Information
-
Patent Grant
-
6553740
-
Patent Number
6,553,740
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Date Filed
Wednesday, June 20, 200123 years ago
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Date Issued
Tuesday, April 29, 200321 years ago
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Inventors
-
Original Assignees
-
Examiners
Agents
- Pitney, Hardin, Kipp & Szuch LLP
-
CPC
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US Classifications
Field of Search
US
- 053 1334
- 053 1392
- 053 412
- 493 213
- 156 66
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International Classifications
-
Abstract
An apparatus for attaching discrete lengths of zipper at spaced intervals across a web of bag making film has an endless belt supported between a pair of pulleys for moving zipper segments into position on the web. The zipper segments are cut from a zipper supply and fed into a nip between the endless belt and the web top surface. After a zipper segment is deposited into position on the web, the endless belt is raised. A vertically movable sealing bar below the web is raised into position to heat the web to seal the zipper to the web after which the sealing bar is lowered. The web then advances and the process is repeated.
Description
BACKGROUND OF THE INVENTION
In U.S. Pat. No. 4,909,017 a method is disclosed for producing a reclosable plastic bag having a zipper that extends transverse to the longitudinal or running direction of the web of the film from which the bag is formed. In accordance with the disclosed method which is illustrated in simplified form
FIG. 1
of the present application, a zipper segment
10
having interlocked profiles is fed transversely across a web of bag making film
12
and one of the profiles is attached to the web. The length of the segment is equal to approximately half the width of the desired bag. At a bag making machine the web is formed into a tube by sealing the edges of the film together with seal bars
14
after which the other profile of the zipper is attached to an inner surface of the tube by seal bar
16
s.
The construction of bag
21
is completed by forming a cross seal
18
by seal bar
20
which also serves to sever the completed bag from the tube.
In U.S. Pat. No. 6,116,314 problems associated with attaching a zipper transverse to the running direction of a bag making film are discussed. In this patent and other relatively recently issued patents, the problems of attaching transverse direction zipper are addressed by providing the zipper profiles with extended flanges to facilitate the attachment process. In many instances, however, it is desirable to use a flangeless zipper or a zipper with limited flanges. For one thing, such zippers utilize less plastic and hence tend to be cheaper than zipper with flanges. In addition, because of their smaller size, greater lengths of flangeless or limited-flange zipper can be wound on comparably sized rolls as compared with flanged zipper which enables longer production runs.
SUMMARY OF THE INVENTION
The present invention relates to a method and apparatus for attaching zipper to film that can be used with virtually any type of zipper profiles. That is, the zipper profiles may be flanged, flangeless or anything in between. In accordance with the present invention, an apparatus for attaching discrete lengths of zipper at spaced intervals across a film has an endless belt supported between a pair of pulleys for moving a zipper segment onto a web of bag making film moving along a path off a supply roll. The zipper consists of profiles with interlocked engagement elements and is fed with one profile atop the other. The zipper segments are cut from a zipper supply and fed into a nip between the endless belt and the web top surface. After a zipper segment is deposited into position on the web, the pulleys are raised to disengage the zipper segment from being driven further by the endless belt. A sealing bar below the web is then raised into position to heat the bottom surface of the web to seal the bottom profile of the zipper to the web top surface after which the sealing bar is lowered. The web then advances and the process is repeated. The resultant bag making film with attached zipper may then be fed directly into a bag making machine or spooled for later use.
BRIEF DESCRIPTION OF THE DRAWINGS
In the accompanying drawings:
FIG. 1
is a schematic representation of a system for producing reclosable bags from a web of bag making film having zipper segments applied transversely to the running direction of the web;
FIG. 2
is a schematic side elevational view of a zipper-to-web applicator in accordance with the present invention;
FIG. 3
is a schematic sectional view taken along reference line
3
—
3
of
FIG. 2
; and
FIG. 4
is a fragmented view similar to
FIG. 3
showing the seal bar in sealing position.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
Reference is now made to the drawings and to
FIGS. 2 and 3
in particular wherein the zipper-to-web applicator
30
of the present invention is depicted. The applicator
30
consists of two main sections, a zipper sealer
32
and zipper drive
34
. The zipper drive
34
consists of an endless belt
36
formed of silicon rubber or the like extending about a pair of pulleys
38
,
40
. One of the pulleys is connected to a drive (not shown) to be driven as indicated in FIG.
3
. The zipper drive
34
is also vertically shiftable between a lower position as shown in
FIGS. 3 and 4
and a raised position that is shown in FIG.
