Note: Descriptions are shown in the official language in which they were submitted.
CA 02680621 2016-03-23
L, =
=
SYSTEM AND METHOD FOR DOUGH EXTRUSION
[0001]
BACKGROUND
[0002] The present disclosure relates generally to the field of dough
extrusion. More
specifically, the disclosure relates to compensation for pressure variance
during dough extrusion.
[0003] Dough (e.g., for bread, buns, or other flour based dough products) can
be
conventionally divided into smaller pieces (e.g., 16-32 ounces) at speeds
ranging from 0 to 200
plus pieces per minute by machine commonly called a Rotary Extrusion Divider
or, Advanced
Dough Divider, for example as manufactured by AMF, Inc. of Richmond, Virginia.
The Rotary
Extrusion Divider conventionally includes an auger (e.g., two screws)
contained in a horizontal
chamber for kneading and moving the dough to a metering pump, or pumps
sometimes via a
distribution manifold that can at least partially control the speed of the
dough as it is sent to a
knife or multiple knifes for cutting at a predetermined size or weight. Other
conventional
methods of dividing dough may not generally be as accurate and repeatable as a
Rotary
Extrusion Divider. Despite the Rotary Extrusion Divider being prominent for
dividing dough,
there has been only been small improvements to the original design of auger
screws feeding a
pump, or pumps.
[0004] Due to the rotational nature of the augers, and the operation of the
metering pump,
the pressure of the dough entering the metering pump varies. This pressure
variation oscillates
generally along a repeating wave pattern, which reduces the overall accuracy
of the
- 1 -
CA 02680621 2009-09-24
Rotary Extrusion Divider scaling weights and requires that excess or
additional dough be
included with each dough division according to statistical models of the
accuracy and precision
of the system performance. Further, this pressure variation is enhanced by the
fixed period of the
knife relative to the period of the repeating wave pattern.
[0005] In recent years, secondary companies have developed add-on machinery to
compliment the Rotary Extrusion Divider. The add-on machinery has helped to
reduce some of
the inherent machine scaling deficiencies. For example, a machine called a
Dough Saver
manufactured by Bakery Systems, Inc. of Saint Louis, MO is essentially a
weight checker
typically positioned between the Rotary Extrusion Divider and a dough ball
conical rounder, or
horizontal rounding bars (however, in some cases because of space limitations
it is located after
the rounder, or bars). The Dough Saver is designed to weigh every dough ball
from the Rotary
Extrusion Divider, however in some cases 100% weight measurement is not
possible. The
computer that controls the Dough Saver and its internal algorithms typically
provides modulating
control to the metering pump(s) based on the dough ball weight measurements.
Depending on a
predefined set of weight samples taken, the computer will change the pump
speed to vary the
weight. However, even with the use of a Dough Saver variability of weights
still exists.
SUMMARY
[0006] One embodiment of the disclosure relates to a system for extrusion of
dough.
The system comprises an auger for moving the dough; a metering pump comprising
an input; a
first motor for actuating the auger to transfer dough to the input of the
metering pump; a first
encoder for reading a position or speed of the first motor and for
transmitting a signal associated
with the position or speed of the first motor; and a controller configured to
receive the signal
from the first encoder to control operation of the first motor. The controller
operates the first
motor to at least partially counteract a variance in a pressure of dough at
the metering pump.
[0007] Another embodiment of the disclosure relates to a method for
controlling
extrusion of dough. The method comprises actuating an auger with a motor;
transferring dough
-2-
CA 02680621 2009-09-24
to an input of a metering pump using the auger; and operating the motor using
the controller to at
least partially counteract a variance in a pressure of dough at the metering
pump. The method
may include reading a position or speed of the first motor using an encoder,
and transmitting a
signal associated with the position or speed of the first motor from the
encoder to a controller.
The method may further comprise operating the motor based on the signal
associated with the
variance in pressure and based on the signal from the encoder.
