U.S. patent application number 13/247560 was filed with the patent office on 2012-09-06 for polymeric bag with elastic drawtape.
This patent application is currently assigned to Trans Western Polymers, Inc.. Invention is credited to Matthew Kim, Gary Price, John Woelfle.
Application Number | 20120224793 13/247560 |
Document ID | / |
Family ID | 46753345 |
Filed Date | 2012-09-06 |
United States Patent
Application |
20120224793 |
Kind Code |
A1 |
Kim; Matthew ; et
al. |
September 6, 2012 |
POLYMERIC BAG WITH ELASTIC DRAWTAPE
Abstract
A manufacturing method for producing a plurality of polymeric
drawtape bags, the method including: a) dispensing a film of
polymeric pliable material; b) producing a web of folded and sealed
polymeric panels from the film, the web including a plurality of
polymeric bags having a pair of drawtapes added into a pair of hems
proximate a bag opening with a series of notches produced near
lateral edges of each of the hems exposing the drawtapes with a
series of lateral seals applied to the exposed drawtapes within the
notches; c) measuring a relative placement of the series of notches
with respect to the seals; and d) providing feedback to a notch
production system to improve placement of the series of lateral
seals of the exposed drawtapes within the notches by accurately
locating the series of notches produced along the web.
Inventors: |
Kim; Matthew; (Tracy,
CA) ; Price; Gary; (Mountain Top, PA) ;
Woelfle; John; (Hazleton, PA) |
Assignee: |
Trans Western Polymers,
Inc.
Livermore
CA
|
Family ID: |
46753345 |
Appl. No.: |
13/247560 |
Filed: |
September 28, 2011 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
61449591 |
Mar 4, 2011 |
|
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|
Current U.S.
Class: |
383/75 ; 493/210;
493/243 |
Current CPC
Class: |
B31B 70/946 20170801;
B31B 70/148 20170801; B31B 70/00 20170801; B31B 2155/00 20170801;
B65D 33/28 20130101; B31B 70/8135 20170801; B31B 2160/10 20170801;
B31B 70/006 20170801; B31B 2155/003 20170801 |
Class at
Publication: |
383/75 ; 493/210;
493/243 |
International
Class: |
B65D 33/28 20060101
B65D033/28 |
Claims
1. A drawtape bag comprising: a body including a pair of pliable
opposing polymeric body panels joined together with a pair of
lateral body seals along a pair of opposing lateral sides and a
bottom bridging and closing said pair of pliable opposing polymeric
body panels producing a polymeric bag with an open mouth end at a
top end, said body panels each forming a hem extending along said
open mouth end, each said hem including a pair of lateral notches
at said opposing lateral sides; and a pair of pliable polymeric
elastomeric drawtapes moveably disposed without attachment within
said hems, one drawtape within each hem wherein opposing lateral
sides of said pair of drawtapes are exposed within said notches and
joined together with a pair of lateral drawtape seals to form a
single closed drawtape loop extending around a perimeter of said
open mouth end wherein said single closed drawtape loop is
configured to be drawn through one or both of said pair of lateral
notches to close said open mouth end; wherein said lateral notch
has a length in a direction along said hem about 1.625 inches or
less wherein said body has a width about 24 inches or less and a
length about 27 inches or greater.
2. The drawtape bag of claim 1 wherein a drawtape seal width of
said lateral drawtape seal is greater than a lateral body seal
width of said lateral body seal.
3. The drawtape bag of claim 2 wherein said drawtape seal width, as
measured as a distance extending into said body from a lateral
edge, is at least 0.5 inches greater than said lateral body seal
width.
4. A drawtape bag comprising: a body including a pair of pliable
opposing polymeric body panels joined together with a pair of
lateral body seals along a pair of opposing lateral sides and a
bottom bridging and closing said pair of pliable opposing polymeric
body panels producing a polymeric bag with an open mouth end at a
top end, said body panels each forming a hem extending along said
open mouth end, each said hem including a pair of lateral notches
at said opposing lateral sides; and a pair of pliable polymeric
elastomeric drawtapes moveably disposed without attachment within
said hems, one drawtape within each hem wherein opposing lateral
sides of said pair of drawtapes are exposed within said notches and
joined together with a pair of lateral drawtape seals to form a
single closed drawtape loop extending around a perimeter of said
open mouth end wherein said single closed drawtape loop is
configured to be drawn through one or both of said pair of lateral
notches to close said open mouth end; wherein said lateral notch
has a length in a direction along said hem about 1 inch or less
wherein said body has a width about 23 inches or less and a length
about 28.25 inches or greater.
5. The drawtape bag of claim 4 wherein a lateral drawtape seal
width of said lateral drawtape seal is about equal to a lateral
body seal width of said lateral body seal.
6. The drawtape bag of claim 5 wherein said seals are about 0.125
inches wide.
7. A method of manufacturing a drawtape bag, comprising the steps
of: a) directing a pair of overlying polymeric film panels in a
machine direction wherein said pair of polymeric film panels are
joined together at a bottom edge and open at a top edge opposite of
said bottom edge to form a single polymeric film, with the panels
being separable from each other along a mouth end formed opposite
the bottom edge; b) producing a pair of hems along said top edges
of said film panels of said single polymeric film; c) producing
drawtape notches in each hem of said pair of hems at regular
distance intervals corresponding to a desired width of the drawtape
bags; d) adding a pair of pliable polymeric drawtape into said pair
of hems, a drawtape disposed into each hem; e) sealing said panels
to each other using body seal structures generally transverse to
the machine direction to create individual drawtape bags; and f)
sealing said drawtapes to each other using drawtape seal structures
within said drawtape notches to form, for the drawtape bag, a
single closed drawtape loop disposed around a perimeter of said
mouth end.
