U.S. patent application number 10/780846 was filed with the patent office on 2005-08-18 for method and apparatus for making flexible articles having elastic-like behavior with visually distinct regions.
Invention is credited to Broering, Shaun Thomas, Peck, Daniel Charles, Waldron, Matthew William.
Application Number | 20050178493 10/780846 |
Document ID | / |
Family ID | 34838640 |
Filed Date | 2005-08-18 |
United States Patent
Application |
20050178493 |
Kind Code |
A1 |
Broering, Shaun Thomas ; et
al. |
August 18, 2005 |
Method and apparatus for making flexible articles having
elastic-like behavior with visually distinct regions
Abstract
A method of forming flexible bags from a continuous web is
disclosed. The method includes introducing a continuous web of
sheet material and passing it through a process whereby the
flexible bag is formed having elastic-like behavior. The continuous
web is processed into a continuous web having at least two regions
that are visually distinct. A sheet material is introduced having
one portion of the sheet material overlapping another portion of
the sheet material. The sheet material is formed into a strainable
network. The strainable network includes a plurality of first
regions and a plurality of second regions. The first regions are
substantially un-deformed and the second regions are formed into
disengageable pleat elements. As the overlapped portions of the
sheet material are formed they engage each other at the pleat
elements. The pleat elements of each overlapped portion become
engaged within each other and resist disengagement because of the
frictional forces of the sheet material. The overlapped portions of
the sheet material are separated using a disengaging means so that
the overlapped portions become disengaged and are separated from
each other while riding on the disengaging means. The disengaging
means is in the form of either air knife, static opening bar,
dynamic opening bar, or suction means, and any combinations
thereof.
Inventors: |
Broering, Shaun Thomas; (Ft.
Thomas, KY) ; Waldron, Matthew William; (West
Chester, OH) ; Peck, Daniel Charles; (Cincinnati,
OH) |
Correspondence
Address: |
The Procter & Gamble Company
Intellectual Property Division
Winton Hill Technical Center-Box 161
3110 Center Hill Avenue
Cincinnati
OH
45224
US
|
Family ID: |
34838640 |
Appl. No.: |
10/780846 |
Filed: |
February 18, 2004 |
Current U.S.
Class: |
156/197 ;
156/205; 156/253; 156/269; 156/474; 383/118; 383/120 |
Current CPC
Class: |
Y10T 156/1003 20150115;
B31B 50/00 20170801; B31B 70/942 20170801; B31B 70/003 20170801;
B31B 70/88 20170801; Y10T 156/1016 20150115; Y10T 156/1084
20150115; B31B 70/98 20170801; Y10T 156/1057 20150115 |
Class at
Publication: |
156/197 ;
156/205; 156/474; 156/253; 156/269; 383/118; 383/120 |
International
Class: |
B65D 030/02; B65D
030/20; B65B 043/04 |
Claims
What is claimed is:
1. A method of making an article having elastic-like behavior
comprising the steps of: Introducing a sheet material having at
least one overlapped portion; Forming said overlapped portion of
sheet material into a strainable network including a plurality of
first regions and a plurality of second regions, said first regions
being substantially un-deformed and said second regions being
formed into disengagable pleat elements; and Disengaging said pleat
elements using a disengaging means:
2. The method of making an article according to claim 1, wherein
said disengaging means is selected from the group consisting of air
knife, static opening bar, dynamic opening bar, and suction means,
and any combinations thereof.
3. The method of making an article according to claim 1, further
comprising the step of overlapping one portion of sheet material
over another portion of sheet material.
4. The method of making an article according to claim 2, further
comprising the step of separating said overlapped portions of said
sheet material using said disengaging means.
5. The method of making an article according to claim 2, wherein
said dynamic opening bar comprises at least one first set of
rollers and said pleat elements are disengaged from each other
while at least one portion of said sheet material rides over an
opposite outer segment of at least one roller.
6. The method of making an article according to claim 5, wherein
said dynamic opening bar includes an end cap.
7. The method of making an article according to claim 5, wherein
said dynamic opening bar is wholly surrounded by said overlapped
portions of said sheet material.
8. The method of making an article according to claim 5, wherein
said dynamic opening bar comprises a second set of rollers and said
pleat elements remain engaged as said sheet material passes between
a first set of rollers and thereafter said pleat elements are
disengaged while at least a portion of said sheet material is
riding over at least one opposite outer segment of a second set of
rollers.
9. The method of making an article according to claim 1, wherein
said disengaging step further comprising riding said sheet material
on said disengaging means.
10. The method of making an article according to claim 2, wherein
the step of forming further comprises forming said pleat elements
as said sheet material passes between a pair of forming rollers, at
least one forming roller having toothed regions and grooved
regions.
11. The method of making an article according to claim 2, wherein
said disengaging step further comprises the step of applying a
vacuum to at least one overlapped portion of said sheet
material.
12. The method of making an article according to claim 1, further
comprising the step of winding said sheet material onto a roll.
13. The method of making an article according to claim 1, further
comprising the step of incorporating a closure means into said
sheet material.
14. The method of making an article according to claim 1, further
comprising the step of unwinding a continuous web of sheet material
from a roll.
15. The method of making an article according to claim 1, further
comprising the steps of extruding a raw plastic material and
converting the extruded plastic material into a continuous web of
sheet material.
16. The method of making an article according to claim 1, further
comprising the step of forming flexible bags from said sheet
material.
17. The method of making an article according to claim 16, further
comprising the step of sealing at least one edge of said flexible
bag, and severing said sheet material across a width thereof at
said sealed edge to separate said sheet material into individual
flexible bags.
18. The method of making an article according to claim 16, further
comprising the step of sealing at least one edge of said flexible
bag, and perforating said sheet material across a width thereof at
said sealed edge.
19. The method of making an article according to claim 18, further
comprising the step of interleaving said individual flexible
bags.
20. A method of making an article having elastic-like behavior
comprising the steps of: Introducing at least one sheet material
having at least one overlapped portion; Forming said overlapped
portion of sheet material into at least one region of disengagable
pleat elements; and disengaging said pleat elements using a
disengaging means selected from the group consisting of air knife,
static opening bar, dynamic opening bar, and suction means, and any
combinations thereof.
Description
TECHNICAL FIELD
[0001] The present invention relates to a method and apparatus for
the production of flexible articles from a continuous web; and more
particularly, a method and apparatus for the making of flexible
bags having elastic-like behavior is disclosed.
BACKGROUND OF THE INVENTION
[0002] Flexible articles, particularly flexible bags made of
comparatively inexpensive plastic materials, have been widely
employed for the containment and/or disposal of various items. As
utilized herein, the term "flexible" refers to materials that are
capable of being flexed, stretched, or bent, especially repeatedly,
such that they are pliant and yieldable in response to externally
applied forces. Accordingly, "flexible" is substantially opposite
in meaning to the terms inflexible, brittle, or unyielding.
Materials and structures that are flexible, therefore, may be
altered in shape and structure to accommodate external forces and
to conform to the shape of objects brought into contact with them
without losing their integrity. Flexible bags of the type commonly
available are typically formed from materials having consistent
physical properties throughout the structure of the flexible bag
including such properties as stretch, tensile, and/or elongation
properties. Typically, such flexible bags are utilized as trash
bags, body bags, Christmas tree disposal bags, colostomy bags, dry
cleaner bags, laundry bags, stock pick bags, and shopping bags.
Methods for making such bags are well known in the art. Typical of
such prior art is that disclosed in U.S. Pat. No. 4,867,735 issued
to Wogelius on Sep. 19, 1989 that discloses a method and apparatus
for continuous fabrication of bags from a multilayer thermoplastic
film web.
