channels 126 as desired. Channel 126 is connected to annular gallery 140 by radial port 160 at one end of casting roll 12 and, in turn, to radial channel 135 at end 127 of stub shaft assembly 121, and to annular gallery 140 by radial port 161 at the other end of casting roll 12. 150 and thus to the radial flow passage 136 at the end 128 of the stub shaft assembly 121 . Water fed through one annular gallery 140 or 150 at one end of the roll 12 flows in parallel through all of the channels 126 in a single pass to the other end of the roll 12 and at the other end of the cylindrical tube 120 . It can exit via radial channels 135 or 136 and the other annular gallery 150 or 140 . Directional flow can be reversed as desired by appropriate connections in the supply and return lines. Alternatively or additionally, a multi-pass configuration, such as a three-pass configuration, can be provided by optionally connecting or optionally blocking selected ones of the waterways 126 to or from the radial paths 135,136.

Stub shaft assembly 122 may be longer than stub shaft assembly 121 . As shown in FIG. 3B, stub shaft assembly 122 may include two sets of water flow ports 133,134. Water is delivered axially to and from the casting rolls 12 through the stub shaft assembly 122 by rotary water flow couplings 131 and 132 which are connectable with water flow ports 133 and 134 . In operation, cooling water flows into and out of channel 126 of cylindrical tube 120 via radial channels 135, 136 extending through ends 127, 128 of stub shaft assemblies 121, 122, respectively. Stub shaft assembly 121 is mated with axial tube 137 to provide fluid communication between radial passage 135 at end 127 and a central cavity within casting roll 12 . The stub shaft assembly 122 is fitted with an axial space tube to have a central water conduit 138 in fluid communication with the central cavity 163 and an annular water conduit 139 in fluid communication with the radial passages 136 at the ends 122 of the stub shaft assembly 122 . To separate. A central water conduit 138 and an annular water conduit 139 can provide cooling water flow to and from the casting rolls 12 .

In operation, incoming cooling water may be supplied from supply line 131 to annular water conduit 139 via water flow ports 133 in fluid communication with radial passages 136, annular gallery 150 and water passage 126, then annular gallery 140, It is returned via radial passage 135 , axial tube 137 , central cavity 163 and central water conduit 138 to outlet line 132 via water flow port 134 . Alternatively, the flow of water into, out of and through the casting rolls 12 may be reversed if desired. The water flow ports 133, 134 can be connected to water supply and return lines to flow in and out of the water passages 126 of the cylindrical tubes 120 of the casting rolls 12 in either direction as desired. Depending on the direction of flow, the cooling water flows through cavity 163 before or after it flows through channel 126 .

Each cylindrical tube 120 may have at least one expansion ring with a thermal insulation coating. As shown in FIG. 8, each of the cylindrical tubes 120 is provided with a thermal insulation coating 350 and at least one thermal insulation coating 350 is applied to opposite ends of the cylindrical tubes 120 and spaced within 450 mm inside the ends of the cast strip formed in the casting operation. Two expansion rings 210 may be provided. FIG. 9 is a cross-sectional view of a longitudinal portion of a casting roll with an insulating coating 350 and an expansion ring 210 spaced from the casting strip edge and having heating elements 370 .

Alternatively, as shown in FIG. 10, at least two expansion rings 210 with thermal insulation coating 350 are placed on opposite ends of cylindrical tube 120 inwardly from the ends of the cast strip at the opposite ends of the casting rolls in the casting operation. An additional expansion ring 220 spaced to within 450 mm to the left and provided with a thermal insulation coating 330 is positioned within the cylindrical tube 120 at a location corresponding to the center of the cast strip formed on the casting surface during casting.

In another modification, as shown in FIG. 3A, an expansion ring 220 with a thermal insulation coating 330 is placed within the cylindrical tube 120 at a location corresponding to the center of the cast strip formed on the casting surface of the casting roll during casting. can be placed in

As shown in FIGS. 8-10, the thermally coated expansion ring can be positioned adjacent within the cylindrical tube and spaced from the cast strip edge. Each expansion ring may have an annular dimension of 50-150 mm (eg 70 mm). Similarly, the expansion ring, which is thermally coated and positioned corresponding to the central portion of the cast strip formed during casting, may have an annular dimension of 50-150 mm (eg 70 mm).