8. The method of claim 7 wherein said drawtape seal structures are
wider than said body seal structures.
9. The method of claim 7 wherein said drawtape seal structures are
about equal to said body seal structures.
10. The method of claim 7 further comprising the steps of: g)
perforating each said seal structure generally transverse to said
machine direction to define the drawtape bag between successive
perforations.
11. The method of claim 10 further comprising the steps of: i)
imaging said successive perforations in relation to a trailing edge
of associated successive drawtape notches to provide a series of
notch registration signals; and j) adjusting said forming step c)
responsive to said series of notch registration signals.
12. A manufacturing system for producing polymeric drawtape bags,
the system comprising: a plurality of manufacturing stations to
dispense polymeric pliable material and to produce a web of folded
and sealed polymeric panels forming a plurality of polymeric bags
having a pair of drawtapes added into a pair of hems proximate a
bag opening with a series of notches produced near lateral edges of
each of said hems exposing said drawtapes with a series of lateral
seals applied to said exposed drawtapes within said notches; and a
notch registration system, coupled to one or more stations of said
plurality of manufacturing stations, measuring a relative placement
of said series of notches with respect to said seals and providing
feedback to a notch production system of said plurality of
manufacturing stations to improve placement of said series of
lateral seals of said exposed drawtapes within said notches by
accurately locating said series of notches produced along said
web.
13. A manufacturing method for producing a plurality of polymeric
drawtape bags, the method comprising the steps of: a) dispensing a
film of polymeric pliable material; b) producing a web of folded
and sealed polymeric panels from said film, said web including a
plurality of polymeric bags having a pair of drawtapes added into a
pair of hems proximate a bag opening with a series of notches
produced near lateral edges of each of said hems exposing said
drawtapes with a series of lateral seals applied to said exposed
drawtapes within said notches; c) measuring a relative placement of
said series of notches with respect to said seals; and d) providing
feedback to a notch production system to improve placement of said
series of lateral seals of said exposed drawtapes within said
notches by accurately locating said series of notches produced
along said web.
Description
CROSS REFERENCE TO RELATED APPLICATIONS
[0001] This application claims the benefit of U.S. Provisional
Application No. 61/449,591, filed 4 Mar. 2011, the contents of
which are hereby expressly incorporated in its entirety by
reference thereto for all purposes.
BACKGROUND OF THE INVENTION
[0002] The present invention relates generally to polymeric bags,
and more specifically, but not exclusively, to polymeric elastic
drawtape trash bags and methods of their manufacture.
[0003] Polymeric trash bags are a common household product and have
been so for many years. Common trash bags include a variety of
polymeric materials, sizes, thicknesses, colors, counts, and
closure formats. Polymeric trash bags are used not only for
collection, containment, and disposal of trash and garbage, but
also for long term storage of items such as clothing and the like.
With the constant growing use of polymeric trash bags,
manufacturers are always researching new manufacturing materials
and methods to enhance consumer experience while at the same time
providing options to generate less waste, enhance sustainability,
and improve profitability.
[0004] The closure method of polymeric trash bags differ in design.
A common polymeric bag design can be as simple two bag panels
sealed along opposing sides creating what is commonly called an
`open top` bag. This style of bag is inserted into a trash
container with the upper edges of the bag rolled over the container
rim to provide a means to hold the bag to the container. When the
bag is filled, the bag is removed by pulling the bag from the trash
container, spinning the top of the bag shut, and then applying a
twist-tie (or other closure system) to hold the bag shut. Two
specific inherent frustrations apply to this design: (1) The bags
tend to fall into the trash container while filling as the bag does
not provide a feature to secure the bag to the top of the
container; and (2) Consumers have expressed concern that the tie
devise sometimes become lost thus requiring the consumer to (try
to) tie a knot in the bag which can be difficult in the event there
is not enough material remaining in the bag body once filled.
[0005] To overcome the `open top` bag closure frustrations,
manufacturers developed a polymeric trash bag commonly called
"drawtape" and/or "drawstring" trash bags. A typical drawtape (or
drawstring) bag feature includes a pair of polymeric strips
enclosed in a formed hem in the top of each bag panel. When
polymeric drawtape trash bags are used by a consumer, the drawtape
feature provides a method for removal of the trash bag from the
container as the drawtape acts as a handle for gripping and lifting
the bag. Once the bag has been lifted from the container, the
polymeric drawtape strips can be tied to each other to secure the
bag shut and then provide a carrying mechanism to transport the bag
to its desired location. Throughout the existence of drawtape style
polymeric trash bags, this design style has become a common product
used in households and business.
[0006] Because of the variety of polymeric drawtape trash bag sizes
and trash container sizes, a common unsatisfactory experience
expressed by consumers when using a polymeric drawtape trash bag in
a container is the bags do not always remain secured to the top of
the container consequently when the bag is filled, the bag tends to
pull/drop inward into the container which then results in trash and
garbage not completely being captured by the bag thus the trash
container is subject to becoming soiled and unsanitary. When this
condition occurs, the consumer has to reach into the container and
through trash to locate the top of the trash bag--more specifically
locate and grip the drawtape pull feature. When the bag fails to
remain in place, the outcome defeats the purpose of using a bag to
provide a barrier between the trash and trash container.
