The present invention relates to methods and apparatuses for automated manufacture of a reclosable plastic package having a resealable closure, especially as part of a form, fill and seal process. In particular, the invention relates to methods and apparatuses for manufacturing reclosable plastic packages and bags having a zipper installed in the mouth of the package.
In the use of plastic bags and packages, particularly for foodstuffs, it is important that the bag be hermetically sealed until the purchaser acquires the product, takes it home, and opens the bag or package for the first time. It is then commercially attractive and useful for the consumer that the bag or package be reclosable so that its contents may be protected. Flexible plastic zippers have proven to be excellent for reclosable bags, because they may be manufactured with high-speed equipment and are reliable for repeated reuse.
A typical zipper comprises one fastener strip or member having a groove and attached to one side of the bag mouth, and another fastener strip or member having a rib and attached to the other side of the bag mouth, which rib may interlock into the groove when the sides of the mouth of the bag are pressed together. Alternatively, a fastener strip having a plurality of ribs may be on one side of the bag mouth, while a fastener strip having a plurality of grooves or passageways may be on the other side, the ribs locking into the passageways when the sides of the mouth of the bag are pressed together. In the latter case, there may be no difference in appearance between the two fastener strips, as the ribs may simply be the intervals between passageways on a strip that may lock into another of the same kind. In general, and in short, some form of male/female interengagement is used to join the two sides of the bag mouth together. The fastener strips or members are bonded in some manner to the material from which the bags themselves are manufactured.
In the automated manufacture of plastic reclosable packages or bags, it is known to feed a zipper assembly to a position adjacent a sheet of thermoplastic film and then attach the zipper assembly to the bag by means of heat sealing. The zipper assemblies are attached at spaced intervals along the thermoplastic sheet, one zipper assembly being attached to each section of film respectively corresponding to an individual package or bag. The zipper assembly consists of two interlocking fastener strips that, in the final package, lie inside the mouth of the package. Each fastener strip preferably has a flange that extends toward the product side of the package in a direction transverse to the line of the zipper. In accordance with one known method of feeding zipper assemblies to an automated form, fill and seal machine, the zipper assembly is in the form of a tape that is unwound from a spool for automated feeding. The tape comprises a continuous length of interlocked fastener strips. The continuous tape is fed to a cutting device that cuts the tape at regular lengths to form an individual zipper. Each individual zipper is attached to the thermoplastic film by heat sealing or other suitable means.
Prior to cutting and heat sealing, the zipper tape, with or without sliders, must be automatically positioned correctly relative to the thermoplastic film. Moving the zipper tape into position overlying the thermoplastic film requires an automated feeding device. In cases where the bag making film and the zipper tape are stopped during sealing of the zipper tape to the bag making film, the zipper tape feeding apparatus must operate intermittently.
There is a need for methods and apparatus for feeding a zipper tape, with or without sliders, to a desired position overlying the bag making film without slippage of the zipper tape.
The present invention is directed to a method and apparatus for automatically feeding zipper tape a station where it can be sealed to bag making film. In the embodiments disclosed herein, the zipper tape feeding apparatus comprises a pair of opposed circulating belts, one belt being driven intermittently by a motor and the other belt being free to circulate during frictional contact with the driven belt and a zipper tape that is sandwiched between the confronting portions of the belts. The belts are preferably made of a material, e.g., rubber, that minimizes slippage of the zipper tape during feeding. In an exemplary application of the invention, a zipper tape feeding apparatus may be placed between a slider insertion station and a zipper sealing station. The latter can be combined with a vertical form-fill-seal (FFS) machine, in which case the zippers are applied to the film in a direction transverse to the running direction of the bag making film.
One aspect of the invention is an apparatus comprising first and second multi-pulley assemblies, first and second belts respectively encasing the first and second multi-pulley assemblies and comprising mutually confronting portions, and a zipper tape comprising at least a portion trapped between the confronting portions of the first and second belts.
Another aspect of the invention is an apparatus for feeding a zipper tape comprising first and second circulating belts, the first belt being arranged to circulate along a first pathway comprising a first generally straight path segment, and the second belt being arranged to circulate along a second pathway comprising a second generally straight path segment, wherein the first and second generally straight path segments lie parallel and adjacent to each other, the first and second belts moving in the same direction along the first and second generally straight path segments during belt circulation. The zipper tape comprises first and second profiled closure members that are interlocked to each other, and first and second zipper flanges respectively connected to the first and second profiled closure members, the first and second zipper flanges confronting each other. The first and second belts cause a portion of the zipper tape trapped therebetween to move in the same direction as the belts move along the respective straight path segments during belt circulation.
