Note: Descriptions are shown in the official language in which they were submitted.
AUTOMATIC SPEED CONTROL OF A REWINDER
TECHNIC~L FIELD
This invention relates generally to paper finishing systems which
include a rewinding machine for converting large parent rolls of paper
into smaller diameter rolls, or logs, an accumulator which provides tem-
porary storage of the logs, and a saw for cutting the logs into rolls hav-
ing a length suitable for use by the consumer. This invention is spe-
cifically directed to an apparatus for automatically controlling the re-
winding speed based on the status of the various machines in the finish-
ing system.
BACKGROUND ART
In early paper finishing systems it was generally customary to man-
ually set the speed of each machine so that it produced work pieces at a
slightly lower rate than could be handled by the next machine in the
line. Thus, a paper finishing system that included a rewinding machine
for converting large parent rolls Q~ paper into smaller diameter rolis, or
logs, a saw for cutting the logs into lengths used by the consumer, and
a wrapper for wrapping the rolls, the log saw speed would be set so that
it could cut logs at a faster rate than could be produced by the rewinder,
and the wrapper speed would be set so that it could wrap rolls at a faster
rate than could be produced by the log saw. When a parent roll has been
exhausted the rewinder must be shut down so that a new parent roll can
be installed. In such a system, while the rewinder is down for a parent
roll change, the flow of logs to the log saw is stopped and the log saw
~S and the wrapper become idle.
It was recognized that the production rate o~ the finishing system
could be increased by incorporating a temporary storage device, called a
log accumulator, between the rewinder and the log saw. Such a ~inish-
ing system is shown and described in U.S. Patent 3,016,780 issued to
D~ W. Mosen on January 16, 1962. One advantage of having an accumu-
lator is that the rewinder can continue to produce logs even when the
log saw is not operating, as the excess logs are stored in the accumu-
lator. Another advantage is that the speed of the rewinder can be set
so that it produces logs at a faster rate than can normally be handled
35 by the log saw. If the speed of the rewinder is set properly, when the
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parent roll is exhausted, there will be a sufficient number of logs stored
in the accumulator to allow cont;nued operation of the log saw and wrapper
while a new parent roll is placed on the rewinder.
In finishing systems that have an accumulator, there are occasions
when the accumulator becomes almost full or full. This could happen,
for example, if the saw were shut down for a period of time and the re-
winder continued to produce logs. If the rewinder is set to produce logs
at a faster rate than can be handled by the log saw, and the accumulator
is almost full when the log saw comes back on line, it is possible to jam
either the accumulator or the log saw and ~he rewinder will shut down
which usually results in waste. If the rewinder shuts down several times
during a relatively short period of time, there is a tendency for the
finishing line operator to lower the rewinder speed thereby lowering the
probability that the finishing system will ever reach a point where the
rewinder can produce more logs than can be instantaneously handled by
the accumulator and the log saw. Over the long term, this reduction in
speed, although slight, can represent a significant reduction of the aver-
age flow rate of product through the finishing system.
It is, therefore, desirable to automatically control the speed of the
rewinder to maintain a high flow rate of product through the finishing
system. It is also desirable to take into account the status of the re-
winder, accumulator and saw when automatically controlling the speed of
the rewinder.
It is quite common for a finishing line operator to be responsible
for operating two web rewinders. One responsibility of the operator is
to replace an exhausted parent roll with a new parent roll. If it should
happen that both parent rolls are exhausted at the same time, the first
rewinder will be shut down for the time required to change the parent
roll, but the second rewinder will be down for the time required to change
two parent rolls. Thus, if it appears that both parent rolls will be
exhausted at the same time, it would be desirable to automatically control
the speed of the rewinders so that the parent rolls will not become
exhausted at the same time.
