U.S. patent application number 12/037126 was filed with the patent office on 2009-08-27 for apparatus and method for centering and spreading a web.
Invention is credited to Uwe Schneider.
Application Number | 20090211070 12/037126 |
Document ID | / |
Family ID | 40602238 |
Filed Date | 2009-08-27 |
United States Patent
Application |
20090211070 |
Kind Code |
A1 |
Schneider; Uwe |
August 27, 2009 |
Apparatus And Method For Centering And Spreading A Web
Abstract
A web centering and spreading processing system and related
method are used to center a moving web and then spread the web in
order to remove wrinkles from the web. The centering mechanism, in
one example, has a centering roller that receives the wrinkles web.
The outer edges of the web, which tend to be uneven and not
centered, are detected and a signal is sent to the centering roller
to move the web laterally and thereby center the web. The centered
web, which is substantially centered but not necessarily precisely
centered, moves to a spreader station that receives the web and
spreads it thereby removing any wrinkles in the web. The spreader
station may include a roller with a recessed center area and that
has at least one set of contoured plates that move across the
roller from an inner position to an outer position. The plates have
gripping surfaces that grip the edges of the web and spread the web
to remove the wrinkles. The plates also have an inner smooth area
that, in conjunction with the recessed area, allow the inner area
of the web to essentially float and thereby be spread to remove the
wrinkles without binding.
Inventors: |
Schneider; Uwe; (Cincinnati,
OH) |
Correspondence
Address: |
THE PROCTER & GAMBLE COMPANY;Global Legal Department - IP
Sycamore Building - 4th Floor, 299 East Sixth Street
CINCINNATI
OH
45202
US
|
Family ID: |
40602238 |
Appl. No.: |
12/037126 |
Filed: |
February 26, 2008 |
Current U.S.
Class: |
26/98 ; 26/75;
26/88 |
Current CPC
Class: |
B65H 2801/57 20130101;
B65H 23/025 20130101; B65H 23/032 20130101 |
Class at
Publication: |
26/98 ; 26/75;
26/88 |
International
Class: |
D06C 3/00 20060101
D06C003/00 |
Claims
1. A method of processing a web comprising: in a web processing
system defining a machine center line and a cross-machine direction
substantially perpendicular to the machine center line, receiving a
moving web defining a first side edge and a second side edge, the
web further having one or more wrinkles; adjusting the web in the
cross-machine direction; and laterally spreading the web to
substantially remove the one or more wrinkles.
2. The method of claim 1 wherein the adjusting operation further
comprises: detecting a difference between a first distance and a
second distance, the first distance being between the first side
edge and the machine center line and the second distance being
between the second side edge and the machine center line.
3. The method of claim 2 wherein the first distance is between the
first side edge and a first target location a set distance from the
machine center line and the second distance is between the second
side edge and a second target location the set distance from the
machine center line.
4. The method of claim 2 wherein the operation of detecting occurs
between the adjusting and laterally spreading operations.
5. The method of claim 2 wherein the adjusting operation further
comprises: adjusting the web so that the first distance and the
second distance are substantially equal.
6. The method of claim 1 further comprising the operations of:
receiving, in association with the adjusting operation, at least
one control signal indicative of the difference; adjusting the web
in the cross-machine direction as a function of the at least one
signal.
7. The method of claim 1 further comprising: prior to the adjusting
operation, activating at least a portion of the moving web in the
cross-machine direction, the operation of activating forming at
least some of the one or more wrinkles.
8. The method of claim 1 wherein the operation of laterally
spreading includes: engaging the moving web adjacent the first side
edge; engaging the moving web adjacent the second side edge; and
allowing the moving web to freely move over an area between the
first side edge and the second side edge to spread the web and
substantially remove the one or more wrinkles.
9. The method of claim 1 wherein the moving web comprises a
plurality of diapers and the method further comprising: following
the laterally spreading operation, cutting each of the plurality of
diapers from the moving web.
10. The method of claim 1 further comprising the operations of:
detecting an aspect of the web indicative of a distance between the
first side edge and the second side edge; and controlling the
laterally spreading of the web to substantially remove the one or
more wrinkles as a function of the aspect of the web indicative of
the distance between the first side edge and the second side
edge.
11. A web processing system defining a machine center line and a
cross-machine direction configured to process a moving web defining
a first side edge and a second side edge comprising: a web
centering assembly comprising a centering mechanism in
communication with at least one sensor configured to detect the
relationship between the moving web and the machine center line,
the centering mechanism configured to receive at least one signal
indicative of the relationship between the moving web and the
machine center line and adjust the moving web in the cross-machine
direction; and a web spreading assembly including a spreader roller
defining a first circumference and a second circumference
substantially equal to the first circumference, and a third
circumference less than the first and second circumference and
positioned between the first and second circumferences, the
spreader roller moveably supporting a first plate and a second
plate on at least a portion of the first and second circumference,
respectively, the first and second plate arranged to engage the web
received from the web centering assembly in a region of the first
and second edge side edges respectively, and move substantially in
the cross-machine direction to spread the web.
12. The web processing system of claim 11 wherein: the first plate
defines an outer area with a surface configured to engage the web
in the region of the first side edge; and the second plate defines
a second outer area with a second surface configured to engage the
web in the region of the second side edge.
13. The web processing system of claim 12 wherein: the first plate
defines an inner area adjacent the outer area, the inner area
having a low coefficient of friction surface configured to allow
the web to freely slide of over the inner area; and the second
plate defines a second inner area adjacent the second outer area,
the second inner area having a low coefficient of friction surface
configured to allow the web to freely slide over the inner
area.
14. The web processing system of claim 13 wherein: the first plate
defines an arc with a diameter substantially the same as a diameter
of the spreader roller at the first circumference; and the second
plate defines an arc with a diameter substantially the same as a
diameter of the spreader roller at the second circumference.
