Metal working – Method of mechanical manufacture – Assembling or joining
Reexamination Certificate
1999-04-19
2001-12-18
Bryant, David P. (Department: 3726)
Metal working
Method of mechanical manufacture
Assembling or joining
C029S243560
Reexamination Certificate
active
06330739
ABSTRACT:
CROSS REFERENCE TO RELATED APPLICATION
This application is based upon and claims the benefit of Japanese Patent Application No. 10-109428, filed on Apr. 20, 1998, the contents of which are incorporated herein by reference.
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to a method for caulking two members and an apparatus used for the method.
2. Description of the Related Art
Two members can be fixed with one another by a so-called caulking method. For instance, as shown in
FIG. 14
, the caulking method is carried out to a first member
1
a
formed with two caulking claws
11
a
and an engagement recess
10
a
, and to a second member
2
a
having an engagement portion
20
a
that is disposed in the recess
10
a
. In this state, the caulking claws
11
a
are bent along the outer surface of the second member
2
a
to hold the second member
2
a
. Otherwise, as shown in
FIG. 15
, the caulking claws
11
a
are upset inward by flat pushing jigs to hold the second member
2
a.
However, in the methods described above, there arise the following problems. That is, when the caulking claws
11
a
are bent by caulking, as shown in
FIG. 16
, cracks
99
are liable to occur on the outer surfaces of the caulking claws
11
a
due to tensile stress that is produced on the outer surface side during the caulking.
When the caulking claws
11
a are upset by caulking, cracks do not occur; however, as shown in
FIG. 17
, central portions of the caulking claws
11
a
may expand during the upsetting when rigidity of the second member
2
a
is smaller than that of the first member
1
a
. In such a case, as shown in
FIGS. 18 and 19
, the second member
2
a
can be easily detached from the first member
1
a
by levering.
SUMMARY OF THE INVENTION
The present invention has been made in view of the above problems. An object of the present invention is to provide a caulking method for easily and securely fixing two members and an apparatus used for the method.
According to the present invention, a first member having a pair of claws opposed to one another and an engagement recess provided between the pair of claws is caulked with a second member having an engagement portion. Specifically, after disposing the engagement portion of the second member in the engagement recess of the first member, outer faces of the pair of claws are externally held by a first jig. Then, a second jig is brought to contact with front end portions of the pair of claws. The second jig has a generally trapezoid recess with a pair of first processing walls that contact the front end portions of the pair of claws and a second processing wall interposed between the pair of first processing walls. Next, the pair of claws is bent along the pair of first processing walls to reach the second processing wall, respectively, by pushing the second jig. Successively, the pair of claws is upset by the second processing wall by further pushing the second jig.
That is, according to the present invention, the pair of claws is upset after they are bent inward by the second jig while being held externally by the first jig. As a result, the first member is securely caulked with the second member without expanding in an opposite side of the second member and without producing cracks thereon. The first and second jigs can be easily manufactured, resulting in low cost.
The first member is preferably disposed on a base so that the engagement recess is open on an opposite side of the base for holding the second member therein. Preferably, the first processing walls are inclined walls relative to the second processing wall, and the second processing wall is a flat wall. Preferably, inflected joint-portions are provided between the first processing walls and the second processing wall to prevent stress concentration thereon.
REFERENCES:
patent: 2759256 (1956-08-01), Bergan
patent: 3146519 (1964-09-01), Redwine
patent: 3643327 (1972-02-01), Jackson
patent: 3871071 (1975-03-01), Luongo
patent: 3995870 (1976-12-01), Hulek
Bryant David P.
Denso Corporation
Pillsbury & Winthrop LLP
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