Note: Descriptions are shown in the official language in which they were submitted.
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WEB RETENTION APPARATUS AND METHOD FOR CUTOFF BLADE
Field of the Invention
The present invention relates to systems and methods for securing product to
machine surfaces, and more specifically, to apparatus and methods for securing
material
to a machine surface (such as a roll) during and after cutting operations of
the material
on the machine surface.
Background of the Invention
Material cutting is a common operation performed in many industries, including
the paper, textile, plastics, synthetics, and foil industries. Particularly
where material is
in sheet or flat form, a preferred manner employs one or more rolls around
which the
material is passed as it is transversely cut. Certain conventional cutting
systems have a
cutoff roll with one or more surface blades thereon. Material is fed around
the rotating
cutoff roll, and the material is usually either pinched or sheared between a
surface blade
and an anvil blade in close proximity to the cutoff roll. Because the demand
for
processed product is usually high, the speed at which the cutoff roll rotates
and at which
the material moves is also high. However, because certain materials are
inherently
difficult to manipulate and control (especially at relatively high material
speeds), a
number of systems and methods have been developed for releasably holding
material to
the surface of the cutoff roll as the material is pulled around the rotating
cutoff roll.
One such conventional system employs a vacuum system for the cutoff roll. In
this system, a number of holes are located on the exterior surface of the
cutoff roll.
Vacuum applied to the roll in a manner well-known to those skilled in the art
generates
a suction through the holes, thereby holding the material against the surface
of the roll.
By controlling the application of vacuum to selected areas of the roll,
conventional
systems can be operated to hold or release the material at desired times or at
particular
cutoff roll rotational positions. While these systems are effective at
releasably holding
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2
the material, a problem arises in those locations on the cutoff roll which are
near the
cutoff blades on the roll. As shown in Figure 1, material 1 is cut by shearing
between
the cutoff blade 2 on the cutoff roll 3 (which rotates in the direction of
arrow A) and a
nearby stationary anvil blade 4. This cutting produces a trailing edge 5 and a
leading
edge 6 of the cut material 1. For proper material control and manipulation in
later
operations, the leading edge 6 of the material 1 must be held in place on the
cutoff roll
3. If desired, even greater material control and improved manipulation ability
can be
achieved by holding both the leading edge 6 and the trailing edge S of the cut
material 1
in place on the cutoff roll 3.
As will be appreciated by those skilled in the art, if the leading edge 6 is
not
held in place on the cutoff roll 3, the material 1 can "pile up" and even
cause jams in
downstream operations. The leading edge 6 of the cut material 1 is
particularly prone to
piling up behind the severing blade 2. Prior art systems have attempted to
address this
problem in a variety of different ways. Perhaps the most commonly found
solution is to
locate one or more vacuum holes 7 beneath a leading portion or end of the cut
material
1. An example of a system employing such a design is disclosed in U.S. Patent
Number
3,709,088 issued to Trogan et al. Also, U.S. Patent numbers 4,041,816 and
4,080,856
issued to Shearon show a system having two rows of vacuum holes behind the
cutoff
blade for holding the leading end of severed material. While such systems may
be
effective to hold severed material ends in place on a cutoff roll, their
design presents
limitations which the present invention addresses. Specifically, in the design
of the
conventional systems using vacuum holes to hold severed material ends, the
systems
invariably rely upon the vacuum holes to hold the face of the material near
the severed
ends. Because the material can slip on the cutoff roll and may not fall
exactly in the
desired locations over the vacuum holes after being cut, the prior art designs
are not
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3
always effective to prevent piling up of the material ends (and especially the
leading
end of the severed material as shown in Figure 1) near the cutoff blades.
Also, the prior
art designs are inherently limited to operations upon certain types of
material. For
example, the systems disclosed in the Trogan et al. and Shearon patents noted
above
often work poorly with mufti-ply materials, where the vacuum holes exert a
high
holding force on the nearest material ply, but exert a progressively lower
holding force
on overlying plies. Also, these systems can completely fail to work with very
porous
material (which is not very subject to force by vacuum) or with materials
having a ply
with very low porosity underlying one or more other plies (which other plies
are
effectively shielded from the vacuum force by the low porosity ply).
