Note: Descriptions are shown in the official language in which they were submitted.
CA 02526241 1998-04-14
DEVICE FOR UNWINDING A TISSUE ROLL
This application is a divisional application of Canadian Patent Application
Serial
Number 2,285,949 filed on April 14, 1998.
fdackaround of Invantigw
The present invention relates to methods for making and processing high bulk
tissue webs. More particularly, the invention pertains to a method of making a
tissue web
that is wound on large diameter parent rolls, unwound for finishing
operations, and
subsequently rewound.
Unwinds are useo widely in the paper converting industry, particularly in the
production of bathroom tissue and kitchen toweling. Manufactured parent rolls
are
unwound for finishing operations, such as calendering, embossing, printing,
ply
attachment, perforating, and then rewound into retail-sized logs or rolls. At
the time a
parent roll runs out in a traditional operation, the spent shaft or core must
be removed
from the machine, and a new roll moved into position by various means such as
an
overhead crane or extended level rails.
Historically, unwinds have made use of core plugs for support on unwind stands
with the power for unwinding coming from belts on the parent roll surface.
Such surface
driven unwind systems are not suitable for all types of tissue webs, because
they can
decrease the machine direction stretch, reduce the bulk, or damage the surface
of some
types of tissue webs, particularly high-bulk tissue webs. In contrast, center
driven unwind
systems have been used mainly in film unwinding.
The down time associated with a parent roll change represents a substantial
reduction in total available run time. In addition, the manpower required to
change a
parent roil tends to negatively impact the efficiency of a rewinder line, and
possibly even
the productivity of neighboring operations when workers are borrowed for roll
changes.
Even where a finishing unit is employed to bond the expiring web and the new
web
together, the webs are manually threaded and advanced resulting in significant
inefficiencies. Consequently, parent roll changes according to current
practices can
reduce the maximum output that can be obtained from a rewinder line, and may
adversely impact the productivity of neighboring operations as well.
Thus, there is a need for an improved method for making and processing a web
which maintains the desirable characteristics of the web, such as the bulk and
uniformity
of the web. There is also a need for an improved method for making and
processing a
web that dramatically reduces the time the machine is actually stopped, to
significantly
improve overall efficiency and to maintain or improve safety for all
personnel.
1
CA 02526241 1998-04-14
According to an aspect of the invention, there is provided a torque transfer
device
for unwinding a tissue roll that has a circumferential surface, opposite end
surfaces, an
inner core surface, an outside diameter of at least about 60 inches, and a
width between
the opposite end surfaces of at least about 55 inches, comprising: a frame
comprising a
pair of arms that are spaced apart to accommodate the width of the roll
therebetween,
each arm comprising a side clamping mechanism mounted thereon and adapted to
engage
one of the opposite end surfaces of the tissue roll, the side clamping
mechanism
comprising: a backing plate operably connected to and rotatable with an unwind
shaft that
is connected to an electric drive means; an inflatable bladder mounted on the
backing
plate; and means for inflating the bladder such that the opposite end surfaces
of the roll are
sandwiched between the side clamping mechanisms.
The advantages attributable to the supplemental torque transfer means compared
to traditional unwind assist devices, such as surface belts and rider rolls,
include: low
engagement pressures may be used due to the large available contact area; the
circurnferential surface of the roll is not damaged; torque is transmitted
directly to a
significant portion of the roll versus through the core and/or the
circumferential surface of
the roll; and operators can observe the complete circumferential surface of
the roll.
A method of making and processing a high bulk tissue web is described herein.
The
method comprises the steps of: depositing an aqueous suspension of papermaking
fibers
onto an endless forming fabric to form a web; drying the web to form a dried
web having a
bulk of 9.0 grams per cubic centimeter or greater; winding the dried web to
form a plurality
of parent rolls each comprising a web wound on a core; transporting the parent
rolls to an
unwind stand comprising a pair of spaced apart arms, each arm comprising
torque
transmitting means for engaging a parent roll; engaging the torque
transmitting means with
a first parent roll; partially unwinding the first parent roll using variable
speed drive means
operably associated with the torque transmitting means; rotatably supporting
the partially
unwound first parent roll on a core placement table that is adapted to receive
the partially
unwound first parent roll from the arms; engaging the torque transmitting
means with a
second parent roll; bonding a leading end portion of the web on the second
parent roll to a
trailing end portion of the partially unwound first parent roil to form a
joined web; and
rewinding the joined web.
Also disclosed is a method of making and processing a high bulk,
uncreped throughdried tissue web comprises the steps of: depositing an aqueous
2
CA 02526241 1998-04-14
suspension of papermaking fibers onto an endless forming fabric to fornn a
web;
transferring the web to a throughdrying fabric; throughdrying the web to form
an
uncxeped throughdried web having a bulk of 6.0 grams per cubic centimeter or
greater,
winding the dried web to form a plurality of parent rolls each comprising an
uncreped
throughdried web wound on a core; transporting the parent rolls to an unwind
stand
comprising a pair of spaced apart arms, each arm comprising torque
transmitting means
for engaging a parent roll; engaging the torque transmitting means with a
first parent roll;
partially unwinding the first parent roll using variable speed drive means
operably
associated with the torque transmitting means; rotatably supporting the
partially unwound
first parent roll on a core placement table that is adapted to receive the
partially unwound
first parent roll from the arms; engaging the torque transmitting means with a
second
parent roll; bonding a leading end portion of the web on the second parent
roll to a
trailing end portion of the partially unwound first parent roll to form a
joined web; and
rewinding the joined web.
The unwind stand may inGude a frame with pivotally mounted arms. The arms
desirably move the first parent roll to an unwind position for partially
unwinding the first
parent roll; then move the first parent roll to a position in close proximity
to or contact with
2a
CA 02526241 1998-04-14
the core placement table; and then move the second parent roll to an unwind
position for
partially unwinding the second parent roll core. When the webs from the first
and second
parent rolls are being spliced together, the variable speed drive means and a
core
placement drive motor simultaneously unwind the first and second parent rolls.
The webs of the parent rolls are desirably united using a thread-up conveyor.
The leading end portion of the web on the second parent roll is transported by
the
thread-up conveyor, which preferably comprises a vacuum means operably
associated
with an endless screen belt means. In one embodiment, the leading end portion
of the
web on the second parent roll is transported over the endless screen belt
means with
decreasing amounts of vacuum. Once the leading end portion of the web on the
second
parent roll is disposed on the trailing end portion of the web on the
partially unwound first
parent roll, the thread-up conveyor and unwinding of the second parent roll
are operated
at a same surface speed.
