Method of applying a slider to a fastener-carrying plastic web

Information

  • Patent Grant
  • 6526726
  • Patent Number
    6,526,726
  • Date Filed
    Thursday, August 10, 2000
    23 years ago
  • Date Issued
    Tuesday, March 4, 2003
    21 years ago
Abstract
A method of applying a slider to a fastener-carrying web of plastic film. The fastener includes interlockable profiles and fins depending from the respective profiles. One of the fins is attached to the web of plastic film such that the profiles are immediately adjacent to the web. The fastener is folded away from the web about the attached fin such that the profiles and proximate portions of the fins are oriented at an angle, preferably about 90 degrees, relative the web. Because the profiles and proximate fin portions are oriented at an angle relative to the web, they can be easily accessed and controlled for applying the slider to the profiles and performing other fastener-related operations.
Description




FIELD OF THE INVENTION




The present invention generally relates to reclosable plastic bags and, more particularly, to a method of applying a slider to a fastener-carrying web of plastic film.




BACKGROUND OF THE INVENTION




In one method of making slider-operated reclosable plastic bags, a continuous fastener is sealed to opposing longitudinal edges of a folded web of thermoplastic film moving in a longitudinal direction. To form individual bags, the folded web is sealed at bag-width distances apart along side seals that are generally transverse to the direction of web movement. To facilitate opening and closing the fastener, sliders are applied to the fastener at bag-width distances apart either just before or just after the side seals are formed in the folded web. In another method of making slider-operated reclosable plastic bags, the sliders are applied to the fastener prior to attaching the fastener to the moving web. In each of the above-noted methods, the fastener is positioned relative to the moving web such that the fastener can be easily accessed and controlled for installing the sliders.




To make slider-operated reclosable plastic bags in which the fastener is buried within a header or pocket near the top of the bags, the fastener is initially sealed near a center, rather than an edge, of a web of thermoplastic film moving in a longitudinal direction. The moving web is then folded in half along a longitudinal fold with the fastener inside the web and proximate the fold. To form individual bags, the folded web is sealed at bag-width distances apart along side seals that are generally transverse to the direction of web movement. Unless sliders are applied to the fastener prior to attaching the fastener to the moving web, it is difficult to access and control the fastener for installing sliders and performing other fastener-related operations after the fastener is attached near the center of the moving web. Because the fastener is parallel and close to the same plane as the web, gaining access to the fastener for applying sliders becomes limited by the close proximity of the fastener to the web.




SUMMARY OF THE INVENTION




Accordingly, an object of the present invention is to provide a method of applying a slider to a fastener-carrying web of plastic film that allows the fastener to be easily accessed and controlled for installing the slider and performing other fastener-related operations after the fastener is attached to the web.




This and other objects are realized by the following method of applying a slider to a fastener-carrying web of plastic film. The fastener includes interlockable profiles and fins depending from the respective profiles. One of the fins is attached to the web of plastic film such that the profiles are immediately adjacent to the web. The fastener is folded away from the web about the attached fin such that the profiles and proximate portions of the fins are oriented at an angle, preferably about 90 degrees, relative the web. Because the profiles and proximate fin portions are oriented at an angle relative to the web, they can be easily accessed and controlled for applying the slider to the profiles and performing other fastener-related operations.











BRIEF DESCRIPTION OF THE DRAWINGS




Other objects and advantages of the invention will become apparent upon reading the following detailed description and upon reference to the drawings in which:





FIG. 1

depicts a method of making a slider-operated fastener;





FIG. 2

is a view taken along line


2





2


in

FIG. 1

;





FIG. 3

is a view taken along line


3





3


in

FIG. 1

;





FIG. 4

is a view taken along line


4





4


in

FIG. 1

; and





FIG. 5

depicts a method of forming, filling and sealing reclosable plastic bags employing the slider operated fastener illustrated in FIG.


1


.











While the invention is susceptible to various modifications and alternative forms, a specific embodiment thereof has been shown by way of example in the drawings and will herein be described in detail. It should be understood, however, that it is not intended to limit the invention to the particular forms disclosed, but on the contrary, the intention is to cover all modifications, equivalents, and alternatives falling within the spirit and scope of the invention as defined by the appended claims.




