Note: Descriptions are shown in the official language in which they were submitted.
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IMPROVEMENTS IN ASSEMBLING PACKAGING
The present invention relates to improvements in
assembling packaging, especially packaging which
incorporates a tape, such as a tear tape, to assist in
the opening of a package.
In known systems, a sheet of packaging material
which will form a plurality of packages is printed,
before being cut into the requisite sized packages. If a
tear tape is to be included in the finished package, this
is usually applied after the printing step, but before
the sheet is cut. Tear tape is usually supplied on self-
wound reels, wherein one side of the tape is coated with
pressure-sensitive adhesive, and the other side is coated
with a release agent, such as silicon. Such a tape is
disclosed in the applicant's own EP 0 121 371.
Alternatively, if the tape is not self-wound, a release
paper may be provided to prevent the tape from adhering
to itself too strongly. Alternatively, an adhesive, such
as hot melt adhesive, can be applied to one side of the
tape, by a hot shoe, or similar device as a step of the
application process.
The present invention is mainly concerned with the
application of self-wound tear tape to packaging, where
one side of the tape is coated with release agent and the
other is coated with pressure-sensitive adhesive. This
type of tape has advantages over the hot melt adhesive
type in that: the tape can be applied more quickly, there
is less likelihood of the adhesive contaminating other
parts of the machinery, and no adhesive seeps out from
under the tape after its application. Such seepage
could, for example, cause problems when different
packaging portions to which tapes are applied are stacked
on top of each other, especially when the adhesive is
still warm.
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In known systems where tear tape is applied to
packaging, tape is fed into the printing machine from a
tape reel which may be motorised, depending upon the size
and type of reel. The tape is then applied to the
packaging as the packaging passes through the machine.
When the reel of tape is empty, the machine must be
stopped temporarily so that the reel can be changed.
Obviously, this decreases productivity, not only because
the printing has temporarily ceased, but also because
upon restarting of the machine the distinct printing
stages must again be brought into precise registration
before the printing may be continued at normal speed.
EP 0358 477 discloses a toggle for attaching the
trailing edge of a tape currently in use to the leading
end of a reserve tape. The tape in use is supplied with
a pin, which is disposed transversely to the axial extent
of the tape. The reserve tape is provided with a loop,
through which the tape in use (i.e. current tape) passes.
When the pin attached to the tape in use contacts the
loop, the reserve tape will be drawn into the machine.
The portion of packaging incorporating this toggle will
subsequently have to be located manually and discarded.
This document discusses the fact that this toggle may
cause the reserve tape to be fed into the machine upside
down and that this could be a problem for tapes with one
adhesive side. To address this problem the document
discusses including a tail segment, where the portion of
the tape in use that is attached to the reel is loosely
attached (for example, with masking tape) to the portion
of the in use tape having the pin. However, this
arrangement involves complicated preparation of the tapes
and is therefore undesirable.
US 4,572,460 discloses a similar system in which the
tape in use is provided with an aperture, and the reserve
tape is supplied with a "mushroom-like" tab. There is no
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mention of any modification that would make this
apparatus suitable for use with adhesive tape.
It would be advantageous to be able to supply tape
continuously from a plurality of rolls of tape
sequentially, without having to prepare the tapes, or
having to attach anything thereto as with the prior art.
One aspect of the present invention provides a
method of splicing tapes, having an adhesive coating, the
method comprising the steps of:
driving a first tape supplied from a first tape
supply reel past a splicing area, the splicing area
including at least two rollers movable between a closed
position in which contact is made with tape in the
splicing area, and an open position in which contact is
not made with any tape in the splicing area;
introducing a second tape from a second tape supply
reel into the splicing area when the rollers are in the
open position; and
pressing the first and second tapes together with
the rollers, to cause the first and second tapes to
adhere together, one on top of the other.
Preferably the method includes the steps of
monitoring the amount of tape remaining on the first reel
and moving the rollers in the splicing area into the
closed position when the amount of tape remaining on the
first reel falls to a predetermined level.
At least one of the first or second tapes should be
coated with adhesive on one side.
Preferably the method further includes the step of
cutting the first tape after the tapes have been joined.
