One-piece crimp-type connector and method for terminating a coaxial cable

A set of three annular ribs (44,46,48) disposed annularly around a crimp sleeve (28) are crimped radially inward about a coaxial cable (10) having a forward end portion (20) of its cable braid (16) exposed and folded backwardly, the ribs when crimped inwardly providing cable retention, electrical circuit path between the sleeve and braid, and in a moisture seal adjacent the rearward end face (38) of the sleeve.

This invention relates to a connector for terminating a coaxial cable and 
more particularly to a one-piece crimp-type sleeve for simultaneously 
clamping and moisture sealing a terminated cable. 
Many electrical connectors for terminating coaxial cables of the type 
including an insulated inner conductor surrounded by a conductive braid 
shield and insulated jacket include a conductive cylindrical ferrule with 
the insulated conductor passing through the ferrule and the brain 
circumposing and engaging the ferrule. A crimp ring is then crimped 
radially inward about the jacket to secure the cable to the ferrule. It 
has been found that with this crimp design that the crimp joint could be 
poor and not reliable, the termination was not weather-proofed at the 
termination end of the ferrule, and additional parts were required for the 
assembly. This situation was found to be true whether the cross-section of 
the crimp ring was cylindrical or hexagonal. 
It is a purpose of this invention to provide a termination for a coaxial 
cable of the type described which eliminates loose crimp joints and 
weather proofs the cable termination. 
In accordance with these objects, this invention provides a connector 
member which includes a cylindrical sleeve having a stepped bore extending 
therethrough with a rearward internal diameter of the bore being larger 
than that of the forward end portion of the cable so as to define a cavity 
to receive the cable to be terminated. A set of three annular ribs extend 
radially outward from the outer periphery of the sleeve, each being 
adapted to be crimped radially inward about its respective cable portion 
by an amount generally measured by the outward radial extension of each 
rib. The first rib is adjacent to the rearward end face of the sleeve 
leading into the bore and the crimp provides moisture sealing protection 
and a gripping retention about the outer insulative jacket. The second rib 
circumposes a backward folded portion of the braid and its crimp completes 
a conductive path between the sleeve and the cable and provides a gripping 
retention. The third rib is adjacent the interior end wall of the sleeve 
and, like the second rib, provides another conductive path and gripping 
retention about the cable. 
The cable forward end portion is prepared by exposing and folding 
rearwardly a portion of the braid conductor so as to surround part of the 
insulative outer jacket. The prepared end portion is inserted into the 
sleeve cavity so that the braid fold surface abuts against an interior end 
wall of the sleeve. The edge of the folded back braid is disposed between 
the first and the second ribs. 
As a result, the one-piece crimp sleeve allows a user to utilize tools 
readily available and having a low cost, eliminates a need for additional 
pieces, and provides a moisture sealed entry around the cable adjacent to 
the cavity entry without additional sealing devices (e.g., O-rings, 
gaskets, etc.). As a result, the connector assembly is water-proofed, 
provided with excellent cable retention, and has high reliability crimp 
connection.

Referring now to the drawing, FIG. 1 shows a coaxial-type cable 10 of the 
type comprising a center conductor 12 which is sucessively circumposed by 
a dielectric layer 14, an outer conductor 16 of braid (i.e., the shield), 
and an outer insulating jacket 18, the center and outer conductors each 
having a forward end portion exposed for termination in a connector 
member. 
FIG. 2 shows the exposed forward end portion 20 of the braid conductor 
having been folded rearwardly back onto the cable by an amount sufficient 
to surround part of the insulating jacket 18 and expose part of the 
dielectric layer 14. An abutment face 22 is formed at that point (i.e., 
the bight) where the braid is folded. 
FIG. 3 shows a connector member 24 comprising a cylindrical sleeve 28, a 
coupling ring 26 mounted for rotation about the sleeve, and a forward end 
portion of the prepared cable 10, positioned in the sleeve, the cable 
being partially cut-away and in section to show detail of the sleeve. The 
coupling ring is internally threaded for coupling with a mating connector 
element (not shown). 
The sleeve 28 includes an enlarged forward section 30 which fits within the 
coupling ring, a rearward section 32 for terminating the cable, and an 
interior bore 34 which extends from a forward end face 36 to a rearward 
end face 38 thereof. The bore 34 is stepped and expands from a first 
diameter in the forward section 30 to a larger second diameter in the 
rearward section 32 an amount sufficient to define a cavity 40 sized to 
receive the forward end portion of the cable, the transition step in the 
bore defining an interior end wall 42 for the abutment 22 face of the 
braid to abut and define an inward limit for positioning the cable in the 
cavity. The cavity 40 is defined by a cylindrical wall 41 the diameter of 
which is slightly greater than that part of the cable where the braid is 
folded back whereby to receive the cable in a snug clearance fit. 
Disposed at selected axial positions and extending annularly around the 
outer periphery 44 of the sleeve are three ribs 46, 48 and 50, the first 
rib 46 being disposed adjacent to the rearward end face 38, the second rib 
48 being disposed centrally of the rearward section 32, and the third rib 
50 being disposed proximate to the interior end wall 42 of the bore 34. As 
shown, the forward end portion 20 of the braid is folded back axially by 
an amount sufficient so that the braid has its edge 21 terminate between 
the location of the first and the second ribs. That is, the second (i.e., 
center) rib 48 is in circumposing relation about the rearward terminus of 
the backwardly folded cable braid. 
Shown in dotted lines is a tool 52 comprising three inward jaw members 54, 
each jaw being registered with one respective rib. As a result of each jaw 
member being driven in the direction of the arrow "A", each rib is driven 
radially inward whereby the sleeve is locally compressed into engagement 
with the outer surface of the cable. 
The ribs 46, 48 and 50 each extend radially outward from the outer 
periphery 44 of the sleeve by an amount which defines the inward 
compression. In particular, as result of the inward compression (or 
crimping) of the ribs, the surface defining the inner wall 41 of the 
cavity 40 and circumposed by the respective ribs deforms radially inward 
about the cable. The outer periphery of each rib, once the sleeve 28 is 
crimped, is generally coaxial with the outer periphery 44 of the 
undeformed sleeve between the ribs. 
FIG. 4 shows a completed crimping. The first rib 46 is engaged with the 
outer insulator jacket, the second (i.e., center ) rib 48 is pressing down 
about the cable braid, and the third rib 50 is pressing down about the 
cable braid adjacent the end wall. The sleeve 28, so crimped, provides a 
gripping mechanical retention about the cable at three locations, two 
electrical circuit paths which will shield the center conductor, and a 
moisture seal. The first rib 46 grips the cable and moisture seals the 
area around the entrance to the cavity. The second and third rib, in 
addition to gripping the cable, also engage the braid conductor to 
complete a circuit path between the braid and sleeve. The braid end face 
22, by abutting the end wall 42 of the cavity, also enhances the 
conductive path between the braid and sleeve. 
FIG. 5 shows the sleeve 28 crimped about the cable end portion and enlarges 
detail of the deformed sleeve and the outer periphery of the first rib 46 
relative to the outer periphery of the undeformed sleeve (to the right of 
the rib 46), this being typical for each of the three ribs.