U.S. patent number 3,608,799 [Application Number 04/878,692] was granted by the patent office on 1971-09-28 for print to cut register system.
This patent grant is currently assigned to Zerand Corporation. Invention is credited to Charles R. Edson.
United States Patent |
3,608,799 |
Edson |
September 28, 1971 |
PRINT TO CUT REGISTER SYSTEM
Abstract
A print to cut register system for establishing and maintaining
registration between a pattern on a moving web and a cutting die by
controlling the operative condition of a pair of web feed rolls.
The print to cut register system incorporates an electric signal
means responsive to the output of a registration error detector.
The electric signal means, which may include a computing resolver,
provides an output signal proportional to the alteration in the web
feed rolls necessary to correct the detected registration error.
The electric signal means is connected to electromechanical means
having a servomotor for converting the output signal of the
electric signal means into a corresponding shaft speed and rotary
direction signal. The servomotor shaft speed and rotary direction
signal is amplified by the torque amplifier and provided through a
differential drive means to the feed rolls to correct the
registration error.
Inventors: |
Edson; Charles R. (West Allies,
WI) |
Assignee: |
Zerand Corporation (New Berlin,
WI)
|
Family
ID: |
25372593 |
Appl.
No.: |
04/878,692 |
Filed: |
November 21, 1969 |
Current U.S.
Class: |
226/31 |
Current CPC
Class: |
B65H
23/18 (20130101); B26D 5/24 (20130101) |
Current International
Class: |
B65H
75/24 (20060101); B65H 75/18 (20060101); B26D
5/20 (20060101); B26D 5/24 (20060101); B65H
23/18 (20060101); B65h 023/18 () |
Field of
Search: |
;226/2,30,31,27-29 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Schacher; Richard A.
Claims
I claim:
1. A registration system for providing registration between
successive portions of a moving web and a web-treating apparatus
cyclically applied to each of the web portions, said web-treating
apparatus having controllable metering rolls located upstream along
the web for regulating the length of the web portion provided to
the web treating apparatus during each cycle of operation and the
registration of the portions with the apparatus in accordance with
the rotary condition of the rolls, said web-treating apparatus
further having a registration error detector for detaching the
registration error between the web-treating apparatus and the
successive portions of the web and providing an error signal
accordingly, said web-treating apparatus having a differential
drive means for establishing a rotary condition of the metering
rolls, said registration system comprising:
a signal-converting means having an input responsive to the error
signal of the registration error detector for converting the error
signal into an output signal corresponding to a
registration-correcting alteration in the rotary condition of the
metering rolls;
said registration error detector providing a periodic error signal
in accordance with a predetermined cumulative registration error
occurring over sequential cycles of operation of the web-treating
apparatus and wherein said signal converting means comprises means
for converting the periodic error signal into a continuous output
signal responsive to the occurrence of the error signal,
said signal-converting means also including a signal-generating
means for providing a signal and a signal-altering means cooperable
therewith, said signal-altering means containing said
signal-converting means input and being operable by the error
signal for altering the signal-generating means signal to convert
the error signal into said output signal, said signal-altering
means being electromechanically cooperable with said
signal-generating means and said signal-altering means being
mechanically movable responsive to the error signal for altering
the signal-generating means signal, and
electromechanical means coupled to said signal-converting means and
having a controllable output member responsive to said output
signal, said output member being drivingly connected to the
differential drive means for altering the rotary condition of the
metering rolls to provide registration between the web portions and
the web-treating apparatus.
2. The registration system according to claim 1 wherein said
signal-generating means comprises a secondary circuit inductively
coupled to a primary circuit for providing the output signal in
said secondary circuit, and said signal-altering means comprises
means for varying the inductive coupling between said primary and
secondary circuits by means of mechanical motion.
3. The registration system according to claim 2 wherein said
signal-altering means comprises means for rotating said secondary
circuit with respect to said primary circuit to vary the inductive
coupling between the primary and secondary circuits.
4. The registration system according to claim 3 wherein said
signal-altering means includes means for limiting the relative
rotation of said secondary circuit and the variability of the
inductive coupling to preselected limits.
5. The registration system according to claim 2 wherein said
primary and secondary circuits are inductively coupled through a
movable magnetic core and wherein said signal-altering means
includes means for moving said magnetic core to vary the coupling
between said primary and secondary circuits.
6. The registration system according to claim 1 wherein said
signal-generating means comprises a resistive element having a
wiper providing said output signal and said signal-altering means
comprises means for moving said wiper with respect to said
resistive element.
7. The registration system according to claim 1 including means for
generating an output signal from said signal converting means
independently of the registration error detector error signal.
8. The registration system according to claim 1 including means for
mechanically moving said signal-altering means independently of the
registration error detector error signal.
9. The registration system according to claim 1 wherein said
signal-converting means comprises electronic means for providing a
continuous output signal responsive to the occurrence of the error
signal.
10. The registration system according to claim 1 wherein the
web-treating apparatus includes a registration error detector
providing an additional error signal corresponding to the
registration error existing during each cycle of operation and
wherein said registration system includes a summing means having an
input receiving the additional error signal and said output signal
of said signal-converting means and providing an electric signal
corresponding to the sum of the additional error signal and said
output signal and wherein said electromechanical means is
responsive to said electric signal.
11. The registration system according to claim 10 wherein said
summing means comprises electronic summing means.
12. The registration system according to claim 10 wherein said
summing means comprises means for inductively summing the
additional error signal and said output signal.
13. The registration system according to claim 10 including means
connected to said summing means for altering said summed electric
signal independently of the registration error detector and the
signal converting means.
14. The registration system according to claim 1 wherein said
electromechanical means includes a servomotor having a rotatable
output shaft coupled to the differential drive means, said
servomotor having an energizable electromagnetic circuit
determinative of the rotary condition of said output shaft, said
electromagnetic circuit being energized by the electric signal for
determining the rotary condition of the output shaft.
15. The registration system according to claim 1 wherein said
electromechanical means includes a torque amplifier interposed
between the output shaft of said servomotor and said differential
drive means and containing said output member, said torque
amplifier amplifying the rotary condition of said servomotor output
shaft.
16. The registration system according to claim 15 wherein said
torque amplifier includes a primary power source independent of
said differential drive means.
17. A registration system for providing registration between
successive portions of a moving web and a web-treating apparatus
cyclically applied to each of the web portions, said web-treating
apparatus having controllable metering rolls located upstream along
the web for regulating the length of the web portion provided to
the web-treating apparatus during each cycle of operation and the
registration of the portions with the apparatus in accordance with
the rotary condition of the rolls, said web-treating apparatus
further having a registration error detector for detecting the
registration error between the web-treating apparatus and the
successive portions of the web and providing an error signal
accordingly, said web-treating apparatus having a differential
drive means for establishing a rotary condition of the metering
rolls, said registration system comprising:
a signal-converting means having an input responsive to the error
signal of the registration error detector for converting the error
signal into an output signal corresponding to a registration
correcting alteration in the rotary condition of the metering
rolls; said registration error detector providing a periodic error
signal in accordance with a predetermined cumulative registration
error occurring over sequential cycles of operation of the
web-treating apparatus and wherein said signal-converting means
comprises means for converting the periodic error signal into a
continuous output signal responsive to the occurrence of the error
signal, said signal-converting means includes a signal-generating
means for providing a signal and a signal-altering means cooperable
therewith, said signal-altering means containing said
signal-converting means input and being operable by the error
signal for altering the signal-generating means signal to convert
the error signal into said output signal, a tachometer for
measuring the speed of the moving web and for providing a speed
signal proportional to the speed of the web and wherein said
signal-generating means is energized by the speed signal of said
tachometer, and electromechanical means coupled to said signal
converting means and having a controllable output member responsive
to said output signal, said output member being drivingly connected
to the differential drive means for altering the rotary condition
of the metering rolls to provide registration between the web
portions and the web-treating apparatus.
