EP0752194A1 - Induktionstiegelofen mit mindestens zwei parallel an einen schwingkreisumrichter angeschlossenen spulen - Google Patents
Induktionstiegelofen mit mindestens zwei parallel an einen schwingkreisumrichter angeschlossenen spulenInfo
- 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
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)
- Furnace Details (AREA)
- General Induction Heating (AREA)
Description
Claims
Applications Claiming Priority (3)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
DE4410436 | 1994-03-25 | ||
DE4410436 | 1994-03-25 | ||
PCT/DE1995/000376 WO1995026619A1 (de) | 1994-03-25 | 1995-03-18 | Induktionstiegelofen mit mindestens zwei parallel an einen schwingkreisumrichter angeschlossenen spulen |
Publications (2)
Publication Number | Publication Date |
---|---|
EP0752194A1 true EP0752194A1 (de) | 1997-01-08 |
EP0752194B1 EP0752194B1 (de) | 1998-07-15 |
Family
ID=6513869
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
EP95913850A Expired - Lifetime EP0752194B1 (de) | 1994-03-25 | 1995-03-18 | Induktionstiegelofen mit mindestens zwei parallel an einen schwingkreisumrichter angeschlossenen spulen |
Country Status (5)
Country | Link |
---|---|
US (1) | US5940427A (de) |
EP (1) | EP0752194B1 (de) |
AT (1) | ATE168517T1 (de) |
DE (1) | DE59502832D1 (de) |
WO (1) | WO1995026619A1 (de) |
Families Citing this family (9)
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 |
WO2002054831A2 (en) * | 2001-01-08 | 2002-07-11 | Inductotherm Corp. | Induction furnace with improved efficiency coil system |
KR20040015249A (ko) * | 2001-05-22 | 2004-02-18 | 인덕터썸코포레이션 | 바닥에 유도 코일을 구비한 노 |
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 (de) * | 2014-01-31 | 2017-12-13 | Danieli & C. Officine Meccaniche, S.p.A. | Anlage und verfahren zum schmelzen von metallmaterialien |
Family Cites Families (8)
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 |
DE1549673A1 (de) * | 1966-12-21 | 1971-04-08 | Almex Ab | Zeichenlese- und -uebertragungsvorrichtung |
GB2232832B (en) * | 1989-06-14 | 1993-11-10 | Inductotherm Europ | Induction Melting |
-
1995
- 1995-03-18 AT AT95913850T patent/ATE168517T1/de not_active IP Right Cessation
- 1995-03-18 DE DE59502832T patent/DE59502832D1/de not_active Expired - Fee Related
- 1995-03-18 EP EP95913850A patent/EP0752194B1/de not_active Expired - Lifetime
- 1995-03-18 WO PCT/DE1995/000376 patent/WO1995026619A1/de active IP Right Grant
-
1996
- 1996-03-18 US US08/702,447 patent/US5940427A/en not_active Expired - Fee Related
Non-Patent Citations (1)
Title |
---|
See references of WO9526619A1 * |
Also Published As
Publication number | Publication date |
---|---|
ATE168517T1 (de) | 1998-08-15 |
WO1995026619A1 (de) | 1995-10-05 |
US5940427A (en) | 1999-08-17 |
EP0752194B1 (de) | 1998-07-15 |
DE59502832D1 (de) | 1998-08-20 |
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