Advantageously, the thread-up conveyor may be moved, and in particular
pivoted,
relative to the second parent roll between an active position and a standby
position. In
the active position, the thread-up conveyor is in close proximity to or in
contact with tile
second parent roll, whereas in the standby position the thread-up conveyor is
positioned
away from the parent roll.
The core placement table is desirably moveable in a direction transverse to
the
path of travel of the web between an inline position and a standby position.
The inline
position corresponds to the web centerline to enable partially unwound parent
rolls to be
placed on the core placement table, whereas in the standby position the core
placement
table is positioned away from the unwinding operation for ease of operator
access.
Suitable soft, high bulk tissues for purposes of this invention include tissue
sheets
as described in U.S. 5,607,551 issued March 4, 1997 to Farrington, Jr. et a1.
entitled "Soft
Tissue", which is herein incorporated by reference. The method is particularly
useful for
soft, high bulk uncreped throughdried tissue sheets. Such tissues suitably
have bulk
values of 6.0 cubic centimeters per gram or greater (before calendering),
desirably about
9 cubic centimeters per gram or greater, more specifically from about 10 to
about 35
cubic centimeters per gram, and still more specifically from about 15 to about
25 cubic
centimeters per gram. The method for measuring bulk is described in the
Fartington. Jr.
et al. patent. In addition, the soft, high bulk tissues of this invention can
be characterized
by a relatively low stiffness as determined by the MD Max Slope andlor the MD
Stiffness
Factor, the measurement of which is also described in the Fartington, Jr. et
al. patent.
More specifically, the MD Max Slope, expressed as kilograms per 3 inches of
sample,
3
CA 02526241 1998-04-14
can be about 10 or less, more speafically about 5 or less, and stilt moro
specifically from
about 3 to about 8. The M!7 Stiffness Factor for tissue sheets of this
inven~on, expressed
as (kilograms per 3 inches)-microns°', can be about 150 or less, more
specifically about
100 or less, and still more specifically from about 50 to about 100.
Furthermore, the soft,
high bulk tissues of this invention can have a machine direction stretch of
about 10
percent or greater, more specifically from about 10 to about 30 percent, and
still more
specifically from about 15 to about 25 percent. In addition, the soft, high
bulk tissue
sheets of this invention suitably have a substantially uniform density since
they are
preferably throughdried to final dryness without any significant differential
compression.
Parent roll cores used in the present method preferably have an outside
diameter
of at least about 14 inches, and more particularly about 20 inches. The parent
rolls have
a face or circumferential surface, an inner core surface, and opposite end
surfaces. The
outside diameters of such rolls can be at least about 60 inches, and in
particular about
120 inches or greater, such as about 140 inches or greater. The widths of the
parent
rolls, measured between the opposite end surfaces, are generally at least
about
55 inches, more particularly at least about 100 inches, such as about 105
inches or
greater. Consequently, the weights of the rolls may be about 2000 Ibs. or
more,
particularly about 3000 Ibs. or more, and more particularly about 4000 Ibs. or
more.
In particular ~ embodiments, a center driven unwind system is employed to
eliminate or reduce the following detrimental effects on the web: 1. surtace
damage
(scuffing, tearing, etc.); 2, wrinkling of the web; 3. de-bulking; and 4.
stretch loss. All of
these detrimental effects are typical of a surface driven unwind on a low-
density
basesheet, such as an uncreped through-aim dried basesheet. These effects
negatively
impact the off-line finishing processes and/or the finished product. A large
factor in
creating these defects is the differential effects across the circumferential
surtace of a
parent roll due to the limited contact area with the surtace driven unwind
belts.
Specifically the possible defects are: 1. surface damage which introduces
defects or
tears that affect product performance and/or process runability; 2. wrinkling
which
impacts processes such as calendering, embossing, printing, ply-bonding,
perforating
and rewinding, thereby affecting finished product appearance, performance and
process
runability; 3, de-bulking which results in a denser web which affects product
pertom~tance
and preference; and 4. stretch loss which affects product performance and/or
process
nrnability.
The center driven unwind is used to preserve web attributes, such as high bulk
and stretch, during the unwinding process. The web is also treated
consistently across
4
CA 02526241 1998-04-14
the circumferentisi surface of the parent roll. Other system components, such
as dntw
control, are used to further protect the web. As an alternative to the center
driven
unwind, or in combination therewith, other suitable torque transmitting means
may be
employed to unwind the parent rolls. For example, the torque transmitting
means may
comprise side clamping mechanisms such as one or more inflatable bladders that
engage the opposite end surfaces of the parent rolls.
The addition of a torque transmitting means that engage the opposite end
surfaces of the parent rolls provides a further means of transferring torque
to the roll for
unwinding. This supplemental torque transfer may be desirable for relatively
high bulk
sheets, because the wound in tension in the roll may be reduced in order to
protect the
web properties. Lower wound in tension, though, adversely impacts the ability
to drive
the roll from the core. In high bulk sheets, using a center-driven unwind
system alone
creates the potential for slippage or shifting between the individual layers
of the roll as
well as between the initial sheet layers and the core, particularly during
periods of high
acceleration or deceleration. Rapid speed changes combined with a large mass
moment
of inertia produces high torque requirements resulting in very large
circumferential forces,
especially in areas near the core. The combination of large forces and lower
intertayer
pressures increases the likelihood of shifting between sheet layers, which
leads to
problems in the unwinding sequence such as web velocity or tension
variability,
telescoping of the parent roll and/or severe wrinkling of the web.
In one embodiment, the supplemental torque transfer means transmits torque
from the unwind shaft through the roll via the one or more inflatable bladders
that are in
pressure contact with the opposite end surfaces of the parent roll. The
bladders can be
supported by a backing plate that is operatively attached to the unwind shaft.
The
bladders can be deflated and thus disengaged as the parent roll is unwound to
smaller
diameters to eliminate disturbances with the web as it is peeled away from the
roll. The
bladders are suitably formed of an air or fluid impermeable material that is
conformable to
the end surfaces of the parent rolls, for example rubber, polyurethane, other
synthetic
polymers, or the like. Particularly suitable materials may have a coefficient
of friction of
about 0.3 or greater, and particularly about 0.5 or greater.