15. The web processing system of claim 11 wherein the moving web
includes a plurality of diapers, the system further comprising: a
web activation station configured to intermittently activate the
diaper web in the cross-machine direction and subsequently provide
the moving web to the web centering assembly and a web cutting
station configured to receive the moving web from the web spreading
assembly and cut the individual diapers from the moving web.
16. The system of claim 11 wherein the web centering assembly
comprises means for centering the web in communication with means
for detecting an edge of the web.
17. The system of claim 11 wherein the web spreading assembly
comprises means for spreading the web.
18. The system of claim 11 wherein the web spreading assembly is
further configured to receive the at least one signal indicative of
the relationship between the moving web and the machine centerline,
the web spreading assembly further configured to control an amount
of movement of the first plate and second plate substantially in
the cross-machine direction to spread the web as a function of the
at least one signal.
19. A web spreading assembly comprising: a spreader roller
configured to receive a web, the spreader roller having an outer
substantially circumferential surface defining a first
circumference, a second circumference substantially equal to the
first circumference, and a third circumference less than the first
and second circumference and positioned between the first and
second circumferences; the spreader roller moveably supporting at
least a first plate and second plate on at least a portion of the
first and second circumference, respectively, the first and second
plates arranged to engage the web and move substantially in the
cross-machine direction to spread the web; the spreader roller
including a spreader mechanism coupled with the first plate and the
second plate and configured to move the first and second plates
substantially in the cross-machine direction, the spreader
mechanism receiving at least one control signal indicative of a
width of the web, the spreader mechanism configured to control an
amount of movement of the first plate and the second plate in the
cross-machine direction as a function of the at least one control
signal; the first plate defines an outer area with a surface
configured to engage the web in the region of the first side edge,
the first plate further defines an inner area adjacent the outer
area, the inner area having a low coefficient of friction surface
configured to allow the web to freely slide of over the inner area;
and the second plate defines a second outer area with a second
surface configured to engage the web in the region of the second
side edge, the second plate further defines a second inner area
adjacent the second outer area, the second inner area having a low
coefficient of friction surface configured to allow the web to
freely slide over the inner area.
20. The web spreading assembly of claim 19 wherein the spreader
mechanism is supported within the spreader roller, the spreader
mechanism including a first member at least partially extending
through a first lateral channel in the spreader roller and coupled
with the first plate, the spreader mechanism including a second
member at least partially extending through a second later channel
in the spreader roller and coupled with the second plate, the first
member operably coupled with a first piston configured to move in
the cross-machine direction, the second member operably coupled
with a second piston arranged to move in the cross-machine
direction opposite the movement of the first piston whereby the
first and second plates engage the web in a first relative position
and move laterally and away to a second relative position to spread
the web.
Description
FIELD OF THE INVENTION
[0001] Aspects of the present disclosure involve a web processing
apparatus and method. More particularly, aspects of the present
disclosure involve an apparatus and method for centering and
spreading a moving web.
BACKGROUND OF THE INVENTION
[0002] Many different products, such as diapers, are manufactured
or produced in a web process. Generally speaking, a web might begin
with some form of base material and the constituent parts of the
end product are introduced into the moving web at various stations.
At the end of the process, the web contains a series of end
products, which are each then individually cut from the web. So, in
the example of a diaper, the various constituent parts of the
diaper, such as the backing, elastic waist bands, absorbent pads,
etc., are arranged and fixed on the web until the web includes a
series of finished diapers, which are each then cut from the
web.
[0003] Any such web processing system, whether it be for diapers or
otherwise, may impart wrinkles or folds into the web. Wrinkles may
impart unwanted variability into the end product. For example, if a
diaper web having a wrinkle in the waist band area is cut from the
web, the waist band in the final diaper may have a jagged edge
along the waist band. Other such unwanted variations are also
possible.
[0004] As will be recognized from the discussion below, these and
other problems in the art are addressed by various systems and
methods set forth herein for centering a web and spreading the web
to remove wrinkles and position the web for a cutting stage or
other subsequent processing operation. Before explaining the
disclosed embodiments in detail, it is to be understood that this
disclosure is not limited in its application to the details of the
particular arrangements shown. Moreover, implementations conforming
to aspects of the disclosure may be set forth in different
combinations and arrangements unique in their own right. Also, the
terminology used herein is for the purpose of description and not
of limitation.
SUMMARY OF THE INVENTION
[0005] One aspect of the present disclosure involves a method of
processing a web, such as but not limited to a diaper web, that
involves a processing system defining a machine center line and a
cross-machine direction substantially perpendicular to the machine
center line. The method receives a moving web defining a first side
edge and a second side edge. The web may have wrinkles or other
folds. The method further includes adjusting the web in the cross
machine direction and laterally spreading the web to substantially
remove the one or more wrinkles. The adjusting operation may
involve detecting a difference between a first distance and a
second distance, the first distance being between the first side
edge and the machine center line and the second distance being
between the second side edge and the machine center line. The
spreading operation may involve detecting an aspect of the web
indicative of a distance between the first side edge and the second
side edge and controlling the laterally spreading of the web to
substantially remove the one or more wrinkles as a function of the
aspect of the web indicative of the distance between the first side
edge and the second side edge.
[0006] Another aspect of the present disclosure involves a web
processing system defining a machine center line and a
cross-machine direction configured to process a moving web defining
a first side edge and a second side edge. The system includes a web
centering assembly comprising a centering mechanism in
communication with at least one sensor configured to detect the
relationship between the moving web and the machine center line.