[0007] Consumers are always seeking the latest and greatest feature
to enhance a product experience. With this in mind, manufacturers
began researching new materials and methods that offer stretchable
drawtape strips in trash bags. The advantage of a stretchable
drawtape is simple--when the top section of a polymeric drawtape
trash bag is folded over the container rim, the bag tends to stay
in place thus allowing the bag panels to act as a liner overcoming
the need for consumers having to reach into a trash container to
reattach the bag to the container rim and having to clean the
container interior.
[0008] Elastic drawtape polymeric trash bags are manufactured by
several companies all of which utilize a variety of manufacturing
techniques, methods, materials, and processes. Following are two
product description examples and corresponding consumer
experiences.
[0009] 1. One product design utilizes an elastic polymeric drawtape
enclosed in individual hems along the top of the polymeric trash
bag. A dedicated heat seal attaches the drawtape ends to the bag
hem panels on each side of the bag. The dedicated drawtape seals
extend further into the bag body panel width than the main bag
panel seals thus creating a reduced bag opening size
(circumference) when measured against the bag panel interior size
(circumference). This reduced opening provides a means to secure
the bag to a container rim. This bag design includes a centralized
semicircular cutout in the top of the bag to allow bag closure when
the drawtape strips are pulled through the cutouts. A descriptive
reference for this product is found in US Pub No. 2010/0111452-A1
entitled REDUCED OPENING ELASTIC DRAWSTRING BAG filed 30 Oct.
2008.
[0010] This product design requires the consumer to stretch the
upper portion of the bag body hem panels while in the same motion
stretching the elastic drawtape strips in order to secure the top
of the bag around the container rim. Stretching both the bag body
hem panels and elastic drawtape in one motion requires additional
pulling force and strength from the consumer when compared to
product #2 described in the next section below. Furthermore, when
having to pull the drawtape strips from a centralized hole, the
experience can lead to cinching/gathering of the bag hem panels
upon closure thus making it difficult to fully close the bag.
Depending on the consumer, products that require an extra force to
use a trash bag may lead to frustration and tendency to purchase
other products.
[0011] 2. One product design utilizes a polymeric drawtape material
that is not of an elastic material in design however the drawtape
strips have been designed in a manner to include looped sections
which have an elastic adhesive strip attached to the looped
sections. The elastic adhesive strips are adhered to the polymeric
drawtape strips to allow the drawtape to react in an elastic manner
when pulled. There is one drawtape strip enclosed in each of the
two individual bag body hems along the top of the polymeric bag. In
this design, the bag has a pair of notch cutouts on the top of the
bag with one located on each side of the bag. The drawtape is
sealed to each other (strip 1 to strip 2) while remaining separate
of being sealed to the bag body panels and hem sections. The notch
cutouts allow the drawtape to extend outside of the bag body
panels. This design requires less force when the drawtape is pulled
by the consumer as the consumer only has to stretch the drawtape
strips around the container rim to secure the bag to the container.
A descriptive reference for this product is found in U.S. Pat. No.
6,059,458 entitled ELASTIC TOP DRAWTAPE BAG AND METHOD OF
MANUFACTURING THE SAME filed 5 Feb. 1999.
[0012] Depending on the consumer and pulling force exerted during
closure, the adhesive strips on the looped drawtape can break free
from the non-elastic drawtape strips thus rendering the stretchable
capability unusable. Furthermore, it was discovered during visual
product analysis that the notch proximity to the edge of the bag
panels varied in dimension and the shape was of a rectangular shape
vs. a half semicircular shape as noted in the aforementioned patent
document drawings. Depending on the pulling force exerted on the
bag during closure, the notches tend to enlarge thus creating
openings at the drawtape closure points which could subject the bag
contents to pests and other environmental conditions.
[0013] What is needed is an improved design and manufacturing
method for polymeric elastic drawtape bags that addresses the
limitations of existing bags.
BRIEF SUMMARY OF THE INVENTION
[0014] Disclosed is an improved design and manufacturing method for
polymeric elastic drawtape bags that addresses the limitations of
existing bags. The following summary of the invention is provided
to facilitate an understanding of some of technical features
related to polymeric bags and manufacturing processes thereof, and
is not intended to be a full description of the present invention.
A full appreciation of the various aspects of the invention can be
gained by taking the entire specification, claims, drawings, and
abstract as a whole.
[0015] A drawtape bag includes a body having a pair of pliable
opposing polymeric body panels joined together with a pair of
lateral body seals along a pair of opposing lateral sides and a
bottom bridging and closing the pair of pliable opposing polymeric
body panels producing a polymeric bag with an open mouth end at a
top end, the body panels each forming a hem extending along the
open mouth end, each the hem including a pair of lateral notches at
the opposing lateral sides; and a pair of pliable polymeric
elastomeric drawtapes moveably disposed without attachment within
the hems, one drawtape within each hem wherein opposing lateral
sides of the pair of drawtapes are exposed within the notches and
joined together with a pair of lateral drawtape seals to form a
single closed drawtape loop extending around a perimeter of the
open mouth end wherein the single closed drawtape loop is
configured to be drawn through one or both of the pair of lateral
notches to close the open mouth end; wherein the lateral notch has
a length in a direction along the hem about 1.625 inches or less
wherein the body has a width about 24 inches or less and a length
about 27 inches or greater.
