Abstract:
An apparatus is provided for cutting a film wrapped around a tray containing full bottles. The apparatus has a tray supporting surface formed with a pair of mirror image arcuate slots. A pair of knives are mounted to conveyor mechanisms to be driven in paths for cutting the film wrap on the bottom surface of the tray in the form of an X. A pair of adjustable side rails and a retracting stop are positioned to locate the tray for accurate film cutting. The knives travel sequentially to avoid interference as their paths intersect at the apex of each conveyor mechanism. Subsequent to cutting the film wrap, an operator is able to lift the film wrap off the tray and bottles to enable the bottles to be lifted and moved for creating a variety sales unit containing multiple drink flavors in the same tray.

Description:
FIELD OF THE INVENTION 
     The present invention relates to the field of packaging machinery, and more particularly to machinery for cutting a film wrap from trays prior to removing the film wrap to access the tray contents. 
     BACKGROUND OF THE INVENTION 
     Bottled drinks in flavors are very popular. These flavored bottled drinks may be intended for energy or performance enhancement, or simply to satisfy a thirst. Bulk merchandise stores, e.g. Costco, Sam&#39;s Club, are also popular since they give the customer an actual or perceived value by selling products in larger sales units. In this way, bulk merchandise stores have become a popular consumer source of flavored bottled drinks. 
     Bottling plants that provide these flavored drinks, for reasons of efficiency, produce and bottle a single flavor of drink for as long as possible. The bottling plant will fill bottles with a flavor, place the filled bottles in reusable shallow corrugated trays and wrap the trays with a transparent film sheet for storage and shipping. The packed tray may contain 12, 24 or other quantity of filled bottles. Trays are then placed on pallets for shipment. A bottling plant may fill and warehouse a single flavor drink for weeks before switching to a different flavor. 
     However, customers are expressing a preference to buy a variety of flavors rather than a tray containing 24 bottles of a single flavor. A demand has been found for bottled drinks in a tray containing a variety of flavors. In a tray, e.g. of 24 bottles, 6 bottles of each of four flavors has become a recently popular sales unit in the bulk merchandise stores. Since the bottling plants are set up to run long production batches of a single flavor, creating a variety sales unit tray must be treated as a secondary operation. The secondary operation, a mixing plant, will reuse the original trays for reasons of economy. 
     In the process of converting single flavor trays to multiple flavor trays, the film wrap covering the input single flavor tray noted above must first be removed before the bottles can be lifted and transferred to another tray. Current film wrap removal has been a fully manual operation in which the worker places the single flavor tray on a surface, inverts the tray and contents, cuts an “X” or other pattern through the film covering the tray bottom, re-inverts the tray to upright, and pulls the film up and off to expose the bottles, depicted in  FIGS. 1A-1D  of this application. A tray filled with 24 bottles containing 16 ounces of liquid each weighs approximately 50 pounds. In addition to the time involved and the strenuous act of inverting the tray of bottles twice, the manual cutting frequently damages the trays and may result in the worker sustaining cuts to the hands, worker injury and increased insurance costs. When a cut involves bleeding, the bottle processing operation must be shut down and disinfected according to Federal Food And Drug Administration regulations, a process that takes approximately 45 minutes. During this 45 minute cleaning, no production is accomplished on this conveyor line. 
     Therefore, a need exists for an apparatus for assisting in removing the film wrap from a tray of filled bottles that reduces the time and labor involved, reduces the damage to the trays, and eliminates the danger of worker injury. 