S
CA 02526241 1998-04-14
Also described is a method for making a web with dramatically less
down time needed to splice parent roll webs. The method utilizes a finishing
operation that substantially continuously impacts the web in order to splice
the
webs together. For purposes of the present invention, finishing operations
that
substantially continuously impact the web include embossing, crimping, and
even
calendering. These finishing operations desirably impact the web over the full
width of
the web so that a full-width splice is produced between the webs for improved
strength.
The term "substantially continuously impact" is used herein tv refer to
processes that
structurally modify the surface characteristics of the web, either
continuously as in
calendering or substantially continuously as in embossing or crimping, and
that form a
joined web for rewinding purposes when two webs from different parent rolls
are
processed simultaneously. This is in contrast to separate bonding units that
are only
intermittently operated to form a splice between webs from different roils.
This is also in
contrast to methods that inject bonding agents, such as glue, tape, or the
tike, in order to
splice the webs together.
A method of splicing tissue webs without glue or tape is described, comprising
the
steps of: partially unwinding a first tissue web from a first parent roll
using drive motor
means; transporting the first tissue web to a finishing unit comprising rolls
defining
a finishing unit nip; substantially continuously impacting solely the first
tissue web
in the finishing unit nip while the first tissue web is unwound from the first
parent
roll using drive motor means; partially unwinding a second tissue web from a
second parent roll; transporting the second tissue web to the finishing
6
CA 02526241 1998-04-14
unit using drive motor means; maintaining the first and second tissue webs
moveable
relative to one another upstream of the finishing unit; simultaneously
unwinding both the
first and second tissue webs from the first and second parent rolls using
drive motor
means and passing the webs jointly through the finishing unit nip to bond the
webs
together, and substantially continuously impacting solely the second tissue
web in the
finishing unit nip while the second tissue web is unwound from the second
parent roll
using drive motor means.
Thus, the webs from the expiring roll and the new roll are both driven through
the
first process nip, and are not bonded together until the first process nip.
Utilizing the first
finishing operation after the unwind to splice different parent roll webs
together eliminates
the need for separate bonding units and eliminates the need for external
bonding means
such as glue, tape, or the like. The present method replaces existing manual
methods
such as threading each new web or tying webs together.
The tissue product described herein can be one-ply, two-ply, three-ply or
more.
The individual plies can be layered or non-layered (homogeneous) and uncreped
and
throughdried. For purposes herein, "tissue sheet" is a single ply sheet
suitable for facial
tissue, bath tissue, towels, napkins, or the like having a density of from
about 0.04 grams
per cubic centimeter to about 0.3 grams per cubic centimeter and a basis
weight of from
about 4 to about 40 pounds per 2880 square feet. Tensile strengths in the
machine
direction are in the range of from about 100 to about 5,000 grams per inch of
width.
Tensile strengths in the cross-machine direction are in the range of from
about 50 to
about 2500 grams per inch of width. Ceilulosic tissue sheets of paper-making
fibers are
preferred, although synthetic fibers can be present in significant amounts.
Brief Description of the ~rawinas:
The invention is described in conjunction with the accompanying drawings:
FiG. 1 is a schematic side elevational view of an unwind system near the end
of
an unwind cycle;
F1G. 2 is a perspective side elevational view of the unwind system of FIG. 1
as
seen from the upstream drive side, i.e., _the side opposite the operator side,
wherein
upstream refers to the start of the path or stream of the web and downstream
refers to
the direction of the rewinder,
F1G. 3 is another perspective view of the unwind system but slightly more
downstream than F1G. 2 and showing the unwind in the middle of an unwind
cycle;
7
CA 02526241 1998-04-14
FIG. 4 is a schematic side elevational view corresponding to the perspective
view
of F1G. 3 but showing a full roil at the start of the unwinding cyde;
FIG. 5 is a top plan view of the unwind system as seen in the preceding views
but
with a portion broken away to reveal an othervvise hidden cylinder,
F1G. 6 is a schematic side elevationai view similar to FiG. 1 but from the
operator
side and also showing the condition of the apparatus as a parent roll is
almost completely
unwound, i.e., slightly later in the operational sequence than FIG. 1;
FIG. 7 is another sequence view now showing the beginning of the provision of
a
new parent roil;
FIG. 8 is a view of the apparatus in its condition slightly later than that
shown in
FIG. 7;
FIG. 9 is a view like the preceding views except that now a fully wound parent
roll
is installed in the unwind;
FIG. 10 is a view of the apparatus in a condition for coupling the leading
edge
portion of the new parent roll to the trailing tail portion of the almost
expended parent roll;
FIG: 11 is a view similar to F1G. 10 but now showing the two webs in the
process
of being bonded together;
FIG. 12 is a top plan view of the thread-up conveyor,
FIG. 13 is a side elevational view of the conveyor of FIG. 12;
FIG. 14 is a fragmentary perspective view from the operator side of the unwind
system and featuring the control means;
FIG. 15 is a partial schematic process flow diagram for a method of making a
tissue web, and in particular an uncreped tissue web;
FIG. 16 is a partial schematic process flow diagram illustrating a method of
splicing webs together utilizing a finishing unit;
FIG. 17 is a partial longitudinal section view of a torque transfer means for
transmitting torque from the unwind shaft through the roll via a side clamping
mechanism,
and in particular, an inflatable bladder;
FIG. 18 is a partial longitudinal section view similar to FIG. 17 but
illustrating an
alternative torque transfer means employing a plurality of inflatable
bladders; and
FIG. 19 is a partial longitudinal section view of another alternative torque
transfer
means, with portions broken away for purposes of illustration.
8
CA 02526241 1998-04-14
~taited~acrip3fc~n of the Dn~d~s,:
Referring tlrst to Figure 15, a method of carrying out this invention will be
described
in greater detail. Figure 15 describes a process for making a tissue web, and
particularly
an uncreped throughdried base sheet. Shown is a twin wire former having a
layered
papertnaking headbox 101 which injects or deposits a stream of an aqueous
suspension
of papermaking fibers onto a forming fabric 102. The resulting web is then
transferred to
a fabric 104 traveling about a forming roll 103. The fabric 104 serves to
support and carry
the newly-formed wet web downstream in the process as the web is partially
dewatered
to a consistency of about 10 dry weight percent. Additional dewatering of the
wet web
can be carried out, such as by differential air pressure, while the wet web is
supported by
the forming fabric.