[0003] Some flexible bags have also been made from thin films that
have deformations formed in them. A known method of forming such
films is by passing a continuous web between a pair of matched
forming rollers to form an intentional pattern of deformations on
the film. One problem that arises when making flexible bags from a
film formed in this manner is that, if the film has at least one
overlapped layer or is made in a tubular manner, when having
deformations formed therein, one layer becomes engaged within the
other and is difficult to separate for subsequent processing. A
similar problem arises when films such as thermoplastic elastomeric
films exhibit excessive blocking characteristics. Blocking is the
tendency of a film to adhere to itself. One approach to resolving
this problem for continuous webs made in a tubular manner is to
inflate the tube of film with air to separate the two formed
layers. For example, U.S. Pat. No. 3,857,144 issued to Bustin on
Dec. 31, 1974 discloses making a flexible bag in which a
polyethylene film is passed between a pair of matched forming
rollers and the continuous formed web is then inflated or an air
bubble is trapped within the web to separate the two formed layers.
Also, illustrative of the state of the art with regard to flexible
bags and continuous webs with intentional patterns of deformations
formed in them are, for example, U.S. Pat. No. 5,554,093 issued to
Porchia et al. on Sep. 10, 1996, U.S. Pat. No. 5,575,747 issued to
Dais et al. on Nov. 19, 1996, U.S. Pat. No. 5,723,087 issued to
Chappell et al. on Mar. 3, 1998, and U.S. Pat. No. 6,394,652 issued
to Meyer et al. on May 28, 2002.
[0004] It is frequently difficult to separate the overlaying or
overlapping layers of film in which deformations have been formed
which can cause problems during subsequent processing. This problem
is even more acute when the continuous web from which the flexible
bags are made is not in a tubular configuration that can be easily
inflated using air. In particular, many flexible bags are made by
simply laying at least one thin plastic sheet over another or by
folding a sheet or a continuous web over onto itself in an
overlapped or "C" fold configuration. In these instances, inflating
the continuous web using air is not a practical method to separate
the overlapping layers since the air has a tendency to escape
through the open edge opposite the fold. Even when a tubular
configuration of continuous web is used, an air bubble can have a
tendency to leak air out through the deformations or creases formed
in the continuous web. Consequently, it is desirable to identify a
process for easily separating overlapped layers of a continuous web
after patterns of deformations have been formed in the continuous
web. Additionally, it is desirable to provide such a process and
apparatus capable of producing flexible bags from a continuous web
at high speeds in a consistent manner.
SUMMARY OF THE INVENTION
[0005] The present invention provides a method and apparatus for
making flexible articles such as flexible bags and the like from a
continuous web of sheet material.
[0006] In one embodiment of the present invention, a continuous
process for making flexible articles having elastic-like behavior
is provided. The process comprises several steps. A sheet material
is introduced having one portion of the sheet material overlapped
onto another portion of the sheet material. The sheet material is
formed into a strainable network. The strainable network includes a
plurality of first regions and a plurality of second regions. The
first regions are substantially un-deformed and the second regions
are formed into disengageable pleat elements. As the overlapped
portions of the sheet material are formed they engage each other in
the pleat elements. The pleat elements of each overlapped portion
become trapped within each other and resist disengagement because
of the frictional forces and attractive forces of the sheet
material. The overlapped portions of the sheet material are
separated using a disengaging means so that the overlapped portions
become disengaged and separated from each other upon riding on the
disengaging means. Preferably, the disengaging means is in the form
of a static opening bar, a dynamic opening bar, or a suction means.
More preferably, the flexible article is a flexible bag that is
formed from the sheet material.
BRIEF DESCRIPTION OF THE DRAWINGS
[0007] While the specification concludes with claims particularly
pointing out and distinctly claiming the present invention, it is
believed that the present invention will be better understood from
the following description in conjunction with the accompanying
drawing figures, in which like reference numerals identify like
elements, and wherein:
[0008] FIG. 1 is a perspective view of a flexible bag made in
accordance with the present invention;
[0009] FIG. 2 is a schematic illustration of a process to
manufacture flexible bags in accordance with the present
invention;
[0010] FIG. 3 is a simplified perspective illustration of a forming
apparatus in accordance with the present invention;
[0011] FIG. 4 is a simplified side view of an alternative forming
apparatus with the continuous web in accordance with the present
invention;
[0012] FIG. 5 is a partial plan view illustration of the continuous
web of sheet material resulting from the present invention in a
partially tensioned condition;
[0013] FIG. 6 is a perspective illustration of a static opening bar
in accordance with the present invention;
[0014] FIG. 7 is an illustration of a static opening bar and
continuous web taken at section line 7-7 of FIG. 6;
[0015] FIG. 8 is a perspective illustration of one embodiment of a
dynamic opening bar in accordance with the present invention;
[0016] FIG. 9 is a perspective illustration of another embodiment
of a dynamic opening bar in accordance with the present
invention;
[0017] FIG. 10 is a side view illustration of a dynamic opening bar
with the continuous web of the present invention;
[0018] FIG. 11 is a perspective illustration of one embodiment of
an end cap in accordance with the present invention;
[0019] FIG. 12 is a perspective illustration of a preferred
embodiment of a dynamic opening bar in accordance with the present
invention;
[0020] FIG. 13 is a side view illustration of a preferred dynamic
opening bar with the continuous web of the present invention;
[0021] FIG. 14 is a perspective illustration of yet another
embodiment of a dynamic opening bar in accordance with the present
invention;
[0022] FIG. 15 is a perspective illustration of the dynamic opening
bar of FIG. 13 captured within a cage in accordance of the present
invention;
[0023] FIG. 16 is a side view illustration of an alternative
embodiment of a dynamic opening bar and a cage;
[0024] FIG. 17 is a perspective illustration of an alternative
embodiment of a disengaging means in accordance with the present
invention with vacuum manifold disconnected for clarity;
[0025] FIG. 18 is a side view illustration of yet another
alternative embodiment of a disengaging means in accordance with
the present invention; and
[0026] FIG. 19 is a perspective view of a roll of flexible bags
made in accordance with the present invention.
DETAILED DESCRIPTION OF THE INVENTION
[0027] In this detailed description of the present invention, any
patent or non-patent literature referenced herein and the
disclosure contained therein is intended to be and is hereby
incorporated by reference.
[0028] Referring now to FIG. 1 in which is illustrated a preferred
embodiment of a flexible bag 10 made according to the present
invention. Flexible bag 10 includes bag body 20, an opening along
top edge 28, a sealed first seam 21, a sealed second seam 23, and a
closed bottom formed at bottom fold 22. Preferably, flexible bag 10
includes first regions 64 and second regions 66 forming a
strainable network across bag body 20. In one embodiment of
flexible bag 10, first regions 64 are in a substantially
crisscrossing pattern across bag body 20. In this embodiment,
flexible bag 10 is tubular in shape and has an interior 12.
Flexible bag 10 is illustrated with optional closure means 30
located at or adjacent to top edge 28. Optional closure means 30
can be used to close flexible bag 10 forming a fully enclosed
container to assure the contents contained in its interior 12 do
not escape through the opening at top edge 28.
