Abstract:
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.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     This application is a continuation-in-part (CIP) of Ser. No. 09/093,111, filed Jun. 8, 1998 now U.S. Pat. No. 5,953,796, the disclosure of which is incorporated herein by reference. 
    
    
     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. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     In the accompanying drawings: 
     FIG. 1 is a cross sectional view of an interlockable zipper in accordance with the present invention; 
     FIG. 2 is a perspective view of a slide zipper in accordance with the present invention attached to a plastic bag; 
     FIG. 3 is a cross sectional view of the closing end of the slider and zipper; 
     FIG. 4 is a cross sectional view of the opening end of the slider and zipper; 
     FIG. 5 shows an FFS machine adapted to make slide zippered bags according to a first embodiment of the present invention; 
     FIG. 6 shows a side view of the vertical seal bars of the FFS machine of FIG. 5 disposed to seal the zipper to the thermoplastic film; 
     FIG. 7 shows a cross sectional view of the zipper guide and the vertical seal bars of the FFS machine of FIG. 5; 
     FIG. 8 shows an FFS machine adapted to make slide zippered bags according to a second embodiment of the present invention; 
     FIG. 9 shows an FFS machine adapted to make slide zippered bags according to a third embodiment of the present invention; and 
     FIG. 10 shows an FFS machine adapted to make slide zippered bags according to a fourth embodiment of the present invention. 
    
    
     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.