The wet web is then transferred from the fabric 104 to a transfer fabric 106
traveling at a slower speed than the forming fabric in order to impart
increased MD
stretch into the web. A kiss transfer is carried out to avoid compression of
the wet web,
preferably with the assistance of a vacuum shoe 105. The web is then
transferred from
the transfer fabric to a throughdrying fabric 108 with the aid of a vacuum
transfer roll 107
or a vacuum transfer shoe. The throughdrying fabric can be traveling at about
the same
speed or a different speed relative to the transfer fabric. If desired, the
throughdrying
fabric can be nrn at a slower speed to further enhance MD stretch. Transfer is
preferably
cartied out with vacuum assistance to ensure deformation of the sheet to
conform to the
throughdrying fabric, thus yielding desired bulk, flexibility, CD stretch and
appearance.
The level of vacuum used for the web transfers can be from about 3 to about 15
inches of mercury (75 to about 380 millimeters of mercury), preferably about
10 inches
(254 millimeters) of mercury. The vacuum shoe (negative pressure) can be
supplemented or replaced by the use of positive pressure from the opposite
side of the
web to blow the web onto the next fabric in addition to or as a replacement
for sucking it
onto the next fabric with vacuum. Also, a vacuum roll yr rolls cart be used to
replace the
vacuum shoe(s).
While supported by the throughdrying fabric, the web is final dried to a
consistency
of about 94 percent or greater by a throughdryer 109 and thereafter
transferred to an
upper carrier fabric 111 traveling about roll 110.
The resulting dried basesheet 113 is transported between upper and lower
transfer
fabrics, 111 and 112 respectively, to a reel 114 where it is wound into a
parent roll 115
for subsequent unwinding, possible converting operations, and rewinding as
described
below. For the tissue making portion of this invention, the forming process
and tackle can
9
CA 02526241 1998-04-14
be conventional as is well known in the papertnaking industry. Such fomration
processes
inducts Fourdrinier, roof fom~ers such as a suction breast roll, gap formers
such as twin
wire formers and crescent formers, and other suitable formers. A twin wire
fom~er may be
preferred for higher speed operation. Forming wires or fabrics can also be
conventional.
the finer weaves providing greater fiber support and a smoother sheet and the
coarser
weaves providing greater bulk. Headboxes used to deposit the fibers onto the
forming
fabric can be layered or nonlayered, although layered headboxes are
advantageous
because the properties of the tissue can be finely tuned by altering the
composition of
the various layers. The throughdtyers and throughdrying fabrics can also be of
a
conventional nature.
In the central part of FIGS. 1 and 2, the numeral 20 designates generally a
frame
for the unwind stand which indudes a pair of side frames as at 20a and 20b,
the latter
being seen in the central portion of FIG. Z. The frame 20 pivotally supports
arm means
generally designated 21 which is seen to be essen6affy U-shaped. The arm on
the
operating side is designated 21a while the arm on the drive side is designated
21b.
Interconnecting and rigidifying the two arms is a transverse member 21 c. The
arms are
seen to support a parent roll R which, as can be quickly appreciated from a
consideration
of FIGS. 3 and 4, is in the process of being unwound to provide a web W. The
web W
proceeds over a roller 22 (designated in the center left of FIGS. 1 and 4) and
into a
bonding unit generally designated 23. These elements of the system are also
seen in
FIG. 5. The roller 22 may be an idler or driven.
Other elements depicted in FIGS. 1-4 are a thread-up conveyor generally
designated 24, a core placement table generally designated 25 and a means 26
such as
a cart for supporting a parent roil R' subsequently to be unwound (see FIGS. 1
and 2j. In
FIG. 2, the core C is dearly seen. Also, at the extreme left in FIGS. 2 and 3,
a rewinder
RW is seen to be at the downstream end of the system.
It is believed that various aspects of the invention can be appreciated most
quickly from an understanding of the sequence of operation which is depicted
in FIGS. 1
and 6-11.
FIG. 1
With the machine running and the diameter of the parent roil R decreasing, a
deceleration diameter is calculated by a control means generally designated
27. In
FIG. 2, this is partially obscured by the side frame 20a but can be seen
clearly in F1G. 14.
When the parent roll diameter reaches this determined diameter, the unwind and
associated equipment begin decelerating. During this time the core placement
table 25 is
CA 02526241 1998-04-14
aligned with the web center line of FIG. 2, having previously been in the
standby position
of F1G. 3.
F1 6
When all machine sections reach zero or a reduced speed and the core table 25
is confirmed empty, the core placement position of the arm means 21 is
calwlated which
will set the expired parent roll Rx slightly above or lightly on the aadle
rollers 2B, 29 of
the core table 25. Advantageously, one of the cradle rollers 28 is driven,
while the other
is an idler.
The arm means 21 is now pivoted toward this calculated position, as shown in
FIG. 6. As the arm means moves under the signal from the control means 27, the
web W
can be unwound in order to prevent web breakage. wring this period the parent
roll cart
26 (see FIG. 6) is moved into the unwind loading position.
The cart movement is based on previous roll diameter, measured diameter or an
assumed diameter. The previous roll diameter is that of the last parent roll
when loade ~.
So the assumption is that the new parent roil has the same diameter and so the
position
of the "old" roll is the one selected for the "new" roll. The "measured"
diameter can be
that as actually measured, either mechanically or manually. The "assumed"
diameter is a
constant value selected by the operator which is used repeatedly as coming
near the
actual diameter. in any event, this pre-positions the cart to minimize
subsequent moves
which, if needed, could fnrstrate the achievement of a one-minute or less roil
change.
The cart movement is under the control of the control means 27. The object of
the
inventive unwind is to have its operation as automatic as possible, for both
safety and
efficiency.
The cart 26 may move into the position shown in the unwind along either the
machine directional axis or the cross directional axis. However, the cart 26
is shown
moving along the machine direction (see the wheels 30) in FIGS. 6-13 for
conceptual
clarity.
When the amn means 21 reaches the core drop position relative to the core
table 25 as shown in FIG. 6, the core chucks 31 (see FIG. 5) are contracted by
control
means 27 which allows both of the core chucks 31 (see particularly FIG. 2) to
be fully
retracted out of the core C (compare FIGS. 6 and 7), and the expired parent
roll R, placed
onto the core table 25. Advantageously, the control means 27 is a Model PIC
900
available from Giddings and Lewis, located in Fond du Lac, Wisconsin.
