US 3417593 A
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Description (OCR text may contain errors)
23%., 2 3 1% T. E. LEWH$ 3,4175% METHOD AND APPARATUS FOR FORMING SQUARE OR RECTANGULAR WIRE Filed Feb. 25, 1964 v 2 Sheets-Sheet 1 INVENT OR ATTORNEYS T. E. LEWIS 3,417,593
S FOR FORMING SQUARE OR RECTANGULAR WIRE METHOD AND APPARATU Filed Feb. 25, 1964 2 Sheets-Sheet 2 PRIOR ART INVENTOR ATTORNEY w Wily/167 7 "a 3 PRIOR ART 36 II United States This invention relates to a wire treating method and apparatus and more particularly to a device for converting film coated wire having a circular cross-section into wire of substantially rectangular or square cross-section. Wire of rectangular or square cross-section possesses several highly desirable characteristics as compared to conventional round wire. Thus, in the winding of magnet coils or the like, square wire can be readily wound onto spools in uniform transverse and vertical layers wherein the big -speed spooling operation is greatly facilitated by the square cross-section of the wire which efiiciently aligns and guides the wire onto the spools. This contrasts markedly with spooling of ordinary round wire wherein the continuously curved peripheral surfaces of adjacent wire windings are prone to slip or shift laterally with respect to each other whereby, for example, a next outer layer of windings may be commenced prior to completion of a preceding inner layer, resulting in defective coils, or necessitating delays for shutdown to rectify the error.
Similarly, wire of substantially rectangular cross-sectional configuration sharply reduces gaps or wasted space normally found between adjacent turns or windings in a round-wire spooled or other layered arrangement as the flat wire surfaces will snugly abut each other. Such spacesaving with square wire permits usage of smaller spools, increases flux density, and facilitates heat transfer and thus improved in-service cooling of a coil unit by virtue of the greatly increased areas of contact between adjacent windings, among other advantages.
Hitherto, however, it has not been practically or economically feasible to convert small-gauge round wire in volume quantities. The surface of squared wire produced by previous techniques, for example, has been found to be diflicult to uniformly insulate, as by a coating of plastic film, lacquers, etc., as well as necessitating fairly elaborate and proportionately expensive apparatus.
By the method and apparatus of my invention, however, I have successfully squared round wire to thereby achieve the advantages set forth, and, more importantly, have also efiiciently squared insulated wire of relatively small gauges, hitherto deemed impractical. Further, I have found that not only can wire be squared in a rapid and expeditious manner, but also in utilizing my invention several marked improvements in dielectric and other properties of insulated wire are achieved.
It is therefore a principal object of my invention to provide a highly efiicient technique for converting conventional round wire to wire of square or rectangular cross-section.
It is a further object of my invention to provide squared wire wherein the plastic or other insulative coating thereon is substantially of uniform thickness about the wire and free from irregularities or other defects.
It is another object of my invention to provide a wire squaring apparatus which is of simple, compact and inexpensive construction, yet highly efiicient for the purposes contemplated, and which also may be easily adjusted to differing squared dimensions as desired.
A further significant object of the present invention is to improve dielectric properties of coated wire by subjecting the peripheral surface thereof to a rolling acatent O tion, which effectively closes any pinholes or similar surface defects present in the insulation.
Another object is to provide a method and apparatus for improving the dielectric properties of coated wire and simultaneously reshaping the same by subjecting the peripheral surface thereof to a rolling action.
Another object of my invention is to provide a wiresquaring device of compact and lightweight form which in use is capable of being hand-held if desired, and in which case the squaring device itself may be manually manipulated to guide the squared wire onto its associated spool.
A further important object is to provide a wire-squaring apparatus which, while compact and inexpensive, is capable of a wide range of wire width and height adjustment, whereby a desired preselected wire resistance may be obtained, for example, or the dimensions of the desired wire can be accurately predetermined to snugly fit a given coil form as to width or height thereof.
Other objects and advantages of my improved method and apparatus will be apparent from the following detailed description taken in connection with the accompanying drawings, in which:
FIGURE 1 is a side diagrammatic elevation of a handheld squaring device according to my invention in use between supply and take-up wire spools;
FIGURE 2 is a top plan view of the arrangement of FIGURE 1;
FIGURE 3 is a side elevation, partly in section, illustrating my improved wire squaring apparatus;
FIGURE 4 is a top plan view of the apparatus of FIGURE 3;
FIGURE 5 is a partial transverse cross section of a prior art magnet spool having several conventional insulated round wire windings thereon;
FIGURE 6 is a cross section similar to FIGURE 3 showing the improved winding arrangement achieved by my invention;
FIGURE 7 is a fragmentary section generally similar to FIGURE 6, wherein strips of paper or the like are interposed between successive convolute layers of the winding;
FIGURE 8 is an enlarged cross-section of a film-coated insulated wire produced according to my invention;
FIGURE 9 is similar to FIGURE 8, disclosing coated squared wire produced by prior art teachings.
