CN116511244A - Shearing double-roller casting belt - Google Patents

Shearing double-roller casting belt Download PDF

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Publication number
CN116511244A
CN116511244A CN202210064888.XA CN202210064888A CN116511244A CN 116511244 A CN116511244 A CN 116511244A CN 202210064888 A CN202210064888 A CN 202210064888A CN 116511244 A CN116511244 A CN 116511244A
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CN
China
Prior art keywords
strip
cooling
hotter
length
portions
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Pending
Application number
CN202210064888.XA
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Chinese (zh)
Inventor
P.G.凯利
J.E.凯弗
T.维斯德姆
C.梅德林
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Nucor Corp
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Nucor Corp
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Priority to CN202210064888.XA priority Critical patent/CN116511244A/en
Publication of CN116511244A publication Critical patent/CN116511244A/en
Pending legal-status Critical Current

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Classifications

    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
    • B21B—ROLLING OF METAL
    • B21B1/00—Metal-rolling methods or mills for making semi-finished products of solid or profiled cross-section; Sequence of operations in milling trains; Layout of rolling-mill plant, e.g. grouping of stands; Succession of passes or of sectional pass alternations
    • B21B1/22—Metal-rolling methods or mills for making semi-finished products of solid or profiled cross-section; Sequence of operations in milling trains; Layout of rolling-mill plant, e.g. grouping of stands; Succession of passes or of sectional pass alternations for rolling plates, strips, bands or sheets of indefinite length
    • B21B1/24—Metal-rolling methods or mills for making semi-finished products of solid or profiled cross-section; Sequence of operations in milling trains; Layout of rolling-mill plant, e.g. grouping of stands; Succession of passes or of sectional pass alternations for rolling plates, strips, bands or sheets of indefinite length in a continuous or semi-continuous process
    • B21B1/26—Metal-rolling methods or mills for making semi-finished products of solid or profiled cross-section; Sequence of operations in milling trains; Layout of rolling-mill plant, e.g. grouping of stands; Succession of passes or of sectional pass alternations for rolling plates, strips, bands or sheets of indefinite length in a continuous or semi-continuous process by hot-rolling, e.g. Steckel hot mill
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
    • B21B—ROLLING OF METAL
    • B21B13/00—Metal-rolling stands, i.e. an assembly composed of a stand frame, rolls, and accessories
    • B21B13/02—Metal-rolling stands, i.e. an assembly composed of a stand frame, rolls, and accessories with axes of rolls arranged horizontally
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
    • B21B—ROLLING OF METAL
    • B21B15/00—Arrangements for performing additional metal-working operations specially combined with or arranged in, or specially adapted for use in connection with, metal-rolling mills
    • B21B15/0007—Cutting or shearing the product
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
    • B21B—ROLLING OF METAL
    • B21B45/00—Devices for surface or other treatment of work, specially combined with or arranged in, or specially adapted for use in connection with, metal-rolling mills
    • B21B45/02—Devices for surface or other treatment of work, specially combined with or arranged in, or specially adapted for use in connection with, metal-rolling mills for lubricating, cooling, or cleaning
    • B21B45/0203—Cooling
    • B21B45/0209—Cooling devices, e.g. using gaseous coolants
    • B21B45/0215—Cooling devices, e.g. using gaseous coolants using liquid coolants, e.g. for sections, for tubes
    • B21B45/0218—Cooling devices, e.g. using gaseous coolants using liquid coolants, e.g. for sections, for tubes for strips, sheets, or plates
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
    • B21B—ROLLING OF METAL
    • B21B45/00—Devices for surface or other treatment of work, specially combined with or arranged in, or specially adapted for use in connection with, metal-rolling mills
    • B21B45/02—Devices for surface or other treatment of work, specially combined with or arranged in, or specially adapted for use in connection with, metal-rolling mills for lubricating, cooling, or cleaning
    • B21B45/0203—Cooling
    • B21B45/0209—Cooling devices, e.g. using gaseous coolants
    • B21B45/0215—Cooling devices, e.g. using gaseous coolants using liquid coolants, e.g. for sections, for tubes