Therefore, a need exists for an apparatus and method which can releasably
secure the severed ends of material to a roll to prevent the ends from piling
up and
jamming downstream equipment and operations, which works well with material of
virtually any porosity, and which can effectively hold all plies of mufti-ply
material to
the roll. Each preferred embodiment of the present invention achieves one or
more of
these results.
Summar~of the Invention
In the present invention, material which has been cut by, for example, a
cutoff
blade on a cutoff roll is held to the surface of the cutoff roll on either or
both sides of
the cutoff blade by a web attraction device. The web attraction device can
take a
number of forms, each of which hold the severed ends) of the material to the
cutoff roll
surface following the cutting operation. The web attraction device exerts an
web
attraction force created by an attraction generator. A preferred web
attraction device is
a vacuum aperture preferably running along at least a portion of the length of
the cutoff
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4
roll and on one or both sides of the cutoff blade. Preferably, the vacuum
aperture is in
the shape of an elongated groove or slot running immediately behind the cutoff
blade.
More preferably, the vacuum aperture runs substantially the entire length of
the cutoff
roll behind the cutoff blade. Most preferably, the vacuum aperture is shaped
and
positioned behind the cutoff blade to receive the leading edge of the severed
material
after it has been cut by the cutoff blade. All plies of the leading edge are
preferably
pulled down into the vacuum aperture rather than merely being held in place on
the roll
surface by vacuum holes.
In this manner, and unlike the prior art devices and systems, the present
invention holds the ends of the cut material better by pulling the edge or
edges of the
cut material into one or more vacuum apertures. Also, all plies of mufti-ply
materials
are thereby secured, and even highly porous materials and mufti-ply materials
having a
very low porosity ply are fully held to the roll. The present invention thus
ensures that
more material types are better secured in place to prevent material pile-ups
and
potential jamming problems in downstream operations.
More information and a better understanding of the present invention can be
achieved by reference to the following drawings and detailed description.
Brief Description of the Drawings
The present invention is further described with reference to the accompanying
drawings, which show preferred embodiments of the present invention. However,
it
should be noted that the invention as disclosed in the accompanying drawings
is
illustrated by way of example only. The various elements and combinations of
elements described below and illustrated in the drawings can be arranged and
organized
differently to result in embodiments which are still within the spirit and
scope of the
present invention.
CA 02372719 2001-11-22
,P~~S 0 9 JUL 2001
In the drawings, wherein like reference numerals indicate like parts:
FIG. 1 is a cross-sectional view of a prior art web retention apparatus for a
cutoff roll;
FIG. 2 is a cross-sectional view of the web retention apparatus according to a
first
preferred embodiment of the present invention;
FIG. 3 is a cross-sectional view of the web retention apparatus according to a
second
preferred embodiment of the present invention;
FIG. 4 is a cross-sectional view of the web retention apparatus according to a
third
preferred embodiment of the present invention; and
FIG. 5 is a cross-sectional view of the web retention apparatus according to a
fourth
preferred embodiment of the present invention.
Detailed Description of Preferred Embodiments
A preferred embodiment of the present invention is illustrated in Figure 2,
which
shows the stage of material cutting operations after a sheet of material 10
has been severed.
The present invention finds particular applicability to cutting operations
performed upon
sheets of paper (such paper used for tissues, toilet paper, napkins, paper
towels, etc.).
However, it should be noted that the present invention also finds
applicability in a number of
other industries in which cutting operations are performed upon virtually any
type of material
which can be found in sheet form. Such materials commonly include other paper
types,
plastic sheeting and the like, and even include cloth, fabrics, textiles,
films, rubber and other
synthetic materials, foils, etc. Therefore, although reference throughout this
specification and
claims is made to a "web" of paper product (the term "web" commonly refernng
to paper
product in sheet form such as toilet paper or napkin stock), the term "web" is
used herein to
refer to any material in sheet form regardless of porosity, method of
manufacture, or
composition, including without limitation paper and paper by-products, cloth,
fabric, textiles,
foils, films, rubber and other synthetic materials, etc.
