US2510598A - Method of making iron cores - Google Patents

Description

June 6, 1950 H. E. OLES 2,510,598

METHOD OF MAKING IRON CORES Filed Dec. 12, 1944 ll llllllllllll llll lllllllllllll lmmll llllllm imllllllll" mmmm I ii a IN VEN TOR. ll ererf E 0/ 5 WGWL 47 F ORA E Y rmma Juno 6, 1950 2,510,598

UNITED STATES PATENT OFFICE METHOD OF MAKING IRON CORES Herbert E. Olea, Indianapolis, Ind., assignor to P. B. Mallory a 00., Inc., Indianapolis, Ind., a corporation of Delaware Application December 12, 1944, Serial No. 567,850

Claims.

The present invention relates to the art of forming ferromagnetic core members, and, mor particularly, to a novel method of making iron cores from fine-gauge ferromagnetic wire, and to the products of such method.

It is already known to produce a flexible fabric or web including war strands of textile material and weft strands of a suitable paramagnetic maierial, such as for exampl iron wire of appropriate thickness. This fabric or web was wound up into a core body of appropriate shape, characterized by the presence of a large number of parallel-spaced fine ferromagnetic strands.

Cores provided in accordance with this method 4 th present invention will become apparent from the following description, taken in conjunction with the accompanying drawing, in. which:

Fig. 1 illustrates the weaving pattern of a ferromagnetic fabric embodying the present invention; the thickness of the several strands and the spacing thereof being greatly exaggerated for rea sons of clarity;

Fig. 2 depicts a section taken on line 2-2 of Fig.

Fig. 3 shows a ferromagnetic core of cylindrical shape wound up from the fabric of the invention;

Fig. 4 is a diagrammatic view showing the treatment of the wound core body by means of a suithad the advantage of low eddy current losses but is able solvent bath; were otherwise not particularly eiilcient in view Fig. 5 is a similar view illustrating the conof their relatively low "space factor." solidating step in the method of the invention in- It is one of the principal objects of the present cluding the application of pressure with or withlnvention to improve the iron cores of the deout the simultaneous application of heat to the scribed generic type and particularly to increase go preformed core body; and the space factor" thereof, that is, to increase Fig. 6 is a perspective view of the finished core. the proportion of the core volume occupied by the While a preferred embodiment of the invention ferromagnetic wire to the total volume of the core. is described herein, it is contemplated that con- It is another object of the present invention to siderable variation may be made in the method of provide a novel type of flexible fabric constituted procedure and the construction of parts without of warp strands of electrically insulating diamagdeparting from the spirit of the invention. In netic material and of weft strands of ferromagthe following description and in the claims, parts netic material, the said warp strands being soluble will be identified by specific names for convenina suitable solvent so that upon winding up the ience, but they are intended to be as generic in fabric into a core structure, the warp strands may their application to similar parts as the art will be dissolved and the remaining body compressed permit. and consolidated thereby to increase the space Referring now more particularly to Figs. 1 and 2 factor of the finished product. of the drawing, reference character It denotes It is a further object of the invention to provide the warp threads or strands, while reference a novel and improved method of forming iron character ll denotes the weft thread or strand. cores in which warp strands of an electrically The warp strands may be of any suitable insulating thermoplastic diamagnetic material are electrically non-conductive diamagnetic macombined by weaving with weft strands of a paraterial, such as for example conjugated polymagnetic material to constitute a fabric subsemers, cellulosic materials as natural and requently wound up on a core, the wound core strucgenerated cellulose and ester and others thereof, ture being subjected to heat and pressure to cause synthetic resins, elastomers, and the like, which the thermoplastic diamagnetic material to flow, are either soluble in a suitable solvent or which whereby the core structure is consolidated and are thermoplastic or fusible in character. The the space factor thereof is increased. weft strand or strands may be of any suitable The invention also contemplates a novel type p netic ma ri l ch as. f r pl n of core structure comprising a bundle of substanwire of appropriate thickness, generally less than tially parallel-spaced iron wires of greatly re- 0.01 inch in diameter, and is preferably covered duced diameter bonded together by means of or coated with one or more suitable electrically thermoplastic diamagnetic materials which is insulating compounds or materials including insimple in construction, has excellent physical sulating varnishes, lacquers, natural and synproperties, such as high space factor and low thetic resins, elastomers, cellulosic materials, and eddy current losses, and which may be readiLv the like. Of course, itis desirable to so select the manufactured on a quantity production scale at said covering or coating materials for the paraa low cost. magnetic strands that they are not attacked by Other and further objects and advantages of the solvent of the warp strands or, if thermoplasno, a tic and fusible warp strands are employed, that the said coating materials have a higher temperaaccordance with the specific application which is contemplated. The diamagnetic strands extend longitudinally of the web, while the paramagnetic strand will extend transversely of the web, re versing its direction at alternate edges of the web to constitute selvedge l2, so formed as to prevent raveling.

The ferromagnetic web embodying the inVen-' tion may be produced by means of conventional weaving procedures and may be stored and shipped in such condition, if desired. The iron cores may be formed from the said web in various ways. For example, the ferromagnetic web may be wound up to constitute a cylindrical or rodlilse core body it, having a slightly larger diameter than the desired core, as this is shown in Fig. 3.