Description
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to print to cut register systems
suitable for use with web-treating apparatus.
2. Description of the Prior Art
The present invention relates to control apparatus for equipment
which treats a moving web or strip of material. The invention is
more specifically directed to a print to cut register system for
maintaining synchronization between a pattern printed on the web
and a cutter press or punch which forms blanks for cartons and the
like from the printed web. The synchronization of the web pattern
with the operation of the cutter press is often termed
"registration" or "register," the terms being used interchangeably
herein.
Web treating apparatus of the type with which the present invention
is employed may typically include one or more printing sections in
which the desired pattern is placed on the web by rotating
cylindrical printing plates as the web moves continuously through
the printing sections. When a previously printed web is undergoing
treatment, the web-treating apparatus may include an unwind stand
which continuously pays out the web at a constant rate.
The operation of the cutter press requires that the web be
stationary as a reciprocating die portion of the press ascends onto
the web to cut the web and form the blank. For this cutting
operation the web is intermittently fed into the press, held
stationary during the cutting, and then removed from the press. As
can be readily appreciated, the registration or synchronization
which must be maintained between the printed pattern and the
cutting dies, so as to insure, for example, that labels appear in
the proper place on the finished carton blank, is made more
difficult by the intermittent stopping and starting of the web
during the cyclical operation of the cutter press.
To coordinate the operation of the printing section or unwind
stand, through which the web moves continuously, with the cutter
press, through which the web moves intermittently, a pair of
continuously active metering feed rolls are utilized to supply the
web to the cutter press at a precise rate. The web so fed then
passes through a pair of intermittently active feed rolls which
actually place the web fed by the continuously active metering feed
rolls in the cutter press. A brake bar is provided between the
continuously active metering feed rolls and the intermittently
active feed rolls to arrest the travel of the moving web during the
cutting stroke of the press. A slack loop is built up in the web
between the brake bar and the continuously active metering feed
rolls during each stroke of the press. This slack loop is then
taken up by the intermittently active feed rolls during the next
operation of the cutter press. The length of web fed by the
continuously active metering feed rolls into the slack loop during
each stroke or cyclical operation of the press is termed the
"repeat length." The repeat length of the web determines the amount
of material fed into the cutter press during each operation. The
rotary speed of the metering feed rolls, in turn, determines the
amount of web material fed into the slack loop and the repeat
length.
It will be appreciated that as one cycle of operation of the cutter
press may be used to form a blank of any size, the intermittent or
cyclical operation of the cutter press is independent of the size
of the blank being formed so that the operation of the press may
proceed at a uniform repetitive rate. The rotational speed of the
continuously active metering feed rolls, on the other hand, is
directly responsive to the repeat length of the web and the size of
the blank being formed. Hence, the rotational speed of the
continuously active metering feed rolls must vary with the size of
the pattern placed on the web in order to provide the desired
repeat length: for short patterns and repeat lengths the metering
feed rolls turn less for each operation of the press and for long
patterns and repeat lengths the metering feed rolls must turn more.
To accommodate all sizes of patterns and repeat lengths, the
continuously active metering feed rolls must be driven at a
variable speed dependent on the desired repeat length. This
requires the speed of the continuously active metering feed rolls
to be infinitely variable.
The speed of the continuously active metering feed rolls must also
be varied to correct registration errors appearing between the web
pattern and the cutter press die. These registration errors may be
characterized as being of two general types. The first type is a
constant error and occurs when the correct repeat length is being
fed to the cutter press but the position of the pattern with
respect to the cutting die of the press is faulty. For example, a
pattern of the desired repeat length may continually be fed to the
cutting press 0.01 inches short of its desired position. This type
of registration error may hereinafter be termed a position
registration error and is correctable by a momentary increase in
the speed of the continuously active metering feed rolls which
advances the web pattern to the desired position. The second type
of registration error is a cumulative type and occurs when the
repeat length is incorrect. Thus, the repeat length of web provided
to the cutter press may be 0.01 inches shorter than necessary to
provide proper registration. This registration error of 0.01 inch
will appear on the finished blank. On the next operation of the
cutter press, an additional repeat length, also 0.01 inch shorter
than necessary is fed to the cutting press. The registration error
appearing in the finished blank will now be 0.02 inches because of
the two successive operations during which the repeat length of the
web was 0.01 inches too short. On the third operation, the
registration error will total 0.03 inch. It will therefore be
apparent that even small errors in the web repeat length, termed
repeat length errors, will have a deleterious effect on web
registration because of their cumulative effect. Repeat length
errors are correctable by altering the rotary speed of the metering
feed rolls on a continuous basis so as to provide the correct
repeat length of web to the cutter press.
The continuously active metering feed rolls of the web treating
apparatus are generally driven through mechanical linkage from the
crankshaft providing reciprocation to the cutting die of the press
so that the rolls are activated any time the cutter press is
operated. However, as the crankshaft and cutter press operate at a
constant speed, it will be readily appreciated that driving the
metering rolls from this source can provide only uniform speed to
the rolls rather than the desired infinitely variable and
controllable speed.
While a change gearbox may be inserted along the shafting between
the cutter press and the metering rolls, gearing alone cannot
provide infinitely variable and controllable speed to the feed
rolls because of the discrete ratios found in gear drives. Neither
can changing the diameter of the rolls.
While infinitely variable drives, as for example, a
variable-diameter pulley drive may be used, they are subject to
drift, a random change in speed with time, which alters the repeat
length provided by the metering rolls and destroys the desired
registration.
The prior art has been able to overcome the shortcoming of both
gear drives and variable-speed drives and provide a satisfactory
print to cut register system only through the use of a drive system
which is complex, cumbersome, and expensive. This system utilizes
two differentials, a change gearbox, an infinitely variable ratio
drive including the associate ratio regulating apparatus, an
adjusting motor, a hydraulic compensator motor and its solenoid
valve and hydraulic pump, and an electromechanical brake. In such a
system, the cutter press crankshaft is connected through the change
gearbox to one input of one of the differentials. This differential
is generally termed the primary differential. The output shaft of
the primary differential is connected to the continuously active
metering feed rolls. The input of the infinitely variable ratio
drive is connected to a power takeoff on the output shaft of the
primary differential. The output shaft of the variable ratio drive
is connected to one of the inputs of a second differential termed
the secondary differential. By varying the coupling ratio between
the input and output shafts, the drive provides an infinitely
variable ratio range to its output shaft over some definite ratio
range. The infinitely variable ratio drive may typically be of the
variable diameter pulley type having a motor for altering the
diameters of the pulleys and the shaft coupling ratio.
The output shaft of the secondary differential is connected to the
second input of the primary differential. The other input of the
secondary differential is connected to a hydraulic motor.
In operation, the gear ratio of the change gearbox is selected so
that the output shaft of the gearbox drives the metering feed rolls
through the primary differential at a speed which provides, as
closely as possible, the desired repeat length to the web, within
the limits of the available gear ratios in the gearbox. The
variable ratio drive is adjusted to furnish, through the primary
and secondary differentials, the alteration in the metering feed
roll speed necessary to yield precisely the desired repeat length
of web. The aforesaid alteration in metering feed roll speed is
obtained by adjusting the ratio of the output shaft of the variable
ratio drive to a level such that when the drive output shaft speed
is added to, the speed of the output shaft of the primary
differential, a corrective speed increment is applied to the
metering roll speed established by the change gearbox. In this
manner, drift in the variable speed drive causes a negligible speed
variation in the overall speed of the feed rolls because it acts
only on the generally small corrective speed increment provided by
the variable ratio drive.
Under such conditions, if a position registration error appears
between the web pattern and the cutting die, the hydraulic motor is
operated to momentarily alter the speed of the feed rolls through
the primary and secondary differentials to correct this error. The
hydraulic motor thus serves as a position error correcting means.