[0029] Preferably, flexible bag 10 is constructed from a sheet
material 52 that is suitable for containing and protecting a wide
variety of items and/or objects contained within interior 12 of
flexible bag 10. The term "sheet material" as used herein is the
composition or substance from which the articles described herein
are made. Various materials known in the art are suitable for
constructing sheet material 52 used in flexible bags 10 made in
accordance with the present invention. For example, some typical
sheet materials 52 for making such flexible bags 10 can be
substantially impermeable materials including any polymeric
material. Exemplary, but non limiting, polymeric materials can
include polyvinyl chloride (PVC), polyvinylidene chloride (PVDC),
and any polyolefin such as linear low density polyethylene (PE),
low density PE, high density PE or polypropylene (PP). Other types
of materials may include aluminum foil, thin sheet metal, coated
(waxed, etc.) and uncoated paper, coated nonwovens, or can even be
substantially permeable materials including any scrims, meshes,
wovens, nonwovens, or perforated or porous films, whether
predominantly two-dimensional in nature or formed into
three-dimensional structures. Such sheet materials 52 may comprise
a single composition or layer or may alternatively be a composite
or laminate structure of disparate materials or multiple layers, or
any combinations thereof.
[0030] In yet another embodiment of the present invention, sheet
material 52 can be formulated to include a slip agent. Slip agents
can bloom to the surface of sheet material 52. In addition to
having slip agents incorporated in the composition of sheet
material 52, additional slip agents can be applied to the surface
of at least a portion of sheet material 52. A slip agent is a
compound or composition that can help to reduce the coefficient of
friction on the surface of sheet material 52 thereby making the
sheet material 52 easier to disengage and separate from any
overlapping portion. Slip agents may even prevent portions of sheet
material 52 from adhering to each other. Some exemplary slip agents
can include, for example, talc (hydrated magnesium silicate),
diatomaceous earth, ceramic microspheres, N-Ethylenebisstearammide,
erucamide, acrawax C, graphite, or the like. Ceramic microspheres
useful herein are commercially available from 3M Corporation under
the name Zeeospheres.TM. ceramic microspheres.
[0031] Various articles other than flexible bags 10 can be produced
using the present invention including, for example, cartons, cans,
containers, bottles, boxes, jars, packages, pouches, plates, wraps,
webs, films, sheets, and the like. Some of the numerous product
applications for flexible bags 10 made as disclosed herein include,
for example, sandwich bags, food storage bags, trash bags, body
bags for containment of human or animal remains, Christmas tree
disposal bags, colostomy bags, dry cleaning and/or laundry bags,
bags for collecting items picked from warehouse inventory (stock
pick bags), shopping bags, and the like.
[0032] In one embodiment of the present invention, flexible bags 10
can be made from raw materials in that the process begins with the
manufacture of a continuous web 53 of sheet material 52 from which
a multiplicity of flexible bags 10 is produced. The term
"continuous web" as used herein is an integral length of sheet
material 52 sufficient to fabricate a multiplicity of flexible bags
10 connected in an edge-to-edge configuration. In another
embodiment of the present invention, flexible bags 10 can be made
from a previously produced roll or discrete piece of sheet material
52 which is then introduced into the process defined herein.
[0033] Referring now to FIG. 2, one method for making flexible bag
10 is by creating sheet material 52 and converting it into multiple
flexible bags 10 through a continuous or discontinuous process. A
raw plastic material can be formed by blowing or casting a
continuous web 53 of sheet material 52 as is well known in the art.
For example, a continuous web 53 can be blown from a raw stock of
plastic material introduced in pellet form into an extruder 120,
from which a tubular structure such as a tube 51 of thin plastic
material is extruded through tubular die 121. Tube 51 is inflated
by blowing or capturing an air bubble within tube 51. Typically,
this tube 51 is cooled as it rises. Tube 51 can be pressed together
through a set of pinching rollers 122. Pinching rollers 122
collapse the air bubble and compress the walls of tube 51 together
into a flattened continuous web 53 of sheet material 52 having at
least one overlapped portion. Overlap or overlay as used herein
includes, without limitation, any ply, layer, web, film or sheet
laid on any portion of another. For example, overlapped can include
multiple layers, multiple-ply, laminates, tubes, folded sections,
gussets, or any two sheets laying on any part of another sheet or
even on any part of the same sheet. Consequently, sheet material 52
can be overlapped in a manner that the overlapped portions are
placed into contact with each other. It is when the overlapped
portions of sheet material 52 are in contact that they can
thereafter be disengaged and separated such that they are no longer
in contact with each other. One method for making a continuous web
53 of sheet material 52 is disclosed in U.S. Pat. No. 3,857,144
issued to Bustin on Dec. 31, 1974. Another way to make a continuous
web 53 of sheet material 52 is by casting the continuous web 53 and
one such casting method is disclosed in U.S. Pat. No. 4,428,788
issued to Kamp on Jan. 31, 1984.
[0034] In a preferred embodiment of the present invention,
continuous web 53 can pass through or over cutting station 154
after passing through pinching rollers 122. Cutting station 154 can
simply be a blade or a set of blades that can cut or slit
continuous web 53 longitudinally as it passes over cutting station
154. In one embodiment of the present invention, a single
continuous web 53 can be cut into two or more continuous webs 53
which can then be wound into rolls 11 and stored for future use or,
alternatively, one or more of such continuous webs 53 are
introduced into additional converting station as described herein.
For example, continuous web 53 can be cut by cutting station 154 so
as to separate continuous web 53 into four separate continuous webs
53 such that two of the resulting continuous webs 53 are
substantially curved having a substantially "C" shaped transverse
cross-section and the other two continuous webs 53 are
substantially flat. The two flat continuous webs 53 can then be
passed through separate folding stations 133 to fold sheet material
52 in order to overlap at least one portion over another and then
these continuous webs 53 can be wound onto rolls 11. Alternatively,
the two flat continuous webs 53 can be wound into rolls 11 without
folding. Likewise the two substantially curved continuous webs 53
can be passed through separate folding stations 133 to overlap at
least one portion of sheet material 53 onto another. The
substantially "C" shaped cross-section is formed by overlapping or
overlaying at least a portion of the sidewalls of sheet material 52
over each other. Thereafter the sidewalls are referred to as being
connected through a folded region, which in the present embodiment
is bottom fold 22. Alternatively, two flat continuous webs 53 or
other discrete pieces of sheet material 53 can be laid into contact
with each other and sealed together along a longitudinal edge
forming the region referred to as bottom fold 22. Each continuous
web 53 of sheet material 52 can then be independently wound into
rolls 11 for future use or can be immediately processed according
to the present invention.
[0035] Once sheet material 52 is produced, it can be introduced
into a continuous or discontinuous process for making articles such
as flexible bags 10 through transport rollers 123. In this same
manner, sheet material 52 can be introduced into multiple
converting stations for immediate processing. At various points
along the process described herein, continuous web 53 of sheet
material 52 can be wound into a roll 11 and stored for future use
in this or another process as is known by those of ordinary skill
in the art. "Continuous process" as used herein means repetitive,
ongoing or continuing steps that are not intended to stop or cease
until multiple flexible bags 10 are produced. As used herein,
"introduce" can mean pass, feed, insert, engage, flow or push sheet
material 52 into the next converting station. At winding station
111, sheet material 52 is wound into rolls 11 of sheet material 52
as is known by those of ordinary skill in the art. Sheet material
52 can be introduced into any one of the numerous converting
station by unwinding a previously wound roll 11 of sheet material
52 and introducing it through transport rollers 123.
[0036] The processing of continuous web 53 of sheet material 52
continues as sheet material 52 passes through the next converting
station which can be an alternative or optional step. This optional
step can be closure station 160 which incorporates or forms closure
means 30 onto sheet material 52. Closure means 30 is formed at edge
28 and is used to seal or close off interior 12 after flexible bag
10 is filled with contents. Under some circumstances a closure
means 30 formed by a lesser degree of encirclement (such as, for
example, a closure means disposed along only one side of edge 28)
may provide adequate closure integrity. Closure means 30 can be
made from a strip of flexible plastic material in accordance with
U.S. Pat. No. 4,624,654 issued to Boyd et al. on Nov. 25, 1986.
