Note: Descriptions are shown in the official language in which they were submitted.
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TITL~: METHOD ~ND APPARATU~ FOR CUTTING A WEB OF
FLEXIBLE MATBRIAL INTO LONGITUDINA~LY EXTENDING
~TRIP8
FIELD OF THE INVENTION
The present invention relates to a method and an
apparatus for slitting a continuous web of flexible
material into narrower, longitudinally extending strips.
Advantageously, the in~ention can be used for slitting a
web of fluid absorbent material, such as peat moss into
strips that can be directly processed in automatic
e~uipment to assemble disposable absorbent products, such
as sanitary napkins, diapers, adult briefs, urinary pads,
wound dressings and the like.
BACKGROUND OF THE INVENTION
The prior art has recognized the potential of peat
moss material for use as an absorbent medium in structures
for absorbing body exudate. Peat moss material has highly
desirable fluid absorption properties such as a remarkable
absorption capacity and the ability of "drying" adjacent
materials by continuing to pull or wick fluid away from
them over a long time period such that virtually all the
fluid is collected in the peat moss core. These
,
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attributes allow the material to provide highly efficient
absorbent components which can be made relatively thin for
better fit, comfort and discretion, while being
sufficiently absorbent to prevent overflow leakage and
garment staining.
The following United 5tates Patents document the use
of peat moss material for manufacturing absorbent
components for disposable absorbent products:
PATENT # INVENTOR DATE I8SUED
4,170,515 Lalancette et al. October 9, 1979
4,215,692 Levesque August 5, 1980
4,226,237 Levesque October 7, 1980
4,305,393 Nguyen December 15, 1981
4,473,440 Ovans September 25, 1984
4,507,122 Levesque March 26, 1985
4,618,496 Brasseur October 21, 1986
4,676,871 Cadieux et al. June 30, 1987
4,992,324 Dubé February 12, 1991
5,053,029 Yang October 1, 1991
The subject matter of these references is
incorporated herein by reference.
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Peat moss material can be formed in a highly cohesive
web by any one of the processes disclosed in the above
identified prior art. In a web form, the peat moss
material is convenient to handle and it can be directly
S processed in high speed automatic equipment for assembling
dispGsable absorbent products.
Equipment capable to manufacture disposable absorbent
products functions most efficiently when the peat moss web
is supplied in narrow continuous strips, whereby no edge
trimming is required to form the individual absorbent
cores. In practice, the width of an absorbent core is
relatively small, in the order of 5 centimetres for a
sanitary napkin and somewhat wider for a diaper or a
disposable adult brief. To obtain such narrow strips, it
is common practise to longitudinally cut a wide web of
peat moss material in a plurality of strips that are
winded on a common core to form independent rolls having
the requisite width. The cutting process is carried out
by passing an unsupported run of the peat moss web through
a cutting station having a cutting assembly extending
transversely with relation of the web and carrying a
plurality of blades in a spaced apart relationship. The
blades continuously slit the web as the latter is carried
forward. This method works well with webs that have a
relatively constan~ calliper, such as paper. However, the
calliper of peat moss webs is difficult to maintain within
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close tolerances and appreciable variations are often
encountered. It has been observed that such calliper
variations cause an uneven cutting action by the blades.
In extreme cases, the uneven cutting action may cause
adjacent strips to overlap when they are winded which may
result into breakage of the entire peat moss web.
OBJECT AND 8TATEMENT OF THE INVENTION
An object of the present invention is a method and an
apparatus for cutting a continuous web of flexible
material such as peat moss for example, into
longitudinal}y extending strips, allowing to cleanly cut
webs of uneven calliper without significant risks of
causing an overlap between adjacent strips when the web is
being winded or web breakage.
8UMMARY OF THE INVENTION
As embodied and broadly described herein, the
invention provides a method for cutting a continuous web
of flexible material into longitudinally extending strips,
the method comprising the steps of:
~ winding a continuous web of flexible material to
build-up a roll and rotating the roll in order to draw the
web of flexible material thereon;
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- engaging a rotary blade against a peripheral
surface of the roll while the roll is being rotated; and
- rotating the rotary blade, whereby the rotation of
the roll causes a relative movement between the rotary
blade and the web of flexible material taken-up by the
roll in order to continuously slit the web of flexible
material which is winded on the roll as separate strips.
This method allows to slit into longitudinally
extending strips and wind webs of material having an
uneven calliper, such as peat moss webs, without
significant risks of causing adjacent strips to overlap or
to cause web breakage. This is due to the fact that the
cutting action is carried on the roll itself where the web
is firmly supported and is less likely to move or twist as
in the case of an unsupported run of the web.