    • B21B45/0233—Spray nozzles, Nozzle headers; Spray systems
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
    • B21B—ROLLING OF METAL
    • B21B9/00—Measures for carrying out rolling operations under special conditions, e.g. in vacuum or inert atmosphere to prevent oxidation of work; Special measures for removing fumes from rolling mills
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B22—CASTING; POWDER METALLURGY
    • B22D—CASTING OF METALS; CASTING OF OTHER SUBSTANCES BY THE SAME PROCESSES OR DEVICES
    • B22D11/00—Continuous casting of metals, i.e. casting in indefinite lengths
    • B22D11/001—Continuous casting of metals, i.e. casting in indefinite lengths of specific alloys
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B22—CASTING; POWDER METALLURGY
    • B22D—CASTING OF METALS; CASTING OF OTHER SUBSTANCES BY THE SAME PROCESSES OR DEVICES
    • B22D11/00—Continuous casting of metals, i.e. casting in indefinite lengths
    • B22D11/06—Continuous casting of metals, i.e. casting in indefinite lengths into moulds with travelling walls, e.g. with rolls, plates, belts, caterpillars
    • B22D11/0622—Continuous casting of metals, i.e. casting in indefinite lengths into moulds with travelling walls, e.g. with rolls, plates, belts, caterpillars formed by two casting wheels
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B22—CASTING; POWDER METALLURGY
    • B22D—CASTING OF METALS; CASTING OF OTHER SUBSTANCES BY THE SAME PROCESSES OR DEVICES
    • B22D11/00—Continuous casting of metals, i.e. casting in indefinite lengths
    • B22D11/14—Plants for continuous casting
    • B22D11/144—Plants for continuous casting with a rotating mould
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/02—Ferrous alloys, e.g. steel alloys containing silicon
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/04—Ferrous alloys, e.g. steel alloys containing manganese
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
    • C22C38/40—Ferrous alloys, e.g. steel alloys containing chromium with nickel
    • C22C38/42—Ferrous alloys, e.g. steel alloys containing chromium with nickel with copper
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
    • C22C38/40—Ferrous alloys, e.g. steel alloys containing chromium with nickel
    • C22C38/44—Ferrous alloys, e.g. steel alloys containing chromium with nickel with molybdenum or tungsten
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
    • C22C38/40—Ferrous alloys, e.g. steel alloys containing chromium with nickel
    • C22C38/48—Ferrous alloys, e.g. steel alloys containing chromium with nickel with niobium or tantalum
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
    • C22C38/40—Ferrous alloys, e.g. steel alloys containing chromium with nickel
    • C22C38/58—Ferrous alloys, e.g. steel alloys containing chromium with nickel with more than 1.5% by weight of manganese
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
    • B21B—ROLLING OF METAL
    • B21B13/00—Metal-rolling stands, i.e. an assembly composed of a stand frame, rolls, and accessories
    • B21B13/02—Metal-rolling stands, i.e. an assembly composed of a stand frame, rolls, and accessories with axes of rolls arranged horizontally
    • B21B2013/021—Twin mills
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
    • B21B—ROLLING OF METAL
    • B21B13/00—Metal-rolling stands, i.e. an assembly composed of a stand frame, rolls, and accessories
    • B21B13/02—Metal-rolling stands, i.e. an assembly composed of a stand frame, rolls, and accessories with axes of rolls arranged horizontally
    • B21B2013/025—Quarto, four-high stands
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
    • B21B—ROLLING OF METAL
    • B21B15/00—Arrangements for performing additional metal-working operations specially combined with or arranged in, or specially adapted for use in connection with, metal-rolling mills
    • B21B2015/0057—Coiling the rolled product

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  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Chemical & Material Sciences (AREA)
  • Materials Engineering (AREA)
  • Metallurgy (AREA)
  • Organic Chemistry (AREA)
  • Continuous Casting (AREA)

Abstract

A method of producing twin roll cast, hot rolled, cooled and coiled metal strip comprising controlling the method such that at the end of a cooling station, portions of the strip length are relatively hotter than other portions of the strip length, and such hotter portions are subsequently sheared by and at a shearing station, the hotter portions being sheared more readily than other relatively cooler portions of the cooling strip length.

