Abstract:
A method of forming carrier web having discrete lengths of mating zipper profile thereon. The zipper profile is fed from a supply roll to overlie a carrier web, tacked to the web and then severed from its supply roll.

Description:
BACKGROUND OF THE INVENTION 
     This invention is relates to methods of manufacturing carrier webs bearing zipper profile for use in making reclosable zipper bags with gusseted sides. 
     Heretofore reclosable plastic bags with gusseted sides have been made from plastic sheet having essentially uniform thickness for the front, rear and side walls including the gusset areas. While such side gusset bags featuring zippers have been produced, they have never provided a bag that could be opened to the full width of the gusset and also be fully closed by the zipper. In copending application Ser. No. 09/645,825, filed Aug. 25, 2000, entitled GUSSETED ZIPPER BAG, now U.S. Pat. No. 6,325,543, a reclosable bag with gusseted sides which overcomes the above mentioned problem is disclosed. This bag makes use of a carrier web bearing discrete sections of zipper profile. 
     SUMMARY OF THE INVENTION 
     The present invention concerns a new method of manufacturing carrier web bearing discrete sections of zipper profile for use in the manufacture of such gusseted zipper bags. One object is to produce for gusseted zipper bags a carrier web bearing intermittent zipper segments where the gusseted area to be captured by the mated zipper elements is thinner than the original bag film. A further object is to attach these mating zipper profile elements to the carrier web while maintaining the flanges of the mating elements separate and unsealed from each other. 
     The new method provides for discrete zipper sections to be attached to a carrier web at predetermined intervals lengthwise along the carrier web, which zipper sections may be mating profile elements or may comprise a unisexual element that is folded such that one part releasably engages the other part. 
     The disclosure further includes a method of folding these elements along the longitudinal axis of the carrier strip to provided mated zipper profiles. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a side elevation schematic view partially in section of an apparatus for forming a carrier web bearing intermittent segments of zipper profile; 
         FIG. 2  is a sectional view taken along reference lines  2 — 2  of  FIG. 1 ; 
         FIG. 3  is a sectional view taken along reference lines  3 — 3  of  FIG. 1 ; 
         FIG. 4  is an elevation view partially in section of a second embodiment of the apparatus for manufacturing a second embodiment of the carrier web carrying intermittent zipper profiles; 
         FIG. 5  is a sectional view taken along reference lines  5 — 5  of  FIG. 4 ; 
         FIG. 6  is a sectional view taken along reference lines  6 — 6  of  FIG. 4 ; and 
         FIG. 7  is a sectional view taken along reference lines  7 — 7  of FIG.  4 . 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     In  FIG. 1  the apparatus  10  has, at the right side of the drawing, drum  11  on which is wound a continuous strand of mated zipper profile  12 . Moving to the left and downstream from this drum or source  11  of zipper profile are the following components: zipper drive  13 , cutting station  14 , bar seal station  22 , further seal station  24 , carrier web drive  26  and take-up spool  28 . 
     Beginning at the drum  11 , the zipper drive delivers zipper  12  to cutting station  14  for cutting a segment or length of zipper profile. Adjacent drum  11  and below the cutting station is drum  16  on which is wound a supply of lower carrier web  17  in the form of a continuous plastic strip. 
     This lower carrier web  17  is fed to underlie the segment of zipper profile, and at station  18  the cut off segment of profile is tack sealed by sealer  19  to the carrier web. Next is drum  20  from which unwinds upper carrier web  21  which is fed to bar seal station  22  where the mating portions of the zipper are joined to the upper and lower carrier webs respectively. Next  1  downstream is further seal station  24  (to be described later), and finally carrier web drive  26  pulls the zipper/carrier web combination  27  and directs it onto take-up spool  28  for future use in the manufacture of gusseted bags. 
       FIG. 2  is a sectional view taken through along lines  2 — 2  of  FIG. 1  slightly downstream of cutting station  14 , showing how the mating profiles are guided and how the flanges of the mating profile elements are separated. The zipper  12  consists of male and female parts  12 M and  12 F respectively which are joined in the usual manner by interlocking the profile elements. Male zipper  12 M with its flange  33  and female zipper  12 F with its flange  34  are separated by guide plate  30  above which and below which the male and female flanges  33 ,  34  ride. A lower plate  29  which serves as an anvil cooperating with knife  15  is provided below guide plate  30  and above the feed-off of lower carrier web  17 . 
     Zipper drive  13  delivers zipper profile to the area  18  where tack seal  19  tacks the profile to lower carrier web  17 , and knife  15  cooperating with anvil  29  severs the trailing end of a segment of zipper profile from the front end of the following segment. The lower carrier web then moves the zipper profile segment further downstream to station  22  where upper carrier web  21  delivered from drum  20 , is positioned to overlie said zipper segment along with the lower carrier web below it, all of which is now situated between seal bars  32  and  35  at station  22 . 
     The bar seal station  22  is further illustrated in  FIG. 3  wherein upper carrier web  21  is below upper seal  32  and above the flange  33  of the male profile element  12 M. The flanges  33  and  34  of the upper and lower zipper elements being separated by guide plate  30 . 
     As evident, when the seal bars  32 ,  35  converge, upper carrier web  21  becomes sealed to male zipper flange  33  and lower carrier web  17  becomes sealed to flange  34  of female zipper, while the two flanges  33 ,  34  remain separated from each other because of the guide plate at between them, which prevents them from being sealed together. In addition seal bars  32  and  34  are notched in the areas of the male and female profiles so as to prevent any accidental sealing of the profiles to each other. Downstream from seal station  22  is carrier web drive  26  which pulls the resulting carrier web  27  comprising continuous webs  17  and  21  with the intermittently spaced zipper elements, where the male and female profile elements are releasably interlocked together, and the male and female elements respectively are permanently joined respectively to the upper and lower carrier webs  21 ,  17 . 
     For the sake of clarity and simplicity, FIG.  4  and other figures herein, having certain components substantially the same as components in  FIG. 1 , will use the same reference numbers for such components. Accordingly, in  FIG. 4  there is drum  11  with a continuous supply of zipper  11 Z the profile of which engages with itself. Such profile is depicted schematically in  FIG. 5  as an array of six spaced-apart arrows, which will be discussed in further detail later. 
     Downstream of drum  11  in  FIG. 4  is zipper drive  13  which directs the zipper to cutting station  14  and adjacent to tack seal station  18  where the zipper is tack sealed to lower carrier web  17 . Thereafter, seal bar  34  secures the lower carrier web  17  to the zipper. In this instance the heat delivered by the seal bar is closely controlled to prevent distorting the interlocking elements. At folding station  42  the zipper and its carrier web are folded about their central longitudinal axis as further schematically indicated in  FIG. 6  so as to cause one half of the profile of the zipper to interlock with the other half. 
     Upon complete folding, as schematically seen in  FIG. 7 , the zipper now has upper and lower parts  44 ,  45  releasably interlocked with carrier web above and below the folded profile. 
     At the end of this folding phase a cutting element  47  slices the lower carrier web  117  and zipper flanges lengthwise so that the zipper&#39;s upper element  44  and lower element  45  are fully separated. After the cutting element  47 , a sealing station  49  seal across the carrier webs at a point half way between zipper element sections. Downstream of this slicing phase is a final carrier web drive  48  which pulls the manufactured zipper product and feeds it to a spool for later combination with bag material.