[0008] Another embodiment of the disclosure relates to a system for extrusion
of
dough. The system comprises an auger; a metering pump comprising an input; a
first motor for
actuating the auger to transfer dough to the input of the metering pump; a
controller configured
to control operation of the first motor; and a pressure sensor configured to
detect a pressure of
the dough and configured to transmit a signal associated with the pressure to
the controller. The
controller operates the motor to at least partially compensate for a variance
in the pressure of
dough
BRIEF DESCRIPTION OF THE DRAWINGS
100091 FIG. I is a schematic view of a dough extrusion system according to an
exemplary embodiment.
100101 FIG. 2 is a schematic view of a dough extrusion system according to
another
exemplary embodiment.
100111 FIG. 3 is a schematic view of a dough extrusion system according to
still
another exemplary embodiment.
[0012] FIG. 4 is a schematic view of a dough extrusion system according to a
further
exemplary embodiment.
[0013] FIG. 5 is a flow diagram of a dough extrusion method according to an
exemplary embodiment.
-3-
CA 02680621 2009-09-24
[00141 FIG. 6 is a flow diagram of a dough extrusion method according to
another
exemplary embodiment
100151 FIG. 7 is a flow diagram of a pressure variance compensation method
according
to an exemplary embodiment.
100161 FIG. 8 is an exemplary illustration of a potential improvement by
implementing
encoders and pressure variance compensation.
[00171 FIG. 9 is an exemplary illustration of another potential improvement by
implementing encoders and pressure variance compensation.
DETAILED DESCRIPTION OF THE EXEMPLARY EMBODIMENTS
[00181 Referring to FIG. 1, a dough extrusion system 10 is configured to
divide dough
(e.g., viscous materials for making bread, buns, biscuits, rolls, dumplings,
pastry, cookies, or
other dough-based products) into discrete sizes or weights, for example for
later packaging, for
baking, etc., according to an exemplary embodiment. Dough extrusion system 10
generally
includes a hopper 12 that receives dough either in a batch of varying sizes,
or metered into the
hopper 12 via a conveyor, or pipe and guides it to an auger 14. Auger 14 is
actuated by a first
motor 16, which is driven by a first variable frequency drive ("VFD") 18, and
a gearbox 20 via a
chain or belt 22. According to various exemplary embodiments, first motor 16
may be any type
of motor capable of actuating auger 14, for example an asynchronous 3-phase AC
motor. Auger
14 may include one or more screws that rotate to pass dough to an input of a
metering pump(s)
24. The screws may be open screws or closed screws according to various
exemplary
embodiments. According to some exemplary embodiments, the screws may have
varied pitches,
for example a pitch between about 6 and 10 degrees. Due to the rotational
nature of augers 14,
and the operation of the metering pump, the pressure of the dough entering the
metering pump
24 varies. This pressure variation oscillates generally along a repeating wave
pattern, for
example a generally sinusoidal wave or other repeating wave pattern (e.g., see
FIG. 8). For
-4-
CA 02680621 2009-09-24
example, the dough pressure may vary along a repeating wave pattern between
about 20 and 90
pounds per square inch ("PSI") (per revolution), between about 30 and 80 PSI,
between about 40
and 70 PSI, between about 50 and 60 PSI, between about 53 and 57 PSI, up to
about 65%, up to
about 45%, up to about 27%, up to about 10%, up to about 3.5%, or other
variation along a
repeating wave pattern.
[0019] Metering pump(s) 24 is actuated by a second motor(s) 26 driven by a
second
variable frequency drive(s) 28. According to various exemplary embodiments,
metering
pump(s) 24 may be a positive displacement pump or any other type of pump
capable of receiving
dough and outputting the dough at a generally constant rate with minimal
variation. Metering
pump 24 outputs the dough at a generally constant speed through a pipe and
shape to a cutting
device or knife(s) 30 (e.g., cutting or slicing device, etc.) that cuts the
dough into discrete sizes.
Knife 30 is actuated by a third motor(s) 32 driven by a third variable
frequency drive(s) 34 and
may be any knife capable of cutting dough. A conveyor or other material
handling system or
apparatus may be located at the output of knife 30.