[0016] A method of manufacturing a drawtape bag includes a)
directing a pair of overlying polymeric film panels in a machine
direction wherein the pair of polymeric film panels are joined
together at a bottom edge and open at a top edge opposite of the
bottom edge to form a single polymeric film, with the panels being
separable from each other along a mouth end formed opposite the
bottom edge; b) producing a pair of hems along the top edges of the
film panels of the single polymeric film; c) producing drawtape
notches in each hem of the pair of hems at regular distance
intervals corresponding to a desired width of the drawtape bags; d)
adding a pair of pliable polymeric drawtape into the pair of hems,
a drawtape disposed into each hem; e) sealing the panels to each
other using body seal structures generally transverse to the
machine direction to create individual drawtape bags; and f)
sealing the drawtapes to each other using drawtape seal structures
within the drawtape notches to form, for the drawtape bag, a single
closed drawtape loop disposed around a perimeter of the mouth
end.
[0017] A manufacturing system for producing polymeric drawtape
bags, the system including a plurality of manufacturing stations to
dispense polymeric pliable material and to produce a web of folded
and sealed polymeric panels forming a plurality of polymeric bags
having a pair of drawtapes added into a pair of hems proximate a
bag opening with a series of notches produced near lateral edges of
each of the hems exposing the drawtapes with a series of lateral
seals applied to the exposed drawtapes within the notches; and a
notch registration system, coupled to one or more stations of the
plurality of manufacturing stations, measuring a relative placement
of the series of notches with respect to the seals and providing
feedback to a notch production system of the plurality of
manufacturing stations to improve placement of the series of
lateral seals of the exposed drawtapes within the notches by
accurately locating the series of notches produced along the
web.
[0018] A manufacturing method for producing a plurality of
polymeric drawtape bags, the method including: a) dispensing a film
of polymeric pliable material; b) producing a web of folded and
sealed polymeric panels from the film, the web including a
plurality of polymeric bags having a pair of drawtapes added into a
pair of hems proximate a bag opening with a series of notches
produced near lateral edges of each of the hems exposing the
drawtapes with a series of lateral seals applied to the exposed
drawtapes within the notches; c) measuring a relative placement of
the series of notches with respect to the seals; and d) providing
feedback to a notch production system to improve placement of the
series of lateral seals of the exposed drawtapes within the notches
by accurately locating the series of notches produced along the
web.
[0019] Although the production lines used to manufacture polymeric
drawtape trash bags utilize industry standard technologies, the
process has an inherent variation in the placement of the drawtape
notch cutout. The variation is partially the result of the pliable
characteristic of the film and web tension variables. One component
of a bag manufacturing line is referred to as "The Dancer" (a
downstream component) also contributes to notch placement variation
as the Dancer tends to oscillate in response to film tension
variables thus offsetting the notch placement. One feature of our
invention includes technologies to control and limit the notch
placement variations.
[0020] Other features, benefits, and advantages of the present
invention will be apparent upon a review of the present disclosure,
including the specification, drawings, and claims.
BRIEF DESCRIPTION OF THE DRAWINGS
[0021] The accompanying figures, in which like reference numerals
refer to identical or functionally-similar elements throughout the
separate views and which are incorporated in and form a part of the
specification, further illustrate the present invention and,
together with the detailed description of the invention, serve to
explain the principles of the present invention.
[0022] FIG. 1 illustrates a storage system including a receptacle
and a polymeric bag sized for use with the receptacle;
[0023] FIG. 2 illustrates a front view of a first type of a
polymeric drawtape bag;
[0024] FIG. 3 illustrates a front view of a second type of a
polymeric drawtape bag;
[0025] FIG. 4 illustrates an overview of a manufacturing process
producing the first type of polymeric drawtape bag;
[0026] FIG. 5 illustrates an overview of a manufacturing process
producing the second type of polymeric drawtape bag; and
[0027] FIG. 6 illustrates an overview of the control components of
the manufacturing process.
DETAILED DESCRIPTION OF THE INVENTION
[0028] Embodiments of the present invention provide an improved
design and manufacturing method for polymeric elastic drawtape bags
that addresses the limitations of existing bags. The following
description is presented to enable one of ordinary skill in the art
to make and use the invention and is provided in the context of a
patent application and its requirements.
[0029] FIG. 1 illustrates a storage system 100 including a
receptacle 105 and a polymeric bag 110 sized for use with the
receptacle. Storage system 100 is ubiquitous and implemented in a
wide variety of formats. The present invention is most conveniently
described in a specific context, but it is understood that it may
be adapted for implementation in many other contexts as well.
