Abstract:
A split-level singulator for arranging and conveying articles in a single file. The singulator comprises a central conveyor and two flanking conveyors advancing in a conveying direction. Rollers in the conveyors protrude through the thickness of the conveyors and ride on underlying supporting bearing surfaces that cause the rollers to rotate as the conveyors advance in the conveying direction. The rollers in the central conveyor rotate in the conveying direction. The rollers in the flanking conveyors rotate in directions oblique to the conveying direction to direct articles conveyed atop the rollers downstream and toward the central conveyor. The tops of the rollers of the central conveyor are vertically offset above or below the tops of the flanking oblique rollers.

Description:
BACKGROUND 
     The invention relates to power-driven conveyors generally and, more particularly, to singulating conveyors for aligning a mass of conveyed articles in a single file. 
     One version of singulator is realized as a central conveyor belt with rollers arranged to rotate on axes perpendicular to the direction of the belt travel. These in-line rollers protrude through the thickness of the belt and ride on a conveyor pan below the belt along a carryway. The article-supporting portions of the rollers protruding past the top of the belt rotate in the direction of belt travel to push conveyed articles forward along the belt and separate them from trailing articles. Flanking the central belt are two belts with rollers arranged to rotate on axes oblique to the direction of belt travel. The rollers on each side of the central belt rotate to push conveyed articles toward the central belt and into a single file. The combined action of the oblique and in-line rollers also tends to orient the articles with their major axes parallel to the direction of belt travel. Like the rollers in the central belt, the rollers in the flanking belts protrude through the thickness of the belts and ride on bearing surfaces underlying the belts. The three belts are coplanar with the rollers all tangent to a common plane. 
     One problem with such a singulator is that large articles that are wider than the width of the central belt tend to rock laterally back and forth when they are more or less centered on the singulator, but still contacting the oblique rollers on both of the flanking belts. Another problem is that narrow articles that fit entirely or almost entirely on the central belt do not orient well because they do not receive the simultaneous rotational effect caused by sufficient contact with enough rollers arranged at different angles. 
     Thus, there is a need for a singulating conveyor that minimizes these problems. 
     SUMMARY 
     These problems are overcome by a singulator embodying features of the invention. One version of a singulator comprises first, second, and third conveyors advancing in a conveying direction. The second and third conveyors flank the first conveyor on opposite sides. Each of the conveyors has rollers that protrude through the thickness of the conveyors. The rollers are arranged to rotate in different directions. The peripheries of the rollers protruding above the first conveyor rotate in the conveying direction. The peripheries of the rollers protruding above the second and third conveyors rotate oblique to the conveying direction and toward the first conveyor. The rollers rotate on bearing surfaces disposed below the first, second, and third conveyors. The tops of the peripheries of the rollers in the first conveyor all extend to a first level. The tops of the peripheries of the rollers in the second and third conveyor belts all extend to a second level that is above or below the first level. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       These features of the invention, as well as other aspects and advantages, are better understood by referring to the following descriptions, appended claims, and accompanying drawings, in which: 
         FIG. 1  is an isometric view, partly cut away, of one version of a singulator embodying features of the invention; 
         FIG. 2  is a cross section of the singulator taken along lines  2 - 2  of  FIG. 1 , showing a lowered central conveying region; 
         FIG. 3  is a top plan diagram of a prior art singulator illustrating a problem with conveying narrow articles; 
         FIG. 4  is a top plan diagram of the singulator of  FIG. 1 , illustrating the handling of narrow packages; 
         FIG. 5  is a cross sectional view as in  FIG. 2  of another version of a singulator with a raised central conveying region; 
         FIG. 6  is a top plan diagram of a prior art singulator as in  FIG. 3  illustrating a problem with conveying wide articles; 
         FIG. 7  is a top plan diagram of the singulator of  FIG. 5 , illustrating the handling of wide packages; 
         FIG. 8  is a cross section as in  FIG. 2  of another version of singulator with smaller-diameter rollers in the central conveying region; and 
         FIG. 9  is a cross section as in  FIG. 5  of another version of singulator with larger-diameter rollers in the central conveying region. 