Description

Shearing double-roller casting belt
Technical Field
The present invention relates to the manufacture of thin strip, such as thin steel strip, by twin roll casting.
Background
In twin roll casters, molten metal is delivered from a delivery system to a casting pool supported on casting surfaces of a pair of counter-rotating horizontal casting rolls, the interior of which is water cooled, thereby forming a solidified metal shell on the moving casting roll surfaces. The metal shells are brought together at the nip between them to produce a solidified strip product that is delivered downwardly from the nip between the casting rolls. The term "nip" as used herein refers to the general area of the casting rolls closest together.
The molten metal may be poured from a ladle into a smaller vessel or series of smaller vessels from which it flows through one or more metal delivery nozzles located above the nip to form a casting pool of molten metal supported on the casting surfaces of the casting rolls above the nip and extending the length of the nip.
The casting pool is typically confined between side plates or dams held in sliding engagement with the ends of the casting rolls to dam the casting pool against outflow. The upper surface of the casting pool (often referred to as the "meniscus" height) is generally above the lower end of the delivery nozzle such that the lower end of the delivery nozzle is immersed in the casting pool.
When casting steel strip with a twin roll caster, the strip exits the nip, passes through a guide table, through a pinch roll stand, and then through a hot rolling mill where the strip is thinned to a desired thickness. The hot rolled strip is then cooled to form a strip having the microstructure desired for the end use. The cooled strip is then wound up and periodically cut with a shears upstream of the coiler to form strips of the desired length in each coil.
The above comments are not an admission of common general knowledge in china or elsewhere.
Disclosure of Invention
The invention includes a method of producing a twin roll cast, hot rolled, cooled and coiled metal strip comprising controlling the method such that at the end of the cooling station, portions of the strip length are hotter than other portions of the strip length, and these hotter portions are subsequently passed through and sheared in a shearing station.
The invention includes a method of producing a cast metal (typically steel) strip comprising: forming a continuous thin metal strip having a thickness of less than 3mm in a twin roll caster; moving the cast strip through a hot rolling mill and reducing the thickness of the cast strip; moving the hot rolled strip through a cooling station and cooling the strip; moving the cooled hot rolled cast strip through a shearing station and periodically shearing the strip and forming a selected length of strip; and moving the cooled hot rolled strip to a coiler and forming a coil of selected length at the coiler and for controlling the method such that portions of the length of the cooled strip are hotter at the ends of the cooling station than other portions of the length of the strip and such hotter portions are subsequently passed through and sheared in the shearing station, wherein the hotter portions are more susceptible to shearing than other relatively cooler portions of the length of the cooled strip.
The method produces rolls of cast, hot rolled and cooled metal strip having leading and trailing end portions that exceed the customer specifications of the strip because these portions are hotter portions when sheared to form the leading and trailing end portions of the continuously wound rolls. The central part of the coil meets the customer specifications.
The term "customer specification" is understood herein to mean a specification that includes coil weight, strip thickness, composition, microstructure, and mechanical properties.
The hotter portion may be at any suitable temperature.
In any event, the choice of higher temperature is a function of many factors, including, for example, the composition of the steel and the microstructure and final properties of the strip exiting the cooling station.
The method may be controlled such that the hotter portion is at least 100 ℃ hotter than the rest of the cooling belt.
The method may be controlled such that the hotter portion is at least 150 ℃ hotter than the rest of the cooling belt.
The method may be controlled such that the hotter portion is at least 200 ℃ hotter than the rest of the cooling belt.
The method may be controlled such that the hotter portion is at least 300 ℃ hotter than the rest of the cooling belt.
The method may be controlled such that the hotter portion is at least 400 ℃ hotter than the rest of the cooling belt.
The process may be controlled such that the length of the hotter portion is the length that passes through the cooling station for up to 7 seconds under standard operating conditions of the process.
