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Патент USA US3069618

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Dec. 18, 1962
J. w. FORRESTER ETAL
3,069,608
NUMERICAL CONTROL SERVO-SYSTEM
Filed Aug. 14, 1952
15 Sheets-Sheet 1
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JAY w. FORRESTER
WILLIAM M. PEASE
JAMES O. MCDONOUGH
ALFRED K. SUSSKIND
BY
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Dec. 18, 1962
J. w. FORRESTER EI‘AL
3,069,603
NUMERICAL CONTROL SERVO-SYSTEM
15 Sheets-Sheet 3
Filed Aug. 14, 1952
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INVENTORS
JAY W. FORRESTER
WILLIAM M. PEASE
JAMES O. MCDONOUGH
ALFRED K. SUSSKIND
BY
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Dec. 18, 1962
J. w. FORRESTER ETAL
3,059,608
NUMERICAL CONTROL SERVO-SYSTEM
Filed Aug. 14, 1952
l5 Sheets-Sheet 4
INVENTORS
JAY W. FORRESTER
WILLIAM M. PEASE
JAMES O. MCDONOUGH
ALFRED
Dec- 13, 1962
J. w. FORRESTER ETAL
3,069,608
NUMERICAL CONTROL SERVO-SYSTEM
Filed Aug. 14, 1952
15 Sheets-Sheet 5
.E
m
INVENTORS
JAY W. FORRESTER
WILLIAM M. PEASE
JAMES 0. MC DONOUGH
ALFRED K. SUSSKIND
BY
Dec. 18, 1962
J. w. FORRESTER ETAL
3,069,603
NUMERICAL CONTROL SERVO-SYSTEM
Filed Aug. 14, 1952
15 Sheets-Sheet 6
m9
INVENTORS
JAY W. FORR ESTER
WlLLIAM M. PEASE
JAMES O. MCDONOUGH
ALFRED K. SUSSKIND
l______| E
BY
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Dec. 18, 1962
J. W. FORRESTER ETAL
3,069,608
NUMERICAL CONTROL SERVO-SYSTEM
Filed Aug. 14. 1952
l5 Sheets-Sheet 8
Fig. 8
TIME
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CARRY OUTPUT OF
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CARRY OUTPUT OF
SECOND FLIP-FLOP,
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INVENTORS
JAY W. FORRESTER
WILLIAM M. PEASE
JAMES O. McDONOUGl-I
ALFRED K. SUSSKIND
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- Dec. 18, 1962
J. w. FORRESTER ETAL
3,069,608
NUMERICAL CONTROL SERVO-SYSTEM
Filed Aug. 14, 1952
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Dec. 18, 1962
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Filed Aug. 14, 1952
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WILLIAM M. PEASE
JAMES O. MCDQNOUGH
ALFRED K. SUSSKIND
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Dec. 18, 1962
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J. w. FORRESTER ET AL
3,069,608
NUMERICAL CONTROL SERVO-SYSTEM
Filed Aug. 14, 1952
15 Sheets-Sheet 12
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INVENTORS
JAY W. FORRESTER
WILLIAM M. PEASE
JAMES O. MCDONOUGH
ALFRED K. SUSSKIND
Dec. 18, 1962
J. w. FORRESTER ETAL
3,069,608
NUMERICAL CONTROL SERVO-SYSTEM
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Filed Aug. 14, 1952
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INVENTORS
JAY W. FORRESTER
WILLIAM M. PEASE
JAMES O. MCDONOUGH
ALFRED K. SUSSKIND
United States Patent 0
1
3,059,608
NUMERIQAL CONTROL SERVO-SYSTEM
Jay W. Forrester, William M. Pease, and James 0. Mc
Donough, Concord, and Alfred K. Susskind, Cam
bridge,_l'viass., assignors, by mesne assignments, to John
T. Parsons, Danville, Ill.
Filed Aug. 14, 1952, Ser. No. 304,2§4
69 Claims. (Cl. 318-162)
3,069,608
Patented Dec. 18, 1962
2
motions included in the control system. Another impor~
tant feature of the invention is the provision for select
ing a choice of ratios available in the digital domain
which are readily changeable to various speeds.
Another important object of the invention is the elimi
nation of the necessity of separate orders or commands
for the rate of advance of one or more machine operated
parts and for governing the position thereof. The inven
tion provides a single set of binary-divided pulse rates
This invention relates to control systems and particu 10 which generate “machine time” and “machine space,”
both having the same dimensions expressed in pulses
larly to a novel method of and apparatus for controlling
thereby eliminating the necessity of providing separate
the operation of industrial appliances and processes such
as machine tools and the like.