To correct a position registration error, the coupling ratio of the
variable ratio drive is not altered.
However, if a repeat length error appears in the web-treating
apparatus, the coupling ratio in the variable ratio drive is
readjusted to change the metering feed roll speed in a manner such
as to provide the desired repeat length to the web.
From the foregoing, it is apparent that heretofore available print
to cut register systems, while they have provided reasonably
satisfactory register control, have been exceedingly complex. This
complexity has made them costly to construct and, because of a
propensity to malfunction and break down, costly to both operate
and maintain.
As major components of such prior art systems were driven by the
main mechanical linkage between the cutter press and the
continuously active metering feed rolls, most of the system
elements, of necessity, had to be of a size capable of handling all
the mechanical power transmitted through the main linkage. The
control portions of the system had to be similarly sized so that
the register systems tended to be cumbersome as well as
complex.
Further, such print to cut register systems have been unable to
correct or compensate for known registration errors without
actually operating the cutter press. These known errors, like those
occurring during the normal operation of the cutter press, could
only be removed by actual operation of the press. This has resulted
in wastage of the web material.
SUMMARY OF THE PRESENT INVENTION
It is, therefore, the object of the present invention to provide an
improved print to cut register system suitable for use with
web-treating apparatus.
It is a further object of the present invention to provide such a
print to cut register system which is simple and economical in
construction and operation and which is capable of substantially
trouble-free operation for substantial periods of time.
Another object of the present invention is to provide a print to
cut register system which permits known registration errors
existing in the web-treating apparatus to be corrected or
compensated for prior to operation of the web treating
apparatus.
The simplicity and economy of the print to cut register system of
the present invention, in great measure, may be attributed to the
incorporation of electric signal converting means and signal
summing means in the system. These signal means provide an electric
signal corresponding to the metering feed roll speed alteration
necessary to effect proper registration. Power-amplifying elements
are employed to change the electric signal into a register
correcting speed alteration of the metering feed rolls. In this
manner, the mechanical complexity of prior art print to cut
register systems, driven by the cutter press-- feed roll linkage,
is avoided. At the same time, the use of small, compact electronic
and electromechanical components in regulating the corrective
action of the print to cut register system is permitted.
Briefly, the present invention provides a print to cut register
system for providing registration between successive portions of a
moving web and a web-treating apparatus cyclically applied to each
of the web portions, as for example, to cut a blank from the web.
The web-treating apparatus includes controllable metering rolls
located upstream along the web for regulating the length of the web
portion provided to the web-treating apparatus during each cycle of
operation and the registration of the portions with said apparatus
in accordance with the rotary condition of the metering rolls. The
web-treating apparatus further includes a registration error
detector for detecting the registration error between the
web-treating apparatus and successive portions of the web and
providing an error signal accordingly. A differential drive means
rotates the metering rolls to establish their rotary condition.
The print to cut register system includes a signal-converting means
having an input responsive to the error signal of the registration
error detector for converting the error signal into an output
signal corresponding to a registration correcting alteration in the
rotary condition of the metering rolls. An electromechanical means
having a rotatable output member drivingly coupled to the
differential drive means is included in register system for
altering the rotary condition of the metering rolls in accordance
with the rotary condition of the output member. The
electromechanical means has an input responsive to the output
signal of the signal converting means for altering the rotary
condition of the output member in accordance with the output signal
to provide registration between the web portions and the
web-treating apparatus.
The print to cut register system may also include a summing means
which sums the output signal of the converting means with an
additional error signal produced by the registration error detector
responsive to the registration error existing during each cycle of
operation of the web-treating apparatus so that the alteration of
the metering feed roll rotary condition is responsive to both
signals.
The print to cut register system provides for the correction of
known registration errors by including means for altering the
output signal of the converting means or summing means
independently of the error signals of the registration error
detector.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a somewhat diagrammatic view of a web-treating apparatus
including the print to cut register system of the present
invention, the latter being shown in generalized block diagram
form;
FIG. 2 is a detailed schematic diagram of the print to cut register
system of the present invention;
FIG. 3 is a schematic diagram, similar to FIG. 2, showing the
operation of the print to cut register system of the present
invention in correcting position registration errors;
FIG. 4 is a schematic diagram, similar to FIG. 2, showing the
operation of the print to cut register system of the present
invention in correcting repeat length errors; and
FIGS. 5a, b, c and d are partial schematic diagrams showing other
embodiments of the print to cut register system of the present
invention.
DESCRIPTION OF THE PREFERRED EMBODIMENT
The Web-Treating Apparatus
As shown in FIG. 1, web-treating apparatus 10 includes an unwind
stand 12 on which is placed the web 14 in roll form. It may be
assumed that a pattern 16 has been printed on web 14 by a previous
processing step. Registration marks 18, bearing a fixed locational
relationship to the pattern 16, may also be applied along one edge
of the web.
The web 14 passes from unwind stand 12 to cutter press 22 in the
direction indicated by the arrow in FIG. 1. The web initially
passes through continuously active metering feed rolls 26 and 28.
These continuously active rolls establish the repeat length of the
web by feeding it at a precise rate to the cutter press.
Continuously active feed rolls 26 and 28 are driven by a drive
means, hereinafter described in detail.
The web next passes through a pair of brake bars 30 and 32, the
lower bar 30 of which may be vertically reciprocal for intermittent
clamping engagement with the fixed upper bar 32, to thereby stop
the web when the operation of cutter press 22 occurs and to form a
slack loop 14a in the web. The brake bars then release the web to
permit intermittently active feed rolls 34 and 36 to provide
another repeat length of web 14 to the cutter press.
Cutter press 22 includes an upper, fixed platen 40 and a vertically
reciprocal cutting die 46 which is movable toward and away from
fixed platen 40. Cutting die 46 is reciprocated by connecting rod
48 which is journaled at its upper end on shaft 50 carried by
cutting die 46. The lower end of connecting rod 48 is mounted on
crankshaft 52 driven by an electric motor 54.
Cam shaft 82 which is diagrammatically shown as an extension of
crankshaft 52 operates brake bars 30 and 32 and intermittently
active feed rolls 34 and 36 for shifting the brake bars into
clamping engagement with web 14 and for inactivating intermittently
active feed rolls 34 and 36 during the operation of cutter press
22.
The cut out blanks 16a formed from pattern 16 on web 14 are moved
down chute 44 to storage area 42.
The Register Error Detector
The web-treating apparatus includes a register error detector which
detects both positional registration errors and repeat length
registration errors and provides an output signal responsive to
such errors which may be utilized for operation of the print to cut
register system of the present invention. The position of the web
pattern 16 with respect to the cutter press is ascertained through
the use of register marks 18 on web 14. Photoelectric cell 70 is
positioned a predetermined distance from cutter press 22 and in a
manner such that a passage of a register mark 18 causes
photoelectric cell 70 to generate an output signal in the form of
an electric pulse.
The operative condition of cutter press 22 is sensed by a switch
which is operatively driven by crankshaft 52 and hence coordinated
with the operation of cutter press 22. As typically shown in FIG.
1, a cam 72 is mounted on crankshaft 52 for moving the movable
element 74 of switch 76 as crankshaft 52 rotates to open and close
the switch and provide an output signal therefrom.
In essence, the registration error is detected by a coincidence
detector. The photoelectric cell 70 and switch 76 are operated such
that if the operation of cutter press 22 is in exact
synchronization with the pattern 16 on web 14, so that cutting die
46 engages and cuts web 14 in registration with the pattern,
photoelectric cell 70 and switch 76 will generate signals
simultaneously, or in coincidence. A circuit is provided to detect
this coincidental signal generation, or the lack thereof, if
pattern 16 is out of registration with cutting die 46, and to
provide an output signal accordingly. Additional circuitry is
provided in the register error detector to detect the magnitude of
asynchronous signal generation so as to provide an output signal
indicative of the amount and direction of, as well as the presence
of, registration error.