DISCLOSUF<E O~ INVENTION
35 In accordance with'this P~ven~tion, a web finishing system that in-
cludes a web rewinder and an accumulator includes means for automatically
controlling the speed of the rewinder as a function of the status of the
--3--
accumulator, one measure of which is the number of emp-ty
storage spaces in the accumulator. In another aspect of
this invention, means are provided for automatically con-
trolling the speed of the rewinder based on the status or
efficiency of the rewinder. One example of a measure of
the status or efficiency of the rewinder is the number of
times the rewinder is shut down over a predetermined inter-
val of time. Another example of a measure of the status
or efficiency of the rewinder is the rate that it makes
reject logs. Rewinder speed can also be used as a measure
of the status or efficiency of the rewinder.
In another aspect of the invention, means are
provided for measuring the diarneter of the parent roll in
the rewinder and the speed of the rewinder is automatical-
ly controlled based on the size of the parent roll andthe number of empty storage spaces in the accumulator.
In one described embodiment of the invention, the finish-
ing system includes a second rewinder. Means are provided
for also measuring the diameter of the parent roll in the
second rewinder. The size of the parent roll in both
rewinders are monitored and the winding speed of at least
one rewinder is automatically controlled to prevent both
parent rolls from being exhausted at the same time.
In another aspect of the invention, the finishing
~5 system includes a log saw and means for monitoring the
status of the log saw. The log saw status is a parameter
that is also used to automatically control the speed of
the rewinder.
Other aspects of the invention are as follows:
An improved web finishing system comprising a web
rewinder for making logs from a parent roll and an accu-
mulator for temporarily storing logs, wherein the improve-
ment comprises:
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(a) first means for generating a signal repre-
senting the number of empty storage spaces in the accumulator,
and
(b) circuit means responsive to the first means
signal for automatically controlling the speed of the rewind-
er.
An improved web finishing system comprising a first
web rewinder for making logs from a first parent roll, a
second rewinder for making logs from a second parent roll
and an accumulator for temporarily storing logs, wherein the
improvement comprises:
~ a) first means for generating a signal representing
the size of the first parent roll;
(b) second means for generating a signal represent-
ing the size of the second parent roll;
(c) third means for generating a signal represent-
ing the number of empty storage spaces in the accumulator;
and
~ d) circuit means responsive to the first, second
and third means signals for automatically controlling the
speed of the first rewinder thereby controlling when both
parent rolls run out.
An improved web rewinder for making logs from a
parent roll wherein the improvement comprises:
(a) first circuit means for generating a signal
representative or the efficiency of the rewinder; and
(b) second circuit means responsive to the first
circ~lit means signal for automatically controlling the
speed of the rewinder.
An improved web finishing system comprising a web
rewinder for making logs from a parent roll and an accumu-
lator for temporarily storing logs, wherein the improve-
ment comprises:
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(a) first means for generating a signal represen-
tative of the status of the rewinder;
lb) second means for generating a signal repre-
senting the status of the accumulator; and
(c) circuit means responsive to the first and~
second means signals for automatically controlling the
speed of the rewinder.
In an article handling system, the combination
comprising:
(a) an accumulator adapted to receive and
temporarily store articles;
(b) first article handling means for providing
articles, at a controllable rate, to be stored in the
accumulator;
(c) first circuit means for generating a signal
representing a status of the accumulator; and
(d) second circuit means responsive to the first
circuit means signal for controlling the output rate of
the first article handling means.
BRIEF DESCRIPTION OF DRAWINGS
While the specification concludes with claims
particularly pointing out and distinctly claiming that
which is regarded as the present invention, the objects
and advantages of this invention can be more readily as-
25 certained from the following description of a preferredembodiment when read in conjunction with the accompany-
ing drawings in which:
Fig. 1 is a block diagram o~ the equipment and
sensors that are used in an embodiment of the finishing
30 system;
Fig. 2 is a block diagram of the equipment for
controlling the finishing equipment shown in Fig. l;
Fig. 3 is a flow diagram showing the logic per-
formed by the control equipment depicted in Fiy. 2;
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Fig. 4 is a flow diagram showin~ the logic performed by the
control equipment of Fi~. 2 to determine the efficiency of the
rewinder shown in Fi~. 1; and
Fig. 5 is a flow cliagrarn showing the logic performed by the
5 control equipment of Fig. 2 for keeping track of the stora~e
capacity of the accumulator shown in Fig. 1.
