U.S. patent number 3,887,122 [Application Number 05/320,272] was granted by the patent office on 1975-06-03 for press feeder control apparatus.
This patent grant is currently assigned to Hyper-Loop, Inc.. Invention is credited to Marcel R. Sommeria.
United States Patent |
3,887,122 |
Sommeria |
June 3, 1975 |
Press feeder control apparatus
Abstract
In a press feeder control a main counter is provided for
initially manifesting a quantity representative of the distance
travelled by a web as it is drawn into position in relation to a
press, and decremented in response to each incremental movement of
such web, so that it is decreased to zero as the web is moved to
the proper position. The drive of the web is controlled to
accelerate the web at a preselected rate until a preselected
velocity is obtained, and to decelerate the web at the same
preselected rate so as to bring the web to the desired position as
the velocity of the web is reduced to zero. Means is provided for
selectively driving the out-feed drive at a faster rate than the
in-feed drive, to stretch the web in the vicinty of the press.
Inventors: |
Sommeria; Marcel R. (Palos
Heights, IL) |
Assignee: |
Hyper-Loop, Inc. (Bridgeview,
IL)
|
Family
ID: |
23245651 |
Appl.
No.: |
05/320,272 |
Filed: |
January 2, 1973 |
Current U.S.
Class: |
226/136; 318/603;
318/696; 226/139; 318/685 |
Current CPC
Class: |
G05B
19/231 (20130101); G05B 2219/43006 (20130101) |
Current International
Class: |
G05B
19/19 (20060101); G05B 19/23 (20060101); B65h
017/22 () |
Field of
Search: |
;226/134,136,137,139,33,43 ;318/696,685,600,601,603 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Schacher; Richard A.
Attorney, Agent or Firm: Hill, Gross, Simpson, Van Santen,
Steadman, Chiara & Simpson
Claims
What is claimed is:
1. In apparatus for controlling the movement of a member from a
first position to a second position including drive means operable
in response to a train of pulses having a separate pulse for each
increment of movement of said member, the combination comprising: a
main counter, means presetting said main counter to manifest a
quantity proportional to the distance between said first and second
positions, generating means for generating a pulse train having a
manually adjustable pulse repetition rate, means for connecting
said pulse train to said main counter for decrementing said counter
with each pulse of said pulse train, and means adapted for
connecting said pulse train with said drive means, said generating
means including means for varying the pulse repetition rate of said
pulse train, decreasing said pulse repetition rate to substantially
zero when said member reaches said second position.
2. Apparatus according to claim 1 wherein said generating means
includes means for increasing the pulse repetition rate of said
pulse train from zero to maximum value as said member moves from
said first position, and means for decreasing said pulse repetition
rate from said maximum value to zero as said member reaches said
second position, the rate of decrease of the pulse repetition rate
being equal to the rate of increase of the pulse repetition
rate.
3. Apparatus according to claim 2 including a second counter, means
for connecting said pulse train to said second counter during the
period in which the pulse repetition rate of said pulse train is
increasing to a maximum value, and thereafter manifesting the
number of pulses counted by said second counter while said pulse
repetition rate is maintained at said maximum value.
4. Apparatus according to claim 3 including a comparator connected
to said main counter and to said second counter and responsive to a
coincidence between the content of said main counter and said
second counter to produce an output signal, and means connected to
said comparator and responsive to said output signal for intiating
a decrease in the pulse repetition rate of said pulse train.
5. Apparatus according to claim 1 including connecting means for
interconnecting said train of pulses with said drive means, said
connecting means being adapted to selectively insert additional
pulses into said pulse train.
6. Apparatus according to claim 5 including manually operable means
for selecting the frequency of pulses inserted into said pulse
train.
7. In apparatus for controlling the movement of a member from a
first position to a second position including drive means operable
in response to a train of pulses having a separate pulse for each
increment of movement of said member, the combination comprising: a
main counter, means presetting said main counter to manifest a
quantity proportional to the distance between said first and second
positions, generating means for generating a pulse train, means for
connecting said pulse train to said main counter for decrementing
said counter with each pulse of said pulse train, means adapted for
connecting said pulse train with said drive means, said generating
means including means for varying the pulse repetition rate of said
pulse train, increasing said pulse repetition rate from zero to a
maximum value as said member moves from said first position, and
decreasing said pulse repetition rate from said maximum value to
zero as said member reaches said second position, the rate of
decrease of said pulse repetition rate being equal to the rate of
increase of said pulse repetition rate, a second counter, means for
connecting said pulse train to said second counter during the
period in which the pulse repetition rate of said pulse train is
increasing to a maximum value, and thereafter manifesting the
number of pulses counted by said second counter while pulse
repetition rate is maintained at said maximum value, a comparator
connected to said main counter and to second counter and responsive
to a coincidence between the content of said main counter and said
second counter to produce an output signal, means connected to said
comparator and responsive to said output signal for initiating a
decrease in the pulse repetition rate of said pulse train, a third
counter, means for generating said pulse train having a pulse
repetition rate proportional to the product of the content of said
third counter and the pulse repetition rate of an input pulse
train, means for increasing the content of said third counter as
said member is moved from said first position, and means for
decreasing the content of said third counter in response to the
output signal from said comparator unit.
