Abstract:
A roller for a conveyor system is comprised of a body portion that is generally cylindrical and rotatable about a central axis. A first bearing surface is defined around the body portion. A second bearing surface is raised above the first bearing surface and is generally concentric to the first bearing surface, the second bearing surface being more resilient than the first bearing surface.

Description:
RELATED APPLICATIONS 
     This application claims the benefit of U.S. Provisional Application No. 60/816,542, filed Jun. 26, 2006, which is fully incorporated herein by reference. 
    
    
     FIELD OF THE INVENTION 
     The present invention relates generally to conveyor systems and, more particularly, to a roller assembly for a conveyor system. 
     BACKGROUND OF THE INVENTION 
     The present invention relates to a conveyor system and roller assembly that is particularly applicable for use in a multi-chamber washer and shall be described with reference thereto. It being understood, however, that a conveyor system or roller assembly according to the present invention may find advantageous application in other applications. 
     A multi-chamber washer is generally comprised of several different chambers that are aligned side-by-side. Each chamber has a specific purpose, such as washing, rinsing, or drying a load. 
     Objects washed within a multi-chamber washer are typically contained within an open basket or tray. A conveyor system is provided within the washer to move the basket or tray from one chamber to another. The conveyor system typically extends through the adjacent chambers within the washer to convey a basket or rack to the respective chambers. 
     Conveyor systems comprised of driven rollers have been used to convey the baskets or trays through a multi-chamber washer. One problem with such conveyor systems is maintaining a sufficient driving force between the baskets and the rollers. In this respect, different types of baskets may be used within the multi-chamber washers. Baskets having a base formed of plastic materials are often used in such washers to reduce noise during the conveying, i.e., indexing, of the baskets. Plastic material also makes it easier to control the friction coefficient between the baskets and the drive rollers. Other manufacturers form baskets of stainless steel material. Stainless steel racks are more easily cleaned during the washing process and are able to heat more quickly because of the higher coefficient of thermal conduction. 
     It is also known to form the conveyor rollers of a plastic or metal material. As indicated above, rollers formed of plastic material can provide a better coefficient of friction between the roller and the basket and, likewise, help reduce noise during the conveying, indexing process. However, as noted above, plastic rollers are more difficult to clean, as compared to metal rollers. Metal conveyor rollers are preferred because of the ability to clean such rollers during the washing process, as well as their durability. However, maintaining adequate driving force between a metal roller and a metal frame of a basket can be difficult, particularly in wet environments that would be encountered within the washer. Similarly, the friction coefficient between a metal roller and a metal basket will vary depending upon the weight of the basket and the articles therein. 
     The present invention overcomes these and other problems and provides a roller assembly for a conveyor system having improved frictional, driving characteristics. 
     SUMMARY OF THE INVENTION 
     In accordance with a preferred embodiment of the present invention, there is provided a conveyor roller for a conveyor system. The roller is comprised of a body portion that is generally cylindrical and rotatable about a central axis. A first bearing surface is defined around the body portion. A second bearing surface is raised above the first bearing surface and is generally concentric to the first bearing surface, the second bearing surface being more resilient than the first bearing surface. 
     In accordance with another aspect of the present invention there is provided a roller for a conveyor system in a multi-chamber washer, the conveyor system being operable to convey a rack along a path within the multi-chamber washer. The roller is comprised of an outer roller section that is generally cylindrical in shape with a planar inner surface having an annular grove formed therein. The groove defines an inner portion and an outer portion of the inner surface, the inner portion extending above said inner surface. An inner roller is section generally cylindrical in shape with a planar inner surface having an annular grove formed therein. The groove defines an inner portion and an outer portion of the inner surface, said inner portion extending above the inner surface. The inner portion of the inner roller is dimensioned to mate with the inner portion of the outer roller whereby the annular grove and the outer portion in the inner roller and the annular grove and the outer portion in the outer roller form an opening therebetween. A friction element is disposed between the outer roller and the inner roller. The friction element is dimensioned to be retained in the opening. The friction element is generally cylindrical in shape with a outer cylindrical portion having a diameter greater than an outer diameter of the outer roller and the inner roller such that the outer cylindrical portion extends above the outer diameter of the outer roller and the outer diameter of the inner roller, the friction element being formed of a resilient material. 
     An advantage of the present invention is a conveyor roller that can be used in multi-chamber washers for conveying metal or plastic baskets within the washer. 
     Another advantage is a conveyor roller as described above that is less likely to slip. 
     Another advantage of the present invention is a conveyor roller as described above having improved frictional contact with an article to be conveyed. 