The centering mechanism is configured to receive at least one
signal indicative of the relationship between the moving web and
the machine center line and adjust the moving web in the
cross-machine direction. The system further includes a web
spreading assembly including a spreader roller defining a first
circumference and a second circumference substantially equal to the
first circumference, and a third circumference less than the first
and second circumference and positioned between the first and
second circumferences. The spreader roller moveably supports a
first plate and a second plate on at least a portion of the first
and second circumference, respectively. The first and second plate
are arranged to engage the web received from the web centering
assembly in a region of the first and second edge side edges
respectively, and move substantially in the cross-machine direction
to spread the web.
[0007] Yet another aspect of the present disclosure involves a web
spreading assembly including a spreader roller configured to
receive a web. The spreader roller has an outer substantially
circumferential surface defining a first circumference, a second
circumference substantially equal to the first circumference, and a
third circumference less than the first and second circumference
and positioned between the first and second circumferences. The
spreader roller moveably supports at least a first plate and second
plate on at least a portion of the first and second circumference,
respectively, the first and second plates arranged to engage the
web and move substantially in the cross-machine direction to spread
the web. The spreader roller includes a spreader mechanism coupled
with the first plate and the second plate and configured to move
the first and second plates substantially in the cross-machine
direction. The spreader mechanism receives at least one control
signal indicative of a width of the web and the spreader mechanism
is configured to control an amount of movement of the first plate
and the second plate in the cross-machine direction as a function
of the at least one control signal. The first plate defines an
outer area with a surface configured to engage the web in the
region of the first side edge and further defines an inner area
adjacent the outer area. The inner area has a low coefficient of
friction surface configured to allow the web to freely slide of
over the inner area. Similarly, the second plate defines a second
outer area with a second surface configured to engage the web in
the region of the second side edge. The second plate further
defines a second inner area adjacent the second outer area. The
second inner area has a low coefficient of friction surface
configured to allow the web to freely slide over the inner
area.
[0008] These and other aspects of the present disclosure are set
forth in greater detail below.
BRIEF DESCRIPTION OF THE DRAWINGS
[0009] FIG. 1 is a representative side view of one example of a web
processing system involving various web processing stations
including a web centering station and a web spreading station.
[0010] FIG. 2 is a top view of a diaper web that may be processed
in accordance with implementations set forth herein.
[0011] FIG. 3 is a representative view of a web having a
longitudinal fold or wrinkle.
[0012] FIG. 4 is a partially exploded isometric view of one
particular implementation of a web centering and spreading
assembly.
[0013] FIG. 5 is an isometric view of the web centering and
spreading assembly shown in FIG. 4.
[0014] FIG. 6 is an exploded rear isometric view of the web
centering and spreading assembly of FIG. 4.
[0015] FIG. 7 is a rear view of the web centering and spreading
mechanism of FIG. 4.
[0016] FIG. 8A is a diagram depicting a web including a wrinkle and
outer edges that are not centered.
[0017] FIG. 8B is a diagram depicting the web of FIG. 8A after it
has been centered such that the web still includes a wrinkle but
the side edges are centered.
[0018] FIG. 8C is a diagram depicting the web of FIG. 8B after the
spreading operation such that the web is centered and the wrinkle
has been removed from the web.
[0019] FIG. 9 is a flowchart depicting one method of centering and
spreading a web.
[0020] FIG. 10 is a representative isometric view of a web
spreading roller.
[0021] FIG. 11 is an exploded isometric view of a web spreading
mechanism for use in a web spreading assembly.
DETAILED DESCRIPTION OF THE INVENTION
[0022] Aspects of the present disclosure involve an apparatus and
method for centering and spreading a web. In one particular
implementation, the apparatus and method are deployed in a diaper
manufacturing process to remove wrinkles in a diaper web before the
diapers are cut from the web. A centering and web spreading
assembly, in one example, involves a camber roller assembly that
receives a web including some wrinkles. Due to the presence of the
wrinkles, as well as other factors, the web may enter the camber
roller such that the web's longitudinal center line is misaligned
with the machine and associated roller center line. Additionally,
the outer edges of the web may be misaligned relative to the center
lines and misaligned relative to the outer edges of the camber
roller (e.g., the side edges of the web are not equidistant from
the outer edges of the roller). Thus, in one implementation, the
camber roller has one or more edge sensors, positioned either
before, after, or in both positions relative to the web entering
the camber roller and may be in a feedback or a feedforward
configuration. The edge sensors are configured to detect the edges
of the web and adjust the camber roller to center the web on the
roller, such that the outer edges of the web are substantially
equidistant from the center line of the roller and/or the outer
sides of the roller. The camber roller may remove some wrinkles,
but is not primarily tasked with removing wrinkles from the
web.
[0023] The centered web proceeds from the camber roller assembly to
a spreader assembly that receives the web and spreads the web
laterally (in the cross-machine direction) to remove any wrinkles
in the web. The spreader assembly includes a spreader roller
defining an inner circumferential area adjacent two outer
circumferential areas having a slightly greater diameter than the
inner area. Two pairs of spreader plates are positioned on the
spreader roller, with a first pair of plates positioned on the
outer area and the second pair of plates positioned about 180
degrees from the first pair and also on the outer area. A pair of
spreader plates are configured to engage the web as it contacts the
spreader roller, with the spreader plates initially positioned
adjacent the inner reduced diameter area. As the roller rotates in
the direction of the moving web, the spreader plates move outwardly
relative to each other and toward the outer edge of the roller
thereby spreading the web. The spreader plates each include an
inner smooth area and an outer gripping area. The outer gripping
area engages the outer edge region of the web, while the inner
smooth area of the plate in conjunction with the reduced diameter
inner area of the spreader allows the web to spread without being
hindered by either the roller or a portion of the spreader
plates.