11
CA 02526241 1998-04-14
FIG. 7
As the artn means 21 moves toward this new posfion, photoelectric sensors 32
(see FIG. 5) which are mounted on the artn means 21, detect the edge of the
parent roll
loaded into the parent roll cart. When each sensor detects a parent roll edge,
the angular
position of the arm means 21 is recorded by the control means 27. Each data
point along
with known geometries and cart X-Y coordinates (see the designated arrows in
FIG. 7) is
used to calculate parent roll diameter and estimate X-Y coordinates of the
center of the
core C. Based on the core coordinates, the parent roll cart 26 is
repositioned.
With the parent roll R repositioned and artn means 21 moving toward the parent
roll loading position, the sensors 32 mounted on the arm means 21 (see FIG. 5)
will
detect the leading and trailing edge of the core. As each sensor 32 detects an
edge, the
angular position of the associated pivot arm is recorded in the control means
27.
This data, along with known geometries, is used to calculate multiple X-Y
coordinates of the center of the core. Coordinates are calculated separately
for each end
of the core. Averaging is used to obtain a best estimate of core coordinates
for each end
of the core.
The parent roll cart 26 is again repositioned to align the center of the core
C and
core chucks 31. If the cross directional axis of the core is property aligned
with the cross
directional axis of the cart 26, both the core chucks 31 are extended into the
core C and
the chucks are expanded to contact the core. The expansion and contraction of
the
chuck means 31 is achieved by internal air operated bladders or other
actuating means
under signal from the control means 27. Air is delivered through a rotary
union 33, shown
in the central portion of FIG. 3.
FIG. 8
FIG. 8 shows the arm means 21 in the loading position. If core skewing is
excessive, the alignment of the parent roll core and core chucks must be
individually
perfomned on each end of the core. First, the arm means 21 and possibly the
parent roll
cart 26 are positioned so that one chuck 31 can be extended into the core C.
Once in the
core, the first chuck is expanded. Next, the parent roll cart 26 andlor arm
means 21 is
repositioned to align the remaining core chuck 31 with the core C. Once
aligned, the
second core chuck 31 is extended and expanded.
When fully chucked, regardless of the chucking process, the parent roll R is
lifted
slightly out of the cart 26. Then, the parent roll is driven, i.e., rotatably,
by motors 34
(FIGS. Z and 5) which drive the chucks 31. Using motors on each arm evenly
distributes
12
CA 02526241 1998-04-14
the energy requirod. However, advantageous results can be ~tairted with
motorizing
only one of the chucks. Sufficient torque is applied by the core chuck drive
motors 34 to
test for slippage between a core chuck 31 and the core C. If slippage is
detected, the
parent roll is louvered back into the cart 28. The core chucks are contracted,
removed
from the core, and repositioned (i.e., "loaded' into the core. The core
slippage test is
then repeated. Multiple failures of this test can result in an operator fault
being issued.
FI . 9
If no slippage is detected, arm means 21 is moved to the winding position,
i.e.,
generally upright. As shown by FIG. 9, with the arm means in the run position,
the
vacuum thread up conveyor 24 is lowered into close proximity to or contact
with the
parent roll and the vacuum is activated. The core chuck drive motors 34 rotate
the parent
roll R. The thread-up conveyor 24 operates at the same surface speed as the
parent roll
surtace speed.
FIG. 10
Now referring to FIG. 10, when the leading end Le of the web on the parent
roil R
comes into contact with the vacuum conveyor 24, the tail is sucked up and
pulled along
by the vacuum thread up conveyor.
When the discharge end of the vacuum thread-up conveyor 24 is reached, the
new web end portion l.e drops onto the trailing end portion Te of the web from
the expired
parent roll Rx, depicted by FIG. 10. The rest of the machine line inGuding the
driven roller
28 is now brought up to match speed with that of the unwind.
FIG. 11
The new web is carried through the line with the web from the expired roll.
The
two webs can then be bonded together as at W in F1G. 11. An embossing-type
method
as at 23 is shown, but any method of web bonding could be used. After
combining the
webs, the web from the expired parent roll is no longer needed and brake means
associated with the core table or roller 2$ stops the expiring parent roll
from turning and
thus breaks the expired web. When appropriate, vacuum is removed and the
vacuum
thread-up conveyor is raised. The unwind nvw returns to previous running
speeds. As the
machine accelerates, the parent roll cart 28 is returned to its loading
position for another
roll and the core table is retracted to allow for core removal.
13
CA 02526241 1998-04-14
control Means
The control means 27 performs a number of functions. First, in combination
with
the parent roll cart means 26, it calculates diameter and determines the
position of the
core C for positioning the cart means for insertion of the chuck means 31 into
the parent
roll core. Further, the control means 2T includes means cooperating with the
sensor
means 32 for calculating the coordinates of the parent roll core and averaging
the
coordinates prior to insertion of the chuck means 31. Still further, the
control means
inGudes further means for comparing the alignment of the core cross-
directional axis with
the parent roll cross-directional axis.
When all is aligned, the control means 27 operate the chuck means 31 for
insertion into the core C by actuation of the cylinders 35 (see FIGS. 2 and
5). The control
means 27 further causes expansion of the chuck means 31 in order to internally
clamp
the tubular core C. Relative to the insertion of the chuck means 31, the drive
shaft of
each motor 34 is offset from the axis of the associated chuck means 37 as can
be seers
in the left central part of F1G_ 2 and the upper part of FIG. 5. There, the
motor 34 is
connected by a drive 36 to the shaft 37 of the chuck means 31. The shaft 37 is
rotatably
supported in the housing 38 of the chuck means 31. From the upper part of FIG.
5, it will
be seen that the motor 34 is offset from the shaft 37 and from the lower part
of FIG. 5 it
will be seen that the cylinder 35 is responsible for moving the housing 38 and
therefore
the chuck means 31 into engagement with the core C.
During normal operation, the control means also calculates the deceleration
diameter of the roll R being unwound, confirms the emptiness of the core table
25 and
operates the artn means 21.