[0030] The specific preferred context includes bag 110 as a
nominally 13 gallon (49.21 liters) drawstring bag with "gripping"
technology and having side hole notch for accessing the drawstring,
hereafter referred to as a 13 gallon bag. A nominal 13 gallon bag
is configured for receptacle 105 as a nominally 13 gallon
receptacle, but there is a very wide variation in dimensions. For
example, even though referred to as a 13 gallon receptacle, the
actual gallon equivalent of receptacle 105 can range from about 9
gallons to about 14 gallons. Receptacle 105 may have representative
dimensions ranging from a top rim circumference of about 46.5
inches to about 49 inches while a depth dimension varies in a range
of about 19 inches to about 24 inches. For a limited sampling of
receptacles, receptacle 105 is, on average, about 12.4 gallons with
a circumference of about 48 inches and a depth of about 22 5/9
inches. Any sampling will show variation from these values.
[0031] Any manufacturer of bag 110 desirably provides dimensions
for bag 110 that will provide usefulness to as great a number of
people of possible, in as simple and efficient manner as possible.
Ultimately for any particular implementation of manufacturing for
bag 110, specific bag dimensions are chosen in contemplation of a
range of useful receptacle sizes. For a "grip" feature, it is
contemplated that the circumference of the gripper feature of bag
110 will be smaller than the smallest circumference of the set of
receptacles, with elastic "stretching" to provide the grip. There
is a limit to the amount of stretching that can occur before
deformation destroys the elasticity, which defines an effectively
upper bound for the circumference for receptacle 105. For a
particular design of bag 110, the present invention is used to
improve the usefulness to the end-user.
[0032] FIG. 2 illustrates a front view of a first type of a
polymeric drawtape bag 200. Bag 200 includes a polymeric film 205
with a first fold 210 at a bottom and a pair of lateral edge seals
215 to produce an opening 220 at a top. At the top a pair of second
folds 225 and a pair of top seals 230 create a pair of hems 235
enclosing a pair of drawtapes 240 that are sealed together at a
pair of lateral edge seals 245 to produce a single closed loop 250
extending through both hems 235. Loop 250 is captured within hems
235, but is otherwise unattached to polymeric film 205 so loop 250
moves independently and freely within hems 235. A set of lateral
notches 255 in hems 235 expose lateral edge seals 245 of loop
250.
[0033] Several important aspects of the present invention relate to
the dimensions of the bag, the seals, the notches and the interplay
of these dimensions in the context of use with receptacle 105 shown
in FIG. 1. As noted above, dimensions of notches 255 affect the
size of "holes" in the top of bag 200 after loop 250 is pulled
closed and tied. Notches 255 are used to allow a user to
conveniently access loop 250 and to remove bag 200 from receptacle
105 so they are necessary but can, when not appropriately
addressed, produce such undesirable effects. Heretofore Applicant
is unaware that bag manufacturers have manufactured an apparatus
such as bag 200, much less addressed specifically problems
associated with enlargement of lateral notches 255 in bag 200.
[0034] Specifics of bag manufacture vary from one bag format to
another. As noted, there are different ways of providing a reduced
circumference opening, not all of which include an independent
closed loop drawtape accessed by lateral notches with the closed
loop drawtape providing the sole gripping function. Important
dimensions for bag 200 include Bag.sub.Width1 and Bag.sub.Length1
which define the useful capacity of bag 200. Lateral side seals 215
each have a width shown as Body.sub.Seal1 defining a width of the
bag opening therebetween. Lateral edge seals 245 each have a width
shown as Loop.sub.Seal1 defining a width, Loop.sub.Length1,
therebetween. Notches 255 have a nominal length dimension shown as
Notch.sub.Length1. Loop.sub.Seal1 is greater than Body.sub.Seal1
and as explained in more detail herein, Notch.sub.Length1 is a
factor related to Bag.sub.Width1 and is desirably reduced when
possible, while preserving other important characteristics of bag
200.
[0035] FIG. 3 illustrates a front view of a second type of
polymeric drawtape bag 300. Bag 300 includes a polymeric film 305
with a first fold 310 at a bottom and a pair of lateral edge seals
315 to produce an opening 320 at a top. At the top a pair of second
folds 325 and a pair of top seals 330 create a pair of hems 335
enclosing a pair of drawtapes 340 that are sealed together at a
pair of lateral edge seals 345 to produce a single closed loop 350
extending through both hems 335. Loop 350 is captured within hems
335, but is otherwise unattached to polymeric film 305 so loop 350
moves independently and freely within hems 335. A set of lateral
notches 355 in hems 335 expose lateral edge seals 345 of loop
350.
[0036] Several important aspects of the present invention relate to
the dimensions of the bag, the seals, the notches and the interplay
of these dimensions in the context of use with receptacle 105 shown
in FIG. 1. As noted above, dimensions of notches 355 affect the
size of "holes" in the top of bag 300 after loop 350 is pulled
closed and tied. Notches 355 are used to allow a user to
conveniently access loop 350 and to remove bag 300 from receptacle
105 so they are necessary but can, when not appropriately
addressed, produce such undesirable effects. Heretofore Applicant
is unaware that bag manufacturers have manufactured a drawtape bag
such as bag 300, much less addressed specifically problems
associated with enlargement of lateral notches 355 in bag 300.