[0020] It is noted that while a single metering pump 24, second motor 26,
second
variable frequency drive 28, knife 30, third motor 32, and third variable
frequency drive 34 are
illustrated, according to other exemplary embodiments, system 10 may include
more than one of
each these components. For example, system 10 may include a manifold coupled
to auger 14 for
dividing the dough into multiple lines for cutting. Each of the multiple lines
may include a
respective metering pump, second motor, second variable frequency drive,
knife, third motor,
and third variable frequency drive 34. In other embodiments, the manifold may
be located
between the metering pump and the knife, or at the output of the knife.
[0021] As the dough passes from auger 14 to metering pump(s) 24, a pressure
transducer or sensor 36 measures the pressure of the dough at the input of
metering pump 24.
An electrical signal representing the pressure reading is sent to a
proportional-integral-derivative
("PID") loop controller 38 coupled to first variable frequency drive 18. PID
loop 38 and first
variable frequency drive 18 then output a signal to first motor or auger motor
16 to adjust the
-5-
CA 02680621 2009-09-24
speed of auger 14 to provide an amount or pressure of dough to metering pump
24 with little
variance. According to various exemplary embodiments, pressure sensor 36 can
be any type of
absolute or relative pressure sensor capable of sensing the pressure of the
dough at metering
pump 24. According to alternative exemplary embodiments, pressure sensor 36
may be replaced
by any of a variety of technologies capable of measuring or detecting volume,
weight, mass,
density, or other characteristic of dough.
[0022] PID control loop 38 may receive an input variable in the process being
measured (a process variable ("PV")) and compare it to a process setpoint (SP)
to eliminate or
reduce an error or difference between the process variable and setpoint. The
error can be caused
by natural tendencies in system 10 or by an external disturbance. PID loop 38
calculates a
control variable (CV) that is output to a system device that has influence
over the process
variable. In the illustrated exemplary embodiments, the setpoint is the
desired pressure, the
process variable is the actual pressure read from pressure sensor 36, and the
control variable is a
speed command to auger motor 16 that has a direct effect on the pressure. PID
loop 38 may
provide a generally constant pressure at the desired setpoint to allow
consistent metering by
metering pump 24, resulting in more accurate and consistent dough piece
weights.
[0023] The PID loop mathematics operate on control systems feedback loop
theory
using three parameters. The "P" in the system is the proportional term used to
designate the
proportional response of the error between process variable and setpoint. The
higher the
proportional gain, the larger the response to error. The "I" in the system is
the integral term and
generally provides a proportional response by analyzing past error values over
time. The integral
term can reduce error faster than proportional control alone but also can
cause the process
variable to overshoot after reaching setpoint since it is using past values.
The "D" is the
derivative term of loop control and provides a response to the error by
looking at the rate of
change of the error to predict future error values and eliminate them. The
derivative term may
counteract the integral overshooting but slow down the response as well. The
three parameters
are generally tuned to values that are appropriate for a particular system,
for example dough
extrusion system 10. According to various exemplary embodiments, any one of
several tuning
-6-
CA 02680621 2009-09-24
methods and theories may be used that take into account different parts and
types of the dough
extrusion process.
[0024] Each of first variable frequency drive 18, second variable frequency
drive 28,
and third variable frequency drive 34 may also be coupled to a manual
potentiometer 39
configured to allow an operator to manually adjust the speed of first motor
16, second motor 26,
and third motor 32. According to some exemplary embodiments, a vacuum pump 40
may be
placed in the auger chamber. Vacuum pump 40 is generally configured to "degas"
the dough or
remove air pockets in the dough and assist in the movement of dough in hopper
12 into the auger
(14). Vacuum pump 40 may be any vacuum pump of past, present, or future design
that is
capable of removing air. It is noted that according to other exemplary
embodiments, vacuum
pump 40 may be omitted.
[0025] Referring to FIG. 2, a dough extrusion system 100 similar to system 10
of FIG.
