Conveyors: power-driven – Conveyor section – Having means to enhance the friction or adherence between...
Reexamination Certificate
2001-10-02
2002-10-22
Bidwell, James R. (Department: 3651)
Conveyors: power-driven
Conveyor section
Having means to enhance the friction or adherence between...
C198S853000
Reexamination Certificate
active
06467610
ABSTRACT:
BACKGROUND
This invention relates generally to power-driven modular conveyor belts and, more specifically, to conveyor belts and modules with attachments retained by a connecting pin.
Because they do not corrode, are positively driven by sprockets, and are easy to repair, modular plastic conveyor belts are widely used to convey a variety of articles. Modular plastic conveyor belts are made up of molded plastic modular links, or belt modules, that can be arranged side by side to form a belt row of selectable width. Series of spaced-apart hinge eyes extending from the leading and trailing ends of the modules include aligned openings forming passageways to receive pivot rods, or hinge pins. The hinge eyes along one row interleave with the hinge eyes of an adjacent row. Hinge pins extending through the passageways join adjacent rows of modules together into a conveyor belt and form hinge joints at which the belt can articulate.
Many applications require a conveyor belt to transport articles along an inclined path. To prevent articles, especially bulk products, from sliding down the conveying surface of a belt as it traverses an incline or a decline, flights are often used. Typically, flights are in the form of rectangular plates extending perpendicularly from the conveying surface of a belt. Flights form walls past which conveyed articles cannot slide. In most modular plastic belts, flights are integrally molded as part of a belt module. Because the molds for simple flight designs are typically two-piece molds and relatively inexpensive, a manufacturer may be able to afford a different mold for each simple flight variation. But each time a new application calling for a flight revision arises, a new mold must be cut. Furthermore, flights with complex topologies can require expensive molds and molding techniques. For example, some applications, such as conveying fruits upward out of a liquid-filled vat, may demand drain holes through the flight. Molding the drain holes in an integral flighted module requires a complicated and much more expensive mold of three or more pieces. Thus, supplying a variety of flights of varying designs requires an extensive inventory of expensive molds.
Another shortcoming with integrally-molded flighted modules is that the width of the flight is typically coextensive with the width of the module base. When assembled side by side in the row of a conveyor belt, flighted modules have a seam between them. Longitudinal seams between belt modules across the width of a belt row significantly diminish the beam strength of the belt.
Cleanability is another important concern in many belt applications, especially in food handling applications. It is important to minimize the number of crevices and crannies that can harbor bacteria in a belt. But avoiding all trouble spots in a modular conveyor belt with its many pieces is impossible. One of the most troublesome areas is the hinge between belt rows. Unless precautions are taken, bacteria can reside along the hinge pin at the hinge eyes. That's why modular conveyor belts for conveying food products are usually designed with open hinges that expose a large percentage of the hinge pin. In this way, the hinges are easy to view and to clean by jet spraying, for instance. Food processors are experienced in cleaning belts and have developed further expertise in cleaning belt hinges.
Because integrally-molded flighted modules do not have gaps between the flight and the conveying surface, cleaning them is straightforward. But belt modules having detachable elements, such as flights, hold down tabs, and high-friction inserts, can present a cleaning problem. By providing hiding places for bacteria, the interfaces between the belt modules and the attachments require special attention. To clean the belt effectively for it to pass required inspections, a food processor may have to use a more complex cleaning system that can clean both hinges and attachment points. For this reason, detachable belt accessories are not so common in certain food applications.
Thus, there is a need for a modular conveyor belt that can be customized with a variety of attachments, as well as a conveyor belt with accessories that are easy to clean.
SUMMARY
These needs and others are satisfied by a modular conveyor belt embodying features of the invention. The conveyor belt is constructed of a series of rows of belt modules. Each row includes at least one module extending from a first end to a second end in the direction of belt travel. A first set of hinge eyes is disposed along the first end, and a second set of hinge eyes, along the second end. The rows are arranged end to end with the first set of hinge eyes of a row interleaved with the second set of hinge eyes of an adjacent row. Hinge pins disposed in aligned openings in the interleaved hinge eyes connect adjacent rows into a conveyor belt and form a hinge between adjacent rows. At least some of the modules are base modules that may include intermediate structure with upstanding members spaced apart across their widths. Aligned apertures are formed in the base modules, such as through the upstanding members. A belt attachment, such as a custom flight, has spaced apart connection members with aligned apertures. The connection members are arranged with the base modules, such as interleaved with the upstanding members. The apertures of both are aligned and form a passageway to receive a connecting pin that retains the belt attachment to the base module. In this way, a variety of custom attachments can be mounted on a conveyor belt.
Some custom attachments include a flight portion and a perforated flight portion for good drainage. To increase the beam strength of the belt, the belt can be constructed with the belt attachment spanning the seam between side-by-side base modules.
In other versions of the modular conveyor belt, second aligned apertures are formed in the upstanding members of the base modules and in the connection members of the attachments. These second aligned apertures form a second passageway through the interleaved upstanding members and connection members. A second connecting pin resides in this second passageway to constrain, with the first connecting pin, the attachment firmly to the base module.
In another version, the belt attachment includes stabilizing structure that interfits with the intermediate structure of the base modules. This interfit, in conjunction with the connecting pin, holds the belt attachment in place. The stabilizing structure can be realized, for example, as protrusions formed at the bottom of the connection members that mate with receptacles in the intermediate structure of the base modules. In yet another version, the connection members include shank portions with spacers extending from sides of the shank portions. The spacers prevent the attachment from sliding sideways along the connecting pin and help expose a large percentage of the connecting pin in the manner of an open belt hinge for easy cleaning and inspection.
Thus, a conveyor belt embodying features of the invention can be customized with a variety of attachments of different topologies, materials, or colors that are individually easier to mold than an integral module without sacrificing cleanability.
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Bidwell James R.
Cronvich James T.
The Laitram Corporation
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