Abstract:
A placement component rapidly moves individual bag blanks from a pack or magazine to a conveyor system in uniformly spaced relationship. Each bag blank has opposite surfaces. While the conveyor system continues to move the bags, opening tabs are automatically applied to opposite surfaces of each bag, followed by high speed application and cutting of sideways extending flexible closure strips. The bag blanks are moved continuously from the placement component to the high speed cutting section, as compared to incremental movement, for high speed manufacturing of specialized bags.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
   This application claims the benefit of U.S. Provisional Application No. 60/471,093, filed May 15, 2003. 

   FIELD OF THE INVENTION 
   This invention relates to a system for making a special receptacle or package, and more particularly to a system for making a reclosable sterile collection bag having a flexible strip closure mechanism. 
   BACKGROUND OF THE INVENTION 
   Bags having wire closure mechanisms are currently used to obtain industrial, chemical, and forensic material samples in a sterile manner. For example, U.S. Pat. No. 2,973,131 describes a collection bag having metal wires. Strips of pressure sensitive tape are used to attach the metal wires to opposite sides of the bag. Both the wires and the tape project beyond the side edges of the bag. During use, the bag is filled, the mouth of the bag is closed and rolled against the body of the bag, and the projecting portions of the metal wires are folded back to clamp the rolled end closed. 
   Later inventions have been made to improve the ease with which the bag may be opened. For example, U.S. Pat. Nos. 3,189,253; 4,356,954; and 5,180,220 each use center pull tabs. U.S. Pat. No. 4,356,954 uses downwardly-directed strip ends. U.S. Pat. No. 5,180,229 encloses the wire ends with an additional length of covering material. The arrangements of the above patents can be difficult and costly to manufacture. Other potential problems are pull tabs or tear strips that become separated from their bags and fall into (and therefore contaminate) foodstuffs or other products, and bags that are difficult to open or which may be punctured inadvertently. 
   SUMMARY OF THE INVENTION 
   The present invention provides a novel system for manufacturing a sterile collection bag having a body and an opening mechanism. The body is formed of opposed sidewalls and includes an upper body end portion adjacent to the mouth opening. The interior of the body defines a sterile collection space for a sample object or fluid. The opening mechanism includes first and second flexible closure strips, each having a first end, a second end, and a midsection. The strips can be constructed of plastic with an integrated, centrally located metal wire. The strips are attached to the sidewalls of the bag body and are longer than the width of the body so as to project beyond the sidewall edges. The projecting ends of the strips can be secured to one another. 
   The bag can be designed in such a way as to prevent the intrusion of air and other contaminants to the interior sterile collection space until its initial use, by sealing the top of the bag. For example, the bag can be formed of polymer film, and one or more lateral notches are cut slightly above the location of the attached flexible closure strips. The strips can be sufficiently rigid and abrupt to facilitate lateral tearing of the upper end of the bag, guided by an adjacent edge of a closure strip. This allows the top of the bag to be torn away for opening upon initial use, but prevents air and other contaminants from entering the interior sterile collection space beforehand. 
   In accordance with the present invention, bags of the type described above can be manufactured inexpensively and at high speed by automatic equipment including a placement component for rapidly moving individual bag blanks from a pack or magazine to a conveyor system in uniformly spaced relationship, and automatic equipment for applying opening tabs to opposite surfaces of the bag, followed by high speed application and cutting of the flexible closure strips. The manufacturing method preferably is conducted with the bag blanks moved continuously from the placement section to the high speed cutting section, as compared to incremental movement which could slow down the manufacturing process. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The foregoing aspects and many of the attendant advantages of this invention will become more readily appreciated as the same become better understood by reference to the following detailed description, when taken in conjunction with the accompanying drawings, wherein: 
       FIG. 1  is a front elevation of a sterile collection bag that can be made by the system of the present invention; 
       FIG. 2  is a front elevation of a closure strip for use with the bag of  FIG. 1 ; 
       FIG. 2A  is a front elevation corresponding to  FIG. 2 , showing an alternative closure strip that may be used; 
       FIG. 3  is an enlarged section along line  3 — 3  of  FIG. 2 ; 
       FIG. 4  is a top perspective of a bag that can be made by the system of the present invention with some component parts shown in exploded relationship; 
       FIG. 5  is a top perspective corresponding to  FIG. 4 , but with the parts assembled and the bag partially opened prior to use for collection of a sample; 
       FIG. 6  is a top perspective corresponding to  FIG. 5 , with the mouth of the bag opened for insertion of a sample; 
       FIG. 7  is a perspective of a bag in accordance with  FIG. 6  rolled and clamped closed to retain a collected sample therein; 
       FIG. 8  is a top perspective of an alternative bag partially opened; 
       FIG. 9  is a top perspective of the alternative bag with the mouth of the bag opened; 
       FIG. 10  is a diagrammatic side elevation of a pick-up and placement component used in a bag manufacturing system in accordance with the present invention, and  FIG. 10A  is a top perspective of a bag blank operated on by such component; 
       FIG. 11  is a diagrammatic side elevation of a tab-applying component used in a bag manufacturing system in accordance with the present invention, and  FIG. 11A  is a top perspective of a bag blank operated on by such component; 
       FIG. 12  is a diagrammatic side elevation of a closure strip-applying component used in a bag manufacturing system in accordance with the present invention; and  FIG. 12A  is a top perspective of a bag blank operated on by such component; and 
       FIG. 13  is a diagrammatic side elevation of a high speed cutting component used in a bag manufacturing system in accordance with the present invention, and  FIG. 13A  is a top perspective of a bag operated on by such component. 