[0037] Other types of closure means 30 may alternatively be
utilized including, for example, drawstring-type closures, tieable
handle tabs or flaps, twist tie or interlocking strip closures,
adhesive-based closures, interlocking mechanical seals with or
without slider-type zipper closure mechanisms, removable ties or
strips made of plastic or other materials, heat seals, or any other
suitable closure means 30 can be used. Such closure means 30 are
well known in the art as are methods of manufacturing and making
them. Alternatively, closure means 30 of any design and
configuration suitable for its intended purpose may be utilized in
constructing flexible bags 10 according to the present invention.
In yet another alternative embodiment, closure means 30 can be
omitted from flexible bag 10. After closure means 30 is
incorporated into continuous web 53 of sheet material 52,
continuous web 53 of sheet material 52 can be introduced to the
next converting station through transport rollers 123.
[0038] Now referring to FIG. 3, forming apparatus 500 includes a
pair of rollers 502, 504. First roller 502 includes a plurality of
toothed regions 506 and a plurality of grooved regions 508 that
extend across cylindrical roller 502. Toothed regions 506 include a
plurality of teeth 507. Second roller 504 includes a plurality of
teeth 510 which mesh with teeth 507 on roller 502. An alternative
embodiment of intermeshing first roller 502 and second roller 504
is illustrated in FIG. 4 along with a continuous web 53 of sheet
material 52. Continuous web 53 of sheet material 52 can be
introduced into forming apparatus 500 to form a strainable network
having at least two visually distinct regions 64, 66. As continuous
sheet material 52 is passed between intermeshing rollers 502 and
504, grooved regions 508 will leave portions of continuous web 53
of sheet material 52 unformed producing first regions 64. The
portions of continuous web 53 of sheet material 52 passing between
toothed regions 506 and teeth 510 will be formed by teeth 507 and
510, respectively, into a plurality of disengageable pleat elements
74 in second regions 66.
[0039] As sheet material 52 passes between first forming roller 502
and second forming roller 504, disengageable pleat elements 74 are
formed into the overlapped portions of sheet material 52. The
overlapped portions of sheet material 52 are pressed into contact
with each other at first regions 64 and are pressed into engaging
contact with one another in second regions 66 where the raised
pleat elements 74 are formed. Regions 66 can comprise rows of
deeply formed deformations in sheet material 52 of continuous web
53, while regions 64 can comprise intervening un-deformed portions
of continuous web 53.
[0040] Forming apparatus 500 can form discrete areas having an
increased frequency of pleat elements 74 or discrete areas having a
decreased frequency of pleat elements 74 in sheet material 52 by
increasing or decreasing the concentration of teeth 507 along the
circumference of forming roller 502 and along the width of forming
roller 502. Likewise, the height of teeth 507 on forming roller 502
can vary within a particular toothed region 506 and along the
circumference of forming roller 502 in order to vary the height of
corresponding pleat elements 74. Such a configuration of forming
apparatus 500 allows pleat elements 74 to be formed in sheet
material 52 having predetermined elongation characteristics. As
used herein, the term "formed" refers to the creation of a desired
three-dimensional structure or geometry upon sheet material 52 that
will substantially retain its shape when it is not subjected to any
externally applied elongation or other forces. The term "pleat"
refers to a formation having a major axis and a minor axis wherein
the major axis is equal to or preferably greater than the minor
axis.
[0041] In accordance with the present invention as illustrated in
FIG. 5, these first regions 64 and second regions 66 impart bag
body 20 of flexible bag 10 with an elastic-like behavior. As used
herein, the term "elastic-like" describes the behavior of flexible
materials which when subjected to an applied elongation force, the
flexible materials extend in the direction of the applied
elongation and when the applied elongation is released the flexible
materials return, to a substantial degree, to their untensioned
condition. In particular, sheet material 52 includes a "strainable
network" of distinct regions 64, 66. As used herein, the term
"strainable network" refers to an interconnected and interrelated
plurality of first regions 64 and second regions 66 which enable
the elastic-like behavior. This strainable network can be extended
to some useful degree in a predetermined direction, such as along
axis "T", in response to the applied and subsequently released
elongation force. In particular, pleat elements 74 are able to
unbend, unfold or geometrically deform in a direction substantially
perpendicular to their first axis 76 to allow extension of sheet
material 52 in response to such an applied axial elongation. Sheet
material 52 made in accordance with the present invention is
configured such that the un-deformed first regions 64 are visually
distinct from the substantially deformed second regions 66. As used
herein, the term "visually distinct" refers to features of sheet
material 52 which are readily discernible to the normal naked eye
when sheet material 52 or articles incorporating sheet material 52,
such as flexible bags 10, are observed.
[0042] Additionally, while it is presently preferred to construct
substantially the entire bag body 20 from a sheet material 52
having the structure and characteristics made in accordance with
the present invention, it may be desirable under certain
circumstances to provide such elastic-like behavior in only one or
more portions or zones of bag body 20 rather than its entirety. For
example, bag body 20 of flexible bag 10 can have discrete areas
where first regions 64 and second regions 66 exist and the
strainable network is evident while also having discrete areas of
bag body 20 without any such strainable network. These discrete
areas can be produced when forming rollers 502, 504 that produce
pleat elements 74 are intermittently retracted or removed from
being in contact with sheet material 52 as continuous web 53 passes
through forming apparatus 500. This intermittent removal or opening
of forming rollers 502, 504 allows discrete areas of un-deformed
sheet material 52 to be created. Such intermittent removal can be
synchronized to create a repeating pattern of discrete areas that
are un-deformed while also providing discrete areas that are formed
of first regions 64 and second regions 66 in a strainable network.
Sealing land 26, first seam 21, bottom fold 22, and second seam 23
(shown in FIG. 1) are each an example of areas that can be wholly
void of any such strainable network. Sealing land 26, first seam
21, and second seam 23 can be un-deformed areas that help assure
proper sealing.
[0043] Sheet materials 52 such as those illustrated and described
herein as suitable for use in accordance with the present invention
are described in greater detail in commonly assigned U.S. Pat. No.
5,518,801 issued to Chappell et al. on May 21, 1996; U.S. Pat. No.
5,691,035 issued to Chappell et al. on Nov. 25, 1997; and U.S. Pat.
No. 5,650,214 issued to Anderson et al. on Jul. 22, 1997; and U.S.
Pat. No. 5,723,087 issued to Chappell et al. on Mar. 3, 1998. A
flexible bag 10 made from sheet material 52 including the
strainable network for use with the present invention is
illustrated and described in greater detail in commonly assigned
U.S. Pat. No. 6,394,652 issued to Meyer et al. on May 28, 2002.
While continuous web 53 has been described in this process along
with forming rollers 502, 504, it is understood that a discrete
piece of sheet material 52 can be substituted for such continuous
web 53 and reciprocating forming plates or any other device can
alternatively be used to form the strainable network having first
regions 64 and second regions 66. The term "discrete piece" as used
herein is an integral length of sheet material 52 sufficient to
fabricate only a portion of or only a few flexible bags 10
connected in an edge-to-edge configuration.
[0044] Another method of forming sheet material 52 suitable for use
in the present invention is vacuum forming. An example of a vacuum
forming method is disclosed in commonly assigned U.S. Pat. No.
