Abstract:
An improved bagger or bag dispenser for supplying bags attached to strips in a bag assembly to a workstation includes a reversible drive that pulls the bag assembly from a supply to the work station and returns unused bags to the supply when changing bag assemblies. The bagger includes a winding spool having tapered ribs and valleys.

Description:
This application claims the benefit of U.S. Provisional Application No. 60/718,523 filed Sep. 19, 2005. 

   FIELD OF THE INVENTION 
   The invention relates to bag dispensers or baggers that supply bags to a workstation, and in particular to bag dispensers or baggers in which the lead end of a bag assembly is wound on to a take-up reel or roller and related methods. 
   BACKGROUND OF THE INVENTION 
   Foods products, such as meat, cheese and the like, are conventionally packaged in plastic bags at workstations. Packaged foods products must carry product information such as packaging date and product source information. Product information is commonly printed on the bags. 
   Baggers or bag dispensers that supply printed bags to workstations are available. These devices include a drive that moves the bags from a supply of bags to the workstation. The bags pass a printer that prints product information on exposed sides of the bags before the bags reach the workstation. 
   Bags are supplied by the manufacturer as an indefinite-length bag assembly, either as a roll of bags or as a shingled bag assembly stored in a box. The bags are spaced along the length of the bag assembly. With shingled bag assemblies, lead ends of the bags are adhered to tape strips and trailing ends overlie each other. The tape strips are fed through the device from the box to the workstation. The bags are removed from the tape strips at the workstation. 
   Glatfelter, Jr. U.S. Pat. No. 6,837,023, assigned to the common assignee of this application, is incorporated herein by reference and discloses a bagger that is intended for high-production workstations where product is automatically bagged and sealed. The bagger reliably prints product information on bags of a shingled bag assembly. The two tape strips on the lead end of the bag assembly are attached to a take-up reel so that rotation of the reel by a drive motor pulls the bag assembly to the workstation. The tape strips are wound on the reel as the bag assembly is pulled through the bagger. 
   Workstations typically process production runs requiring different size bags for different size products. The bagger described in U.S. Pat. No. 6,837,023 is intended to be used with different size bags. When changing bag assemblies to change bag size the tape strips of the installed bag assembly are cut near or at the take-up reel, the bags on the lead end of the installed bag assembly are stripped off the tape strips and the assembly is removed from the bagger. The strips at the lead end of the removed assembly can easily be wound onto the reel when the assembly is reinstalled in the bagger. A new bag assembly with different sized bags is then installed in the bagger. The unused bags stripped from the removed bag assembly are discarded and wasted. 
   Conventional bag dispenser take-up reels are rotated by air ratchet drive motors. This type motor rotates the take-up reel through a fixed angle per each ratcheting motion. Each extension of an air cylinder advances the bag assembly a predetermined distance, typically about 0.25 inches. The operator cannot adjust this distance to correct the position of a bag assembly misaligned at the printer or the loading station. 
   Conventional take-up reels pull each tape strip in unison. After prolonged operation, one tape strip will often lag behind the other as the strips wind onto the reel. Tape strip lagging causes bags on the assembly to become misaligned at the printer or the loading station and may cause jams in the dispenser. 
   The bags are expensive. It is desirable to reduce operating cost by eliminating bag waste during operation of the bagger and when changing from one bag assembly to another. 
   SUMMARY OF THE INVENTION 
   The invention is an improved bagger or bag dispenser in which the drive that pulls the bag assembly through the machine is reversible to unwind tape strips from the reel and permit return of unused bags to the box or back on the roll when changing bag assemblies. No bags are wasted when changing from one size bag assembly to another. Printed bags that are returned can have the prior printing wiped off or otherwise erased or covered for later re-printing. The weight of the bag assembly assists in unwinding the tape strips from the take-up reel. The path of the bag assembly through the device is configured such that the weight of the bag assembly assists in moving the bag assembly in the reverse direction past the printer and back to the supply. 
   The two tape strips are wound to form strip rings on the take-up reel. The reel preferably includes two spools specialized to facilitate winding and removal of wound tape strips. The spools are preferably made from thermoplastic plastic material to reduce adhesion to the wound tape strips and have circumferentially-spaced, outwardly or inwardly tapered ribs that support the strip rings and reduce the surface area contacting the strips. The tapered ribs facilitate tape winding and define grooves that allow easy removal of wound tape rings. 
   A reversible air stepper motor is used to rotate the reel. The air stepper motor allows fine control of take-up reel rotation, allows the operator to control the position of bags on the bag dispenser with high accuracy and allows reverse rotation of the reel to permit unwinding of tape strips from the rings during changeover from one size bag assembly to another size bag assembly. 