[0037] Specifics of bag manufacture vary from one bag format to
another. As noted, there are different ways of providing a reduced
circumference opening, not all of which include an independent
closed loop drawtape accessed by lateral notches with the closed
loop drawtape providing the sole gripping function. Important
dimensions for bag 300 include Bag.sub.Width2 and Bag.sub.Length2
which define the useful capacity of bag 300. Lateral side seals 315
each have a width shown as Body.sub.Seal2 defining a width of the
bag opening therebetween. Lateral edge seals 245 each have a width
shown as Loop.sub.Seal2 defining a width, Loop.sub.Length2,
therebetween. Notches 255 have a nominal length dimension shown as
Notch.sub.Length2. Loop.sub.Seal2 is equal to Body.sub.Seal2 with
Bag.sub.Width2 less than Bag.sub.Width1 and Bag.sub.Length2 greater
than Bag.sub.Length1 (to make the capacity of the bag 300
essentially the same as bag 200), Notch.sub.Length2 is less than
Notch.sub.Length1, and as explained in more detail herein,
Notch.sub.Length2 is a factor related to Bag.sub.Width2 and is
desirably reduced when possible, while preserving other important
characteristics of bag 300.
[0038] For example, Notch.sub.Length1 is at least about 1.625
inches (and may be increased in some implementations if variation
in notch cutting risks having a lateral edge seal 345 sealed to
hems 335). Loop.sub.Seal1 is about 0.625 inches greater than
Body.sub.Seal1. For other bag designs having lateral cutouts
accessing an enclosed elastic-type drawstring, notch lengths are
significantly larger and can be about 2.25 inches to about 2.5
inches. As further discussed below, use of a novel manufacturing
process enables the notch length to be reduced. For example,
Notch.sub.Length2 is about 1 inch, with Loop.sub.Seal2 about equal
to Body.sub.Seal2.
[0039] FIG. 4 illustrates an overview of a manufacturing process
400 producing the first type of polymeric drawtape bag 200 shown in
FIG. 2. Process 400 includes three manufacturing stations, a
dispensing station 405, a first forming station 410, and a second
forming station 415. Station 405 holds a roll 420 of polymeric
pliable material (aka polymeric film) 425. Roll 420 is manufactured
in a blown film extrusion process in the shape of a tube that is
flattened into a web format, then cut on one side and then wound
into a finished roll 420. Film 425 drawn off roll 420 includes a
fold 430 at a bottom edge while a top edge is open, which creates a
front panel (shown) and a back panel (not shown). Station 405
delivers film 425 to station 410 and then to station 415 for
further processing.
[0040] Station 410 pulls film 425 over a set of folding plates
where a section of both the front and back film panels at the top
end are each folded back over a pair of elastomeric (e.g., formed
of a polymeric material to be elastic for expanding, gripping
receptacle openings to hold bag upright) drawtapes 432. A top seal
435 is applied to both the front and the back film panels to form a
pair of hems 440 and the bag opening therebetween (only the front
drawtape 432, seal 435, and hem 440 are shown for clarity).
Specifically, a cutter (aka--Servo Cutter or the like) periodically
cuts a pair of notches 445, one notch 445 into each panel, to
expose periodic openings in the top edge. Film 425 continues
downstream over a set of folding bars where the individual front
and back bag are separated and hem 440 is then formed respectively
in each panel. At this point, a single strip of polymeric elastic
drawtape 432 is inserted into each hem 440 (a first strip inserted
into a front hem 440 and at the same time a second strip inserted
into a back hem 440). Film 425 continues downstream where the
respective top seals 435 are applied to both the front and back
panels, thus creating hems 440, one in each panel, with each hem
440 enclosing one polymeric elastic drawtape 432.
[0041] Film 425 continues from station 410 in this format
downstream into station 415 for further processing. Film 425
travels through a web tensioning device (aka--a Dancer), and
continues downstream around a sealing drum where periodic bag panel
seals 450 and drawtape seals 455 are made. Seals 450 are made from
primary seal bar mechanisms secured in the sealing drum. Seals 450
are made from seal bars that are secured to the primary seal bars
however the sealing variables are controlled separate of the
primary seal bar. Film 425 continues over a series of folding bars
for folding the sealed film into a folded web format.
[0042] The folded web then travels through a perforation knife
cutting station where periodic perforations 460 are made to folded
web which provides a mechanism to separate the sealed web format
into individual bags in a downstream machine (e.g., a folder,
winder, or the like--not shown). Bag 200 may be thus made by
process 400 and provides good results for a range of products. A
controller 465 using a feedback system 470 is optional in process
400 for notch placement, but its use as further described herein
could improve notch placement and permit narrower notches to be
employed and thereby improving bag 200 by reducing the notch hole
enlargement issue described herein.
[0043] Process 400 includes a considerable length of film 425
throughout the manufacturing line. For example, a distance between
the Servo Cutter at station 410 and a web perforation device at a
downstream end of station 415 is about fifty feet. This equates to
about 25 bags thus any variation in a tension of film 425 tension
typically results in oscillations in the Dancer which in turn
creates an expansion or retraction of the web path in the machine
direction. These oscillations cause the notch cutout placement to
move proportionally to the web expansion/retraction. In the event
the notch cutout 445 moves upstream or downstream as the result of
the web movement, notch 445 may be positioned in the immediate area
of the drawtape seal 450 thus becoming sealed to either end of hem
440 thus rendering the elastic characteristic of drawtape 432 to
not function as designed. In order to provide a means of
compensation for the web expansion/retraction and to ensure a
precise placement of notch 445 and its registration to the bag
panel side seals 450 and drawtape seal 450, controller 465 and
feedback system 470 are used and the tighter these registration
requirements (e.g., smaller notches), the more useful is controller
465 and feedback system 470. Thus, for process 500 described below
in FIG. 5 for production of bag 300, the controller and feedback
system are desirably included.