DESCRIPTION OF ILLUSTRATED EMBODIMENTS




Turning to the drawings,

FIG. 1

depicts a method of making a slider-operated fastener for use in reclosable plastic bags. In the method, there is provided a continuous fastener


10


including first and second opposing tracks


12


and


14


. The tracks


12


and


14


include respective first and second interlocking profiles


16


and


18


and respective first and second fins


20


and


22


extending downward from the respective profiles


16


and


18


. The profile


16


preferably includes a rib, and the profile


18


preferably includes a groove for receiving the rib. Further details concerning the construction of the profiles


16


and


18


may be obtained from U.S. Pat. No. 5,007,143 to Herrington, which is incorporated herein by reference in its entirety. The fastener


10


may be unwound from a spool or the like.




The fastener


10


is conveyed along a web of plastic film


50


to a fin seal station


100


(FIGS.


1


and


2


). The fin seal station


100


includes a guide


102


with a splitter


104


that extends between the fins


20


and


22


. The fin seal station


100


also includes a heated tack or seal bar


106


. The bar


106


is reciprocated into and away from the fin


22


and the splitter


104


while the fastener


10


and the web


50


are temporarily stopped. When this occurs, the fin


22


is lightly tacked or sealed to the web


50


at a seal line


108


(FIGS.


3


and


4


).




As the web


50


and fastener


10


are advanced past the fin seal station


100


the fastener


10


engages a plow or ramp


110


that folds the fastener


10


about the seal line


108


to an orientation approximately perpendicular to the web


50


(see, for example, FIG.


3


). Rollers, guides and the like (not shown) may be located downstream from the plow


110


to assist in maintaining the fastener


10


in this orientation perpendicular to the web.




The fastener-carrying web


50


is conveyed by to a preseal station


112


. The preseal station includes a pair of reciprocating seal bars


24


and


26


. Either both of the seal bars


24


and


26


move back and forth between open and closed positions, or one of the seal bars is stationary while the other seal bar moves back and forth. At least one seal bar is heated. The other bar may be heated as well, or may simply serve as a compliant backing against which the heated seal bar applies pressure and temperature when the seal bars


24


and


26


are brought together. The temperature, pressure, and dwell time of the seal bars


24


and


26


are properly adjusted to allow the seal bars


24


and


26


to impart a U-shaped preseal


28


. While the web


50


is temporarily stopped at the preseal station, the fins


20


and


22


are sealed to each other along the U-shaped preseal


28


. The preseal


28


includes a pair of opposing sides


28




a


,


28




b


and a bottom


28




c


bridging the opposing sides. The opposing sides


28




a


,


28




b


are generally located along an upper portion of the fins


20


and


22


and extend downward from the interlocked profiles


16


and


18


. The bottom


28




c


is located along a lower portion of the fins


20


and


22


. The seal bar


24


has a U-shaped projection


30


corresponding to the shape of the preseal


28


. Although the preseal


28


is illustrated as being generally U-shaped, the area between the sides


28




a


,


28




b


of the preseal


28


may be sealed as well so that the preseal


28


appears like a solid rectangle rectangle, or a bracket shape to minimize the heat imparted on the lower portion of the fins


20


and


22


causing stretching, shrinkage and wrinkling of fins. The preseal


28


preferably does not extend into the profiles


16


and


18


due to the technique for installing sliders on the fastener


10


later in the manufacturing process.




After forming the preseal


28


, the fastener-carrying web


50


is conveyed to a notching station


114


. The notching station


114


includes a pair of reciprocating cutters


32


and


34


. Either both of the cutters


32


and


34


move back and forth between open and closed positions, or one of the cutters is stationary while the other cutter moves back and forth. The cutter


32


forms a rectangular projection, while the cutter


34


forms a rectangular hole for receiving the projection. Other shapes may be used as well. The web


50


is temporarily stopped at the notching station with the preseal


28


aligned between the separated cutters


32


and


34


. While the web


50


is stopped, the cutters


32


and


34


are brought together such that the projection of the cutter


32


punches a rectangular section


36


through the hole of the cutter


34


, thereby leaving a U-shaped notch


38


in the fastener


10


. Prior to being punched out, the section


36


is disposed between the opposing sides


28




a


,


28




b


of the preseal


28


and above the bottom


28




c


of the preseal


28


. Therefore, the preseal


28


generally encompasses the notch


38


and defines a periphery thereof such that the preseal provides a leak-resistant barrier to entry into an interior of the fastener


10


between the fins


20


and


22


via the notch


38


. As discussed below, the leak-resistant barrier effectively minimizes leaks in the reclosable plastic bags ultimately formed by the manufacturing process.




