EP0384174A2 - Méthode de surveillance du procédé de solidification dans la coulée continue - Google Patents

Méthode de surveillance du procédé de solidification dans la coulée continue Download PDF

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Publication number
EP0384174A2
EP0384174A2 EP90101969A EP90101969A EP0384174A2 EP 0384174 A2 EP0384174 A2 EP 0384174A2 EP 90101969 A EP90101969 A EP 90101969A EP 90101969 A EP90101969 A EP 90101969A EP 0384174 A2 EP0384174 A2 EP 0384174A2
Authority
EP
European Patent Office
Prior art keywords
continuous casting
sensor coils
monitoring
solidification process
levitation coil
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.)
Granted
Application number
EP90101969A
Other languages
German (de)
English (en)
Other versions
EP0384174B1 (fr
EP0384174A3 (fr
Inventor
Andreas Dr.-Ing. Krause
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
KM Kabelmetal AG
Original Assignee
KM Kabelmetal AG
Priority date (The priority date 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 date listed.)
Filing date
Publication date
Application filed by KM Kabelmetal AG filed Critical KM Kabelmetal AG
Priority to AT90101969T priority Critical patent/ATE93424T1/de
Publication of EP0384174A2 publication Critical patent/EP0384174A2/fr
Publication of EP0384174A3 publication Critical patent/EP0384174A3/fr
Application granted granted Critical
Publication of EP0384174B1 publication Critical patent/EP0384174B1/fr
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

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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
    • B22D11/145—Plants for continuous casting for upward 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
    • B22D11/16—Controlling or regulating processes or operations
    • B22D11/18—Controlling or regulating processes or operations for pouring
    • B22D11/181—Controlling or regulating processes or operations for pouring responsive to molten metal level or slag level
    • B22D11/186—Controlling or regulating processes or operations for pouring responsive to molten metal level or slag level by using electric, magnetic, sonic or ultrasonic means