A further aspect of the invention is an apparatus comprising first and second belts arranged with respective portions confronting each other, each of the first and second belts having a respective endless groove formed therein. The endless grooves are aligned with and confront each other along the confronting portions of the first and second belts, thereby forming a passageway.
Yet another aspect of the invention is an apparatus comprising: first and second belts arranged with respective portions confronting each other at an interface; and a zipper tape comprising first and second profiled closure members that are interlocked to each other, and first and second zipper flanges respectively connected to the first and second profiled closure members, the first and second zipper flanges confronting each other, respective portions of the first and second zipper flanges being disposed between and in contact with respective first portions of the confronting portions of the first and second belts, while the first and second profiled closure members lie outside of the confronting portions of the first and second belts.
Another aspect of the invention is a method of feeding zipper tape comprising the following steps: arranging first and second belts for circulation along first and second paths respectively, respective mutually opposing first portions of the first and second belts being in contact along a generally straight path segment; placing a portion of a zipper tape between and in contact with respective mutually opposing second portions of the first and second belts, the zipper tape portion being disposed parallel to the generally straight path segment; and driving the first belt to circulate in a predetermined direction with sufficient friction between the first belt and contacting portions of the zipper tape and the second belt that the second belt circulates in a direction opposite to the predetermined direction and the zipper tape is advanced.
Other aspects of the invention are disclosed and claimed below.
The present invention can be utilized in conjunction with many different methods of packaging product in a reclosable plastic package or bag. In particular, the invention has application in automated lines or machines which form a package, fill it with product, and then seal the product inside the package using a known form-fill-seal (FFS) methods. Although embodiments of the invention are disclosed below with reference to systems that apply zippers to bag making film in a direction transverse to the running direction of the film (i.e., the machine direction), the invention may be employed in other types of systems as well. For example, the zipper tape drive assembly could be used to feed zipper tape to a sealing station in the machine direction.
A typical zipper designed for use with a slider comprises a pair of zipper flanges that extending below the profiled closure members are sealed to the bag making film. A typical zipper designed for use without a slider comprises interlocking profiled closure members with dual flanges that respectively extend above and below the closure members. The upper flanges serve as pull flanges for opening the zipper by grasping, while the lower flanges are sealed to the bag making film.
In a typical form-fill-seal operation, a continuous supply of thin packaging or bag making film is paid off of a supply reel by a suitable mechanism. For example, the FFS machine may be provided with feed drive rollers for pulling the film through the FFS machine. For each length of bag making film corresponding to an individual package, a zipper assembly is attached to the film. The zipper may be laid directly on the film, but preferably is fed laterally across the upper surface of the film at right angles to the longitudinal edges of the film or, in other words, at right angles to the longitudinal formation axis of the film. The zippers are cut off from the end of a zipper tape that is paid out from a zipper tape supply reel and guided to a sealing and cutting station, where an individual zipper is cut and sealed to the bag making film. The length of each zipper segment will be less than one-half of the film width. Typically, a flange on one side of the zipper is sealed to the film at a sealing station in advance of the FFS machine. The lateral portions of the film beyond the ends of the attached zipper are sufficiently long so that they can eventually be folded over and sealed to the other zipper flange at the end of the FFS machine.
Reference will now be made to the drawings in which similar elements in different drawings bear the same reference numerals.
Prior to opening of the package by the consumer, the slider-zipper assembly may be covered on the consumer side by an enclosed header 16 that is hermetically sealed. The sealed header 16, which provides a tamper-evident feature, comprises front and rear panels that may be integrally formed with or heat sealed to the front and rear walls, respectively, of the receptacle. The numeral 32 in
It should be appreciated that the front wall of the header 32 and the front wall 12 of the receptacle are shown in
In accordance with one embodiment of the invention, the slider-zipper assembly arrives at the position shown in
Although each assembly in the disclosed embodiment has three pulleys in each row, each row may more generally comprise two or more pulleys and is not limited to three. Preferably, each pulley has the same radius and is mounted to a respective rotatable shaft 48. However, the radii of the pulleys in a given multi-pulley assembly may be different, provided that the confronting portions of the belts, which are tangent to each contacting pulley, are disposed in respective planes. In the disclosed embodiment, the axes of rotation of all the pulleys are mutually parallel, with the axes of rotation of pulleys 36, 38 and 40 being coplanar in a first plane, while the axes of rotation of pulleys 42, 44 and 46 are coplanar in a second plane parallel to the first plane. However, the invention does not preclude one or more additional pulleys in each multi-pulley assembly, which added pulleys support the circulating belts on the return side and are not arranged in the above-described row of pulleys that support the confronting portions of the belts. In this alternative, the pathway followed by each circulating belt would be different than the racetrack shape seen in FIG. 3.
