Note: Descriptions are shown in the official language in which they were submitted.
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WEB CALIPER MEASUREMENT AND CONTROL SYSTEM
BACKGROUND OF THE DISCLOSURE
In the manufacturing and conversion of web materials, particularly fibrous web
materials, and
more specifically tissue web materials, the properties of the web are
monitored by means of on-line
measurements. The measurements are conducted in the cross-machine direction
(CD) of the web in
order to produce a CD profile of the measured property. Typically the
measurements are performed by
means of measuring apparatuses in which the moving web is measured by means of
a measuring
sensor moving back and forth in the CD. The properties to be measured may
include, for example,
moisture, caliper, basis weight, ash content, color, opacity, brightness,
gloss, or smoothness of the
web.
The results obtained from the measuring sensors are used not only for
monitoring the
properties of the web, but also for controlling the manufacturing and
converting processes. For
example, the measurement results may be transmitted to a control unit where
they are utilized to
determine control signals for profiling apparatuses belonging to either the
manufacturing or converting
process. Based upon the control signal the manufacturing or converting process
may be adjusted to
alter the CD properties of the web.
To-date however, it has not been possible to quickly and accurately measure
the CD caliper of
a web in real time so as to use the measurement to accurately and effectively
control the
manufacturing and converting processes. For example, methods that rely upon
moving a sensor
across the web in the CD are not sufficiently fast to enable accurate and
reliable control. Similarly,
sensors that sense only a small portion of the web do not provide sufficient
data regarding the CD web
profile upon which to base process control. Thus, there remains a need in the
art for a method of
quickly and accurately measuring web caliper across at least a portion of the
cross-machine direction
of the web and controlling one or more manufacturing or converting operations
based upon the
measured web caliper.
Moreover, there remains a need in the art for a method of coordinating caliper
control by
calendering and finished roll winding that provides for well wound finished
product rolls and is capable
of preserving desired physical properties of the web substrate throughout the
entirety of the winding
process.
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SUMMARY OF THE DISCLOSURE
The present inventors have now discovered a means of accurately and quickly
measuring web
caliper in real time during the converting process, which measurement may be
used to control one or
more manufacturing or converting unit operations. For example, in one
embodiment the present
invention provides a method of using a winding apparatus to wind tissue web
onto a core to form a
rolled tissue product, comprising the steps of providing a first winding
algorithm; winding the tissue
web about the core in accordance with the first winding algorithm; measuring
the caliper of the web
across at least a portion of the cross-machine direction of the web, such as
across at least a 2.0 cm
portion of the web and more preferably at least a 3.0 cm portion of the web;
comparing the measured
caliper to a target caliper value; providing a second winding algorithm based
upon the comparison of
the measured caliper to the target caliper; and adjusting at least one winding
parameter in accordance
with the second winding algorithm.
In other embodiments the present invention provides a web winding and
measuring system,
comprising a calender system; a rotatably-mounted spool onto which a web of
material is wound to
form a roll; a draw roll over which a web of material is conveyed prior to
being wound to form a roll; a
light-emitting device configured to illuminate the web as it is conveyed over
the draw roll, providing a
line on the upper surface of the web in a cross-machine direction; a light-
receiving device configured to
detect the line; a means for generating measurement data from the detected
line; a computing device
communicatively coupled to the light-receiving device and configured to
receive the measurement data
and calculate web caliper; a comparison means for comparing the calculated web
caliper to a target
web caliper value and determining whether the target web caliper has been
achieved, upon
determining that the at least one target characteristic has not been achieved,
determine an adjustment
to at least one parameter to achieve the target characteristic; and adjust the
at least one parameter
based on the determined adjustment.
In still other embodiments the present invention provides a web winding and
measuring
system, comprising a web tensioning system; a rotatably-mounted spool onto
which a web of material
is wound to form a roll; a draw roll over which a web of material is conveyed
prior to being wound to
form a roll; a light-emitting device configured to illuminate the web as it is
conveyed over the draw roll,
providing a line on the upper surface of the web in a cross-machine direction;
a light-receiving device
configured to detect the line; a means for generating measurement data from
the detected line; a
computing device communicatively coupled to the light-receiving device and
configured to receive the
measurement data and calculate web caliper; a comparison means for comparing
the calculated web
caliper to a target web caliper value and determining whether the target web
caliper has been
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achieved, upon determining that the at least one target characteristic has not
been achieved,
determine an adjustment to at least one parameter to achieve the target
characteristic; and adjust the
at least one parameter based on the determined adjustment.
