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Publication numberUS3704336 A
Publication typeGrant
Publication dateNov 28, 1972
Filing dateApr 1, 1971
Priority dateApr 1, 1971
Publication numberUS 3704336 A, US 3704336A, US-A-3704336, US3704336 A, US3704336A
InventorsSynnestvedt Don A
Original AssigneeAjax Magnethermic Corp
Export CitationBiBTeX, EndNote, RefMan
External Links: USPTO, USPTO Assignment, Espacenet
Support means for induction coil
US 3704336 A
Abstract
There is disclosed herein longitudinal outer coil support means for a multisection induction coil, the coil comprising both cooling and power coil sections each including a number of coil turns. The coil turns carry fastening devices at spaced portions of the periphery, the fastening means being aligned longitudinally of the multisection induction coil and projecting through longitudinally aligned, insulating sections. The outer edges of each longitudinally aligned group of insulating sections are disposed in a channel member.
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Description  (OCR text may contain errors)

United States Patent Synnestvedt SUPPORT MEANS FOR INDUCTION v COIL [72] Inventor: DonA. Synne stvedt, Warren, Ohio [73] Assignee: Ajax Magnethermic Corporation,

Warren, Ohio [22] Filed: April 1, 1971 [21] Appl. No.: 130,240

521 U. S.Cl...-' ..-...-....13/27 51 Int.Cl ..F2' 7d 11/06, HO5b5/l.6

[58] Field of Search "13/27; 26; 219/1015 [56] References Cited" UNITED STATES PATENTS 2,755,326 7/1956 Kennedy ..13/27 1451 Nov. 28, 1972 3,004.091 10/1961 Tamaetal ..'..13/27 Primary ExamineF-RoyN. Envall, Jr. Attorney-J. H. Slough [57] I ABSTRACT There is disclosed herein longitudinal outer coil support means for a multisection inductionxcoil, the coil comprising both cooling and power coil sections each including-a number of coil turns. The coil turns carry fastening devices at spaced portions of the periphery, the fastening means being aligned longitudinally of the multisection induction coil and projecting 'through longitudinally aligned, insulating sections. The outer edges of each longitudinally aligned group of insulating sections 'are disposed in a channel member.

13 Clains, 5 Drawing ligures SUPPORT MEANS FOR INDUCTION COIL In the past, it has been known to support the coil turns by means of elongated, woodensupports disposed parallel with the axis of the coil and bolted to the outer periphery of the coil turns by means of studs welded or otherwise suitably secured to said coil turns. In operation of the furnace, these wooden supports are subjected to substantial stresses which tend to cause splitting of the wood. This, in turn, exposes the studs for possible arcing. v

The present invention, in the embodiment herein illustrated and described, is directed to longitudinal coil supports each of which comprises a plurality ofwooden support sections supporting portions of the overall cooling and heating coil means, there being a single mounting member connecting all of the support sections in each longitudinal support. Studs carried by the coil turns and projectingthrough the wooden support sections and bolts connecting said section to the single mounting member are encapsulated and electrically isolated to prevent arcing.

It is an object of theinvention to provide an imand highly effective in use.

' A still further object of the invention is to provide an induction heater or" furnace in combination with the improved longitudinal support means of this invention.

Other objects of the invention will be readily understood from the following description of one embodiment thereof as disclosed in the accompanying drawings, in which said drawings:

FIG. 1 is a transverse section through a simplified induction furnace taken generally along the line l-1 of FIG. 2;

FIG. 2 is a vertical section taken generally along the line 2-2 of FIG. 1;

FIG. 3 is an' enlarged vertical section, with portions removed, taken generally along the line 3-3 of FIG. 1;

FIG. 4 is a transverse section taken along the line 4- 4ofFlG: 3; and

. FIG. 5 is a transverse section taken along the line 5 5 of FIG. 3.