BEST MODE FOR CARRYING OUT THE INVENTION
Figures 1 ancl 2 together comprise a block diagram of a
finishing system in which the speed of a rewinder 10 is
10 automatically controlled in accordance with this invention. The
finishing equipment and sensors are shown in Fig. 1 and the
rewinder 10 speed control equipment is shown in Fig . 2. Only those
elements of rewinder 10 necessary for an understanding of the
invention have been depicted in Fig. 1. A complete description of
15 one type of rewinder 10 that can be automatically controlled in
accordance with this invention is found in U.S. Patent No.
2,769,600, issued November 6, 1956 to E . M . I(witek, et al . The
rewinder 10 is a machine that converts a large parent roll 12 of a
web material, such as toilet tissue or paper towels, into rolls 40,
20 commonly referred to as logs, having a diameter that is suitable
for use by a consumer . The parent rol 1 12 is rotatably mounted
within a support stand 14. During the rewinding process, the web
16 from parent roll 12 is threaded over a bed roll 18 mounted on
axle 20. Bed roll 18 is rotatably driven from motor 22 through
25 appropriate belts and gears represented schematically by dashed
line 24. The speed of rewinding the web 16 is determined by the
~n~ular velocity of the bed roll 18 which can be controlled by
applying a suitable voltage to the input 30, designated REWINDER
COMMAND SPEED, for motor 22. A RFWINDER RUN/STOP signal 32
30 appears at an output of the rewinder 10. This REWINDER RUN/STOP
signal 32 can be provided through a switch or relay closure that
is activated by the on-off swi~ch of rewinder 10. A shaft position
encoder 26 is mechanically coupled to the axle 20 of bed roll 18.
The output signal 34 of encoder 26 is a series of pulses wherein
35 each pulse represents a fixed angle of rotation of the bed roll 18.
As will be described later, these pulses can be processed to
provide an indication of the actual speed of rewinder 10. A sensor,
or transducer 36, provides an analog signal 38, desi~nated ROLL
A1 SIZE, that is representative of the diameter of parent roll 12. In one
embodiment of the invention, the transducer 36 was a sonar gauge, model
35000, manufactured by Stevens International, Inc., however, one skilled
in the art will readily appreciaté that mechanical, optical or other types
5 of sensors or transducers can also provide the required indication of the
diameter of parent roll 12.
The finishing system can include a second rewinder 11. Rewinder
11 can have its own automatic speed control equipment (not shown) which
is identical to the automatic speed control equipment associated with re-
winder 10 shown in Figures 1 and 2. Whether or not rewinder 11 has
its own automatic speed control equipment, in one aspect of the invention,
a second sensor, or transducer 37, provides an analog signal 39, desig-
nated ROLL A2 SIZE, that is representative of the diameter of the parent
roil in rewinder 11 and which can be used to control the speed of rewinder
15 10.
Logs 40 that have been produced by rewinder 10 are transported
by a conveyor 42 toward an accumulator 64. While the logs 40 are en
route to the accumulator 6~, improperly made logs 62, or rejects, are
manually or automatically removed from the finishing system. 1 hus, when
20 hinged member 44 is in the horizontal position, a properly made log 40 is
allowed to proceed toward the accumulator 64, but when hinged member 44
swings downward to the position indicated by dashed line 45, a rejected
log 62 falls into a waste bin 60. As a rejected log 62 falls into the wa~te
bin 60, it trips a sensor 54 and circuit means 56 connected to sensor 54
~5 provides an electrical signal 58, designated REJECT LOG, indicating the
production of a rejected log 62. Properly made logs 40 continue to the
input 4~ of accumulator 64. As log 40 enters accumulator 64, it operates
sensor 51 and circuit means 50 connected to sensor 51 provides an
electrical signal 52, designated LOAD ACC, indicating that a log 40 has
30 been loaded into the accumulator 64.
