Abstract:
An improved segment wheel assembly for an article packaging machine is provided for picking individual carton blanks from a magazine and delivering the carton blanks to a conveyor to be carried to a packaging station of the machine. The segment wheel assembly has a pair of generally cylindrical segment wheels spaced apart from each other in end-to-end relationship. An unobstructed space is defined between the spaced segment wheels and each segment wheel has a generally rectangular cutout with the cutouts being aligned. A pick arm assembly including suction cups is disposed within the unobstructed space. A drive train rotates the segment wheels in unison and, simultaneously, oscillates the suction cup back and forth within the unobstructed space. The suction cup repeatedly grabs single carton blanks from the magazine and pulls them toward the rotating segment wheels, whose cutouts engage each carton blank and urges it toward and into the conveyor.

Description:
TECHNICAL FIELD 
     This invention relates generally to carton packaging machines and more particularly to segment wheel assemblies of such machines for picking single carton blanks from a magazine and delivering the carton blanks to a conveyor. 
     BACKGROUND 
     It is well known in carton packaging machines to utilize segment wheel assemblies to pick single carton blanks from a magazine of back-to-back blanks and position the blanks on a conveyor. The conveyor generally then transports the carton blanks to in a single file end-to-end relationship to an area of the packaging machine where they are folded around or packed with articles such as, for example, beverage cans. U.S. Pat. No. 6,497,084 of Janen, which is owned by the assignee of the present invention, discloses a carton blank transport apparatus that includes a traditional segment wheel assembly and conveyor for the aforementioned use, and this patent is hereby incorporated fully by reference. 
       FIGS. 1 and 2  below illustrate in somewhat simplified form a traditional and well known prior art segment wheel assembly found in carton packaging machines. The prior art assembly  11  comprises a first segment wheel  12 , generally in the shape of a disc, and a similar second segment wheel  13 , that are mounted in spaced relationship on a rotatable segment wheel shaft  14 . The segment wheel shaft  14  is continuous and extends between the segment wheels  12  and  13 . The segment wheels  12  and  13  ride on respective nip rollers  22  and  23 , which also are rotatable. As shown in  FIG. 2 , each segment wheel is formed with a somewhat crescent-shaped cut-out  26  for purposes detailed below. 
     A pair of pick arms  16  and  17  are mounted on a pick arm shaft  18  disposed above the segment wheels. The pick arms extend downwardly between the segment wheels and are provided at their lower ends with suction cups  19  and  21 . Of course, associated suction lines, side plates, bearings, sprockets, and gears are associated with the segment wheel assembly  11  to operate the assembly as described below. Such associated machinery is well known in the art and thus need not be described in detail here. 
       FIG. 2  illustrates typical operation of the prior art segment wheel assembly an is a view taken along line A-A of  FIG. 1  so that only segment wheel  13  and pick arm  17  are shown. It will be understood that the other segment wheel and pick arm operate identically. In operation, a horizontal back-to-back stack of carton blanks  32  is located in a magazine adjacent the downstream end of the segment wheel assembly. The segment wheel  13  is rotated in a counterclockwise direction at a predetermined speed, as indicated by arrow  28 , while the nip roller  23  is rotated in a clockwise direction as indicated by arrow  29 . As the segment wheel and nip roller are rotated, the pick arm  17  is articulated back and forth by the articulating pick arm shaft  18 , as indicated by arrows  31 . The range of articulation is predetermined so that the suction cup  21  swings toward and contacts a carton blank on the end of the stack  32 . 
     The suction cup grabs the end blank of the stack and, as the pick arm begins to articulate back, pulls the blank to the right in  FIG. 2  against the rotating segment wheel  13 . The timing of this motion is such that the cutout  26  of the rotating segment wheel  13  passes the top of the carton blank, which drops into the cutout. The pick arm then releases the blank and articulates on up to the right and out of the way. As the segment wheel continues to rotate, the lip  27  of its cutout  26  pulls or urges the top of the carton blank down against the rotating nip roller  23 . The blank then becomes captured between the nip roller and the segment wheel and is thereby drawn to the right and delivered to a conveyor (not shown), which conveys the blank to the right as indicated by arrow  33  to be delivered to a packaging area of the packaging machine. The just described motion of the segment wheel assembly repeats over and over. In this way, carton blanks are drawn one at a time from the stack  32  and delivered in single file edge-to-edge relationship to the conveyor. 
