U.S. patent application number 15/524062 was filed with the patent office on 2017-11-16 for web caliper measurement and control system.
The applicant listed for this patent is Kimberly-Clark Worldwide, Inc.. Invention is credited to Gregory Michael Bixler, Vivek Moreshwar Karandikar, Daniel James Wilczynski.
Application Number | 20170327337 15/524062 |
Document ID | / |
Family ID | 56284796 |
Filed Date | 2017-11-16 |
United States Patent
Application |
20170327337 |
Kind Code |
A1 |
Bixler; Gregory Michael ; et
al. |
November 16, 2017 |
WEB CALIPER MEASUREMENT AND CONTROL SYSTEM
Abstract
The present disclosure relates to systems and methods for 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. The web caliper measuring system may be
employed in the web converting system to improve web caliper
control and improve winding. The web caliper measurement may be fed
back to a calendering system to improve the caliper of web fed into
a winding system, or the caliper may be fed forward to the web
winding system to improve web tension and winding performance.
Inventors: |
Bixler; Gregory Michael;
(Appleton, WI) ; Karandikar; Vivek Moreshwar;
(Neenah, WI) ; Wilczynski; Daniel James; (Irvine,
CA) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Kimberly-Clark Worldwide, Inc. |
Neenah |
WI |
US |
|
|
Family ID: |
56284796 |
Appl. No.: |
15/524062 |
Filed: |
December 30, 2014 |
PCT Filed: |
December 30, 2014 |
PCT NO: |
PCT/US14/72755 |
371 Date: |
May 3, 2017 |
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
B65H 2511/13 20130101;
B65H 18/28 20130101; B65H 26/08 20130101; D21G 9/0045 20130101;
B65H 26/04 20130101; B65H 2701/1924 20130101; B65H 2511/13
20130101; B65H 2553/41 20130101; B65H 2220/03 20130101 |
International
Class: |
B65H 26/08 20060101
B65H026/08; B65H 26/04 20060101 B65H026/04 |
Claims
1. A method of using a winding apparatus to wind a tissue web onto
a core to form a rolled tissue product comprising the steps of: a.
providing a first winding algorithm; b. winding the tissue web
about the core in accordance with the first winding algorithm; c.
measuring the caliper of the tissue web across at least a portion
of the cross-machine direction of the web; d. comparing the
measured caliper to a target caliper value; e. providing a second
winding algorithm based upon the comparison of the measured caliper
to the target caliper; and f. adjusting at least one winding
parameter in accordance with the second winding algorithm.
2. The method of claim 1 wherein the steps of winding the tissue
web and measuring the caliper are performed concurrently and
continuously during the formation of the rolled tissue product and
wherein the caliper is measured across at least a 2.0 cm portion of
the web.
3. The method of claim 1 wherein the at least one winding parameter
is either the tension exerted on the web or the rotational speed of
the core.
4. The method of claim 1 further comprising the step of conveying
the web over the surface of a draw roll prior to winding the tissue
web about a core and wherein the caliper is measured using a
caliper measurement device disposed above the surface of the draw
roll and the device comprises a light source and a detector and
wherein the caliper is measured across at least a 2.0 cm portion of
the web.
5. The method of claim 4 wherein the step of measuring the caliper
further comprises transmitting measurement data from the caliper
measuring device to a computing device in communication therewith
and calculating the web caliper based upon triangulation.
6. The method of claim 1 further comprising the steps of providing
a calender load profile and adjusting the calender load profile
based upon the comparison of the measured caliper to the target
caliper.
7. The method of claim 6 wherein the calender load profile adjusts
the displacement of a first roll in a calender system relative to a
second roll in the calender system.
8. A web winding and measuring system comprising: a. a calender
system; b. a rotatably-mounted spool onto which a web of material
is wound to form a roll; c. a draw roll over which a web of
material is conveyed prior to being wound to form a roll; d. a
light-emitting device configured to illuminate the web as it is
conveyed over the draw roll, providing a line measuring at least
2.0 cm on the upper surface of the web in a cross-machine
direction; e. a light-receiving device configured to detect the
line; f. a means for generating measurement data from the detected
line; g. a computing device communicatively coupled to the
light-receiving device and configured to receive the measurement
data and calculate web caliper; and h. 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.