Core Table and Threadup Conveyor
Reference to FIG. 5 reveals that the core placement table 25 is mounted in
rails
39 for advantageous removal during the unwind cycle. So if a web break occurs,
the
table is out of the web path so as not to interfere with clean-up. Also in
Fig. 5 the
thread-up conveyor 24 is seen to include a vacuum manifold 40 which provides a
plurality
of vacuum stages as at 41, 42, 43 and 44 of gradually less vacuum. The
conveyor 24 is
advantageously of screen or mesh construction to facilitate pickup of the
leading edge
portion of the web from the °newn parent roll.
Such a leading end portion may be folded to provide triangular shape to
facilitate
taping down. This helps prevent inadvertent detachment of the leading edge
portion from
14
CA 02526241 1998-04-14
the underlying p!y during transfer of the paront roll from the paper machine
to the site of
rewinding. Normally, the first log nswound from a new parent roll is discarded
so this
eliminates the concern over a lumpy Vansfer.
As part of the program of operation of the unwind under the control of the
control
means 27, the conveyor 24 and vacuum from a pump (not shown) are both shut
down to
conserve energy and avoid unnecessary noise.
The thread-up conveyor 24 is pivotally supported on a pair of pedestals 45
(see
the right lower portion of FIG. 13) which provides a mounting 48 for each side
of the
conveyor 24 (see FIG. 12). The mountings 48 rotatably carry a cross shaft 47
which is on
the axis of the lower (driving) roller 48. At its upper end, the conveyor has
an idler roller
49 supported on the staged chamber generally designated 50 which is coupled to
the
manifold 40.
Positioning of the conveyor 24 via changing its angle is achieved by a pair of
pressure cylinders 57 coupled between the pedestals 45 and the chamber 50. The
cylinders 51 are also under the control of the control means 27.
~vstem Parameters
To enable the control means 27 to calculate the deceleration diameter near the
end of the unwind cyGe, a further sensor 52 is provided on the transverse
member 21c of
arm means 21, as seen in FiG. 5. In addition, the sensor continually reports
the radius of
the parent roll and the control means continually calculates the motor speed
to obtain a
desired unwind. Alternatively, process feedback such as load cells or dancers
can be
used to report to the control means changes in tension or the like and enable
the control
means to vary the motor speed.
Once the rewinder is located, which is a primary consideration because of its
involvement with the core hopper, core feed, log removal and log saw, the
unwind
frame 20 is placed a suitable distance upstream to accommodate the core
placement
table 25, the thread-up conveyor 24 and any bonding unit 23.
The location of the core placement table 25 is a function of the pivot
geometry of
the arm means 21 as can be appreaated from a consideration of FiG. 6. On the
other
hand, the location of the thread-up conveyor 24 is not only a function of the
arm means
geometry but also the size parent rolls to be unwound.
In a similar fashion to the location of the core table 25, the cart 26 must be
placeable to have the parent roll engageable by the chucks 31 of the arm means
21.
CA 02526241 1998-04-14
The unwind system, although having a means for actually rotating the parent
roll,
really includes a path or section of a mill's converting area extending from
the cart
means 28 which provides the next parent roll, all the way to the rewinder
proper.
Structural Features
The unwind system includes many significant structural features which are
discussed below. For example, unwind system employs the roll cart means 28
operably
assoaated with the frame 20 for supporting a "new" parent roll R', the roll
cart means 28
cooperating with the control means 27 for positioning the chuck means 31 and
inserting
the same into a parent roll core C.
Further, the control means 27 includes sensor means 32 cooperatively coupled
together for calculating the coordinates of the "new" parent roll R' and
averaging the
coordinates prior to insertion of the chuck means 31.
SGII further, the control means 27 inGudes the capability to compare the
alignment
of the core cross directional with the parent roll cross directional axis. The
control means
capability also includes the controlling of the insertion of the chuck means
31 into the
core C by, for example, controlling the operation of the fluid pressure
cylinders 35.
Near the end of the unwinding cycle, the control means 27 regulate the pivotal
movement of the arm means 21 as a function of the degree of unwinding of the
parent
roll R. Also during the unwinding cycle (during its last stages generally),
the control
means 27 in combination with sensing means 53 determines the condition of the
core
placement table 25 (see the left center portion of FIG. 5).
Near the very end of the unwinding cycle it is important for the core
placement
table to be in position to receive the almost-expired roll Rx, be free of any
obstructing
material and also have its rotating roller 28 in operation. But at the very
end, motor and
brake means 54 operably associated with the roller 28 are energized to snap
off the
web W, with a minimum of web tail retained on the table 25 -- optimally about
%.° (6 mm).
Prior to the time referred to immediately above, but again toward the end of
an
unwinding cycle, the control means actuates the thread-up conveyor 24 via a
drive 55
(see the lower left of FIG. 12). The drive 55 is coupled to the drive 56 of
the driven
roller 22 (see FIG. 5) which, in time, is driven by a motor (not shown). Also,
there is
actuation of a vacuum pump (not shown) to apply a reduced pressure to the
manifold 40.
As indicated above, the disclosed method and unwind system for large diameter
parent rolls is completely automated to avoid the need for manual handling of
cumbersome and potentially dangerous rolls. At the outset, the cart 26 is
advantageously
16
CA 02526241 1998-04-14
equipped with an upper table 57 (see FIG. 2) which is rotatal~e about a
vertical axis
duouqh an anc of 90° to psrtnit cantilever delivery of a new parent
roll whose axis is
parallel to the length of the web path, i.e., from cart 28 to bonding station
23. The
controller 27 thereupon causes the table 57 to rotate to the position shown in
FIGS. 2
and 3 for commenting the unwind cycle. As the previous parent roll nears
expiration, the
arm means 21, which have been detached from the previous roll core are
automatically
pivoted from downstream to upstream and the chucking of the core perfomned
automatically as descrtbed above. Then, at the end of the cycle, the depleted
core is
deposited on the table 25 and the arm means 21 upchucked far the initiation of
another
cycle.
FIG. 16
FIG. 16 illustrates an automated off tine method for splidng tissue webs from
different parent roils for subsequent rewinding. The method utilizes a
finishing unit that
substantially continuously impacts each web during unwinding to form the
splice between
the webs. As illustrated, an expiring roll Rx has been deposited on the core
placement
table 25. The web W from the expiring roU Rx is desirably transported in
sequence to a
calendering unit 130 and an embossing unit 140. Either the catendering unit or
the
embossing unit substantially continuously impacts the web W during the time
that the
web is unwound from its parent roll Rx. The calendered and embossed tissue web
W may
then be wound at a rewinding unit RW. For example, the tissue web W may be
wound
onto tissue roll cores to forth logs, which are subsequently cut into
appropriate widths
and the resulting individual tissue rolls are packaged (not shown).