Accordingly, a precise cutting action is made possible in
spite of calliper variations.
As embodied and broadly described herein, the
invention provides an apparatus for cutting a continuous
web of flexible material into longitudinally extending
strips, the apparatus comprising:
- a winding assembly for winding a continuous web of
flexible material to form a roll, the winding assembly
rotating the roll to draw the web of flexible material and
build-up the roll; and
`
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- a cutting assembly including a rotary blade
engaging a peripheral surface of the roll, whereby the
rotation of the roll causes a relative movement between
the rotary blade and the web of flexible material taken-
s up by the roll in order to continuously slit the web of
flexible material which is winded on the roll as separate
strips.
In a preferred embodiment, the cutting assembly
includes an elongated shaft carrying a plurality of
circular blades axially spaced apart from one another.
The elongated shaft is positioned in a parallel
relationship with the roll of flexible material and
pressed against the roll. To carry out the cutting action
the elongated shaft is rotated in a direction opposite the
direction of rotation of the roll. The circular blades
may be equidistant from one another to form strips of
equal width. It may also be envisaged to vary the spacing
between the blades to form on the æame roll strips of
different width.
Advantageously, the cutting assembly is provided with
one or more idler rollers rotatably mounted on the
elongated shaft between adjacent blades and ride on the
roll of flexible material. The purpose of the idler
rollers is to control the depth of penetration of the
blades in the roll.
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In a preferred embodiment, the roll of flexible
material is rotated by supporting it on a pair of parallel
drive rollers slightly spaced apart to form an elongated
cavity receiving the roll of flexible material. One of
the drive rollers is rotated which causes the roll of
flexible material to turn by virtue of friction between
the surface of the drive roller and the web of flexible
material.
BRIEF DE~CRIPTION OF T~E DRAWINGR
- Figure 1 is a perspective schematical view of an
apparatus for slitting a continuous web of peat moss
material into a plurality of longitudinally extending
strips, constructed in accordance with the present
invention;
- Figure 2 is a side elevational view of a winding
and cutting station of the apparatus shown in Figure l;
- Figures 3 and 4 are similar views to Figure 2
showing in the winding and the cutting station a
progressively growing roll of peat moss material;
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- Figure 5 is an enlarged fragmentary view of the
apparatus shown in Figure 1, illustrating a blade of a
cutting assembly penetrating the roll of peat moss
material; and
- Figure 6 is a front elevational view of the cutting
assembly shown in Figure 5.
DESCRIPTION OF A PREFERRED EMBODIMENT
The apparatus in accordance with the invention is
particularly useful for cutting a web of fluid absorbent
material, such as peat moss which has an uneven calliper
into narrow, longitudinally extending strips. However, it
should be appreciated that the invention is not limited to
a specific material to be cut as the apparatus may process
a wide range of flexible webs, such as paper for example.
The cutting apparatus, designated comprehensively by
the reference numeral 10, comprises an assembly of guide
rollers 12 which direct a web of peat moss material 14
from a supply reel 16 to a winding and cutting station 18.
The winding and cutting station 18 includes a trimming
assembly 20 for cutting the side edge portions of the web
14 to provide a web with straight side edges and constant
width. The winding and cutting sta-tion 18 further
comprises a winding assembly 22 for winding the web 14
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received from the trimming station 20 into a roll 24
having a core 25, and a cutting assembly 26 for slitting
the web on the roll 24 into narrow, longitudinally
extending strips which are winded as independent narrow
rolls on the core 25.
The trimming station 20 comprises a cutting roll 28
including a rotating shaft 30 which extends transversely
to the web 14 and on which are formed radially projecting
circular blades 32 in an axially spaced apart
relationship. The distance between the blades 32
determines the width of the web 14 that is being fed to
the winding and cutting station 18. The cutting roll 28
is associated with an anvil roll 34 comprising
circumferential grooves 36 (only one being shown in the
drawings) for receiving the blades 32.
The cutting roll 28 and the anvil roll 34 are rotated
in opposite directions to cut the side edges of the web 14
by shearing action. The supports for these rolls and
their drives have not been shown in the drawings for the
purpose of simplicity.
The ~inding assembly 22 is located above the
trimming station 20 and it comprises a pair ~f elongated
drive rollers 38 and 40 which are generally parallel to
one another and slightly spaced apart to define
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therebetween an elongated recess in which the roll 24 is
seated. The drive rollers 38 and 40 are coupled to a
common drive (not shown in the drawings), and turn in the
same direction.