     
    
    
     DETAILED DESCRIPTION 
     An exemplary version of a conveyor suitable for singulating conveyed articles in shown in  FIG. 1 . The singulator  20  includes a first conveyor  22  flanked on opposite sides by second and third conveyers  24 ,  26 . All three conveyers in this example are individual endless conveyor belts looped around pulleys or sprocket sets  28 , which are mounted on shafts  30  rotatably supported in bearing blocks  32  attached to a conveyor frame (not shown). A motor  34  coupled to the shaft at one end of the singulator drives the conveyor belts in the conveying direction indicated by arrow  36 . The conveyor belts are supported along a carryway by one or more carryway pans  38  mounted in the conveyor frame. Shoes or rolls  39  reduce the sag in the belts in the returnway path. Linear wearstrips  40  attached to the pan form lanes running in the lengthwise direction of the singulator. The wearstrips support the two flanking belts  24 ,  26  along the carryway. A sheet  42  underlies and supports the central belt  22 . The wearstrips could alternatively be replaced by a sheet or the sheet replaced by linear wearstrips. 
     The central conveyor belt  22  includes rollers  44  that reside in cavities  46  formed in the belt. The cavities open onto the top surface  48  and the opposite bottom surface of the belt. Salient portions of the rollers protrude above and below the belt beyond the top and bottom surfaces. Conveyed articles ride atop the rollers on the carryway. The sheet  42 , which acts as a bearing surface, contacts and supports the rollers below the belt along the carryway. As the central belt is driven in the conveying direction, the relative motion between the belt and the sheet causes the rollers to rotate. The rollers are arranged to rotate on axes  43  perpendicular to the conveying direction, which means that the tops of the peripheries of the rollers above the belt rotate in the conveying direction. An article atop these rollers is pushed forward relative to the belt. 
     The flanking conveyor belts  24 ,  26  have rollers  50 ,  52  mounted in cavities  54 ,  56  arranged to provide components of motion in both the conveying direction and a lateral direction toward the central belt. Like the rollers  44  on the central belt, the rollers in the flanking belts protrude past top and bottom surfaces  58 ,  59  of the belts and ride on the underlying wearstrips  40 . The rollers  50  on the second conveyor belt  24  rotate about first axes  60  oblique to the conveying direction. Articles conveyed atop the rollers in the second belt are directed downstream and toward the central conveyor in the direction of arrow  61 . The third conveyor belt  26  is a mirror image of the second belt. Its rollers  52  rotate about second axes  62  oblique to the conveying direction. Articles conveyed atop these rollers are pushed downstream and toward the central conveyor belt in the direction of arrow  63 . 
     As shown in  FIG. 1 , but better in  FIG. 7 , the central conveyor belt  22  resides lower in the conveyor frame than the two flanking oblique-roller belts  24 ,  26 . This is achieved in this example by vertically offsetting the top bearing surface  64  of the central carryway sheet  42  below the level of the top bearing surfaces  65  of the wearstrips  40  supporting the flanking belts. In this way the tops  66  of the peripheries of the in-line rollers  44  on the central belt are at a first level L 1  below the level L 2  of the tops  67  of the peripheries of the oblique rollers  50 ,  52  in the flanking belts. 