     While prior art segment wheel assemblies have proven reasonably successful, they nevertheless have been plagued with various problems and shortcomings inherent in their designs. The most serious of these, perhaps, is the fact the pick arm must be highly curved and convoluted as shown in  FIG. 2  in order to avoid hitting the segment wheel shaft  14  as the pick arm articulates. A closely related problem is that the lower end of the pick arm and thus the suction cup  21  also must be located relatively low so that it does not hit the segment arm shaft during operation. This means that the suction cup necessarily engages and grabs the carton blanks of the stack at a location substantially below the top edges of the blanks. This, in turn, causes a number of problems. For instance, since the blanks are being pulled against the segment wheels from a low position, substantial bowing of the blanks as they engage the segment wheels can occur. This bowing can cause flaps in the blank to pop open, misalignment of the blanks as they are delivered to the conveyor, and even machine jams on occasion. It would be much more desirable to grab the carton blanks nearer their top edges where end flaps typically are located. However, this has not been possible in the past because of the requirement that the suction cups clear the segment wheel shaft  14  as they move back and forth. 
     Accordingly, a need exist for an improved segment wheel assembly in which carton blanks are picked from a stack at or near their top edges rather than nearer their middle portions. More generally, a need exists for a segment wheel assembly wherein suction cups of the pick arm assembly can be positioned to engage blanks at any desired location. A further need exists for a segment wheel assembly with a simpler, more space efficient, and less convoluted pick arm configuration. It is to the provision of a segment wheel assembly that addresses these and other needs that the present invention is primarily directed. 
     SUMMARY OF THE INVENTION 
     Briefly described, the present invention, in one preferred embodiment thereof, is an improved segment wheel assembly that addresses the problems and shortcomings of the prior art. The segment wheel assembly comprises a pair of spaced apart segment wheels in the shape of horizontally aligned cylinders closed at one end. Each segment wheel or cylinder has a separate shaft secured to and projecting from its closed end and the shafts are rotatably journaled in appropriate bearings on respective side plates of the assembly. Thus, unlike the prior art, there is no segment wheel shaft that extends across the entire assembly. Instead, the space between the facing ends of the segment wheels is open and free of any obstruction. Each segment wheel cylinder is machined with an open slot along one side and the slots of each segment wheel also are aligned with each other. The drive train of the assembly rotates each of the separated aligned segment wheels in unison so that the slots always align and rotate with each other. 
     A pair of pick arms are mounted on an articulating shaft above the segment wheels. The pick arms extend downwardly into the open and unobstructed space between the facing ends of the segment wheels and are provided on their lower end portions with suction cups for grabbing carton blanks from a magazine as described above. Since the space between the segment wheels is open and unobstructed, the pick arms can be straight or substantially straight, or at least less convoluted as needed, because there is no shaft in the space to be avoided as the arms articulate. More importantly, however, the suction cups can be positioned on the pick arms so that they engage cartons in the magazine at or near the top edges of the cartons or at any more desirable location. Thus, the problems caused in the prior art from bowing of cartons during the selection process is eliminated. Further, since the pick arms are simpler, the space between the segment wheels can be narrower than in the prior art, which, in combination with the more desirable selection of carton blanks from their top edges, allows the assembly to function with narrower carton blanks than the prior art. 
     These and other features, objects, and advantages of the spaced segment wheel assembly of this invention will become more apparent upon review of the detailed description set forth below, when taken in conjunction with the accompanying drawing figures, which are briefly described as follows. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  illustrates key components of a typical prior art segment wheel assembly, discussed above, as seen from the upstream end thereof. 
         FIG. 2  is a view of the prior art segment wheel assembly taken along line A-A of  FIG. 1  and illustrating typical operation of such assemblies and the problems caused by the continuous segment wheel shaft. 
         FIG. 3  is an end view, from the upstream end thereof, of a segment wheel assembly that embodies principles of the present invention in a preferred form. 
         FIG. 4  is an end view of the segment wheels and pick arms of the segment wheel assembly of  FIG. 3  as seen from the downstream end thereof. 