Each expansion ring, which is thermally coated and spaced from the cast strip edge, can have a width of up to 200 mm (eg, 83.5 mm). Similarly, the expansion ring, which is thermally coated and placed in the middle of the cast strip at the time of casting, can have a width of up to 200 mm (eg 83.5 mm).

The deformation of the crown of the casting roll casting surface can be controlled by adjusting the radial dimension of at least one expansion ring located inside the cylindrical tube. The radial dimension of the at least one thermally coated expansion ring can be controlled by adjusting the temperature of the expansion ring. The cast strip thickness profile can then be controlled by the radius of the expansion ring and thus the crown of the casting surface of the casting roll. The circumferential thickness of the cylindrical tube is made less than 80 mm so that the crown of the casting surface can deform in response to changes in the radial dimension of the expansion ring.

Each thermally coated expansion ring is configured to increase in radial dimension to cause expansion of the cylindrical tube, thereby altering the crown of the casting surface and the cast strip thickness profile during casting. Power wires 222 and control wires 224 extend from slip ring 240 to each expansion ring. A power wire 222 supplies power to the expansion ring. A control wire 224 provides temperature feedback, which is used for power control of the expansion ring.

As shown in FIG. 11, each expansion ring may have channels 340 through which water can flow. The water flow can be controlled to adjust the expansion of the expansion ring.

Each expansion ring can be electrically heated to increase its radial dimension. As shown in FIG. 15, each expansion ring can have at least one heating element positioned as desired to effectively heat the ring. The expansion ring 300 has for that purpose a heating element 310 on the right side and a heating element 320 on the left side. Each expansion ring can provide up to 30 kW of heat input, preferably at least 3 kW of heat input. The force resulting from the radial dimensional increase is applied to the cylindrical tube causing expansion of the cylindrical tube, altering the crown of the casting surface and the cast strip thickness profile. In order to achieve the desired thickness profile by controlling the radial dimension of the expansion ring and controlling the casting speed, a strip thickness profile sensor 71 is positioned downstream to control the thickness profile of the cast strip 21 as shown in FIGS. 2 and 2A. can be detected. For direct control of casting rolls 12, sensor 71 is normally provided between roll nip 18 and pinch rolls 31A. This sensor may be any suitable device, such as an X-ray instrument, capable of directly measuring the thickness profile across the width of the strip periodically or continuously. Alternatively, a plurality of non-contact sensors may be arranged laterally of the cast strip 21 on the guide table 30, and a combination of thickness measurements from multiple locations laterally of the cast strip 21 may be processed by the controller 72 to obtain a strip thickness profile. is determined periodically or continuously. The thickness profile of cast strip 21 can be determined from this data periodically or continuously as desired.

The radial dimension of each expansion ring can be controlled independently of the radial dimensions of the other expansion rings. The radial dimension of each thermally coated expansion ring adjacent and inboard of the strip ends of the casting rolls can be controlled independently of each other. Alternatively, the radial dimension of the expansion ring adjacent the inside of the strip end of the casting roll can be thermally coated and controlled independently of the expansion ring corresponding to the center of the cast strip. Sensor 71 produces a signal indicative of the cast strip thickness profile. The radial dimension of each thermally coated expansion ring is controlled according to signals emitted by the sensors, which control the roll crown of the casting roll casting surface during the casting operation.

Furthermore, while the casting roll drive is controlled to vary the rotational speed of the casting rolls, the radial dimension of the expansion ring can also be varied in response to electrical signals received from sensor 71, thereby changing the speed of the casting roll during the casting operation. Control the roll crown of the casting roll casting surface.

It has been found that a thermal barrier coating is necessary to control heat transfer from the expansion ring to the casting rolls. Tests conducted have shown that when the thermal barrier coating is applied, there is minimal heat transfer from the expansion ring to the casting rolls during casting, allowing the expansion ring to achieve the desired temperature and expansion, and thus the desired cross-section. The strip thickness profile can be reached to control the crown of the casting surface commercially.