1 is configured to divide dough into discrete sizes or weights, for example
for later packaging,
for baking, etc., according to an exemplary embodiment. System 100 includes a
programmable
logic controller ("PLC") 102 instead of PID controller 38 or including the PID
logic. PLC 102
can adjust first, second, and/or third variable frequency drives 18, 28,
and/or 34 to control the
speed of first motor 16/auger 14, second motor(s) 26/metering pump(s) 24,
and/or third motor(s)
32/knife(s) 30 based on pressure readings from pressure sensor 36. According
to various
exemplary embodiments, PLC 102 can be any PLC of past, present, or future
design that is
capable of controlling the variable frequency drives or the speed of the
motors in extrusion
system 100.
[0026] PLC 102 may be coupled to a user or operator interface 104 to allow an
operator
to monitor and adjust the machine more easily. Interface 104 may include a
recipe management
system to facilitate the storage of operating variables (e.g., in a memory)
depending on the type
or recipe of dough, including individual PID loops, parameters and allow a
more rapid "one
step" changeover.
-7-
CA 02680621 2009-09-24
[0027] Actuation of the auger screws may cause a natural variation in pressure
at
metering pump 24. For example, the shape and rotation of the screws may cause
a naturally
occurring repeating wave pattern effect, reducing the effectiveness of PID
loop control and
causing variation in the dough pressure at metering pump 24 and reducing the
overall accuracy
of the Rotary Extrusion Divider scaling weights.
[0028] Referring to FIG. 3, a dough extrusion system 200 is configured to
divide dough
into discrete sizes or weights, for example for later packaging, for baking,
etc., according to
another exemplary embodiment. Auger 14, metering pump(s) 24, and pressure
sensor 36 at the
input of metering pump 24 may be generally similar to those like parts of
FIGS. 1 and 2.
[0029] According to the illustrated exemplary embodiment, a first motor 202
and
gearbox 204 (the auger drive motor assembly) may be a servo motor, AC
permanent magnet
motor, or AC synchronous motor that uses feedback from a first encoder 206 and
a zero or close
to zero backlash gearbox, respectively. Servo and servo control technology may
allow cam
profiling to be set up in conjunction with PID control. A controller 208
(e.g., a PLC controller)
can use a cam profile to take the shape and rotation of the auger screws into
account and
counteract the natural cam effect to reduce or eliminate the varying dough
pressure. A different
cam profile can be setup for each type of dough, if necessary. Gearbox 204 is
configured to
allow less backlash of the gears and to have higher tolerance for speed
change. Gearbox 204
may have a speed ratio of about 50:1, to 25:1, or any other suitable ratio
which can be achieved
via the gearbox, or pulley ratios from the gearbox to the auger drive. The
servo motor and servo
control may allow for more precise speed and position control and may permit
use of maximum
torque throughout the speed range. Alternatively, first motor 202 may be a
vector motor with
encoder 206 feedback. A second motor 210 and a third motor 212 for metering
pump(s) 24 and
knife(s) 30 may be vector or servo motors that use feedback from a second
encoder 214 and a
third encoder 216, respectively. One or more of the motors can also be AC
motors with a turn
down ratio of 1000:1 or greater.
-8-
CA 02680621 2009-09-24
[0030] Use of vector or servo motors for auger, metering pump, and/or knife
motors
202, 210, and/or 212 may increase the speed resolution accuracy of system 200.
For example,
the resolution or speed control accuracy may increase from a range of 0.5%-2%
to a range down
to 0.001%. The encoders coupled to each motor may be configured to provide a
signal to a
variable frequency drive and/or PLC 208 that represents an absolute position,
an absolute speed,
and/or notification of a slip of the respective motor. If PLC 208 receives a
signal representative
of the motor position, it may calculate the speed based on a history of
positions at various times.
In the illustrated exemplary embodiments, encoders 214 and 216 coupled to
second motor 210
and motor 212, respectively, are configured to provide data to variable
frequency drive 28 or 34
controlling the respective motor. Encoder 206 coupled to first motor 202 is
configured to
provide data to first variable frequency drive 18 and PLC 208 via a signal
splitter 218 that sends
the data to both variable frequency drive 18 and PLC 208. According to
alternative exemplary
embodiments, encoders 206, 214, and/or 216 may be omitted and motors 202, 210,
and/or 212
can be vector motors that provide vector feedback to the respective variable
frequency drive or
PLC 208.