Preferably the method further includes the step of
moving the rollers to the open position.
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The step of monitoring the amount of tape remaining
on the first reel may be automated.
The step of moving the rollers to the closed
position when the amount of tape remaining on the first
reel falls to a predetermined level may be automated, and
may be based on the automatic monitoring of the amount of
tape remaining on the first reel.
The step of cutting the first tape may be automatic,
and may be performed when a predetermined time has
elapsed with the rollers in the closed position.
The step of monitoring the amount of tape on the
first reel may comprise the steps of:
resting circumferentially on the reel an arm, one
end of which is pivotally mounted on a rotary
potentiometer, so that as tape is dispensed from the
reel, and its diameter reduces, the arm is displaced
pivotally:
monitoring the change in potential difference across
the potentiometer;
using the said change in potential difference across
the potentiometer to determine the amount of tape
remaining on the reel.
Alternatively, the step of monitoring the amount of
tape on the first reel may comprise the steps of:
resting circumferentially on the reel an arm,
provided with a metal target, so that as tape is
dispensed from the reel, and its diameter reduces, the
arm is displaced;
providing an inductive sensor in the proximity of
the metal target;
monitoring the load on the inductive sensor;
using the load on the inductive sensor to determine
the amount of tape remaining on the reel.
According to another aspect of the present invention
there is provided an apparatus for supplying a continuous
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length of adhesive tape from reels carrying discrete
amounts of adhesive tape, the apparatus comprising:
a splicing unit, including a tape path for conveying
tape, and at least two rollers, being movable between an
open position in which the rollers do not come into
contact with the tape path and a closed position in which
the rollers contact the tape path to join together tapes
from different reels in use.
There may be further provided first and second tape
dispensers, for holding first and second reels of
adhesive tape, respectively, wherein the splicing unit
further includes at least one reserve tape retaining
means, for retaining a leading edge of a tape from one of
the first or second reels as a reserve reel.
The other of the first or second reels, as a
currently-supplying reel, may be provided with an
automatic monitoring system for monitoring the amount of
tape held on the reel. The monitoring system may be
connected to a control unit, which is arranged to move
the rollers from the open position to the closed position
when a signal from the monitoring system indicates that
the amount of tape held on the currently-supplying reel
has reached a predetermined low level.
The control unit may also control the reserve tape
retainer, for allowing a tape held thereon to become
released therefrom when the rollers move into the closed
position.
The control unit may actuate a cutting mechanism,
for cutting a tape from a spent reel when the rollers are
in the closed position. The cutting may be activated a
predetermined time after the rollers have been moved into
the closed position.
The control unit may return the rollers into the
open position a predetermined time after they moved into
the closed position.
The monitoring unit may comprise:
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an arm pivotally mounted on a portion of casing, for
positioning circumferentially on a reel of tape, and a
rotary potentiometer attached pivotally to one end of the
arm, so that as the arm falls, the potential difference
across the potentiometer will vary according to the
position of the arm, for determining the amount of tape
remaining on a reel.
Alternatively, the monitoring unit may comprise:
an arm having a metal target, pivotally mounted on a
portion of casing, for positioning circumferentially on a
reel of tape, and in the proximity of an inductive
sensor, so that as the arm falls, a different loading on
the inductive sensor is produced, for determining the
amount of tape remaining on a reel.
A DC output may be produced by the monitoring unit
which may then be input into a control unit.
According to another aspect of the invention there
is provided tape splicing apparatus for splicing together
tapes from different tape supply reels, the apparatus
comprising:
a splicing station, having a first tape input path
along which tape is arranged to pass from a first tape
supply reel to a common tape output, and a second tape
input path along which tape is arranged to pass from a
second tape supply reel to the common tape output,
wherein the splicing station has at least a pair of nip
rollers movable between a first, open configuration in
which the rollers are spaced apart, and a second, closed
configuration, in which the rollers come together to urge
the tape portions from the first and second input paths
into contact, one an top of the other;
wherein one of the first and second tape supply
reels is arranged as a current reel and the other reel is
arranged as a standby reel;
wherein the apparatus comprises means arranged in
use to determine the quantity of tape remaining on the
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current reel andlor the estimated time remaining before
the tape supply on the current reel is exhausted;
wherein, based upon said determination, the
apparatus is arranged to move the nip rollers from the
first position to the second position to cause the tapes
to adhere to one another;
and wherein, the apparatus further provides cutting
means, arranged to cut the tape from the current reel
thereby to replace the current reel with the standby
reel.
