Methods of manufacturing slider-operated string-zippered bags on VFFS machine
A method of manufacture comprising the following steps: (a) guiding a web material in a machine direction through a vertical form-fill-seal (VFFS) machine with a portion or portions of the web material being wrapped around a tube; (b) joining first and second flangeless zipper strips to first and second portions of the web material that do not form part of the portion or portions of the web material that are wrapped around the tube; (c) inserting a slider on the first and second flangeless zipper strips joined to the web material; (d) cross sealing the web material at a location downstream from the tube; and (e) dropping product through the tube and onto the most recently formed cross seal.
The present invention relates to reclosable bags having slider-operated string zippers. More particularly, the present invention relates to a method and apparatus for making slider-operated string-zippered reclosable bags on vertical form-fill-seal (VFFS) machines.
Methods and apparatus for manufacturing reclosable bags on VFFS machines using reclosable zippers are well known in the art. These prior art methods and apparatus are not limited to interlocking zippers which are directly opened and closed by the hands of the bag user, but also include methods and apparatus for making reclosable bags that employ a slider for opening and closing the zipper.
Reclosable bags having slider-operated zippers are generally more desirable to consumers than bags that have sliderless interlocking zippers since it is much easier for the user to open and close bags having a slider-operated zipper. One class of slider bags employ a flanged zipper, while another class of slider bags employ a flangeless or so-called “string” zipper. As used herein, the term “string zipper” means a zipper comprising two zipper strips having substantially no flanges. Therefore, instead of attaching the zipper strips to a bag by means of extension flanges that are heat sealed to the bag walls, a string zipper is attached to the bag walls at the backs of the zipper strips, in regions directly opposite to the interlocking profiled closure members.
In general, bags that have a string zipper can be manufactured more cheaply than bags that have a flanged zipper. This is due in part to the following factors: a string zipper uses less material than a zipper with flanges and can be produced faster and in greater multiples, and string zippers are easier to handle and store. It is thus commercially highly desirable and advantageous to provide methods and apparatus for manufacturing slider-operated string-zippered bags in a continuous, automated process. In particular, it is desirable to provide methods and apparatus for making slider-operated string-zippered bags on a VFFS machine.
BRIEF DESCRIPTION OF THE INVENTIONThe present invention is directed to methods for manufacturing slider-operated string-zippered bags on a VFFS machine.
One aspect of the invention is a method of manufacture comprising the following steps: (a) guiding a web material in a machine direction through a vertical form-fill-seal (VFFS) machine with a portion or portions of the web material being wrapped around a tube; (b) joining first and second flangeless zipper strips to first and second portions of the web material that do not form part of the portion or portions of the web material that are wrapped around the tube; (c) inserting a slider on the first and second flangeless zipper strips joined to the web material; (d) cross sealing the web material at a location downstream from the tube; and (e) dropping product through the tube and onto the most recently formed cross seal.
Another aspect of the invention is a method of automatically manufacturing bags fitted with a slider-operated string zipper, comprising the following steps: (a) intermittently advancing a web along a pathway that partly encircles a tube, whereby after each advancement, first and second portions of the web are wrapped around respective portions of a tube having an axis, while third and fourth portions of the web extend generally radially outward from the tube; (b) during each dwell time, joining respective sections of first and second flangeless zipper strips to the third and fourth portions of the web while the first and second portions of the web are wrapped around the respective portions of the tube, thereby forming a zipper-web assembly; (c) during each dwell time, inserting a slider on the first and second flangeless zipper strips respectively joined to the third and fourth web portions; (d) during each dwell time and after step (b) has been performed, cross sealing the web in a first transverse region at an elevation below an outlet end of the tube; (e) during each dwell time and after step (d) has been performed, dropping product down the tube and onto the most recently cross-sealed portion of the web; and (f) during each dwell time, cutting the zipper and the web along a transverse line that intersects a respective cross-sealed region, thereby severing a finished bag from the zipper-web assembly.
