U.S. patent application number 10/903453 was filed with the patent office on 2006-02-02 for methods of manufacturing slider-operated string-zippered bags on vffs machine.
Invention is credited to Steven Ausnit, Gregory H. Crunkleton, Eric J. Fenzl, Basil C. Linton, John H. Schneider.
Application Number | 20060021295 10/903453 |
Document ID | / |
Family ID | 35124399 |
Filed Date | 2006-02-02 |
United States Patent
Application |
20060021295 |
Kind Code |
A1 |
Schneider; John H. ; et
al. |
February 2, 2006 |
Methods of manufacturing slider-operated string-zippered bags on
VFFS machine
Abstract
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.
Inventors: |
Schneider; John H.;
(Frankfort, IL) ; Ausnit; Steven; (New York,
NY) ; Crunkleton; Gregory H.; (Nicolson, GA) ;
Linton; Basil C.; (Loganville, GA) ; Fenzl; Eric
J.; (Loganville, GA) |
Correspondence
Address: |
Dennis M. Flaherty;Ostrager Chong Flaherty & Broitman P.C.
Suite 825
250 Park Avenue
New York
NY
10177-0899
US
|
Family ID: |
35124399 |
Appl. No.: |
10/903453 |
Filed: |
July 30, 2004 |
Current U.S.
Class: |
53/412 ;
53/451 |
Current CPC
Class: |
B65D 33/2591 20130101;
B65B 61/188 20130101; B65B 9/20 20130101; B65B 9/213 20130101; B65B
51/225 20130101 |
Class at
Publication: |
053/412 ;
053/451 |
International
Class: |
B65B 61/18 20060101
B65B061/18 |
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.
Description
BACKGROUND OF THE INVENTION
[0001] 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.
[0002] 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.
[0003] 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.
[0004] 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 INVENTION
[0005] The present invention is directed to methods for
manufacturing slider-operated string-zippered bags on a VFFS
machine.
[0006] 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.
[0007] 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.
[0008] 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.
[0009] 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.
[0010] 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.
[0011] 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.
[0012] 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.
[0013] Other aspects of the invention are disclosed and claimed
below.
BRIEF DESCRIPTION OF THE DRAWINGS
[0014] FIG. 1 is a drawing showing a reclosable package having a
slider-operated string zipper with end stops.
[0015] FIG. 2 is a drawing showing a partially sectioned view of a
slider-string zipper assembly incorporated in a reclosable package.
The zipper and receptacle are shown only in a section plane in
front of the closing end of the slider. The portions of the zipper
and receptacle disposed behind the section plane have not been
shown to avoid cluttering the drawing.
[0016] FIG. 3 shows one conventional VFFS machine adapted to make
slider-operated reclosable bags wherein the zipper is joined to the
film by flanges.
[0017] FIG. 4 shows another conventional VFFS machine adapted to
make slider-operated reclosable bags wherein the zipper is joined
to the film by flanges.
[0018] FIG. 5 is a drawing showing one side of a string zipper
being joined to a flat film web upstream of a VFFS machine (not
shown) in accordance with a first method of manufacture.
[0019] FIG. 6 is a drawing showing a sectional view of the web of
FIG. 5 wrapped around a tube of a VFFS machine with the other side
of the zipper about to be joined to the film web in accordance with
the first method of manufacture.
[0020] FIG. 7 is a drawing showing two zipper strips being joined
to opposite marginal portions of a flat film web upstream of a VFFS
machine (not shown) in accordance with a second method of
manufacture.
[0021] FIG. 8 is a drawing showing a sectional view of the web of
FIG. 7 wrapped around a tube of a VFFS machine with the string
zipper being held in an opened state for insertion of a slider in
accordance with the second method of manufacture.
[0022] FIG. 9 is a drawing showing a side view of a portion of a
fill tube having adjacent stations for zipper alignment, slider
insertion and zipper closure in accordance with the second method
of manufacture.
[0023] FIG. 10 is a drawing showing a sectional view of a string
zipper being joined to marginal portions of a film web wrapped
around a tube of a VFFS machine in accordance with a third method
of manufacture.