   The take-up reel has left and right spools and a differential spool drive that permits rotation of each spool at a differential speed to take-up tape strip slack when one tape strip lags behind the other tape strip. 
   Baggers or bag dispensers in accordance with the present invention reduce waste making it easier and more efficient to change bag assemblies and facilitate removal of strip rings. Other objects and features of the invention will become apparent as the description proceeds, especially when taken in conjunction with the accompanying drawings illustrating the invention, of which there are six sheets of drawings of two embodiments. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  is a side view, partially broken away, of a bagger in accordance with the present invention; 
       FIG. 2  is a top view of the view of the bagger taken along line  2 — 2  of  FIG. 1 ; 
       FIG. 3  is a top view of the take-up reel taken generally along line  3 — 3  of  FIG. 1 ; 
       FIG. 4  is a sectional view taken along line  4 — 4  of  FIG. 3 ; 
       FIG. 5  is a sectional view taken along line  5 — 5  of  FIG. 3 ; and 
       FIG. 6  is a perspective view of a second embodiment take-up reel for a second embodiment bagger. 
   

   DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     FIG. 1  illustrates bagger  10  having a frame  12 , a workstation  14  at the top of the frame and a bag printer assembly  16  mounted on one side of frame  12 . An indefinite length shingled bag assembly  18  is fed from box  20  mounted on the bottom of frame  12 , through printer assembly  16  and to station  14 . The printer assembly prints desired information, typically date and source information, on each bag in the bag assembly. 
   Bag assembly  18  includes two spaced, parallel indefinite length adhesive tape strips  22 . A plurality of generally rectangular shingled plastic bags  24  is adhered to strips  22 . The assembly  18  is fed downstream from box  20  to station  14  in the direction of arrow  26 . Each bag  24  is made from thin plastic film and has opposed sides  28 , an open lead end  30 , sealed trailing end  32  and sealed edges  34  extending between ends  30  and  32 . 
   As shown in  FIG. 1 , bag assembly  18  is fed from box  20  to printer assembly  16  with strips  22  on the top of the bag assembly and bag upstream or trailing portions  38  hanging down from the bottom of the assembly. The bag assembly is fed around lower roller  40 , through printer assembly  16 , around upper roller  42 , around the rounded edge  44  of workstation  14  and to slot  46  extending access the workstation. 
   At slot  46 , tape strips  22  are fed through selected guide recesses  50  in comb  48 . Recesses  50  facilitate feeding bag assemblies having tape strips with different spacing  52 . The recesses locate strip rings at desired locations on the elongate spools in the reel assembly. 
   Strips  22  extend through comb  48  and are wound on reel assembly  54 . Reversible drive motor  56  rotates reel assembly  54  in the direction of arrow  58  to feed bag assembly  18  from box  20 , through printer assembly  16  and to station  14 . Reversible motor  56  rotates reel assembly  54  via a belt drive  60  that includes a belt  62  extending from motor drive pulley or input member  64  to a driven differential wheel  66  on differential  68  of reel assembly  54 . See  FIG. 3 . Belt  62  includes teeth  63  which engage grooves on pulley  64  and wheel  66 . 
   Motor  56  selectively drives reel assembly  54  in response to control circuitry in a forward direction of rotation indicated by arrow  58  or in an opposite, reverse direction of rotation. A control circuit (not shown) enables a user to rotate the reel in a winding operating mode for supplying printed bags to workstation  14  or in a unwinding operating mode to remove or change bag assemblies. 
   If desired, motor  56  may be a pneumatic stepper motor that allows the tape strips  22  to be advanced along bagger  10  and wound around reel assembly  54  at precisely controlled distances or steps of as fine as 0.001 inch. The pneumatic stepper motor allows precise positioning of each bag  24  for printing and/or loading by bagger  10 . An electric stepper motor mat be used if desired. 
   The control circuitry may include a programmable logic controller (PLC) to control the pneumatic stepper motor  56 . 
   Reel assembly  54  has left and right reel halves  70  and  72  and a central differential assembly  76 . Each reel half has a drive shaft  74  extending the length of the reel half. Each shaft is connected to one output connection of differential  68  in assembly  76 . The differential assembly and shafts are rotatably supported on inboard bearing wall  78  and  80  mounted on frame  12 . Shafts  74  are coaxial. 