   

   DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
   The present invention provides a system for manufacturing a bag that can be used in collection, processing, and manipulation of material samples taken for biological, industrial (such as food sampling) and forensic testing. 
   Referring to  FIG. 1 , the bag  10  includes a body  12  formed of plastic or other known flexible, non-porous collection bag material. The body  12  includes opposed front and rear walls  14  and an upper body end portion  16 . Each sidewall  14  has an exterior surface and a center section. The bottom and side edges of the sidewalls are sealed, such as by conventional heat sealing or adhesive, represented by the cross-hatching along the bottom and side marginal portions. The top edge  17  also is sealed. The interior of the body  12  defines a sterile collection space for a sample to be placed. Notches  15  are provided at the side edges of the sidewalls  14  at the juncture between the bag body  12  and upper body end portion  16 . Preferably the upper body end portion  16  is brightly colored or otherwise prominently marked (represented by stippling in the drawings) so as to be readily visible when separated from the remainder of the bag structure as described below. 
   A flexible closure strip  22  usable with the bag of  FIG. 1  is illustrated in  FIGS. 2 and 3 . With reference to  FIG. 3 , closure strip  22  has an essentially planar backside  23  which may be coated with a layer of adhesive  24 . A malleable wire  25  is embedded in a longitudinally extending rib  26  which preferably is located intermediate the top and bottom edges  27 ,  28  of the strip. Thus, a substantial protrusion is provided on the front side  29  of strip  22 . Preferably the wire  25  is entirely surrounded and coated by the plastic material of the strip, so that no part of the midsection of the wire is exposed. The plane of the front side  29  of the strip, ignoring the rib  26 , is approximately aligned with the periphery of the embedded wire  25 . 
   The wire is a malleable metal, similar to wires used for common twist ties. In this construction, the plastic material also is a malleable material having little, if any, memory or spring characteristics, such that a double thickness of strips  22  can be easily bent to a new configuration and retain that configuration until bent back or bent to a new configuration. However, when in the flat configuration illustrated in  FIG. 2 , at least the top edge  27  of the strip has sufficient thickness so as to be almost rigid as compared to the flexible bag material, with an abrupt corner or corners. 
   As described in more detail below with reference to  FIGS. 10–13 , to facilitate bag manufacture and assembly by automatic machinery, long lengths of the closure strip  22  may be formed in rolls, prior to application of the adhesive coating  24 . Strips of a desired length can be cut from the roll and applied to the bag, all by the automatic machinery, but, in accordance with the present invention, continuous strips may be applied across multiple bags before the strips are cut. The wires  25  embedded in the pre-formed strips are reliably positioned as desired at the center of the strips. This alleviates the prior problem of misalignment of wires under paper tapes, direct contact of the wires with the bags, and exposed wires. 
   With reference to  FIG. 4 , each strip  22  is applied to its bag with the top edge  27  of the strip extending between or close beneath the bag notches  15 . As see in the drawings, the front and back strips are in directly opposed relationship. Preferably the manner of attachment is adhesive applied along the midsection and projecting end portions  31  of each strip. Thus such end portions are secured together at their flat rear faces  28 . Opening tabs  30  have top end portions interposed between the strips  22  and the bag sidewalls  14 , and secured thereto by the adhesive. Such tabs have large projecting portions which preferably are square and approximately one inch in width by one inch in length, at least about ¾ inch in each dimension in the preferred embodiment. The projecting parts of these tabs  30  hang loose and are of a textured material suitable for writing indicia on them by a conventional writing instrument such as a pen or pencil, and of non-slippery material, i.e., with a sufficiently high co-efficient of friction that they may be readily grasped between a user&#39;s thumb and forefinger, for example, and pulled relatively apart as described below with reference to  FIG. 6 . 
