Conveyors: power-driven – Conveyor section – Endless conveyor
Reexamination Certificate
2001-01-16
2003-02-25
Hess, Douglas (Department: 3651)
Conveyors: power-driven
Conveyor section
Endless conveyor
C198S842000
Reexamination Certificate
active
06523679
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates generally to belt-type conveyors, and more particularly to a modular sanitary conveyor having removable wear strips that is suitable for use in applications in which strict sanitary standards must be met, such as the food industry.
2. Brief Description of the Prior Art
Conveyors are typically used for the transport of many articles including produce and food products. Sanitation is a primary consideration in the food processing industry, and the conveyors must be maintained in a clean and hygienic condition to meet basic sanitary standards. Some regulations require that the food conveyor be taken apart and completely cleaned every twenty-four hours. Thus, cleaning of the conveyors requires considerable down-time of the equipment.
When conventional conveyors with endless belts are used, it is usually very time-consuming to clean the conveyors because the inside of the bell, the end rollers and all other conveyor parts covered by the belt are very difficult or impossible to clean in an acceptable way. In some instances the conveyors have ledges, pockets, threads, nuts and bolts, and various surfaces which accumulate liquids and/or debris from the food being processed, and some portions of the conveyors may be difficult to access. In other instances the conveyors and belt supporting wear strips have flat surfaces that overlap and form laminations which tend to accumulate liquids and/or debris from the food being processed.
A typical conveyor using modular or “table top” type chain typically includes a conveyor support to support the chain. In some prior art conveyors the support way is provided with replaceable wear strips of low friction material so that, as the wear strips wear out due to the friction involved as the chain passes over the strips, the strips are easily replaced. Some prior art conveyors employ a pair of round or rectangular wear strips which wind from one end of the conveyor support way to the other in a “serpentine” configuration. In order to maintain the wear strips in the desired serpentine configuration, the wear strips have typically been bolted or otherwise fastened to cross members disposed in spaced relationship along the length of the return way.
Although bolting serpentine wear strips to cross members has proven to be useful where the wear strips are formed of material having a low thermal coefficient expansion, the bolting technique is not particularly useful where the wear strip is composed of a material having a high thermal coefficient of expansion, such as ultra-high molecular weight or “UHMW” polyethylene. This is because when a strip of material fixedly secured between two stationary members becomes heated, the resultant expansion of material will cause an increased lateral curvature of the serpentine wear strip or a vertical buckling of the serpentine wear strip thereby reducing desired support of the chain along its full length. Thus, plastic materials with high thermal coefficients of expansion which are highly suitable for use as wear strips, such as UHMW polyethylene, are not commonly used as serpentine wear strips.
The bolting technique of installing wear strips require strips with bolt holes at precise locations along their length, and each wear strip must be individually bolted to each cross member, and unbolted to replace and/or clean. Thus, the bolted wear strips require a threaded bore in the surface that supports them, and they have holes and flat surfaces that overlap the support surface and form laminations which tend to accumulate liquids and/or debris from the food being processed.
There are several patents that disclose various sanitary conveyors and conveyor belt wear strip apparatus.
Fleckenstein et al, U.S. Pat. No. 3,993,185 discloses a sanitary conveyor for use in strict sanitary environments that has a flat or cleated conveyor belt which can be horizontally or angularly positioned as required wherein the belt passes over a smooth, continuous planar bed. The invention further includes a belt tensioning and slack off feature that enables the conveyor, and both sides of the belt to be cleaned without disassembly or removal of the belt from the conveyor.
Grimes et al, U.S. Pat. No. 3,964,800 discloses a wear strip for conveyor chains comprising a flat upper wear member having at least two spaced-apart holes therethrough for the reception of screws or bolts, at least one linear support member joined to the underside of the wear member, and at least two base members joined to the underside of the wear member and having holes therethrough in registry with the holes through the wear member. Each of the holes in the wear member is preferably countersunk on the upper surface.
Bode et al, U.S. Pat. No. 4,989,723 discloses an endless plastic conveyor belt assembled of plastic modules having relatively open pintle slots receiving respective connecting rods. The conveyor frame includes a plurality of straight longitudinally extending, transversally spaced rails having wear surfaces which are plated with wear strips made of a synthetic plastic material and removably mounted in place using button-headed protrusions integrally provided on the undersides of the wear strips near their leading and trailing ends. The button headed protrusions near the leading end snaps into a round hole through the respective rail, and the button headed protrusions near the trailing end snap into a longitudinally elongated slot through the rail.
Butt, U.S. Pat. No. 4,325,480 discloses a conveyor support way for a table top chain comprising a series of alternating first and second transverse cross members. Each of the first cross members contains a first pair of open top spaces and each of said second cross members contains a second pair of open top spaces, the first pair of spaces being disposed laterally inwardly of the second pair of spaces. A pair of serpentine wear strips are provided to support the chain, each extending along the length of the series of cross members, alternately through an associated one of the first cross member spaces and through an associated one of the second cross member spaces. Each wear strip is axially slidably and removably mounted on the series of cross members.
Ledginham et al, U.S. Pat. No. 5,190,145 discloses a conveyor system which utilizes U-shaped mounting clips having U-shaped arm ends which are snapped onto cross members between frame portions of the conveyor system, and are shaped to have snapped therein wear strips that are oriented in serpentine manner as viewed from above. Portions of the wear strips are maintained spaced apart by spacers mounted onto the rods and by spacer pins that are provided on the mounting clips for association with each other or with side frames. Intermediate pinch clips, are provided to hold central regions of the wear strips close to each other, at regions where there are no cross members.
The present invention is distinguished over the prior art in general and these patents in particular by a modular sanitary conveyor which includes a longitudinal conveyor bed frame that is slidably received and supported on a support stand and a motor and clutch assembly that is slidably received and supported on the side of the frame. The frame has lateral side walls secured together by a series of cross members and has a serpentine support way for supporting belts and table top chains that is formed of individual wear strips that are installed, retained in place, and removed without the use of tools. Unitary bearings are slidably received in slots at each end of the side walls and rotatably support a drive sprocket shaft and an idler sprocket shaft having respective drive sprockets and idler sprockets slidably received thereon. All components can be easily and quickly disassembled for cleaning and reassembled without the use of special tools.
SUMMARY OF THE INVENTION
It is therefore an object of the present invention to provide a modular sanitary conveyor that is particularly useful in applications in which strict sanitary sta
Hess Douglas
Roddy Kenneth A.
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