Terminating a shield of a malleable coaxial cable

A method of terminating a malleable external shield (16) of a malleable coaxial cable (2) is carried out by inserting an end of the cable (2) into a tubular connector body (5) through one end (41) thereof and driving a shield gripping tubular metal member (8) surrounding the cable (2) into the connector body (5) from the one end (41) thereof so that the shield gripping member (8) tightly grips the cable shield (16), an external peripheral end flange (38) on the shield gripping member (8) being proximate to the one end (41) of the connector body (5). In order to afford strain relief for the electrical connection between the shield gripping member (8) and the cable shield (16), a solder ring (48) surrounding the cable (2) is held on the flange (38) and an induction heating ring (50) is employed to melt the solder ring (48) to provide a solder fillet (52) rigidly connecting the flange (38) to the cable shield (16).

FIELD OF THE INVENTION 
This invention relates to a method of terminating a malleable external 
shield of a malleable coaxial cable by means of a tubular connector body 
and a shield gripping tubular metal member having an external peripheral 
flange surrounding one end thereof. The invention also relates to an 
electrical connector body terminating such a shield. 
BACKGROUND OF THE INVENTION 
There is disclosed in U.S. Pat. No. 4,452,503, a method of terminating a 
solid metal shield of a semi-rigid coaxial cable which method comprises 
the steps of; inserting an end of the cable into a tubular connector body 
through one end thereof; driving a shield gripping tubular metal member in 
the form of a shield gripping ring, in surrounding relationship with the 
cable, into the connector body from said one end thereof, into force 
fitting relationship with the connector body, tightly to grip the cable 
shield, and thereby positioning a flange on the trailing end of the shield 
gripping ring proximate to said one end of the connector body and 
externally thereof. The shield gripping ring has projecting therefrom 
spline fingers which are forced into the shield of the cable as the shield 
gripping ring is driven into the connector body, so that effective 
electrical connection is made between the ring and the shield. Since the 
solid, relatively rigid, metal shield of such a cable tends to buckle when 
it is bent, the cable is unsuitable for use in a crowded environment, 
where it needs to be routed amongst other cables which have been 
terminated and are grouped together at an input-output panel, for example. 
The rigid cable is bent to a desired orientation before assembling the 
cable to a connector. This avoids having to waste a connector if the cable 
is damaged by improper bending. A disadvantage is that the connector must 
be spaced a short distance from a bend in the cable, because the bend is a 
barrier to an assembly tool used to tighten the connector on the cable. A 
connector might be designed with loose component parts which will required 
a fixture to hold the parts stationary while solder is applied to join the 
parts to the cable. The bend in the cable is a barrier to the fixture. It 
would be desirable to have a cable that can be bent closely to an applied 
connector without risk of damage. 
There is described in a new product bulletin referenced NP42-1, by Belden 
Wire and Cable, Richmond, Ind., (Copyright 1987 Cooper Industries 
Incorporated) a malleable coaxial cable called "conformable" coaxial 
cable, having a malleable external shield comprising a metal wire braid 
filled with a malleable metal, for example tin, by dipping the braid in 
the metal when in a molten state. Such cable, whilst retaining the 
electrical performance of the solid metal shielded cable mentioned above, 
has the advantage that it can readily be bent without buckling. When 
terminated, however, by the method described in U.S. Pat. No. 4,452,503, 
the electrical connection between the shield and the gripping of the cable 
shield. 
Methods similar to those described in U.S. Pat. No. 4,452,503, are also 
described in U.S. Pat. Nos. 4,408,821, and 4,540,231. There is described 
in U.S. Pat. No. 4,712,296, method of using an electrical induction 
heating ring in the form of conductive metal plate, to fuse together parts 
of a coaxial electrical connector. 
SUMMARY OF THE INVENTION 
The present invention is intended to provide a method of terminating a 
malleable external shield of a malleable coaxial cable, whereby the cable 
can be flexed without impairing the integrity of the electrical connection 
between the shield gripping tubular metal member and the cable shield. 
According to the method of the invention, after the shield gripping metal 
member has been driven into the connector body from said one end thereof, 
a solder ring is held against the flange on the opposite side thereof to 
the connector body and in surrounding relationship with the cable, and the 
solder ring and the flange, as well as the cable in the vicinity of the 
flange are heated, thereby melting the soldering ring to produce a solder 
fillet rigidly connecting the flange to the shield of the cable, so as to 
provide strain relief for said electrical connection, whereby the cable 
may be flexed without weakening that connection. 