8. Apparatus according to claim 7 including a source of clock
pulses, and adjustable means having a storage device, said
adjustable means being connected to said source of clock pulses and
adapted to produce a train of pulses having a pulse repetition rate
proportional to the product of the pulse repetition rate of said
clock pulse source and a quantity manifested in said storage
device, and means for connecting said adjustable means with said
second counter.
9. Apparatus according to claim 7 including a source of clock
pulses, adjustable means having a storage device, said adjustable
means being connected with said source of clock pulses and adapted
to produce an output pulse train having a pulse repetition rate
proportional to the product of the pulse repetition rate of said
clock pulse source and a quantity means to said third counter for
incrementing said counter from zero to a maximum value in response
to each of the pulses produced by said adjustable means.
10. Apparatus according to claim 7 including means for increasing
the content of said third counter at a uniform rate until a maximum
content is reached, and means causing said third counter to
manifest the number of pulses applied thereto during the period of
increase of the pulse repetition rate of said pulse train.
11. In apparatus for controlling the movement of a member from a
first position to a second position including drive means operable
in response to a train of pulses having a separate pulse for each
increment of movement of said member, the combination comprising: a
main counter, means presetting said main counter to manifest a
quantity proportional to the distance between said first and second
positions, generating means for generating a pulse train, means
adapted for simultaneously connecting each pulse of said pulse
train to said main counter for decrementing said counter and to
said drive means for moving said member, said generator means
including means for varying the pulse repetition rate of said pulse
train, increasing said pulse repetition rate as the first pulses of
said pulse train are applied simultaneously to said main counter
and to said drive means, and decreasing said pulse repetition rate
to substantially zero when said member reaches said second
position.
12. In apparatus for controlling the movement of the member from a
first position to a second position including drive means operable
in response to a train of pulses having a separate pulse for each
increment of movement of said member, the combination comprising: a
main counter, means presetting said main counter to manifest a
quantity proportional to the distance between said first and second
positions, generating means for generating a pulse train, means for
connecting said pulse train to said main counter for decrementing
said counter with each pulse of said pulse train, means adapted for
connecting said pulse train with said drive means, said generating
means including means for varying the pulse repetition rate of said
pulse train for the first group of pulses applied to said drive
means as said member moves away from said first position and for
decreasing said pulse repetition rate to substantially zero when
said member reaches said second position and for maintaining said
pulse repetition rate at a constant value between said first group
of pulses and the period of decreasing pulse repetition rate, and
manually operable means for selecting the value of said constant
pulse repetition rate.
13. Apparatus according to claim 12, including manually operable
means for selecting the length of the periods over which said pulse
repetition rate is increasing and decreasing.
14. In apparatus for controlling the movement of a member from a
first position to a second position including drive means operable
in response to a train of pulses having a separate pulse for each
increment of movement of said member, the combination comprising: a
main counter, means presetting said main counter to manifest a
quantity proportional to the distance between said first and second
positions, generating means for generating a pulse train, means for
connecting said pulse train to said main counter for decrementing
said counter with each pulse of said pulse train, and means adapted
for connecting said pulse train with said drive means, said
generating means including means for linearly varying the pulse
repetition rate of said pulse train, decreasing said pulse
repetition rate to substantially zero when said member reaches said
second position.
Description
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to control apparatus for a punch press or
the like, and more particularly to digital apparatus by which the
feed of the web to the press, and away from the press, may be
accurately controlled for maximum speed and accuracy in the
positioning of the web.
2. The Prior Art
It is important to correctly position a web formed a sheet metal or
the like in relation to a punch press or the like when a quantity
of similar shapes are to be punched from the web. In order to
maintain efficient use of the material in the web, the web must be
positioned accurately so as to produce a minimum amount of wastage
in between adjacent punched sections of the web. At the same time,
in order to improve efficiency of operation of the press, the web
must be correctly positioned as rapidly as possible. It has not
been possible in the past to achieve accurate positioning without
sacrificing some speed of operation, and vice versa.
In the prior art it has been customary to employ analog type
devices, or hybrid digital-analog devices for feeding the web into
correct position in relation to the press. However, the analog
devices and the analog portions of the hybrid devices are subject
to long-time drift and do not insure maximum accuracy over long
periods of time. Moreover, as they are responsive to the magnitude
of the difference between the desired position and the actual
position at any given time, the speed of operation is quite low if
high accuracy is desired.
