Conveyors: power-driven – Conveyor section – Endless conveyor
Reexamination Certificate
1999-07-29
2001-02-20
Bidwell, James R. (Department: 3651)
Conveyors: power-driven
Conveyor section
Endless conveyor
C198S850000, C198S493000
Reexamination Certificate
active
06189686
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates generally to a slat conveyor chain for conveying articles while a treatment liquid such as soap-and-water solution is supplied onto the load-bearing upper surface of the slat conveyor chain. More particularly, this invention relates to such a slat conveyor chain which is particularly suitable for conveyance of PET (polyethylene terephthalate) bottles, cans or the like containers for medicines and beverages.
2. Description of the Related Art
Conventionally, a slat conveyor chain formed from synthetic resin is used for conveyance of PET bottles, cans or the like containers for medicines and beverages.
As shown in
FIGS. 8A and 8B
, the conventional synthetic resin slat conveyor chain includes a series of slats
1
and chain links
2
formed integrally with respective undersides of the slats
1
and articulated by pins
3
at their reinforcement ribs to form an endless chain. The slats
1
are made from an engineering plastics such as polyacetal resin. The pins
3
are formed from stainless steel or engineering plastics.
When used in various production lines, the conventional slot conveyor chain is looped around a pair of horizontally spaced drive and driven sprockets S
1
, S
2
and is driven by the drive sprocket
1
to transport articles W such as beverage containers carried on respective load-bearing upper surfaces of the slats
1
while respective undersides of the slats
1
are stably guided by a pair of laterally spaced guide rails R, R (
FIG. 9
) located on opposite sides of the links
3
.
To protect the beverage containers W against an abrasive mark or scar during conveyance on the load-bearing upper surfaces of the slats
1
, and to secure stable conveyance of the containers W with minimum abrasive wear of the chain, a soap-and-water solution is showered from a nozzle N onto the load-bearing upper surfaces of the slats
1
to lower the friction coefficient of the load-bearing upper surfaces and to lubricate the chain. The nozzle N is disposed above the slat conveyor chain at a position near the driven sprocket S
2
, as shown in FIG.
10
.
The PET bottles, for which demand has increased in recent years, are relatively soft. Accordingly, when many such relatively soft PET bottles are accumulated on the synthetic resin slat conveyor chain during conveyance, the accumulated PET bottles are likely to deformed or otherwise damaged due to a large line pressure (conveyance resistance) resulting from an increased frictional resistance produced between the load-bearing upper surfaces of the slats
1
and bottom surfaces of the PET bottles.
Especially for those PET bottles having a bottom wall of petaloid shape, stable conveyance is almost impossible because the PET bottles are likely to come down or fall during conveyance due to their very unstable petaloid-shaped bottom walls. To deal with this problem, the amount of soap-and-water solution showered onto to the load-bearing upper surfaces of the slats is increased to a level greater than as used for conveyance of beverage cans. However, due to the increased supply of soap-and-water solution, the slat conveyor chain becomes excessively wet and the soap-and-water solution stays on part of the slat conveyor without draining. Excessive soap-and-water solution, which may stay on the load-bearing upper surfaces of the slats or between the undersides of the slats and the guide rails, scatters around a conveyor frame and thus causes contamination of working environment around the conveyor frame. Additionally, the scattered soap-and-water solution may cause corrosion of bearings fitted around drive and drive shafts of a chain drive mechanism and corrosion of a speed reducer of the chain drive unit, resulting in considerable shortening of the service life of the chain drive mechanism. These problems also occur when the articles to be conveyed are bins or when vast amounts of washing liquid are used for washing articles while being conveyed.
SUMMARY OF THE INVENTION
With the foregoing problems in view, it is an object of the present invention to provide a slat chain conveyor which can smoothly discharge an excess amount of treatment liquid, such as lubricating liquid or washing liquid, from an upper surface to the underside of each slat to secure smooth and stable conveyance of articles while keeping the surrounding working environment against contamination with the treatment liquid and also preventing reduction of service life of a chain drive unit due to corrosion of parts with the treatment liquid.
To attain the foregoing object, the present invention provides a slat conveyor chain for a slat conveyor including a sprocket for driving the slat conveyor chain to travel in a direction along a guide rail of the slat conveyor for conveyance of articles while a treatment liquid is supplied onto an upper surface of the slat conveyor chain. The slat conveyor chain comprises: a series of slats each having a multiplicity of drain holes extending from an upper surface to an underside of each slat for the passage therethrough of the treatment liquid, the drain holes being distributed in a desired pattern; and a series of links formed integrally with the respective undersides of the slats and articulately connected together by pins to form a flexible endless chain driven by the sprocket. The underside of the slats each have a sliding surface portion facing the guide rail, and at least one discharge groove formed in the sliding surface portion and connected to at least one of the drain holes. The treatment liquid supplied onto the upper surface of the slat conveyor chain for smooth and damage-free conveyance of the articles is smoothly discharged from the discharging groove through said at least one drain hole without scatting around a frame of the slat conveyor. With this discharging of the treatment liquid, bearings and a speed reducer of a chain drive mechanism are protected against corrosion. The slat conveyor chain can, therefore, operate smoothly over a long period of use while keeping the surrounding working environment against contamination with the treatment liquid.
Preferably, the drain holes each have a flared end opening at the upper surface of each slat, so that the excessive treatment liquid is smoothly introduced into the drain holes.
The discharge groove may extend in a direction parallel to the direction of travel of the slat conveyor chain. In this instance, the pattern of the drain holes is preferably such that a plurality of drain holes arranged in a row in a direction parallel to the direction of travel of the slat conveyor chain are all connected to the discharge groove.
As an alternative, the discharge groove may extend obliquely from the vicinity of an outer side edge of each slat to the associated link in a direction opposite to the direction of travel of the slat conveyor chain. The obliquely extending discharge groove is particularly suitable when the treatment liquid is a lubricating liquid because a pin-joint portion between two adjacent links can be lubricated with the lubricating liquid. The pattern of the drain holes is preferably such that a plurality of drain holes arranged in a row oblique to the direction of travel of the slat conveyor chain are all connected to the discharge groove.
Preferably, the sliding surface portion of each slat is partly spaced by a distance from the guide rail at a leading end portion and a trailing end portion of each slat. This arrangement achieves smooth delivery of the treatment liquid from the discharge groove in one slat to the discharge groove in a subsequent slat without causing spouting of the treatment liquid over the upper surface of the slat conveyor chain through a joint clearance between the adjacent slats. The distance between the sliding surface portion and the guide rail is preferably at lest equal to a depth of the discharge groove. Preferably, the leading end portion and the trailing end portion are complemental in shape, and the trailing end portion of the one slat is interdigitated with
Murakami Yoshihiro
Shibayama Katsutoshi
Bidwell James R.
Dann Dorfman Herrell and Skillman, P.C.
Skillman Henry H.
Tsubakimoto Chain Co.
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