Abstract:
A modular conveyor belt with a self-adjusting edge for bearing against a conveyor side rail. An edge pad, which can be made of a durable material for long wear life, pivotably attaches to the side edge of a belt row. The pivotable attachment allows the pad to adjust itself to maximize its contact area with the side rail.

Description:
CROSS REFERENCE  
       [0001]     This application claims the benefit of U.S. Provisional Patent Application No. 60/521,807, filed Jul. 6, 2004. 
     
    
     BACKGROUND  
       [0002]     This invention relates generally to power-driven conveyors and, more particularly, to modular conveyor belts that engage a conveyor side rail as they advance along a conveying path.  
         [0003]     Modular conveyor belts are constructed of a series of rows of belt modules linked by hinge pins through the interleaved hinge eyes of consecutive rows. Conveyor belts are supported in a conveyor frame that defines the belt&#39;s conveying path. In some applications, the conveying path includes turns. Modular belts that can negotiate turns typically bear against a side rail at the inside of the turns as the belt advances. The inside edge of the belt rubs on the side rail. Usually the side rail provides a vertical surface against which the parallel vertical side edge of the belt can bear. But, in many situations, the side edge of the belt at the inside of a turn is not parallel to the vertical side rail. If the plane of the belt at the inside edge is not aligned perpendicular to the side rail, the contact between the side rail and the edge of the belt is not distributed across the entire side edge of the belt. Instead, only a corner of the belt&#39;s inside edge contacts the side rail. The concentrated force at the corner digs into and scores the side rail. The friction heats the belt at the edge and, especially in the case of plastic belts, causes the belt material to deteriorate, which shortens the belt&#39;s useful lifetime.  
         [0004]     Thus, there is a need to prevent modular conveyor belts from prematurely aging because of the misalignment of the bearing edge of a conveyor belt relative to a conveyor side rail.  
       SUMMARY  
       [0005]     This need and other needs are satisfied by a modular conveyor belt embodying features of the invention. In a first version, a series of rows of belt modules are hingedly interconnected end to end to form a conveyor belt that extends in a lateral direction from a first side edge to a second side edge. A bearing member is attached pivotably to the first side edge.  
         [0006]     In another aspect of the invention, a modular conveyor belt is made up of a series of rows of belt modules hingedly interconnected end to end. The belt extends laterally from a first side edge to a second side edge and each row generally defines a plane. A bearing member pivotably attached to the first side edge of a row includes an outer bearing surface whose orientation is variable relative to the plane of the row.  
         [0007]     In yet another aspect of the invention, an edge module for a modular conveyor belt comprises a module body extending longitudinally from a first end to a second end, laterally from a first side edge to a second side edge, and in thickness from a top to a bottom. Hinge eyes extend longitudinally from the first and second ends. A bearing member is pivotably attached to the first side edge of the module. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0008]     These features and aspects of the invention, as well as its advantages, are better understood by reference to the following description, appended claims, and accompanying drawings, in which:  
         [0009]      FIG. 1  is a top plan view of a portion of a modular conveyor belt embodying features of the invention;  
         [0010]      FIG. 2A  is an isometric view of an edge portion of an edge module usable in a belt as in  FIG. 1  without an edge pad, and  FIG. 2B  is an isometric view as in  FIG. 2A  with an edge pad in place.  
         [0011]      FIGS. 3A and 3B  are isometric and front elevation views of an edge pad as in  FIG. 2B ;  
         [0012]      FIG. 4  is an elevation view of a side edge of a belt module as in  FIG. 2B  showing the range over which the edge pad can swivel;  
         [0013]      FIG. 5A  is an elevation view of the inside edge portion of a conveyor as in  FIG. 1 , and  FIG. 5B  is an elevation view as in  FIG. 5A  with the edge portion of the belt lifted out of its preferred position; and  
         [0014]      FIG. 6  is an isometric view of another version of a side edge usable in a belt as in  FIG. 1  and featuring an edge pad with a stub for attaching to an edge module. 
     