SUMMARY OF THE INVENTION
It is a principal object of the present invention to provide a
press feeder control apparatus which is adapted for rapidly and
accurate positioning of a web in relation to rapid punch press or
the like.
Another object of the present invention is to provide such
apparatus which operates by entirely digital means.
A further object of the present invention is to provide means for
electronically synchronizing the in-feed and the out-feed of the
web in relation to the press.
Another object of the present invention is to provide press feeder
control apparatus by which the out-feed may be made more rapid than
the in-feed of the web, to allow for stretching of the web
material.
A further object of the present invention is to provide press
feeder control apparatus in which the maximum velocity and the rate
of acceleration and deceleration are independently selectable
without affecting accuracy of the positioning.
Another object of the present invention is to provide press feeder
control apparatus in which the time at which deceleration is to be
initiated is computed automatically so as to permit the
deceleration of the web to terminate exactly at the time that the
web reaches its correct position.
These and other objects and advantages of the present invention
will become manifest upon an inspection of the following
description and the accompanying drawings.
In one embodiment of the present invention there is provided a main
counter, means for presetting the main counter with a quantity
representative of the length of feed desired for a quantity of web
material, means for decrementing the main counter at an increasing
rate until a maximum rate is achieved, means for accelerating the
web material in response to the rate at which the main counter is
counted down, a second counter, means for incrementing the second
counter until equality is reached, between the quantity manifested
in the main counter and the quantity manifested in the second
counter, and means responsive to such equality for decreasing the
speed at which the main counter is decremented, whereby said
counting rate is reduced to zero and the main counter is reduced to
zero, simultaneously with the web material having been advanced by
the length represented by the initial quantity inserted into the
main counter.
BRIEF DESCRIPTION OF THE DRAWINGS
Reference will now be made to the accompanying drawings in
which:
FIG. 1 is a functional block diagram of a system incorporating an
illustrative embodiment of the present invention;
FIG. 2 is a functional block diagram showing certain portions of
FIG. 1 in more detail;
FIG. 3 is a functional block diagram of the stretch logic unit of
FIG. 1;
FIG. 4 is a functional block diagram of the main counter
illustrated in FIG. 1; and
FIGS. 5-7 are graphs illustrating the operation of the apparatus
under various conditions.
DESCRIPTION OF THE PREFERRED EMBODIMENT
Reference will first be made to FIG. 5, which illustrates graphs of
certain parameters of the web material as it is fed to the press.
The curve 10 shows the velocity of the web with respect to time. It
can be seen that the velocity increases linearly from zero until a
maximum value VM is reached at time t1, after which the maximum
velocity is maintained until time t2. At t2, the velocity is
reduced in a linear fashion until zero velocity is reached at time
t3. As more fully described hereinafter, the maximum velocity of
the web VM is controlled in accordance with a preselected value,
and the constant acceleration between zero and t1, which is equal
to the constant deceleration between t2 and t3, is also a
preselected value.
A main counter controls the distance for which the web is fed
during each cycle of operation of the apparatus. The content of the
main counter is illustrated in FIG. 5 with respect to time on the
time scale as the curve 12. The curve 12, which represents the
content of the main counter, decreases from a predetermined initial
value L, which is preset into the main counter in proportion to the
distance desired for the web to be fed as it is fed in toward the
press. During the time that the velocity of the web is increasing,
the content of the main counter is decreased parabolically
downward, after which the content of the main counter is decreased
at a constant rate for the period between t1 and t2. At t2 the
content of the main counter is decreased more gradually
(parabolically) until it reaches zero at the same time that the
velocity of the web is reduced to zero.
FIG. 5 also illustrates a graph which corresponds to the content of
a second counter, hereinafter sometimes referred to as an
"up-counter." The content of the up-counter increases parabolically
from zero until t1, when the velocity VM of the web is reached,
after which the content of the up-counter is maintained at a
constant value until t2, during which the web travels at a constant
maximum velocity. At the end of this period the content of the
up-counter is reduced parabolically to zero, reaching zero at the
time that the web velocity is reduced to zero. The function of the
up-counter is to determine when the time t2 occurs, at which the
content of the up-counter is equal to the content of the main
counter, and which signifies that deceleration of the web, at the
same rate at which it was accelerated prior to t1, is to begin so
as to reduce the velocity of the web to zero at the same time it
arrives at its desired position.
FIG. 5 illustrates in dashed lines the operation of the present
invention for a smaller predetermined distance L'. The main counter
begins to decrease its content in the same manner described for the
distance L, as shown by the curve 16, and the up-counter begins to
count upwardly at the same rate as before. As soon as the contents
of the main counter and the up-counter are equal, however, the main
counter slows its rate of decrease, and the velocity, shown in
curve 18, also decreases, reducing the velocity to zero as the
content of the main counter reaches zero.