The present invention may include any combination of
the features and/or limitations referred to herein,
except such features as are mutually exclusive.
Preferred embodiments of the present invention will
now be described with reference to the following
drawings, in which:
Fig. 1 shows tape from a dispensing unit being fed
to packaging material in accordance with an embodiment of
the present invention;
Fig. 2 shows the tape dispensing unit of Fig. 1;
Fig. 3 shows the tape splicing portion of the tape
dispensing unit of Fig. 2;
Fig. 4 shows a tape loaded on the tape dispensing
unit;
Fig. 5 shows a tape in use on the tape dispensing
unit;
Fig. 6 shows two tapes being spliced together;
Fig. 7 shows the join between two tapes;
Fig. 8 shows a portion of the tape-splicing unit in
more detail;
Fig. 9 shows part of an empty reel detection system;
Fig. 10 shows part of another detection system;
Fig. 11 shows a schematic diagram of a control
system.
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Turning to Fig. 1, this shows generally at 10
a tape dispensing unit in accordance with an embodiment
of the present invention, feeding tear tapes 12, 13, to a
continuous portion of packaging material 14. The portion
of packaging may be, for example, in a printing machine,
so that commercial graphics and other information may be
printed thereon. The dispensing unit may be located
outside the printing machine. The tear tape is applied
to the packaging portions so that consumers may easily
open the assembled packages. In this example, two tapes,
each of which is a self-wound pressure sensitive tear-
tape, having one surface coated in pressure-sensitive
adhesive and having the other, opposed surface coated in
a silicon release coating, are applied to the packaging
portion 14. This portion will subsequently be cut into
individual packaging portions, each of which will
eventually form a package. In practice a larger number
of tapes can be applied in this way (for example 6
tapes). Tape is applied to the packaging from a reel. A
reserve reel also holding tape is provided. When the end
of the tape on the reel in use is reached the tape
dispensing unit splices together the end of the tape in
use with the beginning of the reserve reel, so that tape
is fed continuously to the packaging material.
Fig. 2 shows the dispensing unit 10 of Fig. 1 in
more detail, where tapes 12, 13 are being dispensed from
the machine 10. For each of tapes 12, 13 there are two
servo-assisted motor-driven dispenser reels 16a, 16b.
The tape from these reels is conveyed to a splice unit 18
via accumulators 20. The splice unit ensures that a
continuous supply of tape is dispensed from the
dispensing unit 10, even when the supply from one of the
reels 16a, 16b becomes exhausted. A control cabinet 22
is disposed on the side of the dispensing unit 10. The
function of this will be described later.
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Fig. 3 shows the splice unit 18 of Fig. 2 in more
detail. Two tapes 12a and 12b are fed into the splice
unit. In this example, the upper tape 12a is in use -
i.e. it is currently being applied to the packaging (not
shown). It is fed through the splice unit, and onto an
accumulator. It is then fed out of the machine and
applied to packaging, as shown in Fig. 1. The lower tape
12b is in the standby position. It is manually fed into
the splicing unit by an operative, and the leading edge
is held in place by a vacuum shoe 26b.
Fig. 4 shows a perspective view of the splicing
unit with the tape 12b in the standby position, resting
on the vacuum shoe 26b. The tape is prevented from being
accidentally drawn back onto its supply reel by a one-way
tape-clamp roller 28b and a roller 30b.
Fig. 5 shows a perspective view of the splicing
unit with the upper tape 12a in use. The tape is guided
by a roller 30a, and passes over a tape guide roller 32.
The splicing unit has upper and lower parts 18a, 18b,
carrying the upper and lower tapes 12a, 12b respectively.
When the control unit 22 determines that the supply of
the upper tape 12a has almost finished, the upper and
lower portions of the splicing machine 18a, 18b are
pressed together.
