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Патент USA US3048660

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Aug. 7, 1962
Filed Oct. 17, 1958
United States Patent O??ce
Patented Aug. 7, 1962,
John W. Allen, Donald P. Lerch, and George W. Ziegler,
Jr., Carlisle, Pa., assignors to AMP Incorporated, Har
risburg, Pa.
Filed Oct. 17, 1958, Ser. No. 767,878
5 Claims. (Cl. 174—90)
The use of electrical connectors having ferrule-forming
portions which are U-shaped in cross-section for forming
electrical connections to electrical conductors is now wide
spread, various methods of folding the arms of the con
nectors about the conductors being used. Such connec
tors have numerous advantages but suffer from the sub
stantial disadvantage that no entirely satisfactory means
of pre-insulating them has heretofore been found. Where
pre-insulation has been required it has been necessary
to use closed barrel type connectors.
Among the objects of this invention are the provision
it is clearly desirable that the outer layer of insulation
must not be ruptured during the crimping operation and
it has been found that rupturing is particularly liable to
occur when the ferrule-forming portion of the connector
is made, as is common, from a substantially rectangular
plane blank, which is bent up into a U-shape in cross
section and presents a substantially rectangular side eleva
tion. The reason for this is apparently the extrusion of
the metal in the crimping operation which forms pro
tuberances at each end of the edges of the arms of the
connector; these protuberances rip and rupture the
By making the connector from a circular
blank we ?nd that we are able to avoid this rupturing and
at the same time achieve more than mere point to point
contact of the curved arms of the connector, because of
the extrusion of metal into the angles between the two
arms. The ferrule-forming portion formed from a circu
lar blank will be U-shaped in cross-section and its side
elevation a segment of a circle.
of a pre-insulated strip of electrical connectors, a blank 20
The invention will now be described in greater detail
for making the connectors, a method of crimping the con
and by way of example with reference to the accompany
nectors and a pre~insulated electrical connection. Other
ing drawings; it should be clearly understood that these
objects will become apparent hereinafter.
A pre-insulated strip of connectors according to this
invention comprises a U-shaped strip of a linear polyester
having one arm of the U longer than the other, the inside
edge of the longer arm and the outside edge of the shorter
arm being chamfered, the strip carrying a coating of a
heat and pressure-sensitive adhesive on its inside surface
and having U -shaped ferrule-forming portions of electrical
connectors sticking to the inside surface at regular inter
vals. The preferred linear polyester is polyethylene
therephthalate and in particular the material sold by E. I.
Dupont de Nemours and Company Inc. under the regis
tered trademark “Mylar.” We have found that the linear
polyesters are the only plastic insulating materials that
drawings are given purely by way of example and not
limitation and that various modi?cations, alterations and
variations can be made to the illustrated embodiments
within the scope of this invention. In the drawings:
FIGURE 1 is a perspective view of a strip of pre
insulated connectors;
FIGURE .2 is a plan view of a blank for making the
connectors shown in FIGURE 1;
FIGURE 3 is a section on the line 3-3 of FIGURE 2;
FIGURE 4 is a perspective view of a connection made
with a connector from the strip of FIGURE 1;
FIGURE 5 is a section on the line 5—5 of FIGURE 2;
FIGURES 6 to 8 are partial sections showing stages
in the crimping of a connection; and
are satisfactory; they combine good mechanical proper
FIGURES 9 and 10 are perspective views of alternative
ties with excellent electrical properties.
In accordance with the invention, a U-shaped ferrule
Referring ?rst to FIGURE 1 a strip 2 of polyethylene
forming portion of an electrical connector stuck to the 40 terephthalate is U-shaped in cross-section. One arm 4 of
inside surface of a U-shaped strip of a linear polyester,
the U is longer than the other arm 6. The inside edge
the arms of the polyester strip being of unequal length,
of the arm 4 is chamfered at 8 and the outside edge of
the remainder of the inside surface having a coating of a
the arm 6 is chamfered at 10. The inside surface of the
heat and pressure-sensitive adhesive is crimped about an
strip 2 has a coating of a pressure sensitive and heat cur
electrical conductor lying within the U. According to
able adhesive. At regular intervals along the length of
this feature the connector assembly is forced by means
the strip 2 connectors 12 are stuck by means of the
of a substantially plane anvil into a semi-cylindrical,
adhesive. The connectors are applied to the strip with
heated, die so that the arms of the connector and strip
are folded about the conductor and compressed together
to give a connection substantially D-shaped in cross-sec
tion and substantially voidless, the shorter arm of the
heat and pressure.