The process may be controlled such that the length of the hotter portion is the length that passes through the cooling station for up to 5 seconds under standard operating conditions of the process.
The method may include water cooling the hot rolled strip as it moves through the cooling station.
The method may include selectively controlling the supply of cooling water to form the hotter portions of the cooling belt as the hot rolled strip moves through the cooling station.
The method may include continuously cooling the hot rolled strip with water from a plurality of water spray assemblies spaced along a length of the cooling station.
The method may include selectively controlling water flow to the water spray assembly and gradually increasing the temperature of the hotter portion of the cooling belt moving through the cooling station as compared to the temperature of the preceding portion of the cooling belt having moved through the cooling station.
The method may include selectively reducing water flow at each water spray assembly over a period of time and gradually increasing the temperature of the hotter portion of the cooling belt moving through the cooling station as compared to the temperature of the preceding portion of the cooling belt having moved through the cooling station.
The invention also provides an apparatus for producing a cast metal strip comprising:
-a twin roll strip caster for forming a continuous thin metal strip having a thickness of less than 3 mm;
-a hot rolling mill for reducing the thickness of the cast strip;
-a cooling station for cooling the hot rolled strip;
-a shearing station for periodically shearing the cooled strip and forming a strip of selected length; and
-a reel-up for forming rolls of cooling strip of a selected length; and
-a controller for controlling the method such that the portions of the length of the cooling belt are hotter at the ends of the cooling station than other portions of the length of the belt, and these hotter portions are subsequently sheared by and at the shearing station, wherein the hotter portions are more easily sheared than the other relatively cooler portions of the length of the cooling belt.
The present invention also provides a length of coil of twin roll cast, hot rolled and cooled metal strip that includes a leading end portion and a trailing end portion that are beyond customer specifications for the strip, and a center portion that is within the customer specifications.
The control option for the cooling station may be any one of the following options, with the attention being directed to the time at which the shear cut of the hotter portion of the strip occurs.
-full automatic control of the water supply to the cooling station, capable of controlling the belt temperature along the length of the belt.
-performing an automatic shear cut in the controlled hotter part by fully automatic position tracking through the pass-through station and the shear station.
-timing of closing the cooling station water supply set by the PLC. The PLC control calculates the time between the water flow reduction signal and the timing of the shear actuation by each water supply valve. This includes hysteresis in the valve response and the shear response. The dynamic belt speed is included in the calculation. The control system monitors coil size and mass. When the desired tape size or quality is reached, the shear cut is activated. The cooling control calculates and activates the valve timing in advance to ensure that the timing of the shear activation signal will cause the cut to occur in the hotter portion of the belt.
-manually shutting off the water supply to the cooling station. The operator requests manual cutting by pressing a shear cut button of the control system. The control system then activates the cooling valve to shut off the water, forming the hotter portion of the belt. The shear initiation is delayed until the cut occurs in the hotter portion of the tape.
-single button press, PLC control of the cooling station water supply is activated.
-emergency shut-off of the water supply to the cooling station. In some emergency situations, the operator needs to immediately make the cut. If there is a double button press (or other) option in the control system, the shear cut will be initiated without changing the cooling valve. Shear cutting will occur in the cold band.
-closing all water supply valves if the control system detects that the belt is stopped on the table. This may make it easier to cut and remove the tape because it is softer in the uncooled condition.
The steel may be any suitable steel composition for use in twin roll strip casters.
The invention is particularly advantageous for high strength steels that are very difficult to shear, such as martensitic steel grades.
For example, the steel may be a high strength low alloy steel.