Referring now to the drawings in all of which like parts are designated by like reference numerals and particularly to FIGS. 1 and 2, a simplified form of a coreless electric induction furnace is shown generally at 10. The furnace includes a central container 11 comprising a cylindrical side wall 12 and a unitary bottom wall 13 formed of a suitable refractory material. At

the top of the container 11, the refractory material forms an outwardly projecting flange 14 which may be provided with a suitable pouring spout (not herein illustrated) if desired. The container 1 l is adapted for melting metals and metal alloys therein and for this purpose is provided with a hollow, insulated induction heating coil generally indicated at 15 comprising two coil sections, an upper section 15a and a lower section 15b, which are preferably mechanically wound in opposite directions but which may be wound in the same direction if desired. The induction coil 15 surrounds the cylindrical side wall 12 and extends generally from the upper surface of the bottom wall 13 to a point spaced a substantial distance downwardly from the flange 14.- Between the upper coil section 15a and said flange 14 there is provided a nonenergizable, hollow, insulated cooling coil section 16a. A substantially similar cooling coil section 16b surrounds the solid bottom wall 13. The cooling coil section 16a is' provided with a suitable inlet 17 and outlet 18 for circulating water or other suitable coolant therethrough to cool the upper portion of the container 11. As herein illustrated, the coil sections 15a, 15b 16a, and 16b are offset wound but they may be helically wound if desired. It will be understood that the cooling coil section 16b is similarly provided with an inlet and outlet, not herein illustrated, which would be located at another point in the periphery of the furnace.

The induction coil sections 15a and 15b are hollow whereby coolant can also be circulated therethrough. As shown at the coil section 15b, each power coil section has an inlet 19 at one end thereof and another inlet 20 at the other end thereof to receive the coolant which is discharged at an intermediate point in the coil section by means of outlets 21 and 22, respectively. It will be understood that the coil section 15a is similarly provided with coolant circulating inlet and outlet means which are located at another point in the periphery of the furnace. It will be further understood that the power coil sections 15a and 15b are provided with suitable power connections at their terminal ends adjacent to the inlets 19 and 20 by means of which said power coil 15 is energized from a suitable source of electrical current (not herein illustrated).

As herein disclosed, the entire container 11 and the power and cooling coil sections 15a, 15b, 16a, and 16b are contained within a frame 25 comprising a bottom wall 26 having a cylindrical side wall 27 surrounding the container and coils, the bottom wall 26 supporting a base 28 upon which the container and coils are disposed. As seen in FIGS. 1 and 2, the cylindrical side wall 27 is disposed radially outwardly from the power and cooling coilsections thereby affording an annular chamber 30 therebetween. A plurality of circumferentially spaced yokes 31 are disposed within the annular chamber 30 in abutting relationship with both the coils and the cylindrical wall 27. Each yoke 31 comprises a plurality of laminations 32 made of silicon iron or the like, each lamination extending the full length of all of the power and cooling coils. In each said yoke, the laminations 32 are secured together at spaced intervals throughout their length by means of U-shaped clamps 33. Adjustable yoke bolts 35, as shown in FIG.

' 2, are threaded through the cylindrical wall 27 opposite I each said clamp whereby the yokes 31 are adjustable inwardly and can be tightened against the power and cooling coils. A suitable insulation such as asbestos type insulating board 34 is provided between the laminations 32 and the coil sections a, 15b, 16a, and 16b.

By referring to FIGS. 1 and 2 of the drawings, it will become readily apparent that the circumferenti'ally spaced yokes 31 disposed in the annular chamber 30 afford firm radial support for the cooling coil sections 16a and 16b and the power coil sections 15a and 15b. The yokes also provide a magnetic path to guide the magnetic flux, thereby minimizing the occurrence of stray field currents and minimizing loss due to heating outside structure.

As is'well known in the art, coils of this type also must be provided with adequate longitudinal support or bracing in a direction parallel with the axis of the coil sections. All helical and offset wound coils of the present type have an inherent tendency to unwind and this movement must be resisted in addition to movements and vibrations occuring as a result of energization of the power coil and thermal variations. Where adjacent power coil sections are mechanically wound in opposite directions as preferred in the present invention, said adjacent coils will tend to unwind in relatively opposite directions. By connecting all of the coils to common support means, the unwinding forces of adjacent coils tend to counteract each other while placing great stress on the support means. Insulated wooden supports to which the coils are sometimes bolted afford a desired means of support, but it has been found that such necessarily long wooden coil supports tend to split under load whereby coil studs used for securing the coils are exposed for possible arcing.

