Application system for sliders at form-fill-seal machine

A method and apparatus for manufacturing reclosable bags having slide zippers on a form-fill-seal machine is provided. In a first embodiment the sliders are preapplied to the zipper and the bags are made using conventional form-fill-seal techniques. In a second embodiment a coil of sliders is fed into the form-fill-seal machine where the sliders are applied to the zippers by an insertor mechanism. In a third embodiment a magazine of individual or connected sliders is used to feed a slider insertor mechanism which then applies the sliders to the interlocked zippers. In a fourth embodiment bulk sliders are introduced into a vibratory feeding bowl which then orients and feeds the sliders to the slider insertor mechanism.

BACKGROUND OF THE INVENTION
 1. Field of the Invention
 The present invention relates to reclosable plastic bags having slide
 zippers. More particularly, the present invention relates to a method and
 apparatus for making slide-zippered reclosable bags on form-fill-seal
 (FFS) machines.
 2. Description of the Prior Art
 Methods and apparatus for manufacturing reclosable plastic bags on FFS
 machines using reclosable zippers are well-known in the art. These prior
 art methods and apparatus, however, are limited to interlocking zippers
 which are directly opened and closed by the hands of the bag user and are
 not designed for the utilization of a slider for opening and closing the
 zipper.
 The method and apparatus of the present invention, on the other hand,
 relate specifically to reclosable bags having a slide zipper. Reclosable
 bags having slide zippers are generally more desirable to consumers than
 bags which have traditional interlocking zippers since it is much easier
 for the user to open and close bags having a slide zipper. It is thus
 commercially highly desirable and advantageous to provide a method of and
 apparatus for manufacturing slide-zippered reclosable plastic bags in a
 continuous, automated process.
 Slide zippers for use with plastic bags are well known in the reclosable
 fastener art. Examples of conventional slide zippers can be found in U.S.
 Pat. Nos. 5,007,143, 5,008,971, 5,131,121 and 5,664,299. Typical slide
 zippers comprise a plastic zipper having two interlocking profiles and a
 slider for opening and closing the zipper. The slider straddles the zipper
 and has a separator at one end which is inserted between the profiles in
 order to force them apart, that is, the separator plows between the
 profiles forcing them to disengage. The other end of the slider is
 sufficiently narrow to be able to close the zipper.
 Recently, a new type of slider zipper has been developed which, as
 discussed fully below, improves on prior art slide zippers and includes
 features which facilitate the manufacture of bags in automated form fill
 processes.
 It is therefore the object of the present invention to provide a unique and
 novel method and apparatus for making slide-zippered bags on an FFS
 machine.
 SUMMARY OF THE INVENTION
 The present invention is, in two aspects, a method of making slide-zippered
 plastic bags on an FFS machine and an apparatus for making slide-zippered
 plastic bags on an FFS machine.
 In a first embodiment of the present invention, the slider is preapplied to
 the zipper at the zipper manufacturing site. Then, at the FFS site the
 plastic bags are made on the FFS machine utilizing conventional and
 well-known FFS technology, such as disclosed in U.S. Pat. No. 4,894,975.
 To facilitate guiding and alignment of the zipper, the zipper is provided
 with guiding flanges.
 In a second embodiment of the present invention, the plastic bags are made
 on the FFS machine and the zipper is attached to the bags in the
 conventional manner. A coil of sliders, each slider being connected to its
 two adjacent sliders, is used to feed the sliders into the FFS machine,
 which sliders are then applied by a slider insertor mechanism to the
 zipper. In a slight variation of this embodiment, the slider insertor
 mechanism can be positioned to apply the sliders to the zipper before the
 zipper is fed into the FFS machine for sealing to the plastic bags.
 In a third embodiment of the present invention, the plastic bags are made
 on the FFS machine and the zipper is attached to the bags in the
 conventional manner. A magazine of individual or interconnected sliders is
 used to feed a slider insertor mechanism which applies the sliders to the
 zipper. In a slight variation of this embodiment, the slider insertor
 mechanism can be positioned to apply the sliders to the zipper before the
 zipper is fed into the FFS machine for sealing to the plastic bags.
 In a fourth embodiment of the present invention, the plastic bags are made
 on the FFS machine and the zipper is attached to the bags in the
 conventional manner. Bulk sliders are introduced into a vibratory feeding
 bowl which orients and feeds the sliders to the slider insertor mechanism
 which applies the sliders to the zipper. In a slight variation of this
 embodiment, the slider insertor mechanism can be positioned to apply the
 sliders to the zipper before the zipper is fed into the FFS machine for
 sealing to the plastic bags.