   Each reel half  70 ,  72  includes a tape winding spool  82  mounted on the end of shaft  74  extending outwardly from a bearing wall  78 ,  80 . Each winding spool  82  includes an elongate body  84  defining a cylindrical shaft passage  86  having a sliding fit on shaft  74 . Cross pin  88  extends through body  84  and shaft  74  to assure that the winding spool  82  rotates with shaft  74 . See  FIG. 4 . A circular inner flange  90  extends radially outwardly from the inner end of body  84  adjacent a bearing wall  78 ,  80 . As shown in  FIG. 3 , flange  90  has an inner side at the adjacent wall  78 ,  80  and outwardly tapered circumferential surface  92  extending from the edge of the flange radially inwardly and away from the adjacent wall. See  FIGS. 3 and 4 . 
   Six 60 degree-spaced longitudinally tape-winding ribs  94  extend radially outwardly from body  84  and from flange  90  to outer body end  98 . As shown in  FIG. 3 , the ribs  94  taper radially inwardly from flange  90  to end  98  to define six straight, tapered tape-winding surfaces  100 . The surfaces  100  faces radially outwardly and are equally spaced around the spool. Six longitudinal recesses or valleys  96  are located between adjacent ribs  94 . Strip rings  112  are wounded on surfaces  100  and have different interior diameters depending upon where the rings are located along the spools. 
   Shaft  74  extends beyond spool end  98  and is provided with a circumferential detent groove  102  located outwardly from end  98 . Optional spool end cap  104  is mounted on the free end of shaft  74  and carries a spring detent  106  engageable with groove  102  to hold the cap in place on the shaft. End cap  104  extends outwardly from shaft  74  and beyond the outer ends of tape-winding ribs  94 . Three 120 degree-spaced pins  108  extend through cap  104  parallel to the axis of shaft  74 . The inner ends of the pins  108  fit into valleys  96  between adjacent winding ribs  94  on body  84  to prevent rotation of the cap on the body. The outer ends of the pins extend outwardly beyond the cap to provide tie offs for the end of a tape strip wound on the spool. Radial slot  110  extends inwardly from the outer circumference of cap  104  to facilitate leading the strip end to an adjacent tie off pin  108  as illustrated in  FIG. 5 . 
   The operation of bagger  10  will now be described. 
   The bag assembly  18  is loaded on the machine by drawing the assembly from box  20  or a reel mounted on the frame, feeding the assembly through printer  16  and leading the assembly around edge  44  onto workstation  14 . A number of bags at the lead end of the assembly are removed from strips  22 . The strips are positioned in appropriately spaced recesses  50  in comb  48 . Each strip is then wound several times around a body  84  of an underlying winding spool  82  against the winding surfaces  100  on ribs  94 . Then, the free ends of the strips  22  are fed through slots  110  in end caps  104  and tied off onto the outer ends of pins  108  extending through the end caps. If end caps  104  are not used, the ends of the tape strip are fed through slots in the outer ends of the spools and held in recesses in the spool ends. Winding of the strips on to the spools may be facilitated by lifting up the portion of the workstation  14  to the right of slot  46  as shown in  FIG. 1  to provide access to the spools. 
   With the tape assembly in place in the machine, bagging operations are commenced as described in U.S. Pat. No. 6,837,023. Initial actuation of air motor  56  rotates the spools  82  in a winding direction to take-up slack in one or both strips  22  prior to feeding the bag assembly past printer  16  and onto the workstation  14 . 
   With continued operation of machine  10  the two strips  22  are wound onto the two winding spools  82  to form wound generally circular strip rings  112 . Each ring  112  is formed by a number of loops of adhesive tape strip  22  wound around a spool and adhered to each other. The strip forming each ring  112  is wound on the thin winding surfaces  100  at the ends of the six winding ribs  94  and has a generally hexagonal inner surface  114  defined by ribs  94  with straight cords  95  extending between adjacent ribs. The tape strips have low area contact with the winding spool  82  to facilitate removal of the strip ring from the spool. During winding, the location of the recess  50  guiding the strip to the spool and adhesive engagement with the ribs prevent the strip ring from migrating along the spool  82 . 
   The winding strip rings  112  are easily removed from spools  82  when machine  10  is deactivated. For instance, it may be desirable to remove the rings when they have grown to a maximum size prior to depletion of all of the bags in assembly  18 . In this case, motor  56  is reversed to unwind a length of strip from each of the rings. The rings are then severed from the unwound strips and caps  104  are removed from shafts  74 . The ends of the strips extending from the rings to the caps are cut away and discarded. The strip rings  112  are then easily removed from the winding spools by positioning a tool or the operator&#39;s fingers in valleys  96  between the strip rings and flanges  90  and withdrawing the strip rings from the spools. The height of ribs  94  decreases outwardly from the flanges  90  to assure that the strip rings, once dislodged from their winding positions, are free of the ribs during withdrawal. After the strip rings have been removed, the free ends of the strips extending from the bag assembly in machine  10  are reattached to the spools as previously described. 