Web 10 is shown held against the surface 12 of a cutoff roll 14, which itself
is
mounted for rotation near a stationary anvil 16. Herein, it is to be
understood that the
AMENDED SHED
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6
"surface" 12 of the cutoff roll 14 is the outer surface of the cutoff roll 14
in one highly
preferred embodiment (which surface can be interrupted by one or more blades
or
apertures as described below). It will be appreciated by one having ordinary
skill in the
art that the web 10 is severed as it is rotated by turning the cutoff roll 14
past the
stationary anvil 16. The stationary anvil 16 has an anvil blade 18 which
preferably is in
light interference contact with a cutoff blade 20 mounted in a conventional
manner on
the cutoff roll 14. As the cutoff blade 20 passes the anvil blade 18, the web
10 on the
surface 12 of the cutoff roll 14 is severed between the cutoff blade 20 and
the anvil
blade 18. The areas of the severed web 22, 24 which are remote from the cutoff
blade
20 are preferably held against the surface of the cutoff roll 14 in a
conventional manner
(e.g., via vacuum holes in the cutoff roll 14, not shown). However, it is
possible to
secure the web material upon the cutoff roll 14 by only holding the web 10 to
the cutoff
roll 14 behind the cutoff blade 20 in a manner as described below, with the
web
material following behind under a light tension around at least a portion of
the cutoff
roll 14.
After being severed by the cutoff blade 20, a leading web edge 26 and a
trailing
web edge 28 are defined in the web 10 - one on either side of the cutoff blade
20. The
web edges 26, 28 are now free to move with respect to the cutoff roll 14.
Generally,
only the leading web edge 26 has a tendency to move or gather on top of the
cutoff roll
14 due to the rotational direction of the cutoff roll 14. Therefore, the
present invention
finds particular applicability to the area behind the cutoff blade 20.
However, it should
be noted that the present invention also can be useful in locations in front
of the cutoff
blade 20 (as described below).
In the first preferred embodiment of the present invention illustrated in
Figure 2,
the cutoff roll 14 has a web retention device (indicated generally at 40)
behind the
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7
cutoff blade 20. The web retention device 40 has an aperture 30 preferably in
the shape
of an elongated groove or slot which preferably runs substantially the entire
length of
the cutoff roll 14 behind the cutoff blade 20. Although separate apertures
running only
a small percentage of the length of the cutoff roll 14 can be used, the
aperture 30 is
preferably uninterrupted along its length. However, interruptions in the
aperture 30 are
possible without significantly affecting the performance of the present
invention. The
aperture 30 is preferably shaped and sized to receive the leading web edge 26,
and
preferably has walls 32, 34 defining a throat 36 of the aperture 30. As such,
an
uninterrupted aperture 30 is preferred because it permits easier reception of
the leading
web edge 26 into the aperture 30 (though even an interrupted elongated
aperture 30 will
still permit lengths of the leading web edge 26 to be pulled into the aperture
30 in
accordance with the present invention as described below). It will be
appreciated that
the particular dimensions and arrangement of the throat 36 and walls 32, 34
can vary
considerably. For example, the walls 32, 34 can be closer or farther apart to
result in
apertures 30 of different widths. In the preferred embodiment of the present
invention,
the walls 32, 34 preferably substantially face one another to define the sides
of the
groove-shaped aperture 30. Also, the thickness of the walls 32, 34 need not be
of any
particular dimension for proper operation of the invention. The walls 32, 34
can be
relatively deep, or can be shallow enough that they are defined only by the
edges of the
aperture 30. Indeed, the dimensions and configuration of the throat 36 and the
walls 32,
34 are only dictated by the ability of the aperture 30 and the throat 36 to
receive the
leading web edge 26. Similarly, the depth of the aperture 30 can vary
considerably, and
is preferably at least deep enough to receive the leading web edge 26 of the
severed web
without creating an excess of material at the mouth 38 of the aperture 30.
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8
A vacuum source is in communication with the cutoff roll 14 and is preferably
created in a conventional manner by a vacuum generator (not shown), but can
instead
be supplied by a vacuum tank or other receptacle capable of holding a vacuum.