My wire squaring apparatus is shown generally at 10 in the drawings, through which a running length of conventional round wire 11 is fed, as from right to left in FIGS. 1 and 2. The wire, which may be lacquered, enameled or similarly insulatively coated, is delivered from a supply spool thereof as at A, and is taken up by a similar spool at B or other coil form which is preferably driven to thereby pull the wire through the apparatus.
Referring more particularly to FIGS. 3 and 4, the device 10 includes a base 12 which includes upstanding integrally formed forward and rear members 13, 14 respectively. Each member is apertured to receive therein a bored wire-guiding plug 16 of a material preferably having a low coefficient offriction, such as polytetrafluoroethylene. The plugs are releasably retained within the blocks 13, 14 by any convenient means whereby the same may be readily removed and replaced upon becoming worn. The plastic plugs are axially bored to a diameter slightly greater than that of the maximum wire size normally handled by the apparatus so as to guide the wire cleanly therethrough without undue friction or binding. The members 13, 14 and their associated guide plugs 16 are disposed in longitudinal axial alignment.
Disposed between the guide members 13, 14 are the roller squaring assemblies 18, 19 which include respectively longitudinally spaced pairs 20, 21 of squaring rollers. The roller pairs are disposed perpendicular to each other and in alignment with the apertures through the guide plugs 16, whereby the wire 11 as clearly illustrated is trained between the successively spaced series of parallel rollers. The rollers are cylindrical annuli of hardened, polished steel, and are mounted for free rotation on axles or bearing mounts 22.
The bearing mounts 22 are respectively carried by and fixed with respect to right angularly related bifurcated and cantilevered support blocks 23, 24, each of which is slotted at 29 to define a pair of legs having a substantially U-shaped configuration. The blocks 23, 24 are integrally formed with the base 12 and disposed adjacent each other with the leg pairs thereof projecting in opposite directions. The rollers are mounted respectively on each of the legs of the blocks near the closed end of slots 2e thereof to thereby dispose the same in closely adjacent longitudinally spaced relation. While in FIGS. 3 and 4 the roller pairs are shown as rather well spaced apart longitudinally of the device for clarity of illustration, in actual practice, the roller pairs 18, 19 are as closely spaced as feasible for reasons pointed out hereinafter. The legs of each U-shaped support block 23, 24 are transversely threaded and tapped to receive an adjustment screw 26. Thus, by virtue of the cantilevered mounting of blocks 23', 24 and the slots 29 between the leg pairs thereof, threaded adjustment of either screw 26 effects narrowing or widening of slot 29 between the support block legs in cooperation with the inherent resiliency of the metal support blocks 23, 24, whereby the wire feed gap between the adjacent parallel rollers may be precisely regulated within narrow limits. In this manner the dimensions of the wire feed path through the roller pairs can be adjusted in accordance with the particular size of wire being fed through the apparatus with respect to the desired squared size thereof to be produced.
The inherent resiliency of the U-block legs about the connected ends thereof will act as a hinge for adjustment of the rollers to a limit determined by the setting of the adjustment screws 26. If desired, screws 26 may be provided with suitable indicia or calibrations to visibly indicate the spacing of the roller pair associated therewith.
By virtue of the positioning of the roller pairs 20, 21 at right angles to each other, it will be seen that they act in rapid succession upon the wire fed therebetween to press or iron the same into a rectangular configuration. Thus, with the round wire 11 threaded through the apparatus and attached to a take-up spool, and thereafter rapidly drawn through the machine, the rear set of rolls 20 will iron and flatten the wire on two sides thereof from a round cross-section to a cross-section wherein the sides of the wire are flattened and the top and bottom thereof will remain curved. Immediately thereafter, however, the wire passes between the second and forward set of right angularly disposed rollers 21 which iron the curved upper and lower faces of the partially squared wire into substantially flat form, thereby flattening all four sides of the wire as the same is delivered through the forward guide block 13, forming a rectangular or substantially square wire 11 as seen in FIG. 8.