[0031] Auger 14 may also be coupled to a "home" reference or cam proximity
switch
219 configured to reset the position of auger 14 screws to an original home or
reference position.
PLC 208 may communicate with switch 219 to control when auger 14 is reset. By
resetting
auger 14 to the reference position, PLC 208 knows the position of auger 14
and, with variable
frequency drive 18, can more accurately adjust motor 202 and the speed and
position of auger
14.
[0032] It is noted that while a single metering pump 24, second motor 210,
second
variable frequency drive 28, third motor 212, third variable frequency drive
34, second encoder
214, third encoder 216, and knife 30 are illustrated, according to other
exemplary embodiments,
system 200 may include more than one of each these components. For example,
system 200 may
include a manifold coupled to auger 14 for dividing the dough into multiple
lines for cutting.
Each of the multiple lines may include a respective metering pump 24, second
motor 210, second
-9-
CA 02680621 2009-09-24
variable frequency drive 28, third motor 212, third variable frequency drive
34, second encoder
214, third encoder 216, and knife 30.
[0033] The motors may operate in a given frequency band, for example up to
about 70
Hz, between about 60 and 70 Hz, between about 63.5 and 63.9 Hz, at a frequency
modulating up
to about 1.5 Hz, etc. For a range between about 63.5 and 63.9 Hz with a
modulation of 0.4 Hz, a
conventional resolution of 1% leaves an error of up to about 0.64 Hz, which is
greater than the
typical modulation of the motor. By increasing the resolution to 0.001%, in
the same example,
the error may be only 0.00064 Hz, which is well within the operating range of
the motor.
[0034] The encoder data sent to PLC 208 may be used in conjunction with the
pressure
data from pressure sensor 36 to determine the speed that each motor should be
run at a given
point in time. PLC 208 is configured to send control signals (e.g., digital,
analog, etc.) to
variable frequency drives 18, 28, and 34 via a switch 220. Switch 220 is
configured to route
PLC 208 signals to the appropriate one or more variable frequency drives to
drive the motors and
deliver a generally constant dough pressure for cutting. According to some
exemplary
embodiments, switch 220 may be an Ethernet switch and the control signals may
be sent to
variable frequency drives 18, 28, and 34 with an Ethernet communication
protocol. According
to another exemplary embodiment, the control signal may be a direct analog
control signal that is
readable by PLC 208. According to other exemplary embodiments, the
communication protocol
between PLC 208 and the variable frequency drives may be another serial,
parallel, USB,
Firewire, WiFi, WiMAX, Bluetooth, RF, Control Net, Device Net, Remote 10,
DH485, CAN,
any other wired or wireless protocol, or any protocol capable of facilitating
communication
between PLC 208 and variable frequency drives 18, 28, and 34. In these
exemplary
embodiments, switch 220 may be any appropriate switch capable of routing the
communication
signals.
[0035] PLC 208 may be coupled to a user or operator interface 222 to allow an
operator
to monitor and adjust the machine more easily. Interface 222 may include a
recipe management
system to facilitate the storage of operating variables (e.g., in a memory)
depending on the type
-10-
CA 02680621 2009-09-24
or recipe of dough, including individual PID loops, parameters and allow a
more rapid "one
step" changeover.
[0036] According to some exemplary embodiments, vacuum pump 40 may be placed
in
the auger chamber and auger 14. Vacuum pump 40 is generally configured to
"degas" the dough
or remove air pockets in the dough and assist in dough entering the auger
chamber. Vacuum
pump 40 may be any vacuum pump of past, present, or future design that is
capable of removing
air pockets in dough. It is noted that according to other exemplary
embodiments, vacuum pump
40 may be omitted.
[0037j Referring to FIG. 4, a dough extrusion system 300 similar to system 200
of FIG.