Definitions

  • the invention relates to a method according to the preamble of patent claim 1.
  • a casting process also known as upward casting, which permits the continuous production of metal strands from the melt, is known, for example, from DE-A-30 49 353. It is essential for this casting process that a certain section of a water-cooled mold or the solidifying metal column located inside the mold is concentrically surrounded by a special induction coil, the so-called levitation coil.
  • This levitation coil generally consists of a larger number, for example 6, of winding groups arranged one above the other, which are coupled to one another in such a way that an upward moving alternating electromagnetic field is formed within the levitation coil as soon as the levitation coil is excited by a three-phase voltage source.
  • the magnetic field of the levitation coil induces eddy currents in the molten metal.
  • the radial and axial components of the magnetic induction generated by the levitation coil have the effect that forces are generated in the axial direction (upward) and in the radial direction on the liquid or already solidified metal through which the eddy currents flow. These forces ensure that the pressure of the melt and the strand shell on the mold wall are reduced and an increase in the casting speed can be achieved by lower frictional forces.
  • the invention is therefore based on the object of specifying a measuring method with which the position and extent of the solidification front can be identified in a simple manner and with sufficient accuracy during the casting process.
  • the invention is based essentially on the knowledge that the electrical conductivity of metals increases during the transition from the molten to the solid state and with decreasing temperature.
  • the electrical conductivity at the solidification point suddenly increases to a significantly higher value than in the molten state.
  • the electrical conductivity also increases significantly in the temperature range at which the metal alloy solidifies.
  • the temperature of the melt decreases with increasing height due to the progressive heat removal within the continuous casting mold.
  • the proportion of solidified metal increases until the central metal column is completely solidified.
  • the distribution of the electrical conductivity changes specifically within the central metal column. This makes it possible Assign a characteristic conductivity distribution to each cross-sectional plane of the mold perpendicular to the direction of movement of the strand.
  • the area of cooling and solidification of the melt within the mold has spread far apart.
  • the length of this area for example when casting round solid profiles, is a multiple of the strand diameter. Accordingly, the conductivity distribution changes slowly over the length of the mold.
  • An essential feature of upward casting is that almost the entire mold length is surrounded by a levitation coil.
  • the excitation frequency is chosen so that the penetration depth of the magnetic field and the strand radius are of the same order of magnitude. This ensures that the outer area of the strand cross-section, in which the solidification begins and which is of interest for the control of the casting process, is penetrated to a sufficient extent by the field of excitation.
  • a secondary field is generated by the eddy currents, which can provide information about the conductivity distribution within the metal column.
  • the continuous casting mold consists, for example, of a tubular body, around which a heat exchanger is arranged in a ring. Since the walls of the heat exchanger and the mold are relatively thin and are made of materials that weaken the magnetic field of the levitation coil as little as possible with high thermal conductivity, the secondary field is also only slightly weakened.
  • the sensor coils arranged concentrically around the central column of the molten metal or the already solidified metal deliver signals (measuring voltages) to a transmitter via the secondary field. After appropriate evaluation of these signals, it is possible to make statements about the position and extent of the solidification front and to control the solidification process directly during the casting process. Fluctuations or changes in the solidification process, which may be noticeable in the increased occurrence of irregularities in the area of the strand cross section near the surface, are thus recognized at a stage before the strand reaches the exit area of the mold.
  • the sensor coils are particularly advantageously located inside the levitation coil and outside the continuous casting molds.
  • the windings of the sensor coil then have a diameter that lies between the inside diameter of the levitation coil and the outside diameter of the continuous casting mold.
  • the sensor coils can also be arranged in the space between the levitation coil and the heat exchanger wall or in the mold lining.
  • the sensor coils preferably consist of one or more turns of a thin insulated wire.
  • the wire is spirally wound in several turns on the outer surface of the heat exchanger outer wall in one or more layers as closely as possible.
  • the two wire ends of each sensor coil are led to a transmitter, which processes the voltage signal occurring at the wire ends during operation in a suitable manner.
  • the voltage induced in each sensor coil by the alternating field of the levitation coil is a function of the frequency, the current intensity of the current flowing through the levitation coil and the conductivity distribution within the central metal column. Furthermore, the induced voltage is dependent on the geometry of the sensor coils and levitation coil as well as their arrangement to one another.
  • the cooling of the liquid or solidified metal column leads to an increase in conductivity.
  • This increase in conductivity is indicated by a decrease in the amplitude of the measuring voltage while the excitation field strength remains the same.
  • the cause of the change in a measurement signal cannot be clearly identified if only a single sensor coil is used. Therefore, at least two sensor coils are preferably arranged one above the other and the measuring voltages supplied to the transmitter are compared with each other.
  • the measurement voltage which occurs when the metal is in the molten state is expediently chosen as the reference signal.
  • the further cooling of the strand above a temperature at which the solidification begins then only leads to a relatively small decrease in the voltage amplitude at a sensor coil during the temperature changes usually occurring during the casting process, while the entire course of the solidification by a significantly more pronounced drop in the voltage amplitude is marked.
  • the conductivity distribution during the cooling and solidification of the melt within the continuous casting mold results in a profile of measuring voltages on the sensor coils arranged one above the other, with which the position and the extent of the solidification front can be determined with sufficient accuracy. In this way, an uneven solidification course during the casting process can be recognized immediately.
  • An impermissible migration of the solidification front from the desired position in the casting direction can be recognized by the fact that the measuring voltages which are fed to the transmitter from the sensor coils arranged further in the casting direction have higher values.
  • a short-term sticking of the still thin strand shell deviating from normal operation at a certain position within the continuous casting mold is manifested, for example, by a significant drop in the measuring voltage in the sensor coil responsible for the location of the fault.
  • Another advantage of the method according to the invention is that even casting errors, such as cracks, can be identified from the comparison of the measurement signals of a plurality of sensor coils before the strand has left the mold and larger quantities of defective material have been generated.
  • the figure shows a schematic representation of a cross section through a tubular continuous casting mold 1 arranged in an upright position, which is surrounded by a heat exchanger 3 in an annular manner for cooling the liquid metal 2.
  • Coolant with a high flow rate is continuously fed in at the coolant inlet 4, flows through the heat exchanger 3 and is discharged again in the upper part of the heat exchanger 3 at the coolant outlet 5.
  • the levitation coil is designated by 6, the turns of which are arranged essentially perpendicular to the axis of the continuous casting mold 1 between the coolant inlet 4 and the coolant outlet 5 and are connected to a multiphase voltage source, not shown.
  • the alternating electromagnetic field of the levitation coil 6 induces eddy currents in the liquid metal 2, which cause the metal column 7 and the liquid metal to experience an upward lifting effect.
  • sensor coils 8 are arranged one above the other such that their distance from the outer wall of the heat exchanger 3 is the same.
  • 6 sensor coils 8 are shown, the measurement voltage profile of which permits overall sufficient information about the course of the solidification front 9. For higher demands on the accuracy of the identification of the position and extent of the solidification front 9, it is advantageous to provide sensor coils 8 at a distance of at least 1 cm.
  • the levitation coil 6 and the sensor coils 8 have a concentric position around the cylindrical continuous casting mold 1, the inside diameter of which is approximately 20 mm.
  • the sensor coils 8 are each arranged within the levitation coil 6 at a height at which the mean turn of each turn group is located, which is excited with the same phase in each case.
  • the diameter of the levitation coil 6 is approximately 41 mm, while the turns of an excitation phase have a height of 24 mm.
  • the excitation frequency was 2,000 Hz.
  • Each of the 6 sensor coils 8, which are wound from 8 turns of a thin insulated copper wire has a diameter of approximately 35 mm.
  • the effective values in the vicinity of the solidification front 9 were in the range from 86 to 95%.

