U.S. patent number 3,828,298 [Application Number 05/325,705] was granted by the patent office on 1974-08-06 for electrical terminal for a braided shield on a coaxial cable.
This patent grant is currently assigned to AMP Incorporated. Invention is credited to William Ludlow Schumacher.
United States Patent |
3,828,298 |
Schumacher |
August 6, 1974 |
ELECTRICAL TERMINAL FOR A BRAIDED SHIELD ON A COAXIAL CABLE
Abstract
The present invention discloses an electrical terminal for
grounding the braided shield on a coaxial cable. The terminal has
beveled, inwardly projecting lances on each sidewall of the ferrule
forming portion which separates the strands of and slides behind
the braided shield so as to lace the shield between the sidewalls
and lances to provide mechanical support and electrical
contact.
Inventors: |
Schumacher; William Ludlow
(Camp Hill, PA) |
Assignee: |
AMP Incorporated (Harrisburg,
PA)
|
Family
ID: |
23269062 |
Appl.
No.: |
05/325,705 |
Filed: |
January 22, 1973 |
Current U.S.
Class: |
439/442; 439/394;
174/75C |
Current CPC
Class: |
H01R
9/0512 (20130101) |
Current International
Class: |
H01R
9/05 (20060101); H01r 003/06 () |
Field of
Search: |
;339/95,96,97,223
;174/75C,78 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Zugel; Francis K.
Assistant Examiner: Hafer; Robert A.
Attorney, Agent or Firm: Osborne, Esq.; Allan B.
Claims
What is claimed is:
1. A sheet metal electrical terminal for terminating the braided
shield on a coaxial cable, comprising:
a. a generally U-shaped ferrule having a base portion and a pair of
sidewalls connected to and extending upwardly from opposite sides
of the base portion;
b. a pair of lances extending from each sidewall, said lances
attached at one end to each sidewall with the other end extending
upwardly from the base portion and inwardly toward the opposite
sidewall, each lance being formed into a generally four sided
pyramid, the free end being pointed, said lances adapted to pierce
and slide in behind portions of the braided shield of a coaxial
cable which may be pressed into the ferrule; and
c. a pair of openings on each sidewall in alignment with said
lances so that as the lances slide in behind portions of the
braided shield, such portions may project into the openings.
2. A stamped and formed sheet metal electrical terminal for
grounding the braided shield on a coaxial cable, which
comprises:
a. a U-shaped ferrule-forming portion having a base portion and a
pair of upstanding sidewalls extending from opposite sides of said
base portion, said sidewalls adapted to be crimped into
encompassing engagement with said braided shield, said
ferrule-forming portion further having two pair of adjacent,
upwardly extending lances with each pair on either side of said
base portion and positioned internally of said sidewalls, (with
each lance in each pair beind adjacent to the other), said lances
having a beveled outwardly-facing sides and sharp tips on the free
end thereof, said lances adapted to pierce and slide inbehind said
braided shield so that a portion of said shield becomes laced
between said lances and said sidewalls;
b. connector means integrally attached to one end of said
ferrule-forming portion, said connector means comprising a flat
portion being coplanar with said base portion of said
ferrule-forming portion and an upstanding member integral with said
flat portion and adapted to structurally support said flat portion,
said connector means adapted for being attached to a ground;
c. a U-shaped insulation-support wire barrel having a base portion
and a pair of upstanding sidewalls extending from opposite sides of
said base portion, said sidewalls adapted to be crimped into
encompassing engagement with said coaxial cable; and
d. connecting means for connecting said wire barrel to another end
of said ferrule-forming portion whereby said base portion of said
wire barrel is displaced downwardly from said base portion of said
ferrule-forming portion.
Description
BACKGROUND OF THE INVENTION
In various applications and particularly in some radio frequency
applications it is necessary to terminate the outer conductive
braided shield of a coaxial cable to a ground. In these
applications it is desirable to terminate the braided shield
without interrupting the center conductor and dielectric
surrounding it.
Some of the known prior art provides electrical connectors or
terminals for connecting the braided shield to an electrical lead
which is in turn attached to a ground. For example, U.S. Pat. Nos.
3,194,877 and 3,549,787 disclose terminals of this nature.
U.S. Pat. No. 3,435,126 teaches a metal band having a plurality of
prongs which bit into the braided shield. The metal band is
directly attached to a ground by means of a hose clamp which is
threaded through slots in the ground.
Whereas the above cited patents and others in the art provide means
for adequately grounding the braided shield, they either require a
separate electrical lead, a number of components or detailed
preparation of the cable to be grounded.
Accordingly it is an object of the present invention to provide a
low cost, stamped and formed electrical terminal for grounding the
braided shield on a coaxial cable quickly and simply and which
provides good mechanical and electrical properties.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1a is a perspective view of the terminal constructed in
accordance to the present invention and a prepared coaxial cable to
be terminated;
FIG. 1b is a transverse cross-sectional view of the terminal and
cable of FIG. 1a;
FIG. 2a is a perspective view of the cable partially pressed into
the terminal of FIG. 1a.
FIG. 2b is a transverse cross-sectional view of the terminal and
cable taken along lines 2b--2b of FIG. 2a;
FIG. 3a is a perspective view of the completed termination of the
cable into the terminal of FIG. 1a;
FIG. 3b is a transverse cross-sectional view taken along lines
3b--3b of FIG. 3a; and
FIG. 3c is an axial cross-sectional view taken along lines 3c--3c
of FIG. 3a.
DESCRIPTION OF THE PREFERRED EMBODIMENT
In the accompanying drawings, the number 10 designates generally a
length of a coaxial cable comprising from the center outwardly, a
primary conductor 12, a conductor insulation or dielectric 14, an
outer conductive braided shield 16 and lastly the outer insulation
jacket 18. Braided shield 16 is commonly made of one or more layers
each of which contain many strands of fine wire braided together.