     SUMMARY OF THE INVENTION 
     The present invention provides an apparatus for cutting the film wrap covering a tray of filled bottles in a manner to overcome the drawbacks outlined above. The worker places the full, film-wrapped tray on a cutting table and presses two actuator switches simultaneously. A photoelectric curtain safety barrier is activated to guard against the worker placing a hand in the cutting area while the apparatus is operating. A pair of knives are driven sequentially along a pair of mirror image paths that approximate an X-shape, cutting the film wrap covering the bottom of the tray. The film is cut with minimum contact to the tray. The worker then grasps the film wrap on opposed sides of the tray and removes the film wrap, and the tray full of bottles is moved to the mixing station. The act of inverting the tray and bottles manually has been eliminated. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The present invention is best understood in conjunction with the accompanying drawing figures in which like elements are identified by similar reference numerals and wherein: 
         FIGS. 1A-1D  depict a sequence according to the prior art in which the filled tray is inverted, the film wrap is manually slit on the bottom surface, and the tray is re-inverted to upright. 
         FIG. 2  is a top perspective view of a film cutting apparatus according to the present invention. 
         FIG. 3  is a partially exploded top plan view of the knife driving mechanism of the invention. 
         FIGS. 4A and 4B  are enlarged side perspective views of a knife carrier assembly during film cutting and between cutting sequences, respectively. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     Referring to  FIGS. 1A-1D , the process for cutting a film wrap around a tray carrying a plurality of filled bottles according to the prior art is depicted in three steps.  FIG. 1A  shows a tray containing filled bottles in upright orientation as the tray is transferred from an incoming pallet to a cutting surface. The tray and bottles are enclosed in a transparent film that is heat sealed. The bottles each typically contain 16 fluid ounces of drink, weighing 2.1 pounds each. A tray holding 24 such bottles weighs approximately 50 pounds. A worker next inverts the tray of full bottles to the position shown in  FIG. 1B  in order to expose the tray bottom for cutting. As illustrated in  FIG. 1C , the worker has cut the film wrap twice to form an X-shape that will enable the film wrap to be removed in a single piece. The manual cutting operation is generally done with a utility knife or a box cutter having a sharp blade that is extended for use and retracted for storage. The worker attempts to cut through only the film wrap, but in order to be certain of severing the film in a single pass for each cut line, the tray may also be cut. The tray is formed of cardboard, and damage from cutting can weaken the bottom to the degree that the tray will no longer safely support a 50 pound load. Therefore, damaged trays must be replaced. After forming the X-shape cut through the film wrap bottom, the tray and bottles are again inverted to be upright, as seen in  FIG. 1D . The worker next grasps the side portions of film wrap near the tray bottom and pulls upward in the directions indicated by arrows L to remove the film wrap and expose the bottles. 
     As mentioned briefly above, in addition to the damage caused to trays by the manual cutting operation, there are other drawbacks to this process. A first drawback is that the worker is required to invert each 50 pound tray of bottles twice, causing considerable muscle strain and fatigue. A second drawback of this manual cutting operation is that in handling 50 pound trays, a tray will be dropped occasionally, damaging bottles of liquid and requiring cleanup. A third and major drawback of this manual cutting operation is worker injury, resulting in a need to clean and treat a wound, as well as to stop the production line to disinfect the areas contaminated by blood, drastically affecting productivity. Worker injury and increased insurance costs are potentially significant. 
     Referring now to  FIG. 2 , a film wrap cutting apparatus  10  of the invention is illustrated in top perspective view. Film wrap cutting apparatus  10  is generally in the form of a table with the main mechanical components mounted within, as will be described in detail below. The upper surface of apparatus  10  is a plate  14  that is oriented substantially horizontally and adapted for supporting a tray full of bottles. A pair of arcuate slots  18   a  and  18   b  are formed through plate  14  with a central portion of slot  18   a  overlapping a central portion of slot  18   b . A first knife  20   a  is shown with a point thereof extending through slot  18   a  to be visible above plate  14 . A second knife  20   b  is shown with a point thereof extending through slot  18   b  to be visible above plate  14 . Knives  20   a ,  20   b  extend above plate  14  by a height sufficient to cut through the film wrap without damaging the tray. In operation, a tray of bottles is placed upright on plate  14  with the bottom of the film wrap in contact with surface  14 . Knife  20   a  is driven along slot  18   a  and knife  20   b  is driven along slot  18   b  to make a pair of intersecting arcuate cuts through the bottom film wrap on the tray. Knife  20   b  is not positioned directly opposite to knife  20   a  in order for knives  20   a ,  20   b  to travel in sequence and not collide. The two arcuate cuts approximate the X-shape cuts formed manually and described above in respect to  FIG. 1C . Whereas the preferred embodiment of the invention employs arcuate slots  18   a ,  18   b , it is understood that alternate slot shapes and travel paths for knives  20   a ,  20   b , e.g. partial trapezoid shapes, are considered within the scope and concept of the present invention. 
