Metal fusion bonding – Process – Using dynamic frictional energy
Reexamination Certificate
1998-12-22
2001-06-12
Evans, Geoffrey S. (Department: 1725)
Metal fusion bonding
Process
Using dynamic frictional energy
C228S114500
Reexamination Certificate
active
06244496
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to a connected structure, more particularly, to a connected structure including a supporting member and a bushing mounting member connected thereto for use as, for example, an automobile suspension arm or an engine mount.
2. Description of the Related Art
FIG. 8A
shows a conventional automobile suspension arm
50
used as an upper arm, a lower arm, a trailing arm or a torsion arm. The suspension arm
50
includes a rod-shape supporting portion
51
and a bushing mounting portion
52
formed at opposite ends of the supporting portion
51
. The bushing mounting portion
52
may be formed at one end of the supporting portion
51
. The bushing mounting portion
52
has a circular opening
53
for mounting a columnar vibroisolating bushing
60
. The bushing
60
includes, for example, a central supporting member
61
, an outer rigid sleeve
62
having an outer diameter slightly larger than the inner diameter of the opening
53
, and a rubber elastic member
63
disposed between the center supporting member
61
and the outer rigid sleeve
62
. The bushing
60
is press-fitted in the opening
53
. As shown in
FIG. 8A
, the supporting portion
51
is provided with a plurality of penetrated holes
54
.
The above suspension arm
50
has been manufactured by cutting an extruded article having a cross-section corresponding to the cross-section of the suspension arm
50
to have a predetermined thickness in the direction of the extrusion.
Therefore, the supporting portion
51
is formed to have a rectangular shape in cross-section as shown in FIG.
8
B. Such a rectangular cross-sectional shape of the supporting portion
51
inherently deteriorates the efficiency for utilizing the surrounding space. Further, the supporting portion
51
makes the whole suspension arm
50
heavy because the supporting portion
51
is formed to be non-hollow article.
It may be possible to manufacture the suspension arm
50
by separately preparing the supporting portion
51
and the bushing mounting portion
52
, and then integrally joining them by a melt welding such as a MIG welding (metal electrode inert gas welding) and a TIG welding (tungsten-inert-gas arc welding), However, since the heat quantity of the melt welding is large, the rubber elastic member
63
of the bushing
60
, which is press-fitted in the bushing mounting body
52
, is influenced by the heat generated during the welding to cause the change of its characteristic. Further, such a large heat quantity may cause a poor joint between the supporting body
51
and the bushing mounting body
52
, and/or a thermal fatigue of the supporting body
51
and the bushing mounting body
52
.
SUMMARY OF THE INVENTION
An object of the present invention is to provide a connected structure for use as a suspension arm or the similar structure, which is light in weight and high in strength and has an improved efficiency for utilizing the surrounding space and a predetermined characteristics of a bushing, and also is to provide a method for manufacturing the connected structure.
Another object of the present invention is to provide a method for manufacturing a connected structure in which the manufacturing efficiency can be improved.
In order to attain the above object, according to the present invention, a connected structure includes a hollow supporting member having an opening at one end thereof, and a bushing mounting member having a bushing mounting portion for mounting a bushing having a rubber elastic member and a connecting portion protruded from the bushing mounting portion. The connecting portion is inserted in the opening and joined to the hollow supporting member along a circumferential direction thereof by a friction agitation joining method, whereby the bushing mounting member is integrally connected to the hollow supporting member.
According to the present invention, the connected structure can be light in weight since the supporting member is made of a hollow article. Further, since the bushing mounting member is joined to the hollow supporting member by a friction agitation joining method in which heat quantity is smaller than that of the melt welding such as a MIG welding or a TIG welding, the joint strength between the supporting member and the bushing mounting member will not deteriorate, and the materials of the connected structure will not be thermally fatigued. As a result, a connected structure having high joint strength and well joint condition can be obtained.
Even if the supporting member is joined in a state that the busing is mounted in the bushing mounting portion, characteristics of the bushing can be well maintained since the rubber elastic member of the bushing is hardly affected by heat.
When the hollow supporting member has a circular cross-sectional shape, surrounding space of the supporting member can be efficiently utilized.
Further, according to the present invention, a method for manufacturing a connected structure having a supporting member and a bushing mounting member connected to the supporting member, includes the steps of preparing a hollow supporting member having an opening at one end thereof, preparing a bushing mounting member having a bushing mounting portion for mounting the bushing and a connecting portion protruded from the bushing mounting portion, inserting the connecting portion into the opening of the hollow supporting member, and joining the connecting portion and the hollow supporting member along a circumference of the hollow supporting member by a friction agitation joining method.
According to the method, a lightweight connecting member can be obtained since the supporting member is made of a hollow article. Further, since the supporting member and the connecting portion inserted into the opening of the supporting member are joined along a circumference of the supporting member by the friction agitation joining method, a connected structure with a high joint strength and fine joint quality can be obtained.
If the connecting portion is press-fitted into the opening of the supporting member and the friction agitation joining method is performed by inserting a rotating probe into the connecting portion from the hollow supporting member to soften and agitate a portion where the probe contacts by friction heat, and rotating one of the connecting portion and the hollow supporting member along axis thereof, whereby both of the connecting portion and the hollow supporting member rotate together and the rotating probe advances along a circumference of the hollow supporting member, the joining can easily be performed.
If the friction agitation joining method is performed by using a joining device having a pin-shaped probe coaxially integrally protruded from an end surface of a columnar rotor having a diameter larger than a diameter of the probe, inserting the rotating probe into the connecting portion from the hollow supporting member to soften and agitate a portion where the probe contacts by friction heat, advancing the rotating probe along a circumference of the hollow supporting member in such a state that the end surface of the columnar rotor presses a portion of the hollow supporting member located behind said columnar rotor and is lifted up from a portion of the hollow supporting member located ahead of the columnar rotor, not only the rotating probe generates friction heat, but also the friction between the pressed portion of the end surface and a surface and an inner matrix of the supporting member generates friction heat. Thus, a portion of the supporting member and the connecting portion where the probe contacts and the region there-around can be softened quickly, resulting in speedy and efficient joining work. Further, since the end surface of the rotor is lifted up from the surface of the upstream portion of the supporting member, the edge of the end surface of the rotor facing the upstream portion of the supporting member can be prevented from being caught by the surface of the supporting member so as not to tear o
Enomoto Masatoshi
Hashimoto Takenori
Kato Rentaro
Kawata Naoyuki
Nishikawa Naoki
Edmondson Lynne
Evans Geoffrey S.
Tokai Rubber Industries Ltd.
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