EP0752194A1 - Four a creuset a induction comportant au moins deux bobines raccordees en parallele a un convertisseur de frequence a circuit oscillant - Google Patents

Four a creuset a induction comportant au moins deux bobines raccordees en parallele a un convertisseur de frequence a circuit oscillant

Info

Publication number
EP0752194A1
EP0752194A1 EP95913850A EP95913850A EP0752194A1 EP 0752194 A1 EP0752194 A1 EP 0752194A1 EP 95913850 A EP95913850 A EP 95913850A EP 95913850 A EP95913850 A EP 95913850A EP 0752194 A1 EP0752194 A1 EP 0752194A1
Authority
EP
European Patent Office
Prior art keywords
coils
capacitors
crucible
parallel
converter
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
EP95913850A
Other languages
German (de)
English (en)
Other versions
EP0752194B1 (fr
Inventor
Reinhold Hürtgen
Thomas Frey
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.)
Otto Junker GmbH
Original Assignee
Otto Junker GmbH
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 Otto Junker GmbH filed Critical Otto Junker GmbH
Publication of EP0752194A1 publication Critical patent/EP0752194A1/fr
Application granted granted Critical
Publication of EP0752194B1 publication Critical patent/EP0752194B1/fr
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

Links

Classifications

    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05B—ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL
    • H05B6/00—Heating by electric, magnetic or electromagnetic fields
    • H05B6/02—Induction heating
    • H05B6/06—Control, e.g. of temperature, of power
    • H05B6/067—Control, e.g. of temperature, of power for melting furnaces
    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05B—ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL
    • H05B6/00—Heating by electric, magnetic or electromagnetic fields
    • H05B6/02—Induction heating
    • H05B6/22—Furnaces without an endless core
    • H05B6/24—Crucible furnaces

Definitions

  • the invention relates to an induction crucible furnace with at least two coils connected in parallel to a load-guided oscillating-frequency converter, enclosing the circumference of a vertical crucible and positioned one behind the other in the direction of the crucible axis and connected in series with a capacitive resistor.
  • the upstream capacitive resistor has the purpose of bringing the resonant circuit into the range of the resonant vibration.
  • an ideal series resonant circuit with a coil of inductance vity L, a capacitor of capacitance C and a vanishing ohmic resistance.
  • the equation applies to the resonant frequency fo of the resonant circuit
  • the task is known to supply the melting material with a power density that increases or decreases in the axial direction in order to influence the movement of the melting bath.
  • a further example of a different power requirement in different crucible areas is given by a crucible which is only partially filled, as is the case, for example, during the charging of the crucible or possibly with a less than maximum possible amount of melting material.
  • the coils surrounding an empty crucible part cannot pass any power on to the melt.
  • the melting material acts like a core of the coil, with almost all types of melting materials reducing the inductance of the coil.
  • Such a reduction in inductance causes an increase in the resonance frequency fo in the corresponding resonant circuit according to equation (I).
  • a desired power distribution can also be brought about in accordance with the above by using a series resonant circuit converter whose operating frequency is slightly below the resulting resonance frequency of the entire system 1.
  • the prior art with regard to the preamble of claim 1 therefore has the particular disadvantage that when using a single capacitive resistor for several Induction coils connected in parallel, the voltage on the coils is the same in each case, an adaptation to the actual power requirement in the area of the respective coil is not possible.
  • the object of the invention is to be able to use simple means to determine an effective distribution of the power output by a resonant circuit converter to the individual coils.
  • the induction crucible furnace according to the invention can also be designed such that the capacitance of at least one of the capacitive resistors can be changed.
  • Possible capacitive resistors are capacitor units, which are composed of a single capacitor or else of several capacitors and, if appropriate, switching elements.
  • the individual capacitors can be connected to one another in different ways by switching elements, so that the total capacitance of the capacitor unit can be set to different values as required.
  • a variable capacitance has the advantage that the resonance frequency of an individual resonant circuit can also be adapted to changing process conditions, for example in the case of crucible loading, even during furnace operation.
  • the induction crucible furnace according to the invention can be designed such that an on / off switch is connected in series with at least one of the coils.
  • Fig. 1 shows an induction crucible furnace with two individual resonant circuits connected in parallel to a resonant circuit converter and
  • FIG. 2 shows a diagram to show the power consumption of an induction crucible furnace according to the invention, which is dependent on the level of the crucible, in comparison with the prior art.
  • FIG. 1 shows an induction crucible furnace, the crucible 2, which is only half filled with melting material 1, is surrounded by two coils 3, 4.
  • a capacitor 6, 7 is connected in series with each coil 3, 4, so that two separate individual oscillating circuits 8, 9 are created. These are connected to a parallel resonant circuit converter 5.
  • a capacitor 10 connected in parallel with the individual oscillating circuits 8, 9 serves to compensate for the reactive power.
  • the lower one Zelschwing Vietnamese 8 encloses a portion of the crucible 2 filled with melting material 1, the upper single oscillating circuit 9 an empty crucible part.
  • the capacitances of the capacitors 8, 9 are chosen to be the same size.
  • the resonance frequency of the lower individual resonant circuit 8 is closer to the operating frequency of the resonant circuit converter 5 than the resonant frequency of the upper individual resonant circuit 9. It follows that the power emitted by the coils 3, 4 is based on that with the melting material 1 filled part of the crucible 2 is concentrated.
  • the induction crucible furnace according to the invention brings about a higher power consumption by the furnace itself compared to the prior art when the crucible 2 is not completely filled. This fact is shown in the diagram in FIG. 2.
  • the ratio of the total power actually consumed by the PGES induction crucible to the nominal power of the furnace PN is plotted along the ordinate and the crucible fill level in percent along the abscissa.
  • Curve 11 shows the power ratio PGES / PN as a function of the crucible fill level for an induction crucible furnace, the individual coils of which are connected in parallel in accordance with the prior art. Accordingly, the power consumption drops as soon as the crucible fill level falls below 100%.
  • Curve 12 shows the corresponding power ratio in the case of an induction crucible furnace according to the invention. It can be seen that up to a crucible fill level of well below 50%, the power ratio remains almost constant at PGES / PN »1. Only at a crucible fill level of less than 103. do the two curves 11, 12 approach each other again. When the crucible 2 is not completely filled, the induction crucible furnace according to the invention thus also increases the power consumed by the furnace, which is passed on to the melting material 1.