Each connector is made from a cir
cular blank as shown in FIGURES 2 and 3.
The blanks are formed by a progressive die forming
operation from a strip of brass, the ?nal stage being the
strip being gripped between the arms of the connector
stamping of the circular ‘blank from the strip. Each blank
and the longer arm being stuck to the shorter arm by the
14 has ?ve parallel grooves 16 running across a central
heat from the die. Advantageously there is a series of
plateau 17 from which the blank tapers down gradually
connectors supported on a unitary continuous strip of 55 to its edges, which are thinner than the centre.
linear polyester which is fed to present the connectors one
by one to the die and anvil and in which each connector
The blanks are formed up into U-shaped cross-section
with the grooves 16 running at right angles to the axis of
the U, before they are stuck to the strip 2.
assembly is disconnected from the continuous strip by
The arms 4 and 6 of the strip 2 have slits 18‘ at regular
severing the strip while the connector is being applied
60 intervals between the connectors .12 to enable the strip
to the conductor.
An electrical connection between a ferrule of an elec
trical connector and an electrical conductor lying within
the ferrule forms a still further feature of the invention,
to be handled with greater ease and to be Wound up on
curved part of the connection has a longitudinal slit in
which is held one side of a strip of a linear polyester.
The connectors illustrated in FIGURE 1 are used for
splicing two or more conductors together end to end or
reels. The slits 1S_are of such a depth that they leave
a connecting link between the units of the strip which is
narrow enough to permit coiling but wide enough to pre
according to which the connection is substantially D
shaped and substantially voidless in cross-section and the 65 vent accidental breaking of the strip.
for joining two or more conductors together at points
This strip is wrapped around the connector ferrule and
intermediate to their ends or for similar purposes. FIG
overlaps itself to provide a continuous insulating sheath 70 URES
4 and 5 illustrate a splice connection between two
in surrounding relationship to the ferrule, and the other
insulated stranded conductors 20 and 22. The two con
end of it overlapping the strip and sticking to it. Now,
ductors lie side by side in the ferrule 24 formed by fold
ing the arms of the connector 12 and the arms 4 and 6
of the strip about the conductors. The arms 4 and 6
are also curled around the insulation of the conductors
ance with the invention need not necessarily be circular
shown in the drawing although the circular blank shown
presents substantial advantages in the manufacturing
process. It is, however, highly desirable that the longi
20 and 22 and form insulation supports 26.
The operation of the crimping process and the detailed C1 tudinal edges of the connector be chamfered as shown
and that these longitudinal edges be rounded, i.e. the
construction of the connection will be apparent from FIG
URES 5 to 8. In FIGURES 6 to 8 a connector is in
position on an anvil 28 which has a substantially plane
upper surface. The anvil cooperates with a semi-circular
U-shaped connector should offer as a sector of a circle in
side elevation. Thus, a connector in accordance ‘with the
invention can be formed from ‘an oval-shaped, or a rec
tangle whose ends have been rounded into sectors, rather
than a round blank with the curved edges only having a
We claim:
curled into the position shown in FIGURE 7; in this
1. A U-shaped sheet of a linear polyester having one
position by virtue of the chamfered edges 8 and 10 the
longer arm 4 slides over the shorter arm 6. Continued 15 arm of the U longer than the other, at least one of said
arms being chamfered along its longitudinal edge, said
forcing of the connector into the die 30 causes the shorter
sheet carrying a coating of a heat-and-pressure sensitive
arm 6 to be gripped between the arms of the connector
while the longer arm is forced to overlap the shorter
adhesive on its surface within the U, at least one electrical
connector of U-shaped cross section disposed in said sheet
The die 30 is heated, for example by an electrical heat 20 and adhering thereto with its arms parallel to the arms
of said sheet, the side edges of the arms of said connector
ing element, not shown, mounted directly above the die
cavity. The heat of the die activates the adhesive coating
being rounded at their extremities and the edge portions
on the inner side of the arms 6 and ‘4, and sticks the in
of said arms of said connector having a tapered cross sec
sulation to itself, to the conductor where the shorter arm
tion, and said arms of said connector being devoid of
sharp corners.
