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Publication numberUS1136942 A
Publication typeGrant
Publication dateApr 27, 1915
Filing dateSep 23, 1913
Priority dateSep 23, 1913
Publication numberUS 1136942 A, US 1136942A, US-A-1136942, US1136942 A, US1136942A
InventorsElisha B Cutten
Original AssigneeUs Horse Shoe Co, Elisha B Cutten
Export CitationBiBTeX, EndNote, RefMan
External Links: USPTO, USPTO Assignment, Espacenet
Laminated core for electrical apparatus.
US 1136942 A
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Description  (OCR text may contain errors)



Patented Apr. 27, 1915.





Application filed September 23, 1913.

To ($1.75 whom it may concern Be it lmown that I, ELISHA B. Curran, a citizen of the United States, residing in Erie, county of Erie, State of Pennsylvania, have invented certain new and useful Improvements in Laminated Cores for Electrical Apparatus; and I do hereby declare the following to be a full, clear, and exact description of the invention, such as will enable others skilled in the art to which it appertains to make and use the same.

The object of the invention is to provide a highly efficient and economical construction of laminated core for electrical apparatus in which the individual laminm are provided with a multiplicity of body perforations or slits so disposed as to effectively break up the continuity of the laminae in respect of eddy currents or induction currents in the iron, said slits being preferably arranged in multiple rows, with the slits of adjacent rows in staggered relation and the several rows being substantially parallel to the direction of the magnetic flux in the core when the latter is applied to its intended use. The sheets or laminae slitted as indicated are preferably secured together in superposed relation to build up the core to the desired thickness, by means of a suitable cement, the pack of superposed sheets and interposed cement being subjected to heavy pressure so that when the cement has set, the core will stand solid, self-supporting mass requiring no other securing means, such as bolts or rivets commonly employed for holding the laminae together.

In the accompanying drawings, Figure 1 illustrates the invention as applied to a sheet or lamina for a field core or frame for a dynamo-electric machine. Fig. 2 illustrates the same as applied to a sheet or lamina to be used as an element of the armature of the dynamo-electric machine. Fig. 3 is a similar view showing a sheet or lamina for the core of a transformer.

In applying the invention, in its adapt-a tion in connection to various forms of induc tional electrical apparatus involving magnetic cores, thin sheets of magnetic material, usually soft iron, are cut or stamped to the required shape of the cross section of the core, as is usual, and the entire body portion of each sheet is perforated or pierced S 'ecification of Letters Patent.

Patented Apr. 27, 1915.

Serial No. 781,304.

by means of a suitable tool to produce a multiplmity of relatively narrow slits or slots, just wide enough to effectively separate the metal, but without leaving any material or appreciable opening or gap between the adjacent sides of the slots. Preferably the slits or slots are arranged in regular substantially parallel rows spaced at close intervals and following approximately the lines of magnetic flux in the completed core, with the slits of adjacent rows arranged in staggered relation, thereby breaking up the continuity of the body portion of each sheet, leaving the solid metal portions of the sheet in the form of thin narrow tortuous bands or strips between the slits, which has the of feet of breaking up the eddy currents and reducing the effect of hysteresis to a minimum, with a consequent avoidance of the objectionable heating effects common to the magnetic cores of electrical apparatus.

In Fig. 1, the invention is illustrated as applied to the laminae F forming the field core or frame of a dynamo-electric machine, and it will be noted that the slits are arranged or disposed, first in circumferential rows 1, 2, etc, in the spaces between the poles, while the slits in the portions constitilting the poles are arranged radially so that the successive rows of slits are disposed substantially parallel to the lines of magnetic flux, and at right angles to the objectionable heating currents induced in the core. Furthermore, the slits in adjacent rows are arranged in staggered relation so as to more effectually interrupt the flow of the induced heating currents.

