US3055412A - Die assembly for crimping a shielded cable - Google Patents

Description

p 25, 1962 D. DIBNER 3,055,412

DIE ASSEMBLY FOR CRIMPING A SHIELDED CABLE Filed July 22, 1954 INVENTOR. .DAVID DIBNER HIS ATTORNEY United States Patent Filed July 22, 1954, Ser. No. 444,991 1 Claim. (Cl. 153-1) My invention relates to a novel crimp for securing connectors or ferrules to a coaxial cable. Ordinarily, these connectors are crimped with a die having interlocking teeth or leaves operating in corresponding grooves which produce circumferential and staggered indentations on the outer surface of the connector. If one end, or possibly both ends of the ferrule are located over one of the grooves in the die, the ferrule will bend into this groove under the crimping force and result in a flare or bell being formed in the connector edge. This condition is objectionable because wiring assemblies or harnesses employing large numbers of such ferrules are frequently packed tightly together, increasing the possibility of the sharp, flared edge of the installed ferrule cutting into the adjacent cable and producing a short circuit. The trend towards closely packing cables is a result of greater miniaturization in electronic design. This problem is almost solely confined to the smaller shielded or coaxial cables where the cables are unable to resist the cutting of the flared ferrules.

At present, two types of die crimps are commercially available for such connectors. One employs symmetrical grooves which close down on the ends of the connectors. Pockets are laterally provided into which the excess material fiows to form a flash, causing a cross-sectional configuration of the cable that is almost oval, with two flash elements extending therebeyond. I have found this type of crimp to be objectionable, for the connector should not provide an extension or edge which could do damage to an adjacent cable.

The other present type avoids the flash by providing a hexagonal crimp. I find that this type of crimp is objectionable because the six corners of the connector provide sharp points which also can damage adjacent wires in a harness assembly.

Accordingly, the principal object of my invention is to produce a crimp for a coaxial cable connector which will reduce or eliminate the present type of belling, flaring or ovalizing, which exposes sharp edges, or points which damage adjacent cables.

These and other objects of my invention are accomplished and my new results obtained as will be apparent from the device described in the following specification, particularly pointed out in the claim, and illustrated in the accompanying drawing, in which:

FIG. 1 is a side elevation of a pair of crimping dies in open position for incorporating my invention.

FIG. 2 is a longitudinal sectional view of the same.

FIG. 3 is a side elevation of the dies of FIG. 1 in closed position.

FIG. 4 is a longitudinal sectional View of the same.

FIG. 5 is a perspective view of the upper die of FIG. 1.

FIG. 6 is a side elevation of the crimp forming my invention on a coaxial cable connector.

In the drawing FIG. 1, there is illustrated a pair of die bases 10 and 12, each provided with plate-like teeth or leaves, namely 14 and 16, respectively, which when the dies are closed, mate or interlock with each other into slots 15 and 17, respectively, providing semi-cylindrical crimping surfaces 18 and 19 outlining a hole 20 which is less than the original diameter of the connector being crimped. As shown in FIGS. 5 and 6, the crimp 21 caused by leaves 14, and crimp 22 caused by leaves 16, compress the connector 23 around the shielded wires 24 of the coaxial cable 25.

Beyond the crimping teeth 14 and 16, there are provided corresponding grooves 26 and 28, respectively, concentric with and larger than hole 20 for swaging the end surfaces 27 of the connector into cylindrical position during crimping. The dies are limited in their closing movement by flat surfaces 30 and 32, respectively, provided on opposite spaces thereof.

When the annealed copper ferrule 23 is placed over the shielding wire 25 of the coaxial cable 26 and then between the dies 10 and 12 in their open position, the ferrule is located by the operator placing it approximately over the surfaces 18. When the dies 10 and 12 are pressed together by the accommodating installation tool, not shown, the ferrule is first squeezed or crimped by the edges of the interlocking surfaces 18 and 19. When the ferrule is under compression from the teeth, it tends to buckle as a result of the deformation being applied to it. This normally results in the flaring, flashing or belling which has previously been considered objectionable. However, in my new device, the ends of the ferrule are contained and controlled by the swaging grooves 26 and 28 which reduce the diameter of the ferrule enough to close the ferrule around the cable, but in such a way as to provide a smooth, cylindrical appearance at the ends of the ferrule and to avoid any belling or flashing as was previously experienced. Note that in my design, not only are flash pockets avoided in the swaging grooves which would allow room into which the ferrule would expand and therefore result in flash projection, but the swaging grooves are provided with sharp edges which maintain the ferrule in a cylindrical form without allowing it to ovalize or flash. This design maintains the features and advantages of the interlocking teeth type of ferrule crimping die and also achieves a method of reducing the diameter of a cylindrical ferrule by swaging without deforming the ends of the ferrule in such a way as to be damaging to conductors placed adjacent to it.

I have thus described my invention, but I desire it understood that it is not confined to the particular forms or uses shown and described, the same being merely illustrative, and that the invention may be carried out in other ways without departing from the spirit of my invention, and, therefore, I claim broadly the right to employ all equivalent instrumentalities coming within the scope of the appended claim, and by means of which objects of my invention are attained and new results accomplished, as it is obvious that the particular embodiments herein shown and described are only some of the many that can be employed to attain these objects and accomplish these results.

I claim:

A pair of crimping dies for crimping a connector to a shielded cable, each die comprising a plurality of extending interspaced slots and leaves, each of said slots accommodating a leaf from the mating die, said leaves provided with semi-cylindrical crimping surfaces, said dies provided with semi-cylindrical grooves on a side of the dies, for compressing the uncrimped ends of the connector body in a perfectly cylindrical shape, concentric with and slightly larger than the crirnped surfaces, said die parts compressing a cylindrical connector to a coaxial cable into a cylindrical shape free of flaring, belling and flashing.

References Cited in the file of this patent UNITED STATES PATENTS 4 Richardson July 5, 1910 Carlson Sept. 26, 1944 Lepkowski Dec. 11, 1945 Dupre Dec. 28, 1948 Bergan Aug. 30, 1949 Macy May 26, 1953 Pierce Oct. 26, 1954 Wells Mar. 15, 1955 FOREIGN PATENTS Germany Apr. 24, 1925

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