The line 22 in
Still referring to
The first multi-pulley assembly can be driven by a motor (not shown) having an output shaft coupled to the shaft 48 of one of the pulleys 36, 38 or 40. In the case where zipper segments are being fed to a zipper sealing station in a direction transverse to the running direction of the film, a stationary zipper segment will be sealed to a stationary bag making film during the sealing portion of the work cycle, with the tape and film being intermittently advanced during the intervals between sealing operations. Thus, the belt 50 in the disclosed embodiment is driven intermittently rather than continuously. Consequently, the motor is preferably a servomotor or a stepper motor. Each time a new zipper segment is needed at the zipper sealing station, the motor is activated and then controlled to feed the zipper tape forward to the sealing station by a predetermined distance equal to the width of the zipper on a package. Then the motor is turned off. The second multi-pulley assembly is not driven by the motor, but rather is free to circulate in response to a force of friction exerted on the portions of the outer surface of belt 52 that confront the driven belt 50. In the disclosed embodiment, the belt 50 is arranged to circulate along a first pathway comprising a first generally straight path segment, while the belt 52 is arranged to circulate along a second pathway comprising a second generally straight path segment, the belts confronting along these generally straight path segments. These adjacent straight path segments lie parallel and adjacent to each other. The belts 50 and 52 thus move in the same direction along these generally straight path segments during belt circulation, with the zipper tape being carried along with the moving belts.
The dimension of the belts 50 and 52 can be selected to accommodate the type of zipper being used. Also the belts may be provided with relief to accommodate the zipper profiles in cases where the entire zipper tape is sandwiched between the opposing belts. However, in the case of a zipper tape having sliders clipped thereon at spaced intervals along the length of the tape, the entire zipper tape cannot be sandwiched between the belts due to the lack of clearance for the sliders between the contacting belts. In the latter case, the zipper tape with sliders must be set up to have the profiled closure members of the zipper tape and the sliders disposed beyond the edge of the opposing belts.
As previously mentioned, in cases where the zipper tape being fed has no sliders, the entire zipper tape can be sandwiched between the opposing belts, with the opposing belts being in direct contact to the left and to the right (above and below if the zipper tape were disposed vertically) of the zipper tape.
In accordance with the embodiment depicted in
In the exemplary application of feeding tape to a sealing station, at the same time that the belt drive assembly is pushing the zipper tape toward the sealing station, a tape transfer assembly at the sealing station can be exerting a pulling force on the incoming terminal end of the zipper tape. An exemplary tape transfer assembly is shown in
In the front view presented in
As seen in
Still referring to
The rotation of shaft 86 also drives the rotation of the other drive roller assemblies 78 and 80 of the tape transfer assembly. As seen in
The peripheral surface of each drive roller is made of silicone to prevent slippage of the plastic zipper tape during transfer of the zipper tape in a direction transverse to the running direction of the bag making film. The non-slipping contact of the periphery and groove of the drive rollers with the zipper tape during roller rotation in a clockwise direction (as seen in
After each slider-zipper assembly has been attached to the bag making film along a line transverse to the running direction of the film, the film with slider-zipper assembly must be advanced by one package length. With reference to the drawings, the bag making film will be advanced in a direction directed out of the page in FIG. 6 and from left to right in FIG. 7. However, as seen in
Although
Means other than a gearbelt can be used to couple the belt drive assembly to the tape transfer assembly. For example, the tape drive and tape transfer assemblies could be driven by separate motors, operation of the motors being synchronized by a programmable controller.
While the invention has been described with reference to preferred embodiments, it will be understood by those skilled in the art that various changes may be made and equivalents may be substituted for members thereof without departing from the scope of the invention. In addition, many modifications may be made to adapt a particular situation to the teachings of the invention without departing from the essential scope thereof. For example, it should be obvious that the slider guide may be formed as a monolithic piece or may be an assembly having two or more parts. Therefore it is intended that the invention not be limited to the particular embodiment disclosed as the best mode contemplated for carrying out this invention, but that the invention will include all embodiments falling within the scope of the appended claims.
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Number | Date | Country | |
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20040063558 A1 | Apr 2004 | US |