For illustrative purposes, FIG. 12 shows tests performed with and without the thermal insulation coating on the expansion ring. A thermal barrier coating of zirconia stabilized with 8% yttria was plasma sprayed onto the outside of the expansion ring to give a thermal barrier coating thickness of 0.025 inch. Each expansion ring had an approximately 85 mm wide casting roll section that was shrink fit into the expansion ring. Channels were provided within each casting roll section. Water was supplied at approximately 15 lb-in and the water flow varied between 8.6 and 8.9 gallons per minute. Inlet water temperature was 68°F. Separate tests were run at 50% power and 100% power. As shown in FIG. 12, the expansion ring ended up with a peak delta temperature of 54° C. when tested at 50% power. On the other hand, the thermally coated expansion ring resulted in a peak delta temperature of 90°C, a 67% increase in peak delta temperature. As shown in FIG. 12, the test failed to heat the uncoated expansion ring at 100% power, while the thermally coated expansion ring at 100% power reached a peak delta temperature of approximately 130°C. finished.

FIG. 13 shows a graph comparing average expansion ring temperature and edge drop. Edge drop correlates to cast strip thickness. As shown in FIG. 13, the edge drop appears to respond to each temperature change of each heated expansion ring. As the temperature increases, the expansion ring expands, reducing the cast strip thickness at the casting roll edges and increasing the edge drop.

FIG. 14 shows a graph comparing the expansion of a heated ring and the temperature of an expansion ring covered with a thermal insulation coating. The expansion ring was placed adjacent to the casting rolls in a normal casting operation and had a channel therein through which water flowed. The coated expansion ring was heated from 85.6°F to 120°F, held briefly at 120°F, and then heated to 160-200°F. As demonstrated, dimensional expansion of greater than 100 μm was achieved when the coated expansion ring was heated to 115°F. As explained, with an uncoated expansion ring it would not be possible to obtain these results due to heat transfer to the casting rolls. The expansion of the expansion ring is directly correlated with the temperature to which the expansion ring can be heated. As described, an expansion ring coated with a thermal barrier can heat up rapidly to achieve high effective temperatures. Therefore, a thermal barrier coating of at least 0.010 inch (eg, 0.025 inch) thickness is essential to control or eliminate heat transfer from the expansion ring to the casting rolls.

In each of these embodiments of the method and apparatus, channels are also provided within the expansion ring to allow water to flow through the channels within the ring and to regulate water flow through these channels. The water flow is adjusted to increase or decrease the diameter of the expansion ring and thus the cylindrical tube as desired to control the shape of the casting roll during operation.

Although the principle and operation have been described and illustrated with reference to specific embodiments, it is to be understood that the invention may be practiced otherwise than as specifically described and illustrated without departing from its scope.

12 Casting Roll 12A Roll Casting Surface 14 Movable Tundish 15 Refractory Exit Shroud 16 Distributor 17 Metal Feed Nozzle 18 Roll Gap 20 Side Weir 21 Casting Strip 71 Profile Sensor 120 Cylindrical Tube 126 Channel 127 End 210 Expansion Ring 220 Expansion Ring 300 expansion ring 310 heating element 320 heating element 330 thermal insulation coating 340 channel 350 thermal insulation coating 370 heating element

Claims (39)