4,342,314 issued to Radel et al. on Aug. 3, 1982. Alternatively,
the sheet material 52 may be hydraulically formed in accordance
with the teachings of commonly assigned U.S. Pat. No. 4,609,518
issued to Curro et al. on Sep. 2, 1986. After the strainable
network is incorporated into sheet material 52, it can be
introduced to the next converting station through transport rollers
123.
[0045] After forming continuous web 53 in the manner described, it
is frequently difficult to separate overlaying or overlapping
layers of sheet material 52 in which pleat elements 74 have been
formed. This problem is even more acute when continuous web 53 is
not in a tubular configuration that can be easily inflated using
air. A similar problem with overlapped layers adhering to each
other occurs with continuous webs 53 that are highly blocked.
Consequently, in one embodiment of the present invention a means
for disengaging pleat elements 74 and/or separating overlapped
portions of sheet material 52 is provided. Preferably, continuous
web 53 is introduced into pre-opening or disengaging means 130
prior to sheet material 52 being introduced into bag-making machine
32.
[0046] Referring now to FIG. 6, disengaging means 130 in the form
of an opening bar 200 is illustrated as a static opening bar 201
having a static leading edge 203. The term "static" as used herein
means without movement or fixed in once place. In this embodiment,
static leading edge 203 is static relative to the other components
of disengaging means 130. Preferably, static leading edge 203 has a
substantially rounded configuration. One example of a static
opening bar 201 can include a support arm 205 that extends from and
is supported at only one end by a mount 209 in a cantilevered
manner. Extending outwardly from support arm 205 in a manner that
can be substantially horizontal is forward extension 207.
Preferably, forward extension 207 has a substantially cylindrical
or rounded leading edge 203.
[0047] As illustrated in FIG. 7, the cantilevered configuration of
static opening bar 201 allows insertion of static opening bar 201
between the overlapped portions of continuous web 53 of sheet
material 52. Preferably, static opening bar 201 can extend at least
partially across the width of sheet material 52. More preferably,
static opening bar 201 is smooth and, in one embodiment,
cylindrical allowing sheet material 52 to flow over an outer
surface thereof without encountering any sharp corners that would
disrupt the movement of sheet material 52. The forwardly extending
portion of static opening bar 201 is oriented substantially planar
with the path of sheet material 52 immediately upstream of static
leading edge 203. Static leading edge 203 encounters the overlapped
portions of sheet material 52 causing the overlapped portions to
separate from each other as static opening bar 201 is forced
between the overlapped portions. In this manner, static opening bar
201 is used to disengage pleat elements 74 (not shown) and separate
the overlapped portions of sheet material 52 as sheet material 52
rides over static opening bar 201. "Ride" as used herein means to
come into physical contact with or to be carried on something or
supported on or by the thing contacted. To "Ride" or "Riding"
indicates that an item has come into contact with or against the
thing over which it is being conveyed. As static leading edge 203
encounters the overlapped portions of sheet material 52, the
frictional forces engaging pleat elements 74 of sheet material 52
are overcome. As sheet material 52 rides on static opening bar 201,
the amount of force encountered as pleat elements 74 are disengaged
increases as the rate at which sheet material 52 rides over static
opening bar 201 increases.
[0048] In another embodiment of the present invention illustrated
in FIG. 8, separating the overlapped portions of sheet material 52
includes the use of a disengaging means 130 in the form of an
opening bar 200 that is a dynamic opening bar 202 having a dynamic
leading edge 204. Dynamic, as used herein, means that leading edge
204 is not static relative to the other components of disengaging
means 130. Dynamic leading edge 204 includes a pair of adjacent
idler rollers 206, 208 extending in a cantilevered manner from base
210. Adjacent, as used herein, means that the pair of idler rollers
206, 208 are placed next to each other with only a small interval
of space between them. Preferably, idler rollers 206, 208 are made
of a high strength, lightweight materials to resist deflection
forces such as, for example, aluminum, copper, carbon fiber or
titanium. For improved handling of sheet material 52 without
slippage and to assist in pulling continuous web 53 over idler
rollers 206, 208, preferably idler rollers 206, 208 have high
friction surfaces, such as with a plasma coating, for example, a
PC12036 plasma coat commercially available from Plasma Coatings of
TN, Inc. The axis of both idler rollers 206, 208 are preferably
aligned parallel to each other and idler rollers 206, 208 are
oriented transverse to the flow of sheet material 52.
Alternatively, idler rollers 206, 208 can be arranged in unaligned
configurations, for example, in an offset or nonparallel
configuration. Idler rollers 206, 208 revolve around axles that are
supported by high-speed bearings mounted in base 210. In this
embodiment, idler rollers 206, 208 form a dynamic leading edge 204
in that idler rollers 206, 208 rotate when contacted by sheet
material 52.
[0049] In a preferred embodiment of dynamic opening bar 202,
illustrated in FIG. 9, idler rollers 206, 208 can be supported by
high-speed bearings mounted in base 210 at one end and in end cap
230 at the other end. In this preferred embodiment, end cap 230 is
mounted on support arm 211 but alternatively, end cap 230 can be
made integral with support arm 211. Optionally, end cap 230 and
support arm 211 can be omitted as previously described. Support arm
211 is mounted on base 210 and spans between base 210 and end cap
230 just behind idler rollers 206, 208. The down stream trailing
edge 238 of support arm 211 is positioned so as not to interfere
with the flow of sheet material 52. Dynamic opening bar 202 extends
at least partially across the width of sheet material 52 in a
cantilevered manner. In this configuration, end cap 230 is
positioned to allow the C folded region of continuous web 53 to
ride upon outer surface 235.
[0050] As illustrated, idler rollers 206, 208 are constructed in a
configuration in which each idler roller 206, 208 is made up of two
separate intermediate rollers attached end to end. In particular,
idler roller 206 includes first intermediate roller 251 connected
end to end with a second intermediate roller 253. Similarly, idler
roller 208 is of the same configuration having a first intermediate
roller 252 connected end to end with a second intermediate roller
254. Bracket 250 is mounted between first intermediate rollers 251,
252 and second intermediate rollers 253, 254 forming a junction
between first intermediate rollers 251, 252 and second intermediate
rollers 253, 254. Bracket 250 is shaped somewhat like a "figure 8"
and is recessed from the outer diameter of each corresponding
roller 251, 252, 253, 254. In this manner, continuous web 53 of
sheet material 52 can ride over idler rollers 206, 208 without
contacting bracket 250. This configuration enables a wider dynamic
opening bar 202 for handling wider continuous webs 53.
[0051] An end cap 230 is configured with rounded edges to allow the
overlapped portion of sheet material 52 to pass over outer surface
235 without encountering any sharp edges. In one embodiment, end
cap 230 is substantially hemispherical at a forward portion and
tapers toward rear end 239 in a somewhat "tear drop" shape. End cap
230 is attached to support arm 211 using fasteners that pass
through fastener recesses 237 in outer surface 235. Preferably, end
cap 230 is aligned with opposite outer segments 216, 218 of idler
rollers 206, 208 to assure that no misalignment exists between the
ends of idler rollers 206, 208 and end cap 230. Any such
misalignment can result in tearing, ripping or disfiguring of sheet
material 52 as continuous web 53 rides over dynamic opening bar
202. Consequently, in a most preferred embodiment, end cap 230 is
slightly recessed below opposite outer segments 216, 218 of idler
rollers 206, 208 and a trailing edge 238 of support arm 211 does
not extend beyond rear end 239 of end cap 230.
