US2643366A - Terminal of the grommet type - Google Patents

Description

June 23, 1953 Q. BERG I TERMINAL OF THE GROMMET TYPE Filed Feb. 12, 1949 7. INVENTOR BY, QOf/VT/N 559 Patented June 23, 1953 UNITED STATES PATENT OFFICE TERMINAL OF THE GROMME'I TYPE Quentin Berg, New Cumberland, Pa., assignor to Aircraft-Marine Products Inc., Harrisburg, Pa.

Application February 12, 1949, Serial No. 76,070

4 Claims.

This invention relates to electrical terminals and to methods of making and applying them, and to electrical connections made by use of such terminals.

When the maximum dimension of an electrical terminal must be maintained very small, it has been common practice to use various types of eyelets. Most of these eyelets merely had a tu bular portion at their center with an annular flange extending therefrom. In use, an electrical conductor or wire was looped around this tubular portion or the strands of a stranded conductor split and wrapped around bi-laterally, and the tubular portion (with or without breaking into fingers) was forced down and outward and compressed onto the wire. Such eyelets were generally recognized as inferior terminals having relatively poor electrical and mechanical characteristics. In an effort to improve these eyelets the compressed assemblies were usually dipped in solder to provide them with greater strength and electrical stability.

Besides these disadvantages. eyelet type terminals found in the prior art could not utilize the sheet metal stock from which they were made economically.

An object of this invention is to provide compact electrical terminals which have inherently greater mechanical strength and electrical conductivity than has been obtained with eyelet terminals in the prior art, and which therefore do not require soldering.

A further object of this invention is to provide an electrical terminal of small maximum radius which utilizes relatively greater percentage of the sheet metal stock from which it is made.

A third object is to provide electrical terminals which satisfy the preceding objects and which can be made as an integral strip and which can be left in such strip until they are applied to the ends of wires, whereupon they may be easily severed from the strip.

Yet another object of this invention is to provide terminals in strip form, as described above, which are adapted to be used in automatic applying and severing machines.

Other objects will be apparent from the fllowing description and claims.

These various objects are met by my novel method of making a termina1 of the eyelet type from a rectangular sheet metal blank in which a terminated wire is enclosed between an annular base and ears folded from both the inner and outer peripheries of the annulus.

In this specification and the accompanying drawings are shown and described a preferred embodiment of the invention and various modifications thereof. It is to be understood that these are not intended to be exhaustive nor limiting of the invention, but on the contrary are given principally for purposes of illustration in order that others skilled in the art may fully understand the invention and 1the principles thereof and the manner of applying it in practical use so that they may modify and adapt it in various forms, each as may be best suited to the conditions of a particular use.

In the accompanying drawings:

Figure l is a perspective view of a terminal constructed according to this invention and crimped on the end of a wire;

Figure 2 is a perspective view of a terminal shown in Figure 1 prior to its being crimped on the end of a wire, with other terminals of a strip or continuous series of them shown in phantom lines;

Figure 3 is a top plan view of a strip of sheet metal showing various stages in the formation of terminals, of the type shown in Figures 1 and 2, according to this invention;

Figure l is a perspective view of a second embodiment of this invention;

Figure 5 is a top plan view similar to Figure 3 but of a third embodiment of this invention; and

Figure 6 is a perspective view of the embodiment constructed according to Figure 5.

Referring to Figure 1, the terminal structure 2 shown has outer ears 4 compressively turned inward and crimped on an electrical conductor or wire 6 looped into an annular channel I, while inner ears 8 are similarly turned outward over the wire 6 and crimped thereon. Note that, in the embodiments shown in Figures 1 through 4, the inner ears 8 are peripherally alternated with respect to the outer ears 4 and thus the inner and outer ears neatly intermesh with one another and almost totally enclose the wire 6, as is shown in Figure 1. This removes one of the serious objections to eyelets in the prior art, namely the escape of strands or whiskers which can make accidental contact with other parts.

Figure 2 shows a terminal of the type shown in Figure l, but before crimping and prior to a wire being inserted therein. As shown in Figure 3, this termina1 may be formed from rectangular sheet metal blanks by a series of stamping operations. Figure 3 shows the blanks. 20 themselves being formed from a strip of sheet 3 metal l2, which in effect is an integrally connected series of such blanks.

In the operation designated generally as in Figure 3, small pieces are stamped out of the metal strip I2, leaving triangular holes [4. In the next operation IS the strip is cut laterally beyond the holes l4, producing the end edges 18 of rectangular blanks 20 and, with the cutting means presently employed, a slight fold 24 is formed in one end margin of the blank 20.

The purpose of the triangular holes I4 is to so shape the corner portions I3 that they will leave an opening between them, when folded to form ears 4, sufficient to permit the wire 6 to enter said opening without a tendency to be cut by the edges of the terminal when crimped. This is best understood from Figure l. The triangular openings l4 can be extended out to the side edge l5 of the metal strip 12, thus avoiding the need for the separate cutting step described above as part of the operation designated l6. Also, in order to produce a straight end edge l8 at one end of the metal blanks 20, the triangular openings [4 may have one side perpendicular to the side edge [5 of the strip l2. The operation It also includes the step wherein crossed cuts or weakened lines 22 are stamped in the bottom of the blank 20 approximately on the diagonals of the blank. As shown, the lines 22 are not cut through, but leave the blank strong enough to withstand a shallow drawing operation 26, wherein the area of the crossed cuts 22 is stamped into the shape of an inverted shallow cup 28.