A further aspect of the invention is a method of manufacture comprising the following steps: (a) guiding a length of web material, having mutually parallel first and second lateral edges when the web material is flat, such that a major portion of the length of web material is wrapped around a tube having an axis, and first and second portions adjacent or near the first and second lateral edges respectively of the length of web material extend in mutually confronting relationship outside the tube, separated by a gap; (b) guiding a length of string zipper comprising interlocked first and second flangeless zipper strips to a position outside the tube and parallel to the tube axis, the length of string zipper being disposed in the gap between the first and second portions of the length of web material; (c) joining the length of string zipper to the length of web material while the major portion of the length of web material is wrapped around the tube, thereby forming a zipper/web assembly, the first flangeless zipper strip being joined to the first portion and the second flangeless zipper strip being joined to the second portion; and (d) inserting a slider onto the zipper/web assembly while the major portion of the length of web material is wrapped around the tube.
Yet another aspect of the invention is a method of manufacture comprising the following steps: (a) guiding a length of web material, having mutually parallel first and second lateral edges when the web material is flat, such that: (i) first and second portions of the length of web material are wrapped around respective portions of a tube, (ii) first and second marginal portions adjacent the first and second lateral edges respectively of the length of web material project generally outward and away from the tube in mutually confronting relationship, and (iii) the first and second portions are connected by a loop having mutually opposing first and second walls separated by a gap; (b) guiding a length of string zipper comprising interlocked first and second flangeless zipper strips to a position outside the tube and parallel to the tube axis, the length of string zipper being disposed in the gap between the first and second walls of the loop; (c) joining the length of string zipper to the length of web material while the first and second portions of the length of web material are wrapped around respective portions of the tube, thereby forming a zipper/web assembly, the first flangeless zipper strip being joined to the first portion and the second flangeless zipper strip being joined to the second portion; (d) cutting off a portion of the loop beyond the string zipper; and (e) after step (d), inserting a slider onto the zipper/web assembly while the first and second portions of the length of web material are wrapped around respective portions of the tube.
A further aspect of the invention is a method of manufacture comprising the following steps: (a) guiding a length of web material, having mutually parallel first and second lateral edges when the web material is flat, such that: (i) first and second portions of the length of web material are wrapped around respective portions of a tube, (ii) first and second marginal portions adjacent the first and second lateral edges respectively of the length of web material project generally outward and away from the tube in mutually confronting relationship, and (iii) the first and second portions are connected by a folded portion having an M-shaped profile with mutually opposing first and second interior walls separated by a gap; (b) guiding a length of string zipper comprising interlocked first and second flangeless zipper strips to a position outside the tube and parallel to the tube axis, the length of string zipper being disposed in the gap between the first and second interior walls of the folded portion; (c) joining the length of string zipper to the length of web material while the first and second portions of the length of web material are wrapped around respective portions of the tube, thereby forming a zipper/web assembly, the first flangeless zipper strip being joined to the first portion and the second flangeless zipper strip being joined to the second portion; and (d) inserting a slider onto the zipper/web assembly while the first and second portions of the length of web material are wrapped around respective portions of the tube.
Another aspect of the invention is a method of manufacture comprising the following steps: (a) guiding a web material in a machine direction through a vertical form-fill-seal (VFFS) machine; (b) joining a string zipper to the web material upstream of the VFFS machine; (c) inserting a slider over said string zipper and portions of said joined web material at a location adjacent a tube of said VFFS machine; (d) cross sealing the web material at an elevation below the tube; and (e) dropping product through the tube and onto the most recently formed cross seal.
A further aspect of the invention is a method of manufacture comprising the following steps: (a) guiding a web material in a machine direction through a vertical form-fill-seal (VFFS) machine with portions of the web material being wrapped around respective portions of a tube of the VFFS machine; (b) joining the web material to two sides of a string zipper to form a web/string zipper assembly, the joining step being performed at locations upstream of the VFFS machine; (c) removing at least a portion of the web material suspended between the zones of web/zipper joinder at a location upstream of the VFFS machine, but downstream of the locations where step (b) is performed; (d) inserting a slider on the string zipper at a location upstream of the VFFS machine, but downstream from the locations where step (b) is performed; (e) cross sealing the web material at a location downstream from the tube; and (f) dropping product through the tube and onto the most recently formed cross seal.
Other aspects of the invention are disclosed and claimed below.
BRIEF DESCRIPTION OF THE DRAWINGS
Reference will now be made to the drawings in which similar elements in different drawings bear the same reference numerals.
