Abstract:
A method of preparing flat articles for sorting includes the steps of: (1) receiving a bundle of flat items to be sorted, the bundle being wrapped with a flexible film such that the film forms an enclosed package of flat items, (2) placing the bundles on a substantially horizontal, substantially frictionless work surface, moving the bundle adjacent at least one film slitter, the film slitter being automatically activated when the bundle is moved adjacent the film slitter, (3) removing the cut film from the flat items, and (4) stacking the unbundled flat items in a cartridge.

Description:
TECHNICAL FIELD 
     The invention relates to devices and methods for preparing bundled flat mail for sorting. In particular the invention relates to an improved workstation for unbundling flat mail and a method of using the same. 
     BACKGROUND OF THE INVENTION 
     The United States Postal Service (USPS) receives hundreds of thousands mail pieces on a daily basis from printers, premail processors and sorts and other entities for sorting and distribution. In many cases, these mail pieces are bound in bundles with combinations of plastic wrap and straps, the plastic wrap typically being a polyethylene or ethylene copolymer film while the straps are formed from nylon, polyester or a similar high-tensile strength material. Although these bundles are normally light enough to be readily handled, the straps and plastic wrap must nonetheless be removed, an awkward and time consuming task. After the mail has been unbundled, it must then be faced and edged prior to being fed to an automated sorting machine. 
     Currently, the process of unbundling, edging and facing mail is performed manually on an ad hoc basis. In some instances, the operator picks up an incoming bundle from an arriving container or transport, slices and removes the straps and plastic wrapping from the bundle using a hand-held knife. The unbundled mail must then be faced, edged and transferred to another container for transport to an automated sorter. These manual activities involve a large number of bends, lifts and turns on the part of the mail handler, motions that are ergonomically inefficient and time consuming. The present invention addresses these deficiencies. 
     SUMMARY OF THE INVENTION 
     In accordance with the invention, an apparatus for preparing flat articles for sorting includes a work table with a substantially horizontal, frictionless work surface for supporting film-wrapped bundles of flat articles to be sorted. The work table is provided with one or more hot air film slitters mounted adjacent the table for slitting the film and a sensor for activating the slitter when a bundle is moved adjacent the hot air slitter. A retractable clipper is also mounted adjacent or on the table for slicing flexible bands that may be secured around the bundles. 
     In a preferred embodiment, a pair of hot air film slitters are mounted on the table and configured to simultaneously slit film on adjacent sides of the bundle. One or more contact switches are used to activate the hot air film slitters when the bundle is moved into position wherein the bundle contacts the switches. 
     In one aspect, the apparatus includes a cartridge for receiving unbundled flat items and a lift for supporting a plurality of such cartridges. In a preferred embodiment, the lift is self-adjusting such that as flat items are stacked into a cartridge positioned on the lift, the height of the cartridge is adjusted to maintain the top of the stack level, or approximately level with the height of the table. 
     In another aspect, the invention provides a method of preparing flat articles for sorting, including the steps of: (1) receiving a bundle of flat items to be sorted, the bundle being wrapped with a flexible film such that the film forms an enclosed package of flat items, (2) placing the bundles on a substantially horizontal, substantially frictionless work surface, moving the bundle adjacent at least one film slitter, the film slitter being automatically activated when the bundle is moved adjacent the film slitter, (3) removing the cut film from the flat items, and (4) stacking the unbundled flat items in a cartridge. In one variation, the method further includes the steps of removing flexible straps used to secure the bundles with a retractable clipper mounted adjacent the work surface and using a first film slitter is positioned at 90° relative to a second film slitter to simultaneously cut film on adjacent sides of the bundle. In a preferred embodiment, the film slitter(s) or cutter(s) a hot air slitters that are activated when the bundle touches a contact switch positioned to correspond with the bundle being adjacent to the film slitter. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a schematic representation of a work station according to the invention; 
         FIGS. 2 and 3  are side and end views, respectively, of a mail cartridge suitable for use in the practice of the invention; 
         FIG. 4  is a partial side view of an adjustable lift suitable for use with the mail cartridge of  FIGS. 2 and 3 ; and 
         FIGS. 5 and 6  are side and end views of a cart adapted to transport the cartridges of  FIGS. 2 and 3 . 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Referring to  FIG. 1 , according to the invention, incoming bundles  12  of flat mail are introduced to workstation  10  with a “lift and tilt” device  14  such as a powered tiltable lift which deposits the mail pieces in an elevated holding bin  16 . Bundles  12  are formed from a stack or stacks of mail pieces that have been wrapped in a plastic film to form an enclosed package. In some cases, the film-wrapped packages  12  of mail pieces will also be wrapped with flexible straps, typically made from a high tensile strength material such as nylon or polyester. 
     Bundles  12  from bin  16  are directed down an inclined funnel-like ramp  18  to a horizontal work table  20 . To aid in manipulating bundles of mail on work table  20 , the table is provided with an essentially frictionless working surface  22  by means of a plurality of ball or roller bearings  24  mounted in the surface of table  20  such that the bearings  24  may freely rotate. Alternatively, table  20  could be provided with a plurality of holes or orifices  26  through which compressed air is ejected to support objects placed on the table thereby providing an essentially friction-free working surface. Although as illustrated, inclined ramp  18  is used to convey bundles to work table  20 , other means, such a horizontal or inclined belt or roller conveyor could also be utilized to transport bundles  12  to the table. 
