Conveyors: power-driven – Conveyor section – Endless conveyor
Reexamination Certificate
2001-12-06
2002-12-03
Ellis, Christopher P. (Department: 3651)
Conveyors: power-driven
Conveyor section
Endless conveyor
C227S058000, C227S059000, C227S060000, C227S061000, C029S432100, C474S253000, C474S255000, C474S257000
Reexamination Certificate
active
06488144
ABSTRACT:
FIELD OF THE INVENTION
The invention relates to fasteners for splicing ends of conveyor belts together and applicators therefor and, more particularly, to conveyor belt fasteners having rivets pre-inserted thereto and an apparatus and method for securing pre-inserted rivet fasteners to belt ends.
BACKGROUND OF THE INVENTION
To join two belt ends together, mechanical belt fasteners are typically used either of the hinged type where the individual fasteners have upper and lower plates joined by arcuate loops for mating with the loops of identical hinged fasteners on other belt ends or the solid plate type where the upper and lower plates span the joint between the two belt ends to be spliced together. In both cases, the plates have apertures therein that are aligned when clamped on respective upper and lower surfaces of the belts so that fastener members, e.g. rivets, staples, can be installed through the apertures and the belt for securing the belt fasteners to the belt ends. Conveyor belts having these types of splices in place can be used in a wide variety of applications depending on the materials being conveyed and the stresses applied to the splice during conveyor belt operations.
To assist in installation of rivets to belt fasteners with the rivets extending through the carcass of the conveyor belt, pilot nails have been utilized attached to a lower, hollow end portion of the rivet, such as shown in U.S. Pat. No. 3,913,180, commonly assigned to the assignee of the present invention. The pilot nails fit through an aperture in the upper plate and pierce the underlying upper surface of the belt and lead the attached rivets through the belt until the lower, hollow end of the rivet projects through the lower plate aperture for being upset thereat to form a flared rivet head at the bottom of the rivet shaft. After the bottom rivet head is formed, the nail is released from being held in the hollow end of the rivet and is caught in the applicator tool. This creates the problem of what to do with the mess created by the separated pilot nails as well as complicating the application process.
There have been various application tools developed for installing riveted belt fasteners to belt ends. Applicants' assignee herein has tools for users that allow individual rivet and pilot nails assemblies to be driven as well as those that can gang drive several of these assemblies simultaneously such as for larger rivet fasteners that utilize several rivets for an individual fastener. The present invention is not limited to the number of rivets used with a fastener. An applicator tool for rivet fasteners is shown in applicants assignee's co-pending U.S. patent application, Ser. No. 09/177,238, whose disclosure is incorporated as if reproduced in its entirety herein. In each instance, the rivets and nails have to be loaded into a shaft of the tool aligned over the apertures of the plates for driving therethrough. This can create undesirable delays in the installation process for splicing belt ends using rivet belt fasteners.
For splice strength using riveted fasteners, it is very important that the heads of the rivet are properly formed. Further, in applications where the conveyor belts are used for agricultural equipment such as round hay balers and net wrapping hay balers, it is very important to maintain a low profile for the fastener secured on the belt end. To this end, the rivet heads should be seated in the recessed apertures of the plates so they do not project over the top thereof as otherwise the projecting portions of the head may catch or snag on the net wrapping about the bales. These agricultural applications also tend to be very abusive on the splice in terms of the high-tension forces they are exposed to and the relatively small diameter pulleys, e.g. 3 to 3.5 inches in diameter, about which they must travel. To make the fasteners stronger, larger, thicker plates can be utilized along with greater numbers of rivets. However, this raises the costs for the fastener and is a detriment to their ability to travel about small sized pulleys. Thus, one option is to reduce the size of the plate by keeping it relatively thick and lowering the number of rivets used therewith. In this instance, proper forming of rivet heads becomes extremely important as there are fewer rivets holding the plates onto the belt ends.
Accordingly, there is a need for a rivet fastener that can be installed to belt ends with greater ease and speed, and an application tool for this purpose. Further, a rivet fastener that is relatively small in size but provides relatively high strength is needed.
SUMMARY OF THE INVENTION
In accordance with the present invention, a fastener for splicing ends of conveyor belts together is provided having a rivet that is pre-inserted to provide speed and ease in installation. Although one rivet per fastener is illustrated and described, one or more rivets can be pre-inserted on an individual fastener in accordance with the teachings of the invention herein. In the context of the present invention, the term “pre-inserted” refers to the rivet being held in the plate aperture so that the rivet is carried by the plate before the installation process commences. The pre-inserted rivet preferably is held by an interference fit in the plate aperture as described hereinafter, although the rivet could be held by other mechanisms such as by an adhesive between the rivet and aperture.
As mentioned above, the rivet can be held in an aperture of the upper plate by an interference fit at the lower end thereof. Preferably, the interference fit is achieved by knurling of the lower end portion of the rivet shaft to create raised interference portions or ridges integral therewith that are sized to be in an interference fit in the upper plate aperture. The remainder of the shaft can be sized to provide clearance between it and the aperture. In this manner, during driving of the rivet, after the interference portions clear the upper plate aperture, the rivet is no longer in press-fitting engagement therewith. This avoids scraping of the rivet shaft by the edges about the upper plate aperture minimizing damage to the rivet body and so that the softer metal material of the rivet is not pushed up under the head preformed at the upper end thereof as might otherwise prevent the upper rivet head from seating fully in the recessed aperture of the upper plate. Further, with the upper rivet head properly seated in the upper plate recessed aperture, the amount of material at the lower end of the rivet for being upset is sufficient for proper forming of the lower rivet head to increase the holding strength of the rivet. In a preferred form where only a single rivet is used to secure the fastener to the belt, the ability to properly form and seat the rivet heads for providing good holding power is of particular importance.
Accordingly, and in one form of the invention, a fastener for splicing ends of conveyor belts together is provided including upper and lower plates for being clamped on respective upper and lower surfaces of the conveyor belt. Apertures of the plates are generally aligned with each other with the plates clamped on the belt. A rivet is provided having a shaft with an end portion thereof held in an upright, pre-inserted position in the aperture of the upper plate prior to riveting of the fastener to the belt end. Interference portions integral with the shaft end portion are sized to be in an interference fit in the upper plate aperture. Thus, the present fastener avoids the need for loading rivets into a shaft of an applicator tool speeding installation time.
The interference portions can include raised ridges having an interference diameter larger than the aperture diameter. Preferably, the rivet shaft has a clearance diameter and includes a preformed enlarged head at one end thereof. The interference diameter of the raised ridges is larger than the clearance diameter so that after the held rivet portion is driven through the upper plate aperture, the shaft clears the aperture to minim
Mitas Gary E.
Vogrig Joseph C.
Winkelman John H.
Deuble Mark A.
Fitch Even Tabin & Flannery
Flexible Steel Lacing Company
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