Note: Descriptions are shown in the official language in which they were submitted.
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DRIVEN LAYON ROLLER APPARATUS FOR FILM OR SHEET WINDERS
BACKGROUND
[0001]The present invention pertains to a layon roller for a plastic film or
sheet
winder. The layon roller is driven in rotation by a coupling to a drive source
where
the coupling enables the layon roller to float on the roll of film or sheet
wound on the
winder and maintain a very precise and accurate pressure on the roll.
DESCRIPTION OF THE RELATED ART
[0002]One critical process when producing film products such as a plastic film
or
sheet is the ability to be able to wind the final product plastic film or
sheet into rolls.
The process of winding plastic film or sheet into rolls is done in a machine
called a
winder. There are many different types of winders, and they all use specific
characteristics to achieve different properties in the rolls of film or sheet
wound on
the winders.
[0003]A basic type of plastic film or sheet winder is a center winder such as
that
represented schematically in Figure 1. In a center winder of the type shown in
Figure 1 the shaft of the winder is driven in rotation and a torque produced
by the
winder rotation is transmitted through the roll of film or sheet wound on the
winder to
the surface of the roll. The torque exerts a pulling force on the film or
sheet being
gathered onto the roll. In a center winder such as that shown in Figure 1,
either the
torque of the winder shaft or the speed of the winder shaft or a combination
of both is
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varied to adjust the tensile force in the film or sheet being wound on the
winder and
maintain the tensile force in the film or sheet substantially constant.
[0004] In order to control variables of the film or sheet being wound on the
roll on
the winder, for example air entrapment between the film or sheet and the
exterior of
the roll, a second idle roller known as a layon roller is positioned against
the roll on
the winder where the film or sheet is being wound onto the roll. The layon
roller
applies a force on the roll wound on the winder. This is represented in Figure
2. The
applied force of the layon roller on the roll wound on the winder is commonly
generated by pneumatic pressure, but other electrical devices and mechanical
or
hydraulic devices can be used to cause the layon roller to apply a force on
the roll
being wound on the winder.
[0005] When designing layon rollers that are used with film or sheet winders
such
as that represented in Figure 2, it is crucial that the layon roller have the
ability to
maintain very precise and accurate pressure that is applied by the layon
roller to the
exterior surface of the roll of film or sheet being wound on the winder. To
accomplish this precise and accurate control of the pressure applied by the
layon
roller, a "floating" type layon roller is often used with a film or sheet
winder. A
"floating" type layon roller has very low inertia and friction, and employs a
torque
tube or similar device to maintain axial alignment of the layon roller torque
tube axis
of rotation with the axis of rotation of the winder. The layon roller is free
to ride on
the surface of the roll being wound on the winder as the roll grows in
diameter or
circumference, and thereby the layon roller maintains a substantially constant
applied force to the surface of the roll being wound on the winder.
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[0006] In order to maintain tension in the plastic film or sheet being pulled
toward
the winder as the film or sheet accumulates on the roll being wound on the
winder,
the torque required to rotate the center shaft of the winder increases due to
the
effective diameter increase of the roll on the winder. However, the increased
torque
required to rotate the roll being accumulated on the winder is transmitted
through the
accumulated layers of the film or sheet wound on the winder and is inherently
detrimental to the final roll characteristics.
SUMMARY
[0007] To have better control of the tension in the film or sheet being wound
on the
roll on the winder it is necessary to remove the variable torque being
transmitted
through the roll on the winder. Another torque transmission with a constant
force
distance relative to the roll wound on the winder must be provided. This can
be done
by adding torque to the layon roller. This is known as center surface winding
and it
is represented in Figure 3.
[0008] Although applying a torque to the layon roller is a straight forward
concept,
the process of adding a power transmission to apply torque to the layon roller
has a
major side effect. Adding a drive transmission to the layon roller to supply
torque to
the layon roller removes the ability of the layon roller to still be able to
float freely on
the surface of the roll being wound on the winder. This in turn removes the
ability of
the layon roller to maintain a very delicate and precise pressure against the
film or
sheet roll being wound on the winder.
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[0009] The present invention overcomes this problem by providing a layon
roller
having a coupling to a source of rotation where the coupling makes use of a
magnetic flux field to transmit rotation to the layon roller. The coupling is
basically
comprised of first and second magnets that are adjacent, but not physically
connected. Rotation of the first magnet causes rotation of the second magnet
through the magnetic flux field. In this way the coupling enables the layon
roller to
transmit torque to the roll being wound on the winder while still being able
to float on
the roll and maintain a very precise and accurate pressure on the roll.
BRIEF DESCRIPTION OF THE DRAWINGS
Further features of the invention are set forth in the following detailed
description of
the invention and in the drawing figures.
[0010] Figure 1 is a schematic representation of a plastic film or sheet
center
winder.
[0011] Figure 2 is a schematic representation of a plastic film or sheet
center
winder with a layon roller.
[0012] Figure 3 is a schematic representation of a plastic film or sheet
center
winder with a layon roller where torque is being applied to the layon roller.
