US 3006981 A
Abstract available in
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Description (OCR text may contain errors)
Oct. 31, 1961 w. H. WEBER 3,006,981
SQUARE THROAT CABLE CONNECTOR Original Filed Nov. 14, 1957 INVENTOR. "441715? 1% WEfiER United States Patent Continuation of application Ser. No. 696,434, Nov. 14, 1957. This application May 22, 1959, Ser. No. 815,073 2 Claims. (Cl. 174-65) This application is a continuation of my co-pending application Serial Number 695,434, filed November 14, 1957 and now abandoned.
The invention relates to tubular connector fittings adapted for securing armored electric cable to outlet or junction boxes, and more particularly to a connector fitting which is adapted for the passage therethrough of the largest number of insulated conductor size combinations available in conventional armored cable, adapted to be intruded into the connector, without deformation or damage to its insulated conductors while limiting the intrusion of the armor of such cable thereinto from one end thereof.
More specifically, the invention relates to a connector fitting which complies with National Electric Code Requirements, and in a three-eighths trade size thereof, is adapted for use with known armored cable of compatible range enclosing two, three or four No. 14 or No. 12 insulated conductors each having an overall diameter of three-sixteenths of an inch, or two No. insulated conductors each having an overall diameter of seven thirtyseconds of an inch.
The present invention constitutes an improvement in cable connectors disclosed, respectively, in Patent No. 2,485,676 to George C. Thomas, Jr., and Patent No. 2,600,371 to Martin D. Bergan.
Known cable connectors, as disclosed, for example, in the above-identified patent-s, comprise a tubular shell having a conventional screw-thread and retention nut at one end thereof for securing the connector in an apertured wall of an outlet or junction box, and at its opposite or inner end, with an integral stop means partially closing the said inner end thereof and adapted to serve as a stop bushing for limiting the intrusion therein of armored electric cable of compatible range or size.
Such known devices also included an adjustable clamp of inverted V-shape form with its legs extending through a slide opening provided therefor, intermediate the ends of the connector, to engage an intruded cable lengthwise thereof and on opposite sides of its top or crown portion in such manner as to clamp the cable. without deforming the same, the legs of the V-clamp usually extending at an acute angle to the axial center of the connector and free to rock outwardly, at least to a limited extent so that in the event of an outward pull on an intruded cable, the advanced edges of the clamping legs will be drawn down thereon and the cable thus held against being withdrawn from the connector.
It is known that National Electric Code requirements specify that the opening defined by an integral stop means at one end of a cable connector of trade size, be eifective to not only limit the intrusion therein from its opposite end, of an armored cable of compatible range, dimension, type or size, but at the same time to permit the passage through the opening defined by the stop means,
of the largest number of insulated conductor size combinations available in such armored cable, without deformation or damage to the insulation thereon by the inner peripheral edge of the metal armor at the intruded end of the cable.
In similar cable connectors as known heretofore, such integral stop means defined an end opening of such reduced area, size or configuration that the number of insulated conductors in an armored cable which could be safely drawn therethrough was limited by the particular configuration thereof.
Accordingly, it is an object of the invention to provide an improved stop means in cable connectors of the character specified whereby to provide an end opening therein having a greater area than in prior art connectors without increasing the trade size of the connector.
Another object of the invention is to provide an improved integral stop means in cable connectors of the character specified which defines an end opening therein adapted for the passage therethrough of the largest number of insulated conductor size combinations, in compatible armored cable, adapted to be intruded into said connector, without deformation thereof or damage to the insulation on said conductors while limiting the intrusion of the cable armor thereinto from the opposite end of the connector.
Other objects and advantages of the invention will be set forth in part hereinafter and in part will be obvious herefrom, or may be learned by practice with the invention, the same being realized and attained by means of the instrumentalities and combination pointed out in the appended claims.
The accompanying drawing, referred to herein and constituting a, part hereof, illustrates one embodiment of the invention and, together with the following descrip tion, serves to explain the principles thereof, the drawing being intended to illustrate a trade size cable connector drawn to twice scale size. Thus, the drawing shows the connector on a scale from which actual dimensions are available as a part of this disclosure.