Conveniently, the soldering ring is held against the flange by force of 
gravity, this being done by positioning the connector body so that it 
extends vertically with the flange uppermost, following the step of 
driving the shield gripping member into the connector body; and then 
placing the soldering ring on the flange, for the heating step. 
The heating step may be carried out by holding the flange and the soldering 
within an electrical induction heating ring and energizing the heating 
ring in order to carry out the heating step. By use of the induction 
heating ring, the heat is focused upon the areas to be heated so that 
undue expansion of the dielectric material of the malleable cable is 
thereby avoided. 
The flange, which is preferably spaced from said one end of the connector 
body, is preferably tin plated for solder wetting, the solder ring being 
of a commercially available kind which is self fluxing. The shield 
gripping member is preferably of substantially smaller mass than the 
connector body and is made of an inherently temperature responsive 
material, for example, brass, the connector body being made of a less 
temperature responsive material, for example, stainless steel and being of 
substantially greater mass than the shield gripping member. Under such 
conditions, the flange will quickly rise in temperature when the heating 
ring is energized, undue withdrawal of heat by the connector body being 
avoided. 
According to another aspect of the invention a coaxial electrical connector 
comprises in combination, a malleable coaxial cable having a malleable 
external shield; a tubular connector body; and a shield gripping tubular 
metal member having an external peripheral flange surrounding one end 
thereof. The cable extends through the connector body and the shield 
gripping member, which is interposed between the cable and the connector 
body in force fitting relationship therewith with the flange proximate to 
one end of the connector body and being located externally thereof. The 
connector further comprises a solder fillet extending about the cable and 
rigidly connecting the flange to the cable on the opposite side of the 
flange to the connector body. 
The flange is preferably spaced from the one end of the connector body to 
avoid the latter bleeding heat from the flange when the solder fillet is 
being formed.

DETAILED DESCRIPTION OF THE INVENTION 
An electrical connector for terminating a malleable coaxial cable 2 
comprises an elongate coupling nut 4, a tubular shell connector body 5, an 
elastomeric gasket ring 6, a shield gripping tubular metal member in the 
form of a shield gripping ring 8 and a nut captivating C-clip 10, as shown 
in FIGS. 1 to 4. The cable 2 comprises a center conductor 12, surrounded 
by a dielectric layer 14, which is in turn surrounded by malleable, 
external shield 16 comprising a metal braid filled with a malleable metal, 
for example tin, by dipping it into that metal when in a molten state. 
Such a cable is described in the Belden New Product Bulletin mentioned 
above which is incorporated herein by reference. The dielectric layer 14 
and the shield 16 were stripped back to expose the end portion of the 
center conductor 12 to which portion was inserted into a gripping socket 
end of an electrical pin terminal 18 which has been earlier force fitted 
into a through bore in a dielectric plug 20 secured in the forward end 
part of the connector body 5. The pin terminal 18 projects forwardly from 
the plug 20 into the nut 4. The body 5 has a through bore 22, 
accommodating an end portion of the cable 2, the terminal 18 and the plug 
20. The rearward portion of the wall of the bore 22 is formed with a ring 
of axial grooves 24 extending about its internal periphery. The rear end 
portion of the body 5 is formed with a pair of opposed external lands 25 
as shown in FIG. 3. Towards its forward end, the connector body 5 has an 
external peripheral nut captivating flange 26 against the forward face of 
which the gasket ring 6 rests. Rearwardly of the flange 26, the connector 
body 2 has an external peripheral groove 28 for receiving the C-clip 10. 
The nut 4 has an inwardly projecting annular rear lip 30 and forwardly 
thereof an internal screw thread 32 for meshing with an external screw 
thread of a mating socket coaxial connector (not shown). 
The shield gripping ring 8 has a rigid annular body portion 34, a ring of 
spline fingers 36 projecting forwardly from the periphery of the body 
portion 34 and an external peripheral flange 38 at the rear end of the 
portion 34. The internal wall of the portion 34 is formed with a ring of 
axially extending grooves 40. 