If the roller pairs 20, 21 are equally gapped as determined by adjustment screws 26, the wire will partake of a square con-figuration as in FIG. 8. If desired for a particular application, however, the roller pairs may be set to differing or unequal gaps, whereby the wire will be reshaped to a rectangular cross-section.
A significant physical advantage of squared wire produced by my invention as compared to conventional rounded wire is schematically illustrated in FIGS. and 6, wherein a series of layers or windings of wire are shown as applied to a spool or other core assembly fragmentarily illustrated at 27. With the conventional layered windings of ordinary round wire indicated at 11a, it will be seen that substantial gaps 28 inherently exist between the several windings, thereby requiring additional radial depth and/ or height of the spool to accommodate a given amount of wire.
By the method and apparatus of the instant invention, however, the wire is substantially uniformly squared or otherwise rectangularly configured as seen in FIGS. 6-8, and can be rapidly wound onto spools or into pails or drums, for storage or immediate shipment and use, wherein the substantially fiat sides of the square wire promote uniform and precise alignment of the wire both horizontally and vertically in core-wound formations.
Concomitantly, the usual voids 28 between adjacent wires as seen in FIG. 5 are all but eliminated, thereby materially reducing the necessary height and/or width of a spool or other receiver. Such maximized space utilization is especially apparent in coil windings that employ layer insulation between successive wire layers, as commonly employed in transformer coils. FIG. 7 clearly illustrates the advantages of squared Wire 11 produced by my invention in such a coil, wherein intermediate layers of insulation 32 are provided. It is readily apparent that when conventional interlayers 32 are employed in a round-wire coil, the area represented by gaps 28 increases dramatically, 0n the order of 50%, from the area of gaps 28 in a non-interlayered round-wire coil as in FIG. 5. This is because interlayer insulation 32 prevents even the slightnesting between wire layers seen in FIG. 5. By contrast, squared-wire coils are equally as compact relative to waste space, whether without insulation as in FIG. 6, or with insulation 32 as in FIG. 7.
Accordingly my invention sharply reduces betweenwire gaps, thereby promoting more compact coils, with resulting improved heat transfer, fiux density, etc.
In operation, my device 10 is positioned between a round Wire supply source, such as a spool A, FIGS. 1 and 2, and a take-up spool, as at B, or other receiver. Where the square wire receiver is a spool or reel A, the squaring device 10 can be associated with conventional traversing mechanism for oscillating or reciprocating the device It! generally as indicated by arrow C, FIG. 2, whereby successive convolute wire layers may be neatly built up. A feature of my device, especially as compared with known squaring equipment, resides in its compact size. By virtue thereof, my squaring apparatus can easily be hand-held rather than machine-mounted if desired, or as may be required for particular winding techniques. Thus, the apparatus 10 is diagrammatically illustrated in FIGS. 1 and 2 as being hand held and may readily be manually traversed as required without difficulty on the part of the operator.
In either case, the apparatus 10 will be positioned as close as feasible to the take-up reel B. Such positioning insures the accurate guiding of the wire therethrough and onto the spool thereby eliminating conventional wire guides, and also prevents any axial twisting of the wire by maintaining a minimum distance between the squaring roll and the take-up reel.
A feature of the instant invention is that relatively small gauge film coated wire may be successfully equared therewith. At the present time it is not feasible to coat or enamel pre-squared wire smaller than #14 or #15 AWG. With the apparatus illustrated, however, I have been able to square pro-coated wire of appreciable smalled gauges as from #14 to #23 or #24 gauge, and even finer wire may be squared according to my invention.
A very important aspect of the present invention relates to the reshaping of the insulation coating of plastic, lacquer, etc., along with the wire itself. The successive ironing effects of the roller pairs roll and reshape the insulative coating uniformly with the squaring of the wire itself, whereby the squared wire delivered from the apparatus is as fully protected as previously. The significance of my invention in this regard can be further appreciated when the difficulty of coating previously squared bare wire is considered. When coating by the usual techniques is practiced with square wire, the resultant coating is quite often of irregular thickness and therefore the insulative property thereof may not be accurately determinable. While such a coating tends to be of expected thickness on the flat faces of the wire, it may be excessively thin or thick and thus lacking in uniformity along and around the corners or edges of the wire. The enlarged sectional view of FIG. 9 illustrates the disadvantages found when a pre-squared wire 35 is subsequently insulatively coated with enamel, plastic film, etc. The thin insulating coating initially applied thereto in liquid form tends to accumulate or gob up at the sharply curved or angled corners of the wire, as at 36. Further, such accumulation is of irregular thickness along such edge, depending upon the orientation of the wire at the time of insulation application among other factors. Similarly, the coating process may result in areas as at 37 along the wire corners which have an undesirably thin insulative film thereon. It follows, therefore, that such squared and coated wire produced prior to my invention exhibits undesirable diverse and non-uniform insulative characteristics, entirely apart from the fact that hitherto, generally, it has not been practical to square the finer, smaller dimension wire sizes.