DETAILED DESCRIPTION OF THE INVENTION A reclosable package comprising a bag or receptacle 2 and a flexible plastic zipper 4 operated by manipulation of a slider 10 is shown in
The bag 2 may be made from any suitable bag making film material, including a single layer of thermoplastic material or a laminate comprising two or more layers made of different materials. For example, the laminate could comprise two layers of different thermoplastic materials, a plastic-coated paper or a metallized thermoplastic film. Suitable thermoplastic materials include low-density polyethylene, substantially linear copolymers of ethylene and a C3-C8 alpha-olefin, polypropylene, polyvinylidene chloride, mixtures of two or more of these polymers, or mixtures of one of these polymers with another thermoplastic polymer. The person skilled in the art will recognize that this list of suitable thermoplastic materials is not exhaustive. The thickness of the bag making film is preferably 2 mils or less.
From a structural standpoint, the bag 2 comprises opposing walls (only the front panel 2a is visible in
At its top end, the bag 2 has an openable mouth, on the inside of which is an extruded plastic zipper 4. The zipper 4 comprises a pair of interlockable zipper parts. One zipper part 6 is visible in
The zipper is operated by sliding the slider 10 along the zipper parts. As the slider moves across the zipper, the zipper is opened or closed. As shown in
The bag shown in
A reclosable package or bag comprising a receptacle 2 and a flexible plastic string zipper 4, operated by manipulation of a slider 10, is partially shown in
Zipper strip 8 comprises a base and two generally arrow-shaped rib-like male closure elements or members projecting from the base. Zipper strip 6 comprises two pairs of hook-shaped gripper jaws connected by a sealing bridge. The pairs of gripper jaws form respective complementary female profiles for receiving the male profiles of zipper strip 8. Alternatively, one zipper part could have one male profile and one female profile, while the other zipper part has one female profile and one male profile, or the respective zipper parts could each have more than two male or female profiles. The sealing bridge of zipper strip 6 and the base of zipper strip 8 are resiliently flexible self-supporting structures having a thickness greater than the thickness of the bag film. The male closure elements are integrally formed with the base, while the female closure elements are integrally formed with the sealing bridge.
The upper margins of the walls 2a and 2b of the bag are joined to the backs of the sealing bridge and the base respectively. The upper margins of the bag film may have short free ends, as seen in
The slider 10 comprises a top wall 22 and a pair of side walls 24, 26 that form a tunnel for passage of the string zipper therethrough. The width of the tunnel is substantially constant along the section that is divided by the plow 28 and then narrows from a point proximal to the end of the plow to the closing window at one end face of the slider. The closing end of the slider is seen in
The plow or divider 28 depends downward from a central portion of the top wall 22 to an elevation below the lowermost portions of each sidewall 24, 26. The plow 28 is disposed between opposing sections of the zipper strips that pass through the tunnel. The tip of the plow 28 is truncated and has rounded edges and flattened corners at opposing ends for facilitating insertion of the plow between the zipper profiles without snagging during automated slider insertion. As the slider is moved in the opening direction (i.e., with the closing end leading), the plow 28 pries the impinging sections of zipper strips 6 and 8 apart.
In the embodiment depicted in
The slider may be made in multiple parts and welded together or the parts may be constructed to be snapped together. The slider may also be of one-piece construction. The slider can be made using any desired method, such as injection molding. The slider can be molded from any suitable plastic, such as nylon, polypropylene, polystyrene, acetal, polyketone, polybutylene terephthalate, high-density polyethylene, polycarbonate, or ABS.
The present invention is directed to methods for manufacturing slider-actuated string-zippered bags utilizing VFFS machines.
While the art of manufacturing slider-operated reclosable bags having flanged zippers on a VFFS machine is well known, the invention proposes to make slider-operated reclosable bags whose zippers have no flanges. There are several advantages in using string zipper in a VFFS machine that not only relate to the substantially lower cost of the zipper due to the elimination of the flanges, higher speed of extrusion, and extrusion of a greater number of zippers at the same time out of the same die, but also to the process itself. By eliminating the flanges, a substantially larger footage of zipper can be wound on a spool, which in turn results in less lost machine time due to spool change-over. The string zipper is easier to wind on a spool, easier to handle coming off of the spool and easier to guide into the machine because it is no longer necessary to provide for the flanges. However, to take advantage of these improvements, several changes have to be made in the attachment of the film to the string zipper and in the mounting of the slider. These include the guiding and the sealing of the film to the back or base of the string zipper strips and the mounting of the slider over the attached film and zipper elements.
