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Патент USA US2410295

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Oct 29, 1946-
- H. P. KUEHN! EI'AL
2,410,295
AUTOMATIC PATTERN CONTROLLED MACHINE TOOL
Fi'led Jan. 19, 1943
' 3 Sheets-Sheet 1
_
mal
Invento'r-s:
Hans P. Kuehni,
Norman 6. Bransqn.
by M5. 1M4»,
‘Thei’r- Attorney. '
Oct. 29, 1946.
H.’ P. KUEHNI ETAL
I
2,410,295
AUTOMVATIC PATTERN CONTROLLED MACHINE TOOL
Filed Jan. 19, 1943
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Inventor-s:
-Hans F2 Kuehni,
Norman G. Br-anson.
Their’ Attorney.
_ Oct. 29, 1946.
H. P. KUEHNI! EI'AL
'
2,410,295
AUTOI'ATIC PATTERN CONTROLLED MACHINE TOOL
Filed Jan. 19, 1943
3 Sheets-Shéet 3
@2
Inventor-s:
Hans F.‘ Kuehni,
Nor-man _ G. Branson,
by Their;
#64476Attorney.
M“,
Patented 0a. 29, 1945
Y ' 2,419,295v
. 7 ‘UNITED I srarss PATIENT '0 FFICE] v
2,410,295
AUTOMATIC PATTERN CONTROLLED
MACHINE TOOL '
.
Hans P. Kuehni and Norman G. Brannon, Sche
nectady, N. Y., “assilnors to General Electric
Company, a corporation or New York .
.
Application January 19, 1943, Serial No.-4'l2,840 >
.
8 Claims.
(01. 172-—239)
‘This invention relates to automatic pattern
controlled machine tools, more particularly to
control systems for such machine tools, and a
more speci?c object of the invention is the pro
vision of asimple, reliable, and improved con
trol system of this character.
~v
More speci?cally, the invention relates to autos ‘
matic pattern controlled machine tools such as
tracer device includes a magnetostrictive mem
ber, i. e., a member whose magnetic permeability
changes in response to- the application of a force
to the member. This change in- permeability of
the magnetostrictive member is utilized to pro
duce a control voltage which in turn is utilized,
‘to control the driving means inv the manner, de
scribed in the foregoing.
further object of this invention is the provision 10 In illustrating the invention in one form there
of, it is illustrated as embodied in a control sys-_
of means for eilecting a relative movement of
tem for an automatic pattern controlled metal
the cutter and work piece at a constant contour _ cutting lathe, and also in a control system for a
speed for all angles of such relative movement
polar co-ordinate type milling machine.
, milling machines, lathes, and the like,‘ and a .
so that the tool marks on the work will be evenly
a better and more complete understanding
spaced irrespective of the shape which is being 15 of For
the invention, reference may now be had to
cut.
.
'
the following speci?cation and to the accompany
The ‘relative movement of the cutter and the
ing drawings in which Fig. 1 is a simple, diagram
work piece in machineftools of this character is
matical
illustration of an embodiment of the in
controlled by means of a tracer device which is
vention as applied to a lathe; Fig. 2 is a detailed
‘maintained in engagement with the pattern as 20 sectional view of the tracer element; Figs. 3 and
it is moved along the pro?le thereof.
4 are simple, diagrammatical illustrations of the
Another object of the invention is the pro
sine and cosine regulators which constitute parts
vision of a control system for a pattern controlled
of- the control system; Fig. 5 is a chart of char
machine tool in which the two components of
acteristic curves which serve to explain the op
the relative movement of the cutter and the work 25 eration of the invention; Fig. 6 is a'diagram
piece .- are continuously correlated so that the
matical sketch which illustrates graphically the
movement is not a series of steps and a fine, step
variation of the force between the pattern and
less ?nish of the work is obtained.
' .
' the tracer finger at various angles; Figs. '7, 8, 9,
In carrying the invention into effect in one
10, and 11 are charts of characteristic curves
form thereof, means are provided for supporting '30 which illustrate the correlation oi'the speeds of
the pattern and the work piece in operative rela
the motors which produce the components of the
tionship with the tracer and cutter, respectively.
Suitable driving means controlled by- the-tracer
are provided for effecting the relative movement
relative movement of the cutter and work for the
magnitude of either, and therefore, irrespective
is a schematic diagram of an ampli?er which
constitutes an element of the system.
angles indicated in Fig. 6; Fig. 12 is a diagram
matic sketch illustrating the constancy of the
of the cutter and the work piece. This relative 35 velocity of the relative movement between the
movement of the cutter and the work piece is the
cutter and work at all angles of such relative
resultant of two angularly displaced components,
movement along the contour; Fig. 13 is a view in
_e. g.-, a longitudinal movement and a transverse
perspective illustrating an'application of the in
- movement. Means controlled by the tracer con
vention to a polar co-ordinate type milling ma
trol the driving meansso that the vector sum 40 chine; Figs. 14 and 15 are diagrammatic sketches
_ of the speeds of these two component'movements
illustrating the operation of the invention as apis approximately constant irrespective of the
plied to the milling machine of Fig. 13, and Fig. 16
- of the angle of the resultant movement. This is
accomplished by controlling the driving means in 45. Referring now to the drawings, it is desired to
response to continuous variation of the force be
turn a metallic work piece to so that the ?nal
tween the pattern and the tracer so that the
pro?le
will conform accurately 'to the pro?le of
speed of one of these components is continuously
the pattern i I. The work piece III, which may be
‘varied from a maximum value in one direction
of steel or other material, is rotated by suitable
to a maximum value in the reverse direction, de 50 driving
means about a longitudinal axis de?ned
pendent upon the magnitude of the force, and
by the lathe centers 01' which only the tail stock
the second‘ component is unidirectional and its ' center
I! is illustrated. The driving means for
speed is simultaneously varied in inverse rela-v
rotating the ‘work maybe and preferably is a
tionship to the speed of the?rst component
direct current electric motor supplied from a
In a specific embodiment of the invention, the 55 source of alternating voltage through suitable
9,410,295
3
.
electric valve apparatus which may be controlled
to adjust the speed of rotation of the work piece
to a desired value. Since'the details of this motor
and the electric valve control apparatus from
which it is supplied constitute no part of the in
vention, they are omitted from the drawings in
the interest ‘of simplicity.
