Note: Descriptions are shown in the official language in which they were submitted.
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APPARATUS AND METHOD FOR STABILIZING A MOVING WEB RELATED
APPLICATION
[0001] Continue to next paragraph.
BACKGROUND OF THE INVENTION
[0002] Webs of material (including but not limited to
tissue, towel, paper, board, plastics, and polymers) are
transported through spans that typically have web stabilizers,
such as shown in U.S. Patent No. 4,321,107 and U.S. Patent No.
5,738,760. The webs move at a relatively high speed through
the spans and across the stabilizers.
[0003] As the web moves across the flat surface of these
stabilizers, the side edges of the web tend to curl. Curling
may increase the stresses applied to the web, especially at
the web edges. Curling may result in non-uniform stretching of
the web across the width of the web and increase the risk of
web tearing. The side edges most commonly curl away from the
stabilizers due to web tension, gravity, differences in
material properties, outside influences such as air currents,
and the fact
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that the material on the web ends is connected to other web
material only on one side of the web. There is a need for
devices and methods to reduce curling at the side edges of
webs.
[0004] Other configurations have been proposed, such the
one(s) described in U.S. Publication No. 2010/0213305 filed on
January 28, 2010.
BRIEF DESCRIPTION OF THE INVENTION
[0005] To minimize web curling, at least two forces are
applied: at least one force is applied to the outside sheet
edge region of the stabilizer; and at least one force is
applied to the main body of the web.
[0006] The force is applied to the outside sheet edge
region of the stabilizer to draw the side edge of the web to
the stabilizer. By drawing the side edge of the web to the
stabilizer, the edges of the web are kept in-line with other
portions of the web moving across the stabilizer. Minimizing
curling of the side edges reduces stresses in the web
material, reduces web breaks and may improve characteristics
of the web material because the side ends are subjected to
less stress and stretching.
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[00071 The force applied to the outside sheet edge region
of the stabilizer may be formed by air movement away from
the web edge. For
example, compressed air or a vacuum
may be applied at or near the sheet edge to draw air from
the edge of the web to create a suction pushing the edge
of the web towards the stabilizer. To
create the
suction, air may be forced or drawn through a gap at the
sheet edge. The gap
is generally parallel to and
adjacent the side edge of the web. As the
air flows
through the gap, a pressure drop forms at the sheet edge
that draws the side edge of the web towards the sheet
edge of the stabilizer.
[0008]To create the force applied to the side edge of the
web, the air movement over the sheet edge is preferably
in a direction flowing away from the web, perpendicular
to the sheet edge, and aligned with the intended
elevation of the web. The air
movement may be directed
in other directions, including towards or away from the
stabilizer. The air
flow should create a low pressure
between the web and the sheet edge of the stabilizer such
that the low pressure pulls the side edges of the web
towards the sheet edge.
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[0009] The force is applied to the main body of the web to
inhibit the web from fluttering as it passes near the
stabilizer. To create the force applied to the side edge
of the web, the air movement over the sheet edge is
preferably in a direction flowing parallel or
substantially parallel with the flow of the web. The air
movement may be directed in other directions, so long as
some vector of the air flow is concurrent with the
direction of web travel. The air
flow should create a
buffer zone between the web and the stabilizer such that
fluttering of the web is inhibited.
BRIEF DESCRIPTION OF THE DRAWINGS
[0010]FIGURE 1 is a schematic diagram of a web stabilizer
in accordance with an aspect of the present invention.
[0011] FIGURE 2 is a schematic side-view diagram of a web
stabilizer in accordance with an aspect of the present
invention.
[0012] FIGURE 3 is a schematic cross-sectional diagram of a
web stabilizer in accordance with an aspect of the
present invention.
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DETAILED DESCRIPTION OF THE INVENTION
[0013]FIGURES 1-3 are schematic diagrams of a web
stabilizer 100 and a web moving below the stabilizer. A
moving fluid, preferably a gas such as air, is introduced
along two portions: substantially widthwise near the
outside edge of the web and substantially lengthwise
along the stabilizer.
[0014]As indicated by the arrows (which indicate the
direction of airflow), gaps 102 may introduce air
substantially perpendicular to the direction of web
travel. Although
illustrated as perpendicular to the
direction of web travel (i.e., at 90 as measured from the
direction of web travel), any suitable angle may be
employed. For
instance, the "side air" introduced via
the gaps 102 at the sides of the web travel may be at any
angle between 0 and 90 (such as at substantially 75 ) or
even any angle at 90 60 as measured from the direction
of web travel.
[0015]Similarly as indicated by the arrows (which again
indicate the direction of airflow), gaps 104 may
introduce air substantially parallel to the direction of
web travel (i.e., substantially at 0 as measured from the
direction of web travel). Other
suitable angles may be
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employed. For
instance, the "step air" may be at any
angle +900 as measured from the direction of air travel.
[0016] The stabilizer 100 may be designed to handle any
suitable size of web, such as webs that are approximately
212 inches wide. Smaller
and larger widths are
contemplated, and the precise width of web is relatively
unimportant to aspects of the present invention.
[0017]The moving fluid (e.g., air) introduced via gaps 102
and gaps 104 create forces that stabilize the web,
possibly inhibiting curling and/or fluttering. Reducing
curling and/or fluttering should, in many instances,
reduce sheet breaks and improve performance and the speed
potential of the web machine.
[0018]The machine may be employed in a process for making
tissue, towel, paper, board, plastics, and/or polymers.