a. A pair of counter-rotating casting rolls with a nip between them so that the cast strip can be fed downwardly through the nip, each casting roll having a casting surface of 80 mm or less in thickness and made of copper or a copper alloy. assembling a caster formed by a cylindrical tube made of a material selected from the group and having a plurality of longitudinal water passages extending therein;
b. At least two expansion rings are positioned adjacent within the cylindrical tube within 450 mm inwardly from the cast strip edge formed at the opposite ends of the casting rolls during the casting operation, each expansion ring being made of stainless steel, nickel or having at least one heating element made of a nickel alloy and in direct contact with the expansion rings, each expansion ring having a thermal insulation coating, each expansion ring being a cylindrical tube of increasing radial dimension due to increasing radial dimension; The thermal insulation coating minimizes heat transfer from the expansion ring to the casting rolls during casting, and the configured to regulate the expansion of the expansion ring and thus the cylindrical tube by providing a flowable channel within each expansion ring;
c. assembling a metal feed system capable of forming a casting pool supported on the casting surfaces of the casting rolls above the nip by side dams defining the casting pool adjacent the ends of the nip;
d. A roll crown comprising controlling the roll crown of a casting roll casting surface during a casting operation by controlling the radial dimension of an expansion ring in response to at least one of digital or analog signals received from at least one sensor. Controlled thin strip continuous casting method. e. capable of detecting at least one of the following characteristics,
temperature of the expansion ring,
downstream casting strip thickness profile,
the local thickness of the cast strip at a defined point close to the cast strip edge;
casting roll surface crown during casting operation and radial casting roll expansion at a defined point close to the casting strip edge;
and further comprising arranging at least one sensor capable of emitting a digital or analog signal indicative of at least one of said properties of the cast strip. f. Further comprising disposing at least one expansion ring within the cylindrical tube corresponding to the center of the cast strip formed on the casting roll during casting, each expansion ring being made of stainless steel, nickel or a nickel alloy. having at least one heating element in direct contact with the expansion rings, each expansion ring having a thermal insulation coating, each expansion ring causing expansion of the cylindrical tube by increasing its radial dimension to cause expansion of the cylindrical tube during casting; A thermal barrier coating configured to modify the crown of the casting surface and the cast strip thickness profile, minimizing heat transfer from the expansion ring to the casting rolls during casting, and providing channels in each expansion ring through which water can flow. 3. A method of continuously casting thin strip with roll crown control according to claim 1 or claim 2, adapted to regulate the expansion of the expansion ring and thus of the cylindrical tube. g. Controlling the casting roll drive to vary the rotational speed of the casting rolls while varying the radial dimension of the thermally insulated expansion ring in response to at least one of the digital or analog signals received from the at least one sensor. 3. The method of continuously casting thin strip with roll crown control according to claim 2, further comprising: modifying and controlling the roll crown of the casting surface of the casting rolls during the casting operation. h. The radial dimension of the thermally insulated expansion rings and the radial dimension of each thermally insulated expansion ring corresponding to the central portion of the cast strip, while controlling the casting roll drive to vary the rotational speed of the casting rolls. 4. The roll of claim 3, further comprising changing dimensions in response to at least one of digital or analog signals received from the at least one sensor to control roll crown of the casting surface of the casting roll during the casting operation. Thin strip continuous casting method with crown control. A method for continuously casting thin strip with roll crown control according to any one of claims 1 to 5 , wherein each expansion ring with thermal insulation coating has an annular dimension of 50-150 mm. A method of continuously casting thin strip with roll crown control according to any one of claims 1 to 5 , wherein each expansion ring is provided with an insulating coating and has a width of up to 200 mm. A thin film with roll crown control according to any one of claims 1 to 7 , wherein the roll crown of the casting surface of the casting roll can be controlled by independently controlling the radial dimension of each expansion ring, which is provided with a thermal insulation coating. Strip continuous casting method. i. further comprising varying the radial dimension of the expansion ring while varying the horizontal distance between the axial centerlines of the casting rolls by controlling the position of the casting rolls, each thermally coated expansion ring comprising: controlling the roll crown of the casting surface of the casting roll during the casting operation in response to at least one of the digital or analog signals received from the at least one sensor in response to at least one characteristic at the center or edge of the casting strip; A thin strip continuous casting method by roll crown control according to claim 3. A method for continuously casting thin strip with roll crown control according to any one of claims 1 to 9 , wherein the casting surface of each casting roll is coated with a metal or metal alloy. a. A pair of counter-rotating casting rolls with a nip between them so that the cast strip can be fed downwardly through the nip, each casting roll having a casting surface having a thickness of 80 mm or less and made of copper or a copper alloy. assembling a caster formed by a cylindrical tube made of a material selected from the group and having a plurality of longitudinal water passages extending therein;