The
vacuum source is in communication with the aperture 30 to exert a suction
force
through the aperture 30. The web retention device 40 (which includes the
vacuum
generator, the aperture 30, throat 36, walls 32, 34, and mouth 38) thereby
holds the
leading web edge 26 on the cutoff roll 14. Specifically, the leading web edge
26 is
drawn into the aperture 30 after the web 10 has been severed. In this manner,
even if
the web 10 has multiple plies, has one or more non-porous plies which underlie
other
plies, or is highly porous, all plies of the leading web edge 26 are drawn
into the
aperture 30 of the web retention device 40 by the suction created in the
cutoff roll 14.
This is in contrast to the prior art systems which relied upon suction against
the face of
the web 10 to hold the web 10 on the cutoff roll 14. In contrast to the
present invention,
the holding effectiveness of such prior art systems is necessarily dependent
upon the
web and ply materials being held.
After the leading edge 26 of the web 10 has been pulled into the aperture 30
of
the web retention device 40, the leading edge 26 can be held therein until
such time as
the web 10 is pulled or released from the cutoff roll 14 for later operations
performed
upon the web 10. By holding the leading edge 26 within the web retention
device 40 in
the manner described above, the web 10 is kept flat and secure even up to the
leading
edge 26 of the severed web 10, thereby avoiding web pile-ups and undesirable
web
edge movement after cutting.
A second preferred embodiment of the present invention is illustrated in
Figure
3. The apparatus of the second preferred embodiment is substantially the same
as the
first preferred embodiment described above and illustrated in Figure 2, with
the
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9
exception of the location of the web retention device 140 (specifically, the
location of
the aperture 130 of the retention device 140). While the aperture 30 of the
first
preferred embodiment has walls 32, 34 defining the throat 36 of the aperture
30, the
throat 136 in the second preferred embodiment is defined by wall 132 and the
rear
surface 142 of the cutoff blade 120. In other words, the web retention device
140 and
the aperture 130 thereof are located immediately behind and are partially
defined by the
cutoff blade 120. The apparatus illustrated in Figure 3 serves to illustrate
how the
present invention can take a variety of forms all of which act to receive the
leading edge
26, 126 of a severed web 10, 110 into the aperture 30, 130 of a web retention
device 40,
140 to more reliably and securely hold the severed web 10, 110 against motion
and/or
piling up behind the cutoff blade 20, 120.
It should be noted that in the embodiments of the present invention described
herein and illustrated in the figures, although it is preferred that the
leading edge 26,
126 of the severed web 10, 110 is received within the aperture and held
therein by the
vacuum force, an aperture located immediately behind the cutoff blade 20, 120
is itself
unique and (with sufficient vacuum force) can hold the severed edge 26, 126 to
the
cutoff roll 14, 114. Therefore, the present invention can also be practiced by
locating
the retention device 40, 140 immediately behind (or in front of as will be
discussed
below) the cutoff blade to hold the severed edges of the web 10, 110 securely
against
the cutoff roll 14, 114 without actually drawing in the severed edges 26, 126
within the
aperture 30, 130.
Although the preferred embodiments of the present invention each employ an
aperture 30, 130 connected to a vacuum generator to draw the severed edges 26,
126 of
the web 10, 110 into the aperture 30, 130, a vacuum generator is only one type
of web
attraction device that can be used to achieve this result. For example, it is
possible to
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use electrostatic force to attract the severed edges 26, 126 of the web 10,
110 into the
aperture 30, 130 or against the cutoff roll 14, 114 beside the cutoff blade
20, 120.
Specifically, one or more surfaces of the cutoff roll 14, 114 near the cutoff
blade 20,
120 (e.g., one or more walls 32, 132, 34 of the aperture throat 36, 136,
and/or part of the
cutoff blade surface 12, 112 beside the cutoff blade 20, 120) can be made of a
material
capable of retaining an electric charge. When one such surface is used, the
surface
preferably extends substantially the entire length of the cutoff roll 14, 114
behind the
cutoff blade 20, 120. Alternately, multiple charge surfaces can be used, each
separated
from one another along the length of the cutoff roll 14, 114. The charge
surfaces) can
be electrically insulated to prevent charge drain and charge bleeding to other
parts of
the cutoff roll 14, 114. The surfaces) can be connected to an electrostatic
generator
which generates a charge on the surfaces) at controlled times to attract and
repel the
severed edges 26, 126 to and away from the cutoff roll 14, 114, respectively.
