Note: Descriptions are shown in the official language in which they were submitted.
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Patent
APPARATUS AND METHODS FOR MINIMIZING WASTE
DURING WEB SPLICING
Related Application
This application claims the benefit of United
States Provisional Application Serial No. 60/880,143
filed 12 January 2007.
Background of the Invention
The invention disclosed herein relates to an
apparatus and method for decreasing the amount of roll
waste present in many web based operations, such as
diaper manufacturing or printing.
Roll waste occurs when the material on an
expiring roll, such as a paper roll, is not completely
unwound prior to splicing a standby material roll into
the system, leaving raw material remaining on the core of
the expiring roll. In present methods using standard web
splicing techniques, material in a radius of as much as
1/," to '-~" of raw material remains on the core of the
expiring roll, and this material is generally wasted.
During the course of time, the roll waste can become
quite considerable in terms of both cost and waste of
natural resources.
During web processing operations, a web is fed
from a primary supply wheel (the expiring roll) into the
manufacturing process. As the material from the expiring
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roll is paid out, it is necessary to splice the leading
edge of a web from a standby roll to the trailing edge of
the material on the expiring roll in a manner that will
not cause interruption of the web supply to a web
consuming or utilizing device.
In modern splicing systems, a web accumulation
dancer system may be employed, in which an accumulator
accumulates a substantial length of a running web. By
using an accumulator, the material being fed into the
process can continue, yet the trailing end of the
material can be stopped or slowed for a short interval so
that it can be spliced to leading edge of the new supply
roll. The leading portion of the expiring roll remains
being paid out continuously to the web-utilizing device.
The accumulator continues to feed the web utilization
process while the expiring roll is stopped so the new
material roll can be spliced to the end of the expiring
roll.
In this manner, the device has a constant web
supply being paid out from the accumulator, while the
stopped web material in the accumulator can be spliced to
the standby roll. Examples of web accumulators include
that disclosed in U.S. Patent Application Serial No.
11/110,616, which is commonly owned by the assignee of
the present application, and incorporated herein by
reference.
A zero speed splice unit is an air-operated
clamping and cutting mechanism. The purpose of the
splice unit is first to join an expiring material roll
with the leading edge of a standby roll, then to cut the
expiring roll from the process. The splice unit uses two
clamp bars, one on each side. The clamp bar nearest to
the expiring web advances to make the splice. A knife
located in the center of the unit captures the expiring
web on the drive side and cuts the web as it advances to
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the operator side. The clamp releases, and the knife
returns.
An electrical sensor monitors the RPM of the
active web spindle. A diameter is calculated for the
expiring roll using the machine web speed and the RPM of
the spindle. When the expiring roll diameter reaches a
preset size, the machine control system initiates an
automatic splice. The spindle motor stops the expiring
roll and the accumulation is paid out.
The splice unit joins the expiring web with
the standby web while the two webs are at rest. The
machine continues to run during the splice because of web
material stored in the accumulator. The splice knife
then cuts the expiring material web before accelerating
new material from the standby roll. The spindle motor
accelerates the new material roll to the proper speed
before the web is used up in the accumulator.
Machine vision systems typically requires
digital input/output devices and computer networks to
control other manufacturing equipment, in this case the
splicing unit.
A typical machine vision system will consist
of several among the following components:
= One or more digital or analog camera (black-and-
white or colour) with suitable optics for acquiring
images
= Lighting
= Camera interface for digitizing images (widely
known as a "frame grabber")
= A processor (often a PC or embedded processor, such
as a DSP)
= Computer software to process images and detect
relevant features.
= A synchronizing sensor for part detection (often an
optical or magnetic sensor) to trigger image
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acquisition and processing.
= Input/Output hardware (e.g. digital I/O) or
communication links (e.g. network connection or RS-
232) to report results
= Some form of actuators used to sort or reject
defective parts.
The sync sensor determines when a part (often
moving on a conveyor) is in position to be inspected. The
sensor triggers the camera to take a picture of the part
as it passes by the camera and often synchronizes a
lighting pulse. The lighting used to illuminate the part
is designed to highlight features of interest and obscure
or minimize the appearance of features that are not of
interest (such as shadows or reflections).