FIG. 1 illustrates a clock pulse generator 20, which furnishes
clock pulses for operating a ramp time control device 21, which is
controlled in accordance with the setting of a manual control
device 22, to produce a variable frequency train of pulses on an
output line 23, which is connected to the input of a ramp counter
24. The counter 24 is employed for the purpose of generating the
curve 10 of FIG. 5, and the velocity of the web is proportional to
the content of the counter 24.
The clock pulse generator 20 is also connected to a feed speed
control device 25, which is controlled by the manually adjustable
device 26 to produce an output pulse train on a line 27
proportional to the maximum desired velocity of the web.
Accordingly, the device 26 establishes the proportionality factor
between the content of the counter 24 and the velocity of the web.
The line 27 is connected to the input of a repetitive adder 28,
which produces a pulse train on an output line 29, proportional to
the product of the pulse repetition rate of the pulse train on the
line 27, and the content of the counter 24. The pulses on the line
29 control the in-feed drive, and are furnished to the drive via a
logic unit 30 to a line 31 connected to the in-feed drive unit 32.
The drive unit 32 may be any type which is responsive to a train of
pulses for moving a member an incremental length for each such
pulse. One such unit is described in my copending application, Ser.
No. 266,579 filed June 27, 1972 for "Digital Regulating Control For
Servo System."
The pulses on the line 29 are also fed to the main counter 33 and
to the up-counter 34. The main counter 33 is initially set to a
quantity representative of the desired distance the web is to move,
by signals over a line 35 from a terminal 36. The up-counter is
initially preset to zero by a signal over a line 37 from the logic
unit 30.
The ramp counter 24 is counted to its maximum capacity, which is
15, and then sends a signal to the logic unit 30 over a line 38,
which causes the logic unit to disconnect the counter 24 from the
ramp speed time control unit 21 (by means not shown) so that the
counter 24 continues to manifest its maximum count, for controlling
the web to move at maximum speed.
When the contents of the main counter 33 and the up-counter 34
become equal, this is recognized by a comparator unit 39, which
furnishes a signal to the logic unit 30 over a line 40. The logic
unit then reconnects the counter 24 to the unit 21, but in such a
way that the counter 24 is decremented by pulses from the unit 21,
so as to gradually reduce the speed of the web. When the counter 24
is reduced to its zero, a pulse is produced on a line 41, connected
to the logic unit 30. Simultaneously, the content of the main
counter 33 is reduced to zero, and a pulse is conveyed to the logic
unit 30 over a line 42, and the logic unit 30 discontinues emitting
pulses on the line 31.
The outfeed drive 43 is preferably the same as the in-feed drive
32, and is controlled by the logic unit with a pulse train over the
line 31', connected to the outfeed drive 43 through a stretch logic
unit 44. The logic unit 44 is controlled by a manually adjustable
device 45 to add pulses to the pulse train on the line 31 at a
predetermined rate, so as to increase the pulse repetition rate
applied to the outfeed drive 43, and stretch the web material in
the vicinity of the press as desired.
A counter 46 is provided for controlling the number of cycles of
operation of the apparatus. It is initially preset by a signal from
a terminal 46' over a line 47, to the numbers of cycles desired,
and disables the logic unit 30 over a line 48 when the desired
number of cycles have been performed.
Referring now to FIG. 2, some of the apparatus of FIG. 1 is
illustrated in more detail. At the beginning of a cycle the main
counter 33 is loaded with a quantity representative of the distance
which the web is to be moved for correct positioning of the web in
relation to the press by means of switches 49. A start feed signal
is produced at a terminal 50 when the web is to be fed by the
distance preset into the counter 33. A line 51 is connected from
the terminal 50 to the input of a switch noise suppressor unit 52,
which functions to suppress the noise on the line 51 by clipping or
the like, producing on an output line 53 a pulse which is
substantially free of noise. The line 53 is connected to the input
of a line receiver 54 which produces a pulse at its output which is
at the correct voltage level for the logic units which follow. The
output of the line receiver 54 is connected to the D input of a
flip-flop 55, to set the flip-flop 55.
The clock input of the flip-flop 55 is connected to a terminal 56
which is supplied with ramp frequency pulses from the ramp time
control unit 21 (FIG. 1). The ramp frequency pulses cause the
flip-flop 55 to be reset with the next pulse following its setting
but in the meantime the flip-flop 55 is effective to produce a
pulse on an output line 57, which is connected to the input of a
monostable multivibrator 58. The output of the monostable
multivibrator 58 is connected to the input of a second monostable
multivibrator 59, and the output of the multivibrator 59 is
connected to one input of a NAND gate 60. The two monostable
multivibrators 58 and 59 insure against incorrect operation which
would result if a second start feed pulse was presented to the
terminal 50 before the cycle is completed.