These and other embodiments of the present invention will now be described
further in the
following detailed description taken in connection with the accompanying
drawings.
BRIEF DESCRIPTION OF DRAWINGS
FIG. 1 is a schematic diagram of one embodiment of a caliper measurement and
web handling
system for winding a roll of web material;
FIG. 2 is a block chart of a control method for controlling the caliper of a
web;
FIG. 3 illustrates a caliper measuring device useful in the present invention;
and
FIG. 4 is a schematic diagram of another embodiment of a caliper measurement
and web
handling system for winding roll of web material.
Repeat use of reference characters in the present specification and drawings
is intended to
represent the same or analogous features or elements of the disclosure.
DETAILED DESCRIPTION OF THE DISLOSURE
The present invention solves the problem of accurately measuring the thickness
of a moving
web, and in certain embodiments a non-planar web being conveyed over a
conveying surface, and
making adjustments to the web converting machinery based upon the measured web
caliper.
Generally the web caliper is measured without contacting the web and in real
time while the web is
being conveyed at high rates of speed. At the same time the method provides
for caliper measurement
across at least a portion of the web in the cross-machine direction, which
further improves the
accuracy of the caliper measurement and is a significant improvement over
single point
measurements. Additionally, by measuring across at least a portion of the
cross-machine direction and
by taking a continuous measurement, a three dimensional image of the web
surface may be
generated. The three-dimensional image not only provides for a highly accurate
caliper measurement,
but provides the additional benefit of enabling the detection of flaws in the
web.
Further, the accurate and continuous measurement of web caliper may be used to
improve the
manufacture and processing of the web. For example, winding of the web may be
improved by
enabling compressive strain to be accurately determined and continuously
monitored during winding.
Compressive strain is determined from the difference between the actual
thickness of the layers of
material on the roll and the theoretical thickness of layers of material wound
with no compressive
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strain. The actual thickness of the layers of material on the roll is obtained
by accurately measuring the
length of material in each layer on the roll and hence the diameter of each
layer. The thickness of a
band comprising a number of layers can be calculated from the difference of
the diameters of its inner
and outer layers. By continuously measuring the thickness of the material
before it is wound onto the
roll, variations in the thickness of the material can be taken into account in
determining the
compressive strain, increasing the accuracy of the measurement. This results
in improved roll structure
control and fewer rejected rolls.
Accurate web caliper measurement may also enable more accurate web tension
control. For
example, the measured caliper may be used to calculate sheet density, which
may be in-turn used to
adjust the metered winding algorithm. Adjustments to the winding algorithm may
control the rotational
speed of the mandrel in order to maintain the web of material under constant
tension.
Measurement of web caliper may also be used to control the tension of the web
as it is fed to
the log winding device. For example, the web may be trained around a driven
draw roll and then
passed through a dancer assembly. From there, it may be trained under a guide
roll and drawn into the
log winding device. In response to tension changes in the web, the dancer
assembly moves from its
reference position to lengthen or shorten the web path as necessary to
maintain uniform tension in the
web. The dancer motion may be controlled by applying a drive torque or a
holdback torque to the draw
roll depending on detected web caliper. That, in turn, decreases or increases
the tension in the web
entering the dancer assembly as needed to return the dancer assembly to its
reference position.
Additionally, the accurate and continuous measurement of web caliper may be
used to adjust
web caliper prior to winding the web into a rolled product, such as by
adjusting calendering of the web.
Thus, in certain embodiments, to properly control the structure of the
finished roll product the caliper of
the web may be measured prior to winding, and more preferably immediately
prior to winding, to
generate a first caliper measurement value. The first caliper measurement
value may be compared to
a desired caliper measurement value to yield a determined caliper
differential, which may be in-turn be
used to adjust the calendering system load profile.