In a typical register error detector of the type which may be used
with the print to cut register system of the present invention,
photoelectric cell 70 provides an output signal in conductor 80 to
coincidence circuit 81. The application of the photoelectric cell
output signal to the coincidence circuit is controlled by a gate
circuit 82 interposed in conductor 80. This gate circuit, shown
diagrammatically in FIG. 1 as a switch, is controlled by the signal
from switch 76 in conductor 84 so that for a certain time interval
during each cycle of operation of cutter press 22, gate circuit 82
is closed allowing the output signal of photoelectric cell 70 to be
provided to coincidence circuit 81. This time interval is termed
the scanning interval or scanning zone. The signal from switch 76
is also provided through a delay circuit 86, shown diagrammatically
as a capacitor, to pulse generator 88 for causing the pulse
generator to generate a pulse. The delay in the generation of the
pulse by pulse generator 88 effected by delay circuit 86 is such
that the pulse is provided halfway through the scanning zone.
The output signals of gate circuit 82 and pulse generator 88 are
provided to coincidence circuit 81 which ascertains coincidence, or
the lack thereof, between pulse generation by photoelectric cell 70
and by pulse generator 88. As indicated generally above, if the
signal from photoelectric cell 70 and pulse generator 88 are
generated simultaneously, no registration error exists between
pattern 16 on web 14 and cutter press 22. If a registration error
does exist in the cutter press, photoelectric cell 70 will generate
a pulse either before or after the pulse provided by pulse
generator 88. The precedence or sequence of the pulse from
photoelectric cell 70 is taken as an indication of the direction of
the registration error. For example, if the pulse from
photoelectric cell 70 is generated before the pulse from pulse
generator 88, the web is ahead of the desired position due either
to a position registration error or a repeat length error. If the
pulse from photoelectric cell 70 is generated after the pulse from
pulse generator 86, the web is behind the desired position.
The output signal of coincidence circuit 81 in conductor 90, is a
bipolarity, variable duration signal. The polarity of the output
signal is determined by the sequence of generation of the pulses by
photoelectric cell 70 and pulse generator 88, and is thus an
indication of the direction of the registration error. The duration
of the error signal is proportional to the time difference between
the generation of the two pulses and is thus an indication of the
magnitude of the registration error. The output signal in conductor
90 from coincidence circuit 81 is supplied to the print to cut
register system as hereinafter described, in the form of discrete
pulses generated during each operation of the cutter press 22 which
are indicative of the registration error existing in the cutter
press during the immediately previous operation. The pulse signals
control the operation of the print to cut register system to
correct the registration error.
The output signal in conductor 90 is also provided to add/subtract
circuit 92 which may in its simplest form be a capacitor.
Add/subtract circuit 92 serves as an accumulator in that it sums
each of the variable-duration pulse error signals generated in
conductor 90 by coincidence circuit 81, as by adding a proportional
charge to the capacitor. When the sum of a series of sequential
error signals in conductor 90 reaches a predetermined magnitude
(capacitor charge level), the circuit provides an output signal in
conductor 94. This output signal is indicative of the fact that
repetitive registration errors are appearing and that the
additional corrective action by the print to cut register system is
required.
An add/subtract circuit is employed to permit the occurrence of
registration errors in one direction to be offset by the occurrence
of registration errors in the other direction so that the
cumulative error signal must be in a one of the two directions
before an output signal is generated. The output signal from
add/subtract circuit 92 in conductor 94 when the predetermined
cumulative error signal magnitude is reached is a bipolarity pulse
signal of a fixed time duration. The polarity of the output signal
from add/subtract circuit 92 is an indication of the direction of
the cumulative registration error between pattern 16 and cutter
press 22. After generation of an output signal, add/subtract
circuit 92 reverts to its original condition and repeats its
operation.
A register error detector suitable for use with the print to cut
register system of the present invention is made and sold by
Hurletron, Inc., Danville, Ill., under the model designation
222-RB-1 .
The Gearbox and Differential
Crankshaft 52 includes gearing 100 which drives main drive shaft
102. Drive shaft 102 provides power through gearbox 104 to shaft
106. The speed ratio between main drive shaft 102 and shaft 106 may
be altered by the selection of the appropriate gears in gearbox 104
by means of lever 108. Shaft 106 comprises one of the two input
shafts of differential 110. The output shaft 112 of differential
110 is connected through gearing 114 to continuously active
metering feed roll 26. The gear ratio of gearbox 104 is selected so
that, with the second input shaft to differential 110 locked, the
metering feed rolls 26 and 28 are driven at a speed which provides,
as closely as possible within the limits of the gear ratios of
gearbox 104, the correct repeat length to web 14. It will be
appreciated that replacable matched pairs of gears may be used
instead of gearbox 104 to select the gear ratio, if desired.
The second input shaft to differential 110 is used to provide the
alteration in metering feed roll speed necessary to establish and
maintain registration between web pattern 16 and cutting die 46 of
cutter press 22. This second differential input shaft is driven by
the print to cut register system responsive to the output signals
of the register error detector.
The Print to Cut Register System
General
The print to cut register system of the present invention is shown
in block diagram form in FIG. 1 and in detailed schematic form in
FIG. 2.
Conductors 90 and 94 containing the two output signals of the
register error detector are connected to input terminals 120 and
122, respectively, of the print to cut register system. The print
to cut register system includes a signal converting means for
converting the fixed duration pulse signal provided to conductor 94
by add/subtract circuit 92 into a continuous signal having a
magnitude responsive to the number of times such signals are
generated. This means is illustratively shown in FIG. 1 as an
electromechanical resolver 132 having a positioning motor 134 for
adjusting the position of a movable winding in the resolver
responsive to the signal in conductor 133 connected to terminal
122. The inductive coupling between the input and output portions
of the resolver and the output signal in conductor 136 is altered
by adjustment of the movable winding. The output signal of
tachometer 124, responsive to the speed of web 14, is provided,
through amplifier 126, in conductor 128 to input terminal 130 and
through conductor 138 to resolver 132 so that the output of the
resolver is also a function of the speed of the web. In this
manner, when the speed of the web is altered, the operation of the
print to cut register system is correspondingly altered so that the
operation of the register system is coordinated with the speed of
the web at all times. This is commonly termed "tracking."
The system also includes a summation means for summing the
continuous signal generated by the signal-converting means with the
discrete registration error pulse signals in conductor 90, supplied
through an input signal means 160, so as to provide an electric
signal corresponding to the desired alteration in the rotary
condition of the metering feed rolls 26 and 28. This means may
typically be a summing amplifier 140, receiving as inputs, the
signal in conductor 136 from resolver 132 and the signal in
conductor 142 from terminal 120. An output signal corresponding to
the sum of the signals in the aforesaid conductors is provided at
the output of amplifier 140 in conductor 144.
The signal in conductor 144 is provided to a means for converting
the electrical signal into a mechanical shaft speed, and direction
signal. This means may comprise a feedback controlled servo
amplifier 146 connected to conductor 144 and servomotor 148
operated by the servoamplifier.
A torque amplifier 150 is connected to servomotor 148 for
amplifying the shaft speed, position, and rotary direction signal
to a magnitude sufficient to permit its application to the second
input shaft of differential 110 so as to provide a speed alteration
to the metering feed rolls 26 and 28 necessary to correct the
detected registration errors. A typical torque amplifier is the
band and drum clutch assembly shown in FIGS. 1 and 2.
Input Signal Means
Turning now to FIG. 2, the elements of one embodiment of the print
to cut register system are shown in detailed schematic form
therein. For purposes of illustration, an AC coupled system is
shown therein in exemplary fashion.