This cupped area 28 is not essential to utilization of this invention in its more basic aspects, but is advantageous with the relative dimensions shown for obtaining more complete enclosure of a wire 6 (referring to Figure 1) by the two sets of ears 4 and 8. As will be seen, this step of forming a shallow cup 28 (Figure 3) in the area of the cuts 22 produces longer inner ears 8 than if the sheet metal blank 20 were left flat.

The final operation, shown generally at 30, consists of folding up the four corner portions l3 of the blank 20 to form the outer ears 4, and severing the bottom of the cup 28 at the cuts 22 and opening, like petals of a flower, the four inner ear portions 8.

It will be noted that, in Figures 2 and 3, the side edges of the blank are folded up with the outer ears 4, a construction which not only provides a better annular channel I for receiving a wire 6, but also strengthens the structure 2, particularly in respect to the outer ears 4. The folds 29 which join the ears 4 and 8 to the annular channel I are shown as smoothly curved in two senses, that is, curved across the fold as well as along the fold, creating the channel I of rounded cross section and of generally round shape. Such compoundly-curved folds help to minimize the size of the terminal by giving it, when crimped on a Wire, a generally round shape with a rounded aperture 9 (Figure 1) adapted to closely fit a round screw, bolt, binding post, or other male terminal member. Further, the annular channel 1 of rounded cross-section is adapted to closely fit a wire received therein, as well as being of greater strength than a fiat base. These curves, however, are not essential; for some uses, the terminal may have a fiat bottom with the ears 4 and 8 rather sharply folded up from this flat bottom.

For some purposes, terminals of small dimension which securely grip the insulation on the wire connected thereto are desired. Figure 4 shows an embodiment of this invention which incorporates an insulation-support ferrule-forming portion 34 with the terminal structure 2 as described above. In use, a wire loop is inserted in the annular channel 1, the two sets of cars 4 and 8 compressed over it, and the ferrule-forming portion 34 compressed on the wire insulation in such a fashion as to grip it securely against being pulled back from the terminal assembly.

After inserting a wire wrapped in a loop to fit the annular channel 1, the crimping Of a terminal structure 2 as shown in Figure 2 to form a wire terminal as shown in Figure 1 can be done by a pair of annular concave crimping dies, a cylindrical male die which fits into a conical female die being advantageous for this operation. With dies of the latter type, the female member is advantageously used to draw the ears 4 and 8 inward and crimp them on the wire.

In order to utilize this invention on Wire which has not been previously stripped of its insulation, the peripherally alternated ears 4 and 8, or modifications thereof, may be so curled that their ends are driven inward and down against a wire placed in the annular channel I with radii of curvature of rolled inward portions such that these cars pierce the wire insulation and contact the central conductor core of the wire. The means of doing this could be similar to those disclosed and claimed in the Hackbarth Patent 2,302,767, issued November 24, 1942.

Though there are great advantages to be derived from the terminal structure 2 shown in Figures 1 through 4, a second form of construction 2b is shown in Figures 5 and 6 wherein the inner ears 8?) are radially opposed to the outer ears 4, rather than alternated. Figure 5 shows the formation of the structure 2b with this different arrangement of the inner ears 4, with steps similar to those discussed above in reference to Figure 3.

The terminal structure 2b can be attached to a loop in a wire 6 by folding radially opposed pairs of ears 4 and 8b toward each other, enclosing a wire 6, and further so curling the ears toward each other so that their abutting edges are driven down into the strands of a stranded wire until the assembly is sufhciently compacted to provide a secure physical and electrical connection. The cross section of a crimp Of this type provides a broadly curved bottom periphery and a top with two abrupt curves side by side, as is shown in the copending application of James C. Macy, Serial No. 717,842, filed December 23, 1946,

Another way of applying this second form of terminal 2b would be to roll the outer and inner ears 4 and 822 over the wire in such a fashion that the ears of one set are clamped over those of the radially opposed set.

Various forms of terminals constructed according to my invention have advantages which are important though not immediately apparent. One of these is that such terminals have substantially the same metal thickness throughout, and thus, for a given maximum metal thickness, are stronger than the eyelets of the prior art.

Another advantage of my invention is that the strands of a stranded wire are picked up, gathered together, and drawn into the annular channel and then tightly enclosed by the inner and outer ears during a crimping operation with a comically-walled, concave, annular female crimping die as discussed above.

I claim:

1. An electrical connector which includes an annular base, four ear portions extending upward from each of the inner and the outer peripheries of said annular base, the said ear portions extending from the outer periphery being generally triangularly shaped and defined at their tips by substantially right angles.

2. An electrical connector comprised of an an nular base, four ear portions extending upfrom each of the inner and outer peripheries of said annular base, said ear portions being generally triangularly shaped and defined at their tips by substantial-1y right angles, said connector structure being characterized by the fact that it is formed of a metal sheet of generally rectangular shape.

3. An electrical connector as defined in claim 2 in which the altitude of the triangle of said ear portions from said tips to the periphery of References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 950,524 Whytock, Jr Mar. 1, 1910 1,044,283 Stanger i Nov. 12, 1912 FOREIGN PATENTS Number Country Date 96,422 Austria Mar. 26, 1924

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