The general purpose of this invention is to provide an
orders or commands for the rate and the position of the
feed directions. No models or templates are required
to perform the coordinated motions in the machine-feed
directions and instead, information for controlling the ma
chine may be stored in coded form on simple, convenient
mediums such as punched paper tape, punched cards,
vide improved means in the system for storing and com
operating parts controlled thereby.
Another important object of the invention is to provide
improved control system which is especially desirable for 15
a novel method of and means for synchronizing command
machining mathematically de?nable surfaces without re
pulses governing the action of one or more controlled
sorting to the expensive practice of ?rst constructing
parts or servo-mechanisms with response pulses for sub
models or templates having better than the required ac
stantially simultaneously synchronizing the input com
curacy of the ?nished work. In such use, the present in
vention enables the machining or shaping of work which 20 mands with the output responses in order that the system
may behave as nearly like a continuously operated sys
is not limited to lines parallel to the machine-feed direc
tem as possible.
tions but permits any cutting or shaping operation along
Another important object of the invention is to pro
any line skewed or inclined with respect to the machine
paring the input commands and output responses in incre
mental form and for simultaneously subtracting one from
the other to obtain a differential or error signal for con
trolling the movement of one or more servomotors. In
magnetic tape, photographic ?lm, et cetera. Electrical
means is employed for interpreting the coded informa
tion and for transmitting the information in electrical
carrying out this object there is provided a reversible
counter which approximates a continuous differential for
an error detecting or summing device and which enables
Although the invention is applicable to the control of
pulses spaced in time, each pulse of which may represent
the movement and positioning of one or more moving
an instruction to an operating part of the machine to
the output to be compared with the input substantially
form to the one or more moving operating parts of the
simultaneously and while storing only the maximum
controlled unit or machine. The result is that the con
error and not the entire command number.
trol system or director may be located remote from the
Another important object of the invention is to provide
machine and be used not only to control one but several 35
a master or clock oscillator which generates a series of
similar machines.
move one unit of distance. An important feature of the
parts of various types of apparatus, it is especially appli
cable to the shaping or sculpturing of objects and particu 40 invention relates to the provision of a frequency divider
associated with the clock oscillator which generates a pat
larly the machining of templates, forging dies, stretch
tern of potential command pulses for governing the op
form dies, airfoil sections, et cetera. Conventional die
eration of the servo-mechanisms. Another important fea
making and similar shaping processes are usually 1a
borious, time consuming, painstaking operations requir
ture of the invention is the novel association of the fre
ing the production of checking templates, and ?nal hand
quency divider with an information storage medium re
?nishing to produce an accurate die. The present inven—
tion eliminates the production of template and in most
instances reduces the necessity for hand ?nishing of the
die or other object worked on at the same time permitting
sponsive to coded information on tape or otherwise which
impresses the stored information into the potential com
mand pulses provided by the frequency divider.
Another important object of the invention is to provide
smaller tolerances than those usually required by present
a counting-error detector which functions to subtract the
day standards. The elimination of the tedious hand oper
ations as well as the production of templates, consider
An important object of the invention is to provide a
control system for a machine, such as a milling machine,
output from the input pulses and is reversible to ap
proximate a continuous error-detecting or summing de
vice. The counting error detector has a register capacity
which by virtue of its construction and function need only
be large enough to store the maximum differential or error
the various motions of the machine and which converts
on pulses and which permits the use of synchronizing sens
ably shorten the diemaking time.
which incorporates a pulsed sensing electrical circuit and 55 between the input and output pulses, which differential
or error is utilized to control the operation of one or
provides binary-dividedpulse rates properly phased to in
more servomotors. In consequence, the digital conver
terpret the commands on medium containing the stored
sion of the output and the input is in pulses and in a dif
control information. The control system is designed to
ferential or error channel where the signals are relatively
employ digital technique to maximum advantage and re
quires only a single enumerating speci?cation. An im 60 small. The digital conversion to the analog commands
is “inside the loop” of one or more servo-mechanisms
portant feature of the invention is the integration of the
employed in the machine and as a result the analog un
rate and position commands into one system enabling the
certainty is limited to an arbitrarily small percentage of
use of a single medium upon which the stored informa
tion is carried.
the total signal handled.
Another important object of the invention is to pro 65
Another important object of the invention is to provide
vide a control system which insures synchronism between
a code converter in the form of a sensing system operating
the information provided in digital form into the analog
form ?nally embodied in the machined workpiece. An
ing pulses for accuracy and checking.
