Patent Publication Number: US-8123021-B2

Title: Methods for singulating abutting articles

Description:
BACKGROUND 
     The invention relates generally to power-driven conveyors and, more particularly, to methods for operating conveyors to separate and singulate abutting conveyed articles. 
     Singulating conveyors are used to convey articles in a single file so that the articles can be individually processed. One conventional way of singulating articles is to cascade a series of centering conveyors having article-supporting rollers on opposite sides of the conveyor rotating in converging directions to direct articles toward a lateral position across the width of the conveyor. Each successive centering conveyor operates at a faster speed to increase the separation between consecutive articles. But some articles, such as boxes, have a tendency to remain in frictional contact with each other, especially if they are laterally abutting along long sides. The conventional centering conveyors are not always able to separate laterally abutting boxes. 
     Thus, there is a need for a method of separating laterally abutting conveyed articles so that they can be singulated. 
     SUMMARY 
     This need is satisfied by methods for singulating laterally abutting conveyed articles in a conveyor embodying features of the invention. One such method comprises: (a) feeding laterally abutting articles onto an upstream portion of a first conveyor segment divided across its width into a first conveyor section having article-supporting rollers rotating to direct supported articles downstream in a first direction and a second conveyor section having article-supporting rollers rotating to direct supported articles in a second direction downstream and away from the first conveyor section toward a first side of the conveyor; and (b) rotating the rollers in the first conveying section at a first velocity having a downstream component of velocity in a general conveying direction and rotating the rollers in the second conveying section at a second velocity having a downstream component of velocity, wherein the first direction diverges from the second direction. 
     In another aspect of the invention, such a method comprises: (a) feeding laterally abutting articles onto an upstream portion of a first conveyor segment divided across its width into a first conveyor section having article-supporting rollers arranged to rotate in a first direction and a second conveyor section having article-supporting rollers arranged to rotate in a second direction oblique to the first direction, downstream and away from the first conveyor section toward a first side of the conveyor; and (b) separating laterally abutting articles by directing those articles on the second conveyor section toward the first side of the conveyor and with a downstream speed less than the downstream speed of those articles on the first conveyor section. 
     In yet another aspect of the invention, a method for singulating laterally abutting articles conveyed downstream along a conveyor comprises: (a) conveying articles in a general conveying direction on a first diverging roller conveyor segment having article-supporting rollers arranged to direct some of the articles toward the first side of the conveyor and away from the other articles; and (b) conveying the articles on a centering roller conveyor segment downstream of the first diverging roller conveyor segment having article-supporting rollers arranged to merge the articles along an axis between the first and second sides of the conveyor. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       These features and aspects of the invention, as well as its advantages, are better understood by referring to the following description, appended claims, and accompanying drawings, in which: 
         FIG. 1  is an axonometric view a belt conveyor useful in carrying out the methods of the invention; 
         FIG. 2  is a partial cross section of the belt conveyor of  FIG. 1  taken along lines  2 - 2 ; 
         FIG. 3  is a cross section of the belt conveyor of  FIG. 1  taken along lines  3 - 3 ; 
         FIG. 4  is a top plan view of a powered-roller conveyor useful in carrying out the methods of the invention; 
         FIG. 5  is a top plan schematic representation of the belt conveyor of  FIG. 1  and the powered-roller conveyor of  FIG. 4  showing how it separates laterally abutting boxes; 
         FIG. 6  is a top plan schematic representation of a singulating conveyor useful in carrying out the methods of the invention and incorporating the belt conveyor of  FIG. 1  or the powered-roller conveyor of  FIG. 4 ; and 
         FIGS. 7-9  are top plan schematic representations of other conveyor roller configurations useful in carrying out the methods of the invention. 
     
    
    
     DETAILED DESCRIPTION 
     One version of a conveyor for helping to singulate laterally abutting conveyed articles according to the method of the invention is the belt conveyor shown in  FIGS. 1-3 . The conveyor  20  includes an endless conveyor belt  22  having an upper conveying surface  26  along which articles are conveyed. The upper conveying surface of the belt is supported on a carryway that includes support members, such as wearstrips  29 , or equivalently, a wear sheet spanning the width and length of the carryway. The conveyor belt is driven in a conveying direction  32  by a drive including a motor  34  coupled to a drive shaft  36 . Sprockets  38  mounted on the drive shaft engage drive surfaces on the inner sides  40  of the belt at a downstream end  42  of the carryway. The belt is trained between the drive sprockets  38  and idle sprockets  39  at an upstream end  43  of the carryway. The idle sprockets are mounted on an idle shaft  37 . Both shafts are supported for rotation in bearing blocks  44  at each end, which are mounted in a conveyor frame (not shown). The belts are supported and their sag is reduced along a lower returnway  46  by rollers or shoes  48 . 