   Change over from a bag assembly having strips at one spacing  52  to a bag assembly having strips at a different spacing  52  is easily accommodated without waste of bags. In this case, motor  56  is operated in a reverse direction to unwind sufficient lengths of strips from the strip rings to permit reverse feeding of the bag assembly back into the box without need for removing and discarding bags from the lead end of the assembly. The prior strip rings are removed and a new bag assembly with different spacing strips  22  is then installed as previously described. 
     FIG. 6  illustrates a second embodiment take-up reel assembly  116  similar to reel assembly  54 . Like reel assembly  54 , reel assembly  116  is mounted on frame  12  by bearing walls  118  and  120  and includes a differential assembly  122 , like assembly  76 , and left and right reel half  124  and  126 , like halves  70  and  72 . Each reel half has a drive shaft (not illustrated), like shaft  74 , joined to the differential and extending outwardly from the adjacent bearing wall. 
   Each reel half includes a winding spool  128  on a shaft extending outwardly from the differential assembly. Each spool  128  includes an elongate body  130  with the shaft extending into a cylindrical passage in the center of the body. The body includes an outer circumferential flange  132  and six 60 degree-spaced radial ribs  134  extending longitudinal from flange  132  inwardly to the inner end  136  of the body. The tape winding ribs  134  have narrow, straight tape winding surfaces  138  at the outer ends thereof, like surfaces  100 . Surfaces  138  taper radially inwardly from flange  132  to end  136 . Valleys  140 , like valleys  96 , extend longitudinally between adjacent ribs  134 . 
   Body  130  includes a handle  142  which extends outwardly from outer flange  132  and a spring detent (not illustrated) which engages a detent groove on the end of the shaft extending from the differential. The spring detent prevents accidental outward displacement of body  130  from the shaft. Inner circumferential flange  144  is mounted on the shaft and rotates with the shaft. When positioned on the shaft, the inner end  136  of body  130  engages a surface on flange  144  so that body  130  rotates with the shaft. The spring detent engagement between handle  142  and the shaft prevents disengagement of the rotary drive connection between the flange and body. 
   The take-up reel assembly  116  is rotated by a pneumatic step motor (not illustrated) similar to motor  56  through a drive belt (not illustrated) like belt  62 . The belt is wound around an output pulley on the motor and a drive wheel on differential assembly  122 , as illustrated in  FIG. 3 . 
   Flange  132  includes an inwardly sloping conical surface  146  extending from the outer edge of the flange radially inwardly and toward the adjacent bearing wall  118 ,  120 . Tape strip slots  148  are formed through the outer portion of flanges  132 . 
   The operation of a bagger with a second embodiment take-up reel assembly  116  will not be described. 
   The bag assembly is fed into machine  10  as described. Elongate tape strips from the lead end of the assembly are positioned in proper comb recesses  50  and wound around the ribs of each winding spool. The ends of the tape strips for each spool are fed through slots  148  in the outer flanges  132  and secured to handles  142 . The machine may then be operated as described with tape strips wound up on the reels to form generally circular strip rings like rings  112  engaging tape winding surfaces  138  on the ribs and having generally hexagonal inner surfaces like surfaces  114 . 
   When it is desired to remove the winding strip rings from the reels, the motor is reversed to unwind desired lengths of tape strips. The motor is then deactivated and the unwound length of tape strips and the tied off ends are severed from the strip rings. The winding spools  128  are then removed from the drive shafts and the strip rings are removed from the ribs by positioning a tool or the operator&#39;s fingers in the valleys between the ribs adjacent flange  132  and sliding the strip rings longitudinally past the inner body end  136 . 
   Following removal of the strip rings, the take-up reels are repositioned on the shafts with the inner ends  136  engaging rotary drive surfaces on inner flanges  144  and the spring detents seated in grooves in the ends of the shafts. The unwound tape strips are wound on the reels and secured to the handles as previously described for continued operation of the machine. 
   Conical surfaces  92  on flanges  90  and conical surface  146  on flanges  132  guide strips wound onto the reels, particularly during take-up of slack strips after strip rings have been removed or a new bag assembly has been installed. 
   The ribs in both spools  82  and  128  taper radially inwardly along the length of the spools to the small diameter ends of the spools to facilitate easy removal of strip rings wound on the spools independently of the longitudinal positions of the rings on the spools. 
   The winding spools and flanges are preferably formed from thermoplastic material but may be formed from metal or other material, as desired. 
   While I have illustrated and described preferred embodiments of my invention, it is understood that these are capable of modification, and I therefore do not wish to be limited to the precise details set forth, but desire to avail myself of such changes and alterations as fall within the purview of the following claims.