The pattern II is supported by suitable means
-
4
tension of which may be suitably adjusted by
means of a threaded annular member 32, which
is in internal threaded engagement with the wall,
of the shell 23. The disk 30 is provided with an
adjustable set screw 30a.
A hollow cylindrical member 33 made of a mate
rial possessing the property of magnetostrlction,
such as nickel-steel, is arranged centrally within
the cylindrical jacket 29 and is of su?icient length
to
project through the openings 23c and 23d
10
is ?rmly clamped by suitable means such as
in the top and bottom caps 23a and 28b, respec
clamping screws M. The supporting plate l3
tively. This magnetostrlctive element is ?rmly
may be securely fastened to the bed of the lathe,
‘ illustrated as a plate ill to which the pattern II
or may be built as an integral part of the lathe.
held between the set screw 30a and the top sur
A cutter I5 is held in a tool post it which is
mounted in a compound rest comprising an upper
cross feed member l1 which is slidably mounted
on the cross feed slide of the carriage l8. The
carriage I3 is slldably mounted on ways lSa
vided with a rounded recess to receive the rounded
for longitudinal movement along the bedplate IS.
face of the horizontal flange of the tracer ?nger.
As shown, the top surface of the ?ange is pro
end of the cylindrical magnetostrictive element.
If a force is applied to the contact point 23b
of the tracer ?nger in any radial direction in a
The longitudinal movement is e?ected by means 20 plane perpendicular to the longitudinal axis of
the ?nger, a limited rotation of the ?nger 23
of a lead screw 20 and a. cooperating threaded
about a point on the seating ring 24 as a pivot
member (not shown) with which the carriage is
will result. For example, if a force f1 acting to
provided.
‘
~
ward the left is applied to the contact point 23b.
A tracer 2| is maintained in fixed but adjus
the ?nger will be given a limited rotation in a
table relationship with respect to the cutter by
means of a rigid supporting arm 22 to which the
tracer 2| is ?rmly secured and which, in turn,
is rigidly secured to the cutter supporting means,
i. e., the compound rest ll. ‘Thus the tracer 2i
and the cutter l6 are supported in operative
relationship, respectively, with the pattern 13
and work piece III.
A preferred construction of the tracer device
clockwise direction about the point 25c as a cen
ter, and the ?anged head 25a acting as a lever
will apply a force to compress the magnetostric
tive member. Likewise, if a force )‘2 acting to
ward the right is applied to the contact point 23b,
the ?nger 25 is given a limited counterclockwise
rotation about the point 2511 as a center, and the
flanged head 25a will apply a force to compress
the magnetostrictive member 33. Thus, the
2| is illustrated in Fig. 2. It comprises an outer
tracer ?nger 25 acts as a bell crank to apply a
cylindrical shell 23 which is formed of mild steel.
compressional
force to the magnetostrictive mem
The upper portion of the shell 23 is bored to have
ber 33 in response to the application of force
a larger inside diameter than the inside diameter
to the contact point 25b in any radial
of the lower portion, thereby to provide a seat for
direction in a horizontal plane. The compres
a ring 24 which is preferably made of hard tool
sion
of the magnetostrictive element is therefore
steel. A tracer ?nger 25 which is made of hard 40
independent of the direction of the force applied
tool steel and has a shape which is generally
to the tip of the tracer ?nger. In other words,
similar to that of a poppet valve is mounted within
the tracer is nondirectional. The application of
the bore of the lower portion of the shell with
a force to the magnetostrictive element e?ects a
its ?anged head bearing on the hardened seating
ring 24. The lower end of the finger 25 projects 45 change in its magnetic permeability.
Within the jacket 29 and surrounding the
through an opening in the bottom of the cylin
magnetostrictive member 33 is a coil 34 which
drical shell and is of tapering shape to provide
is wound upon a spool 35 that is preferably made
a cylindrical portion 25b which serves as the
of a suitable phenolic condensation product, such
contact point which engages the pro?le edge of
the pattern. The clearance between the ?nger 50 as Bakelite. The magnetostrictive member and
the jacket 23 form a magnetic circuit for the
and the outer shell at the bottom may be made
magnet ?ux produced by the coil. Leads 33 and
quite small, e. g., .01 inch. A second hard steel
31 are brought out from the coil through open
ring 26 rests upon the lower hard steel ring 24.
ings in the top cap 29a, the disk 30, and the disk
As indicated, the inside diameter of the ring 25
is greater than the inside diameter of the lower 55 shaped terminal bracket 33 which is clamped in
place at the upper end of the shell by means of
ring 2i so as to provide su?icientspace for the
an internally threaded clamping ring 39 which
?anged head of the tracer ?nger 25.
is in threaded engagement with the outside wall
A cylindrical spacing member 21 made of hard
of the shell 23 at the upper end thereof. The coil
tool steel is fitted within a large diameter bore
33 constitutes one arm of a Wheatstone bridge,
in the upper portion of the shell. This cylindri
the remaining arms of which comprise the resis
cal member is held ?rmly against the upper hard
tor 40 plus the portion of resistor M at the left
ened ring 26 by means of an annular member
of the slider Illa, the resistor 42 plus the portion
28 which is in threaded engagement with the
of resistor ll at the right of the slider, and the
internal wall of the shell 23.
Within the cylindrical spacing member 21 is a 65 coil 43.
A periodically varying voltage of suitable fre
clyindrical jacket 29 which may be made of any
quency, e. g., 2,000 cycles per second is supplied to
suitable magnetic material, e. g., one of the well
the opposite bridge points Ma and 4311 from an
known nickel-iron alloys such as Nicalloy or
electric valve type oscillator 44. Any suitable type
Permalloy. This jacket has a top cap 29a and a
bottom cap 29b. These caps are provided with 70 of oscillator may be used. The constructional
centrally disposed openings 29c and 29d, respec
tively.
details of the oscillatorare unimportant and the
oscillator is therefore indicated conventionally in
the drawings.