   With reference to  FIG. 5 , the side notches breach the sheer strength of the plastic bag material providing a convenient starting point for a tear across the upper end portion  16  of the bag. Preferably the notches do not extend beyond the inner edge of the sealed area which would provide an opening into the interior of the bag that could cause contamination. The upper end portion is peeled downward along the top edge  27  of one or the other of the closure strips  22 , as shown in  FIG. 5 . The sharp or abrupt top edge  27  of the strip  22  guides the tear and assists in assuring a clean, complete separation of the upper end portion  16  from the body  12  of the bag. The bag material can be a transversely oriented polymer, but an advantage of the invention is that a less expensive nonoriented polymer film can be used without scoring or partial perforation while still allowing the bag to be opened for use by tearing away the top end section  16 . 
   Typically, the bags are formed of a transparent or nearly transparent material, for visualization of any samples held therein. However, it has been found that upper tear strips of a transparent material may fall into the nearby environment, causing possible contamination. The brightly colored or otherwise prominently marked tear strip of the present invention is readily identified so that it will be retrieved if it is inadvertently dropped. 
   With reference to  FIG. 6 , once the upper body end  16  has been tom from the bag, the mouth of the bag can be opened conveniently by pulling on the projecting tabs  30 . The desired sample S can be inserted through the open mouth of the bag. For the reasons discussed above, preferably the tabs  30  are brightly colored or otherwise prominently marked in case they become separated from the bag. Also, the non-slippery material, in combination with large tabs, make opening the bag mouth more convenient than in known designs, and the tabs provide a location for marking information concerning the contents, date of collection, etc. 
   After insertion of the sample S into the bag, the mouth is closed manually, rolled shut, and the projecting ends of the closure strips folded back onto the body of the bag to clamp it in the closed condition shown in  FIG. 7 . 
   In the construction illustrated in  FIGS. 8 and 9 , the projecting end portions  31  of the front and rear closure strips  22  are not secured together. The midsections of the strips, which can be less pliable than the strips of the previously described construction, are adhered to the bag body, but end portions  31  are unconnected so that they may diverge from each other at a small acute angle from the side edges of the bag to their free ends. Otherwise, the embodiment of  FIGS. 8 and 9  is identical to the embodiment previously described. The top end part  16  can be torn beginning from a notch  15  along the abrupt top edge  27  of a strip  22 , as shown in  FIG. 8 . Thereafter, the strip ends  31  can be squeezed together to bias the midsections of the strips apart as seen in  FIG. 9 . If necessary to achieve a desired degree of opening, the strip ends at one side can be pushed toward the strip ends at the other, or the opening tabs can be used. After insertion of the sample, the mouth of the bag is closed, rolled, and clamped to the condition of  FIG. 7 . 
   The ends of the strips  22  can extend straight and perpendicular to the top and bottom strip edges  27 ,  28  as seen in  FIG. 2 , for example. The plastic material has less tendency to puncture a bag, and the embedded wire is not exposed to a position where it substantially increases the prospects of a puncture. 
   In another construction, shown in  FIG. 2A , the ends of strips  22  are formed with shallow recesses or central indentations  32  such that the wire ends are offset inward from the plastic strip ends  34 . The plastic ends are broader and more blunt than the wires, and less likely to cause unintended punctures. 
     FIGS. 10–13  illustrate automatic manufacture of sterile collection bags of the type described above. A placement component  32  picks up individual bag blanks  34  from a pack or magazine  36  and transfers the bags to a conveyor  38 . In a representative embodiment, this component can correspond to the model RPP-421 “pick and place” equipment of MGS Machine Corporation of Maple Grove, Minn., but other conventional “pick and place” machines can be used. The RPP-421 equipment includes a planetary drive for multiple pick-up heads  40  which include pressure-actuated pick-up members  42 . The pick-up members follow an epicyclic path from the pick-up point at the right of  FIG. 10  through the position indicated at  44  to the position indicated at  46  where an individual bag blank is released onto the conveyor  38 . Pick-up and release of the blanks is timed and coordinated so that the spacing between adjacent bags is uniform. The conveyor  38  can have projections  48  which assist in providing the desired spacing, in combination with the timed release of a bag on the upper surface of the conveyor in synchronism with the conveyor drive. An individual bag blank  34  is shown in  FIG. 10A , including the upper end portion  16  which is sealed, and the sealed side marginal portions. The bottom  50  of the bag blank is open in the illustrated embodiment, so that a desired sample, reagent, dilutent, etc. can be inserted after the bag manufacturing process described herein. For sample collection, the bottom  50  of the bag blank can be sealed from the outset. 