The output of the multivibrator 58 is connected to one input of a
NAND gate 61. The other input to the gate 61 is connected from the
Q output of a flip-flop 62, which is initially in its reset state,
thus disabling the gate 61. The output of the multivibrator 59,
which occurs later, is connected through the gate 60 to place the
flip-flop 62 in its set state, thus enabling the gate 61. However,
by this time, the output from the multivibrator 58 has ceased, so
the gate 61 remains non functional. If a second pulse is applied to
the terminal 50 while the flip-flop 62 is set, the gate 61 passes a
pulse from the multivibrator 58 to set a flip-flop 63, to signify a
feed error. When the flip-flop 63 is set, a signal is supplied to
the error control apparatus 63a, which functions to disable
operation of the apparatus as long as an error persists. It
furnishes a signal which resets the flip-flop 63 when an error
condition is corrected.
The NAND gate 60 has two inputs in addition to the one connected
from the multivibrator 59. One of these inputs is supplied from the
counter 46 over a line 64, and the signal on this input is high as
long as the number of cycles manifested by the counter 46 has not
been reached. The counter 46 is preset initially with the number of
cycles to be performed by signals from the input terminal 46' and
is decremented by unity for each cycle over a line 66.
The other input to the gate 60 is connected from a terminal 67
which is high when the apparatus is to operate in an automatic
mode. The Q output of the flip-flop 62 is connected to one input of
a NAND gate 68, and enables the NAND gate 68 to pass command pulses
present on a line 69 to the output thereof and through an inverter
70 to the input of the main counter 33. Another terminal of the
NAND gate 68 is connected to the output of the error control unit
63a over a line 70 so that the gate 68 is inhibited when an error
has occured. Another input to the gate 68 is connected to a
terminal 71, which is normally high. The level at the terminal 71
goes low in response to manula operation of a switch when it is
desired to inhibit operation of the apparatus.
The pulses which are passed by the gate 68 are effective to
decrement the main counter 33.
The output of the gate 68 is also connected over a line 72 and
through a NAND gate 73 to the input of the up-counter 34, so that
the up-counter 34 counts upwardly from zero at the same rate that
the content of the main counter 33 is being decreased. The NAND
gate 73 is enabled by a line 74 which is connected from the output
of a NAND gate 75. The output of the NAND gate 75 is connected to
the line 74 through an inverter 76.
The output of the NAND gate 75 is low when a flip-flop 77 is in its
set state, and two other flip-flops 78 and 79 are in their reset
states, a condition which occurs for the first time when the
flip-flop 77 is set by a signal over a line 80 from the NAND gate
60 at the same time that the flip-flop 62 is set. The other two
flip-flops 78 and 79 which control the NAND gate 75 have previously
been preset, as had the flip-flop 77, over a line 81. Accordingly,
the NAND gate 73 is enabled to pass command pulses over the line 82
to increment the counter 34 at the same rate that the main counter
33 is being decremented.
The output of the inverter 76 is also connected to a line 82 which
is connected to one input of a NAND gate 83. The other input of the
NAND gate 83 is connected to the terminal 56, which furnishes the
pulses at the ramp frequency, so that pulses are passed by the gate
83, to the ramp counter 24, which has previously been cleared over
a line 84 connected from the Q output of the flip-flop 62, which
occurs at the time that the flip-flop 62 is preset by the signal
derived from the NAND gate 60.
The counter 24 is connected in association with the repetitive
adder 28, which adds the content of the counter 24 over and over,
once for each pulse applied thereto over a line 85 from a terminal
86, which terminal is connected to the feed speed control unit 25
(FIG. 1). The storage capacity of the adder 28 is exceeded
periodically, as the content of the counter 24 is added frequently
by the adder unit 28, and each time the capacity is exceeded, an
overflow pulse is produced on the line 29. The pulse train thus
produced has a pulse repetition rate corresponding to the quantity
stored in the counter 24, since the larger is the quantity stored
in the counter 24, the fewer times that that quantity must be added
to exceed the capacity of the adder 28. The overflow pulses are
conveyed to a NAND gate 68 over the lines 29 and 69 and then to the
counters 33 and 34. The initial count in the counter 24 is zero, as
it is cleared by the pulse on the line 84. However, the pulses
which are supplied to the counter 24 through the gate 83 cause its
content to increase, resulting in an increase in frequency of
overflow pulses on the line 29. Therefore, the rate at which the
main counter 33 is being decreased, and the rate at which the
up-counter 34 is being increased, increases in proportion to the
quantity stored in the counter 24. This rate is also proportional
to the pulse repetition rate of the pulse train on the line 85, for
this determines the rate at which the content of the counter 24 is
added.
