Conveyors: power-driven – Conveyor section – Endless conveyor
Reexamination Certificate
1999-05-28
2001-04-10
Valenza, Joseph E. (Department: 3651)
Conveyors: power-driven
Conveyor section
Endless conveyor
C198S851000
Reexamination Certificate
active
06213292
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to a molded conveyor chain having number of link plates of synthetic resin pivotally connected together by connecting pine and driven by sprockets for conveyance of delicate or easy-to-break articles in the electric, electronic, food-processing or pharmaceutical industry.
2. Prior Art
Various molded conveyor chains having a number of link plates of synthetic resin connected together by connecting pins are known. As shown in
FIG. 11
, the connecting pins of the conventional molded conveyor chains have a flat portion
51
on its circumferential surface, and two projections
52
,
52
formed on the flat portion
51
at positions equidistant from the center of the connecting pin
50
. Tn the assembled Plate of the conveyor chain as shown in
FIG. 12
, a barrel end of one link plate
60
and an open end of the adjacent link plate
60
are pivotally connected by one of the connecting pins
50
. Each of the projections
52
,
52
of the connecting pin
50
has an outer edge engaged with an inner surface of one of two hinges at the open end of the link plate
60
, and opposite end portions of the connecting pin
50
are located inside two aligned pin holes
61
,
61
of the hinges of the link plate
60
. The connecting pin
50
is received in a bush hole
62
formed in a hinge at the barrel end of the link plate
60
with a clearance therebetween. Sliding engagement between the circumferential surface of the connecting pin
50
and the bush hole
62
in the link plate
60
enables the conveyor chain to bend or flex about the axis of the connecting pin
50
.
The illustrated conventional molded conveyor chain has various drawbacks as enumerated below.
(1) The opposite end portions of the connecting pin
50
have a length Y set to be smaller than the width X of each hinge of the link plate
60
, as shown in FIG.
12
. Accordingly, when the operator attempts to insert the connecting pin
50
alternately into the pin holes
61
and the bush hole
62
to pivotally connect two adjacent link plates
60
,
60
, the forward movement of the connecting pin
50
is arrested when a loading one of the projections
52
comes into engagement with an outer surface of one of the hinges of one link plate
60
. To cope with this problem, the operator is forced to hammer the trailing end of the connecting pin
50
while gripping the two link plates in such a manner as to maintain accurate alignment between the pin holes and the bush hole. Such link-plate joining operation is tedious and time consuming and exerts a great load on the operator. Furthermore, when the two link plates
60
are to be detached, the connecting pin
50
is axially driven with a hammer until two projections
52
move past the pin hole
61
which is located at the open end of the link plate
50
. This means that a stroke Z of hammering the connecting pin
50
to remove the connecting pin
50
from the two adjacent link plates
60
,
60
is substantially equal to the length of the connecting pin
50
. Such a large hammering stroke considerably lowers the efficiency of the link-plate detaching. A conveyor chain disassembling work also encounter with the same problem because this work involves the connecting pin detaching operation.
(2) In the case where the conveyor chain is automatically assembled on a special automatic assembling machine, the positions of the projections
52
,
52
on each connecting pin
50
are precisely controlled in such a manner that the projections
52
are in engagement with the opposed inner surfaces of two hinges of each link plate
60
. It may occur, however, that when opposite ends of the conveyor chain are manually joined together to set the conveyor chain on a conveyor frame, the connecting pin
50
is driven either excessively or insufficiently. In this instance, one of the projections
52
of the connecting pin
50
is caught or arrested within a corresponding one of the pin holes
61
of the link plate
60
. Due to a stress exerted from the projection
52
to the peripheral wall of the pin hole
61
, the hinge having the thus stressed connecting pin hole tends to break while the conveyor chain is running. This will cause a downtime of the conveyor chain.
SUMMARY OF THE INVENTION
It is accordingly an object of this invention to provide a molded conveyor chain having structural features which enable easy and reliable joining and separation of the conveyor chain to facilitate assembling and disassembling of the conveyor chain which is required at the initial setting on a conveyor frame and which may become necessary for subsequent maintenance of the conveyor chain.
Another object of the present invention is to provide a molded conveyor chain which is capable of smoothly conveying delicate or easy-to-break articles in the electric, electronic, food-processing, or pharmaceutical industry.
In one preferred form of the present invention, a molded conveyor chain includes a number of link plates molded of synthetic resin and pivotally connected together by connecting pins. Each of the link plates has a leading end edge, a trailing end edge opposite to the leading end edge, a plurality of aligned bush holes formed at intervals along the trailing end edge, and a plurality of aligned pin holes formed at intervals along the leading end edge. The connecting pin is inserted alternately into the pin holes in one of the link plates and the bush holes in the adjacent link plate to pivotally connect said one link plate and the adjacent link plate. Each of the connecting pins has a radial locking projection to prevent the connecting pin from displacing off said one link plate and the adjacent link plate. The locking projection is located closer to one end of the connecting pin than to a longitudinal central portion of the connecting pin.
Preferably, each of the connecting pins further has a flange-like stopper formed integrally with an end face of said one end of the connecting pin. The flange-like stopper is engaged with one of opposite sidewalls of said one link plate to position the locking projection such that the locking projection is received inside one of the bush holes in the adjacent link plate. Said one sidewall may have a recess for receiving therein the flange-like stopper of the connecting pin. It is preferable that the flange-like stopper has a beveled inner surface, and the recess has an outer end flared to form a space between a peripheral wall of the recess and the flange-like stopper for accepting insertion of a tip end of a screwdriver into the recess such that the tip end of the screwdriver is received in a space defined between a bottom surface of the recess and the beveled inner surface of the flange-like stopper.
The connecting pins have a non-circular cross section, such as a D shape. The pin holes has a cross section complementary to the cross section of the connecting pins. Thus, the connecting pins cannot rotate relative to the pin holes. The D-shaped pin holes are arranged with flat surface portions of the respective peripheral walls facing forward of the conveyor chain.
The bush holes are circular holes having an inside diameter slightly greater than the outside diameter of the connecting pins. The connecting pin slidably received in the bush holes allow the adjacent link plates to pivot or turn relative to each other about the axis of the connecting pin.
The locking projection is formed on a flat surface portion of the D-shaped connecting pin. The maximum height of the locking projection is determined such that the projection is located inside a circular cylinder drawn by a circumferential surface of the connecting pin. Thus, the connecting pin can be inserted into and removed from the two adjacent link plates without damaging peripheral walls of the bush holes.
In another preferred form of the invention, a molded conveyor chain includes a number of link plates molded of synthetic resin and pivotally connected together by connecting pins. Each of the link plates has a leading end edge, a trailing end edge opposite
Ishii Takashi
Murakami Yoshihiro
Shibayama Katsutoshi
Takahashi Toshio
Dann Dorfman Herrell and Skillman
Sharma Rashmi
Skillman Henry H.
Tsubakimoto Chain Co.
Valenza Joseph E.
LandOfFree
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