[0024] FIG. 11 is a drawing showing a sectional view of a string
zipper being joined to a gusset formed in a film web wrapped around
a tube of a VFFS machine with marginal portions of the web being
sealed together in accordance with a fourth method of
manufacture.
[0025] FIG. 12 is a drawing showing a sectional view of a string
zipper being joined to a loop formed in a film web wrapped around a
tube of a VFFS machine with marginal portions of the web being
sealed together in accordance with a fifth method of
manufacture.
[0026] FIG. 13 is a block diagram showing various stages of a sixth
method of manufacture wherein zipper sealing and slider insertion
occurs upstream of the fill tube of a VFFS machine.
[0027] FIGS. 14 and 15 are drawings showing, at different
elevations, a sectional view of a portion of a forming collar
having a relieved area for providing clearance for a slider
inserted on a string zipper/film web assembly in accordance with
the sixth method of manufacture
[0028] FIG. 16 is a drawing showing a sectional view of a portion
of the fill tube with a confronting guide for retaining the slider
and string zipper in a vertical position adjacent to the fill tube
in accordance with the sixth method of manufacture.
[0029] FIG. 17 is a drawing showing a fragmentary, partially
sectional top view of the components of a slider insertion station
as disclosed in U.S. patent application Ser. No. 10/622,996. In
this example, the zipper-film assembly moves from left to right, as
indicated by arrow A.
[0030] FIG. 18 is a drawing showing a fragmentary, partially
sectional front view of the slider insertion components for the
implementation depicted in FIG. 17. Again the zipper-film assembly
moves from left to right, while the slider is moved in a direction
out of the page during insertion.
[0031] FIG. 19 is a block diagram generally representing
programmable control of many of the components of the slider
insertion apparatus disclosed in U.S. patent application Ser. No.
10/622,996.
[0032] 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
[0033] 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 FIG. 1. It should be understood that the method
disclosed herein can make be a reclosable package of the type shown
in FIG. 1 or other types of reclosable packages having different
structures, but having in common a slider-actuated string
zipper.
[0034] 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.
[0035] From a structural standpoint, the bag 2 comprises opposing
walls (only the front panel 2a is visible in FIG. 1) that may be
secured together at opposite side edges of the bag by seams 16 and
18 (indicated by dashed lines), formed in conventional fashion,
e.g., by application of heat and pressure. The opposing bottoms of
the walls are also heat sealed together to form a bottom seam or
cross seal 20. Alternatively, functionally equivalent means can be
used. For example, the seams could be made by applying ultrasonic
wave energy instead of conductive heat.
[0036] 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 FIG. 1. The profiles of the zipper parts may take any
form. For example, the zipper may comprise interlocking rib and
groove elements, alternating hook-shaped closure elements, or
interlocking ball-shaped closure elements. The preferred zipper
material is polyethylene, but polypropylene and other plastic
materials can be used. Typically the upper margins of the front and
rear bag walls are respectively sealed to the respective zipper
parts by conduction heat sealing.
[0037] 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 FIG. 1, the slider is slidable along
the zipper in a closing direction "C", causing the zipper parts to
become engaged, or in an opening direction "O", causing the zipper
parts to become disengaged.
[0038] The bag shown in FIG. 1 further comprises end stops 12 and
14 for preventing the slider from sliding off the end of the zipper
when the slider reaches the zipper closed or fully opened position.
Such end stops perform dual functions, serving as stops to prevent
the slider from going off the end of the zipper and also holding
the two zipper profiles together to prevent the bag from opening in
response to stresses applied to the profiles through normal use of
the bag. The end stops typically comprise stomped areas on the
zipper parts themselves. The stomped end stops comprise sections of
the zipper parts that have been fused together and flattened at the
ends of the zipper. This is typically accomplished by applying
ultrasonic wave energy, but alternatively can be done by applying
sufficient heat and pressure. Ultrasonic stomping can be carried
out using ultrasonic welding equipment of the type disclosed in
U.S. patent application Ser. No. 10/113,489, entitled "Method and
Apparatus for Ultrasonically Stomping Slider End Stops on
Zipper".
