US3595979A - Induction furnaces - Google Patents

Induction furnaces Download PDF

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Publication number
US3595979A
US3595979A US6441A US3595979DA US3595979A US 3595979 A US3595979 A US 3595979A US 6441 A US6441 A US 6441A US 3595979D A US3595979D A US 3595979DA US 3595979 A US3595979 A US 3595979A
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United States
Prior art keywords
channel
throat
central
central channel
hearth
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Expired - Lifetime
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US6441A
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English (en)
Inventor
Wilbur E Shearman
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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    • 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
    • H05B6/16—Furnaces having endless cores
    • H05B6/20—Furnaces having endless cores having melting channel only

Definitions

  • My invention relates further to improvements in induction furnaces of the type set forth, described and claimed in US. Pat. No. 3,092,682 granted June 4, I963 to Manuel Tama and the present inventor.
  • the furnace of my present design provides substantially increased velocity, increased hearth circulation and a further reduction in the temperature differential between the melt channels and the hearth, as contrasted with the previous construction recited above, and is adapted to utilize by reason of its more rapid flow and lower temperature differentials higher power inputs than possible with prior furnaces of this type. It has particular application in the melting of ferrous and nonferrous metals and their alloys where higher power inputs are used.
  • Certain larger furnaces of this type have employed a number of channel induction means and have a plurality of throats communicating with the substantially larger hearth.
  • the invention has been found particularly advantageous in higher power channels which are substantially longer than those heretofore used.
  • Another object of my invention is to increase the rapid exchange of the relatively small amount of molten metal contained within the power generating secondary loop with the bulk ofthe metal contained in the hearth.
  • a still further object of my invention is to achieve the improved temperature differentials and flow in a unidirectional flow furnace with minimum eddies and turbulence in the loop.
  • Another object of the invention is to achieve improvements in the lining life of the furnace by the higher velocities and lower temperatures of said furnace.
  • FIG. 1 is a vertical section of a first embodiment of the improved induction melting furnace of this invention
  • FIG. 2 is a section taken along the line 2-2 of FIG. l;
  • FIG. 3 is a top plan view of the channel form in the furnace ofFIGS. land 2',
  • FIG. 4 is a section similar to the lower portion of FIG. 1 showing a second embodiment of the furnace of this invention
  • FIG. 5 is a section taken along the line 5-5 of FIG. 4;
  • FIG. 6 is a top plan view of the channel form in the furnace ofFIGS. 4 and 5;
  • FIG. 7 is an enlarged perspective of the channel form of FIGS. 13 as viewed from the bottom, side and one end thereof, the modification of FIGS. 4-6 being shown in broken lines;
  • FIG. 8 is a top plan view similar to FIGS. 3 and 6 showing a further modified channel form
  • FIG. 9 is an enlarged perspective sectional view of the furnace of FIG. 4 with a diagram superimposed thereabove showing the temperature pattern when said furnace is operated at the 0-kw. power level;
  • FIG. 10 is an isometric view showing the outline of a prior art channel form with the corresponding temperature pattern superimposed thereon, the same being a copy of FIG. 5 of U.S. Pat. No. 3,092,682;
  • FIG. 11 is a perspective sectional view of a furnace constructed generally according to the above prior art patent with a diagram superimposed thereabove showing the temperature pattern when the same is operated at the power level of FIG.
  • FIG. 12 is an enlarged fragmentary view of portions of FIG. 2 showing the induced current pattern ofthe invention.
  • FIG. 13 is an enlarged fragmentary view of portions of FIG. 1 further illustrating the induced current pattern of the inven tion.
  • FIGS. 1 and 2 are a housing 1, comprising a hearth 2 and a submerged resistor twin coil unit attached thereto.
  • the hearth is adapted to hold the bulk ofa charge of metal to be melted up to the level 2 and is lined with refractory material 3.
  • a submerged resistor unit is provided with two loops (twin coil furnace); therefore, three substantially parallel channels 4, 5 and 6 are provided connected at the bottom by a channel portion 7 and connected at the upper ends thereof through a throat l1 and each of the channels, as shown in the prior art patent referred to above, has a major portion ofits length of substantially uniform cross section.
  • the transformer assembly comprises, in the embodiments illustrated, two coils of insulated copper wire which in operation are connected to a current supply source, such as a singlephase supply source of standard frequency alternating current, not shown. In the drawings, these coils are denominated by the numeral 8.
  • An iron core 10 threads the primary winding and is closed in itself from both sides of the furnace.
  • the transformer assembly is contained in a housing 12 to which a current of air may be passed by a blower 13 for cooling purposes.
  • the submerged resistor unit is fastened to the hearth unit attached to the flange 14 by bolts or the like.
  • the furnace has a removable cover I5.
  • the portion of the throat llimmediately adjacent the upper end of the center channel 5 which channel is of substantially uniform cross section is of substantially greater width axially as shown by arrows at A than the axial width of the center channel shown at B and theaxial width of I the bottom channel shown at C. l have found that such substantial axial enlargement of the throat in the portion carrying the electrical currents which equally divide from the upper portion of the center channel is of greatest benefit in achieving maximum flow and lowest temperature differentials. In FIGS. 12 and 13 such current pattern is illustrated.