’ '
Above the screw ring 28 is a disk member 30
The Wheatstone bridge is initially balanced by
made of hard tool steel. It is ?rmly seated on
the ring 23 by means of a spring washer 3| the 76 adjustment of slider “a when no force is applied
$410,095
v5
6
to the tracer ?nger and the magnetostrictive ele
ment is prestressed. When a force is applied to
the tracer ?nger, this force is multiplied and
,
portant characteristic of this time of valve is that
when connected in series with a resistor across
a source of variable voltage, the voltage drop
across the terminals of the valve remains sub
translated into a compressional force acting on
the magnetostrictive member. The resulting
stantially constant.
change in permeability of the magnetostrictive
member unbalances the Wheatstone bridge and
Direct current power at a suitable voltage is
supplied to the power input terminals 45c and 45! p
or the cosine regulator from a suitable source
causes a periodically varying voltage to appear
across the opposite bridge points 40a and 42a. - such as the regulated power supply represented This unbalanced voltage is .applied to the input 10 by the two supply lines 45. A voltage divider com
prising ?xed resistor portions 55a, 55b, 55c, and
terminals of an electric valveltype ampli?er 45.
55d and a variable resistor portion 55s is con
Preferably the ampli?er 45 is of the type which
has a direct voltage output that is approximately . nected across the power input terminals 45¢ and
45)‘. The cathodes 52a and 52b oi.’ valve 52 and 55a
linearly proportional to the e?ective value of the
periodically varying input voltage. Direct current 15 and 53b of valve 55 are connected by means of
sliders to points on this voltage divider of pro-‘
power is supplied to the power input terminals
gresslvely increasingly positive voltage so that
45a and 45b of the ampli?er from a suitable
the left-hand conducting path of valve 52 is
source such as a regulated ‘power supply (not
biased to cutoff, and the right-hand path of valve
shown) which is conventionally indicated in the
drawings by the two supply lines 45. The circuit 20 52 and both paths of valve 55 are biased beyond
cuto? by progressively increasing amounts. The
details of this ampli?er are illustrated in Fig. 16.
grids of both valves are all connected together to
As shown the ampli?er comprises two stages of’
the input terminal 49a, and the negative terminal
voltage ampli?cation with a transformer output
of- the cathode voltage divider is connected to the
to a full wave recti?er. The ?rst stage is a'pen
tode valve and the second stage is a triode valve.
The two stages are coupled by means of capacita
input terminal 49b.
’
The anodes 52c and 52d of valve 52 and 530 and
53d of valve 58 connect through parallel adjusta
tive coupling, The A-C voltage input is supplied
ble resistors 55, 51, 55, and 59, respectively, and
to the terminals 45c, 45d and the D.-C. output
through a series resistor 50 to the anode of valve
voltage appears across the resistor between the
terminals 45c and 45!.
30 54 which is connected to the positive power input
Theirelationship between the force applied to
terminal 49c.
~
'
the tracer ?nger and the output voltage of the
The valve 54 is connected in series with a re
ampli?er 45 is illustrated graphically by the
sistor 5| across the power supply, and a_voltage
divider comprising ?xed resistor 62 and adjust
straight line curve 41 in Fig. 5, in which ordinates
represent volts and abscissae represent force‘ act 35 able resistor 53 is connected across the valve
54. The power input voltage may be any suit
ing on the tracer ?nger. This curve 41 indicates
that the direct voltage output is approximately
able value which may be assumed, for example,
to be 300 volts. Accordingly, the voltage of the
linearly proportional to the force acting on the
terminal 54a is 300 volts positive. The slider 53a
tracer ?nger.
The 'output voltage of ampli?er 45 is applied 40 is initially adjusted to a point on the voltage di
vider such that the voltage drop between termi
simultaneously to the input terminals 48a, 45b,
nal 54a and the slider is equal to the voltage
1 and 49a, 49b of two electric valve type regulators
drop produced across the resistor 50 by the com
48 and 49, respectively, which are referred to as
bined saturation currents of both conducting
the ‘sine regulator and the cosine regulator, re
spectively. The sine regulator is an electric valve
‘ paths of valve 52. Assuming this voltage drop
to be 50 volts, the slider ‘53a will be adjusted to
apparatus which has a direct voltage output which
the 250-volt point on the voltage divider 52, 53,
approximates a sine function of the magnitude
and a net voltage of 50 volts will appear across
of the direct voltage applied to its input term
the output terminals 490 and 49d when both
inals. That is to say, that as the voltage applied
to the input terminals 48a and 45b varies con 50 valves 52 and 53 are at cutoff. This is the maxi
mum positive output voltage of the cosine regu
tinuously and linearly from a minimum value to
lator and it exists when the force on the ‘tracer
.a higher value, the voltage at the output term-'
?nger is zero, as indicated by the point 5la on
inals 48c and 48d of the sine regulator varies
continuously from a minimum value to a maxi
mum value and then to a minimum value, as in
curve 5| in Fig. 5. As the force increases, the
* voltage supplied to the input terminals 49a and
Thecosine
49b increases ‘linearly and in accordance with
regulator 49 is a similar electric valve apparatus,
the direct output voltage at the output terminals
490 and 49d of which varies approximately as
a cosine function of the magnitude of the direct
voltage applied to its input terminals. Since the
input voltages of the sine regulator and cosine
curve 41. This causes the left-hand conducting
‘ - dicated by the curve ‘50 of Fig. 5.
path of valve 52 to become conducting and to
conduct an amount of current that increases as
the input voltage increases. This increasing our
rent-produces an increasing voltage drop across
resistor 50 which is in opposition to the voltage
between terminals 54a and slider 53a so that the
regulator are the output voltage of the ampli?er
voltage of ‘terminal 50a begins to decrease with
45 which is linearly proportional to the force ap
plied to the tracer ?nger, the output voltage of 65 the result that the net voltage across output ter
minals 49c and 49d decreases correspondingly.
the’ sine and cosine regulators are therefore sine
This is indicated in Fig. 5 by the negative slope
‘and cosine functions of the magnitude of this
of curve 5i between the points 5la and MD. The
magnitude of the current conducted by the left
As indicated in Fig.3, the cosine regulator com
prises a plurality of electric valves 52, 55. and 54. 70 hand conducting path of valve 52, and conse
quently, the steepness of the curve 5| between‘
Although the electric valves 52 and 53 may be of
force.