It may be possible to use at least certain embodiments in
connection with making sheets of malleable metals or
other thin films.
[0019]The stationary web stabilizer 100 may be a generally
rectangular device having a substantially flat bottom
surface, as more fully described herein. The web
generally moves at a high velocity over the flat bottom
surface. The movement of the web creates a pressure
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difference on opposite sides of the web that draws the
web towards the surface. The
center portion of the web
may be adjacent the bottom of the stabilizer. The side
edges of the web may curl away from the bottom of the
stabilizer. There is
a desire to eliminate the curling
and force the side edge into the same plane as the center
portion of the web.
Furthermore, there is a desire to
simultaneously stabilize the center portion of the web.
[0020]To remove the curl of a side edge of the web, a
moving fluid, e.g., air, is directed away from the side
edge to generate a transverse force applied to the side
edge and, at the same time, a moving fluid is directed in
the direction of web travel to generate a congruent force
applied to the web. The transverse force causes the side
edge of the web to move towards the outer edges of the
stabilizer, while the congruent force prevents the web
from impacting the stabilizer.
[0021] The term "air" is used to refer to a moving fluid
that is preferably atmospheric air but may be other gases
and liquids and includes using vacuum or other negative
pressures. In some
embodiments, for example, the moving
fluid may alternatively comprise inert or substantially
inert gasses (e.g., noble gasses, nitrogen, etc.) may be
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used. And in
some embodiments, the moving fluid may
facilitate a reaction in or on the web. For
instance,
the use of oxygen may facilitate an oxidation reaction on
the web surface.
[0022] The air may flow through any suitable configuration
of tubes and/or pipes and may be delivered and/or
controlled separately with respect to gaps 102 and 104.
In some instances, at least one hollow beam with air
nozzles delivers air to gaps 102 and/or 104.
[0023] Gaps 102 and/or 104 may include air knives, pipes,
beams or bars with internal air passages and air nozzles
formed by drilled holes or slots along the length of the
device. The devices are preferably mounted on or in the
vicinity of a bottom surface of the stabilizer 100 and,
particularly, at or outside the sheet edge region of the
bottom surface and along the width of the stabilizer 100.
Alternatively, the stabilizer may be positioned below the
web and have an upper surface adjacent the web, where the
air movement device is mounted on top of the upper
surface. The surface of the stabilizer adjacent the web
may be flat, arched, contoured or have other shape which
faces the web.
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[0024] The air movement through gaps 102 and/or gaps 104 is
at a pressure and velocity sufficient to influence the
position and orientation of the web edges and web body
such that the entire web, including the web's edges, is
rendered more stable from the reduced flutter and curl.
[0025] The surface of the stabilizer 100 adjacent the web
may be smooth or rough, a bottom (or top) surface and a
planar surface.
[0026] Air through gap 102 may be introduced beyond the
web's edge in a horizontal dimension, such in a range of
zero to twelve inches from the web edge. The air may be
introduced such that the air flows along the surface of
the stabilizer. In some
embodiments, the air flows away
from edge of the web in a direction substantially
parallel to the surface of the stabilizer.
[0027] FIGURE 2 schematically illustrates a side-view of
stabilizer 100 showing gaps 106 and 108 for "side air"
supplied at least partially perpendicularly to the
direction of web travel (as shown by the arrow). The
side air stabilizes the edges of the web during
operation, and the holes or perforations 110 and 112 in
gaps 106 and 108 supply the air in a direction at least
partially orthogonal to the side-view depicted (i.e., the
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air through holes or perforations 110 and 112 are
directed partially towards the viewer). Gaps 106 and 108
are defined by the difference in location of surfaces 130
and 132. The web stretches along the width of stabilizer
100 in a plane substantially parallel to surfaces 130 and
132.
[0028] As schematically illustrated in the cross-sectional
view of FIGURE 3, gaps 116 and 114 supply the "step air"
in the direction of web travel. Gaps 116 and 114 may be
of any suitable height, such as, for example, any height
in the range of 1/16" to 3/4" (or greater). These
gaps
may have a number of holes or perforations that supply
air to stabilize the web during operation. For instance,
there may be thousands, e.g., about 3600, of perforations
for each step. These
holes or perforation may each be
about 0.001" in diameter or larger (e.g., 0.01").
[0029]Although only two gaps are illustrated, alternative
embodiments may include a single gap supplying "side
air." In
addition, other embodiments may include three
or more gaps for supplying side air. It may
be
preferable to have the same number of slots supplying
"side air" as supplying "step air".
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[0030] As illustrated, surfaces 130 and 132 have a stepped
configuration, in which the gaps 116 and 114 that supply
the "step air" alter the surface of the stabilizer 100.
The surfaces 130 and 132 are discontinuous to the
direction of the web travel, and the direction of the web
travel is substantially parallel to the stepped surfaces
130 and 132.
[0031] Shafts 118, 120, 122, 124, 126, and 128 supply a
fluid (e.g., air) individually, selectively, and/or
collectively to both the gaps for side-air and step-air.
These shafts may additionally or alternatively provide
mounts for mounting the stabilizer in place. The shafts
are connected to gaps 102 and 104 by any suitable
equipment, such as, for example, hoses, pipes, etc.
[0032]While the invention has been described in connection
with what is presently considered to be the most
practical and preferred embodiment, it is to be
understood that the invention is not to be limited to the
disclosed embodiment, but on the contrary, is intended to
cover various modifications and equivalent arrangements
included within the spirit and scope of the appended
claims.
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