Turning now to FIG. 1, one embodiment of a system 100 useful for winding a web
40 of
material is illustrated. In the illustrated embodiment the web 40 is a tissue
web, such as paper towels,
toilet paper, or facial tissue, which is wound into a roll 90. In the
illustrated embodiment a tissue web
40 is unwound from a parent roll (not illustrated) and passed through a
caliper control device 12. The
caliper control device 12 may be, for example, a calendering system comprising
a top roller 14 spaced
from a bottom roller 16. The rollers 14 and 16 form a nip 18 through which the
web 40 is fed. By
applying pressure to the web, the thickness or caliper of the web may be
reduced.
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When using a calendering device, the calendering device may be a gap
calendering device or
a contact calendering device. Further, the rollers 14 and 16 may be steel
rollers, rubber-coated rollers,
or mixtures thereof. In addition to a calendering device, any suitable caliper
control device may be
used in accordance with the present invention. For example, in an alternative
embodiment, an
embossing device may be used in order to control the caliper of the web. In
still other embodiments the
caliper may be controlled by adjusting tension in the web as the web is
unwound from the parent roll.
Tension control devices are well known in the art and may include, for
example, a dancer roll.
With further reference to FIG. 1, the relative position of the rollers 14, 16
that make up the
calender unit may be controlled by one or more hydraulic actuators 15, 17.
Useful hydraulic actuators
are known in the art and may comprise a hydraulic cylinder 22 and a moveable
arm 23. The oil
pressure prevailing in the actuator 21 can be adjusted by means of a hydraulic
pressure control unit
26, which may be a programmable logic controller (PLC), thus attaining the
desired linear pressure
profile in the calender nip 18.
In their operational positions the first 14 and second 16 opposed calender
rollers are held by
two hydraulic actuators 15, 17, which act on the mounting faces of the
rollers. With the aid of stops
against which the piston of the lower hydraulic actuator works the bottom
roller 14 is held in a pre-
determined position. The position of the second roller 16 is adjusted by
lowering or raising with the aid
of the upper hydraulic actuator 17.
The weight of the rollers 14 and 16, because of their vertically shiftable
mounting, produces a
minimal pressure on the roller nip 18. This pressure can be increased with the
aid of a loading device,
which in one embodiment acts on the top roller with a downward force and, in
an exemplary
embodiment, consists of a hydraulic actuator 17 capable of inserting small
increases of downward
force on the two mounting faces of the top roller 14. While this is an
exemplary embodiment of a
calendering operation the specific structure of the calendering stack is not
critical to the functioning of
the invention.
Once the web 40 leaves the calender nip 18 it is passed over a series of draw
rolls 30, 32, 34,
36 and finally to a log winding device (one embodiment illustrated further in
FIG. 4) to be wound into a
roll 90. In general, any suitable log winding device may be used in accordance
with the present
invention. For instance, the winding device may be a surface winding device, a
center winding device,
a coreless winding device, or the like.
The system further comprises a first computing device 102 communicatively
coupled to a
hydraulic pressure control unit 26, which is in-turn communicatively coupled
to a hydraulic actuator 21.
The hydraulic actuator 21 comprises a moveable arm 23 which is in
communication with a calender roll
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16 to move the roll from a first to a second position. Additionally the system
100 comprises a caliper
meter 50 communicatively coupled to the interface board 124. The interface
board 124 may be
communicatively coupled to a router or switch 126, which is in communication
with the first computing
device 102 and the PLC 26. In some implementations, a second computing device
is communicatively
coupled to the PLC.
In the illustrated embodiment, the first computing device 102 generates
instructions for
configuring the PLC 26 to control the actuator 21. More specifically, the
first computing device 102
generates instructions based on predetermined parameters for controlling
winding of a web 40 into
a roll 90. The parameters incorporate assumptions regarding, for example, the
density and
compressibility of the finished roll 90, a target number of sheets in the
finished roll 90, and a target
diameter of the finished roll 90. The first computing device 102 configures
the PLC 26 to operate in
accordance with the parameters. More specifically, the PLC 26 transmits
instructions to the actuator 21
to operate the calender system 12 according to caliper loading algorithm 24
based on the parameters.
The caliper loading algorithm 24 dictates the relative position of the first
14 and second 16 calender
rolls, which in-turn affects the calender nip pressure, based on the
parameters.