-
.
.
points 5la and Nb, depends upon the adjustment
any suitable type, they are preferably twin triode
of anode resistor 55.
.
valves of the "hard” tube type. The valve 54 is a
When the force on the tracer ?nger increases
cold cathode type diode valve containing a small
amount of an inert gas such ‘as neon. The im 75 to the value b and the input voltage increases to
2,410,998
V
a value corresponding to the height of curve II
at point "I: in Fig. 5, the current in the left
hand conducting path ‘01 valve 52 reaches sat
nation. and the voltage across output terminals
“c and “d is decreased to the value indicated
by point lib on curve II. At this point, the
rlghtdiand path of valve 52 becomes conducting.
As the force on the tracer ?nger increases be
yond the value b, the right-hand path of valve
.
‘r8
.
their Junction point Ila is connected to the posi
tive power input terminal 48c.
'
.
'
when both valves are at cutoi! the voltage dif
terence across the output terminals is zero. How
ever, as the force on the tracer ?nger is increased
from zero, the voltage from ampli?er ll is ap
plied to the input terminals "a and no, and
the left and right-hand paths of valve ll be
come successively conducting and produce volt
ll conducts an increasing amount of current with 10 age drops across resistor ll so that a net volt
the result that the voltage drop across the re
age appears across the output terminals llc and
sistor 8| is iurther increased until the saturation '
lid. The portion of the curve ll between zero
point is reached, which occurs when the force on
and "b represents theoutput voltage as the
the tracer ?nger has a value corresponding to
iorce increases from zero to the value b, and the
the dotted line 0, Fig. 5. At this point, the‘volt 15 portion of the curve between the points at and
age drop across resistor ill is equal to the volt
5,00 represents the output voltage as the force in
age drop between terminal "a and the slider» 83a
creases from b to c. As the force increases be
with the result that the net voltage across the
yond the value c both paths of valve I! become
output terminals llc and lid is zero, which con
successively conducting and produce a voltage
dition is represented‘in Fig. 5 by the curve ,5! 20 drop across resistor 89 which is in opposite sense
crossing the zero axis at'point llc. The slope
to the voltage drop across resistor I8. and there
oi‘ the curve 5| between points lib and Sic is.
fore. decreases the net voltage at the output
made greater than the slope between 51a and Bib
terminals. The portion of curve 50 between
by adjusting the'resistor 51 to a lower value than
points 500 and 50d represents the output voltage
resistor ll.
25 as the force increases from value c to value d,
As the force on the tracer ?nger is increased
and the portion between the points 50d and He
beyond the value c, the left-hand and right
represents the output voltage as the force iii
hand paths of valve 58 are successively rendered
creases from value d to value c.
conducting, and the voltage drop across resistor
‘Thus the force on the tracer ?nger increases
80 is correspondingly increased with the result 30 linearly from zero, the output voltage of the
that the terminal 80a becomes more negative
cosine regulator it varies continuously from a
than the slider 83a, thereby reversing the po
maximum positive value to a maximum negative
larity ol'the voltage across the output terminals.
value, and the magnitude or the output ‘voltage
With increasing force on the tracer ?nger the‘
of the sine regulator 48 is simultaneously varied
output voltage takes on the successive values in 35 continuously but inversely to the magnitude of
dicated by the negative half of curve 5| until at
the output voltage 01' the cosine regulator. How
a force corresponding to dotted line e, both con
ever, the polarity of the output voltage of the
ducting paths of valve 51 are saturated and the
sine regulator does not change.
voltage drop across resistor 60 is twice the volt
The transverse movement or the cutter i8 is
age drop between terminal 54a and slider 63a, 40 effected by means or an electric motor 10, the
so that the net voltage across the output termi
drive shaft of which is connected to the cross
nals 49c and 49d is equal in magnitude and op
slide ll of the lathe through suitable driving con
posite in polarity to the maximum positive volt
nections illustrated as comprising worm gearing
age. This maximum negative voltage is repre
H, shaft 12, bevel gearing ‘l3, and a lead screw
sented in Fig. 5 by the point 5le, the ordinate
of which is equal to but opposite in sign to the
Although the motor Til may be of any suit
ordinate of the point iila which represents the
able type, it is illustrated as a split series ?eld
maximum positive voltage. Thus it is seen that
direct current motor. Power is supplied to the
by proper adjustment oi! resistors 56, 51, 5B, and
motor "i0 from a suitable source of single phase
II. the voltage output of the cosine regulator is
alternating voltage which is represented by the
caused to approximate a true cosine function of
two supply lines 15 through a transformer 18
the magnitude 0! the force applied to the tracer
and suitable electric valve apparatus comprising
?nger; ‘1A closer approximation, if desired, can
the thyr'atron valves ll and ‘i8. These two valves
be obtained by increasing the number of valves.