[0024] In one implementation, discussed below in detail, the edge
sensors have an additional role besides providing a control signal
to the web centering assembly. Namely, the edge sensors also
provide a control signal to the web spreading assembly. The web
spreading assembly uses the control signal to control the spreader
plates to impart either a greater or lesser amount of web
spreading. The edge sensors detect the relative position of the web
edges, which web edge positioning is a function of the degree of
wrinkling of the web. A greater degree of wrinkling in the web will
translate to one or both edges of the web being closer to the
machine center line. Hence, before entering the spreader assembly,
the effective width of the web will be more or less depending on
the number of wrinkles, degree of wrinkling, among other factors.
By providing the control signal to the web spreading assembly, the
spreader plates may be moved to a greater or lesser extent to
compensate for the presence of a greater number of wrinkles, degree
of wrinkling (requiring more spreading) or a lesser number and
degree of wrinkling (requiring less spreading). These
implementations are discussed in greater detail below.
[0025] One example of a diaper manufacturing process that may
employ a centering and spreading apparatus is schematically
illustrated in FIG. 1. The diaper manufacturing process produces a
continuous web 20 defining a plurality of interconnected disposable
absorbent articles, such as diapers 22, that are eventually cut out
of the web into individual diapers. Each diaper 22 includes an
absorbent pad element or absorbent core 24, a pair of elastomeric
elements or patches 26, which may be comprised of "live" synthetic
or natural rubber, synthetic or natural rubber foam, elastomeric
film, elastomeric nonwoven laminate, elastomeric scrim or the like,
or other materials or combinations of materials commonly used for
such purposes. The absorbent pad elements 24 and the elastomeric
elements 26 are located intermediate a backsheet 28 and a topsheet
30.
[0026] The backsheet 28 is generally that portion of the diaper
which prevents the exudates absorbed and contained therein from
soiling articles which may contact the diaper, such as bedsheets
and undergarments. The backsheet 28 may be impervious to liquids
(e.g., urine) and include a thin plastic film. Other suitable
backsheet material may include breathable materials which permit
vapors to escape from the diaper while still preventing exudates
from passing through the backsheet. Examples of breathable
materials include woven webs, nonwoven webs, composite materials
such as film-coated nonwoven webs, and microporous films.
[0027] The topsheet 30 may be compliant, soft feeling, and
non-irritating to the wearer's skin. Further, at least a portion of
the topsheet 30 may be liquid pervious, permitting liquids to
readily penetrate through the thickness of the topsheet. The
topsheet may be made of a hydrophobic material or may be treated to
be hydrophobic in order to isolate the wearer's skin from liquids
contained in the absorbent pad. If the topsheet is made of a
hydrophobic material, at least the upper surface of the topsheet is
treated to be hydrophilic so that liquids will transfer through the
topsheet more rapidly. This diminishes the likelihood that body
exudates will flow off the topsheet rather than being drawn through
the topsheet and being absorbed by the absorbent pad. The topsheet
can be rendered hydrophilic by treating it with a surfactant or by
incorporating a surfactant into the topsheet. A suitable topsheet
may be manufactured from a wide range of materials, such as porous
foams; reticulated foams; apertured plastic films; or woven or
nonwoven webs of natural fibers (e.g., wood or cotton fibers),
synthetic fibers (e.g., polyester or polypropylene fibers), or a
combination of natural and synthetic fibers. If the absorbent
assemblies include fibers, the fibers may be spunbond, carded,
wet-laid, meltblown, hydroentangled, or otherwise processed as is
known in the art.
[0028] The continuous webs of backsheet material 28 and topsheet
material 30 may be maintained under very slight tension in the
machine direction (i.e., along the web longitudinally) to reduce
wrinkling and to facilitate registration with the diaper assembly
and converting operations until the completed diaper web is severed
into discrete diapers 22.
[0029] The absorbent pad segments 24 are fed into a nip (not shown)
between a pair of combining or laminating rolls 34 at regularly
spaced intervals. The absorbent pads 24 may comprise any absorbent
material which is generally compressible, conformable,
non-irritating to the wearer's skin, and capable of absorbing and
retaining liquids such as urine and other certain body
exudates.
[0030] The elastomeric patches 26 may be secured to the backsheet
28, topsheet 30 or both utilizing either an intermittent bonding
configuration or a substantially continuous bonding configuration.
The intermittent bonding configuration may be desirable in those
situations where a relatively high degree of z-direction bulking is
desired in the finished product. Conversely, a continuous bonding
configuration may be desirable where a relatively lower degree of
z-direction bulking is desired in the finished product.
[0031] The web of backsheet material 28 is directed to a glue
applicator 36. The glue or adhesive 38 may be heated or unheated.
If an intermittent bonding pattern is used, the glue applicator 36
may be used to apply discrete, spaced apart spots, lines, or
spirals of adhesive in the predetermined areas of the backsheet 28
where the substantially untensioned elastomeric patches 26 will be
placed.
[0032] Alternatively, if a substantially continuous bonding pattern
is utilized, the glue applicator may be used to apply a
substantially uniform and continuous application of adhesive 38 to
the backsheet 28 in those predetermined areas of the backsheet 28
where the substantially untensioned elastomeric patches 26 will be
placed. Instead of using an adhesive, the backsheet 28 and/or
topsheet 30 may be bonded to the elastomeric patches 26 using heat
bonding, pressure bonding, ultrasonic bonding, etc. In such
instances, thermal energy may, if desired, be applied to the
backsheet 28 by other means well known to those skilled in the art,
e.g., radiant heaters, hot air blasts, etc., to achieve a similar
result.
[0033] Two rolls of elastomeric material 40 are fed under very
slight (essentially "zero strain") tension at a speed which
provides the desired length of elastomeric patch 26 per diaper onto
an anvil roll 42 equipped with vacuum hold down ports (not shown)
at its periphery. A knife 44 makes one cut per diaper and the
substantially untensioned elastomeric patches 26 travel with anvil
roll 42 secured to its periphery by vacuum until they reach
transfer location 46. At location 46 the elastomeric patches 26 are
transferred to predetermined portions of the backsheet web 28
coinciding with adhesive 38. The transfer is sequential and the
surface speed of the vacuum equipped anvil roll 42 and the
backsheet web 28 are essentially equal. The backsheet web 28 with
elastomeric patches 26 attached thereto at predetermined points
along its length is then directed to the pair of laminating or
combining rolls 34.