         FIG. 5  is a view of the segment wheel assembly taken along line B-B of  FIG. 4  and illustrating the improved operation of the segment wheel assembly of this invention. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       FIGS. 1 and 2 , which illustrate the prior art, have been discussed above in the Background section. Reference is now made in more detail to the remaining drawing figures, which illustrate the present invention in a preferred embodiment considered by the inventors to be the best mode of carrying out the invention.  FIG. 3  is a view of the segment wheel assembly of this invention as seen from the downstream end thereof; that is, from the end to which stacked back-to-back carton blanks are fed from a magazine. The segment wheel assembly  41  comprises a first side plate  42  and a second side plate  43 , between which key components of the assembly are supported. A first segment wheel  44  is rotatably mounted to side plate  42  and a second segment wheel is rotatably mounted to side plate  43 . More specifically, the first segment wheel is configured as a cylinder that is open on its right hand side in  FIG. 3  and closed at its left hand side. A generally rectangular cutout  47  is formed on one side of the segment wheel  44  and a shaft  49  is fixed to and projects to the right of the closed end of the segment wheel. The shaft  49  is rotatably journaled in and extends through a bearing assembly  52  mounted to the end plate  42 . A sprocket  54  is mounted to the end of the shaft  49  on the outside of the end plate  42 . It will thus be seen that rotation of the sprocket  54  causes the segment wheel  44  likewise to rotate. 
     Similarly, a second segment wheel  46 , which is a mirror image of the first segment wheel  44 , has a rectangular cutout  48  and is rotatably mounted to the end plate  43  by means of a shaft  51  that is journaled in and extends through a bearing assembly  53 . A sprocket  56  is mounted to the end of the shaft  51  on the outside of end plate  43  so that rotation of the sprocket  56  causes the second segment wheel  46  likewise to rotate. The cylindrical segment wheels are mounted in opposed horizontally aligned and spaced apart relationship with respect to each other. Most significantly, since the shafts  49  and  51  are fixed to the closed ends of the segment wheels  44  and  46  respectively, there is no shaft that extends across the entire width of the assembly as in the prior art. Thus, the space between the opposed segment wheels  44  and  46  in the center of the assembly is completely open and unobstructed. 
     A drive shaft  57  extends between the end plates  42  and  43  at the bottom of the assembly and its ends are rotatably journaled in and extend through respective bearing assemblies  58  and  59 . A sprocket  61  is secured to the left hand end, in  FIG. 3 , of the drive shaft  57  on the outside of end plate  42 . Similarly, a sprocket  62  is secured to the right hand end of the drive shaft  57  on the outside of end plate  43 . A drive chain  63  (shown here in phantom line for clarity of illustration) extends around the sprocket  54  and the sprocket  61  on the left of the assembly and is appropriately tensioned by means of an idler sprocket  66 . Similarly, a drive chain  64  (shown in phantom line) extends around sprocket  56  and sprocket and sprocket  62  on the right side of the assembly and is appropriately tensioned by idler sprockets  66 . With this arrangement, it will be appreciated that rotation of the drive shaft  57  by a drive motor (not shown) causes the segment wheels  44  and  46  to rotate in unison. Further, the sizes of the sprockets are selected so that the segment wheels rotate at the same rate of rotation. In this way, the rectangular cutouts  47  and  48  formed in respective segment wheels  44  and  46  remain always aligned with each other, as illustrated, as the segment wheels are rotated by rotation of the drive shaft  57 . 
     Nip rollers  67 , which preferably are made of a rubberized or otherwise high friction material, are mounted beneath the segment wheels  44  and  47  and may engage the segment wheels. The nip rollers may be separately rotatable at a desirable speed or may rotate with the segment wheels. Conveyor chains  69  are shown between the nip rollers. The conveyor chains  69  are part of a conveyor assembly that extends downstream of the segment wheel assembly and to which carton blanks are fed by the segment wheel assembly. The conveyor assembly itself is traditional and not part of the present invention and thus it is not shown or described in detail here. However, reference is made to U.S. Pat. No. 6,497,084 incorporated by reference above, which discloses a typical packaging machine conveyor assembly. The conveyor chains  69  may include dogs  70 , which, as is known in the art, align and space single carton blanks on the conveyor assembly as the blanks are conveyed from the segment wheel assembly  41  to downstream areas of the packaging machine where they are packed with articles such as, for instance, beverage cans. 
     A pick arm assembly  71  is mounted between end plates  42  and  43  above the spaced segment wheels  44  and  46 . The pick arm assembly comprises a pick arm shaft  72  that is rotatably journaled in and extends through bearing assemblies  73  and  74  on the end plates. A first pick arm  76  and a second pick arm  77  are secured to the pick arm shaft  72  at its mid section. As described in more detail below, the pick arms  76  and  77  extend downwardly into the unobstructed space between the segment wheels  44  and  46  as shown. A first suction cup assembly  78  is mounted, preferably adjustably, to the first pick arm  76  and is positioned between the segment wheels. A second suction cup assembly  79  is mounted, again preferably adjustably, to the second pick arm  77  and likewise is positioned between the segment wheels, all as shown in  FIG. 3 . 