When the quantity stored in the counter 24 reaches "15," this is
recognized by a unit 87, which produces a pulse on the line 38. The
counter 24 is a four stage binary counter, so that the quantity
"15" is identified by high outputs from all four stages of the
counter. The unit 87 preferably contains a four input NAND gate
connected to the four outputs of the counter 24, so that an output
pulse is produced on the line 38 when all four outputs are high.
The line 38 is connected to the set input of the flip-flop 78.
Accordingly the flip-flop 78 is set, and its Q output goes low,
thereby disabling the NAND gate 75, and disabling the gate 73 by
which command pulses are supplied to the up-counter 34.
Accordingly, no further pulses are introduced into the up-counter
34, which therefore maintains the count which it manifests at the
time that the counter 24 reaches "15."
The quantity "15," when stored in the counter 24 gives a maximum
frequency of overflow pulses on the line 29, which is proportional
to the repetition rate of the pulses applied to the terminal 56,
with the result that the frequency of the command pulses applied to
the counters 33 and 34 is at a maximum. As the command pulses
represent individual increments of movement for the web, as it is
fed in toward the press, the frequency at which the command pulses
are produced is directly proportional to the velocity of the web.
As a result, the velocity of the web is increased to a maximum and
that maximum is realized when the counter 24 reaches the quantity
"15." Thereafter, feed continues with the content of the main
counter 33 being reduced at a constant rate, until a comparison
between the quantities stored in the main counter 33 and the
up-counter 34 is recognized by the comparator unit 39. When this
occurs an output pulse is produced on the line 40, which is
effective to change the state of the flip-flop 79, as the line 40
is connected to its clock input. This causes the Q output of the
flip-flop 79 to go low, disabling the NAND gate 75 if it is not
already disabled, and produces an output signal on the Q output of
the flip-flop 79. The line 102 is connected from the Q output of
the flip-flop 79 to one input of a NAND gate 103, the other input
of which is connected to the terminal 56 to receive the pulses at
the ramp frequency. Accordingly the gate 103 passes the pulses from
the terminal 56 to a line 104 which is connected to the reverse
counting input of the counter 24. Accordingly, the counter 24 is
decremented by application of successive pulses from the terminal
56 over the line 104, with the result that the frequency of the
overflow pulses produced on the line 29 is reduced, thereby
decelerating the web.
This operation continues, with additional pulses being supplied to
decrease the quantity stored in the counter 24, until the counter
24 has been reduced to zero. This occurs at the same instant at
which the main counter 33 is reduced to zero, for the time required
to reduce the counter 24 from "15" to zero, by application of the
pulses at the terminal 56, is the same time which is required to
increase it from zero to "15," and that time corresponds to the
time required to produce the number of command pulses stored in the
up-counter 24. This is exactly the same number of pulses which
remain in the down counter at the time that the comparator unit 59
issues its output pulse on the line 40. Accordingly, the velocity
of the web, which is proportional to the quantity stored in the
counter 24, is reduced to zero at the same time at which it reaches
its correct position in relation to the press, having moved the
number of increments of movement initially set into the main
counter 33.
A monostable multivibrator 106 is connected to the line 41, which
produces a pulse when the content of the counter 24 is reduced to
zero. The pulse causes the multivibrator 106 to emit a pulse on an
output line 81, which is connected to the reset inputs of the
flip-flops 77, 78 and 79, thus serving to reset them to their
initial conditions. The resetting of the flip-flop 79 causes the
output on the line 102 to go low, disabling the gate 103, so the
counter 24 is held at zero. The multivibrator 106 is also triggered
by a pulse appearing on a line 111, which is developed when the
content of the main counter 33 reaches zero.
The line 42 is connected to one input of a NAND gate 107, the two
other inputs of which are normally high. One of these inputs is
connected to a terminal 108, which goes low momentarily when power
is first applied to the system, and the other is connected to a
terminal 109, which goes low momentarily when the apparatus is
desired to be reset for any reason.
The output of the gate 107 is connected through an inverter 110 to
a line 111, which is connected to an input of the multivibrator
106, and also to the reset input of flip-flop 62, which serves to
reset the counter 24 to zero, via the line 84, and to decrement the
batch counter 65 by means of a pulse transmitted thereto over the
line 66. The Q output goes low, which serves to disable the gate
68. The Q output of the flip-flop 62 is also connected over a line
112, through an inverter 113, to an input 114 of the up-counter 34,
which operates to reset the up-counter to zero, and to an input 115
of the main counter 33, which serves to transfer a new quantity
into the counter 33 from the switches 49, preparatory to a new
cycle of operation.