[0034] The continuous web of topsheet material 30 is directed to a
second glue applicator 48 where a pattern of adhesive 50 is sized
to substantially match the dimensions and locations of the
elastomeric patches 26 on backsheet web 28. As with backsheet
material 28, the pattern of adhesive applied to the topsheet
material 30 may be either intermittent or substantially continuous.
If desired, adhesive applicator 48 may be identical to adhesive
applicator 36.
[0035] The backsheet web 28 and the topsheet web 30 and the
absorbent pads 24 are brought into contact with one another at
combining rolls 34. Just prior to the webs and pads coming into
contact with one another, additional adhesive is applied to one or
both webs by means which are, for clarity, not shown in FIG. 1. The
latter adhesive secures predetermined portions of the backsheet,
topsheet and absorbent pad to one another to form the diaper web
20. The fully assembled diaper web 20 may thereafter proceed
through a pair of bond setting rolls 52, which may include chilling
to minimize glue bleed through.
[0036] The fully assembled diaper web 20 is then directed through
an activation system 54. One example of an activation system is set
forth in U.S. Pat. No. 6,500,377 titled "Method and Apparatus for
Activation a Moving Web," issued Dec. 31, 2002, which is hereby
incorporated by reference herein. The activation system is arranged
to intermittently stretch the web laterally (i.e., in the
cross-machine direction).
[0037] FIG. 2 illustrates a portion of the diaper web 20 defining
one diaper 56 after it is cut from the web (bounded by vertical
dashed lines) and adjacent diapers. The diaper includes the
absorbent core 24, a first elastic waistband section 58 and a
second elastic waistband section 60, along with the elastic side
panel sections 26. When fitted to a person, the absorbent core is
in the crotch region, the waistband areas are circumferentially
fastened together around the user's waist, and the leg cutouts 62
(cut after the centering and spreading operations discussed below)
are around the user's legs. The activation operation stretches the
web in the cross-machine direction 64 generally along the waistband
and the side panel areas, which activates the waistband and side
panels so that the waistband and the side panels are elastically
extensible after the diaper is removed from the web. In one
implementation, the web is stretched in the side panel region a
greater degree than it is stretched in the absorbent region.
Activation causes a variable web width and also variable web
tension, which can cause the web to wrinkle.
[0038] Web wrinkling sometimes involves folds 66 or wrinkles
running somewhat longitudinally in the machine direction as shown
in FIG. 3, which illustrates the wrinkled web before it enters a
camber roller 68. The presence of wrinkles can be problematic for
subsequent web processing steps. For example, in the diaper
assembly process discussed herein, if the fully assembled diaper
and activated web is processed in a side notch cutting tool 72A
that cuts the leg notches 62 in the web 20 for each individual
diaper, or in a knife tool 72B that cuts the web into individual
diapers, then the presence of wrinkles can cause uneven leg
notches, uneven diaper dimensions, ragged and uneven edges, among
other problems. Accordingly, one aspect of the present disclosure
involves an apparatus and method for spreading the web to remove
wrinkles.
[0039] In a system for fabricating diapers from a web, such a
spreading apparatus 70 is positioned after the activation station
54 and before any subsequent cutting stations 72, as shown in FIG.
1. Also, a web centering station 74, including camber roller 68, is
positioned before the web spreading station 70 so that the web is
substantially centered with respect to the machine center line
before it enters the spreader assembly 70. Such a system may be
used in any web processing system where lateral web spreading is
desirable, whether or not to remove wrinkles from a web.
[0040] FIGS. 4 and 5 illustrate rear isometric views of one example
of a web centering and spreading mechanism 76. FIG. 6 illustrates
an exploded isometric view of the web centering and spreading
mechanism. The web centering and spreading mechanism includes two
primary components, the centering station 74 and the spreader
assembly 70. The web, including wrinkles, first enters the
centering station, which in one particular implementation involves
a camber roller assembly (see, e.g., FIG. 4) where it is
substantially centered with respect to the machine center line.
From the camber roller, the web then proceeds to a set of edge
sensors 78 (see, e.g., FIG. 5) that detect the outer edges of the
web 80 (see FIG. 1) and provide a feedback signal to the camber
roller 74 to center the web and also provide a feedforward signal
to the spreader assembly 70 for adjusting the amount spreading.
From the edge sensors, the web proceeds to the power spreader
assembly 70 (see, e.g., FIG. 5) where any wrinkles or folds are
stretched out of the web. In the example implementation shown
herein, the camber roller assembly and the power spreader assembly
are shown supported on a common frame. However, in a system
conforming to aspects of this disclosure, the camber roller
assembly, or other web centering device, and related edge sensors
or other sensor types or arrangements, along with the power
spreader assembly may be supported on separate frame assemblies.
Additionally, other stations may be positioned between the
centering station and the spreader station, and the centering
station and/or the spreader station may be set forth in combination
with other components, stations, or the like.
[0041] The camber roller assembly 74 is configured to center the
web on the camber roller 68 such that the web will be substantially
centered on the power spreader assembly. The edge sensors 78 are
connected to a servo motor 82 on the camber roller assembly in a
feedback configuration. The edge sensors detect each outer edge 80
of the web as it runs through the sensors and sends feedback
signals to the camber roller assembly to adjust the camber roller
68 to center the web.
