Abstract:
A conveyor and methods for turning cases. The conveyor includes a pair of side-by-side belts running preferably at different speeds. The different belt speeds cause the leading edge of a package straddling both belts to move toward the slower belt. The two belts include transverse rollers that can be selectively actuated in a series of actuation zones along the conveyor to push packages conveyed atop them to the right or to the left. A controller controls the actuation of the belt rollers in each zone sequentially so that the belt rollers supporting the leading edge of the package push it towards the slower belt and the belt rollers supporting the trailing edge of the package push it towards the faster belt to accelerate the turning of the package as the belts advance.

Description:
BACKGROUND 
       [0001]    The invention relates generally to power-driven conveyors and, more particularly, to belt conveyors and methods for turning cases using conveyor belts with selectively actuated, case-supporting rollers. 
         [0002]    Traditional case-turning conveyors use two side-by-side conveyor belts traveling parallel to each other at different speeds. When a package is fed onto and straddles the two belts, the faster belt pulls one side of the package ahead, causing the package to rotate, its leading edge moving toward the slower belt. The package continues to rotate as it is conveyed along the conveyor, finally resting mostly on the slower belt and turned somewhat less than 90°. The package is then plowed into its final orientation and lateral location by a rail extending across the conveyor. 
         [0003]    Thus, there is a need for a case turner that can turn packages completely 90° in a short distance without the need for plowing. 
       SUMMARY 
       [0004]    This need and other needs are addressed by a conveyor embodying features of the invention. One version of such a conveyor comprises a first conveyor belt advancing at a first speed in a direction of belt travel. A second conveyor belt is arranged side-by-side with the first conveyor belt. The second conveyor belt advances in the direction of belt travel at a second speed. Preferably, the first speed is greater than the second speed. The first and second conveyor belts have article-supporting rollers arranged to rotate perpendicular to the direction of belt travel. A series of sequentially actuated actuation zones are disposed consecutively along the length of the conveyor. Each actuation zone has actuators selectively actuating all the article-supporting rollers of the first and second conveyor belts in the actuation zone to rotate in one perpendicular direction or in the opposite direction. 
         [0005]    In another aspect of the invention, a method for turning an article comprises: advancing a first conveyor belt at a first speed in a direction of belt travel; advancing a parallel second conveyor belt at a second speed in the direction of belt travel; sensing the leading edge of a conveyed article straddling the first and second conveyor belts; actuating article-supporting rollers in the first and second conveyor belts supporting the leading edge of the conveyed article to rotate in a direction perpendicular to the direction of belt travel to move the leading edge of the conveyed article toward the second conveyor belt; and actuating article-supporting rollers in the first and second conveyor belts supporting the trailing edge of the article to rotate in a direction opposite to the direction of the rollers supporting the leading edge to move the trailing edge of the article toward the first conveyor belt. 
         [0006]    Yet another aspect of the invention provides a method for turning an article. The method comprises: conveying an article simultaneously on a pair of side-by-side conveyor belts advancing at different speeds in a direction of belt travel to cause the article to rotate with the leading edge of the article moving toward the slower belt and the trailing edge of the article moving toward the faster belt; and accelerating the rotation of the article by actuating article-supporting rollers in both conveyor belts under the leading edge to rotate toward the slower belt and by actuating article-supporting rollers in both conveyor belts under the trailing edge of the article to rotate toward the faster belt. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0007]    These features and aspects of the invention are exemplified in more detail in the following description, appended claims, and accompanying drawings, in which: 
           [0008]      FIG. 1  is an isometric view, partly cut away, of a case-turning conveyor embodying features of the invention; 
           [0009]      FIG. 2  is an exploded isometric view of the roller-actuation system of the conveyor of  FIG. 1 ; 
           [0010]      FIG. 3  is an enlarged isometric view of a portion of the roller-actuation system of  FIG. 2  showing rack-and-pinion roller actuation; 
           [0011]      FIG. 4  is a bottom isometric view of the rack actuators in the roller-actuation system of  FIG. 2 ; 
           [0012]      FIGS. 5A-5C  are cross sectional views looking upstream at the conveyor of  FIG. 1  showing actuating rollers in positions causing the belt rollers to rotate in directions to push conveyed packages to the left in  FIG. 5A , to the right in  FIG. 5B , and to brake the belt rollers in  FIG. 5C ; 
           [0013]      FIG. 6  is a schematic diagram of the roller-actuation control system used in the conveyor of  FIG. 1 ; and 
           [0014]      FIG. 7A-7C  are top plan views of the case-turning conveyor of  FIG. 1  illustrating its operation. 