  • the current path rather than as in the prior art being in planes perpendicular to the axis, tends to diverge axially from the center plane X-X as the current emerges from the center channeL
  • This substantial axial enlargement A 'in the current carrying portion of the throat achieves greater velocities and a lowering of temperature patterns.
  • Certain tests have indicated that preferably the axial widening of thethroat of that portion adjacent the upper end of the center channel should be held approximately to twice the width of the center and'bottom outwardly and upwardly gradient surfaces 50 and 5d.
  • the surfaces 5a and 5b are preferably tapered whereas the outwardly and upwardly gradient surfaces Sc and 5d are preferably curved. It will be understood that any of said gradient surfaces shown in FIGS. 4 to 6 inclusive, may ifdesired be either tapered or curved.
  • FIG. 7 is a perspective view disclosing in solid lines that form of the invention shown in FIGS-1,2 and 3 and in broken lines that form of the invention shown in FIGS. 4 to 6, inclusive.
  • FIG. 8 a modification of the throat and channels is shown, the widened throat and channels being of circular form and the form of the throat may be varied as in other forms shown.
  • FIG. 5 showing of US. Pat. No. 3,092,682 is shown as FIG. 10 herein and shows the improved temperature distribution pattern thereon.
  • lines 45 to 56 of the patent input averaged 14 kw.
  • the flow was 64,200 pounds per hour or 32.l tons per hour and the maximum temperature rise was 23 F.
  • the molten metal used in the example of the prior patent was lead.
  • FIGS. 4, 5 and 6, As shown in FIG. 9, the axial widening of the throat 11 adjacent the upper end of the center channel 5 effects for molten brass at an 800 kw. power level, a reduction of the maximum temperature differential from F. in FIG. ll showing to 40 F. and a greatly increased flow of 292 tons per hour.
  • FIGS. 1 to 3 leads to the same effect. Where higher power inputs are used, the advantages of the invention are obvious.
  • an inductor in accordance with the present invention will maintain a very high rate of unidirectional flow when the cross-sectional and longitudinal dimensions of the channels are increased when increasing the size of the inductor to enable a higher power input.
  • inductor units may be employed in a furnace and that the same may be positioned laterally of the hearth, etc.
  • bottom channel what is referred to is that channel which connects the lateral and center channel and is positioned farthest away from the hearth than the other channels.
  • a hearth a secondary loop adjacent said hearth, a throat interposed between said hearth and said secondary loop, two primary coils threading the secondary loop, said secondary loop consisting of two substantially rectangular branches formed by a central melting channel, a pair of lateral melting channels and a bottom channel; the said central and lateral channels connecting the said throat and the said bottom channel, each of the said channels having a major portion of its length of substantially uniform cross section, said throat having a portion at its intersection with the said central channel of an axial dimension substantially greater than the axial dimension of said central channel and substantially greater than the axial dimension of said bottom channel, said axial dimensions being those parallel to the axis of said primar y coils,.the molten metal flow from said central channel into said bottom channel being evenly divided flowing through each said lateral channel back into said throat and hearth.
  • each of said lateral channels has a substantially minor portion of its length provided with inwardly curved bottom edges, the radius of said curved bottom edges being substantially less than one half the diameter of each said primary coil.
  • a hearth in an induction furnace of the submerged resistor type for melting metals, a hearth; a secondary loop adjacent said hearth; a throat interposed between said hearth and said secondary loop, two primary coils threading the secondary loop; said secondary loop consisting of two substantially rectangular branches formed by a central melting channel; a pair of lateral malting channels and a bottom channel; said central and lateral channels connecting said throat and said bottom channel, each of said channels having a major portion of its length of substantially uniform cross section; a current carrying portion of saidthroat adjacent to the intersection of the throat with the central channel having an axial dimension greater than the axial dimension of said central channel and substantially greater than the axial dimension of said bottom channel, said axial dimensions being parallel to the axis of said primary coils, the molten metal flow from said central channel into said bottom channel being evenly divided flowing through each said lateral channel back into said throat and hearth.
  • a hearth In an induction furnace of the submerged resistor type for melting metals, a hearth; a secondary loop adjacent to said hearth; a throat interposed between said hearth and said secondary loop; said secondary loop consisting of two substantially rectangular branches formed by a central melting channel, two lateral melting channels and a bottom channel; two primary coils threading the secondary loop providing a concentric electrical field within said central channel; said central and lateral channels connecting said throat and said bottom channel, each of said channels having a major portion of its length of substantially uniform cross section; a current carrying portion of said throat proximate to the intersection with said central channel of an axial dimension being substantially greater than the axial dimension of said central channel and substantially greater than the axial dimension of said bottom channel, said axial dimensions being parallel to the axis of said primary coils, the molten metal flow from said central channel into said bottom channel being evenly divided flowing through each said lateral channel back into said throat and hearth.