It will be
appreciated by one having ordinary skill in the art that the changes in charge
created
upon the surfaces) of the cutoff roll 14, 114 can be created at particular
angular
positions of the cutoff roll 14, 114 during its rotation or can be created at
desired time
intervals depending at least in part upon the speed of the cutoff roll 14,
114. Such a
controller for performing these timed or orientation-specific operations can
be purely
mechanical (e.g., electrical contacts maintaining current only in certain
angles of the
cutoff roll 14, 114, etc.) or can controlled electronically (e.g., via a
microprocessor
timed to create or remove the charge at timed intervals based upon cutoff roll
speed,
etc.) in manners well-known to those skilled in the art.
It should be noted that the web retention device of the present invention in
its
various forms (described and illustrated in the preferred embodiments) can
even include
combinations of vacuum retention and electrostatic retention, such as by
controllably
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11
electrostatically charging one or more of the walls 32, 34 or the throat 36 in
the first
preferred embodiment. These other web retention devices also act to pull and
retain the
severed edge of a web closely beside its cut location on a cutoff roll (for
example), and
fall within the spirit and scope of the present invention.
The embodiments of the present invention described above and illustrated in
the
drawings each disclose a web retention device 40, 140 located behind the
cutoff blade
20, 120. However, it should be noted that the web retention device 40, 140
(the
aperture 30, 130 and its related elements) can be located in front of the
cutoff blade 20,
120 in order to hold the trailing web edge 28, 128 of the web 10, 110 to the
cutoff roll
14, 114. Such alternate embodiments function in substantially the same manner
as the
embodiments described above. In yet another alternate embodiment, the cutoff
roll 14,
114 can even be provided with a web retention device 40, 140 located behind
the cutoff
blade 20, 120 and a web retention device 40, 140 located in front of the
cutoff blade 20,
120. By providing apertures 30, 130 on either side of the cutoff blade 20,
120, both the
leading and trailing web edges 26, 126, 28, 128 can be held securely to the
cutoff roll
14, 114.
The embodiments described above and illustrated in the figures are presented
by
way of example only and are not intended as a limitation upon the concepts and
principles of the present invention. As such, it will be appreciated by one
having
ordinary skill in the art that various changes in the elements and their
configuration and
arrangement are possible without departing from the spirit and scope of the
present
invention as set forth in the appended claims.
For example, the embodiments described above and illustrated in the figures
show the web retention device 40, 140 located behind or in front of a cutoff
blade 20,
120 on a cutoff roll 14, 114. However, one having ordinary skill in the art
will
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12
recognize that the aperture 30, 130 and blade 20, 120 arrangement of the
present
invention can be employed with the same advantageous results to any system or
device
in which the leading and/or trailing edges of a cut web 10, 110 are left after
being cut.
The blade 20, 120 and the aperture 30, 130 need not necessarily be on a roll
or a curved
surface, but can instead be located on a table or any other surface on top of
over which
a web 10, 110 is placed to be cut. (In such cases, the "surface" can be
interrupted by
the blades) and aperture(s)). The advantages of the present invention are,
however,
realized most particularly in applications where the surface is in motion or
is moved,
and/or in which it is desirable to hold the severed web 10, 110 in place to
prevent web
piling up or motion beside the blade. Also, although the appended claims, the
description, and the figures of the preferred embodiments disclose or make
reference to
a particular orientation of the web 10, 110, the cutoff roll 14, 114 and the
web retention
devices 40, 140, it is to be understood that this orientation is not to be
considered a
limitation upon the spirit and scope of the present invention. For example,
the cutoff
roll 14, 114 is disclosed and claimed herein as being located beneath the web
10, 110.
It will be appreciated by one having ordinary skill in the art that the
present invention
can be employed with many other web/retention device/cutoff roll orientations,
and that
reference in the claims to a particular orientation (e.g., "beneath",
"underlying", etc.) in
fact includes all web-to-surface orientations which are adjacent one another.
Also, the present invention is described and illustrated as performing web
retention operations upon edges 26, 28, 126, 128 of a severed web 10, 110.
