Conveyors: power-driven – Conveyor section – Endless conveyor
Reexamination Certificate
2000-02-23
2001-10-30
Ellis, Christopher P. (Department: 3651)
Conveyors: power-driven
Conveyor section
Endless conveyor
Reexamination Certificate
active
06308825
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a plastic conveyor chain wherein a plurality of plastic link elements are connected with each other by connecting pins extending through pin holes in the link elements.
2. Description of the Related Art
In this type of plastic conveyor chain, it is a conventional practice to provide a retainer device for normally retaining the connecting pins in the pin hole and preventing them from being unintentionally removed from the pin holes, so that they can be readily disengaged from the pin holes whenever necessary. To this end, for example, the conveyor chain is provided with plugs each having a plurality of deformable legs which are forcedly driven axially into the pin hole and engaged with a recess in the inner peripheral surface of the pin hole.
However, in order to remove the connecting pins from the pin holes, it is necessary to temporarily remove the plugs from the pin holes in advance. Not only is the removal of the plugs from the pin holes troublesome and time-consuming, but also the plugs are lost quite frequently. When the plug is lost, the plug is often mixed with articles to be transferred by the conveyor chain.
SUMMARY OF THE INVENTION
It is therefore a primary object of the present invention to provide an improved plastic conveyor chain that eliminates the above-mentioned drawbacks of the prior art.
It is a specific object of the present invention to provide an improved plastic conveyor chain including a plug which assures a smooth side sliding movement of the link elements in operation of the conveyor chain.
It is another object of the present invention to provide an improved plastic conveyor chain including a plug which positively prevents undesired disengagement of the connecting pin from the pin hole, while allowing the connecting pins to be simply and quickly disengaged form the pin hole whenever necessary.
It is another object of the present invention to provide an improved plastic conveyor chain including a plug which is simple in structure, easy to use, superior in durability, and less expensive to produce.
These and other objects and advantages can be attained by the present invention which provides a conveyor chain comprising a plurality of plastic link elements connected with each other by connecting pins extending through respective pin holes in the link elements, and retainer means for retaining the connecting pins in the pin holes.
According to the present invention, the retainer means comprises a recess formed in each chain link element in its side surface at a location adjacent to the pin hole, and a communication hole formed in each chain link element for communicating the recess with the pin hole. The retainer means further comprises a plug that is accommodated in the recess so as to be movable toward and away from the pin hole. The plug has a proximal end which is slidably movable in the recess, and a distal end which is inserted into the communication hole such that the distal end is moved into, and retracted from the pin hole as the proximal end is moved in the recess toward and away from the pin hole.
In the conveyor chain according to the present invention, the plug of the retainer means is positively retained in the recess of the link element and serves to normally prevent an unintended axial withdrawal of the connecting pin from the pin hole, and the plug is effectively prevented from being lost without inhibiting a smooth side sliding movement of the link elements in operation of the conveyor chain. Further, only by slidingly moving the plug within the recess toward and away from the pin hole, it is possible to simply and promptly effect a changeover of the conveyor chain between a mode in which the connecting pin can be positively retained in the pin hole and another mode in which the connecting pin can be removed therefrom. The retainer means is functionally advantageous, easy to use, substantially free from troubles in operation, suitable for mass-production and inexpensive.
Advantageously, the conveyor chain according to the present invention further comprises lock means for normally retaining the plug in a lock position in which the distal end of the plug is situated in the pin hole. Thus, the plug is normally prevented from being moved away from the pin hole even when vibrations or external forces are applied to the chain during the operation, thereby positively preventing an unintended axial withdrawal of the connecting pin out of the pin hole.
In this instance, the lock means may comprise projections formed on opposite side surfaces of the plug and recess, wherein the projections ride over each other as the plug is slidingly moved into, and from the lock position. Such arrangement of the lock means is simple in structure and easy to produce, and does not essentially increase the cost.
Advantageously, the proximal end and the distal end of the plug are in the form of a base part and an extension, respectively. In this instance, the base part may be formed with a slit at location adjacent to the projection, for affording a flexibility to the base part of the plug such that it can be resiliently deformed. The deformability of the base part as afforded by the slit ensures that the plug can be readily installed into the corresponding recess in the base part, and that the projections on the opposite side surfaces of the plug and recess are allowed to smoothly ride over the other as the plug is slidingly moved toward and away from each other.
Preferably, the base part of the plug is provided with projection or projections on upper and lower surfaces thereof, which can be maintained in engagement with corresponding edges of the recess. In this instance, after the plug has been installed into the recess, the projections in engagement with the edges of the recess serve to retain the plug in place, thereby positively preventing an unintended removal of the plug out of the recess through its front opening.
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An English Language abstract of JP 11-314722.
Bower Kenneth W
Ellis Christopher P.
Greenblum & Bernstein P.L.C.
Yamakyu Chain Co., Ltd.
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