[0013] Figure 4 is a partial perspective view of one advantageous embodiment
of
the driven layon roller for a film or sheet winder of the invention.
[0014] Figure 5 is a partial elevation view of the layon roller of Figure 4.
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DESCRIPTION
[0015] Figure 4 shows the driven layon roller for a film or sheet winder of
the
invention 10. The driven layon roller of Figure 4 isolates forces associated
with
transmitting rotation power or torque to the layon roller and thereby
maintains the
ability of the layon roller to provide very delicate and precise pressure
against the roll
wound on the winder.
[0016] The driven layon roller of the invention shown in Figure 4 has a unique
coupling that allows for torque to be transmitted to the layon roller to
rotate the layon
roller while adding little or no inertia and imposing little or no radial
forces to the
layon roller as the layon roller moves position relative to the winder.
[0017] The unique coupling of the invention 10 shown in Figure 4 is a magnetic
coupling. The magnetic coupling uses magnetic forces to transmit torque to the
layon roller, but still allows for axial and parallel misalignment, with
minimal effect on
the delicate and precise pressure exerted by the layon roller on the roll of
film or
sheet wound on the winder.
[0018] Referring to Figures 4 and 5, the driven layon roller apparatus 10 of
the
invention includes a supporting frame 12, as is conventional. In Figures 4 and
5 only
the right hand side of the frame is shown. In the illustrative embodiment
shown, the
coupling of the invention is located at the right side of the frame. However,
it could
also be located at the left side. A cylindrical stub shaft 14 projects from
the side of
the frame 12 into the frame interior. The cylindrical stub shaft 14 surrounds
an
opening 16 through the side of the frame 12. A pair of bearing assemblies 18
are
mounted on the exterior surface of the stub shaft 14. A generally cylindrical
drive
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hub 20 is mounted on the pair of bearing assemblies 18 and rotates on the stub
shaft
14.
[0019] A transmission drive assembly rotates the drive hub 20 on the stub
shaft 14.
In the embodiment of the apparatus shown in Figures 4 and 5, the drive
transmission
is comprised of a driven sprocket 22 secured on the drive hub 20, a drive
sprocket
24 and a chain 26 looped around the driven sprocket 22 and the drive sprocket
24.
Although a sprocket and chain drive transmission is shown in Figures 4 and 5,
other
equivalent types of drive transmissions can be employed in the apparatus to
selectively rotate the drive hub 20 on the stub shaft 14.
[0020]A central shaft 28 is supported on the frame 12. Although only the right
hand
end of the shaft 28 is shown in Figures 4 and 5, the left hand end of the
shaft is
supported by the frame 12 in a similar manner to that of the right-hand end of
the
shaft to be described. The shaft right hand end 30 extends into a pivoting
shaft
support 32 that in turn is mounted in the opening 16 of the frame 12. The
shaft end
30 is mounted in a cylindrical portion 32 of the pivoting shaft support. As
shown in
Figures 4 and 5, the cylindrical portion 32 of the shaft support is slightly
smaller than
the frame opening 16. A flange portion 34 of the pivoting shaft support
extends
radially outwardly from the cylindrical portion 32. A pivot pin 36 connects
the flange
portion 34 to the frame 12 and enables the pivoting shaft support to pivot in
the
frame opening 16 relative to the frame.
[0021]A pivot actuator 38 is connected between the frame 12 and the flange
portion
34 of the shaft support. Selective extension and retraction of the pivot
actuator 38
causes the flange portion 34 of the shaft support to pivot about the pivot pin
36, and
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thereby causes the central shaft 28 to move in a pivoting movement relative to
the
frame 12. The pivoting movement of the central shaft 28 selectively moves the
shaft
away from and toward a roll of film 40 wound on a shaft positioned adjacent
the
apparatus of the invention.
[0022] A bearing assembly 42 is mounted on the central shaft 28 adjacent its
right
hand end 30. A similar bearing assembly is mounted on the shaft 28 adjacent
the
left hand end of the shaft. A pair of support discs 44 are mounted on the
bearing
assemblies 42. The bearing assemblies 42 enable the support discs 44 to rotate
freely on the central shaft 28.
[0023]The pair of support discs 44 support the cylindrical layon roller 46 for
rotation
of the roller on the central shaft 28. The layon roller 46 has a cylindrical
exterior
surface 48 and an opposite cylindrical interior surface 50 that surrounds a
hollow
interior volume 52 of the roller. The layon roller 46 has an axis of rotation
that is
coaxial with the center axis 54 of the central shaft 28.
[0024]A driven hub is mounted to the support disc 44 adjacent the right hand
end of
the central shaft 28. The driven hub has an annular flange portion 56 that is
secured
to the support disc 44 to rotate with the support disc. The hub also has a
cylindrical
portion 58 that extends axially from the annular flange 56 and extends around
the
central shaft 28. The hub cylindrical portion 58 is spaced radially outwardly
from the
central shaft 28, whereby the driven hub is free to rotate around the central
shaft.