3 is configured to divide dough into discrete sizes or weights, for example
for later packaging,
for baking, etc., according to an exemplary embodiment. Dough extrusion system
300 includes a
second pressure sensor 302 at the output of each metering pump 24 to provide
PLC 208 with a
second pressure reading. The second pressure reading may allow for greater
control over dough
extrusion system and may allow for isolation as to where any variance is
occurring. For
example, PLC 208 may be able to determine whether a variance is primarily due
to the actuation
of auger 14 or due to actuation of metering pump 24.
[0038] Referring to F1G. 5, a method 500 for counteracting variance in dough
pressure
or weight in a dough extrusion system (e.g., dough extrusion system 10, 100,
200, and/or 300) is
shown, according to an exemplary embodiment. Auger 14 of the dough extrusion
system is
actuated by motor 16 or 202 (step 502), transferring dough to metering pump 24
(step 504).
Motor 16 or 202 for actuating the auger is operated to counteract variance in
dough pressure at
metering pump 24 (e.g., before and/or after metering pump 24) (step 506).
According to various
exemplary embodiments, the operation of motor 16 or 202 may be adjusted at
various intervals,
for example at about 1 second intervals, at about 10 second intervals, at
about 100 millisecond
intervals, at about 10 millisecond intervals, etc.
-11-
CA 02680621 2009-09-24
100391 Referring to FIG. 6, a method 600 for counteracting variance in dough
pressure
in a dough extrusion system (e.g., dough extrusion system 10, 100, 200, and/or
300) is shown,
according to another exemplary embodiment. Dough is fed to auger 14 (e.g.,
from hopper 12)
(step 602) and actuation of auger 14 (step 604) transfers the dough to
metering pump 24 (step
606). The system measures the pressure of the dough at the input and/or output
of metering
pump 24 at a predetermined interval (step 608). The speed of one or more
motors in the system
is measured (step 610), for example by encoders or by vector feedback at the
same or a different
predetermined interval as the dough pressure measurement. A controller (e.g.,
PLC 208, PID
loop 38, etc.) determines an appropriate speed or adjustment to the speed for
each of the one or
more motors that may at least partially counteract a measured variance in
dough pressure (step
612), for example motors 16, 26, and 32 or motors 202, 210, and 212. The
system then operates
the one or more motors to be adjusted (e.g., via variable frequency drives) to
counteract the
variance in dough pressure (step 614). It is noted that the actuation of auger
14 a.ndlor metering
pump 24 may be independent of the measuring of dough pressure and motor speed.
100401 The above described dough extrusion systems are configured to reduce
the
variance in dough pressure moving through the system, thereby reducing the
amount of excess or
additional dough included with each dough division according to statistical
models of the
accuracy and precision of the system performance. Specifically, the systems
may compensate
(i.e., counteract, offset, neutralize, balance, make up for, etc.) for a
variance in dough pressure
(e.g., repeating wave pattern) caused by the rotation of the auger 14. For
example, the PLC or
PID loop may detect the pressure variance via the first sensor and/or the
second sensor. The
PLC or PID loop may then adjust one or more of the motors accordingly to
compensate for or
counteract the pressure variance, for example by reading the speed and/or
position of the motor
by reading an encoder and adjusting the phase of the motor to counteract the
phase of the auger.
Because the pressure variance may not perfectly match a mathematical repeating
wave pattern
(e.g., a sinusoidal wave), the PLC or PID loop may use the pressure and
encoder readings to
adjust the motors to compensate for or counteract the variance. Alternatively,
in some
exemplary embodiments, the variance may be very similar to a mathematical
repeating wave
-12-
CA 02680621 2009-09-24
pattern (e.g., a sinusoidal wave) and PLC or PID loop may automatically
execute operations or a
program to cause the motors to compensate for or counteract an expected
mathematical pattern.
[0041] Control of dough metering pump 24 input pressure for divider system 300
and
400 may be accomplished by precise and constant dough material flow from dough
auger 14 to
metering pump 24. By its nature, an auger has a repeating wave pattern
material flow effect and
may even include a portion where reduced or no material flow occurs.