     A crank assembly  81  operatively links the segment wheels to the pick arm assembly and thus to the pick arms  76  and  77 . More specifically, a crank wheel  83  is operatively secured to the end of the pick arm shaft  72  on the outside of end plate  42 . A corresponding crank wheel  82  is secured to the end of the segment wheel shaft  49  outboard of the sprocket  54  so that the crank wheel  82  rotates with the sprocket  54  and thus with the segment wheels  44  and  46 . The crank wheel  83  is provided with an off-center crank lug  87  that projects outwardly from the crank wheel. Likewise, the crank wheel  82  is provided with an off-center crank lug  86 . A crank arm  84  links and is rotatably coupled to the crank lugs  86  and  87 . 
     In operation, the crank lugs are strategically located on their respective crank wheels so that rotation of the segment wheels  44  and  46  and, consequently, rotation of the crank wheel  82  causes the pick arm crank wheel  83 , and thus the pick arm shaft  72 , to rotate back and forth through only a portion of a full arc. This, in turn, causes the pick arms  76  and  77  and their suction cup assemblies  78  and  79  to move or oscillate back and forth in a direction generally normal to the page in  FIG. 3 . The precise nature of this oscillation and its purpose is described in more detail below. 
     With the just described arrangement, it will be seen that when the drive shaft is rotated, the segment wheels rotate in unison while the pick arms and suction cups oscillate back and forth in the unobstructed space between the segment wheels. The nip rollers also rotate against the segment wheels and, separately, the conveyor chains are driven so that their top flight moves downstream away from the segment wheel assembly  41 . 
       FIG. 4  is an enlarged view of the segment wheels, pick arm assembly, and nip rollers of the segment wheel assembly  41 , this time as seen from the upstream end of the segment wheel assembly. The cylindrical segment wheels  44  and  46  are seen rotatably mounted to the end plates as described above on individual shafts  49  and  51  respectively. The generally rectangular cutouts  47  and  48  formed in the segment wheels are more clearly visible in  FIG. 4 . Nip rollers  67  are rotatably mounted beneath the segment wheels and the pick arm assembly  71  is shown with its pick arm shaft  72 , pick arms  76  and  77  extending into the space between the segment wheels, and suction cup assemblies  78  and  79  mounted to the lower end portions of the pick arms within the space. It should be recognized that the suction cup assemblies and their suction cups are located in the unobstructed space between the segment wheel assemblies. More importantly, they are vertically positioned at a location occupied, in the prior art, by a segment wheel shaft (see  FIG. 1 ). Such positioning of the suction cup assemblies heretofore has not been possible, as described above, because of the requirement to avoid interference with the segment wheel shaft. In any event, as detailed above, as the segment wheels  44  and  46  are rotated in the direction indicated by arrows  85 , the pick arms and suction cups oscillate back and forth in a direction generally normal to the page in  FIG. 4 . 
       FIG. 5  is a view taken along B-B of  FIG. 4  and perhaps best illustrates the operation of the segment wheel assembly of the present invention, at least in one embodiment thereof. It should be understood that in  FIG. 5  as in other figures, the elements have been simplified and many elements known in the art and not part of the invention, such as the infeed magazine, outfeed conveyor, suction lines, etc., are not shown, all for clarity of description and understanding of the invention. Referring to  FIG. 5 , cylindrical segment wheel  44  is seen from its open end so that the end of cutout  47  is visible around the circumference of the segment wheel  44 . Pick arm  76  is mounted to pick arm shaft  72  and extends downwardly into the space between the segment wheels. In  FIG. 5 , pick arm  76  is illustrated as a simple straight metal arm. However, in practice, the arm can take on any of a number of application specific shapes or configurations to, for example, provide for a desired orientation and placement of the suction cup. Further, the pick arm need not be a single piece of metal but can, in fact, be a more complex multi-part assembly to provide adjustment and placement options, as needed. A suction cup assembly  78  is mounted to the lower end portion of the pick arm and, in the illustrated embodiment, is seen to be adjustable in position by means of a mounting slot  94 . Nip roller  67  is mounted beneath the segment wheel  44  and rotates therewith or is separately rotated, as discussed above. 
     Operation of the segment wheel assembly of this invention will now be described with reference to segment wheel  44  and pick arm  76  shown in  FIG. 5 . Operation of the other segment wheel  46  and pick arm  77 , not shown in  FIG. 5 , is identical. The purpose of the segment wheel assembly is to pick single carton blanks from a stack of back-to-back carton blanks  88  that are fed to the segment wheel assembly from the left in  FIG. 5  (i.e. from the upstream end of the segment wheel assembly) on a magazine (not shown). Individual carton blanks are then delivered single file and in a flat edge-to-edge orientation to a conveyor (not shown) on the right or downstream end of the segment wheel assembly. As discussed above, the conveyor then carries the carton blanks to an area of the packaging machine where they are packed with product, as is known in the art. 