The camera's image can be captured by the
framegrabber. A framegrabber is a digitizing device
(within a smart camera or as a separate computer card)
that converts the output of the camera to digital format
(typically a two dimensional array of numbers,
corresponding to the luminous intensity level of the
corresponding point in the field of view, called pixel)
and places the image in computer memory so that it may be
processed by the machine vision software.
The software will typically take several steps
to process an image. In this case, the image processing
will result in either detection of the indicator
material, or non-detection of the indicator material.
Commercial and open source machine vision
software packages typically include a number of different
image processing techniques such as the following:
= Pixel counting: counts the number of light or dark
pixels
= Thresholding: converts an image with gray tones to
simply black and white
0 Segmentation: used to locate and/or count parts
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= Blob discovery & manipulation: inspecting an image
for discrete blobs of connected pixels (e.g. a
black hole in a grey object) as image landmarks.
These blobs frequently represent optical targets
for machining, robotic capture, or manufacturing
failure.
= Recognition-by-components: extracting geons from
visual input
= Robust pattern recognition: location of an object
that may be rotated, partially hidden by another
object, or varying in size
= Barcode reading: decoding of 1D and 2D codes
designed to be read or scanned by machines
= Optical character recognition: automated reading of
text such as serial numbers
= Gauging: measurement of object dimensions in inches
or millimeters
= Edge detection: finding object edges
= Template matching: finding, matching, and/or
counting specific patterns.
In most cases, a machine vision system will use a
sequential combination of these processing techniques to
perform a complete inspection. A system that reads a
barcode may also check a surface for scratches or
tampering and measure the length and width of a machined
component.
Summary of the Invention
An apparatus and methods are disclosed to
reliably utilize material as close as possible to the end
of the primary supply wheel so to minimize the roll
waste.
An indicator material, such as tape, is
positioned on the primary and standby supply wheels at a
distance from the end of the roll so that a reader, such
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as a machine vision system, can detect the presence or
absence of the indicator material on the rolls. If the
indicator material is present, the machine vision system
will initiate a minimal waste splice logic. If the
indicator material is absent, the machine vision system
will initiate a standard splice logic.
Brief Description of the Drawings
Fig. 1 is a perspective and schematic view of
an apparatus for detecting an indicator material present
on a supply roll;
Fig. 2 is a logic flowchart for an apparatus
for detecting an indicator material present on a supply
roll;
Fig. 3 is a side view of apparatus for
detecting an indicator material present on a supply roll
including a splicer.
Description of the Preferred Embodiment
Although the disclosure hereof is detailed and
exact to enable those skilled in the art to practice the
invention, the physical embodiments herein disclosed
merely exemplify the invention which may be embodied in
other specific structures. While the preferred
embodiment has been described, the details may be changed
without departing from the invention, which is defined by
the claims.
Referring now to Fig. 1 is a perspective and
schematic view of an apparatus for detecting an indicator
material present on a supply roll is disclosed. In this
system, vision system 12 is supplied to detect the
presence or absence of indicator material 16. As shown,
it is preferred that indicator material 16 be positioned
extending externally of the material roll 14, which is
rotatably held in the system by spindle 18. The web 20
is paid out to a splicer as shown. In an alternate
embodiment, the indicator material need not extend
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externally of the material roll 14, but instead could be
either applied to the side or interior of the roll 14,
either radially or longitudinally. The positioning of
the indicator material 16, although preferred to extend
externally from the roll 14, is based on preference of
the material supplier of the roll 14, and detection of
the indicator material 16 is adjusted by adjusting the
field of vision of the vision system 12.
One preferred indicator material 16 is simply
tape that extends out from the roll 14. However, any
identifiable feature that either the material supplier or
the user adds at a predetermined distance from the end of
the roll suffices.
In an alternate embodiment, the indicator
material 16 could be coded with information to tell the
vision system 12 the exact distance to the end of the
roll, if the indicator material 16 is not set at a
predetermined distance.
