Electrical connectors – Contact comprising cutter – Insulation cutter
Reexamination Certificate
2002-07-03
2004-05-18
Patel, Tulsidas C. (Department: 2839)
Electrical connectors
Contact comprising cutter
Insulation cutter
Reexamination Certificate
active
06736664
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a piercing terminal penetratingly connected to a flexible flat circuit body, in which the periphery of flat conductor portion is covered with a coating consisting of an insulator, such as a flexible print circuit (FPC) and flexible flat cable (FFC).
The present invention also relates to a machine and method for crimping a piercing terminal, by which the piercing terminal having a claw piece for piercing is crimp-connected to the flexible flat circuit body.
2. Description of the Related Art
An example of the art relating to such a piercing terminal and method for crimping a piercing terminal is described in Japanese Patent Publication No. S57-48833.
As shown in
FIGS. 11 and 12
, a piercing terminal
40
includes a crimp-connection part
43
having an approximately flat basal plate
41
and claw pieces
42
arising from both sides of the basal plate
41
. Each claw piece
42
consists of a wide base
42
a
joining to the basal plate
41
and a narrow free end
42
b
continuing to the base
42
a.
A flat circuit body
46
(see
FIG. 12
) being connected to the crimp-connection part
43
is a flexible circuit body, in which the periphery of a band-shaped conductor portion
47
is covered with a coating
48
consisting of an insulator, and is a thin circuit body called FPC or FFC.
The claw piece
42
adjoining each other in the length direction of the piercing terminal
40
is parted away from each other forming a tapered space therebetween. The base side of the claw piece
42
continues to the basal plate
41
and the joining portion of the claw pieces
42
.
Since the claw piece
42
provided at both sides of the width direction of the basal plate
41
is alternately formed with each other, therefore at the opposite side of each claw piece
42
in the width direction, there is a tapered-shape space facing thereto. The claw piece
42
includes a round-shaped end
42
c
and a sharp side edge
42
d.
At the center of the basal plate
41
, there is provided a protrusively striped contact portion
44
. In the direction crossing the contact portion
44
at right angles, there is formed a groove
45
, which extends up to the inner surface of the claw piece
42
.
As shown in
FIG. 12
, the claw piece
42
pierces through the conductor
47
, thereby the piercing terminal
40
is fixed to the flat circuit body
46
. The free end
42
b
of the claw piece
42
is caulked inwardly along a press surface
49
a
of a crimper
49
and stripes the coating
48
of the flat circuit body
46
away so as to come in contact with the conductor
47
, thereby the electric conduction is attained.
However, the conventional piercing terminal described above has the following problems to be solved.
One problem is that since the piercing terminal
40
has a plurality of claw pieces
42
, when the flat circuit body
46
becomes thick, the claw piece
42
might not be able to pierce through the flat circuit body
46
. To the contrary, if the number of the claw pieces
42
is reduced, the connection between the piercing terminal
40
and the flat circuit body
46
might become insufficient, resulting in that the piercing terminal
40
might come off from the flat circuit body
46
.
Another problem is that when the thickness of the conductor
47
becomes different, a plurality of the piercing terminals
40
having different size must be prepared. That is, when the piercing terminal
40
is crimped between an anvil (not shown in the figure) and crimper
49
, the piercing terminal
40
forms a crimp height depending on the shape of the crimper
49
. If the flat circuit body
46
or conductor
47
is thin, the end of the claw piece
42
does not reach the conductor
47
, the connection between the piercing terminal
40
and the flat circuit body
46
might become insufficient. To the contrary, if the flat circuit body
46
or conductor
47
is thick, the protrusion length of the claw piece
42
becomes short, resulting in that the claw piece
42
might not be caulked in a curled shape.
In such a case described above, a piercing terminal having a suitable size must be selected and therefore, the number of parts increases causing the cost up and the parts control becomes complicated causing the deterioration in workability.
Another problem is that the contact area between the flat circuit body
46
and the claw piece
42
, which depends on the caulked shape of the claw piece
42
, is small. That is, since the radius of curvature of the caulked portion of the claw piece
42
is small, the contact area between the conductor
47
and the claw piece
42
is small, therefore a good electric conduction cannot be attained. That is, when the crimper
49
caulks the claw piece
42
, if a fabrication error takes place, a good electric conduction might not be attained.
FIGS. 13A and 13B
are cross sectional views before and after crimping, respectively, illustrating an example of a conventional method of crimping a piercing terminal.
A piercing terminal
240
and a flat circuit body
246
are sandwiched between a crimper
244
, which is a die for pressing, and an anvil
245
, which is a die as a pedestal, and caulked into each other so as to be crimped.
The anvil
245
is a pedestal, on which the piercing terminal
240
is placed, and there is formed a projection
245
a
having a trapezoid shape in its cross section on the center of the anvil
245
. The projection
245
a
fits to the bottom of a protrusively striped contact portion
241
a
of the piercing terminal
240
.
The crimper
244
is provided with a pair of curved portions
244
a
, each of which is parted away from the other by a protrusion
244
b
having a flat part. The protrusion
244
b
faces the projection
245
a
and is set to be movable relatively to the anvil
245
.
However, the conventional method of crimping a piercing terminal described above has the following problems to be solved.
One problem is that the contact area between the flat circuit body
246
and the claw piece
242
of the piercing terminal
240
, which depends on the caulked shape of the claw piece
242
, is small. That is, the claw piece
242
is caulked inwardly along the curved portion
244
a
of the crimper
244
and since the radius of curvature of the bent portion of the claw piece
242
is small, if the thickness of the conductor
247
of the flat circuit body
246
becomes different, the contact area between the claw piece
242
and the conductor
247
becomes decreased or increased, therefore a good electric conduction might not be attained. Particularly, in case of an electric wire of an electric power system, since the electric wire supplies power from a battery to loads and a large current flows in the wire in comparison with a wire of a signal system, an electric resistance becomes large when the contact area is small, resulting in bad electric conduction.
In such a case, in order to adjust a crimp height of the piercing terminal
240
, a distance between the crimper
244
and anvil
245
must be changed and otherwise the piercing terminal
240
having a different size must be prepared, resulting in that the parts control becomes complicated causing the deterioration in workability.
SUMMARY OF THE INVENTION
It is therefore an objective of the present invention to solve the above problems and to provide a piercing terminal having high reliability for crimping, by which the piercing terminal can be securely pierced through a flat circuit body even if the flat circuit body has a thick conductor and the piercing terminal has a plurality of claw pieces.
It is also an objective of the present invention to provide a highly reliable machine and method for crimping a piercing terminal, by which the piercing terminal can be securely crimp-connected to a flat circuit body having different thickness.
In order to attain the above objective, the present invention is to provide a piercing terminal to be connected to a flat circuit body comprising:
an electrically conductive basal plate; and
a plurality of claw pi
Murayama Toshisada
Ueda Hirohisa
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