Note: Descriptions are shown in the official language in which they were submitted.
4~9
S P E C I F I C A T I O N
The invention relates to improvements in
apparatus for making plastic film bags having reclos-
able fasteners thereon, and particularly of the type
5 having opposed in~erlocking rib and groove elements on
the confronting top edges of the bags.
In the manufacture of bags of this type,
continual efforts are being made to increase the speed
of production output to thereby effect a saving in cost
of the individual bags. There are factors which limit
10 the speed cf extrusion of the film and speed of joining
of profiles so that the present concept embodies manu-
facturing simultaneously a plurality of bags in a
unique manner so that actually, material for making
four bags with each cross-sealing operation is produced
15 simultaneously in a single tubular extrusion film.
Attempts to make multiple bags in a single
extrusion operation encounter the problems of control-
ling the film and controlling the profiles. The pro-
files are joined before the film is wound or spooled in
20 order to avoid the risk of not knowing whether or not
acceptable interlocking profiles have been provided and
in order to complete the continuous strip in a form
which is suitable for storage without deforming the
profiles or damaging the film adjacent the profiles.
25 Methods heretofore have been employed wherein tubular
film has been formed and folded in such a way so as to
simultaneously make dual bags with each cross seal-ny
operation. However, a feature of the present invention
is to provide a method and mechanism for making a
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~L2~;499
double double tube wherein material for four bags is
formed. The difficulty in forming a double double tube
is to handle the large amount of film emanating from
the extruder, collapsing the bubble of the film so that
5 the profiles are aligned and joined and handled in such
a manner so that usable strips of profile film are pro-
vided which can be formed into four bags. The handling
of such a tube creates problems in where the tube is to
be slit, which profiles are to be joined to each other,
10 and the collapsing of the bubble in such a manner that
a fold mark is formed where the natural fold of the
eventual bag will occur.
It is accordingly an object of the present
invention to provide an improved apparatus for forming
15 a unique tubing which is capable of being converted
into four reclosable bags at cne time by a single
cross-cutting and sealing arrangement. More parti-
cularly, the method and apparatus of the invention
provides double double profile film sets or in other
20 words, two sets of double profile film.
A further object of the invention is to
provide a unique manner of slitting and foldinq and
joining profiles in a tubing so that strips of double
profile film for conversion into two sets of double bag
25 film strips are formed.
A feature of the present invention is the
formation of a continuous tube of film with eight
profiles on the inner surface, and finding a satis-
factory way of joining said profiles so as to form
30 profile film strips that can be readily converted into
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sets of reclosable bags. One unsatisfactory manner of
approaching the problem is to roll the tube into a
spool after aligning the profiles, but not joining
them, so that the tube is folded between profiles and
5 then separating anc1 rejoining the tube suctions later
at the bag machine. This situation creates the problem
of not knowing whether or not the profiles are satis-
factory until much later.
Another alternative unsatisfactory solution to
l0 handling the tube is to slit the tuhe into two sections
which would have to be joined onto themselves and
spooled.
A feature oE the invention is the making of a
quadruple profile tube which is then divided into two
15 sets of double profile film wherein the profile from
one of the film sections is folded into the other film
sections and vice-versa. In this manner, production
output can be increased substantially since two double
profile films for conversion into reclosable bags are
20 provided from one quadruple profile tube.
Pursuant to the present invention, there is
provided an apparatus for making flexible plastic bags
with integral pressure interlocking rib and groove
elements on the con~ronting top edges, comprising means
25 for extruding a continuous tube with pairs of closely
spaced interlocking elements on the surface of the
tube, the total pairs being a multiple of 2 with at
least 4 pairs on the tube; means for slitting the tube
leng~hwise between profiles of alternate pairs; and
30 means for folding the tube between each adjacent pair
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s~
for bringing the profile adjacellt the slit over onto
the closest profile of the pair which has not been
slit.
There is also provided by the present inven-
5 tion a mechanism for making fle~ible plastic bags withintegral pressure interlocking rib and groove elements
on the confronting ~op edges comprising in combination
an extruder die for extruding a continuous tube having
die openings shaped and spaced to form on the inner
10 surface of the tube a first pair of closely spaced r:ib
elements and a second pair of closely spaced rih ele-
ments diametrically opposed from the first; a first
pair of closely spaced groove elements intermediate the
pairs of rib elements and a second pair of closely
15 spaced groove elements diametriclly opposed from the
first pair of groove elements with the groove e~ements
being of the size and shape to pressure interlock with
the rib elements; and first and second cutters for
continuously longitudinally cutting the tube at a first
20 location between one of said pair of rib or groove ele-
ments and at a second location between the other of
said pair of rib or groove elements.