 The present invention will now be described in more complete detail with
 reference being made to the figures identified below wherein the same
 numerals represent identical elements.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
 FIG. 1 shows a cross sectional view of interlockable zipper 10 which may be
 used to practice the present invention. The zipper 10 is formed of a
 resilient plastic material such as polyethylene and comprises a first
 profile 12 and a second profile 14. The zipper 10 is disposable across the
 mouth 11 of a plastic bag 13, as shown in FIG. 2. For purposes of this
 description the bag 13 will be assumed to be oriented with its mouth 11 on
 top as depicted in FIG. 2.
 The first profile 12 has a base 15 having an inner side 16 and outer side
 18, a top portion 20, a bottom surface 22, a flange 24, a top hooked arm
 26 and a bottom hooked arm 28.
 The top hooked arm 26 and the bottom hooked arm 28 of the first profile 12
 have hooked ends 30 and 32 which are directed away from each other. Thus,
 the hooked end 30 of top hooked arm 26 is oriented upwardly while the
 hooked end 32 of the bottom hooked arm 28 is oriented downwardly. As is
 clear from FIG. 1, the top hooked arm 26 is longer and thinner than the
 bottom hooked arm 28. The top hooked arm 26 is thus more flexible than the
 bottom hooked arm 28, thereby providing for ease of opening of the zipper
 10 from the outside of a bag employing the zipper 10. Conversely, because
 bottom hooked arm 28 is shorter and thicker than top hooked arm 26, and
 thus less flexible, the internal opening force will be greater.
 The second profile 14 likewise has a base 33 having an inner side 34 and an
 outer side 36, a top portion 38, a bottom surface 40, a flange 42, a top
 hooked arm 44 and a bottom hooked arm 46. The top hooked arm 44 and bottom
 hooked arm 46 of the second profile 14 have hooked ends 48 and 50 which
 are directed towards each other and positioned and sized to engage the
 hooked ends 30, 32 of the first profile hooked arms. Thus, the top hooked
 arm 44 has a downwardly oriented hooked end 48 which is engageable with
 the hooked end 30 of the top hooked arm 26 of the first profile 12 and the
 bottom hooked arm 46 has an upwardly oriented hooked end 50 which is
 engageable with the hooked end 32 of the bottom hooked arm 28 of the first
 profile 12. This two-arm configuration of the zipper 10 provides a
 relatively leak proof seal. The second profile 14 may also have an
 inwardly directed wedge or bump 52 which is located between the top hooked
 arm 44 and the bottom hooked arm 46 and aids in guiding the profiles into
 and out of engagement. The profile flanges 24, 42 provide a means by which
 the zipper may be guided in an automated bag making process, such as on a
 form-fill-seal machine, and also provide a means by which the zipper may
 be sealed to the bag 13.
 The slide zipper assembly is further provided with a slider 54 which slides
 along the mouth 11 of the bag 13 as shown in FIG. 2. FIGS. 3 and 4 show
 how the zipper 10 cooperates with the slider 54. Thus, the slider 54 has a
 closing end 56 and an opening end 58. As shown in FIG. 2, the slider 54 is
 slidable in an opening direction "O" in which the zipper profiles 12, 14
 are disengaged by the slider, and a closing direction "C" in which the
 zipper profiles 12, 14 are engaged by the slider.
 FIG. 3 shows the details of the closing end of the slider and FIG. 4 shows
 the details of the opening end of the slider. It should be understood that
 for purposes of clarity the zipper 10 and slider 54 in FIGS. 3 and 4 are
 shown with the same orientation. However, when one actually looks at the
 zipper from the closing end and the opening end the orientations of the
 zipper and slider will be reversed.
 The slider 54 straddles the zipper 10 and is slidable along the zipper 10
 in the closing and opening directions. The profiles are closed and sealed
 to each other at both ends to ensure that the zipper 10 does not become
 separated at its ends during use. In addition, the zipper 10 may be
 provided with a stopper at both ends which serves to prevent the slider
 from becoming disengaged from the zipper.
 The slider 54 has a top portion 60, a first arm 62 and a second arm 64. The
 first arm 62 has an inner side 66, an outer side 68, and an inwardly
 directed bottom tab 70. Likewise, second arm 64 has an inner side 72, an
 outer side 74, and an inwardly directed bottom tab 76. The inner sides 66,
 72 of the slider arms are tapered towards the closing end 56 so that at
 the closing end the arms are sufficiently close to press the profiles into
 engagement with each other.
 The tab 70 of the first arm 62 has a tapered top surface 78, a side surface
 80, and a tapered bottom surface 81. The tapered top surface 78 of the tab
 70 mates with the bottom surface 22 of the first profile 12, imparting a
 generally upward force thereto. This force, as discussed below, plays a
 role in the opening and closing action of the slider 54.
