Clamp type contact and method of manufacture thereof

A clamp type contact has a first elongate contact piece which is punched out of a blank member having an upper thin piece and a lower thick piece disposed in a relative downward direction from a position immediately below the end of the upper thin piece so as to have a free end and a base end. A second elongate contact piece is defined by the remaining upper thin piece and has a free end corresponding to the end of the upper thin piece, a base end integrally joined to the base end of the first elongate contact piece, a base portion extending sidewise from the base end and a bent portion allowing the free end to face the free end of the first elongate contact piece. A male contact piece is formed on the lower thick piece of the blank member.

BACKGROUND OF THE INVENTION 
1. Field of the Invention 
The present invention relates to a clamp type contact having a pair of 
elongate contact pieces adapted to clamp a terminal of an electronic 
component or electric connector therebetween and to a method of the 
manufacture of the clamp type contact. 
2. Description of the Related Art 
Generally, clamp type contacts used in a connector for connecting 
electronic appliances together are required to have good spring 
characteristics. A material having a high degree of toughness, such as 
phosphor bronze, is plated with gold and the result is used as a contact 
piece. Recently, there is an increasing demand for the miniaturization of 
contacts and the reduction of an accommodation space for contacts. 
Therefore, efforts have been made to obtain contact pieces having lengths 
effective to exhibit elastic displacement and to improve stock utilization 
as much as possible under the limited conditions by using a blank layout, 
resulting from the aforementioned demands for miniaturization and 
reduction. 
Heretofore, a pair of opposed contact pieces of a clamp type contact have 
been formed either by punching a long blank member out of a sheet and 
bending the long blank member in a U-shaped or by punching two blank 
members connected through a connection portion out of a sheet and bending 
the blank members to rise from the connection portion, such as disclosed 
in Japanese Utility Model Publication No. SHO 52-49978. In either case, it 
is necessary not only to punch a blank member of at least a length 
corresponding to the total length of the contact pieces developed, but 
also to consider the bend allowance for the connection portion of the 
contact pieces in order to obtain sufficient effective lengths of the 
contact pieces. Since the reduction in length of the blank member to be 
punched out of a sheet has its own limit and since the bend allowance 
constitutes excess material, stock utilization cannot be greatly improved. 
Furthermore, since the opposed surfaces of the prior art contact pieces 
have relatively large widths, the recent demand for the miniaturization of 
contacts is not met. 
When a clamp type contact has a pair of contact pieces of the same 
thickness for clamping a terminal therebetween, since the free ends of the 
contact pieces have similar frequency characteristics, there is a fair 
possibility of resonance phenomena occurring through the medium of the 
clamped terminal due to external vibrations, thereby giving rise to 
unstable contact between the terminal and the contact pieces. 
SUMMARY OF THE INVENTION 
The present invention has been proposed in order to eliminate the drawbacks 
of the conventional clamp type contact. 
The main object of the present invention is to provide a clamp type contact 
efficiently manufactured from a blank member punched out of a sheet and 
having a limited length and a limited width, designed to facilitate highly 
enhanced stock utilization, simple in construction and capable of reliably 
clamping a terminal between contact pieces having a sufficient effective 
length necessary for exhibiting elasticity and also capable of suppressing 
resonance phenomena resulting from external vibrations tending to cause an 
unstable connection between the terminal and the contact pieces. 
To attain the object described above, according to the present invention, 
there is provided a clamp type contact comprising a first elongate contact 
piece punched out of a blank member having an upper thin piece and a lower 
thick piece disposed in the downward direction from a position immediately 
below the end of the upper thin piece so as to have a free end and a base 
end; a second elongate contact piece constituted by the remaining upper 
thin piece and having a free end corresponding to the end of the upper 
thin piece, a base end joined integrally to the base end of the first 
elongate contact piece, a base portion extending sideways from and 
inclined relative to the base end thereof and a bent portion allowing the 
free end thereof to face the free end of the first elongate contact piece 
and a male contact piece constituted by the lower thick piece of the blank 
member. 
The above and other objects, characteristic features and advantages of the 
present invention will become more apparent to those skilled in the art as 
the disclosure is made in the following description of preferred 
embodiments of the invention, as illustrated in the accompanying drawings.

