Abstract:
A transverse-roller conveyor belt and a conveyor system providing a drive mechanism for driving the rollers in the belt to divert conveyed articles. The conveyor belt includes belt rollers that each engage a pair of smaller-diameter, article-conveying rollers. The conveyor system&#39;s drive mechanism, when selectively actuated, rotates the belt rollers, which rotate the article-supporting rollers to divert conveyed articles toward or off the side of the belt. Gaps between at least some of the pairs of article-supporting rollers admit the teeth of a transfer comb to strip remaining articles off the downstream end of the belt.

Description:
BACKGROUND 
     The invention relates generally to power-driven conveyors and more particularly to conveyor systems having belts with article-supporting rollers actuated to divert articles toward a side of the belt. 
     Some conveyor belts include rollers that can be rotated to divert articles toward one side of the belt or the other. In the INTRALOX® Series 7000 Transverse Roller belt, the rollers are arranged with their axes of rotation aligned with the direction of belt travel. The rollers extend beyond top and bottom surfaces of the belt. A drive mechanism engages the rollers below the bottom surface of the belt and causes the rollers to rotate and divert articles across the width of the belt. The rollers in the INTRALOX® Series 7000 belt are separated transversely by belt structure that has drive recesses on a bottom surface for receiving the teeth of drive and idle sprockets. The belt structure separating the rollers limits the minimum transverse spacing of the rollers and the contact area available for supporting articles atop the rollers. 
     SUMMARY 
     These limitations are addressed by a conveyor belt embodying features of the invention. One version of such a belt comprises a first set of rollers supporting a second set of rollers. The first rollers are arranged to rotate on axes oriented in a direction of belt travel. The second rollers, which are supported atop the first rollers, have axes of rotation parallel to the axes of the first rollers. Each of the first rollers contacts a pair of the second rollers flanking the first roller. 
     In another aspect of the invention, a conveyor system comprises a conveyor belt as described in the preceding paragraph and a drive mechanism underlying the conveyor belt. The drive mechanism engages the first rollers to rotate them in a first direction perpendicular to the direction of belt travel. The first rollers, in turn, rotate the second rollers in a second direction opposite to the first direction. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       These aspects and features of the invention, as well as its advantages, are described in more detail in the following description, appended claims, and accompanying drawings, in which: 
         FIG. 1  is a partly exploded view of a portion of one row of a modular plastic conveyor belt embodying features of the invention; 
         FIG. 2  is a cross section of a portion of the conveyor belt of  FIG. 1  taken along lines  2 - 2 ; 
         FIG. 3  is an isometric view of a carryway portion of a conveyor system using a conveyor belt as in  FIG. 1  with the article-supporting rollers removed for clarity; and 
         FIG. 4  is an isometric view of an outfeed end of the carryway portion of the conveyor system of  FIG. 3 . 
     
    
    