       
    
    
     DETAILED DESCRIPTION 
       [0015]    One version of a case-turning conveyor embodying features of the invention is shown in  FIG. 1 . The conveyor  10  includes a conveyor frame  12  mounted on legs  14 . The frame includes a pair of side walls  16 ,  17  that confine conveyed articles, such as packages, and serve as mounts for various conveyor components. Articles are conveyed along the conveyor by a pair of side-by-side conveyor belts  18 ,  19 , both advancing in a direction of belt travel  20 . In general, one of the belts travels at a high speed  22  and the other at a low speed  23 . But both belts could travel at the same speed. Both belts have rows of article-supporting rollers  24  mounted on axles  26  ( FIG. 2 ) parallel to the direction of belt travel. This allows the rollers to rotate perpendicular to the direction of belt travel as indicated by two-headed arrow  28 . 
         [0016]    The endless belts are trained around drive and idle sprockets  30 ,  31 , which engage the belts at opposite ends of the conveyor to drive them in the direction of belt travel. The sprockets are mounted on a pair of drive shafts  32  and idle shafts  33 . The sprockets for one of the drive shafts and one of the idle shafts engage one of the conveyor belts; the sprockets for the other drive shaft and idle shaft engage the other belt. The idle shafts  33  are supported at outside ends in shaft bearings  34  mounted to the side walls of the conveyor. Shaft bearings (not shown) for the inside ends of the idle and drive shafts are mounted to the conveyor frame under the abutting portions of the two belts. The outside ends of the drive shafts are coupled to motors M 1 , M 2  through gearboxes  36 . The motors drive the drive shafts to advance the belts in the direction of belt travel. 
         [0017]    The belts are supported just inward of the sprockets on narrow rails  38  that contact the inner sides of the belt between consecutive rollers. The belts are supported on a roller-actuating mechanism  40  along a major portion of the length of the conveyor. Articles entering and exiting the conveyor ride across roller transfer plates  42 . A sensor, such as a photo eye including a photo emitter, is mounted to one of the side walls at the entrance to the conveyor. A reflector  45  on the side wall opposite the photo eye reflects emitted light back to the photo eye unless the light beam is occluded by an article entering the conveyor. But any sensor capable of detecting the presence of an article entering the conveyor could be used instead of a photo eye. Also mounted to the conveyor frame are input/output devices  46 , such as relay units, forming an interface between the conveyor and a programmable logic controller (PLC). 
         [0018]    The roller-actuating mechanism  40 , as shown in  FIGS. 2-4 , comprises an array of small actuating rollers  48  mounted on axles  50  supported in geared rotary carriers  52 . A pinion gear  54  at the bottom of each rotary carrier rides along a slot  56  in an actuator plate  58 . Teeth  60  formed on one side of the slot mesh with the teeth of the pinion gear to rotate the rotary carrier and change the direction of rotation of the actuating roller as the actuator plate translates laterally in the width direction of the conveyor. The slot teeth form a rack gear for each rotary carrier. 
         [0019]    The rotary carriers extend through circular openings  62  in a carryway pan  64  affixed to the conveyor frame. The carryway pan fixes the position of the actuating rollers in the array and allows each rotary carrier to rotate in its opening. The pan is attached to a lower bottom plate  66 , also affixed to the conveyor frame. Small openings  67  in the bottom plate for each roller rotatably receive lower stems  68  at the bottom of each rotary carrier to provide stability. The pan and the bottom plate are fastened together and spaced apart by spacers  70 . A series of actuator plates  58  are sandwiched between the pan and the bottom plate. The actuator plates, which extend across the width of the conveyor, are free to translate laterally, as indicated by arrow  72 , to rotate the rotary carriers. 