     The operation of the singulator with the lowered central belt is shown in  FIG. 4  in contrast with the operation of a conventional one-level singulator in  FIG. 3 . In the conventional singulator, a narrow article  68  is directed toward the central belt  22 ′, which is at the same level as the flanking belts. Once the article is more or less centered on the conveyor, only a small part of it may extend beyond the central conveyor onto either of the flanking conveyors  24 ,  26  with the oblique rollers. As a consequence, the article is supported atop many more of the central belt&#39;s in-line rollers than the flanking belts&#39; oblique rollers, and there is not enough relative force exerted by the oblique rollers to cause the article to rotate its major axis  70  in line with the conveying direction  36 —the preferred orientation of the article. With the central conveyor lower, as in  FIG. 4 , the article  68 ′ bridging the two flanking conveyors is largely out of contact with the in-line rollers in the lower central conveyor  22 . The outer ends of the article are then subjected to the lateral components of force extended by the oblique rollers, which tend to rotate and align the article with its major axis  70  in the conveying direction. 
     Another version of a singulator in which the central conveyor is vertically offset from the flanking oblique-roller conveyors is shown in  FIG. 5 . In this example, the wearstrips of  FIG. 2  are replaced with longitudinal rollers  72  that are free to rotate on axles  74  aligned in the conveying direction. These longitudinal rollers decrease slip between the oblique rollers  50 ,  52  and the outer bearing surfaces of the longitudinal rollers, especially for roller angles above 30° off the conveying direction. But flat wearstrips or other flat bearing surfaces could be used in the example of  FIG. 5 , and the longitudinal rollers could be used under the oblique rollers in the singulator of  FIG. 2 . The central conveyor belt  22 ″ is shown raised relative to the flanking belts  24 ,  26 . This is achieved by raising the level of the bearing surface  64 ′ of the carryway sheet  42 ′ to a level above the tops of the underlying longitudinal rollers. The raised level L 3  of the tops of the rollers is preferably about 0.3 cm (⅛ in) above the level L 2  of the tops of the oblique rollers. (In  FIG. 2 , the level L 1  of the tops of the rollers of the central conveyor is preferably about 0.3 cm below the level L 2  of the tops of the oblique rollers.) 
     The operation of a conventional one-level singulator conveying wide articles is shown in  FIG. 6 . Because a wide article  76  that is more or less centered extends onto both the flanking conveyors  24 ,  26 , as well as the level central conveyor  22 ′, there is a tendency for the article to rock laterally back and forth as more or less of the oblique rollers of one of the flanking conveyors engage the articles. With the central conveyor  22 ″ raised as in  FIG. 5 , the more-or-less-centered article  76  is more stably conveyed atop the slightly raised in-line rollers of the central conveyor largely out of contact with the oblique rollers in the flanking conveyors. Thus, rocking of the centered article is reduced. 
     Another version of a singulator for narrow articles is shown in  FIG. 8 . In this version, the singulator is constructed of a single conveyor belt  78  with obliquely arranged rollers  80  in flanking regions  81 ,  82  of the belt and with in-line rollers  84  in a central region  85 . The rollers ride on bearing surfaces  86 ,  87  underlying the belt. The in-line rollers  82  have a smaller diameter than oblique rollers  80 . Because the tops of the smaller in-line rollers are at a lower level than the tops of the oblique rollers, this singulator operates as shown in  FIG. 4 . To accommodate the smaller-diameter in-line rollers, the bearing surface  87  underlying them is raised above the level of the bearing surfaces  86  underlying the oblique rollers. 
     Another version of a singulator that operates as shown in  FIG. 7  is depicted in  FIG. 9 . This one-belt singulator has larger-diameter in-line rollers  88  in the central region. The tops of the larger-diameter rollers lie at a level above the level of the tops of the peripheries of the flanking oblique rollers  80 . To accommodate the larger-diameter rollers, the bearing surface  90  underlying the in-line rollers is lower than the bearing surfaces  86  underlying the smaller oblique rollers. Thus, this singulator operates in the same way as the singulator in  FIG. 5 . 
     Although the invention has been described with reference to a few preferred versions, other versions are possible. For example, the central conveyor could alternatively be raised or lowered by vertically offsetting the axles on which the rollers rotate. As another example, the vertical offset between the oblique and the in-line rollers may be slightly more or less than 0.3 cm. So, as these examples suggest, the claims are not meant to be limited to the details of the preferred versions.