WO1995013154A1 - Procede et dispositif de ralentissement du deplacement d'un bain de fusion lors d'un coulage dans un moule - Google Patents

Procede et dispositif de ralentissement du deplacement d'un bain de fusion lors d'un coulage dans un moule Download PDF

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Publication number
WO1995013154A1
WO1995013154A1 PCT/SE1994/001000 SE9401000W WO9513154A1 WO 1995013154 A1 WO1995013154 A1 WO 1995013154A1 SE 9401000 W SE9401000 W SE 9401000W WO 9513154 A1 WO9513154 A1 WO 9513154A1
Authority
WO
WIPO (PCT)
Prior art keywords
melt
mould
copper plates
magnetic field
casting
Prior art date
Application number
PCT/SE1994/001000
Other languages
English (en)
Inventor
Magnus HALLEFÄLT
Sten Kollberg
Anders Lehman
Göte Tallbäck
Original Assignee
Asea Brown Boveri Ab
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 Asea Brown Boveri Ab filed Critical Asea Brown Boveri Ab
Priority to AU10369/95A priority Critical patent/AU1036995A/en
Priority to JP7513753A priority patent/JPH09504999A/ja
Priority to EP95900962A priority patent/EP0728051A1/fr
Publication of WO1995013154A1 publication Critical patent/WO1995013154A1/fr

Links

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
    • B22D11/10—Supplying or treating molten metal
    • B22D11/11—Treating the molten metal
    • B22D11/114—Treating the molten metal by using agitating or vibrating means
    • B22D11/115—Treating the molten metal by using agitating or vibrating means by using magnetic fields