     DETAILED DESCRIPTION 
     A portion of one row of a modular conveyor belt embodying features of the invention is shown in  FIG. 1 . The belt row  10  comprises one or more belt modules  12  arranged side by side. Each module extends from a first end  14  to an opposite second end  15  in a direction of belt travel  16 . Belt rollers  18  reside in cavities  20  formed in the belt module between the first and second ends. An axle  22  extending through a bore  24  in each belt roller defines an axis of rotation  26  for the belt roller. The axis of rotation  26  is parallel to the direction of belt travel  16 . The axles of all the belt rollers  18  in the belt row  10  lie in a common plane. 
     Mounted atop each belt roller  18  is a pair  28  of article-supporting rollers  30  of substantially the same length as the belt rollers. Because there are more article-supporting rollers  30  than belt rollers  18 , the article-supporting rollers provide more contact area for conveyed articles than would the belt rollers  18  in a belt without the pairs of article-supporting rollers  30 . The peripheries of the rollers contacting each other may be made of high-friction materials for good engagement. The article-supporting rollers alternatively can be made of materials producing a low-friction or durable periphery. Bores  32  through the article-supporting rollers  30  receive axles  3 , which define axes of rotation  35  parallel to the axes  26  of the belt rollers  18 . The ends of the axles are pressed-fitted in upper openings  36  formed in stanchions  37  extending upward from the seats  38  of supports  40 . The axles can be corrosion-resistant, plain, or hardened steel, for example. The supports each have a lower leg  42  extending downward from the opposite end of the seat  38 . The lower legs  40  reside in the belt-roller cavities  20  at opposite ends. The seats  38  sit on the top surface  44  of the belt module  12 . A hole  46  through each leg  42  of the support  40  receives the axle  34  of the article-supporting roller  30 . The axle  34  retains the support  40  in the cavity. The lateral (widthwise) dimension of the cavities  20  is only slightly greater than the lateral dimension of the support legs. In this way, the supports are prevented from rotating in the cavities. 
     As shown in  FIG. 2 , the belt rollers  18  are separated from each other across a first gap  46 . The article-supporting rollers  30  of each pair  28  atop a common belt roller are separated by a second gap  48 . The pairs  28  of article-supporting rollers are separated from their neighboring pair by a third gap  50 . The first gaps  46  are wider than the third gaps  50 . At least some of the third gaps  50  are wider than the second gaps  48 . The rest of the third gaps can have the same width as the second gaps for a more uniform roller arrangement. The diameter of the belt rollers  18  is greater than the diameter of the article-supporting rollers  30 . Furthermore, the bores  32  through the article-supporting rollers  30  have a diameter large enough in relation to the diameter of the axles  34  to provide a degree of clearance that ensures that the article-supporting rollers float on their axles to maintain their peripheries in uniform contact with the peripheries of the belt rollers to compensate for roller wear and manufacturing tolerances in the positioning of the axles  22 ,  34 . Just as the axes of the belt rollers  18  lie in a common plane  52 , the axes of the article-supporting rollers  30  lie in a parallel common plane  54  above the plane of the belt roller. 
     A carryway portion of a conveying system  56  having a conveyor belt  58  constructed of rows  10  of belt modules  12  as in  FIG. 1  is shown in  FIG. 3  with the article-supporting rollers removed for simplicity. Adjacent rows are joined at hinge joints  59  by hinge rods  61  through interleaved hinge elements  63  at the ends of each row. The conveyor belt  58  is shown advancing in the direction of belt travel  16  along a carryway path. A drive mechanism  60  in the form of a planar array of passive actuating rollers  62  that rotate on axes  64  oblique to the direction of belt travel  16  into the axes of the belt rollers  18 . As the conveyor belt advances in the direction of belt travel, the freely rotatable belt rollers  18 , which have salient portions protruding below the bottom of the conveyor belt, engage the freely rotatable, oblique actuating rollers  62 . The forward motion of the belt causes the oblique rollers  62  to rotate as indicated by arrow  66  and the belt rollers  18  to rotate toward a first side  67  of the belt as indicated by arrow  68 . The belt rollers  18  can be rotated in the opposite direction toward an opposite second side  69  of the belt by reorienting the oblique actuating rollers  62  so that their axes  64  extend obliquely from the first side  67  downstream to the second side  69  of the belt. And, as shown in  FIG. 2 , rotating the belt rollers  18  toward the first side of the belt causes the article supporting rollers  36  to rotate in the opposite direction  72 . The actuating roller array  60  can also be selectively disengaged from the belt rollers  18  by an actuator raising and lowering the array, as indicated by two-headed arrow  70 . When the roller array is disengaged, the belt rollers  18  and the article-supporting rollers  30  are not actively driven by the forward motion of the belt  58 , and conveyed articles supported atop the article-supporting rollers are not diverted toward either side of the belt. 
     As shown in  FIG. 4 , articles not diverted off either side of the conveyor belt  58  are stripped from the belt by a transfer comb  73  having teeth  74  that fit into the wider third gaps  50  between, in the example of  FIG. 4 , every other pair  28  of article-supporting rollers  30 . The transfer comb  73  is positioned at an outfeed end  76  of the carryway. At the outfeed end  76 , the conveyor belt transitions from the upper carryway to a lower returnway around a reversing element, in this example, a set of sprockets  78  mounted on a shaft  80 . The shaft may be a drive shaft conventionally rotated by a motor. Sprocket teeth  82  received in receptacles  84  formed in the belt drive the belt in the direction of belt travel  16 . Articles conveyed atop the article-supporting rollers  30  are pushed across top surfaces  86  of the comb teeth  74  and onto a transfer plate  88  at the outfeed end of the carryway as the belt  58  transitions downward to the returnway. 
     Although the invention has been described in detail with respect to an exemplary version, other versions are possible. For example, the conveyor belt shown is a modular plastic conveyor belt having belt and article-supporting rollers. But the conveyor belt can be a flat, hingeless belt with two sets of rollers, or it can be an array of two sets of rollers supported at opposite ends by roller chain. As another example, the drive mechanism for the rollers can alternatively be realized as an array of short caster rollers rather than the long actuating rollers shown in  FIG. 3 . And the caster rollers can be rotated about vertical axis into non-actuating positions with their axes perpendicular to the direction of belt travel, allowing the belt rollers to ride along the caster array without rotation. As yet another example, the wider gaps between article-supporting roller pairs that accommodate the teeth of a transfer comb could be positioned between each pair of article-supporting rollers or between every third pair, and so on, depending on the desired tooth density. And the reversing element may be idle or drive sprockets, pulleys, or drums. So, as these few examples suggest, the scope of the claims is not meant to be limited to the exemplary embodiments described in detail.