[0039] 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 FIG. 2, adapted from U.S. patent
application Ser. No. 10/367,450. The receptacle 2 comprises
mutually opposing front and rear walls 2a and 2b that are joined
together on three sides, as previously described with reference to
FIG. 1.
[0040] 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.
[0041] 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 FIG. 2, provided that the free ends are not so
long as to interfere with travel of the slider along the zipper or
become entangled with the zipper profiles.
[0042] 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 FIG. 2. The upper margins of the bag walls 2a and 2b, which
are joined to the backs of the zipper strips 6 and 8, are disposed
between the respective zipper strips 6, 8 and the respective slider
sidewalls 26, 24 of the slider. Also, the slider shown in FIG. 2
has one leg (i.e., side wall 26) longer than the other, to wit, an
extension 30 of side wall 26 projects to an elevation lower than
the bottom edge of the opposing side wall 24. This design
facilitates proper orientation of the slider during automated
feeding to a slider insertion device.
[0043] 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.
[0044] In the embodiment depicted in FIG. 2, the slider 10 further
comprises a retaining projection or ledge 32 that projects inward
from the side wall 26 and a retaining projection or ledge 34 that
projects inward from the side wall 24. The ledges 32 and 34 project
toward each other, forming respective latches for latching the
slider onto the zipper, thereby increasing slider pull-off
resistance. The ledges 32 and 34 further comprise respective
inclined bottom surfaces 36 and 38 that extend downward and outward
from the respective inner edges of the generally horizontal
surfaces. The inclined surfaces 36 and 38 are each substantially
planar and serve to guide the respective zipper strips 6 and 8 into
the slider tunnel during automated insertion of the slider onto an
open section of the zipper.
[0045] 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.
[0046] The present invention is directed to methods for
manufacturing slider-actuated string-zippered bags utilizing VFFS
machines. FIG. 2 shows a portion of a slider-actuated
string-zippered bag having a specific structure. However, the
methods of manufacture disclosed herein are not limited in their
application to bags of the type having the structure shown in FIG.
2. In particular, the respective structures of the string zippers
and the sliders that can be used to construct reclosable bags can
be different than those shown in FIG. 2. For example, the string
zipper may have a single male profile and a single female profile,
instead of having the paired male and female profiles depicted in
FIG. 2, or the slider may be of the type that does not have a
separating finger.
[0047] 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.
[0048] 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.
[0049] FIG. 3 shows slider-operated reclosable bags, having flanged
zipper strips, being manufactured on a conventional VFFS machine
100. Thermoplastic film 102 is fed from a continuous supply roll
(not shown) into the VFFS 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 film
passes through a generally circular gap (not seen in FIG. 3)
between the forming collar and the top of the forming tube in a
well-known manner.
[0050] Still referring to FIG. 3, an interlocked flanged zipper 5
having sliders 11 pre-applied thereto (i.e., mounted at spaced
intervals along the zipper) is fed from a continuous coil on a
supply reel 112. The flanged zipper is guided (by conventional
means not shown) between the longitudinal edges 108, 110 of the
film 102, after which vertical seal bars 114 seal the zipper
flanges (not shown) to the longitudinal film edges 108, 110 to form
what will be the top of the bag. The sliders 11 must be clear of
the vertical seal bars 114 such that the sliders 11 do not
interfere in the sealing of the zipper 5 and are not crushed by the
vertical seal bars 114. Accordingly the zipper flanges are made
long enough to eliminate any interference between the sliders 11
and the vertical seal bars 114. The zipper flanges also assist the
zipper 5 to be guided into the VFFS machine 100 by a set of rollers
116, and thereby keep the zipper aligned with the edges of the
film.
[0051] 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.
[0052] Another conventional VFFS machine 100' for making
slider-operated reclosable bags with flanged zippers is shown in
FIG. 4. In this embodiment, the components of the VFFS machine 100'
that are designated with the same reference numerals as like
components of the VFFS machine 100 shown in FIG. 3 generally
function in the same manner. The difference with the embodiment
shown in FIG. 4 is that the zipper 5 does not have the sliders 11
pre-applied thereto. Rather, the sliders 11 are applied to the
zipper after the zipper is sealed to the longitudinal edges 108,
110 of the film 102.