 The tab 76 of the second arm 64 likewise has a tapered top surface 82, a
 side surface 84, and a tapered bottom surface 85. The tapered top surface
 82 mates with the bottom surface 40 of the second slider arm 64.
 The mating of the profile bottom surfaces 22, 40 and the slider tab tapered
 top surfaces 78, 82 ensures that the slider 54 is securely positioned over
 the zipper 10 and reduces the possibility that the slider 54 will be
 pulled off the zipper 10. The slider tab tapered bottom surfaces 81, 85
 facilitate insertion of the slider 54 over the zipper 10.
 As is clear from FIG. 3, the zipper 10 is captured between the inner sides
 66, 72 of the slider arms 62, 64 and between the two tabs 70, 76. The tabs
 70, 76 cooperate with the slider top 60 to hold the slider 54 in place.
 The inner sides 66, 72 of the slider arms 62, 64 are sufficiently close at
 the closing end so that when the slider 54 is moved in the closing
 direction "C", the inner sides 66, 72 of the slider arms 62, 64 press
 against the outer sides 18, 36 of the first and second profiles 12, 14,
 thereby effecting engagement of the profiles 12, 14.
 FIG. 4 shows the opening end 58 of the slider 54. At the opening end 58 the
 inner sides 66, 72 of the slider arms 62, 64 are sufficiently far apart so
 as to not impart a closing force to the profiles 12, 14. To this end, at
 the opening end 58 a separator blade 86 extends downwardly from the slider
 top as shown. In addition, the inner side 66 of first slider arm 62 is
 contoured to define a cavity 88 which extends upwardly into the top 60.
 The separator blade 86 is positioned so that when the slider 54 is moved
 in the opening direction, the separator blade 86 will deflect the top
 hooked arm 26 of the first profile 12 downwardly and out of engagement
 with the top hooked arm 30 of the second profile 14. A component of the
 force on the top hooked arm 26 of the first profile 12 will also direct
 the now disengaged profile 12 sideways and into cavity 88.
 As the slider 54 is moved in the opening direction "O", the separator blade
 86 deflects the top hooked arm 26 of the first profile 12 downwardly and
 out of engagement with the top hooked arm 30 of the second profile 14
 until the top hooked arm 26 engages bump 52. The bump 52 provides a
 camming surface for the top hooked arm 26 as a component of the force
 exerted by the separator blade acts on the top hooked arm 26 to urge the
 first profile 12 away from the second profile 14. Simultaneously, the top
 surface 78 of the tab 70 pushes the bottom portion 22 of the first profile
 12 upwardly. This upward deflection in combination with the outward
 deflection of the first profile 12 by the separator blade 86 disengages
 the bottom hooked arm 28 of the first profile 12 from the bottom hooked
 arm 46 of the second profile 14 and moves the first profile 12 up and into
 the cavity 88. Alternatively, means could be provided to force the second
 profile downwardly out of engagement with the first profile, as opposed to
 forcing the first profile upwardly or both upwardly and downwardly
 together.
 Thus, the combined action of the separator blade 86 and first slider arm
 tab 70 on the first profile 12 serves to open the zipper as the slider is
 moved in the opening direction. Movement of the slider in the closing
 direction causes the slider arms to force the profiles into engagement.
 Because of the attractiveness of slide zippers to consumers, it is
 commercially highly desirable to manufacture slider-zippered bags in a
 continuous automated process, such as on an FFS machine.
 FIG. 5 shows a bag being manufactured on an FFS machine 100 in accordance
 with a first embodiment of the present invention. Thermoplastic film 102
 is fed from a continuous supply thereof into the FFS machine 100 and
 wrapped around a forming collar 104 and around a filling tube 106 to bring
 the longitudinal edges 108, 110 of the film 102 together to form a tube.
 The interlocked zipper 10 having sliders 54 preapplied thereto is fed from
 a continuous coil thereof 112 between the longitudinal edges 108, 110 of
 the film 102 as shown, after which vertical seal bars 114 seal the zipper
 flanges 24, 42 to the longitudinal film edges 108, 110 to form what will
 be the top of the bag. The sliders 54 must be clear of the vertical seal
 bars 114 such that the sliders 54 do not interfere in the sealing of the
 zipper 10 and are not crushed by the vertical seal bars 114, as shown in
 FIG. 6. It is thus critical that the zipper flanges 24, 42 be long enough
 to eliminate any interference between the sliders 54 and the vertical seal
 bars 114.
 The zipper flanges 24, 42 also serve to allow the zipper 10 to be guided
 into the FFS machine 100 by zipper guide member 116, and thereby keep the
 zipper aligned with the edges of the film, as shown in FIG. 7, which shows
 a cross section of the zipper 10, the slider 54, the film 102, the
 vertical seal bars 114, and the zipper guide member 116.