A detailed construction of log accumulator 64 is not shown as their
construction is well known in the art, as represented, for example, by
U.S. Patent 4,142,626, issued March 6, 1979, to John J. Bradley.
Although the log accumulators depicted in Fig. 1 and described in the
35 Bradley patent are first in, first out accumulators, the rewinder speed
control equipment of this invention will work equally well with a last in,
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first out accumulator. Although not absolutely necessary, it has been
found desirable to provide sensors in the accumulator 64 which provide a
first signal 6~, designated ACC FULL, indicating that the accumulator 64
is full and a second signal 68, indicating that some predetermined number
5 of logs have been stored in accumulator 64. In the described embodiment,
the signal 68, designated ACC HALF FULL, indicates that the accumulator
64 is half full. When a log 72 is discharged from the accumulator 64, it
is transported by a conveyor 70 to a log saw 80 which cuts the logs into
rolls having a length suitable for use by a consumer. As a log 72 is dis-
10 charged from the accumulator 64, it operates a sensor 74 which is con-
nected to circuit means 76 which provides a signal 78, designated
DISCHARGE ACC, indicating that a log has been discharged from the
accumulator 64. The saw 80 is a model 125, manufactured by Paper
Converting Machine Company. A detailed description o~ the saw is not
15 provided because it is not necessary for a description of this invention.
The saw 80 has been modi~ied to provide a saw status signal 82, designated
SAW RUN. In one embodiment of the invention, the saw status signal 82
is an indication that the saw is running which can be provided by a switch
or relay closure that is activated by the on-off switch o~ the saw 80.
20 Examples of other signals representative of the status of saw 80 which
can be used to control the speed of rewinder 10 are log saw waste and
log saw cutting rate.
The individual rolls 86 produced by the saw 80 are transported by
means of a conveyor 84 to either a wrapping machine (not shown) or to
25 a packing machine (not shown).
Fig. 2 is a block diagram of the equipment that accepts the finish-
ing system sensor signals and machine status signals and automatically
controls the speed of rewinder 10. The analog signal 39, ROLL A2 SIZE,
is converted into a digital number, A2, by an analog-to-digital converter
S 91. The digital number A2 is applied to an input 142 of a programmable
controller 140. Programmable controller 140 is a Modicon 384 available
from Gould, Inc. Similarly, the analog signal 38, ROLL A1 SIZE, is con-
verted to a digital number, A1, by an analog -to-digital converter 90.
The digital number, A1, is ap~lied to an input 144 of programmable
controller 140. The LOAD ACC signal 52 is applied as a digital signal, F,
to an input 146 of programmable controller 140. The accumulator status
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signal 66, ACC FULL, is applied as a digital input, G, to an input 148
of programmable controller 140. The accumulator status signal 68, ACC
HALF FULL, is applied as a digital signal, H, to an input 150 of program-
mable controller 140. The accumulator status signal 78, DISCHARGE ACC,
5 is applied as a digital signal, I, to an input 152 of programmable controller
140. The saw status signal 82, SAW RUN, is applied as a digital signal,
J, to an input 153 of programmable controller 140.
The counter and gates circuitry 96 and counter 102 convert the
ANGLE CHANGE signal 34 from encoder 26 into a digital number that is
10 proportional to the actual speed of the rewinder 10. As shown in the
figure, the counter portion of circuit 96 counts at a 1 megahertz rate.
