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
  • B22D11/14—Plants for continuous casting
• • 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
  • B22D11/12—Accessories for subsequent treating or working cast stock in situ
  • B22D11/128—Accessories for subsequent treating or working cast stock in situ for removing

Definitions

• the invention relates to a process for the continuous casting of thin slabs with casting speeds greater than 3 m / min. in a continuous caster, in which the melt is passed into a mold via a submerged spout, which can be closed by a shut-off element, which is followed by a strand guide equipped with rollers.
• the invention further relates to a continuous caster for performing the method.
• the strand Under the ferrostatic pressure of the molten steel, the strand may bulge when casting slabs, ie. after leaving the mold, the strand shell undergoes a series of bulging and rolling deformations, but bulging is restricted by the support rollers of the strand guide frame arranged downstream of the mold.
• At least one of the roller tracks on the frame part is arranged so as to be displaceable in the longitudinal direction of these roller tracks and fixed on the frame part in different positions.
• the construction proposed here is intended, inter alia, to prevent an inadmissible bulging of the strand shell while maintaining the same distance as possible between the end rollers of adjacent frame parts. This document therefore deals exclusively with the constructive construction of a continuous caster.
• the melt is usually passed into an oscillating mold via a submerged nozzle.
• the inflow quantity is adjusted regularly via a stopper or slide closure arranged at the inlet of the immersion spout.
• the level of the melt in the mold is measured and used via an EDP-supported measuring and control device to change the stopper position in the closure, thereby compensating for an up and down movement of the bath surface.
• the invention has for its object to provide a method and a system for the continuous casting of thin slabs, by which or by actively avoiding an uncontrolled swinging up of the casting level in the mold and, moreover, the slab quality is improved by reducing the center drop.
• the minimal force acting on the upper and lower broad side of the strand shell of a slab is achieved by choosing a different arrangement of the opposing rollers in the area of the elastic behavior of the strand shell than in the plastic region of the strand shell. It is hereby achieved that after the transition phase, the strand, which is becoming more and more solid, winds through the strand guide. In this way it is avoided that bulges or indentations impressed into the strand shells at the same time on the top and bottom of the strand shell box simultaneously strike the supporting guide rollers. A simultaneous compression of two bulges would lead to a "pumping" and a simultaneous impact of two indentations would lead to a "suction" of the sump enveloped by the strand shell box. Since the only opening of the strand shell box is in the mold during casting, the casting level there is then caused to vibrate.
• the required to avoid the swing movement of the rollers is in the range of translation a of a size between 0.1 to 0.5 xl R, where R l is the roller pitch in mm.
• Transition area from plastic to elastic behavior of the strand shell carried out is advantageously set by the amount, type and location of external cooling. Overall, the transition area depends on the casting speed and the temperature profile and also on the shell thickness, the length of the sump Steel grade, ie. their chemical composition, the mold exit dimension and the design of the continuous caster, and here in particular the strand width and the roll division.
• the transition area from the plastic to the elastic behavior of the strand shell can be found in every frame of the strand guiding device.
• a continuous casting installation is proposed in which the guide frame is divided into three zones, the guide rollers in the starting zone having a different association to one another than in the end zone arranged after a transition zone.
• the individual zones can already be arranged in the first framework.
• the individual zones of the roll allocation can be permanently installed.
• the guide frame in the transition zone is structurally designed so that the same number of guide rollers is provided in the upper frame and in the lower frame and that the positioning of the guide rollers of the lower frame is carried out continuously variable along the strand.
• an additional guide roller can be provided, which can be positioned in the subframe in addition to the existing guide rollers.