For example, the steel may be an ultra-high strength weathering steel sheet formed from a molten steel melt comprising (i) 0.20% to 0.35% carbon, less than 1.0% chromium, 0.7% to 2.0% manganese, 0.10% to 0.50% silicon, 0.1% to 1.0% copper, less than or equal to 0.12% niobium, less than 0.5% molybdenum, 0.5% to 1.5% nickel, and a ballast containing less than 0.01% aluminum by weight; and (ii) the remaining iron and impurities resulting from the melting.
For example, the steel may be any of the following ASTM and other grades 55, 70, 80, 90, 100, 550 and Q690.
Advantages of the above-described methods and apparatus include the following.
During the production of high strength steel, the shear cutting of the strip takes place in the hotter softer material.
The shearing blade is used for a longer time.
Conventional shear blade materials may be used.
More even band entry shear-pebble shape reduction.
A flatter strip enters the turning roll of the coiler-less pebbles.
-a flat feed belt for the downstream process.
The ability to cut high strength belts using smaller (lower manufacturing weight), lower capital cost shearing stations.
-a sample of quenched material represents a bulk coil. Samples of the tape may be drawn for inspection and testing. The sample must represent the bulk of the roll. It cannot extract the hotter part of the belt. If the length is short, the hotter part can be removed from a set of unwind rolls shortly after removal from the reel and the sample removed from the cooled length of the belt. If the hot rolled strip length is long, stations may not be provided to remove these longer lengths of strip. The roll must be sent to a downstream station to remove the longer hot length of the roll and then the test sample is run. This may lead to testing and inspection delays. The fast feedback on testing and inspection means that the roll is ready for the next processing step, thereby improving the process efficiency.
Drawings
For a more detailed description of the invention, some illustrative examples will be given with reference to the accompanying drawings, in which:
FIG. 1 is a schematic side view of one embodiment of a twin roll caster of the present invention;
FIG. 2 is an enlarged partial cross-sectional view of a portion of the twin roll caster of FIG. 1;
FIG. 3 is a partially schematic side view of the exit end of the twin roll caster of FIG. 1;
FIG. 4 is a graph of cooling station water flow and strip temperature versus time showing an embodiment of the method of the present invention;
FIG. 5 is a graph corresponding to that shown in FIG. 4, showing a time sequence of closing and opening water supply valves to a header of a water spray assembly positioned at intervals along the length of a cooling station to form a hotter portion along the length of a strip passing through the cooling station in accordance with an embodiment of the method of the present invention; and
fig. 6 is a graph showing shear cutting time.
Detailed Description
The following description of the examples is made in the context of microalloyed twin roll strip casting high strength steel. The invention is not limited to the production of high strength steel strips.
The described embodiment is one, but not all, of the embodiments of the invention.
All other embodiments obtained based on the described embodiments of the invention by a person skilled in the art without any inventive effort fall within the scope of the invention.
Unless defined otherwise, technical or scientific terms used in this disclosure should take the meanings commonly understood by one of ordinary skill in the art to which this invention belongs.
Referring now to fig. 1 and 2, a twin roll caster is shown comprising a main frame 10 that stands from the factory floor and supports a pair of counter-rotatable casting rolls 12 mounted in modules of roll cassettes 11. Casting rolls 12 are mounted in roll cassettes 11 for operation and movement as described below. The roll cassettes 11 facilitate rapid movement of the casting rolls 12 from the set position to the operational casting position as a unit in the casting machine and rapid removal of the casting rolls 12 from the casting position when the casting rolls 12 are to be replaced. The roll cassette 11 is not particularly structured so long as it functions to facilitate movement and positioning of the casting rolls 12 as described herein.
Twin roll caster comprises a pair of counter-rotatable casting rolls 12 with casting surfaces 12A positioned laterally to form a nip 18 therebetween. Molten metal is supplied from ladle 13 through a metal delivery system to metal delivery nozzle 17 (core nozzle) between casting rolls 12 above nip 18. The molten metal so delivered forms a casting pool 19 of molten metal above the nip 18 supported on the casting surfaces 12A of the casting rolls 12. The casting pool 19 is confined in the casting area at the ends of the casting rolls 12 by a pair of side closure plates or dams 20. The upper surface of the casting pool 19 (commonly referred to as the "meniscus" height) may rise above the lower end of the delivery nozzle 17 such that the lower end of the delivery nozzle 17 is submerged within the casting pool 19. The casting area includes the addition of a protective atmosphere over the casting pool 19 to inhibit oxidation of the molten metal in the casting area.
