US1165558A - Method of producing electromagnetic coils. - Google Patents

Description

' Patented Dec. 28, 1915. 172 4.

C. H. THORDARSON.

METHOD OF PRODUCING ELECTROMAGNETIC COILS.

APPLICATION FILED 1 m. 11. 1915.

UNITED STATES PATENT OFFICE.

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, men or mnucnm nlqrnonanmc coma To all Y Be it known that I, Cnm'rzn vH. Tnoa- DARSON, a citizen of the United States, and a resident of Chicago, inthe county of Cook and State of'Illinois, have invented certain new and useful Improvements in Methods of Producin Electromagnetic Coils; and I do hereby eclare that the following is a full, clear, and exact description thereof, reference being had to the accompanying drawings, and to the characters of reference marked thereon, which form a part of this specification.

This invention relates to a novel method of producing flat wire electro-magnetic coilsor windings for transformers and other electro-magnetic devices, and the invention consists in the matters hereinafter set forth and more particularly pointed out in the appended claims.

An object of the invention is to reduce the cost of producin such coilsand to-reduee the dimensions 0 the coil produced as compared to its capacit fol-work.

Another object o the invention is to provide an improved method of producing coils, whereby such coils may be made up of extremely thin and narrow flat wires without involving complications in handling the wire in the difierent stages of the manufacture of the coil.

In producin a coil in accordance with my novel method apply to a sheet or web of electrically conductive metal of the required gage, and of a substantial width to produce a number of flat wires, a thin insulating coating which, (for some metals may consist of an oxid formed on the sheet, and for others of an enamel applied thereto) thereafter slitting the sai sheet into narrow strips of a width to produce the resultant flat wires; thereafter winding the flat wires thus produced into a coil, and thereafter treating or conditioning the end faces of the coil, formed by the edges ofthe flatwire, so as to remove or avoid sharp projections or burs formed on said edges when cutting the sheet to produce'the flat wires, and thereby avoiding short circuiting between the turns. In some instances, the conditioning of the end faces of the coil may be efiected by an acid of such character as to cut back into the metal of the fiat wire at the exposed sides thereof, while being neutral to the insulating covering, so as to leave, in effect, between the turns overhanging insulating ledges con- Specification r Il'ettera Ila tent Patented 28,1915. I a u auum uury nau. l mma-104.1

i of the edges of oxid or enamel In other 3 instances, the burs or,

roughened edges may be covered by an in-. 'sulati'ng' coatingto avoid short circuitingquently passing the coatedsheet through an annealing chamber. la effect between lyticor enamel bath and a strip or sheet of metal to be coated, the insulatin tends to accumulate at the edges 0 the strip or sheet so as to thereby substantially thicken the coated sheet or strip at its By reason of the capilthe liquid of the electrocoating .-may-be applied a the mar-l gins. For this reason it becomes impractical to coat flat wires of the ultimate width required for the coil inasmuch as the thickened margins prevent the flat wire being made intocompactly and. symmetrically wound coils.

In the practice of my improved method for producing coils the edges of the coated sheet are sheared 01f at or before the time the sheet is being cut into'strips, so that the re portion of the sheet from-which the flat wires are cutis' of uniform gage throughout and may becompactly and sym- I metrically wound into a coil. it is cially impossible, toapply such insulating coatmg to very thin and narrow stri s or wires, say of .0003 of an inch in thic ess and from i to of an inch inwidth,

reason of the mechanical difiiculties whic Furthermore,

are encounteredin passing such thin deli cafe strips through the coating bath and winding them into a coil. This mechanical difliculty of handling the material is not encountered when the coil is produced by my improved IDEthOdyfOI the reason that the sheet itself is of such width as to be readily passed through the coating bath, and said sheet may be readily. cut up into strips and the strips wound intocoils; However, regardless of the gage and width of the flat wire, the expense of producin same by my novel method is materially ret luced by reason of the greater facility of handling the material. n some instances I may wind the strips into coils directly from the cutquite impracticable, if not commerting machine, while in other cases I may Wind, the strips into rolls which are thereafter unrolled and wound into coils.

I have illustrated in the drawings the Various steps and stages of my novel method.

In said drawings :-Figure'l illustrates a web or sheet which is first subjected to the coating bath and afterward cut to produce the fiat wire or strips] Fig. 2 is a perspective view of a coil, partially wound, produced from the flat wire cut from the sheet shown in Fig. 1. Fig. 3 is an enlarged cross section of one of the coated fiat wires produced by my novel method. Fig. 4 is a similar cross section of a coated flat wire which has been coated after being cut to its final width. Fig. 5 is an enlarged cross section of a number of turns of the coil before the end faces thereof have been conditioned. Fig. 6 is asimilar view after the end faces have been. subjected to the conditioning process.

' The sheet 10, shown in Fig. 1, may be of any suitable width to produce, when cut, a number of resultant fiat wires or strips 11. After the sheet has been subjected to a coating bath to apply an insulating coating thereto the side edges 12, 12 which, as before stated, are slightly thicker than the remaining portions of the sheet are sheared off.

Preferably, in the practice of my novel' method, the side edges of the sheet are,

. sheared off at the same time the sheet is cut or split into strips to form the. fiat wires. Thereafter the coated flat wire is wound to produce the coil 13, shown in Fig. 2.