[0053] As shown in FIG. 4, the sliders are supplied from a
continuous coil 128 to a slider inserter mechanism 130. Each slider
11 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 11 are fed
into the slider inserter 130. As the film 102 advances through the
VFFS machine 100' and as bags are made, a slider 11 is removed from
the connector 132 and applied to the zipper 5 of the bag 122
presently being made. After the slider 11 is applied to the zipper
5, the connector scrap 132 exits the slider inserter 130 and the
first side seal of the bag is made by the cross seal jaws 118. The
bag is then completed in the manner described above.
[0054] 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.
[0055] 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.
[0056] The operation of a conventional VFFS machine has been
generally described with reference to FIGS. 3 and 4 because similar
components are incorporated in the embodiments of the inventions
disclosed herein. In its broad concept, the method of manufacture
disclosed herein comprises 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 fill tube; (b) joining a pair of flangeless zipper
strips to respective other portions of the web material; (c)
inserting a slider on the flangeless zipper strips with web
material joined thereto; (d) cross sealing the web material at a
location downstream from the fill tube; and (e) dropping product
through the fill tube and onto the most recently formed cross seal.
Six embodiments of this method will now be described with reference
to FIGS. 5 through 16, without any intention of limiting the scope
of patent coverage to those specific embodiments. Then a
representative slider insertion apparatus, which can be employed in
any one of the disclosed methods of manufacture when the slider has
a plow (i.e., separating finger), will be described in detail with
reference to FIGS. 17 through 19, with the understanding, however,
that any other suitable slider insertion apparatus can be used. In
particular, if the sliders do not have plows, then a conventional
means for inserting a slider having no plow onto an extruded
plastic zipper can be employed in place of the slider insertion
apparatus depicted in FIGS. 17 through 19.
[0057] 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).
[0058] 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
FIG. 5, a pair of interlocked flangeless zipper strips 44 and 46,
making up a string zipper 4', are guided to a position parallel to
a lateral edge of a web 102 of bag making film and confronting a
marginal portion of the web (as seen in FIG. 5) or a band-shaped
portion of the web separated from the lateral edge by a marginal
portion (not shown in FIG. 5). [As used herein, the term "marginal
portion" means an edge and the area immediately adjacent to it,
i.e., a border.] In the former case, there will be no need to trim
excess web material on the consumer side of the zipper since the
edge of the web is generally aligned with the top of the zipper and
there is substantially no excess web material or the amount of
excess web material will not interfere with slider travel along the
string zipper. In the latter case, the excess web material on the
consumer side of the string zipper will be trimmed to prevent
interference with the slider. As seen in FIG. 5, the string zipper
4' is guided into position by a zipper guide 40 having a channel
that guides the string zipper as it is fed in the machine direction
by means not shown. At the same time, the web 102 is advanced in
the machine direction. In the case where both the zipper and web
are advanced continuously, the zipper sealing operation is
performed continuously by conventional means, in which case a
conventional dancer assembly (not shown) is provided between the
zipper sealing station and the VFFS machine for converting the
continuous web motion into intermittent web motion in synchronism
with the intermittent operation of the VFFS machine. Alternatively,
the zipper sealing operation can be performed intermittently in
synchronism with the intermittent operation of the VFFS machine. In
either case, the zipper sealing station is conventional apparatus.
For example, sealing can be accomplished using an electrically
heated sealing bar 42. In the example depicted in FIG. 5, the
heated sealing bar 42 is shown in a position whereat a marginal
portion of the web 102 can be joined to the back of the flangeless
zipper strip 46. In the case of a continuous zipper sealing
operation, the heat is conducted through an endless barrier strip
(not shown) made of Teflon or similar material, which circulates on
a set of rollers (not shown). The Teflon barrier strip moves with
the web and zipper and prevents the bag making film from sticking
against the stationary heated sealing bar during conduction heat
sealing.
