Classifications

• • 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
• • 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
  • B22D11/0611—Continuous casting of metals, i.e. casting in indefinite lengths into moulds with travelling walls, e.g. with rolls, plates, belts, caterpillars formed by a single casting wheel, e.g. for casting amorphous metal strips or wires
• • 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
  • B22D11/0637—Accessories therefor
  • B22D11/0694—Accessories therefor for peeling-off or removing the cast product

Definitions

• the invention relates to a continuous casting plant for the continuous casting of a thin metal strip, in particular a steel strip with a thickness of less than 20 mm, preferably between 1 to 12 mm, with a melt receiving container which has a melt mouth on which a casting surface for receiving melt in a thin layer can be moved past to form a strand, as well as with a strand support device taking over the strand from the casting surface, and further a method for operating a continuous casting installation of this type.
• a continuous casting installation for producing a thin metal strip of the type described in the introduction is known, for example, from EP-A - 0 526 886.
• the molten metal is applied either to a casting roll or to an endless caterpillar chain composed of links and, after formation of a band-shaped strand shell, is transferred from the casting roll or caterpillar chain to an approximately horizontally oriented strand support device which is designed as an endless conveyor belt.
• the metal strip still has an upper side formed by the melt; it only solidifies on its underside, on which it was in contact with the casting roll or the endless belt.
• the transport device is provided with cooling so that the metal strip is already solidified when it leaves the transport device.
• the transport device which is designed as an endless belt, is formed by a net or grid, air or water being sprayed or guided through the interstices of the net or grid against the strand in order to the bottom of the metal band to cool intensely.
• a stationary intermediate support is provided between the casting surface and the transport device in order to bridge the space between the casting surface and the transport device.
• a system of this type has the disadvantage that the transport device formed by an endless belt has many moving parts which must be arranged in the immediate casting area of the metal belt. They are subject to heavy wear and tear and are therefore subject to great wear in rough casting operations.
• a further disadvantage is that because of the deflection rollers of the casting surface and the transport device there is inevitably a relatively large space which must be bridged by an intermediate support. Difficulties arise here when transporting the metal strip, which has only a thin solidified underside of the band and is still very soft due to the high temperature, since the solidified underside of the metal band is at risk of cracking as a result of the frictional forces occurring between this underside and the intermediate support. These frictional forces are particularly high if the usually provided refractory graphite plates or plates made of refractory material are arranged for intermediate support.
• the transport device can also be formed by a stationary table, the metal belt being transported over the table by driven support rollers.
• the belt can hardly be supported by rollers, since the support rollers would have to have extremely small radii because of the small thickness and the low dimensional stability of the metal belt, in order to be able to be arranged as closely as possible.
• a continuous caster of the type described above is also known from EP-A - 0 568 211.
• a scraper is provided directly next to the casting surface, which takes over the belt from the casting surface and conveys it to a transport table arranged downstream. Both the scraper and the transport table are stationary and approximately in the horizontal direction.
• the hot and still very soft belt that is detaching from the casting surface is at high risk of cracking due to the friction forces that occur, so that the belt, in particular the beginning of the belt, can adhere to the stripper or the transport table. This can damage the belt and even break the casting.
• the tape may also buckle.
• the invention aims to avoid these disadvantages and difficulties and has as its object to provide a continuous caster of the type described above and a method for operating the same, which the casting of metal strips, which still have a very thin strand shell when lifted from the casting surface, without Allow occurrence of a risk of cracking and with high casting performance.
• the continuous caster is also said to have particularly good heat transfer between the partially solidified metal strip and that following the casting surface Allow strand support device, so that the metal strip is rapidly solidified even when casting at high casting speed.
• the strand support device has a substantially flat and substantially horizontal surface supporting the strand, into which gas passage channels open, which can be connected to a gas delivery device.
• a method for producing metal foils is known from EP-A - 0 629 459.
• molten metal is applied to a quenching roller via a nozzle, at which the liquid metal immediately solidifies.
• the foil is separated from the quenching roller by tangential blowing of air and transported away from the quenching roller by means of an endless conveyor belt.
• the metal foil is sucked onto the endless conveyor belt by sucking in air, for which purpose the endless conveyor belt is permeable to air.
