Adhesive bonding and miscellaneous chemical manufacture – Methods – Surface bonding and/or assembly therefor
Reexamination Certificate
1998-08-27
2001-07-24
Knable, Geoffrey L. (Department: 1733)
Adhesive bonding and miscellaneous chemical manufacture
Methods
Surface bonding and/or assembly therefor
C156S130700, C156S201000, C156S406400
Reexamination Certificate
active
06264780
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a method of manufacturing a bead filler and an apparatus for forming a filler portion, and more particularly to a method of manufacturing a bead filler constituted by a core portion and a filler portion and disposed in a curved side portion of a pneumatic tire and a filler portion forming apparatus for forming the filler portion.
2. Description of the Related Art
In a turned-up portion of a carcass ply disposed in the side portion of a pneumatic tire, a bead filler composed of a bead core and a filler portion is disposed. The bead core of the bead filler is formed in a circular ring shape by twisting a plurality of cords into one. On the other hand, the filler portion is made from a rubber composition having a predetermined length, and is formed by linearly extruding the rubber composition in a substantially triangular cross sectional shape having a thick base portion and a thin top poriton. The filler portion having a substantially triangular cross sectional shape is disposed in such a manner that one side of the triangle is brought into contact with the carcass ply main body portion
12
A, one side is brought into contact with a bead core
22
and one side is brought into contact with a carcass ply turned-up portion
12
B, as shown in FIG.
2
.
In a process of manufacturing a tire, as shown in
FIG. 7
, a filler portion
82
extruded to a predetermined length is wound around a periphery of a bead core
84
having a circular ring shape. At this time, since the filler portion
82
is in a linearly extruded belt shape, it is wound substantially in a perpendicular state along an axial direction of the ring-like bead core
84
such that a top portion of the filler portion
82
is disposed in a perpendicular state to a radical direction of the bead core
84
. When the winding start end is first mounted to the bead core
84
and the filler portion
82
is wound around once in a manner that a base portion of the filler portion
82
is disposed to contact with a peripheral portion of the bead core
84
, the winding finish end overlaps and presses onto the winding start end. Accordingly, the winding start end and the winding finish end are joined, and a bead filler
80
integrally constructed by the filler portion
82
and the bead core
84
is formed.
As shown in
FIGS. 7A and 7B
, in the constructed bead filler
80
, in which the filler portion
82
is disposed along an axial direction of the bead core
84
, the filler portion
82
is pulled by the top portion thereof in the direction shown by the arrow M and is formed in a shape similar to the shape of the side portion of the pneumatic tire. Next, the bead filler
80
, formed in the shape similar to the shape of the side portion of the pneumatic tire, is mounted on the carcass ply placed on a forming drum and disposed in the side portion of the pneumatic tire by turning up the turned-up portion
12
B of the carcass ply around the bead filler
80
.
In this case, when the top portion of the filler portion
82
is pulled to resemble the shape of the side portion of the pneumatic tire, the rubber composition is stretched out at the top portion of the filler portion
82
so that the diametrical size is greatly increased. At this time, since the base portion of the filler portion
82
is joined to the bead core
84
, the diametrical size of the base portion of the filler portion
82
is only slightly changed. Accordingly, a large difference in diameter is generated between the base portion and the top portion of the filler portion
82
.
Due to this difference in diameter, the amount of the opening is anticipated in advance and the rubber composition is excessively overlapped at that portion so that the joined portion does not open up at the top portion of the filler portion
82
. Accordingly, even if the joined portion is stretched when the diametrical size has increased greatly by pulling up the filler portion
82
, the winding start end and the winding finish end of the filler portion
82
are not separated from each other, so that a bead filler
80
formed in a shape similar to the shape of the side portion of the pneumatic tire can be obtained.
However, when the anticipated amount of opening is great, the overlapped amount becomes great. Accordingly, there are cases where a great difference in thickness is generated between the overlapped portion and the portion not overlapped. Further, the front end of the bead filler
80
is stretched by the anticipated amount so as to be the original thickness, however, the base portion which is overlapped by the same amount as the top portion is less stretched than the top portion. Accordingly, there are cases where the thickness of the filler portion
82
is uneven in the overlapped portion. As mentioned above, when unevenness is generated in the filler portion
82
along the circumferential direction of the side portion of the pneumatic tire, the unevenness becomes an unevenness along the circumferential direction of the side portion of the pneumatic tire, so that the uniformity of the pneumatic tire is deteriorated.
SUMMARY OF THE INVENTION
The present invention was made by taking the facts mentioned above into consideration. An object of the present invention is to provide a method of manufacturing a bead filler which can easily manufacture a bead filler not deteriorating the uniformity of a pneumatic tire, and a filler portion forming apparatus which can form the filler portion of this kind.
In a first aspect of the present invention, there is provided i) a method of manufacturing a bead filler comprising an annular core portion and a filler portion formed by extruding a rubber composition in a specific cross sectional shape and disposed in a curved side portion along the circumferential direction of the side portion of a pneumatic tire, wherein the filler portion is formed by extruding the rubber composition in a curved shape corresponding to the shape of the side portion of the pneumatic tire.
According to the first aspect of the present invention, since the filler portion is formed by extruding the rubber composition in a curved shape corresponding to the shape of the side portion of the pneumatic tire, a bead filler can be constructed which is integrally formed with the bead portion and already corresponds to the shape of the side portion of the pneumatic tire. Accordingly, a great change in the shape such as an expansion of the diameter by pulling the top portion of the filler portion is not required after constructing the bead filler, so that the time and labor hitherto required for the pulling process and the various process accompanying this process can be removed. Further, since it is not necessary to pull the top portion of the filler portion, the thickness and width of the overlapping portion between the winding start end and the winding finish end of the filler portion can be reduced. Accordingly, unevenness of the thickness of the filler portion along the circumferential direction of the side portion of the pneumatic tire is reduced, and the uniformity of a produced tire not thereby deteriorated. Therefore, a bead filler can be easily manufactured without deteriorating the uniformity of the pneumatic tire.
In this case, the description of the curved shape corresponding to the shape of the side portion of the pneumatic tire indicates all curved shapes intentionally extruded in the shape of the side portion of the pneumatic tire. In other words, not only a curved shape perfectly matching the shape of the side portion of the pneumatic tire, but also a curved shape similar to the shape of the side portion are included in this term.
ii) In the item i) mentioned above, the filler portion extruded in the curved shape may be advantageously joined along the periphery of the annular core portion.
Since the filler portion extruded in the curved shape is joined with the annular core portion, an annular bead filler corresponding to the shape of the side portion of the pneumatic tire can be obtained.
iii)
Iwanaga Noriyuki
Senbokuya Takashi
Bridgestone Corporation
Knable Geoffrey L.
Sughrue Mion Zinn Macpeak & Seas, PLLC
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