     These and other advantages will become apparent from the following description of a preferred embodiment taken together with the accompanying drawings and the appended claims. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The invention may take physical form in certain parts and arrangement of parts, a preferred embodiment of which will be described in detail in the specification and illustrated in the accompanying drawings which form a part hereof, and wherein: 
         FIG. 1  is a perspective view of a multi-chamber washer; 
         FIG. 2  is a perspective view of a chamber within the multi-chamber washer shown in  FIG. 1 , illustrating a portion of a conveyor system; 
         FIG. 3  is a view taken along lines  3 - 3  of  FIG. 2 , showing one edge of a basket supported on a conveyor roller assembly; 
         FIG. 4  is an enlarged sectional view of the conveyor roller shown in  FIG. 3 ; and 
         FIG. 5  is an exploded view of a conveyor roller assembly. 
     
    
    
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS 
     Referring now to the drawings wherein the showings are for the purpose of illustrating a preferred embodiment of the invention only, and not for the purpose of limiting same,  FIG. 1  shows a multi-compartment washer  10 . 
     Washer  10  has a loading end  12  and an unloading end  14 . A loading platform  16  is provided at loading end  12  of washer  10 , and an unloading platform  18  is provided at unloading end  14  of washer  10 . Washer  10  includes an outer housing  22  that is generally rectangular in shape. In the embodiment shown, housing  22  has three access panels  24   a,    24   b,    24   c  to allow access to components of washer  10  within housing  22 . 
     A conveyor system  30  defines a path P through washer  10 . Conveyor system  30  is comprised of spaced-apart, first and second rows  32 A,  32 B of spaced-apart conveyor roller assembly  60  (See  FIG. 2 ). Conveyor roller assemblies  60  in each row  32 A,  32 B are linearly aligned. Conveyor system  30  is designed to convey a basket  40  through washer  10 . Basket  40  is generally rectangular in shape, having an opened upper end for receiving articles to be washed. In the embodiment shown, basket  40  is comprised of a plurality of connected wire rods  42  that are attached to a bottom frame  44 , having a rectangular cross-section, best seen in  FIGS. 3 and 4 . 
     Referring now to  FIG. 2 , a pair of spaced-apart conveyor roller assemblies  60  is shown within one washer compartment  52 . Washer compartment  52  is basically defined by spaced-apart bulkheads  54 , an inner floor panel  56 , and inner side panels  58 . 
     Each roller assembly  60  is dimensioned for mounting to inner side panel  58  of housing  22 . Each roller assembly  60  includes a mounting block  62  that is dimensioned to be attached to inner side panel  58  of housing  22 . 
     Mounting block  62  is generally cylindrical in shape and includes a cylindrical mounting boss  64  extending from one end thereof (See  FIG. 3 ). Mounting boss  64  is dimensioned to extend through an opening within side panel  58  of housing  22 . Conventional fasteners  66  extend through openings in side panel  58  and are threaded into holes (not shown) in the end of mounting block  62  to secure mounting block  62  to side panel  58 , as illustrated in  FIG. 3 . As best seen in  FIG. 4 , a cylindrical bore  68  extends through mounting block  62  and mounting boss  64 . A cylindrical recess  69  (best seen in  FIG. 4 ) is counter-bored into one end of mounting block  62 , as illustrated in  FIG. 4 . 
     A shaft  72  is dimensioned to be positioned within cylindrical bore  66  in mounting block  62 . Shaft  72  includes an elongated, cylindrical body portion  72   a,  having a cylindrical shank portion  72   b  axially extending therefrom. Shank portion  72   b  has threaded end portion  72   c,  best seen in  FIG. 4 . Shank portion  72   b  is smaller in diameter than body portion  72   a,  such that a shoulder  74 , having an annular surface  74   a,  is formed where shank portion  72   b  meets body portion  72   a.  As illustrated in  FIG. 4 , cylindrical bushings  82  are disposed between body portion  72   a  of shaft  72  and the inner surface of bore  68  in cylindrical block  62 . An annular seal element  76  is disposed within recess  69 . A retaining plate  78  is mounted to the end of mounting block  62  to capture seal  76  within annular recess  69 . Fastening means (not shown) attach the retaining plate to mounting block  62 . 
     Body portion  72   a  of shaft  72  extends outward from mounting boss  64  of mounting block  62 , as best seen in  FIG. 3 . The extending portion of body portion  72   a  of shaft  72  is dimensioned to receive a sprocket gear  82 . In the embodiment shown, sprocket gear  82  is attached to the end of shaft  72  by a setscrew  84 . Sprocket  82  is driven by a drive chain or belt  86  that forms part of a drive system (not shown) for driving roller assemblies  60 , as shall be described in greater detail below. 