To better appreciate the invention, several known techniques for manufacturing reclosable bags having slider-actuated flanged zippers will be briefly described. Then the changes to the equipment needed to make reclosable bags having slider-actuated string zippers will be further described in detail.
Still referring to
Then, further downstream in the VFFS 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 cross seal the leading side 120 of the bag 122 presently being made from the film 102 and the lagging side 124 of the preceding bag 126 (the leading side seal of the preceding bag had been made during the previous cross sealing operation), capturing a single slider between the two side seals of the preceding bag 126, and cutting the preceding bag 126 from the film 102. After the first side 120 is cross sealed, the bag may be filled, if desired, through a funnel at the top of the tube 106. Cross seal bars 118 may also seal the ends of the zipper 5 together to prevent the slider 11 from becoming detached therefrom. When the film 102 advances once again, the cross seal bars 118 complete the second cross-sealed side of the present bag, capturing a single slider between the two sides, and then cut the present bag from the film and also complete the first cross-sealed side of the succeeding bag. In this manner slider-operated zippered bags are continuously made.
Another conventional VFFS machine 100′ for making slider-operated reclosable bags with flanged zippers is shown in
As shown in
Alternatively, it is known to connect a box magazine (not shown in the drawings) of individual stacked sliders to the slider insertion mechanism. As the film advances through the machine and as the zipper is attached to the film, the sliders are automatically applied to the zippers of the individual bags by the slider inserter. 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 accordance with a further known alternative, a vibratory feeder bowl (not shown in the drawings) can be used to orient and deliver sliders to the slider inserter. Bulk sliders are loaded by the bag maker into the vibratory feeder bowl. The vibratory feeder bowl then orients the sliders and feeds them to the slider inserter, which then applies the sliders to the zippers. The vibratory feeder bowl may vibrate in either a translational manner (back and forth) or in a rotational manner. Generally, when the VFFS 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.
The operation of a conventional VFFS machine has been generally described with reference to
In each of the six methods disclosed hereinafter, the film web is advanced intermittently through the VFFS machine, with all operations that are performed alongside or below the fill tube being performed during dwell times. All of the six methods have in common the steps of: wrapping portions of a film web around respective portions of the fill tube; joining a pair of flangeless zipper strips to the film web; inserting a slider onto the string zipper; cross sealing the film web at spaced intervals therealong; filling the bag precursor through the fill tube; and then severing the filled bag from the remainder of the zipper/web assembly in process. The methods vary, however, as to the locations where the zipper strips are joined to the web and the locations where the sliders are inserted (although, as will be seen, the sliders are inserted at a station alongside the fill tube in five of six disclosed methods).
In accordance with the first two methods of manufacture disclosed herein, the string zipper is applied and sealed to the bag making film upstream or in front of the forming collar and the fill tube. In accordance with a first method partly depicted in
Now referring to
In accordance with a second method partly depicted in
Now referring to
In accordance with a fourth method of manufacture shown in
The central fold in the M-shaped gusted end forms a tamper-evident membrane in the interior of the bag on the product side of the string zipper. The ends of the membrane are sealed at the side seals. To gain access to the contents of the bag, the user must first open the zipper by moving the slider and then tear open or breach the membrane disposed inside the bag. To facilitating breaching, the membrane may be provides with a line of weakened tear resistance, which may, for example, comprise a line of spaced perforations or a scoreline running the length of the membrane. The perforations may be capped, as taught in U.S. Pat. No. 5,063,639. The merged marginal portions of the membrane and the receptacle walls may be respectively sealed to the backs of the zipper strips. Then any excess film at the outer folds of the gusseted end (i.e., film extending beyond the edges of the zipper strips) is trimmed. Thereafter, a slider is mounted to the string zipper.
In accordance with a fifth method of manufacture shown in
After sealing the string zipper to the film web and then trimming the excess film portions extending beyond the edges of the string zipper, optionally any remnant portions may be respectively sealed to the respective zipper strips by a specially designed heated sealing bar that is fully disclosed in U.S. patent application Ser. No. 10/655,991 entitled “Method and Apparatus for Making Reclosable Bags Having Slider-Actuated String Zippers”. In that patent application, the operation whereby the free remnants are sealed to the zipper is referred to as “lip sealing”. Alternatively, if the cutting lines are located close enough to the respective zipper strips that the remnants of film projecting beyond the zipper are not long enough to interfere with operation of the slider as it moves along the zipper, lip sealing need not be done.