Definitions

  • the present invention relates to a method and a device for braking the flow of liquid metal, melt, in the non-solidified portions of a cast strand during continuous casting of metals.
  • the melt is braked by generating a static magnetic field adjacent to a mould used for forming the metal.
  • the liquid metal which moves in the magnetic field gives rise to induced currents in the melt, which together with the magnetic field give rise to a braking force.
  • melt flows, directly or through a casting pipe, into a mould.
  • the melt is cooled and a solidified, self-supporting surface layer is formed before the strand leaves the mould. If incoming melt is allowed to flow into the mould in an uncontrolled manner, it will penetrate deep down into the non-solidified portions of the strand. This renders difficult the separation of particles contained in the melt, which will adhere to the solidification front instead of being separated to the top surface.
  • the self-supporting surface layer is weakened, which increases the risk of the melt breaking through the surface layer formed in the mould.
  • the cast strand is formed by the melt running down into the mould which is open downwards.
  • the cast strand which after the mould shall have a substantially rectangular cross section, is formed by allowing the melt to flow into a pipe ⁇ like casting mould, located in the mould, with a correspon ⁇ ding rectangular cross section.
  • the walls of the casting mould consist of four separate copper plates. Two of the copper plates constitute the long sides of the mould and the other two copper plates constitute the short sides of the mould. By changing the position of the copper plates which constitute the short sides of the mould, the width of the cast strand may be changed. hen the mould is closed, the copper plates are in contact with each other, which means that all potential differences, if any, between the copper plates are equalized.
  • a static or periodic low-frequency magnetic field is generated with permanent magnets or d.c.-fed induction coils, and are adapted to act across the inflowing melt, in parallel with the short sides of the mould.
  • the melt which moves at a velocity (v) in the magnetic field (B) gives rise to induced currents (i) in the melt.
  • the current density and direction of the induced currents in the melt are calculated by means of the following equation:
  • the induced current is given a direction which is perpendicular to the plane which is formed by the vectors v and B, that is, substantially in parallel with the long sides of the copper plates.
  • these currents are forced to become deflected downwards parallel to the short sides, that is, in the same direction as that in which the melt is moving.
  • One object of the invention is to suggest a method and a device for obtaining an even braking of the melt along the whole width of the mould, and to prevent the occurrence of unbraked flow channels along the short sides of the mould.
  • the invention relates to a method and a device for braking the movement of a melt in non-solidified portions of a cast strand during casting of metal.
  • Melt flows into a mould which comprises four copper plates which form a casting mould, open in the direction of casting, with a substantially rectangular cross section.
  • a static or periodic low-frequency magnetic field is generated across the path of the inflowing melt, whereby electric currents are induced in the melt.
  • two opposite copper plates are electrically insulated from each other, and the induced currents are returned via an external return conductor which is connected between the insulated copper plates.
  • the induced currents, together with the magnetic field, give rise to a force which acts in such a direction that the movement of the melt is braked.
  • the induced currents are prevented from being deflected downwards along the short sides of the mould, but instead the induced currents continue straight out through the copper plates.
  • the force which the induced currents produce then becomes directed upwards, against the direction of flow of the melt, along the whole width of the mould.
  • the unbraked flow channels along the short sides of the mould can no longer arise.
  • Figures la-Id schematically show a device for casting of molten metal according to the prior art.
  • Figures 2a-2d schematically show a device for casting of molten metal according to the invention.
  • Figure 3 schematically shows an embodiment of the invention for casting in a plurality of moulds with a substantially square cross section.
  • Figure la shows a device for casting of metal according to the prior art in a horizontal section.
  • a mould 1 comprises four copper plates, two of the plates 2 constituting the short sides of the mould and the other two plates 3 consti ⁇ tuting the long sides of the mould. When the mould is closed, the copper plates are in contact with each other.
  • Liquid metal, melt is supplied to the mould through a casting pipe 4.
  • Magnets placed on either side of the melt generate a magnetic field, the flux lines 5 of which are parallel to the short sides of the mould.
  • the magnets each comprise a core 6 and a coil 7 wound around the core.
  • the magnetic field acts around the whole width of the mould.
  • Figure lb shows the device in Figure la in a section A-A.
  • the magnetic field generated by the magnets acts in region 8.
  • the figure shows how an incoming primary flow of melt has been divided up into several flow channels.
  • the flow in the down- wardly directed channels 9 which are arranged adjacent the short sides of the mould is not influenced by the magnetic field and is therefore allowed to continue unbraked down into the melt.
  • the other flows 10 are braked by the magnetic field.
  • Figures lc and Id show the electric currents which are induced in the melt.
  • the currents are induced in a direction which is perpendicular to both the magnetic field and the inflowing melt, that is, parallel to the long sides of the copper plates in a horizontal direction.
  • the currents 11 are forced to become deflected parallel to the short sides.
  • the induced currents in the melt, together with the magnetic field, give rise to a force.
  • the force is directed opposite to the flow direction of the melt and will therefore brake the melt, but at the short sides of the mould, where the induced currents are deflected, the force is directed outwards towards the short side and therefore has no braking effect on the move ⁇ ment of the melt. In this way, the downwardly directed flow channels 9 arise along the short sides of the mould.
  • Figure 2a shows a device for casting of metal according to the invention.
  • An electrical insulation 12 is arranged between each of the copper plates.
  • the insulation must be of a material which withstands the wear which arises when the copper plates of the short side change position in connection with the width of the cast strand being changed.
  • the insula- tion may, for example, consist of a plastic layer.
  • the insulation allows the short sides of the mould to have different potential.
  • the currents induced in the melt are returned via an external return conductor 13.
  • the return conductor is connected to two opposite copper plates 2 included in the mould, which are parallel to the magnetic field 5. In this way, the induced currents are conducted out through the copper plates on the short sides of the mould, instead of being deflected downwards along the short sides as before.
  • the return conductor 13 comprises an external current source 15.
  • the induced currents in the melt increase, which increases the braking force.
  • Figures 2c and 2d show the induced currents in the melt.
  • the force which the induced currents produce is directed upwards, against the flow direction of the melt, along the whole width of the mould ( Figure 2d) .
  • the unbraked flow channels along the short sides of the mould disappear because of the upwardly-directed braking forces 14.
  • Figure 2b shows the flow of the melt in a device according to the invention.
  • the advantages of connecting an external current source are, for one thing, that the braking force can be increased with an unchanged magnetic field, and, for another, that the braking force may be maintained unchanged with a reduced magnetic field. If a smaller magnetic field is sufficient, the magnets may be made smaller.
  • FIG. 3 shows an embodiment of the invention which is applicable to casting in a plurality of moulds at the same time.
  • Four moulds 20a, 20b, 20c, 20d are arranged adjacent to each other.
  • Each one of the moulds comprises two pairs of opposite copper plates 2, 3.
  • the moulds have a substantially square cross section.
  • an electrical insulation 12 is arranged between each one of the copper plates in the mould.
  • magnets are arranged for generating a magnetic field in the melt.
  • Each magnet comprises a core 6 and a coil 7 wound around the core.
  • Each one of the four moulds are connected in the closed circuit which is formed by the return conductor 13.
  • Each mould e.g. 20a
  • the return conductor 13 is common to all four moulds.
  • An external current source 15 is connected to the return conductor 13.