100421 The pressure variance compensation function described above may use a
variety
of control profile technologies to offset the mechanical auger 14 repeating
wave pattern material
flow pattern. The pressure variance compensation hardware may include the use
of
programmable logic controller 208 (e.g., such as commercially available from
AB Control
Logix), a closed loop controller (e.g., a servo controller residing in PLC
208), an AC variable
frequency drive (e.g., variable frequency drive 18, 28, and/or 34), and an AC
asynchronous
motor (e.g., motor 202, 210, 212, and/or a servo motor), for example having an
encoder (e.g.,
encoders 206, 214, 216, and/or a 1024 pulse per revolution quadrature encoder)
and reduction
gearbox (e.g., gearbox 204). According to some exemplary embodiments, the
control profile
technology used may be configured to electronically represent a mechanical cam
or other
modulation effect.
[0043] An additional PID (Proportional, Integral, and Derivative) control loop
located
in PLC 208 may be used to adjust the speed of the control profile to maintain
the output of auger
14 at a generally constant pressure set point. This PID loop uses auger
pressure sensor 36
located at the input of metering pump 24 as the process variable and the
control profile speed as
the control variable.
[0044] Referring to FIG. 7, the control functions are sequenced in
programmable
controller 208 using a method 700. First, PLC 208 sets/initiates the pressure
set point for the
PID, which then defines the speed of auger 14 (step 702). Second, the portion
of auger 14 where
reduced or no material flow occurs is located and controlled. This is
accomplished by actuating
-13-
CA 02680621 2009-09-24
reference proximity switch 219 located on the drive pulley of auger 14 (step
704). Once the
pressure variance compensation function is engaged, proximity switch 219 may
locate the
"home" or reference position dynamically while auger 14 is moving and may
provide the
reference position to the closed loop position controller in PLC 208. Third,
once the reference
position is located, PLC 208 engages the pressure variance compensation
function automatically
and engages a predefined electronic position control profile synchronized to
the reference
position (step 706). This pressure variance compensation function repeats with
every revolution
of auger 14 and drives the speed of the motor in a repeating wave pattern
profile (e.g.,
speed/velocity, etc.) to offset the mechanical effect of auger 14. The
predefined control profile
(e.g., to compensate for a generally sinusoidal or other repeating wave
pattern) may be updated
based on measurements taken by pressure sensor 36 anclior pressure sensor 302.
[0045] By this method, the repeating wave pattern material flow effect may be
offset by
the position controller in PLC 208 and the pressure set point may be attained
by use of the PID
resulting in reduced variation of metering pump 24 input pressure and less
variation in the
material flow to metering pump 24.
[0046] FIG. 8 is an exemplary illustration of a potential improvement in dough
pressure
by implementing encoders and pressure variance compensation. The graph
illustrates a potential
comparison of dough pressures between a system using pressure variance
compensation (e.g.,
system 200, system 300, etc.) and a system not using encoders or pressure
variance
compensation, according to one exemplary embodiment. The system not using
encoders or
pressure variance compensation includes a dough pressure (e.g., as measured by
sensor 36)
having a repeating wave pattern over a number of sample points or for each
revolution of the
screws of auger 14. For example, the dough pressure may vary along a repeating
wave pattern
between about 20 and 90 PSI (per revolution), between about 30 and 80 PSI,
between about 40
and 70 PSI, between about 50 and 60 PSI, between about 53 and 57 PSI, up to
about 65%, up to
about 45%, up to about 27%, up to about 10%, up to about 3.5%, or other
repeating wave pattern
variation.
-14-
CA 02680621 2009-09-24
[0047] The system using encoders or pressure variance compensation generally
has less
variation in dough pressure (e.g., as measured by sensor 36). For example, the
dough pressure
may have a variance of up to about 2%, up to about 1.5 %, up to about 1%, less
than 1%, etc. It
is noted that although specific pressures and pressure variances have been
illustrated, according
to other exemplary embodiments, lower or higher pressures or pressure
variances may be
realized depending on the type of dough and the specific system configuration,
however the
variance is generally decreased in the system compensating for or
counteracting the repeating
wave pattern effects.