[0044] FIG. 5 illustrates an overview of manufacturing process 500
producing the second type of polymeric drawtape bag 300 shown in
FIG. 3. As further described below, process 500 is similar to
process 400 except that bag 300 is produced instead of bag 200.
Thus process 500 makes a bag that is narrower, longer, and has a
smaller notch, primarily by controlling registration better using a
controller and a feedback system. Process 500 includes three
manufacturing stations, a dispensing station 505, a first forming
station 510, and a second forming station 515. Station 505 holds a
roll 520 of polymeric pliable material (aka polymeric film) 525.
Roll 520 is manufactured in a blown film extrusion process in the
shape of a tube that is flattened into a web format, then cut on
one side and then wound into a finished roll 520. Film 525 drawn
off roll 520 includes a fold 530 at a bottom edge while a top edge
is open, which creates a front panel (shown) and a back panel (not
shown). Station 505 delivers film 525 to station 510 and then to
station 515 for further processing.
[0045] Station 510 pulls film 525 over a set of folding plates
where a section of both the front and back film panels at the top
end are each folded back over a pair of drawtapes 532. A top seal
535 applied to both the front and back film panels to form a pair
of hems 540 and the bag opening therebetween (only the front
drawtape 532, seal 535, and hem 540 are shown for clarity).
Specifically, a cutter (aka--Servo Cutter or the like) periodically
cuts a pair of notches 545, one notch 545 into each panel, to
expose periodic openings in the top edge. Film 525 continues
downstream over a set of folding bars where the individual front
and back bag are separated and hem 540 is then formed respectively
in each panel. At this point, a single strip of polymeric elastic
drawtape 532 is inserted into each hem 540 (a first strip inserted
into a front hem 540 and at the same time a second strip inserted
into a back hem 540). Film 525 continues downstream where the
respective top seals 535 are applied to both the front and back
panels, thus creating hems 540, one in each panel, with each hem
540 enclosing one polymeric elastic drawtape 532.
[0046] Film 525 continues from station 510 in this format
downstream into station 515 for further processing. Film 525
travels through a web tensioning device (aka--a Dancer), and
continues downstream around a sealing drum where periodic bag panel
seals 550 and drawtape seals 555 are made. Seals 550 are made from
primary seal bar mechanisms secured in the sealing drum. Seals 550
are made from seal bars that are secured to the primary seal bars
however the sealing variables are controlled separate of the
primary seal bar. Film 525 continues over a series of folding bars
for folding the sealed film into a folded web format.
[0047] The folded web then travels through a perforation knife
cutting station where periodic perforations 560 are made to folded
web which provides a mechanism to separate the sealed web format
into individual bags in a downstream machine (e.g., a folder,
winder, or the like--not shown). Bag 300 may be thus made by
process 500 and provides good results for a range of products just
as is true for bag 200, with bag 300 providing a smaller
notch-induced hole. A controller 565 using a feedback system 570 is
preferred in process 500 for accurate notch placement to reduce
notch length.
[0048] FIG. 6 illustrates an overview of a notch registration
control system 600 useful in the manufacturing processes described
herein, specifically as the "optional" components in process 400
and the "preferred" components in process 500. Of course a control
system exists for processes 400 and 500 and the notch registration
control system is an add-on (or integrated) function for a
preferred system of achieving a goal of reduced notch length for
any bag format using a manufacturing process generally similar to
those described herein. Thus not all control and feedback systems
and components used in processes 400 and 500 are described
herein.
[0049] Control system 600 includes components that are preferably
integrated into station 510 (and optionally station 410) and
station 515 (and optionally into station 415) as shown. Components
of control system 600 included in station 510 are an operator
programmable interface 605, a web encoder 610, a servo controller
615, and a servo cutter motor 620. Interface 605 is used for the
initial registration set point value as entered by an operator. Web
encoder 610 generates a web speed feedback signal used at station
515. Servo controller 615 initiates a control sequencing of servo
cutter motor 620. Servo cutter motor 620 actuates a notch cutter
through the polymeric film as described herein.
[0050] Components of control system 600 included in station 515
include a motion controller 625, a dancer and roller assembly 630,
and a dancer oscillation position feedback device 635. Dancer and
roller assembly 630 provide real-time feedback of motion of the
film as it travels through the stations of process 500. Rotary
oscillations of dancer and roller assembly 630 are converted into
linear oscillations by dancer oscillation position feedback device
635 and then into a dancer oscillation signal. Motion controller
625 is a central coordination point for process and feedback
communication regarding notch registration. Motion controller 625
receives the web speed signal from web encoder 610 and the dancer
oscillation signal from dancer oscillation position feedback device
635. Additionally, there is a notch registration feedback signal
indicating current downstream notch registration as described
below.
[0051] The notch registration feedback signal is obtained from
capturing a parameter of the film as it relates to where the system
is placing the notch in relation to the body and loop seals.
Preferably system 600 uses a vision capture system at a vision
capture point between two bags downstream of station 515.
Preferably this vision capture point is a distance between a bag
perforation 560 and a vertical trailing edge 640 of each notch
cutout 545. This vision capture point is the same point on each bag
during line operation.