The command pulses are supplied to the in-feed drive from the gate
68 by means of NAND gates 116 and 117. One input of the NAND gate
116 is connected to the output of the gate 68, via the line 82, to
receive the pulses applied to the main counter 33, and its second
input is enabled when a flip-flop 118 is in condition to select an
automatic mode of operation. This produces a signal on an output
line 119 which is connected to one input of the NAND gate 117. The
other input of the NAND gate 117 is connected to a terminal 120
which is normally high, except when a jogging operation is desired.
The output of the NAND gate 117, which is supplied to the line 31,
is then supplied to the in-feed drive, which feeds the material
from its source of supply into proper position in relation to the
press.
Two additional NAND gates 121 and 122 are provided for the out-feed
drive, and they correspond generally to the gates 116 and 117 for
the in-feed drive. The gate 121 however, instead of being connected
to the source of command pulses produced at the output of the gate
68, is instead connected to a terminal 123, to which a train of
pulses is applied which will be referred to as "mixed" pulses. The
mixed pulses comprise the command pulses produced at the output of
a NAND gate 68, but, in addition, also include the pulses produced
in response to the operation of the stretch logic 44, which is
activated when it is desired to stretch the web material in the
vicinity of the press. When this is desired, additional pulses are
fed to the out-feed drive to cause it to function at a slightly
greater velocity than the in-feed drive.
The second input of the gate 121 is connected to the Q output of
the flip-flop 118, which is high in the automatic mode, and its
output is connected to an input of the gate 122. The second input
of the gate 122 is connected to the terminal 120, which is normally
high, and its output is connected to the out-feed drive over a line
124.
The source of the mixed pulses applied to the terminal 123 is shown
in FIG. 3.
The output of the NAND gate 68 is connected by way of a line 128
and an inverter 130 to one input of a NAND gate 131, and the source
of stretching pulses is connected to the other input of the NAND
gate 131. The frequency of stretching pulses is selected by means
of a plurality of manually operable switches 132, which are
connected via gates 134 to four repetitive adding units 135a-135d,
connected to function as a 16 stage repetitive adder. Four switches
132 are provided, and they are connected to four successive ones of
the 16 inputs of the repetitive adder 135a-135d. The inputs which
are thus connected are selected by the gates 134, so that a great
range of quantities may be represented by the four switches
132.
A flip-flop 131 has its input connected to the output of the
inverter 130, so that it changes its state for every command pulse
applied thereto over the line 128. A NAND gate 140 has one input
connected to the overflow output of the fourth stage 135d of the
repetitive adder, and another input connected to the line 138, so
that the pulses produced on the line 136 are synchronized with the
pulses applied to the line 128, and have a pulse repetition rate
which is a submultiple of the rate of the pulses on the line 128,
as controlled by the switches 132. Four switches 132 are provided,
which operate to preset four successive stages of the multistage
counter 134, which is preferably 16 stages. The selection of the
stages to which the switches 132 are connected is made in
accordance with the range of stretching which is desired. The
repetitive adder 135a-135d functions to produce at an output line
136 an output pulse train having a pulse repetition rate
proportional to the product of the quantity represented by the
switches 132, and the pulse repetition rate of pulses applied to
the operating inputs of the adder units 135a-135d over the lines
137 and 138 from a flip-flop 139. The output of the gate 140, at
which the stretching pulses are produced, is connected through two
monostable multivibrators 142 and 144 in succession to a second
input of the NAND gate 131. The output of the second monostable
multivibrator 144 effectively disables the NAND gate 131 during the
middle portion of one of the command pulses supplied from the
inverter 130, but restores it to its ordinary mode of operation
before the end of such command pulse, to in effect, transform a
single command pulse on the line 128 into a pair of command pulses.
The result is that an additional pulse is added to the terminal 123
for each pulse passed by the gate 140. The time period of the first
multivibrator 142 is sufficient to delay the pulse from the gate
140 so that its leading edge occurs about one-third pulse time
after the leading edge of a pulse produced by the inverter 130, and
the time period of the multivibrator 144 is sufficient to cause the
pulse applied to the gate 131 to disable it for only the middle
third of one command pulse.
The amount of stretching of the web material in the vicinity of the
press is controlled by the rate at which stretching pulses are
produced at the output of the gate 140. As this is a submultiple of
the command pulse rate, the stretching is constant for any rate of
feed.
FIG. 4 illustrates the counter 24 with its three inputs 83a, 104
and 84. The input 84 functions to reset the counter 24, while the
inputs 83a and 104 are connected, respectively, from the gates 83
and 103, serving to increment and decrement the counter 24 for each
input pulse applied thereto. The repetitive addition unit connected
to the counter comprises, in the embodiment shown in FIG. 4, three
functional units 145, 146 and 147, which are commercially available
integrated circuits. In one embodiment, the unit 145 is marketed by
Texas Instruments under model No. SN 7483N, and the units 146 and
147 are marketed by Signetics under model No. N8280A. The manner in
which these units are connected to form a repetitive adder is well
known. The drive for the adder is derived from the terminal 86 and
is connected directly to the unit 147 over the line 85, and to the
unit 146 through an inverter 148, so that the units 146 and 147 are
alternately energized in response to a pulse train arriving at the
terminal 86. A NAND gate 149 has one input connected to an output
of the unit 145 and the other is connected to the line 85, so that
output pulses produced thereby are synchronized with the incoming
pulse train.