         [0020]    The actuator plates, or gear racks  58 , are pulled left or right or centered by actuators, such as linear actuators or pneumatic cylinders  74 ,  74 ′. Each pair of opposed cylinders, whose rods  76  are joined by an adjustable coupling  78 , is arranged to translate one of the gear racks. Threaded ends  80  of the piston rods  76  are received in a threaded bore  82  in the adjustable coupling. The coupling allows the cylinder rods to be adjusted to provide the correct amount of gear-rack translation. The closed ends of the cylinders are attached to cylinder mounts  84 ,  85  by clevises  86 ,  87 . One of the cylinder mounts  85  is stationarily affixed to the lower side of the bottom plate. The other mount  84  has a pair of slots  88  that allow it to slide along the lower side of the bottom plate. Pins  90  extending from the slotted mount  84  through a slot  92  in the bottom plate connect to the corresponding gear rack  58 . In this way, the gear rack translates with the slotted cylinder mount. 
         [0021]    The operation of one gear rack  58  of the roller-actuating mechanism  40  is illustrated in  FIGS. 5A-5C , which show a cross section of the conveyor looking upstream opposite to the direction of belt travel for three conditions. In  FIG. 5A , the belt rollers  24  are actuated to push conveyed articles to the left, as indicated by arrow  90 . The belt rollers protrude through the thickness of the belt  18 ,  19  into contact with the peripheries of the actuating rollers  48 , whose rotary carriers  52  are shown rotated to their maximum counterclockwise position. In this orientation, the tops of the belt rollers rolling on the obliquely oriented actuating rollers rotate toward the left as the belts advance in the direction of belt travel. The rotary carriers are rotated into this position by the gear rack  58 , which is shifted to the left in  FIG. 5A  by the pneumatic cylinders  74 ,  74 ′. In this condition, both cylinders are in their fully retracted positions, as indicated by the short extension of both piston rods  76 , which pulls the gear rack  58  all the way to the left edge  92  of the sandwich formed by the pan  64  and the bottom plate  66 . 
         [0022]    In  FIG. 5B , the cylinders are shown with their rods  76  both fully extended, pushing the gear rack  58  to is rightmost position at the right side  93  of the sandwich. This causes the gear rack to rotate the rotary carriers fully clockwise to change their orientation and the axes of rotation of the actuating rollers  48  into an oblique orientation facing the other side of the conveyor. Now, as the belts advance in the direction of belt travel, articles supported atop the belt rollers  24  are pushed toward the right, as indicated by arrow  91 , as the belts advance in the direction of belt travel. 
         [0023]    The article-supporting belt rollers  24  may be braked as shown in  FIG. 5C . In this condition, the piston rods  76  of one of the pneumatic cylinders  74 ′ is retracted while the rod of the other cylinder  74  is extended. This centers the gear rack  58  in the sandwich and aligns the axles of the actuating rollers perpendicular, and not oblique, to the direction of belt travel into the axles  26  of the belt rollers. This allows the belt rollers to ride along the orthogonally positioned actuating rollers without rotation. 
         [0024]    As shown schematically in  FIG. 6 , the conveyor is controlled by a controller  94  such as a PLC. Other controllers, such as PC&#39;s or special-purpose processors, may be used instead. Input/output devices  46  local or remote to the PLC route sensor input to and control signals from the PLC. For example, the photo eye  44  changes state whenever the light beam crossing the entrance of the conveyor is blocked by the presence of a conveyed article. The photo eye signal  96  is used to indicate that an article is entering the conveyor. The PLC can also control the speeds of the two conveyor belts by changing the speeds of their motors M 1 , M 2  by signals on motor control lines  97 ,  97 ′. And each of the pairs of pneumatic cylinders  74 ,  74 ′ associated with each gear rack can be controlled by signals on signal lines  98 A,  98 A′- 98 X,  98 X′ from the PLC via the input/output devices  46 , such as relay units. 