Cable 10 is prepared for termination to a terminal by stripping
away a portion of the outer jacket 18 so as to expose shield 16.
Where center conductor 12 is to be terminated also, a portion of
shield 16 and dielectric 14 is removed.
Referring now specifically to FIGS. 1a and 1b, an electrical
terminal 20 constructed in accordance with the present invention is
shown. The terminal is made from electrically conductive sheet
metal such as phosphor bronze or brass, and is blanked and formed
by conventional metal-stamping and metal-forming techniques.
At the front end of terminal 20, an offset ring tongue 22 on
connector portion 24 provides the means to attach electrical
terminal 20 to a suitable ground or the like (not shown). As is
well known to those skilled in the art, terminal 20 may be made
with other forms of tongues (not shown) other than ring tongue 22.
Connector portion 24 also includes an upstanding member 25
extending from one side thereof to provide structural strength to
ring tongue 22.
Behind connector portion 24 and integral therewith is a generally
U-shaped braided shield ferrule-forming portion 26.
A U-shaped insulation-support wire barrel 28 extends from and is
integrally connected to ferrule-forming portion 26 by offset
portion 27 which displaces wire barrel 28 downwardly relative to
ferrule-forming portion 26 by a distance substantially equal to the
thickness of insulating jacket 18.
Wire barrel 28 includes a base portion 30 and a pair of upstanding
sidewalls 32--32 extending from opposite sides of base portion 30.
The inside surfaces of base portion 30 and sidewalls 32--32 are
generally smooth but may be ridged (not shown) or otherwise
roughened to enhance the retention of cable 10 therein.
The U-shaped braided shield ferrule-forming portion 26 includes the
bight or base portion 34 and a pair of upstanding sidewalls 36--36
extending upwardly from opposite sides of base portion 34. As FIG.
1b indicates, sidewalls 36 are initially formed so that they are
spread outwardly; i.e., away from each other, a few degrees from
the vertical. This spreading provides a larger opening into
ferrule-forming portion 26 for cable 10.
A pair of lances 38--38 are stamped out of each of the two
sidewalls 36 and are integral with base portion 34. Each lance 38
is formed to project inwardly and extend upwardly parallel to
sidewalls 36 and is also swaged to provide a sharp
inwardly-disposed tip 40 and an outwardly-disposed beveled portion
42. The height of lances 38 preferably is equal to about
three-fourths the diameter of cable 10 without jacket 18.
The distance or spread between lances 38 on opposite sidewalls 36
is substantially equal to the diameter of dielectric 14 of cable
10.
Transverse openings 44 which result from the stamping and forming
of lances 38 provide means for visual inspection of the assembled
termination of FIGS. 3a, b, and c.
METHOD OF TERMINATING A COAXIAL CABLE HAVING A BRAIDED SHIELD ONTO
THE PREFERRED EMBODIMENT
A coaxial cable 10, previously prepared in the manner described
above, is aligned over terminal 20 so that the exposed braided
shield 16 is directly over ferrule-forming portion 26. The axial
length of exposed shield 16 substantially equals the axial length
of ferrule-forming portion 26 and insulating jacket 18 terminates
in the immediate vicinity of offset portion 27; i.e. adjacent to
ferrule-forming portion 26. This alignment is illustrated in FIGS.
1a and 1b.
FIGS. 2a and 2b illustrate how lances 38 pierce braided shield 16
as cable 10 is being pressed into terminal 20. As tips 40 move in
under braided shield 16, a portion thereof is being forced down the
outside beveled portion 42. Such portion is hereinafter designated
as the outboard portion 46 of braided shield 16.
Termination of coaxial cable 10 is completed when it has been
pressed down completely into terminal 20 with sidewalls 32 being
crimped around insulating jacket 18 and sidewalls 36 being crimped
around braided shield 16 in the manner shown in FIGS. 3a and 3b. As
the crimping dies used (not shown) are conventional and well known
in the art and do not form part of the instant invention, further
detail thereof is unnecessary.
As seen in FIGS. 3a, 3b and more particularly in FIG. 3c, outboard
portions 46 are laced through and thereby trapped between lances 38
and sidewalls 36.
Lances 38 retain a residual force in an outwardly direction; i.e.
toward transverse openings 44. Thus should sidewalls 36 relax away
from the crimped position seen in FIGS. 3a and 3b, lances 38 will
follow thereby maintaining electrical pressure contact between
terminal 20 and braided shield 16.
Another novel feature in the present invention is that the lances
38 do not penetrate dielectric 14 nor jacket 18 and thus trap this
material in the electrical connection. The termination is thus free
of matter that is subject to creep or flow. The termination may be
subject to stresses such as tension and temperature changes without
destroying the mechanical or electrical termination.
Although the preferred embodiment of the present invention utilizes
four lances 38, it is apparent that one lance 38 will also provide
the same mechanical advantages but not to the degree as achieved
using four or more.
It should be noted that terminal 20 may be used at any point along
coaxial cable 10 and not necessarily adjacent the cable end. The
amount of insulating jacket 18 that needs to be removed is only the
axial length of braided shield ferrule-forming portion 26.
As is apparent to those skilled in the art, wire barrel 28 may be
cut away from terminal 20 and not used.
As is also apparent to those skilled in the art, ring tongue 22 may
have the form of a tab, spring contact, be the outer shell of a
coaxial contact or any other convenient means of making a ground
connection.
The foregoing detailed description has been given for clearness of
understanding only, and no unnecessary limitations should be
understood therefrom, as some modifications will be obvious to
those skilled in the art.
* * * * *