Adhesive bonding and miscellaneous chemical manufacture – Methods – Surface bonding and/or assembly therefor
Reexamination Certificate
2002-01-24
2004-05-04
Sells, James (Department: 1734)
Adhesive bonding and miscellaneous chemical manufacture
Methods
Surface bonding and/or assembly therefor
C156S064000
Reexamination Certificate
active
06730182
ABSTRACT:
CROSS REFERENCE TO RELATED APPLICATION
This application is based on and incorporates herein by reference Japanese Patent application No. 2001-22103 filed on Jan. 30, 2001 and Japanese Patent Application No. 2001-354598 filed on Nov. 20, 2001.
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a method for vibrating, melting and bonding a plurality of resin parts in which the contact surfaces of resin parts are vibrated, to cause melting and subsequent bonding of the parts.
2. Description of the Related Art
In the background arts, there is a low cost vibrating, melting and bonding method as a method for bonding resin parts to each other. This method is performed as follows. First, while a plurality of resin parts are pressed onto each other, they are made to abut against each other and their contact surfaces are vibrated to melt the resin at the contact surfaces by the use of frictional heat generated by the vibration. Then, when the resin at the contact surfaces is melted, the vibration is stopped and the resin at the contact surfaces is cooled and solidified, thereby bonding the resin parts.
However, according to the conventional technique described above, when variations occur in the state of heating of the contact surfaces during the vibrating operation because of variations in the pressing force, the state or degree of melting of the resin at the contact surfaces varies. When the degree or state of melting of the resin at the contact surfaces varies, there is a problem that when the resin is cooled and solidified, a stable bonding state can not be obtained.
SUMMARY OF THE INVENTION
The present invention has been made in view of the problem of the conventional technology. It is an object of at least one embodiment of the present invention to provide a method for vibrating, melting and bonding resin parts capable of producing a bonded part in which the resin parts are stably bonded to each other.
In order to achieve the object described above, an aspect according to one embodiment of the invention is characterized, in
FIG. 1
, in that in a method for vibrating, melting and bonding at least two resin parts (
7
,
8
) by making the at least two resin parts (
7
,
8
) abut against each other and vibrating their contact surfaces (
71
and
82
of
FIG. 2
) while applying a pressing force to them, the pressing force is sharply increased to a predetermined value P
1
and then is gradually increased.
According to an embodiment of the invention, after a heating operation is started, the pressing force is increased sharply to the predetermined value P
1
to facilitate heat generation. However, if the same pressing force is applied continuously to the contact surfaces (
71
,
82
) of the resin parts (
7
,
8
) after they are heated, the resin material at the contact surfaces (
71
,
82
) is excessively heated and becomes degraded. For this reason, according to an embodiment of the present invention, after the pressing force reaches the predetermined value P
1
, the pressing force is gradually increased to push out the heated resin material from the contact surfaces (
71
,
82
). This exposes a new surface of the resin material which is not heated so much and thus prevents the resin material at the contact surfaces (
71
,
82
) from being excessively heated.
In this connection, since the contact surfaces (
71
,
82
) of the resin parts (
7
,
8
) are not completely flat, variations occur in heating the contact surfaces (
71
,
82
) of the resin parts (
7
,
8
). In order to obtain consistent melting and bonding throughout the contact surfaces (
71
,
82
), it is necessary to apply heat as uniformly as possible throughout the contact surfaces (
71
,
82
). Therefore, it is necessary to melt the resin material at the contact surfaces (
71
,
82
) in a uniform manner to achieve consistency in heating the contact surfaces (
71
,
82
). In this case, even if variations occur in heating the contact surfaces (
71
,
82
) of the resin parts (
7
,
8
), it is possible to prevent parts of the resin material from being excessively heated.
In this manner, by preventing the resin material at the contact surfaces (
71
,
82
) of the resin parts (
7
,
8
) from being excessively heated, it is possible to solidify the resin material which does not deteriorate and is nearly uniform in the state of melting throughout the contact surfaces (
71
,
82
) to produce a well-bonded part. Additionally, the pressing force is continuously and gradually increased until the vibrating of the contact surfaces is finished. This makes it possible to prevent the resin material from being excessively heated by the heat generated by the vibrating operation.
In another aspect, the pressing force is continuously gradually increased from the predetermined value P
1
in a range not exceeding a predetermined upper limit pressing force P
2
. If the pressing force exceeds the predetermined upper limit pressing force P
2
, the resin material is removed from the contact surfaces before the resin material is sufficiently heated and thus there is the possibility that acceptable bonding can not be achieved. For this reason, it is effective to increase the pressing force gradually in the range so as not to exceed the predetermined upper limit pressing force P
2
. Alternatively, the pressing force may be continuously gradually increased by a combination of a period in which the pressing force is held at a constant value and a period in which the pressing force is increased. In order to increase the pressing force gradually, of course, the pressing force may be increased continuously (linearly), and an increasing gradient of the pressing force may be increased gradually as a whole by combining the period in which the pressing force is held at a constant value with the period in which the pressing force is increased.
With respect to vibration, after the vibrating of the contact surfaces is started, a moving speed of the contact surfaces (
71
,
82
) may be sharply increased to a predetermined upper limit and the moving speed may thereafter be decreased gradually. According to an embodiment of the invention, after the vibrating operation is started, by sharply increasing the moving speed to the predetermined upper limit, heating is facilitated to melt the resin material at the contact surfaces (
71
,
82
). By decreasing the moving speed gradually after the resin material at the contact surfaces (
71
,
82
) of the resin parts (
7
,
8
) is heated and melted, heat generation is decreased to prevent the resin material at the contact surfaces from being excessively heated, which may promote material degradation. Therefore, it is possible to solidify the resin material which is not yet degraded and in a state of melting to obtain a well-bonded part.
Continuing with an embodiment of the preset invention, the position of one
8
of the two resin parts (
7
,
8
) is measured as the amount of melting M of the resin parts (
7
,
8
) at the contact surfaces (
71
,
82
) with reference to the other resin part
7
, is in progress. A determination is made whether the amount of melting M increases with the lapse of time or not; and on the basis of the determination result, a determination is made whether the melting and bonding of the resin parts (
7
,
8
) is acceptable.
In the related art, when the amount of melting at the contact surfaces of the resin parts reaches a predetermined amount, the vibrating operation is stopped and the melting resin material at the contact surfaces is solidified to complete the bonding of the contact surfaces. In the case where variations occur in the state of melting of the resin material at the contact surfaces because of variations in heating when the vibrating operation is carried out, the amount of melting hardly increases (or may only increase a little) until the resin material at the portion where heat generation does not yet progress is sufficiently heated and melted. Then, when the whole contact surface is melted, the amount of melting increases at a portion and reaches a p
Iwamatsu Ryouji
Murata Syuuji
Shibata Takayuki
Yada Akihiro
Yamazaki Yasuhiko
Denso Corporation
Harness Dickey & Pierce PLC
Sells James
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