In accordance with a sixth method of manufacture generally depicted in the block diagram of
As seen in
For each of the methods of manufacture disclosed herein, a slider with or without a separating finger can be used. One method for inserting a slider with separating finger or plow onto a string zipper joined to a web was fully disclosed in U.S. patent application Ser. No. 10/622,996, substantial portions of which are set forth below in a manner that conforms to the scheme of the present disclosure, namely, with reference to
Referring to
In accordance with the disclosed embodiment of the invention shown in
As the zipper-film assembly is pulled in the machine direction through the bag making machine (by conventional means not shown), the grooves and the upper and lower guides 84, 86 (best seen in
Referring again to
Referring to
The upper clamp 142 is moved between retracted and extended positions by an air cylinder 168 mounted on a cylinder mounting block 160. The upper clamp 142 is mounted to the end of a piston rod 166. The cylinder mounting block 160 has a guide channel 158 for guiding the upper clamp 142 during its transit. Similarly, the lower clamp 144 is moved between retracted and extended positions by an air cylinder 172 mounted on a cylinder mounting block 164. The lower clamp 144 is mounted to the end of a piston rod 170. The cylinder mounting block 164 has a guide channel 162 for guiding the lower clamp 144 during its transit. The cylinder mounting blocks 160 and 164 are fixed to a support frame not shown. The same support frame supports the tunnel 88 and the slider track 90 and the cylinder 92 depicted in
As best seen in
The interior surfaces of the arms of the U-shaped clamps can be mutually parallel and separated by a distance slightly greater than the width of the pusher. This enables the interior surfaces of the clamp arms to act as extensions of the sidewalls of the pusher channel. This will provide further confinement and alignment of the slider in the pusher as the pusher extends during slider insertion.
During the same dwell time that a slider is being inserted, a slider end stop structure is being formed on the zipper at an ultrasonic stomping station (not shown) downstream from the slider insertion zone. This slider end stop structure will be bisected later during cutting by a hot knife (not shown) to form two slider end stops, i.e., the end stop at the zipper fully closed slider park position for one package and the end stop at the zipper fully open slider park position for the next package. The end stop structure is typically formed by an ultrasonic stomping assembly comprising a horn and an anvil (not shown in the drawings). The horn transmits sufficient ultrasound wave energy into the plastic zipper material that the material is fused into a structure (e.g., a vertically extending hump) defined by the surfaces of the horn and anvil. The horn and anvil may be of the reciprocating or rotary variety.
The separator assembly 80 comprises a central splitter plate 82 having a pair of grooves or channels formed on either side thereof that guide the respective zipper strips as the neck (the hatched strip in
As previously mentioned, the extension and retraction of the pusher 98, the upper clamp 142 and the lower clamp 144 are achieved in the disclosed embodiment by means of respective air cylinders 92, 168 and 172, generally represented in
A person skilled in the art of machinery design will readily appreciate that displacing means other than cylinders can be used to displace the clamps and the pusher. Any other known mechanical displacement means can be used. For the sake of illustration, such mechanical displacement devices include a rack and pinion arrangement, rotation of the pinion being driven by an electric motor, or a linear actuator with ball screw driven by an electric motor.
While the disclosed embodiments make reclosable bags using thermoplastic film, the continuous web of bag making material fed to the VFFS machine can be implemented in a wide variety of ways. It can be constituted merely by a single film of thermoplastic material, or by a composite film of thermoplastic material, i.e. a film built up by juxtaposing layers of different kinds.
While the invention has been described with reference to certain 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. 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.
As used in the claims, the verb “joined” means fused, bonded, sealed, adhered, etc., whether by application of heat and/or pressure, application of ultrasonic energy, application of a layer of adhesive material or bonding agent, interposition of an adhesive or bonding strip, etc. As used in the claims, the term “string zipper” means a zipper comprising two interlockable strips that have substantially no flange or fin portions. As used in the claims, the terms “upstream” and “downstream” refer to the relationship of various positions along a process pathway traveled by an advancing web of flexible material. As a portion of the web advances, it moves “downstream”, whereas work stations already passed by that portion of the web are said to lie “upstream” of the present location of the web portion. Stations that perform work on the web material before it reaches the tube of a VFFS machine are said to be “upstream of the tube”. Further, in the absence of explicit language in any method claim setting forth the order in which certain steps should be performed, the method claims should not be construed to require that steps be performed in the order in which they are recited.