2
. The belt has a concave contour
42
on its outer surface into which a zipper segment
44
fits. A block of a heat resistant material
43
such as nylon or Delrin is provided within the belt, between the pulleys. When in the lower position, the belt forms a nip
46
with the top surface of a web of film seated on the applicator frame
48
so that a segment of zipper
44
fed into the nip is drawn by the belt across the web, as will be described.
The zipper sealer
32
consists of a seal bar
50
that is vertically movable by a two stage cylinder
60
between a lower position shown in
FIG. 2 and a
raised position shown in FIG.
4
. When in the lower position, the seal bar is out of contact with the bottom surface of a web
52
on a support surface of the applicator and spaced sufficiently far beneath the web so that it does not affect the web
52
. In the raised position (shown in FIG.
4
), the sealing bar contacts the web bottom surface and seals the bottom of the lower profile
56
of zipper
44
to the top surface of the film web. To this end, the bottoms of the zipper profiles
56
,
58
may be coated with a sealant layer, such as EVA, to facilitate sealing the zipper to the bag making film. A thermocouple
61
and heater element
62
are provided in the seal bar
50
in the conventional manner to control the temperature for optimum sealing.
In operation a web of bag making film
52
is fed off a feed spool
64
onto a support surface
48
of the applicator. The web feed may be continuous or intermittent. If continuous, dancer rolls or a similar arrangement may be used to enable the web at the applicator to be stopped during the zipper application process. When a desired length of bag making film (determined by the depth of the bag
21
to be formed) is fed onto the applicator support surface, the web is stopped and zipper drive
34
is lowered. Drive pulley
40
is then activated to move belt
36
. A drive arrangement
66
is also activated to draw zipper from a zipper supply spool
68
through guides
70
to the nip
46
between the entrance to the zipper drive
34
and the web seated on support surface
48
. When a sufficient length of zipper is drawn (i.e. a length equal to approximately one half the width of web
52
), cutter
72
is activated to sever the zipper length from the zipper supply. The zipper length is then moved by the lower portion of endless belt
36
into the desired position on web
52
(usually centered with respect to the edges of the web) and the zipper sealer cylinder
60
is activated to raise seal bar
50
. The heated seal bar
50
then seals the bottom of the bottom profile
56
of the zipper to the top surface of web
52
by capturing the two between the seal bar and the belt which is supported by the heat resistant block
43
. The zipper sealer
32
is then lowered, the zipper drive
34
is raised and a take up spool
74
is activated to move the film
52
into the next position to receive a zipper and the process is then repeated. The spool
74
, which consists of the web of bag film with attached zipper is then brought to a bag making machine such as depicted in
FIG. 1
to complete the bag making process.
Thus, in accordance with the above, the desired objectives of the present invention are effectively attained. It should be understood that modifications of the preferred embodiment will be readily apparent to those skilled in the art. For example, rather than spooling the web of bag making film with attached zipper, the zipper applicator may be placed upstream of the bag making equipment so that the film web with applied zipper can be fed directly into the bag making equipment. Also, rather than intermittently stopping the film for each zipper length application, the zipper applicator may be fixed to a shuttle that moves with the film during zipper application and then moves back to the zipper receiving position.
Claims
- 1. An apparatus for attaching discrete lengths of zipper having a pair of interlocked profiles at spaced intervals across a film, one of said profiles being atop the other profile, said apparatus comprising:a film drive for moving a web of bag making film along a path off a supply roll, said web having a top surface and a bottom surface; a zipper segment drive extending transverse to the film path and at least partially across the film path for moving a zipper segment having a discrete length across the top surface of the film in a direction transverse to the moving direction of the web; and a sealer disposed below the web bottom surface and aligned with said zipper drive for sealing said web top surface to a bottom one of said zipper profiles by capturing said web between said sealer and said zipper drive.
- 2. The apparatus in accordance with claim 1 wherein said zipper segment drive comprises a pair of pulleys disposed above said film path and an endless belt extending about said pair of spaced pulleys.
- 3. The apparatus in accordance with claim 2 further comprising means for vertically moving said zipper segment drive toward and away from said web path between a lower position at which said zipper segment between a bottom portion of said belt and said web is driven by said belt across said web and a raised position at which said belt is out of contact with said zipper segment.
- 4. The apparatus in accordance with claim 3 wherein said belt is formed of a silicon rubber.
- 5. The apparatus in accordance with claim 3 further comprising means for cutting said zipper segment from a zipper supply and means for feeding said cut zipper segment into a nip between said belt and said web top surface when said zipper segment drive is in said lower position.
- 6. The apparatus in accordance with claim 1 further comprising means for moving said sealer between an upper position at which said sealer is in position to seal said web to said bottom one of said profiles of a zipper segment on said web top surface and to a lower, non-sealing position.
US Referenced Citations (10)