The gate portion of circuit 96 provides a gating signal 9ô that has a pre-
determined time duration. This gating signal 98 is applied to a gate
input 106 of counter 102. The ANGLE CHANGE pulses 34 from encoder 26
are applied to a count input 104 of counter 102. When counter 102 counts
the number of ANGLE CHANGE pulses that occur over a predetermined
period of time, the resultant count will be a digital number directly pro-
portional to the actual speed of rewinder 10. If the duration of gate
signal 98 is appropriately selected, the digital number in counter 102 will
be a convenient multiple of either meters or feet per second. Since the
programmable controller 140 may want to look at the number, Y, repre-
senting rewinder 10 speed while the number in counter 102 is changing,
it has been found desirable to employ a buffer register 118. The digital
output 110 of counter 102 is applied to a data input 112 of buffer
~5 register 11~. The gate signal 98 of circuit 96 is applied to a set input 116of buffer register 118. At the end of the predetermined count period
for counter 102, as designated by the trailing edge of gate signal 98,
the digital number determined by counter 102 is transferred into buffer
register 118. The output 120 of buffer register 118 is a digital number,
Y, representing the actual speed of rewinder 10 and is applied to input 154
of programmable controller 140. The counter in circuit 96 and counter 102
are both reset by a timing signal, which in one embodiment occurs every
2 minutes. This timing signal is provided at an output 162 of the program-
mable controller 140. The resetting of buffer register 118 occurs every
2 minutes and is also accomplished by a timing signal provided at an
output 164 of programmable controller 140.
The WINDER RUN/~TOP signal 32 is applied -to a count input 124 of
a counter 122 and is also applied as a digital signal, B, to an input 156
of programmable controller 140. The output of counter 122 is a digital
number, V, that is applied to an input 158 of programmable controller 140.
Counter 122 is reset once every minute by a timing signal provided at an
output 166 of programmable controller 140. If rewinder 10 is running
well, the number V in counter 122 will be either zero or one. If the
rewinder 10 is running poorly and has been shut down several times in a
short period of time, the number V in counter 122 can be a number
greater than one. Thus, the number V is an indication of the status or
efficiency of rewinder 10.
The REJECT LOG signal 58 is applied to the count input 132 of a
counter 130. The output 136 of counter 130 is a digital number, W, that
is applied to an input 160 of programmable controller 140. Counter 130
is reset every minute by a timing signal provided at an output 168 of
programmable controller 140. The number W in counter 130 is a measure
of the reject rate and is, therefore, an indication of the status or effi-
ciency of rewinder 10.
The programmable controller 140 processes the sensor and status
information it receives and generates three signals 170, 172, 174, desig-
nated N1, N2 and N3 respectively, representing a digital command speed
for the rewinder 10. If the rewinder 10 is commanded to run at normal
speed, the programmable controller 140 will cause a logical 1 to appear at
output 172. If the rewinder 10 is commanded to run at low speed, which
typically is in the range of 10 to 15% less than normal speed, but which
could be as much as 25 to 35-O less than normal speed, the programmable
controller 140 causes a logical 1 to appear at output 170. If the rewinder
10 is commanded to run at high speed, typically 5 to 15~ higher than
normal speed, but which could be as much as 20 to 35O higher than
normal speed, programmable controller 140 causes a logical 1 to appear at
output 174. The N1, N2 and N3 signals are applied to a motor control
circuit 176 which generates the proper analog REWINDER COMMAND
SPEED signal 30. The motor control circuit 176 includes three voltage
sources 178, 180, and 182, desigr~ated V1, VZ and V3 respectively. The
negative terminals of voltage sources V1, V2 and V3 are connected to
ground 198. The positive terminal of voltage source 178 is connected to
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node 196, representing the REWINDER COMMAND SPEED signal 30, through
normally open relay contacts 186. Similarly, the positive terminal of
voltage source 1~0 is connected to node 196 through normally open relay
contacts 190, and the positive terminal of voltage source 182 is connected
to node 196 through normally open relay contacts 194. The motor control
circuit 176 includes circuitry, represented by dashed line 184, which
causes relay contacts 186 to close when a logical 1 signal appears at
output 170 of programmable controller 140. Similarly, motor control
circuit 176 includes circuitry, indicated by dashed line 188, which closes
relay contacts 190 when a logical 1 signal appears at output 172 of pro-
grammable controller 140, and circuitry, as indicated by dashed line 192,
which closes relay contacts 194 when a logical 1 signal appears at output
174 of programmable controller 140. It is contemplated that voltage
sources V1, V2 and V3 can be adjusted manually by the operator. The
adjustment of voltage source V2 gives the operator control of the normal,
or approximately the average, speed of the rewinder 10. Although pro-
grammable controller 140 has been describecl as providing three levels of
commanded rewinder speed, it will be appreciated by those skilled in the
art that the sensor and status information can be processed by program-
mable controller 140 in a manner that provides many more levels of
rewinder speed command, in which case, a suitable motor control circuit
176 would be provided to generate the analog, REWINDER COMMAND
SPEED signal 30. Furthermore, the functions performed by program-
mable controller 140 could be performed by a digital computer or by
special purpose circuitry.
