Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
CA 02447498 2004-11-19
ANTI-FALL OFF SYSTEM AND METHOD
BACKGROUND OF THE INVENTION
FIELD OF THE INVENTION
This invention relates to an improvement in a system and method for dispensing
a tape, i.e.,
ribbon, web or string, generally referred to herein as "tape", when the tape
is being unwound at a
laminating machine such as a corrugating machine or press. One aspect of the
present invention
is to prevent the tape from falling off the edge of the tape package when
unwinding. Another
aspect is to prevent the tape from twisting in the dispensing equipment.
DESCRIPTION OF THE PRIOR ART
Reinforcing or Tear tapes have been used for many years in modern packaging as
an aid to
maintain structural integrity or as an easy open feature in boxes, packages
and/or containers.
One limitation of the dispensing equipment used at the laminating machine is
the difficulty to
prevent the tape from falling off the edge of the tape package. To be able to
put a reasonable
amount of linear footage on a tape package, the use of a cross winding
principle is mandatory, so
for a tape with a width of '/2 inch wide, the tape package can be 13 to 18
inch wide, with a
diameter up to 18 inches. As a result, the tape is wound on the package with a
traverse pattern
so that when the tape is wound around a spindle, at the same time the tape is
moved in a back
and forth movement along the length of the spindle. The ratio between the
numbers of
revolutions of the spindle over the stroke of the tape along the length of the
spindle is known as
the winding ratio. Since the tape can be slippery at room temperature there is
a danger that,
when the tape gets at the edge of the tape package and it stays there until it
changes direction to
go back toward the middle of the package, it can come off the edge of the tape
package and fall
off down to the spindle of the tape package. When that happens, the tape
cannot go back to the
delivering surface of the tape package and the package stops delivering tape
with the result that
the tape breaks.
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To prevent the tape from coming off the edge of the tape package, the tape
industry has used
different techniques such as: adhesive formulation providing added tack
between the layers of
the tape package, fast winding ratios to try to limit the amount of time when
the tape is
positioned near the edge of the tape package, roll flanges made of hard
materials or paper coated
with pressure sensitive adhesives placed on the edges of the tape package to
create a physical
barrier to prevent the tape from falling off the edge of the tape package, and
so on. Each of these
techniques have their drawbacks which can reduce tape performance at the
laminating machine.
For example, increasing the tack of the adhesive formulation of the tape can
diminish the
performance of the tape in the laminating process or can cause other tape
dispensing problems
such as pulleys becoming gummed with adhesive deposits coming from the
adhesive of the tape.
Another example is the tape that can be damaged by the physical barrier on the
edge of the tape
package, when the physical barrier rubs on the sides of the tape package
during shipment.
The literature is abundant with tape dispenser systems and tape splicing
systems for unwinding
tape packages at laminating machines or presses. Often the literature is
describing splicing
system, as all tape must be feed to continuously running processes and since
all tape packages
contain a very limited amount of linear footage, the splicing feature becomes
a critical element.
We can see this in the following patents (or application): US 4,917,327; US
5,029,768; US
2002/0059982; US 6,325,324; US 5,775,629 and US 6,622,959. It would be evident
to someone
outside this industry that the simplest way to diminish the criticality of the
splicing system
would be to increase the amount of linear footage on a tape package. But as
the industry is well
aware, one of the main reason why tape packages are not made larger is that as
the diameter of
the tape package increases, the amount of time that the tape stays at the edge
of the package
increases, thus increasing the dangers of having tape fall offs to a point
where it becomes a
major problem. This invention solves this problem, as any increases in the
tape package
diameter does not increase the occurrence of fall offs.
SUMMARY OF THE INVENTION
The present invention is directed to a system and method using means to
prevent strip material
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such as a tape from falling off the edges of the tape package. An idler roller
is used and
positioned near the unwinding tape package, where the tape, coming off the
tape package when
unwinding, will go around the idler roller and back around the tape package at
least once and
from there to the system dispensing the tape to the laminating machine. In
this manner when the
tape is coming off the tape package, it goes around the idler roller and tape
package combination
at least once before going through the rest of the dispensing system, in
effect creating at least
one loop of tape going around the idler roller tape package combination. This
apparatus and
method prevents the tape from falling off the tape package because the tape
leaving the package
at the nip point of the tape and tape package when unwinding is being pulled
towards the centre
of the tape package by the preceding loop of tape going around the idler
roller tape package
combination. Without that innovation, when the tape leaves the tape package at
the moment the
tape is at it's edge, the tape actually tries to find the shortest route,
which is going off the side of
the tape package; a defect called a fall-off.
With this innovation, we use the fact that the tape is always somewhat
slippery between each of
it's layers on the tape package, so that when the tape first leaves the tape
package during
unwinding, it is pulled away from the edge of the tape package and towards the
centre of the tape
package by the preceding loop of tape around the idler roller tape package
combination, as the
loop of tape around the idler roller tape package combination is ahead in the
winding pattern of
the tape package. Alternatively, when the tape leaves the idler roller tape
package combination
for the last time before going to the rest of the dispensing system towards
the laminating
machine, this tape has already been pulled off the tape package at least once,
thus is loose on the
idler roller tape package combination and is then being pulled towards the
center, away from the
tape package edges by the geometry of the tape dispenser. As a result, the
tape is always pulled
towards the center (length) of the tape package either by the preceding loop
around the idler
roller tape package combination, or by the geometry of the dispenser when the
tape finally
leaves the idler roller tape package combination.
Another improvement resulting of the use of the loop of tape around the idler
roller tape package
combination, is the fact that the tape stays flat at all time during
unwinding, even if the tape is
being pulled to the center of the tape package by the geometry of the tape
dispenser and the
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traverse winding of the tape package, which helps prevent the tape from
twisting further along
the tape dispensing equipment.
These and other novel features of the invention will be more fully described
herein below.
BRIEF DESCRIPTION OF THE DRAWINGS
The present invention will be described with reference to the accompanying
drawing wherein:
FIG. I is a view of the tape package, idler roller and first pulley of tape
dispenser system.
FIG. 2 is a top view of the tape package, idler roller and first pulley of
tape dispenser system.
FIG. 3 is a side view of the tape package, idler roller and first pulley of
tape dispenser system.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
The present invention provides an improved system and method for the
dispensing of a strip
material such as a tape at the corrugating machine or press. A tape package 13
is unwound,
where the tape is wound with a traverse wind ratio as can be seen by the tape
paths 14, 15 and 16
around the tape package 13. The tape 10 first leaves the nip point 17 and
before going to the
pulley 11 of the tape dispensing system, it goes around idler roller 12 and
back around the tape
package 13 idler roller 12 combination at least once, before going to the
pulley 11.
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