[0059] Now referring to FIG. 6, after the string zipper has been
attached to the film web, the web 102 is moved over the forming
collar (not shown in FIG. 6) and around the fill tube 106, with the
other lateral edge of the web being guided and aligned with the
base of the flangeless zipper strip 44. A marginal portion of the
web (as seen in FIG. 6) or a band-shaped portion of the web
separated from the lateral edge by a marginal portion (not shown in
FIG. 6) is then joined to the back of the flangeless zipper strip
44. In one implementation of this method, the respective guides
also guide the film edges and align them with the edges of the
bases of the flangeless zipper strips. The slider is then mounted
to the string zipper. If the slider has a separating finger or
plow, the moving zipper is opened by a stationary separator plate
and kept in aligned position by the guides. The slider is then
inserted onto a section of zipper that is partially opened and
partially closed. In one implementation, a set of rollers (not
shown) then closes the zipper behind the slider. The rollers
separate as necessary to allow the slider to pass through.
Alternatively, a roller and a retaining plate can be used. Another
implementation of an apparatus for inserting a slider having a plow
will be described in more detail hereinafter with reference to
FIGS. 17-19.
[0060] In accordance with a second method partly depicted in FIG.
7, separated flangeless zipper strips 44 and 46 are guided to
respective positions parallel to the respective lateral edges of a
web 102 of bag making film and confronting a respective marginal
portion of the web (as seen in FIG. 7) or a respective band-shaped
portion of the web separated from the lateral edge by a marginal
portion (not shown in FIG. 7). Any excess web material on the
consumer side of the string zipper can be trimmed as needed to
prevent interference with the slider. As seen in FIG. 7, the
flangeless zipper strip 46 is guided into position by a zipper
guide 40a having a channel that guides the zipper strip as it is
fed in the machine direction by means not shown, while the
flangeless zipper strip 44 is guided into position by a zipper
guide 40b having a channel that guides the zipper strip as it is
fed in the machine direction by means not shown. At the same time,
the web 102 is advanced in the machine direction. The zipper strips
44 and 46 are then sealed to the respective marginal portions of
the web 102 by means of respective heated sealing bars 42.
[0061] Now referring to FIG. 8, after the zipper strips have been
attached to the film web, the web 102 is moved over the forming
collar (not shown in FIG. 8) and wrapped around the fill tube 106,
with the zipper strips 44 and 46 being guided and aligned with each
other by a guide 52 having respective channels for the respective
flangeless zipper strips. The string zipper is open within the
guide 52. Referring now to FIG. 9, downstream of the guide 52, a
slider is mounted to the open string zipper 4' by a slider
insertion device 54. Downstream of the slider insertion device 54,
the string zipper 4' is closed by a zipper closure mechanism 56
having retractable means for allowing the mounted slider to pass
through as the zipper/web assembly advances.
[0062] FIG. 10 is a drawing showing a sectional view of a string
zipper 4' being joined to marginal portions of a film web 102
wrapped around a tube 106 of a VFFS machine in accordance with a
third method of manufacture. In this method, the string zipper is
attached to the film web alongside the fill tube 106. First, the
film web 102 is paid out from a supply roll (not shown) and moved
over the forming collar (not shown). The web 102 is then wrapped
around the fill tube 106. The width of the web is greater than the
circumference of the fill tube. The respective marginal portions of
the web are guided into mutually confronting positions away from
the tube, with a gap therebetween and with the lateral edges of the
web as close to being aligned with each other as possible. The
string zipper 4' is then introduced into the gap between the
marginal portions of the web 102 with the top edges of the zipper
strips generally aligned with the lateral edges of the web.
Typically, the string zipper, as it advances, is guided by contact
with the walls of a channel of a zipper guide (not shown). When the
string zipper 4' is in an aligned position with the film edges, the
bases of the zipper strips are joined to the marginal portions of
the web by means of a pair of reciprocating heated sealing bars 48a
and 48b. Thereafter a slider is inserted onto the string zipper,
the film web is cross sealed, and product is dropped onto the cross
seal, filling the interior volume of the receptacle formed by the
sealed web. The next cross seal formed will be cut to sever the
filled bag from the zipper/web assembly in process.