6 enters the ferrule and to the insulation on the con—
ductors. The resulting connection is substantially D
2. A strip of polyethylene terephthalate U-shaped in
shaped in cross-section and is forged to a substantially
cross-section and having one arm of the U longer than
voidless connection. Preferably, the crimping operation
the other, the inside edges of the longer arm and the out
is effected in two stages. The connector is compressed
side edge of the shorter arm being chamfered, the strip
tightly around the conductors in a ?rst stage and the 30 having a coating of a heat-and—pressure-sensitive adhesive
pressure is then reduced while maintaining the connection
on its inside surface and having electrical connectors
die 36, having parallel lead-in surfaces 32 tangenial to the
curved die surface. As the anvil 28 forces the connector
into the semi-circular die the arms of the insulation are
in the die. This permits complete softening of the ad
hesive and ensures good sticking of the insulating mate
rial ‘without the danger of extruding it from between the
sticklng to the inside surface of the strip, each electrical
connector having a ferrule-forming portion U-shaped in
cross-sectlon to conform with the strip and its side eleva
die and anvil.
cc 01 tion being a segment of a circle.
The grooves 16 running across the connector assist in
_ 3. A ‘blank for making an electrical connector includ
the gripping of the conductors and contribute to the tensile
ing as a ferrule-forming portion a circular disc of metal
strength of the connection.
with its edge thinner than its centre and which tapers
As the connector is applied to the conductors a shear
gradually from a central plateau outwards and has a se
blade removes the connector from the strip by cutting the 4.0 nes of parallel grooves across the central plateau.
link joining it to the next connector in the strip. The
4. A crimped electrical connection between a ferrule
strip is then advanced another unit into position on the
of an electrical connector and an electrical conductor lying
anvil for making the next connection.
within the ferrule, the connection being substantially
In the connector shown in FIGURES 1 to 8 the con
nector is formed solely by the ferrule-forming portion
and the connector is useful only for making splices. The
invention is not, however, limited to this construction of
connector. For example, the connector may have a ring
tongue as shown in FIGURE 9. In the connector illus
trated a ferrule-forming portion 34 is similar in construc an O
tion to the connector 12, the base of the U being extended
to form part of a ring-tongue 36. The strip of linear
polyester again is coated with an adhesive and the con—
nectors stuck to it, but in this case the link joining two
connectors is formed by one arm 38 (in this case the
longer arm). Each connector is removed from the strip
during the crimping operation by severing along the dotted
lines 40.
FIGURE 10 shows a further embodiment in which the
ferrule forming portions 12 are integral with rings 42
attached to each other in side by side relationship by means
of slugs 44. In crimping terminals of this type onto
wires, an automatic feeding means for the strip is advan~
tageously provided to feed the terminal to a position be
neath the crimping press.
While the invention has been herein disclosed with
reference to a U-shaped ferrule adapted to be crimped
onto a stripped wire, it will be apparent that the inven
tion is also applicable to insulated wires, particularly Wires
having one or more strands insulated with thin coverings
of insulation such as varnish. In the latter case, the ser
rations 16 will serve the function of penetrating the varnish
D-shaped and substantially voidless in cross section in
which’ the curved part of the ferrule has a longitudinal
seam in which is held one end of a strip of a linear poly
ester, the strip surrounding the ferrule and stuck to said
ferrule, and ‘the other end of said strip overlapping said
one end and sticking to said one end, said ferrule having
been formed [from a circular blank and the edges of the
curved part of said ferrule tapering towards said seam.
5. A method of making an electrical connection be
tween two electrical conductors which comprises placing
the conductors within a U-shaped electrical connector
stuck to the inside surface of a U-shaped strip of a linear
polyester with a heat-and-pressure-sensitive adhesive, and
remalnder of the inside surface having a coating of the
adhesive, the strip having one arm longer than the other
and the edge of the longer arm of the strip being cham
fered on its inside surface and the edge of the shorter arm
being chamfered on its outside surface, said method com
prrsmg the further steps of applying heat and pressure to
curl the arms of said strip to position the shorter one of
said arms under the longer one of said ‘arms, thereafter
further curling said arms and additionally curling the
sides ‘of said electrical connector towards each other until
the sides of said ‘connector grip the shorter arm of said
strip and the longer arm of said strip is wrapped around
the joint formed by the sides of said connector and over
laps the shorter arm of said strip, and then reducing the
pressure applied to said connector and continuing to apply
heat thereto to effect sealing of the overlapping arms of
to establish electrical contact with the conductor as is
said strip.
known to the art.
It should also be mentioned that a connector in accord 75
(References on following page)
References Cited in the ?le of this patent
Dillon _______________ __ Nov. 15, 1921
Sowter ______________ __ Mar. 15, 1955
Broske ______________ __ Mar. 19, 1957
Hammell _____________ __ July 23, 1957
Fuller _______________ __ July 29, 1958
Sowa _________________ __ Dec. 2, 1958
AMP pamphlet, received in Patent Office March 5,
1954 (page 3 relied on).
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