Plastic and nonmetallic article shaping or treating: processes – Mechanical shaping or molding to form or reform shaped article – To produce composite – plural part or multilayered article
Reexamination Certificate
2003-03-26
2004-11-16
McDowell, Suzanne E. (Department: 1732)
Plastic and nonmetallic article shaping or treating: processes
Mechanical shaping or molding to form or reform shaped article
To produce composite, plural part or multilayered article
C264S236000, C264S237000, C264S284000, C264S285000, C264S286000, C264S287000, C264S347000, C264S348000
Reexamination Certificate
active
06818167
ABSTRACT:
TECHNICAL FIELD
This invention relates to a method of manufacturing an endless rubber crawler suitable for use in snowmobiles remolded from recreational vehicles (hereinafter abbreviated as RV vehicle) or the like, construction vehicles and the others.
BACKGROUND ART
Recently, it is increasing to use an RV vehicle as a snowmobile or the like by taking off drive wheels from the RV vehicle and attaching a tracked driving device comprised of plural sprockets and rollers thereto and mounting an endless rubber crawler onto the tracked driving device. In this case, it is strongly demanded to provide a rubber crawler capable of accommodating with the speedup of the running speed
And also, construction vehicles and the like are mounted with a rubber crawler for reducing noise, vibration and the like in addition to the usual snowmobiles. Even in this case, it is pressed to accommodate the crawler with the speedup.
The rubber crawler widely used from the old time is generally manufactured by methods as shown in
FIGS. 1 and 2
, respectively.
The method shown in
FIG. 1
is a basic manufacturing method. According to this method, a band-shaped rubber member
31
containing reinforcing cords (not shown) embedded therein as shown in FIG.
1
(
a
) is sandwiched between upper and lower molds
32
,
33
as shown in FIG.
1
(
b
) and these molds
32
,
33
are sandwiched between heat plates
34
,
35
and then the band-shaped rubber member
31
is vulcanized by heating to obtain a crawler material
36
. Thereafter, as shown in FIG.
1
(
c
), both crisscross thin end portions
36
A,
36
B of the crawler material
36
are piled one upon the other, and these both end portions
36
A,
36
B are joined by vulcanization through upper and lower molds
37
,
38
and heat plates
39
,
40
for joining end portions to form an endless rubber crawler.
The method shown in
FIG. 2
is a manufacturing method called as a feed vulcanization, which is used for manufacturing an endless rubber crawler having a relatively long peripheral length.
In this case, a continuous band-shaped rubber member
41
containing reinforcing cords embedded therein as shown in FIG.
2
(
a
) is sandwiched between relatively short upper and lower molds
42
,
43
and these molds
42
,
43
are sandwiched between heat plates
44
,
45
as shown in FIG.
2
(
b
), and a given length of the band-shaped rubber member
41
is partially vulcanized by heating. By successively repeating such a procedure over a full length of the band-shaped rubber member
41
is formed a crawler material
46
. Then, an endless rubber crawler can be manufactured from the crawler material
46
by piling both crisscross thin end portions
46
A,
46
B of the crawler material
46
one upon the other and joining by vulcanization through upper and lower molds
42
,
43
and heat plates
44
,
45
as shown in FIG.
2
(
c
).
In these conventional methods, however, it is obliged to previously conduct the shaping of the band-shaped rubber material
31
,
41
prior to the vulcanization step, so that the shaping step and the shaping apparatus are unavoidable and also an apparatus for transferring the band-shaped rubber material to the vulcanization step becomes large-scale and the manufacture of the rubber crawler is required to take a great deal of time and many operation numbers.
Further, in the vulcanization method shown in
FIG. 1
, the mold and heat plate become long and massive and are required to have a large setting space, and also the joint vulcanization step on only the end portions is further required. On the other hand, in the vulcanization method shown in
FIG. 2
, the mold and heat plate are made small, but the vulcanization is repeated from several times to about 10 times every a given length, so that a considerably long vulcanization time is required and also there is a problem that the joining step of the end portions is required likewise the above case.