Figures 3, 4 and 5 are flow diagrams illustrating the logic performed
by programmable controller 140 while processing the sensor and status
information in order to select the normal, low or high speed command
signals for motor control circuit 176.
In the discussion that follows, X represents the number of empty
spaces available in accumulator 64. The numbers X1, X2 and X3 depend
on system parameters such as accumulator size, etc. and in the described
embodiment have the values 30, 60 and 20 respectively. The number X4
is that number of rolls that can be finished from a parent roll that has a
diameter equal to A.
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Fig. 3 is the flow chart of the main control routine for programmable
controller 140. This control routine is executed about 10 to 15 times
every second. The start of the routine is indicated by block 200.
Upon entering the main routine, a check is made as indicated by
5 decision block 202, to see if the rewinder 10 is running. If the rewinder
10 is not running, the programmable controller 140 waits until the
REWINDER RUN/STOP signal, B, indicates that the rewinder has been
turned on. If the rewinder 10 is running, a rewinder status bit, M, is
checked as indicated by decision block 204. If the rewinder status bit,
10 M, is a logical one, indicating that rewinder 10 is not running well,
blocks 206 and 208 command the rewinder 10 to operate at normal speed.
Thus, the speed of the rewinder 10 is automatically controlled by the
status or efficiency of the rewinder 10. If the rewinder status bit, M,
is a logical zero indicating that the rewinder 10 is running well, program-
mable controller 140 performs decision block 210. The logic of decision
blocks 210, 212 and 214 controls the speed of rewinder 10 so that the
parent roll 12 in rewinder 10 does not become exhausted at the same time
as the parent roll in rewinder 11. Thus, if the diameters of both parent
rolls are less than A, block 224 is performed which commands rewinder 10
20 to run at low speed. If the diameter of parent roll 12 in rewinder 10 isless than A, and the diameter of the parent roll in rewinder 11 is greater
than A, biock 216 will command rewinder 10 to run at high speed if there
are enough empty spaces in the accumulator 64 to accept the rolls, as
determined by decision block 214, and will be operated at low speed if
25 there are not enough empty spaces in the accumulator 64.