Input signal means 160 is interposed in conductor 142 between input
terminal 120 and summing means 140 for converting the pulse signals
in conductor 90 into AC signals suitable for operating the print to
cut register system. For this purpose, the input signal means
includes an AC power source comprised of a transformer 162, the
primary winding 164 of which is connected to an alternating current
power supply (not shown) and the secondary winding 166 of which has
a grounded center tap. One end of secondary winding 166 is
connected through parallel relay contacts 168a and 170a to
conductor 142a. The other end of secondary winding 166 is also
connected through parallel relay contacts 172a and 174a to
conductor 142a.
Relay contacts 168a and 172a are operated by relay coils 168b and
172b connected to conductor 142 and energized by the pulse signals
from coincidence circuit 81. Oppositely poled diodes 176 and 178
are connected in series with the relay coils so that a pulse signal
of one polarity from coincidence circuit 81 energizes one of the
relay coils while a pulse signal of the other polarity energizes
the other of the relay coils.
When closed by the energization of relay coil 168b, relay contacts
168a provide an AC signal in conductor 142a having a phase which is
opposite that of the AC signal provided in conductor 142a when
relay contacts 172a are closed by the energization of relay coil
172b, as shown by the AC graphs 176a and b adjacent the opposite
ends of transformer secondary winding 166. Thus, input signal means
160 converts the bipolarity pulse signals in conductor 90 into
corresponding AC pulse signals, the phase of which is controlled by
the polarity of the pulse signals from coincidence circuit 81.
A manual control is included in input signal means 160 to provide
for the generation of signals in conductor 142a independently of
the pulse signals from coincidence circuit 81. This manual control
has a signal source, such as grounded center tap batter 178 having
a manually manipulatable switch 180 connectable to either end of
the battery. The signal from switch 180 is provided in conductor
182 to parallel connected relay coils 170b and 174b for opening and
closing relay contacts 170a and 174a, respectively. Oppositely
poled diodes 184 and 186 inserted in series with the relay coils
causes one polarity of voltage in conductor 182 to energize one of
the relay coils and the other polarity of voltage in conductor 182
to energize the other relay coil. Relay contacts 170a and 174a
provide oppositely phased AC voltages in conductor 142a in a manner
similar to relay contacts 168a and 172a. If desired, the signal
level provided by relay contacts 168a and 172a in conductor 142a
may be rendered different, as by resistors 188 and 190.
As will hereinafter be described in greater detail, signals
generated in conductor 142a by the closure of relay contacts 168a
and 170a serve to advance the position of web pattern 16 with
respect to cutting die 46 so that these relay contacts are given an
advance designation ADV in FIG. 2. Relay contacts 168a are
designated as the automatic advance contacts AUTO ADV, to indicate
that their operation is governed by the operation of the register
error detector in an automatic manner whereas relay contacts 170a
are designed MAN ADV to indicate their operation is manually
controlled by switch 180.
The closure of relay contacts 172a and 174a generate signals which
serve to retard the position of web pattern 16 with respect to
cutting die 46 so that these contacts are designated AUTO RET and
MAN RET, respectively, for reasons analogous to the designation of
contacts 168a and 170a.
Turning now to the other output signal of the register error
detector, that is, the fixed duration pulse output signal in
conductor 94 from add/subtract circuit 92, this signal may be
supplied directly to resolver positioning motor 134 in conductor
133, assuming motor 134 is of a direct current type. If motor 134
is of an alternating current type, an input signal means, similar
to input signal means 160, must be utilized.
A selector switch 200 is interposed in conductor 133 to select
either manual or automatic operation of motor 134. In the automatic
position of selector switch 200, motor 134 is connected directly to
input terminal 122 and its operation is automatically controlled by
the register error detector. In the manual position of selector
switch 200, motor 134 is connected to switch 202 operatively
associated with grounded center tap battery 204 so that motor 134
may be rotated in either direction by manual manipulation of switch
202.
THE COMPUTING RESOLVER
As hereinbefore noted, the signal-converting means incorporated in
the print to cut register system of the present invention for
converting the fixed duration pulse signals of and/subtract circuit
92 into a continuous signal, may comprise a computing resolver. A
resolver is a single phase transformer, the secondary winding of
which is relatively rotatable with respect to the field of the
primary winding. The secondary winding is generally mounted on a
rotor and is movable from a position in which it is in alignment
with the poles of the stator field, and thus has a maximum voltage
induced therein, to a position in which it is across the magnetic
field of the stator and has a minimum voltage induced therein. The
magnitude of the induced voltage is a function of the primary or
stator winding energization, as well as the rotor position, so that
an output voltage or signal taken from the secondary winding is the
function of the two factors. The position of the rotor also
determines the phase relationship of the induced output voltage
with respect to the voltage applied to the primary winding. In the
present print to cut register system, the output voltage of the
resolver is used to provide registration correction in accordance
with both the magnitude and the phase of the resolver output
voltage in a manner hereinafter described.
The computing resolver 132 incorporated in the print to cut
register system of the present invention is shown in diagrammatic
form in FIG. 2 to facilitate the analysis of its operation.
Computing resolver 132 includes a primary or stator winding 206
energized by the signal in conductor 138 from tachometer 124
responsive to the speed of web 14. It will be appreciated that the
primary winding energizing signal from tachometer 124 includes the
alternating circuit bias necessary for the transformer operation of
resolver 132.
The secondary, or rotor, winding 208 of resolver 132 is mounted on
rotor shaft 210 so that the winding may be rotated within the
magnetic field created by stator winding 206 by resolver
positioning motor 134. The winding may be placed on magnetic core
212. A pair of slip rings 214 and 216 are provided on rotor shaft
210 to which the ends of rotor winding 208 are connected and from
which the output signal of computing resolver 132 is taken by
brushes 218 and 220. The output signal from brushes 218 and 220 is
provided in conductor 136.
There are numerous computing resolvers presently on the market
which are suitable for use as resolver 132. For example, the
resolver manufactured by Clifton Precision Products Corporation, 8
Progress Parkway, Maryland Heights, Mo., and sold under the model
designation CSH-15-DS-3, may be used.
Rotor shaft 210 is rotated by resolver positioning motor 134 which
may be any of the various types of commercially available motors
capable of providing closely controlled rotation to rotor shaft
210. A low speed motor, such as a 1 r.p.m. motor is suitable for
use as positioning motor 134.
A pulse signal of one polarity in conductor 133 from add/subtract
circuit 92 causes the motor 134 to turn in one direction, while a
pulse signal of the other polarity causes the motor to turn in the
other direction. As the output signal from add/subtract circuit 92
in conductors 94 and 133 is a pulse signal of fixed duration, motor
134 is likewise rotated a constant amount each time it is
energized. In a similar manner, when selector switch 200 is in the
manual position, motor 134 will be rotated in a direction
determined by the polarity of the signal generated in switch 202
from battery 204. The amount of rotation of motor 134 is determined
by the closure time of switch 202.
When rotor winding 208 is rotated in one direction from the null,
or minimum voltage, position of the rotor winding, an AC signal of
a given phase will be generated in conductor 136. The magnitude of
the AC signal will be proportional to the amount of rotation from
the null position. When the rotor winding is rotated in the other
direction from the null position, an AC signal of the opposite
phase will be generated in conductor 136. The magnitude of this AC
signal will also be proportional to the amount of rotation. One
phase of the AC signal occuring in the print to cut register system
may hereinafter be designated as positive phase while the other,
opposite phase is termed the negative phase, as by reference to the
AC half-cycle which occurs immediately after a time base point.
In order to maintain linearity between the change in position of
secondary winding 208 and the change in magnitude of the output
signal in conductor 136, the rotation of output shaft 210 on either
side of the null, or minimum voltage, position of the rotor winding
208 with respect to stator winding 206 may be limited. For this
purpose, a cam 222 is mounted on rotor shaft 210 for actuating
limit switches 224 and 226 to shut down motor 134, as by opening
switch 228 when the predetermined limits of rotation are reached.