b. At least one expansion ring is positioned within the cylindrical tube in correspondence with the central portion of the cast strip formed against the casting rolls during the casting operation, each expansion ring being made of stainless steel, nickel or a nickel alloy for expansion. It has at least one heating element in direct contact with the rings, each expansion ring having a thermal insulation coating, each expansion ring causing expansion of the cylindrical tube by increasing its radial dimension, thereby improving the casting surface during casting. The expansion ring is configured to vary the crown and cast strip thickness profile, the thermal insulation coating minimizes heat transfer from the expansion ring to the casting rolls during casting, and the expansion ring is provided with channels within each expansion ring through which water can flow. Finally, it is configured to adjust the expansion of the cylindrical tube,
c. assembling a metal feed system capable of forming a casting pool supported on the casting surfaces of the casting rolls above the nip with side dams defining the casting pool adjacent the ends of the nip;
d. Roll crown of the casting surface of the casting roll during casting operations by controlling the radial dimension of the at least one thermally coated expansion ring in response to at least one digital or analog signal received from at least one sensor. A thin strip continuous casting method by roll crown control, which consists of controlling the e. capable of detecting at least one of the following characteristics,
temperature of the at least one expansion ring;
downstream cast strip thickness profile;
the local thickness of the cast strip at a defined point close to the cast strip edge,
casting roll surface crown during casting operation,
radial casting roll expansion at a defined point close to the casting strip edge,
Continuous casting of thin strip with roll crown control according to claim 11 , further comprising arranging at least one sensor capable of emitting a digital or analog signal indicative of at least one of the above-mentioned properties of the cast strip. Method. f. changing the radial dimension of the at least one thermally insulated expansion ring while controlling the casting roll drive to change the rotational speed of the casting rolls; 13. The method of continuously casting thin strip with roll crown control according to claim 11 or claim 12 , further comprising controlling the roll crown of the casting roll casting surface during the casting operation according to at least one. A method for continuously casting thin strip with roll crown control according to any one of claims 11 to 13 , wherein at least one thermally coated expansion ring has an annular dimension of 50 to 150 mm. A method for the continuous casting of thin strip with roll crown control according to any one of claims 11 to 13 , wherein at least one thermally coated expansion ring has a width of up to 200 mm. Roll crown according to any one of claims 11 to 15 , wherein the roll crown of the casting surface of the casting rolls can be controlled by independently controlling each expansion ring provided with a thermal insulation coating and corresponding to the casting strip center. Controlled thin strip continuous casting method. g. varying the radial dimension of the at least one expansion ring while varying the horizontal distance between the axial centerlines of the casting rolls by controlling the position of the casting rolls; an expansion ring controlling the roll crown of the casting surface of the casting roll during the casting operation in response to at least one of the digital or analog signals received from the at least one sensor in response to at least one property in the central portion of the casting strip; A method for continuously casting thin strip with roll crown control according to any one of claims 11 to 16 . A method for continuously casting thin strip with roll crown control according to any one of claims 11 to 17 , wherein the casting surface of each casting roll is coated with a metal or metal alloy. a. A pair of counter-rotating casting rolls with a nip therebetween and capable of feeding cast strip downwardly through the nip, each casting roll having a casting surface having a thickness of 80 mm or less and made of copper and copper alloys. a pair of casting rolls formed of a cylindrical tube made of a material selected from the group consisting of:
b. It has at least one heating element made of stainless steel, nickel or nickel alloy and in direct contact with the expansion ring and has a thermal insulation coating to cause expansion of the cylindrical tube by increasing its radial dimension during casting. A casting roll configured to alter the roll crown and cast strip thickness profile of the casting surface of the casting roll, a thermal insulation coating to minimize heat transfer from the expansion ring to the casting roll during casting, and an internal channel through which water can flow. Within 450 mm inwardly of the cast strip edges positioned adjacent within the cylindrical tube and formed at opposite ends of the casting rolls during the casting operation, configured to regulate the expansion of the expansion ring and, in turn, the cylindrical tube. at least two expansion rings spaced apart by
c. and a metal feed system capable of forming a casting pool positioned above the nip and supported on the casting surfaces of the casting rolls by side dams defining the casting pool adjacent the ends of the nip. Thin strip continuous casting equipment. d. capable of detecting at least one of the following characteristics,