‘l1 and ‘iii are connected as half-wave recti?ers
Thei sine regulator 48 is similar in most re
and individually supply voltage to the motor
spects' to the cosine regulator. It comprises two
through one or the other of the split ?eld wind
electric valves 64 and 85 which are identical with
ings ‘Illa or 10b to effect rotation of the motor
valves 52 and SI of the cosine regulator. The
in the forward or reverse direction as required.
grids of both valves are connected together to
The anodes 11a and 18a of thyratrons Ti and ‘ID
the input terminal 48a. A voltage divider com 60 are connected through the field windings 70a
prising ?xed resistors 66a, 66b, 56c, and 56d and
and ‘(0b in parallel and through the armature
adjustable resistor tie is connected across the
of motor 10' to the right-hand terminal of the
power input terminals lie and 48!. The cath
secondary winding of transformer 16, and the
cathodes Tlb and 18b are connected to the left
odes Na, 84b, 85a, 85b are connected to points
hand terminals of the secondary winding. A
on the voltage divider of progressively increas
pair of resistors 19 and 80 is connected in series
ingly positive voltage, so that the left-hand con
relationship with each other across the control
ducting path of valve 84 is biased to cutoff and
grids 11c and lie, and the junction point 19a
the right-hand path and both paths of valve 65
of these two resistors is connected through the
are biased beyond cutoii' by progressively increas
70 active portion of a potentiometer resistor 8| be
ing amounts. The anodes 64c and Bid or valve
tween the terminal 19a and the slider 8|a to the
64 are connected to output terminal 48c, and the
cathodes 11b and 181). A periodically varying
anodes 85c and 65d are connected to output ter-.
voltage is supplied from a source 82 through a
minal “it. Two resistors 58 and 69 are con
phase shifting bridge network to the potentiom
nected in series across the output terminals and 75 eter Bi and thence to the control grids lie and
2,410,296
9
‘m. The source’ "may be and-preferably is v
the same source, as the source ‘I! to which the
anodes are connected. As shown, the phase shift
ing bridge network'comprises the opposite halves
of the secondary winding of the transformer 83,
the adjustable resistor 8.4, and the capacitor 85.
By suitably adjusting the resistor 84, the alter
nating component of voltage supplied to the con
trol grids may be dephased with respect to the
. anode voltage. Preferably the resistor “is ad
Justed-so that the alternating voltage supplied to
the control grids is dephased from the anode
voltage by approximately. 90 degrees lagging, with
‘1o
1
,
For the purpose of accurately regulating the
speed 01' motor ‘III to a value correspondingto the
instantaneous magnitude of the output voltage
of the cosine regulator, means are provided for
supplying to the grid circuit 01' the ampli?er valve
86 a signal voltage‘which is proportional to the
‘speed oi“ the motor 10 and opposite in polarity to
the voltage supplied from the cosine regulator.
This signal voltage is provided by means of a
10 tachometer generator 89 which is driven by mo~
tor ‘Ill and generates a voltage which is linearly
proportional to the speed of motor 10. This sig
nal voltage is applied across a resistor 90‘ in the
the result that the thyratrons Ti and ‘I8 conduct
grid circuit oi’ ampli?er valve 86 so that it op
only during a small portion oi’ the positive halt 15 poses
the voltage supplied from the cosine regu
cycle of the voltage applied to the anodes 11a
lator,
and
the di?erence of the two voltages is the
. ‘
and ‘Ila.
effective control'voltage on the grid of the am
For the purpose of amplifying, the 'direct volt
pli?er valve. The tendency of this feedback cir
age output of the cosine regulator, a suitable am
cuit is to regulate the signal voltage to the output
pliiier comprising a-\tw‘in triode valve 86 is pro 20 voltage of the cosine regulator.‘ In other words,
vided. Power is supplied to the power input ter
it maintains the signal voltage approximately
minals 88a and 86b of this ampli?er from a suit;
equal
to the output voltage of the cosine regulator.
able independent D. C. source. The control grids I ‘Since the signal voltage is linearly proportional
of this ampli?er are biased to provide push pull - to the speed oi’ motor 10, an equilibrium condi
class A operation with both paths of the valve 25 tion is reached when the dlil'erence of the two
conducting equal amounts of current through re
voltages is just suiilcient to cause the motor 10
sisters 81 and 88. when a voltage’ is supplied
to operate at a speed which accurately corre
from the cosine regulator to the grids of valve
sponds to the magnitude of the output voltage of
88, one path is caused to conduct more current - the cosine regulator. Since the output voltage oi
than the other, depending upon the polarity of 30 the cosine regulator is a cosine function of the
- the voltage from the cosine regulator with the
magnitude of the force applied to the tracer
result that the voltage drop across one of the ' finger, .the speed oi‘ the motor ‘Ill ‘will also be a
resistors 81 and 88 is increased and the voltage
cosine function or the magnitude of this force.
drop across the other is decreased. As a result,
The longitudinal feed lead screw is driven by a
a direct current voltage'component in the posi 35 motor’
9| which is controlled to operate. at a
tive direction is applied to the grid of one of
speed which is proportional to the magnitude of
the thyratrons. This direct current component
the output voltage of the sine regulator 48 by
adds to the alternating current component sup
means of electric valve apparatus shown within
plied to the grid in such a direction as to have
the dotted rectangle 92, This apparatus is iden
the e?ect of advancing the phase of the grid 40 tical
with the electric valve apparatus which con
voltage thereby to render the thyratron conduct_
trols the cross feed motor 10, and accordingly. a
ing by an amount proportional to the magni
repetition of the description and operation of this
tude of the voltage supplied from the cosine reg
electric
valve apparatus is omitted. The tech
ulator to the ampli?er valve 86. At the same
ometer generator 93 performsthe same function
time, a direct current component is supplied to
in regulating the speed of the longitudinal feed.
the control grid 01' the other thyratron in such a
9| that is performed by tachometer gen
direction that it further retards the phase of ‘ motor
erator
89
in regulating the speed of the cross feed
the grid voltage, and thus the thyratrons 11 and
drive motor 10.
'18 are selectively energized to e?'ect rotation of
A voltmeter 84 is connected across the output
motor ‘Iii in one direction or the other depending .
terminals
oi’ the ampli?er 45. The scale of this
upon the polarity of the output voltage of the
meter is so calibrated that each graduation cor
cosine regulator. In the circuit shown whenthe
responds to .00005'inch de?ection of the tracer
output terminal 49c oi’ the cosine-(regulator is
?nger. The meter can thus be used as a very ac
positive, the thyratron Tl is energized and that
curate gauge for electrical adjustment of the
current is supplied to the motor "H3 in such a ,
direction for example as to cause the tool [5
to be moved inward toward the work piece 10.
cross feed of the compound rest for taking ?nish
cuts. Since it is possible to estimate fairly ac
curately one-halt the. distance between scale
Conversely, when the output terminal 49d of
the cosine regulator is positive. the thyratron
graduations. the cross feed can be adjusted‘ to
within .000025 inch of a desired position. This
'18 will be energized and the motor 10 will be 60 degree of accuracy exceeds by a wide margin that
caused to rotate in a direction to withdraw the
obtainable by means otthe usual mechanical
tool l5 from the work. The rotational response
scales on, the cross feed adjustment of a lathe‘.
may be reversed by means of a switch in lines
The electrical adjustment consists in shifting the
49c, 49d as required.