Claims
1. A method of manufacture comprising the following steps:
- (a) guiding a web material in a machine direction through a vertical form-fill-seal (VFFS) machine with a portion or portions of said web material being wrapped around a tube;
- (b) joining first and second flangeless zipper strips to first and second portions of said web material that do not form part of said portion or portions of said web material that are wrapped around a fill tube of said VFFS machine;
- (c) inserting a slider on said first and second flangeless zipper strips joined to said web material;
- (d) cross sealing said web material at a location downstream from said fill tube; and
- (e) dropping product through said fill tube and onto the most recently formed cross seal.
2. The method as recited in claim 1, wherein steps (b) and (c) are performed at stations upstream of said tube, further comprising the step of guiding said slider in a channel in a forming collar of said VFFS machine as said web material advances.
3. The method as recited in claim 1, wherein steps (b) and (c) are performed at stations adjacent said tube.
4. The method as recited in claim 1, wherein step (b) is performed at stations upstream of said tube and step (c) is performed at a station adjacent said tube.
5. The method as recited in claim 1, wherein said first flangeless zipper strip is joined to said web material at a station upstream of said tube and said second flangeless zipper strip is joined to said web material at a station adjacent said tube.
6. The method as recited in claim 3, further comprising the steps of:
- guiding a portion of said web material to form a loop, said looped portion comprising said first and second portions to which said first and second flangeless zipper strips are respectively joined;
- aligning said first and second flangeless zipper strips with each other; and
- guiding said first and second flangeless zipper strips to positions whereat said aligned first and second flangeless zipper strips are disposed between said first and second portions of said web material.
7. The method as recited in claim 6, further comprising the steps of:
- guiding first and second marginal portions of said web material into mutually confronting relationship; and
- joining said first and second marginal portions to each other.
8. The method as recited in claim 6, further comprising the steps of cutting off a third portion of said web material that lies between said first and second portions of said web material and forms part of said loop.
9. The method as recited in claim 3, further comprising the steps of:
- guiding a portion of said web material to form a gusset, said gusseted portion comprising said first and second portions to which said first and second flangeless zipper strips are respectively joined;
- aligning said first and second flangeless zipper strips with each other; and
- guiding said first and second flangeless zipper strips to positions whereat said aligned first and second flangeless zipper strips are disposed between said first and second portions of said web material.
10. The method as recited in claim 9, further comprising the steps of:
- guiding first and second marginal portions of said web material into mutually confronting relationship; and
- joining said first and second marginal portions to each other.
11. The method as recited in claim 9, further comprising the steps of cutting off first and second folded portions of said web material disposed at a mouth of said gusset on opposite sides of said first and second flangeless zipper strips.
12. The method as recited in claim 1, wherein said first and second portions of said web material are at or near respective lateral edges of said web material.
13. A method of automatically manufacturing bags fitted with a slider-operated string zipper, comprising the following steps:
- (a) intermittently advancing a web along a pathway that partly encircles a tube, whereby after each advancement, first and second portions of said web are wrapped around respective portions of a tube having an axis, while third and fourth portions of said web extend generally radially outward from said tube;
- (b) during each dwell time, joining respective sections of first and second flangeless zipper strips to said third and fourth portions of said web while said first and second portions of said web are wrapped around said respective portions of said tube, thereby forming a zipper-web assembly;
- (c) during each dwell time, inserting a slider on said first and second flangeless zipper strips respectively joined to said third and fourth web portions;
- (d) during each dwell time and after step (b) has been performed, cross sealing said web in a first transverse region at an elevation below an outlet end of said tube;
- (e) during each dwell time, dropping product down said tube and onto the most recently cross-sealed portion of said web; and
- (f) during each dwell time, cutting said zipper and said web along a transverse line that intersects a respective cross-sealed region, thereby severing a finished bag from the zipper-web assembly.
14. The method as recited in claim 13, wherein said web has first and second lateral edges that are parallel to each other when said web is flat, said third portion of said web being adjacent or near said first lateral edge, and said fourth portion being adjacent or near said second lateral edge.
15. The method as recited in claim 14, further comprising the step, performed during each dwell time, of trimming at least some of the excess web material that extends from said third portion of said web to said first lateral edge and at least some of the excess web material that extends from said fourth portion of said web to said second lateral edge.