Decision blocks 218, 220 226 and 228 select the speed of rewinder 10
based on the status or efficiency of the saw and the status, or number
of empty spaces available in accumulator 64, when the diameter of the
parent roll 12 in rewinder 10 is greater than A. If the saw 80 is running,
30 the rewinder 10 is commanded to wind at low speed if there are fewer
than 21 empty spaces available in the accumulator 64, is commanded to
wind at normal speed if there are between 21 and 60 empty spaces
available in accumulator 64, or is commanded to wind at high speed if
there are more than 60 empty spaces available in the accumulator 64. If
35 the diameter of parent roll 12 in rewinder 10 is greater than A, and the
saw 12 is not running, the rewinder 10 is commanded to wind at low
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speed if there are ~ewer than 30 empty spaces available in accumulator 64,
is commanded to wind at normal speed if there are between 31 and 60
empty spaces available in accumulator 64, or is commanded to wind at high
speed if there are more than 60 empty spaces available in accumulator 64~
Referring now to Fig. 4 there is shown a flow diagram of the sub-
routine for keeping track of the status or efficiency of rewinder 10. If
the rewinder 10 is running well, the rewinder status bit, M, will be equal
to a logical 0, and if rewinder 10 is running poorly, the rewinder status
bit, M, will be set to a logical 1. As indicated by decision block 242, a
check is made to see if rewinder 10 has been shut down more than twice
during the past one minute. If it has been shut down an excessive
number of times, this is an indication that the rewinder 10 is operating
poorly and block 250 causes the rewinder status bit, M, to be set to a
logical 1. If the rewinder 10 has not been shut down an excessive number
of times, that is an indication that the rewinder is running properly and
block 246 causes the rewinder status bit, M, to be set to a logical 0 and
then proceeds to decision block 248. Block 248 checks the reject rate of
rewinder 10. If more than two logs have been rejected since the start
of a one minute interval, the rewinder is not performing well and the
rewinder status bit, M, is set to a logical 1. If fewer than two logs have
been rejected since the start of the last one minute interval, the rewinder
10 is considered to be running well and the rewinder status bit, M, is
left equal to a logical 0.
Fig. 5 is a flow chart showing the subroutine that keeps track of
the number of empty spaces in the accumulator 64. The s~art of the sub-
routine is indicated at block 260. As mentioned above, the variable X
represents the number of empty spaces in the accumulator 64. Blocks
262 and 264 recognize the presence of the LOAD ACC signal, F, indica-
ting that a log is being stored in the accumulator 64, and subtracts one
from the number of empty spaces, X, in accumulator 64. Blocks 266 and
268 respond to the ACC FULL signal, G, and sets X equal to zero which
means that there are no spaces aYailab!e in accumulator 64. Blocks 270
and 272 respond to the ACC HALF FULL si~nal, H, and sets X equal to
70 which is one-half the storage capacity of accumulator 64. Blocks 274
and 276 respond to the [~ISCHARGE ACC signal, I, by adding one to
the number of empty spaces, X, in the accumulator 64. It is to be noted
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that blocks 266, 268, 270 and 272 are not absolutely necessary for pro-
grammable controller 140 to keep track of the number of empty spaces in
accumulator 64. The logic represented by blocks 266-272 acts as a check
on the value of the variable X in the event the programmable controller
5 140 fails to properly keep track of the number of empty spaces in the
accumulator 64. It will also be appreciated that while the ACC FULL and
ACC HALF FULL signals are convenient for the accumulator employed in
the described system, any other convenient checkpoints could be employed.
Thus, a finishing system has been described that can include a web
rewinder 10, an accumulator 64 and a saw 80. A programmable controller
140 automatically controls the speed of rewinder 10 based on the status
of the system or on the status of the equipments that make up the
system. Among the parameters that can control the speed of rewinder 10
are: the status of the rewinder 10, the efficiency of the rewinder 10,
the status of the accumulator 64, the status of the saw 80, the size of
the parent roll 12 in the rewinder 10 being controlled by programmable
controller 140, and the size of the parent roll in a rewinder 11 that is
adjacent to the controlled rewinder 10. Although the operator can
establish the normal speed, which approximates the average speed, of the
rewinder 10, the programmable controller 140 controls the instantaneous
speed of the rewinder 10 to optimize the productivity of the entire fin-
ishing system.
While the present invention has been described with reference to a
specific enbodiment thereof, it will be obvious to those skilled in the art
that various changes and modifications may be made without departing
from the invention in its broader aspects.