After forming the notch


38


, the fastener-carrying web


50


is conveyed to a slider insertion station


116


(FIGS.


1


and


3


). While the web


50


is temporarily stopped at the slider insertion station


116


, a slider


40


from a source of multiple sliders is positioned within the notch


38


. Further details concerning the source of multiple sliders may be obtained from U.S. patent application Ser. No. 09/307,893 entitled “Assembly and Accumulation of Sliders for Profiled Zippers”, filed May 10, 1999, and incorporated herein by reference in its entirety. The slider


40


is then threaded onto the fastener


10


in response to relative movement of the slider


40


and the fastener


10


. Further details concerning the equipment for installing the slider


40


onto the fastener


10


via the notch


38


may be obtained from U.S. patent application Ser. No. 09/307,937 entitled “Zipper and Zipper Arrangements and Methods of Manufacturing the Same”, filed May 10, 1999, and incorporated herein by reference in its entirety.




After installing the slider


40


onto the fastener


10


, the fastener-carrying web


50


is conveyed to an end stop applicator


118


. The end stop applicator


118


applies terminations or end stops


42


and


44


to the respective fastener ends


46


and


48


on opposite sides of the notch


38


. In the plastic bags ultimately formed by the manufacturing process, the end stop


42


will be located at the fastener end


46


of one bag, while the end stop


44


will be located at the fastener end


48


of the adjacent bag. The end stops perform three primary functions: (1) preventing the slider


40


from going past the ends of the fastener, (2) holding the profiles together to resist stresses applied to the profiles during normal use of the plastic bag, and (3) minimizing leakage from inside of the plastic bag out through the fastener ends.




In one embodiment, the end stop applicator


118


includes a pair of chilled, reciprocating molds


51


and


52


. Either both of the molds


51


and


52


move back and forth between open and closed positions, or one of the molds is stationary while the other mold moves back and forth. While the web


50


is temporarily stopped, the molds


51


and


52


close around the fastener ends


46


and


48


. A predetermined amount of melted/softened plastic material is then forced around and between the profiles


16


and


18


at the fastener ends


46


and


48


by a conventional back pressure device (not shown) coupled to a supply tube. The molds


51


and


52


form channels for receiving the plastic material and guiding it to the fastener ends


46


and


48


. Further details concerning the injection-molded end stops


42


and


44


and the method of making the same may be obtained from U.S. patent application Ser. No. 09/636,244 entitled “Injection-Molded End Stop for a Slider-Operated Fastener”, filed concurrently herewith, and incorporated herein by reference in its entirety.




Instead of applying injection-molded end stops, other types of end stops may be applied to the fastener ends


46


and


48


, including those disclosed in U.S. Pat. Nos. 5,924,173, 5,833,791, 5,482,375, 5,448,807, 5,442,837, 5,405,478, 5,161,286, 5,131,121, 5,088,971, and 5,067,208, which are incorporated herein by reference in their entireties. In U.S. Pat. No. 5,067,208, for example, each end stop is in the form of a fairly rigid strap/clip that wraps over the top of the fastener. One end of the strap is provided with a rivet-like member that penetrates through the fastener fins and into a cooperating opening at the other end of the strap.




