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
  • B22D11/16—Controlling or regulating processes or operations
  • B22D11/161—Controlling or regulating processes or operations for automatic starting the casting process
• • 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
  • B22D11/147—Multi-strand plants
• • 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
  • B22D11/16—Controlling or regulating processes or operations

Definitions

• the invention relates to a method for the automatic vertical continuous casting of metals, in particular aluminum alloys, in a casting installation comprising several molds, in which method the liquid metal is fed from a furnace to the molds via a casting trough and via nozzles with a controllable flow rate into the closed molds are initially guided on a lowerable casting table, whereby the metal flow rate of each nozzle, based on an initial time and an initial level of the metal at which the metal level control begins, is individually regulated in each mold so that the metal in all molds has a substantially identical starting level at a predetermined starting time, at which the lowering of the casting table for producing the metal strands begins.
• Controlling the start-up process is decisive for the trouble-free operation of a multi-strand casting system, i.e. the optimal control of the metal supply to the individual casting units until the actual casting start, which is initiated by lowering the casting table.
• the metal supply to the individual molds is usually regulated individually via nozzles assigned to them, the metal flow rate of which can be adjusted in a variable manner by means of a motor-driven plug rod.
• the metal level in each mold is continuously measured in a known manner using level measuring devices, compared with the setpoint specification and the speed of the metal feed into the mold is adjusted via the difference between the actual and setpoint by correspondingly controlling the plug rod drive in the associated nozzle.
• a metal level control for a multi-strand casting system is known, in which when a first metal level is reached in a mold, a setpoint value that increases linearly in time to a second level common to all molds is specified.
• the metal level in the individual molds is regulated on the basis of the increasing target value as soon as it is reached in the individual molds.
• EP-B-0517629 discloses a method of the type mentioned at the outset, in which the individual metal level control starts in each mold as soon as the inflowing metal has reached a predetermined minimum height above the respective approach floor. Starting from this minimum height above the approach floor, the level control takes place in each mold based on individual, linearly increasing setpoint curves, so that a predetermined, common level is achieved in all molds simultaneously.
• a major disadvantage of the methods according to the prior art with different filling curves for each mold is the risk that the system will get out of control if one of the molds does not fill or starts to fill up due to premature solidification of the molten metal.
• large differences in the filling kinetics when lowering the casting table can occur if individual molds fill too late and consequently show a steep filling curve towards the end of the filling process.
• the algorithm also becomes much more complicated.
• the invention is therefore based on the object of creating a method of the type mentioned at the outset, in which the metal level in the individual molds during the start-up base and mold filling phase is simple and in the shortest possible time for the start of the lowering of the casting table predetermined level can be regulated without the risk of freezing of metal.
• the part of the setpoint curve with the larger slope, starting from the initial level, preferably extends in a range of approximately 10 to 70%, preferably 30 to 60%, of the total level increase.
• the part of the setpoint curve with the smaller slope against the starting level preferably extends over a range of 10 to 40%, preferably 15 to 25%, of the total level increase.
• the setpoint curve is composed of 4 to 8, preferably 5 to 6, pairs of values.
• the metal level control in all molds begins simultaneously as soon as the initial level is reached in one mold.
• the lowering of the casting table with the approach floors also expediently begins as soon as the start level is reached in a mold.
• the metal level in the casting trough is also preferably kept at a constant level from the start of the filling phase of the start-up trays and the molds to and with the stationary casting phase.
• the metal feed into the molds based on the setpoint curve is preferably PID-controlled.
• - Fig.1 shows a simplified cross section through a
• Part of a mold with retracted approach floor 2 shows a setpoint curve of the time course of the metal level in the individual molds.
• the pouring channel is filled to a predetermined metal level by tilting the furnace containing the liquid metal.
• a sensor e.g. an inductive sensor - the correct fill level is displayed, a slide opens and the filling of the approach floors 12 and the molds 10 begins with the liquid metal 14.
• the metal level in the start-up floor 12 or in the mold 10 takes place e.g. PID controlled via an inductive sensor.
• the setpoint curve shown in FIG. 2 can be in a region A starting from the initial value N and in a subsequent region that runs against the starting level N rich B can be divided. It is readily apparent that area A of the setpoint curve has a larger slope than the mean slope - Ns —- rN — o. Accordingly, there is a smaller slope for area B.
• the setpoint curve is formed by 6 pairs of measured values N, t.
• the exemplary embodiment shown in the drawing relates to the continuous casting of an aluminum alloy in a conventional mold.
• the method according to the invention can also be used in other casting methods such as, for example, casting in an alternating electromagnetic field (EMC).
• EMC alternating electromagnetic field
• the process is also not limited to the casting of aluminum alloys.
• Other materials that can be cast into strands with the method according to the invention are e.g. Magnesium or copper alloys.

Landscapes

• Engineering & Computer Science (AREA)
• Mechanical Engineering (AREA)
• Continuous Casting (AREA)
• Treatment Of Steel In Its Molten State (AREA)
• Manufacture And Refinement Of Metals (AREA)

Priority Applications (1)

Applications Claiming Priority (4)

Publications (2)

Family

ID=8230140

Family Applications (2)

Family Applications Before (1)

Country Status (9)

Families Citing this family (3)

Family Cites Families (6)

• 1997
  • 1997-01-24 EP EP97810035A patent/EP0855238A1/fr not_active Withdrawn
• 1998
  • 1998-01-07 EP EP98900062A patent/EP0959995B1/fr not_active Expired - Lifetime
  • 1998-01-07 WO PCT/CH1998/000004 patent/WO1998032559A1/fr active IP Right Grant
  • 1998-01-07 AT AT98900062T patent/ATE211039T1/de not_active IP Right Cessation
  • 1998-01-07 DE DE59802528T patent/DE59802528D1/de not_active Expired - Fee Related
  • 1998-01-07 US US09/355,241 patent/US6260603B1/en not_active Expired - Fee Related
  • 1998-01-07 CA CA002277959A patent/CA2277959C/fr not_active Expired - Fee Related
  • 1998-01-07 AU AU53053/98A patent/AU716841B2/en not_active Ceased
• 1999
  • 1999-07-06 IS IS5111A patent/IS2026B/is unknown
  • 1999-07-22 NO NO993589A patent/NO993589L/no not_active Application Discontinuation

Non-Patent Citations (1)

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