[0052] As illustrated in FIG. 10, inner segments 219, 220 of the
set of idler rollers 206, 208 is the area where idler rollers 206,
208 come into close proximity with each other and opposite thereto
are outer segments 216, 218. Preferably, idler rollers 206, 208 are
positioned such that a plane containing their centerlines is
substantially perpendicular to the path of sheet material 52 just
upstream of dynamic opening bar 202 and idler rollers 206, 208 are
preferably, equal-distant from the plane defined by the path of
sheet material 52 just upstream of dynamic opening bar 202. The
overlapped portions of sheet material 52 ride over opposite outer
segments 216, 218 of idler rollers 206, 208 thus causing pleat
elements 74 to disengage and overlapped portions of sheet material
52 to separate from each other. Location "U" is the point at which
overlapped portions of sheet material 52 naturally begin
disengaging and separating from each other. The distance from
dynamic leading edge 204 to location U varies depending on the rate
at which continuous web 53 is traveling, and the tension of
continuous web 53 and adherence between the overlapped portions of
sheet material 52. Location U may oscillate in the machine
direction or in a cross direction. This oscillation can be toward
and away from dynamic leading edge 204 even when continuous web 53
is moving at a constant rate of speed.
[0053] Referring now to FIG. 11, in an alternative embodiment, end
cap 230 can have dimples 236 in outer surface 235 in order to
enable continuous web 53 of sheet material 52 to ride over end cap
230 with less friction than when outer surface 235 is smooth.
Preferably, dimples 236 in outer surface 235 are substantially
hemispherical. Fastener recesses 237 are also illustrated in outer
surface 235 of end cap 230. To assure that sheet material 52 and
the overlapped portions thereof smoothly flow as they ride over end
cap 230, end cap 230 preferably has a highly polished outer surface
235. Preferably outer surface 235 has a low coefficient of friction
such as with a plasma coating. One exemplary plasma coating is
PC-14015-02 plasma coating commercially available from Plasma
Coatings of TN, Inc.
[0054] In one preferred embodiment of the present invention as
illustrated in FIG. 12, dynamic opening bar 202 includes two sets
of adjacent idler rollers 206, 208, 212, 214. Second set of idler
rollers 206, 208 forming dynamic leading edge 204 (not shown) and
having end cap 230 are substantially the same as described in
reference to FIGS. 8 through 10. In this embodiment, first set of
adjacent idler rollers 212, 214 is added and positioned immediately
upstream of second set of idler rollers 206, 208 across the entire
width of continuous web 53. First set of adjacent idler rollers
212, 214 are supported by frame 221 having high-speed bearings
mounted on both ends of idler rollers 212, 214. Frame 221 can be
constructed of multiple components or as one unitary component.
Second set of idler rollers 206, 208 are preferably supported at
only one end by high-speed bearings mounted on base 210 in a
cantilevered manner and having end cap 230 affixed on the ends
opposite base 210. Additionally, support arm 211 is mounted on base
210 and spans between base 210 to end cap 230 just behind idler
rollers 206, 208. Alternatively, second set of idler rollers 206,
208 and support arm 211 can be mounted on a portion of frame 221
that is positioned so second set of idler rollers 206, 208 are just
behind first set of idler rollers 212, 214.
[0055] Now referring to FIG. 13, when disengaging means 130 is in
the form of two sets of adjacent idler rollers 206, 208, 212, 214,
the overlapped portions of sheet material 52 are disengageable as
they pass between first set of idler rollers 212, 214. Thereafter
the overlapped portions of sheet material 52 are disengaged and
separated from each other as each overlapped portion encounters and
moves toward opposite outer segments 216, 218 of second set of
idler rollers 206, 208. Sheet material 52 rides between first set
of idler rollers 212, 214 and then the overlapped portions of sheet
material 52 are pulled away from each other in a manner that
disengages pleat elements 74 and separates the overlapped portions
of sheet material 52 as sheet material 52 moves toward and rides on
second set of idler rollers 206, 208. Sheet material 52 rides on
inner segments 227, 228 of first set of idler rollers 212, 214 and
rides over outer segments 216, 218 of second set of idler rollers
206, 208. These two sets of adjacent idler rollers 206, 208, 212,
214 are configured such that first set of idler rollers 212, 214 is
spaced apart from second set of idler rollers 206, 208 to assure a
fixed location U for separation of the overlapped portions of sheet
material 52. In a preferred configuration, spacing Z between first
set of idler rollers 212, 214 and second set of idler rollers 206,
208 is less than about the distance between naturally occuring
location U and second set of rollers 206, 208.
[0056] In still another embodiment of the present invention as
illustrated in FIG. 14, dynamic opening bar 202 is shown including
an end cap 230 at either end. Often continuous webs 53 of sheet
material 52 are extruded and blown and further processed without
cutting of continuous web 53 and without folding to overlap any
portions of continuous web 53. In these instances, continuous web
53 remains in a substantially tubular configuration without any
open edges. During processing, overlapped portions are formed
simply by collapse of the tubular walls. Consequently, there are no
open edges to insert and maintain the support of disengaging means
130 in even a cantilevered manner. In order to separate such
continuous webs 53 an alternative embodiment of disengaging means
130 is utilized. Dynamic opening bar 202 includes a pair of idler
rollers 206, 208 that form dynamic leading edge 204. The axis of
both idler rollers 206, 208 are aligned parallel to each other and
idler rollers 206, 208 are positioned adjacent to each other. Idler
rollers 206, 208 revolve around axles that are supported by end
caps 230. Opposing end caps 230 are used to support idler rollers
206, 208 at both ends of idler rollers 206, 208. Support arm 211
spans between both opposing end caps 230 and is positioned just
behind idler rollers 206, 208. Each end cap 230 is attached to
support arm 211 at opposite ends of support arm 211 using fasteners
that pass through fastener recesses 237 in outer surface 235 in the
same manner as previously discussed. During use, this configuration
of dynamic opening bar 202 can be wholly surrounded by overlapped
portions of sheet material 52.
[0057] Now referring to FIG. 15, dynamic opening bar 202 is capable
of movement between upper support rollers 280, 282, 284, 286 and
lower support rollers 281, 283, 285, 287 which form a cage 290
around dynamic opening bar 202 so that dynamic opening bar 202 is
captured within cage 290. In this embodiment, dynamic opening bar
202 is illustrated as being horizontally disposed within cage 290.
Upper support rollers 280, 282, 284 have corresponding lower
support rollers 281, 283, 285 that are preferably arranged in pairs
spaced longitudinally adjacent and on opposite sides of dynamic
opening bar 202. At a forward end of cage 290 are positioned a set
of adjacent support rollers 280, 281. Support roller 280 is aligned
in an upper position while support roller 281 is aligned in a lower
position. Forward support rollers 280, 281 are spaced apart to
allow continuous web 53 to pass between them while preventing the
forward migration of dynamic opening bar 202. At this forward
location dynamic leading edge 204, idler rollers 206, 208 and
support rollers 280, 281 are all positioned the same relative to
each other as the two sets of adjacent idler rollers illustrated in
FIG. 12. Positioned just behind and outboard of idler rollers 206,
208 and outboard of a mid-portion of dynamic opening bar 202 are
middle support rollers 282, 283. Middle support rollers 282, 283
are positioned on opposite sides of dynamic opening bar 202 in
order to maintain dynamic opening bar 202 in its horizontal
position parallel to the flow of continuous web 53. In a preferred
configuration two sets of middle support rollers 282, 283, 286, 287
are provided to maintain dynamic opening bar 202 in its horizontal
position. Middle support rollers 282, 286 are spaced apart adjacent
an upper side of dynamic opening bar 202 while middle support
rollers 283, 287 are spaced apart adjacent a lower side of dynamic
opening bar 202. Rear support rollers 284, 285 are positioned to
assure dynamic opening bar 202 does not migrate rearward from its
desired position. In this manner dynamic opening bar 202 is
captured within cage 290.