     To accomplish the above purpose, segment wheel  44  with its rectangular cutout  47  is rotated in a counterclockwise direction as indicated by arrow  89 . At the same time, nip roller  67  rotates or is rotated in a clockwise direction as indicated by arrow  91 . As the segment wheel  44  and nip roller  67  rotate, pick arm  76  and its suction cup assembly are oscillated by pick arm shaft  72  in a back and forth direction, as indicated by arrows  92 . The timing of the rotation and oscillation, as determined by the configuration of the crank assembly, is such that the suction cup moves toward the stack  88  of carton blanks as the rectangular cutout  47  rotates around toward the blanks. The suction cup engages and grabs the end-most blank of the stack  88  and begins to oscillate back to the right in  FIG. 5 . This pulls the upper edge portion of the blank toward the rotating segment wheel until the upper portion of the blank engages the segment wheel. Because of the unobstructed space between the segment wheels, the suction cup can be adjusted to any desired location within the space so that it engages the carton blank at precisely the desired location, which may be near the top edge of the blank. This eliminates the bowing and attendant problems common in prior art segment wheel assemblies. 
     Shortly after the carton blank engages the segment wheel  44 , the rectangular cutout  47  of the segment wheel  44  rotates past the upper edge portion of the blank. The upper edge portion of the blank, aided by the moving suction cup, falls and/or is pulled into the rectangular cutout at the leading edge thereof. As the segment wheel continues to rotate, the trailing edge of the rectangular cutout engages the upper edge portion of the carton blank on the back side of the blank, the suction cup disengages and moves out of the way to the right, and the trailing edge of the cutout begins to urge the upper edge portion of the carton blank downwardly toward the bottom of the segment wheel and toward the nip roller  91 . When the upper edge portion of the carton blank engages the nip roller  91 , it is captured by the rubberized nip roller, which ejects the carton blank to the right, as indicated at  93  and  98  in  FIG. 5 . During this process, the carton blank is captured by the conveyor (not shown) and conveyed downstream of the segment wheel assembly to a packing area of the packaging machine. The just described process of selecting individual carton blanks from the stack  88  repeats continuously, thereby delivering cartons continuously in horizontal, single file, edge-to-edge relationship to the conveyor. 
     It will thus be seen that the segment wheel assembly of this invention provides numerous advantages and improvements over prior art segment wheel assemblies of the type shown in  FIGS. 1 and 2 . Perhaps the primary advantage is that the unobstructed space between the segment wheels eliminates convolutedly shaped pick arms of the prior art that are configured to move around and avoid hitting a segment wheel shaft, and the consequent limited and usually lower-than-desirable suction cup positioning of the prior art. Instead, a simple pick arm or pick arm assembly can be used and the suction cup can be positioned at virtually any location between the segment wheels to engage and grab carton blanks near their upper edge portions, or at any other desired location, to obtain most efficient operation. Further, the relatively long rectangular cutouts in the cylindrical segment wheels of this invention adapt automatically to carton blanks of different widths without having to move disc-shaped segment wheels closer or further apart on their shafts as in the prior art. Narrower cartons can also be accommodated more easily with the unique spaced apart segment wheel assembly of the present invention. 
     The invention has been described herein in terms of preferred embodiments and methodologies considered by the inventors to be the best mode of carrying out the invention. It will be apparent to those of skill in the art, however, that various additions, deletions, and modifications might be made to the illustrated embodiments within the scope of the invention. For instance, as mentioned above, the pick arm or pick arm assembly can be shaped other than as shown or can comprise multiple components if desired to provide for appropriate range of adjustment of the suction cup assembly and other purposes. Further, while cylindrical segment wheels with rectangular cutouts are considered preferable, segment wheels of other shapes also might be substituted. For example, it may be possible to substitute traditional disc-shaped segment wheels on separate shafts with an unobstructed space between the segment wheels. Indeed segment wheels of many configurations might be substituted for the preferred cylindrical segment wheels, and such will be equivalent to the segment wheels of the preferred embodiments. Finally, while the particular drive train shown in the preferred embodiment also is preferred, other drive train configurations certainly are possible. These and other modifications to the illustrated and preferred embodiments may be made by skilled artisans without departing from the spirit and scope of the invention as set forth in the claims.