• a cooling device is provided, which is installed in the area in which the plastic behavior of the strand shell usually occurs and whose quantity, shape and temperature of the cooling medium can be set.
• a complete suppression of the uncontrolled swinging up of the casting level in the mold is achieved if the stopper control has a natural frequency that is outside the resonance frequency of the pumping frequency of the liquid column and thus outside the frequency of pumping the strand shell.
• FIG. 1 shows a schematic view of the continuous caster
• Figure 2a, 2b are schematic representations of the area of plastic
• Figure 3a, 2b shows the arrangement of the guide rollers in the area of the elastic behavior of the strand shell
• Figure 4 is a schematic representation of a guide roller area
• FIG. 1 shows a melt supply vessel 43, the bottom opening of which can be closed by a stopper 44 which is connected to a stopper control 45.
• An immersion spout 42 which projects into a mold 41, is fastened to the melt supply vessel 43.
• the mold 41 is followed by individual segments having scaffolds 12, 22, 32 corresponding to an initial zone 11, a transition zone 21 and an end zone 31.
• the start and transition zones 11 and 21 respectively extend over a relatively wide area, which is followed by the end zone 31.
• the starting zone 11 and the transition zone 21 can already be present in the first framework, so that the end zone 31 extends over the remaining area of strand guidance.
• the individual stands have guide rollers 13, 23, 33, which are arranged in the upper frame 14, 24, 34 and lower frame 15, 25, 35 (see FIG. 4).
• the slab B is shown schematically, whose bottom tip S s protrudes beyond the end zone 31. Furthermore, a cooling device 61 is indicated schematically in the end region of the starting zone 11.
• FIGS. 2a and 2b show guide rollers 13 in the area of the plastic behavior of the strand shell, in which a stationary waveform is molded.
• Thickness of the bulge is marked with D, the mouth width of the rollers with d.
• the guide rollers 13 are located directly opposite each other with the jaw width d and are at a distance from one another on the respective strand side, which is determined by the roller pitch l R.
• the strand shell W which includes the sump S, has indentations and bulges.
• the bulge D is smaller than the stationary bulge in the case of guide rollers 13 arranged opposite one another according to FIG. 2a.
• FIGS. 3a and 3b show the situation in the area of the elastic behavior of the strand shell, which is imprinted with an unsteady undulating surface shape.
• FIG. 3a a section through the strand shell box is shown schematically, in which the broad sides have indentations and bulges that lie opposite one another in mirror symmetry.
• the strand moves in the strand withdrawal direction through the guide frame in such a way that it meanders through the rollers, which are spaced apart from one another.
• the strand shell box is shaped like a double-walled corrugated sheet. During the pulling-off process of the strand, this corrugated sheet-shaped strand shell box moves through the guide frame in such a way that it also winds through the opposite guide rollers.
• FIG. 4 shows a frame 12, 22, 32 and an upper frame 14, 24, 34 and a lower frame 15, 25, 35 and guide rollers 13, 23, 33.
• An additional roller 19, 29, 39 is provided on the lower frame 15, 25, 35 which, after a translation of the lower guide rollers 13, 23, 33, can additionally be added to the row of these rollers, as shown in the lower part of FIG. 4, and as a result of which an offset arrangement of the opposite rollers 13, 23, 33 can be achieved .
• a translation of the guide rollers is also possible without the addition of a further roller 19, 29, 39, but then there is a gap to be observed in the row of the lower guide rollers.
• Means for carrying out the translation a are only indicated in the lower part of FIG. 4 by reference symbols 16, 26, 36
• a measuring element 74 for the pressure and a measuring element 75 for the position of the strand shell are shown, which are connected to actuators 71, 72, 73, which in turn act on hydraulic elements 18, 28, 38, by means of which the pressure on affected guide rollers can be kept essentially constant.

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• 1997
  • 1997-10-22 WO PCT/DE1997/002518 patent/WO1998020998A1/fr active IP Right Grant
  • 1997-10-22 AU AU71788/98A patent/AU7178898A/en not_active Abandoned
  • 1997-10-22 EP EP97948688A patent/EP0946318B1/fr not_active Expired - Lifetime
  • 1997-10-22 AT AT97948688T patent/ATE201342T1/de not_active IP Right Cessation

Non-Patent Citations (1)

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