     When a bundle  12  arrives on surface  22 , operator  30  utilizes a retractable electrically or pneumatically powered clippers  32  to cut any bands from the bundle. Operator  30  then manipulates bundle  12 , placing adjacent sides of the bundle against or immediately adjacent to a pair of conventional hot air slitters  34 ,  36  in order to cut the plastic wrap surrounding the bundle. 
     As shown, hot air slitter  34  is positioned at 90° relative to hot air slitter  36  which allows the operator to cut the plastic wrapping on two sides of the bundle simultaneously. To activate the slitter, operator  30  pushes a bundle  12  against one or more contact switches  38  which activate slitters  34 ,  36 . Alternatively, the operator may position the bundle and activate slitters  34 ,  36  with a switch  21  that is preferably positioned so that the operator may activate the slitters by stepping on switch  21 , thereby leaving the operators hands free to manipulate the bundle. After the operator cuts the plastic warp on two sides of bundle  12 , he or she rotates the bundle 180° and repeats the process, cutting the plastic wrap on two additional sides of the bundle. If necessary, the operator may rotate bundle  12  again to cut the plastic wrap on one or both of the two remaining sides of the bundle. 
     After the plastic wrap or film has been cut, the operator peels or lifts the film from bundle  12  and slides the unbundled mail into a mail cartridge  50  on the side of surface  22  opposite ramp  18 , edging the mail along the sides and bottom of the mail pieces. Bands and plastic film cut from bundles  12  along with any other debris is placed upon conveyor  42  which transports the debris to a trash receptacle  44 . 
     Turning to  FIGS. 2 and 3 , mail cartridge  50  is designed to allow the operator to edge mail along the sides and bottom of the mail pieces quickly and efficiently after the mail has been unbundled. Cartridge  50  comprises an end wall  54 , bottom wall  56 , rails  52  and one or more stack supports  58  and is open on the side opposite end wall  54  to allow the operator to place mail into the cartridge with a minimum of effort. Stack supports  58  include a handle  64  for positioning and removing the support from cartridge  50  and a pair of ball lock pins  60  inserted and secured in selected holes  62  formed in end wall  54  to hold support  58  in position. 
     Stack support  58  is also provided with a tab  68  at the end of the support adjacent handle  64  that is configured to fit into a slot  70  in bottom wall  56 . Tab  68  and slot  70  include serrations  72  that interlock to secure stack support  58  in position in cartridge  50 . 
     Turning to  FIG. 4 , in order to facilitate loading unbundled mail from working surface  22  into cartridge  50 , a self adjusting lift  80  is provided. As illustrated, lift  80  includes a frame  82  and a movable cartridge support  84  with a recess  86  configured to receive rails  52  of cartridge  50  and support the cartridge in lift  80 . Cartridge support  84  is mounted on an endless belt or chain  88  which is driven by motor  90  to raise or lower cartridge  50  relative to working surface  22  of work station  10 . A sensor  92  detects when the operator has loaded a sufficient number of mail pieces into cartridge  50  to raise the height of mail piece stack  94  to a predetermined position adjacent working surface  22  and generates a signal which is used to actuate motor  90 . Motor  90  in turn drives chain  88 , lowering cartridge support  84  and cartridge  50  such that the top of stack  94  is maintained at a level no higher than working surface  22 . As will be appreciated, maintaining the height of stack  94  enables the operator to move unbundled mail from work station  10  onto cartridge  50  with a minimum of movement and effort. 
     Turning to  FIGS. 5 and 6 , after a cartridge  50  has been filled with mail, the cartridge is transferred to a cart  100 . As shown, cart  100  includes a T-shaped frame  102  mounted on casters or wheels  104 , thereby allowing the cart to be easily moved between work station  10  and an automated sorting machine. Cart  100  includes a plurality of brackets  106 , each of which is angled downwardly toward the center of frame  102 . As shown, each of brackets  106  is provide with a pair of spaced apart ribs  108  positioned such that rails  52  of cartridges  50  fit between and engage one or both of ribs  108  to retain cartridges  50  in place on cart  100 . 
     After cart  100  has been loaded with filled cartridges  50 , the cart is moved to the feeder of an automated sorting machine. The cartridges are transferred, manually or with a powered transfer device to the feed where the operator removes stack supports  58  and slides the unbundled and edged mail from the cartridge onto the feeder for sorting. 
     As will be appreciated, the mail handling system of the invention reduces the amount of labor required to unbundle wrapped and strapped packages of mail received from bulk mailers, pre-sorters and similar entities. The mail handling system of the invention is also ergonomically efficient, reducing the number of lifts, turns and motions required of postal personnel. Further, while certain embodiments of the invention have been illustrated for the purposes of this disclosure, numerous changes in the method and apparatus of the invention presented herein may be made by those skilled in the art, such changes being embodied within the scope and spirit of the present invention as defined in the appended claims. For example, the stack supports could be fashioned to swing into and out of the holding position, rather than be detachable as described above.