Landscapes

  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Continuous Casting (AREA)
  • Investigating Or Analyzing Materials By The Use Of Magnetic Means (AREA)
  • Feeding, Discharge, Calcimining, Fusing, And Gas-Generation Devices (AREA)
EP90101969A 1989-02-23 1990-02-01 Méthode de surveillance du procédé de solidification dans la coulée continue Expired - Lifetime EP0384174B1 (fr)

Priority Applications (1)

Application Number Priority Date Filing Date Title
AT90101969T ATE93424T1 (de) 1989-02-23 1990-02-01 Verfahren zur ueberwachung des erstarrungsvorgangs beim kontinuierlichen stranggiessen.

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
DE3905516 1989-02-23
DE3905516A DE3905516A1 (de) 1989-02-23 1989-02-23 Verfahren zur ueberwachung des erstarrungsvorgangs beim kontinuierlichen stranggiessen

Publications (3)

Publication Number Publication Date
EP0384174A2 true EP0384174A2 (fr) 1990-08-29
EP0384174A3 EP0384174A3 (fr) 1991-03-06
EP0384174B1 EP0384174B1 (fr) 1993-08-25

Family

ID=6374702

Family Applications (1)

Application Number Title Priority Date Filing Date
EP90101969A Expired - Lifetime EP0384174B1 (fr) 1989-02-23 1990-02-01 Méthode de surveillance du procédé de solidification dans la coulée continue

Country Status (8)

Country Link
US (1) US5042559A (fr)
EP (1) EP0384174B1 (fr)
JP (1) JP2948607B2 (fr)
AT (1) ATE93424T1 (fr)
CA (1) CA2009758C (fr)
DE (2) DE3905516A1 (fr)
ES (1) ES2045586T3 (fr)
FI (1) FI90507C (fr)