This wound body is now further treated in order to substantially eliminate the warp strands and thereby to increase the space factor. In case the warp strands are soluble in a suitable solvent, the wound core body is introduced into a treating tank it having a quantity of the solvent i therein so that the core body is fully submerged in the solvent (Fig.4). After allowing the solvent to act upon the core body for a sufiicient length of time, most of the warp strands will be dissolved or at least considerably softened. The core body is now removed from the solution and is inserted between suitably formed pressure jaws l6 and H (Fig. 5). By pressing the said jaws or pressure dies together, the remaining portion of the dissolved or softened warp strands will be squeezed out and only the ferromagnetic Weft strands will remain in a strongly consolidated and condensed position. At the same time, the

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dimensions of the core bodywill be reduced to those of the desired core. While most of the material of the warp strands will be removed, a small residual amount thereof will be instrumental in permanently bonding the wound structure and will prevent unwinding thereof. It has been found that the finished core structure has excellent magnetic properties, low eddy current losses, and a very high space factor.

As an alternative of the method of the invention, when the warp strands are constituted of a thermoplastic or fusible'material, the solvent applying step may be omitted and heat and pressure may be simultaneously applied to the wound core structure by means of the apparatus shown in Fig. 5. In this case, jaws l6 and ll are heated, for example by means of an electric heating element (not shown), to a temperature sufficient to cause fusion or at least softening of the thermoplastic material of the warp strands. The simultaneous application of heat and. pressure will cause the warp strands to soften and to flow so that their major portion will bev squeezed out of the wound core body, while their remaining portion upon cooling will permanently bond the weft strand or strands into an integral body of reduced dimensions. The core structure obtained in this manner is shown in Fig. 6 and is likewise characterized by low eddy current losses and a high space factor.

It will be noted that the principles of the invention provide various important advantages.

Of these the most important is that iron cores of a great variety of shapes and sizes may be readily built up from ferromagnetic wire of very small diameter, without the difficulties heretofore encountered in building up cores from fine wire by means of bundling, and the like procedures.

It is also to be observed that the cores embodying the invention substantially eliminate the diamagnetic strands from the finished core struc ture so that the warp strands do not detrimentally affect the space factor of the finished core.

Moreover, the methods of the invention are very simple and may be readily applied to the quantity production of iron cores from fine-gauge iron wire without requiring any expensive or complicated special equipment.

Although the present invention has been disclosed in connection with a few preferred embodiments thereof, variations and modifications may be resorted to by those skilled in the art without departing from the principles of the present invention. Thus, cores having other than a solid cylindrical shape may be made by substantially the same method, such as tubular cores, and o, I or H-shaped cores. In some cases it may be found advantageous to reverse the relative position of the diamagnetic and paramagnetic strands and to make the warp strands of paramagnetic material and the weft strand of diamagnetic ma terial. All these variations and modifications are considered to be within the true spirit and scope of the present invention, as disclosed in the foregoing description and defined by the appended claims.

What is claimed is:

1. The method of forming core structures for electromagnetic devices which comprises provid ing a web with warp strands of relatively electrically-non-conductive diamagnetic material and weft strands of a wire of ferrous material, winding up a predetermined length of said web to constitute a core, subjecting said core to a solvent treatment to bring the warp strands at least into a semi-fluid state, and subsequently applying pressure to said core to eliminate the major portion of the material of the warp strands and to obtain a compacted structure substantially consisting of closelyspaced ferrous weft strands bonded together by the remainder of the material of said warp strands.

2. The method of forming core structures for electromagnetic devices which comprises providing a web with warp strands of a diamagnetio dielectric material and weft strands of a wire of ferrous material covered by a thin electrically insulating layer, rolling up a predetermined length of said web to constitute abody slightly larger in diameter than that of the desired core,

subjecting the said body to a solvent treatment adapted to convert the warp strands at least into a semi-fluid state without substantially attacking the insulating layer of the weft strands, and

applying pressure to said body to eliminate the said core with a solvent to dissolve and to remove at least the major portion of the material of the warp strands therein,- and subsequently applying pressure to said substantially eliminate air spaces therefrom and to obtain a dense core structure consisting of closely spaced ferrous weft strands bonded together by the remainder of the material of said warp strands.

4. The method of forming core structures for electromagnetic devices which comprises providing a web with warp of a diamagnetic material soluble in a "suitable solvent and weft strands of a ferrous material coated with an electrical insulating material, rolling up a predetermined length of said web to constitute a body largerindiameterthanthat ofthedesiredcore, treating said body with a liquid which is a solvent for the said warp strands and substantially a non-solvent for the coating of the said weft strands, and subsequently compressing the said body to squeeze outthe major portion of the material of the warp strands to provide a core structure of the desired dimensions character- 8 iaed by a high space factor and low eddy current low, said core structure consisting of closely spaced ferrous weft strands electrically insulated from each other by coatings of said insulating material and bonded together by the remainder of the material of said warp strands.

HERBERT E. OLES.

REFERENCES CITED The following references are of record in the tile of this patent:

UNITED STATES PATENTS

Claims (1)

1. THE METHOD OF FORMING CORE STRUCTURES FOR ELECTROMAGNETIC DEVICES WHICH COMPRISES PROVIDING A WEB WITH WARP STRANDS OF RELATIVELY ELECTRICALLY-NON-CONDUCTIVE DIAMAGNETIC MATERIAL AND WEFT STRANDS OF A WIRE OF FERROUS MATERIAL, WINDING UP A PREDETERMINED LENGTH OF SAID WEB TO CONSTITUTE A CORE, SUBJECTING SAID CORE TO A SOLVENT TREATMENT TO BRING THE WARP STRANDS AT LEAST INTO A SEMI-FLUID STATE, AND SUBSEQUENTLY APPLYING PRESSURE TO SAID CORE TO ELIMINATE THE MAJOR PORTION OF THE MATERIAL OF THE WARP STRANDS AND TO OBTAIN A COMPACTED STRUCTURE SUBSTANTIALLY CONSISTING OF CLOSELY SPACED FERROUS WEFT STRANDS BONDED TOGETHER BY THE REMAINDER OF THE MATERIAL OF SAID WARP STRANDS.

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