Electrical connectors – Contact comprising cutter – Axially penetrating the elongated conductor
Reexamination Certificate
2002-06-27
2004-05-25
Paumen, Gary (Department: 2833)
Electrical connectors
Contact comprising cutter
Axially penetrating the elongated conductor
Reexamination Certificate
active
06739899
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to a method and structure for connecting a terminal with a wire in which a tubular wire connecting portion of a terminal is crimp-connected to a core of a wire in a uniform manner over the whole circumference by using, for example, a rotary swaging machine.
Conventionally, a wire is connected to a terminal by the following connecting method. As shown in
FIGS. 21A and 14B
, for example, a core
37
of a wire
35
is crimped by a pair of crimp pieces
34
which are erected from both sides of a bottom plate
36
of a terminal
33
, and the paired crimp pieces
34
are crimpingly deformed into a substantially eyeglasses-like shape, whereby the core
37
is strongly pressed from both the sides and tip ends
34
a
of the crimp pieces
34
are caused to bite the middle area of the core
37
. As a result, the contact between the core
37
and the crimp pieces
34
is attained. As shown in
FIG. 21B
, inside the crimp pieces
34
, the diameter of the core
37
is reduced, and, in the front and rear end sides of the crimp pieces
34
, the diameter of the core
37
is outward increased, so that the core
37
is crimped by the wedge function.
The connecting method using the pair of crimp pieces
34
is effective for the wire
35
of a small diameter. By contrast, for a wire of a large diameter such as a shielded wire through which a large current can be flown, the method has a problem in that the contact area between the crimp pieces
34
and the core is small and the electric resistance is easily increased.
Therefore, a terminal of a type in which a core is crimped equally in the circumferential direction is used for such a wire of a large diameter. As an example of a connecting method using such a terminal,
FIG. 22
shows a method of connecting a terminal with a wire which is disclosed in Japanese Utility Model Publication No. 43746/1975.
In the connecting method, under a state where a core of a wire is inserted into a tubular wire connecting portion of a terminal, the tubular wire connecting portion is crimped into a hexagonal shape by a pair of upper and lower dies
21
, to cause the core
23
to be closely contacted into the wire connecting portion
22
. As shown in
FIG. 23
, each of the dies
21
has three pressing faces
24
, and a center ridge
25
is formed on each of the pressing faces
24
. As shown in
FIG. 22
, the ridges
25
radially press the centers of the outer faces of the hexagonal wire connecting portion
22
to enhance the contact performance between the core
23
of the wire and the wire connecting portion
22
of the terminal.
However, the conventional connecting method and the connecting structure using the method have a problem in that, as shown in
FIG. 22
, burrs
26
are easily produced between the upper and lower dies
21
and on both sides of the wire connecting portion
22
, and a large manpower is required for removing the burrs
26
. When the wire connecting portion
22
of the terminal is crimped by using the upper and lower dies
21
, as shown in
FIG. 24
, the vertical crimp forces (internal stress) P
1
which are directed to the center of the core
23
largely act, and the crimp forces (internal stress) P
2
on the lateral portions tend to be reduced, thereby causing another problem in that a gap is easily formed on both sides of the wire connecting portion
22
and between the element wires of the core
23
, or between the core
23
and the wire connecting portion
22
. When such a gap is formed, the electric resistance is increased to produce the possibilities that the power transmission efficiency is lowered, and that the connecting portion is overheated.
FIG. 25
shows a mode of crimp-connection of a wire by using a method similar to that of FIG.
22
. The ridges
25
of the dies
21
(
FIG. 23
) radially press a core
23
′ of a wire at six places as indicated by the arrows F. Therefore, the core
23
′ is deformed so as to have a tortoise-like section shape, and stress concentration (the chain lines
29
show the distribution of internal stress) occurs in regions of a wire connecting portion
22
′ of a terminal which are between recesses
27
due to the ridges
25
(FIG.
23
), i.e., in the vicinities of convex portions
28
, and the crimping on the core
23
′ becomes uneven in the circumferential direction. As a result, gaps (gaps between element wires)
30
are easily formed in the core
23
′, gaps
31
are easily formed also between: the core
23
′ and the wire connecting portion
22
′ of the terminal, and the wire connecting portion
22
′ tends to crack because of the stress concentration, thereby producing a problem in that the strength is reduced. When the gaps
30
and
31
are formed, the electric resistance is increased in the same manner as described above to produce the possibilities that the power transmission efficiency is lowered, and that the connecting portion is overheated. Moreover, there is a further possibility that the core
23
′ easily slips from the wire connecting portion
22
′.
SUMMARY OF THE INVENTION
In view of the above-discussed problems, it is an object of the invention to provide a method and structure for connecting a terminal with a wire in which a tubular wire connecting portion of a terminal can be beautifully crimped to a wire with producing internal stress uniformly in the circumferential direction, and without producing burrs, gaps between element wires of a core of the wire, and between the core and the wire connecting portion of the terminal can be eliminated to enhance the reliability of the electrical connection between the terminal and the wire, and the mechanical strength of the connecting portion can be improved.
In order to solve the aforesaid object, the invention is characterized by having the following arrangement.
(1) A method of connecting a terminal with a wire comprising the steps of:
inserting a core of the wire into a tubular wire connecting portion of the terminal; and
crimping the wire connecting portion in a radial direction of the wire so that the wire connecting portion is compressed in the radial direction and uniformly over a whole circumference of the wire.
(2) The method according to (1), wherein the wire connecting portion is compressed by dies in the radial direction over the whole circumference while rotating the dies by using a rotary swaging machine.
(3) The method according to (1), wherein
a protrusion is formed on an outer periphery of the wire connecting portion, and
during circumferential crimping of the wire connecting portion, the protrusion is projected from an inner periphery of the wire connecting portion to bite the core.
(4) A structure for connecting a terminal with a wire wherein a core of the wire is inserted into a tubular wire connecting portion of the terminal, and the wire connecting portion is crimped in a radial direction of the wire so that the wire connecting portion is compressed in the radial direction and uniformly over a whole circumference of the wire and an outer periphery of a compressed part of the wire connecting portion has a true circular section shape.
(5) The structure according to (4), wherein
a protrusion is formed on an outer periphery of the wire connecting portion, and
the protrusion is projected from an inner periphery of the wire connecting portion to bite the core after the wire connecting portion is crimped.
(6) The structure according to (5), wherein the protrusion is an annular ridge or at least one projection.
(7) A terminal comprising:
a wire connecting portion including a wire insertion hole, the wire connecting portion being to be subjected to a circumferential crimping process; and
a contact protrusion, for entering a core of a wire, elongating in, a longitudinal direction of a wire and disposed in the wire insertion hole.
(8) The terminal according to (7), wherein the contact protrusion is positioned at a center of the wire insertion hole.
(9) The terminal according to (7), wherein the contact protrusion has
Asakura Nobuyuki
Kuwayama Yasumichi
Maki Toshihiro
Onuma Masanori
Paumen Gary
Yazaki -Corporation
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