Conveyors: power-driven – Conveyor section – Endless conveyor
Reexamination Certificate
2001-04-04
2003-03-04
Valenza, Joseph E. (Department: 3651)
Conveyors: power-driven
Conveyor section
Endless conveyor
C198S845000, C059S004000, C474S209000
Reexamination Certificate
active
06527106
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to a roller fitted around a bushing of a conveyor chain used for conveyance of bottles, cans, precision parts, paper containers, sushi serving plates and so on, or of a chain used for cower transmission, and also to a chain equipped with such roller.
A conveyor chain such as a top chain used for conveyance of sushi serving plates along a circulation path is mainly formed from engineering plastic or stainless steel. According to the structure, the top chain is generally classified into two types; one being of the “roller” type which has a roller mounted on a bushing at the link joint portion of a base chain, and the other being of the “bush” type which has no roller mounted on a bushing (see, Japanese Utility Model Laid-open Publication No. (SHO) 62-98615 and Japanese Utility Model Publication No. (HEI) 2-31456, respectively).
FIG. 3
shows in top plan view a part of the conventional roller type top chain formed from a plastic material. The top chain
31
comprises a crescent-shaped top plate
32
and a base chain
33
.
FIG. 4
shows a link element of the top chain
31
, which is formed by an offset link. As shown in perspective view in
FIG. 5
, an upper link
34
and an inner bushing tube
35
are formed integrally with each other, and a lower link
36
and an outer bushing tube
37
are formed integrally with each other. The inner bushing tube
35
is fitted in the outer bushing tube
37
so as to form a link assembly
38
. The inner and outer bushing tubes
35
and
37
jointly form a bushing portion having a separable structure. When the inner bushing tube
35
is inserted in an axial hole
37
A of the outer bushing tube
37
, a generally annular locking projection
35
A formed on the tip end of the inner bushing tube
35
is snap-fit or otherwise interlocked with an annular recessed portion (not shown) formed continuously with a closed end portion (lower end portion in
FIG. 5
) of the axial hole
37
A. The inner bushing tube
35
has an axial slit
35
B extending at least across the locking projection
35
A so as to facilitate elastic deformation of the locking projection
35
A when the locking projection
35
A is forced into the axial hole
37
A of the outer bushing tube
37
.
In the manufacture of the top chain
31
, a roller
40
is rotatably mounted on the outer bushing tube
37
, as shown in
FIG. 5
, before the inner bushing tube
35
is fitted in the outer bushing tube
37
to complete the link assembly
38
. The top plate
32
and the link assembly
38
are then connected together by a metallic connector pin
41
. A top chain
31
is thus formed. In the top chain
31
, the base chain
33
connected with the link assembly
38
constitutes an offset chain. The top plate
32
and the upper link
34
are integrally molded of a synthetic resin. Alternatively, the upper link
34
may be firmly fitted between parallel spaced locking projections (not shown) formed on the undersurface of the top plate
32
in either case, the upper link
34
and the top plate
32
are firmly connected together against separation. In
FIGS. 3
to
5
, reference characters
32
A,
34
A and
36
A denote pin holes for receiving therein the metallic connector pin
41
.
FIG. 6
shows in perspective view a part of the conventional bush type top chain. This top chain is substantially the same as the roller type top chain
31
previously described, with the exception that it does not have a roller. In the bush type ton chain, a link assembly having a bushing portion
39
is connected to a top plate
32
by a connector pin
41
. The bushing portion
39
has a separable structure composed of inner and outer bushing tubes assembled together in the same manner as described above. The bushing portion
39
may be formed integrally with upper and lower links
34
,
36
.
As a conveyor chain, a generally known bush chain is used. The bush chain (not shown) comprises a series of link assemblies each having two inner links connected together by two bushings formed integrally therewith, and a series of sets of outer links arranged alternately with the link assemblies and articulately connected to the link assemblies by means of connector pins extending through the bushings. In one form, each of the link assemblies may be molded from a synthetic resin into an one-piece or unitary structure, and the outer links may be made of metal and disposed on the opposite outer sides of the link assembly so as to form a chain.
In the conventional roller type top chain, the upper link
34
and the lower link
36
are structurally independent from each other, and the bushing portion has a separable structure composed of an inner bushing tube
35
and an outer bushing tube
37
. The inner and outer bushing tubes
35
,
37
are engaged together merely by an interlocking engagement between the locking projection
35
A formed on the tip end of the Inner bushing tube
35
and a recessed portion (not shown) formed continuously with the lower end portion of the axial hole
37
A of the outer bushing tube
37
. The interlocking engagement between the inner and outer bushing tubes
35
,
37
may be released, so that the conventional roller type top chain is inferior in strength and rigidity of the bush portion to a chain having link assemblies each formed of two links connected together by two bushings formed integrally therewith. Accordingly, when the conventional roller type top chain is subjected to a great tensile force, the bushing portion may be damaged, resulting in reduction of the service life of the top chain. Another problem is that when a great tensile force is applied to the top chain, the upper and lower links
34
,
36
of each link assembly
38
tend to spread or move apart in vertical direction about the bushing portion
35
,
37
, and the amount of deformation of the top chain in the vertical direction increases with spreading of the links
34
,
36
, accordingly. Since the direction of spreading movement of the upper and lower links
34
,
36
substantially coincides with the axial direction of the connector pin
41
, removal of the connector pin is likely to occur, which may cause accidental disassembly of the top chain.
To deal with the foregoing problems, attempts have been made to form two links and a single bushing integrally with each other to form a single link assembly or to form two links and two bushings integrally with each other to form a single link assembly. However, the link assemblies thus formed make it impossible to mount a roller on the bushing portion.
The conventional bush type top chain is generally used with a sprocket disposed on each corner portion of a circular path of the chain. The sprocket and parts required to install the sprocket make the bush type top chain complicated in construction. Additionally, the bush type top chain requires a larger installation space than the roller type top chain because the roller type top chain can be guided only by horizontal rails without using sprockets. In view of the space requirement, horizontal guide rails disposed at a corner portion may be used with the bush type top chain. However, as opposed to rolling contact achieved between the roller type top chain and the horizontal guide rail, sliding contact achieved between the bush type top chain and the horizontal guide rail creates a greater frictional resistance, and the tensile force acting on the bush type top chain increases accordingly.
SUMMARY OF THE INVENTION
It is an object of the present invention to provide a roller which is capable of being mounted on a link assembly of a strong and rigid one-piece structure composed of two links and one or more bushing members formed integrally with the links.
Another object of the present invention is to provide a chain which is highly resistant against damage even when subjected to a great tensile force, has a roller capable of being mounted on a bushing portion with utmost ease, and can be manufactured with improved efficiency.
In one aspect, the present invention seeks to provide a roller for
Murakami Yoshihiro
Shibayama Katsutoshi
Tanabe Minoru
Howson & Howson
Tsubakimoto Chain Co.
Valenza Joseph E.
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