The caliper meter 50 repeatedly emits light 52 towards the upper surface 42 of
the web 40 and
samples the light to generate measurement data. The caliper meter 50 transmits
the measurement
data to the interface board 124. The interface board 124 may further be
configured to receive
additional information regarding the web, the roll and the winding device,
such as the relative position
of the winding device mandrel, the web tension and speed of the winding
device. The interface board
124 transmits the measurement data to the first computing device 102.
The first computing device 102 receives the measurement data from the
interface board 124
and calculates the web caliper (MO. As the web 40 is continuously wound into
rolls 90 the caliper
meter 50 repeatedly generates measurement data and transmits the measurement
data to the first
computing device 102 through the interface board 124. Accordingly, the first
computing device 102
continuously collects measurement data and repeatedly calculates the caliper
of the web as the roll 90
grows. In some embodiments, the first computing device 102 generates, in
memory, a three
dimensional profile of the web of material based on the collected measurement
data. In other suitable
implementations, the first computing device 102 determines at least one target
characteristic of the roll
90 to be achieved by the web winding and measuring system 100 and analyzes the
measurement data
to determine whether the at least one target characteristic has been achieved.
The at least one target
characteristic may include, for example, a target number of sheets of the roll
90, a target diameter for
the roll 90, and/or a target ratio of a number of sheets of the roll 90 to a
diameter of the roll 90.
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In some embodiments the first computing device 102, upon determining that the
at least one
target characteristic has not been achieved, determines an adjustment to at
least one parameter to
achieve the target characteristic. The first computing device 102 then
transmits the at least one
adjusted parameter to the first computing device to the PLC 26 to cause the
PLC 26 to be configured
based on the at least one adjusted parameter. In some implementations the
first computing device 102
determines, for example, an adjustment to the calender nip pressure by the
actuator 21.
Additionally, in some embodiments, and as described in more detail herein, the
first computing
device 102 generates a mathematical model of how the starting parameters and
operating parameters
affect the resulting characteristics of a roll. The first computing device 102
generates the mathematical
model by applying one or more statistical techniques, such as linear or
polynomial regression, and/or
principal component analysis to the collected data to determine how parameters
affect the resulting
characteristics of a roll and which parameters have the most influence in
affecting the resulting
characteristics of the roll.
Accordingly, upon entering a set of parameters into the first computing
device, an operator of
the web winding and measuring system may execute a simulation of forming a
roll, based on the
parameters, prior to actually forming the roll on the web winding and
measuring system. In other
instances, an operator may enter a set of target characteristics and starting
parameters into the first
computing device and the first computing device provides the operator with a
set of operating
parameters required to achieve the target characteristics, based on the
mathematical model. To
control the caliper of the web, the first computing device may be configured
with a comparison means
that compare the measured caliper values to the target caliper values. On the
basis of the comparison,
the comparison means forms an error profile that may be used to determine a
corrected error profile.
The corrected error profile may be transmitted to the PLC for controlling the
calender nip load. For
example, using the corrected error profile a new control signal may be
transmitted to one or more
actuators to adjust the calender nip pressure.
One method for determining corrected error profiles and new control commands
is illustrated
in block charts in FIG. 2. The first computing device 102 may comprise a
comparison means to which
the measurement results (Mc) are input. The target web caliper (Tc) values are
also input in the
comparison means. The comparison means compares the measured values of the
process with the
target web caliper values and forms an error profile Po on the basis of the
comparison, which profile is
sent to the PLC 26. The PLC 26 comprises control algorithms forming control
signals (C) on the basis
of the error profile PD, which control signals are sent to one or several
actuators affecting the relative
position of the calender roils and in-turn the caiender nip profile and bad.
In certain embodiments the
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calender unit may comprise a plurality of actuators arranged across the width
of the web so that they
each have a separate area of influence in the cross-machine direction of the
web. The control signals
C cause the necessary change in the operation of the actuator, thus affecting
the caliper of the web
across the entire cross-machine direction. The control unit updates the error
profile PD for example
constantly in accordance with a given measurement cycle, time or control
interval, producing the
control commands C typically on the basis of the last error profile. The error
profile P0 can be
calculated for example at intervals of two measurement scans across the width
of the web. The
function of the control unit and the means relating thereto are known as such
by a person skilled in the
art, and therefore they will not be described in more detail in this context.