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  • Physics & Mathematics (AREA)
  • Electromagnetism (AREA)
  • Vertical, Hearth, Or Arc Furnaces (AREA)
  • Furnace Details (AREA)
  • General Induction Heating (AREA)
  • Manufacture And Refinement Of Metals (AREA)
US6441A 1970-01-28 1970-01-28 Induction furnaces Expired - Lifetime US3595979A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
US644170A 1970-01-28 1970-01-28

Publications (1)

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US3595979A true US3595979A (en) 1971-07-27

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US6441A Expired - Lifetime US3595979A (en) 1970-01-28 1970-01-28 Induction furnaces

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US (1) US3595979A (index.php)
JP (1) JPS5025666B1 (index.php)
DE (1) DE2064467A1 (index.php)
GB (1) GB1340506A (index.php)

Cited By (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4170713A (en) * 1977-04-07 1979-10-09 Butseniex Imant E Channel-type induction furnace
EP0048629A3 (en) * 1980-09-24 1982-06-02 The Electricity Council Channel induction furnaces
WO2001099473A3 (en) * 2000-06-20 2002-04-18 Louis Johannes Fourie Induction furnace
WO2003059011A1 (en) * 2002-01-14 2003-07-17 Louis Johannes Fourie Induction furnace control
US20060133194A1 (en) * 2004-12-22 2006-06-22 Kenzo Takahashi Agitator, agitating method, and melting furnace with agitator
US20130336354A1 (en) * 2011-03-01 2013-12-19 Louis Johannes Fourie Channel type induction furnace

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB8314577D0 (en) * 1983-05-26 1983-06-29 Alcan Int Ltd Recovery of aluminium scrap

Cited By (12)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4170713A (en) * 1977-04-07 1979-10-09 Butseniex Imant E Channel-type induction furnace
EP0048629A3 (en) * 1980-09-24 1982-06-02 The Electricity Council Channel induction furnaces
US4435820A (en) 1980-09-24 1984-03-06 The Electricity Council Channel induction furnaces
WO2001099473A3 (en) * 2000-06-20 2002-04-18 Louis Johannes Fourie Induction furnace
US6819705B2 (en) 2000-06-20 2004-11-16 Louis Johannes Fourie Induction furnace
AU2002215497B2 (en) * 2000-06-20 2006-06-01 Louis Johannes Fourie Induction furnace
AU2002215497C1 (en) * 2000-06-20 2006-12-21 Louis Johannes Fourie Induction furnace
WO2003059011A1 (en) * 2002-01-14 2003-07-17 Louis Johannes Fourie Induction furnace control
US20050129086A1 (en) * 2002-01-14 2005-06-16 Fourie Louis J. Induction furnace control
US20060133194A1 (en) * 2004-12-22 2006-06-22 Kenzo Takahashi Agitator, agitating method, and melting furnace with agitator
US8158055B2 (en) * 2004-12-22 2012-04-17 Kenzo Takahashi Melting furnace with agitator
US20130336354A1 (en) * 2011-03-01 2013-12-19 Louis Johannes Fourie Channel type induction furnace

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Publication number Publication date
DE2064467A1 (de) 1971-08-12
JPS5025666B1 (index.php) 1975-08-26
GB1340506A (en) 1973-12-12

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