Fig. 3 shows a cross section of one of the flat wiresvll and also the insulating coating 14 thereon. It will be noted that the thickness or gage of the flat Wire is uniform throughout the width of the wire. In comparing the fiat wire 15 shown in Fig. 4 (which latter, it is assumed, has been coated as an individual wire) with the flat wire 11. shown in Fig. 3, it will be notedthat in the former figure the coating solution has collected along the edges in a manner to produce on both sides thereof thickened portions 16, substantially thicker than the body of the fiat wire, so that it becomes impracticable to compactly wind such a wireinto a coil with all parts of the turns laid fiat upon each other, or to insure an assemblage of the flat wires in a coil with the edges flush to produce smooth end faces, inasmuch as the thickened portions will tend to cause the turns to slip or slide sidewise upon each other and produce irregular or unsymmetrical coil end faces.

The fiat wires or strips may be cut from machine to the coil winding machine, or they may be primarily formed into rolls and the rolls thereafter unwound and rewound into coils.

.ing sodium potassium tartrate, to form a thin oXid coating on the surface of the sheet. Such an -o-xid coating may be produced extremely thin while possessing high insulating efficiency. For instance, when employing a flat wire of .0003 of an inch in thickness the coating on each side need not exceed .0001 of an inch. It will thus be observed that-the flat wire may be wound in a very compact coil or winding structure so as to thereby reduce the dimensions of the coil, and also-reduce its weight as compared to its electromagnetic efficiency.

When employing copper as a metal to'produce the flat wire I may coat the sheet with a suitable enamel having the required degree of thinness and at the same time possessing the required insulating efficiency.

After the coil has been wound, the end faces thereof present somewhat the appearance illustrated in Fig. 5, with the edges of the fiat wire slightly roughened or burred due to the action of the cutting tools thereon during the cutting operation. Such roughened. edges are objectionable in the coil inasmuch as they form discharge points across which the turns of the coil are liable to short circuit. The endfaces of the coil may be conditioned to avoid such roughened edges of the flat wire either by coating the said faces with an insulating material to thereby insulate the turns from each other, or such conditioning may be effected by means of an acid of such character that when applied to the end faces of the coil it acts to cut the side edges of the flat wire slightly back' from the planes of the said faces but which has no effect on the insulating coating. When using aluminum as the flat wire material, provided with an oxid insulating coating, I may treat-the edges of the wire to produce the result described by the use of a solution of diluted hydrocloric acid. After the edges of the wire have been thus treated the edges of the insulating coating, which have not been affected by the conditioning process, overhang the wire edges to produce insulating ledges 17 which avoid short circuiting between the turns of the winding across said edges. Thereafter the end faces of-the coils may be treated to a coat of thin insulating material, such as shellac, which may be applied by a brush or by dipping the coil in the shellac, or like solution.

When using copper wire coated with an insulating enamel I may employ for the purpose of conditioning the end faces of the coil any suitable acid which will cut the copper but which is neutral to the enamel such, for instance, as diluted nitric acid.

An advantage of the coil produced by my novel method in its use in a transformer, for instance, is that the edges of the flat wire may be very efiiciently exposed to a circulating coating medium whereby overheating of the wire under heavy service is avoided.

I claim as my invention 1. The method of producing electro-magnetic coils, which consists in applying to a sheet of electrically conductive metal an insulating coating, thereafter shearing the thickened edges from the sheet and cutting the sheet into strips to produce flat wire conductors, and finally winding the flat wires thus produced into a coil.

2. The method. of producing electro-magnetic coils which consists in applying to a sheet of electrically conductive metal an insulating coating, thereafter cutting the sheet into strips to produce fiat wire conductors, thereafter winding the flat wire thus produced into a coil and finally treating the end faces of the coil to insulate the winding turns from each other at said end faces.

3. The method of producing electro-magnetic coils which consists in passing a sheet of electrically conductive metal through a bath to form thereon an insulating coating, shearing the thickened edges from said sheet, and cutting said sheet into strips to produce flat wire conductors, winding the flat wire thus produced into a coil, and finally conditioning the end faces of the coil to insulate the winding turns from each other at said end faces.

4. The method of producing electro-magnetic coils which consists in treating a sheet of electrically conductive metal to form thereon an insulating coating, cutting said sheet into strips to produce flat wire conductors, winding the flat wire thus produced into a coil and treating the edges of the flat Wire at the end faces of the coil to remove the bur therefrom while retaining the coating to form insulating ledges which overhang the edges of the wire.

5. The method of producing electro-magnetic coils which consists in treating a sheet of electrically conductive metal to form thereon an insulating coating, cutting said sheet into strips to produce fiat wire conductors, winding the flat wire thus produced into a coil, treating the edges of the Hat wire at the end faces of the coil to remove the bur therefrom, while retaining the coating to form insulating ledges which overhang the edges of the wire, and finally coating the end faces of the coil with a thin insulating material.

6. The method of producing electro-magnetic coils which consists in applying to both sides of a very thin, wide sheet of electrically conductive metal an insulating coating, thereafter cutting the sheet into narrow strips to produce flat wire conductors covered on both sides with an insulating coating and finally winding the flat insulated wires into a coil.

In testimony that I claim the foregoing as my invention I affix my signature in the presence of two witnesses, this 29th day of December, A. D. 1914.

CHESTER THORDARSON.

Witnesses:

W. L. HALL, G. E. DOWLE.

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