As was stated above, the control unit comprises means for controlling the
manufacturing or
finishing process of a web. In addition to the above-mentioned means the
control unit may also
comprise other means. The steps of the above-described control method can be
performed by a
program, for example a microprocessor. The means may be composed of one or
more
microprocessors and the application software contained therein. The means may
also comprise means
for transmission of information and signals between the means. In this
example, there are several
means carrying out the steps, but the different steps of the method can also
be performed in a single
means. The means for determining the corrected error profile can be arranged
as an independent part
of the control unit, or they can be integrated as a part of the control means.
The means for determining
the corrected error profile can also be arranged as a separate program unit
outside the control unit.
Thus, the control unit and the means for determining the corrected error
profile have been provided
with means for transmitting information between them.
The measurement results measured by the measuring devices can be transmitted
to the
control unit via conductors or wirelessly. If the measurements are transmitted
to the control unit
wirelessly, the measuring means are provided with a transmitter for
transmitting measurement results,
and the control unit is provided with a receiver for receiving measurement
results. The control
commands produced by the control unit can also be conveyed to the control unit
either via conductors
or wirelessly. If the control commands are transmitted to the actuators
wirelessly, the control unit is
provided with a transmitter for transmitting control commands and the actuator
is provided with a
receiver for receiving control commands.
Turning now to FIG. 3, a caliper measurement device 50 useful in obtaining
caliper
measurement data is illustrated in greater detail. In the illustrated
embodiment the caliper
measurement device 50 comprises radiation source 51 positioned so as to
illuminate the upper surface
42 of the web and in certain embodiments the surface 38 of the draw roll 36.
In certain embodiments
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the caliper measurement device 50 may comprise a multi-point triangulation-
based sensor which is
well known in the art. For example, US Patent No. 4,937,445, the contents of
which are incorporated
herein by reference in a manner consistent with the present application,
discloses a sensor head
capable of measuring the dimensions of a workpiece by illuminating the
workpiece with a plurality of
light sources and then aligning a series of spots reflected from a workpiece
using a camera that lies in
the same plane as both the spots and the light sources.
In the illustrated embodiment the caliper measurement device 50 comprises a
radiation
source 51 which generates a line 45 generally oriented in the cross-machine
direction (CD), which is
generally perpendicular to the machine direction (MD). The caliper measurement
device 50 further
comprises a detector 46 configured to detect radiation reflected from the
surfaces of the upper surface
42 of the web 40 or the surface 38 of the draw roll 36. The radiation source
51 and detector 46 are
generally illustrated as being contained within a single apparatus, i.e,,
caliper measurement device 50,
however, in certain embodiments the devices may be housed separately.
The radiation source may be any structure for generating an illumination line;
such as a laser
or narrow-band light emitting diode (LED) and optics for focus and fine line
generation. The radiation
source could generate radiation with substantially identical visible or other
wavelengths, although
different wavelengths can be used. For instance, near-infrared (NIR)
wavelengths could be used. The
radiation source may produce radiation continuously or in a pulsed fashion,
meaning the illumination
line 45 could be generated intermittently or continuously. In the illustrated
embodiment the radiation
source projects a reference laser plane towards the upper web 42 and forms a
line 45 in the cross-
machine direction on the surface 42 of the web 40. While the line is
illustrated as being projected
normal to the nominal web surface other angles maybe used so long as the line
illuminates a portion of
both the web surface and the conveyor surface. In certain embodiments the line
measures at least
about 1.0 cm, still more preferably at least about 2,0 cm and still more
preferably at least about 3.0 cm,
such as from about 3,0 to about 10.0 cm,
The detector 46 detects the illuminated line 45. The detector 46 may be any
suitable structure
for capturing information about lines projected onto a sheet. In one
embodiment the detector 46
comprises a lens 47 and a detector array 48. In addition to providing a
focused image, the lens 47 may
include filters to exclude unwanted wavelengths of light from acquired images.
The detector array 48
may be photo-detector arrays of either linear or matrix types, or Position
sensing photodiodes (PSDs)
which provide image position data as a voltage. Where photo-detector arrays
are used, processing to
determine zone image position can use thresholded centroids and multiple
centroids or first moment
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calculations. Suitable detector arrays include, for example, a charge-coupled
device (CCD), a
complementary metal oxide semiconductor (CMOS) device, or a charge injection
device (CID).