In the drawing:
FIG. 1 is a plan view of a sheet metal stamping of predetermined configuration from which the improved cable connector is formed;
FIG. 2 is an end-edge view of the sheet metal stamping showing one marginal edge thereof as rounded to present a smooth edge face;
FIG. 3 is an end View of an improved cable connector as formed from the stamping shown in FIG. 1;
FIG. 4 is a side elevation of the improved cable connector shown in FIG. 3;
FIG. 5 is a longitudinal sectional view of the improved cable connector as secured in an apertured wall of an outlet box and showing an armored cable with a plurality of insulated conductors as a part thereof;
FIG. 6 is a fragmentary end view of the connector shown in FIG. 3, and illustrating a maximum number of either No. 14 or No. 12 insulated conductors in a compatible armored cable as they are passed through the partially closed end of the tubular connector; and
FIG. 7, is a similar fragmentary view illustrating two No. 10 insulated conductors in a compatible armored cable as they are passed through the partially closed end of the tubular connector.
Referring to the drawing and to FIGS. 1 and 2 in particular, a sheet metal stamping 10, of suitable thickness and of the configuration illustrated, is cut from coiled strip stock of cold rolled steel, for example, having the desired final width, and rounded marginal edges as indicated at 12.
In the production of the metal stamping 10, the strip stock is fed into a special multi-operation mill wherein one marginal edge portion thereof is successively worked to form a linear kerf or groove 14, parallel with and adjacent one marginal edge 12, to provide a relatively narrow longitudinally extending area of reduced thickness therein which diminishes from its maximum depth at a linear shoulder 16, defined thereby, to a point short of the adjacent marginal edge 12.
In a subsequent operation, portions of the strip stock along the adjacent marginal edge 12, are cut out at spaced points as at 18, to define four equally spaced substantially triangular projections 20, having their root end in the linear kerf or groove 14-, defining an area of reduced thickness, and presenting aligned, rounded edge faces of normal thickness. At the same time, a longitudinally extending bead 22 of substantially semi-circular form in cross-section, is rolled or struck out of the plane of the incomplete stamping 10, substantially centrally between its marginal edges 12.
Subsequently, an elongated opening or aperture 24 is cut through the stamping 10, along one side of the raised bead 22 and intermediate the opposite ends thereof, and a substantially rectangular boss 26, struck out of the plane thereof and extending transversely between the elongated opening 24 and the opposite marginal edge 12 of the stamping 10, the boss 26 presenting an inclined fiattop side 28 having an opening 36 pierced therethrough as best shown in FIGS. 1 and 2.
In the final operation, a locking tab 32, is formed on the end of the stamping 1i), and an aligned complementary slot 34 in the opposite end thereof, with the successive severing of each stamping 11} from the strip stock as will be understood.
After each stamping 10, so formed, has been severed from the coiled strip stock, it is fed into engagement with a suitable mandrel, forming a part of a special rolling mechanism, on which the four projections 29 are bent inwardly toward each other at substantially right angles thereto While the stamping is being rolled into circular form and the tab 32, at one end thereof, finally locked in the complementary slot 34, provided therefor in the opposite end of the stamping It The extended free ends 22' of the linear bead 22 serve to obviate a gap in the annular shoulder 40 upon the rolling of the stamping 10 into circular form as will be understood.
With the stamping 10 thus rolled into tubular form with its opposite ends locked together in abutting, dovetailed relation, a tubular connector 36, substantially as illustrated in FIGS. 3 and 4, is provided. Subsequently, each tubular connector 36 is placed on a suitable form and the four projections 21 at one end thereof finally bent at right angles to its axial center and in right angular relation with each other substantially within one end of the tubular connector 36, whereby the projections 20 form the equivalent of a stop bushing presenting a square opening or throat therein having rounded, defining edge faces 38, with their respective opposite ends in abutting relation. Thus, a square opening in full outline is provided in one end of the connector 36, presenting an area which is particularly adapted to receive therethrough, as exemplified in FIGS. 6 and 7, the largest number of insulated conductor size combinations available in commercial armored cable having an overall external diameter compatible with, corresponding to or utilizable with the size of the tubular connector herein specified, without deformation of or damage to the insulation on its conductors while limiting the intrusion of the armored cable C, with or without the usual, well known anti-short bushing, into the tubular connector from its opposite end.