The repetitive adders employed for the stretch logic unit shown in
FIG. 3 are formed of the same components, but the units
corresponding to the unit 145 of FIG. 4 are connected together in
cascade, to accommodate a wider range of output pulse repetition
rates.
Preferably, the ramp time control unit 21 and the feed speed
control unit 25 are also formed in the same manner as the
arrangement of FIG. 4, except that groups of switches 22 and 26 are
substituted for the counter 24 in FIG. 4, so that the pulse
repetition rate of the output pulse train is a product of the pulse
repetition rate of the clock pulse generator 20, and the quantity
manually set into the switches 22 and 26.
In an alternative embodiment of the present invention, all of the
repetitive adder units are replaced by another form of multiplier
unit, which functions to produce an output pulse train having a
pulse repetition rate proportional to the product of the pulse
repetition rate of an input pulse train, and the content of a
register such as the counter 24 or a group of switches. One such
multiplier which may be employed in substitution for the repetitive
adders used in the embodiment described above is marketed by Texas
Instruments under model No. SN 7497, and its use as a multiplier is
described in the T.I. Application Note CA160.
The effects of modifying the multiplier employed in the units 21
and 25 are shown in FIGS. 6 and 7. FIG. 6 shows velocity curves for
the web for two different settings of the switches 26, which
control the pulse repetition rate on the line 27. The time
positions of the times t1, t2, and t3 are unchanged, but the
maximum web velocity has been altered.
FIG. 7 shows velocity curves for two different settings of the
switches 22, which control the pulse repetition rate on the line
23. The maximum velocity is constant, but the rate employed for
acceleration and deceleration is altered. For any settings of the
switches 22 and 26, however, synchronization is maintained, and the
velocity of the web is brought to zero as the web arrives at its
proper position.
The provision by which the gate 75 is disabled by the setting of
either of the flip-flops 78 and 79 enables the apparatus to operate
properly for any distance L set into the main counter 33. If the
distance L is relatively large, the gate 75 is disabled when the
counter 24 reaches "15." Otherwise, it is disabled when the
up-counter 34 reaches the same count as the main counter 33, the
condition illustrated by the dashed curve 16 in FIG. 5.
In order to insure that the content of the main counter 33 is
reduced to zero during the cycle, even if the counter 24 reaches
zero before the main counter 33, the adder unit 28 has its carry-in
input 160 connected to a source of positive potential at a terminal
161, so that an output is present on the output of unit 145 (FIG.
4) after the counter 24 reaches zero. This operates to cause the
adder 28 to add unity to the content of the adder 28 for each pulse
at the terminal 86, so that overflow pulses are produced at a low
rate, even when the counter 24 is zero. These are passed to the
gate 68. The counter 33 is thereby positively reduced to zero, and
the resetting of the flip-flop 62 disables the gate 68. This
operation positively brings the main counter 33 to zero to avoid a
hang-up which otherwise would prevent the drive from reaching the
desired position.
Although manually operated switches 22, 26, 132 and 49 have been
described in connection with the apparatus illustrated in the
drawings, such switches may optionally be replaced with a register
or the like, set in accordance with signals produced by a card
reader, magnetic tape reader, or the like, or an input from a
computer.
The inverter 148 is employed in the apparatus of FIG. 4 to derive
staggered control pulses for controlling the units 146 and 147. It
is preferable to employ a flip-flop with the repetitive adder units
associated with the ramp time control 21 and the feed speed control
25, with the flip-flop connected to change its state with each
input pulse, and the Q and Q outputs of the flip-flop connected to
control the units similar to the units 146 and 147 of FIG. 4.
It will be appreciated that although the present invention has been
described specifically in terms of a press feeder, it may be
employed wherever precise and swift movement is desired. The
invention is especially useful where it is desired to independently
select desired values for velocity and acceleration.
In one embodiment, the following devices were employed for some of
the functional units illustrated in the drawings: Counter 24 T.I.
model SN 74193N Counter 33 four T.I. model SN 74193N units Counter
34 four Signetics model N8281A units Comparator 39 four T.I. model
SN 74L85M units Adder 145 T.I. model SN 483N Units 146 & 147
T.I. model SN 8280 NAND gates T.I. model SN 7400N Flip-flops T.I.
model 7474N Monostable Multivibrators T.I. model 74122N
* * * * *