The cutting assembly 26 comprises an elongated shaft
42 generally parallel to the longitudinal axis of the roll
24 and rotated by a drive mechanism 44. The shaft 42 is
slidingly mounted in vertically extending tracks 46
whereby the entire cutter assembly 26 can move radially
with respect to the roll 24. The drive mechanism 44 is
such as to maintain the driving relationship with the
shaft 42 while the latter slides in the tracks 46. Drives
with this characteristic are well known to those skilled
in the art and a detailed description thereof is not
deemed to be necessary.
The cutter assembly 26 further comprises a plurality
of radially projecting circular blades 48 rigidly mounted
on the shaft 42 in an axially spaced apart relationship.
The blades 48 may be equidistant to slit the web 14 into
strips of the same width, or the distance between the
blades may be varied to form strips of different width.
on the shaft 42 are rotatably mounted a pair of idler
rollers 49, situated between adjacent blades 48 and which
have a diameter less than that of the blades 48. The
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idler rollers 49 engage in a rolling contact the
peripheral surface of the roll 24 and rotate therewith.
A pneumatic piston-cylinder assembly 51 mounted
inside one of the tracks 51 is coupled to the shaft 42 to
vertically displace the shaft. The piston-cylinder
assembly 51 also serves to urge the cutting assembly 26
against the roll 24. The amount of pressure developed
between the cutting assembly 26 and the surface of the
roll 24 is controlled by regulating the air pressure in
the piston-cylinder assembly 51.
The operation of the cutting apparatus 10 is as
follows. The web 14 is unwinded from the supply reel 16
and the leading edge of the web is threaded through the
guide rollers 12, through the trimming station 20 and up
to the winding assembly 22. The leading edge of the web
14 is then manually wound a few turns over the core 25 to
start the roll 24. The cutting assembly 26 is lowered by
extending the piston-cylinder assembly 51 to rest on the
roll 24. The air pressure in the piston-cylinder assembly
51 is adjusted to obtain the desired amount of pressure
between the cutting assembly 26 and the roll 24. This
parameter is not critical for th~ success of the invention
as the apparatus 10 may be operated at a wide range of
pressures between the cutting assembly 26 and the roll 24.
Preferably, the pneumatic circuit of the piston-cylinder
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assembly 51 is such as to be capable of maintaining a
constant air pressure therein irrespective of the degree
of the extension of the piston-cylinder assembly 51. This
feature allows to keep the pressure of the cutting
assembly 26 against the roll 24 constant at different
vertical positions of the cutting assembly.
The winding assembly 22 is actuated to rotate the
drive rollers 38 and 40 in the direction shown by the
arrows in Figures 2 to 4. The friction existing between
the cylindrical surfaces of the drive rollers 38 and 40
and the web 14 will cause the roll 24 to rotate and draw
the web 14 to further build-up the roll.
Simultaneously with the actuation of the winding
assembly 22, the drive of the trimming station 20 is
actuated, whereby the rolls 28 and 34 are rotated to trim
the side edge portions of the web 14 passing between them.
The resulting trims are discarded or preferably recycled.
The drive unit 44 of the cutting assembly 26 is
actuated to rotate the shaft 48 in a direction shown by
the arrows in Figures 2 to 4. The direction of rotation
of the shaft 42 is the opposite of the direction of
rotation of the roll 24. The blades 48, under the effect
of rotation continuously cut the web 14 that is being
taken-up by the roll 24 into narrow longitudinally
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extending strips. Those strips are winded as independent
rolls on the core 25. As the diameter of the roll grows,
the cutter assembly 26 is raised gradually against the
force exerted by the piston-cylinder assembly 51. It
should be appreciated that the constant air pressure in
the pneumatic circuit of the piston-cylinder assembly 51
allows to keep the pressure between the cutting assembly
26 and the roll 24 generally constant for different roll
diameters.
The idler rollers 49 riding on the roll 24 control
the depth of penetration of the blades 48 in the roll.
Figures 5 and 6 best show this feature. The depth of
penetration is determined by the radial extent of the
blades beyond the idler rollers 49. In the example shown,
the blades have a diameter of approximately 15.24
centimetres and the idler rollers have a diameter of
approximately 14.92 centimetres. Accordingly, the depth
of penetration is of approximately 0.318 centimetres. A
typical peat moss web has a calliper of approximately
0.07 centimetres, whereby the blades 48 extend
approximately three to four layers deep in the roll 24.
The scope of the present invention is not limited by
the description, examples and suggestive uses herein, as
modifications can be made without departing from the
spirit of the invention. Applications of the product and
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the methods of the present invention for sanitary and
other health-care uses can be accomplished by any sanitary
protection, incontinence, medical and absor~ent methods
and techniques as are presently or prospectively known to
those skilled in the art. Thus, it is intended that the
present application covers the modifications and
variations of this invention provided that they come
within the scope of the appended claims and their
equivalents.
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