temperature of the expansion ring,
a cast strip thickness profile located downstream of the nip;
the local thickness of the cast strip at a defined point close to the cast strip edge;
casting roll surface crown during casting operation radial casting roll expansion at a defined point proximate to the casting strip edge and at least one sensor capable of producing a digital or analog signal indicative of at least one of the foregoing characteristics 20. The thin strip by roll crown control of claim 19 , wherein roll crown of a casting roll casting surface during a casting operation is controlled by controlling the radial dimension of an expansion ring in response to signals received from said at least one sensor. Continuous casting equipment. e. further comprising at least one expansion ring within the cylindrical tube corresponding to the central portion of the cast strip formed on the casting roll during the casting operation, each expansion ring being made of stainless steel, nickel or nickel alloy and directly attached to the expansion ring; It has at least one heating element in contact , each expansion ring has a thermal insulation coating, and each expansion ring causes expansion of the cylindrical tube by increasing its radial dimension, thereby reducing the crown and the roll casting surface during casting. A thermal barrier coating minimizes heat transfer from the expansion rings to the casting rolls during casting, and channels within each expansion ring through which water can flow are designed to vary the thickness profile of the expansion ring and thus the cylinder. 21. Apparatus for continuously casting thin strip with roll crown control according to claim 19 or 20 , adapted to regulate the expansion of the shaped tube. f. Casting by controlling the casting roll drive to change the rotational speed of the casting rolls while changing the radial dimension of the thermally insulated expansion ring in response to electrical signals received from the at least one sensor. 21. Apparatus for continuously casting thin strip with roll crown control according to claim 20 , further comprising a control system capable of controlling the roll crown of the casting roll casting surface during operation. Apparatus for continuously casting thin strip with roll crown control according to any one of claims 19 to 22 , wherein each expansion ring with thermal insulation coating has an annular dimension of 50 to 150 mm. Apparatus for the continuous casting of thin strip with roll crown control according to any one of claims 19 to 22 , provided with a heat insulating coating and each expansion ring having a width of up to 200 mm. A roll crown controlled thin film according to any one of claims 19 to 24 , wherein the radial dimension of each thermally coated expansion ring can be independently controlled to control the roll crown of the casting roll casting surface. Continuous strip casting equipment. Apparatus for continuously casting thin strip with roll crown control according to any one of claims 19 to 25 , wherein the casting surface of each casting roll is coated with a metal or metal alloy. a. A pair of counter-rotating casting rolls with a nip between them and capable of feeding cast strip downwardly through the nip, each casting roll having a casting surface of less than 80 mm in thickness and made of copper or a copper alloy. a pair of casting rolls formed of a cylindrical tube made of a material selected from the group and having a plurality of longitudinal water channels extending therein;
b. It has at least one heating element made of stainless steel, nickel or a nickel alloy and in direct contact with the expansion ring and has a thermal insulation coating during casting by causing expansion of the cylindrical tube with an increase in radial dimension. configured to alter the crown of the casting surface and the thickness profile of the cast strip, the thermal insulation coating to minimize heat transfer from the expansion ring to the casting rolls during casting, and the expansion ring by providing channels therein through which water can flow; at least one expansion ring within the cylindrical tube at a location corresponding to the central portion of the cast strip formed against the casting rolls during the casting operation, which in turn is configured to regulate the expansion of the cylindrical tube; ,
c. a metal feed system capable of forming a casting pool supported on the casting surfaces of the casting rolls by side dams positioned above the nip and defining the casting pool adjacent the ends of the nip;
Thin strip continuous casting equipment with roll crown control. d. capable of detecting at least one of the following characteristics,
temperature of said at least one expansion ring;
a cast strip thickness profile located downstream of the nip;
the local thickness of the cast strip at a defined point close to the center of the cast strip;
casting roll surface crown during casting operation,
radial casting roll expansion at a defined point close to the center of the cast strip;