The vision system 12 is coupled to a
programmable logic controller, which controls the splicer
through the logic provided in Fig. 2; either standard or
minimal waste splice logic.
Referring now to Fig. 2, a logic flowchart for
an apparatus for detecting an indicator material present
on a supply roll is shown. In this logic, if the vision
system 12 detects the indicator material 16, minimal
waste splice logic is employed. If the vision system 12
does not detect the indicator material 16, standard
splice logic is employed.
In the standard splice logic, a user measures
the diameter of the new supply roll and enters the
diameter into the splice controller. An electrical
sensor monitors the RPM of the web spindle carrying the
new supply roll as the roll is paid out. A diameter is
calculated for the expiring material roll using the
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machine web speed and the RPM of the spindle. When the
roll diameter reaches a preset size, the machine control
system initiates an automatic splice. The spindle motor
stops the active roll. The splice unit joins the
expiring web with the new web while the two webs are at
rest. The machine continues to run during the splice
because of web material stored in the accumulator. The
splice knife then cuts the old material web before
accelerating new material. The spindle motor accelerates
the new material roll to the proper speed before the web
is used up in the accumulator.
In the minimal waste splice logic, it is
preferred that the indicator material 16 is set at a
predetermined distance from the end of the roll, for
instance 3 to 6 feet of material remaining. In this
manner, early detection of the presence of the indicator
material 16 will trigger the splice based on the known
distance to the end of the roll. Then, by computing the
time until the end of the roll is reached by using the
RPM of the spindle, the machine control system can
initiate the automatic splice routine based on time, and
the time to initiate the splice can be calculated and
activated to take place just prior to reaching the end of
the roll.
One purpose of the indicator material is to
allow the vision system 16 to recognize ahead of time
what type of roll is in the expiring position, and also
to calculate how much material remains on the roll 14, in
order to calculate the time/distance left relationship,
and to trigger the splice routine at just the right time
to eliminate the possibility that the roll 14 will expire
without being spliced to the new roll, which can lead to
machine down time. In this manner, the splice triggered
by the machine PLC will initiate at a time when the roll
is almost, but not yet fully, expired. For instance, if
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the vision system recognizes that the roll contains
indicator material 16, and the machine PLC is informed
that the roll 14 will have exactly 3 feet left, and
further is informed at what rate the material is being
paid out, the machine PLC would then calculate the amount
of time remaining until initiating a splice with nearly
zero material remaining on the roll.
Referring now to Fig. 3, a side view of
apparatus for detecting an indicator material present on
a supply roll includ=ing a splicer is shown.
As can be seen, two vision systems 12 may be
employed such that each system is directed at an
indicator material 16 on both the expiring roll 14a and
the new supply roll 14b. It is noted that only one of
the two visions systems 12 would be reading the expiring
roll (14a as shown in Fig. 3), and thus communicating
with the machine PLC and splicer, at any given time. The
other vision system 12 would not activate until the new
supply roll (14b as shown in the sequence in Fig. 3)
became the expiring roll (14b as shown in the sequence in
Fig. 3). Only the vision system 12 watching the expiring
roll need be involved in the splice logic selection
process described with reference to Fig. 2.
Both the expiring roll 14a and the new supply
roll 14b feed webs 20 into the splicer for splicing,
which is controlled by the machine PLC coupled to the
vision systems 12. The web 20 is paid out into the
accumulator 22, which can be of any type used to
facilitate constant supply of the web 20 to the process,
while allowing zero speed splicing at the splicer unit.
It is only necessary for the indicator
material 16 to be present on the expiring material roll
14a in order to select the minimal waste splice logic,
because the splice logic is initiated based on the
marker-tape on the expiring roll. If the new roll that
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is spliced into the process is a standard roll, lacking
indicator material 16, then the subsequent splice would
be a standard splice based on the splice logic.
The foregoing is considered as illustrative
only of the principles of the invention. Furthermore,
since numerous modifications and changes will readily
occur to those skilled in the art, it is not desired to
limit the invention to the exact construction and
operation shown and described. While the preferred
embodiment has been described, the details may be changed
without departing from the invention, which is defined by
the claims.