However, it
should be noted that the present invention can operate upon a portion of the
severed
web 10, 110 which is located a distance from the edges 26, 28, 126, 128 of the
severed
web 10, 100. For example, in the first preferred embodiment of the present
invention
described above and illustrated in Figure 2, the aperture 30 is located
immediately
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13
behind the cutoff blade 20. However, depending at least in part upon the
dimensions
and size of the cutoff roll 14, the cutoff blade 20, and the web 10, it is
possible that the
leading web edge 26 of the severed web 10 is not pulled into the aperture 30.
A portion
of the severed web 10 behind the leading web edge 26 can instead be pulled
into the
aperture and held therein by the vacuum force. Though the result of such an
action is
still the same (the severed leading web edge 26 is held closely to the surface
of the
cutoff roll 14 to prevent piling up in downstream operations), the web edge 26
itself
need not necessarily be pulled into the aperture 30 for the present invention
to operate
correctly. Any portion of the severed web located closely behind the cutoff
blade 20
can be retained within the aperture 30 to still practice the present
invention. Of course,
this is also true for embodiments of the present invention in which the
trailing severed
web edge 28 is held within an aperture in the cutoff roll 14, and is true for
the
alternative embodiments of the present invention described herein. As such,
reference
in this application to the term "edge" (particularly with reference to
retaining an edge of
the web within an aperture 30, 130) is not limited to the physical edge of a
web, but
instead means any portion of the web which is retained within an aperture
following the
principles of the present invention.
Additionally, the particular system in which the present invention is
illustrated
and described above (a cutoff roll 14, 114 and a stationary anvil 16, 116 and
anvil blade
18, 118) is to be considered only an example of the many systems and devices
in which
the present invention can be employed. For example, the present invention can
be
utilized with systems having a rotating anvil 16, 116 and anvil blade 18, 118
or with
systems having a stationary cutoff roll 14, 114 and a moving anvil 16, 116 and
anvil
blade 18, 118, or even with systems having web severing elements or devices
well-
known to those skilled in the art but which are completely different than
those disclosed
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14
herein. In this regard, it is to be noted that the cutoff blade 20, 120 need
not necessarily
be mounted or attached to the surface (or with respect to the surface) on
which the web
retention devices 40, 140 are located. Specifically, the blade 20, 120 and web
retention
devices 40, 140 illustrated in the figures are shown fixed in place relative
to one
another. However, a number of other conventional cutting elements and systems
can be
used with equal effect to sever the web 10, 110 in a place near the aperture
30, 130
(allowing the aperture 30, 130 to pull and hold the severed web 10, 110). One
example
of an alternate cutting element is a blade mounted upon an arm which
reciprocates to
bring the blade into and out of contact with the passing web 10, 110. Many
cutting
arrangements do not physically separate the severed edges of the web 10, 110
with a
barrier, such as the cutoff blade 20, 120 in the preferred embodiments
described above.
In such cases, it is possible to pull both the leading and trailing edges 26,
126, 28, 128
into the same aperture 30, 130.
Finally, it will be appreciated by one having ordinary skill in the art that
the
aperture 30, 130 used in the present invention can vary in shape and size
while still
accomplishing the purposes of the invention. As noted above, the dimensions
and
arrangement of the throat 36, 136 and aperture walls 32, 132, 34, 140 of the
aperture 30,
130 can vary considerably, as can the particular orientation of the aperture
30, 130 with
respect to the cutoff blade 20, 120. It should also be noted that the overall
length and
shape of the aperture 30, 130 can vary significantly. Specifically, the
aperture 30, 130
need not necessarily run the entire length of the roll 14, 114, or even the
entire length of
the blade 20, 120. Because the web material used is often somewhat elastic, an
elongated aperture 30, 130 can be shorter in length than the blade 20, 120 but
still be
able to pull (by vacuum) a significant length of the web edge therein to hold
the web 10,
110 against the roll 14, 114. In this regard, it is thus possible to have a
cutoff roll 14,
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114 with more than one elongated aperture 30, 130 behind or in front of the
cutoff blade
20, 120. For example, a line of elongated apertures 30, 130 can be arranged in
an end-
to-end fashion behind the cutoff blade 20, 120, rather than having one long
aperture
running behind the cutoff blade 20, 120.