The ladle 13 is typically of conventional construction supported on a rotating turntable 40. For the delivery of the metal, a ladle 13 is positioned above a movable tundish 14 in the casting position to fill the tundish 14 with molten metal. The movable tundish 14 may be positioned on a tundish car 66. The tundish car 66 is capable of transferring the tundish 14 from a heating station (not shown) where the tundish 14 is heated to near the casting temperature to a casting position.
The movable tundish 14 may be fitted with a sliding gate 25 that may be actuated by a servo mechanism to allow molten metal to flow from the tundish 14 through the sliding gate 25 and then through the refractory outlet shield 15 to the transition piece or distributor 16 in the casting position. The molten metal flows from the distributor 16 to the delivery nozzles 17 between the casting rolls 12 above the nip 18.
The side dams 20 may be made of a refractory material such as zirconia graphite, graphite alumina, boron nitride zirconia or other suitable composite materials. The side dams 20 have surfaces that are capable of physically contacting the casting rolls 12 and the molten metal in the casting pool 19. The side dams 20 are mounted in side dam holders (not shown) that are movable by side dam actuators (not shown), such as hydraulic or pneumatic cylinders, servos, or other actuators, to engage the side dams 20 with the ends of the casting rolls 12. In addition, the side dam actuator is capable of positioning the side dam 20 during casting. The side dams 20 form the end caps of the molten metal bath on the casting rolls 12 during the casting operation.
FIG. 1 shows a twin roll caster producing cast strip 21 with strip 21 passing through a guide table 30 to a pinch roll stand 31 comprising pinch rolls 31A. Upon exiting the pinch roll stand 31, the cast thin strip 21 may pass through a hot rolling mill 32, the hot rolling mill 32 including a pair of work rolls 32A and backup rolls 32B, forming a gap capable of hot rolling the cast thin strip 21 delivered from the casting rolls 12 where the cast thin strip 21 is hot rolled to reduce the strip to a desired thickness, improve the strip surface, and improve strip flatness. The work roll 32A has a work surface associated with a desired belt profile across the work roll 32A. The hot rolled cast strip 21 is then transferred to the output stage 33 in the cooling station 97 where it can be cooled by contact with a coolant, such as water, supplied via nozzles 90 or other suitable means, as well as by convection and radiation. Regardless, the cooled hot rolled cast strip 21 passes through a second pinch roll stand 91, the pinch roll stand 91 having a pair of rolls 91A providing tension to the cast strip 21. Finally, the cooled hot rolled cast strip 21 is then coiled, and the strip is periodically cut with a shears at a shearing station 98 upstream of the coiler to form strips of the desired length for each coil.
As described below, the casting rolls 12 are internally water cooled such that as the casting rolls 12 counter-rotate, the shells solidify on the casting surfaces 12A as the casting surfaces 12A move into contact with each rotation of the casting rolls 12 and through the casting pool 19. The shells are brought together tightly at the nip 18 between the casting rolls 12 to produce a cast thin strip product 21 that is delivered downwardly from the nip 18. Cast strip product 21 is formed from shells at nip 18 between casting rolls 12 and is transported downwardly and moved downstream as described above.
In operation, the belt exits the nip at a temperature of about 1400 ℃ or greater. To prevent oxidation and scaling of the strip, the metal strip is cast down into a closure 27, the closure 27 supporting a protective atmosphere directly below the casting rolls in the casting position. The enclosure 27 may extend along the path of the cast strip up to the first pinch roll stand 31 and may extend along the path of the cast strip up to the hot rolling mill 32 to reduce oxidation and fouling.
After the hot rolling mill 32, the rolled thin strip then enters a cooling station 97 where the strip is cooled by water as it moves over the output table 33 in the cooling station 97, the water being delivered by the spray nozzles 90 of the multiple rows of water spray assemblies extending through the output table 33. Although the nozzle atomizes the coolant to produce a spray, in any embodiment, any other coolant discharge port can be used in the nozzle. In addition to creating a spray, other types of coolant discharge ports may discharge a non-atomized coolant stream.
In the exemplary embodiment shown in FIG. 3, a cooling station 97 extends along a strip path 99 between the hot rolling mill 32 and the second pinch roll stand 91 with a plurality of nozzles 90 in a multi-row water jet assembly disposed therebetween. Although not discernable in the view shown in fig. 3, the rows of nozzles 90 extend substantially across the width of the belt or cooling station in a widthwise arrangement and are spaced apart along the length of the cooling station.