• the foils have a thickness of the order of 25 ⁇ m, and amorphous solidification occurs when the liquid metal strikes them.
• the solidified metal foil is brittle and tends to flutter and, due to its marginal weight, would immediately lift off the endless conveyor belt and the quenching roller, which is prevented by sucking against the endless conveyor belt and placing a beam against the quenching roller.
• the gas delivery device is advantageously designed as a device which pressurizes the gas to be delivered through the gas passage channels, such as inert gas or air.
• the gas passage channels such as inert gas or air.
• the gas conveying device is designed as a device which pressurizes the gas to be conveyed through the gas passage channels.
• This enables the metal strip to be easily sucked into the top of the strand support device during continuous operation, that is to say after casting, so that particularly good contact between the metal strip and the strand support device and thus particularly effective cooling is ensured.
• This enables casting at high casting rates, i.e. high casting speeds, or the casting of somewhat thicker metal strips in a short time until solidification occurs.
• the invention makes it possible to find sufficiency with a very simply designed strand support device, namely a strand support device designed as a rigidly arranged plate, that is to say without moving parts.
• the strand support device is formed from a good heat-conducting material, in particular copper or a copper alloy, and is expediently provided with an internal cooling, in particular a liquid internal cooling.
• the strand support device is formed by two components, e.g. a strand scraper directed towards the casting surface and directly terminating at this and a cooling table adjoining this in the direction of strand extraction, both the strand scraper and the cooling table being provided with gas passage channels.
• the strand support device is advantageously provided with side boundaries which extend in the strand pull-out direction of the strand and encompass the strand longitudinal side edges. This largely prevents lateral gas leakage when a gas cushion is generated between the metal strip and the strand support device.
• the gas passage channels advantageously take up a total cross-sectional area of 0.01 to 20%, preferably 0.1 to 5%, of the surface of the strand support device supporting the strand at their openings opening into the surface of the strand support device.
• the gas passage channels preferably have a cross-sectional area of 1 to 50 mm 2 , preferably 3 to 20 mm 2 , at their openings opening into the surface of the strand support device.
• a particularly advantageous generation of a gas cushion is ensured if the gas passage channels form an acute angle with their mouths with the surface of the support device. It is advantageous if the orifices of the gas passage channels are directed in such a way that a gas stream which moves essentially in the direction of pulling out the strand is formed. This gas flow already forms at the channel mouths.
• the cross-sectional area of the openings formed by the gas passage channels on the surface of the strand support device is expediently larger at the beginning of the strand support device than in sections of the strand support device following in the strand pull-out direction, which in particular facilitates critical casting, ie the start of casting, in which the metal strip is particularly at risk.
• the strand support device is provided with coolant channels arranged transversely to the strand running direction and at least several of these coolant channels are each connected to a coolant supply pipe functioning as a distributor line and to a coolant discharge pipe functioning as a manifold, which are arranged with respect to the strand support device.
• a coolant channel is advantageously guided several times through the strand support device starting from the distributor line and then opens into the header line.
• the pressure between the underside of the strand and the strand support device is advantageously adjusted by appropriate suction and / or gas supply for control purposes.
• a method for starting up a continuous caster in which melt is continuously applied from a melt receiving container to a casting surface moving past a melt mouth of the melt receiving container, and the melt solidifies on the casting surface with the continuous formation of a strand, the strand, which may be facing away from the casting surface Side is still liquid, is conveyed from the casting surface to a strand support device and is supported and cooled there, characterized in that a gas cushion is generated between the strand support device and the solidified underside of the strand of the strand, etc. especially only at the beginning of the strand.
• the continuous caster in which melt is continuously applied from a melt receiving container to a casting surface moving past an opening of the melt receiving container and the melt solidifies on the casting surface with the continuous formation of a strand, the strand, which may be on its side facing away from the casting surface is still liquid, is conveyed from the casting surface onto a strand support device and is supported and cooled there Expediently, a negative pressure and thus a particularly good fit of the underside of the strand against the surface of the strand support device are generated between the strand support device and the solidified underside of the strand