From an inspection of FIGS. 3 and 4, it will be apparent that in the formation of the stamping 10, of FIG. 1, into tubular form, the raised bead 22 is bent into an annular shoulder 40, and that the area of reduced thickness 14, forms a short, reduced external diameter 42 smaller than the external diameter of the body of the connector 36 extending between the raised bead 22 and the shoulder 16, defining the said area of reduced thickness, the reduced external diameter 12 having a dimension such that the bent or root end of the inturned projections 20 is not torn or otherwise mutilated during a screwthreading operation on the adjacent body portion of the connector.
After the tubular connector 36, has been formed as above described, the opening 31) through the transverse boss 26 is screw-threaded for the reception of a set screw 43, and, a screw-thread 44 suitably cut or rolled in the outer periphery of the connector body 36 from the reduced external diameter d2 substantially to the annular shoulder 40, for the reception of a dished lock-nut 46, whereby the connector is secured in an apertured wall of a junction box B, as in FIG. 5, the reduced external diameter 42 of the connector serving to pilot the lock-nut 46, onto the screw-threads 44 in the threading thereof on the connector by reason of the fact that the reduced external diameter 42 is smaller than the root diameter of the screw-thread 44-, as best shown in FIG. 4.
As shown in FIG. 5, the tubular connector 36 includes a V-shaped clamp 48 provided with a clearance opening 5t; for passage of the set-screw 43 therethrough, whereby the clamp 48 is adjustably secured on the connector 3'6 in inverted, straddled relation with respect to the boss 26, with one leg thereof extending through the slot 24. The free end of each leg 52 of the clamp 48 is formed on a radius to present an accurate surface to the periphery of an armored cable C when intruded into the connection 36, to secure the same against relative endwise movement upon final adjustment of the set-screw 43.
By way of example, an armored cable C is shown in FIG. 5, as intruded into the tubular connector 36 and secured thereto by means of the clamp 48, the inner end of the cable being formed square therewith and in abutment with the inturned projections Ztl, or, a known form of anti-short bushing fitted between the end face of the armored cable and the inturned projections 20, with the exposed insulated conductor ends of the armored cable drawn through the square throat of the tubular connector 36, the rounded edge faces 38 of the square throat defining projections 20, protecting the insulation on the exposed cable conductors against abrasion.
While the invention has been illustrated and described with respect to a preferred embodiment thereof, it is to be expressly understood that modifications may be made therein without departing from the invention concept underlying the same. For example, the tubular connector 36 may be provided with a known cable securing clamp comprising complementary, relatively adjustable, semi-circular elements in opposed relation and adapted to be secured on an intruded armored cable by means of suitable screws. Therefore, the invention is not to be limited except as is necessitated by the prior art and the scope of the appended claims What is claimed is:
1. A tubular connector for armored electric cable adapted to snugly enclose four insulated conductors each having a substantially common outer diameter comprising a fiat blank cut out along an axial marginal edge thereof to define four equidistant T-shaped projections extending from said marginal edge, said blank being axially tubularly formed to define said connector for receiving an end portion of said cable therein, said T- shaped projections being bent inwardly at right angles toward each other and normal to the axial center of the connector and adapted to be abutted by said cable end portion, and being so proportioned that, when so bent inwardly, the outer ends of said projections will be in abutment and will define one end of said connector and the full outline of the sides and corners of an equilateral rectangular opening at said end of the connector with each side of said opening being equal to twice said insulated conductor diameter, and means for securing said cable end portion fixedly within said connector whereby said connector may receive and similarly cooperate with said four insulated conductors or a cable with a lesser number of larger size insulated conductors.
2. In a tubular connector as set forth in claim 1, said fiat blank being provided, adjacent to and parallel with said axial marginal edge, with a linear groove defining a linear area of reduced thickness parallel to and spaced from said axial marginal edge, said T-shaped projections extending from said linear area of reduced thickness to said axial marginal edge, said linear area in the formed tubular blank defining a reduced circumferential portion at said end of the tubular connector marginally beyond the T-shaped projections.
References Cited in the file of this patent UNITED STATES PATENTS 2,485,676 Thomas Oct. 25, 1949 2,506,398 Thomas May 2, 1950 2,600,371 Bergan June 10, 1952 2,821,567 Bergan Jan. 28, 1958