The present invention is directed to longitudinal coil supports generally indicated at 39 which are of the wooden type and which extend the full axial length of the cooling and power coil sections. The longitudinal coil supports 39 are disposed between the yokes 31 and, as detailed in FIG. 3, each said coil support comprises a plurality of short wooden support sections 40,

there being one of said sections for each of the cooling coil sections 16a and 16b and each induction coil section 15a and 15b. Each wooden section 40 extends thefull length of the coil section with which it is associated, the wooden support sections being spaced slightly apart in the vertical direction in each longitudinal coil support. At each coil support, each turn of the cooling coil sections 16a and 16b is provided with a stud 41 having its head 41a welded to the outer periphery of the coil turn whereby said stud projects radially outwardly therefrom. A layer of asbestos insulating board or other suitable insulation 43 is disposed between each wooden support section 41 and its adjacent coil section, and the studs 41 project outwardly through the insulation 43 and through suitable bores 44 in the support section. It will be understood that the turns of the power coil sections 15a and 15b are each connected to a support section 40 in the same manner as the turns of the cooling coils by welded studs 41' which differ from the studs 41 only by having differently shaped heads 41a at their weldedends. The radially outwardly directed, longitudinal edge portions of the wooden support sections 40 are provided with recesses 42 within which the outermost, threaded ends of the studs 41 and 41' are disposed. Each stud 41 and 41 is secured by a suitable nut 46 which is also disposed within a recess 42. A second layer of insulation 47 is disposed on theoutwardly facing surface of each wooden support 40 thereby covering the recesses 42 and completely encapsulating the outer end of the studs 41. and 41 The outer edge portions of all of the wooden support sections 40 of a single longitudinal coil support 39 are seated within a single, radially inwardly opening aluminum channel member 48. The insulation 47 is disposed in the bottom of the channel with the outer edge surfaces of the wooden support sections disposed against said insulation. As detailed in FIGS. 4 and 5, each channel member 48 comprises a bottom wall 48a and inwardly projecting, parallel flanges 48b, said flanges overlapping the wooden support sections 40 a substantial distance.

Each of said wooden support sections 40 is secured to the associated channel member 48 by a single, intermediately disposed bolt 50. The head of the bolt 50, shown at 50a, is encapsulated within a recess 51 at the I inner edge of the associated support section beneath or outwardly of the inner layer of insulation 43. Each said bolt projects outwardly from the recess 51 through a suitable aperture 52, the outer insulation 47, and a suitable aperture 53 in the bottom wall 48a of the channel member 48. The outer threaded end portion of each bolt 50 is then secured by a suitable nut 54. Thus, it will be seen that all of the short wood support sections 40 in each longitudinal coil support 39 are held in vertical alignment between the parallel flanges 48b of a single channel member 48. I

It has been found that by utilizing short wooden support sections, the resultant loading on the support as a whole is distributed in such a manner as to prevent splitting. The provision of short wooden support sections slightly separated from each other prevents the stresses from one coil section from being transferred to the wood support section of another coil or coil section which said stresses are ultimately absorbed by the single connecting channel 48. This, in combination with the recessed, encapsulated studs and bolts, substantially eliminates the possibility of arcing.

It will be understood that many changes in the details of the invention as herein described may be made without, however, departing from the spirit of or the scope of the appended claims.

I claim:

1. In combination with an electrical induction furnace coil made up of at least two axially aligned power coil sections with an axially aligned cooling coil section disposed at either end of said power coil sections, each said power and cooling coil section comprising a number of coil turns, longitudinal coil supports for supporting said turns each comprising a plurality of separate spaced insulating sections aligned parallel with the axis of said furnace coil adjacent to the outer periphery of said furnace coil; at least certain of said coil turns carrying radially outwardly directed studs projecting into and secured to said insulating sections, each said insulating section adapted to support a plurality of said coil turns in each said coil section; a single mounting member disposed parallel with and engaging all of the insulating sections in each longitudinal coil support wherebysaid insulating sections are maintained in alignment; and means securing each said insulating section to the mounting member associated therewith.