While the fastener-carrying web


50


is temporarily stopped in the method depicted in

FIG. 1

, the various stations simultaneously perform their respective functions on different parts of the continuous fastener


10


spaced approximately at bag-width distances apart. Therefore, as the preseal station


112


forms a new preseal


28


, (1) the notching station


114


forms a new notch


38


within a previously formed preseal, (2) the slider insertion station


116


installs a slider


40


via a previously formed notch, and (3) the end stop applicator


118


applies new end stops


42


and


44


proximate a previously installed slider. After each of the stations has completed its respective function on the stopped fastener


10


, movement of the web


50


is resumed. The web


50


is moved for approximately a bag-width distance so that the next station can perform its respective function. The preseals


28


are advantageous in that they allow the fastener


10


to be controlled during such downstream operations as notch formation, slider installation, and end stop installation and when the fastener


10


is tensioned by various rollers in the bag making machine. The preseals


28


keep the interlocked profiles


16


and


18


together and prevent them from moving longitudinally relative to each other. In addition, by folding the fastener


10


away from the web


50


, the fastener


10


can be easily accessed and controlled for the presealing, notching, slider installing and end stop installing operations.




After the end stop application


118


, the fastener


10


is folded down onto the web


50


by a second plow or ramp


120


(FIGS.


1


and


4


). The fastener


10


and web


50


are then ready for being formed into individual bags with reclosable fasteners.




The fastener-carrying web


50


is conveyed to a folding station


54


(FIG.


5


). At the folding station


54


, the web


50


is folded in half with the fastener


10


inside the web


50


and proximate the fold


56


. To fold the web


50


, the web


50


is conveyed over a horizontal roller


58


, under a triangular folding board


60


, and then between a pair of closely spaced vertical rollers


62


. The folded web


50


includes a pair of overlapping panels


64


and


66


joined along the fold


56


. Other embodiments could include the fastener


10


inside the web opposite the fold at the web panel edges. For exposed zipper, the fastener would be sealed to the web proximate to the top edge of the web.




After folding the web


50


, the fastener fins


20


and


22


are permanently sealed to the respective web panels


66


and


64


by respective seal bars


68


and


70


. The seal bars


68


and


70


are sufficiently wide that they generate the fin seals across the entire width of a bag produced by the method in FIG.


5


. Either both of the seal bars


68


and


70


move back and forth between open and closed positions, or one of the seal bars is stationary while the other seal bar moves back and forth. The fastener-carrying web


50


is temporarily stopped while the seal bars are brought together to seal the fastener


10


to the web


50


. Both of the seal bars


68


and


70


are preferably heated. The temperature, pressure, and dwell time of the seal bars


68


and


70


are properly adjusted to allow the seal bars


68


and


70


to generate the permanent fin seals. In an alternative embodiment, the seal bars


68


and


70


are replaced with a static heat sealing mechanism such as a pair of hot air blowers that blow heated air onto the respective fastener fins.




After sealing the fins


20


and


22


to the respective web panels


66


and


64


, the web panels


64


and


66


are sealed to each other along a side seal


72


by a pair of reciprocating seal bars


74


and


76


. The side seal


72


is transverse to a direction of movement of the folded web


50


and is aligned with a center of the notch


38


(and preseal


28


). Also, the side seal


72


extends from the folded bottom


56


to an open top


53


of the folded web


50


. Either both of the seal bars


74


and


76


move back and forth between open and closed positions, or one of the seal bars is stationary while the other seal bar moves back and forth. The folded web


50


is temporarily stopped while the seal bars are brought together to seal the web panels


64


and


66


to each other. At least one seal bar is heated. The other bar may be heated as well, or may simply serve as a compliant backing against which the heated seal bar applies pressure and temperature when the seal bars


74


and


76


are brought together. The temperature, pressure, and dwell time of the seal bars


74


and


76


are properly adjusted to allow the seal bars


74


and


76


to generate the side seal


72


.




After generating the side seal


72


, the folded web


50


is conveyed to a cutter


78


for separating the folded web


50


into individual plastic bags. While the folded web


50


is temporarily stopped, the cutter


78


cuts the folded web


50


along a center of the side seal


72


to produce the individual plastic bag


80


. The plastic bag


80


is opened with an opening device


79


and filled with a product through its open top


53


at a filling station


82


. Finally, the open top


53


is sealed by a heat sealing mechanism


84


to form final seal


86


. The end result is a filled and sealed bag


80


ready for shipment to a customer such as a grocery store or convenience store.