[0042] Referring primarily to FIGS. 4, 6 and 7, the camber roller
assembly includes the camber roller 68 rotatably supported between
a pair of brackets 84. The axis 86 of the camber roller is
perpendicular to the machine direction (perpendicular to movement
of the web) so that the web moves evenly over the roller, and
maintains a straight path between rollers of the system. The axis
of the camber roller is generally perpendicular to the machine
direction (oriented in the cross-machine direction), but is movably
mounted so that the roller 68 may be moved slightly away from
perpendicular to the machine direction. In this way, the web moving
over the roller can be adjusted from side-to-side on the roller to
center the web. Due in part to the presence of wrinkles and the
lateral activation operation imparted on the web, the web moving
from the activation station 54 may be uncentered and/or may have
uneven edges (the outer edges of the web are not equidistant from
the outer edges of the camber roller, for example, due to the
presence of wrinkles).
[0043] Returning to the discussion of the camber roller assembly,
each bracket is coupled to a servo motor assembly 88. The servo
motor 82 is operably coupled with a pair of roller guides 90. Each
roller guide includes a guide rod 92 or other member defining an
axis angularly offset from the cross-machine direction. In the
particular embodiment illustrated herein, the roller guides are
each arranged with a forward angle such that each respective guide
rod (92A, 92B) has an outer end in a rearward orientation and a
forward end in a forward orientation toward the center of the
roller 68. Hence, the rods (92A, 92B) converge toward each other
forward the center of the roller. For purposes of this discussion,
the front of the machine is the side shown in FIGS. 4-7. Further,
the guide blocks (94A, 94B) are movably supported on the guide rods
(92A, 92B). The servo motor is coupled to the left guide block to
cause the guide block to move along the guide rod 94A. In this way,
as shown by the arrows of FIG. 6, if the left guide block 94A, for
example, moves slightly leftward and the right guide block 94B is
also moved leftward along respective guide rods, then the camber
roller is adjusted such that its left side is moved rearward and
its right side is moved forward. In contrast, if the left guide
block moves slightly right and the right guide block
correspondingly moves slightly right, then the camber roller is
adjusted such that the left side moves slightly forward and its
right side moves slightly rearward. By adjusting the camber roller
in this way, the edges of the web 80 and the web 20 itself may be
substantially centered on the camber roller. Referring to the first
example and the associated arrows, if the left and right blocks
(94A, 94B) are moved leftward causing the camber roller 68 to be
angularly positioned with respect to the web such that the left
side of the camber roller (68A) is slightly rearward and the right
side of the camber roller (68B) is slightly forward, the web 20
will track laterally across the roller from right to left. As the
web moves through the edge sensors 78, the left and right edges 80
of the web are detected and corresponding feedback signals are
provided to the servo 82 to adjust the camber roller to keep the
web centered on the roller.
[0044] Various degrees of folding and web off-center variance may
be experienced in any particular implementation. It is possible,
for example, for there to be between 10-15 millimeters of variance,
and hence the camber roller to adjust the web to account for this
degree of variance, which may not result in the web being precisely
centered. The web will experience some degree of off-center
variance even after centering due to variability in folds and the
degree to which any particular centering implementation can account
for such variance. Further, it is possible to deploy others
mechanisms to center the web, such as an offset pivot guide, a
pivot table, etc., some of which are supplied by FIFE Corporation
as referenced herein. The term "centering" or the like as used
herein indicates that the web is adjusted or otherwise positioned
so that the web enters the spreader assembly with the web edges
relatively evenly fed in the assembly to substantially uniformly
spread the web to remove folds. In a particular implementation
where the machine center line corresponds with the center line of
the spreader roller, as discussed above, and the spreader plates
are symmetrically positioned relative to the machine center line,
then "centering" indicates that the web is adjusted so that the web
edges are substantially equidistant from the machine center
line.
[0045] FIGS. 8A-8C illustrate representative examples of the web 20
as it enters the camber roller with a wrinkle 66 and with
misaligned edges (80A, 80B) (FIG. 8A), as the folded web exits the
camber roller and enters the power spreader with the edges centered
(FIG. 8B), and finally as the unwrinkled and centered web exits the
spreader. FIGS. 8A-8C are discussed in conjunction with the method
set out in the flowchart of FIG. 9. Referring first to FIG. 8A, it
can be seen that when the web 20 enters the camber roller assembly,
the web may include a fold 66 or a wrinkle and the web may not be
centered. In the example of FIG. 8A, there is a fold along the left
side of the web. Additionally, the left edge (80A) of the web is
positioned to the right of a left web edge target location 96A by
amount X.sub.1. The right side of the web does not have a wrinkle
or fold and the right edge 80B of the web is outside (to the right)
of a right web edge target location 96B by amount X.sub.2. The left
web edge and right web edge target locations correspond to the full
width of the web centered on the roller. Thus, processing of the
web by centering and spreader assemblies discussed herein begin
with a folded web (operation 900, FIG. 9). The target locations are
equidistant from the respective outer edge of the roller and the
machine center line M, in one example.
[0046] After the web has moved through the camber roller assembly,
as shown in FIG. 8B, the fold 66 on the left side of the web is
still present, but the left and right edges (80A, 80B) of the web
have been substantially centered (i.e., the left and right edges of
the web are substantially equidistant by amount X.sub.3 from the
left and right target locations (96A, 96B) (operation 910). Due to
the presence of the fold, the web center line W is not aligned with
the machine center line M, even though the folded web and the left
and right edges of the web have been centered. As discussed above,
some form of sensor arrangement, whether edge sensors or otherwise,
detect the position of the web relative to the machine center line
and provide the appropriate signals to the centering mechanism
(operation 920). The sensors may be positioned to detect the web
edges or other aspect of the web before or after the centering
mechanism. The sensors also provide a signal or signals to the
spreader mechanism to adjust the degree of spreading commensurate
with the relative position of the edges (80A, 80B) to the target
location (96A, 96B). Hence, the greater X.sub.3, the greater degree
of spreading and the lesser X.sub.3, the lesser degree of
spreading.