It has been found that sufficient linearity or proportionality
between the change in position of rotor winding 208 and the output
signal in conductor 136 may be obtained by limiting the rotation of
rotor shaft 210 to between 30.degree. and 60.degree. on either side
of the null position of rotor winding 208.
To ascertain the rotary position of rotor core 212 and secondary
winding 208 with respect to the magnetic field of primary winding
206, an indicator disc 211 may be provided on rotor shaft 210. Disc
211 has a scale 213 which cooperates with index line 215 for
locating the resolver rotor. Scale 213 and index line 215 are
located so that a reading of zero is obtained when the rotor
winding 208 is in the null position. Scale 213 may be calibrated on
either side of the zero position in inches of increase or decrease
in the repeat length of web 14 obtained by altering the position of
secondary winding 208. This allows the position of secondary
winding 208 to be preset prior to the operation of web-treating
apparatus 10 so as to compensate for known repeat length errors, in
a manner hereinafter described.
As a result of the above-described interconnection and operation of
resolver 132, a continuous AC output signal is generated in
secondary winding 208 and conductor 136, the magnitude of which is
a function both of the speed of web 14, because of the energization
of the primary winding 206 by tachometer 124, and the output signal
of the register error detector in conductor 90 from add/subtract
circuit 92, because of the rotation of secondary winding 208
responsive to this latter signal. The phase of the continuous AC
output signal is a function of the direction of rotation of rotor
winding 208 from the null position and therefore a function of the
polarity of the output signal of the register error detector in
conductor 94.
The Summing Means
The signal from resolver secondary winding 208 in conductor 136 and
the signal from coincidence circuit 81 in conductor 142 are
supplied to the input of a summing means, capable of summing the
biphase AC signals existing in the conductors. This may, for
example, be operational amplifier 140. An output signal
corresponding to the sum of the signals in the aforesaid conductors
is provided at the output of amplifier 140 in conductor 144. The
output signal is an AC signal, the magnitude and phase of which is
a function of the relative magnitudes and phases of the AC input
signals in conductors 136 and 142a. Input signals of similar phases
are added while input signals of different phases are subtracted.
The output signal corresponds to the alteration to be effected in
the rotary condition of the metering feed rolls 26 and 28 by the
print to cut register system to correct the registration error
between web pattern 16 and cutting die 46.
The Servomotor
The output signal in conductor 144 is provided to servo amplifier
146 and thence to servomotor 148 by means of conductor 230.
Servomotor 148 converts the output signal of amplifier 140 into the
shaft speed and rotary direction signal necessary to actually
effect the desired alteration in the rotary condition of metering
feed rolls 26 and 28. The servomotor shaft signal is amplified, as
hereinafter described, and applied to the metering feed rolls to
effect the required correction.
Servomotor 148 may be of the type having a pair of electrically
displaced stator windings 232 and 234. One of the stator windings
234 may be biased with alternating current from source 236 to
create a magnetic field in the servomotor. The other stator winding
232 may be energized by the output signal in conductor 230 from
amplifier 146, so as to create a revolving magnetic field in the
servomotor to cause the motor to rotate in accordance with the
energization of stator winding 232. The direction in which the
output shaft 238 of servomotor 148 will rotate is determined by the
phase of the output signals in conductor 230, the speed at which it
rotates depends on the magnitude of the output signal, and the
amount by which it rotates depends on the duration of the output
signal. A tachometer 240 on the output shaft 238 of servomotor 148
provides a feedback signal to servo amplifier 146 to insure that
the output of servomotor 148 corresponds to the input signal from
amplifier 146.
Torque Amplifier
The output signal from servomotor 148 is provided to a torque
amplifier 150 which amplifies the shaft speed and rotary direction
signal to a magnitude sufficient to permit its application to the
second input of differential 110 so as to provide a speed
correction to metering feed rolls 26 and 28.
Numerous mechanical or electromechanical devices may be used as
torque amplifier 150. One such device is the band and drum clutch
assembly shown diagrammatically in FIGS. 1 and 2. A principal power
source is provided for torque amplifier 150 in the form of a motor
242. The application of the power of motor 242 to output shaft 244
of torque amplifier 150 is controlled by the output shaft of
servomotor 148, thereby achieving the described torque
amplification. Motor 242 drives input shaft 246 of torque amplifier
150 which in turn drives a pair of drums 248 and 250 in opposite
directions through gearing 252.
A spiral, or helical, band surrounds each of the drums.
Specifically, band 254 surrounds drum 248 while band 256 surrounds
drum 250. One end of each of the bands is connected through gearing
258 to output shaft 244. The other end of the bands is connected to
gearing 260 which is coupled to output shaft 238 of servomotor 148
in a manner such that rotation of the output shaft of servomotor
148 serves to tighten one or the other of the bands onto the
respective drum so as to couple output shaft 244 to one of the
drums driven by input shaft 246. The direction in which the
servomotor output shaft 238 rotates determines which of the drums
will be coupled to the output shaft and the direction of rotation
of output shaft 244. The speed at which the servomotor output shaft
238 rotates determines the amount of the clutching action between
the band and the drum and thus the speed of output shaft 244. In
this manner the speed and direction characteristics of the output
shaft 238 of servomotor 148 undergo a power magnification.
The output shaft 244 of torque amplifier 150 comprises the second
input of differential 110.
A torque amplifier of the general type described above is made and
sold by the Seneca Falls Machine Company, Seneca Falls, N.Y., under
the description Mechanical Power Amplifier and model designation
Mark IV or V. See also U.S. Pat. No. 3,187,599 to Eisengrein, et
al., assigned to the aforementioned Seneca Falls Machine
Company.
Operation of Web-Treating Apparatus
In considering the general operation of web-treating apparatus 10,
it may be assumed that web 14 is being reeled off unwind stand 12
at a relatively uniform rate by an unwind stand drive mechanism or
drive rolls (not shown). The web passes through continuously active
metering feed rolls 26 and 28 which, in turn, meter the web to
cutting press 22 at a precise rate.
During each cycle of operation of cutter press 22, as cutting die
46 moves away from platen 40, brake bars 30 and 32 release web 14.
At the same time intermittently active feed rolls 34 and 36 engage
web 14 to move the entire slack loop 14a of the web into the cutter
press. As cutting die 46 again moves toward platen 40, brake bars
30 and 32 reengage the web and intermittently active feed rolls
disengage the web so that the portion of the web in the press is
stationary as cutting die 46 cuts the web against platen 40.
Continuously active feed rolls 26 and 28 reform the slack loop 14by
feeding an additional repeat length of web material into the loop
during the time brake bars 30 and 32 engage web 14.
Operation of the Print to Cut Register System
Turning now to a consideration of the print to cut register system
of the present invention, it may be further assumed that during the
immediately preceding operative cycles of cutter press 22, no
register error has been detected between web pattern 16 and cutting
die 46. Metering rolls 26 and 28 are driven by gearbox 104 and
differential 110 at a speed which feeds, as closely as possible,
within the gear ratios of gearbox 104, the desired repeat length
into slack loop 14a during each operation of cutter press 22.
As no registration error exists between pattern 16 on web 14 and
cutter press 22, none will be detected by the registration error
detector. The pulse generated by photoelectric cell 70 and the
pulse generated by pulse generator 88 will arrive at coincidence
circuit 81 coincidentally. Because of the synchronism in pulse
generation, no output signal will be provided in conductors 90 and
94 which would alter the operation of the print to cut register
system.