While the web


50


is temporarily stopped in the method depicted in

FIG. 2

, the various stations simultaneously perform their respective functions on different parts of the continuous web


50


. For example, when the web


50


is stopped, (1) the fastener fins


20


and


22


can be permanently sealed to the respective web panels


64


and


66


by respective seal bars


68


and


70


, (2) the web panels


64


and


66


carrying previously sealed fastener fin sections can be sealed to each other along a side seal


72


by the seal bars


74


and


76


, and (3) the folded web


50


can be cut along a previously generated side seal. After each of the stations has completed its respective function on the stopped web


50


, movement of the web


50


is resumed.




While the present invention has been described with reference to one or more particular embodiments, those skilled in the art will recognize that many changes may be made thereto without departing from the spirit and scope of the present invention. For example, the fastener may be folded prior to being attached to the web. The fastener profiles are folded relative to distal portions of the fastener fins, and then one of the distal fin portions is attached to the web. Also, the equipment used in the fastener and bag manufacturing processes may be modified so that the processes are entirely continuous with no temporary stoppages in the movement of the fastener or bag making web. Thus, any and all of the unit operations may be performed (1) during a continuous web motion such as a rotary or continuous draw machine or (2) during the web index of an intermittent motion machine. Each of these embodiments and obvious variations thereof is contemplated as falling within the spirit and scope of the claimed invention, which is set forth in the following claims.