[0063] In accordance with a fourth method of manufacture shown in
FIG. 11, respective portions of the web are wrapped around
respective portions of the fill tube 106. At the same time, a
portion of the web not wrapped around the fill tube is folded three
times to form an M-shaped gusseted end alongside a portion of the
fill tube, while the marginal portions (starting at the lateral
edges) of the web are guided into mutually confronting positions
alongside another portion of the fill tube. Then the string zipper
is introduced into the central fold of the gusseted end, and the
bases of the flangeless zipper strips are sealed to the opposing
walls of the central fold by heated sealing bars 48a and 48b. The
zipper sealing operation is performed with double layers of film
being merged and joined to the backs of the respective flangeless
zipper strips. [Details of this operation can be found in U.S.
patent application Ser. No. 10/617,234 filed on Jul. 10, 2003 and
entitled "Tamper-Evident Reclosable Bag Having Slider-Actuated
String Zipper". At the same time, the free marginal portions of the
film web are sealed together, e.g., by conventional heated sealing
bars 58 and 60, whether at 90.degree. or 180.degree. from the
fold.
[0064] 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.
[0065] In accordance with a fifth method of manufacture shown in
FIG. 12, respective portions of the web are wrapped around
respective portions of the fill tube 106. At the same time, a fold
or loop 86 is formed in a portion of the web not wrapped around the
fill tube, while the marginal portions (starting at the lateral
edges) of the web are guided into mutually confronting positions.
Then the string zipper is introduced into the loop 86, and the
bases of the flangeless zipper strips are sealed to the inside of
opposing walls of the film fold by heated sealing bars 48a and 48b.
At the same time, the free marginal portions of the film web are
sealed together, e.g., by conventional heated sealing bars 58 and
60, whether at 90.degree. or 180.degree. from the fold. Then the
excess film of the film fold 86 beyond the edges of the zipper
strips is trimmed. Thereafter, a slider is mounted to the string
zipper.
[0066] 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.
[0067] In accordance with a sixth method of manufacture generally
depicted in the block diagram of FIG. 13, the closed string zipper
is applied and the slider is inserted upstream of the VFFS machine.
First, the film web is folded to form a loop. Then the string
zipper is inserted inside the fold and the backs of the zipper
strips are joined to mutually confronting band-shaped portions of
the fold or loop by a zipper applicator 62. Then most of the
portion of the loop that connects the band-shaped zones of
zipper/web joinder is removed by a trimmer 64 by cutting along two
lines that are as close to the edges of the respective zipper
strips as possible. A slider insertion device 66 then opens a
section of the string zipper and inserts the slider so that the
opening end of the slider overlies a portion of the open section of
the string zipper. After slider insertion, an ultrasonic welding
station 68 deforms the string zipper into a slider end stop
structure by application of ultrasonic wave energy, causing the
zipper strips to be come fused together when the thermoplastic
zipper material cools. [Alternatively, the zipper strips could be
ultrasonically stomped in the VFFS machine alongside the tube.] The
web is unfolded with the string zipper and slider below the plane
of the web. The zipper/web assembly then processes through the VFFS
machine 70 as normal except for a relieved area on the forming
collar that provides a channel for the slider, as shown in FIGS. 14
and 15. The hatched area shown in FIG. 14 represents a section at a
first elevation through the channel of the forming collar 104,
while the hatched area shown in FIG. 15 represents a section at a
second elevation through the channel, the second elevation being
lower than the first elevation. The relieved portion of the forming
collar comprises a groove 105 designed to guide the zipper and
slider as the zipper/web assembly moves over the forming collar and
down through a gap between the forming collar and the fill tube.
The film web is advanced with the string zipper (and mounted
slider) folded in a horizontal position against the film web
because the zipper, due to its construction, cannot form an arc
when it is in a vertical position.
