Zipper applicator

[00002] 1. Field of the Invention

[00003] The present invention relates to the application of zippers to film used to make reclosable plastic bags. More specifically, the present invention relates to a roller-type zipper applicator with a zipper guide in which a disc with a circumference greater than at least one of the rollers of the applicator is positioned on the end of the roller with the smaller circumference.

[00004] 2. Description of the Prior Art

[00005] The present invention relates to improvements in the package-making art and may be practiced in the manufacture of reclosable thermoplastic bags and packages of the type that may be used for various consumer products. Such packages often include a form of peel-seal to render the package moisture and/or airtight prior to the initial opening and/or as a tamper-evident seal. A zipper means protects any remainder of the product therein after the initial opening.

[00006] The indicated art is fairly well developed but nevertheless remains open to improvements contributing to increased efficiency and cost-effectiveness in the package-making art. In the prior art, McMahon et al. (U.S. Pat. No. 4,909,017) discloses a method of making a form-fill bag having a reclosable fastener. Prior to entering a form-fill and seal (FFS) machine, fastener strips are attached to the surface of the film at bag length intervals transverse to the running direction of the film. The fastener strips contain pre-joined interlocked rib and groove strips. Only one of the strips is attached to a top surface of the film, with the other strip facing upwardly or, in other words, inwardly toward the interior of the bag to be formed. The attached strips are secured at the center of the film and each strip is less than half of the film's width. The film is then advanced to the FFS machine and drawn over a forming collar and about the filling tube, with the longitudinal side edge margins of the film brought together and seamed with a fin seal to form a tube. Cross-seals are made across the tube to join the unattached fastener strip to form the top and bottom of the bag.

[00007] A problem is sometimes encountered during the attachment of the fastener or zipper to the film. Typically a roller-type zipper applicator engages one profile of the zipper and positions the zipper on the film used on the FFS machine. The other profile of the zipper is interlocked with the engaged profile and moves to be later attached to the film as a result of the profiles being interlocked. However, if the profiles are not securely interlocked or longitudinally slide against each other, the profiles may significantly misalign in relation to each other as the roller moves the profile on which it is engaged. This misalignment of the zipper profiles makes it difficult to properly seal the zipper to the film, resulting in a defective zipper after formation of the reclosable bag. An improvement in the zipper applicator would be the ability to engage both profiles with at least one or more rollers of the zipper applicator in order to calibrate the movement of both profiles to the movement of the rollers. The calibrated movement of both profiles would prevent the zipper profiles from misaligning with each other before attachment to the film used to make a reclosable bag.

[00008] Accordingly, the present invention relates to a zipper applicator that engages both profiles of an interlocked zipper as the zipper or fastener strip is guided onto a supply of thermoplastic film used to make a reclosable bag. Prior to attachment on the film, a length of interlocked zipper is separated from a continuous supply and is advanced by a roller-type zipper applicator on a zipper guide. A first interlocked profile of the zipper is engaged by at least one roller of the zipper applicator. A knurled or serrated disc, mechanically attached to an end section of at least one roller of the zipper applicator, engages a web of the second interlockable profile that extends beyond the width of the first profile. As a result of their attachment, the disc and the roller move the profiles at the same speed so that the profiles remain aligned as they are moved on the zipper guide. The length of zipper is then attached to a surface of the thermoplastic film used to make the reclosable bag. As an alternative to attaching a disc to the end of a roller, a roller of the zipper applicator that is stepped with an extending area may engage the extended web.

[00014] Referring now to the drawings in detail wherein like numerals indicate like elements throughout the several views, the zipper applicator 10 of the present invention is shown in FIG. 1. As shown in the figure, a zipper 12 is advanced on a zipper guide 14 of the zipper applicator in movement direction “A”. The zipper is advanced and transversely fed to thermoplastic film 16 used to make a reclosable bag; however, the zipper may be fed to the film in other directions known to those skilled in the art. The zipper 12 that is preferably used with the zipper applicator 10 is of the type comprising two interlocked profiles 18, 20 in which an attaching web 22 of the profile 20 extends beyond the width of an attaching web 23 of the profile 18, with the width of the profiles being transverse to the longitudinal ends of the zipper.

[00015] As the zipper 12 is advanced by the zipper applicator 10, a first roller 24 engages the profile 18 of the zipper and further advances the zipper until it is engaged by a second roller 26. The second roller 26 also engages web 23 of the profile 18 but additionally engages the web 22 of the second profile 20. Specifically, a disc 28 that is mechanically attached to an end section of the second roller 26 engages the web 22 by having a diameter larger than the diameter of the second roller. Preferably the disc 28 has a serrated, stainless steel surface that engages the web 22, with the disc having a diameter approximately one sixteenth of an inch greater than the diameter of the second roller 26. By its attachment to the second roller 26, the disk 28 and the second roller move both profiles 18, 20 at the same speed. The result is that the profiles 18, 20 remain aligned with each other as they are moved on the zipper guide 14 until the profiles are sealed to the film 16 by a sealing bar 32. Alternatively, and as shown in FIG. 2, the end section of the second roller 26 could include a stepped extending area 30 instead of the disc 28.

[00016] In an alternative view of FIG. 3, the disc 28 directly engages the web 22 of the profile 20 while the second roller 26 of the web engages the web 23 of the profile 18. The disc 28 and the second roller 26 also reduce movement of the zipper 12 in direction “B” by engaging the profile 20. By reducing or eliminating movement in direction “B”, the zipper stays further aligned on the zipper guide 14 and remains perpendicular to the movement of the film 16 during its attachment to the film.

[00017] For the illustrative purposes of a perspective view of the zipper applicator 10 of FIG. 1, the zipper applicator comprises two rollers 24, 36 without attached discs, and two rollers 26, 38 with attached discs 28. Preferably, the zipper applicator 10 of the present invention has additional rollers 40, 42 and 44 with all of the identified rollers driven by a motor drive 46 as shown in the arrangement of FIG. 4. In FIG. 4, the rollers 24, 36, 40 and 42 do not have an attached disc 28 and the rollers 26, 38 and 44 have an attached disc 28.

[00018] Thus, the several aforementioned objects and advantages of the present invention are most effectively attained. Although preferred embodiments of the invention have been disclosed and described in detail herein, it should be understood that this invention is in no sense limited thereby and its scope is to be determined by that of the appended claims.