Metal working – Method of mechanical manufacture – Disassembling
Reexamination Certificate
1999-11-22
2001-06-05
Briggs, William (Department: 3722)
Metal working
Method of mechanical manufacture
Disassembling
C029S268000, C029S566100
Reexamination Certificate
active
06240614
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a blind rivet disassembling device and method and a production system using the method, wherein a blind rivet body having a body portion and a flange portion, with a through hole being formed through the blind rivet body in an axial direction of the body portion from the body portion toward the flange portion, is inserted into clamping holes formed in base metals, a mandrel having a stem portion and a head portion, the head portion being substantially integral with the stem portion and larger than the diameter of the through hole of the blind rivet body, is inserted into the through hole, the head portion of the mandrel is pulled into the through hole as the mandrel is pulled, so that a peripheral wall of the body portion around the through hole undergoes a plastic deformation and is bulged and the mandrel is broken, allowing a portion of the mandrel to remain as a residual mandrel within the through hole, the base metals are sandwiched by the bulge of the peripheral wall of the body portion and the head portion of the mandrel, and the blind rivet clamped to the base metals is separated from the base metals.
2. Description of the Related Art
As a technique for joining base metals such as steel plates or plastic plates or for joining another member to such a base metal there is known a rivet clamping technique. As an example there is known a clamping method in which base metals
1
and
2
are joined mechanically with use of a blind rivet.
As shown in FIG.
14
(
a
), the blind rivet, indicated at
10
, comprises a blind rivet body
11
and a mandrel (core stem)
12
. The blind rivet body
11
comprises a body portion
11
b
and a flange portion
11
c
which is substantially integral with the body portion
11
b
. A through hole
11
a
is formed through the blind rivet body
11
in an axial direction of the body portion
11
b
from the body portion toward the flange portion
11
c
. The mandrel
12
comprises a head portion
12
a
and a stem portion
12
c
which is substantially integral with the head portion. The head portion
12
a
has an outside diameter larger than the diameter of the through hole
11
a
. The stem portion
12
c
is formed with a constriction
12
b
at an intermediate position in its extending direction.
Using the blind rivet
10
, the base metals
1
and
2
are clamped together mechanically in accordance with the following procedure for example.
First, the body portion
11
b
of the blind rivet body
11
is inserted into clamping holes
1
a
and
2
a
of base metals
1
and
2
, as shown in FIG.
15
(
a
), and a blind rivet clamping device
13
is set at an end portion of the mandrel
12
, as shown in FIG.
15
(
b
),
Then, as shown in FIG.
15
(
c
), a nose piece
13
a
of the blind rivet clamping device
13
is brought into close contact with the flange portion
11
c
of the blind rivet body
11
and the blind rivet clamping device
13
is triggered while the flange portion
11
c
is pushed against the base metal
1
by the nose piece
13
a.
As a result, the mandrel
12
is chucked by a jaw member
13
b
of the blind rivet clamping device
13
and is pulled in the direction opposite to the pushing direction, then as the head portion
12
a
of the mandrel is pulled into the through hole
11
a
, the peripheral wall of the body portion
11
b
projecting from the back side of the base metal
2
is deformed plastically into a bulge
11
d
by the head portion
12
a
of the mandrel
12
, which is brought into pressure contact with the base metal
2
.
In this state, if the jaw member
13
b
is further pulled in the direction opposite to the pushing direction, the mandrel
12
will be broken at its constriction
12
b
, so that the base metals
1
and
2
are clamped together by the blind rivet
10
, as shown in FIG.
15
(
d
). A portion of the mandrel
12
remains as a residual mandrel
12
′ within the through hole
11
a
, as shown in FIG.
14
(
b
).
According to this method using the blind rivet
10
, since the base metal clamping is effected by applying tension in the direction opposite to the pushing direction, as shown in FIGS.
15
(
a
) to
15
(
d
), the clamping work for the base metals
1
and
2
can be done without supporting the back side of the base metals and therefore this method is suitable for clamping the base metals
1
and
2
in such a place where the worker's hand cannot reach the back side of the base metals.
Thus, in the blind rivet
10
, as the mandrel
12
inserted into the through hole
11
a
of the blind rivet body
11
is pulled, the peripheral wall of the body portion undergoes a plastic deformation, with consequent formation of the bulge
11
d
, and the base metals
1
and
2
are held in a clamped state by both bulge
11
d
and flange portion
11
c
. In the event there should occur a defective clamp in clamping the blind rivet
10
to the base metals
1
and
2
and the resulting necessity of repeating the same work or in the event there should occur the necessity of recycling the base metals
1
and
2
, it is necessary to disassemble and remove the blind rivet
10
.
As a disassembling method for the blind rivet
10
there is known such a method as shown in
FIG. 16
, in which with a drill
14
, the flange portion
11
c
of the blind rivet
10
is cut and removed from the body portion
11
b
, then, by tapping the cut portion in a direction in which the body portion
11
b
comes out of the clamping holes
1
a
and
2
a
, the blind rivet
10
is pulled out from the base metals
1
and
2
.
Such a conventional blind rivet disassembling method requires much time and labor for preparatory works, including selection of the drill
14
and the cutting work. Moreover, in cutting the flange portion
11
c
, if the tip of the drill
14
reaches the base metal
1
and cuts the clamping hole
1
a
of the base metal, with consequent increase in size of the clamping hole
1
a
, as shown in
FIG. 17
, it will be impossible to ensure a sufficient clamping force even if this base metal
1
is recycled and re-clamped using the blind rivet
10
. Generally, once the base metals
1
and
2
are flawed in the blind rivet disassembling work, it becomes difficult to recycle such base metals.
Further, in the case of using this type of a drill in the clamp member disassembling work, the blind rivet body
11
undergoes a follow-up rotation with rotation of the drill
14
at the time of cutting the flange portion
11
c
of the blind rivet
10
, thus giving rise to the problem that the base metal
1
is scratched or it is impossible to cut the flange portion
11
c
. Particularly, when the base metal
1
is used as an outer component of a product, a scratch, if any, on the surface of the base metal
1
will markedly deteriorate the commercial value of the product. Therefore, such a scratched base metal
1
cannot be recycled, and if it should be recycled, the percent defective of the base metal at the time of disassembly would become very high.
Therefore, to prevent the follow-up rotation of the clamp member with rotation of the drill
14
, the flange portion
11
c
is cut with by the drill
14
, as shown in
FIG. 16
, while the flange portion
11
c
or the body portion
11
b
is chucked by a chucking tool
15
such as pliers or pincers. However, this work is performed by two or more workers because it is dangerous if this work is done by one worker, resulting in an increase of personnel expenses in the disassembling work.
Particualarly, as shown in
FIG. 18
, when the flange portion
11
c
of the blind rivet
10
is in a flat shape and is difficult to be chucked by the chucking tool
15
and when the base metals
1
and
2
are clamped by the blind rivet
10
in such a place where the worker's hand cannot reach the back side of the base metals, it is difficult to prevent the follow-up rotation because the body portion
11
b
cannot be chucked by the chucking tool
15
.
As another method for removing the blind rivet
10
from the base metals
1
and
2
there also
Jibiki Yuichi
Kojima Takao
Briggs William
Oblon & Spivak, McClelland, Maier & Neustadt P.C.
Ricoh & Company, Ltd.
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