Tachometer 124 energizes primary winding 206 of resolver 132 with a
signal proportional to the speed of web 14. The secondary winding
208 of resolver 132 remains in the position, with respect to the
magnetic field of energized primary winding 206, established by the
previous operations of the print to cut register system. A
continuous signal is therefore generated in conductor 136, the
magnitude of which is a function of the speed of web 14, through
the energization of primary winding 206, and the relative position
of secondary winding 208 with respect to the magnetic field of the
primary winding. The phase of this signal is also a function of the
relative position of secondary winding 208 with respect to the
magnetic field of the primary winding and specifically the
direction of rotation of the secondary winding from the null
position. The signal in conductor 136 is shown by the graph 306 in
FIG. 2 as a positive phase signal.
The continuous signal in conductor 136 is provided to summing
amplifier 140. As the register error detector is in the quiescent
state, no signal is generated in conductor 90 and none is supplied
via conductors 142 and 142a, to summing amplifier 140 so that the
signal in conductor 136 from computing resolver 132 is the only
signal received by summing amplifier 140. The output signal of
summing amplifier 140 in conductor 144 is therefore an AC signal
proportional in magnitude, and corresponding in phase to the signal
in conductor 136 and is designated by the same graph and
number.
The output signal of summing amplifier 140 is provided to
servomotor 148, through servoamplifier 146, to energize stator
winding 232 of the servomotor to cause servomotor output shaft 238
to rotate in a direction and at a speed determined by the phase and
magnitude, respectively, of the output signal 306 of summing
amplifier 140.
The shaft speed and direction signal of servomotor 148 is supplied
to torque amplifier 150 through gearing 260 which causes one of the
bands of torque amplifier 150 to tighten on one of the drums,
thereby to drive output shaft 244 at a speed and in a direction
similar to the speed and direction of servomotor output shaft
238.
Output shaft 244 of torque amplifier 150 is connected to the second
input of differential 110 so that the rotary speed condition of
continuously active metering feed rolls 26 and 28 is a summation of
the speed of shaft 106 from gearbox 104 and the speed of output
shaft 244 of the torque amplifier 150 in the print to cut register
system. The speed of shaft 244 may be either additive or
subtractive of the speed of shaft 106 in determining the speed of
metering rolls 26 and 28, depending on the relative directions of
rotation of the two shafts. In the present exemplary case, it will
be assumed that the speed of shaft 244 is additive to the speed of
shaft 106 so that the summed total of the speeds of the two shafts
is such as to rotate continuously active metering feed rolls 26 and
28 at a speed which maintains the registration between web pattern
16 and cutter press 22.
It is theoretically possible to drive metering feed rolls 26 and 28
solely by means of gearbox 104 at a speed sufficient to maintain
registration, as by selecting gear ratios for gearbox 104 and roll
diameters for metering feed rolls 26 and 28 which will meter
exactly the right repeat length of web 14 into the slack loop 14a
during each operation of the cutter press 22. However, as a
practical matter this is difficult, if not impossible. Due to
slippage between the web and the rolls, stretching of the web, and
the like, registration errors inevitably occur no matter how
carefully the gear ratios and roll diameters are selected. These
errors necessitate almost continual utilization of the print to cut
register system to maintain registration and the web-treating
apparatus 10 has been so described, supra.
When a registration error does appear in the position of pattern 16
with respect to cutting die 46, of either the positional type or
repeat length type, during any given operative cycle of cutter
press 22, the following occurs. The registration error detector
detects the registration error and an output signal is provided in
conductor 90 to terminal 120 of the print to cut register system.
The time length or duration signal is proportional to the magnitude
of the registration error and the polarity of the signal is in
accordance with the direction of the sensed registration error. In
an exemplary case, the registration error detector may ascertain
that the pattern 16 on web 14 is ahead of the desired position,
with respect to cutting die 46 by 0.1 inch and provide a signal of
negative polarity for 0.1 seconds in conductor 90. This signal is
diagrammatically shown in FIG. 3 by the graph 302. It may also be
assumed that the accumulated error must total 0.5 inch in one
direction before an output signal is provided from add/subtract
circuit 92 in conductor 94. Thus, at the present time, no output
signal is provided in conductor 94.
The signal 302 in conductor 90 is supplied through terminal 120 to
conductor 142 to energize input signal means 160. Signal 202, being
of the negative polarity, energizes relay coil 172b to close relay
contacts 172a, as shown in FIG. 3, and generate an AC signal 304 in
conductor 142a from transformer secondary winding 166. The AC
signal 304 is generated for the 0.1 second that signal 302 in
conductor 142 from coincidence circuit 81 energizes relay coil
172b. The phase of signal 304 is negative, which is indicative of
the fact that signal 302 is of a negative polarity. Signal 304 is
supplied to the input of summing amplifier 140 in conductor
142a.
As no signal is provided in conductor 94 the operation of resolver
132 is not altered from that obtained during the previous operation
of cutter press 22 during which no registration error was detected.
Positive phase signal 306 continues to be generated in conductor
136. As noted supra, the magnitude of signal 306 is a function of
the speed of web 14 and the position of rotor secondary winding 208
and the phase of signal 306 is a function of the direction of
rotation of rotor winding 208 with respect to the null position of
the winding. Signal 306 is supplied by conductor 136 to the input
of summing amplifier 140.
Summing amplifier 140 sums input signal 304 in conductor 142a and
input signal 306 in conductor 136 and provides an output signal
accordingly. As the phases of signals 304 and 306 are opposite,
signal 304 will be subtracted from signal 306 to produce signal 308
in conductor 144. As noted from FIG. 3, signal 308 includes reduced
signal portion 308a, the magnitude of which represents the
difference in magnitudes between signal 306 and 304. Signal 308a
corresponds to the reduction in the rotary speed of continuously
active metering feed rolls which must be made to move web pattern
16 backward with respect cutting die 46 and into registration with
the die.
Signal 308 is applied to servomotor 148, through servoamplifier
146, to reduce the speed of servomotor output shaft 238 in
accordance with reduced signal portion 308a; that is, to reduce the
speed of servomotor output shaft 238 in proportion to the reduced
magnitude of signal portion 308a and for the 0.1 second time
interval during which signal portion 308a is formed by the
subtraction of signal 304 from signal 306.
The reduction in the speed of servomotor output shaft 238 reduces
the speed of torque amplifier output shaft 244 by a like amount and
for a like time interval. This reduces the speed of continuously
active metering feed rolls 26 and 28 correspondingly through
differential 110 so as to decrease the length of web 14 supplied to
slack loop 14a by the metering rolls preparatory to the next
operative cycle of cutter press 22.
It may well be that the reduced length of material in slack loop
14a which is supplied to cutter press 22 during the next cycle of
operation will be such as to move the web pattern rearward to a
position in which it is in exact registration with cutting die 46.
This is often the case when the registration error is of the
positional type. If registration is obtained, the registration
error detector ascertains the condition of registration and no
output signal is provided in conductor 90 during the subsequent
operations of cutter press 22. The signal recorded in add/subtract
counter 92 remains entered there, however.
In many cases, a registration error will still remain between
pattern 16 on web 14 and cutting die 46 of cutter press 22. This
may occur when the registration error is of the repeat length type.
For example, the repeat length of web supplied by metering rolls 26
and 28 when driven by gearbox 104 alone, may be 0.1 inch too great.
Thus, while the positional pattern of web 14 will be moved 0.1 inch
rearwardly by the reduced repeat length of web 14 supplied by the
above described operation of the print to cut register system, the
excessive repeat length reinserts the same registration error on
the subsequent cycle of operation of cutter press 22. The
registration error detector detects the same 0.1-inch error and the
print to cut register system provides the same rotary condition
correction to feed rolls 26 and 28. The additional 0.1-inch
correction is noted by add/subtract counter 92 and added to the 0.1
inch recorded therein from the previous operation.