   From the constant speed, driven conveyor  38 , the bags are fed to another constant speed conveying mechanism  52  which includes upper and lower endless belts  54  and  56 . With reference to  FIG. 11 , the upper belt  54  has a lower run  58  biased relatively toward the upper run  60  of the lower belt  56 . These two belts are positioned to grasp the bag blanks  34  at approximately their center portions, and slide the upper end portions of the blanks along a horizontal support and guide plate  62 . This plate is offset toward the viewer in  FIG. 11  from the adjacent runs  58 ,  60  of the belts  54 ,  56 , but underlies the upper portions of the bag blanks. The opening tabs  30  ( FIG. 11A ) are applied by automatic equipment  64  as the bags are moved continuously in the direction of the arrow  66 . The equipment  64  is in the form of automatic label applicators such as the model  230  applicator of Accraply, Inc., of Plymouth, Minn. The tabs are provided on a backing roll  68  with only the end portions corresponding to the upper end portions of the tabs  30  having pressure sensitive adhesive. The backing strip is wound around feed and tension rollers to an applicator head  70  and applicator roll  72 . The applicator has an automatic product speed following feature such that a tab  30  is applied midway between the opposite side edges of each bag blank  34 . The first tab is applied by a first applicator unit at the top, where the upper end portion of the bag is supported on the plate  62 . The other tab is applied to the bottom surface by a second applicator component  64  which is offset downstream from the first unit and has its applicator head  70  and roller  72  aligned with an opening  74  through the plate  62  so that the bottom surface of the bag blank is exposed for a short distance. Following application of the tabs by the label applicators, the bare backing tape is wound on a take-up roll  76 . The condition of the bag following this procedure is illustrated in  FIG. 11A , with the opening tabs  30  adhesively secured to the opposite walls of the bag, but only at the top end portions, leaving a free or hanging end portion of each tab. 
   With reference to  FIGS. 12 and 12A , following automatic application of the oppositely located tabs, the belts  54 ,  56  convey the bag blanks to components  78  for applying the flexible closure strips  22 . As noted above, long lengths of the closure strip material can be formed in rolls  80  with a continuous strip  22  guided past an adhesive applying nozzle  82 . Each of the units  78  correspond to a “tin tie” applicator available from Bedford Technology Division of Bedford Industries of Worthington, Minn., in combination with a series 3000V hot melt adhesive applicator available from Nordson Corporation of Duluth, Ga. At the top and at the bottom, a continuous strip  22  having the cross-sectional structure shown in  FIG. 3  is routed around feed and tension rollers with the flat back of the strip  22  passing adjacent to one of the nozzles  82  where a continuous bead of adhesive is applied. From the nozzles, the strips  22  are brought together between pinch rolls  84 . This secures the top and bottom strips together at locations between the spaced bags being conveyed past the pinch rolls, and secures the strips to the bags in directly opposed relationship, as illustrated in  FIG. 12A , for example, over the upper portions of the tabs  30  and along the upper end portions  16  of each bag blank  34 . 
   With reference to  FIGS. 13 and 13A , following application of the continuous closure strip material, the bags  34  continue their travel by the center belts  54 ,  56  to a high speed cutting mechanism  86 . The cutting mechanism quickly and precisely cuts the strips  22  midway between adjacent bags, resulting in the bag shown in  FIG. 13A . In a representative embodiment, the high speed cutting mechanism includes a carriage  88  mounted on a rail  90  for movement back and forth in the direction of and contrary to the direction of travel of the bags  34 . Movement of the carriage is accomplished by a driven belt mechanism  92 . A knife  94  cooperates with an anvil  96  mounted on the carriage, and is actuated as the carriage is moved at the same speed as the bags and closure strips. More specifically, a sensor  93  detects passage of a bag  34  and actuates movement of the “flying knife” carriage in the direction of travel of the bag, with the knife and anvil positioned precisely between adjacent bags. The knife  94  is rapidly moved downward to cut the strip and back upward while moving in the same direction and at the same speed as the bags. The carriage then is quickly reciprocated back to the starting position for the next cutting operation. 
   After the quick and precise cutting of the closure strips  22 , the bags are fed to an exit conveyor  98  or other exit or collection mechanism. From the time of placement of the bags onto the first conveyor ( FIG. 10 ), to the final cutting operation ( FIG. 13 ), the bags preferably move continuously without stopping for any of the bag-forming operations. 
   While the preferred embodiment of the invention has been illustrated and described, it will be appreciated that various changes can be made therein without departing from the spirit and scope of the invention.