16. The method as recited in claim 13, further comprising the following steps, performed before said respective sections of said first and second flangeless zipper strips are joined to said third and fourth portions of said web respectively:
- interlocking said respective sections of said first and second flangeless zipper strips together;
- guiding said interlocked respective sections of said first and second flangeless zipper strips to a position outside said tube and parallel to said tube axis; and
- forming a gusset in said web, said third and fourth portions of said web forming respective mutually confronting portions of said gusset and being disposed on opposite sides of said interlocked respective sections of said first and second flangeless zipper strips during joining of said respective sections of said first and second flangeless zipper strips to said third and fourth portions of said web respectively.
17. The method as recited in claim 16, further comprising the step, performed during each dwell time, of trimming at least some of the excess web material that extends beyond said interlocked respective sections of said first and second flangeless zipper strips in a direction away from said tube.
18. The method as recited in claim 16, wherein said web has first and second lateral edges that are parallel to each other when said web is flat, further comprising the following steps:
- guiding first and second marginal portions of said web into mutually confronting positions, said first marginal portion being bounded on one side by said first lateral edge and said second marginal portion being bounded on one side by said second lateral edge; and
- joining said first and second marginal portions of said web together.
19. The method as recited in claim 13, further comprising the following steps, performed before said respective sections of said first and second flangeless zipper strips are joined to said third and fourth portions of said web respectively:
- interlocking said respective sections of said first and second flangeless zipper strips together;
- guiding said interlocked respective sections of said first and second flangeless zipper strips to a position outside said tube and parallel to said tube axis; and
- forming a loop in said web, said third and fourth portions of said web forming respective mutually confronting portions of said loop and being disposed on opposite sides of said interlocked respective sections of said first and second flangeless zipper strips during joining of said respective sections of said first and second flangeless zipper strips to said third and fourth portions of said web respectively.
20. The method as recited in claim 19, further comprising the step, performed during each dwell time, of trimming at least a portion of said loop.
21. The method as recited in claim 19, wherein said web has first and second lateral edges that are parallel to each other when said web is flat, further comprising the following steps:
- guiding first and second marginal portions of said web into mutually confronting positions, said first marginal portion being bounded on one side by said first lateral edge and said second marginal portion being bounded on one side by said second lateral edge; and
- joining said first and second marginal portions of said web together.
22. A method of manufacture comprising the following steps:
- (a) guiding a length of web material, having mutually parallel first and second lateral edges when said web material is flat, such that a major portion of said length of web material is wrapped around a tube having an axis, and first and second portions adjacent or near said first and second lateral edges respectively of said length of web material extend in mutually confronting relationship outside said tube, separated by a gap;
- (b) guiding a length of string zipper comprising interlocked first and second flangeless zipper strips to a position outside said tube and parallel to said tube axis, said length of string zipper being disposed in said gap between said first and second portions of said length of web material;
- (c) joining said length of string zipper to said length of web material while said major portion of said length of web material is wrapped around said tube, thereby forming a zipper/web assembly, said first flangeless zipper strip being joined to said first portion and said second flangeless zipper strip being joined to said second portion; and
- (d) inserting a slider onto said zipper/web assembly while said major portion of said length of web material is wrapped around said tube.
23. The method as recited in claim 22, further comprising the following steps:
- (e) moving said length of web material to a position whereat said major portion of said length of web material is not wrapped around said tube;
- (f) cross sealing said zipper-web assembly in first and second transverse regions that are spaced apart while said major portion of said length of web material is not wrapped around said tube;
- (g) after said first transverse region has been cross sealed and before said second transverse region has been cross sealed, dropping product down said tube and onto said cross-sealed web in said first transverse region; and
- (h) cutting said zipper-web assembly in each of said first and second transverse regions.
24. The method as recited in claim 22, further comprising the step of trimming at least some of the excess web material that extends from said first portion of said web to said first lateral edge and at least some of the excess web material that extends from said second portion of said web to said second lateral edge.