[0058] In order to insert and extract dynamic opening bar 202 from
within cage 290, middle support rollers 282, 286 in the upper
position can be removed so that dynamic opening bar 202 can be
lifted out of cage 290. Alternatively, middle support rollers 282,
286 in the upper position can be attached to a hinged frame. In
this manner, the hinged frame could be opened moving middle support
rollers 282, 286 away from dynamic opening bar 202 for maintenance
or other purposes. For example, during start up of continuous web
53 dynamic opening bar 202 can be inserted within the tubular walls
when middle support rollers 282, 286 are moved out of position.
Middle support rollers 282, 286 are moved back into position in
order to maintain dynamic opening bar 202 captive.
[0059] In this configuration, continuous web 53 of sheet material
52 can wholly enclose dynamic opening bar 202 which floats within
the tubular walls of continuous web 53. The overlapped portions of
sheet material 52 ride between forward support rollers 280, 281 of
cage 290 and over opposite outer segments 216, 218 of idler rollers
206, 208 on dynamic opening bar 202 thus causing pleat elements 74
to disengage and overlapped portions of sheet material 52 to
separate from each other. In this manner, continuous web 53 is
threaded between dynamic opening bar 202 and cage 290. The
overlapped portions of continuous web 53 of sheet material 52 can
ride over opposite sides of dynamic opening bar 202.
[0060] Referring now to FIG. 16 in which is illustrated, an
alternative dynamic opening bar 202 within cage 290 with continuous
web 53 threaded between dynamic opening bar 202 and cage 290. In
this alternative configuration of dynamic opening bar 202, an
additional pair of upper idler rollers 292, 294 are positioned on
an upper portion of dynamic opening bar 202 down stream of idler
roller 206 and an additional pair of lower idler rollers 293, 295
are positioned on a lower portion of dynamic opening bar 202 down
stream of idler roller 208. Upper idler rollers 292, 294 and lower
idler rollers 293, 295 can be mounted at both ends in end caps 230.
Upper idler rollers 292, 294 and lower idler rollers 293, 295
assist in supporting and guiding continuous web 53 of sheet
material 52 as continuous web 53 is threaded between middle support
rollers 282, 286 that are spaced adjacent an upper side of dynamic
opening bar 202 and middle support rollers 283, 287 that are spaced
adjacent a lower side of dynamic opening bar 202. Upper idler
rollers 292, 294 and lower idler rollers 293, 295 cooperate with
corresponding upper middle support rollers 282, 286 and lower
middle support rollers 283, 287 respectively to assist in
maintaining the smooth flow of continuous web 53 as continuous web
rides over dynamic opening bar 202 while also maintaining dynamic
opening bar 202 in a horizontal position. Optionally, upper idler
rollers 292, 294 and lower idler rollers 293, 295 can be spherical
ball bearings instead of cylindrical rollers.
[0061] In another alternative embodiment of the present invention
as illustrated in FIG. 17, the step of separating the overlapped
portions of sheet material 52 (not shown) includes the use of a
disengaging means 130 in the form of a suction means 550. Suction
means 550 is used to disengage and separate the overlapped portions
of sheet material 52 as sheet material 52 rides on suction means
550. In this embodiment, suction means 550 can be an integral part
of forming roller 502, 504 and can include apertures 575 in at
least one of forming rollers 502, 504. A plurality of small
apertures 575 on each tooth 507 are connected with a vacuum
manifold 570 through passageways internal to forming rollers 502,
504. Openings 576 are depicted on a faceplate at one end of rollers
502, 504. Vacuum manifold 570 is attached to openings 576 in a
manner that allows rotation of rollers 502, 504. As sheet material
52 passes between forming rollers 502 and 504 wherein pleat
elements 74 are formed, suction is also applied to the overlapped
portions of sheet material 52 through apertures 575. A vacuum,
indicated generally by arrow "V", is created and suction applied
through vacuum manifold 570 extending through openings 576 into
passageways and apertures 575 in teeth 507. This vacuum allows a
suction force to be applied to the overlapped portions of sheet
material 52 thereby disengaging pleat elements 74 immediately after
they are formed by forming rollers 502 and 504. In particular, the
suction applied through apertures 575 pulls the overlapped portions
of sheet material 52 apart. In that manner, pleat elements 74 are
disengaged and the overlapped portions of sheet material 52 are
separated.
[0062] In yet another alternative embodiment, as illustrated in
FIG. 18, suction means 550 can be in the form of opposing plenums
579 that are situated in close proximity to sheet material 52 just
after continuous web 53 passes through forming apparatus 500. A
vacuum, as indicated generally by arrows "V", can be applied
through each plenum 579 sufficient to pull the overlapped portions
of continuous web 53 of sheet material 52 apart in order for pleat
elements 74 to become disengaged from each other. The vacuum also
provides sufficient suction to separate the overlapped portions of
sheet material 52 from each other. After pleat elements 74 are
disengaged and overlapped portions of sheet material 52 are
separated from each other, continuous web 53 can be introduced to
the next converting station through transport rollers 123.
[0063] In an alternative embodiment of the present invention,
disengaging means 130 can be in the form of an air knife used to
disengage and separate overlapped portions of sheet material 52.
Air knives are well known by those of ordinary skill in the art in
that air can be blown between the overlapped portions of sheet
material 52 to disengage pleat elements 74. In still another
alternative embodiment, disengaging means 130 can include an air
bearing. For example, an air bearing can be a surface disposed
between the overlapped portions of sheet material 52 and wherein a
layer of air is introduced onto the surface such that sheet
material 52 rides on the layer of air. Air bearings of this type
are well known in the art. Alternatively, such surfaces can utilize
any gas, liquid, gel or flowable solid to form the layer on which
sheet material 52 traverses including, for example, nitrogen, oil,
glycerol, graphite, grease, water, and any combinations
thereof.
[0064] Referring back to FIG. 2, optionally, a pair of opposing
gussets 54 can be formed in continuous web 53 at an optional
converting station using methods well known in the art. Such an
optional gusseting station 150 is illustrated as being just before
bag-making machine 32 but alternatively gussets can be inserted
into continuous web 53 in various other sequences as is known by
those of ordinary skill in the art.
[0065] The processing of continuous web 53 can continue by
introducing continuous web 53 into a bag-making machine 32.
Continuous web 53 passes through bag-making machine 32 to form
flexible bag 10 including a strainable network having at least two
visually distinct regions. For example, flexible bags 10 can be
formed from continuous web 53 such that said continuous web 53 has
a perforated or tear section adjacent to a sealed section which
extends transversely across a width of said continuous web 53. A
perforated section adjacent to sealed section can be spaced apart
longitudinally from a next pair of similarly configured perforated
section and sealed section. One such method of forming such a
flexible bag 10 is disclosed in U.S. Pat. No. 4,867,735 issued to
Wogelius on Sep. 19, 1989. After flexible bags 10 are incorporated
into continuous web 53, continuous web 53 can be introduced to the
next converting station through transport rollers 123.
[0066] Alternatively, converting station, just ahead of bag-making
machine 32 can be a calender station 150 used to process continuous
web 53 by flattening or pressing together at least a portion of
continuous web 53 to improve bonding or sealing capabilities of
sheet material 52. In particular, discrete areas of continuous web
53 should stay in close contact with each other to insure effective
sealing, bonding and forming of sheet material 52. Consequently,
continuous web 53 can be pretreated by uniformly flattening pleat
elements 74 via the application of pressure and heat upon sheet
material 52. To form these discrete portions onto continuous web 53
at the required locations, a set of rolls can be used. Continuous
web 53 passes between smooth rollers as they are pressed into
contact with each other to flatten sheet material 52. In a
preferred embodiment, smooth rollers are heated using steam or some
other method of heating smooth rollers. As sheet material 52 passes
between smooth rollers, pleat elements 74 of second region 66
become substantially planar with the un-deformed first region 64.
