US3813470A - Horizontal coreless induction furnaces - Google Patents

Horizontal coreless induction furnaces Download PDF

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Publication number
US3813470A
US3813470A US00355647A US35564773A US3813470A US 3813470 A US3813470 A US 3813470A US 00355647 A US00355647 A US 00355647A US 35564773 A US35564773 A US 35564773A US 3813470 A US3813470 A US 3813470A
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United States
Prior art keywords
metal
coil
heating
chamber
horizontal
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Expired - Lifetime
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US00355647A
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English (en)
Inventor
W Duca
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.)
Park Ohio Holdings Corp
Original Assignee
Ajax Magnethermic Corp
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Publication date
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Priority to US00355647A priority Critical patent/US3813470A/en
Priority to JP1500374A priority patent/JPS5425663B2/ja
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Publication of US3813470A publication Critical patent/US3813470A/en
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Expired - Lifetime legal-status Critical Current

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    • 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
    • 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
    • H05B6/34—Arrangements for circulation of melts
    • 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
    • H05B2213/00—Aspects relating both to resistive heating and to induction heating, covered by H05B3/00 and H05B6/00
    • H05B2213/02—Stirring of melted material in melting furnaces

Definitions

  • ABSTRACT There is disclosed herein a horizontal coreless induction furnace having a polyphase coil that is electrically energized to establish a unidirectional stirring motion within the horizontally disposed corelss melt section of the furnace to prevent or reduce the build up of nonmetallics within the power coil surrounded portion of the furnace.
  • This invention relates to the induction heating and melting of metal and particularly to a means of applying power to a horizontal coreless induction furnace.
  • This invention relates to improvements in horizontal coreless induction furnaces of the type set forth, described and claimed in US. letters Pat. Nos. 3,483,301 patented Dec. 9, 1969 and 3,602,625 patented Aug. 31, 1971.
  • a single phase induction heating coil is wound annularly about a horizontal melting tunnel of the furnace. Energization of the induction coil establishes circumferential secondary currents within the molten metal and also causes a pattern of circulation within the molten metal shown by closed loops in the drawings herein which loops are termed quadrantal" herein.
  • the aforesaid molten metal circulation can transport nonmetallic particles such as molding sand or iron oxide which become dispersed in the molten iron as the charge melts. It has been found that such nonmetallic particles are transported into the heating coil region of the furnace and that, due to the opposing stirring forces within the single phase quadrantal stirring pattern, they will be entrapped near the center of the heating coil on the refractory surfaces of the horizontal melting tunnel.
  • the horizontal coreless induction furnace of the present invention is constructed to achieve unidirectional stirring of the molten metal within the horizontal tunnel of the furnace as contrasted to the prior quadrantal stirring referred to and thereby prevent the buildup of nonmetallic particles within the power coil region.
  • Another object of this invention is to prevent or reduce the formation of slags by interaction between nonmetallic particles at the power coil surrounded refractory surface or wall of the so-called horizontal coreless induction furnace.
  • Another object of this invention is to prevent attack of the power coil surrounded refractory walls by slags formed as a result of interaction between nonmetallic particles deposited thereon.
  • a further object of this invention is to provide means whereby the unidirectional flow of molten metal in a horizontal coreless furnace may be selectively achieved in either direction as desired.
  • FIG. I is a longitudinal section through a furnace of the type referred to showing the stirring pattern for a single phase coil as shown in the cited prior art;
  • FIG. 2 is a longitudinal section through the furnace of this invention showing the stirring pattern for a polyphase coil according to the invention wherein the direction of the molten metal circulation may also be reversed from that shown;
  • FIG. 3 is an electrical diagram showing one type of polyphase power system connection to the coil in the furnace of this invention.
  • FIG. 4 is a voltage, current and flux vector diagram for the polyphase coil in the furnace of this invention.
  • 10 indicates generally the horizontally disposed coreless induction furnace of this invention. It may be suitably adapted for melting or superheating any metal or alloy, but is expected to be particularly useful in ferrous metallurgy. Furnaces of this type are used commonly for melting metals, and the usual procedure is first heating molten metal inductively in the heating section of the furnace, the heated molten metal in turn melting the cold metal introduced through the charging section.
  • the molten metal 15 is shown contained within the refractory lining 19 of the horizontally disposed heating section 16, substantially vertically disposed charging section 17, and substantially vertically disposed pour section 18.
  • Cooling coil sections 22, 24, are shown disposed coaxial with the heating and stirring coils 20 at either end thereof and said coil sections are not supplied with current.
  • the induction heating and stirring power coil 20 is cylindrically wound about the horizontal portion 16 of the furnace which constitutes the principal metal containing cavity of the furnace.
  • a stirring pattern 25 as shown in FIG. 1 occurs. This is commonly referred to as quadrantal stirring. It has been found that if any nonmetallic material, such as finely dispersed metal oxides or gas bubbles resulting from the reduction of these metal oxides, is caught in the horizontal movement of the metal, it would be transported to a location adjacent the center of the coil and remain in such location by entrapment due to the opposing stirring forces and the fact that nonmetallic materials are not acted upon electromagnetically. As a result metal oxide buildup and/or the formation of a pocket of gas 26 tends to take place. This phenomena can occur even though the height of the metal in the charge section 17 and the pour section 18 is adequate to prevent surface slagfrom being drawn down into the heating section 16 as disclosed in US. letters Pat. No. 3,483,301.
  • lf nonmetallic particles of more than one kind are accumulated near the coil center, such as for instance silica and iron oxide, a low melting point slag may be formed.
  • the refractory lining may also participate in such a slag-forming reaction.
  • the coil 20A be connected as a polyphase load, as for example from a three phase input from an alternating current source, in which case a stirring pattern as shown at 30 in FIG. 2 occurs.
  • a stirring pattern as shown at 30 in FIG. 2 occurs.
  • the stirring pattern it is to be noted, in this form extends beyond the power coil section refractory surfaces. If any nonmetallic material such as finely dispersed metal oxides or gas bubbles resulting from the reduction of metal oxides are caught in the horizontal movement of the metal, the same will be transported through the horizontal heating section 16 by virtue of the unidirectional stirring achieved and buildup, slag formation, or gas pockets are prevented.
  • the coil 20 of the horizontal coreless furnace of this invention is shown as a three-section power coil with one center section 36 of the power coil reverse wound from the outer sections 35 and 37.
  • the coil is connected to a three-phase supply L1, L2, L3 in such a manner that each phase-to-phase voltage ener: gizes one coil section.
  • Capacitor banks-38, 39, and 40 are employed to correct the furnace power factor as is well known to those skilled in the art.
  • FIG. 3 A simplified showing of electromagnetic aspects of the connection of FIG. 3 is illustrated by vector diagrams of voltage E, current I, and flux 1 in H0. 4.
  • any two of the three-phase lines are reversed and the same type of action occurs except that the metal is transported unidirectionally in the opposite direction.
  • a horizontal coreless induction furnace for heating or melting metal comprising a horizontally disposed heating chamber having two axially spaced openings therein, a reservoir angled with respect to and extending upwardly from said chamber and communicating with one opening in said chamber, a second reservoir angled with respect to and extending upwardly from said chamber and communicating with the other opening therein, one of said reservoirs being adapted to receive a charge of metal to be heated or melted and the other reservoir being adapted to discharge molten metal therefrom, and an induction power coil supplied with polyphase current, said coil wound about the horizontally disposed heating chamber, the axis thereof coinciding with the axis of the said chamber and providing heating and unidirectional stirring of the metal in said heating chamber through the length of the coil wherefore finely dispersed metal oxides and gas pockets are not entrapped therein.
  • a method for melting or heating metal in a coreless induction furnace having an open ended horizontally disposed heating chamber, two reservoirs each in communication with an end of said heating chamber, and an induction power coil comprising, introducing a charge of metal through one of said reservoirs, supplying polyphase current to said coil to heat said charge to a predetermined temperature to melt said charge and to unidirectionally stir said molten metal in said heating chamber and transport said molten metal throughout the length of the coil whereby metal oxides and gas pockets are not entrapped therein.