Another important object of the invention is to provide
70
important feature of the invention is the use of a common
a dual storage system which allows the machine to op
time parameter in the digital domain for coordinating all
erate continuously from discontinuously obtained data
‘8,069,608
3
4
furnished by coded media such as punched tape. The
dual storage system comprises two storage registers which
are alternately operable to impress the information stored
therein into the potential command pulses for operating
the servo-mechanisms.
FIG. 17 is a plan view of a section of punched tape
illustrating the arrangement of holes in two adjacent in
formation blocks,
5
Another important object of the invention is to provide
means for checking the operation of the machine parts and
FIG. 18 is a diagrammatic View of an airfoil panel,
FIG. 19 is a perspective sectional view of the airfoil
panel of FIG. 18, illustrating the relation of the cutter’s
center to the workpiece and the three axis coordinates,
particularly the use of a counter as an error detector which
and
provides one pulse in a series of pulses for each cycle of
information. This pulse is preferably the last of the
series of pulses provided for each cycle of information and
FIG. 20 is a perspective diagram illustrating the correc
tion to be applied to the coordinates to account for non
coincidence of cutter center to point of contact with the
is used as a check on the system to avoid any unannounced
workpiece.
loss of synchronism either in the control system or in the
Although the control system of the present invention is
applicable to other uses, it is herein described as applied
to and combined with an industrial machine and speci?cal
ly a machine tool. A machine tool numerically con
trolled by the system is designed to serve function which
is not available in existing types of such machines. it
differs from standard machine tools in that directions of
cuts are not limited in lines parallel to the machine-feed
functioning of the servo-mechanisms.
Another important object of the invention is to pro
vide a novel method and means for detecting or sensing
the direction in which an operating part or tool of the
machine has moved. This is accomplished by the pro
vision of a novel position coder which transmits outgoing
pulses in separate circuits, the sequence of such pulses
being alterable depending upon the position of the operat
ing part for controlling the direction of the future move
ment of the part. These signals, in the form of pulses,
are carried Within the loop of the servo-mechanisms and
incorporated in the pulsing system at the. point Where the
digital commands are converted into analog commands.
Various other objects, advantages and meritorious fea
tures of the invention will become more fully apparent
from the following speci?cation, appended claims and ac
directions, but as a result of a positive coordination among
the several feed mechanisms it is possible to out along a
line inclined or skewed with respect to the feed directions
built into the machine. Moreover, such a machine tool
I’ differs from contour directed machine tools in that no
models or templates are required to perform the coordi
nated motions in the several directions in which the ma
chine is capable of operating.
The control instructions fed to the machine by the con
companying drawings wherein:
30 trol system may be set in either manually or automatical
FIG. 1 is a general perspective view of a machine tool
ly by means of a control unit referred to as the director.
in the form of a bridge type planer mill and a director
The automatic instructions may be set into the machine on
unit for controlling the operation of the machine tool.
an information storing medium such as punched paper
FIG. 2 is a functional block diagram
perspective of
tape, magnetic tape, punched cards, photographic ?lm, et
the machine tool and its director unit and partially broken 35 cetera. These instructions are speci?cations of straight
away to show the major components thereof and the in
line segments. By suitable coding of the data storing me
terconnection therebetween,
dium, such as punched tape, any curved line within the
FIG. 3 is a simpli?ed block diagram of the overall sys
capabilities of the machine tool can be machined or cut by
tem of the invention for controlling the‘operating parts
approximating the curved line by a series of straight-line
of a machine tool,
40
segments.
be
set in manually
In addition,
at theinstructions
director. This
to themay
machine
be accom
FIG. 4 is a partial block diagram of the control system
of the present invention,
plished by means of a plurality of banks of switches which
FIG. 5 is the balance of the block diagram illustrated
through circuits inform the machine how far it must travel
in FIG. 4,
in each coordinate direction and the machine acts upon
FIG. 6 is a simpli?ed block diagram of the clock system
these instructions to produce a straight-line motion for
schematically illustrating the division of a cycle of pulses
the speci?ed interval.
generated by a clock oscillator and the modulation there
FIG. 1 shows a conceptual arrangement of a machine
of by manual or automatic control means,
tool and its director. The machine tool illustrated in PEG.