Smooth rollers flatten or collapse pleat elements 74 while not
changing the functional structure of the strainable network. After
continuous web 53 passes through this converting station,
continuous web 53 can be introduced to the next converting station
through transport rollers 123.
[0067] The processing of continuous web 53 continues as continuous
web 53 is introduced to a folding station 133. Continuous web 53
passes through folding station 133 that is preferably positioned
after bag-making machine 32. Folding of continuous web 53 is in a
manner that reduces the transverse width of continuous web 53 by
overlapping portions of continuous web 53 upon each other. Folding
bars 33 comprise folding station 133 and are used in a manner known
by those of ordinary skill in the art. After the folding is
completed, continuous web 53 can be introduced to the next
converting station through transport rollers 123.
[0068] The processing of continuous web 53 continues as continuous
web 53 is introduced into rewinding station 111 that is preferably
positioned after all of the processing of continuous web 53 is
completed. Rewinding station winds continuous web 53 into rolls 11
of flexible bags 10. These flexible bags 10 are wound in a manner
such that upon unwinding a section of continuous web 53 allows
flexible bags 10 to be severed from each other for individual use.
Rewinding can include continuous web 53 being wound around a
cylindrical core to form rolls 11 of flexible bags 10. Cylindrical
cores can be utilized or omitted using winding methods that are
known in the art.
[0069] Alternatively, once the desired sheet materials 52 are
manufactured, comprising all or part of the components to be
utilized for bag body 20, flexible bag 10 may be constructed in any
known and suitable fashion such as those known in the art for
making such flexible bags 10 in a commercially available form.
Heat, mechanical, ultrasonic, or adhesive-sealing technologies may
be utilized to join various components or elements of flexible bag
10 to themselves or to each other. In addition, bag body 20 may be
folded or bonded to construct flexible bag 10 from a single
continuous web 53 or a singular discrete piece of sheet material 52
or any combinations thereof.
[0070] A further alternative embodiment of the present invention
can include taking a roll 11 of previously formed disposable bags
or a roll 11 of sheet material 52 and unwinding roll 11 and
introducing continuous web 53 from such roll 11 into a process as
previously described above. Optionally many additional processing
steps can be added either before or after the forming or separating
of flexible bags 10 as described herein. Other processing steps can
be completed such an alternative converting station illustrated as
processing station 127 which can include, for example, printing
labels, additional folding, cutting, forming or sealing or any
combination of these or other converting processes.
[0071] While the process for making flexible bags 10 from a sheet
material 52 has been described in a particular order, it is known
that these steps can be performed in various orders. For example, a
preferred sequencing of the process for making such flexible bags
10 can be to introduce the raw material into an extruder and then
blow or cast form continuous web 53. Thereafter, continuous web 53
can be processed through a number of converting station or,
alternatively, continuous web 53 of sheet material 52 can be wound
onto a roll 11 at any stage during the process. Such a roll 11 of
sheet material 52 can then be set aside or introduced into any step
of the process desirable. A particularly preferred process involves
taking a pre-existing roll 11 of overlapped sheet material 52 and
introducing this sheet material 52 into closure station 160. Next
sheet material 52 can be introduced into forming apparatus 500 in
order to form pleat elements 74 in sheet material 52. Then, sheet
material 52 is introduced into separating station 130 in order to
disengage pleat elements 74 and to separate the overlapped portions
of sheet material 52. Thereafter, sheet material 52 is introduced
into bag-making machine 32 to make flexible bags 10.
[0072] While particular examples and exemplary methods to introduce
continuous web 53 and sheet material 52 have been described,
numerous variations of such examples are well know in the art. For
example, continuous web 53 or an individual or discrete sheet of
precut sheet material 52 having a single-ply can be introduced into
forming apparatus 500 and then folded in a folding station 133 and
introduced into bag-making machine 32. Alternatively, multiple
continuous webs 53 or multiple discrete sheets of sheet material 52
in a flat configuration can be introduced into forming apparatus
500 and then folded in a folding station 133 and introduced into
bag-making machine 32. Alternatively, the overlapped portions can
be multiple continuous webs 53 or multiple discrete sheets of sheet
material 52 sealed at one longitudinal edge to form bottom fold 22.
Another alternative can be the introduction of at least one or more
continuous webs 53 or discrete sheets of sheet material 52 that are
overlapped upon themselves and having pleat elements 74 formed
therein that are introduced into disengaging means. Yet another
alternative method of introducing continuous webs 53 can be one or
more tubes 51 that have pleat elements 74 formed therein can be
introduced into disengaging means 130. Still another alternative
can be to introduce one or more tubes 51 having pleat elements 74
formed therein that can then be cut, disengaged, separated, folded
and then introduced to bag-making machine 32. As illustrated herein
it should be apparent to those of ordinary skill in the art that
the converting stations and steps described herein can be sequenced
in various orders other than those described herein without any
undue experimentation.
[0073] FIG. 19 illustrates the results of one embodiment of the
present invention, a roll 11 of flexible bags 10. In this
embodiment, multiple flexible bags 10 are joined in end-to-end
fashion forming continuous web 53 from which a multiplicity of
individual flexible bags 10 can be separated. In the embodiment
illustrated, sheet material 52 has a perforation or frangible zone
25 between sealed edge 21 and sealed edge 23. Closure means 30 is
shown in the form of a draw tape 31 which can be attached by
inserting a strip of draw tape 31 into the continuous web 53 of
sheet material 52 through a hem or channel 34 formed along top edge
28. A scalloped area 17 can also be cut out of top edge 28 to
provide access to a portion of draw tape 31. Since flexible bags 10
in their pre-use condition may be externally smaller than typical
bags of lesser stretch capability, the dimensions of roll 11 may be
likewise smaller since flexible bags 10 can expand in use to the
desired size. Such a reduced size roll 11 may be particularly
useful for dry cleaning bags.
[0074] In yet still another converting station, continuous web 53
of sheet material 52 can be divided, separated, severed or torn
apart into individual flexible bags 10 at finishing station 161.
Dividing continuous web 53 of sheet material 52 into individual
flexible bags 10 can be accomplished by tearing each flexible bag
10 away from continuous web 53 along frangible zone 25.
Alternatively, each flexible bag 10 can be separated from
continuous web 53 by cutting across the width of continuous web 53
during a severing and sealing step at the location of frangible
zone 25. In particular, after flexible bags 10 have been formed, a
sever-sealing device can be provided that creates sealed edge 21
and sealed edge 23 using heat or some other means while
simultaneously severing or cutting continuous web 53 between sealed
edge 21 and sealed edge 23 along frangible zone 25. Cutting
continuous web 53 in this manner separates individual flexible bags
10 from the remainder of continuous web 53. Flexible bags 10 can
then be stacked together or folded in an interleaved manner. This
allows stack 129 of interleaved flexible bags 10 to be placed into
a package from which a consumer may extract each individual
flexible bag 10 one by one without having to tear one flexible bag
10 from another.
[0075] While particular embodiments of the present invention have
been illustrated and described, it would be obvious to those
skilled in the art that various additional changes and
modifications can be made without departing from the spirit and
scope of the present invention. It is therefore intended to cover
in the appended claims all such changes and modifications that are
within the scope of this invention.
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