Fig. 6 shows the splicing unit when the upper and
lower portions are brought together. A pneumatic
actuator 33a, 33b is connected to each of the upper and
lower section of the splicing machine to enable the two
sections to be pressed together. The upper tape,
currently in use 12a is pressed against the lower,
reserve tape 12b by nip rollers 34a, 34b. The upper and
lower nip rollers are provided with appropriate coatings
to prevent them from sticking to the surfaces of the
tapes with which they are in contact. The calculated
force at the point of joining the two tapes together
between the nip rollers is in the region of 175N. The
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pressure sensitive adhesive coating of one tape adheres
sufficiently well to the release coating of the other
tape and over a sufficient length, such that one tape may
pull the other.
After a suitable time has elapsed the upper tape
12a is cut against an anvil 36, by a cutter 38a. The
leading edge of the lower tape is now attached to the
trailing edge of the upper tape 12a and the former is
drawn out of the splicing machine, The reel dispensers
are motorised since the new reel will have a large amount
of inertia. This reduces the risk of the tape breaking
under the tension caused by acceleration. Furthermore,
each tape runs from its dispenser to an accumulator. The
accumulator has the effect of accelerating the tape
slightly before splicing occurs, and allows the length of
the tape path to decrease slightly after splicing has
occurred, to reduce the effect of the tension caused by
the acceleration.
After the spent upper tape 12a is cut, the nip
rollers are drawn apart again after a suitable time to
ensure that the tapes are properly adhered together. The
lower tape 12b is now fed onto the packaging material.
Then, a new reel of tape will be fitted in place of the
spent reel, and the leading edge of this tape drawn out
and placed on the vacuum shoe 26a. A corresponding
process will be carried out when the lower tape 12b
currently in use runs out. Accordingly, this process can
be carried out indefinitely without stopping the machine,
which would lead to costly "down-time" and reduce
productivity.
Fig. 7 shows the two portions of the upper and
lower tape 12a, 12b spliced together. The top diagram
shows how the tapes are spliced together in the case of
the splicing discussed in relation to Fig. 6 (i.e. where
the upper tape 12a is replaced with the lower tape 12b).
The old upper tape 12a has pressure sensitive adhesive 40
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on its underside. This sticks to the non-adhesive side
of the new lower tape 12b. Part of the packaging
material will have a portion of tape in which there is a
double thickness of tape, as shown in Fig. 7. However,
this portion of tape will not be able to function as a
tear tape because the adhesive bond between the two
portions of tape is not strong enough to adhere the
portions together when the tape is torn through
packaging. The average breaking strength of a splice of
two self-windable tapes with an overlap of 70mm is 4.2
kg. This weak bonding is necessarily the case, since in
the case of self-wound tape one side of the tape is
coated with a release coat which prevents the surface of
the tape coated with pressure sensitive adhesive from
sticking to its adjacent winding too strongly.
Accordingly, the portion of the packaging which carries
this double thickness of tape must be located and
discarded. The lower diagram in Fig. 7 shows the
positioning of the tapes if the lower tape 12b is in use,
and a new upper tape 12a is to be spliced thereon. In
either case the adhesive 40 on the underside of the upper
tape 12a adheres the tapes together.
Fig. 8 shows a perspective view of one of the
portions of the splicing machine 18b in more detail. The
tapes are clamped in the reserve position by a clamp
roller 28b and a tape guide roller 30b. These rollers
are positioned by a pneumatic cylinder 42. The cutter
38b, which is arranged to cut an almost spent tape which
has been spliced, is a rotary cutter. The cutter and the
nip rollers 34b are moved by a pneumatic actuator 33b.
This allows the nip rollers of the upper and lower
portions of the splicing unit 18a, 18b to be moved
together and apart, to perform the splicing action. The
vacuum shoe, or guide block 26b has a channel, with small
holes disposed therein. The vacuum shoe is held at a
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slightly negative pressure; hence the holes will draw the
tape to the shoe and hold it thereon.
Fig. 9 shows a detection system mounted on the
wall of the dispensing unit. This detection system
detects the radius of a reel of tape 44 so that the
splicing unit can be activated when the amount of tape on
the reel in use falls to a low level. An arm 46 is
pivotally mounted on the case of the detection unit.