     The conveyor belt  22  has two sets of rollers  50 ,  51  with diameters that exceed the thickness of the belt. Salient portions of the rollers extend past top and bottom sides  52 ,  53  of the belt. The salient portions of the rollers  50 ,  51  ride along roller-engagement bearing surfaces  54  formed by the flat top sides of the support members—wearstrips  29 , in this example. The rollers engage the bearing surfaces as the belt advances and rotate in the direction indicated by the arrow  56  in  FIG. 3 . The rollers  50  in a first conveying section  47  at one side of the belt are arranged to rotate on lateral axes  58  (90° from the conveying direction). These rollers  50  are referred to as in-line rollers because they rotate in and push conveyed articles parallel to the main conveying direction, i.e., the direction of belt travel  32 . The rollers  51  in a laterally offset second conveying section  49  nearer the other side of the belt  22  are arranged to rotate on axes  59  oblique to the conveying direction and to the axes of the in-line rollers. For example, the axes of the rollers could be 30° off the lateral axes of the in-line rollers. These rollers  51  are referred to as oblique rollers. As the belt advances, each roller applies a force to an article conveyed atop it in a direction perpendicular to the roller&#39;s axis. Thus, the in-line rollers  50  push the article in the conveying direction  32 , and the oblique rollers  51  push the article obliquely toward its side of the conveyor away from the first conveying section  47 . Alternatively, the conveyor could be realized as two individual side-by-side belts: one with the in-line rollers and the other with the oblique rollers. 
     As the belt advances, the rollers rotate in the directions indicated. If the rollers do not slip as they rotate on the bearing surfaces, the tops of the in-line rollers  50  will have a velocity with a speed in the direction of belt travel and relative to the conveying surface equal to the belt speed. The tops of the oblique rollers  51  will also have a velocity component in the direction of belt travel equal to the belt speed and to the speed of the in-line rollers. The tops of the oblique rollers will, of course, also have a lateral component of velocity whose magnitude depends on the rollers&#39; angle of obliqueness. In high-speed operation of the belt, however, the oblique rollers, because of their oblique orientation, will experience more sliding than the in-line rollers as they are dragged along the bearing surface by the belt&#39;s advance. The sliding decreases the rotational speed of the rollers. The result is that the velocity component in the direction of belt travel of the in-line rollers, which inherently slip less than the oblique rollers, is greater than the oblique rollers&#39; velocity component in the direction of belt travel. And the greater the angle of the oblique rollers&#39; orientation, the greater is the slip. With two side-by-side belts, each could alternatively be mounted on separate drive and idle shafts and driven at different speeds to achieve different roller velocities from one belt to the other. 
       FIG. 4  shows a live- or powered-roller conveyor that may be used to practice the method of the invention. The conveyor  60  is divided widthwise into a first conveying section  62  having in-line rollers  64  arranged to rotate on first axes  66  perpendicular to the conveying direction  68  and an adjacent second conveying section  63  having oblique rollers  65  arranged to rotate on oblique second axes  67 . Unlike belt rollers, which advance with the belt, the rollers in powered-roller conveyors are stationary, their positions along the conveyor fixed. The in-line article-supporting rollers  64  are conventionally powered by a belt or band to rotate to propel articles atop the rollers in the direction given by arrow  70  at a speed proportional to the length of the arrow. The oblique rollers  65  are driven by a separate drive mechanism or the same drive mechanism as the in-line rollers arranged to propel articles in the direction of arrow  71  at a speed proportional to the length of the arrow such that the oblique rollers&#39; component of velocity  71 ′ in the conveying direction  68  is less than the speed of the in-line rollers. (The oblique rollers&#39; lateral component of velocity  71 ″ directs articles conveyed atop the oblique rollers to the side  72  of the conveyor opposite the in-line-roller conveying section.) 
     The method of operation of the diverging roller conveyor of  FIG. 1  or  4  is shown in  FIG. 5 . Two laterally abutting articles  74 ,  75  are fed onto the upstream end  76  of the conveyor atop in-line rollers in a first conveying section  78  and oblique rollers in an adjacent second conveying section  79 . Arrows  80  and  81  indicate the relative velocities (magnitude and direction) of the tops of the rollers in each conveying section. As the coupled articles engage the rollers in each conveying section, article  74 , which is shown resting in the oblique-roller section is rotated and diverted toward a side wall  82  bordering the outer side of the second conveying section. (The downstream speed of articles could be slowed by their frictional contact with the side wall. Increasing the side-wall friction by making it out of a higher-friction material is another way of controlling the speed of the articles in the oblique-roller section.) Article  75 , which lies largely atop the rollers in the in-line section, is sped ahead of article  74  by the greater downstream speed of the in-line rollers. Because few of the oblique rollers engage article  75 , it continues to proceed in the conveying direction. If the article was atop more of the oblique rollers, it would eventually be drawn onto the second conveying section, but not before it has been separated from and advanced ahead of its former mate, article  74 . The paths of the two articles are shown with the articles depicted in their approximate orientations and positions on the conveyor at four different times to demonstrate the operation of the diverging roller conveyor. The initial divergence of the paths indicates the effectiveness of the conveyor in separating the abutting articles and eliminating their further mutual frictional interaction, which could cause jamming in narrower conveyors or in the case of larger or more abutting articles. 