• a gas cushion is generated between the solidified underside of the partially or thick-stranded strand and the strand support device, in which there is an overpressure relative to the ambient air pressure (atmosphere) of 0.1 to 20 mbar, preferably 0.5 to 10 mbar.
• the negative pressure between the solidified underside of the strand and the strand support device is advantageously up to 1000 mbar (vacuum), preferably it is between 5 and 100 mbar.
• FIG. 1 shows a partially sectioned side view of a continuous casting installation according to the invention in a schematic representation
• Fig. 2 shows a detail of Fig. 1 on an enlarged scale
• Fig. 3 shows a cross section along the line III-III of Fig. 1 also on an enlarged scale
• FIG. 4 shows a modified embodiment in a representation analogous to FIG. 2.
• 5 and 6 illustrate in a schematic representation once (FIG. 5) a partial view of a continuous casting installation and once (FIG. 6) a section along the line VI-VI of FIG. 5.
• melt 3 is allowed to flow from a melt receptacle 4 via a melt mouth 5 of this container 4 onto a casting roller 6.
• a very thin strand shell 7 is first formed, which is lifted from the surface 8 of the casting roll 6 and transferred to a strand support device, which is generally designated 9.
• the strand support device 9 has a wedge-shaped strand wiper 10, which is pointed with its pointed end 11 directly against the casting surface 8.
• the strand wiper adjoins the casting surface in the area just next to the uppermost generatrix 13 of the casting surface, which lies in the vertical plane 13 through the axis of rotation 12 of the casting roll.
• a cooling table 14 supplementing the strand support device 9 is provided directly on the strand wiper 10. Both the surface of the stripper 10 receiving the metal strip 1 with the solidified underside and the cooling table 14 following the stripper are oriented approximately horizontally.
• the metal strip 1 reaching the cooling table 14 still has a liquid surface 15, but the solidified strand shell 7 of the metal strip 1 increases in thickness as it moves along the cooling table 14 until the metal strip 1 solidifies at a point 16 on the cooling table 14 is.
• the strand stripper 10 and the cooling table 14 are made of a good heat-conducting material, preferably copper or a copper alloy, in order to ensure good heat transfer between the metal strip 1 and the strand support device 9.
• Both the stripper 10 and the cooling table 14 are provided with a liquid internal cooling system, which is formed by channels 17 extending transversely to the longitudinal extension of the strand support device 9.
• the channels 17 are connected to coolant supply and discharge pipes 18, 19 which are arranged parallel to the longitudinal extension of the strand support device 9 and to the side thereof.
• a plurality of channels 17 are each connected in line with a coolant supply pipe 18 and with a coolant discharge pipe 19, one coolant channel 17 in each case being guided through the strand support device 9 in a meandering manner.
• both the stripper 10 and the cooling table 14 are also provided with gas channels 20, which also extend transversely to their longitudinal directions and from which gas passage channels 21 emanate, which open out on the surface 22 of the cooling table 14 or stripper 10.
• the gas channels can be connected via gas lines 23 arranged in the longitudinal direction of the strand support device 9 to a gas delivery device which is designed both as the gas within the gas channels 20 under pressure and under pressure.
• gas such as inert gas or air, can optionally be blown through the gas passage channels 21 between the underside of the metal strip 1 and the surface 22 of the cooling table 14 and also of the strand wiper 10.
• strips 24 or similar structures are preferably provided in order to achieve a throttling effect, so that the gas consumption when generating a gas cushion between the metal strip 1 and the strand support device 9 can be kept low.
• the invention allows changes in the casting performance (changes in strip thickness 2 and / or changes in casting speed) to be taken into account and to continue casting without problems.
• the gas passage channels 21 are arranged obliquely, u.zw. such that an air flow moving in the direction of extrusion (casting direction) 25 is formed when the gas passage channels 21 are pressurized.
• the invention is not limited to the embodiment shown in the drawing, but can be modified in various ways.
• a strictly horizontal alignment of the strand support device 9 is not necessary; it only has to be ensured that a tape can be formed with a desired thickness.
• some of the gas passage channels can be connected to a separate gas delivery device, so that gas can be supplied or sucked off at different intensities over the length of the strand support device 9. It is also conceivable to apply gas overpressure to some of the gas passage channels and, at the same time, to apply gas negative pressure to other gas passage channels.

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• 1995
  • 1995-02-23 AT AT0033195A patent/AT402266B/de not_active IP Right Cessation
• 1996
  • 1996-02-22 CA CA002213630A patent/CA2213630A1/en not_active Abandoned
  • 1996-02-22 WO PCT/AT1996/000027 patent/WO1996026028A1/de not_active Application Discontinuation
  • 1996-02-22 BR BR9607314A patent/BR9607314A/pt not_active Application Discontinuation
  • 1996-02-22 EP EP96901639A patent/EP0810909A1/de not_active Withdrawn
  • 1996-02-22 JP JP8525234A patent/JPH11500359A/ja active Pending
  • 1996-02-22 KR KR1019970705908A patent/KR19980702508A/ko not_active Application Discontinuation

Non-Patent Citations (1)

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