100481 FIG. 9 is an exemplary illustration of a potential improvement in dough
weight
distribution by implementing encoders and/or pressure variance compensation.
The graph
illustrates a potential distribution of dough weights for a system using
encoders and pressure
variance compensation (e.g., system 200, system 300, etc.) and a system not
using encoders or
pressure variance compensation, according to one exemplary embodiment. The
system not using
encoders or pressure variance compensation includes a dough pressure (e.g., as
measured by
sensor 36) having a repeating wave pattern over a number of sample points or
revolutions of the
screws of auger 14, as described above. This variation in dough pressure
causes a greater
variation or distribution of dough weights after being cut by knife 30.
Because the system using
encoders and pressure variance compensation generally has less variation in
dough pressure, it
may also allow for less distributed weights of dough pieces closer to a
minimum cut-off weight
("minimum label weight") that is required to meet the weight provided on the
product packaging.
For example, the savings provided by the encoders and the pressure variance
compensation can
be estimated by ( 2
[0049] As illustrated, the system not using encoders or compensating for
repeating
wave pattern effects has a mean dough weight that is higher than the mean
dough weight in a
system that does compensate for the repeating wave pattern effects. Further,
the system not
compensating for repeating wave pattern effects has 1st 2nd, and 3rd sigma or
standard deviation
values that are higher than those of the system that does compensate. By
compensating for or
counteracting repeating wave pattern effects, a lower weight of dough may be
cut-off by knife 30
-15-
CA 02680621 2009-09-24
while still meeting the minimum cut-off weight requirements/goals. Because
less dough is used,
the cost of producing the product may be reduced with the decreased weight,
for example the
cost may be reduced by the difference between ( 2 ¨ I) such as in the example
of FIG. 9.
[0050] It is important to note that the terms "motor," "variable frequency
drive,"
"auger," "knife," and "metering pump" are intended to be broad terms and not
terms of
limitation. These components may be used with any of a variety of dough
products or
arrangements and are not intended to be limited to use with dough
applications. For purposes of
this disclosure, the term "coupled" shall mean the joining of two members
directly or indirectly
to one another. Such joining may be stationary in nature or movable in nature.
Such joining
may be achieved with the two members or the two members and any additional
intermediate
members being integrally formed as a single unitary body with one another or
with the two
members or the two members and any additional intermediate member being
attached to one
another. Such joining may be permanent in nature or alternatively may be
removable or
releasable in nature. Such joining may also relate to mechanical, fluid, or
electrical relationship
between the two components.
[0051] It is also important to note that the construction and arrangement of
the elements
of the dough extrusion system as shown in the preferred and other exemplary
embodiments are
illustrative only. Although only a few embodiments of the present invention
have been
described in detail in this disclosure, those skilled in the art who review
this disclosure will
readily appreciate that many modifications are possible (e.g., variations in
sizes, dimensions,
structures, shapes and proportions of the various elements, values of
parameters, mounting
arrangements, materials, colors, orientations, etc.) without materially
departing from the novel
teachings and advantages of the subject matter recited in the claims. For
example, while the
components of the disclosed embodiments will be illustrated as a system and
process designed
for a dough product, the features of the disclosed embodiments have a much
wider applicability
-16-
CA 02680621 2016-03-23
- the dough extrusion system design is adaptable for other dough products that
are metered
and/or cut. Further, the size of the various components and the size of the
containers can be
widely varied. The scope of the claims should not be limited by the preferred
embodiments set
forth in the examples, but should be given the broadest interpretation
consistent with the
description as a whole. The order or sequence of any process or method steps
may be varied or
re-sequenced according to alternative embodiments. Other substitutions,
modifications, changes
and/or omissions may be made in the design, operating conditions and
arrangement of the
preferred and other exemplary embodiments without departing from the spirit of
the present
invention.
- 17-