     The diverging roller conveyor whose operation is illustrated in  FIG. 5  could be further used as part of a longer conveyor, such as the exemplary singulating conveyor system shown in  FIG. 6 . (The arrows on the conveyor segments indicate the direction of rotation of the rollers in that portion of the conveyor.) The conveyor  90  has an infeed conveyor  92  at an upstream end feeding a scrambled mass of articles onto a first diverging roller conveyor  94 , such as one that operates according to the principles of  FIG. 5 . The infeed conveyor may be a flat or modular plastic conveyor belt or a roller or slat conveyor running at, for example, 90 ft/min. The articles are initially separated and partly singulated in the first diverging roller conveyor that may be running at 140 ft/min to help increase separation from the upstream pack. The first diverging roller conveyor is shown divided across its width into an in-line-roller conveying section  96  and an oblique-roller conveying section  97  whose rollers are oriented 30° from the orientation of the in-line rollers. The in-line rollers rotate faster in the downstream conveying direction  98  than the oblique rollers as indicated by the arrows. The demarcation between the two sections is indicated as the centerline  99  of the conveyor segment, but could be offset laterally toward either side of the conveyor. Two centering conveyors  100 ,  101  are cascaded downstream of the first diverging roller conveyor segment  94 . As indicated by the arrows and the demarcation line in the upstream-most centering conveyor  100 , it has two side-by-side conveyor sections with oblique rollers arranged to rotate in directions, for example, ±30° off in-line, to cause conveyed articles to converge toward a lateral position indicated by the demarcation line  102 , which forms a merge axis parallel to the general conveying direction. This centering conveying segment serves to further increase the separation between consecutive articles received from the first conveying segment by running at a faster forward speed, such as about 200 ft/min. The centering segment also tends to align the articles in a single file along the demarcation line  102 , which is shown closer to the left-hand side  104  than to the right-hand side  105  of the conveyor. The following centering conveyor segment  101  runs even faster than the preceding one at, for example, about 225 ft/min to effect even greater article separation through acceleration from one segment to the next. Its line of demarcation between the two oblique-roller sections is even closer to the left-hand side than in the preceding segment. The final conveying segment shown is a registration conveyor  106  that has, for example, 30° oblique rollers arranged to push all the conveyed articles in registration against the left-hand side of the conveyor. This stepping of the lateral singulation position along the cascaded segments helps ensure a complete singulation of the articles against the left-hand side of the conveyor with adequate separation, but stepping is not necessary in all applications. 
     Singulating conveyors having other roller configurations are illustrated in  FIGS. 7-9 . In  FIG. 7 , the infeed conveyor  92  feeds articles onto a diverging roller conveyor segment  108  having side-by-side oblique-roller sections  110 ,  111 . Like the oblique rollers in the centering conveyor segments  100 ,  101  of  FIG. 6 , the oblique rollers may be arranged as mirror images of each other, but directed outward instead of inward. They could also be rotated at the same speed, which would produce velocities that differ in direction but not in magnitude. Downstream centering conveyor segments  112  and  114 , which would typically be operated at successively higher speeds to increase separation, are similar to the corresponding segments in  FIG. 6 , except that they are shown without the stepping of the line of demarcation  116  between the differently directed roller sections. The final segment  106  is a registration conveyor segment that aligns the articles against the left-hand side of the conveyor. 
     The singulating conveyor in  FIG. 8  has a diverging roller segment  94  as in the conveyor of  FIG. 6  followed by a centering conveyor segment  112  as in  FIG. 7 . Following the centering segment is a second diverging segment  118  whose rollers are configured to speed articles in the left-hand section  120  in the conveying direction and articles in the right-hand section  121  toward the right-hand side of the conveyor at a slower speed in the conveying direction. Because the second diverging roller segment directs articles toward the opposite side of the conveyor than does the first diverging roller segment, it can be helpful in separating abutting packages that the first diverging roller segment could not successfully separate because of how the packages happened to have been arranged. The articles are then received on a registration conveyor  122 , whose oblique rollers are oriented to direct articles into alignment along the right-hand side of the conveyor. 
     The conveyor illustrated in  FIG. 9  is similar to the conveyor of  FIG. 8 , except that a second centering segment  112 ′ is inserted between the second diverging segment  118  and the registration conveyor  106 , which, in this example, directs separated articles toward the left-hand side instead. 
     Although the invention has been described in detail with a few preferred versions, other versions are possible. For example, the oblique rollers were shown on angles of 30° only, but they could be oriented on other angles. As another example, the speeds of the successive conveyor segments given for the example of  FIG. 5  were for descriptive purposes only and not by way of limitation. So, as these examples suggest, the details were provided as examples of different ways of practicing the invention and not by way of limiting the scope of the claims to those details.