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  • Physics & Mathematics (AREA)
  • Electromagnetism (AREA)
  • Furnace Details (AREA)
  • General Induction Heating (AREA)
  • Crucibles And Fluidized-Bed Furnaces (AREA)
US00355647A 1973-04-30 1973-04-30 Horizontal coreless induction furnaces Expired - Lifetime US3813470A (en)

Priority Applications (2)

Application Number Priority Date Filing Date Title
US00355647A US3813470A (en) 1973-04-30 1973-04-30 Horizontal coreless induction furnaces
JP1500374A JPS5425663B2 (enExample) 1973-04-30 1974-02-07

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US00355647A US3813470A (en) 1973-04-30 1973-04-30 Horizontal coreless induction furnaces

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US3813470A true US3813470A (en) 1974-05-28

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JP (1) JPS5425663B2 (enExample)

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5354970A (en) * 1992-06-30 1994-10-11 Inductotherm Corp Pot for batch coating of continuous metallic strip
US5872805A (en) * 1996-08-14 1999-02-16 Inductotherm Corp. Pot for coating continuous metallic strip

Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US1811644A (en) * 1931-06-23 Edwin fitch northrup
US3483301A (en) * 1966-12-07 1969-12-09 Gen Motors Corp Horizontal coreless induction furnace

Family Cites Families (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3602625A (en) * 1970-04-06 1971-08-31 Ajax Magnethermic Corp Horizontal coreless induction furnace

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US1811644A (en) * 1931-06-23 Edwin fitch northrup
US3483301A (en) * 1966-12-07 1969-12-09 Gen Motors Corp Horizontal coreless induction furnace

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5354970A (en) * 1992-06-30 1994-10-11 Inductotherm Corp Pot for batch coating of continuous metallic strip
US5872805A (en) * 1996-08-14 1999-02-16 Inductotherm Corp. Pot for coating continuous metallic strip

Also Published As

Publication number Publication date
JPS5425663B2 (enExample) 1979-08-29
JPS5019038A (enExample) 1975-02-28

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