 Then, further downstream in the FFS machine 100 cross seal bars 118 form
 the sides of the bags by transversely sealing the tube of film. The cross
 seal bars 118 simultaneously seal the first side 120 of the bag 122
 presently being made and seal the second side 124 of the preceding bag 126
 (the first side seal of the preceding bag had previously been made),
 capturing a single slider between the two sides of the preceding bag 126,
 and cut the 126 preceding bag from the film 102. After the first side 120
 is completed, the bag may be filled, if desired. Cross seal bars 118 may
 also seal the ends of the zipper 10 together to prevent the slider 54 from
 becoming detached therefrom. When the film 102 advances once again, the
 cross seal bars 118 complete the second side of the present bag, capturing
 a single slider between the two sides, and cut the present bag from the
 film and also complete the first side of the succeeding bag. In this
 manner slide-zippered bags are continuously made.
 A second embodiment of the present is shown in FIG. 8. In this embodiment,
 as in the first embodiment as well as all other embodiments, the FFS
 machine 100 functions in the same manner. The difference with this
 embodiment from the first embodiment, however, is that the zipper 10 does
 not have the sliders 54 preapplied thereto. Rather, the sliders 54 are
 applied to the zipper after the zipper is sealed to the longitudinal edges
 108, 110 of the film 102.
 As shown in FIG. 8, the sliders are supplied from a continuous coil 128 to
 a slider insertor mechanism 130. Each slider 54 is connected to its
 adjacent slider via a connector 132. This connection may be achieved in
 any number of ways. For example, the sliders may be mechanically
 connected. Alternatively, the sliders may be connected by a carrier
 adhesive tape. Still alternatively, the sliders may be connected by a
 metal or plastic wire or molded together by a plastic "runner".
 The connected sliders are fed into the slider insertor 130. As the film
 advances through the FFS machine and as bags are made, a slider 54 is
 removed from the connector 132 and applied to the zipper 10 of the bag 122
 presently being made. The use of tapered bottom surfaces 81, 85 on the
 slider 54 facilitate this application. After the slider 54 is applied to
 the zipper 10, the connector scrap 132 exits the slider insertor 130 and
 the first side seal of the bag is made by the cross seal jaws 118. The bag
 is then completed as discussed above.
 In a slight variation of this second embodiment, the slider insertor
 mechanism 130 can be positioned to apply the sliders 54 to the zipper 10
 between the zipper roll 112 and the FFS machine 100.
 A third embodiment of the present invention is shown in FIG. 9. In this
 embodiment once again the zipper 10 is sliderless as it is sealed to the
 longitudinal edges 108, 110 of the film 102. A box magazine 134 of
 individual stacked sliders 54 is connected to the slider insertion
 mechanism 130. As the film 102 advances through the machine and as the
 zipper 10 is attached to the film, the sliders are automatically applied
 to the zippers of the individual bags by the insertor 130. The magazine is
 interchangeable with other magazines and may be replaced by another
 magazine when it becomes empty. Other types of commonly used magazines may
 also be employed, such as a coil type magazine wherein the sliders are
 attached to each other.
 In a slight variation of this third embodiment, the slider insertor
 mechanism 130 can be positioned to apply the sliders 54 to the zipper 10
 between the zipper roll 112 and the FFS machine 100.
 In a fourth embodiment of the present invention, the zipper 10 is similarly
 sealed to the longitudinal edges 108, 110 of the film 102 without the
 sliders 54 being preapplied. Instead, a vibratory feeder bowl 136 is used
 to orient and deliver sliders 54 to the slider insertor 130. Bulk sliders
 54 are loaded by the bag maker into the vibratory feeder bowl 136. The
 vibratory feeder bowl 136 then orients the sliders 54 and feeds them to
 the slider insertor 130, which then applies the sliders to the zippers.
 The vibratory feeder bowl 136 may vibrate in either a translational manner
 (back and forth) or in a rotational manner. Generally, when the FFS
 machine is running at a slow speed, such as less than 60 bags per minute,
 a translational device may be used. When faster speeds are desired,
 however, the rotational type of feeder bowl should be used to adequately
 provide for high speeds.
 In a slight variation of this fourth embodiment, the slider insertor
 mechanism 130 can be positioned to apply the sliders 54 to the zipper 10
 between the zipper roll 112 and the FFS machine 100.
 Any of the foregoing embodiments may be used to make slide-zippered plastic
 bags on an FFS machine in a continuous, rapid manner. Modifications to the
 above would be obvious to those of ordinary skill in the art, but would
 not bring the invention so modified beyond the scope of the appended
 claims.