Claims
  • 1. A method of applying a slider to a fastener-carrying web of plastic film, comprising:providing said web of plastic film; providing a fastener including first and second opposing tracks, said first and second tracks including respective first and second interlocking profiles and respective first and second fins extending from said respective first and second profiles; sealing one of said first and second fins to said web of plastic film; folding said fastener relative to said web of plastic film wherein said fastener is at an angle to said web of plastic film; and mounting the slider to said fastener.
  • 2. The method of claim 1 further including sealing said first and second fins to each other at spaced preseals prior to said mounting said slider.
  • 3. The method of claim 1 further including forming a notch in said first and second interlocking profiles prior to said mounting said slider.
  • 4. The method of claim 1 further including sealing said first and second fins at spaced preseals, and forming a notch in each said respective preseal and in said first and second interlocking profiles prior to said mounting said slider onto said zipper.
  • 5. The method of claim 1 further including folding said slider-carrying fastener onto said web of plastic film.
  • 6. The method of claim 1 further including folding said web of plastic film to form two sides of a bag, sealing the other of said first and second fins to said web of plastic film, forming side seals in said web of plastic film for individual bags, and separating said web of plastic film into individual bags.
  • 7. The method of claim 1 further including forming a tube out of said web of plastic film to form two sides of a bag, sealing the other of said first and second fins to said web of plastic film, forming side seals in said web of plastic film for individual bags, and separating said web of plastic film into individual bags.
  • 8. A method of applying sliders to a fastener-carrying web of plastic film, comprising:advancing said web of plastic film along a predetermined path; providing a fastener including first and second opposing tracks with respective first and second respective interlocking profiles and respective first and second fins depending from said respective first and second profiles; sealing one of said fins to said web of plastic film; folding said fastener away from said web of plastic film about said sealed fin; mounting sliders on said fastener at predetermined locations; and folding said slider-carrying fastener onto said web of plastic film.
  • 9. The method of claim 8 further including sealing said first and second fins at said predetermined locations.
  • 10. The method of claim 8 further including forming at said predetermined locations a notch in said first and second respective interlocking profiles and said first and second fins prior to said mounting said sliders.
  • 11. The method of claim 8 further including folding said web of plastic film in half to form two sides of said bags.
  • 12. The method of claim 8 further including folding said web of plastic film in half to form two sides of said bags, and forming side seals for said bags in said web of plastic film.
  • 13. The method of claim 8, further including folding said web of plastic film in half to form two sides of said bags, forming first and second fin seals to said two sides of said bags, forming side seals for said bags in said web of plastic film.
  • 14. The method of claim 8 further including folding said web of plastic film in half to form two sides of said bags, forming side seals for said bags in said web of plastic film, and cutting said web of plastic film along said side seals to separate said bags.
  • 15. The method of claim 8 further including folding said web of plastic film in half to form two sides of said bags, forming first and second fin seals to said two sides of said bags, forming side seals for said bags in said web of plastic film, and cutting said web of plastic film along said side seals to separate said bags.
  • 16. A method of making plastic bags that have a fastener opened and closed by a slider, comprising:advancing a web of plastic film along a path; advancing a fastener along said path adjacent said web of plastic film, said fastener including first and second tracks, said first and second tracks including respective first and second interlocking profiles and respective first and second fins depending from said respective first and second profiles, sealing one of said first and second fins to said web of plastic film; folding said fastener away from said web of plastic film about said one of said first and second fins sealed to said web of plastic film; sealing said first and second fins to each other at selected locations; removing at least a portion of said first and second tracks and said first and second fins at said selected locations; mounting a slider at said selected locations onto said first and second tracks; and folding said fastener onto said web of plastic film.
  • 17. The method of claim 16 further including folding said web of plastic film to form two sides of said bags.
  • 18. The method of claim 16 further including forming a tube out of said web of plastic film to form two sides of a bag.
  • 19. The method of claim 16 further including folding said web of plastic film to form two sides of said bags; andsealing the other of said first and second fins to said web of plastic film.
  • 20. The method of claim 16 further including folding said web of plastic film to form two sides of said bags;sealing the other of said first and second fins to said web of plastic film; and forming side seals in said web of plastic film.
  • 21. The method of claim 16 further including folding said web of plastic film to form two sides of said bags;sealing the other of said first and second fins to said web of plastic film; forming side seals in said web of plastic film; and forming separated bags by cutting said web of plastic film along said side seals.
  • 22. A method of applying a slider to a fastener-carrying web of plastic film, comprising:providing a fastener including first and second interlockable profiles and a fin depending from each of said first and second interlockable profiles; attaching one of said fins of said fastener to said web of plastic film such that said profiles are immediately adjacent to said web; folding said attached fastener away from said web such that said profiles are spaced from said web; and applying the slider to said profiles of said folded fastener.
  • 23. The method of claim 22 wherein said step of folding said attached fastener away from said web includes folding said attached fastener about said attached fin.
  • 24. The method of claim 22 wherein said step of folding said attached fastener away from said web includes orienting said profiles generally perpendicular to said web.
  • 25. The method of claim 22 further including folding said fastener back onto said web such that said profiles are immediately adjacent to said web after said step of applying said slider to said profiles.
  • 26. A method of applying a slider to a fastener-carrying web of plastic film, comprising:providing a fastener including interlockable profiles and fins depending from said respective profiles; attaching one of said fins to said web of plastic film such that said profiles are immediately adjacent to said web; folding said fastener away from said web about said attached fin such that said profiles and proximate portions of said fins are oriented at an angle relative to said web; and applying a slider to said profiles of said folded fastener.
  • 27. A method of applying a slider to a fastener, comprising:providing a fastener including interlockable profiles and fins depending from said respective profiles; folding said profiles relative to distal portions of said fins such that said profiles are oriented at an angle relative to said distal fin portions; attaching one of said distal fin portions to a web of plastic film such that said profiles and proximate portions of said fins are oriented at an angle relative to said web; and applying a slider to said profiles of the folded fastener.
  • 28. The method of claim 27 wherein said step of folding said profiles relative to said distal fin portions includes orienting said profiles generally perpendicular to said distal fin portions.
  • 29. The method of claim 27 further including folding said fastener back onto said web such that said profiles are immediately adjacent to said web after said step of applying said slider to said profiles.
REFERENCE TO RELATED APPLICATIONS

The present application is being filed concurrently with U.S. patent application Ser. No. 09/636,244 entitled “Injection-Molded End Stop for a Slider-Operated Fastener,” U.S. patent application Ser. No. 09/636,421 entitled “Slider-Operated Fastener With Spaced Notches and Associated Preseals,” U.S. patent application Ser. No. 09/635,451 entitled “Method and Apparatus for Guiding a Fastener in a Bag Making Machine,” and U.S. patent application Ser. No. 09/637,038 entitled “Method and Apparatus for Making Reclosable Plastic Bags Using a Pre-applied Slider-Operated Fastener,” all of which are incorporated herein by reference in their entireties.

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