In Fig. 2, the invention is shown as applied to the laminae of an armature core A built up of a series of d sks of thin sheet metal provided with radial teeth in which the armature coils are placed. In this form of apparatus, the slits in the main body por tion of the individual sheets or lamina: are disposed in concentric rows at close intervals, while the slits in the teeth are arranged in radial rows and extend well into the body portion, the slits 1, 2, 3 of adjacent rows being staggered, as before.

In Fig. 3, there is exemplified a typical sheet or lamina C for a transformer, in the form of a rectangle having its entire body portion pierced or perforated by a closely arranged series of rows of slits, with the slits 1n ad acent rows arranged in staggered relation, as hereinbefore described.

The fore oin elements are of course.

paratus of the class described, the sheets or laminae are first stamped or pressed from soft iron or other suitable magnetic sheet material to the required shape, represented by the cross sectional contour of the core. Either simultaneously with the stamping operation or subsequent thereto, the entire body portion of each lamina is slitted as hereinbefore indicated by suitable punches which pierce the metal through and through at the slits, leaving the latter as very narrow elongated openings, the successive slits of each row and the several rows being separated from each other by narrow bands of solid or unsevered metal. After the slitting face of the metalwhere the punches emerged 1 are smoothed offby means of an emery wheel or other. abrasivev device, so that when the sheets are superposed one upon another, they will lie in close proximity. After the sheets have been thus prepared, they: are arranged in stacks to build up a core of the described thickness, a suitable cement beingxa'pplied to the sheets so superposed. T he stack of sheets is then subjected to heavy pressure, which has the effect of compacting and compressing the sheets orlaminze and the interposed cement to the desired longitudinal dimension of the finished core. The cement not only. fills the spaces between adjacent sheets or laminae but passes through the thin slits in the individual sheets and effectively locks the mass together so that it forms a In applying the invention to electrical ap.

solid and rigid structure, requiring no other or auxiliary clamping means.

vVhat I claim is 1. The method of constructing laminated cores for electrical apparatus which consists in forming sheets of metal to the required shape, slitting the sheets at a multiplicity of points the slits being substantially parallel with the lines of magnetic flux, and superposing and compressing said slitted sheets to form the core.

2. The method of constructing laminated cores tor electrical apparatus which consists in forming sheets of metal to the re quiredshape, interrupting the continuity of the sheets by closely arranged rows of narrow slits the slits of adjacent rows being CllS- rows being substantially parallel with the lines ofmagnetic flux in the'core, and secure provided-with multiplicity of closely arranged narrow slits piercing the body thereof and running substantially parallel with the lines or" magnetic flux in the core.

at. A plate or lamina for cores of electrical posed in staggered relation and the several apparatus provided with a multiplicity of Y closely spaced rows of narrow slits piercing the body thereof the slits or adjacent rows being arranged instaggered relation.

5. A core for electrical apparatus come prising a superposed series of thin sheets of magnetic material cement under pressure, each sheet being provioed with a multiplicity of rows'of narrow- ELISHA B. CUTTEN.



Gopies of this patent may be obtained for five cents each, by addressing the Commissioner of- Patents,

' Washington, D. G.

secured together by

Referenced by
Citing PatentFiling datePublication dateApplicantTitle
US2449021 *Jun 8, 1942Sep 7, 1948Hoover CoDynamoelectric machine
US4282451 *Apr 10, 1979Aug 4, 1981Bbc Brown Boveri & Company LimitedSolid rotor for asynchronous electrical machines
US4528466 *Mar 24, 1980Jul 9, 1985Papst Motoren KgComponents for polyphase linear motors
US4595849 *Jun 13, 1985Jun 17, 1986Les Produits Associes Lpa SaSmall a.c. motor having an oscillatory permanent magnet armature
US4613842 *May 31, 1984Sep 23, 1986Nippon Steel CorporationIron core for electrical machinery and apparatus as well as method for producing the iron core
US4839552 *May 28, 1987Jun 13, 1989Tamagawa Seiki Kabushiki KaishaBrushless DC motor
U.S. Classification310/216.106, 336/234, 310/216.46
Cooperative ClassificationH02K1/02