Abstract:
The present invention relates to a system and method for extracting and polywrapping articles stored in a pocket of a container. The container may be part of a DPP machine. In operation, a separator sheet is extracted, the bottom of the pocket opened so as to allow the articles therein to drop into a polywrapping device, and the polywrapping device sequentially polywraps the articles. After the articles are dropped from the pocket, the separator sheet is reinserted. Rollers and cross sealer bars, appropriately placed, facilitate the polywrapping. Optional use of an H-belt is possible as well as a tracked sheet bottom transporting the pockets to the polywrapping device.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
   The present application claims priority to provisional patent application No. 60/499,612, filed on Sep. 3, 2003, which is herein incorporated by reference. 

   BACKGROUND OF THE INVENTION 
   The present invention is directed to the filed of article handling and more particularly to a system and method for extracting and polywrapping sorted articles. The articles are typically sorted by a delivery point packaging machine (DPP). Articles as used throughout the application is defined as at least one of mail, books, magazines and other such articles. DPP machines are used to sort large batches of articles. The articles are fed into the machine by feeders which also decode the destination address of the article as well as the article&#39;s thickness. The DPP includes a plurality of slots or pockets for receiving articles. The pockets are logically assigned a destination address and once the address is known (as will be the case when the article is fed into the DPP) the article is routed to its respective pocket. The pockets are stored in containers, themselves stored in a casting of a tower. 
   Once the batch of articles is appropriately sorted, it may become necessary, depending upon the application, to extract and polywrap the articles. Extracting the articles from the pockets entails the articles removal from the pockets with the sorting order of the articles within the pockets maintained. Polywrapping the articles entails wrapping at least one of the articles in a polywrap—a plastic like material—which facilitates article handling and the like. 
   Current systems for extracting and polywrapping articles are cumbersome, complicated, bulky and present engineering challenges. Additionally, extracting and polywrapping systems have not been effectively applied to DPP machines. Accordingly, a need exists in the art for effective and cost efficient article extraction and polywrapping. An additional need is that the aforementioned be applicable to DPP machines. 
   SUMMARY OF THE INVENTION 
   The present invention is directed to a method for performing article extraction and polywrapping. The invention is further directed to a system for carrying out the method. In the method: the casing are removed to an extraction zone or into an extraction position; a separator sheet present in the container is removed; the bottom of each pocket in the container is individually opened allowing the articles stored therein to fall through the opening; the downward motion of the article is assisted by an H-belt; the articles are received at a polywrapping station where the articles are sequentially polywrapped. 
   The present system comprises means for accomplishing the aforementioned method steps. In particular, the bottom of the pocket may include a plurality of tracks and the walls defining the pocket may include protrusions which interact with the tracks so as to facilitate lateral displacement of the pocket floor and prevent any articles from becoming caught between a pocket side wall and its base. The article contents remain within the pocket. The H-belt may comprise a top webbing running between the two walls and descendible to the floor. The polywrapping station my include a first and second crimping unit to crimp polywrap film at the beginning and end of the article descent, respectively so as to encase the articles in the film. Likewise, the top of a former set of polywrapped articles may form the bottom of a subsequent set of polywrapped articles, thereby making successive and more efficient use of the film. Additionally, the polywrapping station may include a pair of rollers as well as cutting means arranged to sequentially seal and separate the sets of now polywrapped articles. 

   
     BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS 
     These and other embodiments of the present invention will be set out below in more detail with respect to the specification and claims, wherein like reference numerals refer to like parts. In the figures: 
       FIG. 1  depicts a schematic of a first embodiment of the present invention; 
       FIG. 2   a  depicts a perspective schematic view of a pocket according to the present invention; 
       FIG. 2   b  depicts a second view of the pocket according to  FIG. 2   a;    
       FIGS. 3   a  and  3   b  depict operation of the present method; and 
       FIG. 4  depicts a flowchart of the present method. 
   