In the illustrated embodiment a single light source 51 projects a line of
light 45 such that light
is reflected from the upper surface 42 of the web 40 in nominal alignment
along a reflection axis. The
reflected light is assessed for displacement from a nominal position (for
example height of the surface
from which the light is reflected, i.e. vertical displacement). A measurement
plane is defined to include
the reflection axis and the possible displaced locations of the reflections.
The reflected light passes
through the lens 47 and is detected by the detector array 48.
The analysis of the images captured by the detector could be performed by any
suitable
device or system. In some embodiments, the detector is included within a
'smart" camera, where some
or all operations in the analysis of an image and the calculation of a
triangulated distance to a point are
done by the camera itself. In other embodiments, the detector provides images
or other information to
an external device or system that processes the images and calculates the
triangulated distances. For
example, as illustrated in FIGS. 1 and 4 the caliper measurement device 50
provides data to an
interface board 124, which in-turn transfers data to a computer 102 for
calculation of distances based
upon triangulation, analysis of the distance data and ultimately calculation
of web caliper (C).
In one embodiment the distance between the surface 38 of the draw roll 36 and
the caliper
measuring device 50 is first determined by illuminating the surface 38 with a
line of light 45 prior to the
web 40 being conveyed over the surface 38 of the draw roll 36. The caliper
measuring device 50 is
located a distance H above the surface 38 and a horizontal distance x from
radiation source 51.
Detector 48 detects the line 45. A computerized Image processing unit 102
computes the height (H1)
from the caliper measuring device 50 to the surface 38 by applying the
formula:
h = H ¨ -
tan 0
where 0 is the angle at which detector 48 views line 45. A second measurement
(H2) is taken once the
web 40 is being conveyed along the surface 38 of the draw roll 36. With the
addition of the web 40 to
the draw roll surface 38 the height increases causing 0 to increase. Further
as the height of the web
relative to the surface of the draw roll increases and decreases the value of
0 increases and
decreases.
The actual position of line 45 and the vertical distance of line 45 above the
surface 38 of the
draw roll 36 can be determined by triangulation. It is a straightforward image
processing task to
determine the angle (1) and the height (H2) from the images captured by the
camera. Once H2 is
determined, caliper (C) of the web 40 is calculated by simply subtracting H1
from H2. Although the
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camera cannot see the bottom surface of the web (surface opposite the upper
surface 42), it is
assumed that the lower surface lies substantially in-plane with the known
plane of the conveyor
surface 16.
In other embodiments the height of the draw roll surface (H1) and the height
of the web (H2)
are measured concurrently by illuminating the upper surface of the web and the
draw roll surface
concurrently as the web is conveyed across the surface. In this embodiment the
upper web 40 surface
42 and the draw roll surface 38 are illuminated using a radiation source 51 to
form a line 45 disposed
substantially in the cross-machine direction of the web 40 normal to the
machine direction and the
direction of travel of the web. Thus, the line 45 extends beyond the edge 44
of the web 40 and onto the
surface 38 of the draw roll 36. To determine the location of the edge 44 a
matrix array is used to sense
the line 45. A contour of the web surface 42 is produced by the light section
principle, and the location
of the edge 44 can be determined by the location of rapid contour fall of the
image. For example, by
sequentially scanning lines of the array of the first location at which the
line location is for example,
100 pixels less than the previous, can be chosen as the edge 44 of the web 40.
The caliper C of the
web 40 may then be calculated by simply subtracting H1 from H2.
FIG. 4 illustrates an alternate embodiment of a web winding system 100. The
system 100
includes a first computing device 102 communicatively coupled to a PLC 204
which controls a log
winding apparatus. The PLC 204 is communicatively coupled to a servo drive
206. The servo drive 206
is communicatively coupled to a servo motor 208 and an encoder 210. The servo
motor 208 is coupled
to a motor pulley. The motor pulley is operatively coupled to a spool pulley
through a drive belt. The
spool pulley is coupled to a spool. That is, the spool is rotatably mounted to
the spool pulley.