[0025]As stated earlier, the driven layon roller apparatus has a unique
coupling that
allows for torque to be transmitted from the drive hub 20 to the layon roller
46 to
rotate the layon roller while adding little or no inertia and imposing little
or no radial
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force to the layon roller as the layon roller pivots relative to the roll of
film 40. The
unique coupling is a magnetic coupling. The magnetic coupling uses magnetic
forces to transmit torque to the layon roller 46, but still allows for axial
and parallel
misalignment, with minimal effect on the delicate and precise pressure exerted
by
the layon roller 46 on the roll of film or sheet wound on the roll of film 40.
[0026]The magnetic coupling includes a magnetic first coupling piece 62. In
the
preferred embodiment the first coupling piece 62 is a permanent magnet.
However,
in other embodiments the first coupling piece 62 could be an electromagnet.
The
first coupling piece 62 has a general cylindrical configuration with a
cylindrical
exterior surface 64 that is secured inside the drive hub 20 for rotation of
the first
coupling piece 62 with the drive hub. The first coupling piece 62 also has a
cylindrical interior surface 66 that surrounds and is spaced from the central
shaft 28.
Other configurations of the first coupling piece could be employed. The
exterior 64
and interior 66 cylindrical surfaces have a center axis of rotation. The
center axis of
the first coupling piece 62 is parallel with the layon roller axis of rotation
54, but is not
necessarily coaxial with the layon roller axis of rotation due to the ability
of the layon
roller to move in pivoting movements about the pivot pin 36. The first
coupling piece
62 also has a flat annular surface 70 that faces toward the driven hub
cylindrical
portion 58.
[0027] The magnetic coupling also includes a magnetic second coupling piece
72. In
the preferred embodiment the second coupling piece 72 is also a permanent
magnet. The second coupling piece 72 is basically a mirror image of the first
coupling piece 64. The second coupling piece 72 also has a cylindrical
exterior
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surface 74 and an opposite cylindrical interior surface 76. Again, other
configurations of the second coupling piece could be employed. The cylindrical
interior surface 76 is secured to the driven hub cylindrical portion 58
whereby the
second coupling piece 72 rotates with the driven hub, the support disc 44
secured to
the driven hub, and the layon roller 46 mounted on the support discs. The
second
coupling disc 72 also includes a flat annular surface 80 that opposes and is
parallel
to the flat annular surface 70 of the first coupling piece 62.
[0028]The first coupling piece flat annular surface 70 and the second coupling
piece
flat annular surface 80 are parallel and axially spaced from each other with
there
being nothing but a void or empty space 82 between the two surfaces. However,
the
two surfaces 70, 80 are sufficiently close for the two magnets 62, 72 to
produce
magnetic flux that passes through the empty space 82 between the two magnets.
[0029]On rotation of the first coupling piece 62 by the driven sprocket 22,
the
magnetic flux in the empty space 82 between the first coupling piece annular
surface
70 and the second coupling piece annular surface 80 imparts a rotation torque
to the
second coupling piece 72 which in turn is transmitted to the layon roller 46.
However, because the first coupling piece 62 and the second coupling piece 72
are
not physically connected and do not make physical contact, the layon roller 46
is free
to float and pivot while simultaneously providing torque to the plastic film
or sheet
being wound on the roll of film 40. All forces associated with the power
transmission
from the driven sprocket 22 are isolated by the sprocket and the drive hub 20
that
are mounted for rotation on the stub shaft 14 of the frame 12.
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[0030]Although the drive transmission shown in Figures 4 and 5 is a sprocket
and
chain assembly, the concept of the invention would work equally well
regardless of
the initial power transmission. For example, the sprocket and chain assembly
could
be replaced with a pulley and belt drive or with a spur gear drive.
[0031]Another unique feature of the driven layon roller apparatus 10 of the
invention
is the positioning of the first magnetic coupling piece 62 and the second
magnetic
coupling piece 72 internally inside the hollow interior volume 52 of the layon
roller 46.
This provides a space saving option. Additionally, the first magnetic coupling
piece
62 could be located outside the interior volume of the layon roller 46 with
the second
magnetic coupling piece 72 being positioned inside the hollow interior of the
roller.
Still further, both the first 62 and second 72 magnetic coupling pieces could
be
located outside the interior volume of the layon roller 46.
[00321Although the layon roller of the invention has been described as being
used
with a plastic film or sheet winder, the layon roller would work equally well
in other
areas of substrate winding, for example winding a paper web, and the layon
roller of
the invention should not be interpreted as limited to use with only plastic
film or sheet
winders. Additionally, the magnetic couple could be used in other
applications, for
example on a surface winder.
[0033] As various modifications could be made in the constructions of the
apparatus
herein described and illustrated without departing from the scope of the
invention, it
is intended that all matter contained in the foregoing description or shown in
the
accompanying drawings shall be interpreted as illustrative rather than
limiting. Thus,
the breadth and scope of the present invention should not be limited by any of
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above described exemplary embodiments, but should be defined only in
accordance
with the following claims appended hereto and their equivalents.