7 bridge balance the desired degree by means oi’ the
The ampli?cation ratio oi’ ampli?er 86 is such
65 potentiometer 4|. Also, the voltmeter 94 serves
that a very small voltage; e. g., one volt across
_ as an extremely accurate measuring device in set
the output terminals of the cosine regulator- will
fully advance the phase oi’ the grid voltage of
one or the other of the thyratrons ‘I1 and 18. As
a result, the active thyratron tends to supply a
current to the armature of the motor ‘III which is several times full load value. This would tend
oi’ course to accelerate the motor 10 to maximum '
' speed for any output voltage of the cosine regu
lator in excess of one volt.
'
.
ting up a templet on the templet supporting
plates. Any lack of parallelism between the ion
gitudinal edge, of the templet and'the center axis
of the lathe and the amount 01 such divergence is
readily indicated on the meter byv moving the
tracer?nger along the longitudinal edges oi’ the
template with no work piece in the lathe.
With the foregoing understanding of the ele- '
75 merits and their organization in the system, the
‘
2,410,295
11
operation of the system will readily be under—
stood from the following detailed description.
It may be assumed that the tool and tracer are
in position for starting a out. In other words, the
.
12
teed motor 8 I. When the tracer point has moved
through 45 degrees of are along the semicircular
edge l3b, the force exerted on the tracer ?nger,
attains the magnitude indicated by the dashed
line b’ in Fig. 9, with the result that the cross
feed motor 10 and longitudinal feed motor 9|
operate at equal speeds as indicated in Fig. 9 by
the intersection of the sine curve and cosine curve
matic view of the portionof the pattern consti
on the dashed vertical line b’. Since the speeds
tuting the longitudinal edge i311 and the semicir
cular edge I311. The tracer point 251) is in the 10 of both motors are equal, the tracer point and
the cutter 15 will have a direction relative to the
position indicated in Fig. 6, and the tool I5 is in a
pattern and work piece, respectively, which is at
corresponding position with respect to the work
an angle of 45 degrees to the horizontal edge Ilia
piece ID.
as indicated by the arrow 91?) in Fig. 6.
The system is energized by closing the switches
When the tracer ?nger reaches a position hali
95, 96, and 91. Although the switches are illus
way along the semicircular curve l3b, the Iorce
trated as simple manually operated knife
on the tracer ?nger represented by ‘the vector
switches, it will be understood of course that
tracer point 25!) will be withdrawn from the lon
gitudinal edge l3a at the left of the pattern,
as indicated in Fig. 6 which is an enlarged sche
they may be remotely controlled electromagnetic
86c again increases to the value represented by
the dashed line c’ in Fig. 8 which is the same
contactors. When the tracer point 25b is in
value of force that was exerted on the tracer
the position illustrated in Fig. 6, no force is ex
?nger when it ?rst came into contact with the
erted on the tracer ?nger. Since, when no force
longitudinal edge 13a. As a result, at this point
is exerted von the tracer finger. the output volt
the tracer ?nger and the cutter are moved in a
age 01' the cosine regulator is maximum and
longitudinal direction with no component of
the output of the sine regulator is zero, as indi
transverse motion as indicated by the dotted
cated in Fig. 5, the cross feed motor 10 which
arrow Slain Fig. 6.
is controlled by the cosine regulator will advance
As the tracer ?nger 25b moves beyond the
the tool toward the work piece and at the same
midposition on the semicircular curve in Fig. 6,
time advance the tracer ?nger toward the tem~
the force on the tracer ?nger is increased be
plot at maximum speed, as indicated by the
dotted arrow- associated with the tracer point 30 yond the value indicated by the vertical line 0'
because the longitudinal feed motor 91 tends to
25b in Fig. 6. The output voltage of the sine
keep forcing the tracer ?nger against the semi
regulator being zero, the longitudinal feed m0
circular edge l3b and the speed of the cross feed
tor 9| will be at rest and there will be no com
motor is zero. But,“ as the force increases be
ponent of longitudinal movement of the tool.
yond the value indicated by the dashed line 0’,
This relationship of the speeds of the cross feed
the output voltage of the cosine regulator passes
motor 10 and the longitudinal teed motor Si is
through zero and the polarity of the voltage re
indicated in Fig. 7.
verses, with the result that the cross teed motor
When the tracer point 25!) engages the edge
‘Hi rotates in the reverse direction to withdraw
l3a oi the pattern, a force is exerted on the
tracer ?nger and this force quickly builds up to 40 the tracer ?nger and the cutter.
This reverse component of the cross feed mo
the value indicated by the dashed line 0' in Fig.
tion produced by the reverse rotation of the cross
8, and the magnitude of this force is also indi
feed motor combined with the longitudinal com
cated by the vector 95a in Fig. 6. As indicated
ponent produced by the longitudinal feed motor
in Fig. 8, when a force of this magnitude is apcauses the tracer and the cutter to follow a path
plied to the tracer ?nger, the output oi! the cosine
along the semicircular edge [3b between the po
regulator decreases to zero and the output of the
sitions indicated by the vectors 96c and 96d in
sine regulator increases to a maximum, with the
Fig. 6.
result that the speed of the cross feed motor is
At the 45-degree position represented by the
decreased to zero and‘ the speed of the longi
tudinal feed motor 9! is increased to maximum. 50 position of the vector 96d, the force on the tracer
?nger attains a value indicated by the magnitude
This results in moving the tracer ?nger in a
of the vector 96d which corresponds to the mag
longitudinal direction with zero component of
nitude‘ of the force indicated by the dashed line
transverse motion as indicated by the dotted
(1’ in Fig. 10, with the result that the cross feed
arrow 91a. Simultaneously of course the cutter
motor ‘Ill and the longitudinal feed motor SI
I5 is moved along the work piece in the same
operate at speeds represented by the intersec
direction.