This arm rests on the circumference of the reel. A metal
target 48 is housed on the arm 46. As the tape on the
reel is used, the diameter of the reel decreases and the
arm falls. An inductive sensor 50 is located in the
proximity of the arm, and when the arm falls the metal
target moves near the inductive sensor 50. When the
inductive sensor senses that the arm has fallen by a
certain amount, a signal can be sent to order the
splicing unit to activate, hence splicing the new,
reserve tape and preventing the supply of tape from
running out. An accumulator arm 20, balanced by an
adjustable weight 52 can also be seen in this diagram.
Fig. 10 shows another, alternative detection
system. This system also involves an arm pivotally
mounted on the case of the detection unit. In this case
the arm is connected to a potentiometer 54. The position
of the arm is converted to a DC output by the
potentiometer, between 0 and 10 V. This input can be
used to derive information about the amount of tape left
on the reel, and may detect as little as one tape
thickness remaining on the reel. Similarly to the case
above, if the amount of tape left on the reel is
sufficiently small the controller can instruct the
splicing unit to splice the new, reserve tape. Fig. 10
also shows an additional potentiometer 56. This can be
used to control the speed of the motor 58 which drives
the main shaft onto which the reel of tape is mounted.
As mentioned above, a full reel of tape has a relatively
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large amount of inertia. Accordingly, a relatively large
force must be applied to the tape to accelerate the reel
to the required speed. Therefore there is a danger of
the tape breaking if it is subjected to a large
acceleration. In order to reduce the momentary force on
the tape, the tape dispenser is provided with a motorised
spool 60. As mentioned earlier the tape may also be
conveyed via an accumulator, which can provide a variable
tape path, which shortens when the tape is subject to
higher tension.
Fig. 10 also shows an inductive sensor 62 for
detecting whether a tape is missing. A suitable signal
or alarm can be activated to alert an operator to the
absence of tape.
It may be necessary to slow the speed of the
machinery when the tape is spliced, depending on the
running speed of the machinery. Printing machines, which
may use such dispensing units may run at about 4mls
(800ft/min), whereas currently splicing can only be
performed at 2m/s (400ftJmin). The motorised reel on the
tape in use can be slowed to accommodate this change in
speed; when the potentiometer senses that the tape on the
reel is running low, i.e. the machine is about to perform
splicing, the reel and therefore the tape can be driven
at a lower speed. When the splicing action is completed
the reel can again be driven at the usual speed.
Fig. 11 shows a schematic diagram a control
system which can be utilised by the dispensing unit.
Digital inputs relating to various information are fed
into the programmable logic controller. The information
can include, for example: whether the top or bottom tape
has been selected (with a push-button); whether the end
of the reel has been sensed with a inductive sensor 50;
whether a reel of tape is missing, as sensed by a
inductive sensor 62; or whether the nip rollers are in an
open or closed configuration, as sensed by a reed switch
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on a pneumatic actuator 33a, 33b. Analogue inputs such
as those received by the inductive sensor shown in Fig. 9
or the potentiometers shown in Fig. 10 are also fed into
the programmable logic controller. The controller can
then control various activities of the dispensing
machine. For example, when the voltage output by the
potentiometers reaches a certain level corresponding to
an almost empty reel the pneumatic actuators attached to
the upper and lower portions of the splicing machine are
activated to draw the nip cylinders on the upper and
lower portions of the splicing unit together, so that
splicing may take place. Furthermore, a signal may need
to be sent to the pneumatic cylinder controlling the
position of the clamp roller and the tape guide roller
clamping a tape in the upper or lower clamp roller, so
that the tape can be released in preparation for
splicing. Similarly, a signal to turn off the vacuum on
the upper or lower vacuum shoes, to prevent the vacuum
from holding the leading edge of a reserve tape may need
to be sent. A signal may also need to be sent to the
upper or lower rotary cutter so that the upper or lower
tape may be cut after splicing.
Accordingly, the detection of the amount of tape
remaining on the reel can be performed automatically, and
this information can be used to perform the splicing of
the tape in use to the reserve tape automatically.
However, these functions could also be performed
manually.
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