         [0025]    The process of turning a case 90° according to the invention is illustrated in  FIGS. 7A-7C . In  FIG. 7A , an article in the form of a rectangular package  100  enters the case-turning conveyor  10  straddling both belts  18 ,  19  and with its short edge  102  leading (easy way). The right-hand belt advances at a first speed s 1  greater than the speed s 2  of the left-hand belt  19 . As soon as the leading edge of the package interrupted the light beam  104  at the entrance to the conveyor, the photo eye sensor  44  signaled the PLC. Upon receiving the package-entry signal, the PLC actuated the upstream-most gear rack to rotate its associated rotary carriers  50 A and their actuating rollers  48 A through a 45° angle toward the right side  104  (looking downstream) of the conveyor. The actuating rollers controlled by the upstream-most gear rack form a first actuation zone Z A  that extends across the width of the conveyor just downstream of its upstream end  106 . The belt rollers  24 A, which roll on the obliquely oriented actuating rollers  48 A in zone Z A  and support the leading edge of the package, rotate toward the left side  105  of the conveyor, as indicated by arrows  108 , as the belts advance. The leading edge, which is urged toward the slower belt  19  by the speed differential of the two belts, is further pushed in that direction by the rotation of the article-supporting rollers in zone Z A . All the actuating rollers downstream of zone Z A , such as those in zone Z B , are oriented with their axes  110  perpendicular to the direction of belt travel. As the leading edge  102  of the package advances along the length of the conveyor, the PLC times the actuation and direction of the actuating rollers and subsequent actuation zones so that the leading edge is always subjected to a leftward lateral force by its supporting belt rollers. So, depending on the speed of the motors and with knowledge of the turning characteristics of the package, the PLC can sequentially actuate successive zones to continue to push the leading edge of the package toward the left. And, as the leading edge clears a zone, the PLC can quickly deactuate that zone to prevent the belt rollers from urging the middle of the package toward one side or the other. 
         [0026]      FIG. 7B  shows the trailing edge  103  just entering zone Z A . The rollers in Z C  under the leading edge  102  of the package are actuated to continue the push of the leading edge toward the slower belt  19  on the left. The rollers just behind, in zone Z B , supporting the middle of the package are deactuated in their brake position and exert no lateral force on the package. The rollers in zone Z A  are actuated by the PLC to push the trailing edge of the package toward the faster belt  18  on the right side  104  of the conveyor. Consequently, in zone Z A , the actuating rollers  48 A are oriented obliquely at 45° toward the left side  105  of the conveyor to cause the belt rollers to push the trailing edge of the package in the direction of arrows  109 . By actuating the belt rollers under the leading edge of the package to rotate toward the slower belt and actuating the rollers under the trailing edge to rotate toward the faster belt, the PLC can accelerate the turning of the package in a shorter distance along the length of the conveyor. 
         [0027]    As shown in  FIG. 7C , in which the package  100  is almost turned fully 90° with its long side leading (hard way), the leading short edge  102  is in actuation zone Z E  and the trailing short edge is in zone Z D . In this situation, the belt rollers in zone Z E  are actuated to push the leading short edge toward the left side  105  of the conveyor and the belt rollers in zone Z D  are actuated to push the trailing short edge toward the right side  104 . And the rollers in zone Z F  ahead of the package and in zones Z C  and Z B  now behind the package are deactuated, awaiting the arrival of the leading edge of a subsequent package  100 ′, just entering newly actuated zone Z A  to undergo the same case-turning process. 
         [0028]    The total length along the conveyor of the actuation zones, the shape, weight, and frictional characteristics of the packages, the maximum speeds of the belts, and the desired degree of package turning are all important factors in determining at what speeds to run the belts and how much conveyor length is required to turn the packages as desired before feeding them off the downstream end of the conveyor. To prevent packages from turning past the desired goal, the PLC could start advancing the belts at the same speed once a leading package reached one of the downstream zones at which it should have been fully rotated and until that package reached the exit end of the conveyor. Then, the PLC could return the two belts to their normal differential speeds to turn the trailing package. Of course, it would be possible to select just the right length of conveyor or the number of zones to actuate to turn packages of various characteristics. 
         [0029]    Although the invention has been described in detail with respect to a preferred version, other versions are possible. For example, multiple sensors could be spaced along the length of the conveyor, such as one per actuation zone, to give the PLC a realtime indication of a package&#39;s position to control the actuation zones, rather than having the PLC rely on a timing sequence triggered by just a single package sensor at the entrance of the conveyor. Likewise, the PLC could control the absolute, as well as the relative speeds of the two belts. So, as these few examples suggest, the scope of the claims is not meant to be limited to the preferred version described in detail.