   DETAILED DESCRIPTION OF THE INVENTION 
     FIG. 1  depicts a schematic representation of a first embodiment of the present invention. As depicted, a pocket carrier or POD  10  is being indexed in a direction indicated by arrow  18 . A second carrier  11  is depicted upstream. The function of the carriers used in the present system are identical and will be described with reference to an example carrier  10 . 
   Carrier  10  comprises a plurality of pockets  12   a  and  12   b  for accommodating at least one article  14  therein. The size and number of pockets per container and the number of articles accommodated therein are a matter of design. Pockets  12   a  include articles therein, while pocket  12   b  is empty. The pockets generally have at least one open side for article insertion. The pocket bottoms may be selectively opened as will be discussed herein. The pocket tops may be open or close as dependent upon design. As depicted in  FIG. 1 , the container travels  12  along a bottom  16  which includes at least one opening  20 . The container may alternatively travel upon rails which by definition include an open bottom. For purposes of illustration, the solid bottom  16  with opening  20  will be referred to hereinafter. The opening  20  is positioned to align with the pocket bottom and is sufficiently large to facilitate passage of articles therethrough. 
   Positioned below opening  20  is polywrapping means  21  comprising film  24 , a pair of rollers  26 , and a plurality of cross sealing bars  28   a ,  28   b . The polywrapping means includes other components known to one skilled in the art and not discussed here for purposes of clarity. The film is introduced into the polywrapping means from two locations so as to run between the rollers and sealing bars in a downward direction away from the sheet bottom  16 . Other film introducing schemes may be used as envisioned by the skilled person. As depicted in  FIG. 1 , the film  24  is positioned below sheet bottom  16  and is laterally and vertically displaceable. The film passes over and between the rollers  26  and descend downward in between the opposing cross sealer bars  28   a ,  28   b . The rollers  26  are spaced a part a distance  27  sufficiently large so as to allow articles  14  to pass, therebetween. The rollers  26  may be coplanar and/or coaxial. Positioned downstream of rollers  26  (in the direction of film flow) are the cross scaling bars  28   a  and  28   b . The cross sealing bars are spaced apart a vertical distance  34  which is larger than the longest article ( 4   a ). Likewise, the cross sealing bars are spaced apart a horizontal distance sufficiently large so as to allow articles within the pocket to pass therethrough. The cross bars may be coplanar and/or coaxial. The cross sealing bars arc laterally displaceable so as to join at point  36 . At point  36 , the two sides of the film are brought and sealed together. Cross bars  28   a  define an upper position and cross bars  28   b  a lower position, in between which the articles become sealed between two foils of film. As further depicted, a group of articles  8  have descended through opening  20 , in the direction indicated by arrow  22 . The descent  150  may be about 50 mm, although other descents lengths may be used by design. 
     FIG. 2  depicts a single pocket  12  and a POD base  100 . Base  100  includes a plurality of tracks  40  through which prongs  42  may pass. The tracks run substantially parallel to indexing direction  18  ( FIG. 1 ). A plurality of prongs  42  are attached to a pocket wall  44  comprising a separator sheet design. This design entails a plurality of spaced rollers  46 . The rollers are displaced at four corners defining the pocket. Running vertically about the rollers is a first sheet  48  in an endless loop. Running horizontally between the rollers is a second sheet  50 . The combination of the two sheets  48  and  50  as well as the base  100  define a pocket cavity  102 . When the rollers are rotatably engaged, the second sheet  50  can be made to descend in the direction of the base  100  as well as rise away. The base  16  further includes a pair of latches  52 . Bottom rollers, downstream in the direction of index  18 , include a pair of lateral protrusions  54  for abutting the latches  52  thereby temporarily halting the lateral displacement of the pocket  12  with respect to base  100  or visa versa. The protrusions prevent articles from getting caught between pocket side walls and base. The lateral movement is facilitated by the prongs  42  running in track  40 . The lateral movement will be approximately equal to or greater than the width of cavity  102  so as to allow articles within the cavity to pass through the now open base without obstacle. 
     FIG. 2   b  depicts the pocket  12  with base  100  removed and second sheet  50  descended. Prongs  52  abut protrusions  54 . The descending motion of the second sheet will urge articles within the cavity through the now open pocket bottom. The combination of the first and second sheet comprise an H-belt. 
   The operation of the present invention will now be described with reference to  FIGS. 3   a ,  3   b  and  4 .  FIGS. 3   a  and  3   b  are divided into four sections each (labeled  1 - 8 ).  FIG. 4  depicts a flowchart of the present inventive method. Sections  1 ,  2  and  8  depict pocket  12  from above and the remaining figures depict the pocket from the side. The method starts (step  70 ). Stored in pocket  12  are articles  14  and separator sheet  56 . As depicted in section  2  separator sheet  56  is removed (step  72 ) from an open side in the direction as indicated by arrow  58 . 
     FIG. 3  depicts a side view of the pocket  12  with the separator sheet  56  now removed. A previously wrapped group of articles  60  is depicted below top cross sealer bars  28   a . Moving from the left to right side of the figure, the pocket  12 , with base  100  therebelow, is laterally displaced over the top of opening  20  (step  74 ). Once the pocket is arranged over opening  20  (left image), the base  100  is laterally displaced in the direction indicated by arrow  106  thereby exposing articles  14  to opening  20 . 
   In section  4 , the articles  14  accommodated within pocket  12  drop into opening  20  and rollers  26  and atop top cross sealer bars  28   a  (step  76 ). 
   In section  5 , the cross section bars  28   a  descend in the direction of bottom cross bars  28   b . This action pulls down the film with the articles creating the side walls which will seal in the articles with the film. Additionally, bottom cross section bars  28   b  now rise into position above top cross section bars  28   a  thereby getting ready for the next group of articles. The second sheet  50  is depicted partially descended and protrusions  42  partially elevated (step  78 ). 
   In section  6 , with the tallest articles descending below the top cross sealer bars  28   a , the top cross sealer bars  28   a  are brought together. The second sheet  50  is depicted fully descended and protrusions  42  fully elevated (step  80 ). 
   In section  7 , with the pocket  12  now empty, the second sheet  50  is elevated back to a top position with the protrusions  42  descended into a bottom position (step  82 ). 
   In section  8 , the separator sheet  56  is reinserted in cavity  102  (step  84 ). At this point, the now empty pocket may be reintroduced for receiving new mail and the method continues with the next pocket including articles therein. The method then ends (step  86 ). 
   The invention being thus described, it will be obvious that the same may be varied in many ways. Such variations are not to be regarded as a departure from the spirit and scope of the invention, and all such modifications would be obvious to one skilled in the art are intended to be included within the scope of the following claims.