DESCRIPTION OF THE PREFERRED EMBODIMENTS 
Now, the present invention will be described in detail with reference to 
the illustrated embodiments. 
FIGS. 1 to 3 illustrate one embodiment of the clamp type contact according 
to the present invention and FIGS. 4A through 4G illustrate a method of 
manufacturing the clamp type contact. As illustrated in FIGS. 5 and 6, 
blank members 1 are punched out of a sheet a which has been subjected to a 
cutting treatment in its lengthwise direction so as to form a thin section 
b on the upper side thereof and a thick section c on the lower side 
thereof. Each of the blank members 1 has an upper thin piece b' exhibiting 
a high degree of elasticity and a thick piece c' exhibiting high rigidity 
and constituting a male contact piece 5, as illustrated in FIG. 4A. The 
upper portion of the thin piece b' of the blank member 1 is subjected to a 
bending treatment with a press to form an arcuate portion 3b as 
illustrated in FIG. 4B. The thin piece b' of the blank member 1 is punched 
at the center from a position immediately below the arcuate portion 3b in 
the downward direction with a joint portion 4 left existing, thereby 
forming a first elongate contact piece 2 and a second elongate contact 
piece 3 as illustrated in FIG. 4C. The first and second elongate contact 
pieces 2 and 3 have free ends 2a and 3a respectively and have their base 
ends connected to each other through the joint portion 4. 
The formation of the arcuate portion 3b and the formation of the first and 
second elongate contact pieces 2 and 3 may be effected simultaneously with 
the punching of the blank members 1 out of the sheet a. 
The second elongate contact piece 3 is then bent at its base end so as to 
extend sideways and apart from the first elongate contact piece 2 at a 
predetermined angle as illustrated in FIG. 4D. The first elongate contact 
piece 2 is then subjected to forging pressure at its free end 2a to form 
an expanded portion 2c having an increased surface area and a reduced 
thickness as illustrated in FIG. 4E and, as illustrated in FIG. 4F, the 
expanded portion 2c of the first elongate contact piece 2 is bent to form 
an arcuate portion 2b. The second elongate contact piece 3 extending 
sidewise is then bent so that a base portion 3c thereof remains extended 
sidewise and a rising portion thereof assumes a substantially L-shape 
having a bent portion 6 and so that the bottoms of the arcuate portions 2b 
and 3b of the first and second elongate contact pieces face each other, as 
illustrated in FIG. 4G. 
Thus, the clamp type contact according to the present invention is 
manufactured. A terminal of an electronic component such as an IC lead, or 
a terminal of an electric connector (not shown) is clamped between the 
arcuate portions 2b and 3b of the first and second elongate contact pieces 
2 and 3 of the clamp type contact as illustrated in FIGS. 1 to 3. The 
joint portion 4 of this clamp type contact can serve as a fulcrum 
permitting the first and second elongate contact pieces 2 and 3 to be 
elastically shifted. In place of the arcuate portions 2b and 3b, the free 
ends 2a and 3a may be formed into a substantially L-shape or any other 
projecting shape. Since forging pressure is subjected to the free end 2a 
of the first elongate contact piece 2, as described above, the surface 
area of the arcuate portion 2b can be made as approximate to the surface 
area of the arcuate portion of the second elongate contact piece 3 as is 
possible, and thus contact of a terminal clamped between the arcuate 
portions 2b and 3b is ensured. 
FIGS. 7 to 9 illustrate another embodiment of the clamp type contact 
according to the present invention. In this embodiment, the lower end of 
the clamp type contact is formed into a pressure-connection contact piece 
7, instead of a male contact piece 5 as in the first embodiment, having a 
cable press-in groove 8 perpendicular to the space between the first and 
second elongate contact pieces 2 and 3. This embodiment is identical in 
structure, other than the lower end of the clamp type contact, to the 
preceding embodiment and, therefore, the detailed description of this 
embodiment has been omitted. 
FIGS. 10 to 12 illustrate still another embodiment of the clamp type 
contact according to the present invention. This embodiment is different 
from the preceding embodiments wherein the blank member 1 is punched at 
the center thereof to form the first elongate contact piece 2 hollowed out 
of the center of the blank member 1 and the second elongate contact piece 
3 is bifurcated, in that this embodiment has first and second elongate 
contact pieces 2 and 3 formed by punching a blank member 1 at one side 
thereof from a portion thereof immediately below the free end 3a as 
illustrated in FIG. 10 showing a semifinished product. The semifinished 
product is processed into a clamp type contact in the same manner as that 
illustrated in FIGS. 4D through 4G. In this embodiment, therefore, the 
second elongate contact piece 3 exhibits higher strength than the 
bifurcated second elongate contact piece 3 of the preceding embodiments. 
According to the present invention, as described above, it is possible to 
efficiently manufacture, from blank members punched out of a sheet to 
having a limited length and a limited width and with highly enhanced stock 
utilization, clamp type contacts having a simple construction having a 
pair of first and second elongate contact pieces which extend in parallel, 
have their respective free ends facing each other and their respective 
base ends joined together, and also have sufficient effective lengths 
necessary for exhibiting elasticity and that terminals of an electronic 
component or electric connector can be elastically clamped between the 
free ends thereof with a high degree of reliability. 
Therefore, the present invention can meet an increasing demand for the 
miniaturization of clamp type contacts. Furthermore, since the free ends 
of the pair of first and second elongate contact pieces of the present 
clamp type contact facing each other have different thicknesses, it is 
possible to suppress the resonance phenomena resulting from external 
vibrations and tending to give rise to an unstable connection between the 
terminals and contact pieces.