Other objects, advantages and features, as
well as equivalent methods and apparatuses which are
25 intended to be covered herein, will become more appar-
ent from the -teacnings of the present invention in
connection with the disclosu.re of the preferred embod-
iment thereof i.n the specification, claims, and draw-
ings, in which:
ON THE DRAWIN~S
-
FIG. 1 is a perspective view of aa tubular
plastic profile film being extruded and formed into
separate double proEile film strips in accordance with
5 the principles of the present invention;
FIG. 2 is an enlarged detailed sectional v.iew
taken ~bst~ntially along the line Il-II and illus-
trating mechanism which is added to the showing of FIG.
1 to accomplish the function shown schematically in
10 FIG. l;
FIG. 3 is a perspective view of a bag of the
type which will result from the manufacturi.ng arrange-
ment illustrated;
FIG. 4 is a vertical sectional view through
15 the bag of FIG. 3 taken substantially along line IV-IV;
FIG. 5 is a view of a secondary form of quad-
ruple profile tubing, FIG. 1 illustrating the preferred
form; and
FIG. 6 is a perspective view illustrating the
20 manner of handling each of the dual double strips
formed by the method of FIG. 1.
As illustrated in FIG. 1, an extruder 10 is
provided with molten plastic which is pressure extruded
through an annular slot to form a continuous film tube
25 11. The slvt ls shaped so as to form on the inner sur-
face of the tube a series of eight profiles. The
profiles are of the rib anA groove type and are of
complementary shape and size so as to be pressure
interlockable and separable fcr forming reclosable
3G fasteners at the confronting top edges of plastic film
-5
4~9
bags such as illustrated in FIGS. 3 and 4.
On the inner surface of the film is a first
pair 12 of closely spaced male profiles or ribs 12a and
12b. Diametrically opposite this location relative to
5 the tubular film is a second pair 13 of ribs 13a and
13b which are also closely spaced.
Circumferentially between the diametrically
opposite pairs 12 and 13 is a pair 14 of closely spaced
female profiles or grooves 14a and 14b. Diametrically
10 opposite the pair 14 i5 a second pair 15 of closely
spaced grooves 15a and 15b. The spacing between the
rib elements and groove elements is sufficient to
provide material for pull flanges as shown in the
finished bag of FIGS. 3 and 4.
As the tube is extruded and becomes prelimi-
narily cooled, it is flattened against the resistance
of the air bubble within the tube in a manner so as to
align the first pair 12 of ribs with the first pair 14
of grooves thereby forming a first set 16. Similarly,
20 the second pair 13 of ribs is aligned with the second
pair 15 of grooves forming a second set 17 of ribs and
grooves.
The collapsing of the tube into this alignment
may occur by utilizing spaced rolls or guides correctly
25 positioned in relationship to the ribs and grooves as
they appear on the film tube.
The next step includes cutting or slitting the
tube longitudinally continuously with knives 45 and 46
to form slits shown at 47 and 48 respectively. The
30 slit formed by the knife 45 is midway between the first
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pair 12 of profi:Les which is in the upper layer of the
tube which is folded a~ its lateral side edges 20 and
21. The slit formed by the knife 46 is midway between
the second pair 13 of ribs on the lower layer of the
5 tube. The slits are simultaneously made, but al~er-
natively either slit can be made in advance of the
other, but both slits must be completed before the tube
is foldedO
In the next step which uniquely forms strips
10 18 and lg of profile film for conversion into double
bags, the severed film is folded in such a manner so as
to form two dual profile film strips. The folding is
accomplished by a suitable guidance structure such as
that shown in FIG. 2 where the profile 12a from the
15 first set 16 is folded over onto the second set 17 to
be interengaged with the groove 14 simultaneously with
the interengagement of profiles 12b and 15b.
As substantially the same time, the proile
13a from the second set 17 is folded over onto the
20 first set to be interengaged with the groove 15a, while
simultaneously therewith profiles 13b and 14b ale being
interengaged. This unique folding provides the two
double profile film strips 18 and 19 which are utilized
to form bags in the manner illustrated in FIG. 6.
FIG. 2 illustrates the manner in which the
folding may be accomplished. An edge guide such as 39
having a concave groove m~y be provided to receive the
doubled edges 20 or 21 of the film strip 16 and 17, and
shaped metal or plastic guide strips hold the groove
30 elements l~a and L4b in place as illustrated by the
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backing pla~e 33 a]ld the guide plates 34, 35 and 35.
The rib 13b is guided and pressed to interlock in~o the
groove 14b by shaped plates 34a and 35a and backing
plate 33a.
The rib 12a is brought over onto the second
set 17 by curved plates 37 and 38 and backing plate 38a
which bring the rib 12a along the path in~icated by the
broken lines into the dotted line position of 12a where
it is pressed into the groove 14a. A similar mechanism
10 is provide~ for folding the lower layer of the film to
bring the rib 13a into the groove 15a.