tion of the dashed line (1' with the sine and cosine
As the tracer point 25b begins .to move out of
curves. In other words, the speeds of both mo
engagement with the edge 13a of the pattern at
tors will be equal and the cross feed motor ‘Ill
the corner Hit), the force on the tracer ?nger
decreases at a rapid rate with the result that 60 will be rotating in the reverse direction, i. e.,
the direction to withdraw the tracer ?nger and
the speed of the cross feed motor 10 is rapidly
the tool. The results of these two components
increased to maximum and the speed of the
will produce a resultant relative movement of
longitudinal feed motor BI is rapidly decreased
the tracer point and pattern indicated by the
to zero. This causes the tracer point to advance
dotted arrow 91d and will of course also produce
inwardly along the semicircular edge lib oi’ the
a corresponding relative movement between the
pattern as illustrated by the dotted line 98 which
cutter and the work piece.
_
indicates the path of movement of the center of
As the tracer point approaches the corner lid,
the tracer point. The cutter is of course main
the component of movement produced by the
tained in a corresponding position with respect
to the work piece.
'
70 cross feed motor can no longer relieve the force
on the tracer ?nger, and consequently, this force
As the tracer finger 25b is moved inwardly
continues to increase until when it attains a
along the semicircular curve Hi), the force on
magnitude represented by the vector 96c and by I
the tracer ?nger again increases linearly, there
the position of the dashed line e' in Fig. 11, the
by decreasing the speed of the cross teed motor
‘HI and increasing the speed of the longitudinal 75 speed of the longitudinal feed motor 9| is de
2,410,295
creased to zero and the speed or the ‘cross feed
motor 10 is increased to a maximum in the re
verse direction as indicated by the intersection
of the dashed line c’ with the sine and cosine
curves. As a result, the tracer point‘ and‘ the
tool will be withdrawn at’maximum speed.
.
14
“3 through suitable worm gearing III. This
component of the relative movement of the cut
ter and work piece represented by the vector V'c
‘ in Fig. 14 corresponds to the transverse compo
nent of the relative movement produced by the
cross teed motor ‘ID in the system of Fig. 1.
However. as the tracer point tends to ride of!
The table NH and the pattern supporting spin
the edge of the templet at, the corner l3d, the
dle I03 are driven in synchronism with each other
force on the tracer-?nger decreases. rapidly to
by means of an electric motor “5 to the drive
the value indicated by the position of the dashed 10 shaft or which the table and the spindle are
line 0' in Fig, 8,-with the result that the tracer
respectively connected through suitable worm
?nger and cutter are moved in a longitudinal
gearing Hi and worm gearing“ H ‘I which have
.direction with no component of transverse mo!
the same ratio. The component of relative move
tion as indicated by the intersections of the
ment between the cutter and the work piece pro
dashed line 0' with the sine and cosine curves 50' 15 duced by the motor I I 5 and represented by the ,
and 5|’ in Fig. 8'. Thus, the relative movement
of the cutter and work piece is controlled to
follow a path corresponding to the contour of
the pattern.
.
vector V'r. corresponds to the longitudinal~ com
ponent of movement produced by the longitudi
nal feed motor 9| in Fig. 1.
-
~
The cross feed motor “3 and the longitudina
Thus, the relative movement of the cutter 20 or rotary i'eed motor H5 are controlled by means ,
of electric valve apparatus (not shown) which
responding to the- contour of the pattern.
is identical with the electric valve apparatus of
The constancy of the ‘magnitude of the veloc
Fig. 1. In other words, the motors H3 and H5
ity V of the relative movement of the cutter
replace the motors ‘l0 and 9|, respectively in the
and workpiece for all cutting angles on the con 25 control system of Fig. 1.
tour is illustrated in Fig. 12 and is explained
I The operation or the apparatus of Fig. 13 when
mathematically as follows: The relationship be
translated into terms describing milling ma
tween the sine and cosine functions of a variable
chine operation instead of lathe operation is in
quantity such as an angle is de?ned for all
all material respects identical with the opera
‘values of the angle by the equation: _
30 tion of the system of Fig. 1, and a repetition of
and work piece is controlled to follow a path cor
(1) sin=+cos’=1, or
.
‘such operation is omitted.
Although in accordance with the provisions
(2) \/sin’+cos==1, which is a constant.
of the patent statutes this invention is described
Since the velocity of the longitudinal components
as embodied in concrete form and the principle
VL is always proportional to the sine function of 35 thereof ‘has been described, together with the
the magnitude of the force F on the tracer ?n
ger and the velocity of the transverse component
V1‘ is always proportional to the cosine function
of-the magnitude of the force F, therefore,
(3) \/Vz.2+Vc==a constant, and since the re
sultant velocity V=\/Vr.=‘+Vc’, therefore V equals
a constant.
best mode in which it is now contemplated. ‘
applying that principle, it will be understood
that the apparatus shown and described is merely
illustrative and that the invention is not limited
40 thereto, since ‘alterations and modi?cations will
readily suggest themselves to vpersons skilled in
the art without departing from the true spirit
In other words, the velocity V of the relative
movement of the cutter and work piece is con
stant for all angles'oi such movement along the
path of the contour of the work piece.
In Fig, 13 which illustrates an application of
the invention to a polar .co-ordinate type milling
a movable element having an initial position, a
machine, the work piece I00, which is illustrated
pair of members, a separate driving means for
of this invention or from the scope of the annexed
claims.