[0047] As will be discussed in further detail below with respect to
the spreader mechanism and referring now to FIG. 8C, when the web
20 is subsequently processed in the spreader assembly, the fold is
removed from the left side of the web and the web is spread such
that left and right outer edges (80A, 80B) of the web are aligned
with target locations (96A, 96B) and thus the center line W of the
web is aligned with the machine center line M (operation 930).
[0048] Referring now in more detail to the power spreader assembly
70 illustrated in FIGS. 4-7 and 10-11, the power spreader assembly
includes an outer roller sleeve 98 mounted on a roller body 100
defining a spreader roller 102. The roller sleeve supports the web
as the web moves over the power spreader assembly. The power
spreader assembly includes four opposing spreader plates (104A,
104B, 104C, 104D). The spreader plates are positioned as two pairs
(104A, 104C and 104B, 104D) spaced 180 degrees apart on the outer
surface of the sleeve 98. Each pair of spreader plates is arranged
to synchronously oscillate along the outer surface of the roller
sleeve from an inner location when a pair of plates first contacts
the web outwardly along the sleeve to spread the web and then back
to the inner location as the spreader roller rotates to position
the pair of plates 104 to again engage the web. When one pair of
plates is at an outer location and beginning to reset to an inner
position, the other pair is at an inner location and moving
relatively outwardly to spread the web.
[0049] As shown in FIG. 10 and others, each spreader plate is a
substantially rectangular member defining an arcuate contour with
the same diameter as the outer circumference area of the roller
sleeve. Accordingly, each spreader plate 104 is arranged flatly
against the outer surface of the roller sleeve 98.
[0050] The outward facing surface of each spreader plate 104
defines two different surface areas, an outer rough 106 or gripping
surface that is arranged along the side of the spreader plate
adjacent to the outer edges of the spreader roller and an inner
smooth surface 108. As the spreader plates engage the web and move
from an inner position outwardly (see arrows of FIG. 10), the outer
gripping surfaces engage the outer edge 80 regions of the web and
pulls each outer edge outwardly over the roller sleeve. The inner
smooth area of the spreader plate allows the web material to move
over the spreader plate without binding. In this way, the spreader
plates spread the web outwardly toward each side of the roller (and
target locations 96A, 96B) and also allow web wrinkles and folds 66
to be removed as the portion of the web engaging the smooth section
of the spreader plate is able to slide over the plates.
Additionally, as mentioned above, the roller sleeve 98 defines an
inner recessed region 110 centrally located between the outer
raised regions 112 of the sleeve that support the spreader plates.
Thus, the inner area has a lesser circumference than the adjacent
outer area. With this configuration, the area of the web positioned
over the recessed region 110 of the sleeve is able to be stretched
and moved without binding on the roller sleeve surface. The web can
move over the roller surface without the recess; however, the
recess helps to prevent the web from snagging or otherwise engaging
some surface and thereby preventing some of the wrinkle from
unwrinkling.
[0051] Referring now primarily to FIGS. 4, 6 and 11 (illustrating
exploded views of the power spreader assembly) the spreader plates
(104A-104D) are each mounted to respective plate coupling members
(114A-114D). The plate coupling members are each coupled to a
spreader mechanism 116 and are each provided in a channel 118 in
the roller sleeve. For each pair of plates and associated plate
coupling members there is an associated pair of aligned channels
118 in the cross-machine direction. The channels run from an inner
area outwardly toward the outer edge of the sleeve. Accordingly,
the coupling members 114 moving in the respective channels are able
to move the spreader plates 104 inwardly and outwardly by way of
the spreader mechanism discussed below.
[0052] Referring primarily to FIG. 11, the spreader mechanism 116
supports each spreader plate (104A-104D) such that when one pair of
spreader plates is moving inwardly toward each other (e.g., plates
104B and 104D), the opposing pair of spreader plates (e.g., plates
104A and 104C) located 180 degrees from the first pair of spreader
plates, are moved outwardly away from each other toward the outer
edges of the roller sleeve. This allows a pair of spreader plates
to engage and begin spreading the web every half rotation of the
spreader roller. It is possible to only include one pair of
spreader plates, but such a single pair would only engage the web
once per rotation of the roller. Other plate arrangements and
mechanisms are also possible.
[0053] The spreader mechanism includes the first plate coupling
member 114A coupled to the opposing second coupling member 114B by
way of a cross-coupling member 118. Similarly, the spreader
mechanism includes the third plate coupling member 114C coupled to
the respective opposing fourth plate coupling member 114D by way of
a second cross-coupling member 120. Accordingly, the first plate
coupling member 114A on one side of the roller sleeve is operably
connected to the second coupling member 114B on the opposing side
of the sleeve. Similarly, the third coupling member 114C is
connected to the respective fourth coupling member 114D on the
opposite side of the sleeve. The second plate coupling member 114B
is clamped to a first piston rod 122 and the third plate coupling
member 114C is clamped to a second piston rod 124. The first piston
rod is configured to move freely through a sleeve 126 in the fourth
plate coupling member 114D while the second piston rod is
configured to move freely in a sleeve 128 in the first plate
coupling member 114A. Thus, when the first piston rod 120 moves
along its axis, it causes the second plate coupling member 114B and
the first coupling member 114A to move in the same direction.
Similarly, when the second piston rod 124 moves along its axis, it
causes the third and fourth coupling members (114C and 114D) to
move in the same direction.
[0054] One end of each respective piston rod are coupled to a
wobble plate 130, while the right side of each rod is movably
supported in a respective sleeve 132. The wobble plate is
configured to teeter about a point between the piston rods such
that the piston rods move in opposing directions. For example, if
the first piston rod moves in direction D.sub.1, the second piston
rod will move in direction D.sub.2. Note, FIG. 11 illustrates the
opposite side of the spreader assembly from FIG. 4, among others.