If the registration error is due to improper repeat lengths
resulting from the inability of gearbox 104 and the print to cut
register system to drive feed rolls 26 and 28 at the precise speed
needed to provide the correct repeat length in slack loop 14a, a
registration error will continue to appear during each cycle of
operation of cutter press 22. In the present exemplary instance,
when the cutter press has operated five times with the registration
error of 0.1 inch, a total of 0.5 -inch error will have been
accumulated in add/subtract counter 92. At this point, add/subtract
counter 92 has reached its preset maximum of 0.5 inch of
registration error and provides an output signal 310 of a
predetermined duration in conductor 94 as shown in FIG. 4. For
example, the duration of signal 310 may be 0.3 seconds. The
polarity of signal 310 is negative as the accumulated error is the
sum of a series of errors in which the web pattern 14 is ahead of
the desired position with respect to cutting die 46.
Signal 310 is provided through conductor 94 to input terminal 122
of the print to cut register system and to conductor 133. Assuming
selector switch 200 is in the automatic position, the signal in
conductor 133 is supplied to resolver-positioning motor 134,
energizing the motor to rotate resolver shaft 210 and secondary
winding 208. In the present example, motor 134 will move secondary
winding 208 toward the null position so as to provide a reduced
continuous output signal 312 in conductor 136. Because of the
linearity or proportionality between the rotor winding position and
the induced voltage in the rotor winding 208, the change in the
output signal of resolver 132 in conductor 136 is proportional to
the amount of displacement of rotor winding 208.
Reduced output signal 312 is provided to summing amplifier 140 and
to servomotor 148 to reduce the speed of servomotor output shaft
238 on a continuous basis to a lower level. The reduction in speed
of output shaft 238 causes a corresponding reduction in the speed
of torque amplifier output shaft 244 and in the speed of
continuously active metering feed rolls 26 and 28. The reduction in
the speed of the continuously active metering feed rolls decreases
the repeat length 14a of the web 14 and serves to move web pattern
16 rearwardly with respect to cutting die 46 and into registration
with the cutting die for all succeeding operations of cutter press
22. As registration errors reoccur in web-treating apparatus 10
they are corrected in the same manner as described above.
From the foregoing, it will be readily appreciated that
registration errors caused by the position of web pattern 16 being
behind the position necessary for registration with cutting die 46,
rather than ahead of such a position as in the examples above, are
corrected by increasing the speed of feed rolls 26 and 28, and the
repeat length of web 14, either for a single operation of cutter
press 22 responsive to a signal from coincidence circuit 81 or
continuously responsive to a signal from add/subtract circuit
92.
It will be further appreciated that, in instances in which the
registration errors are occurring at random, that is, first in one
relative direction of web pattern 16 with respect to cutting die 46
and then in the other relative direction, errors in one direction
are subtracted from errors in the other direction in add/subtract
counter 92 so as to insure that only when the registration error
repeatedly occurs in the one direction is an output signal provided
in conductor 94.
In the event the repetitive operation of cutter press 22 is speeded
up, continuously active metering feed rolls 26 and 28 will be
driven faster by gearing 100 connected to crankshaft 52, gearbox
104, and differential 110 so as to supply the same repeat length of
web 14 to slack loop 14a during each cycle of operation even though
a shorter time interval is available for so doing.
The corrections for registration errors made by print to cut
register system 10 must also be made more rapidly under such
conditions because of the shortened time interval. As the operation
of cutter press 22 is increased, the line speed of web 14 is
likewise increased. This causes tachometer 124 to provide an
increased output signal through amplifier 126 and conductors 128
and 138 to resolver primary winding 206 so as to correspondingly
increase the magnitude of any output signal induced in resolver
secondary winding 208 and provide more rapid correction through
servomotor 148 and torque amplifier 150 for registration errors
appearing between pattern 16 and cutting die 46.
In many cases, the magnitude of expected registration errors may be
determined to a greater or lesser extent prior to the operation of
cutter press 22. It is therefore desirable to correct the
registration errors before cutter press 22 is run to lessen wastage
of the web due to incorrect registration.
For example, if it is clearly evident that the repeat length of web
14 provided by continuously active metering feed rolls when rotated
through differential 110 by gearbox 104 alone is 0.1 inch longer
than the length required for registration, selector switch 200 may
be switched to the manual position. Switch 202 is then manipulated
to provide a signal from battery 204 to resolver positioning motor
134 to rotate resolver rotor winding 208. Through the operation of
the print to cut register system, this will alter the speed and
rotary direction of output shaft 244 of torque amplifier 150 so as
to reduce the speed of feed rolls 26 and 28 by the amount necessary
to reduce the repeat length of the web 0.1 inch to the proper
length.
As noted supra, because of the proportionality maintained between
changes in the position of rotor winding 208 and changes in the
magnitude of the resolver output in conductor 136, disc 211 which
indicates the rotary position of resolver secondary winding 208 may
be calibrated directly in inches of increase or decrease in the
repeat length of web 14 obtained by altering the position of
secondary winding 208. Similarly, if it is evident that, while the
web repeat length is correct, the position of pattern 16, with
respect to cutting die 46, is incorrect, the switch 180 in input
signal means 160 may be manipulated to energize one of relay coils
170b or l74b to close relay contacts 170a or 174a to generate a
signal in conductor 142a. The signal provided to summing amplifier
140 from input signal means 160 under such conditions operates the
print to cut register system in a manner similar to a signal from
coincidence circuit 81 produced during actual operation of cutter
press 22 to alter the position of web pattern 16 with respect to
cutting die 46.
Other Embodiments
Other forms and embodiments of the print to cut register system
described above may be devised. For example, rotary transformer or
resolver 132 may be replaced by a linear transformer 132a shown in
FIG. 5A. Such linear transformers typically have the primary
winding 206a and secondary winding 208a thereof coupled through a
rectilinearly movable core 209 so that by moving the core the
coupling is varied. The core may be moved by a lead screw mechanism
231 connected to motor 134.
If it is desired to use direct current control signals, rather than
AC signals in the print to cut register system of the present
invention, a slide wire resistor arrangement 132b may be utilized
in which the resistive element or wire 206b is energized by a
direct current tachometer 124a responsive to web speed. The
resistor slide 208b, from which the output signal for conductor 136
is taken, is driven by motor 134 through a leadscrew arrangement
231a. See FIG. 5B.
If it is desired to avoid the use of electromechanical devices, a
step function generator 132c as shown in FIG. 5C may be utilized.
Such a function generator provides a plurality of output signal
levels responsive to a series of input signals. The output signal
levels may be either AC or DC as desired. The polarity of the input
signals and of the output signal level may correspond. As the
number of input signals of a given polarity received by function
generator 132c increases, the output signal level also
increases.
In the present print to cut register system such a function
generator may be employed to provide an increasing output signal
level 316 in conductor 136 as the number of output signals 310 of a
given polarity from add/subtract circuit 92 increases. Subsequently
received output signals from add/subtract circuit 92 of the other
polarity would reduce the signal level or reverse its polarity if
they exceeded, in number, the number of output signals of the given
polarity.
Tachometer 124 may also be connected to function generator 132c by
conductor 138 to uniformly increase all the output signal levels as
the speed of the web increases. Coincidence circuit 81 may also be
connected to the function generator by conductor 142a to
momentarily alter the signal level responsive to the coincidence
circuit output signals thus combining the converting and summing
means.
The converting means and summing means may also be combined, in
resolver 132d shown in FIG. 5D, through the use of an additional
primary winding 206c. This winding is mounted on rotor core 212 and
energized through brushes 225 and 227 and collector rings 219 and
221 with the signal in conductor 142a from coincidence circuit 81.
The signal from coincidence circuit 81 would then be
electromagnetically added to the signal induced in secondary
winding 208 by the energization of primary winding 206 and the
relative position of the rotor winding with respect to the stator
field and provided in conductor 136 directly to servoamplifier
146.
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