[0052] System 600 includes, for a vision system, an imager 645
(e.g., feedback system 570) and a vision feedback processor 650
(e.g., controller 565). Imager 645 includes a digital capture
imaging sensor that inspects a placement of edge 640 with respect
to perforation 560. Imager 645 works in cooperation with feedback
processor 650 to send a notch registration feedback signal to
motion controller 625 so motion controller 625 can set precise
registration of notch 545.
[0053] Description of Systems Control:
[0054] Upon start-up of the manufacturing line, an initial notch
registration offset is set by a programmed value entered into
interface 605 by an operator as determined by a visual measurement
of a placement of notch 545 and its relation to perforation 560.
During line operation, a trigger signal is generated from the bag
machine perforation drum and is relayed to motion controller 625.
Motion controller 625 uses feedback from three interface sources:
web encoder 610 that measures web speed, feedback processor 650
providing the notch registration feedback signal based on a pixel
count of stored images against a live image capture from imager 645
during operation, and dancer oscillation position feedback device
635. As the line continues to run, motion controller 625 calculates
notch registration adjustments based on real time feedback from the
web encoder, vision and dancer feedback systems. Motion controller
625 maintains registration by outputting a signal to servo
controller 615 at every sequence of the perforation drum.
[0055] The improved manufacturing process can be implemented under
program control of a plurality of machine code instructions
accessed from a memory and executed by a controller or processor.
Some or all of the inventive aspects of certain ones of the
embodiments of the present invention may be implemented in such
non-transitory program instructions stored in a memory.
[0056] As noted herein, the system and process are most preferably
implemented in a polymeric bag used for collection and storage of
materials. The system and methods above has been described in
general terms as an aid to understanding details of preferred
embodiments of the present invention. Other preferred embodiments
of the present include the described application for improved
polymeric trash bags. In the description herein, numerous specific
details are provided, such as examples of components and/or
methods, to provide a thorough understanding of embodiments of the
present invention. The preferred embodiments include specific
physical processing devices and steps, such as cutters for notches
and inserters for placing drawtapes into formed hems. The preferred
invention encompasses other devices and methods for producing
notches, e.g., punches, lasers, and other processing equipment and
methods, to yield the desired structures.
[0057] One skilled in the relevant art will recognize, however,
that an embodiment of the invention can be practiced without one or
more of the specific details, or with other apparatus, systems,
assemblies, methods, components, materials, parts, and/or the like.
In other instances, well-known structures, materials, or operations
are not specifically shown or described in detail to avoid
obscuring aspects of embodiments of the present invention.
[0058] Reference throughout this specification to "one embodiment",
"an embodiment", or "a specific embodiment" means that a particular
feature, structure, or characteristic described in connection with
the embodiment is included in at least one embodiment of the
present invention and not necessarily in all embodiments. Thus,
respective appearances of the phrases "in one embodiment", "in an
embodiment", or "in a specific embodiment" in various places
throughout this specification are not necessarily referring to the
same embodiment. Furthermore, the particular features, structures,
or characteristics of any specific embodiment of the present
invention may be combined in any suitable manner with one or more
other embodiments. It is to be understood that other variations and
modifications of the embodiments of the present invention described
and illustrated herein are possible in light of the teachings
herein and are to be considered as part of the spirit and scope of
the present invention.
[0059] It will also be appreciated that one or more of the elements
depicted in the drawings/figures can also be implemented in a more
separated or integrated manner, or even removed or rendered as
inoperable in certain cases, as is useful in accordance with a
particular application.
[0060] Additionally, any signal arrows in the drawings/Figures
should be considered only as exemplary, and not limiting, unless
otherwise specifically noted. Furthermore, the term "or" as used
herein is generally intended to mean "and/or" unless otherwise
indicated. Combinations of components or steps will also be
considered as being noted, where terminology is foreseen as
rendering the ability to separate or combine is unclear.
[0061] As used in the description herein and throughout the claims
that follow, "a", "an", and "the" includes plural references unless
the context clearly dictates otherwise. Also, as used in the
description herein and throughout the claims that follow, the
meaning of "in" includes "in" and "on" unless the context clearly
dictates otherwise.
[0062] The foregoing description of illustrated embodiments of the
present invention, including what is described in the Abstract, is
not intended to be exhaustive or to limit the invention to the
precise forms disclosed herein. While specific embodiments of, and
examples for, the invention are described herein for illustrative
purposes only, various equivalent modifications are possible within
the spirit and scope of the present invention, as those skilled in
the relevant art will recognize and appreciate. As indicated, these
modifications may be made to the present invention in light of the
foregoing description of illustrated embodiments of the present
invention and are to be included within the spirit and scope of the
present invention.
[0063] Thus, while the present invention has been described herein
with reference to particular embodiments thereof, a latitude of
modification, various changes and substitutions are intended in the
foregoing disclosures, and it will be appreciated that in some
instances some features of embodiments of the invention will be
employed without a corresponding use of other features without
departing from the scope and spirit of the invention as set forth.
Therefore, many modifications may be made to adapt a particular
situation or material to the essential scope and spirit of the
present invention. It is intended that the invention not be limited
to the particular terms used in following claims and/or to the
particular embodiment disclosed as the best mode contemplated for
carrying out this invention, but that the invention will include
any and all embodiments and equivalents falling within the scope of
the appended claims. Thus, the scope of the invention is to be
determined solely by the appended claims.
* * * * *