The catendering unit 130 comprises a pair of calendering rolls 132 and 134
that
together define therebetween a calendering nip 136. A spreader roll 138 is
shown
preceding the calendering nip 136, although other details of the calendering
unit 130
are not shown for purposes of clarity.
The calendering nip 136 may comprise a "soft-nip" wherein the rolls have
different surface hardnesses and at least one of the rolls has a resilient
surface.
Resilient calendering rolls suitable for the present invention are typically
referred to as
rubber covered catendering rolls, although the actual material may comprise
natural
rubber, synthetic nrbber, composites, or other compressible surfaces. Suitable
resilient
calendering rolls may have a Shore A surface hardness from about 75 to about
100
Durometer (approximately 0 to 55 Pusey & Jones), and particularly from about
85 to
about 95 Durometer (approximately 10 to 40 Pusey & Jones). For instance, the
17
CA 02526241 1998-04-14
calendering rolls may comprise a smooth heel roll 134 and a smooth resilient
roll 132
formed of a composite polymer such as that available from Stows Woodward
Company, U.S.A., under the tradename MULT1CHEM. The calendering nip pressure
is
suitably from about 30 to about 200 pounds per lineal inch, and more
particularly from
about T5 to about 175 pounds per lineal inch. Creped throughdried webs
desirably
have the sheet orientation for calendering and embossing as disdosed in
copending
U.S. Patent Application Serial No. 08/876,548, filed June 18, 1997 by R.
Jennings et al.
and titled 'Sheet Orientation For Soft-Nip Calendering And Embossing Of Creped
Throughdried Tissue Products."
Upon exiting the calendertng unit 130, the tissue web W is transported to an
embossing unit 140 comprising a pattern roll 142 and a backing roll 144. The
pattern
and backing rolls 142 and 144 together define therebetween an embossing nip
146. A
spreader roll 148 is shown preceding the embossing nip 146, although other
details of
the calendering unit 130 are not shown for purposes of clarity.
Embossing is a welt-known mechanism to increase sheet caliper, and it also
provides an additional benefit by imparting a decorative pattern to the tissue
product.
These decorative patterns may comprise "spot embossing" or "spot embossments"
which indude discrete embossing elements. Such elements may be about 0.5 inch
by
0.5 inch to about 1 inch by 1 inch in size, and thus from about 0.25 to about
1 square
inch in surface area. These discxete embossing elements are typically spaced
about
0.5 inch to about 1 inch apart. The spot embossing elements are formed on a
pattern
roll, which is also referred to as an embossing roll, and are pressed into the
tissue
sheet. The spaced-apart discxete spot embossing elements substantially
continuously
impact the web as it is processed through the embossing nip 148. The spot
embossing
elements can depict a decorative pattern such as flowers, leaves, birds,
animals, and
the like. As disclosed in copending U.S. Patent Application Serial No.
081876,547, filed
June 16, 1997 by Z. Salman et at. and titled "Calendered And Embossed Tissue
Products," high-bulk tissue products can be embossed with improved pattern
clarity by
processing the high bulk tissue webs sequentially through separate calendering
and
embossing units.
The backing roll 144 may comprise a smooth rubber covered roll, an engraved
roll such as a steel roll matched to the pattern roll, or the like. The
embossing nip may
be set to a pattemlbacking rob loading pressure from about 80 to about 150
pounds per
lineal inch, for example an average of about 135 pounds per lineal inch, such
that the
embossing pattern is imparted to the tissue web W. The backing roll can be any
18
CA 02526241 1998-04-14
material that meets the process requiremeMa such as natural rubber, synthetic
nrbber
or other compressible surtaxes, and may have a A surtace hardness fiom about
85 to about 85 Durometer, such as about 75 Durometer.
A new parent roil R' is shown in FiG. 18 being automatically threaded into the
finishing line. Rotation of the new parent roll is effected through the core
chucks 31 (not
shown), which are mounted on the amps 21 and thereby connected to the frame
20. As
illustrated, the leading end L, of the new web has already been transported by
the
thread-up conveyor 24 and deposited onto the trailing end portion T, of the
nearly
expired web W. The web W from the expiring roil Rx preferably passes over a
roller 22
and follows a downward path thereafter to the first finishing unit. The
leading end L, of
the new web may then be deposited onto the nearly expired web W at the
location of the
roller 22 or downstream of the roller 22 to facilitate travel of both webs to
the first
finishing unit. As described previously, the thread-up conveyor 24 is
desirably operated in
conjunction with rotation of the core chucks 31, and possibly rotation of the
roller 22 as
well. The roller 22 is desirably a driven roller with a high frictional cover,
formed for
example of fovp material as used in engaging hook-and-loop materials, or the
like.
Thus, the webs from both the expiring roll Rx and the new roll R' are
transported
to the firs: finishing unit, which in this case is the calendering unit 130.
The webs are not
bonded together prior to the calendering unit 730, and as a result they are
said to be
moveable relative to one another upstream of the calendering unit. The process
for
automatically splicing the webs together involves simultaneously unwinding
both webs
from their respective parent rolls and simultaneously passing both webs
through the
finishing unit nip 136 to bond the webs together. In the illustrated
embodiment, the parent
rolls Rx and R' are simultaneously driven by the cradle roller 28 and the core
chucks 31.
Thereafter, the web from the expiring roll Rx may be broken and the new web
may be
substantially continuously impacted by the calendering unit or the embossing
unit while
the web is urnnround.
The present method of splicing webs together from different parent rolls using
the
first finishing operation eliminates the need for separate bonding units and
eliminates the
need for external bonding means such as glue, tape, or the like. This method
also
replaces manual methods such as threading each new web or tying webs together.
In the illustrated embodiment, the first finishing operation is the
calendering unit,
which is used substantially continuously while the tissue webs are unwound.
The first
finishing operation after the unwind could alternatively be an embossing unit,
a crimping
unit, or other such device that impacts each individual tissue web while it is
being
19
CA 02526241 1998-04-14
unwound, and bonds the overlapping webs together during a web splice such that
the
webs are held together to the rewinder. The method dramatically reduced the
down time
assodatad with splicing ditier~ent parent roll webs together compared to prior
methods.