     Mounting block  62  is dimensioned to support a rail  92  along the upper edge thereof. In the embodiment shown, rail  92  is an elongated cylindrical rod that extends through washer  10 . Rail  92  has a cylindrical bore  94  extending transversely therethrough (See  FIG. 4 ). Bore  94  is dimensioned to receive a conventional fastener  96  that is received within a threaded opening  98  (best seen in  FIG. 4 ) within mounting block  62 . Guide members  102  are attached to the lateral sides of rail  92  by fasteners  104 , as best seen in  FIG. 4 . 
     A roller  112  is mounted to shank portion  72   b  of shaft  72 . In the embodiment shown, roller  112  is comprised of an inner roller section  112 A, an outer roller section  112 B, and a friction element  132 . In the embodiment shown, inner roller section  112 A and outer roller section  112 B are essentially identical. Each roller section  112 A,  112 B is basically a cylindrical disc  114 , having a cylindrical outer surface  116  and a central, hexagonal-shaped opening  11  S extending through disc  114  (See  FIG. 5 ). An annular groove  122  is formed within a side surface of each roller section  112 A,  112 B. Annular groove  122  defines an annular wall or ridge  124  that defines the periphery of each cylindrical disc  114 . In the embodiment shown, annular wall  124  is dimensioned wherein the width of cylindrical surface  116  is less than the overall thickness of roller section  114 . Openings  118  in roller sections  112 A,  112 B are dimensioned to receive shank portion  72   b  of shaft  72 . When the first and second roller sections  112 A,  112 B are assembled together on shaft  72 , annular grooves  122  formed therein are facing each other. As best seen in  FIG. 4 , a generally T-shaped, annular slot is defined therebetween. 
     The slot is dimensioned to receive and capture an annular friction element  132  best seen in  FIGS. 4 and 5 . Friction element  132  has a generally T-shaped cross section. Friction element  132  includes a base portion  132   a  and a radially extending wall portion  132   b.  Wall portion  132   b  is dimensioned to extend slightly beyond cylindrical surfaces  116  of roller sections  112 A,  112 B when friction element  132  is captured therebetween. As illustrated in the bottom of  FIG. 4 , radially extending wall portion  132   b  of friction element  132  extends a dimension “X” above cylindrical surfaces  116  of roller sections  112 A,  112 B. Friction element  132  is preferably formed of a resilient elastomeric material. In one embodiment, friction element  132  is formed of a silicone material, code 1104X, 75 DURO, SHORE A. Friction element  132  may be formed of other soft, rubber materials, such as, by way of example and not limitation, ethylene propylene diene monomer (EPDM) rubber. Roller sections  112 A,  112 B are mounted to the shank portion of the shaft by a conventional cap-nut  142  threaded onto threaded end portion  72   c  of shaft  72  (See FIG.  5 ). Fastener nut  142  forces roller sections  112 A,  112 B against an annular surface  74   a  of shoulder  74  on shaft  72 . 
     Referring now to the operation of roller assembly  60 , chain drive  86  on conveyor system  30  simultaneously rotates sprocket gear  82  of each roller assembly  60 . Rotation of sprocket gear  82  causes corresponding shaft  72  and roller  112  attached to shaft  72  to rotate in a pre-determined direction.  FIGS. 3 and 4  show a typical metal basket  40  supported by a conveyor roller assembly  60 . As illustrated in  FIGS. 3 and 4 , roller assemblies  60  are dimensioned to engage and support the lower frame portion  44  of a basket  40 . As illustrated in the drawings, inner and outer roller sections  112 A,  112 B, being comprised of stainless steel, provide stable support for basket  40  thereon. Friction element  132 , being formed of a soft, resilient material, improves the traction between basket  40  and roller  112 . In this respect, resilient, friction element  132  of roller  112  maintains surface contact with basket  40 , thereby providing improved frictional contact therewith. In the event basket  40  is heavy, resilient, flexible frictional material will compress until the weight of the basket is borne by the metal roller sections  112 A,  112 B. Resilient friction element  132  will remain in contact with frame  44  of basket  40 , thereby improving the frictional contact therewith. With base portion  132   a  of friction element  132  being wider, friction element  132  is held in place by inner and outer roller sections  112 A,  112 B. 
     The present invention thus provides a composite roller having metal sections for providing firm support of objects and a resilient strip extending from the surface of the roller sections to provide better contact and frictional engagement with the underside of the objects. 
     The foregoing description is a specific embodiment of the present invention. It should be appreciated that this embodiment is described for purposes of illustration only, and that numerous alterations and modifications may be practiced by those skilled in the art without departing from the spirit and scope of the invention. It is intended that all such modifications and alterations be included insofar as they come within the scope of the invention as claimed or the equivalents thereof.