2. The combination as set forth in claim 1: said insulating sections having inner longitudinal edge portions adjacent to said furnace coil and radially outwardly directed opposite longitudinal edge portions; said mounting member being elongated and channel-shaped in cross section, said opposite longitudinal edgeportions disposed within and engaged by the channel of said mounting member; and means securing each said insulating section to said mounting member.' 3. The combination as set forth in claim 2: each of said coil turns having a radially outwardly directed stud projecting into and secured to an insulating section of each longitudinal coil support; said means securing each said insulating section to the mounting member associated therewith comprising a single bolt projecting through said insulating section and said mounting member. 4. The combination as set forth in claim 3: each said insulating section having recesses in the outwardly directed, opposite longitudinal edge portion thereof in alignment with the studs connected to said insulating section; said studs terminating "and being provided with nut means within said recesses; each said insulating section having a recess in the inner longitudinal edge portion thereof intermediate the ends of said insulating section; the bolt securing each said insulating section to said mounting member having a head portion disposed within said last mentioned recess and'projecting outwardly through said insulating section and said mounting member. 5. The combination as set forth in claim 4: insulation means disposed on both inner and outer longitudinal edge portions of said insulating sections and covering said recesses whereby said studs and bolts are encapsulated and electrically isolated. 6/lnduction heating means for an induction furnace comprising at least four coaxial individual coil sections including two end cooling coil sections and two intermediate power coil sections, each coil section comprising a plurality of continuous coil-turns; a plurality of longitudinal coil supports disposed parallel with the axis of the coil sections and spaced circumferentially around the outer periphery of the heating means; each said longitudinal coil support extending the full axial length of the combined coil sections and comprising a plurality of separate spaced, wooden support sections aligned end-to-end along said heating means; each of said coil turns having a radially outwardly projecting stud at each longitudinal coil support projecting through and secured to the adjacent wooden support section, each support section of each longitudinal coil support extending along and supporting the coil turns of an entire coil section; said support sections having inner longitudinal edge portions adjacentto the outer peripheries of the coil turns, and outer longitudinal edge portions directed radially outwardly of said coil turns; each of said aligned support sections in each said longitudinal coil support engaging a single elongated, channel-shaped mounting member with the outer edge portions thereof being disposed within the channel between spaced flanges thereof; a single bolt means securingeach said wooden support section to the channel-shaped mounting member associated therewith intermediate the ends of said support section; said studs and said bolts being electrically isolated from each other.

7. Induction heating means as set forth in claim 6: each said wooden support section having recesses in the outer longitudinal edge portion thereof in alignment with the studs connected to said section; said studs terminating and being provided with nut means within said recesses; each said support sec tion having a recess in the inner longitudinal edge portion thereof intermediate the ends of said section; the bolt securing each support section to the mounting member associated therewith having a head portion'disposed within said last mentioned recess and projecting outwardly through said section and said mounting member. 8. Induction heating means as set forth in claim 7: insulation, means disposed on both inner and outer longitudinal edge portions of said wooden support sections and covering said recesses whereby said studs and bolts are encapsulated and electrically isolated. I 9. An induction furnace for melting metal comprising a refractory container; coil means surrounding said container coaxially therewith; said coil means comprising upper and lower, individual cooling coil sections and at least two intermediate power coil sections, each of said coil sections comprising a plurality of continuous turns of an inductor; a base for said furnace and a cylindrical wall spaced radially outwardly from said coil means; laminated iron yokes disposed at spaced intervals around said coil means and extending longitudinaily parallel with the axis thereof between said coil means and said wall and affording radial support for said coil; longitudinal coil supports extending the full length of said coil means and disposed between said yokes; each said coil support comprising a plurality of separate spaced insulating sections aligned parallel with the axis of said coil means adjacent to the outer periphery thereof; each coil turn carrying radially outwardly directed studs at each longitudinal coil support projecting through and secured to an insulating section, each said insulating section extending axially the length of a coil section; each longitudinal coil support having a single, channel-shaped mounting member engaging the outer edges of all insulating sections thereof whereby said sections are maintained in alignment; and means securing each said insulating section to the mounting member associated therewith.

' 10. An induction furnace as set forth in claim 9:

said insulating sections being made of wood and having inner longitudinal edge portions adjacent to said coil and radially outwardly directed outer longitudinal edge portions disposed in the channel of one of said mounting members; each said insulating section having recesses in the outer longitudinal edge portion thereof in alignment with studs connected to said insulating section; said studs terminating and being provided with nut means within said recesses; each said insulating section having a single recess in the inner longitudinal 7 edge portion thereof intermediate the ends of said insulating section; said means securing each said insulating section to a mounting member comprising a bolt having a head portion disposed within said last mentioned recess and projecting outwardly through said insulating section and secured to said mounting member. l 1. An induction furnace as set forth in claim 10: insulation means disposed on both inner and outer longitudinal edge portions of said insulating sections and covering said recesses whereby said studs and bolts are encapsulated and electrically isolated. i 12. In combination with an electrical induction furnace coil made up of at least two axially aligned power coil sections with an axially aligned cooling coil section disposed at either end of said power coil sections, said power coil sections being wound in opposite directions, each said section comprising a number of coil turns, longitudinal coil supports for supporting said turns each comprising a plurality of separate spaced insulating sections aligned parallel with the axis of said furnace coil adjacent to the outer periphery of said furnace coil; at least certain'of said coil turns carrying radially outwardly directed studs projecting into and secured to said insulating sections, each said insulating section adapted to support a plurality of said coil turns;

a single mounting member disposed parallel with and engaging all of the insulating sections in each longitudinal coil support whereby said insulating sections are maintained in alignment; and means securing each said insulating section to'the mounting member associated therewith.