Further details regarding the twin roll caster described in fig. 1-3 can be found in the specification of chinese patent application 201780029304.2 filed in the name of the applicant, the disclosure of which is incorporated herein by cross-reference.
In operation, the method is controlled such that at the end of the cooling station 97, portions of the ribbon length are relatively hotter than other portions of the ribbon length, and these hotter portions are then passed through and sheared at the shearing station 98, with the hotter portions being more easily sheared than other relatively cooler portions of the cooled ribbon length.
In the exemplary embodiment, control is provided by selectively supplying water to nozzles 90 of water spray assemblies that are spaced apart along the length of cooling station 97. This includes selectively closing and opening valves that allow water to flow to the headers of the water spray assemblies so that the portion of the belt passing along the length of the cooling station 97 receives less water than the other preceding and following portions of the belt length and thus becomes hotter than those preceding and following portions. The selective supply of water to the nozzles 90 of the nozzle assembly is timed according to the speed of the belt through the apparatus so that the hotter portions arrive at the shear station 98 as the web cutting time comes. The hotter portions of the tape shear more easily.
FIG. 4 is a plot of cooling station water flow and strip temperature ("y" axis) versus time ("x" axis) showing an embodiment of the method of the present invention for twin roll casting and hot rolling 1500 grade-martensite. As can be seen in fig. 4, the water supplied to the header of the nozzle assembly gradually decreases over a period of time and then increases over another period of time (see line 101), with the result that the belt temperature increases rapidly and then decreases rapidly (see line 103), although there is a short lag time between the water flow decrease and the belt temperature increase. As is clear from fig. 4, the water supply control creates a hotter portion of the belt.
FIG. 5 is a graph corresponding to that shown in FIG. 4, showing a time sequence of closing and opening the water supply valve to the header of the water spray assembly to produce a decrease and increase in water supply to the header of the nozzle assembly shown by line 101 of FIG. 4 to form a hotter portion along the length of the strip passing through the cooling station. The figure shows a time series of on/off of 9 bottom manifold valves in the cooling station, noting that the manifold valves control water flow to the headers of the water spray assemblies, which are spaced along the length of the cooling station.
It will be appreciated that cutting each hotter portion of the strip, and then winding the strip, results in the portion of the hotter portion downstream of the cutting station 98 forming the trailing end portion of one roll, while the other portion of the hotter portion upstream of the cutting station 98 forms the leading end portion of the next formed roll. This results in the trailing and leading end portions of the roll having a different microstructure than the body of the cooled roll.
Fig. 6 shows the delay in initiating the shear cut relative to the cooling control at the cooling station 97. The "shear cut open" (see bottom cooling manifold valve 4 status of fig. 6) is in part the duration of the shear signal sent from the PLC. The "shear position" (see bottom cooling manifold valve 1 status of fig. 6) line is the actual position of the shear drum, in this case the shear station 98 is the drum, the knife spans one position on the circumference, the drum rotates to the belt speed, and the knife cuts the moving belt. Rotation also increases the delay of the actual cutting time, which must be considered. The "shear cooling valve close command" portion is the duration of a signal from the PLC that runs a time sequence of closing and opening the water supply valve to the header of the water spray assembly to form the next hotter portion along the length of the strip passing through the cooling station.
Thus, the method produces cast, hot rolled and cooled coil leading and trailing end portions that exceed the customer specifications of the strip because these portions are hotter portions when sheared to form the leading and trailing end portions of the continuously wound coil. The central portion of the roll meets customer specifications.
While the principles and modes of operation of this invention have been illustrated and described with respect to specific embodiments, it must be understood that this invention may be practiced otherwise than as specifically illustrated and described without departing from its spirit or scope.