FIGS. 17 - 19
Other forms of torque transmitting means that do not contact the outer
circumferential surface of the parent roll are described in relation to FIGS.
17 - 18. In
FIGS. 17 and 18, the torque transfer means comprise side clamping mechanisms
that
engage only the opposite end surfaces of the parent roll and sandwich the roll
therebetween: Such side damping mechanisms may be used as the sole unwind
devices or as supplemental devices in combination with a center unwind drive
(not
shown). The torque transfer means 160 shown in FIGS. 17 and 18 are operable to
transmit torque from an unwind shaft 162 through a parent roll R. The torque
transfer
means 160 apply pressure against the end surfaces 163 of the roll R using an
inflatable
annular bladder 164 (FIG. 17) or alternatively a plurality of inflatable
annular bladders
166 (FIG. 18). The roll core C is positioned over the end of the shaft 16Z and
against a
ring 167.
The inflatable bladders 164 and 166 are attached to a backing plate 168 that
is
fixedly attached to the unwind shaft 162. The bladders may be inflated and
deflated by
the movement of a fluid though suitable conduits (not shown) into bladder
cavities 170.
As a result, the inflatable bladders are capable of applying pressure to the
end surfaces
of the parent roll, and are capable of deflating or retracting as the parent
roll unwinds. in
regard to F1G. 18, the annular bladders 166 may be deflated or disengaged in
series
moving radially inward as the parent roll is unwound to smaller diameters so
as not to
interfere with the sheet as it is peeled away from the roll. The interior
bladders 166 may
be left inflated to continue transmitting torque through the rot! at smaller
roll diameters.
The bladder contact pressures against the ends of the parent roll will depend
on the
configuration of the torque transfer means 160, but are suitably less than
about
2.5 pounds per square inch (psi), particularly about 0.5 to about 2.5 psi, and
more
particularly less than about 1 psi, to minimize damage to the tissue web.
In FIG. 17, an optional friction plate 172 is attached to the inflatable
bladder 164
to engage the end surfaces 163 of the roll R upon inflation of the bladder
164. The
friction plate 172 may be formed of any material that best grips the roll
using minimal
pressure and causes minimal damage to the edges of the sheet, although the end
surfaces of the roll are not normally used to make finished tissue products.
CA 02526241 1998-04-14
The size of the backing plate 188 will depend on the size of the parent rolls,
but
may be at least about 45 inches, such as about 45 to about 80 inches outside
diameter,
so as to De located where the highest forces are present. The portion of the
torque
transfer means 180 that contacts the end of the roll will have specified inner
and outer
diameters which minimize pressure on the roll, maximize contact area, or
optimize the
relationship between the contact area, engagement pressure, and friction
characteristics
of the torque transfer means.
The unwind system partially illustrated in FIG. 19 combines core chucks 31
that
engage the inner surface 175 of the core C and supplemental torque transfer
means 160
that engage the end surfaces 163 of the parent roll R. The unwind system
includes
opposed chuck shaft assemblies 176 (only one shown), which each comprise an
unwind
shaft 162 rotatabiy mounted within a hub 178 and drivingly connected to a
variable
speed drive (not shown). Each chucfc shaft assembly 176 also comprises a core
chuck
31 and a supplemental drive chuck 180, both of which are mounted on the shaft
162 to
rotate therewith. The core chucks 31 inGude inflatable core chuck bladders 182
that are
adapted to frictionally engage the inner core surface 175 when the chuck shaft
assembly
176 is inserted into the core C. The supplemental drive chuck 180 includes
inflatable
coupling bladders 184, the operation of which is described hereinafter.
Conduits (not
shown) within the chuck shaft assembly 176 operably connect the cavities of
the core
chuck bladders 182 and coupling bladders 184 to a fluid source (not shown) for
inflating
and deflating the bladders.
The supplemental torque transfer means 160 inGudes an annular backing
plate 168. A plurality of concentric, inflatable annular bladders 166 are
attached to the
backing plate and adapted to engage the end surfaces 163 of a parent roll R,
shown in
Gose proximity to the chuck shaft assembly 176 for purposes of illustration.
The backing
plate 168 includes an integral, axially extending collar 186 that is
releasably attached by
spring balls and detents or other suitable means (nvt shown) to a portion of
the fixed
frame 188. Conduits (not shown) within the backing plate 168 and chuck shaft
assembly 176 and connected by a rotary joint operatively connect the cavities
of the
annual bladders 166 to a fluid source (not shown).
Once the core chucks 31 are aligned for insertion into a core C, the chuck
shaft
assemblies 176 are axially advanced toward one another into the roN R. Axial
movement
is ternporariiy halted when the supplemental drive chucks 180 are radialiy
inward of the
backing plate collars 186, at which point flanges 190 of the supplemental
drive chucks
1$0 may contact the collars. The coupling bladders 184 are then inflated to
frictionally
21
CA 02526241 1998-04-14
enflage the backing plate collars 188. The chuck shaft assemblies 178 then
resume their
axial advance until the core chucks 31 are within the core C and flanges 192
of the core
chucks abut the core. Both the bladders 182 within the core chucks 31 and the
annular
bladders 184 on the backing plates 168 are then inflated to engage the inner
surface 175
of the core and the end surfaces 183 of the parent roll. Alternatively, the
supplemental
torque transfer means 180 and chuck shaft assembly 178 could be fixedly
connected
(not shown).
The supplemental torque transfer means 160 described in relation to FIGS.
16 - 19 are particularly beneficial for use with loosely-wound parent rolls
having an
outside diameter of about 120 inches or greater, for example about 140 inches
or
greater. The supplemental torque transfer means reduces or eliminates slippage
between individual sheet layers and between sheet layers and the inner roll
core,
particularly during high acceleration or deceleration periods. The desired
level of torque
can be transferred from the unwind shaft through the roll itself by selection
of the
coefficient of friction of the side clamping mechanism, the contact area of
the side
Damping mechanism, and the air pressure of the bladders.
While in the foregoing specification, a detailed description of various
embodiments of the invention have been set down for the purpose of
illustration, many
variations in the details hereingiven may be made by those skilled in the art
without
departing from the spirit and scope of the invention.
22