13. In combination with an electrical induction furnace coil made up of at least two axially aligned power coil sections with an axially aligned cooling coil section disposed at either end of said power coil sections, said power coil sections being wound in the same direction, each said section comprising a number of coil turns, longitudinal coil supports for supporting said turns each comprising a plurality of separate spaced insulating sections aligned parallel with the axis of said furnace coil adjacent to the outer periphery of said furna'ce coil; at least certain of said coil turns carrying radially outwardly directed studs projecting into and secured to said insulating sections, each said insulating section adapted to support a plurality of said coil turns; a single mounting member disposed parallel with and engaging all of the insulating sections in each longitudinal coil support whereby said insulating sections are maintained in alignment; and means securing each said insulating section to the mounting member associated therewith.

Patent Citations
Cited PatentFiling datePublication dateApplicantTitle
US2755326 *Jun 2, 1955Jul 17, 1956Ajax Electrothermic CorpInduction furnace
US3004091 *Sep 15, 1958Oct 10, 1961Ajax Magnethermic CorpCoreless induction furnace melting of metals
Referenced by
Citing PatentFiling datePublication dateApplicantTitle
US3900695 *May 16, 1974Aug 19, 1975Asea AbElectric induction furnace
US4486641 *Dec 21, 1981Dec 4, 1984Ruffini Robert SInductor, coating and method
US5197081 *May 24, 1990Mar 23, 1993Inductotherm Corp.magnetic return apparatus for coreless induction furnaces
US5247539 *May 11, 1992Sep 21, 1993Abb Patent GmbhMagnetic yoke for an induction crucible furnace
US5257281 *Jan 31, 1990Oct 26, 1993Inductotherm Corp.Induction heating apparatus and method
US5272720 *Jun 1, 1990Dec 21, 1993Inductotherm Corp.Induction heating apparatus and method
US5416794 *Aug 16, 1993May 16, 1995Inductotherm Corp.Induction furnace havng a modular induction coil assembly
US5418811 *Apr 8, 1992May 23, 1995Fluxtrol Manufacturing, Inc.High performance induction melting coil
US5430758 *Mar 30, 1993Jul 4, 1995Abb Patent GmbhMagnetic yoke for an induction crucible furnace
US5550353 *Feb 6, 1995Aug 27, 1996Inductotherm Corp.Induction heating coil assembly for prevent of circulating current in induction heating lines for continuous-cast products
US5588019 *Feb 15, 1995Dec 24, 1996Fluxtrol Manufacturing, Inc.For melting a workpiece
US6434182May 23, 2001Aug 13, 2002Lecrotherm, Inc.Composite insulating clamp assembly for induction furnace
DE4115278A1 *May 10, 1991Nov 12, 1992Abb Patent GmbhMagnetischer rueckschluss fuer einen induktionstiegelofen
DE10026921A1 *May 30, 2000Dec 13, 2001Ald Vacuum Techn AgCoil has several loops above each other in mutually parallel planes with each open loop having two ends at certain distance apart and each being connected via connecting piece to one end of adjacent open loop
DE10026921C2 *May 30, 2000Apr 11, 2002Ald Vacuum Techn AgSpule
EP0563802A2 *Mar 25, 1993Oct 6, 1993ABB PATENT GmbHMagnetic yoke for a crucible induction furnace
EP0639936A1 *Nov 2, 1993Feb 22, 1995Inductotherm Corp.Induction furnace having a modular induction coil assembly
EP0858246A2 *Jul 2, 1997Aug 12, 1998Inductotherm Corp.Induction coil and coreless induction furnace employing same
Classifications
U.S. Classification373/153
International ClassificationH05B6/02, H05B6/24
Cooperative ClassificationH05B6/24
European ClassificationH05B6/24