Families Citing this family (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE19843354C1 (de) * 1998-09-22 2000-03-09 Ald Vacuum Techn Gmbh Vorrichtung zum gerichteten Erstarren einer in eine Formschale gegossenen Metallschmelze sowie ein Verfahren hierzu
US7010835B2 (en) * 2001-10-24 2006-03-14 Tillim Stephen L Parallel handle system and method for designing a parallel handle system
US10022787B2 (en) 2015-08-24 2018-07-17 Retech Systems, Llc Method and system for sensing ingot position in reduced cross-sectional area molds

Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4030533A (en) * 1974-06-24 1977-06-21 Nippon Steel Corporation Continuous casting system
GB2061783A (en) * 1979-10-31 1981-05-20 Asea Ab Electromagnetic stirring in continuous casting
DE3049353A1 (de) * 1980-07-02 1982-02-04 General Electric Co., Schenectady, N.Y. "verfahren zur herstellung eines metallgegenstandes von grosser laengenausdehnung durch kontinuierliches giessen und vorrichtung zur durchfuehrung des verfahrens"
EP0098214A1 (fr) * 1982-06-28 1984-01-11 Institut De Recherches De La Siderurgie Francaise (Irsid) Procédé de brassage électromagnétique des métaux, notamment des aciers, coulés en continu et dispositif de mise en oeuvre
JPS60133955A (ja) * 1983-12-20 1985-07-17 Sumitomo Metal Ind Ltd 連続鋳造の電磁撹拌方法

Family Cites Families (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4495983A (en) * 1980-04-07 1985-01-29 Olin Corporation Determination of liquid-solid interface and head in electromagnetic casting
US4414285A (en) * 1982-09-30 1983-11-08 General Electric Company Continuous metal casting method, apparatus and product
US4796687A (en) * 1987-07-10 1989-01-10 Olin Corporation Liquid/solid interface monitoring during direct chill casting

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4030533A (en) * 1974-06-24 1977-06-21 Nippon Steel Corporation Continuous casting system
GB2061783A (en) * 1979-10-31 1981-05-20 Asea Ab Electromagnetic stirring in continuous casting
DE3049353A1 (de) * 1980-07-02 1982-02-04 General Electric Co., Schenectady, N.Y. "verfahren zur herstellung eines metallgegenstandes von grosser laengenausdehnung durch kontinuierliches giessen und vorrichtung zur durchfuehrung des verfahrens"
EP0098214A1 (fr) * 1982-06-28 1984-01-11 Institut De Recherches De La Siderurgie Francaise (Irsid) Procédé de brassage électromagnétique des métaux, notamment des aciers, coulés en continu et dispositif de mise en oeuvre
JPS60133955A (ja) * 1983-12-20 1985-07-17 Sumitomo Metal Ind Ltd 連続鋳造の電磁撹拌方法

Non-Patent Citations (2)

* Cited by examiner, † Cited by third party
Title
FOUNDRY, Band 13, Nr. 3, M{rz 1980, Zusammenfassung Nr. 51-0321; "Improved system for measuring molten steel level in mold of CCÄcontinious castingÜ machine", & NKK NEWS, April 1979, 19, (3), 1.3 *
PATENT ABSTRACTS OF JAPAN, vol. 9, no. 297 (M-432)[2020], 25. November 1985; & JP-A-60 133 955 (SUMITOMO) 17-07-1985 *

Also Published As

Publication number Publication date
JP2948607B2 (ja) 1999-09-13
CA2009758C (fr) 1995-12-05
FI90507C (fi) 1994-02-25
FI90507B (fi) 1993-11-15
FI900445A0 (fi) 1990-01-29
DE59002415D1 (de) 1993-09-30
ATE93424T1 (de) 1993-09-15
DE3905516A1 (de) 1990-08-30
ES2045586T3 (es) 1994-01-16
CA2009758A1 (fr) 1990-08-23
EP0384174B1 (fr) 1993-08-25
US5042559A (en) 1991-08-27
EP0384174A3 (fr) 1991-03-06
JPH02235560A (ja) 1990-09-18

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