Thus, the D.sub.1 and D.sub.2 directional arrows are illustrated
appropriately.
[0055] Discussing now the coordinated movement of the spreader
assembly, if the first piston rod 122 moves in Direction D.sub.1,
then the second plate coupling member 114B will similarly move in
direction D.sub.1 along with attached spreader plate 104B, which
moves from an outer position along the roller sleeve to an inner
position along the roller sleeve.
[0056] As the first plate coupling member 114A is operably
connected with the second plate coupling member 114B by way of the
cross-coupling member 118, when the first piston rod 122 moves in
direction D.sub.1, the first plate coupling member 114A also moves
in direction D.sub.1 from an inner position along the roller sleeve
to an outer position along the roller sleeve (see also FIG. 10),
opposite the relative direction of the second plate coupling member
(moves from an outer position to an inner position). As the first
piston rod 122 is moving in direction D.sub.1, the second piston
rod 124 is moving oppositely in direction D.sub.2. Accordingly, the
third plate coupling member 114C moves outwardly from the inner
position along the sleeve to an outer position along the sleeve. As
the fourth plate coupling member 114D and associated spreader plate
104D are coupled to the third plate coupling member 114C by way of
the cross-coupling member 120, the fourth plate coupling member
114D moves inwardly from an outer position along the roller sleeve
to an inner position along the roller sleeve as the second piston
rod moves along D.sub.2. In this way, the second and fourth plate
coupling members (114B, 114D) and the respective spreader plates
(104A, 104C), move inwardly from outer positions on the roller
sleeve to inner positions on the roller sleeve, and in
synchronization the opposing first and third plate coupling members
(114A, 114C) and respective spreader plates (104A, 104C) move in a
coordinated fashion from an inner position on the roller sleeve to
an outer position on the roller sleeve. When the first piston rod
moves along D.sub.2 and the second piston rod moves along D.sub.1,
the opposing movements are imparted on the spreader plates (i.e.,
the first and third plate coupling members move from outward
positions to inward positions and the second and fourth plate
coupling members move from inward positions to outward
positions).
[0057] An actuator 134 is coupled to the wobble plate 130 at member
136. The actuator controls the degree of actuation (or teetering)
of the wobble plate and hence the degree of stroke of the piston
rods (122, 124). The actuator may be configured to receive a signal
from the edge sensors 78, and use the signal to control the degree
of actuation of the wobble plate. Hence, if the edge sensor detects
a relatively wider web (indicative of a lesser degree of folding)
compared to a relatively narrower web (indicative of a greater
degree of folding), then the actuator is configured to provide a
lesser or greater degree of stroke on the piston rods,
respectively. In this way, the plates will impart a greater or
lesser degree of relative movement to spread the web a greater or
lesser degree. So, for example, if the edge sensors detect a
relatively wider web indicative of a relatively lesser degree of
folding or wrinkling, then the actuator will impart a relatively
lesser degree of stroke and consequently lesser degree of relative
movement of the spreader plates. This allows the spreader plates to
spread the web sufficiently to remove the fold or wrinkle, but not
overspread the web, which may deform some of the elastic
components, which may then not have sufficient time to contract to
normal size in the immediately following side cutting stage 72A
(which cuts the leg notches in the example of a diaper) and
otherwise damage the web in any particular configuration.
[0058] Although various representative embodiments of this
invention have been described above with a certain degree of
particularity, those skilled in the art could make numerous
alterations to the disclosed embodiments without departing from the
spirit or scope of the inventive subject matter set forth in the
specification and claims. All directional references (e.g., upper,
lower, upward, downward, left, right, leftward, rightward, top,
bottom, above, below, vertical, horizontal, clockwise, and
counterclockwise) are only used for identification purposes to aid
the reader's understanding of the embodiments of the present
invention, and do not create limitations, particularly as to the
position, orientation, or use of the invention unless specifically
set forth in the claims. Joinder references (e.g., attached,
coupled, connected, and the like) are to be construed broadly and
may include intermediate members between a connection of elements
and relative movement between elements. As such, joinder references
do not necessarily infer that two elements are directly connected
and in fixed relation to each other.
[0059] In some instances, components are described with reference
to "ends" having a particular characteristic and/or being connected
to another part. However, those skilled in the art will recognize
that the present invention is not limited to components which
terminate immediately beyond their points of connection with other
parts. Thus, the term "end" should be interpreted broadly, in a
manner that includes areas adjacent, rearward, forward of, or
otherwise near the terminus of a particular element, link,
component, member or the like. In methodologies directly or
indirectly set forth herein, various steps and operations are
described in one possible order of operation, but those skilled in
the art will recognize that steps and operations may be rearranged,
replaced, or eliminated without necessarily departing from the
spirit and scope of the present invention. It is intended that all
matter contained in the above description or shown in the
accompanying drawings shall be interpreted as illustrative only and
not limiting.
[0060] The dimensions and values disclosed herein are not to be
understood as being strictly limited to the exact numerical values
recited. Instead, unless otherwise specified, each such dimension
is intended to mean both the recited value and a functionally
equivalent range surrounding that value. For example, a dimension
disclosed as "40 mm" is intended to mean "about 40 mm."
[0061] All documents cited in the Detailed Description of the
Invention are incorporated herein by reference; the citation of any
document is not to be construed as an admission that it is prior
art with respect to the present invention. To the extent that any
meaning or definition of a term in this document conflicts with any
meaning or definition of the same term in a document incorporated
by reference, the meaning or definition assigned to that term in
this document shall govern.
[0062] While particular embodiments of the present invention have
been illustrated and described, it would be obvious to those
skilled in the art that various other changes and modifications can
be made without departing from the spirit and scope of the
invention. It is therefore intended to cover in the appended claims
all such changes and modifications that are within the scope of
this invention.
* * * * *