In sharp contrast to the prior art, pre-coated wire which has been squared according to my invention partakes 0f the highly desirable cross-section seen in the enlarged view of FIG. 8, wherein the wire 11 is found to have a substantially uniform, unvarying and pinhole-free film of insulation 33 therearound, thereby insuring reliability in test and usage.
In addition to the physical advantages achieved by the present invention of winding ease, space-saving, uniform layering, better heat transfer, etc., I have also found that surprising and unexpected improvements in the dielectric and related properties of the coating on the wire are also achieved by the rolling action of my device to which the wire is subjected. Such improvements may be best illustrated by the following test results:
Aluminum round wire of #17 AWG having a polyester coating thereon constitutes a standard wire product sold and utilized in the industry. Tests made of the coating thereon indicated a dielectric kilovolt rating of 5.5 and a volts/mil rating of 1833. This standard coating round wire was then squared by the apparatus as above set forth. After squaring, the dielectric kilovolt reading of the rolled coating was found to have increased to 10.2, an improvement of 85 /2%. An even greater increase was shown in the volts/mil test, which indicated 3335 for the squared wire, an improvement of 142%. Further, scrape resistance of the coating showed an improvement of approximately These striking qualitative improvements in wire treated according to my invention are noteworthy from several practical standpoints in that, for example, a somewhat thinner coating than is presently customary may be initially applied to round wire. The wire thereafter will be squared by the apparatus 10 to produce a resultant square wire product which will have the acceptable coating test characteristics of conventionally thicker-coated ordinary round wire, despite the thinner initial coating thereof, thereby eflecting significant economies in coating material.
It is to be noted that the action on the wire in converting the same from round to square form and achieving the results set forth in almost entirely of a rolling or reshaping nature as distinguished from a drawing technique.
There is, however, a slight resultant elongation of the wire in passing through the roller assemblies.
What I claim is:
1. An apparatus for squaring round wire, comprising a base, two longitudinally closely spaced roller assemblies carried by said base, each of said roller assemblies including a slotted U-shaped support member defining substantially parallel spaced legs, a freely rotatable roller mounted upon each of said legs adjacent the closed end of said slot in parallel spaced relation to the roller on the adjacent leg, adjusting means bridging the gap between said legs adjacent the open end of said plot adjusting the spacing between said legs and thereby the spacing between said rollers against the resilient resistive force of said U-shaped block, each of said roller assemblies being mounted on said frame to dispose the respective roller pairs of each block at right angles to each other to thereby define a longitudinal path of travel for the wire between the rollers of said pairs for reforming said wire into substantially square configurations.
2. A method of converting coated round wire to coated rectangular wire while winding a running length of said wire from a supply source onto a take-up core comprising the steps of (1) holding by hand between said supply source and said take-up core a means for flattening two pair of opposed sides of said coated roun-d wire,
(2) feeding said coated round wire from said supply source through said hand held means for flattening two pairs of opposed sides of said coated round wire thereby converting said coated round wire into coated rectangular wire,
(3) and, thereafter, immediately winding said coated rectangular wire on said take-up core.
3. A method of converting coated round wire to coated rectangular wire while winding a running length of said wire from a supply source onto a take-up core as defined in claim 2 including the additional step of laterally traversing the take-up core with said means for flattening two pairs of opposed sides of said coated round wire whereby said wire is wound evenly on said take-up core.
4. A method of converting coated round wire to coated rectangular wire while winding a running length of said wire from a supply source onto a take-up core comprising the steps of (1) positioning a means for flattening two pairs of opposed sides of said coated round wire between said supply source and said take-up core,
(2) feeding said coated round wire from said supply source through said means for flattening two pairs of opposed sides of said coated round wire thereby converting said coated round wire into coated rectangular wire,
(3) thereafter, immediately winding said coated rectangular wire on said take-up core,
(4) and laterally traversing the take-up core with said means for flattening two pairs of opposed sides of said coated round wire whereby said wire is wound evenly on said take-up core.
CHARLES W. LANHAM, Primary Examiner. L. A. LARSON, Assistant Examiner.
US. Cl. X.R.