FIG. 7 is a schematic View in perspective illustrating
1 and subsequently discussed hereinafter is an example
the automatic data supply system including the manner
of how this invention may be applied. It is not limited
of reading coded information on punched tape and the
to machines of this character. The illustrated machine
distribution of such information to separate banks of
tool is a bridge type of planer mill and is generally indi
storage control registers,
cated at 119‘. The director for the machine tool is gener
ally indicated at 12 and may be located near the machine
FIG. 8 is a chart illustrating the pulse sequence pro
vided by the initial frequency divider in the clock system,
tool or remote therefrom.
FIG. 9 is a chart illustrating the pulse sequence pro
The particular machine tool illustrated herein has three
operating axes functioning in planes perpendicular to one
another in order to provide relative movement between the
vided by the second frequency divider in the clock system,
FIG. 10 is a schematic perspective view illustrating a’
typical power servo-mechanism for controlling the move
work and the shaping or cutting tool. These axes are re
60 ferred to respectively as the “X,” “Y” and “Z” axes. The
FIG. 10A illustrates a preferred circuit for the synchro
“ ”’ axis in the illustrated embodiment of the invention
devices,
is utilized to drive a table 14 upon which the work is
ment of one of the operating parts of a machine tool,
FIG. 11 is a schematic perspective view of one of the
placed and to move the table relatively horizontally to
pulse-code-to-analog servo-mechanisms in the control sys~
tem,
FIG. 12 is a diagrammatic representation of the posi
tion coder illustrating how pulses received by the coder
guide channels i8—18 of conventional design for this
and fro on a bed 16 having a pair of parallel ways or
purpose. The “Y” axis is utilized to drive a part of the
machine referred to as the rail Zn in a vertical path above
the table 14. The rail is mounted for vertical travel on an
inverte generally U-shaped column 22 which is a cus
are modi?ed to determine the direction of each movement
of the machine tool part controlled thereby,
FIG. 13 is a simpli?ed equivalent circuit of the decoder, 70 tomary feature of the bridge type or" planer mill. Carried
FIG. 14 isa block diagram of the divider checking cir
on the rail 20 is a head 24 from which depends a shaping
cuit,
tool which may be a cutter 26. The third axis “Z” is
utilized to drive the head
in a to and fro direction along
the rail 2% cross-wise to the table 14.
FIG. 15 is a block diagram of the summing register,
FIG. 16 is a block diagram of the position-code con
verter,
75
Separate-drive equipment is provided for moving the
3,069,608
6
5
table 14, rail 20, and the head 24 as shown in FIG. 2,
these drive mechanisms may be housed in separate units
indicated respectively at 28, 30 and 32. However, as il
lustrated in FIG. 1, the drive equipment for the table and
the rail may be housed in a single unit indicated at 34 at
one side of the column 22. Each drive equipment for
the separate axes of the machine tool is preferably a
power operated servo-mechanism of the character herein
after described.
The various component parts of the director 12 may be 10
functions to start and stop the machine, check signals sup
plied by the directing elements of the system and as later
pointed out hereinafter for indicating any malfunctioning
of the machine to the operator. The central control is
electrically connected to the clock system 42 previously
ponents and for indicating any malfunction in the con
trol system. Referring to FIG. 2, the director 12 is
servo-mechanisms in turn furnish synchro data to the
machine drive servomotors 28, 30 and 32 which as
broken away to show schematically such components as a
previously described control the moving parts 14, 2d and
mentioned which serves as the primary pulse source for
the operation of the machine. Included in the clock sys
tem as hereinafter described is means for dividing the
pulses emitted by the clock system. One set of divided
pulses from the clock system is furnished by channel 78
to both the automatic data supply system 44 with which
incorporated into a single unit as shown in FIGS. 1 and 2
the tape reader ‘46 or other form of sensing mechanism for
and located either adjacent to the ,machine or remote
reading stored information is associated and to the manual
therefrom. The director is electrically connected to the
data supply system 48 which, as shown in the block dia
servo drive mechanisms of the machine tool by electric
conduits as illustrated in FIG. 2. Separate electrical con 15 gram of FIG. 3, is disposed in relatively parallel relation
ship to the automatic data supply system. Another di
trol channels lead from the director to each of these drive
vided set of pulses from the clock system ‘42 is conveyed
mechanisms, the one for the table drive equipment being
by channel 80 for synchronizing the operation of the pulse
indicated at 36; the one for the rail equipment being indi
code-to-analog servo-mechanisms in the manner herein
cated at 38, and the one for the head drive equipment be
after described.
ing indicated at 40. It is understood that the director 12
The function of the data supply systems 44 and 48
may be provided vwith simlar sets of control channels 36,
is to convert the instructions either manually applied or
38 and 40 for controlling one or more additional machine
automatically furnished on coded tape into controlling
tools.
