Conveyors: power-driven – Convertible
Reexamination Certificate
1999-11-05
2001-08-07
Ellis, Christopher P. (Department: 3651)
Conveyors: power-driven
Convertible
C198S841000
Reexamination Certificate
active
06269939
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The invention relates to belt or chain conveyors and, more specifically, to means and methods for converting roller conveyors into belt or chain conveyors.
2. Description of Related Art
Roller conveyors are commonly used, especially in the package handling industry, to provide a solid conveying surface for a variety of materials. Typical roller conveyors include a steel, galvanized, or aluminum frame with parallel side walls. An array of cylindrical rollers is supported between the side walls. Spring-loaded shafts extending from the ends of the rollers rest in openings in the side walls spaced to provide standard roller centers, such as 1.5 inches or 2 inches and their multiples. The topmost portions of the rollers lie in a conveying plane. Packages or other products placed on the conveying plane span two or more rollers. In the simplest of roller conveyors, packages are transported by gravity when the conveying plane is inclined or by a push when the conveying plane is horizontal. The momentum of the packages contacting a roller causes the roller to rotate and transport the package to the adjacent downstream roller. In powered roller conveyors, a rubber or fabric belt frictionally drives one or more of the conveying rollers to transport packages. Because of their simple construction, roller conveyors are an inexpensive means for conveying packages.
But roller conveyors have shortcomings. First, the roller bearings wear over time, which causes a roller to roll less easily or to freeze completely. Second, the mounting holes for the roller can wallow out, which can cause the rollers to assume cocked orientations relative to each other and to the conveying plane. Third, as they age, roller conveyors can become noisy. Fourth, because passive horizontal roller conveyors depend on a push to get a package rolling, there is no guarantee that the package will make it to its destination without getting stranded.
To meet changing conveyance demands, motor-driven belt or chain conveyors often replace roller conveyors. Motor-driven belt conveyors are less noisy, avoid stranding packages, and are especially helpful in transporting high volumes of packages. Because the roller conveyor is already in place, using as much of it as possible to support the replacement belt conveyor is advantageous. In many cases, a belt is merely installed on the roller conveyor frame with the rollers acting as a carryway support for the belt. One problem with this solution is the noise generated by the belt bouncing up and down on the undulating and intermittent support surface provided by the rollers. For that reason, the rollers are often removed and replaced by a metal support structure positioned between and supported by the side walls of the roller conveyor frame. But it takes a lot of time and effort to remove the rollers and construct, fit, and install the support structure.
Clearly there is a need for a simple and quick way to convert a roller conveyor into a motor-driven belt or chain conveyor.
SUMMARY OF THE INVENTION
This need and others are satisfied by a conveyor conversion kit and associated conversion method having features of the invention. The conversion kit includes an attachment collar and an associated wearstrip. The attachment collar surrounds all or part of the circumference of a first roller of the original roller conveyor. The wearstrip extends outward from the attachment collar to overlie a group of consecutive rollers. The wearstrip is supported by the rollers. In an actual conversion, many attachment collars and associated wearstrips are mounted on the rollers to form a generally planar carryway bed to support a motor-driven conveyor belt in the former roller conveyor frame. In this way, a belt conveyor according to the invention is constructed.
In some versions of the conversion kit, the attachment collar surrounds only part of the circumference of the roller so that the collar may be slipped on or clipped on as a spring clip. In other versions, the attachment collar completely surrounds the roller. For example, the collar has a central bore contoured to match the circumference of the rollers and is installed by sliding over an end of the roller along its length. In other versions, the collar comprises two sections surrounding complementary portions of the roller circumference. The two sections may be separable at, for example, a hinge. A latch may be used in other versions to lock the collar in place on the roller. In another version, the attachment collar includes an attachment portion about the roller with a threaded hole through the attachment portion to admit a set screw that, when tightened, bears against the roller and prevents it from moving relative to the collar. In other versions, the collar includes a locking band, such as a hose clamp or a cable tie, or a lockable cuff or a spring clip to attach to the roller. For use especially with off-the-shelf metal-framed wearstrip, the collar is made of two halves with confronting notches that form a width-adjustable channel that squeezes against the metal-encased wearstrip to hold it fast when a fastener connecting the two halves is tightened.
The wearstrip in some versions is a rectangular length of material extending transverse to the roller axes in the direction of belt travel. Each wearstrip length is attached to, or integrally extends from, an attachment collar. In other versions, the wearstrip is in a zig-zag pattern with attachment collars at one or more of the vertices of the zig-zag pattern. In yet other versions, the wearstrip is a flat plate covering most of the width of the conveyor between the side walls. The flat plate is attached at various locations to attachment collars, such as one having a stem disposed between adjacent rollers and with first and second arms extending in opposite directions from the lower end of the stem to surround portions of the adjacent rollers. The top end of the stem attaches to the wearstrip, which is held down by the bifurcated attachment collar.
A method for converting a roller conveyor into a belt conveyor includes attaching collars to selected rollers of the roller conveyor, arranging wearstrip material that extends from or attaches to the collars in a pattern overlying and spanning consecutive rollers to form a conveyor bed of wearstrip material supported on the rollers, and installing a conveyor belt chain on the conveyor bed.
Thus, it is possible to take advantage of a roller conveyor already in place by attaching the elements of a conveyor conversion kit to a roller conveyor to convert it quickly into a less noisy belt conveyor without having to remove the rollers.
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Greve Christopher G.
Lapeyre Robert S.
Crawford Gene O.
Cronvich James T.
Ellis Christopher P.
The Laitram Corporation
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