[0068] As seen in FIGS. 14 and 15, the channel is designed to guide
the slider and dictate its orientation as it advances in the
machine direction. As seen in FIG. 14, the flexible string zipper
must be disposed on its side to allow it to bend freely, without
opening, as it passes over the forming collar. The channel then
gradually turns with decreasing elevation along the fill tube until
the slider is generally oriented along a radial line alongside the
fill tube. During this transition, the slider is rotated about
90.degree.. FIG. 15 shows the channel 105 at a particular point in
the transition. The final positions of the zipper and slider
relative to the fill tube are shown in FIG. 16. Where the forming
collar 104 ends, the channel 105 continues downward in the form of
a retaining guide 72 that encompasses and traps the zipper and
slider adjacent the fill tube 106 and constrains the slider to be
disposed as shown in FIG. 16. In this particular implementation,
the retaining guide 72 comprises a vertical channel that guides the
zipper 4 and slider 10 as they progress downward.
[0069] 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 FIGS. 17-19.
[0070] Referring to FIG. 17, at the first station after the dancer
assembly, the slider (e.g., slider 10 shown in FIG. 2) is inserted
onto the zipper-film assembly. The slider insertion station
comprises three assemblies (namely, a separator assembly, a pusher
assembly and a clamping assembly) that cooperate to insert the
slider on the zipper while the zipper is being held open on one
side of the slider insertion zone and closed on the other side of
the slider insertion zone.
[0071] In accordance with the disclosed embodiment of the invention
shown in FIG. 17, a zippered portion of a folded web 102,
comprising a string zipper 4, is pulled through a separator
assembly 80. The separator assembly 80 disengages the zipper strips
during advancement of the zipper-film assembly, thereby opening the
string zipper 4. As best seen in FIG. 17, the separator assembly 80
comprises a central splitter plate 82 separated by gaps from upper
(84) and lower (86) guides disposed above and below the splitter
plate 82. Only the splitter plate 82 and the upper guide 84 of the
separator assembly 80 are visible in FIG. 17. The splitter plate
has a pair of mutually parallel grooves (not shown in FIG. 17) on
opposite sides thereof, the grooves being aligned with the machine
direction. In FIG. 18, the hatched region designated 82 represents
a section through the splitter plate along a plane intersecting and
parallel to the grooves. The leading edge (not shown) of the
portion of the splitter plate between the grooves pries open the
advancing interlocked zipper strips. The upper and lower guides 84
and 86 hold the respective separated zipper strips 6 and 8 in the
grooves as the zipper strips advance, thereby maintaining the
zipper strips in a straight orientation parallel to the machine
direction. The upper and lower guides can be separated from the
splitter plate to facilitate aligning the zipper in the
inserter.
[0072] 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 FIG. 18) prevent cross-directional wandering of the
separated zipper strips 6, 8.
[0073] Referring again to FIG. 17, the pusher assembly 96 comprises
a pusher 98 that pushes a slider 10 onto an open section of the
zipper in a slider insertion zone. The pusher displacement is
driven by an air cylinder 92. The pusher is fixed to a distal end
of a rod 94 of a piston slidable inside the cylinder 92. The pusher
98 is alternately extended and retracted by actuation of the air
cylinder 92, which has two separate ports (not shown) for intake of
compressed air from separately controlled air lines. The pusher 98
travels along a straight tunnel or channel 88, shown in section in
FIG. 17. One sidewall of the channel 88 has an opening that
communicates with the end of a slider track 90. A succession of
sliders 10' are fed periodically along track 90 by a conventional
pneumatic slider feeding system (not shown). When the pusher 98 is
retracted, the next slider (designated by 10' in FIG. 5) must be
automatically fed to a pre-insertion position directly in front of
the pusher 98.
[0074] Referring to FIG. 18, upstream and downstream of the slider
insertion zone, the zipper strips 6, 8 are clamped by the clamping
assembly 140, which comprises a U-shaped upper clamp 142 and a
U-shaped lower clamp 144. The upper clamp 142 comprises an upstream
arm 146, a downstream arm 148 and a cross member 150 that is
connected to and supports arms 146 and 148. [Arms 146 and 148 are
shown in section in FIG. 17.] Similarly, the lower clamp 144
comprises an upstream arm 152, a downstream arm 154 and a cross
member 156 that is connected to and supports arms 152 and 154. Each
of the four arms of the clamping assembly has a textured end face
to provide additional holding force. A portion of the splitter
plate 82 is disposed in the space between the confronting end faces
of the upstream clamp arms 146 and 152. The downstream arms 148 and
154 are longer than the upstream arms by roughly one-half the
thickness of the splitter plate at the grooves. In the disclosed
embodiment, the end faces of the upstream clamp arms 146 and 152
each have a surface comprising a respective plurality of mutually
parallel ridges aligned with the cross direction, while the
downstream clamp arms 148 and 154 each have a surface comprising a
respective plurality of mutually parallel ridges aligned with the
machine direction. This upper and lower clamping arrangement fixes
the respective positions of the zipper strips at each end of the
slider insertion zone. In particular, the cross-directional ridges
on the end faces of the upstream clamp arms, in combination with
the splitter plate grooves aligned with the machine direction, fix
the positions of the separated zipper strips in both directions.