The resu:Ltant dual double profile film strips
18 and 19 are formed into bags by cross-cutting and
sealing. The resultant bags are illustrated in FIGS. 3
15 and 4. The plastic film bags such as shown as 25 have
a folcled bottom 29 and cut and sealed side edges 30 and
31. The profiles are 30ined at 26 with groove profile
26a receiving rib profile 26b. Above the profiles are
short flarlges 27 and 28 which permit the user to pull
20 the profiles apart: for in opening the bag.
FIG. 5 illustrates a modified and less desir-
able form of film, but one which is constructed in
accordance with the principles of the present inven-
tion. In the film of FIG. 5, a first pair 41 of
25 profiles is located within the tube 40, and a second
pair 42 of profiles is located diametrically opposite
the first pair 41. A third pair 43 of profiles is
located between the first and second pair, and a fourth
pair 44 is positioned diametrically opposite the third
30 pair 43. Each pair consists of a male and female with
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5499
their locations being alternated as the tube is viewed
progressing clockwise or counter-clockwise within the
tube.
When the tube of FIG. 5 is slit, the first
5 slit, which is ma~e by the knife 45 will be located
between the profiles of the first pair 41, and the
groove element 41a will be folded over onto the rib
element 43a. The second slit will be made by the knife
46 between the profiles of the second pair 42, and the
10 groove profile 42a will be folded over onto the rib
profile 44a, in the same manner as illustrated in FIG.
1.
With reference to FIG. 1, the knives 45 and 46
may be located so that instead of cutting between the
15 rib elements, they cut between the groove elements. In
such arrangement, knife 45 will cut a slit between the
groove elements 15a and 15b of the pair 15, and the
knife 46 will slit midway between the groove elements
14a and 14b of the pair 14. W'nen the slits are made,
20 the tube will be folded so that the groove 15a is
brought over onto the rib 13a. The groove 14a will be
brought over onto the rib 12a. Similarly, with respect
to the arrangement shown in FIG. 5, slits may be ma~e
between the pairs 43 and 44, and the tube would be
25 folded to align the rib and profile elements. In each
case the folding will result in double bag strips such
as 18 and 19 in FIG. 1.
As the two double profile film strips 18 and
19 are formed, they are wound onto rolls 22 and 23.
30 These rolls may either be used separated to form two
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~2~54~
bags or simultaneously used to form four bags. As
illustrated in FIG. 6, the roll 22 is unrolled with the
profile film strip 18 being fed into a perforation
device 50 which forms a longitudinal line of perfora-
5 tions 51 in the tube layer opposite the slit 48. Thetubing is then fed into a sealing and cutting mechanism
52 wherein spaced cross-seals are made to form side
seals such as 53 and 54 at the edges of the bags and
the bags are cut apart at their side edges. The bags
10 are stacked in a stacking tray 55, and when removed,
can be torn apart at their top edges to separate the
stacks 56 and 57 at the center separation 58. The
separate stacks then may be banded such as shown by
bands 59 and 60.
While preferred forms are illustrated, tubing
may be extruded with 12 profilès on the inner surface
or with 16, or any additional multiples divisible by
4. Each set of 4 profiles will form an additional
double bag strip, and the total number is limited only
20 by the capability of handling the material and the size
of the die and the equipment which must be provided.
In each instance where additional profiles are added in
multiples of 4, the same positional relationship of
profiles is used with pairs of closely spaced elements
25 and slits made between alternate pairs, and one profile
adjacent the slit folded over onto the profile next to
lt. The pairs are arranged relatively close to each
other, slits are made in alternate pairs around the
periphery of the tubing, and the profiles are brought
30 together to mate with the profile which is adjacent it
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in the next pair. The spacing between pairs, of
course, is chosen dependent on ~he size of the bag
which is to be produced as will be apparent from the
resultant bag shown in FIGS. 3 and 4. Tne closeness of
5 the profiles in each pair will be chosen in accordance
with the length of the flap or flange at the top of the
bag. As will be understood from the foregoing descrip-
tion, when tubing is extruded with 12 or more profiles
on the inner surface, slits are made between alternate
10 pairs of profiles, and the pairs of profiles in a 12
profile bag are not diametrically opposite each
another. In accordance with the present invention, the
tubing is extruded with at least 4 pairs of profiles,
and the pairs can be increased, but must be done so in
15 multiples of 2. In some instances, it may be desirable
to locate the profiles on the external surface of the
tubing, although the profile location on the ~nner
surface is preferred.
Thus, it will be seen that we have provided an
20 improved method and mechanism which meets the objec-
tives above set forth and which is capable of utiliza-
tion for increasing output and reducing scrap rate.
The mechanism doubles the production of structures
which are capable of producing dual bags and quadruples
25 the output of structures which produce single bags
without disadvantages to the resultant bag structure.