Claims (14)

1. A method of producing a cast metal strip comprising:
forming a continuous thin metal strip having a thickness of less than 3mm in a twin roll caster;
moving the cast strip through a hot rolling mill and reducing the thickness of the cast strip;
moving the hot rolled strip through a cooling station and cooling the strip;
moving the cooled hot rolled cast strip through a shearing station and periodically shearing the strip and forming a selected length of strip;
the cooled hot rolled cast strip is moved to a coiler and a selected length of coil is formed at the coiler and the method is controlled such that portions of the length of the cooled strip are hotter at the ends of the cooling station than other portions of the length of strip and these hotter portions are subsequently passed through and sheared in the shearing station, with the hotter portions being more susceptible to shearing than other relatively cooler portions of the length of cooled strip.
2. The method according to claim 1, comprising: the method is controlled such that the hotter portion is at least 200 ℃ hotter than the other portions of the cooling belt.
3. The method according to claim 1, comprising: the method is controlled such that the hotter portion is at least 300 ℃ hotter than the other portions of the cooling belt.
4. The method according to claim 1, comprising: the method is controlled such that the hotter portion is at least 400 ℃ hotter than the rest of the cooling belt.
5. The method according to any of the preceding claims, comprising: the process is controlled such that the length of the hotter portion is the length through the cooling station for a period of up to 7 seconds under standard operating conditions of the process.
6. The method according to any of the preceding claims, comprising: the process is controlled such that the length of the hotter portion is the length through the cooling station for a period of up to 5 seconds under standard operating conditions of the process.
7. The method according to any of the preceding claims, comprising: the hot rolled strip is water cooled as it moves through the cooling station.
8. The method of claim 7, comprising: the supply of cooling water is selectively controlled to form the hotter portions of the cooling belt as the hot rolled strip moves through the cooling station.
9. The method according to claim 7 or 8, comprising: the hot rolled strip is continuously cooled with water from a plurality of water spray assemblies spaced along the length of the cooling station.
10. The method of claim 9, comprising: the water flow to the water spray assembly is selectively controlled and the temperature of the hotter portion of the cooling belt moving through the cooling station is gradually increased compared to the temperature of the preceding portion of the cooling belt having moved through the cooling station.
11. The method of claim 9, comprising: the water flow at each water spray assembly is selectively reduced over a period of time and the temperature of the hotter portion of the cooling belt moving through the cooling station is gradually increased as compared to the temperature of the preceding portion of the cooling belt having moved through the cooling station.
12. An apparatus for producing cast metal strip comprising:
-a twin roll strip caster for forming a continuous thin metal strip having a thickness of less than 3 mm;
-a hot rolling mill for reducing the thickness of the cast strip;
-a cooling station for cooling the hot rolled strip;
-a shearing station for periodically shearing the cooled strip and forming a strip of selected length; and
-a reel-up for forming rolls of cooling strip of a selected length; and
-a controller for controlling the method such that the portions of the length of the cooling belt are hotter at the ends of the cooling station than other portions of the length of the belt, and these hotter portions are subsequently sheared by and at the shearing station, wherein the hotter portions are more easily sheared than the other relatively cooler portions of the length of the cooling belt.
13. A length of coil of twin roll cast, hot rolled and cooled metal strip comprising: a leading portion and a trailing portion beyond the customer specification of the belt, and a center portion within the customer specification.
14. A roll of tape according to claim 13, manufactured by a method according to any one of claims 1 to 9.
CN202210064888.XA 2022-01-20 2022-01-20 Shearing double-roller casting belt Pending CN116511244A (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
CN202210064888.XA CN116511244A (en) 2022-01-20 2022-01-20 Shearing double-roller casting belt

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
CN202210064888.XA CN116511244A (en) 2022-01-20 2022-01-20 Shearing double-roller casting belt

Publications (1)

Publication Number Publication Date
CN116511244A true CN116511244A (en) 2023-08-01

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Family Applications (1)

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CN202210064888.XA Pending CN116511244A (en) 2022-01-20 2022-01-20 Shearing double-roller casting belt

Country Status (1)

Country Link
CN (1) CN116511244A (en)

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