Expanded – threaded – driven – headed – tool-deformed – or locked-thr – Threaded fastener locked to a discreet structure – Nut – and means to engage substructure on its opposite faces...
Reexamination Certificate
2000-08-14
2003-01-28
Saether, Flemming (Department: 3679)
Expanded, threaded, driven, headed, tool-deformed, or locked-thr
Threaded fastener locked to a discreet structure
Nut, and means to engage substructure on its opposite faces...
C411S181000, C411S501000
Reexamination Certificate
active
06511274
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a metal fastening member such as a T nut, a rivet and the like or to an outer casing member for a bullet having a hollow shaft portion. More specifically, the present invention relates to a metal fastening member and an outer casing member for a bullet having such a structure in that a cap provided at a tip end portion is easily separated to come off when driven into an object.
2. Description of the Background Art
A conventional T nut having a thin flarable portion (prospective caulked portion) in the shaft portion is disclosed, for example, in U.S. Pat. Nos. 5,238,344 or 5,348,432.
A T nut
11
described in U.S. Pat. No. 5,238,344 has such a shape as shown in
FIGS. 95A and 95B
, which is provided as an integral part by sheet metal working of an iron based metal plate, for example, which T nut includes a shaft portion
12
and a flange portion
13
protruding outward from a first end portion of the shaft portion
12
.
Shaft portion
12
has a hollow cylindrical shape with uniform outer diameter, a flarable portion
14
at a second end portion opposite to the first end portion, and a female screw
15
a
formed on an inner peripheral surface of a female screw forming portion
15
other than the flarable portion
14
. Flarable portion
14
is made thinner in thickness as compared with female screw forming portion
15
. Therefore, when female screw
15
a
is to be formed, the thread can be formed either from the side of the first end portion or the second end portion of the shaft portion
12
.
Flange portion
13
has two pawls
16
formed by mushing part of an outer peripheral edge of flange portion
13
from the outer side to the inner side, which pawls oppose to each other at 180°, protruding toward the second end portion of shaft portion
12
. As a result of formation of the pawls
16
, notches
17
having approximately semi circular cross section are left at the outer peripheral edge of flange portion
13
.
Such a T nut
11
is used, for example, in the manner as shown in FIG.
97
A. Referring to
FIG. 97A
, shaft portion
12
is first inserted to an object
19
of fixing formed of resin material or wood and having a receiving hole
18
formed in advance, and in this state, the flarable portion
14
is caulked by a caulker, so that a caulked portion
14
a
is formed on one surface side of object
19
of fixing. At the same time, pawls
16
are driven into the other surface of the object
19
of fixing. Thus T nut
11
is completely fixed in object
19
.
A T nut
31
described in U.S. Pat. No. 5,348,432 has such a shape as shown in
FIGS. 96A and 96B
. Similar to T nut
11
described above, it is provided as an integral body by sheet metal working of an iron based metal plate, for example, and the T nut has a shaft portion
32
and a flange portion
33
protruding outward from the first end portion of shaft portion
32
. The shaft portion
32
has a female screw forming portion
35
where a female screw
36
is formed on the inner periphery, and the T nut also has a flarable portion (prospective caulked portion)
34
. The structure of T nut
31
is different from that of T nut
11
in that two pairs of pawls
37
and
38
as well as
39
and
40
extending from the first end portion toward the second end portion are arranged opposing in the radial direction of flange portion
33
, so that flange portion
33
as a whole has substantially octagonal shape.
Such a T nut
31
is generally called a “hopper feed T nut”, since the T nut
31
can be smoothly moved along a feed track which is provided on a nut fixer for fixing the nut to the object, enabling automatic feeding of the T nuts. For example, British Patent No. 1,157,734 describes a type of such a hopper feed T nut in detail.
FIG. 96B
shows the aforementioned feed track
243
in phantom lines. Feed track
243
includes a pair of guide rails
244
and
245
having C-shaped sections, which are symmetrically arranged to be opposite to each other. Flange portion
33
is received by each of the guide rails
244
and
245
, so that T nut
31
is moved along feed track
243
in a prescribed posture while locating the pawls
37
to
40
between the guide rails
244
and
245
. Though not shown, feed track
243
is frequently bent to bring the T nut
31
into a desired posture, so that shaft portion
32
is aligned with a hole provided in an object, not shown.
T nut
31
is used in the similar manner as T nut
11
, as shown in
FIG. 97B
, for example. More specifically, shaft portion
32
of T nut
31
is inserted to a through hole
18
of an object
19
of fixing, flarable portion
34
is caulked by a caulker in this state, and caulked portion
34
a
is formed on the side of one surface of object
19
. At the same time, pawls
37
to
40
are driven into the other surface of object
19
.
In such a state of fixing of T nut
31
, rotation of T nut
31
relative to the object
19
of fixing is inhibited by pawl
37
to
40
, and flange portion
33
and caulked portion
34
a
grip the object
19
, so that T nut
31
is not slipped from through hole
18
. Thus, T nut
31
is firmly fixed on object
19
, and the fixed state is maintained semi-permanently.
When the above described T nut is to be driven to the object of fixing under automatic control, however, it is necessary to provide a receiving hole exactly at the expected position to which T nut is driven, of the object of fixing. Further, it is necessary to position the T nut exactly at the receiving hole and to drive the T nut into the object.
Therefore, when the T nut is to be driven to the object of fixing by automatic control, exact positioning is necessary both in the process of forming receiving hole and the process of driving the T nut, which results in lower efficiency of working and increase in cost of driving.
SUMMARY OF THE INVENTION
The present invention was made to solve the above described problems and its object is to provide a metal fastening member having such a structure that enables exact driving into the object of fixing without the necessity of forming a receiving hole in advance.
Another object of the present invention is to provide an outer casing member for a bullet of which tip end portion surely tears simultaneously with collision at the object.
According to an aspect, the present invention provides a metal fastening member including a cylindrical shaft portion having a flarable portion which is expected to be caulked and a shaft body portion provided continuous from the flarable portion, and a cap portion provided continuous from an end portion of the flarable portion opposite to the shaft body portion, and formed of an integral metal material, wherein a connecting region between the flarable portion and the cap portion has such a shape in that, a force bending outward the flarable portion is exerted when a pressing force is applied to the tip end surface of the cap portion in a direction from the side of the cap portion to the side of the flarable portion, so that the cap portion is separated or goes off from the flarable portion by the bending force and the flarable portion comes to be bent outward.
In the above described structure, when the metal fastening member is driven into the object of fixing, the object of fixing is removed by the cap portion, and therefore it is unnecessary to provide in advance a receiving hole for driving the metal fastening member in the object of fixing.
As an example of a preferred embodiment, a structure may be adapted in which an inner surface of the flarable portion is recessed outward at the connecting region between the flarable portion and the cap portion, so that immediately after driving the metal fastening member into the object of fixing, when the cap portion collides an abutting member provided outside, the cap portion is kept in the state colliding against the abutting member, whereas an external force for caulking is applied to the flarable portion. At this time, as the inner surface of the flarable portion is recessed outward
Fasse W. F.
Fasse W. G.
Nagayama Electronic Industry Co. Ltd.
Saether Flemming
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