Additionally, an encoder 220 is operatively coupled to the spool. The encoder
220 is communicatively
coupled to an interface board 124. Other devices for monitoring and measuring
winding may be
coupled to the spool such as a tension sensor 221 or a humidity sensor 222.
In addition to the encoder 220 a caliper measurement device 50 is
communicatively coupled to
the interface board 124. The caliper measurement device 50 preferably
continuously measures at least
a portion of the web caliper in the cross-machine direction as the web is
being conveyed over the
surface 38 of the draw roll 36 before it is wound into a roll on the mandrel
138. Preferably the CD
portion of the web measured by the caliper measurement device is at least
about 1.0 cm, still more
preferably at least about 2.0 cm and still more preferably at least about 3.0
cm, such as from about 3.0
to about 10.0 cm. The interface board 124 is communicatively coupled to a
first computing device 102.
The first computing device 102 may also be communicatively coupled to a second
PLC 26 for
controlling a calender unit. Based upon measurement data received from the
caliper measurement
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device 50 the first computing device 102 may generate signals to control the
calender device as
described above. In this manner measurement data from the caliper measurement
device 50 may be
transmitted to the first computing device 102 and used to adjust the web
caliper by making
adjustments to the calender system load profile. The adjusted web caliper may
then be measured and
fed forward to adjust the metered winding algorithm used to control the
winding apparatus and/or one
or more components of the winding apparatus.
In the illustrated embodiment, the first computing device 102 generates
instructions for
configuring the PLC 204 to control the servo drive 206. More specifically, the
first computing device
102 generates instructions based on predetermined parameters for controlling
winding of a web of
material into a roll. The parameters incorporate assumptions regarding, for
example, the density and
compressibility of the finished roll, a target number of sheets in the
finished roll, and a target diameter
of the finished roll. The first computing device 102 configures the PLC 204 to
operate in accordance
with the parameters. More specifically, the PLC 204 transmits instructions to
the servo drive 206, to
operate the servo motor 208 according to an electronic cam profile based on
the parameters. The
electronic cam profile dictates positions and velocities for the servo motor
208, based on the
parameters. The servo drive 206 transmits power and instructions to the servo
motor 208 in
accordance with the electronic cam profile and receives feedback regarding the
position and/or
velocity of the servo motor 208 from the encoder 210.
The servo motor 208 rotates the motor pulley which is coupled to the spool
pulley by the drive
belt. As the spool pulley rotates the spool the encoder 220 generates position
and velocity data about
the spool and transmits the data to the interface board 124. A tension sensor
221 measures tension
exerted by the spool on a web of material being wound by the spool and
transmits tension data to the
interface board 124. The caliper measuring device 50 repeatedly emits light 52
towards the web (not
illustrated) traveling over the draw roll 36 and samples the light to generate
caliper data, as described
in more detail above. The caliper measuring device 50 transmits the
measurement data to the
interface board 124.
The first computing device 102 receives the measurement data from the
interface board 124
and calculates the caliper of the web. As the web continuously passes over the
draw roll 36 and is
wound into a web on a core supported by the mandrel 138, the caliper measuring
device 50 repeatedly
generates measurement data and transmits the measurement data to the first
computing device102
through the interface board 124. Accordingly, the first computing device 102
continuously collects
measurement data and repeatedly calculates the caliper of the web as the roll
grows.
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Thus the controller may be configured to receive the calculated caliper of the
web immediately
prior to its being wound into a roll and, based on this information, to then
control the metered winding
algorithm should the caliper of the web be outside preset limits.
Specifically, the controller can be
configured to make adjustments in the amount of tension that is placed upon
the web of material
during winding. Through the system, the diameter of the rolls of material
produced and/or the firmness
of the rolls of material produced may be controlled within preset limits such
that every roll produced
has substantially uniform and desirable characteristics.
When introducing elements of the present disclosure or the preferred
embodiment(s) thereof,
the articles "a", "an", "the" and "said" are intended to mean that there are
one or more of the elements.
The terms "comprising", "including" and "having" are intended to be inclusive
and mean that there may
be additional elements other than the listed elements. Many modifications and
variations of the present
disclosure can be made without departing from the spirit and scope thereof.
Therefore, the exemplary
embodiments described above should not be used to limit the scope of the
invention.
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