signals capable of adjusting or modulating the pulses
The director 12 of the control system is sub-divided into
a plurality of components which are electrically coupled 25 generated by the clock system in accordance with the in
structions received. The resulting adjusted pulses are
together for decoding and furnishing command informa
used as command pulses for controlling the moving parts
tion to the power servo-mechanisms housed in the units
28, 30 and 32, for comparing the resulting operation of
of the machine with which the director is associated,
such as the pulse~code-to~analog servo-mechanisms 5t},
the moving part of the machine against the command in
formation furnished thereto, and for checking the com 30 52 and 54 of the machine illustrated herein. These
clock system 42, an automatic data supply system 44 in
24 of the machine tool. Return circuit channels may be
cluding a reader 46 for sensing stored information such 35 provided as indicated in dotted lines at 82, 84 and 86
as on punched tape, a manual data supply system 48, and
for the purpose of signalling the data supply system 44
as many pulse converting servo-mechanisms as there are
to stop the ?ow of command pulses in the event of any
machine drive axes on the machine such as the three
malfunction preventing proper responses. The checking
units 50, 52 and 54, referred to as pulse-code-to-analog
signals ‘furnished by the channels 82, 84 and
are con
servo-mechanisms, which separately control the machine
drive servomotor units 28, 3t) and 32 respectively as illus
trated by the communicating channels 36, 38 and 40 be
tween the director and the milling machine.
veyed to the central control 74 as indicated by the ex
tensions of the dotted lines to that element. In addi
tion, a return line 88 may be provided which connects
the “Y” axis machine driven servo-mechanism 3% with
the central control 74 to furnish a command signal for
The director unit 12 is provided with a front panel as
shown in FIG. 1 upon which various control and indicat 45 retracting the cutter under circumstances preventing the
ing elements are preferably visibly ‘mounted for actuation
stopping of the machine under control.
and observation 'by the operator. Such control and indi
As herein illustrated, the three power servomotors 28,
cating elements are schematically shown in FIG. 1. The
30 and 32 perform the function of positioning the shap
front panel of the director may be sub-divided into panel
ing tool or cutter 26 with respect to the workpiece on
sections fronting the different components of the director 50 the machine table 14‘. In terms of the bridge-type of
therewithin. For example, one panel section ‘56 may con
planer mill being considered herein, it is understood from
tain a start and stop control member 58 and associated
the previous description that one servomotor, such as
alarm controls mounted adjacent thereto. Another panel
thepunit 28, positions the table in the longitudinal di
section, such as that indicated at 60, may contain means
rection; that a second servomotor, such as the unit 3%,
for manually feeding data into the system including a plu 55 positions the rail 243 in a vertical direction with respect
rality of toggle switches 62 disposed on the panel section
to the table; and the third servomotor, such as the unit
in accessible position. The means for automatically sup
32, positions the shaping or cutting tool 26 in the trans~
plying data into the control system, such as the tape reader
46, may be mounted in the director with the front panel
verse (cross feed) direction of the machine. It is under~
stood that the power units or machine drive servomotors
section removed in order to render it accessible to use. 60 are capable of accomplishing their positioning functions
A front panel section 64 may be provided with a control
member 66 for varying the frequency of a pulse generating
clock oscillator. Other front panel sections of the director
in the presence of cutting force reactions of considerable
magnitude.
Group Relation of Functional Components of Control
may be provided with power supply controls such as indi
System
ca-ted at 68 and 70, and with indicating elements 72 as 65
sociated with summing registers and decoders. All the
The general assemblage of the major components of
component parts of the director may be housed in one or
the control system has been heretofore described in con
more units adjacent to the machine controlled thereby, or
nection with FIGS. 1, 2 and 3. There follows a more
they may be' separately located from one another and the
completely integrated charted representation of the con
trol system and showing its application to one of the
machine.
pulse-code~to~analog servo-mechanisms and the machine
FIG. 3 is a simpli?ed block diagram of the control sys
drive servomotor associated therewith. FIGS. 4 and 5
tem for a machine tool showing the connections of the
together illustrate a more comprehensive block diagram
major functional elements thereof. For purpose of clari
of the control system showing the functional components
ty, a brief reference to the simpli?ed block diagram will
show a panel 74 referred to as the central control which 75 of the system and the interconnections therebetween in
3,069,608
7
eluding control and checking channels as well as the main
signal channels.
8
set to correspond to a velocity preferably slightly in ex
cess of the maximum feed rate of the machine under
control as hereinafter explained.