    
     DETAILED DESCRIPTION  
       [0015]     A portion of a modular conveyor belt embodying features of the invention is shown in  FIG. 1  in a turn segment of a conveying path. The belt  10  is constructed of rows  12 A- 12 D of one or more belt modules (in this example, two modules per row: a short edge module  14  and a long edge module  15 ) arranged side by side. Each edge module extends from an outer side  16 ,  16 ′ to an interior side  17 ,  17 ′. The outer sides form the first and second side edges  18 ,  19  of the belt. Hinge eyes  20 ,  20 ′ are spaced apart laterally along first and second ends  22 ,  23  of each row. Aligned openings  24 ,  24 ′ in the interleaved hinge eyes of consecutive rows receive a hinge pin  26  that links the rows together into an endless belt capable of articulating about drive and idler sprockets or drums. To enable the belt to collapse at the inside of a turn, the openings  24  in the hinge eyes along the first end  22  are slotted in the direction of belt travel  28 . The openings  24 ′ at the second end  23  may be circular in cross section. Of course, for a belt that need not follow a curved conveying path, elongated hinge rod openings are not necessary.  
         [0016]     A modular belt of any desired width can be constructed by adding internal modules between the side edge modules  14 ,  15 . Internal modules would typically be similar in structure, but without the outside edge structure  16 ,  16 ′ of the edge modules. The modules are conventionally arranged in a bricklay pattern for strength. Preferably, the modules are formed of a thermoplastic polymer, such as polyethylene, polypropylene, or acetal in an injection molding process. Modular belts of this sort are available from, for example, Intralox, L.L.C., of Harahan, La., USA.  
         [0017]     As shown in  FIG. 1 , the belt  10  is traveling in a turn along a conveying path. Because the path at the inside of a turn is shorter than the path at the outside of the turn, a conveyor belt designed to operate in turns must be able to adjust to the differences in path lengths across the width of the belt. The elongated hinge rod openings in the second set of hinge eyes allow the belt  10  to collapse at the inside of the turn. In the turn, the belt is also pulled against a side rail  30  mounted in a conveyor frame. Rubbing contact between the side of the belt and the side rail generates a great deal of friction. Bearing members in the form of pads  32  pivotably attached to the outer sides  16 ,  16 ′ of the edge modules protect the sides of the belt from the effects of friction; namely, accelerated wear due to abrasion or to degradation of the plastic material of the edge module from continual heating. The pads are preferably made of a durable material, such as carbon steel, stainless steel, or nylon, as some examples.  
         [0018]     The outside edge portion of one version of an edge module in a row is shown in more detail in  FIGS. 2A and 2B . The structure of this edge module  34  differs slightly from that shown in  FIG. 1 , but functions similarly. As best seen in  FIG. 2A , an axle  36  in the shape of a cylindrical barrel with a long axis  38  in the longitudinal direction of the module is formed in a recess  40  at the outside edge of the module body. A pad  32  ( FIG. 2B ) clips onto the axle, about which the pad can rotate over a limited range. As shown in  FIGS. 3A and 3B , the pad includes an outer bearing surface  42  and an opposite inner side  44 . Two arms  46 ,  47  extend from the inner side and terminate at their distal ends in hook portions  48 ,  49  to form a collar open across a throat  45 . Struts  50 ,  51  add support to the arms. Curved surfaces  52 ,  53  on the inner sides of the collar and a curved surface  54  on the inner side of the pad are shaped to rotatably receive the axle  36  on the edge module. The pad snaps onto the axle through the throat of the collar. The hook portions retain the pad on the axle. The curved surfaces on the pad ride around the outer surface of the axle to vary the orientation of the pad relative to the plane of the edge module.  
         [0019]     The range of rotation of the pad  32  relative to the module  34  is shown in  FIG. 4 , in which the plane of the module is represented generally by its lateral centerline  56 , midway between the top  58  and bottom  59  of the edge module. The pad can rotate up to a first position  32 ′ about the axle  36  and down to a second position  32 ″. The angular range of rotation α is symmetrical about the centerline in this example, but could be asymmetrical as well.  FIG. 5A  depicts the edge of a belt supported below on a wearstrip  58 . The outer bearing surface  42  of the pad  32  bears against the conveyor side rail  30 . In the ideal conveying situation depicted in  FIG. 5A , the bearing surface is generally perpendicular to the plane of the edge module. But it sometimes happens that, as a belt makes it way around a turn, the outside of the belt tends to rise up out of the conveyor frame, as shown in  FIG. 5B . The plane of the belt in that situation is no longer perpendicular to the face of the rail. But the pad is able to swivel about the axle so that the bearing surface  42  maximizes its contact area with the side rail. As the plane of the belt changes relative to its ideal horizontal orientation, the swivel pad always assumes the position of maximum contact with the rail. In this way, the pad is self-adjusting.  
         [0020]     Another version of the swivel pad is shown in  FIG. 6 . In this version, an edge module  60  has an outside recess  62 . Opposite walls  64 ,  65  bounding the recess have receptacles  66  formed in them. A pad  68  with an outer bearing surface  70  has a leg  72  extending from its inner side terminating in stubs  74 ,  75  that are received in the receptacles. In this way, the pad can rotate about a longitudinal axis  76  defined by the longitudinally aligned receptacles.  
         [0021]     Thus, the invention has been described in detail with respect to a few preferred versions. But other versions are possible. For example, the joint between the pad and the edge module could be a ball and socket, which would allow the pad to swivel about multiple axes rather than just the single axis of the depicted versions. As another example, the pads need not necessarily be attached on every row or on both sides of the belt. Consequently, as these examples suggest, the scope of the invention is not meant to be limited to the details of the versions described in detail.