Even in these methods, both end portions of the band-shaped crawler material
36
,
46
including the reinforcing cords are joined by vulcanization, so that the reinforcing cords are overlapped in the joint portion to make the thickness thick and hence it is impossible to provide uniform properties on a circumference of the crawler and there is caused a fear of breaking the continuity in the reinforcing strength. And also, it is impossible to embed spiral reinforcing cord(s) capable of uniformly reinforcing on the circumference. In the conventional methods, therefore, it is impossible to manufacture a rubber crawler capable of accommodating with the running at a high speed accompanied with the speedup of a vehicle.
Under the above situation, the applicant already proposed a method of manufacturing a rubber crawler through two-stage vulcanization as shown in
FIG. 3
(Japanese Patent Application No. 11-325474).
This is a method of manufacturing a rubber crawler by vulcanization-joining rubbers
2
A,
2
B and
3
A,
3
B to an inner circumferential side and ground side of an endlessly ring-shaped reinforcing cord
1
by heating and pressing through molds
4
,
5
,
6
, respectively, which comprises a first vulcanization step of simultaneously vulcanization-shaping inner circumferential side rubbers
2
A,
2
B and ground side rubbers
3
A,
3
B having a length corresponding to approximately a half circumferential length of the reinforcing cord
1
in total among a middle mold
6
arranged at the inner circumferential side of the endlessly ring-shaped reinforcing cord
1
and an upper mold
4
and a lower mold
5
arranged up and down on an outer circumferential side of the reinforcing cord, and a second vulcanization step of subsequently vulcanization-shaping inner circumferential side rubbers
2
C,
2
D and ground side rubbers
3
C,
3
D having a length corresponding to approximately a remaining half circumferential length in the same manner as mentioned above.
According to this method, approximately a half circumferential length of the rubber crawler can be shaped by vulcanization at once through the relatively small-size upper and lower molds
4
,
5
and middle mold
6
, and also the vulcanization is completed by two vulcanization-shaping steps in total, so that the reduction of the cost can be attained by miniaturizing the vulcanization equipment and the number of steps including preparatory step and vulcanization step can be decreased, and also it is possible to embed the spiral reinforcing cord and the joint portions through vulcanization-joining can be decreased to give a sufficiently uniform strength property on the circumference and hence the rubber crawler capable of accommodating with the high speed running can be manufactured.
In the above proposed technique, however, a heat plate or the like for vulcanization is particularly arranged in the middle mold
6
at the first vulcanization step, so that a thickness D in up-down direction of the figure of the middle mold used becomes considerably thick. As a result, there is caused an inconvenience that an enveloping space by a protruding portion E
1
of the reinforcing cord
1
from the mold at the first vulcanization step shown in FIGS.
3
(
a
), (
b
) or a protruding portion E
2
of a vulcanized crawler part at the second vulcanization step shown in FIGS.
3
(
c
), (
d
) is restricted by an increment of the thickness D. This is particularly serious in case of adopting a vulcanization method that each end portion of rubber parts
2
A,
3
A and
2
B,
3
B vulcanized at the first vulcanization step is positioned and arranged in the upper and lower molds
4
,
5
and middle mold
6
by overlapping, for example, at a rate corresponding to several pitches at the second vulcanization step to thereby more ensure mutual joining of rubber parts vulcanized at each of the first and second vulcanization steps. That is, the enveloping space becomes further smaller in connection with the length of the mold and the circumferential length of the rubber crawler, so that there is a fear that a handling operation in the taking out of the rubber crawler from the molds low
Bridgestone Corporation
McDowell Suzanne E.
LandOfFree
Method of manufacturing rubber crawler does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Method of manufacturing rubber crawler, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Method of manufacturing rubber crawler will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3300461