Referring particularly to FIGS. 4 and 5, it is noted
that PEG. 5 is a continuation of the block diagram of
The clock oscillator 9d is regulated by the control
FIG. 4 and shows the interconnection of one pulse-code Ci element 66 on the central control panel 7-4. The pur
to-analog servo-mechanism and the power servo—mecha
pose of this control element is to obtain variable feed
nisrn controlled thereby with the command, checking
rates for the movable parts of the machine tool. For
and control circuits of
Al. The pulse-code-to-analog
this purpose, the clock oscillator may be made continu
servo-mechanism selected for illustrative purposes is the
ously variable over two bands. One hand of adjust
one controlling motions along the “X” coordinate of the .0 ment covers ?ve hundred to twenty-?ve hundred pulses
machine, namely, servo—mechanism till.
The machine
per second and the other band covers one thousand to
drive servo—mechanism 28 is operatively associated there
with and as previously described controls the movement
of the machine table “1.1. It is understood, as shown by
the separate command pulse channels leading from the
data supply system 424 in PEG. 3 that the two remaining
servo—mechanisms 52 and 5d and their respective servo
?ve thousand pulses per second. Each pulse generated
by the clock oscillator 96 may be of any form but pref
erably is half sinusoidal and the duration may be ten
micro-seconds at its base. The pulses generated by the
clock oscillator are conveyed by channel 104 to the first
nn era are similarly operatively connected to the com
mand, checking and control circuits of FIG. 4.
frequency divider
In general, the vfunction of the ?rst frequency divider
92 in the clock system is to divide the pulses received
The component systems of the director hereinabove 20 from the clock oscillator, sending certain synchronizing
pulses out on the channel St) to the pulse-code-to-analog
described in connection with FIG. 3 are shown in more
detail in FIGS. 4 and 5. The box outlines for the com
ponents in FIG. 3 are employed in
4
5 ‘but
servo-mechanisms and on a channel 442 to the divider
check circuit Mill, and the remaining pulses to frequency
in larger scale and with more particularity. The central
divider 94. Pulses conveyed to frequency divider 94 are
control panel 7-4, the clock system 4.2, the automatic data 25 potential command pulses for governing the action of
supply system
and the manual data supply system
453 are represented. by separate boxes in the block dia
gram of HS. 4.
Similarly, the pulse-code-to-analog
the pulse-code-to-analog servo-mechanisms.
The potential command pulses furnished ‘by the ?rst
frequency divider 92 are delivered along the channel 168
servo-mechanism 5d and its associated power servo
in the clocl: system to the unit referred to as the start
rnotor 28 are shown in box outline in FIG. 5.
30 stop circuit 96. In general, the function of the start-stop
The several systems illustrated in PEG. 4 are inter
circuit is to control the how of potential command pulses
connected by comrnand, checking and control circuits
to the clock cycle control unit
When the machine
as indicated by the various channels running from one
is ready to operate, a signal conveyed over channel 119
to the other. The central control panel 74‘ contains con
from the control panel 74 to the start-stop circuit allows
trol elements such as push buttons and indicating ele
the ?ow of pulses on channel ‘1% to go to the clock cycle
control along channel 112. When the machine is to be
various c. other; to dit'lerent units of the several systems.
stopped, a signal from the control panel ‘74 to the start
Ce‘tain of the control elements serve to start
stop
stop circuit will shut off the ?ow of pulses from channel
The’; to channel 112.
the machine and to select either the manual or automatic
data supply systems for operation. Electric signal lamps 40
in general, the function of the clock cycle control unit
are also provided for identifying any malfunctioning of
93 in the clock system is to adjust the duration of one
ments such as electric lamps which are connected by
the machine to the ope‘ .tor.
The clock system
clock cycle to the length of the cut desired in one ma
2 includes a clock oscillator 90
which serves as the primary pulse source for the opera
tion of the cont'ol systcn. Also included in the clock i
chine cycle. The machine is preferably provided with a
choice of a plurality of ?xed clock cycles anywhere be
system are tw
'viders or pulse distributors,
tween 21 maximum duration at the nominal clock cycle
rate and a minimum duration of considerable shorter
$2 and $13.
ed to as the ?rst frequency
equency divider
it will
time. In the illustrated embodiment of the invention,
the machine has a choice of eight ?xed clock cycles ‘be
divider
i that the clock system has other op
erating e_
everal of which are interposed be
tween the two frequency dividers. These operating ele
rncnts comprise a start-stop circuit 96, a clock cycle
control 98, and a divider cneck circuit see. The main
channel is directed from the clock oscillator
through the initial or first frequency divider 92., thence
through the start-stop circuit ‘)6 and the clock cycle con~
trol 98 to the second frequency divider 9d. The design
and function of the newly cited operating elements of
Ween 2 seconds and 256 seconds in duration.