     Referring further to  FIG. 2 , a pair of rails  24   a  and  24   b  are provided along opposed side edges of plate  14 . Rails  24   a ,  24   b  are separated by a distance slightly greater than the width of a tray to be processed in apparatus  10 . Rails  24   a ,  24   b  are preferably assembled to plate  14  in a manner to allow for adjustment of the distance therebetween to accommodate different size trays as required. A moveable stop  28  is provided adjacent to an end of plate  14 . Stop  28 , as illustrated, is automatically moved intermittently upward and downward through a slot in plate  14  to allow the worker to quickly and accurately position a tray in the proper location for cutting the film wrap. At the end of the cutting process, stop  28  automatically retracts downward through plate  14  to allow the worker to push a second tray onto plate  14  while moving the first tray off of plate  14  and onto conveyor  40 . Conveyor  40  may be of the gravity or driven types. It will be understood by those skilled in the art that alternate forms of moveable stop may be employed for positioning the tray as described. It will be further understood that the tray may be placed on plate  14  in the space between rails  24   a ,  24   b  by mechanical means, e.g. a robot arm. 
     Once the worker has placed a tray on plate  14 , the worker initiates the mechanical actions by contacting both switches  32   a  and  32   b  simultaneously. The circuit activated by switches  32   a ,  32   b  initiates a single cycle rotation of knives  20   a ,  20   b . As a further safety feature, a pair of photoelectric transmitters and receptors  36   a  and  36   b  are provided adjacent to the entry portion of plate  14 . Photoelectric transmitters and receptors  36   a ,  36   b  are in the form of a light curtain to encompass a broad area, and are capable of emitting a signal for quickly stopping the mechanical action in case a worker breaks the light curtain with a hand or arm. 
     Referring now to  FIG. 3 , a top plan view of a pair of mirror image conveyor mechanisms is illustrated as mounted to a base  44  (shown in long and short dashes) below plate  14  ( FIG. 2 ). Chain  46  is mounted around a drive sprocket  50   a  and an idler sprocket  50   b  for rotation in a substantially semi-circular path defined by a guide plate  56 . Chain  48  is mounted around a drive sprocket  52   a  and an idler sprocket  52   b  for rotation in a substantially semi-circular path defined by a guide plate  58 . Chain  46  and chain  48  are mounted to be substantially co-planar. Sprockets  50   a ,  50   b ,  52   a ,  52   b  are rotatably mounted to base  44 . Drive sprocket  50   a  and drive sprocket  52   a  are synchronously driven by a driver, e.g. a servo motor (not shown), with appropriate drive and speed control. The servo motor may be programmed to drive the mechanism through a single cycle and stop or be stopped by a signaling device. Knife carrier assembly  64   a  is affixed to the exterior surface of a chain  46 . Knife carrier assembly  64   b  is affixed to the exterior surface of a chain  48 . In operation, chain  46  is driven clockwise as indicated by arrow A, and chain  48  is driven counterclockwise as indicated by arrow B. Although chains  46 ,  48  and guide plates  56 ,  58  are seen as mirror images of one another, knife conveyor assemblies  64   a ,  64   b  are cyclically offset from each other. In this manner, when chains  46 ,  48  are simultaneously driven in the directions indicated by arrows A and B, knife carrier assembly  64   a  passes the apex of guide plate  56  before knife carrier assembly  64   b  has reached the apex of guide plate  58 , therefore avoiding an interference. As knife carrier assemblies  64   a ,  64   b  follow their respective semi-circular travel paths beneath a film wrapped tray, the knives cut a pattern in the bottom film covering that approximates an X-shape. 