‘
'What we claim as new and desire to secure"
by Letters Patent of the United States is:
1. A control system comprising in combination,
as a cam, is mounted on a rotating tablellll 50 each or said . members and means responsive
The milling cutter Hi4 together with its driving
to a continuously increasing displacement of said
element from said initial position for producing
a linearly varying voltage, means for deriving
motor I05 are mounted on a head I06 which, in
from said voltage two inversely varying control
and the pattern H12 is secured to a frustum
' shaped spindle £03.
turn, is slidably mounted in ways lli‘la built in 55 voltages, means responsive to one or said in
versely varying voltages for energizing one of
the crossrail 181. In many types of milling ma
chines, the cross rail is slidably mounted on up—
rights to provide for elevation, but in the simple
milling machine illustrated, the crossrail is ?xed
ly secured to an upright I08 which preferably is
formed integral with the bedplate [09. The tra
said driving means to eiIect a component of rela
tive movement of said members with a velocity
that varies continuously from a maximum value
in one direction to a maximum value in the
reverse direction and means responsive to_the
cer ?nger H0 is ?xedly mounted on- the crossrail
I01, and a manually rotatable lead screw Ill
serves to position the head I06 along the ways
other of said inversely varying voltages for ener
gizing the other of said driving means to- effect
to provide for initial adjustment of the distance
between the milling cutter and'the tracer ?nger.
The table _|lll and spindle I03 are rotatably
mounted on a platen I H which is slidably mount- _
ed on the slide I091: with which the bedplate I09
' is provided.
“ an angularly displaced‘ component of relative
movement of said members ‘with a velocity that
e ‘ varies continuously from a minimum value to a
‘maximum value and from said maximum value
to a minimum value.
,
. 2. A control system comprising in combina
70 tion. a movable element having an initial posi- ~
Movement of the platen in ‘together with the
rotating table l_0l which supports the work piece
_tion, a pair of members, means responsive to a
and the spindle I03 which supports the pattern 7
.is e?ected by means of a lead screw (not shown)
‘ment from said initial position for producing a
continuously increasing displacement of said ele
voltage that varies substantially linearly with said
which is driven by means or an electric motor 76 displacement, electric ‘valve means ior deriving
2,410,295
15
y
from said voltage a ?rst control voltage that
16
varies from a positive maximum to a negative
maximum and a, second control voltage that
simultaneously varies from a minimum value to
a maximum value and from said last mentioned
maximum value to a minimum value, and driv
ing means responsive to said ?rst and second
force to said element, means responsive to the
resulting change in permeability of said element
for producing a continuously variable voltage,
means for deriving from said variable voltage two
inversely varying control voltages and means re
sponsive to said inversely varying voltages for
effecting operation of said driving means at in
control voltages for effecting relative movement
versely varying speeds. '
6. A control system comprising in combina
of said members with a velocity having a com‘
ponent that varies from a maximum value in one 10 tion, a magnetostrictive control element, a pair
direction to a maximum value in the reverse
of electric motors, means for applying a variable
direction and an angularly displaced inversely
‘force to said element, means responsive to the
varying component,
3. A control system comprising in combination,
a movable control element having an initial posi
tion, a, pair of driving means and means respon~~
sive to a continuous displacement of said control
resulting change in permeability of said element
for producing a continuously variable control
15 voltage, means for deriving from said voltage two
element from said initial position for producing
a voltage which varies approximately linearly
with said force, means responsive to said voltage
for producing a first control voltage which varies
from a positive maximum to a negative maxi
mum, and a second control voltage that varies
simultaneously from a minimum value to a maxi
continuously and inversely varying control volt
ages, and means controlled by said inversely
varying voltages for operation of said motors at
speeds that vary inversely with respect to each
other as said force is continuously varied.
7. A control system comprising in combina
tion, a magnetostrictive control element, a pair
of electric motors, means for applying a variable
force to said element, means responsive to the
mum value and from said last mentioned maxi 25 resulting change in permeability of said element
mum value to a minimum value, means responé
for producing a direct control voltage that varies
sive to said ?rst control voltage for energizing
substantially linearly as said force varies, means
one of said driving means to operate at a speed
for deriving from said voltage a ?rst control
that varies continuously from a maximum value
voltage that varies continuously from a maximum
in one direction to a maximum value in the re 30 value of one polarity to amaximum value of the
verse direction and means responsive to said
opposite polarity and a second control voltage of
?xed polarity that varies inversely in magnitude
with respect to said ?rst control voltage, and
speed that varies inversely with the speed of said
means controlled by said derived ?rst control
first driving means.
‘
35 voltage for effecting operation of one of said
motors at a speed that varies continuously from
4. A control system comprising in combination,
second voltage for energizing the other of said
driving means to operate in one direction at a
a magnetostrictive control element, a pair of
driving means, means for applying a force to said
a maximum value in one direction to a maximum
value in the other direction.
'
8. A control system comprising in combina
element, and means responsive to the resulting
change in permeability of said element for pro 40 tion, a magnetostrictive control element, a pair
ducing a voltage that varies approximately
of electric motors, means for applying a force
to said magnetostrictive element, means respon
linearly with said force, and electric valve means
sive to the resulting change in permeability of
for deriving from said voltage a ?rst control
voltage that varies continuously from a positive
said element for producing a voltage that varies
'' continuously as said force varies, electric valve
maximum value to a negative maximum value
means for deriving from said voltage a ?rst con
and a second control voltage that simultaneously
trol voltage that varies continuously from a maxi
varies from a minimum value to a maximum
mum value of one polarity to a maximum value
value and from said last mentioned maximum
of the opposite polarity and a second control
value to a minimum value, and means respon
voltage of unchanging polarity that varies in~
sive‘to said control voltages for effecting opera
versely in magnitude with respect to said ?rst
tion 01' one of said driving means at a speed that
varies continuously from a maximum value in
one direction to a maximum value in the reverse
. direction and simultaneous operation of the
other of said driving means in one direction at a
speed that varies inversely with respect to the
speed of said ?rst driving means as said force is
continuously varied.
5. A control system comprising in combina
tion, a 'magnetostrlctive control element, a pair 60
of driving means, means for applying a variable I
derived control voltage as said force varies con
tinuously, and means individually responsive to
each of said derived control voltages for effect
ing operation of each of said motors correspond
ing in speed and direction to the magnitude and
polarity respectively of a diilerent one of said
derived control voltages.
HANS P. KUEHNI.
NORMAN G. BRANSON.
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