The pur
pose of providing a plurality of ?xed clock cycles is in
order to be able to adjust the cycle time long enough to
do a particular operation and thus conserve
e.
For
example, the clock cycle control unit may provide a rela
tively long cycle time for making one long straight line
cut from a single block of data on the tape.
For mak
ing shorter cuts, the clock cycle unit may provide a short
cycle time so that the machine does not consume the
maximum clock time allotted, such as 256 seconds.
The second frequency divider 94 in the clock system
the clock system are described in detail hereinafter.
The clock as
‘ 99 generates
series of pulses 60 receives its pulses from the clock cycle control over
channel 114, and functions to generate on separate lines,
which
usually
yered regularly spaced in time.
a pattern of pulses-which, in accordance with settings in
Tl ese pulses are sent out to the first frequency divider
the automatic or manual data supply system, may or may
and thereafter some of these pulses are delivered to
not be used as command pulses for the pulsc-code-to-ana
the second freque cy divider
Each pulse genera ed.
by the clock oscill, or potentially represents an instruc CD ...l log servo-mechanisms. This is explained in detail here
inafter. Those pulses which are used for command pill”~
tion to move a part of the machine one unit or" distance.
poses are transmitted over channel 78 to the automatic
in the ill ‘ated embodiment of the invention not every
and manual data supply systems. Frequency divider 94
pulse is us~..d
instruction :"sr moving a. controlled
element. Usually only a rela ...ly small number of
also generates an end carry pulse which signi?es the end
pulses gener ted within a prescribed time are utilized as
of a clock cycle. This last pulse is returned by the chan
“command” pulses as hereinafter" described. Since each
nel 116 to the clock cycle control 98 and thence from
pulse chsractcriz a In. veiuent of one unit of distrnce,
there along channel 11% to the automatic data supply
the oscillator fre ency of the pulses
be viewed as
system 4-4 where as hereinafter described it will signal
a distance per unit of time or
a velocity. The pulse
the tape reader or other data sensing means to advance
requency generated by the clock oscillator
may be
and read the next successive instruction on the tape.
3,069,608
10
9
In general, the divider checking circuit 100 in the clock
the pulses from the manual data supply system are fur
system functions to check the second frequency divider
94 and the second stage of the ?rst frequency divider
92. It serves to guard against the loss of a possible corn~
nished to the selected servo-mechanism and when ener
mand pulse and, hence, against integration errors in con
verting rate commands to position commands. If in
checking these frequency dividers, the checking circuit
50, 52 and 54.
The manual supply data system 48 includes a com
mand data converter unit 138 which functions similarly
to the data converter unit 124 to gate the desired pulse
rates from channel 78 over which the pulses from fre
gized by a signal on channel 136 the relays connect channel
134 to one or more pulse converting servo-mechanisms
100 determines there is an unaccounted or missing pulse,
it will send out an alarm pulse over channel 120 to the
start-stop circuit causing the latter to stop the flow of
potential command pulses over channel 112. The two
frequency dividers 92 and 94 may be considered together
to form a single binary frequency divider of various
stages, depending upon the setting of the clock cycle con
quency divider 94 are transmitted.
The manual com
mand data converter may comprise the bank of switches
62 previously described in connection with FIG. 1. In
the illustrated embodiment of the invention, eighteen
manually operated toggle switches are employed in the
trol.
15 bank which will accommodate command orders having
The automatic data supply system 44 as diagrammati
seventeen binary digits and the directional sense digit
cally shown in FIG. 4 comprises the tape reader 46, a
of either a plus or a minus sign. As in the case of auto
data distributor 122, a command data converter unit 124
containing banks of information storage registers as here
inafter described, and a manual-automatic control unit
126 ‘from which command pulses are delivered ‘by chan
nel 128. Since in the block diagrams of FIGS. 4 and 5
the control system is shown as governing the action of
the pulse-code-to-analog servo-mechanism ‘50 for the “X”
matic data command converter unit 124, the three com~
mand numbers for the separate axes of the machine rep
resent the position increment in each axis necessary to
move the machine from its present position to a new
position.