     Referring further to  FIG. 3 , a cam plate  60 , shown out of the mounting position, is assembled to cover sprockets  50   a ,  50   b . Similarly, a cam plate  62  is assembled to cover sprockets  52   a ,  52   b . Cam plates  60 ,  62  are assembled to base  44  and spaced above respective sprockets  50   a ,  50   b ,  52   a ,  52   b . As knife carrier assembly  64   a  completes the arcuate portion of the travel path around guide plate  56  and approaches sprocket  50   a , knife carrier assembly  64   a  is retracted by cam plate  60  in order to prevent further cutting of the film wrap. Knife carrier assembly  64   b  is similarly retracted by contact with cam plate  62  when knife carrier assembly  64   b  approaches sprocket  52   a . At the completion of the cutting cycle, knife carrier assemblies  64   a ,  64   b  are each positioned along the linear portion of their respective cycles and under each respective cam plate  60 ,  62  to retain each knife carrier assembly  64   a ,  64   b  below the surface of plate  14  (see  FIG. 2 ). At the point that knife carrier assemblies  64   a ,  64   b  respectively reach the arcuate portion of their travel paths beyond sprockets  50   b ,  52   b , plates  60 ,  62  release knife carrier assemblies  64   a ,  64   b  to enable film cutting. 
     Referring now to  FIG. 4A , knife carrier assembly  64   a  is shown in enlarged perspective view affixed to chain  46  (shown in dashed lines). Knife carrier assembly  64   a  comprises a clamp block  66  that is formed with a channel sized for engaging chain  46  with fastening means, e.g. set screws. A knife holder  68  is pivotally connected to clamp block  66  by a pivot pin  70  to allow knife holder  68  to rotate a limited amount in the direction indicated by arrow D. A cam rod  74  is affixed to the back surface of knife holder  68  and extends over the top of clamp block  66 . Knife carrier assembly  64   a  and chain  46  travel in the direction indicated by arrow C. Knife blade  20  is free to rotate in the direction indicated by arrow D when cam rod  74  is pressed against the leading edge of cam plate  60 . A spring (not shown) causes knife holder  68  to return to the cutting position as seen in  FIG. 4A . 
     Referring now to  FIG. 4B , knife carrier assembly  64   a  is shown with knife  20  in retracted orientation after cam rod  74  has contacted cam plate  60 . In this orientation, the cutting edge (long edge) of knife  20  is substantially horizontal to avoid contact with the bottom of the film wrapped tray as knife carrier assembly  64   a  is conveyed along the linear portion of the travel path, i.e. after the X-shape has been cut through the film wrap covering the tray bottom. 
     To reiterate the operational sequence according to the invention, a worker or robot places a first tray containing full bottles that is wrapped with film onto a tray supporting surface having a pair of arcuate slots formed therethrough. The tray is positioned between a pair of side rails and against a moveable stop. The operator presses two start switches simultaneously. A first knife is driven by a chain mechanism to contact the bottom of the film wrap following an arcuate path in a clockwise direction. A second knife is driven by a chain mechanism sequentially after the first knife to contact the bottom of the film wrap following an arcuate path in a counterclockwise direction. The two arcuate travel paths of the knives slightly overlap to form an X-shape cut in the film wrap. After cutting the film bottom, the first and second knives are pivoted to positions below the tray supporting surface and the conveyor mechanisms are deactivated. The stop is retracted below the tray supporting surface. The operator removes the cut film wrap from the tray and bottles contained therein and discards the cut film wrap. The operator places another film wrapped tray containing full bottles onto the tray supporting surface, pushing the first tray onto a tray conveyor. The stop is moved upward to position the second tray. The operator presses the two start switches simultaneously. 
     While the description above discloses preferred embodiments of the present invention, it is contemplated that numerous variations and modifications of the invention are possible and are considered to be within the scope of the claims that follow.