In order to terminate the connector to the cable 2, the stripped end of the 
cable 14 is inserted into the bore 22 through the rear end 41 of the 
connector body 5, inserting conductor end 12 into pin 18. The shield 
gripping ring 8 is pre-assembled to body 5 prior to cable insertion. The 
shield gripping ring 8 is then partially inserted, in surrounding 
relationship with the cable 2, into the body 5 from its rear end 41 with 
the spline fingers 36 leading. As shown in FIG. 5, assembly tool clamping 
members 42 and 44 are then moved towards one another along a common axis 
so as to be applied to the forward end 45 of the connector body 5 and to 
the rear face 47 of the flange 38, respectively, thereby to drive the 
shield gripping ring 8 home into the bore 22 of the body 5 into force 
fitting relationship with the body 5, tightly to grip the shield 16 of the 
cable 2 and thereby to position the flange 38 proximate to said rear end 
41 of the body 5, and externally thereof. As the spline fingers 36 of the 
gripping ring 8 are forced into the bore 22, they are deflected radially 
inwardly by an internal contour 46 thereof so that the fingers 36 are 
forced into the malleable cable shield 16, ploughing progressively deeper 
furrows therein as they advance. The interaction between the surface of 
the rigid body portion 34 of the ring 8, and the longitudinal grooves 24 
the connector body 5, and the interaction between the grooves 40 in the 
portion 34 and the cable sheath 16 bring about an interlocking 
relationship between the connector body 5 and the cable 2. Externally 
originating torque generated on the cable 2 is thereby resisted. This 
technique is described in U.S. Pat. No. 4,408,421 which is incorporated 
herein by reference. The tool members 42 and 44 are now withdrawn and a 
commercially available solder ring 48, which is self fluxing, is advanced 
along the cable 2, in surrounding relationship therewith, towards the 
flange 38 as indicated by the arrows in FIG. 6. The structure as so far 
assembled, is then raised to a vertical position as shown in FIG. 7 with 
the flange 38 uppermost, so that the solder ring 48 is held against the 
face 47 of the flange 38 that is to say the side thereof opposite to the 
connector body 5, proximate to the cable shield 16. The assembled 
structure is manipulated by means of a clamp 49 to hold the flange 38 and 
the solder ring 48 within an electric induction heating ring 50 which may 
be in accordance with U.S. Pat. No. 4,712,296 which is incorporated herein 
by reference. The heating ring 50 which is in the form of a conductive 
metal plate is then energized to melt the solder ring 48 to produce a 
solder fillet 52 which as shown in FIG. 1 rigidly connects the rear face 
47 of the flange 38 to the malleable cable shield 16. When the heating 
ring 50 is energized, the temperature of the flange 38 rises rapidly 
because the mass of the ring 8 is small relative to that of the connector 
body 5, the solder joint between the flange 48 and the shield 16 is 
improved if the ring 8, and in particular its flange 38 are tin plated for 
the promotion of solder wetting. In order to avoid heat being bled to an 
undue extent from the flange 38 by the connector body 5, the ring 8 is 
preferably made from an inherently temperature responsive material, for 
example, brass, the body 5 being made of less temperature responsive 
material, for example, stainless steel, and the flange 38 being spaced 
slightly from the rear end 41 of the body 5 as shown. By virtue of the 
provision of the solder fillet 52 flexure of the cable 2 will not effect 
the integrity of the electrical connection between the cable shield 16 and 
the ring 8, although the shield 16 was scored by the spline fingers 36 as 
the ring 8 was driven into the body 5 by the members 42 and 44. 
The assembly having been removed from the heating ring 50 and released from 
the clamp 49, the nut 4 is moved along the cable 2 in surrounding 
relationship therewith, over the flange 38 and along the connector body 5 
until annular lip 30 of the nut 4 abuts the flange 26 of the body 5, the 
c-clip 10 resiliently engaged in the external peripheral groove 28 of the 
body 5 whereby the nut 40 is captivated between the clip 10 and the flange 
26, but is rotatable about the axis of the body 5. The thread 32 of the 
nut 4 may then be meshed with the external screw thread of said mating 
connector, the body 5 being held against rotation by means of a tool (not 
shown) applied to the lands 25. 
What has been described is a preassembled connector in which the component 
parts hold themselves stationary without a fixture until final assembly 
onto a cable. The connector is assembled with solder to a cable 
construction that is malleable and thereby unsuitable for a pressure crimp 
connection. The connector is assembled further with a crimp connection to 
eliminate the drawbacks associated with loose parts requiring a fixture to 
hold the loose parts stationary during solder assembly to the cable.