Alternatively, the surface of each clamp arm end face may comprise
a multiplicity of projections or teeth arranged in a
two-dimensional array. For example, such an array of teeth can be
formed by providing a lattice of grooves on the end face.
[0075] 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 FIG. 17.
[0076] As best seen in FIG. 18, on the upstream side of the slider
insertion zone, the clamp arms 146 and 152 clamp the zipper strips
6 and 8 in the grooves of the splitter plate 82. Due to the
thickness of the intervening splitter plate, the section of the
zipper near the trailing edge of the splitter plate is clamped in
an opened state. Conversely, on the downstream side of the slider
insertion zone, the clamp arms 148 and 154 clamp the adjoining
section of the zipper closed. Thus, the upper and lower clamps of
the clamping assembly 140 serve to stabilize the zipper during
slider insertion in the zone between the upstream and downstream
arms of the clamps. The zipper strips are held in respective
positions such that the slider plow 28 enters the gap between the
zipper strips and then the slider sidewalls respectively pass over
the zipper strips during slider insertion. The slider is pushed
onto the zipper until the retaining ledges on the slider interior
latch under the zipper strips to hold the slider securely on the
zipper. The proximity of closed zipper to the closing end of the
slider and the presence of open zipper at the opening end of the
slider and adjacent the plow facilitates insertion of the slider
onto the zipper. In particular, one function of the splitter plate
and clamp arrangement is to create a funnel shape with the zipper
opening so that the slider plow can project between the zipper
strips during insertion.
[0077] 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.
[0078] 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.
[0079] 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 FIG. 18) between the grooves pries the moving
zipper strips apart. The splitter plate 82 may have parallel sides
or may taper linearly from the neck to the distal edge thereof. As
previously described, the separator assembly further comprises an
upper guide 84 and a lower guide 86, which are positioned on
opposing sides of the splitter plate 82 with respective gaps
therebetween for passage of the respective walls of the film web.
The upper and lower guides 84 and 86 hold the respective zipper
strips in the respective grooves formed in the splitter plate 82.
Thus, as the zipper-film assembly is pulled through the bag making
machine, the splitter plate 82 will pry open successive
package-length sections of zipper during successive zipper-film
advancements, assuming that each advance is equal to one package
length.
[0080] 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 FIG. 19. Alternatively,
hydraulic cylinders could be used. Operation of the cylinders is
controlled by a programmable controller 180, which selectively
activates the supply of fluid to the cylinders in accordance with
an algorithm or logical sequence. The controller may also take the
form of a computer or a processor having associated memory that
stores a computer program for operating the machine. The controller
180 is programmed to actuate the cylinders in the following order:
first, cylinders 168 and 172 are actuated to extend the clamps 142
and 144; then the cylinder 92 is actuated to extend the pusher 98.
These operations are performed during a dwell time, i.e., while the
zipper is stationary. After each dwell time, the zipper is advanced
(with or without attached bag making film) by a conventional zipper
advancement mechanism 184 that is also controlled by the controller
180. In the case where bag making film is attached to the zipper,
the zipper advancement mechanism may comprise drive rollers that
pull the film forward. During zipper advancement, the controller
180 may also activate a slider feeding mechanism 182, causing the
next slider in line to be moved to a pre-insertion position on the
pusher.
[0081] 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.
[0082] 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.
[0083] 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.
[0084] 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.
* * * * *