25. A method of manufacture comprising the following steps:
- (a) guiding a length of web material, having mutually parallel first and second lateral edges when said web material is flat, such that: (i) first and second portions of said length of web material are wrapped around respective portions of a tube, (ii) first and second marginal portions adjacent said first and second lateral edges respectively of said length of web material project generally outward and away from said tube in mutually confronting relationship, and (iii) said first and second portions are connected by a loop having mutually opposing first and second walls separated by a gap;
- (b) guiding a length of string zipper comprising interlocked first and second flangeless zipper strips to a position outside said tube and parallel to said tube axis, said length of string zipper being disposed in said gap between said first and second walls of said loop;
- (c) joining said length of string zipper to said length of web material while said first and second portions of said length of web material are wrapped around respective portions of said tube, thereby forming a zipper/web assembly, said first flangeless zipper strip being joined to said first portion and said second flangeless zipper strip being joined to said second portion;
- (d) cuffing off a portion of said loop beyond said string zipper; and
- (e) after step (d), inserting a slider onto said zipper/web assembly while said first and second portions of said length of web material are wrapped around respective portions of said tube.
26. A method of manufacture comprising the following steps:
- (a) guiding a length of web material, having mutually parallel first and second lateral edges when said web material is flat, such that: (i) first and second portions of said length of web material are wrapped around respective portions of a tube, (ii) first and second marginal portions adjacent said first and second lateral edges respectively of said length of web material project generally outward and away from said tube in mutually confronting relationship, and (iii) said first and second portions are connected by a folded portion having an M-shaped profile with mutually opposing first and second interior walls separated by a gap;
- (b) guiding a length of string zipper comprising interlocked first and second flangeless zipper strips to a position outside said tube and parallel to said tube axis, said length of string zipper being disposed in said gap between said first and second interior walls of said folded portion;
- (c) joining said length of string zipper to said length of web material while said first and second portions of said length of web material are wrapped around respective portions of said tube, thereby forming a zipper/web assembly, said first flangeless zipper strip being joined to said first portion and said second flangeless zipper strip being joined to said second portion; and
- (d) inserting a slider onto said zipper/web assembly while said first and second portions of said length of web material are wrapped around respective portions of said tube.
27. A method of manufacture comprising the following steps:
- (a) guiding a web material in a machine direction through a vertical form-fill-seal (VFFS) machine;
- (b) joining a string zipper to said web material upstream of said VFFS machine;
- (c) inserting a slider over said string zipper and portions of said joined web material at a location adjacent a tube of said VFFS machine;
- (d) cross sealing said web material at an elevation below said tube; and
- (e) dropping product through said tube and onto the most recently formed cross seal.
28. The method as recited in claim 27, wherein step (b) comprises joining a first flangeless zipper strip of said string zipper to said web material upstream of said VFFS machine and joining a second flangeless zipper strip of said string zipper to said web material adjacent said tube.
29. The method as recited in claim 27, wherein step (b) comprises joining a first flangeless zipper strip of said string zipper to a first portion of said web material upstream of said VFFS machine and joining a second flangeless zipper strip of said string zipper to a second portion of said web material upstream of said VFFS machine.
30. A method of manufacture comprising the following steps:
- (a) guiding a web material in a machine direction through a vertical form-fill-seal (VFFS) machine with portions of said web material being wrapped around respective portions of a tube of said VFFS machine;
- (b) joining said web material to two sides of a string zipper to form a web/string zipper assembly, said joining step being performed at locations upstream of said VFFS machine;
- (c) removing at least a portion of the web material suspended between the zones of web/zipper joinder at a location upstream of said VFFS machine, but downstream of the locations where step (b) is performed;
- (d) inserting a slider on said string zipper at a location upstream of said VFFS machine, but downstream from the locations where step (b) is performed;
- (e) cross sealing said web material at a location downstream from said tube; and
- (f) dropping product through said tube and onto the most recently formed cross seal.
31. The method as recited in claim 30, further comprising the step of guiding said string zipper and inserted slider through a channel in a forming collar of said VFFS machine as said web/string zipper assembly advances in said machine direction through a gap between said tube and said forming collar.
32. The method as recited in claim 1, further comprising the step of guiding and turning said string zipper and said inserted slider 90 degrees between entering and exiting a forming collar.
Type: Application
Filed: Jul 30, 2004
Publication Date: Feb 2, 2006
Inventors: John Schneider (Frankfort, IL), Steven Ausnit (New York, NY), Gregory Crunkleton (Nicolson, GA), Basil Linton (Loganville, GA), Eric Fenzl (Loganville, GA)
Application Number: 10/903,453
International Classification: B65B 61/18 (20060101);