and further comprising at least one sensor capable of emitting a digital or analog signal indicative of at least one of said characteristics, and adjusting the radial dimension of said at least one expansion ring in response to the signal received from said at least one sensor. 28. Apparatus for continuously casting thin strip with roll crown control according to claim 27 , wherein the roll crown is controlled by controlling the roll crown of the casting surface of the casting roll during the casting operation. e. during a casting operation by varying the radial dimension of said at least one expansion ring in response to electrical signals received from said at least one sensor while varying the rotational speed of the casting rolls by controlling the casting roll drive. 29. Apparatus for continuously casting thin strip with roll crown control according to claim 28 , further comprising a control system capable of varying the roll crown of the casting roll casting surface of the casting roll. Apparatus for continuously casting thin strip with roll crown control according to any one of claims 27 to 29 , wherein at least one expansion ring provided with a heat insulating coating and corresponding to the center of the cast strip has an annular dimension of 50 to 150 mm. . Apparatus for continuously casting thin strip with roll crown control according to any one of claims 27 to 29 , wherein at least one expansion ring provided with a heat insulating coating and corresponding to the center of the cast strip has a width of up to 200 mm. Roll crown control according to any one of claims 27 to 31 , wherein each thermally coated expansion ring corresponding to the casting strip center is independently controlled to control the roll crown of the casting roll casting surface. Continuous thin strip casting equipment. Apparatus for continuously casting thin strip with roll crown control according to any one of claims 27 to 32 , wherein the casting surface of each casting roll is coated with a metal or metal alloy. a. A pair of counter-rotating casting rolls with a nip between them so that the cast strip can be fed downwardly through the nip, each casting roll having a casting surface having a thickness of 80 mm or less and made of copper or a copper alloy. assembling a caster formed by a cylindrical tube made of a material selected from the group and having a plurality of longitudinal water passages extending therein;
b. At least two expansion rings each made of stainless steel, nickel or a nickel alloy and having at least one heating element in direct contact with the expansion ring and having a thermal insulation coating are formed at opposite ends of the casting rolls during the casting operation. Disposed adjacently within the cylindrical tube within a distance of 450 mm inwardly from the cast strip edge, the thermal insulation coating is applied against the cylindrical tube when the cylindrical tube is cooled in the longitudinal water passages and the heating element is activated. and the expansion ring has a thickness such that it can achieve a temperature difference that is at least 50% greater than that of a similar uncoated expansion ring under similar operating conditions;
c. assembling a metal feed system capable of forming a casting pool supported on the casting surfaces of the casting rolls above the nip by side dams defining the casting pool adjacent the ends of the nip;
d. controlling the roll crown of the casting roll casting surface during the casting operation by controlling the radial dimension of the expansion ring in response to at least one of the digital or analog signals received from the at least one sensor;
e. A method of continuously casting thin strip with roll crown control, comprising providing each expansion ring with a channel through which water can pass, and controlling the flow of said water to adjust the expansion of the expansion ring. 35. The method of continuously casting thin strip with roll crown control as claimed in claim 34 , wherein the casting surface of each casting roll is coated with a metal or metal alloy. The thermal insulation coating protects the expansion ring against the cylindrical tube when the cylindrical tube is cooled in the longitudinal water flow path and the heating element is activated, but under similar operating conditions with a similar uncoated expansion ring. 36. A method of continuously casting thin strip with roll crown control according to claim 34 or claim 35 , having a thickness such as to achieve a temperature difference that is at least 67% greater than the temperature difference. a. A pair of counter-rotating casting rolls with a nip therebetween and capable of feeding cast strip downwardly through the nip, each casting roll having a casting surface having a thickness of 80 mm or less and made of copper and copper alloys. a pair of casting rolls formed of a cylindrical tube made of a material selected from the group consisting of:
b. At least one heating element made of stainless steel, nickel or nickel alloy and in direct contact with the expansion ring and having a thermal insulation coating wherein the cylindrical tube is cooled by a longitudinal water flow path to cool the heating element. having a thickness such that the expansion ring, when actuated, with respect to the cylindrical tube, achieves a temperature difference at least 50% greater than the temperature difference under similar operating conditions with a similar uncoated expansion ring. a casting strip edge positioned adjacently within a cylindrical tube and formed at opposite ends of the casting rolls during a casting operation, configured to provide channels therein through which water can flow to regulate expansion of the expansion ring; at least two expansion rings spaced within 450 mm inwardly from
c. and a metal feed system capable of forming a casting pool positioned above the nip and supported on the casting surfaces of the casting rolls by side dams defining the casting pool adjacent the ends of the nip. Thin strip continuous casting equipment. 38. Apparatus for continuously casting thin strip with roll crown control according to claim 37 , wherein the casting surface of each casting roll is coated with a metal or metal alloy. The thermal insulation coating protects the expansion ring against the cylindrical tube when the cylindrical tube is cooled in the longitudinal water flow path and the heating element is activated, but under similar operating conditions with a similar uncoated expansion ring. 39. Apparatus for continuously casting thin strip with roll crown control according to claim 37 or 38 , having a thickness such as to achieve a temperature difference that is at least 67% greater than the temperature difference.

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