Each pulse-code-to-analog servo-mechanism of the il
lustrated embodiment of the invention comprises as shown
or table axis and its associated power servomotor 28, 25 in the block diagram of FIG. 5 an electrically and me
FIG. 5 illustrates these two component parts of the sys
chanically connected group of units referred to as ‘a
tem and the delivery of command pulses thereto by way
summing register 140, a decoder 142, an ampli?er servo
of channel 128. It is understood that the two remaining
motor 144, a synchro-transmitter 146, and interconnect
pulse-code-to-analog servo-mechanisms 52 and 54 and
ing servo gearing 148 between the servomotor and the
their respective servomotors 30 and 32 are similarly con
synchro-transmitter.
trolled from the data supply systems.
In addition, each pulse-code-to
analog servo-mechanism includes a feed-back mechanism
The function of the tape reader 46 or other device for
schematically shown in FIG. 5 as a position coder 150‘
sensing coded information is to convert information
and a position code converter 152. Although the servo
stored on tape to a form acceptable to the data distribu
tor 122 and the data converter 124 ‘for each axis of the 35 motor of the unit 144 may be directly connected to the
element or machine part under control, in the illustrated
machine. The reader scans the machine orders on the
embodiment of the invention each pulse-code-to-analog
information storage medium, such as the punched holes
servo-mechanism operates through a machine drive servo
in the tape, and converts the pattern of coded informa
mechanism, such as shown in block outline in the lower
tion into pulses transmitted simultaneously over a selected
combination of output lines over channel 130 and lead 40 portion of FIG. 5.
Each machine drive servo-mechanism is shown in the
ing from the tape reader to the data distributor 122.
present form of the invention as comprising a synchro
The primary function of the data distributor 122 in
receiver 154, an ampli?er and servomotor 156, and ma
the automatic data supply system is to route or distribute
chine feed gearing 158 connecting the servomotor with
the tape reader signals representing successive lines of
tape data over channel 132 to the command data convert 45 the controlled part of the machine. In addition, each
machine drive servo-mechanism includes machine data
er until 124, *where the corresponding digits of the ma
gearing generally indicated at 160 and limit stops char
chine control orders are stored. 'Its secondary functions
acterized by the box outline at 162. Synchronizing data
are to control the tape reader so that the proper number
is transmitted between the pulse-code-to-analog servo
of lines are read from the tape at the proper times, and
to signal the control circuits of the panel 74 in the event 50 mechanism and its associated machine ‘drive servo-mech
anism over channel 164.
of certain errors arising in the automatic data supply
system.
It is to be noted that command pulses delivered over
channel 128 from the automatic data supply system 44
The function of the command data converter unit 124
are directed to the summing register 140 where they are
is to control the transmission of the proper number of
control-register pulses to the separate pulse-code-to-analog
servo-mechanisms 50, 52 and ‘54. In the charted rep
resentation illustrated in ‘FIGS. 4 and 5, the control sys
tem is shown as applied to the servo-mechanism 50 for
actutaing the table 14 of the machine tool along the “X”
axis. The command data converter unit contains two
sets or banks of alternately operable registers for each
coordinate axis of the controlled machine. The pulses
desired from either bank of registers, whichever is in
operation during a particular clock cycle, are transmit
55
compared against response pulses arising out of the posi
tion code converter 152.
The channel 80 over which
synchronizing pulses are sent from the first frequency
divider 92 is connected to both the position code con
verter 152 and the position coder 1‘50.
Clock System and Control Registers
FIG. 6 illustrates a simpli?ed schematic block diagram
of the operating relation between the clock system and
the control registers of the data supply system and is
ted over channel 134 to a manual-automatic control unit 65 intended to illustrate how the instructions, whether re
126‘.
The function of the manual-automatic control unit 126
is to determine the source of command pulses for the
corded on storage medium, such as punched tape and
the like, or manually operated, are converted into a series
of pulses which serve as the input to controlled elements
selected pulse-code-to-analog servo-mechanism. The
such as the servo-mechanisms 50, '52 and 54. The basic
control unit ‘126 is actuated to feed pulses from either 70 parts of this operating relationship are embodied in four
the automatic or manual data supply systems ‘44 and 48
principal units: the master or clock oscillator 90 forming
by means of a signal sent over channel 136 from the
part of the clock system 4/2 described in connection with
central control panel 74. The manual-automatic control
FIG. 4; the pulse distributor generally referred to as the
unit 126 may include three relays, one for each axis.
?rst frequency divider ‘)2; the pulse distributor generally
These relays may be arranged so that when de-energized 75 referred to as the second frequency divider 94; a pulse
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