Landscapes

  • Physics & Mathematics (AREA)
  • Electromagnetism (AREA)
  • Crucibles And Fluidized-Bed Furnaces (AREA)
  • General Induction Heating (AREA)
  • Furnace Details (AREA)
EP95913850A 1994-03-25 1995-03-18 Four a creuset a induction comportant au moins deux bobines raccordees en parallele a un convertisseur de frequence a circuit oscillant Expired - Lifetime EP0752194B1 (fr)

Applications Claiming Priority (3)

Application Number Priority Date Filing Date Title
DE4410436 1994-03-25
DE4410436 1994-03-25
PCT/DE1995/000376 WO1995026619A1 (fr) 1994-03-25 1995-03-18 Four a creuset a induction comportant au moins deux bobines raccordees en parallele a un convertisseur de frequence a circuit oscillant

Publications (2)

Publication Number Publication Date
EP0752194A1 true EP0752194A1 (fr) 1997-01-08
EP0752194B1 EP0752194B1 (fr) 1998-07-15

Family

ID=6513869

Family Applications (1)

Application Number Title Priority Date Filing Date
EP95913850A Expired - Lifetime EP0752194B1 (fr) 1994-03-25 1995-03-18 Four a creuset a induction comportant au moins deux bobines raccordees en parallele a un convertisseur de frequence a circuit oscillant

Country Status (5)

Country Link
US (1) US5940427A (fr)
EP (1) EP0752194B1 (fr)
AT (1) ATE168517T1 (fr)
DE (1) DE59502832D1 (fr)
WO (1) WO1995026619A1 (fr)

Families Citing this family (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US6163019A (en) * 1999-03-05 2000-12-19 Abb Metallurgy Resonant frequency induction furnace system using capacitive voltage division
DE19926198A1 (de) * 1999-06-09 2000-12-14 Junker Gmbh O Schaltung und Steuerverfahren für Wechselrichter zur Speisung von Induktionsöfen
AU2002237760B8 (en) * 2001-01-08 2006-01-05 Inductotherm Corp. Induction furnace with improved efficiency coil system
US6693950B2 (en) * 2001-05-22 2004-02-17 Inductotherm Corp. Furnace with bottom induction coil
US6993061B2 (en) * 2003-11-07 2006-01-31 Battelle Energy Alliance, Llc Operating an induction melter apparatus
US7085305B2 (en) * 2004-08-25 2006-08-01 Battelle Energy Alliance, Llc Induction heating apparatus and methods of operation thereof
US7072378B2 (en) * 2004-08-25 2006-07-04 Battelle Energy Alliance, Llc Induction heating apparatus and methods for selectively energizing an inductor in response to a measured electrical characteristic that is at least partially a function of a temperature of a material being heated
CN101782324B (zh) * 2010-02-05 2011-09-28 新星化工冶金材料(深圳)有限公司 控制铝钛硼(碳)合金中TiB2(TiC)颗粒团平均名义直径的电磁感应熔炼电炉
EP3099991B1 (fr) * 2014-01-31 2017-12-13 Danieli & C. Officine Meccaniche, S.p.A. Installation et procédé de fusion de matériaux métalliques

Family Cites Families (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE453717C (de) * 1926-08-19 1927-12-15 Aeg Schaltung fuer Hochfrequenzoefen
US1795136A (en) * 1927-09-08 1931-03-03 Ajax Electrothermic Corp Electric induction furnace
US1943802A (en) * 1930-03-18 1934-01-16 Ajax Electrothermic Corp Electric induction furnace
GB451473A (en) * 1935-11-12 1936-08-06 Asea Ab Means for operating electric eddy current furnaces
GB508255A (en) * 1937-06-02 1939-06-28 British Thomson Houston Co Ltd Improvements in and relating to induction furnaces
US3331909A (en) * 1965-03-12 1967-07-18 Ohio Crankshaft Co Apparatus for energizing an induction melting furnace with a three phase electrical network
NL6710521A (fr) * 1966-12-21 1968-01-30
GB2232832B (en) * 1989-06-14 1993-11-10 Inductotherm Europ Induction Melting

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
See references of WO9526619A1 *

Also Published As

Publication number Publication date
WO1995026619A1 (fr) 1995-10-05
US5940427A (en) 1999-08-17
ATE168517T1 (de) 1998-08-15
EP0752194B1 (fr) 1998-07-15
DE59502832D1 (de) 1998-08-20

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