Abstract

L'invention concerne un procédé et un dispositif de ralentissement du déplacement d'un bain de fusion dans les parties non solidifiées d'une ligne de coulée continue au cours du coulage de métal. Le bain de fusion s'écoule dans un moule qui comprend quatre plaques en cuivre (2, 3) formant un moule de fonte s'ouvrant vers le bas de section relativement rectangulaire. Un champ magnétique basse fréquence statique ou périodique (5) est généré dans le chemin de coulée entrant du bain de fusion, de sorte que des courants électriques sont induits dans ce dernier. Deux plaques en cuivre opposées (2) sont isolées électriquement l'une de l'autre, et les courants induits sont renvoyés par un conducteur de retour externe (13) connecté entre les deux plaques isolées (2). Les courants induits conjointement avec le champ magnétique donnent naissance à une force agissant dans une certaine direction de manière à ralentir le déplacement du bain de fusion sur toute la largeur du moule.
PCT/SE1994/001000 1993-11-10 1994-10-25 Procede et dispositif de ralentissement du deplacement d'un bain de fusion lors d'un coulage dans un moule WO1995013154A1 (fr)

Priority Applications (3)

Application Number Priority Date Filing Date Title
AU10369/95A AU1036995A (en) 1993-11-10 1994-10-25 Method and device for braking the movement of a melt during casting in a mould
JP7513753A JPH09504999A (ja) 1993-11-10 1994-10-25 型内での鋳造中に溶融体の運動を制動する方法および装置
EP95900962A EP0728051A1 (fr) 1993-11-10 1994-10-25 Procede et dispositif de ralentissement du deplacement d'un bain de fusion lors d'un coulage dans un moule

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
SE9303699-4 1993-11-10
SE9303699A SE501935C2 (sv) 1993-11-10 1993-11-10 Sätt och anordning för att bromsa en smältas rörelse vid gjutning i kokill

Publications (1)

Publication Number Publication Date
WO1995013154A1 true WO1995013154A1 (fr) 1995-05-18

Family

ID=20391693

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/SE1994/001000 WO1995013154A1 (fr) 1993-11-10 1994-10-25 Procede et dispositif de ralentissement du deplacement d'un bain de fusion lors d'un coulage dans un moule

Country Status (6)

Country Link
EP (1) EP0728051A1 (fr)
JP (1) JPH09504999A (fr)
CN (1) CN1134678A (fr)
AU (1) AU1036995A (fr)
SE (1) SE501935C2 (fr)
WO (1) WO1995013154A1 (fr)

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0665073A2 (fr) * 1994-01-28 1995-08-02 AEG - Elotherm GmbH Coquille pour la coulée continue
EP0807478A1 (fr) * 1996-05-13 1997-11-19 DANIELI & C. OFFICINE MECCANICHE S.p.A. Procédé et dispositif de coulée continue à champ életromagnétique pulsatoire

Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
SE443307B (sv) * 1982-04-16 1986-02-24 Asea Ab Strenggjutningskokill
WO1993005907A1 (fr) * 1991-09-25 1993-04-01 Kawasaki Steel Corporation Procede pour le coulage en continu de brames d'acier grace a l'utilisation d'un champ electromagnetique

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
SE443307B (sv) * 1982-04-16 1986-02-24 Asea Ab Strenggjutningskokill
WO1993005907A1 (fr) * 1991-09-25 1993-04-01 Kawasaki Steel Corporation Procede pour le coulage en continu de brames d'acier grace a l'utilisation d'un champ electromagnetique
EP0568699A1 (fr) * 1991-09-25 1993-11-10 Kawasaki Steel Corporation Procede pour le coulage en continu de brames d'acier grace a l'utilisation d'un champ electromagnetique

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0665073A2 (fr) * 1994-01-28 1995-08-02 AEG - Elotherm GmbH Coquille pour la coulée continue
EP0665073A3 (fr) * 1994-01-28 1997-01-29 Aeg Elotherm Gmbh Coquille pour la coulée continue.
EP0807478A1 (fr) * 1996-05-13 1997-11-19 DANIELI & C. OFFICINE MECCANICHE S.p.A. Procédé et dispositif de coulée continue à champ életromagnétique pulsatoire
US5988261A (en) * 1996-05-13 1999-11-23 Danieli & C. Officine Meccaniche Spa Continuous casting method and relative crystalliser for continuous casting

Also Published As

Publication number Publication date
JPH09504999A (ja) 1997-05-20
SE501935C2 (sv) 1995-06-26
CN1134678A (zh) 1996-10-30
EP0728051A1 (fr) 1996-08-28
SE9303699D0 (sv) 1993-11-10
AU1036995A (en) 1995-05-29
SE9303699L (sv) 1995-05-11

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