9. The web winding and measuring system of claim 8, wherein the
determined adjustment comprises an adjustment to an amount of
tension exerted on the web.
10. The web winding and measuring system of claim 8, wherein the at
least one target characteristic comprises a target number of sheets
of the roll.
11. The web winding and measuring system of claim 8, wherein the at
least one target characteristic comprises a target diameter for the
roll.
12. The web winding and measuring system of claim 8, wherein the at
least one target characteristic comprises a target ratio of a
number of sheets of the roll to a diameter of the roll.
13. The web winding and measuring system of claim 8 further
comprises a memory coupled to the computing device for generating a
three dimensional profile of the web.
14. A web winding and measuring system, comprising: a. a web
tensioning system; b. a rotatably-mounted spool onto which a web of
material is wound to form a roll; c. a draw roll over which a web
of material is conveyed prior to being wound to form a roll; d. 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; e. a light-receiving
device configured to detect the line; f. a means for generating
measurement data from the detected line; g. a computing device
communicatively coupled to the light-receiving device and
configured to receive the measurement data and calculate web
caliper; and h. 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.
15. The web winding and measuring system of claim 14, wherein
determining an adjustment to at least one parameter includes
determining an adjustment to an amount of tension exerted on the
web.
16. The web winding and measuring system of claim 14, wherein
determining at least one target characteristic includes determining
a target number of sheets of the roll.
17. The web winding and measuring system of claim 14, wherein
determining at least one target characteristic includes determining
a target diameter for the roll.
18. The web winding and measuring system of claim 14, wherein
determining at least one target characteristic includes determining
a target ratio of a number of sheets of the roll to a diameter of
the roll.
19. The web winding and measuring system of claim 14 further
comprising generating, in a memory coupled to the computing device,
a three dimensional profile of the web.
20. The web winding and measuring system of claim 14, wherein the
web tensioning system comprises a pair of draw rolls and a dancer
roll.
Description
BACKGROUND OF THE DISCLOSURE
[0001] 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.
[0002] 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.
[0003] 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.
[0004] 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.
SUMMARY OF THE DISCLOSURE
[0005] 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.
[0006] 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.
[0007] 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 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.
[0008] 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
[0009] FIG. 1 is a schematic diagram of one embodiment of a caliper
measurement and web handling system for winding a roll of web
material;
[0010] FIG. 2 is a block chart of a control method for controlling
the caliper of a web;
[0011] FIG. 3 illustrates a caliper measuring device useful in the
present invention; and
[0012] FIG. 4 is a schematic diagram of another embodiment of a
caliper measurement and web handling system for winding roll of web
material.
[0013] 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 DISCLOSURE
[0014] 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.
[0015] 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 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.
[0016] 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.
[0017] 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.
[0018] 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.
[0019] 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.
[0020] 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.
[0021] 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.
[0022] 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 predetermined position. The
position of the second roller 16 is adjusted by lowering or raising
with the aid of the upper hydraulic actuator 17.
[0023] 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.
[0024] 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.
[0025] 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 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.
[0026] 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.
[0027] 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.
[0028] The first computing device 102 receives the measurement data
from the interface board 124 and calculates the web caliper
(M.sub.c). 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.
[0029] 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.
[0030] 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.
[0031] 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.
[0032] 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 (M.sub.c) are input. The target web caliper
(T.sub.c) 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 P.sub.D, which control signals are
sent to one or several actuators affecting the relative position of
the calender rolls and in-turn the calender nip profile and bad. In
certain embodiments the 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 Po 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.
[0033] 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.
[0034] 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.
[0035] 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 the caliper measurement device 50 may comprise a
multi-point triangulation-based sensor which is well known in the
art. For example, U.S. Pat. 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.
[0036] 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.
[0037] 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.
[0038] 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
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).
[0039] 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.
[0040] 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).
[0041] 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 - x tan .theta. ##EQU00001##
[0042] where .theta. 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 .theta. to increase. Further as the height of the
web relative to the surface of the draw roll increases and
decreases the value of .theta. increases and decreases.
[0043] 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 .phi. 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
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.
[0044] 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.
[0045] 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.
[0046] 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.
[0047] 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 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.
[0048] 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.
[0049] 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.
[0050] 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 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 grows.
[0051] 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.
[0052] 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.
* * * * *